US2866428A

US2866428A - Automatic sheet metal gauging and working machine

Info

Publication number: US2866428A
Application number: US533718A
Authority: US
Inventors: Harry E Stanfield; Ivar B Dahlstrom
Original assignee: DAHLSTROM MACHINE WORKS Inc
Current assignee: DAHLSTROM MACHINE WORKS Inc
Priority date: 1955-09-12
Filing date: 1955-09-12
Publication date: 1958-12-30
Anticipated expiration: 1975-12-30

Description

Dec. 30, 1958 V H. EQSTANFIELD ETAL 2,866,428

AUTOMATIC SHEET METAL GAUGING AND WORKING MACHINE Filed Sept. 12, 1955 3 Sheets-Sheet 1 K &

Lil 36' 62: 60/52 FIG. 2

FIG. 1

I 529) 5Z 6b ill/l l IN VEN r023 Harry E. Szanfield J 1% Iv r15. Dahlslmm WW2; am fltlornags Dec. 30, 1958 H.. E. STANFIELD ET AL 2,866,428

AUTOMATIC SHEET METAL GAUGING AND WORKING MACHINE Filed Sept. 12, 1955 3 sheets sheet 2 I N V E N T025 Harry E SZmZz Q'eZd I 1/011 Dc/hls ran 2 vow M a, 14 izo r116 95 Dec. 30, 1958 H. E. STANFIELD ETAL AUTOMATIC SHEET METAL GAUGING AND woaxmc MACHINE Filed Sept. 12, 1955 3 Sheets-Sheet 3 7 v fix-r. 6

V I 86 F 92 7 V Q, i y

") "if 4%]? H! m4 1 I M v [[006 AFT-U I 1H U1'-/fz" //z" 1 :"-4 mg I05 INVENTOIQSI I 0 Harry 552a 'ld Ivar 5. Dahls ram 'ations.

United State Pa o AUTOMATIC SHEET. 'METAL GAUGING AND WORKING MACHINE This invention relates to an automatic sheet metal severing and working system in which repetitive shearing and working operations on sheet metal .may be carried out with exactitude and within tolerances heretofore believed unachievable in the sheet metal art. A continuous strip may be sheared or otherwise operated'upon at. predetermined repetitive positions along the length thereof, and the distance between such positions may be varied from zero to any predetermined maximum without mechanical adjustment and while the strip is in motion.

It is an object of the present invention to provide an automatic sheet metal severing system in which the sheet metal is cut into predetermined lengths with accuracy heretofore considered unattainable in the art.

It is another object of this invention to provide an improved system for working sheet metal wherein an electronic counter responds to impulses corresponding to small increments of sheet length and said counter con-.

trols the metal working means associated therewith.

It is another object of this invention to provide a shearing system in which the desired length of sheet-metal to be cut may be changed by mere manipulation of a control panel housing an. electronic counter, eliminating the need for experimental cuts,.li ne shut down, and the like.

It is a further object of the present invention to provide an automatic sheet metal working system in which various operations onsheet metal are quickly and auto matically effected at desired locations along the length of a sheet with ease and accuracy.

It is still a furtherobject of this invention to provide an improved system forshearing or otherwise working sheet metal wherein an electrical analog of sheetmetal length is generated whereby greatly increased accuracy and precision is attainable. I

It is a still further object of this invention to provide a novel sheet metal working system including an improved clamp member which insures accuracy in the course of the sheet metal cutting and forming operemploying movable shearing and working apparatus which moves with .the driven sheet metal strip assuring optimum dimensional accuracy, continuous operation, and the absence of lost motion,

The above and other objects .of this invention will become more apparent from the followingdescription,

accompanying drawings, and appended claims.

:In one embodimentxof :invention an". electronic D to Fig. l, a cutting sheet metal into predetermined" lengths is illus- "trated schematically.

2,866,428 P at ent ed Dec. so, 958

counter receives impulses as a strip of sheet metal is passed under a shear, each impulse representing ,a known incremental length of the strip. When a predetermined reference shouldnow be madeto the drawings, wherein:

Figure l is a schematic representation of a continuous sheet metal shearing system incorporating the teaching of this invention.

