U.S. patent number RE34,559 [Application Number 07/501,741] was granted by the patent office on 1994-03-08 for diagnostic method for analyzing and monitoring the process parameters in the operation of reciprocating equipment.
Invention is credited to John Mickowski.
United States Patent |
RE34,559 |
Mickowski |
* March 8, 1994 |
Diagnostic method for analyzing and monitoring the process
parameters in the operation of reciprocating equipment
Abstract
The method of the present invention utilizes a microcomputer in
combination with a CRT and a multiplicity of transducers for
monitoring process parameters in the operation of a reciprocating
device having a linear stroke. A profile of the process parameters
including pressure and velocity are generated as a function of
stroke length and time and are stored in a non-volatile memory and
graphically displayed on the CRT as master traces for comparison
with current data profiles. The velocity is calculated by dividing
distance transversed with time or by use of a velocity position
transducer.
Inventors: |
Mickowski; John (Warwick,
NY) |
[*] Notice: |
The portion of the term of this patent
subsequent to March 12, 2009 has been disclaimed. |
Family
ID: |
26967193 |
Appl.
No.: |
07/501,741 |
Filed: |
March 29, 1990 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
292168 |
Aug 12, 1981 |
4504920 |
Mar 12, 1985 |
|
Reissue of: |
710046 |
Mar 11, 1985 |
04734869 |
Mar 29, 1988 |
|
|
Current U.S.
Class: |
702/183;
264/40.7; 345/16; 345/672; 425/169; 700/206 |
Current CPC
Class: |
G01D
3/08 (20130101); G01D 21/02 (20130101); G01L
1/2256 (20130101); G01L 5/0076 (20130101); G01P
3/54 (20130101); G05B 19/4063 (20130101); G07C
3/00 (20130101); G01P 3/52 (20130101); Y10S
482/902 (20130101) |
Current International
Class: |
G01L
1/22 (20060101); G01P 3/54 (20060101); G01P
3/52 (20060101); G01L 5/00 (20060101); G01P
3/42 (20060101); G01D 21/02 (20060101); G01L
1/20 (20060101); G05B 19/4063 (20060101); G05B
19/406 (20060101); G06F 015/46 (); G01D
003/08 () |
Field of
Search: |
;364/473,476,521,550,551.01,551.02,552 ;425/149,150,169
;264/40.1,40.7 ;73/865.9 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
0018551 |
|
Apr 1983 |
|
EP |
|
0126174 |
|
Feb 1984 |
|
EP |
|
2615445 |
|
Nov 1977 |
|
DE |
|
3142811 |
|
Jul 1983 |
|
DE |
|
Other References
Lousanne, "Process Control: Now It's an Aid in Everylay Injection
Molding", 9 Modern Plastics In., No. 3, pp. 13-15, (Mar. 1979).
.
"Here's A Profitable Alternative to Trail-and-Error Die Casting",
Honeywell, Test Instruments Division, Advertisement, (1979). .
"Australian Research for the Die Casting Industry," Die Casting
Engineer, pp. 14-24, 1980. .
"Predicting Shot Speed Using A Programmable Calculator," Die
Casting Engineer, pp. 42-44. .
"Assessing the Performance of Metal Feed Systems," 9th SDCE
International Die Casting Exposition and Congress, Paper No.
G-T77-071 (1977). .
"Shot Monitoring Instrument," Die Casting Engineering, pp. 35-36,
1981. .
"A Building Block Approach to Shot End Monitoring and Control," Die
Casting Engineer, pp.1 6-26, 1981. .
Listing of Papers & Authors from 11th DCE International Die
Casting Congress in 1981 (pp. 42, 91-77 of May/Jun. 1981 issue of
Die Casting Engineer)..
|
Primary Examiner: Teska; Kevin J.
Attorney, Agent or Firm: Nixon & Vanderhye
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
.[.This is a continuation-in-part of U.S. Ser. No. 292,168 filed
Aug. 12, 1981, now U.S. Pat. No. 4,504,920 issued Mar. 12,
1985..].
.Iadd.This is a continuation of U.S. Ser. No. 292,168 filed Aug.
12, 1981, now U.S. Pat. No. 4,504,920 issued Mar. 12, 1985.
.Iaddend.
Claims
What is claimed is:
1. A diagnostic method for analyzing and monitoring the process
parameters of reciprocating equipment in which a linear
reciprocating injection device is traversed over a fixed stroke
length at high speed comprising the steps of:
(a) dividing said stroke length into a predetermined number of
incremental positions;
(b) generating analog data corresponding to at least the position
of said injection device and the pressure developed by said
injection device at each such incremental position;
(c) recording the time transpired in the movement of said injection
device along said stroke length;
(d) deriving the velocity of said injection device at each such
incremental position;
(e) graphically displaying the data corresponding to pressure and
velocity on a display screen of a cathode ray tube as a function of
the incremental position of said injection device along said stroke
length until said velocity reaches a predetermined minimum level,
with said display forming a master profile for said data;
(f) storing the data representing said master profile at a
predetermined address location in a nonvolatile memory of a
microcomputer;
(g) repeating the sequence of generating, .[.calculating.].
.Iadd.deriving .Iaddend.and storing analog data corresponding to
pressure and velocity as a function of stroke position for a second
die casting .[.operating.]. .Iadd.operation .Iaddend.to form a
current profile of such data for such second operation, and
(h) displaying said current profile on said display screen along
with said master profile for diagnostic comparison purposes.
2. A diagnostic method as defined in claim 1 wherein said minimum
velocity level is a velocity of approximately zero.
