U.S. patent number 3,609,316 [Application Number 04/640,571] was granted by the patent office on 1971-09-28 for composite mixture batching.
This patent grant is currently assigned to Pedershaab Maskinfabrik A/s. Invention is credited to Noel M. H. Brosset, Johan Winther.
United States Patent |
3,609,316 |
Brosset , et al. |
September 28, 1971 |
COMPOSITE MIXTURE BATCHING
Abstract
The present disclosure is directed to a method of using an
analogue computing device for proportioning a plurality of
components of a batch mixture in obtaining a composition exhibiting
desired physical properties.
Inventors: |
Brosset; Noel M. H. (Le
Vesinet, FR), Winther; Johan (Bronderslev,
DK) |
Assignee: |
Pedershaab Maskinfabrik A/s
(Bronderslev, DK)
|
Family
ID: |
8609298 |
Appl.
No.: |
04/640,571 |
Filed: |
May 23, 1967 |
Foreign Application Priority Data
Current U.S.
Class: |
700/239; 235/69;
708/800; 700/265 |
Current CPC
Class: |
G05D
11/133 (20130101); G06G 7/75 (20130101); B28C
7/0418 (20130101); G06G 3/00 (20130101); G05D
11/134 (20130101) |
Current International
Class: |
B28C
7/04 (20060101); G06G 7/00 (20060101); G06G
3/00 (20060101); B28C 7/00 (20060101); G05D
11/00 (20060101); G05D 11/13 (20060101); G06G
7/75 (20060101); G06g 007/12 () |
Field of
Search: |
;235/151.2,184,185,150.2,179 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Morrison; Malcolm A.
Assistant Examiner: Wise; Edward J.
Claims
I claim:
1. A method of proportioning a plurality of components of a batch
mixture comprising at least a first, a second and a third
component, and in which mixture a first physical property is
determined by the ratio between the first and the second component,
and a second physical component, comprising the steps of using an
analogue computing device, producing an analogue value with said
computing device corresponding to the total amount of a batch,
dividing said total analogue value into mutually adjustable
portions corresponding to analogue values of each of the three
components, adjusting a portion of said total analogue value which
represents the sum of said first and said second component first,
to such predetermined ratio between the two analogue values which
correspond to the desired first physical property with said ratio
made readable, retaining said mutual adjustment and the ratio
between the analogue value which represents the third component,
adjusting the sum of the analogue values which represent the first
and the second components until a reading indicates such analogue
value of said second component which corresponds to said second
physical property by means of an indicator, reading out the three
analogue values and mixing the batch according to said
readings.
2. A method as claimed in claim 1, in which a fraction of the
second component is included in the third component, comprising the
steps of measuring the amount of said second component which is
included in said third component, using an analogue computing
device with an adjustable correction device operatively connected
with the means for dividing the total analogue value in portions
corresponding to the analogue values of said second and said third
components, and programming said correction device to decrease the
analogue value of said second component to be read out with the
amount of said second component which is contained in said third
component.
3. A method as claimed in claim 1 for proportioning a batch which
in addition to the three components comprises a further group of
components which are desired to be mixed in the batch in mutual
predetermined proportions as well as in a predetermined ratio
relative to the entire amount of the mixture, comprising the steps
of first proportioning the components of said second group in
predetermined ratio by percent by dividing an analogue value which
represents a unit measure into desired proportion between the
components of said second group, thereafter adjusting said analogue
value which represents said second group to such a ratio to the
analogue value which determines the entire amount of the batch
which corresponds to the desired proportion between the total
amount of the components of said second group and the entire batch
amount, and after adjustment of the analogue values of said first,
second and third component in accordance with the desired physical
properties, using all the analogue values for proportioning the
batch.
4. A method as claimed in claim 3, in which the dispensing of the
components is controlled by producing by means of a dispensing
device, an analogue value which increases as the dispensing
proceeds, comparing the analogue value produced by the dispensing
device with the analogue value which is derived from the analogue
computing device and is indicative of the amount of the component
to be dispensed, and interrupting the dispensing when the analogue
value produced by the dispensing device has been increased to the
value of the other analogue.
5. A method as claimed in claim 4, in which a third analogue value
is produced which is near to but smaller than the analogue value
which is indicative of the amount of the component to be dispensed,
and in which the analogue value produced by the dispensing device
is first compared with said third analogue value and upon becoming
equal therewith, the dispensing device is controlled to decrease
the rate of dispensing.
6. A method of proportioning a concrete batch containing cement,
water and gravel, the cement and water being present in a
predetermined ratio which detemines the strength, and the water
being present in a predetermined amount which determines the slump,
by using an analogue computing device which has means for producing
an analogue value corresponding to the desired total amount of the
batch and dividing said total analogue value in portions which
represent each of the components, comprising the steps of first
adjusting one analogue value which represents the sum of the
amounts of water and cement in a desired ratio between cement and
water corresponding to the desired strength of the concrete and
indicating said ratio, thereafter adjusting the ratio between the
analogue value which corresponds to the amount of gravel and the
sum of the analogue values which represent water and cement without
changing the first adjustment until a predetermined amount of water
which corresponds to the slump can be read out of the computing
device and thereafter using the analogue values of the three
components adjusted in this manner for proportioning the batch.
7. A method as claimed in claim 6, in which the gravel contains an
amount of water, comprising the steps of measuring the water
contents in the gravel and using an analogue computing device which
when operatively connected with the means for producing analogue
values corresponding to water and gravel includes a correction
device and adjusting said correction device to decrease the
analogue value which corresponds to water with that amount of water
which is included in the gravel.
8. A method as claimed in claim 6, for proportioning concrete which
in addition to cement, water and gravel comprises a skeleton having
a different modulus aggregate to be used with desired ratio between
the different modulus aggregates and with a desired ratio between
the total aggregates and the total amount of the mixture,
comprising the steps of dividing an analogue value which represents
a unit amount into portions which represent each of the modulus
aggregates by percent, adjusting said analogue value to a desired
ratio relatively to the analogue value which represents the entire
amount of the mixture to the desired ratio between the amount of
skeleton and the total amount of the mixture and after having
divided the remaining amount of the analogue value into portions
which correspond to analogue values of cement, water and sand to
give the desired physical properties using all the analogue values
for proportioning the mixture.
9. A method as claimed in claim 6, in which the dispensing of the
components is controlled by producing, by means of the dispensing
device, an analogue value which increases as the dispensing
proceeds, comparing the analogue value produced by the dispensing
device with the analogue value which is derived from the analogue
computing device and is indicative of the amount of the component
to be dispensed, and interrupting the dispensing when the analogue
value produced by the dispensing device has been increased to the
value of the other analogue.
10. A method as claimed in claim 9, in which a third analogue value
is produced which is a fraction smaller than the analogue value
which is indicative of the amount of the component to be dispensed,
and in which the analogue value produced by the dispensing device
is first compared with said second analogue value and upon becoming
equal therewith, the dispensing device is controlled to decrease
the rate of dispensing.
11. An analogue computing device for proportioning a plurality of
components of a batch mixture, comprising at least a first, a
second and a third component, and in which mixture a first physical
property is determined by the ratio between the first and the
second component and a second physical property determined by the
amount of the second component, comprising means for producing an
analogue value which corresponds to the entire amount of the batch,
means for dividing said total analogue value into a first fraction
which represents the analogue value of the sum of the two
components, the ratio between which determines the first physical
property and a second fraction which corresponds to the analogue
value of the third component, means for dividing said first
analogue fraction into two portions, each being indicative of the
analogue values of the two components, means for indicating the
proportion between said two analogue values, and means for
indicating the one of the numerical values of the two components,
the amount of which determines the second physical property of the
mixture.
12. Apparatus as claimed in claim 11 having for each group of three
components three reciprocal rulers movable perpendicular to the
direction of each of three sides of a hypothetical or physical
equilateral triangle, the height of which corresponds to the
anologue value of the entire amount of that portion of a batch
which is going to be mixed by the three components in question and
about one corner of which an arm is pivotally mounted with an
abutment which is displaceable in the longitudinal direction of the
geometrical line of the arm for engagement with the interior ends
of the rulers, and in which the rulers are calibrated to indicate
the distance of each ruler from the end which engages the abutment
to the side of the triangle.
13. Apparatus as claimed in claim 12, in which the rulers directly
or indirectly are connected with control means for automatic
control of the dispensing of the individual components in
accordance with the reading of the rulers.
14. Apparatus as claimed in claim 13, in which the rulers are
connected with electrical potential generators operable to control
said generators to produce electrical potentials analogue with the
readings on the rulers, and operable to control the dispensing of
the components.
15. Apparatus as claimed in claim 12, in which an indicator device
is provided in connection with the pivotable arm, and is operable
to indicate the ratio between the readings of those two rulers
which are movable perpendicular to the two sides of the triangle
which intersect at the pivot of the arm.
16. Apparatus as claimed in claim 15, in which the bottom line of
the triangle opposite the pivot point of the arm is displaceable in
a direction perpendicular to the height of the triangle, and that
the height of the triangle is readable on a scale.
17. Apparatus as claimed in claim 16, for proportioning of
concrete, in which the scales of the two rulers which are movable
perpendicular to the two sides of the triangle which intersect the
pivot point of the arm are calibrated corresponding to the amounts
of water and cement, and that the third ruler is calibrated
corresponding to gravel.
18. Apparatus as claimed in claim 17, for proportioning a mixture
having a plurality of further components which in a second group
must be mixed in a desired ratio having a further group of three
rulers for each group of components movable relative to the sides
of a further triangle having one line parallel with the bottom line
of the triangle of the first group of components opposite the point
of intersection about which the pivotable arm is mounted.
19. Apparatus as claimed in claim 18, in which the distance between
the two triangles is variable and readable on a scale.
20. Apparatus as claimed in claim 19, in which one triangle
corresponds to the components water, cement and gravel in concrete
and the rulers in the other triangle correspond to a different size
of skeleton, and that the distance between the two triangles
corresponds to entrained air.
