CA1171158A

CA1171158A - Tracer type metal working machine with improved features

Info

Publication number: CA1171158A
Application number: CA000392644A
Authority: CA
Inventors: Fredrick J. Balfanz
Original assignee: C-R-O Inc
Current assignee: C-R-O Inc
Priority date: 1981-06-29
Filing date: 1981-12-18
Publication date: 1984-07-17
Also published as: EP0068184A1; DE3262404D1; EP0068184B1

Abstract

TRACER TYPE METAL WORKING MACHINE
WITH IMPROVED FEATURES
ABSTRACT OF THE DISCLOSURE
A metal working machine has a tracer and co-ordinate drive control which are connected through the X and Y drive motors and encoders to an input of a CNC
unit mounted on the machine. The CNC is separately connected to a tape recording device and can record the tracer movements on the tape. Additional machine commands can be added via the CNC. The CNC memory can be loaded or programmed either via the tracer itself or subsequently from the recorded tape for later machine controlling playback independent of the tracer or tape.
The CNC is further connected to a digitizing device which makes it possible to reduce the amount of positional in-formation which must be stored by the memory. This is accomplished by manually or automatically varying the positional sampling rate according to the contour and dimensions of the workpiece. When the sampling rate is varied automatically, the information reduction device is provided with a feedback from the tracer. More specifically, and in either the manual or automatic mode, the positional sampling rate is controlled by a variable repetitive timer.

Description

TRACER TYP~ METAL WORKING MACHINE
WITH IMPROVED FEATURES

U.S. PRIOR ART OF INTEREST
3,717,332 Lukes et al. 3/20/73 4,012,027 Hooper 3/15/77 4,121,808 Cardea 10/24/78 4,193,021 Gale et al. 3/11/80 4,255,643 Balfanz 3/10/81 This invention relates to a tracer type metal working machine for welding or cutting metal workpieces.
Tracer type metal working machines have long been in use. Such machines may use a~mechanical follower for a template comprising a reproduction of the part to be welded or cut, or may utilize an optical-type device which scans the edge of a part-template or the outline of a drawing template. ~ ~ -Heretofore, tracer machines have normally func-tioned in one of two ways. In one way, such as in U.S.
- Patent 4,012,027, the tracer output is directly connected to the coordinate tool drive mechanism, and thus the X
and Y axis drive motors, so that the workpiece is worked simultaneously with the tracing operationO In another system, which actually uses two machines, as in U.S.
Patent 4,193,021, the tracer output is fed directly in one machine to a tape recor~er of the paper tape or magnetic t~pe, with the tape being used subsequently in another machine to drive the metal working devices as and when desired.
Modern metal working machines can be made sub-stantially more flexible in operation if they are operated via a CNC (Computerized Numerical Control3 which includes a programmable memory. And yet, the complexities of CNC

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devices are such that many operators prefer to purchase the older tracer type machines.
It is a task of the present invention to provide a tra-cer type metal working machine which can be used in the conven-tional manner to simultaneously drive the tool from the tracer, and which also has the capability to create a tape either simul-taneously with o~ subsequent to tracing.
It is a further task of the invention to provide a tra-cer type metal working machine which has the further capability of operating via a CNC system, which can be programmed directly from a pre-recorded tape or from the tracer output.
It is an additional task of the invention to manually or automatically prevent overloading of the memory of a CNC unit which is being programmed from the tracer output.
According to the present invention there is provided a machine for tool working of plate-like metal workpices, comprising in combination: (a? a frame, (b) a carriage mounted for movement on said frame along an X axis, (c) a cross-member mounted trans-versely of said carriage for movement therewith, (d) metal working means mounted for movement on said cross-member along a Y axis, (e) first and second motive means for driving said carriage and said metal working means along their respective axes, (f) a support for receiving a template thereon, (g~ template tracing means dis-posed adjacent said support, (h) a computerized numeral control having a programmable memo.ry, (i) encoder means for supplying posi-tional coordinate information derived from said tracing means dur-ing following of a template to said computerized numerical control for loading said memory with said information, and (j) a coordinate drive control for actuating said motive means selectively under 3G the control of said computerized numerical control or said tracing means.
In accordance with one aspect of the invention, the tra-

