US2352265A - Method of producing cup washers - Google Patents

Description

June 27, 1944. K L ETAL 2,352,265

METHOD OF PRODUCING-CUP-WASHERS I Filed Au 21. 1942 2 Sheets-Sheet 1 I W v ww 7,

I N V EN TORS.

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Jam; 27, 1944. F. KAPPLE El'AL 2,352,265

METHOD OF PRODUCING CUP-WASHERS Filed Aug. 21, 1942 2 SheetsSheet 2 INVENTORS.

7Q 3 fiQnbIqp /vle; 1510? zwmm 75 i 1422a, "0 5% Patented June 27, 1944 UNITED I METHOD or PRODUCING cUP WASHERS Frank Kapple and Joseph F. Sikora,

assignors to Dunbar-lfapple & Company, cago, 111., a partnership Chicago, Ill., Chi...

Application August 21, 1942, Serial No. 455,670

4 Claims. (01. 86)

This invention relates to the production of cupwashers, and has to do with an improved method of and means for producing metal cup-washers.

Metal cup-washers are used extensively in the airplane industry for taking up any looseness or play in taper pins, and for many other purposes where it is important to assure that parts will be held tightly together in a manner effectively guarding against looseness or play between them. In use, cup-washers must be capable of withstanding pressure of considerable magnitude and,

for that reason, shouldbe formed of steel of proper characteristics and must be of considerable wall thickness. Due to these requirements,

it is the present practice to produce cup-washers v on screw machines from bar stock. That is oblectionable in that it necessitates waste of considerable metal and the use of screw machines which, if not necessary for producing cup-washers, could be used to advantage for other purposes.

The requirements of cup-washers with respect to accuracy in shape and dimensions are quite strict, particularly in the airplane industry, and are very exacting as to cup-washers intended for use in military airplanes. It is not practicable to produce metal cup-washers from sheet stock by the use of dies in presses, by the usual procedure. That has been attempted, but it has been found that, under the present practice, cup-washers formed from sheet stock are inaccurate and are characterized by having a circumferential fold or ring formed therein, rendering them unfit for their intended use, and the stresses involved are such that objectionably high die breakage is incurred.

Our invention is directed primarily to the avoidance of the above noted objections to the present practice in die forming sheet metal of considerable thickness, and thereby rendering it practicable to produce metal cup-washers from sheet stock, by the use of dies in ordinary punch presses. It involves the method of cutting the blanks and forming themaccurately to final size and shape, and the means for practicing that method. More specifically, the method of our invention comprises cutting the blanks and forming them to bell shape of greater height than the desired washers, and then reducing the height of the belled blanks by subjecting them to axial forming pressure between opposed flat surfaces While confined between concentric forming surfaces corresponding to the circumferential surfaces of the desired washers, whereby the metal of the blanks is displaced and redistributed so as to fill the spaces between the concentric surfaces and the ends of the blanks are flattened, the belled blanks being thus formed accurately to the shape and size of the desired washers. The means for, practicing our invention comprises cooperating dies so constructed and related as to guard against objectionable die breakage while rendering. it possible to cut the blanks from metal strip and form them accurately into cup-washers of desired shape and dimensions at much higher speedthan is possible when producing them on screw machines, thus reducing waste metal and increasing production, with a corresponding decrease in cost of production while eliminating the necessity of using screw machines. Further objects and advantages of our invention will appear from the detail description.

In the drawings:

Figure 1 is a central vertical sectional view through the upper and lower dies and associated parts for cutting the blanks and forming them to bell shape, certain parts being shown in elevation and certainother parts being broken away, the upper die being at the end of its down stroke;

Figure 2 is a central vertical sectional view through the upper and lower dies and associated parts for forming the belled blanks to the desired size and shape of the washer andpunching an opening through the upper end thereof, certain parts being broken away and other parts being shown in elevation, with the upper die at the end of its up stroke;

Figure 3 is a view' similar to Figure 2 but with the upper die means on its down stroke and in position for trimming the blank;

Figure 415 a view similar to Figure 3, but with the upper die means at the end of its down stroke; 1 Figure 5 is a sectional view through the lower die block and associated die structure, taken in the axial plane of the forming post, showing a modified' form, with. a belled blank disposed over the post;