Fig.2 is a schematic representation fof alsecon'd'em bodiment of this invention including a system 'employin'g a. plurality -of sheet metal working devices and a" sheet metal shear adapted forcontinuous operation;

Fig. ,3 is an elevational view partly in-section ofa feeder and straightening machine incorporating an 'electromechanical transducer forgenerating impulses Fig. 4 is a fragmentary side elevational view of' an electromechanical transducer.or impulse generator to be utilized with the embodiments of Figs. '1 and 2;

Fig. S-is. atop plan view, partly in section, .of the generator illustrated in Fig. 4; '-Fig.-6 is afragmentary front elevational view partly in'section of an air clamp forming, apart oftheinvention; and i Fig.- 7 is a sectional view of'the .air line 77 of Fig. 6. g It should-be understood, that the illustrations arev more or "less diagrammatic informto better illustrate'theappli-catio-n of. theprinciples involved. The various details "of metalworking machinery are so well known injthe art that further illustration herein would be considered superfluous.

Referring nowto the drawings and more particularly continuous or semi-continuous system fo The system "operates on ,a coil or wound continuous strip of sheet metal 112, which'Q'is positioned on a coilholder 310. Theen'd'of theflco'il is;threaded between roller members'14 andi16 of afeeder 'an'd straightening.machinei'18.

Thelrollers

14 and 1 116 are driven by mo-tive' means, not shown, so thatthe "sheet metalstrip is forced to proceed through. the machine/18 and at the same time any set','cur.vature, or irregularities in the surface thereof will be removed. Up,on,emerg'in' g from the straightening machine'18, the sheet metal, s,t'r ip proceeds across the top surface ofa' hump table 20. The table 20 comprises a supporting framework .21 upon which are mounted a plurality of freely rotatable-rollers 22 which are journalled. in oppositely disposed 'longitudinalchannels 23 of the table. After proceedinglacross the top of the hump table 20, the sheet metalfstrip passes 'througha shear 24., The

bed with which the blade cooperates to sever sheetmetal passing therethrough. Theshear is conventionally operated by an electric motor carrying a flywheel having substantialmass. None of -the. above is illustrated in the drawings-as the details arefamiliar to one Skilled-inthis art'and form no part of the instant invention. Actuation of the .shear blade is electrically controlled i118. manner togbet'described in greater" detail.

For a more complete understanding of this invention,

clamp taken on shear 24 is of "a congention'al type having a. movable shear; blade and a spacedl dielor' The severed lengths of sheet metal are withdrawn from the shear 24 by a conveyor 30 which may be adapted to move the lengths to subsequent work stations or store the length in a stacked relationship. The shear 24 is controlled either directly or indirectly an electronic length measuring system. The system comprises a measuring roller 34, an impulse generator actuated thereby, and an electronic counting device 26 energized with impulses from the generator 28. More particularly, the electronic counter 26 is of the preset'table type, having a control panel 36 associated therewith/'Thus the desired length of the sheet metal strip is introduced on the keyboard 36. As the measuring roller 34 turns the generator 28 applies impulses through conductor 41 to the counter 26; when the counter 26 indicates thenumber pre-set on the kepboard 36, a signal is applied through conductor 39 to actuate the shear 24. his apparent that the impulse generator 28 may be actuiated by any. roller, including the drive roller in the straightening machine 18, a straightening roller or the like: i

When employing the embodiment of Fig. 1, it will be noted that the roller members 14 and 16 in the straightningrnachine18 do not cease to operate during any phase of the shearing process, but continually drive the metalstrip forward over the surface of the hump table ;20. Consequently, when the blade of the shear 24 de- "fscends. and engages the sheet metal strip 12, the sheet metal continues to proceed into the straightening machine 18and, due to its inability to further proceed into the shear 24, builds a slight hump on the top surace of the table 20 until the blade of the shear 24 once again rises,.allowing the unsevered sheet metal strip portion to proceed therein. Itwill also be noted that the top surface of the hump table 20 has a convex configuration whereby a single gentle curvature is formed in the metal on the table, thereby obviating any possibility of the sheet metal strip 12 becoming distorted or applying excessive force against the shear blade.