3. A diagnostic method as defined in claim 2 wherein upon reaching
said minimum velocity level said analog data is displayed as a
function of time by establishing a time frame for the number of
incremental positions remaining after said minimum velocity level
is reached, dividing said time frame into incremental time
increments and recording said analog data at each of said time
increments until the increments of time equal the completion of the
time frame.
4. A diagnostic method as defined in claim 3 .[.wherein the.].
.Iadd.further including the steps of recording .Iaddend.temperature
.[.is recorded.]. .Iadd.in the reciprocating equipment .Iaddend.at
each incremental position along the stroke length and .[.is.].
graphically .[.displayed in step (e).]. .Iadd.displaying said
temperature .Iaddend.along with said pressure and velocity .[.and
stored as master profile data in step (f).]..
5. A diagnostic method as defined in claim 4 further comprising
programming the microcomputer .[.in which said master profile data
is stored.]. to generate a cursor in the form of a vertical line
upon said CRT display at any one of the incremental positions along
said stroke length; adjusting the position of said line cursor to a
desired position in increments corresponding to distance between
said incremental positions; and displaying the data of pressure and
velocity on said CRT screen corresponding to the adjusted position
of said line cursor.
6. A diagnostic method as defined in claim 1 further comprising
detecting when said predetermined minimum velocity level is reached
and graphically displaying the analog data of pressure and velocity
in step (e) as a function of time upon reaching said minimum
velocity level and until said stroke length is completed. .Iadd.7.
A diagnostic method for analyzing and monitoring the process
parameters of reciprocating equipment in which a linear
reciprocating device is traversed over a fixed stroke length at
high speed comprising the steps of:
(a) dividing a parameter indicative of movement of the device into
a predetermined number of incremental data collection points;
performing, for a first ram cycle, the following steps (b)-(f):
(b) generating data corresponding to said parameter and the
pressure developed by said device at each such incremental data
collection point;
(c) recording the time transpired in the movement of said device
along said stroke length;
(d) determining the velocity of said device at each such
incremental data collection point;
(e) generating a graphical representation corresponding to pressure
and velocity as a function of the device movement parameter along
said stroke length;
(f) storing said data in the form of master profile data at an
address location;
(g) repeating the sequence of generating data, determining velocity
and storing data corresponding to pressure and velocity as a
function of movement of said linear reciprocating device for a
second ram cycle to form a current profile of such data for such
second ram cycle; and
(h) generating a graphical representation of said current profile
along
with said master profile for diagnostic purposes..Iaddend. .Iadd.8.
A diagnostic method as defined in claim 7 wherein the step (e) does
not generate said graphical representation corresponding to said
pressure and velocity as a function of the device movement
parameter for a range of device movement parameters that are
substantially zero..Iaddend. .Iadd.9. A diagnostic method as
defined in claim 8 wherein upon reaching said near zero velocity,
said data is graphically represented as a function of time by
establishing a time frame for the number of data collection points
remaining after said minimum velocity level is reached, dividing
said time frame into incremental time increments and recording said
data at each of said time increments until the increments of time
equal the completion of the time frame..Iaddend. .Iadd.10. A
diagnostic method as defined in claim 9 further including measuring
temperature in the reciprocating equipment for data collection
points along the stroke length and graphically representing said
temperature along with said pressure and velocity..Iaddend.
.Iadd.11. A diagnostic method as defined in claim 10 further
comprising generating a cursor in the form of a vertical line for
any one of the data collection points along said stroke length;
adjusting the position of said line cursor to a desired point in
increments corresponding to distance between said points; and
generating an indication of the data of pressure and velocity
corresponding to the adjusted position of said line
cursor..Iaddend. .Iadd.12. A diagnostic method as defined in claim
8 further comprising detecting when said velocity level is reached,
and graphically representing the data of pressure and velocity in
step (e) as a function of time upon reaching said velocity level
and until said reciprocating device traversal is
completed..Iaddend. .Iadd.13. A method for monitoring the process
parameters of a linear reciprocating device which traverses a
stroke path at high speed to develop pressure, said method
comprising the steps of:
(a) collecting data at each of a plurality of data collection
points, said data corresponding to a parameter indicative of
movement of the device and the pressure developed by said device
during a first ram cycle;
(b) graphically representing a first pressure and velocity profile
as a function of the movement of said device along said stroke path
based on said data collected by said step (a);
(c) repeating said collecting step (a) for a further ram cycle;
and
(d) graphically representing a further pressure and velocity
profile as a function of the movement of said device along said
stroke path based on
said data collected by said repeated step (a)..Iaddend. .Iadd.14. A
method as in claim 13 wherein said graphically representing step
(d) includes superimposing graphical representations of said first
profile and said further profile..Iaddend. .Iadd.15. A method as
defined in claim 13 wherein said method further comprises the steps
of generating a cursor, permitting a user to move the cursor so as
to point to a portion of at least one of said graphically
represented first profile and said graphically represented further
profile, and providing numerical information indicating pressure
and velocity corresponding to said pointed-to portion of said
profile..Iaddend. .Iadd.16. A method as defined in claim 13 wherein
the graphically representing step (d) includes the step of
graphically representing said profiles as a function of positions
of said device where said device has a non-zero velocity..Iaddend.
