U.S. patent number 3,611,819 [Application Number 04/840,258] was granted by the patent office on 1971-10-12 for motion-transmitting arrangement.
This patent grant is currently assigned to Zuse KG. Invention is credited to Manfred Hoppe, Walter Jager, Jurgen Muller.
United States Patent |
3,611,819 |
Muller , et al. |
October 12, 1971 |
MOTION-TRANSMITTING ARRANGEMENT
Abstract
A drafting head of a drafting apparatus is mounted for
to-and-fro movement in a predetermined direction. A flexible
elongated rope is connected to the drafting head for exerting pull
thereon to thereby move it in this predetermined direction. A
rotatable drum is mounted for rotation about its axis and has the
rope convoluted about its circumference. The drum includes a
radially expansible annular member and end disks cooperating
therewith for expanding and contracting it so as to vary the
diameter of the drum; a drive serves to rotate the drum about its
axis.
Inventors: |
Muller; Jurgen (Bad Hersfeld,
DT), Hoppe; Manfred (Friedlos, DT), Jager;
Walter (Heimboldshausen, DT) |
Assignee: |
Zuse KG (Bad Hersfeld,
DT)
|
Family
ID: |
5710031 |
Appl.
No.: |
04/840,258 |
Filed: |
July 9, 1969 |
Foreign Application Priority Data
|
|
|
|
|
Oct 9, 1968 [DT] |
|
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P 18 01 973.3 |
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Current U.S.
Class: |
74/89.22; 33/1M;
474/54; 346/139B |
Current CPC
Class: |
F16H
37/126 (20130101); B23Q 1/621 (20130101); F16H
19/06 (20130101); D05B 21/00 (20130101); Y10T
74/18848 (20150115); F16H 2019/069 (20130101) |
Current International
Class: |
B23Q
1/25 (20060101); F16H 35/00 (20060101); B23Q
1/62 (20060101); D05B 21/00 (20060101); F16H
19/00 (20060101); F16h 055/52 () |
Field of
Search: |
;74/89.22,568H,568CT,1,230.21,230.16 ;33/1M |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: O'Dea; William F.
Assistant Examiner: Shoemaker; F. D.
Claims
What is claimed as new and desired to be protected by Letters
Patent is set forth in the appended claims:
1. An arrangement of the character described, comprising a first
element mounted for to-and-fro movement in a predetermined
direction; a flexible elongated second element connected to said
first element for exerting pull thereon and moving said first
element in said predetermined direction; rotatable drum means
mounted for rotation about its axis, said second element being
convoluted about said drum means and the latter comprising a
radially expansible annular first member having opposite ends, a
pair of axially spaced second members just receivable in the
respective open ends, and axially inwardly converging cam faces on
at least one of said first and second members; varying means on
said drum means for effecting relative axial movement of said
second members and for thereby varying the diameter of said drum
means; and drive means operative for rotating said drum means about
said axis thereof.
2. An arrangement as defined in claim 1, wherein said second
members are parallel disc members coaxial with said axis and spaced
from one another in direction thereof, said cam faces being
bevelled edge faces provided on the respective disc members and
each conically diverging in direction away from the respective
other disc member; said opposite open axial end of said radially
expansible annular first member being dimensioned so as to just
accommodate the smallest diameter of the respective disc
members.
3. An arrangement as defined in claim 1, said varying means
comprising a coaxial rod fast with one of said second members and
having an end portion extending through a coaxial aperture in the
other of said second members; and abutment means on said end
portion at the outer axial side of said other second member and
shiftable axially thereon so as to displace said other second
member towards said one second member in response to shifting of
said abutment means towards said one second member.
4. An arrangement as defined in claim 1, wherein said annular first
member is of one piece.
5. An arrangement as defined in claim 1, wherein said annular first
member is of one piece and circumferentially incomplete.
6. An arrangement as defined in claim 4, wherein said annular first
member consists at least in part of synthetic plastic material.
7. An arrangement as defined in claim 1, wherein said annular first
member is composed of a plurality of discrete sections connected to
one another.
8. An arrangement as defined in claim 1; and further comprising
biasing means permanently urging said second members axially away
from one another.
