US2887142A - Rib forming die assembly - Google Patents

Description

May 19, 1959 F. J. EMMONS RIB FORMING D IE ASSEMBLY 2' Sheets-Sheet 1 Filed Aug. 25, 1957 'INVENTOJQ.

May 19, 1959- F. J. EMMONS w 2,887,142

RIB FORMING DIE ASSEMBLY Filed Aug. 23, 1957 5 Sheets-Sheet s INVEN TOR.

United States Patent REFORMING DIE ASSEMBLY Fred J. Emmons, Lebanon, Ind assignor, to Stewart- Warner Corporation, Chicago, 111., a corporation of Virginia Application August 23, 1957, Serial No. 679,948

1. Claim. (Cl. 153-34) The present invention relates to a die assembly for forming a rib in a sheet, metal element, such as the heat exchanger wrapper in a vehicle heater.

One. object of the invention is to. provide, for use in a, suitable.- press brake or the like, an improved die assembly which completely shapes a medial portion of a sheet metal, blank into a protruding rib upon, actuation of the die assembly by a single linear stroke of a die. actuator and completely releases the part in which the ribs is formed upon retraction of the die actuator.

Another object is to provide a dieyassernbly of. the character recited in the previous, object which shapes a hat sheet metal element by bending, alone ,tov forrn an elongated rib projecting perpendicularly. from a. medialv portion ofthe element, thus avoiding,drawmgorstretching of the material, forming the rib.

A further object of the invention is to provide an im-f proved die assembly which will operate dependably; in

the manner set forth in the above objects, to shape a medial portion of a sheet metal element intoaIprotruding rib having an exact, predetermined size.

Another object is to provide an, improved die assembly in which the functional capabilities mentioned in the previous objects are achieved by a unique construction Well suited for economicm manufacture and having a.

long service life during which linear operatingforces are transformed into a powerful rib forming action with great accuracy and dependability.

Other objects and advantages will become apparent from the following description of the exemplary form of the invention shown in the drawings, in which:

Figure 1 is a fragmentary horizontal sectional view taken along the line 1-1 of Fig. 2, and showing structure at one end of a die assembly embodying the invention;

Fig. 2 is an end view of the die assembly taken with reference to the right hand end of Fig. l. and showing the positional relationship of the assembly to coacting elements of a press brake;

Fig. 3 is.a side view of the end portion: of the assembly corresponding to that shown in Fig. 1;

Fig. 4 is a vertical sectional view taken along, the line 4-4 of Fig. 1;

Fig. 5 is a vertical sectional view taken along the line 5-5of Fig. 1;

Fig. 6 is a schematic end' view of the assembly illustrating the beginning of the firstphase of the rib forming action;

Fig. 7 is a schematic end view similar to, Fig 6 but showing the completion of the first phase and the begin ning of the second phase of the rib forming; action;

Fig. 8 is an end viewsimilar to Fig. 7 but showing the completion of the second phase of the rib forming action;

Fig. 9 is a large scale plan view of a sheet metal element in which a medial rib has been formed by the, die assembly of Figs. lto 8; and

Fig. 10 is a fragmentary sectional view. taken. along the line 1ll10 of Fig. 9.

The die assembly 18 forming the illustrated embo-di' ment of the invention comprises a fiat rectangular base 20 of substantial thickness, Figs. 1 to 5, which is adapted to rest horizontally on the work support platform or bed 22 of a conventional press brake or similar machine. In this position, the base 20 underlies a vertically movable ram or slide 24 of the machine, which serves as an actuator for the die assembly.

Illustration and description of the die assembly 18 is simplified by the fact that it is symmetrical with respect to both the longitudinal and transverse center lines of the bed 2%. Hence, only one end portion of the die assembly 18 is illustrated in the drawings. end portion is a mirror image of that shown. The intermediate portion of, the assembly, which can be of any desired length, is a continuation of, the intermediate structure illustrated.

The base 20 provides a common anchor for a series of cam or support plates 26 rigidly mounted on the base in side-by-side, parallel relation to each other. As shown in Figs. 3 and 4, each cam plate 26 is placed'on edge on the base 20 and extends transversely across the, base over the major portion of its full Width. Three machine screws 28, countersunk into the lower side of the base 29, are threaded upwardly into the lower marginal edge of each cam plate to hold it rigidly in place.