.Iadd.17. A method as defined in claim 13 wherein for a range of
substantially zero velocities of said linear reciprocating device,
said profiles are graphically represented as a function of
time..Iaddend. .Iadd.18. A method as defined in claim 13 wherein a
temperature is also measured and collected for each data collection
point along the stroke length and said collected temperature is
graphically represented along with said pressure and
velocity..Iaddend. .Iadd.19. A method for monitoring the process
parameters of a reciprocating apparatus of a type including a ram
which traverses a stroke path at high speed to produce pressure,
said method including the following steps:
(a) providing a stored representation of a master velocity profile
for said ram as a function of position of said ram along said
stroke path;
(b) measuring the movement of said ram;
(c) deriving a velocity signal indicating velocity of said ram at a
plurality of positions along said stroke path based on said
measured movement; and
(d) generating, based on said stored representation and said
velocity signal, a superimposed graphical representation of (i)
said ram velocity as a function of said plurality of positions of
said ram along said stroke path and (ii) said master velocity
profile..Iaddend. .Iadd.20. A method as defined in claim 19 further
including the steps of:
providing a stored representation of a master pressure profile for
said ram as a function of position of said ram along said stroke
path,
deriving a pressure signal indicating the pressure developed by
said ram at said plurality of positions along said stroke path,
and
generating a superimposed graphical representation of (i) said
pressure signal as a function of said plurality of positions of
said ram along said stroke path and (ii) said master pressure
profile..Iaddend. .Iadd.21. A method as defined in claim 19 wherein
the step of measuring includes dividing the stroke length into a
number of increments and generating values corresponding to the
position of said ram at each such increment based on said measured
movement..Iaddend. .Iadd.22. A method for monitoring the process
parameters of a high speed reciprocating ram, said ram traversing a
stroke path at high speed to produce pressure, said method
including the following steps:
(a) storing indicia of electrical signals representing a master
pressure profile;
(b) measuring position of said ram along said stroke path;
(c) measuring pressure produced by said ram; and
(d) electrically generating an image including:
a first graphical representation of pressure versus position of
said ram along said stroke path based on said measured position and
pressure, and
a second graphical representation of pressure versus position of
said ram along said stroke path based on said stored master
pressure profile indicia,
said first and second graphical representations being at least
partially
superimposed in said image..Iaddend. .Iadd.23. A method as in claim
22 wherein said steps (b) and (c) are repeated, and said storing
step (a) comprises the step of storing indicia of measurements
obtained by a repetition of said steps (b) and (c)..Iaddend.
.Iadd.24. A method as in claim 22 wherein said method further
includes the steps of:
measuring the passage of time; and
also electrically generating a graphical representation of pressure
versus time based on said measured time and said measured
position..Iaddend. .Iadd.25. A method for monitoring a
reciprocating apparatus including a ram traversing a stroke path at
high speed to produce pressure, said method including the following
steps:
(a) measuring movement of said ram;
(b) deriving a velocity signal from said measured movement, said
velocity signal indicating velocity of said ram at a plurality of
positions along said stroke path;
(c) deriving a pressure signal indicating said pressure produced by
said ram at a plurality of positions of said ram along said stroke
path; and (d) graphically representing said velocity and pressure
signals as a function of position of said ram along said stroke
path. .Iaddend. .Iadd.26. A method for monitoring a reciprocating
apparatus including a ram and for electrically generating a
graphical representation of results of said monitoring, said ram
traversing a stroke path at high speed during a ram cycle to
produce pressure, said method including the following steps:
(a) providing a time base;
(b) measuring position of said ram for a first ram cycle;
(c) measuring pressure produced by said ram for said first ram
cycle;
(d) electrically generating a first graphical representation of
pressure versus position of said ram for said first ram cycle based
on said measured ram position and said measured pressure; and
(e) electrically generating a second graphical representation of
pressure versus time for said first ram cycle based on said
measured ram pressure and said time base, including the step of
facilitating substantially simultaneous viewing of said first and
second graphical representations.
.Iaddend. .Iadd.27. A method as in claim 26 wherein:
said step (d) includes the step of representing said pressure as a
function of position along a first axis graduated in position
increments; and
said step (e) includes the step of representing said pressure as a
function of time along a second axis, said second axis being
graduated in time increments, said first and second axes being
simultaneously viewable. .Iaddend. .Iadd.28. A method as claim 26
wherein:
said stroke path has an end;
said method further includes determining when the ram reaches the
ned of said stroke path;
said step (d) comprises representing said pressure versus position
of said moving ram; and
said step (e) comprises representing said pressure versus time for
pressure existing after said ram has reached the end of said stroke
path. .Iaddend. .Iadd.29. Apparatus for monitoring the process
parameters of reciprocating equipment, said equipment including a
ram which traverses a stroke path at high speed to produce
pressure, said apparatus comprising:
measuring means coupled to said ram for measuring the movement of
said ram;
velocity means coupled to said measuring means for deriving a first
signal indicating velocity of said ram at a plurality of positions
along said stroke path based on said measured movement;
a memory storing indicia representing a master velocity profile for
said ram as a function of position of said ram along said stroke
path; and
imaging means coupled to said velocity means and to said memory for
generating a superimposed graphical representation of (i) said
velocity as a function of position of said ram along said stroke
path and (ii) said
master velocity profile. .Iaddend. .Iadd.30. Apparatus as defined
in claim 29 wherein:
said apparatus further includes pressure sensing means for
providing a pressure signal indicating the pressure developed by
said ram at said plurality of positions along said stroke path;
said memory also stores indicia representing a master pressure
profile for said ram as a function of position of said ram along
said stroke path; and
said imaging means generating a superimposed graphical
representation of said pressure as a function of said plurality of
positions of said ram along said stroke path and said master
pressure profile. .Iaddend. .Iadd.31. Apparatus as defined in claim
29 wherein the movement measuring means includes means for dividing
the stroke length into a number of incremental positions and
generating values corresponding to the position of said ram at each
such incremental position based on said measured movement.
