US2958242A - Metal forming machine - Google Patents

Description

i. ILA- -L. L. MARCHANT 2,958,242

METAL FORMING MACHINE Nov. l, 1960 Filed May 31, 1957 3 Sheets-Sheet 1 Lee Lloyd archcmt,

FIG. 2 By f his Attorney Nov. 1, 1960 2,958,242

L. L. MARCHANT METAL FORMING MACHINE I5 Sheets-Sheet -2 Filed May 3l, 1957 Lee Lloyd Marchant Oh @j his Attorney Inventor:

Nov. l 1960 Filed May 31, 1957 l.. L. MARCHANT 2,958,242

Plas

FIG.8A

Inventor: Lee Lloyd archant FIG. M

By wwf his AHorney 2,958,242 METAL FORMING MACHINE Lee Lloyd Merchant, 7106 Woodland Ave., Takoma Park, Md.

Filed May 31, 1957, Ser. No. 662,810

3 Claims. (Cl. 78-61) lMy invention relates generally to equipment for forming and shaping metal strips of widely varied sectional configuration and more particularly concerns a machine, highly flexible in utilization, for stretching or shrinking, as the case may be, metal strips of which sheet, at, bars, plate, angles and extruded shapes are but typical.

An object of my invention is to provide a machine adaptable at will in but a few moments time to stretch or shrink along their lengths as desired, metal strips of varied sectional configuration, which machine in itself is essentially simple in construction, sturdy and of long useful life, employing only a comparatively few moving parts and which in direct manner, and utilizing important mechanical advantages, may be adapted readily and rapidly for operation through either pneumatic, hydraulic or mechanical source of power.

A further object is to provide a machine of the general character described which is small, compact and simple in operation, which may be readily designed for either portable manipulation wherein the machine is moved along the work stock, or for installation at a fixed station, past which the work stock is moved during forming, which machine requires but minimum standby time for servicing or repairs, and which can be effectively ernployed by labor of but moderate skill and this after only a short period of initial training.

Yet another object is to provide a machine wherein, for experimental Work, repairs or small-quantity production, many shapes can be completely and readily customformed, without necessity for the preliminary provision of production dies, and which machine displays marked utility in a variety of fields of application of which, as typical and illustrative, may be listed removing wrinkles in metal or straightening metal parts after forming; facilitating nal t of all types and shapes of metal parts; and entirely forming a variety of shapes to be employed throughout the aircraft industries.

Other objects and advantages in part will be obvious and in part pointed out hereinafter during the course of the following description, reference being had for clarity of understanding to the disclosure of the accompanying drawings.

My invention, accordingly, may be seen to reside in the several component parts, structural elements, assemblies of component parts and arrangements thereof, and in the relation of each of the same to one or more of the others, the application of all of which is more fully set forth in the claims at the end of this specification.

For a more thorough understanding of my invention, reference may be had to the several views of the drawings, wherein I disclose, illustratively and as one embodiment of my invention, a portable-type machine which I prefer at present. In these drawings:

Figs. 1 and 1A essentially are side elevation and central vertical longitudinal views of the machine, with parts sec- States Patent tioned for clarity and the machine being disposed with its longitudinal axis extending horizontally, in readiness for use;

Fig. 2 is a plan view of the machine of Fig. l, partially sectionalized and taken at right angles to Fig. 1;

Figs. 3 and 4 are end elevations showing the right and left ends, respectively, of the machine disclosed in Figs. 1 and 2;

Fig. 5 is a transverse section taken Fig. lA;

Fig. 6 is a detailed sectional view of the machine taken on the lines 6--6 of Fig. 2;

iFig. 7 is an isometric view of the machine, disclosing the relationship between the jaw blocks and the jaws themselves;

Figs. 8 and 8A are plan and front elevational views of the stretching machine showing the manner in which the forming jaws function; and

Figs. 9 through ll disclose various sections stretched or shrunk to give desired contour by my machine.

Throughout the several views of the drawings, like reference characters denote like structural parts.

