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Publication numberUS1764318 A
Publication typeGrant
Publication dateJun 17, 1930
Filing dateMay 21, 1927
Priority dateMay 21, 1927
Publication numberUS 1764318 A, US 1764318A, US-A-1764318, US1764318 A, US1764318A
InventorsPeter Kruse
Original AssigneeBliss E W Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Marginal hook-forming mechanism for can-body-making machines
US 1764318 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

June 17, 1930.



P. KRUSE June- 17, 1930.



This invention relates to an improved hook forming mechanism particularly adapted for forming the marginal hooks of can body blanks, which hooks are eventually brought together and interlocked to form the side seam of the can body.

The object of this invention is to provide a mechanism of the described type which is of rugged and compact construction, which may be readily adjusted, and which, because of its novel design, permits of positive and accurate operation at relatively high speeds. A specific object of the invention is to provide a powerful resilient blank-engaging means whereby such blank is held in a fixed position during the hook-forming operation, n

the actual element engaging the blank to thus position it, being known as a presser foot. A further object of the invention is to provide means formaintaining a relatively slight pressure upon the blank while it is being fed between the said presser foot and the guideway along which the blank moves.

The invention further contemplates means for adjusting the pressure of the said presser foot, both during the interval when the blank is being fed under it, and when the pressure is increased to positively hold the blank in a fixed position. The invention also provides an intermediate actuating member interposed between the presser foot device and the hook-bending means whereby the movement of the latter is transmitted and modified to impart to the presser foot device the required operating forces, adjustable cam means being also provided between the said hoolebending kmeans and the intermediate actuator whereby both the extent and timing of the movements of the presser foot device may be regulated. The aforesaid intermediate actuator affords a simple construction by means of which the movements of the hook-bending mean-s, which movements are necessarily of considerable amplitude, may

1927. Serial N0. 193,275.

would otherwise interfere with the removall of theblank by the sliding feed bars as generally employed in body-making machines.

Further objects of the invention'reside in constructional details and particular combinations o-f elements whichwill be apparent from the following description in which reference is had to the accompanying drawings, wherein:

Figure 1 isa front elevation partly in section ofan embodiment of the invention, as

applied to a can body-making machine, thel parts of the mechanism being shown iny one eXtreme position in which the presser Afeet are gripping the blank and the hook-bending knives have been moved to completely form the hooks at both sides of the blank.

Fig. 2 is a fragmentary view similar to Fig. l except that the various parts of the mechanism are shown inl the position which they occupy just before the beginningy of the hook-bending operation.

Fig. 3 is a plan view of the mechanism shown in Figs. l4 and 2.

Fig. 4 is a front elevation partially in section of a'modified form of the invention, the various parts of the mechanism being shown in the eXtreme position correspondingl to that of Fig. 1. v

Referring now to the embodiment illustrated in Figs. 1, 2 and 3, it will be seen that the hook forming mechanism is mounted centrally of, and in close proximity to, the table l along which the can body blanks are fed and subjected to the successive operations usual in can body-making machinery. Each of the devicesfor forming the two marginal hooks comprises three independently movable Vmajor elements,

these being the oscillating presser foo-t carriers 5, 5, the intermediate actuator members 6, 6 which control the movement oil the presser foot carriers, and the oscillating hook-forming members 7, 7, which also cooperate with the said intermediate actuator members 6, 6', totransmit motion 'from the actuating rods 8, 8 to the presser foot cai riers through the said intermediate actuator members.

The right and left hand hooks must be bent in opposite directions from the plane ot the blank in order that they may be caused to interlock when brought together around the usual can-body-orming horn.l For this reason the movements' of the right and lett hand hook-forming members must be in 0pposite directions, and this necessarily gives rise to dierences in construction between the mechanisms for forming the right and left hand hooks respectively. The latter mechanism will be described first.