21. Apparatus as claimed in claim 11, having an electrical voltage
source, means for producing therefrom a voltage which is the
analogue value of a predetermined amount of a batch, a first
voltage divider operable to divide said analogue voltage into a
first portion which is the analogue value of the sum of the two
components, the ratio between which determines the first physical
property of the mixture, and a second portion which is the analogue
value of the third component of the mixture, a second voltage
divider operable to divide said first portion into two mutually
adjustable portions each corresponding to an analogue value of each
of the two components, the ratio between which determines the said
first physical property, means for indicating the ratio between
said last mentioned analogue values and means for indicating the
amount of the analogue value of that one of said two components
which determines the second physical property.
22. Apparatus as claimed in claim 21, for use with proportioning
the components of concrete in which the first voltage divider is
adapted to produce an analogue value which corresponds to the sum
of water and cement and an analogue value which corresponds to
gravel and the second voltage divider is adapted to divide the
first analogue value into portions which represent the analogue
values of cement and water, respectively.
23. Apparatus as claimed in claim 22 for proportioning concrete
having cement, water and gravel, and skeleton comprising different
sizes of stone as well as entrained air, having a first voltage
divider operable to divide an analogue voltage, which corresponds
to the analogue amount of a unisize batch, into a first portion
which comprises the mortar and a second portion which comprises the
skeleton, means operable to indicate the amount of skeleton in
percent of the entire batch, means operable to divide the analogue
portion which corresponds to skeleton into fractions, each of which
corresponds to a different size of stone in the skeleton, means
operable to indicate the analogue values of each of the sizes of
stone in the skeleton in percent of the entire amount of skeleton,
a further voltage divider operable to divide the entire batch
analogue value into a first portion corresponding to the amount of
entrained air and a second portion which corresponds to the
remaining part of the batch, means operable to indicate the amount
of entrained air in percent, means operable to divide the remaining
portion of the entire batch which corresponds to mortar into a
first portion which corresponds to the amount of gravel and a
second portion which corresponds to the sum of water and cement, a
voltage divider for dividing the last portion into towo portions
corresponding to water and cement respectively, means operable to
indicate the ratio between water and cement and/or the strength of
the concrete, and means operable to indicate the amount of water
and/or the slump.
24. Apparatus as claimed in claim 23, in which switch means is
provided operable to apply the voltage corresponding to the
analogue value of the entire batch directly to the voltage divider
system which represents the skeleton, thereby enabling the
porportion between the skeleton components to be adjusted in
percent.
25. Apparatus as claimed in claim 24 in combination with a
dispensing device having means operable to produce an analogue
value which increases as the dispensing proceeds, a differential
operatively connected with teh analogue output which is indicative
of the amount of the components to be dispensed as well as with the
analogue value produced by the dispensing device, said differential
being operable to produce a signal when said analogue value
produced by the dispensing device has been increased to the value
of the other analogue, and control means operable by said signal
for interrupting the dispensing.
26. Apparatus as claimed in claim 25 having means operable to
produce an analogue value which is slightly less than the analogue
value which indicates the amount of the components to be dispensed,
an auxiliary differential device operable to compare said analogue
value with the analogue value produced by the dispensing device and
being able to produce a signal, and control means operable to
reduce the rate of dispensing in response to said signal.
27. Apparatus as claimed in claim 26 comprising an amplification
device operatively connected with the analogue value produced by
the dispensing device to control the analogue value produced by the
dispensing device in proportion to the ratio between the unit
amount of batch as used in the computing device and the actual
amount of batch to be dispensed.
Description
In batch blending it is often the case that one physical property
of the mixture is determined by the ratio between two of the
components, while another physical property is determined by the
amount of one of the components.
A typical example of such a mixture is concrete. In addition to the
skeleton, concrete comprises cement and water and as well known by
those skilled in the art, the ratio between cement and water
determines the concrete strength while the amount of water
determines the slump.
In most concrete mixing stations a plurality of precalculated
standard mixtures are available for immediate delivery. The
calculation of such standard mixtures requires the use of
tabulations and formulas known to those skilled in concrete
technology.
It happens, however, several times daily in most concrete mixing
stations that immediate delivery of a mixture is specified with a
proportioning which differs from any of the standard mixtures.
Though the ready-mix operator is a qualified man with practical
experience, he is not skilled in calculating the correct blending
of a new batch according to individual requirements and even if he
was, such a recalculation would not be feasible under practical
conditions because it would require much more time than available
when a lorry driver pulls in and requests a modified batch to be
taken back to a building site.
The mix-operator knows, however, that if the customer wants a
mixture with more water than in standard mixture then it is
necessary to add more cement to make sure that the mixture keeps
its strength, and for that reason mix-operators all over the world
are inclined to over-proportion the cement in such individually
specified mixtures.
Since the cement is the most expensive component in ready-mixed
concrete, the result is that in a mixing station a substantial
amount of cement is given away or wasted each year. Furthermore the
addition of an arbitrary amount of cement to make up for an extra
amount of water also changes the total volume.
This waste could be avoided, provided a method and an apparatus can
be found for quickly determining the correct amount of cement to be
used in an individually specified concrete mixture to give the
required strength of the mixture.
Corresponding conditions prevail in other technical fields and even
though the invention will be described hereinafter basically with
reference to concrete mixtures, it will be understood that the
invention is not limited to concrete but can be used in other
technical fields where similar conditions are found, namely that
the ratio between two components of a mixture determines one
physical property and the amount of one of the two components
determines another physical property.
It is an object of the invention to provide a simple method which
enables a quick and safe proportioning of the correct amount of the
components to ensure the first mentioned physical property with a
specified amount of the second of the two components which
determines the second physical property.
According to the invention this is achieved by using an analogue
computing device which is programmed for reading in the analogue
values of two of the components and which is also provided with
means for dividing an analogue value which is the sum of an
analogue value corresponding to the two components the ratio
between which determines the first physical property and means for
indicating that ratio. This analogue computing device is used in
such a manner that the ratio between said two last mentioned
components is first adjusted to the value which determines the
first physical property whereafter the amounts of that amount of
the one of the two components which determines the other physical
property is adjusted until a predetermined analogue value can be
read out whereafter the analogue values are used for proportioning
the batch.
It has been suggested to use analogue computing devices in various
embodiments in connection with batch blending, for example to solve
such complicated problems as minimum costs blending, using the
method of steepest ascents.
In such cases, however, the analogue computer has not been
preprogrammed and the programming of such a computer is obviously
far beyond what can be done by the mix-operator of a ready-mix
concrete station. In addition, the problems to be solved by such a
specially programmed analogue computer are entirely different from
the problems which are solved according to this invention.
It has also been proposed to store a substantial amount of data
relating to a plurality of standard mixtures on punched cards or
tape in a general purpose computer to enable the selection of an
already calculated mixture of concrete among so many precalculated
mixtures that practically all deviations from standard mixtures can
be avoided.
This solution is, however, not feasible under practical conditions.
First of all a computer of sufficient capacity to meet all
practical requirements is a fairly expensive equipment which must
be written off and the writing off must be calculated in the price
of all the mixtures. In addition, the selection of the correct one
of maybe several thousand standard mixtures stored in a computer
requires a substantial training of the mix-operator far beyond what
he normally has and with such a large amount of standard mixtures a
mistake is very likely to occur. Thus even if the best standard
mixture to meet a customer's specification may be No. 1237, the
mix-operator may very well supply No. 1252.
The merits of the present invention are that it provides a very
simple method and a correspondingly simple preprogrammed analogue
computer which can be used by any mix-operator after short training
without any knowledge of analogue computers because it is
preprogrammed and the operation is limited to the adjustment of a
few controls and the reading of a few indicators which even may be
calibrated to indicate the desired physical properties
directly.
The method is so simple that mistakes can be practically completely
avoided.
The solution of the problem by a simple method also provides for
construction of a simple analogue computer.
The simplest possible analogue computer according to the invention
has the character of a slide rule and provides two rulers which are
reciprocal in two directions with an angle of 120.degree.
therebetween into engagement with an abutment on an arm which is
pivotable about the point of intersection between two sidelines of
a hypothetical equilateral triangle in which the sides are
perpendicular on the direction of reciprocation of the two rulers
and with the position of the abutment relatively to the two
sidelines of the triangle being readable on a scale.
By calibrating this scale to show the ratio between two components
and calibrating the readings of the two rulers to show the distance
from the abutment to each of the two sides in the hypothetical
triangle, the well-known teaching that the sum of the distance from
each point inside an equilateral triangle perpendicular to each of
its three sides is equal to the height of the triangle enables the
correct proportioning of the two of the components by first
adjusting the pivotable arm to indicate the desired ratio and
thereafter displacing the abutment in the direction of the arm
until the reading on one of the rulers indicates the desired
amount. By using a third ruler reciprocable perpendicular to the
third side of the hypothetical triangle, the reading on the third
ruler indicates the analogue value of the third component of the
mixture, the total amount of which is the analogue value of the
height of the triangle.
By calibrating the first two rulers into amounts corresponding to
cement and water in a concrete mixture and the third ruler
corresponding to gravel such a slide rule device can be used as a
simple calculation aid for concrete proportioning.
A mechanical-geometrical system based on this principle can
obviously be constructed by means of rails and reciprocal rulers
and by using the reciprocation of the rulers, if desired, in
connection with mechanical amplifiers the reciprocation of the
rulers can be used directly or indirectly to control the supply of
the components in amounts corresponding to the analogue values
readable on the rulers from automatic weighing devices.
It will also be possible to combine the rulers with electrical
devices in such a manner that the reciprocation of each of the
rulers controls the movement of a variable tapping on a voltage
divider so as to thereby produce electrical voltages which
represent analogue values of the readable analogue values of the
rulers and thereby provide for electrical control of automatic
dispensing of the individual components.
An analogue electrical system which enables the same simple method
to be used can, however, be constructed by means of voltage
dividers which provide an electrical analogue computer which is
preprogrammed to use the method. In a mixture with three components
it is only necessary to first adjust an analogue value which
corresponds to the total amount of the batch, thereafter adjusting
the ratio between the two of the components and eventually
adjusting the desired analogue value of one of the two components,
the ratio between which must be kept constant.
