US2274828A - Die device - Google Patents

Description

March 3, 1942. H, w; F|NZE 274,828

DIE DEVICE Filed NOV.4 12, 1938 IN VENTR A T T ORNE YS.

Patented Mar. 3, 1942 DIE DEVICE Harvey W. .FinzeL Detroit, Mich., assignor to Douglas .& Lomason, De

tion of Michigan troit, Mich., a corpora- Application November 12, 1938, Serial No. 240,035

` 7 claims. (01.153448) This invention relates to die devices for prol' n ducing various articles from sheet material by stamping operations. The invention has particular reference to dies adapted for performance of forming and deep drawing operations, as well as operations producing wide flanges by wiping the sheet material down from the flat or semiformed portions of the stampedblank.v In one of its aspects the invention contemplates providing an improved method -for performing such operations.

In performing operations of the above character great difficulties have been encountered when the sequence of stamping operations required a deep draw or wiping the portions of a blank l l`2` provide a die device with the aid of which it is down in order to produce a wide flange or skirt J is being wiped down. The tops of such wrinkles f or folds produce excessively high local pressures on the punch of the die device, which pressure is often suflcient to squeeze out the lubricant used to facilitate forming operations and to produce a metal-to-metal contact between the punchV and the blank. The high pressure and the metal-tometal contact produce exceedingly high local friction between the blank, which is held stationary, and the moving punch of the die device. Such friction prevents sliding of the punch relative to the vblank which, in turn, results in sticking or freezing of the tops of the wrinkles to the punch during the first moments of the wiping operation and pushing in front of the punch o-f the larger. part of the -blank portion intended for the skirt or flange. As a result, overstretching and tearing of the metal behind the portion of the punch in direct contact with the material of the blank often occurs. The above difficulties produce a large percentage of scrap in stamping J operations, limit the depth of the permissible draws in stamped articles, require ample lubrication even for relatively shallow draws, do not permit `cold. stamping of heavier stock, and require producing deep draws in several steps with intermediate annealing of partially t formed blanks. In addition, the surfaces ofthe stamped articles come out rough and uneven and require additional finishing by some other method or smooth surfaces approaching in appearance burnished surfaces.

A further object ofthe invention is to provide a die device which requires less lubrication and power for its operation.

A still further object is to provide a die device by whichit is possible to perform cold stamping operations which, if performed in conventional die devices, require preheating of the blank.

'A kstill further object of the invention is to possible to produce stamped articles with deep draws which are either entirely unattainable when conventional dies are used or which come out from such conventional dies with rough or broken surfaces.

A still further object of the invention is to provide an improved die device producing even flow cf metal in the formed blank.

A still further obj ect of the invention is to provide an improved device for stamping which is more efficient, produces deeper draws and flanges, improves the structure of the metal in the blank, as well as the surface thereof.

It is an added object of the invention to pro- Vide a die device of the foregoing .character which is simple'in construction and reliable in operation, and which is relatively inexpensive to manufacture.

Other objects of thisinvention will appear in the following description `and appended claims, reference being had to the accompanying drawing forming a part of this specication wherein like reference characters designate corresponding parts in the several views.

rlig. 1 is a perspective view of a die device embodying the present invention with parts broken away.

Fig. 2 is Ia top View, partly in section, taken on the line 2 2 of Fig. 1.

Fig. Sis a fragmentary sectional view taken in the direction of the arrows on the vertical section plane passing through the line '3 3 of Fig. 2.

Fig. 4 is a -fragmentary sectional View taken in the direction of the arrows on the transversevertical section plane passing through the line `fl--Il of Fig. 3.v

Fig. 5` is a view similar in part to Fig. 3, showing the punch in its up position before descending upon the blank.

, Fig. 6 illustrates al preformed molding which is nally formed in the die device illustrated in the above figures.

Fig. 'l is a perspective view showing the finally finished and trimmed blank.

' Before explaining indetail the present invention it is to be understood that the invention is not` limited in its application to the details of construction rand arrangement of parts illustrated in the accompanying drawing, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation, and it is not intended to limit the invention claimed herein beyond the requirements of the prior art.