Figure 6 is a view similar to Figure 4 but embodying the modified form of forming post shown in Figure 5;'

Figure? is a side view oi a belled blank pro duced by theIdies shown in Figure 1;

' Figure 8 is a side viewv of a cup-washer produced from the blank of Figure 7 by the dies of Figure 2 or of Figure 6;

Figure 9 is an outer end view of one of the trimmings cutters; and

Figure 10 isa plan view of the trimmings cutter of Figure 9.. v

In Figure 1 we have shown die means embodying our invention suitable for cutting a blank and one of which is shown at 2|, are secured in ring l8 and extend upward therefrom-andareslidable through corresponding bores in the press plate or block [5.

A blanking die 22 seats upon vthe upper face of block [5 and is secured thereto in any suitable known manner, conveniently by bolting. Die 22 is provided with a cylindrical opening 23 therethrough which receives a collar 24 having a sliding fit with the. surrounding ,wall of opening 23, and on a tubularforming post 25 screwed or otherwise suitably ..secured 'in" the upper end portion of tube l6 and disposed in concentric spaced relation to the surrounding wall .of, opening 23. The exterior diametr of 'post25is somewhat less than the interior diameter of the desired cup-washer, and the upper portion of this post is appropriately shaped togive the desired bell shape to the blank, as will,be explained pres,-

.ently. The pins 2| contact'dthe under face of collar 24 for urging the latter {upward by means of compression spring [9.

Blanking die 22 cooperates witha hollow cy.- lindrical blanking punch 26, provid ed at its upper end with an outer circumferential fiange21fand mounted in a corresponding opening in a die block 28 suitably secured in a known manner, conveniently by bolting, to ram 29 of ,the press, againstlthe under face of which ram the upper end of blanking punch 26 seats. Apiercin'gpunch 30 is screwed or otherwise suitably secured in ram 29 and extends downward therefrom within and concentrically with ,punch 26in spaced relation thereto. Punch 30 is .of proper diameter to pass into the forming post 25 and is disposed coaxially therewith, blanking die 26 being disposed coaxially with opening -23 of blanking die 22 and, when free from expansive stresses, being of slightly less exterior diameterthan the diameter of opening 23, this difference being about one thousandth of an inch more or less, The blanking punch 26 projects below die block 28 a sufiicient distanceto enter opening 23 for a considerable distance, as shown in Figure l. Preferably, a punch 30 is provided .with'a stop shoulder 3| which'bears against the under face of ram 29 for taking the thrust of this punch during the piercing operation.

A knockout collar 32 has a sliding fit in the upper cylindrical portion 33 of passage 33 in blanking die 26, this passage comprising the up- .per cylindrical portion 33 and a lower down wardly flaring mouth portion 33 merging into portion 33*. A suitable number of pins, preferably three, two of which are shown at 34, are secured at their upperends in a disk 35 slidable in a cylindrical bore 36 extending from the upper face of ram 29, and bear at their lower ends on the upper face of knockoutcollar 32. A disk 31, suitably secured to the lower end of a knockout rod 38, slidable through a guide disk' 39 screwed into the upper endof bore 36, seats on the upper face of disk 35. The collar 32 has a close fit within portion 335' of passage 33 of blanking die 26, sufiicient to retain it therein in stroke of the blanking punch 25,