A simple analogue computer for proportioning three components of a
batch comprises basically only two voltage dividers, each having an
adjustable tapping. The first voltage divider is connected across
the voltage source and thereby supplied with an input voltage which
corresponds to the analogue value of the total amount of the batch.
The other voltage divider is connected between the variable tapping
of the first voltage divider and one end thereof. The adjustment of
the tapping of the second voltage divider is made readable either
by a graduation of a control member or by means of a suitable
instrument. Output terminals are connected with each end of the
first voltage divider as well as with the two variable tappings. An
indicator is provided for reading out the voltage which corresponds
to one of the portions into which the second voltage divider
divides the potential thereacross so as to readout the analogue
value of one of the components.
A simple analogue computer of this kind with two potentiometers can
be used for carrying out the method whereby the variable tapping of
the second potentiometer first is adjusted to the desired ratio
between the two components until the indicator shows the ratio,
whereafter the variable tapping of the first potentiometer is
regulated until the desired analogue value of one of the two
components is indicated between the outlets which are connected
with the two variable tappings of the potentiometers.
In the case of concrete the first adjustment determines the ratio
between cement and water, while the second adjustment regulates the
ratio between gravel and cement plus water. During the last
regulation the ratio is kept constant, and the amount of cement and
water is readjusted with the ratio therebetween maintained until
the desired amount of water can be read out of the computer.
It will often be found in a mixture that a third component of a
mixture such as a filler has a content of one of the two other
components. In concrete it is nearly always the case that the
gravel is wet, i.e. a part of water is included in the gravel.
The invention also enables a correction for such a case. Obviously,
if there is for example 10 percent water in the gravel, the amount
of water used must be reduced correspondingly because otherwise the
adjusted cement/water ratio will not be kept.
By the method according to the invention this can be compensated
for by measuring the amount of the one component which is contained
in the other component and using an analogue computer which
comprises an adjustable summator device which is operatively
connected with the outputs for the two components. By adjusting the
summator device according to the measured contents of one of the
components in the other, it will in the case of for example water
in the gravel automatically decrease the analogue value which
corresponds to the contents of water with an amount corresponding
to the water which is included in the gravel.
It will also often be the case that the quality of one of the
components differs from one supply thereof to the next. It is well
known that the quality of cement differs and it has therefore
previously been necessary to dispense sufficient cement to ensure
that cement of the poorest quality always will give the desired
strength of the concrete. The strength of concrete is governed by
the coefficient of variations. Variations of the quality of the
cement increase the coefficient of variation. The more uniform the
cement quality is, the smaller becomes the coefficient of
variation.
The invention also provides for automatically readjusting the
dispensing of that one of the components of a mixture the quality
of which varies from supply to supply in such a manner that in
order to keep a substantially uniform physical property of the
mixture and savings with respect to the components in question a
relatively increased amount of the component is dispensed when the
quality is poor, while a relatively smaller amount of the component
is dispensed when the quality is better.
According to the invention this is achieved in that the analogue
value of the component in question, the quality of which varies, is
adjusted as a reference value derived from the physical properties
of a reference mixture whereafter a test mixture is produced with a
different quality of the component in question and the physical
properties of the test mixture are derived whereafter a digital
ratio between the two physical properties is calculated and an
adjustable multiplication device which is connected with the
analogue value of the component in question as adjusted according
to the reference mixture is adjusted to the ratio calculated so as
to thereby produce a corrected analogue value of the component in
question which corresponds substantially to that amount of the
component which with different quality will produce substantially
the same physical property of the mixture in which the component of
different quality is used.
With specific reference to concrete this method can be used in such
manner that the reference value of the analogue amount of cement is
adjusted according to a reference mixture for which the factor K in
Bolomeys formula
is calculated whereafter the strength of a test mixture in which a
different cement quality is used is determined and the K-factor of
the test mixture is calculated, whereafter the multiplication
device is adjusted on the ratio between the two K-factors and the
analogue value for the amount of cement of different quality is
derived from the multiplication device.
Further details with respect to the method and the construction of
geometrical mechanical analogue computers as well as equivalent
electrical analogue computers will be described in the following
with reference to the accompanying drawings in which
FIG. 1 is a diagrammatic illustration of controls, indicators and
analogue values illustrating schematically the connections in order
to explain the method and the principle of an analogue computer
according to the invention,
FIG. 2 is a perspective illustration of a computing device
according to the invention,
FIG. 3 is a schematic illustration of a mechanical geometrical
system which provides a part of an analogue computer according to
the invention with appertaining electrical equivalence for that
part of the computer,
FIG. 4 is an illustration similar to that of FIG. 3 with respect to
other parts of the computer,
FIG. 5 is a schematic combination of the systems of FIGS. 2 and
3,
FIG. 6 is a complete mechanical geometrical system constructed
according to the principles of FIGS. 3 and 4 and 5,
FIG. 7 is the electrical equivalence of FIG. 6,
FIG. 8 is a schematic illustration of the control of dispensing one
component by using the electrical analogue value of the amount of
components as reference voltage,
FIG. 9 is a schematic illustration of a further modification of the
principle of FIG. 3,
FIG. 10 is a schematic illustration of a simple calculating device
based on the mechanical geometrical system,
FIG. 11 is a detail of the calculating device of FIG. 10.
FIG. 12 is a diagrammatic illustration of a part of an analogue
computer according to the invention for automatically correcting
the analogue value of one of the components, in response to
variations of quality of the component, and
FIG. 13 is the circuit arrangement of FIG. 12 illustrating a
further automatic correction of a third component in response to
the variation of the analogue value of the component the quality of
which varies.
FIG. 1 illustrates schematically the principles of an analogue
computer for adjusting the desired amounts of seven analogue values
L, C, W, G, S.sub.1, S.sub.2 and S.sub.3, corresponding to the
amounts of seven components of a composite product. The components
will in the following be referred to by the same capital letters as
their analogue values. It is supposed that the ratio between the
analogue values or components C and W determines one physical
property of the composite product and that the absolute analogue
value or amount of W determines another physical property.
To begin with only the part of the computer which relates to the
three components C, W and G will be considered.
The computing device has a first control member K.sub.f which by
means of connections f.sub.c and f.sub.w shown in dotted lines and
symbolizing adjustments is connected with analogue outputs for the
values C and W so as to adjust the ratio therebetween. The control
K.sub.f is also connected with a ratio indicator I.sub.f operable
to indicate the ratio W/C. The computing device furthermore has
another control member K.sub.w which through one connection f.sub.g
is connected with the analogue output G and through another
connection f.sub.cw is connected with the total analogue output
C+W.
The control member K.sub.v is furthermore connected with an
indicator I.sub.w which indicates the value of the analogue value W
and preferably also with indicators I.sub.c and I.sub.g which
indicate the values of C and G respectively.
The method of using this part of the computing device is as
follows:
The ratio between the analogue values C and W is first adjusted by
means of the control member K.sub.f until the desired ratio is
readable on the indicator I.sub.f corresponding to the physical
property of the composite product which is determined by the ratio
W/C. The indicator I.sub.f may within the scope of the invention be
an instrument or a graduated scale or any other type of
indicator.
Hereafter the ratio (C+W):G is adjusted by means of the control
member K.sub.w. Obviously, the ratio W/C as previously adjusted by
means of the control member K.sub.f will not be influenced by the
adjustment of the control member K.sub.w but the analogue values W
and C are changed, still with the same proportion between them.
When, during the adjustment of the control member K.sub.w the
indicator I.sub.w shows the desired amount of the component W which
is required in the mixture in order to obtain the second physical
property, all the three analogue values will be correctly adjusted
and the components can be dispensed in accordance with the analogue
values to provide a composite mixture in which the physical
properties will be as determined by the ratio W/C as well as by the
absolute amount of W.
Though the indicators I.sub.c and I.sub.g are not absolutely
necessary we have found it convenient that also the analogue values
of C and G can be indicated.
In the following it will be supposed that the mixture is concrete
in which the analogue values C, W and G stand for the components,
cement, water and gravel.
When the delivery of concrete of a predetermined strength is
specified by a customer, the ready-mix operator of a concrete
station knows that within practical limits the strength is
determined by the ratio between water and cement and that the
second physical property, namely the slump, is determined by the
contents of water.
The part of the analogue computer briefly described hereinbefore
provides for a method which avoids the danger of overdispensing
cement and thereby wasting cement when the customer requires an
individually composed mixture with a certain absolute amount of
water in order to obtain a certain slump.
Obviously the method of obtaining an immediate answer to the
correct composition of a concrete mixture is that the water/cement
ratio is first adjusted to obtain the desired strength by reading
the ratio on the indicator I.sub.f, whereafter the amount of water
is adjusted until the desired amount is readable on the indicator
I.sub.w. By the last adjustment the analogue value C of cement is
readjusted because the water/cement ratio is kept constant so that
a mixture is always obtained with the desired strength as
determined by the control member K.sub.f and there is no risk of
overdispensing the cement with waste as a result or of
underdispensing with less strength as a result.
In the following the remaining part of the analogue computer device
of FIG. 1 will be explained with reference to concrete
technology.
In addition to cement/water and gravel, concrete usually contains
entrained air L and skeleton composed of different modulus
aggregate or sizes of stones S.sub.1, S.sub.2 and S.sub.3 which in
the following will be supposed to be small, medium and large sizes
of stones.
The computer device has a control member K.sub.s1 with one
connection f.sub.s1 operable to adjust the analogue value of
S.sub.1, another connection f.sub.s2,3 operable to adjust the
analogue values S.sub.2 +S.sub.3 and an indicator I.sub.s1 for the
amount of stones S.sub.3. A further control member K.sub.s2 has
connections f.sub.s2 and f.sub.s3 operable to adjust the ratio
between the stones S.sub.2 and S.sub.3 as well as a connection to
indicators I.sub.s2 and I.sub.s3 for indicating the values of these
analogue values. A further control member K.sub.s3 is provided with
connections f.sub.st and f.sub.m1 to adjust the ratio between the
entire amount of stones S.sub.1 +S.sub.2 +S.sub.3 and the entire
amount of all the components in the mixture as well as an indicator
I.sub.st for indicating some of the analogue values S.sub.1
+S.sub.2 +S.sub.3 in proportion to the sum of all the analogue
values.