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cer and its coordinate drive control are connected through the X
and Y drive motors and encoders to an lnput oE a CNC unit mounted on the machine. The CNC is separately connected to a tape record-ing device and can record the tracer movements on the tape. Ad-ditional machine commands can be added via the CNC. The CNC me-mory can be loaded or programmed either via the tracer itself or subsequently from the recorded tape for later machine controlling playback independent of the tracer or tape.
In accordance with another aspect of the invention, the CNC is ~urther connected to a digitizing device which makes it possible to reduce the amount of positional information which must be stored by the memory. This is accomplished by manually or au-tomatically varying the positional sampling rate according to -the contour and dimensions of the workpiece. When the sampling rate is 2a -~ ~7115~

-3-varied automatically, the information reduction device is provided with a feedback from the tracer. More specif-ically, and in either the manual or automatic mode, the positional sampling rate is controlled by a variable repetitive timer.

BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings illustrate the best mode presently contemplated by the inventor for carrying out the invention.
In the drawings:
FIG. 1 is a perspective view of a machine for cutting metal plates which incorporates the various aspects of the inventionj FIG. 2 is a schematic block diagram of the electronic control system for the machine of FIG. l;
FIG. 3 is a schematic outline of a template showing the changes in positional sampling rate along the template edge;
FIG. 4 is- a schematic outline of a template showing the use of command marks for use with automatic changes in the sampling rate; and FIG. S is a schematic block diagram similar to FIG. 2 and showing the addition of the automatic sampling rate feature.

DESCRIPTION OF THE PREFERRED EMBODIMENT
While the inventive concepts are equally applicable to welding, the illustrative embodiment is directed to a metal cutting machine.
Referring to FIG. I of the drawings, the invention is embodied ~n a cantelever type tracer con-trolled coordinate drive metal cutting machine having a floor supporting framework including a pair of longi-tudinal rails 1 mounted on legs 2, on one oE which is ' ~ ~17115~

slideably or rollably mounted a first carriage 3 defin- -ing a longitudinal or X axis. Carriage 3 is controlled for movement alon~ its axis through a main control box

4 and an X axis motor 5. An elongated transverse rail 6 is rollingly supported at one end on the other rail 1, is supportingly mounted at its midsection by carriage 3, and has a free end portion 7 extending substantially beyond the machine support to thereby overhang a cutting table 8. Table 8 is supported by the floor and is adapted to adjustably carry a horizontally disposed flat plate-like workpiece 9.
A second carriage 10 is slideably or rollably mounted on rail 6 and defines a transverse or Y axis.
Carriage 10 is also controlled for movement along its axis through control box 4, and by a Y axis motor 11.
One or more metal cutting heads 12 (two being shown herein) are adjustably mounted to carriage 10 above ~able 8 and are adapted to cut workpiece 9. ~eads 12 may be of any suitable well-known type, such as flame or plasma torches or laser beam generators. They also may be actuated from control box 4.
The machine is adapted for tracer control of X-axis and Y-axis coordinate drive motors 5 and 11, as by a scanning or tracing head 13 which is fixedly mounied on the inner end portion of carriage 10 remote Erom cutting heads 12. Head 13 may be of any sui-tahle well-known type and may use an optical viewer 14 and photo-electric control system, not shownt to move carriayes 3 and 10 so that cutting heads 12 describe a desired path which may include both curved and straight-line segments.
The tracing system includes a horizontal tracing table 15 which extends between rails 1 and is edge mounted ~:~
for longitudinal sliding or rolling movem2nt in the direc-tion of the X axis. Table 15 is adapted to support a 1 1 7~58 template 16 of any suitable type and which has indicia comprising either edges or lines 17 defining the config-uration of one part to be cut singly or in multiples from workpiece 9. Template 16 is shown as having a lead-in or positioning indicia, such as at point 1~, which is the starting position for tracing oE the piece. As shown, point 18 is on a rear corner of template line 17, although the indicia could be anywhere on the template.
When the apparatus is actuated, tracing head 13 produces electrical output signals in accordance with its position with respect to line 17. These signals are fed to the motor drive to cause head 13 to move along the line. In the usual mode of operation, cutting heads 12 will be caused to move along a corresponding path and, when en-ergized, will cut a first series o~ identical side-by-side parts 19 from workpiece 9 along the front edge thereof.
Control box 4 contains the usual coordinate drive cont~ol 4a for actuating motors 5 and 11 through suitable respective amplifiers 20 and 21, and also includes circuitry for controlling tracer 13, all of this being conventional. An optical tracer 13 and its drive are described in U.S. Patent 3,717,332. Devices of this type are available from Canadian Westinghouse under the designation of Model HL10.
The direct cutting of workpiece 9 simultaneously with tracer operation may be adequate in some instances, but it requires that~the correct template 16 must always be mounted on tracing table 15 during cutting. It would be substantially more desirable to be able to cut work-piece 9, regardless of whether template 16 is present or not. The present invention makes this possible in sev-eral alternate ways.
In accordance with certain aspects of the present invention, the machine incorporates a CNC (Com-puteriæed Numerical Control) 22, which has a programmable , ~ ~711~