.Iaddend. .Iadd.32. Apparatus for monitoring the process parameters
of reciprocating equipment, said equipment including a ram which
traverses a stroke path at high speed to produce pressure, said
apparatus including:
movement measuring means coupled to said ram for measuring the
movement of said ram;
pressure measuring means for measuring the pressure produced by
said ram as said ram traverses said stroke path;
means for storing indicia representing a master pressure profile
for said ram; and
electrical imaging means, coupled to said storing means, said
movement measuring means and said pressure measuring means, for
generating an image based on said measured movement and pressure,
said image including (i) a first graphical representation of
pressure versus position of said ram along said stroke path, and
(ii) a further graphical representation of pressure versus ram
position along said stroke path based on said stored master
pressure profile indicia, said first and second graphical
representations being at least partially superimposed in said
image.
.Iaddend. .Iadd.33. Apparatus as in claim 32 wherein said first
graphical representation corresponds to a first ram stroke; said
storing means is coupled to said movement measuring means and said
pressure measuring means; and said stored master pressure profile
indicia are stored based on said measured movement and pressure for
a second ram stroke different from said first ram stroke. .Iaddend.
.Iadd.34. Apparatus as in claim 28 wherein:
said apparatus further includes means for measuring the passage of
time; and
said imaging means is also for electrically generating a graphical
representation of pressure versus time based on said measured time
and
said measured position. .Iaddend. .Iadd.35. Apparatus for
monitoring the process parameters of reciprocating equipment, said
equipment including a ram coupled to a fluid which traverses a
stroke path at high speed to produce pressure, said apparatus
including:
movement measuring means coupled to said ram for measuring the
movement of said ram;
means coupled to said movement measuring means for deriving a first
signal indicating velocity of said ram at a plurality of positions
along said stroke path based on said measured movement;
pressure sensing means for providing a second signal indicating
pressure produced by said ram at a plurality of positions of said
ram along said stroke path; and
imaging means coupled to said deriving means and said pressure
sensing means for generating a graphical velocity and pressure
profile representation of said first and second signals as a
function of said plurality of positions of said ram along said
stroke path. .Iaddend. .Iadd.36. Apparatus for monitoring the
process parameters of reciprocating equipment, said equipment
including a ram traversing a stroke path at high speed during a ram
stroke cycle to produce pressure, said apparatus comprising:
first measuring means for measuring the movement of said ram for a
first ram stroke cycle;
second measuring means for measuring the pressure for said first
ram stroke cycle;
third measuring means for measuring the passage of time during
which said movement and pressure are measured; and
output means coupled to said first, second and third measuring
means, for producing signals representing first and second
substantially simultaneously viewable graphical representations
based on said measured ram movement, said measured pressure, and
said measured time passage, said first graphical representation
showing pressure of said fluid versus position of said ram for said
first ram stroke cycle, said second graphical representation
showing pressure of said fluid versus time for said first ram
stroke cycle. .Iaddend. .Iadd.37. Apparatus as in claim 30 wherein
said output means provides signals representing an axis, signals
representing said pressure as a function of position along an axis
graduated in position increments, and signals representing said
pressure as a function of time along a second axis being graduated
in time increments, said first and second axes being simultaneously
viewable. .Iaddend. .Iadd.38. Apparatus as in claim 30 further
including an electronic display coupled to said output means, said
electronic display displaying said first graphical representation
showing pressure versus ram position for a portion of said first
ram cycle corresponding to a first time period during which said
ram is moving, said electronic display displaying said second
graphical representation showing pressure versus time for a portion
of said first ram cycle corresponding to a second time period
during which said ram has substantially ceased moving. .Iaddend.
Description
BACKGROUND OF INVENTION
Various industrial processes employ reciprocating machinery having
a linear stroke to implement the process. In die casting and
plastic molding, for example, the linear reciprocating device is an
hydraulic cylinder used for loading raw material into the die or
mold respectively. In die casting, molten metal is forced into the
die from the hydraulic cyliner by a piston type plunger or ram
displaced over a linear stroke under controlled operating
conditions of pressure and velocity. Research in die casting has
achieved a level of sophistication whereby the proper injection
speeds, pressure and temperatures required for optimum operation
for any given machine can be theoretically calculated. To satisfy
the calculated conditions, the operation must be carried out within
narrow ranges of settings for each of the critical process
parameters. Variation in one or more of the process parameters will
affect the performance of the other parameters on the process and
will alter the production rate and affect the yield of the product
produced. To optimize the production output the process parameter
settings are adjusted over a series of production runs until a
product with desired characteristics and production yield is
obtained. Since the events which affect the production cycle occur
much too quickly for human observation it was necessary,
heretofore, for operating personnel to make subjective judgements
in adjusting process parameters in a production run frequently
resulting in high scrap rates. The trial and error technique
commonly used heretofore also required more raw material than
necessary in getting a given required production output. Moreover,
because of the inability to control and adjust the process
parameters accurately, the design of the article produced typically
had to be made with more material than necessary for functional or
strength considerations simply to permit an acceptable yield.
Accordingly, a need exists for a diagnostic instrumentation system
which can readily be applied to the process machinery to monitor
and record objective measurements of machine performance during an
actual production cycle. The objective measurements should
represent machine operational data which will provide technical
personnel with the means to make appropriate adjustments to
maintain optimum process integrity. Prior art instrumentation
claiming to satisfy this need are based upon the use of high speed
analog graphic plotters which typically used expensive ultraviolet
sensitive photographic paper in combination with transducers and
signal conditions designed to collect machine data and display it.