By initially setting the control member K.sub.s3 to read a unit
value of the amount S.sub.1 +S.sub.2 +S.sub.3 on the indicator
I.sub.st such as for example 100 by volume and determining that for
example the ratio between S.sub.1, S.sub.2 and S.sub.3 should be
50: 30: 20 it is possible to obtain the adjustment in the following
manner:
The control member K.sub.s1 is operated until the indicator S.sub.1
shows 50 whereafter the control member K.sub.s2 is operated until
the indicators S.sub.2 and S.sub.3 show 30 and 20 respectively.
When thereafter the control member K.sub.s3 is operated and the
analogue value of the total batch amount also is a unit value, for
example 1,000, and it is desired to have for example 40 percent
skeleton in the mixture, this can be adjusted directly by means of
the member K.sub.s3 by calibrating the indicator I.sub.st to show
percent. Thereby the exact analogue values of the three amounts
S.sub.1, S.sub.2 and S.sub.3 will be readjusted but the initially
adjusted ratio will be kept constant.
The analogue value L for entrained air is adjustable relatively to
the entire sum of analogue values by means of a member K.sub.L by
means of connections f.sub.L and f.sub.t as indicated, and the
contents of entrained air as adjusted thereby can be read out in
percent on the indicator I.sub.L.
When the four adjustments herein described have been made, the
total amount of cement, water and gravel is the difference between
the entire batch amount and the sum of contents of air and
skeleton.
The final step of determining the composition is thereafter to use
the controls K.sub.f and K.sub.w as hereinbefore described to
determine the water/cement ratio according to the desired strength
and the amount of water according to the desired slump.
More specifically the strength is determined by the water/cement
ratio according to Bolomeys formula
.sigma.=K(C/V-0.5)
in which .sigma. is the strength and K is a constant which is
determined by the quality of the cement.
It will be understood that it is possible to calibrate the
indicator I.sub.f directly in strength according to Bolomeys
formula so as thereby to avoid the use of tabulations for
determining the water/cement ratio as a function of strength.
Regarding the adjustment of the amount of water which determines
the slump, it should be observed that the slump is also governed by
the largest size of stones which must be smaller than the narrowest
cross section of the mould. Since the stones already have been
selected according to previous adjustments, the adjustment of
K.sub.w is the actual slump determination.
Obviously, if the amount of water is increased, this will cause an
increase of the total amount of paste which is the sum of cement
and water, and decrease the amount of gravel and alternatively, if
the amount of water is decreased the amount of cement will be
proportionally decreased and the amount of gravel increased.
It will be appreciated that the method of using the schematically
shown computing device of FIG. 1 is extremely simple and provides
for quickly obtaining the correct analogue values of an
individually specified mixture. We have found that the method is so
simple that it is possible with relatively short training to teach
the mix-operator of a concrete station to use the method and obtain
the correct answer in less than 1 minute.
A practical design of an analogue computing equipment according to
the invention is illustrated in FIG. 1 in which 100 is a control
panel on the front side of which the various control members
K.sub.s1, K.sub.s2 ... are shown in the form of control knobs and
in which also the indicators are shown as readable instruments.
It will be understood that the control knob assembly which in FIG.
1 is referred to by KP represents means for adjusting the analogue
values and ratios therebetween and once a predetermined batch of a
composite product has been calculated and the analogue values
adjusted, the computing device can be used to reproduce the same
composition by retaining the controls.
In other words it is possible by completing the system of FIG. 1
with a plurality of preadjusted controls in groups corresponding to
the group KP and selecting each one of said preadjusted groups of
controls to select a corresponding one of a plurality of
precalculated standard mixtures.
This possibility is indicated in FIG. 2 in which StI, StII ... StX
indicate each one of ten different groups of controls which by way
of trimming are adjustable to respond to each one of ten different
standard mixtures and can be selected individually by means of
corresponding selector members SeI, SeII ... SeX of a selector
board 102 which is connected with the control panel 100 by means of
a cable 104.
The arrangement of FIG. 2 is such that all the indicators are
common to each of a selected one of control groups whether it is
the group for individual adjustment KP as shown in FIG. 1 or any
one of the standard mixture groups StI, StII ....
The selector board 102 has in addition to the selectors SeI, SeII
... a selector K.sub.I for selecting the group of controls KP for
individual batch mixing.
While the adjustment members of the group of selectors KP may be in
the form of control knobs or the like which can be individually
adjusted, the corresponding control members of the standard mixture
controls should be designed in such a manner that they can only be
readjusted by means of special tools or the like and only for the
purpose of minor readjustments or trimmings. The groups of standard
mixture controls however, correspond individually with respect to
their connections with the instruments and the analogue value
outputs to the control group KP of FIG. 1, and it will be
appreciated that initially they have to be adjusted individually
precisely in the manner described hereinbefore to correspond to
selected standard mixtures.
In a concrete mixing station the selector board 102 may be arranged
on the platform where the mix-operator can surbey the delivery and
can select either a specified one of the standard mixtures by
pushbutton control or the individual control selector group KP of
FIG. 1 in the case where a mixture which deviates from any of the
available standard mixtures is specified.
The control panel 100 of FIG. 2 has in addition to the controls
hereinbefore described a pushbutton SW and two other controls
K.sub.KW and K.sub.RAT, the function of which will be described in
the following and the selector board 102 has a further control
K.sub.x the function of which also will be described in the
following.
It is indicated that the selector board is connected with a cable
106 which is the output cable from the entire computer device and
adapted to be connected with the dispensing equipment for automatic
dispensing of the individual components according to the adjusted
analogue values of each of them.
As will be appreciated from the foregoing the adjustment procedure
is the same the whole way through and always starts with adjusting
the ratio between two numerical values and after the first
adjustment another adjustment of ratio between two numerical values
is effected and so forth, all in accordance with a pattern which is
related to the technology of the mixture to be produced.
This simple method provides for a simple construction and
preprogramming of an analogue computing device, either in the form
of a simple mechanical calculation device or an equivalent
electrical computer as will be described in the following.
FIG. 3 illustrates a mechanical geometrical system and the
corresponding electrical equivalent for determining the analogue
values of C, W and G.
The mechanical geometrical system comprises three rulers C.sub.1,
W.sub.1 and G.sub.1 each of which extends perpendicularly to each
one of three sidelines a, b, and c of a hypothetical triangle or as
a system of guide members constructed as an equilateral triangle
with a height M which may be variable.
An arm K.sub.f which corresponds to the control member K.sub.f of
FIG. 1 and therefore is designated by the same reference numeral is
pivotally mounted about a top A of the triangle and points on a
scale I.sub.f which is the equivalent of the indicator I.sub.f of
FIG. 1.
The interior ends of the rulers C.sub.1, W.sub.1 and G.sub.1 are
adapted to engage or are connected with an abutment K.sub.w which
corresponds to the control member K.sub.w of FIG. 1 and which is
movable along the geometrical line which coincides with the
longitudinal direction of the arm K.sub.f. This abutment may either
be reciprocally mounted on the arm K.sub.f, or the arm may be
reciprocally mounted with the abutment firmly secured on the
arm.
The geometrical system of FIG. 3 is based on the discovery that the
geometry of equilateral triangles and the electrical analogy
thereof provide a computing aid for proportioning components of a
mixture to fulfil requirements as hereinbefore described.
From the geometry of equilateral triangles it is known that the sum
of the distance from any point inside the triangle perpendicular to
all the three sides is equal to the height of the triangle. It will
therefore be understood that the lengths of the rulers C.sub.1,
W.sub.1 and G.sub.1 inside the triangle which are referred to by C,
W and G will be the analogue values of the three components of the
mixture, the entire amount of which is equal to the height M of the
triangle.
By considering the case where the abutment K.sub.w is moved down to
the bottom c of the triangle corresponding to the analogue values
W.sub.m and C.sub.m of the components W and C, the point Q where
the arm K.sub.f intersects the bottom line c of the triangle will
divide the bottom line into two portions the lengths of which are
2: 3.sup.. C.sub.m and 2: 3.sup.. W.sub.m.
Inasfar as the factor 2: 3 is the same this means that for any
angular position of the arm K.sub.f there will be a predetermined
ratio f=W:C, and by letting the arm point on the scale I.sub.f and
calibrating the same the ratio can be made readable.
By designing the system in such a manner that the rulers are
reciprocable in their longitudinal direction for permanent
cooperation or engagement with the abutment K.sub.w and
simultaneously can be displaced in the direction perpendicular to
their longitudinal directions, the geometrical system provides a
calculation aid for proportioning a mixture which satisfies the
conditions
W:C= f
and
(W+ C):(W+ C+ G)= g
corresponding to a concrete mixture with water, cement and gravel
as basic components.
The geometrical system is used in the simple manner that the arm
K.sub.f first is adjusted to read the desired ratio "f" on the
indicator I.sub.f. Thereby the ratio W:C is adjusted and this ratio
is kept constant during displacement of the abutment K.sub.w along
the arm K.sub.f. By displacing the abutment K.sub.w until the
desired analogue value W can be read on the ruler W.sub.1 a mixture
is calculated with the desired water/cement ratio and the desired
amount of water whereby the analogue values of gravel and cement
can be read on the rulers C.sub.1 and W.sub.1.
The corresponding electrical equivalent of the geometrical system
is also included in FIG. 3 and comprises a voltage divider P.sub.g
in the form of a potentiometer with a movable tapping K.sub.w. An
input voltage corresponding to the height of the triangle M=C+W+G
is applied over the potentiometer P.sub.g.
Between the top end of the potentiometer P.sub.g and its movable
tapping, a further potentiometer P.sub.f is provided with a
variable tapping K.sub.f which is provided with an indicator (not
shown) corresponding to the indicator I.sub.f in FIG. 1, so that
for example the control knob of the potentiometer points on a scale
which is graduated corresponding to the scale I.sub.f of FIG.