As conducive to a more ready understanding of my invention it may be noted at this point that, particularly in the field of aircraft fabrication and as well, in the sheet metal trade generally, urgent immediacy exists for methods and means for shrinking and for stretching metal sections to particular shapes. Frequently these shapes are complicated, being formed on compound shapes and curves perhaps with close conformity to a previously fabricated template. Drastic shrinkage and stretching may berequired in localized regions. Now, metal shapes of a variety of sec-tions, and this in widely varied applications, require such treatment. Illustrative among these are sheet, plate, bars, angles and various extruded shapes, as employed in aircraft, boat, train and truck manufacture.

Important need for such manipulation now has developed with the increasing requirement, particularly in the aircraft industry, for structural elements of stronger section. Because of this requirement, the several related industries have turned both to new types of metals of increased strength and those of heavier cross-section. Thus, a forming machine is required displaying both a high degree of flexibility and as well a capability of handling the severe requirements of present-day duty.

Need exists, as may be -seen from the foregoing, for forming and fitting the fabricated structural elements after they have been passed through production die-s and have undergone initial shaping. Need also exists for conveniently accessible and readily operable equipment for initially and completely forming a variety of structural elements, thereby eliminating necessity for production dies with their `attendant high cost. Typical of such uses is the provision of experimental structural shapes, the repair of existing equipment and initial smallquantity production on a pilot basis. Shaping of the elements of the type indicated is largely achieved through the effective correlation of shrinking and stretching steps whereby the metal shapes are brought into required configuration.

Although machine designers have devoted considerable attention in recent years to this general problem, and although many specific problems have been solved with some measure of success, no really complete solution as yet has come to hand. For one reason or another, the existing equipment has fallen short, from a practical standpoint, of fulfilling the intended function. Either known equipment has failed to display the reqon lines 5-5 of uisite flexibility, or hasprovedtoo costly, or has beenv too large and cumbersome, or else has proved capricious 3 and uncertain in operation, has placed too great a demand on skilled labor, or has otherwise proved unsatisfactory in operation.

An important object of my invention, therefore, is to avoid in large measure, or even eliminate in many respects, the several defects, and disadvantages in known equipment heretofore available in industry, and in so doing and at the same time, to provide a simple and compact machine displaying requisite high degree of flexibility, low in cost, both initially and in maintenance, and permitting certain and predictable forming and shaping` of intricate sections to close dimensional tolerances along their lengths.

Andk now, having reference more particularly to that embodiment of my invention which I disclose in the several views of the drawings, it will be seen that I provide a machine body portion 1 maintained on frame 2 in amanner removably fast, as by Hat-head screws 3. The frame Z illustratively is composed of angle members, as shown in Fig. 4. Of course, frame 2 may take any other suitable and convenient configuration. Frame 2 is carried in convenient holders, not shown, by suitable means such as roller feet 4 (see Figs. l, 2 and 4).

Within the body 1 and its appurtenant structure I provide a number of essential assemblies of parts and mechanisms. ThusI provide a tooling assembly which serves to carry they jaw and jaw blocks which actually contact the metal sections undergoing forming. In turn, the tooling assembly is under the control of and is energized through an arm assembly disposed within the body proper. The loosely floating jaws of the tooling assembly are restrained for movement within jaw stops, later to be described. These jaws exert force on localized regions of the work stock through utilization of energy imparted thereto through the arm assembly.

A cam assembly, provided within an extension 1A of the body 1, serves to Vactuate the arm assembly just referred to. This cam assembly includes a pneumatic piston and cylinder. The cam itself, in function comprises an extension of the piston. In transmitting the force generated by the pneumatic cylinder and piston, this cam serves as a piston rod. The cam assembly, including the piston, is controlled by an air -valve assembly disclosed at the right-hand extensions of Figs. 1 and 2. Finally, as disclosed in Figs. l, 3 and 4, a handle assembly serves to control the operation of the air valve assembly.

For convenience, description will be had seriatim of the air valve assembly, the handle assembly the cam assembly, the arm assembly, and finally the tooling assembly. Upon completion of this `detailed description correlation will be had of the various assemblies into a composite and integrated whole.