It will be observed that the hook-bending member 7 and the presser -foot carrier 5 are mounted so as to independently swing or oscillate about a common axis 9. The intermediate actuator member 6 is mounted to oscillate about a separate axis l0. At the lower left extremity of the hook-forming member' 7 a swinging pin connection 1l is provided whereby the substantiallyT vertical movements of the actuating rod 8 are transmitted to the said member causing it to oscillat-e about the axis 9. This hook-'forming member also carries at a point above and somewhat'to the lett of the said connection to the actuat'ng rod 8, a pin l2 upon which is carried a cam roller 13. The cam roller 13 co-operates witha cam element 20 at the lower end of the intermediate actuator member 6 to transmit movement from the said hook-forming member 7 to the said actuator member, the relationship of the parts being such that a clockwise rotationo'rmember 7 about the axis 9 causes a similar rotation of the said intermediate actuator member 6 around the axis l0. Because oi. the opposite disposition of the members G and 7 with rcspect to their axesV of movement, it results that an upward movement of actuating rod 8 causes a downward movement of the intermediate actuator member.

The upward movement of the intermediate actuator member 6 is transmitted to the upper end oi' the presser foot carrier 5 through a heavy spring 22, and when it is desired to transmit the reverse movement oic member 6 to the presser foot carrier, a one way or lost motion mechanical linkage may be employed. For this purpose a rod 28 is threaded into the base of the spring-retaining recess 24 in the member 6. This rod projects freely through a bore 25 co-axial with the spring-retaining cup 26 formed in the head of the oscillating carrier 5. The

upper end of rod 23 is threaded to receive an adjusting nut 27, the latter being locked in desired position by mea-ns of lock nut 28.

Tthas been found when using can body blanks oi the` usual thin sheet gauges that it desirable at all times to` maintain at least a slight pressure upon the presser foot carrier even while the blanks are being fed under the presser toot, and for this reason nut 27 is ordinarily adjusted so that the link or rod 28 will not act upon said carrier. It unusually heavy blanks are to be employed, itis not necessary to maintain pressure upon them as they are fed under the presser foot, because such blanks will lie flat by virtue Ot' their inherent rigidity. In this case it may be desirable to adjust nut 27 so that upon a predetermined downward movement of the intermediate actuator 6, the presser foot carrier will be swung counter-clockwise around the axis 9, thereby elevating the presser toot situated at the lower end thereoi.

The presser foot proper comprises preterably a hardened steel bar 30 securely attached to the lower end of the oscillating carrier 5, as by means of screws 81. This presser foot bar, in addition to affording on its lower face a flat blank-engaging area whereby the blank is guided and during the hook-forming operation held securely ink place, provides a knife-like edge 82 which constitutes the form or die over which the edge of the blank 33 is bent to form the marginal hook 3d.

The oscillating hook-forming member 7 which swings aboutthe axis 9, as hereinbefore described, carries a supporting ledge or rib Ll() extending in a iore and att direction A (parallel to axis 9), upon which is mounted the hook-forming knife el. This knife comprises a bar of hardened steel having preterably a thin edge portion 4:2 co-operating with the edge 82 of the presser toot bar 30 to form the hook 34 in the blank. Knife atl is secured to the ledge 40 by means of screws e3, and its transverse adjustment is positively maintained by means ot screws dfi. These screws are threaded into a depending tin 45 formed integrally with the member. The screws are advanced to bring the hook-forming knife 4l into correct relationship with the edge of the presser foot bar and then locked by means of lock nuts 8: The screws d3 which clamp the knife 'l pearing guides 50 are provided. While the blank is moving into position, the guides lilla 50, at either side thereof occupy the position indicated in Fig. f2. The guides eX- tend in a fore and aft direction parallel to the presser feet 30, 30 and at a distance therefrom, which distance determines the part of the blank which is utilized to form the overturned hook. The guides are moved vertically away from the edges of the blank by the action of the oscillating hook-bending knives 4l so that they do not obstruct the movement of such knives during the hook-bending operatiion, and this is permissible because of the fact that prior to the displacement of the guides the blank is firmly gripped by the presser feet, as hereinbefore set forth.

The left hand disappearing guide is at all times, except at the moment the hook is being formed, maintained in the operative or guiding position shown in Fig. 2 by the action of compression springsl at either end. The guide 50, asbest seen in Figs. 3 and 4 comprises a horizontal bar having somewhat enlarged ends 52 which slide vertically in suitable guideways 53. The right hand face of these guideways comprises removable guardplates 54, heldin place by screws An angle 54 on the guard plates extends over the guideway and serves to retain springs 5l in position. The working face of the guide 50 is preferably provided with a. removable face plate 56, so that this may be renewed without replacing the entire disappearing guide.