9. An arrangement as defined in claim 8, said biasing means being a
pressure spring arranged within the confines of said annular member
and bearing against said second members concentrically
therewith.
10. An arrangement as defined in claim 1, wherein said annular
member consists of synthetic plastic material.
11. An arrangement as defined in claim 1, wherein said first and
second members are both provided with cooperating ones of said cam
faces.
12. An arrangement as defined in claim 11, wherein said cam faces
are annular faces surrounding said axis of said drum means and
constituting surfaces of rotation.
13. An arrangement as defined in claim 1; and further comprising a
radially expansible cylindrical sleeve surrounding said annular
member so as to vary in diameter in response to variations in the
diameter of said annular member.
14. An arrangement as defined in claim 13, wherein said sleeve is
of one piece.
15. An arrangement as defined in claim 13, wherein said sleeve is
composed of a plurality of discrete connected sleeve sections.
16. An arrangement as defined in claim 1, said annular member
having a cylindrical circumferential surface and being provided
with a plurality of axial slots extending in parallelism with the
generatrices.
17. An arrangement as defined in claim 16, wherein said slots
extend axially inwardly from the opposite ends of said axial
member, the slots at one of said opposite ends being
circumferentially offset with respect to the slots at the other of
said axial ends.
18. An arrangement as defined in claim 3, said abutment means
comprising nut means; and said nut means and said end portion of
said rod being provided with cooperating screw threads.
19. An arrangement as defined in claim 1, and further comprising
securing means securing said flexible member to said drum means
against slippage relative thereto.
Description
BACKGROUND OF THE INVENTION
The present invention relates generally to a motion-transmitting
arrangement, and more particularly to an arrangement for driving a
flexible element to thereby transmit motion to an element connected
with a flexible element.
The present invention will be described hereafter with respect to a
drafting apparatus. However, we wish it to be understood that this
is merely an exemplary description for purposes of better
understanding, and is not to be considered a limitation of the
invention to this particular type of arrangement.
A drafting apparatus is known wherein a so-called bridge member is
movable in a first direction and carries a drafting head, provided
with drafting pens which engage paper located below the drafting
head, which drafting head is movable along the bridge member is a
second direction normal to the first direction. Movement of the
bridge member and the drafting head is accomplished by providing
two drums about which two ropes or lines or similar elongated
flexible elements are convoluted which are suitably secured with
the bridge member and the drafting head, respectively. Each of the
drums is driven in rotation by its associated motor.
Each rotation of one of the drums responds to a shifting of the
associated member, that is either the bridge member or the drafting
head. Accordingly, because the drafting head is carried by and on
the bridge member, the rotation of either one of the drums results
in shifting of the drafting pen or pens carried by the drafting
head and in making of a line on the drafting paper located below
the bridge member and the drafting head. For this reason, and in
order to assure the desired accuracy in the drafting which is made
by means of such an apparatus, the drums for the elongated flexible
elements must be precisely machined. This, however, makes these
relatively expensive and, as has been established, the drafting
accuracy which can be obtained is particularly good even then.
A further prior art construction of a drafting apparatus again
utilizes the principle of effecting shifting of the drafting pen by
means of elongated flexible elements. In addition, however, there
is a constant automatic correction of the shifting of the drafting
pen in dependence upon the angular position of the drums associated
with the elongated flexible elements. In this construction, the
elongated flexible elements are convoluted about the roller mounted
on a level, with deflection of the pivotable level being and
providing the desired correction. However, this requires a
relatively great technological expenditure if the requisite
accuracy of corrections is to be obtained. Aside from this, the
construction in question necessitates the use of spring members
which may result in vibrations intermediate the drum and the
drafting pen which in turn may lead to increased difficulties in
maintaining the desired drafting accuracy.
SUMMARY OF THE INVENTION
It is a general object of the present invention to overcome the
aforementioned disadvantages.
A more particular object of the present invention is to provide a
motion-transmitting arrangement which, employed in apparatus of the
type in question or in apparatus analogous to it, avoids the
disadvantages described with respect to the prior art.