Accordingly, having especial reference to the disclosure of Fig. l, it will be seen that the air cylinder on body extension 1A carries, at its right-hand end, a cylinder head 1B. Cylinder head 1B is made removably fast to the body extension 1A and to the body 1 by suitable means, such as tie rods 5 (these are four in number, see Figs. 1 and 3). These tie rods are conveniently secured in place by suitable washers 5A and related nuts 5B. It will be seen that,v with tie rods mounted in the body 1 (see Figs. 2 and 5), the body extension 1A is held in compression between body 1 and cylinder head 1B. A suitable seal, such as ring 1C, serves to seal the junction of cylinder head 1B and'v body extension 1A.

The air valve assembly, indicated generally at 6 in Figs. l and 2, is made fast on the exterior of cylinder head 1B in generally central manner, communicating to the interior of cylinder 1A through a central port 1D provided in head 1B. A ring 1E serves to seal the joint between head 1B and the air valve assemblyl 6. The air valve assembly includes a housing 6A which is longitudinally and generally centrally bored at 6B. One end of this bore is closed by a screw cap 6C.

Housing 6A is provided with a compressed-air inlet 6D, preferably threaded for the reception of a pressure air-line, not shown. Also provided is a channel 6E leading from the longitudinal bore and communicating directly into the central port 1D in the cylinder head 1B. Moreover, channel 6E comprises an annular and indented ring provided in the bore 6B and of dimensions slightly greater than that of the bore itself. The purpose of this annular recess will be described at a later point herein. Finally, an exhaust outlet 6F is provided in the housing 6A, communicating with bore 6B, and letting to the atmosphere.

I provide a piston Valve 6G in the bore 6B, capable of reciprocation therein. At its handle-adjacent end this valve terminates, as an extension thereof, in an outwardly projecting pistonA rod 6H. In its reciprocating movement through bore 6B valve 6G is both centered and sealed by suitable and convenient sealing means such as O rings 6I.

At its free end, remote from piston rod 6A, the piston valve 6G is centrally recessed as at 6K. A coiled spring 6L is mounted at one end in the recess 6K of the piston valve 6D and at its opposite end in the socket of the cap screw 6C. So mounted, this spring serves to return the piston valve to its rest position after its work cycle has terminated.

Before discussing the operation of the air valve assembly, it will be helpful first to discuss the details of the handle assembly. Here, a handle guard 1F isstruck, cast, or otherwise conventionally formed on or made fast to the body extension 1A, on an outer side thereof (see Figs. l and 1A). Handle 7, having the general configuration of a bell-crank lever, is pivotally pinned at a point intermediate its length, on dog-ear extensions of handle guard or carrier 1F. In operation, and. having reference to the disclosure of Figs. l and 2, the operator swings the free end 7A of the handle 7 clockwise, through a downward sweep, by finger-energizing and thereby upwardly swinging the hand-operated end 7B of handle 7. Adjustable stop 1G (Fig. l), here shown as a screw, serves to limit the upward and reverse swing (on its return stroke) of the free end 7A of handle 7 during its counterclockwise rotation to its rest position.

To bring the apparatus into operation through the air valve assembly, and assuming pressure air is connected at air inlet 6D, the operator manipulates the handle assembly by compressing the hand-operated end 7B of handle 7. Through piston rod 6H piston valve 6G is thereby moved downwardly (see Figs. 1 and 1A) through the longitudinal bore 6B of the air valve housing 6A and against the resistance of the coiled spring 6L. Because of the annular recess provided by the narrowed shank portion of the piston valve 6G itself, inlet port 6D is thereby connected directly to the transverse channel 6E which leads to the Apiston of the cam assembly. At the same time, the lower end of the piston valve 6G seals the exhaust port 6F of the air valve assembly.

Upon completion of the particular work stroke, the operators release of the handle 7 permits upward movement of the piston valve 6G under the impelling force of the energy stored in the coiled spring 6L. The pistonV valve moves upwardly, breaking the connection between the air inlet 6D and the transverse channel 6E, and establishes, through the aid of the annular ring of enlarged dimensions, the exhaust connection between the cylinder of the cam assembly and the outlet port 6F. Atmospheric conditions are quickly established in the cam assembly cylinder.