The left hand hook-forming mechanism hereinbefore described is mounted upon a substantial frame member which provides the necessary supports for the two axes 9 and 10, and also the guideway 53 within which `the disappearing guide 50 is mounted. The axis 9 may comprise a shaft of uniform diameter extending from one side of the frame to the other. The end bearings may be either free or fixed in the frame. On this shaft midway between the sides of the frame, the oscillating hookforming member 7 is mounted, the bearing preferably being provided with abushing 61. The presser foot carrier member 5 has extensions 62 which embrace thesaid shaft at opposite sides of the bearing for the Vhookbending member, the carrier thus forming a fork or yoke whichbridges said member. It is immaterial whether the bearings of the carrier yoke be fixed or free on the shaft 9 since the shaft itself is free to rotate, but in the embodiment illustrated the carrier yoke is secured tothe shaft by means of set screws 68, and this prevents the axial displacement of the shaft.

The intermediate actuator member 6 is mounted upon a shaft 10, which shaft is journaled in bearings 64 provided in the upwardly-extending arms 65 of the frame 60. It will be seen that the frame 60 supports all of the moving parts of theleft hand hook-bending mechanism so that it may be moved outward or inward along the transverse slide k60L in the table l, by means of screw 60h, to accommodate can body blanks of various widths. The frame, when adjusted to the correct position, is securely Y clamped to the table by any suitable means, such as a screw 6()c passing through a bridge piece-60d. The guideways along which tie blanks are fed and which are formed inpart by the cross piece 2 of frame 60, are consequently transversely adjusted in order to accommodate them to blanks of various widths whenever the position of frames 60, 60 is changed. This feature of adjustability is well known and generally employedl body machinery. Such mechanism is not the' subject of the present invention. It will be understood thatsuch blank-shifting mechanism mustpbe properly synchronized with respect to the hook-forming devices, so that the blanks are successively fed beneath the presser feet, brought torest, and permitted to remain stationary while the presser feet effectively grip the blank and the marginal hooks areV formed on the blank.

The hook-forming mechanism may he actuated by any vsuitable means for imparting a reciprocating motion to the actuating rods 8, 8. j

The general characteristic of 'the three primary members 5, 6, 7, and 5', 6, 7 of Vthe left and right hand hook-forming mechanisms respectively is that the parts be made as light as possible consistent with strength and durability, so that high speeds can be obtained vwithout excessive vibration. To this end, eachof theparts menticnedhas beenchanneled out wherever possible so that their main areas consist of a relatively thin metal web.

rlhe right hand hook-forming mechanism corresponds very closely in principle to that of the mechanism on the left, hereinbefore described. Because of the fact that the right hand hook must be bent downwards or oppositely to the left hand hook, the axis V9 of the oscillating hook-bending member 4" is disposed below the blank instead of above it.

The vhook-bending knife 41 is identical with the knife 41 and is similarly mounted upon the oscillating member 7 except that it is inverted. In forming the hook, the member swings counter-clockwise about the aYls 9', causing the knife 41 to swing downwardly and bend the hook over the edge of the stationary member 67. It will be observed that it is the edge of the guide-facing s rip 67 over which the hook is formed inthe present case, whereas in the left hand mechanism the hook is formed over the edge 32 of the presser foot. The left hand guide facing strip 67 yand the right hand presser foot bar 30 are therefore not subjected to any appreciable wear. These corresponding elements on opposite sides are preferably made so that they may be interchanged, and when the edge of the left hand presser foot becomes worn it may be interchanged with the corresponding right hand member, and a similar interchange may be made between the right hand guide facing strips 67 and 67. Like the member 7, the hook-forming member 7 is oscillated by an actuating rod 8, the movement of such rod being, however, in the reverse direction to form the right hand hook, the right hand rod 8 moving upwards to accomplish this result while the left hand rod 8 moves downwards.

The-oscillating motion of member 7 about axis 74 is transmitted by means of a cam roller 13 to a cam element 20 carried on the downwardly projecting arm of the intermediate actuator member 6. This member swings about the axis 75 and transmits its motion through a compression spring 22 to the presser foot carrier 5. In this construction the presser foot carrier and the intermediate actuator oscillate about the common axis 7 5, whereas in the left hand mechanism it is the hook-forming member 7 `and the presser foot carrier 5 which rotate about a common aXis. Because of the somewhat different movements of the members in the right hand mechanism, the contour of cam 20 differs from that of cam 20 in order to effect the engagement of the presser foot in proper time relationship with the movement of the hook-forming knife 41, as is clearly shown in Figs. 1 and 2.