A further object of the present invention is to provide an
arrangement of the type in question which avoids the aforementioned
disadvantages while requiring only small technological
expenditures.
An additional object of the invention is to provide such an
arrangement which requires no components which could produce or aid
to the production of vibrations.
In pursuance of the above objects, and others which will become
apparent thereafter, one feature of my invention resides, briefly
stated, in an arrangement of the type in question which comprises a
first element mounted for to-and-fro movement in a predetermined
direction, and a flexible elongated second element which is
connected to the first element for exerting pull thereon and for
moving the first element in the aforementioned predetermined
direction. Rotatable drum means is mounted for rotation about its
axis, and the second element is convoluted about the drum means.
Varying means is provided on the drum means for varying the
diameter of the same, and drive means is operative for rotating the
drum means about its axis.
Thus, according to the invention, a variation in the diameter of
the drum provides in simple manner for shifting of the first
element-- which may be the bridge element and/or the drafting head
of the drafting apparatus--in dependence upon the angular position
of the drum. A variation in the diameter of the drum can be
effected in simple manner with great accuracy.
The novel features which are considered as characteristic for the
invention are set forth in particular in the appended claims. The
invention itself, however, both as to its construction and its
method of operation, together with additional objects and
advantages thereof, will be best understood from the following
description of specific embodiments when read in connection with
the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a diagrammatic plan view of a drafting apparatus
embodying the present invention;
FIG. 2 is a diagrammatic longitudinal section through a drum
according to the present invention;
FIG. 3 is a fragmentary end elevational view of a drum constructed
in accordance with FIG. 2;
FIG. 3a is an axially section through FIG. 3;
FIG. 4 is a view analogous to FIG. 3 but having a complete
end-elevational view of the drum;
FIG. 5 is a fragmentary developed view of a portion of the
circumference of the drum shown in FIGS. 3-4; and
FIGS 6-8 are somewhat diagrammatic cross-sectional views
illustrating further embodiments of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Discussing firstly FIG. 1, it will be seen that for purposes of
explanation we have shown an invention embodied in a drafting
apparatus which is generally identified with reference numeral 1.
Drafting paper, on which a drawing is to be made, is identified
with reference numeral 2 and the apparatus comprises a bridge
member of first element 3 which is movable in the direction
identified with the arrow x. The bridge member 3 carries a drafting
head 4 which is movable on and with reference to the bridge member
3 in the direction identified with arrow y. Holding means 5 is
provided on the drafting head 4 and holds one or more drafting pens
which are well known to those skilled in the art and are not
illustrated in detail because they do not form a part of the
present invention.
Reference numerals 6x and 6y identifies two motors, such as
electromotors, reference numerals 7x and 7y two drums each of which
is to be driven by one of the motors 6x and 6y, and reference
numerals 8x and 8y identify two lines or ropes each of which is
convoluted about one of the lines or ropes each of which is
convoluted about one of the drums 7x and 7y. There are also
provided a plurality of reversing rollers which are illustrated but
not designated with reference numerals. How the motors can be
reversed in their operation, so that the bridge member 3 and the
drafting head 4 may move to-and-fro, is well known to those skilled
in the art and therefore not illustrated, particularly because it
does not constitute a part of the present invention.
It is, however, pointed out that the rope 8x is connected with the
bridge member 3 at the locations 9 and 10. It is also convoluted
about the drums 7x which is driven by means of the motor 6x.
Rotation of the drums 7x therefore causes movement of the bridge
member 3 in the direction of the arrow x. Rope member 8y is
connected with the base of the apparatus 1 at the locations 11 and
12 and is convoluted about the drum 7y which is driven in rotation
by the motor 6y. Thus, the drawing head 4 is shiftable with respect
to the bridge member 3 in the direction of the arrow y. Evidently,
reversing rollers are associated with the ropes 8x and 8y, as
mentioned before.