The. upward movement of the piston valve 6G is limitedV by the stop 1G. Entrance of pressure air at 6D is effectively barred atthis time until further manipulation ofv handle 7.

Preferably there is employed, as a safety feature, a pressure relief valve 6M. Y

As will be recalled, the cam assembly is energized through the air valve assembly, just discussed. The details of this cam assembly are best described in Figs. `1, 2 and 5. In this cam assembly, the body extension `1A (so-called because it carries the handle assembly) serves as the cylinder for the pneumatic motor, part of the cam assembly, and which is energized through the air Valve assembly, the details of which have been previously described. I mount piston 8A for reciprocation in cylinder 1A. This piston 8A carries packing cup 8B on its face which is made of suitable soft and iiexible material, serving in lieu of piston rings. This cup serves yadequately for its intended purpose, in 'View of the slow rate of movement of the piston 8A. Packing cup 8B has a diameter greater than that of the face of the piston 8A, and consequently of the interior of the cylinder 1A. Thus, the packing cup 8B turns upwardly and outwardly from its lateral extent at its periphery, in a cupped shape, directed away from the main cam element, later to be described. It provides a wiping seal, highly effective in service. The comparatively infrequent and slow movement of the piston 8A enables the packing cup 8B to function satisfactorily as an effective seal against leakage of the pressure air in the cylinder 1A.

A follower plate 8J, having a diameter slightly less thanV that of the piston A, is juxtaposed against the packing cup 8A.

By a threaded extension thereof, I secure the cam spider 8C to the piston 8A and its associated elements. This threaded extension 8D passes through suitable openings which I provide in piston 8A, packing cup 8B and` follower plate 8N. Suitable means such as washer 8E, castellated nut 8F and cotter pin 8G serve to securely hold them together.

For clarity of understanding, it may be noted that body 1 at its terminus adjacent body extension 1A, opens widely thereinto, at 1H. The elongated cam spider 8C has a somewhat truncated configuration, tapering from a wide base at its piston end to a terminal at its pistonremote end `and adjacent the cam followers, to bedescribed. At this end of the cam spider its cross-sectional dimensions are much smaller than -at its piston end. As perhaps best seen from Fig. 5, cam spider 8C has diametrically-opposed wide web portions 8C', 8C. In quadrature with these wide web portions 8C' I provide, on spider 8C, diametrically opposed web portions 8C, 8C", of but shallow depth. A plate-like and fixed cam guide 8K (best shown in IFigs. 2 and 5) serves to guide the cam spider by its wide web portions 8C and to effectively restrain the spider to rectilinear motion. This cam guide 8K is mounted closely and fast against the outer face of the head end of the body 1, in a suitable recess 1' which I provide therein.

The opposed outer faces 8H of cam spider 8C serve as the camming faces for followers 9E. The curved leading-in nose portion of the spider introduced between the lianking cam followers, disposed one on each side of the cam surfaces 8H give quick initial action. Since the cam followers comprise part of the arm assembly, detailed discussion thereof will be reserved for treatment in the disclosure of this latter, next in order for description.

It is the arm assembly 9 which, under the control of the `cam assembly 8, imparts force to the tooling assemb-ly 11. It is this tooling assembly, it m-ay be noted, which includes the working jaw blocks. Thus forces transmitted through piston 8A and its related cam assembly 8 are conducted through thearm assembly 9 to the tooling assembly 11. This arm assembly is housed within the body 1. An internal strut 1J extends across the body 1, adjacent its outer end, to` the left in Fig. 1 and near thetooling assembly. This strut 1I, comparatively massive, serves to carry in pivotal manner forcetransmitting arms, indicated generally at9lA, 9A. These like yarms 9A, 9A are symmetrically disposed, one near each end o-f the strut 1J. Shaped generally as bell-crank levers, they are mounted to rock through restricted angles in direction opposite to each other, in a complemental manner. The pivot points 9B, 9B whereby these arms 9A, 9A mounted on strut 1J are so positionedas to impart important mechanical advantage to the bell-crank levers thus provided. To this end I construct the camadjacent arms 9C, 9C of the bell-crank levers 9A of much greater length than the arms 9D, 9D thereof which are adjacent the tool assembly. The cam-adjacent terminals of the arms 9C, 9C are provided with anti-friction contact means for engaging the cam 8H. These antifriction means are here disclosed as rollers 9E. 9E provided one for each `arm 9C. A coiled spring 9F, sturdy in construction, interconnects arms 9C, 9C shortly rearwardly of their pivot points 9B, 9B. Extended or stretched when the arms 9C, 9C move apart under camming action, this spring 9F retracts when the camming action is discontinued and, with requisite certainty, restores arms 9C, 9C to rest position.