memory and which is connected to receive and store positional signals as to the X and Y coordinates from encremental feedback pulse encoders 23, 24 which are respectively connected to motors 5 and 11 See FIGS.
1 and 2. Such encoders are conventional, are described in U.S. Patent 4,193,021, and are commercially avail-able as model 77 from Dynamics Research Corporation.
The CNC itself is also conventional and is available commercially in conjunction with metal working machines of other types than herein described from C-R-O, Inc., Menomonee Falls, Wisconsin. See also Patents 4,121,808 and 4,255,643 relative to the use of numerical control equipment in a metal cutting machine.
Referring to FIG. 2, CNC 22 has a selectively actuatable output rom its memory to coordinate drive control 4a, so that motors 5 and 11 can be driven Erom the computer memory independently of tracer 13.
The computer memory can be programmed in one of several ways. The initial primary programming method is to operate tracer 13 in conjunction with template 16, as discussed above, causing motors 5 and 11 to operate so that the X and Y positional signals are fed through encoders 23 and 24 to load the memory of CNC 2~. Sub-sequently, at any desired time and without the need for tracer 13 to operate, CNC 22 can output the information from its memory to coordinate drive control 4a to thereby - operate motors 5 and 11 to cut workpiece 9 in exact accordance with the previously tracer-followed template contour.
In addition, once the CNC memory is loaded with the desired cutting program, it can subsequently be used to generate a tape for receipt and permanent storage of the program. For this purpose, a tape unit 25 of any suitable well-known type is connected to CNC 22 so that it can record from or playback to the CNC in the conven-1 171~5~

tional manner. The tape 26 used may be of the paper or magnetic type.
The program initially loaded into the CNC mem-ory may thus be transferred to tape 26. Subsequently, the CNC memory can be erased and used in connection with working other workpieces. When it is desired to cut pieces similar to parts 19 at some later time, tape 26 - can be run to load the CNC memory with the original program This is the second method of programming the memory with the same information. Once this is accom-plished, this program can be outputted to coordinate drive control 4a, as discussed above, as and when desired, to cut similar parts 19 from workpiece 9 independently of tracer 13.
One of the advantages of always initially load-ing the template-tracer controlled machine operation into the memory is that, while the information is in memory, it can be edited before outputtiny it to coor-dinate drive control 4a or tape unit 25. Thus r and as shown in FIG. 2, the CNC memory can have added to it such commands as "Torch On", "Torch Off", 'IAdvance" and "Repeat" etc. This editing can be added so that it is recorded directly on tape 26, or can be manually done after rel~ading of the basic material from the tape.
Computer memories are limited and can only store a fixed amount of information. In some instances 9 parts 19 may be so large or have such a complex config-uration that the positional information to be fed into the CNC memory would overload it. Further aspects of the inventive concept are adapted to solve this problem.
In order to reduce the information to be stored in the CNC memory, a digitizing device may be utilized which causes sampling of the template contour information at controlled spaced points and feeds only the sampled information to memory.