In the drawing there is shown, by way of example, a die device constructed in accordance with one embodiment of the present invention. The device illustrated is adapted for forming finally a preformed molding. It will be understood, however, that the die devices constructed in accordance with the present invention are equally applicable for performing other stamping operations involving forming, deep drawing and other operations in which the reduction of area of the blank occurs. The die devices constructed in accordance with the invention are particularly valuable for performing so-called wipingdown" operations for producing wide flanges or depending skirts on stamped articles.

Referring to thefdrawing, the die device illustrated therein comprises 4a base plate IU to which there is secured in any suitable manner a base block II. In the recess IIa of the base block II there is secured to said block with the aid of screws I2 a die I3. The upper portion |30. of the die is shaped to receive a preformed molding I5 and to provide the necessary support therefor. The structure so far described constitutes the stationary part of the die device.

The movable part of the die device comprises an upper plate I6 having a shank I'I by which it is secured to the movable pressure exerting member of a press. To the upper plate I6 there is secured with the aid of bolts I8 a punch block I9, the dowel pins being provided to prevent any lateral movements of the upper plate I6 and the punch block I9. To the punch block `I 9 there are secured with the aid of Afour screws 2I two lower punch plates 22 having adjacent the central portion of vthe die I3 slanted portions as indicated at 22a.

For the purpose of holding the blank in positionv at the moment when the punch block reaches the blank or preformed molding I5, there are provided holding means representedV by a pressure block 23 guided by the pins 2li. The pins 2li are provided with heads 24a; limiting the downward movement of the pressure block 23 with respect to the upper plate I6 caused by the action of the compression spring 25 provided between said upper plate and pressure block 23 and held in suitable recesses provided in said members.

In the present structure the pressure pad' performs also a part of the forming operation and the same is done by the properly shaped portion 2S thereof cooperating with a. correspondingly shaped portion 21 on the die I3. The spring 25 is made heavy enough to be able to exert the desired pressure when it is compressed by the action of the movable punch. The guide pins I4 ensure proper cooperation of the punch and die.

The portion of the structure so far described is old, and a more detailed description thereof is dispensed with for the sake of brevity.

From an examination of Figs. 6 land 7 it will be understood that when the end` [5a of the molding I5 is bent to produce a portion indicated in Fig. 7 by the numeral 28, a considerable reduction of area has to take place in the side wallsV I5b of the molding'.v When such v'reduction of'are'a occurs, the-material of the molding tendslto form a number of wrinkles orfolds. In` conventional dies formation of such wrinkles or folds on the way of the downwardly moving punch exerting exceedingly high pressure produces the disadvantages described above in detail. The occurrence of such objectionable phenomena produces scoredsurfaces at the tops of the folds, minute cracks at the top of the flange, and rough surface covered with minute wrinkles at the valleys between the folds which may be straightened or flattened by 'the downward moving portion.

With a highly polished stock, such as used for moldings and the like, such rough surfaces are very objectionable, and some methods of nally finishing the formed end of the molding must be employed.

In accordance with the invention, means are provided whereby the above diiculties are overcome and largely eliminated, and the surface of the blank in which reduction of area is taking place comes out from the die very smooth and, in fact, resembling a burnished surface.

In the present embodiment of the invention the above means are exemplified by working rollers 30 provided in cylindrical recesses bored in the material of the punch block I9 and extending over the surface thereof for a distance sufficient to insure proper contact ofthe rollers with the surface of the blank. Said distance may vary in accordance with conditions. For the die of the above described construction I prefer to use about fifteen thousandths of an inch. 'In order to eliminate friction, the working rollers 30 arey supported by means of supporting rollers 3l provided in the punch block I9, see Figs. 4 and 2. The working rollers 30 as well as the supporting rollers 3l may be removed from the block or reinserted thereinto. The rollers are retained in the block I9 by means of a cover 32 closing the front vertical side of the punch block I9 and secured thereto with the aid of screws 33. The arrangement of the supporting rollers is such that they provide the necessary support for the working rollers 30 in the direction of the component force acting thereon, which force in the present structure acts on a line forming an angle of about 45 to the horizontal.