3.
The two variable tappings are connected with output terminals
MS.sub.1 and MS.sub.2 and the ends of the potentiometer P.sub.g is
connected with output terminals OM and OMS.
An indicator I.sub.w for the analogue value of water is provided
between the two variable tappings of the potentiometers and further
indicators I.sub.c and I.sub.g corresponding to those of FIG. 1 may
be provided between the other output terminals.
As indicated in dash and dotted lines the tapping K.sub.f of the
potentiometer P.sub.f corresponds to the arm K.sub.f of the
geometrical system and the tapping K.sub.w of the potentiometer
P.sub.g corresponds to movement of the abutment K.sub.w along the
line of the arm K.sub.f.
The electrical system of FIG. 3 is used for proportioning the
concrete mixture in such manner that when a predetermined strength
is specified, the water/cement ratio is first adjusted by means of
the tapping K.sub.f until the desired ratio can be read on the
indicator. When, thereafter, the tapping K.sub.w is adjusted until
the indicator I.sub.w shows a predetermined amount of water
corresponding to the desired slump, the outputs C, W and G between
the output terminals are electrical voltages corresponding to the
analogue values of each of the three components.
A similar mechanical geometrical system with electrical analogy is
shown in FIG. 4 adapted to adjust the ratio between the three sizes
of stone in the skeleton as well as adjusting the ratio between
skeleton and the total amount of the batch.
For the sake of simplification the three rulers are designated by
the analogue values S.sub.1, S.sub.2 and S.sub.3 as readable inside
the orbits of the triangle. The three rulers are connected at a
point AN where two pivotable arms K.sub.s1 and K.sub.s2
intersect.
Provided the mixture is going to be calculated with the ratio
it will be usual to specify the ratio between the sizes of the
stone in percent such as for example a=50 percent, b=30 percent and
c=20 percent.
By adjusting the angular positions of the two pivotable arms
K.sub.s1 and K.sub.s2 relatively to each other it is possible to
adjust the ratio between S.sub.1, S.sub.2 and S.sub.3 as a : b :
c.
By, prior to this adjustment, adjusting the height of the triangle
according to a unit analogue value, for example 100, the ratio
between S.sub.1, S.sub.2 and S.sub.3 will be expressed in percent
and can be indicated on correspondingly calibrated scales on the
rulers S.sub.1, S.sub.2 and S.sub.3.
By thereafter decreasing the height of the triangle by displacing
the horizontal top line until its adjustment member K.sub.s3
indicates the desired ratio between the total amount of skeleton
and the total amount of the mixture on the scale I.sub.st and
keeping the arms K.sub.s1 and K.sub.s2 locked in the adjusted
positions, the length of the rulers inside the triangle will be
reduced while retaining the adjusted proportions in percent and
when the control member K.sub.s3 has been adjusted to the desired
ratio g according to the last one of the two formulas hereabove the
actual analogue values of S.sub.1, S.sub.2 and S.sub.3 can, by
correspondingly calibrated scales of the rulers, be read out of the
device.
The electrical analogy of FIG. 4 comprises an input potentiometer
D.sub.3 across which an input potential is applied. By initially
adjusting the variable tapping K.sub.s3 of the potentiometer
D.sub.3 to the top of the potentiometer as indicated in dotted
lines the input potential will be applied across the potentiometer
A.sub.s which is provided between the variable tapping K.sub.s3 and
the bottom of the potentiometer D.sub.3 and by means of the
variable tapping K.sub.s1 of the potentiometer A.sub.s and the
variable tapping K.sub.s2 of the potentiometer B.sub.s which is
provided between the variable tapping K.sub.s1 and the bottom of
the potentiometer A.sub.s, the input voltage can be divided in the
proportions a : b : c with the proportions readable on the
indicators I.sub.s1, I.sub.s2 and I.sub.s3 in percent.
When thereafter the variable tapping K.sub.s3 of the potentiometer
D.sub.3 is adjusted to the desired ratio between the entire amount
of skeleton and the entire batch amount as readable in percent on
the indicator I.sub.st, the analogue output values between the
output terminals OMS, OS.sub.1, OS.sub.2 and OS.sub.3 respectively
will be proportionally reduced while retaining the percentage
adjustment between the three components.
As previously mentioned it will frequently be found that a mixture,
such as is the case with concrete, is specified to contain a
further component L which in concrete stands for entrained air in a
certain proportion to the entire amount of the batch whereby the
following conditions must be fulfilled
(S.sub.1 +S.sub.2 +S.sub.3):(L+C+W+G+S.sub.1 +S.sub.2 +S.sub.3)=
d
in which d is the air in percent.
Such a single component can be symbolized by the height of an
equilateral triangle.
As apparent from the foregoing the height of the triangle of FIG. 3
which is referred to by M corresponds to the entire amount of
mortar which is water plus cement plus gravel and the height of the
triangle of FIG. 4 when adjusted to the desired percent of skeleton
in the entire mixture corresponds to the skeleton. The triangle of
FIG. 3 can therefore be referred to as the M-triangle, and the
triangle of FIG. 4 as the S-triangle.
By calculating the entire batch by using the mechanical geometrical
systems it is therefore possible to combine the M-triangle and the
S-triangle in the manner indicated in FIG. 5 and by spacing these
two triangles a distance corresponding to the height of a small
triangle L which symbolizes the amount of entrained air the total
height of the sum of the three triangles between the points A and
A.sub.2 will represent the entire amount of the batch.
Normally the amount of entrained air will be approximately 2
percent when no special measures are taken.
In some cases it is desired, however, to provide more air in the
final mixture by means of additives.
Since it is desired in an analogue computer to have the analogue
value corresponding to the entire batch by way of a unit analogue
such as 1,000 corresponding to, for example 1 m..sup.3 which is
equal to 1,000 litres, it is in FIG. 5 supposed that in such cases
where there will be more air than the natural 2 percent in the
mixture, the compensation for different air contents is obtained by
diminishing the amount of mortar by displacing the bottom line of
the M-triangle to read in the percent of air on a correspondingly
calibrated scale I.sub.L corresponding to the indicator I.sub.L of
FIG. 1.
Obviously it will also be possible to keep the height of the
M-triangle constant and reduce the height of the S-triangle in
accordance with the amount of air.
While FIG. 5 schematically indicates a combination of the systems
of FIGS. 3 and 4, a more specific combination of the geometrical
mechanical systems of FIGS. 3 and 4 is illustrated in FIG. 6.
The apparatus comprises a system of rails with stationary rails
M.sub.a, M.sub.b and M.sub.al, M.sub.b1 which form the sides in two
oppositely directed equilateral triangles with tops A and A.sub.2,
the distance between which can be indicated on a scale I.sub.t to
be adjusted according to a unit analogue value of the entire amount
such as for example 1 m..sup.3 equal to 1,000 liter.
The bottom rail M.sub.c of the M-triangle can be displaced by means
of an adjustment member K.sub.L to indicate the distance between
the two triangles L corresponding to the contents of entrained air
on a scale I.sub.L which extends from the horizontal line M.sub.cl
of the S-triangle.
In its turn the horizontal line M.sub.c1 of the S-triangle can be
displaced by means of the adjustment member K.sub.s3 to indicate
the percentage contents of skeleton in the entire batch on the
scale I.sub.st.
The remaining adjustable members of FIG. 6 are referred to by the
same reference numerals as in the previously explained figures.
In the following it is supposed that a concrete mixture is desired
proportioned according to the following specification:
1. Skeleton composition
S.sub.1 :S.sub.2 :S.sub.3 =a:b:c
2. Ratio Paste--Skeleton
(S.sub.1 +S.sub.2 +S.sub.3):(L+C+W+G+S.sub.1 +S.sub.2
+S.sub.3)=d
3. Entrained air in percent of total mix
L:(L+C+W+G+S.sub.1 +S.sub.2 +S.sub.3)=e
4. Water--Cement ratio
W: C=f
5. Mortar composition, i.e. W+C in percent of mortar
(W+C):(W+C+G)= g and
6. Total amount of a computing size batch by volume
L+C+W+G+S.sub.1 +S.sub.2 +S.sub.3 =1=1,000 liter.
In previous computations of concrete a typical procedure has been
substantially as follows:
The water/cement ratio is calculated from a formula to give the
desired strength. The volume of air is taken from a table. The
approximate quantity of water needed to produce the desired slump
is taken from a table whereafter the exact volume of water can be
calculated. Thereafter, knowing the water/cement ratio, the exact
volume of cement can be calculated. Thereafter the percent of
coarse aggregate or skeleton can be taken from a table. The volume
of sand can then be calculated. Eventually, by multiplying with the
specific gravity, the batch quantities can be calculated. Such
calculation based entirely on concrete theory requires an expert
and will take him between 1 and 2 hours.
By means of the proportioning aid or computing device according to
the invention it is only necessary to read the proportions as
specified, i.e. a, b, c, d, e and f into the device, i.e. to put
the data into the device, which is a simple manual procedure, and
by eventually adjusting g until the analogue value of water "W"
indicates the desired amount, all the other values readjust
themselves and all the batch quantities can be read out of the
device. The whole procedure takes less than 1 minute and the use of
the device does not require an expert.
By means of the system of FIG. 6 it is only necessary to read in
the proportional values a, b, c, d and e which is a simple manual
procedure and thereafter adjusting the value g until the desired
analogue value of water W is readable on the scale. Thereby all the
other analogue values have readjusted themselves and all the
correct analogue values can be read out of the system which thereby
provides a calculation aid for quickly and exactly determining the
correct analogue values of the individual components of the mixture
according to individual specifications without the necessity of
using an expert.
The mode of use and operation of the proportioning aid or computing
device of FIG. 6 is compared with the calculation procedure
hereabove explained as follows with respect to proportioning a
batch as hereabove specified.