As best seen in Fig. lA, each short arrn 9D, 9D of the two bell-crank levers 9A, 9A, is forked or bifurcated as at 9D' to provide a pair of terminal arms 9D", 9D". Between each pair of such terminal arms there is located a related jaw block 11A, later to be described in greater particularity, and associated pair of jaws 11D.

The cam assembly as heretofore disclosed loosely engages, by its arms 9D, 9D, with the force-transmitting elements of the tooling assembly, later to be described. Each jaw block is pivotally fast between the forked ends of the arms 9D, 9D, but the jaws themselves float loosely and are retained against loss through a cornbination of elements, part of which comprises the jaw stop assembly, next to be described and individual face plates. It is because of this freely floating assembly of the jaws themselves that it is made possible to engage firmly against the work stock which is undergoing formlng.

To diverge for a moment, however, it should be noted (having reference to Fig. l) that I provide upper and lower covers A1, A1 for the body 1, thereby effectively shielding the working parts of the arm assembly. lI'hese two covers (see Fig. 2) are disposed on diametric top' jaws. This jaw stop assembly is indicated generally byV the prefix 10. And each such jaw stop assembly includes a yoke 10A in the form of an elongated, generally U-shaped element (Fig. 7) which is made fast at one end to the body 1 by suitable means such as socketheaded cap screws 10B (see Fig. 4).

The tooling assembly referred to above serves to apply the forces transmitted through the cam assembly, multiplied by the mechanical advantages imparted by the arm assembly, directly to the work stock undergoing forming. The tooling assembly comprises two jaw blocks indicated generally at 11A. These are disposed in pivotal manner as at 11B (see Fig. 2), one being between the birfurcated short arm 9D of each of the bell-crank levers 9A. Thus, as best seen in Figs. 4 and 7, one jaw block 11A is disposed to the right, while the other jawl the pivotally mounted jaw blocks 11A are not flush each jaw block 11A (see Fig. 2) has a taper 11A whichv permits one edge to slide against the strut as arcuate motion is imparted to the jaw blocks through the arms 9D, 9D. It is the rear edges of the two jaw blocks which are in continuous contact with strut 1J as noted in Fig. 7. In this manner, a floating adjustment is permitted. The jaws follow the work as a contour is created by the shrinking or upsetting.

As best shown in Fig. 7, the jaws themselves, indicated at 11D, 11D, etc., are provided in pairs, one pair being disposed in the slotted portion 11C of each jaw block. The jaws are mounted freely as has been stated, and are retained between the jaw stop assemblies on the one hand and the face plates 11H on the other hand. Moreover, the work stock moving between the upper and lower jaws of each pair, serves as a positioning element for these jaws. And the teeth 11E, projecting from each jaw 11D, are loosely intermeshed, that is, the teeth of each pair of jaws intermeshes with those of the other.

These loosely intermeshing teeth serve the function of partially guiding the stock and of restraining the stock from buckling or crimping under the upsetting action of the machine.

Consideration of Fig. 7 discloses that the relationship between each jaw block 11A and its associated pair of jaws 11D is essentially that of a pair of inclined cams. With movement of the levers 9A, 9A the jaw blocks 11A, 11A are rocked inwardly as force is applied to the levers 9A, 9A. Firm and compressive contact is established along the contact lines between the jaw block 11A and the related jaws 11D. And a compressive force is eX- erted almost entirely in a horizontal direction on work engaged between the jaws.