blanking die 22, when blanking punch 26 is at .the end of its down stroke shown in Figure 1 so that, when collar 24 is in its uppermost position, the upper face thereof is flush with the upper face of blanking die theupper face of blanking die 22, over opening 23 .thereof, during the upstroke of blanking punch 26, in a known manner. On the down a flat circular blank is cut from the strip 4|, by the cooperating cutting edges ofdie 22 and punch 26 and, in the continued down stroke of punch 26, this blank is formed .into bell shape by the inner surface of punch 26 in cooperation with the forming post 25, producing the belled blank b of Figure 1, the upper encl of which blank is pierced by punch 30 during forming of the blank to belled shape, providing a suitable opening through the top of the blank. The collar 24 is forced downward by blanking die 26, during the cutting and belling operation, and cooperates therewith to prevent wrinkling of the blank as it is formed into bell shape. The blank thus produced tapers upward, the lower portion thereof being spaced a slight distance away from the forming post 25 and of slightly greater interior diameter than the interior diameter of the desired washer, the upper portion of the blank being of less interior diameter than that of the desired blank, and the t p of the belled blank being more or less rounded. The length of the .stroke of the blanking die 26 is such that at the end of its down stroke, shown in Figure 1, suitable clearance 42 is left between die block 28 and the metal strip 4|, which may be a strip of steel of suitable temper and considerable thickness as shown. As the press ram 29 approaches the limit of its upstroke, knockout rod 38 contacts stop 40, and in the continued upstroke of ram 29 blanking die 26 moves upward relative to knockout collar 32, which serves to strip the blank from piercing punch 30 and from the blanking die or punch 26. In the meantime, the strip 4| is advanced an appropriate distance for cutting another blank therefrom and on the succeeding down stroke of ram 29, and with it the blan i g die 26-and associated parts, another blank is cut and belled in the manner described, and knockout collar 32 is returned to its position shown in Figure 1. The slugs cut from the blank by the piercing die 30 pass downward through the forming post 25 and thence through tube I6 into a suitable receptacle placed beneath this tube.

As above stated, the blanking punch 26 is of an exterior diameter slightly less than the diameter of opening 23 of blanking die 22, when in its normal or unexpanded condition. During the operation of cutting the blank and forming it to bell shape between the forming post 25 and the blanking punch 26, the latter punch is subjected to rather high outward pressure causing radial expansion thereof. When that occurs, however, the portion of punch 26 thus expanded is within opening 23, it being noted that the upper end of forming post 25 is an appreciable dis- 22. A metal strip 4| is fed across tance below the upperface of blanking die 22, as 'shown' in Figure 1. Accordingly, the extent to which blanking punch 26 can expand radially is limited by the surrounding wan of opening 23, and the maximum possible radial expansion of blanking punch 26 is restricted so as to be within the elastic limit thereof. That renders it possible to utilize punch 26 for both cutting the blank and forming it to bell shape, as described, without risk of breakagev of punch 26 by the outward "radial pressure to which it is subjected by that operation. I

'It is possible, by means of the dies and associated parts of Figure l, to cut the blank and form it to bell shape and punch it in a single operation, and we prefer to do it in that manher as being conducive tohigh speed operation and increase production. If desired, however, in certain cases the belied and punched blank of Figures 1 and Wmay be produced in several operations, and our invention comprehends, in its broader aspects, producing the blank in that manner.

The outer lower end portion of the blank b produced as above described is flared outward slightly at b, due to the action of the blanking die and punch in the cutting operation. This Jolank is trimmed and formed to final shape and size, to produce the desired washer, by the die me'ains shown in Figures 2 to 4, inclusive. This means comprises a lower die block 45 which may be suitably secured, as by bolting, to a fixed plate or block of an ordinary punch press. A die hold= ing ring 46 is seated in a recess in the upper face of block 45 about the base of an annular swedging die 41 within which mounted a forming post 48, the latter and die 41 being formed of steel of appropriate characteristics. Post 48 extends upward above swedging die 41 a distance equal to the interior height of the desired washer, the upper end of postj48 being flat and the upper end of die 41 also being flat and providing a flat shoulder 49 extending around post 48 a short distance below the top thereof. If desired, v

the post 48 and die 41 may be formed as one piece, as may the post 48 and die 41 and ring 46, though we preferably 'form these parts separateiy, as shown, with a view to reducing the cost of replacement in the event of breakage. Post 48 is provided with a recess 50 extending from its upper end, and with a bore 5| extending from the lower end of recess 50 and opening into a bore 52 in block 45, it being understood that the plate or block of the press to which block is secured is provided with a suitable opening or bore into which bore 52 opens at its lower end.

The upper end of post 48 is disposed in a plane perpendicular to the axis of this post, as is the upper end 49 of swedging die 41.