One of the major disadvantages to the use of a graphic plotter is
that its output is a graphical display of the given parameter under
observation versus time. A time display is difficult to interpret
and requires sophisticated expertise to derive and calculate
quantitative values for the critical parameters affecting the
process. Not only is the interpretation subject to error but it
does not provide readily apparent information from which machine
adjustments may be made in the next production cycle. Another
significant disadvantage is that the oscillographs must be adjusted
to accommodate the transducers used on a specific machine and must
be calibrated for each different type of transducer. Also, because
of the high speed of the paper travel of the recorder it is
necessary for a technical person to be constantly attentive of the
oscillograph so as to minimize the waste of the expensive
paper.
In a die casting operation the reciprocating device would be
representative of the hydraulic cylinder and piston ram for
injecting raw material into the die. In accordance with the method
of the present invention a profile of the critical operational
parameters of the reciprocating device, viz., velocity and
pressure, are generated as a function of ram piston along its
linear stroke. This permits dramatically reduced set up time and
readily provides information for adjustment of the variable
parameters within precise limits to assure maximum production
quality and performance.
SUMMARY OF INVENTION
The method of the present invention comprises the steps of:
dividing the stroke length traversed by the ram into a
predetermined number of incremental positions; generating analog
data corresponding to the position of the ram and the pressure
developed by the ram at each such incremental position; recording
the time transpired in the movement of the ram along the stroke
length; calculating the velocity of the ram at each incremental
position, graphically displaying the data corresponding to pressure
and velocity on a display screen of a cathode ray tube as a
function of the incremental position of the ram along the stroke
length until the velocity reaches a predetermined minimum level,
with the display forming a master profile for such data; storing
the data representing the master profile at a predetermined address
location in a nonvolatile memory of a microcomputer; repeating the
sequence of generating, calculating and storing analog data
corresponding to pressure and velocity as a function of stroke
length for a second die casting operation to form a current profile
of such data and displaying said current profile on the display
screen along with the master profile for comparison purposes. The
best mode for practicing the present invention is described
hereafter at length in connection with the system shown in FIGS.
1-7.
OBJECTS OF THE INVENTION
It is the principal object of the present invention to provide a
method for generating a profile of at least one process parameter
in the control of a reciprocating device having a linear stroke as
a function of stroke position.
Another object of the present invention is to provide a method for
analyzing the process parameters in the operation of reciprocating
equipment in which a profile is recorded of master trace for a
given control parameter as a function of stroke position which is
then compared against a current profile of such control
parameter.
BRIEF DESCRIPTION OF DRAWINGS
Other objects and advantages of the present invention will become
apparent from the following detailed description of the invention
when read in conjunction with the accompanying drawings of
which:
FIG. 1 is a block diagram of the data analysis and display system
of the present invention;
FIG. 1A is a pictorial representation of a typical profile display
of velocity versus position generated in accordance with the
present invention for a die casting operation;
FIG. 2 shows the pressure interface circuit between the
microcomputer of FIG. 1 and the pressure transducer;
FIG. 3 shows the temperature interface circuit between the
microcomputer of FIG. 1 and the temperature transducer;
FIG. 4 shows the position transducer interface circuit between the
microcomputer of FIG. 1 and the position transducer;
FIG. 5 is a flow diagram for the microprocessor of FIG. 1
corresponding to the start function;
FIG. 5A is a flow diagram identifying the software functions for
the program selection "Collect Data" in the flow diagram of FIG.
5;
FIG. 6 is another flow diagram identifying the software functions
for the "Graphics" program selection in the flow diagram of FIG.
5;
FIG. 6A is a flow diagram subroutine for performing the "Plot"
function in the flow diagram of FIG. 6;
.[.FIG. 6B is a .]. .Iadd.FIGS. 6A-1 and 6B are .Iaddend.flow
diagram .[.subroutine.]. .Iadd.subroutines .Iaddend.for performing
the "Current", "Master" and "Plot Variable" subroutines of the Plot
function of FIG. 6A;
FIG. 6C is a flow diagram subroutine for performing the "Cursor"
subroutine for the Cursor function of FIG. 6;
FIG. 6D is a flow diagram subroutine for performing the "Files"
function in the flow diagram of FIG. 6;
FIG. 6E is a flow diagram subroutine for performing the "Get Old"
and "Make New" subroutines of the Files function of FIG. 6C;
and
FIG. 7 is a flow diagram for carrying out the ENTER/EDIT PARAMETER
SHEETS function in the flow diagram of FIG. 6.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now in particular to FIG. 1 and FIG. 1A inclusive which
diagrammatically illustrate the data analysis and display system of
the present invention and a typical CRT (cathode ray tube) velocity
profile generated by the system of the present invention for a die
casting machine.
The basic building blocks of the data analysis and display system
of the present invention comprise a microcomputer 1 of any
conventional design, including a conventional non-volatile memory
7, groups of program selection and function keys, 8, 9 and 12 and a
numeric keyboard 10; a plurality of transducers 2, 3, 4 and 5
respectively and a conventional cathode ray tube 6 hereinafter
referred to as a CRT.