The plates 26 are spaced from each other longitudinally with respect to the. base 2-0 to provide space between adjacent plates for accommodation of yieldable die support structure to bedescribed presently. The exemplary die assembly 18 has seventeen cam plates, only three of which are fully illustrated, Figs. 1, 3 and 4. All the cam plates have a very substantial thickness to provide great strength and rigidity; Moreover, the cam plate at each end of the series has an even greater thickness, Fig. 3, to rigidly withstand the reaction of attached guide. structure to be described presently.

The upper central portion of each, cam plate 26 is cut' away toform a V-shaped notch 30, Fig. 4, opening upwardly away from the base 20 and defining an included angle of approximately ninety degrees, which is symmetrical to a plane perpendicular to the base 20 and extending down the longitudinal centerline. of the base. Thus, the notches 30 in the several cam plates 26 register with each other as viewed from one end of the base 20.

Opposite sides of the notch, 30 in each plate 26 are milled awayto' form two inclined seats 32, Fig. 4, for two elongated bearing plates 34. Each bearing plate 34 is firmly secured to its seat 32 by two machine screws 36- countersunk into the bearing and threadedinto the underlying support plate structure. The upper side of each bearing plate 34 defines a straight cam surface 38 inclined at an angle of approximately forty-five degrees away from a vertical plane extending centrally through all the notches 30.

As will presently appear, the inclined cam surfaces 38 on opposite sides of the notches 3d are used to apply a converging camming action to a, pair of elongated anvil dies 40 formed substantially as mirror images of each other and extending longitudinally through the die assembly 18.

Disposed in mutually opposing relation to each other across the previously mentioned vertical plane of symmetry of the notches 30, the two anvil dies 4d extend perpendicularly across all, the cam plates 26 in immediately overlying relation to the bearing plates 34 on the respective sides of the notches 30.

The portion, of each anvil die member 46 immediately opposing the adjacent, underlying bearing plates 34 is shaped to form a flat bearing surface 42 extending; the

full length of the die member to theside of the die member opposite from the opposing die member 40, as shown The other sesame in Fig. 4. The bearing surface 42 thus formed on each anvil die member 40 has a slope in relation to the base 20 conforming to the slope relative to the same base of the opposing cam surfaces 38 whereby the cam surfaces 38 of the opposing portions of the bearing surface 42 have fiat contact with each other.

The two anvil die members are yieldably urged away from each other by a pair of coiled compression springs 44 located at opposite ends of the die assembly 18 and mounted horizontally between the adjacent ends of the anvil die members. As shown in Fig. 4, opposite ends of each spring 44 extend into opposing spring seats 46 recessed into the respective anvil die members 40.

Both anvil die members 40 are strongly supported against downward movement toward the base 20 by powerful vertical spring forces distributed along the entire length of the die members. For this purpose a series of horizontal support rails 48 are placed under the two anvil die members in alternate spaced relationship to the cam plates 26 (see Figs. 1, 3 and Opposite ends of each support rail 48 are substantially conterminous with corresponding ends of the adjacent cam plates 26. The upper side of each rail 48 forms a straight horizontal skid surface 50 which engages a narrow horizontal support surface 52 formed on the bottom of each anvil die 40. The anvil die surface 52 extends the entire length of the die between the lower edge of the inclined bearing surface 42 on the die and a longitudinal vertical surface 54 extending from the bottom to the top of the die in opposing relation to the other anvil die, Fig. 5.

Each support rail 48 is strongly urged upwardly to the starting position shown in Fig. 5 by a series of seven coiled compression springs 56 evenly spaced along the rail and placed vertically between the support rail and an underlying sill 58 disposed between the two adjacent cam plates 26. A series of horizontally elongated support sills 58 are supported on the base 20 in alternate spaced relation to the plates 26 and individually anchored to the base ,by two screws 60. Opposite ends of the springs 56 extend into spring seats 62 and 64 recessed respectively into the overlying die support rail 48 and into theunderlying spring support sill 58.

Upward movement of the several support rails 48 is stopped at a predetermined level by three vertical restraining bolts 66 connected between each support rail in its underlying support sill 58. As shown in Fig. 5, the three restraining bolts 66 for each support rail 48 pass through the two end springs and the central spring of the series supporting the rail. Clearance for downward movement of the restraining bolts 66 and bolt heads 68 on the lower ends of these bolts is provided by counterbores 70 in the sills 58 and underlying bores 72 in the base 20.

The two anvil die members 40 are guided for movement toward and away from each other and constrained against rotation with respect to each other by guide means which provides for movement of the two anvil die members in unison toward and away from the base 20 while at the same time effectively constraining both anvil die members against movement relative to each other 'in a direction perpendicular to the base 20. Structurally, the guide means comprises a guide lug 74 (Figs. 2 and 3) integrally formed on each end of each anvil die 40 and protruding longitudinally beyond the end of the die in parallel relation to the base 20. Each lug 74 is rectangular in configuration as viewed from one end, Fig. 2, and has flat upper and lower guide surfaces 76, 78 which are parallel to the base 20.