An upper die block 53 is secured in any suitable known manner, conveniently by bolting, to the lower face of a press ram 54 which is re ciprocated in a suitable known manner. Die block 53 is provided with acyl-lndrical recess 55, extending from the upper face thereof and rabbeted so as to provide at its lower end an inwardly extending circumferential shoulder 56, block 53 being further provided with a cylindrical opening 51 of less diameter than recess 55 and extending from shoulder 56 through the lower face of block 53. Opening 51 receives the cylindrical body portion of a. hollow trimming die 58, which fits tightly within opening 51 with its lower end flush with the under face of block .53. Trimming die 58 is provided, at its upper end, with an outer circumferential flange 59 fitting snugly within'recess 55 and seating upon shoulder 56. A spacingcollar 60, fitting snugly within recess 55, seats .upon flange 59 and has its upper end bearing against the lower face of ram 54, cooperating therewith to hold trimming die 58 against upward movement relative to die block 53.

A swedging die and knockout member 6| of cylindrical shape fits snugly through trimming die 58 and is provided, at'its upper end with an outer circumferential flange 62 which, in the projected position of member 6|, shown in Figur 2, contacts flange 59 of trimmingdie 58 and limits the extent towhich member 6| may be projected beyond the lower endof die 58. m Member 6| fits snugly about and is slidable on a sizing die 63 suitably secured in ram 54 and projecting downward therefrom through member 6| in concentric spaced relation to trimming die 58, the lower end of die 63 being spaced a short distance above the lower end of die 58. Ram 54 is provided with a cylindrical bore 64 extending from its upper end, which bore slidably receives a disk 65 in which asuitable number of pins, preferably three, are secured at their upper ends, two of these pins being shown at .66, and extend downward through suitable bores in the lower portion of ram 54 into recess 55of block 53, with their lower ends in contact with flange 62 of member 6|. A disk 61, suitably secured on the lower end of a knockout rod 68, has a sliding fit in bore 64 and seats upon the upper face of disk 65. Rod 68 extends upward through a guide disk 69 screwed or otherwis'ewise suitably'secured in the upper end of bore 64, and is of a length to strike a bar or stop 18 carried'by the press as ram 54 approaches the limit of its upstroke. That restrains member 6| against further upward travel and, in the continued upward travel of trimming die 58 with die block 53 and ram 54, die 58 moves upward along member Bl into the position shown in Figure 2, member 6| thus serving as a knockout member to strip the Washer from trimming die 58 and sizing die 63, as will be explained more fully presently. F

When ram 54' is in position at the end of its upstroke, shown in Figure 2, a belled blank b is placed over the forming post 48 with its lower end seating on shoulder 48 of swedging die 41, as shown. The ram 54 is then moved downward and the trimming die 58, which is disposed coaxially with post 48 and is of proper interior diameter to fit snugly about the post, trims off the outer lower end portion of blank I) so as to remove therefrom the flared element b this trimming die also serving to reduce the lower portion of the blank in diameter so as to contract it about post 48, as shown in Figure 3. At that time the trimming die 58 extends downward below member 6| with its lower (and adjacent the upper end of swedging die 41 and the lower end of member 6| resting upon the upper end of blank 17, the upper end of member 6| being spaced a short distance below the lower face of ram 54; as shown in Figure 3. In the continued down stroke of ram 54, trimming die 58 moves downward into position extending about the upper portion of swedging die 41, the under face of ram 54 contacts the upper end of member 6| and, in the latter portion of the down stroke of ram 54, the blank is subjected to axial, forming pressure between the flat shoulder 46 of 'swedging die 41 and the flatlower end of member 6|. When that occurs the sizing die 63 is disposed through the opening in the top of blank I), and the blank is confined circumferentially between .the concentric surfaces of trimming die 58, forming post 48 and sizing die 63. Again referring to Figure 3-, it will be noted that the lower end portion of sizing punch 63 extends through the opening in the upper end of blank 27, the blank retains its shape shown in Figure 2 except as to the trimming off of the flared element 12 and the contraction of the lower end portion of the blank, and the upper end of member BI is spaced a short distance below the under face of ram 54. As ram 54 moves further downward, trimming die 58 moves downward into position extending about the upper end of post 48. In the continueddown stroke of ram 54, the upper end of member 6! is contacted by the under face of ram 54 and, as the ram moves downward, the blank b is subjected to axial forming pressure thus displacing and redistributingthe metal of the blank so as to cause it to flow outward radially thereof thus moving the circumferential wall of the blank, at the upper portion thereof, outward into contact with the surrounding wall of trimming die 58. Further downward travel of ram 54 reduces the blank in height so as to fill the annular space defined by the concentric walls of trimming die 58 and the upper end portion of post 48, the top of the blank being subjected to pressure between the lower end of member BI and the upper end of post 48, at the end of the downstroke of ram 54, thus flattening the top of the blank, which now is really the washer, at both the inner and the outer surfaces thereof. The blank is thus formed into the washer w shown in Figure 4, in which figure the parts are shown in the positions which they occupy at the end of the down stroke of the press ram. It will be noted from Figure 4 that the washer w is of less height than the blank 17 shown in Figure 3, but is of slightly greater wall thickness, due to the displacement and redistribution of the metal of the blank referred to. It will also be noted in Figure 4 there is still slight clearance between the washer w and the lower end of the as.

