US2332435A - Corrugating die - Google Patents

Description

Oct. 19, 1943. F. P. IBUCKLEIN 2,332,435

CORRUGA'IING DIE Filed Au 27, 1940' 2 She'ets-Sheet 1 .Z'NVENTOR (LU- M- Oct. 19, 1943. F. P. BUCKLEIN CORRUGATING DIE Filed Aug. 27, 1940 2 Sheets-Sheet 2 INVENTOR Patented Oct. 19, 1-943 I Frank'Pf'Itucklein, Los Angeles, Calif., assignor to Lockheed Aircraft Corporation, Burbank,

Calif "A'p'mmat on Augu t. 27, 1:540; s ial No; 354,343

'7 Claims. (ar as-icy I This invention relates tofim proved forming dies; I

for use on simple orsingle acting power presses such as for example the press, brakes used for sheet metal. To this end I have provided a compound, progressive die set to develop the final shape desired in the material being worked upon.

The die set chosen for illustrative purposesv is adapted to form a series of non-sinusoidal ,corrugations in sheet material, the finished inaterial being used as reinforcement beneath the stressed skin covering of airplane wings. forming such reinforcing material the blank sheet has heretofore been supplied with locatingholes or notches fitting over pins on a mandrel, over which a properly formed member is forced to produce the desired shape. In so producing cor-g. rugations the locating holes ,or notches are a source of trouble and delay, andthe inherent springback of high strength material has also been a problem, ince bending sheet material,

without stretching or drawing beyond its yield I cessive operations in forming a single corrugation [4 in a sheet metal blank I5 it will be con- ,venient to describe the separate set-upsfor the point, results in unpredictable springback, which varies with the thickness, temper and elasticity of the material. In order to accurately form' the corrugations without appreciable stretch, and

consequent thinning of the material,I provide,

a multiple station die set wherein an initial overbend is produced in the material by a semi-folding operation; as distinguished from a drawing operation; in order to allow for subsequent springback upon release from the die, and subsequently utilize a spring pressed plunger to, act

I Figure II is a fragmentary longitudinal section on the lineII-JI of Figure I showing the supporting springs and guide pins. I Figure III i a section of the lines III III' of Figure II, in the; plane of one of the spring locations. H 1 i Figures IV to-VII, inclusive, correspond't'othe stagesin the operation of the .dies.

Asshown; i The dies of this invention are intended to '1be used in conventional single acting power presses 1. line IV--IV in Figure II, and show successive or sheet metal press brakes, sothatto simplify the disclosure no further reference will be made to the press or brake, .A lower or female die is built up one baseblock Hlhaving af'locatingkey H for aligning it in the'press bed; ,and;a cooperating maledie has a base block II with a hooked key 13 for fastening the 's arne]to' the movable head or ramof the press. I

Since the die,; as disclosed, performs two suctwo steps. To thisenithe initial forminglmechanism will be first described. The female base block! yieldingly supports a die block lfi by means of springs ll, guide pins [8 serving to as 'a hold-down While another corrugation is ,be-

, ing formed by the semi-folding operation.

It is accordingly anobject of this invention to provide'an improved die for sequentially forming a series of corrugations in sheet material, .it

being evident that while such corrugations will normally be made parallelto each other, in air: plane wing construction it may be. advantageous to taper thev corrugations and/or slightly converge. them for use in Wings of tapered profile.

It is a further object of this invention to provide an improved die for use on simple presses or brakes that will accurately and reproduceably form the desired profile without stretching and.

thinning the material as a result of drawing op erations. I J Other and further important objects "of this invention will be apparent from the disclosures in thespecification and the accompanying drawings. i

This invention in its preferred formis illustrated in the drawings and hereinafter more fully described. 1 4

In the drawings: I

Figure I is a fragmentary perspective view of adie set embodying the features of thisinvention, the length of the dies being'limited only by the size of the press or brake with which it is to be used.

limit the movement of the block I6, The block |6 is provided with pivots l 9for a lever 20 whichv is swung upwardly by theclosingordownward movement of theblock 16 relative to the base 0. The block 1 i3 carries a suitably, shaped member 2| which defines the corner to be produced on the sheet metal blank, and the lever 2t supports a similar me mber 22. which defines. the ,othercorner of the corrugation l4; the upward swing of the lever 20 serving to fold the sheet material about a former 23-1Whi0h, is pivotally suspended frornthe male base block l2. Both' corners 2| and 22 and theformer 23 are of less radius than the final shape of the corrugation,

and allow for springback. The corner member 22 is supported and backed by adjustable shims 24 which control the degree of overbend given the sheet. Also,"removal of the supporting shim will allow an offset for overlapping the edges of adjacent sheets of corrugated material. The former 23 is preferably permitted a slight lateral motion, as indicated by the dotted outline infigure VI, as it is subjectto side pressurefrointhe sheet material during the closing movement of the die, both before and after the lever 20 is shifted to fold the material into the position of Figure v11. This also helps to feed the sheet material into" the desired shape, rather than to stretch it duringthe forming operation] When the dies are fully closed, with the lever Ml-forced ,upward, the corner memlber 22 on the leveroforces the sheet material at an angle against a land on the upper'o'r male die. It will be noted that the corner piece 2|.