The transducers 2, 3, 4 and 5 represent pressure, temperature and
velocity position transducers respectively. Transducers 4 and 5
represent alternative transducers for providing velocity position
data to the microprocessor. Transducer 4 is a conventional digital
type transducer connected to the die casting machine to sense the
pulses generated during machine production in response to each
incremental movement of the reciprocating device (not shown) over
its linear stroke. The output is in a binary coded decimal format
for direct reading by the microcomputer 1. The transducer 5 is a
linear potentiometer having an interface circuit as will be
discussed in more detail with reference to FIG. 4. The
microcomputer 1 may interface to either the digital velocity
position transducer 4 or the linear potentiometer velocity position
transducer 5. The temperature transducer 3 is a temperature
thermocouple having an interface circuit as will be discussed in
more detail with reference to FIG. 3 whereas the pressure
transducer 2 is a conventional strain gage type pressure transducer
in a bridge configuration with an interface circuit as will be
discussed in more detail with reference to FIG. 2.
Each of the transducers 2, 3, 4 and 5 collect data consisting of
velocity, temperature and pressure as a function of stroke position
during a production cycle. The production cycle for a die casting
or plastic molding operation is defined for purposes of the present
invention as the stroke and corresponds to the motion of the
injection ram (not shown) which injects either metal into the die
or plastic into a mold respectively. The stroke length represents
the total displaced distance of the injection ram in the hydraulic
cylinder for a single production cycle.
The conventional microcomputer is connected to a conventional CRT 6
for displaying a profile representative of the data collected by
the transducers 2, 3, 4 or 5 in accordance with programmed
instructions corresponding to the flow digrams 5, 6, 6A-6F and 7
respectively as will be discussed in more detail hereafter. Any
conventional software program format suitable for use with the
microcomputer 1 may be used in the preparation of a program to
fulfill the flow diagram requirements. The program itself .[.does
not form a part of the present invention and.]. may readily be
prepared by any skilled programmer from the flow diagrams.
An illustrated display of a typical profile 14 representative of
the velocity of the injection ram for a production cycle as a
function of stroke position, i.e., the position of the
reciprocating injection ram along the stroke length, is shown on
the CRT 6. A further illustrative display showing two velocity
traces superimposed for comparison is shown in FIG. 1A. The
microcomputer 1 is of any commercially available type which can
generate a cursor. The position of the cursor 16 is FIG. 1A is
controlled by software following the flow diagram subroutine for
the cursor to be discussed hereafter in connection with FIG. 6C and
FIG. 7. The cursor 16 is adjustable over the stroke length and
provides specific parameter information corresponding to its
location on the display thereby permitting the observer to readily
compare parameter values between the superimposed traces at any
stroke position. One of the superimposed traces may represent a
"master" profile defined as an idealized or acceptable profile and
may simply represent a previously recorded profile. A master
profile is used for comparison purposes with a "current" profile. A
current profile is defined as a profile trace formed on the CRT
from data received by the microprocessor from one of the
transducers in response to a current production cycle. The master
profile is stored in the non-volatile memory 7. Any number of
master profiles may be recorded and stored in the non-volatile
memory 7 so as to constitute a library of master profiles. A master
profile is stored at any address in memory 7 identified by the
operator through the use of the numeric keyboard 10. By providing
this ability to superimpose master profiles over a current
profiles, a non-technically trained person can readily distinguish
between a master trace identifying a production run classified as
acceptable or good and the current production run representing the
current profile. It also becomes readily apparent to the operator
where and to what extent adjustment may be necessary to conform
subsequent production runs to the master trace. This is primarily
attributable to the fact that the trace is a function of position
and not time. Individual program selection and function control is
provided by groups of push buttons 8, 9 and 12. Each individual
button in group 9 is assigned a program selection whereas the group
of push buttons 8 and 12 are assigned individual function
selections corresponding to the function selections in the flow
diagrams. The numeric keyboard 10 additionally provides for the
numeric entry of upper and lower limits for each important
parameter so as to define the acceptable range of such parameter
for proper operation of the machine. In addition, the numeric
keyboard 10 may be used to enter data corresponding to a machine
number, ram plunger diameter and production cycle job number which
collectively are used for the file identification for each master
trace stored in the non-volatile memory 7.
FIG. 2 shows the pressure interface circuit between the
microcomputer 1 and the pressure transducer 2. The pressure
transducer 2 is of a conventional bridge type with one leg of the
bridge being adjustable and varying in a conventional fashion in
response to the amount of resistance to movement of the
reciprocating device (not shown). Resistors R1, R2 and R3 form a
zero offset adjustment network to cancel out the zero offset of the
pressure transducer 2 so as to provide a zero differential input to
the operational amplifier U1. Resistors R4, R5, R6, R7 R8 and R9
form an appropriate feedback network to provide an output .[.18.].
.Iadd.19 .Iaddend.of predetermined gain relative to the signal
.[.19.]. .Iadd.18.Iaddend.. RC network combination R7 and C1 reduce
the noise content from the pressure transducer 2. Integrated
circuit 20 is a commercially available analog to digital converter
for converting the analog signal to a digital format preferably in
BCD form. The resistors R11, R12, R13, R14, R15, R25, R26 and R27
are pull up resistors for providing signals on lines AD, BC and MNL
which are connected to provide the microcomputer 1 with continuous
data corresponding to the pressure at the instant of time selected
to be read by the microcomputer. The microcomputer 1 reads the
pressure data in increments of time corresponding to the
incremental displacement of the reciprocating device (not shown)
over the stroke length to provide a profile of pressure versus
stroke position. Resistors R10 and R23 are selected to cancel the
zero offset of the analog to digital converter 20. Capacitor C2 is
an integrating capacitor used by converter 20 during data
conversion. Resistor R22 is used to adjust the gain of the
converter 20 to result in a calibrated output.