swedging die and knockout member 6|, from which it will be clear that, at the time of initiation of forming pressure by die member Bl on the blank b of Figure 3, there is ample space for flow of the metal of the blank displaced and redistributed in the manner stated and the blank can thus beaccurately formed to the shape and dimensions of the desired cup-washer. The parts are so dimensioned that the interior diameter of trimming die 58 corresponds accurately to the exterior diameter of the body portion of the desired washer, the exterior diameter of the portion of post 48 above swedging die 41 corresponds accurately to the interior diameter of the desired washer, the diameter of sizing. punch 63 cor responds accurately to the diameter of the opening through'the top of the desired washer, and the vertical distance between shoulder 49 of swedging die 41 and the lower end of member 6|,

when ram 54 is at the end of its down stroke as shown in Figure 4, corresponds accurately to the height of the desired washer. The blank cut and belled by the means shown in Figure 1 and above described, in 'a single operation, is thus accurately formed into a washer of the desired shape and dimensions, in a single operation, by the means shown in Figures 2 to 4, inclusive, as above described. I

If desired, in certain cases, the belled blank of Figure '7 may be formed into the washer .of Figure' 8 by several separate operations, and, our invention, in its broader aspects, comprehends forming the blank into the washer in that manner, though we preferably do thatin one operation, as above described, as being conducive to increased production with corresponding decrease in cost.

The die block 53 is preferably made of cold rolled steel and the trimming die 58 preferably is made separately from the die block, as above explained, and is made of specially hardened tempered steel. When the blank is subjected to axial pressure so as to be formed into the washer, in the manner above described, the trimming die 58 provides a Wall against which the blank is formed into final shape and subjected to rather high radial pressure. It happens at times that the pressure to which this die is subjected, in the forming of the blank to final shape and size to produce the washer, is sufiiciently severe to cause lengthwise cracking of die 58. We have found by experience that this cracking of the trimming die does not impair its use, and this die may be continued in use after it has been cracked into a plurality of segments, since it is held firmly within the block 53 which, being formed separately from the trimming die and of a relatively soft steel, does not crack. We have, in fact, made the trimming die 58 in a plurality of segments mounted in the die block .53, and have demonstrated that such a trimming die operates satisfactorily. Preferably, however, this die is made in a single piece and if it later cracks into a plurality of segments it. may still be used satisfactorily, as above noted. I The outer lower end portion or flare b trimmed from the blank 2) by the trimming die 58 forms an annular member or trimming 11 This trimming is forced downward along swedging die 41 in the down stroke of the trimming die. It is necessary that the trimmings be removed from about the swedging die, as otherwise they would accumulate and interfere with operation of the dies, as will be obvious. In order that these trimmings may quickly be removed from about die 41, we provide means adjacent the base and at opposite sides of die 41 for cutting the trimmings in two. This comprises cutting members 13 each having a head 14 and a depending stem 15 which fits into a corresponding bore 16 in the base of swedging die 41. The inner end of head 14 is concaved at T! to fit about the body portion of swedging die 41, and this head tapers outward and upward from its inner end and sides to provide a cutting edge 18 extending downward and outward from the body .of swedging die 41. As the trimming die 58 moves downward along the swedging die 41, the trimmings b are forced downward along the latter into contact with the cutting edges 18 of the cutters 13, by which the trimmings are cut in two and forced outward away from the body portion of swedging die 41. The trimmings thus cut apart may quickly be removed by the operator, without causing any objectionable delay in placing of the blanks over the forming post 48 during the operation of the press.