Thus, rotation of the drums 7x and 7y causes movement of both the
drafting head 4 and the bridge member 3 in the direction of their
respectively associated arrows so that a drafting pen carried by
the holder member 5 which is provided on the drafting head 4,
performs a movement which is provided on the drafting head 4,
performs a movement which is dictated by the components of movement
of the members 3 and 4, and draws a corresponding line on the
drafting paper 2. With a given change in the angle of rotation of
the axis of the motors 6x and 6y, shifting of the drafting head 4
is dependent upon the diameter of the drums 7x and 7y. If a
drafting accuracy of 0.2 millimeter or less is required, and if a
given area limit on the drafting paper 2 must not be exceeded, then
it is advantageous to employ the present invention which makes it
possible to adjust the diameter of the drums 7x and 7y.
How this can be accomplished is diagrammatically illustrated in
FIG. 2. The drum shown there is composed of two ends discs 14 and
15 and an annular member 17 located between the end discs 14 and
15. The end y14 and 15 are provided with edge faces which are
constructed as surfaces of rotation and which taper concentrically
towards the axis 16 of the drum in inward direction. The open ends
of the annular member 17 are so dimensioned that the end discs 14
and 15 can enter only partly into the open ends. A suitable device,
to be described later in more detail, serves to press the end discs
14 and 15 inwardly towards one another in direction of the arrows
F1 and F2, respectively. The thus-exerted forces, in conjunction
with the conical configuration of the dam faces or surfaces of
rotation provided on the end disc 14 and 15, tend to radially
extend expand to annular member 17 and to increase the diameter
thereof within the elastic limits. Evidently, movement of the end
discs 14 and 15 in the direction opposite the arrows F1 and F2,
respectively, results in a decrease in the diameter of the annular
member 17.
FIGS. 3, 3a and 4 illustrate in detail a drum constructed in
accordance with the principle of FIG. 2 and suitable for use as one
of the drums 7x, 7y of the apparatus shown in FIG. 1. A shaft, on
which the drum is mounted for rotation, is identified with
reference numeral 20. Mounted on this shaft are two conically
configurated members 21 and 22 which taper inwardly in direction
towards one another. An annular member 23 surrounds the members 21
and 22. Bushings 24 and 25 are provided, screws 26 and 27 serve to
secure the ends of the rope 32 in the manner still to be described,
a nut 30 is threaded onto an externally threaded portion of a hub
constituting a part of the member 21 with a washer 29 interposed
between the hub and nut 30, and an expansion spring 28 urges the
members 21 and 22 axially apart.
It will be appreciated that the member 22 is shifted in direction
of the arrow F2 towards the member 21 if the nut 30 is turned in a
sense threading it deeper onto the hub portion of the member 21.
Because of the conically configurated cam faces of the members 21
and 22, such shifting in the direction of the arrow F2 results in
radial expansion of the annular member 23 within the elastic limits
of the same. In the illustrated embodiment, the diameter of the
annular member 23 is approximately 50 millimeters and the diameter
may be varied within a range of between zero and substantially 1
millimeter because it is essential that the diameter increase be
capable of being reversed in simple and ready manner, the expansion
spring 28 is provided which, when the nut 30 is again loosened,
moves the members 21 and 22 axially apart, thereby permitting the
diameter of the annular member 23 to decrease. If the annular
member 23 is of a material whose inherent elasticity is relatively
high, and if certain structural requirements obtain with respect to
the frictional contact between the members 21 and 22 on the one
hand, and the annular member 23 on the other hand, it is possible
to eliminate the expansion spring 28. In this context it is pointed
out that it is not only the contact surfaces on the members 21 and
22 which taper conically, but that the corresponding surfaces on
the inside of the annular member 23 are complementarily
configurated, as is clearly evident both from FIG. 3a and the
diagrammatic illustration in FIG. 2. However, this is not
absolutely necessary and the diameter variation can also be
obtained if there are tapering contact surfaces only on the members
21, 22 or on the member 23.
As shown in FIG. 3a, the rope or line 32 is convoluted about the
circumference of the annular member 23 and has one of its ends
secured in the bushing 24 via the screw 26, whereas its other end
is secured in the bushing 25 via the screw 27. This manner of
securing the rope 32 is not absolutely necessary, and it will be
possible simply to convolute it about the circumference of the
annular members 23 so that the rope 32 is frictionally entrained.