FIG. 3 shows the temperature interface circuit between the
temperature transducer 3 and the microcomputer 1. Thermocouple 41
is adapted to be coupled to the reciprocating device to provide a
temperature signal corresponding to the temperature in the
reciprocating device as a function of stroke position. The
thermocouple 41 is connected through lead lines 25 and 26 to a
conventional operational amplifier U2. Resistors R28 and R29
provide the .Iadd.input and .Iaddend.feedback resistors for setting
the gain of the first stage of amplification. A second stage of
amplification is provided by a conventional operational amplifier
U3 in conjunction with its feedback .Iadd.and .Iaddend.resistor
network R30, R31, R32, R35 and R34. The output 30 from the second
stage of amplification is fed relative to the potential on line 33
to a conventional analog to digital converter 32 in a manner
similar to that in the interface circuit for the pressure
transducer 2. The output from the analog to digital converter 32 is
provided on the same lines LM N, AB, CD as for the pressure
transducer circuit in FIG. 2.
FIG. 4 shows the linear potentiometer interface circuit between the
linear potentiometer 5 and the microcomputer 1. The linear
potentiometer 5 may be readily mounted to the die casting
.[.maching.]. .Iadd.machine .Iaddend.with its variable wiper arm 35
connected to move with the reciprocating device. Accordingly, the
position of the wiper arm 35 is directly proportional to the
position of the reciprocating device along the stroke length. Since
the velocity of the reciprocating device is equal to distance
divided by time; the velocity is readily determined relative to
each incremental stroke position. The stroke length may be divided
into any number of increments with the velocity representing the
differential of each reading with respective to time.
Linear potentiometer 5 is connected to the interface circuit
operational .[.amplifier.]. .Iadd.amplifiers .Iaddend.U4, U5 and U6
respectively. Operational amplifiers U4 and U5 serve to apply
positive and negative reference voltage levels across the opposite
ends 36, 37 of the potentiometer 5. The operational amplifier U6
amplifies the signal output 38 from the wiper arm 35. Operational
amplifiers U4 and U6 are connected in a conventional unity gain
configuration. Resistors R54 and R55 form a unity gain feedback
circuit which generates a positive reference voltage on end 36 of
potentiometer 5 equal in magnitude to the negative reference
voltage developed by zener diode D1 from a negative power supply
voltage -V through resistor R56. Accordingly, the output 40 of the
operational amplifier U6 is automatically adjusted against drift in
power supply voltage. The output 40 is connected to a conventional
analog to digital converter 65 such as Beckman AD7556. The data
presented on the data bus lines D0 through D7 are connected to the
microcomputer 1. The A to D converter 42 generates a twelve bit
digital signal corresponding to the analog signal 40. Nor gates 71,
72 and 73 control the conversion of data and the interrogation of
the twelve bit output D0 through D11.
Each time the microcomputer takes a reading the enable conversion
line 74 goes to the zero logic state. At the same time, address
lines 75 and 76 are set to a logical zero. When all three of the
signals are logical zero's the output of Or gate 72 is a logical
one thereby enabling the low byte labeled LBI in the A to D
converter 42. This causes the lower significant bits D0 through D7
to be impressed upon the data bus lines .[.B0 to B7.]. .Iadd.D0 to
D7.Iaddend.. After reading the lower eight bits, the microcomputer
1 then interrogates the upper four bits D8 to D11 by setting the
enable conversion line to a zero logic state while setting address
lines 77 and 76 to logical zero. This combination causes the output
of Or gate 73 to go to a logical one which, in turn, enables the
end of Conversion Signal EcoI and the high byte HBI causing the
upper significant bits D8 to D11 to be impressed upon the data bus
lines .[.B0 to B3.]. .Iadd.D0 to D3.Iaddend.. The conversion of
data is initiated when the microcomputer sets the enable conversion
line 74 to a zero logic state and sets the address lines 78 and 76
to logical zero. This causes the output of Or gate 71 to go to a
high state thereby impressing a start signal to the start input of
the A to D converter 42 for starting another conversion cycle. By
continuously repeating the start conversion and reading sequence in
predetermined intervals corresponding to incremental distances the
microcomputer 1 knows at all times what the position of the ram is
along the machine stroke. Upon collecting the position data as a
function of time it need only perform an algorithm representing a
simple mathamatical quotient of distance and time to convert the
position data to velocity data. Accordingly, a profile can be
generated corresponding to velocity versus position as well as
velocity versus time or a combination of both. The latter is
significant in that certain periods may exist when a momentary time
display would be beneficial. In die casting this is true at
approximately the end of the stroke where the velocity of the ram
approaches zero. Accordingly, a combination display is particularly
useful for the pressure profile in a die casting operation over the
final stroke length known to those skilled in the art as the
"biscuit" length.
FIG. 5 illustrated the flow diagram for start up of the
microcomputer 1. Upon depressing the start function key three
program selections identified as Collect Data, Graphics and
Entry/Edit Parameter sheets become selectable. A program is
selected by depressing one of the dedicated function keys
corresponding to the program selection. Any one of the keys in the
function key groups 8, 9, and 12 may be assigned the appropriate
functions.
FIG. 5A shows the flow diagram for the program selection "Collect
Data". The letter (N) designates each incremental position at which
data is to be collected over the stroke length. The stroke length
may be divided into any fixed number of incremental data collection
points preferably corresponding to the screen increments for the
particular microcomputer being used. At each data collection point
a time reading is taken with the number of the data points
designated IT. The start position is labeled S.phi. at time IT
.phi. whereas the current position of the injection ram along the
stroke length is designated SI. The algorithmic statement
SI.varies.S.phi.+E is met only when the ram has advanced from the
start position a fixed distance E representing the desired
incremental spacing between the incremental positions. Once this is
met the incremental position N is advanced by one and a reading is
taken from the transducers 2, 3, 4 or 5 of current velocity,
current temperature, and current pressure. The microcomputer, clock
is used for generating a time frame.