The forming post 48 of Figures 2 to 4, inclusive, is formed of steel of proper temper and hardness and, during the forming of the blank by axial compression thereof so as to produce the washer, the sizing punch 63 extends into recess 58 of post48, in which it has a snug fit, preventing radial compression of this post beyondits elastic limit and thus guarding against cracking thereof by the radial pressure to which it is subjected during the operation of forming the blank to produce the washer. In Figures and 6 we have shown a forming post l8 formed of a highly elastic but incompressible material, such as solid rubber. This forming post is recessed from its upper end for reception of the lower portion of the sizing punch 63, recess 50 of post 48* being of less depth than recess 50 of the steel post 48 of Figures 2 to 4, inclusive. The blank b is placed over the upper end portion of post 48, as before, and during the down stroke of ram 54 of the press is subjected to axial forming pressure. As the sizing punch 63 moves downward it contacts post 8 at the lower end of recess 50 and, in the remaining down stroke of ram 54, post w is subjected to pressure at its upper end and also to th pressure exerted by sizing punch 63, the result being that the material of this post is displaced and the tendency is for the portion of post 48 above swedging die 41 to expand radially under considerable pressure, thus exerting high outward radial pressure against the inner face of the body portion of the blank and forcing it tightly against the surrounding wall of the trimming die 58. The body portion of the blank is thus subjected'to direct outward radial pressure of considerable magnitude, which facilitates shaping it accurately to the surrounding wall of the trimming die 58, where as in the die means of Figures 2 to 4, inclusive, the outward radial pressure to which the blank is subjected is indirect and is a component resulting from the axial forming pressure to which the blank is subjected. The use of a rubber forming post is advantageous in cases where there might be a tendency for the body portion of the washer being produced to bend or buckle inward, due to the unusual height of the washer or characteristics ofthe material from which it is being formed, or from other causes, but we have found that ordinarily the use of a steel forming post is satisfactory and produces the required accuracy in cup-washers formed in the manner above described.

It will be understood, as above indicated, that changes in the method, and in the construction or operation of the means of practicing the method, of our invention may be resorted to without departing from the field and scope thereof, and we intend to include all such variations, as fall within the scope of the appended claims, in this application in which the preferred forms only of our invention have been disclosed.

We claim:

1. The method of producing a metal cupwasher, which comprises cutting a metal blank and forming it to bell shape and punching it in a single operation, and trimming off the outer lower end portion of the blank and subjecting it to axial forming pressure while restricting flow of the metal radially of the blank in a second and single operation, thereby reducing the height of the blank and displacing and redistributing the metal thereof and forming the blank to the size and shape of the desired washer.

2. The method of producing a metal cupwasher, which comprises cutting a metal blank and forming it to bell shape, and trimming off the outer lower end portion of the blank and subjecting it to axial forming pressure between opposed flat surfaces while confined radially between concentric surfaces respectively corresponding in diameter to the inner and the outer diameters of the desired washer, thereby reducing the height of the blank and flattening its ends and displacing and redistributing the metal thereof so as to fill the space between said concentric surfaces and form the blank to the size and shape of the desired washer.

3. The method of producing a metal cupwasher, which comprises cutting a circular metal b a k and formi g it to bell shape, trimming off the outer lower end portion of the blank and reducing the lower portion thereof to apprcximately the same interior and exterior diameter as that of the desired washer and subjecting the blank to forming pressure between opposed flat surfaces while confined between concentric surfaces respectively corresponding in diameter to the inside and the outside diameters of the desired washer, thereby flattening the ends of the blank and reducing it in height and displacing and redistributing the metal of the blank forming it to the shape and size of the desired washer.

4. The method of producing a metal cupwasher, which comprises cutting a circular metal blank and forming it to bell shape and punching an opening through the top wall of the blank in a single operation, and in a second single operation trimming off the outer lower end portion of the blank and forming it to the desired size and shape between concentric surfaces and about a cylindrical surface extending through said opening by subjecting it to axial forming pressure between opposed flat surfaces effective for reducing the height of the blank and for displacing and redistributing the metal thereof, thereby, p oducing the desired washer.

FRANK KAPPLE.

JOSEPH F. SIKORA.

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