However, the solution shown in FIG. 3a has the advantage that there
is no slippage between the rope 32 and the annular member 23. It is
evident, of course, that intermediate its two connected ends the
rope 32 is trained about the various reversing rollers mentioned
with respect to FIG. 1 and connected with the base of the apparatus
1 or the bridge member 3, depending upon whether the rope 32
corresponds to the rope 8y or 8x in FIG. 1.
The axis 20 is driven in rotation in suitable manner, for instance
by a motor which is not shown in FIGS. 3-4 but which may correspond
to one of the motors 6x or 6y of FIG. 1. The friction between the
contact surfaces of the members 21 and 22 on the one hand and those
of the annular member 23 on the other hand is so large that the
annular member 23 will be turned in rotation when the shaft 20
turns, without undergoing any slippage. As FIG. 3, the hub 21b is a
separate element from the member 21, but the latter is a pushed
onto one end of the hub 21b, as shown. The hub 21b, on the other
hand, is pressed-fitted on the shaft 20, although evidently it
would also be possible to key it to be the shaft 20. The screw
threads provided on the hub 21b and with which the nut 30 meshes,
are of very low pitch in order not only to provide for self-locking
of the nut 30, but also to assure that relatively large turning
movements of the nut 30 permit relatively small diameter variations
of the annular members 23. An extension of the hub 21b is provided
with surfaces 21c which serve to retain the hub 21b and thereby the
shaft 20 against rotation when the nut 30 is tightened or loosened.
Bores or analogous recesses 33 provided in the member 22 (compare
FIGS. 3 and 3a) afford access to the screws 26,27.
FIG. 5, finally, shows a further embodiment of the invention, and
in fact a preferred embodiment of the configuration of the annular
member 23. It this embodiment the annular member 23 is provided
with slots or cutouts 34 extending inwardly from opposite axial
sides in parallelism with the generatrices 34 but being so offset
relative to one another in circumferential direction that each slot
at one axial side is located intermediate to adjacent slots at the
other axial side. While the annular member 23 may be made of
different materials, including synthetic plastic material, the one
illustrated in FIG. 5 advantageously consists of steel and has been
found to, one the one hand, have considerable elasticity, but on
the other hand, to be capable of being manufactured economically
but with considerable accuracy. It is particularly well-suited for
use in a drum which is to be used in a drafting table of the type
shown in FIG. 1.
It is also possible to construct the annular member 23 of several
sections, for instance of a plurality of rods or, as shown in FIG.
8, of shell-shaped members 23b, 23bb extending in parallelism with
the axis 20 and together constituting a member corresponding to the
annular member 23. They would, of course, have to be connected in
suitable manner as shown at 23b' but this is a simple matter for
those skilled in the art.
Under certain circumstances, particularly if the annular member 23a
should be made of elastically deformable synthetic plastic material
as for instance in FIG. 6, it might be advisable to surround it
with a cylindrical protective sleeve which would be intended to
counteract possible deformation of the annular member by the rope
32. Such a sleeve again could consist of a single section 70 as
shown in FIG. 7, or of a plurality of sections 60a, 60b which are
connected at 60c as in FIG. 6. It would, of course, have to be able
to undergo diameter variations in the same manner as the annular
member 23.
A further possibility would be to construct the annular member 23
as a circumferentially incomplete member 23a as shown in both FIGS.
6 and 7, that is to provide it with an axially extending slot
23a'.
We wish to reiterate that the present invention is by no means
limited to use in conjunction with a drafting apparatus of the type
shown in FIG. 1, or even to an arrangement wherein motion is
transmitted in the same manner as in FIG. 1. However, where the
arrangement requires motion transmission in the same manner as in
FIG. 1, it is also evident that motion may be transmitted not only
for moving a drafting pen, but also for moving an engraving stylus,
a tool carrier or in fact any other member which must be moved with
precision.
It will be understood that each of the elements described above, or
two or more together, may also find a useful application in other
types of constructions differing from the types described
above.
While the invention has been illustrated and described as embodied
in a motion-transmitting arrangement, it is not intended to be
limited to the details shown, since various modifications and
structural changes may be made without departing in any way from
the spirit of the present invention .
* * * * *