The shear 24 may be somewhat slow acting and unprejdictable as the conventional shear utilizes a continuously running motor and flywheel and a clutch arrangement to engage the shear bladeto the motor for a single revolujtionn There may be an unpredictable delay in moving theshear blade when actuated by the counter 26, depending upon the instantaneous position of the flywheel and thenature of theclutch employed. To avoid any errors in the lengths of sheet metal produced by this system, a quick acting clamping device 25 is preferably employed at the shear whereby the sheet metal will be clamped quickly and consistently once the electronic {counter 26 has read out, indicating the desired length has passed, the shear blade. Following the clamping operation, the metal strip will be locked against further motion and a hump will begin to rise above table 20. Atthe same time the shear blade is actuated and returned to normal andthe clamp releases the strip 12. The accumulated length of flmetal strip quickly passes under the shear and this has already been accurately measuredby the electronic gauging system. It is thus seen that the clamping device 25 functions to stop the strip 12 relative to the shear 24.

As the shear 24 will be a relatively slow acting device, it is possible to energize the shear 24 and the clamp 25 at the same instant through conductor 39 as illustrated.

However, for more positive operation, the embodiment of 'Fig. 1 may utilize a limit switch which is actuated by strip engaging motion of the clamp 25 to, in turn,

actuate the shear 24.

An alternate method of cutting predetermined length of sheet metal strip 12 is to bring the entire strip to rest prior to shearing. To bring the system to rest with reasonable speed and accuracy the motive means, not

shown, which drive the strip holder 10 and.the straightimpulse per revolution.

ening and feeding machine 18 are utilized as dynamic brakes.

When a predetermined number of impulses have been generated and register in counter 26, power is removed from the motors and the motors preferably shorted through a small predetermined resistance. Thereby the motors function as brakes to stop the strip in a minimum time. It has been found that the amount of coasting under these conditions is quite consistent and repetitive so that the efiects thereof are cancelled out during semicontinuous repetitive cutting operations. It is apparent to those skilled in the art that only D. C. motors may be used as a dynamic brake; if A. C. motors are employed, a separate mechanical braking device must be employed.

The motors actuating the straightener-feeder unit 18 are controlled by conductors 32 shown in broken lines, in response to the information received in counter 26. In such a system, the bladeof the shear 24 may be actuated either manually or automatically following stopping of the strip to effectcutting of a desired length of sheet metal. A hump table is not essential in this type of operation, sincethe sheet metal strip is at rest during the shearing operation.

Utilization of the impulse generator 23 in combination with the electronic counter 26 for actuation of a shear 24 or other sheet metal working apparatus is an important novel concept taught by this invention. The electronic counter 26 may be any one of various types well known in the art. The particular counter employed in the illustrated embodiments is a five digit decade counter impulses. The plurality of knobs or buttons 43 are pro vided in digital banks whereby the number of impulses required to actuate the shear may be manually preset. Theirnpulse generator 28 utilized in the shearing system may comprisea tachometer generator, a target of an elec tric eye system, or any other means adapted to transmit electrical impulses, the number of which are proportional to the rotation of measuring roller 34, which is, in turn, proportional to the length of material fed through the shear. The incremental strip length represented by each registered in the counter depends upon several factors. The circumference of the measuring roller 34, the gear ratio between the measuring roller 34 and the impulse generator 28, and the number of impulses per revolution of the impulse generator 28 are the critical factors in the instant structures. In the illustrated embodiment of 12 inches, the gear ratio between the measuring roller 34 and the impulse generator 28 is 1:12 and the impulse generator 28 creates electrical impulses Therefore, for every 12 inches of material passing through the system, the measuring roller 34 rotates once, the impulse generator 28 rotates twelve times, and 1200 impulses are generated. It clearly follows that each impulse, therefore, represents .01 inch of sheet length. Consequently, should a six foot length of sheet metal be desired, 6X12 100, or 7200 impulses is the electronic counter trip figure set in the central control panel 36. As the clamping and shearing operations are quite precisely repetitive, and the clamp or shear is energized with an accuracy of .01 inch, the tolerance to which the successive lengths of strip material may be sheared will be of the order of 1.01 inch. It should ..be noted that this error is a fixed value, irrespective of the length being cut, and is not a percentage of the overall length. It should also be noted that there is no possibility of a cumulative error as might occur when gauging on previously cut strips or the like.