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For this purpose, and as shown in FIG. 2, a repetitive timer 27, such as a variable frequency oscillator, is connected to a CNC input and hence oper-atively through coordinate drive control 4a to tracer 13. During tracing of the template contour, timer 27 gives interrupt signals to tracer 13 through control 4a, causing tracer 13 to stop at each spaced point as determined by the set frequency of oscillations.
At each such point, the logic of timer 27 is such that it in effect also orders the CNC memory to store the X and Y
coordinate positions of tracer 13 as determined by en-coders 23 and 24, and then permits tracer 13 to contin-ue on to the next stop, A digitized series o~ sampled coordinate points is thus stored in memory.
Timer 27, being of variable frequency, can cause the template contour to be sampled at varying rates, such as for example every 1/8", every 2/3", every 1" etc.
FIG. 3 is representative of a template 16a having an edge 17a and which is to be traced by tracer 13 for programming into the memory of CNC 22. The tracer is to start at leading point 18 and Eollow around in a counter-clockwise direction. It can be seen that the first portion 17a-1 of the edge is of gradual cur~
vature requiring a medium frequency of X and Y coordinate sampling. Second edge portion 17a-2 is a much sharper curve, requiring substantially increased frequency of sampling to provide sufficient accuracy. Third edge portion 17a-3 is a straight line and thus only requires sampling at its beginning and end. A 90 corner, not shown, would require the maximum sampliny rate possible.
The concepts of the invention contemplate several modes of variable sampling.
If a manual mode is to be used, repetitive timing control 27 is provided with a dial 28 and manual ~ g7~58 knob or lever 29 which is used to set the frequency out-put for a straight line, sharp corners and various de-grees of curvature. During tracing of edge 17a of FIG. 3, the operator would manually set lever 29 for slightly different medium sampling rates over portion 17a-1 so that tracer 13 would stop along relatively widely spaced discrete points 30. As the tracer approaches corner 17a-2, the operator knows that an increased sampling rate is needed and selectively adjusts lev~r 29 accordingly to provide more closely spaced stopping points 30. Once this corner is tra-versed, the operator, noting that edge portion 17a-3 is a straight line, may shift lever 29 to the area of the "straight line" position. This effectively reduces the sampling frequency, because coordinate sampling is actually needed only at the beginning and end of a straight line. When the area oE starting point 18 is reached, the operator may increase the sampling rate until the part contour is closed, possibly with some overlap.
He then shuts the tracer off. On extremely long straight lines, the oscillator could be turned ofE and the "manual enter location" button pushed occasionally to record periodic location points.
The ultimate result is that the X and Y coor-dinates are not recorded substantially continuously, but only intermittently at the spaced points 30 as needed.
The amount of information stored in the CNC memory is thus greatly reduced. r~he ability to digitize the tem-plate contour is a variable manner, and to actually re~
duce or stop sampling along ~traight lines of great len~th, eliminates the need for an exkensive memory bank~
The invention also contemplates an automatic sampling mode which in many instances may be more accur-ate than when done manually.
For this purpose, and referring to FIGS. 4 and