The adjustment member K.sub.s3 is initially set in a position
corresponding to a unit amount of total skeleton so as thereby to
enable the proportions between S.sub.1 and S.sub.2 and S.sub.3 to
be read out in percent.
Thereafter the arms K.sub.s1 and K.sub.s2 are swung relatively to
the size of the S-triangle until the desired percent between the
stones can be read out of the rulers S.sub.1, S.sub.2 and S.sub.3
and the arms are locked in the adjusted positions relatively to the
sides of the S-triangle.
By means of the member K.sub.s3 the line M.sub.c1 of the S-triangle
is thereafter displaced until the percentage contents of skeleton
relative to the entire amount is readable on the scale
I.sub.st.
Thereafter the bottom line M.sub.c of the M-triangle is displaced
until indication of the percent of air which is expected--either
about 2 percent naturally or more in the case of use of
additives--is readable on the scale I.sub.L.
Thereafter the pivotable arm K.sub.f is adjusted to read the ratio
f between water and cement on the scale I.sub.f, and eventually the
abutment K.sub.w is displaced until the desired amount of water W
is readable on the appertaining ruler on the M-triangle.
After these adjustments all the analogue values can be read out of
the system.
The electrical analogy of the geometrical system of FIG. 6 is shown
in FIG. 7 in which the electrical analogies of FIGS. 3 and 4 are
combined.
The voltage from a stabilized voltage source VS is adjustable by
means of a member OP in such a manner that a stabilized voltage
which is supplied between input terminals IT.sub.1 and IT.sub.2 has
an analogue value which represents the value L+C+W+S+S.sub.1
+S.sub.2 +S.sub.3 =1,000 for example corresponding to 1 m..sup.3 or
1,000 litres.
This analogue value is readable on an indicator I.sub.t and
corresponds to the geometrical distance between the tops A and
A.sub.2 of the triangles of FIG. 6.
As an equivalent to adjusting the distance between the triangles of
FIGS. 5 and 6, the potentiometer D.sub.1 of FIG. 5 is connected
directly over the input terminals so as to enable the proportion
L:(L+C+W+G+S.sub.1 +S.sub.2 +S.sub.3) to be directly adjusted on
this potentiometer and the analogue value of the amount L of
entrained air can be read between the output terminals OL and OM on
the indicator I.sub.L.
The potentiometer D.sub.3 is also connected directly across the
input terminals I.sub.t1 and I.sub.t2. The variable tapping
K.sub.s3 of the potentiometer D.sub.3 is connected with the output
terminal OMS. Hereby the voltage portion between the terminals OMS
and OS.sub.3 corresponds to the entire amount of skeleton and is
referred to by S and the output voltage between the output
terminals OM and OMS corresponds to the entire amount of mortar and
is designated by M.
The skeleton voltage S is divided into three portions by means of
the potentiometers A.sub.s and B.sub.s of FIG. 4 and in a similar
manner the mortar voltage M is divided into three portions by means
of the potentiometers P.sub.g and P.sub.f of FIG. 3.
The potentiometer arrangement P.sub.kw as indicated in dotted lines
will be explained later.
The terminal IT.sub.1 is connected with the variable tapping
K.sub.s3 of the potentiometer D.sub.3 through a connection in which
a manually operable switch S.sub.w is provided so as to enable the
input voltage to be applied directly across the input potentiometer
A.sub.s of the skeleton voltage portion.
In the embodiment illustrated, the ratio indicator for W:C is a
differential coil instrument, the two coils of which at one end are
connected with the variable tapping K.sub.f and the other ends of
each of the coils are connected with the outputs OM and MS.sub.2
respectively.
The previously described method is, by means of the arrangement of
FIG. 7, carried out in the following manner.
A. ADJUSTMENT OF SKELETON COMPOSITION
a. The switch S.sub.w is closed. The adjustable tapping K.sub.s1 of
the potentiometer A.sub.s is adjusted until the indicator I.sub.s1
indicates the desired percent of stones of size S.sub.1, for
example the smallest size.
b. The variable tapping K.sub.s2 of the potentiometer B.sub.s is
adjusted until the desired percent ratio of stones of size S.sub.2
is readable on the indicator I.sub.s2. The latter adjustment also
automatically adjusts the analogue output voltage S.sub.3 to the
desired percent of the amount of stones of size S.sub.3 so that the
three amounts S.sub.1 +S.sub.2 +S.sub.3 =100 percent.
c. The switch S.sub.w is opened.
d. The variable tapping K.sub.s3 of the potentiometer D.sub.3 is
thereafter adjusted until the indicator I.sub.st indicates the
desired percent of skeleton in the entire amount.
B. ADJUSTMENT OF AIR IN THE MIXTURE IN PERCENT
In ready mixed concrete there is always a natural content of air of
between 1 and 2 percent and normally it will be sufficient to set
the air adjustment K.sub.L to 2 percent. By use of additives the
amount of air can be increased and if it is specified that
additives giving for example 5 percent air are going to be used in
the specific mixture, the adjustment K.sub.L should be set to 5
percent, whereby the output between the terminals OL and OM will
correspond to the adjusted amount of entrained air in the
mixture.
e. The air is accordingly adjusted by setting the variable tapping
K.sub.L.
Hereby the total batch analogue voltage has been disposed of with
respect to the skeleton and the air, and the remaining voltage
which is now disposable is between the terminals OM and OMS.
C. ADJUSTMENT OF STRENGTH AND SLUMP
The remaining adjustment is now to divide the remaining output
voltage between the output terminals OM and OMS according to
specified strength and slump which is done in the following
manner.
f. The tapping K.sub.f is adjusted until the desired water/cement
ratio is readable on the indicator I.sub.f which may be calibrated
directly according to the strength of the concrete.
Finally the tapping K.sub.w is adjusted until the specified amount
of water is readable on the indicator I.sub.w. Hereby the amounts
of gravel and cement are automatically readjusted and both amounts
can be read out on the instruments I.sub.c and I.sub.g and the
output voltages C and G correspond to the adjusted values.
After this procedure which can be completed in less than one minute
by a trained person all the analogue output voltages are adjusted
to respond to the desired amounts by volume of the components of
the mixture of a predetermined total amount, for example 1,000
litres which is the value to which the indicator I.sub.t is
supposed to have been set initially.
In the foregoing no attention was paid to the potentiometer
P.sub.kw shown in dotted lines in FIG. 7 and provided between the
variable tappings K.sub.w and K.sub.s3 of the potentiometers
P.sub.g and D.sub.3. The variable tapping K.sub.kw of this
potentiometer is connected with the input of an operational
amplifier DA, the other input of which is connected with the
variable tapping K.sub.w and which operates as a multiplicator.
When this arrangement is used the connection between the point x
and the output terminal M.sub.s2 is disconnected and the output of
the amplifier DA is connected directly with the output
M.sub.s2.
This arrangement serves the purpose of correcting the output
voltages W and G for a contents of water in the gravel which will
be found normally under practical conditions.
Obviously, if there is 5 percent water in the gravel and the
water/cement ratio is adjusted according to a predetermined
strength, the addition of gravel with 5 percent water will increase
the water contents and disturb the adjusted balance of the ratio
W:C with the result that the concrete strength will be reduced. In
such an event it is therefore necessary to reduce the analogue
value W between the terminal M.sub.s1 and M.sub.s2 with a
corresponding amount of water which is present in the gravel.
The content of water in the gravel can be measured in different
ways and if it is found that the content is for example 5 percent,
the variable tapping K.sub.kw of the potentiometer P.sub.kw is set
to 5 percent.
The output from the amplifier DA hereby divides the total analogue
voltage W+G in such a manner that the G-voltage is increased by 5
percent and the W-voltage is reduced corresponding to the volume of
5 percent gravel whereby the total volume is kept constant.
Instead of using a manually operable adjustment by means of the
potentiometer P.sub.kw it is possible to use an electronic network
such as a servo-multiplicator which is controlled by means of the
output voltage of an equipment which measures the contents of water
in the gravel so that an automatic correction for the content of
water in the gravel is obtained without the necessity of making any
manual adjustments.
In smaller mixing stations where the administration of each
component is effected under manual control, a remote control
instrument panel may be provided with indicators which give precise
instructions to the personnel about the amount of each individual
component. In such event each instrument should be calibrated to
show the exact amount of each component by volume or by weight
according to standard practice. In order to avoid mistakes with the
use of such a scheme, the instruments for the commands may be
digital instruments giving the amounts by weight or volume in exact
figures.
In most concrete mixing stations, however, automatic or
semiautomatic administration devices are used with weighing
stations for the components to be dispensed by weight and/or fluid
meters for components to be dispensed by volume. In such event the
proportioning or computing device according to the invention with
output voltage fractions each of which is the analogue value of one
component--which also may be derived from a triangle system to
which electrical output devices are added--lends itself to a
substantially complete automatic administration by combining the
application of analogue output voltages as amount control voltages
to the corresponding respective administration stations with
sequence control operable to select the stations in sequence one
after the other in response to the programmed completion of the
operation of each station.
In practice the use of the analogue output values from the
computing device to control automatic dispensing of the components
in a weighing station can be achieved by means of a device in the
weighing station which produces an analogue value which increases
as the dispensing proceeds, a differential which compares the
analogue value produced in the weighing station and control means
operable to interrupt the dispensing when the analogue values have
become equal.
Preferably a stepwise interruption of the dispensing will be used
in such a manner that the rate of dispensing will be decreased at a
predetermined stage of the dispensing such as at a predetermined
difference between the analogue value supplied by the computer and
the corresponding voltage supplied by the weighing stations such as
for example corresponding to dispensing of between 90 and 95
percent of the predetermined amount so as to thereby ensure against
overdispensing of any of the components.
Such a dispensing arrangement is shown schematically in FIG. 8 and
illustrates the arrangement in connection with the dispensing of
one of the components, for example the cement.
In FIG. 8, 50 is a silo with a closure member 52 the opening and
closing of which can be controlled by a control member 54 and which
can be partly closed from the open condition by means of a control
member 56.
When the closure member is open the material is guided from the
silo 50 along a chute 58 or in any other suitable manner to a
weighing device 60 with a scale 62 which indicates the amount of
material supplied to the weighing device.