It clearly follows that with different gear ratios between the measuring roller or other equivalent component and asses impulse generator 28, or. with a different number of impulses per revolution of impulse generator 28, any number of impulses per increment of length would be obtainable, such as tenths, hundredths, thousandths, etc. per inch,.foot, yard, etc.

'Fig. 2 is a schematic representation of an alternate system which enables a number of metal working operations to be effected on a predetermined length of formed sheet metal which is out, following the working operations, from a continuous coil or strip 13. As in the system of Fig. 1 above described, a coil or continuous strip of sheet metal 1-3 is mounted on a coil holder 15. The end of the sheet metal coil is threaded between the roller members 17 and 19 of a forming machine 21. The forming machine 21 may be any one of many conventional types which roll the strip 13 into various channels and the like, having cross-sectional configuration determined by the sequence of rollers 17 and 19. Upon emerging from the forming machine 21, the sheet metal strip 13 is passed through the various movable dies h, 52, 54 and 56. These di-e members are movable over a fixed bed '58 by means of wheels 6% or slides. in the idle condition, the movable dies are maintained against the fixed blocks 62, positioned on the bed 58.

The four movable dies illustrated in Fig. 2 represent apparatus designed to work the sheet metal strip passing therethrough. For instance, in one particular embodiment, the movable die 56) is a notcher, the die 52 is a lancer, die 54 is a piercer, and die 56 is an embosser. Each of the movable Working units 59, 52,, 54 and '56 is provided with a clamp 66 mounted for movement therevwith. The clamps 66 are controlled by an electronic counter 64 by means of conductors 33. The counter is energized with electrical impulses from generator 29 'by means of conductor 31. Should it be desirable to have the notching die 5%, for example, act upon the sheet metal strip at intermittent predetermined intervals, the electronic counter 64 is set so that, when the impulse generator indicates the desired length, clamp 66:! will engage the moving sheet metal strip and the die assembly '50will move over bed-58. A limit switch '7 positioned on the movable die 5% is tripped by motion of clamp 66, which in turn actuates notching element 72 of the movable die 5%). Following the notching operation, the clamp 70- and notching element 72 release the moving metal strip 13 and the die is returned by retracting means, not shown, to its initial position as defined by the block member 62. it is obvious that the other Working operations performed by the apparatus'carried by the movable dies 52, 54, and 56 may be operable in a similar manner.

Positioned beyond the desired work stations, a shear 74 or similar device is actuated by the electronic counter 64-. Shear 74 has a clamp 76 and shear blade and die 7'8 which are longitudinally movable in a manner similar to the movable dies 5'0, 52, '54 and 56. In the course of actuation of clamp 76, the shear blade '73 is actuated by means of a limit switch 89. The sheet metal strip portion which has been formed, worked, and cut, is then Withdrawn from the shear 74by other means. Movable dies are especially useful where operating on formed material which cannot be distorted or humped. Clamp 76 is actuated through conductor '35.

In Fig. 4, apparatus is illustrated whereby the rotational movement of the measuring roll 34 or other drive component is transmitted to the impulse generator 28. Measuring roll 34 drives a shaft 38, fragmentarily shown, which, in turn, rotatab'ly drives a gear id'lsee 5) of a speed ratio device 42. A number of universal joints 44 are interposed betwe n the shaft 38' and the speed ratio device 42 to provide for any angular disposition between the speed ratio device and the measuring roll Referring to Fig. 3, a mounting bracket 27, housing impulse generator 28 and speed ratio device 42a, are angularly disposed with-respect to a measuring. roll 34 in a feeder and straightening machine 18. Such mountings l 6 are facilitatedby universal auxiliary equipment which might be n'ecessary'in' particu; lar installations.