Considering Fig. 7, pressure is first exerted along the transverse axis and the jaw blocks begin to ride along their camming surfaces 11A and grip the work. As the jaw blocks 11A continue to exert an ever-increasing horif.

zontal component of force on the jaws the work is compressed or upset, the gripping force automatically be ing increased in proportion to the resistance to the compression or to the upsetting. The combined effect is to produce nicely localized shrinking of the metal stock undergoing treatment, effectively conforming the metal to the required shape. Any tendency to crimp is effectively prevented by the teeth on the several jaws, these guiding the work stock against warping. In this connection it is noted that the work-contacting surfaces of the jaws are slightly relieved at the teeth end to allow for a thickening of the work stock as a result of the shrinking operation.

Two springs 11P, preferably of the coiled type, are provided between the jaw blocks 11A, 11A (see. Fig. 4). These springs tend to hold the jaw blocks firmly against the face of the strut 1J guiding the block as impelling force is released (see Figs. 1A and 2). Preferably, the springs are disposed adjacent the strut 1I. As a constructional detail, it is to be noted that, as more particularly seen in Fig. 4, and also shown in Fig. 2, the two jaw blocks 11A are provided with front plates 11H applied thereto which guide the jaw 11D. The plates 11H are screwed to the jaw blocks in removably fast manner as by flat-headed machine screws 11]. And as shown in Fig. 4, there are two such screws for each front plate 11H. Inturned at their inner ends at right angles to the plane of the paper as seen in Fig. 7, to provide guide` portions, these inturned edges of plates 11H engage in guide slots 11G provided along the outermost surfaces of the jaws 11D. The relationship of the guide lips of plates 11H with the elongated slots 11G ensures that the jaws 11D are restrained to desired direction of movement relative to the jaw blocks 11A.

It will be seen that slots 11K, similar to the front face slots 11G, are provided onvthe oppositeY faces of the jaws 8 Y t 11D (see Fig. 6). The slots 11G and 11K in the preferred embodiment take the form of milled recesses provided in the faces of the jaws 11D. As shown in Fig. 6, I may provide recesses 11L in the jaw blocks llAfor the reception of cooperating guide pins 11M. These guide pins, loosely received in the recess 1.1L, engage the guide slots 11K. Cooperating with the inturned edge face plates 11H as received in the slots 11G, the guider pins 11M serve to ensure proper coaction between the jaw blocks 11A and the related jaws 11D as relative movement takes place therebetween. The jaw blocks 11A are undercut at 11N, to facilitate proper reception and movement of the related jaws 11D. Where desired, I omit the recesses lll. and guide pins 11M since for most purposes adequate guiding of the jaws is had by the jaw blocks and associated face plates.

When the metal is undergoing stretching rather than shrinking, the arrangement of the cams is just the same as that shown for shrinking. Typically, the paired camming elements 12, 12 engage against and outwardly cam the rollers 13, 13 of related cranks 14, 14 which are pivoted at 15, 15 on the frame of the machine (see Fig. 8). The short arms 14A, 14A of these levers move outwardly, carrying with them related jaw blocks 16, 16 and jaws 17, 17 for each jaw block (see Fig. 8A).

It is apparent from the foregoing discussion that when the metal is locally stretched it tends towards convex curvature as shown in Fig. 9. While if the cam and arm assemblies are replaced and the jaws and jaw blocks reversed, as in the views shown, so that the metal can be shrunk, the metal section tends to assume desired concave curvature. Fig. l0 shows the effect of shrinking one web of a metal bar having T-section. Similarly, Fig. l-l discloses the effect of shrinking an angle iron of L-section.

The operation of the machine in large measure is evident from a review of the foregoing. The metal stock to be formed is presented between the jaws 11D, 11D of the machine and (having regard to Fig. ll.) substantially parallel to the plane of the paper. Where the machine is made sufficiently light to be portable, the machine itself preferably is moved along the metal section while the latter is held stationary. The machine may be slid along a work bench on its roller feet as shown. Or guide rails may be provided, if desired, for facilitating movement of the machine along the work stock. For a machine of the stationary type then the work stock is fed progressively through the jaws of the machine, localized at a fixed station.