An arrangement operable to produce a potential is connected with
the weighing device and comprises a voltage source BW and a
potentiometer P.sub.wg with a variable tapping K.sub.wg which is
moved by the movable parts of the weighing device as the dispensing
proceeds so as to thereby produce an increasing voltage C.sub.w
between the top of the potentiometer P.sub.wg and the variable
tapping K.sub.wg.
Obviously, when the analogue voltage C corresponding to the desired
amount of the component in question is supplied across the input
terminals I.sub.w1 and I.sub.w2 of the device, it is possible to
use a differential which compares the analogue input voltage and
the voltage produced by the weighing device and which interrupts
the dispensing when the desired amount is supplied to the weighing
device.
The voltage source BW is adjustable and is initially adjusted to a
value which by the dispensing of an amount of cement by weight
between the tapping K.sub.wg and the top end of the potentiometer
P.sub.wg produces a voltage C.sub.w which is equal to the analogue
input voltage between the terminals I.sub.w1 and I.sub.w2 when the
cement amount indicator I.sub.c which is calibrated according to
weight indicates the same amount of cement.
For practical reasons, however, it is necessary in the system to
include a multiplication amplifier in the form of an operational
amplifier OA with feedback over a potentiometer P.sub.oa by means
of which the multiplication factor of the amplifier can be
adjusted.
The reason is as follows:
As previously mentioned the analogue computer is constructed to
always give an analogue voltage portion corresponding to the values
of the individual components corresponding to a total batch volume
of for example 1 m..sup.3.
If a different total amount is specified by the customer it is
obviously necessary to provide for a proportional correction of the
amount of the individual components. Since the analogue input
voltage for the amount C of cement always corresponds to the amount
of cement in 1 m..sup.3, it is necessary if for example 3 m..sup.3
is requested to reduce the voltage produced by the weighing device
in the proportion 1:3 which can be obtained by adjusting the
potentiometer P.sub.wg of the amplifier OA to an amplification
factor corresponding to multiplication in proportion 1:3.
The output of the amplifier OA is connected with the input terminal
I.sub.w2 through a differential device indicated by way of a relay
R.sub.o with a normally closed contact K.sub.rd which is connected
with the control device 54 for closing the closure member 52. The
differential member R.sub.o is shunted by another differential
member R.sub.d which is provided with a bias in such a manner that
it will be actuated when the output voltage from the amplifier OA
has been increased to a value which is slightly less than the value
at which the differential device R.sub.o will respond. The relay
R.sub.d has a contact K.sub.rd which is normally closed and which
is opened to actuate the control device 56 to partly close the
member 52 when the device R.sub.d is actuated.
In the embodiment shown, the bias for the relay R.sub.d is produced
by supplying an alternating voltage across a potentiometer P.sub.r
between the variable tappings of which and the one end of the
primary winding of a transformer T.sub.r is connected with a
secondary winding in which a rectifier E.sub.r is connected.
The arrangement of FIG. 8 indicates schematically the arrangement
used for one of the components, for example the cement and it will
be appreciated that similar arrangements are used for the other
components and are adjusted from a central location such as from
the selector board 102 of FIG. 2 in which the control member
K.sub.x is operable to adjust the amplification factors of the
potentiometers as well as the tapping of the potentiometer P.sub.r
to thereby regulate the bias of the relays R.sub.d in accordance
with the ratio between the total amount to be dispensed and the
unit amount corresponding to the analogue values supplied from the
computing device.
By means of the ratio of the transformer T.sub.r and if necessary
by using an unlinear potentiometer P.sub.r it is possible to
control the part closing of the closure member 52 with substantial
uniform difference between actual amounts dispensed and desired
amounts without that difference being influenced by the total
amount.
The mode of operation of the arrangement of FIG. 8 is substantially
as follows:
When a dispensing switch such as indicated by SD of the selector
board of FIG. 2 is actuated, the closure member 52 of the silo is
opened and the dispensing starts.
As the dispensing proceeds, the tapping K.sub.wg of the
potentiometer P.sub.wg is moved and depending on the amplification
factor of the amplifier OA as adjusted by means of the proportion
selector member K.sub.x of the selector board of FIG. 2 the
analogue voltage C.sub.w produced by the weighing device is
converted into an analogue voltage C'.sub.w which is equal to the
unit value of the computing device. As the voltage C'.sub.w
increases the differential device R.sub.d will first be actuated
when the voltage supplied from the amplifier OA is slightly less
than the input analogue voltage or reference voltage C.
Hereby the contact K.sub.rd is opened and actuates the control
member 56 to partly close the member 52 so as to thereby decrease
the rate of dispensing of the component. When thereafter the
voltage C'.sub.w supplied by the amplifier OA has been increased to
be equal with the voltage C, the differential device R.sub.o is
actuated and actuates the control member 54 to close the member 52
and thereby interrupt the dispensing.
The other components are dispensed in a similar manner by means of
similar control arrangements either simultaneously by means of
individual weighing devices or in sequence controlled by a suitable
sequence control.
In concrete production it is possible to control the dispensing of
gravel and the skeleton components by using a single weighing
device to which the components are supplied from different silos by
connecting the differential devices R.sub.o and R.sub.d to be
actuated in cascade.
In the case of compensation for differences in quality of one of
the components such as difference in quality of cement, an
arrangement in FIG. 12 can be included in the computing device or
added to an existing computing device.
The arrangement of FIG. 12 provides for automatic adjustment of the
analogue value of that component of a mixture which varies with
respect to quality.
Obviously if a component of a mixture varies in quality from one
supply to the next, it is not necessary to use so much of the
component in a mixture when the quality is better as when the
quality is worse.
The arrangement of FIG. 12 enables a simple method for correcting
the dispensing in response to changes in the quality of one
component by using in the beginning the calculated analogue value
of the component in question as based on a known mixture and
adjusting a multiplication device in the analogue computer to the
ratio between two digital values which can be calculated from
proportions between the physical properties of the known mixture as
a master mixture or reference mixture and a test mixture produced
with a part of the component from a new supply.
In the following the arrangement of FIG. 12 will be described with
reference to concrete mixing.
In the production of ready mixed concrete it is necessary to
dispense the cement with a sufficient supply to ensure that the
nominal strength of the concrete is always obtained. The strength
of the concrete is governed by the coefficient of variation which
is the ratio between the crush strength of the concrete by standard
deviations and the middle crush strength. Variations in the
strength of the cement which can be quite substantial from supply
to supply increase the coefficient of variations substantially but
by uniform cement quality the coefficient of variation is reduced
whereby the otherwise necessary strength margin can be reduced and
result in savings of cement.
The proportion between the strength of a known mixture and a
mixture to be produced subsequently can be expressed by the ratio
between two digital values.
The crush strength of a concrete mixture after 28 days can be
calculated by using Bolomey's formula
in which .sigma. is the crush strength for example in kg/cm..sup.2,
K is a constant which primarily depends on the strength of the
cement, C is the cement by weight and W is the water by weight.
For each new mixture it is possible to determine the factor K by
means of a test moulding and using an accelerated test method used
by those skilled in the art and one of which is referred to as the
Jespersen-method which will give the result in about 2 hours.
By making such a test with cement of one supply and inserting the
values in Bolomey's formula it will be found that
in which .sigma..sub.m, K.sub.m and C.sub.m are strength, K-factor
and amount of cement in this mixture which can be used as the
reference mixture.
With the next supply of cement a corresponding test is made with
the same amount of cement C.sub.m as in the reference mixture
whereby other values of strength and factor K are found, namely
Since it is desired to obtain the same physical property, namely
the strength, this means that the following conditions must be
fulfilled:
.sigma..sub.m =.sigma..sub.cn
If the amount of cement of different quality which is necessary in
order to obtain the same strength is called C.sub.na and this value
is inserted in Bolomey's formula for .sigma..sub.cn the condition
is
By solving this equation it is possible to calculate the amount
C.sub.na of cement which must be used in the mixture with cement of
quality according to the new supply as
As apparent from this formula the proportion between the necessary
amount of cement of new quality and cement of old quality is
basically determined by the proportion between the two factors
K.sub.m and K.sub.cn.
It is therefore possible to proceed in such manner that after
having calculated this proportion which can be referred as the
ratio between physical properties of the reference mixture and the
new mixture, the analogue value of the amount of cement in the
reference mixture can be found by multiplying with this ratio after
consideration of the other digital values of the formula in order
to produce an analogue value of the amount of cement which is
corrected to comply with the cement quality of the new mixture.
Hereby the same physical properties will substantially be obtained
by means of the new cement quality in the new mixture.
The computing device of FIG. 12 is especially constructed for this
method in connection with concrete mixing.
In FIG. 12 AC is an analogue computing device with input terminals
I.sub.1 and I.sub.2 for reading in the analogue values of the
amount C.sub.m of cement which is necessary in the reference
mixture with the known factor K.sub.m and with input terminals
I.sub.2 and I.sub.3 for reading in the analogue amount of water
W.sub.m.
As indicated in FIG. 12 in dotted lines the ratio between water and
cement can be adjusted on a potentiometer P.sub.f so that the
calculation device of FIG. 12 can be directly connected with a
computing device of FIG. 7. The analogue computing device of FIG.
12 may, however, also be used in connection with other kinds of
devices which are able to produce analogue values corresponding to
the desired amounts of cement and water in a reference mixture.
The arrangement of FIG. 12 is provided with an adjustable control
member K.sub.RAT which is also shown as an adjustment member in
FIG. 2 for adjusting the ratio K.sub.m :K.sub. cn and output
terminals O'.sub.c and O".sub.c for reading out analogue value
C.sub.na of the amount of cement which is to be used in the new
mixture with quality of the new supply. The arrangement also has
output terminals O'.sub.w and O".sub.w for reading out the amount
of water W.sub.m. Preferably the amount of water is kept constant
in order to secure the same slump of the new mixture as of the
reference mixture.