The program of FIG. 5A provides for consecutive reading at each
incremental position until the assigned number of incremental
positions reaches maximum. In die casting near the end of the
operation when the ram approaches the end of the stroke the
velocity will drop to a plateau level of slightly above zero at
which time it is preferred to continue readings as a function of
time. Accordingly, as shown in FIG. 5A, a time frame is established
for the remaining number of incremental positions with t.phi.
representing the starting time for further consecutive readings as
a function of time. As soon as the current time t(N) plus a
predetermined time increment ".delta." is reached representing a
time data increment IT within the established time frame, from
t.phi. to IT maximum, the next reading is taken. At such instant
the time data increment IT is advanced by one and further readings
are taken until the increments of time IT equal the completion of
the established time frame.
FIG. 6 shows the flow diagram for the program selection Graphics.
With this program selection the operator is given a further choice
of the subordinate functions Plot, Cursor, Frame, Files and Quit.
Any one of these functions become available upon depression of one
of the assigned function keys 8. The Erase function .Iadd.clears
the screen and .[.return.]. .Iadd..Iaddend.returns the program
selection. The program selection is also returned upon depressing
the quit function key.
The Plot function is shown in FIG. 6A providing further selection
of the subroutines Master or Current. FIG. 6B shows the flow
diagram for both the master and current subroutine for the function
selection Plot. The subroutine is the same whether current data or
master data is plotted with the data of each of the variables
loaded and plotted corresponding to each incremental position. The
Cursor function flow diagram is shown in FIG. 6C. A vertical line
is plotted at the existing incremental position on the CRT screen
upon selection of the cursor with corresponding variables for the
cursor position printed on the display for either a master or
current profile. The cursor position is adjustable by the operator
to either the left or right of the displayed cursor position by
depression of the assigned dedicated function keys for cursor left
or right control. The cursor will move in increments N preferably
corresponding to the assigned incremental positions N for the
stroke. Accordingly, the cursor position for one trace will
automatically correspond to the same incremental position for a
superimposed trace. As the flow diagram indicates the cursor may
only be moved to the left or right to an incremental position which
satisfies the statement defining the number of N positions.
In FIG. 6D the flow diagram for the function selection Files is
shown. The operator is provided with a further choice of subroutine
selections "Get Old", "Make New", or "Quit". The subroutines Get
Old and Make New .[.is.]. .Iadd.are .Iaddend.illustrated in FIG.
6E. The files selection "Get Old" corresponds to the selection of a
master trace whereas the files selection "Make New" corresponds to
the storing of current data in forming a master trace in the
non-volatile memory 7. The address number for the old or new master
trace in the non-volatile memory is designated by use of the
numeric keypad.
The Enter/Edit Parameter Sheet program selection identified in the
flow diagram for start up of the microcomputer 1 is shown in FIG.
7. The microcomputer 1 is instructed to go to the numeric keypad
and wait for the operator to read in the numbers corresponding to
the machine in use, the part in use and the machine type. The
microcomputer assigns and constructs characters used for the file
name. The parameters may then be printed out on the CRT screen. The
screen prompt is adjustable to the left, right or up and down. The
screen prompt refers to the flashing inverse video enhancement of
the location on the CRT screen which the computer is currently
monitoring. The user may at any time depress Fields complete to
save the File name. The parameter sheet program may also be used to
print out acceptable high and low limit settings. .[.The velocity
of the injection device may be calculated as indicated heretobefore
by dividing the traversed distance between incremental positions of
stroke length with the differential in time transpired between such
positions or alternatively by using a velocity position transducer
consisting of the analog output variety including but not limited
to potentiometers or LVTD's connected to a conventional analog to
digital (A/D) converter. The A/D converter will generate an
absolute position input for processing by the microcomputer.
Another alternative means of measuring velocity is to use any
conventional velocity position transducer such as the analog output
variety mentioned above in combination with an analog differential
circuit as shown in FIG. 4 enclosed within dotted lines. The analog
differentiator circuit 80 is connected to the position signal
output 40 of the operational amplifier U6 which in turn is
connected to the potentiometer transducer 5. The differentiator
circuit 80 will generate a signal 82 proportional to velocity
which, in turn, is connected to an analog to digital converter 84
which corresponds to the conventional A/D converter 68 with output
data bus lines equivalent to the data bus lines D0-D7 for
connection to the microcomputer.
Although the foregoing invention has been described specifically in
connection with a die casting machine the invention is equally
applicable for use with other machine types including, but not
limited to, extrusion presses, low pressure die casting machines,
permanent hold casting machines, forging presses, powder metal
presses and trim presses. In addition, it should be understood that
the present invention is not limited to graphic display and
embraces numerical analysis and tabular display. It should further
be understood that although multiple process parameters may be
displayed the invention is not limited to the display of a
plurality of parameters. A single profile of any parameter
including velocity, position, pressure, temperature, etc. may be
displayed. In addition, the profiles may be analyzed and reduced to
discreet results for display which results may be compared against
preprogrammed constants stored in the microcomputer such as low
limits and alarm conditions.
A predominant feature discussed throughout the specification is the
ability to store profiles in memory as master traces to be compared
against current data profiles. It is obvious, however, that the
method of the present invention encompasses a display of only the
current data profiles without necessarily superimposing a master
trace..].
* * * * *