The two guide lugs 74 at each end of the die assembly 18 fit respectively into two horizontally elongated slots 80 formed in a vertical guide plate 82 slidably mounted on the vertical, outer end surface of the adjacent cam plate 26. The guide plate slots 80 have a vertical width just sufficient to accommodate the respective guide lugs 74 and a length parallel to the base 20 which allows the desired movement of the anvil dies 40 toward and away from each other. Thus the movement of each anvil die 40 with respect to the opposing anvil die 40 is restricted to a linear path. Each guide plate 82 is guided for vertical movement toward and away from the base 20 by two screws 84 extending through a pair of vertical slots 86 in the guide plate into the adjacent cam plate 26.

The upper side of each anvil die 40 is shaped to form a substantially flat work or blank engaging surface 88, Fig. 4, extending the full length of the anvil die, Fig. 3, in generally parallel relation to the base 20 and intersecting along one longitudinal edge the substantially vertical die surface 54 facing the other anvil die 40. While the blank engaging surfaces 88 are substantially coplanar, they may slope slightly in relation to each other, as shown, to conform to the curvature of a curving sheet metal element 90 (Figs. 2, 4, and 5) in which a rib is to be formed by the die assembly.

To facilitate the formation of ribs in closely spaced relation to each other on the sheet metal element 90, which is to be fashioned into a heat exchanger wrapper, for example, a deep longitudinal relief 92, Fig. 4, is cut into the upper side of each anvil die 40 on the side of the die opposite the other anvil die.

The upwardly facing die surfaces 88 on the anvil dies 40 are opposed by similarly shaped but wider die surfaces 94 on the underside of an overlying ram die 96 extending the full length of the anvil dies. The ram die 96 is supported and actuated by the vertically movable ram 24 previously mentioned.

A narrow creasing blade 98 is fixed to the underside of the ram die 96 to extend longitudinally along the ram die and depend vertically downward between the upper ends of the two anvil dies 40 in transversely centered relationship to the latter dies. In the present instance the creasing blade 98 terminates longitudinally somewhat short of the adjacent longitudinal end of the die assembly, see Fig. 1. The longitudinal portion of the vertical surface 54 of each anvil die 40 which is aligned with the creasing blade 98 is offset away from the opposing anvil die in relation to the portion of the vertical die surface 54 which extends longitudinally beyond the creasing blade 98.

Each operating cycle of the die assembly 18 thus formed begins with the ram die 96 retracted to an elevated position, Figs. 3 and 6, in which the lower edge of the creasing blade 98 is spaced a short distance above the level of the anvil die surfaces 88. At this time the two anvil die members 40 are supported in their uppermost positions by the spring supported slide rails 48 and separated a predetermined maximum amount by the end springs 44.

The sheet metal blank or element 90 in which a rib is to be formed is laid across the blank engaging surfaces 88 of both anvil dies 40 to expand the space between these dies as shown in Fig. 6.

Incipient downward movement of the ram die 96 engages the creasing blade 98 with the longitudinal center of the portion of the blank 90 spanning the space between the anvil dies. This begins the first phase of the rib forming action during which downward movement of the ram die 98 forms a crease 100 in the blank 90 following and extending beyond the lower edge of the creasing blade 98. During this creasing phase of the rib forming action, which occurs while the ram die 96 is moving downwardly from the position shown in Fig. 6 to the position shown in Fig. 7, both anvil dies 40 are held in their original starting position by the support springs 56 and the spreading springs 44. Thus the total residual stress on all the support springs 56 is sufiicient to offset the downward force which must be applied through the blade 98 to effect the desired creasing action.

Moreover, the total residual stress in the support springs 56 is also sufficient to provide a very substantial resistance to downward movement of the anvil dies 40 after the ram die surfaces 94 have been brought fully into engagement with the portions of the sheet metal blank 90 overlying the anvil die surfaces 88. The result is to force the blank 90 down into fiat surface engagement with the anvil die surfaces 88 as shown in Fig. 7 to complete the creasing phase of the rib forming action. It will be observed with reference to Fig. 7 that clamping the blank 90 between the lower die surfaces 88 and the overlying die surfaces 94 in this manner forms incipient bends 102 in the blank 90 at the junctures of the two die surfaces 88 with the adjacent vertical surfaces 54 of the respective anvil dies.