Between the input terminals I.sub.1 and I.sub.2 and the outputs
O'.sub.c and O".sub.c an analogue multiplicator is provided which
when the ratio K.sub.m :K.sub. cn is adjusted by means of the
member K.sub.RAT automatically gives the correct analogue value of
cement C.sub.na.
If the specific gravity of cement which is 3.15 is inserted in the
last of the formulas hereabove, the following expression for the
amount of cement C.sub.na by volume is found as
By means of the system of voltage dividers shown in FIG. 12 where
the input voltage W.sub.m is divided by means of two resistors
R.sub.1 and R.sub.2 and the potential between the point a between
these two resistors and the input terminal I.sub.1 is divided by
means of two resistors R'.sub.3 and R".sub.3, it is possible to
obtain such voltage proportions that the potentiometer R.sub.a can
be calibrated in accordance with the ratio K.sub.m :K.sub. na.
OA is an operational amplifier which is connected as a
multiplicator.
This can be understood in the following manner:
It is required that the potential between the terminals I.sub.1 and
I.sub.2 should be proportional with the expression in parenthesis
in the formula, i.e. proportional with C.sub.m -0.159.sup.. W so as
to obtain direct proportionality with adjustment of the
potentiometer R.sub.a between the input on the terminal I.sub.2 and
the output on the terminal O'.sub.c. The potential which must be
added to the expression in parenthesis is 0.159.sup.. W and this
potential must be applied between the input terminal I.sub.2 and
the output terminal O'.sub.c. This condition can be obtained by the
following proportion between the resistors R.sub.1 and R.sub.2
by proportioning the resistors R.sub.1 and R.sub.2 in this manner a
voltage across the resistor R.sub.1 is obtained which is equal to
0.159 .sup.. W and between the point a and the input terminal
I.sub.1 a voltage is obtained corresponding to C.sub.m +0.159.sup..
W.
By using equal values of the resistors R'.sub.3 and R".sub.3 this
voltage will be divided into two equal portions which means that
across the resistor R".sub.3 a voltage is provided which is
1/2(C.sub.m - 0.159.sup.. W) which multiplied by 2.sup.. K.sub. m
/K.sub. cn gives the first part of the expression in the analogue
value for C.sub.na.
If the potentiometer R.sub.a is adjusted to a ratio the voltage
across the potentiometer R.sub.a is
By calibrating the potentiometer in such a manner that
the total voltage between the output terminals O'.sub.c and
O".sub.c will be equal to the expression for C.sub.na because the
output voltage is composed by the voltage across the potentiometer
R.sub.a and the resistor R.sub.1 of the voltage divider R.sub.1,
R.sub.2.
When K.sub.cn>K.sub.m, i.e. when the cement quality is improved,
the analogue value C.sub.na is decreased and a saving is
obtained.
When K.sub.cn <K.sub.m, i.e. when the quality is decreased, the
amount C.sub.na is increased to obtain the same quality of the
mixture.
As mentioned the analogue output values are calculated by volume.
Since the volume of water the analogue of which is the same between
the output terminals 0'.sub.w and 0".sub.w as between the input
terminals I.sub.2 and I.sub.3 and since it is always desired to
deliver a volume unit, the system is also adapted to automatically
recalculate the analogue value of such a third component of the
mixture the amount of which can be allowed to be increased or
decreased in response to decreasing or increasing of the amount of
cement.
Such third component is the gravel in a concrete mixture and in the
case of relatively minor changes in the amount of cement a
corresponding increase or decrease of the amount of gravel does not
cause any change of the slump beyond allowable limits. Otherwise,
it is possible within the scope of the invention to use a special
filler to replace the cement when required.
FIG. 13 illustrates an embodiment of the analogue computing device
according to the invention in which an analogue value G
corresponding to a predetermined amount of gravel to be used in the
mixture is supplied to input terminals I.sub.4 and I.sub.5, e.g.
derived from a voltage divider in a system as disclosed.
The embodiment of FIG. 13 modifies the output of the analogue value
G by adding thereto the numerical value of C.sub.m -C.sub.na.
In the arrangement of FIG. 13 a differential amplifier DA.sub.1 is
connected between the input terminal I.sub.4 and an output terminal
0'.sub.g. The amplifier DA.sub.1 has four inputs i.sub.l, i.sub.2,
i.sub.3 and i.sub.4 of which .sub.1 and i.sub.3 are connected with
the input terminals I.sub.1 and I.sub.2 respectively whereby the
voltage difference between the inputs i.sub.1 and i.sub.3 is equal
to C.sub.m. The inputs i.sub.4 and i.sub.2 are in a similar manner
connected with the output terminals O'.sub.c and O".sub.c
respectively whereby the voltage across the inputs i.sub.2 and
i.sub.4 is equal to C.sub.na. According to the mode of operation of
such differential amplifiers its output G.sub.1 between the
terminals O'.sub.G and O".sub.G is
G.sub.1 =i.sub.1 +i.sub.2 -i.sub.3 -i.sub.4 =(i.sub.1 -i.sub.3)-
(i.sub.4 -i.sub.2)= C.sub.m -C.sub.na.
This means that the numerical value of C.sub.m -C.sub.na is added
to the analogue value G. In other words, if the cement quality is
increased less cement is included in the mixture (C.sub.na
decreases) and more gravel is added to make up for the missing
amount of cement. If the cement quality decreases compared with the
master mixture, C.sub.m -C.sub.na becomes negative, more cement is
added to the mixture and the amount of gravel is decreased in order
to keep the volume constant.
It will be understood that the invention is not limited to the
embodiments shown and described hereinbefore.
A modification of a simple mechanical geometrical system with one
triangle is illustrated in FIG. 9. The triangle is, as in FIG. 6,
constructed with two relatively stationary rails M.sub.a and
M.sub.b, the ratio determining lever K.sub.f pivotable about the
fixed point A and the parallel displaceable rail M.sub.c. On each
of the rails a guide member GU.sub.1, GU.sub.2 and GU.sub.3
respectively is slidably mounted. Each guide member has a guide
channel which extends perpendicularly to the direction of the
respective rail and in each of which a reciprocable member C, W and
G is mounted, each of which represents one of the "rulers"
hereinbefore mentioned. To each ruler is assigned a thermometer
type indicator I.sub.c, I.sub.w and I.sub.g on an indicator panel
and between each of the reciprocable members and its associated
indicator a transmission TR.sub.c, TR.sub.w and TR.sub.g
respectively is provided to operate each indicator to show a value
which is equal to or proportional to that length of the
appertaining ruler member which extends inside the triangle. The
transmission may be mechanical, hydraulic or of any other
convenient type and include suitable amplification means to provide
for a longer movement of the "thermometer columns" than of the
ruler members.
In FIG. 9 the indicator panel also includes an indicator I.sub.t
for the total amount represented by the height of the triangle
adapted to be actuated through a transmission TR.sub.rt from a
reciprocable member which is actuated by engagement with the rail
M.sub.c and is movable in a guide GU.sub.t.
An abutment PT which may be a pin of equilateral triangular cross
section is slidably mounted on the lever MR.sub.f preferably
against sufficient friction to keep it in any position to which it
is adjusted. Alternatively the abutment PT may be fixed on the
lever MR.sub.f which in such event is reciprocable relatively to
the fixed point A by means of a pin-and-slot connection.
Each "thermometer" may have two or more graduations, e.g.
indicating volume as well as weight of a material with a
predetermined specific gravity.
It is also possible within the scope of the invention to construct
the calculation aid which has the character of a slide rule based
on he geometry explained. A part of the slide rule embodying the
invention is shown in FIGS. 10 and 11.
In order to facilitate the understanding of the structure of FIG.
10, also the triangle with its two sides M.sub.a and M.sub.b and
with its displaceable side M.sub.c is shown, although it will be
obvious that in the practical embodiment only the members which are
reciprocable perpendicular to the side of the triangle are
necessary.
The device of FIG. 10 is mounted on a support SU which may be a
board or a sheet of plactics material. The graduated scale S.sub.f
for the f-ratio is printed on the support and the pivotable lever
K.sub.f is reciprocable relatively to the point A as explained with
reference to FIG. 9 with the abutment PT in the form of a pin
firmly secured on the lever K.sub.f. On the support a bracket
BR.sub.1 is secured with a middle portion which extends parallel
with and slightly spaced from the top surface of the support, so as
to form with the support a guide channel for an elongated
rectangular sheet member S.sub.w of a width which is not much less
than the extension of the side of the triangle, perpendicular to
which the sheet member can slide. A similar arrangement is made
with respect to the other side M.sub.a of the triangle with a
second bracket BR.sub.2 and another slideable sheet member S.sub.c.
As indicated in FIG. 10 the interior ends of the reciprocable sheet
members S.sub.w and S.sub.c engage the abutment PT. Obviously, the
sheet members represent the slideably rulers and by providing
graduations GU.sub.w and GU.sub.c on the sheet members and making
the graduations readable, the analogue values C and W can be read
directly.
In a practical embodiment shown in FIG. 11, which illustrates a
part of the device of FIG. 10, the guide member BR may be of
transparent material such as Perspex with a line RL engraved
thereon for the purpose of reading the graduation GU.sub.w which
may be graduated in analogue values of the amount. In addition a
further plurality of graduations GU.sub.2, GU.sub.3 and GU.sub.4
may be engraved on the slideable sheet member with the further
graduations enabling the amount of the volume of the graduation
GU.sub.w to be read out of the device in different terms, such as
for example weight or other properties. By way of example one
graduation may give the volume of water in litres and another the
volume in gallons, and in order to select the graduations a slide
S.sub.H with a window may be moveable on the bracket BR transverse
to the ruler S.sub.w.
For using the device in calculating concrete a further graduation
of the slideable sheet member may show the slump, so that the
mixing operator can read the correct amount of water directly into
the device by adjusting the water slide merely to the desired
slump.
It will be appreciated that in the device a third slide may be
moveable perpendicularly to the third side of the triangle and that
for a composition with seven components a slide rule device
constructed according to FIG. 10 will include six slides assigned
to two triangles as well as displaceable members with lines
engraved thereon.
* * * * *