The speed ration device 42 comprises the aforementioned gear 40 which meshes'with and drives the gear member 4-6 which is of a'diameter less than that of gear member 40. Shaft 48, transmitting rotational movement of the gear 46 to 'theimpulse' generator'28, is provided with two universal joints 44a similar to universal 4 4'; which permit limited angular freedom between the speed increaser 42 and the impulse generator 28.

The clamps 25, 66 and 76 employed in the systems schematically illustrated in Figs; 1 and 2, are'illustrated in greater detail in Figs. '6 and 7. The clamp comprises a main cylinder 86 having a reciprocally movable projecting rod portion 88 which may be threaded, as shown,

to engage an apertured extension 9th. The cylinder 86' is supported by two brackets 92, more clearly shownin Fig. 7, which are afiixed to the top surface of a support-' ing framework 94. It is obvious that instead of fluid pressure'in cylinder 86, spring means or solenoid means may comprise the actuating means driving the rod 88 down- Wardly. Upon actuation of the cylinder 86, the rod 88 is forced downwardly to extend a clamp face itlbinto' gripping engagement with the sheet metal strip 110 through the linkage hereinafter described. Downward movement of rod 88 forces apair of horizontal driving links 96, which are pivoted to the extension'9 0'by means of shaft 98, to also move in a downward direction. The

drive links 596 force a pair of oppositelydisposed thrust links to approach a horizontal disposition in the course of the downward movement of the rod 88. Each of the thrust links 100 has one end in pivotal engagement with the corresponding end of horizontal drive link 96 by means of a pin 102 and has the other end pivotally connected to a fixed bearinglink 104' and-a clamp link 106-by a pin 101. Fixed bearing links 104' are pivot ally mounted in brackets 103 and clampflinks 106 pivotally mounted on pins in clamp face 1%. Thereby; opposed transverse motion of the pivot pins 101 produces changes in the angularrelationship of the fixed bearing links 104 and clamp links 1%. As the corresponding fixed bearing link 104 and clamp link Hi6 approach a linear relationship, the clamp face 1% is fully extended andrigidly engages the sheet 110. Complete equalization of the clamping force is produced by thedescribe'd balanced clamp. To prevent undue strain on the linkages and move ment of the clamp portion'ltls'in a directioncorrespond ing to movement of the sheet metal strip 110, support brackets 112 are provided. Brackets 112 have journalled therein wheel members 114 which rotatably engage a rear surface of the movable clamp portion 108, preventing movement of the clamp portion in the direction of the movement of the sheet metal. 110 as indicated by arrow 111. The clamp 66 assures-quick engagement of the sheet metal strip and is constructed to obviate any possibility of slippage or distortion of the clamp parts inthe course of the sheet engagement.

It is thus apparent that a novel sheet forming and sheet shearing system has beenprovided. The system utilizes the novel combination of anirnpulse generator in-communication with a measuring roller and an elec' tric counter, for performing sheet metal Working and shearing operations with an exactitude heretofore'unknown in the art. As has been previously mentioned, many. modifications of the illustrated system may be effected without departing from the spirit and scope of the inventive concept presented. For example, it is apparent that any impulse generator is in the system provided only that discrete detectable impulses may be generated to represent very small increments of length; Al'- though all operations have been described utilizing sheet metal, it is to befunderstood that other materials which lend themselves to theoperations previously described,

joints 44 and: other necessary are within the scope of the inventive concept. The inaseasas vention provided is to be limited, therefore, only by the scope of the appended claims.

We claim:

1. In an automatic machine for performing operations on sheet metal or the like, the combination comprising a measuring roller rotatably engaging such sheet metal, rotatable generator means actuated by the rotational movement of said measuring roller, said generator emitting a predetermined number of impulses per revolution of said measuring roller, reciprocally movable clamp means dis-- posed adjacent the path of such sheet metal and movable to a clamping position in said path, counter means actuating said clamp means upon receiving a predetermined number of impulses from said generator means, a limit switch disposed on said clamp means, said limit switch being actuated when said clamp is moved to the clamping position, and sheet metal working means disposed adjacent the path of such sheet metal actuated by said limit switch.