It will be appreciated that the crease 100 and both of the incipient bends 102, Fig. 7, are formed in the sheet metal element 90 by simple bending actions applied to the blank in a manner which effectively avoids stretching or drawing of its structure.

Immediately upon clamping the element 90 between the opposed die surfaces 88, 94, downward force is transmitted through the sheet metal element to force the anvil dies 40 downwardly against the springs 56. It is noteworthy that the reaction of these support springs is transmitted upwardly to the anvil dies 40 through the lower anvil die surfaces 52 which directly underlie the respective die surfaces 88 through which the downward actuating force is applied from the overlying ram die 96. The spring reaction thus transmitted back to the anvil die surfaces 88 is suflicient to prevent slippage between these anvil die surfaces and the adjacent portions of the blank 90 as the two anvil dies 40 are moved downwardly in unison by continued downward movement of the ram die 96.

As this downward movement progresses, the two anvil dies 40 are moved horizontally toward each other by the camming action of the inclined bearing surfaces 38 on the opposing anvil die bearing surfaces 42. During movement of the ram die 96 downwardly from the position shown in Fig. 7 to its lowermost position shown in Fig. 8, each anvil die 40 and the portion of the blank 90 immediately overlying the surface 88 of the anvil die is moved with respect to the ram die 96 straight toward the creasing blade 98. The effect of this is to bend the crease 100 into a 180 turn (also denoted by the nueral 100) and to increase the angle of each bend 102 to 90. Movement of the two bends 102 toward each other displaces the central bend or turn 100 down below the lower edge of the creasing blade 98 as shown in Fig. 8.

Thus, the rib forming action is completed by simple bending actions which generally avoid stretching or drawing the material. In this manner a longitudinal rib 104 is completely formed in the sheet metal element 90, Figs. 8, 9 and 10, by a single downward stroke of the ram die 96. It will be noted with reference to Fig. 9 that the portion of the I'll) 104 formed in the end section of die assembly 18 which extends longitudinally beyond the creasing blade 98 is narrower than the portion of the rib formed in longitudinal alignment with the blade 98.

Retraction of the ram die 96 fully releases the sheet metal element 90 in which the rib 104 is formed. The spring-biased skid rails 48 and the separating springs 44 return the anvil dies 40 to their starting positions, thus releasing the completed rib 104, which springs apart sufliciently to relax any pressure previously applied to the creasing blade 98.

It is noteworthy that the size and depth of the rib 104 thus formed are predetermined with a high order of accuracy by the capacity of the die assembly to maintain the original starting position of the two anvil dies 40 until the sheet metal element is tightly clamped against both die surfaces 88. The distance at which the two anvil dies 40 are exactly spaced from each other in the starting position, together with the depth of the creasing blade 98, precisely measure the width of the sheet metal material which is shaped into the final rib thus assuring the desired dimensions in the completed rib.

While I have shown a preferred embodiment of my invention, it will be apparent that variations and modifications thereof may be made without departing from the underlying principles and scope of the invention. I therefore desire, by the following claim, to include such variations and modifications by which my invention may be practiced through the use of substantially the same or equivalent means.

A rib forming die assembly comprising, in combination, a base, a linear series of cam plates mounted on said base and projecting therefrom in parallel spaced relation to each other, a pair of elongated anvil dies disposed in side-by-side relation to each other and extending longitudinally along said linear series of cam plates in perpendicular crossing relation to the projecting ends of the cam plates, the projecting ends of the cam plates defining deep V-shaped notches opening away from said base and registering with each other as viewed from one end of said linear series of plates, means on each cam plate defining two cam surfaces bounding opposite sides of the notch defined in the cam plate and engaging said respective anvil dies when the latter are in said starting positions thereof, said cam surfaces bounding opposite sides of each notch extending toward said base in converging relation to each other to constrain to mutually converging paths movement of said respective anvil dies from said starting positions thereof toward said base, a series of movable slide elements disposed between said cam plates in alternate spaced relation there to and individually engaging the base sides of both anvil dies, a plurality of compression springs mounted between said base and each slide element strongly to resist movement toward said base of the slide element and said anvil dies in engagement therewith, and means coacting with said slide element to preclude movement of the latter away from said base beyond limits defined by said starting positions of said anvil dies.

References Cited in the file of this patent UNITED STATES PATENTS 1,433,879 Fancher Oct. 31, 1922 2,021,118 Tinkham Nov. 12, 1935 2,044,322 Oliver June 16, 1936 2,144,231 Schwarz Ian. 17, 1939 2,544,447 Dodds Mar. 6, 1951

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