When a fresh length of the metal is lfed into the machine, or the machine is moved onto a fresh length, the operator thereupon causes the machine to operate through its work cycle, to stretch, or shrink, as the case may he, one edge of the length of metal. To achieve shrinking, or upsetting, for example, the handle 7B is clamped up against the handle guard 1F. This depresses the piston rod 6H of the piston valve 6G, against the resistance of the spring 6L. Compressed air port 6D communicates with channel 6E and thus, directly to the head chamber of the air cylinder 1A. At the same time, exhaust port 6F is closed. The pistenA is moved to the left in Fig. 2, so that vits associated cam 8H will engage and bodily move, through rolling contact, with the rollers 9E, 9E of bell-crank levers 9A, 9A.

As the cam 8H continues its movement to the left the cam-adjacent arms 9C are swung outwardly so that the arms 9D adjacent the tool assembly are forced together under tremendous leverage. The separation of the arms 9C is resisted by the coiled spring 9F, this latter being thereby tensioned.

The jaw blocks 11A are swung inwardly, in Figs. 2 and 12, toward the longitudinal axis of the machine and immediately act upon the individual faces of the jaws 11D of the machine (see Fig. 7). A component of forcey 9 at right angles to the direction of the movement of the jaw blocks is imparted to the jaws. As a consequence, the jaws are forced strongly against the work piece, engaging the same from both sides thereof. With the strong grip thus established, further movement of the jaw blocks in an inward direction results in local upsetting of the metal undergoing treatment. All this takes place in a matter of but a moment.

It is highly important, for proper operation of the machine, that the jaws and jaw blocks readily adjust both with respect to each other and as well to the work stock and the other elements of the machine. To this end, the jaws themselves, as has been described, are freely floating. These are retained against loss by the coaction of the jaw stop assembly, the face plates, and the spring 11F. Contributing to this freedom of action, the jaw blocks 11A, with camming surfaces 11A', are disposed with center lines approximately one-eighth of an inch in front of the center line of the bell-crank levers 9A.

When the spot-shrinking or spot-upsetting has been carried to suflicient extent, the operator releases the handle 7B. Spring 6L of the air valve assembly then kicks the piston valve 6G to its rest position, until the arm 7A of the handle 7 abuts the adjustable stop 1G. Pressure port 6D is thereby closed while channel 6E is opened through port 6F, to the atmosphere. Springs 9F retract, pulling together the arms 9C, 9C of the arm assembly, an action which is aided somewhat by the relaxing of the coiled and compressed spring 11G between the jaw blocks 11A. The anti-friction rollers 9E roll along the cam surface 8H and force the piston 8A to the right-most or rest position of the machine (see Fig. 2) against only atmospheric pressure. The spring 11F tends to free the jaws and jaw blocks from the work stock. The work stock is then moved a short distance relative to the machine or the machine is moved relative to the stock, and the process is repeated.

Variation in applied forces, to adjust to desired degree of upsetting, for variation of metal hardness and variation in metal gauge, can be provided for by the variation of applied air pressure or by changing the dimensions of the jaw blocks and jaws, or by a combination thereof.

Typically, I find that with but moderate weight of the machine, say 35 pounds and with maximum air pressure of 125 pounds per square inch, I can effectively shrink or stretch, as the case may be, 24 ST Alloy metal having a thickness of /32 inch with Width of 11/2 inch; 24 SO Alloy with thickness of 'e716 inch With 2 inch width, stainless steel of 5/32 inch thickness against the 11A inch width, and titanium displaying 1/16 inch thickness with width of one inch.