The frame or carriage 60 upon which the members of the left hand rl'iook-forming mechanism are mounted, is necessarily of a somewhat different shape as compared with the frame 60, because'of the'diiferent disposition of the two shafts upon which the oscillating members are mounted. The said shafts are journaled in the side walls of the frame 60', and the frame also supports and constitutes a part of the guidway 53 within which the disappearing guide member 50 is adapted to slide. The right hand disappearing guide comprises a horizontal bar A50 which. lies underneath the downwardly swinginghook-forming knife 41. At either end of thisguidebar arms 77 extend vertically into the guideway 53 so that the hook-forming knife 41 is free to pass through the guide, which is in the form of a U. This guide bar is maintained in contact with thelower side of knife 41 by means of tension springs 78 which engage the upwardly-extending arms 77 of said guidebar. These arms are preferably bored to provide a recess 79 within which the said springs are housed, and the spring is fastened at the lower end of such chamber by means of a pin 80. The upper ends of the tension springs 78 are supported by pins 81 carried by the guard plates 82 corresponding to the guard plates 54 hereinbefore described. The guideway 53 comprises a channel in the vertical wall of frame 60, the disappearing guide memberbeing retained in such channel bythe guard plates 82 which are fastened on the face of said frame.

The function and operation of disappearing guide 50 is substantially like that of the left hand disappearing guide 50 except that the latter is engaged by knife 41 and swung upwardly out of-the way, whereas guide 50 is engaged from above by knife 41 which swings downwardly in forming the right hand hook. The right hand guide is restored to its normal guiding position indicated in Fig. 2, by the action of tension springs 78, which act upwardly.

The operation of the above-described hook-bending mechanism is as follows: The can body blanks are fed by any suitable means into the position shown in Fig. 2, the proper n alignment and transverse disposition of the blanks being insured by the marginal disappearing guides 50, 50. The front or leading edges of the presser foot bars 30, 30', beneath which the blank is fed, are slightly beveled or rounded so as to insure t-he entryV of the blank thereunder. Where blanks of the ordinary light gauge material are employed, the presser foot is permitted to engage the blank with a slight pressure (due to the unbalanced Weight of the presser foot carrier) during the movement of the blank into its final position prior to the hook-bending operation. The blank is brought to rest in the position where it will be acted upon over its entire length by the lhook-bending mechanism, and is thereafter securely clamped in this position by the` downward movement of the presser feet. This clamping action is brought about through motion transmitted from the actuating rods 8, 8, cams 20, 20, intermediate actuators 6, 6 and springs 22, 22. i presser feet, the hook-bending members 7 continuev to move, and their motion is transmitted to intermediate actuators 6, 6, respectively, and this motion is permited after the stopping of the presser foot car- After the effective engagement of the riers because of the resilientconnection afforded by the springs 22, 22. The contin'ued counter-clockwise movement of the hook-bending members 7, 7 about their respective axes 9 and 74 cause the knives 41, 41 to simultaneously engage the portions of the blank which extend beyond the presserfoot and guide facing members 30, 67, and 30', 67, and thereafter to bend these marginal portions of the blank into the V shaped hook shown in Fig. 1. The left hand blank edge is bent upwardly around the edge 32 of the presser foot carrier, and the right hand blank downwardly around the hook-forming edge of guide facing 70. The position of the knives upon the completion of this operation is shown inF ig. 1. Thereafter, the reversemovement of the parts occurs, the left hand hook-forming knife swinging downwardly and permitting the disappearing guide 50 to return to its guiding position, while the right hand knife 41 swings upwardly and permits disappearing guide 50 to rise to its normal guiding position. After the knives have passed beyond the plane of the blank, the continued swinging of members 7, 7 upon which they are mounted, through their Vaction on the cams controlling the movement of intermediate actuators 6, 6, respectively, relieves the pressure upon springs 22, 22, thereby releasing the presser feet from the blank. The blank having its marginal hooks thus formed is then moved out from under the presser feet and another blank brought into position by any suitable feeding means.