2. In an automatic machine for performing operations on sheet metal or the like, the combination comprising a measuring roller rotatably engaging such sheet metal, generator means actuated by the rotational movement of said measuring roller, speed increasing means interposed between said measuring roller and said generator means, said generator emitting a predetermined number of impulses per revolution of said measuring roller, reciprocally movable clamp means engageable with such sheet metal, counter means actuating said clamp means upon receiving a predetermined number of impulses from said generator means, a limit switch disposed on said clamp means, said limit switch being actuated when said clamp is moved to the clamping position, and sheet metal severing means actuated by said limit switch.

3. In an automatic machine for working sheet metal or the like, the combination comprising a measuring roller, at least one driving roller engaging said sheet metal and forcing such sheet metal to rotatably engage said measuring roller, a stationary bed over which said sheet metal passes, sheet metal working die means movable from a predetermined position over said bed, said die means having a clamp portion, a sheet metal working portion and a movable die .bed thereunder, generator means in communication with said measuring roller and emitting a predetermined number of impulses per revolution of said roller, counter means actuated by said counter pulses, said clamp portion being actuated by said counter means to engage said sheet metal, control means disposed on said die means and actuated by motion of said clamp means, said control means actuating said sheet metal working portion, said dies being driven over said fixed bed when said clamp portions are in engagement with said sheet metal, said clamp portion releasing said sheet metal after said metal working portions have operated, and means returning said die means to the original position after release of said sheet metal by said clamp portions.

4. In an automatic machine for working sheet metal or the like, the combination comprising a measuring roller, at least one driving roller engaging said sheet metal and forcing such sheet metal to rotatably engage said measuring roller, a stationary bed over which said sheet metal passes, a plurality of sheet metal working dies movable from predetermined positions disposed over said bed, each of said dies having a clamp portion, a sheet metal working portion and a movable die bed thereunder, generator means in communication with said measuring roller and emitting a predetermined number of impulses per revolution of said measuring roller, counter means actuated by said impulses, said clamp portions being actuated by said counter means, control means disposed on said working dies and actuated by motion of said clamp portions, said control means actuating said sheet metal working portions, said dies being driven over said fixed bed when said clamp portions are actuated, said clamp portion releasing said sheet metal after said metal working portions have operated, and means returning said dies totheir original positions after release of said sheet metal by said clamp portions.

5. In a device for working predetermined lengths of sheet metal or the like, the combination comprising a measuring roller adapted to rotatably engage such sheet metal, at least one driving roller frictionally engaging and moving such sheet metal, a table defining a substantially convex sheet metal path having one end adjacent said measuring roller, a stationary clamp member disposed at the other end of said path, electrical impulse generator means in communication with said measuring roller and emitting a predetermined number of impulses per revolution of said measuring roller, counter means receiving said impulses and actuating said clamp member upon receipt of a predetermined number of impulses, a limit switch actuated by said clamp member, stationary metal working means disposed adjacent said sheet metal and actuated by said limit switch, said driving roller forcing said sheet metal to form a hump on said table during actuation of said clamp and said stationary metal working means.

6. In an automatic machine for severing sheet metal or the like, the combination comprising a shear, drive rollers adapted to frictionally engage and move a sheet metal strip, a measuring roller, generator means in communication with said measuring roller emitting a predetermined number of electrical impulses per revolution of said measuring roller, a roller table defining a convex sheet metal path having one end disposed adjacent said measuring roller, said shear being disposed in proximity to the other end thereof, counter means in communication with said generator means and actuating said shear upon receiving a predetermined number of impulses, said shear means acting as a brake whereby said sheet metal is deformed on said roller table during the shearing operation.

7. In an automatic machine for working sheet metal or the like, the combination comprising a measuring roller, a driving roller engaging and moving said sheet metal, a stationary bed over which said sheet metal passes, a plurality of sheet metal working dies movable from predetermined positions disposed over said stationary bed, each of said dies having a clamp portion and a sheet metal working portion disposed over a movable die bed portion, generator means in communication with said measuring roller emitting a predetermined number of impulses per revolution of said measuring roller, counter means actuated by said impulses, said working die clamp portions and said sheet metal working portions being actuated upon said counter means receiving a predetermined number of impulses.