While the machine has been shown as being pneumatic in nature, it is also entirely possible to adapt it for operation by hydraulic pressure. Or, where desired, it may be operated from forces either entirely mechanical or partly electrical in nature. And in such instance, the energizing force is transmitted through a mechanical linkage which greatly multiplies the effective operating force. Powerful thrust is imparted to the working jaws. The machine readily permits shrinking or stretching metal products in a localized area. This is true either of new products undergoing initial treatment, or in repair of damaged products. Nice tailoring and fitting of al1 types and shapes of sheet metal parts can be achieved. Utility is displayed in entirely forming many products required in aircraft fabrication, for example: illustratively framing, bulkhead members, cap strips, rolled or extruded angles, Ts, channels, fairing sheets, etc.

All the foregoing, as Well as many other highly practical advantages, are typical of my invention.

It becomes apparent that once the broad aspects of my invention are disclosed many embodiments thereof will suggest themselves to those skilled in the art, and as well, many modifications of the present embodiment will present themselves, all falling within the spirit of my disA closure. Accordingly, I intend the foregoing description to be considered as purely illustrative and not by way of limitation.

I claim as my invention:

1. A machine for forming a metal section comprising a frame having an elongated guide surface; a pair of arms pivoted intermediate their length to said frame, one adjacent one end of the guide surface and the other adjacent the other end and extending transversely thereof; power means connected to one end of said pair of arms for application of power, the other end of each of said arms being bifurcated; two jaw blocks, one being located in each bifurcation and pivoted thereto, said jaw blocks being spaced from each other in one position of said pivoted arms and provided with Vlateral openings therein located along a plane parallel to said guide surface, and said blocks being in slidable relation to said guide surface; and two pairs of related jaws, one pair being received in said opening of each said jaw block, said jaw blocks including means creating a camming action between the respective jaws and blocks as said jaws grip a metal section and said -blocks are moved toward each other to tighten the grip on the metal section under the action of said power means.

2. A machine for forming a metal section comprising a frame including a strut portion having an elongated guide surface; a pair of arms pivoted intermediate their length to the strut portion of said frame, one adjacent one end of the guide surface and the other adjacent the other end and each extending transversely thereof; power means connected to one end of said pair of arms for application of power, the other end of each of said arms being bifurcated; two jaw blocks, one being located in each bifurcation and pivoted thereto, said jaw blocks being spaced from each other in one position of said pivoted arms and provided with lateral openings therein located along a plane parallel to said guide surface; two pairs of related jaws, one pair being received in said opening of each said jaw block, said jaw blocks including means creating a camming action between the respective jaws and blocks as said jaws grip a metal section and said blocks are moved toward each other to tighten the grip on the metal section under the action of said power means; and spring means urging said jaw blocks about their pivots to urge their engagement with said guide surface.

3. A machine for shrinking a metal section comprising a frame including a strut portion having an elongated flat guide surface; a pair of arms pivoted intermediate their length to the strut portion of said frame, one adjacent one end of the guide surface and the other adjacent the other end and each extending transversely thereof; power means connected to one end of said pair of arms for application of power, the other end of each of said arms being bifurcated; two tapered jaw blocks, one being located in each bifurcation and pivoted thereto, said jaw blocks being spaced from each other in one position of said pivoted arms and provided with lateral openings therein located along a plane parallel to said guide surface, and said jaw blocks being substantially inline contact with said guide surface and in slidable relation therewith and adapted to rock about said line contact of jaw blocks and guide surface; two pairs of related jaws, one pair being received in said opening of each said jaw block, said jaw blocks including means creating a camming action between the respective jaws and blocks as said jaws grip a metal section and Said blocks are moved toward each other to tighten the grip on the metal section under the action of said power means; spring means between said jaw blocks at areas adjacent said lines of contact between jaw blocks and guide surface to urge said blocks about their pivots into engagement with said guide surface and rocking on the same at said lines of contact; and spring means between opposed jaws of each pair to free the jaws from the metal section following shrinking action.

References Ced in the le of this patent UNITED STATES PATENTS Enfeldt May 13, 1902 Schneider Sept. 28, 1920 Knott Mar. 1, 1927 Hanna Mar. 26, 1929 Junkers June 3, 1930 Keith Apr. 23, 1935 Shai Aug. 20, 19,35

FOREIGN PATENTS Y France Aug. 3, 1942

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