In Fig. 4 there is illustrated a somewhat modified form of my invention. This construction corresponds generally to that illustrated in Fig. 1, vso that except for the following changes, the description of the first form will apply to the second. In the construction illustrated in Fig. 4, adjustable cam actuating blocks 90, 90 have been substituted for the cam rollers `13, 13 shown in Fig..1. These blocks are mounted upon bosses 91, 91 formed on the lface of hookbending members 7, 7 respectively. These members are each provided -with a forwardly-projecting shoulder or'ledge 92, 92, through which are threaded adjusting screws 93, 94, and 93, 94, respectively.

These screws bear against a flattened surface of the cam blocks at points on either side of the bosses in such manner that when one ofthe screws is advanced and the other withdrawn, a small rotative movement will be imparted to the cam blocks. This movement will cause a shifting of the effective contact surfaces 95, 95 of the right and left hand cam blocks so that the timing of the cam action may be varied. This adjustment permits of compensation for wear and also enables-an operator, in setting up the machine for any size of can body blank, to accurately adjust the relative movement of the presser feet with respect'to the hook-- forming knives.

In the construction shown in Fig. 4, the main presser foot springs 22, 22, which correspond l in function to the springs shown in Fig. 1, are provided with tensionadjusting means vwhichy comprise the threaded spring-retaining plugsl 97 97. These plugs screwed into the top of the spring housing formed in the presser foot carriers and are maintained in adjusted position by means of lock nuts 98, 98.

gn both the right and left hand mechanisms an auxiliary presser foot spring 99 is provided, this spring lying within the helical spring 22 `hereinbefore described. The function of this auxiliary spring is to maintain a-certain small pressure upon the presser foot during those periods when the blank is being fed thereunderl or removed. The relatively heavy springs 22, 22, which cause the positive gripping of the blank during the hook-bending operation are preferably designed so that when the intermediate actuators have dropped to their lowermost position, which action occurs during the feeding of the blanks, no pressure will be transmitted to the presser foot carriers therethrough. This result is obtained simply by adjusting the threaded plugs 97, 97 so that when the intermediate actuators are in their lowermost positions the distance between the said plugs-and the spring seats of the .actuators is just equal to or slightly in excess of the normal untensioned length of springs 22, 22. It would be very diilicult to adjust a` single heavy duty spring Y of this type so that in one position it would cause the presser foot to effectively grip the blank, and in another to maintain a gentle yielding pressure suiiicient to insure the proper guiding of the blank as it is fed under the presser foot, and forthis reason the auxiliary spring 99 is employed.V This spring also serves to take out anybacklash which might otherwise occur 'between the cam and cam block, and between the intermediate actuator and the presser foot carrier.

Since the operation of the first embodiment of the invention `has been fully described,`the operation of the construction shown in Fig. 4 will be obvious. v

Whileonly two possible constructions, according Vto my invention,- have been described and illustrated, it will be understood that the invention is not limited there- A to but may be otherwise variously modified and'embodied without departing from the claims. c

spirit thereof, asset forth in the following bodyl making machines, said mechanism comprising blank-gripping means, hookbending means, intermediate, independently-movable means positively actuated by said hook-bending means and a yielding connection between said blank-gripping means and said intermediate means.

2. A hoolcforming mechanism for can body making machines, said mechanism comprising blank-gripping means, hookbending means, mechanism for oscillating said latter means and an independently oscillating intermediate actuator operatively connecting said means, and being moved differentially with respect to said blankgripping means by said hook-bending means whereby movement of the latter is transmitted in modified degree to the said blankgripping means. v

3. A hook-forming mechanism for can body making machines, said mechanism comprising blank-gripping means, hookbending means, an intermediate actuator, cam means interposed between said hookbending means and said actuator adapted to transmit motion from the former to the latter, and a yielding connection between said actuator and said blank-gripping means.

et. The mechanism according to claim 3, further characterized in that cam-timing means are provided whereby the timing of said cam means may be varied to alter the relative movements of said blank-gripping and hook-bending means.