the movable side wall formed by the lever 20 and the corner member 22 serves to wrap the sheet material about. .the plunger, bending .it through more than a half circle, as indicated in Figure VII. The extent of overbending required, 5 may vary with different materials and tempers but is so proportioned that the natural spring-- back or opening movement will result in the dea; sired final form. V i 0 The hold-down mechanism comprises a plunger 26 formed to cooperate with a complementary 7 channel 21 in the female die I6, the plunger being carried by a plate 28 movable relative to the male base block and backed by springs 29, which springs are of less number and strength than the springs inthe lower dieso'that theplunger 26 wil1 be seated and compressing the previously formed corrugation before the female die is compressed. The plunger 26 is removable in case itis desired to manually control the positioning of the material to produce parallel or converging spacing in the material between or adjacent one or more corrugations, in which case the material would be fed from the right. At the same time as: the plunger is seated in the female die 16, the' plate 28 bears againstlands 30 on either side'of the channel 21 so that the plate and plunger serve as hold-downs while the first describedlparts of "the dies are forming another corrugation: The action is a clamping one, as 30 distinguished from a drawing operation wherein the material feeds under the hold-down. The plate 28 and-plunger 26 have guide pins 3! and 32 slideable in suitable recesses in the male base-i: block l2, the guide pins -32 having heads limiting 35 the stroke of the plate and plunger.

Figures IV to VII inclusive illustrate successive stages in the operation of the die, Figure IV illustrating theinitial position with a Dre- 1f? formed corrugation 14 in the sheet metal blank l5' positioned inthe channel 21 to be engaged by the plunger 26 as indicated in Figure V, with theplate 28 pressing the material against the lands 30 on either side of the-channel. Duringqq; continued downward movement of the upper or male die the springs 29 back of the plate 28 are compressed and serve to hold the sheetmaterial while the former 23 bends the material over This bending 'operationct produces reversible side thrust on the former while the sheet is being deformed sufficiently to wrap about the form. During this operation the. material feeds over the corner 22 until the dies bottom andforce the lever 20 upwardly and inwardly to appreciably overbend the material as indicated in Figure -VII. i V a While the die set chosen for illustrative purposes is particularly adapted to form corrugated reinforcing sheets for aircraft purposes, it is evident that my invention is adapted to a wide field of usefulness, particularly in handling impressions in materials that are ordinarily hard to handle in bending operations where it is not desired to stretchthe material.

Having thus described my invention and the 5 present preferred embodiments thereof, I desire to emphasize the fact that many modifications may be resorted to in a manner limited only by a just interpretation of the following claims} I claim;

1. In a corrugating mechanism of the classdescribed, a base block and an, associated female die, a bending member pivoted to said female die and having an outwardly extending portion, and an arcuate upwardly extending portion, said first named portion being engaged with the base blOCktO provide a fulcrum contact, an opposed base block and. an associated male die, means to yieldably support said dies on the blocks, a second bending member pivotally supported on said opposed base block in positions to cooperate re spectivelywith the female die and the first named bending. member, whereby the male die will engage. andrnove the female die towards its base block and simultaneously cause the female bending member to rotate around its fulcrum contact towards the female die, to engage a Work piece.

2. Ina mechanism as set forth in claim I, wherein the yieldable means that support the dies on; the 'respective base Pblocks comprise springs acting to force each die away from its respectivebase blockf 9 In a mechanism "as set forth in claim 1, wherein the base block thatsupports the bending member is formed to provide a land portion adjacent-the bending member, said land portion being operative to engage and bend the material worked on adjacent the bending member.

4;]111 a mechanism as set forth in claim 1,

wherein the terminal free end of the second named bending member is provided with an adjustabletip portion and means 'for adjusting said tip portion relative to. the body portion of the said bending member to controlthe degree of bend made in a sheet worked on';

5. In acorruga'ting mechanism of the class described, in combination, a pair of base blocks,

male and female forming members supported res'pectively on said base blocks, cushioning means "associated with each block and being yieldable for movement of each forming member towards itsrespec'tive base "block, a bending member pivota'lly supported on the block which carries the male forming' memb'er, a second bending member fulcrumedon the female forming member and extended to contact the adjacent base block,

and meanson the supporting base block to engage the second named bending member to more the latter member towards the female forming member in response to relative movement of said last 'named member onits base blo'ck'to form a corrugation in the Work piece;

6. In a mechanisin of the class described in combination, a base block, a female holding die 'swing towardstheffemale holding dieya second .base blockfa male holding die andaa male bend- -ing die carriedby said second base blo'cl; and

positioned thereon to respectively engage'the female'holding' die and the female .bendingdie.

$7. In a device asset forth in claim fi, spring means positioned between the malekholding die and its supporting base block, said spring means being weaker than the spring means between the female die'member and its supporting block whereby, when the male holding die is moved to engage a work piece between the femaleholdingdie' and the male holding die, saidmale holding diewill be'moved axljacent'its supporting block prior to any movement of the female holding die.

. FRANK P. BUCKLEIN

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