5, a tracer 31 of a special type is used. While tracer ) ~ ~ 71 ~5~
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31 is generally similar to tracer 13, it has the additional capability of sensing command marks 32 placed along edge 17b of template 16b. Marks 32 are strategi-cally placed along edge 17b at the onset of an edge portion requiriny a different sampling rate. Thus, edge portions 17b-1 through 17b 5 each need a sampling rate different from the next preceeding edge portion. For example/ edge portions 17b-1 and 17b-3 need a lower frequency of sampling. Edge portions 17b-2 and 17b-4 need a higher frequency, with 17b-4 requiring a very high frequency. Likewise, edge portion 17b-5, being a straight lineJ needs sampling only at its beginning and end.
Tracers which are responsive to command marks to provide a suitable output signal for actuating any desirable device are already known.
Such tracers are sold by Westinghouse Canada Ltd. under the trademark "Linatrol", Model HL-7, which can use a plug-in card to cause reading of marks on a template for automatic control of machine operationJ such as speed, tool on/off, punch mar]cs, etc.
The diagram of FIG. 5 is similar to FIG. 2 except in this instance there is no dial 28. Instead, there is a feed-back from tracer 31 to the variable repetitive timing control 27, as via line 33. Thus, when tracer 31 reaches a command mark 32, it provides an output signal which is received at control 27 to auto-matically change its frequency and the resultant position-al sampling rate of the tracer, as described relative to FIGS. 2 and 3.
The device of the invention provides a major improvement in tracer type machines for tool working of a metal workpiece. The operator now has the option of operating the machine from a CNC memory which has been programmed directly from the tracer or programmed from a .

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~ 1 7~ ~58 tape which was previously recorded from the directly programmed memory. In addition, the device provides a variable sampling rate along the template either by manual or automatic control to reduce the informa-tion needed by the memory for a particular part.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A machine for tool working of plate-like metal work-pieces, comprising in combination: (a) a frame, (b) a carriage mounted for movement on said frame along an X axis, (c) a cross-member mounted transversely of said carriage for movement there-with, (d) metal working means mounted for movement on said cross-member along a Y axis, (e) first and second motive means for driv-ing said carriage and said metal working means along their respec-tive axes, (f) a support for receiving a template thereon, (g) template tracing means disposed adjacent said support, (h) a com-puterized numeral control having a programmable memory, (i) en-coder means for supplying positional coordinate information derived from said tracing means during following of a template to said com-puterized numerical control for loading said memory with said in-formation, and (j) a coordinate drive control for actuating said motive means selectively under the control of said computerized numerical control or said tracing means.

2. A machine according to claim 1, wherein said trac-ing means is mounted on said cross-member, and during following of a template said coordinate drive control actuates said motive means in response to an output of said tracing means to cause said tracing means to follow the contours of the template.

3. A machine according to claim 2, wherein said encoder means are connected to said motive means to derive said positional information therefrom.

4. The machine of claim 3, which includes: means connected to said computerized numerical control memory for re-ceiving and permanently storing said loaded positional coordinate information to thereby permit erasure of said loaded memory.

5. The machine of claim 4 which includes: means to feed said stored positional coordinate information back to said computerized numerical control memory to thereby load the latter with the traced information regarding the followed con-tour of the template independent of said tracing means.

6. The machine of claim 3 which includes: digitizing means operatively connected to said template tracing means for causing the latter to stop and sample the positional coordinates of the template contour at selectively variable discrete spaced points depending upon the curvature characteristics of the said contour.

7. The machine of claim 6 wherein said digitizing means comprises a repetitive timing control connected to said template tracing means and with said timing control having a variable frequency.

8. The machine of claim 7 which includes means to manually vary the output frequency of said repetitive timing control.

9. The machine of claim 7 which includes means to automatically vary the output frequency of said repetitive timing control.

10. The machine of claim 9, wherein said automatic frequency varying means comprises: (a) means associated with said template tracing means for sensing a command mark disposed along the template contour, and with said command mark sensing means providing an output signal, (b) and feedback means connecting the output signal from said command mark sensing means with said repetitive timing control to change the output frequency of the latter, and the resultant sampling rate of said template tracing means.

11. The machine of claim 7, 8 or 9, wherein said repetitive timing control comprises a variable frequency oscillator.