5. A hook-forming mechanism for can body making machines, said mechanism comprising blank-gripping means, hookbendino' means, a main spring adapted toV transmit force from said hook-bending means to said blank-gripping means only when said means are in certain relative positions, andan auxiliary spring adapted to transmit force between said means when said main spring is inoperative, lwhereby the blank-gripping means will maintain a rel atively light pressure on the blank when `said blankis in motion, and a relatively high pressure when saidblank is gripped during the hook-bending operation.

6. A hook-forming mechanism for can body making machines, said mechanism comprising blank gripping means, hook'- bending means, an oscillating drivingA part adapted to actuate said hook-bending means, and yielding connecting means adapted to transmit force from said hook-bending means to said blank-gripping means, said force varying in different positions of said hook-bending means from zero to the value desired for properly gripping the blank during the hook-bending operation.

7. A hook-forming mechanism for can body making machines, said mechanism comprising a pivotally mounted presser foot, a

hook-bending member independently npivot-v ed upona fixed part of the mechanism, a

yielding connection between said memberV and Vsaid presser foot', and actuating means adapted to oscillate the said member, the arrangement of the mechanism being such that the movement of the hook-bending member causes the presser footAto grip the lank prior to the hook-bending operation.

8. A hook-forming mechanism for can body making machines, said mechanism comprising a frame, a hook-bending member, driving means therefor, an intermediate actuator member and a presser foot member, the three members being pivota-lly mounted on said frame and so related that force applied by said driving means is transmitted by said hook-bending member to said actuator member, which, in turn, actuates the said presser foot member, the saidA presser foot member and one of the two first-mentioned members being pivoted about a common axis.

9. A 1hook-forming mechanism for can bodyY making machines, said mechanism comprising an oscillating hook-bending member, a presser foot member, an intermediate actuator between said members, a spring interposed between said intermediate actuator and the said presser foot member, and cam means adapted to transmit motion from said hook-bending member to said' intermediate actuator.

10. The mechanism according to claim 9, further characterized in that said cam means comprises a cam surface, and a cam fol-l lower co-operating therewith, said follower and cam surface being relatively adjustable whereby the relative motions of the hook' bending member and the said lintermediate actuator may be varied.

l1. A hook-forming mechanism for can body making machines, said mechanism comprising a blank-gripping member, a hookbending member, and an intermediate member moving in a different path or orbit from that of themotion of the saidhooksbending member, positive means adapted to transmit motion from said'phook-bending member to said intermediatemember, and a Vyielding' connection between said intermediate member and the blank-gripping memberf.

l2. A hook-forming mechanism for can body making machines, said mechanism comprising a blank-gripping member, a hookbending member, and cam means interposed therebetween adapted to convert a continuous motion .of said hook-bendingv member .the engagement of the blank by said hookbending member and the dwell is maintained while the hook is being formed.

13. rIhe mechanism according to claim 9, further characterized in that said cam means comprises a cam Surface and a cam follower cooperating therewith, the said cam follower being angularly adjustable -Whereby its relationship with respect to said cam surface may be altered to vary the timing of the said intermediate actuator.

In Witness whereof, I have hereunto signed my name.


Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2438057 *Mar 23, 1944Mar 16, 1948Kilham PeterBending brake having unitary actuating means for clamping and bending sheet metal
US2726702 *Mar 2, 1951Dec 13, 1955Ed LaxoHook forming machine
US2871909 *Aug 4, 1952Feb 3, 1959Pines Engineering Co IncUniversal and adjustable mounting for a clamp die in a tube bending machine
US2932336 *Aug 23, 1955Apr 12, 1960American Can CoCan body hook forming mechanism
US4455857 *Sep 27, 1982Jun 26, 1984Salvagnini Transferica S.P.A.Forming press for bending a blank
US4487051 *Dec 17, 1982Dec 11, 1984Toyota Jidosha Kabushiki KaishaPress apparatus
US6477880 *Jan 22, 1999Nov 12, 2002Kuka Schweissanlagen GmbhFlanging device with pressing and clamping elements
EP0579893A1 *Jul 23, 1992Jan 26, 1994MONETA IMPIANTI S.p.A.Apparatus for forming weldless edges on sheet metal articles
U.S. Classification72/305, 72/313
International ClassificationB21D51/26, B21D51/28, B21D19/08
Cooperative ClassificationB21D19/08, B21D51/28
European ClassificationB21D19/08, B21D51/28