8. In an automatic machine for working sheet metal or the like, the combination comprising a measuring roller, a driving roller engaging and moving said sheet metal, a stationary bed over which said sheet metal passes, a plurality of sheet metal forming dies movable from predetermined positions disposed over said stationary bed, each of said dies having a clamp portion and a sheet metal working portion disposed over a movable die bed portion, generator means in communication with said measuring roller emitting a predetermined number of impulses per revolution of said measuring roller, counter means actuated by said impulses, said counter means actuating said working die clamp portions and said sheet metal forming portions upon receiving a predetermined number of impulses, said working dies being driven over said fixed bed when said clamp portions are actuated, said clamp portion releasing said sheet metal after said metal working portions have operated, and means returning said sheet metal working dies to their original positions after release by said clamp and working portions.

9. In an automatic machine for performing operations on sheet metal or the like, the combination comprising a measuring roller rotatably engaging such sheet metal, ro-

tatable generator means actuated by the rotational movement of said measuring roller, said generator emitting a predetermined number of impulses per revolution of said measuring roller, reciprocally movable clamp means disposed adjacent the path of such sheet metal and movable to a clamping position in said path, counter means in electrical communication with said generator means actuating said clamp means upon receiving a predetermined number of impulses from said generator means, and sheet metal working means disposed adjacent the path of said sheet metal and actuated to engage said sheet metal while said clamp means is in engagement therewith.

10. In an automatic machine for performing operations on sheet metal or the like, the combination comprising a measuring roller rotatably engaging such sheet metal, rotatable generator means actuated by the rotational movement of said measuring roller, said generator emitting a predetermined number of impulses per revolution of said measuring roller, reciprocally movable clamp means disposed adjacent the path of such sheet metal and movable to a clamping position in said path, counter means actuating said clamp means upon receiving a predetermined number of impulses from said generator means, sheet metal working means disposed adjacent the path of said sheet metal and actuated to engage said sheet metal while said clamp means is in engagement therewith, and means for actuating said working means whereby said working means engages said sheet metal only during actuation of said clamp means.

11. In an automatic machine for performing operations on sheet metal or the like, the combination comprising means continuously moving said sheet metal along a path through said system, electrical control means sensitive to the length of sheet metal passing from a source thereof along said path, reciprocally movable clamp means disposed adjacent said path and movable into a clamping position in said path, said electrical control means actuating said clamp means upon movement of a predetermined length of sheet metal from said source, sheet metal working means disposed adjacent said path, and means for actuating said working means while said clamp means is actuated.

12. In an automatic machine for performing operations on sheet metal or the like, the combination comprising a source dispensing said sheet metal or the like, means for continuously moving said sheet metal along a path through said system, electrical means sensitive to the length of sheet metal dispensed by said source emitting a predetermined number of impulses per predetermined unit length of said sheet metal, clamp means for said sheet metal disposed adjacent said path, counter means actuat ing said clamp means upon receiving a predetermined number of impulses from said electrical means, and sheet metal working means disposed adjacent said path and actuated by said counter means after said clamp means has engaged said sheet metal.

13. In an automatic machine for severing sheet metal or the like, the combination comprising shear means, a measuring roller rotatably engaging such sheet metal to be severed, tachometer generator means in communication with said measuring roller emitting a predetermined number of electrical impulses per revolution of said measuring roller, and counter means receiving said electrical impulses and actuating said shear means upon receipt of a predetermined number of electrical impulses.

References Cited in the file of this patent UNITED STATES PATENTS 1,919,999 Borton July 25, 1933 2,165,614 Cook et a1 July 11, 1939 2,183,159 Chesley Dec. 12, 1939 2,603,688 Cole July 15, 1952 2,633,195 Rupp Mar. 31, 1953 2,635,809 Camp Apr. 21, 1953