When the preformed molding I5 is inserted into the die device, as shown in Fig. 6, the pressure block 2'3 contacts the same and holds it in place bending at the same time the end with the aid of cooperating portions 26 and 2'I of the pressure block and the die. In consequence of such bending a number ofY Wrinkles will tend to form on the side Walls |51) of the preformed molding I5. However, whenv the working rollers 30 establish` contact with the walls lib, exceedingly high rolling pressure is exerted thereon, wiping down the material of the walls. Because of the rolling contact produced by the working rollers 30, the friction and the objectionable consequences thereof are entirely eliminated, and the surface is not only formed smooth but is, in fact, burnished to produce a smooth, glossy surface. The excess metall flows to the. bottom of the walls I 5 and is trimmed or ground olf. By virtue ofthe above, a smooth surface unattainable 'with the use of conventional die devices is produced, and it does not require any additional iinishingoperations. f

Thus, in one of its broader aspects the invention contemplates providing an improved method of stamping including forming operations i'rivolving reduction ofA area of the'- blank, which method includes' a' step of forming-'the' blank by rolling; friction-less' contact, producing a( combined forming and burnished effect on the blank.

I claim:

1. Die mechanism for operating upon a'anged workpiece, comprising a die and a punch,` one movable relatively to the other, said punch comprising a body member and a member movable relative thereto, the relatively movable member cooperating with the die and movable by engagement therewith to form a portion of said workpiece during an initial relative movement of the punch and die, a roller provided within the body member of the punch and rotatable therein, said roller projecting beyond the surface of the punch for cooperation with the die to engage the formed portion of the workpiece aftersaid in-v itial movement and exert a rolling pressure thereon, and means providing rolling support for said roller throughout the major portion of the length thereof.

2. Die mechanism for operating upon a iianged workpiece, comprising a punch having a body and a yieldable pressure member shiftable within the body, a die having a portion movable between side portions of the punch and engageable with said pressure member to retract the same and perform a forming operation on the workpiece, rotatable rollers mounted in said side portions and engageable with the workpiece after said forming operation to exert rolling pressure on the workpiece at the locality of the formed portion thereof, and a plurality of rollers mounted within the bodi7 of the punch and engaging said first named rollers to receive the reaction forces therefrom.

3. Die mechanism for operating upon a flanged workpiece, comprising a punch having a body and a yieldable pressure member shiftable within the body, a die having a portion movable between side portions of the punch and engageable with said pressure member to retract the same and cooperate with a forming portion of the pressure member to form down an end of the anged workpiece, and a rotatable roller mounted in a side portion of the punch opposite said pressure member and projecting sufficiently beyond the surface of said side portion to exert a rolling pressure on a flanged portion of the workpiece after the completion of the forming operation.

4. Die mechanism for operating upon a flanged member having angularly related surfaces comprising a male die having an upper shaping surface positioned to engage one of said angularly related surfaces of the anged member and a side surface positioned to engage another of said i angularly related surfaces of the flanged member, a punch mechanism comprising a body member and a member slidably carried by the body member and having a lower surface designed to cooperate with the upper surface of the male die in shaping the flanged member, yielding means normally maintaining the slidable member in a depressed relation reiative to said body member,

a roller mounted in a fixed position in the bodyv member above the aforesaid depressed position of said slidable member and arranged to extend slightly beyond the angularly related surface of the flanged member adjacent said side surface of the male die, and meansfor moving the punch mechanism relative to the male die to shape the flanged member between the upper shaping surface of the male die and the lower surface of said slidable member and thereafter to exert a rolling force on the angularly related surface of the flanged member positioned in engagement with the side surface of the male die.

5. Die mechanism for operating upon a channel shaped anged member having a body section and angularly related flanges comprising a male die having an upper shaping surface positioned to engage the body section of the fianged member and side surfaces positioned to engage said flanges, a punch mechanism comprising a body member and a member slidably carried by the body member and having a lower surface designed to cooperate with the upper surface of the male die in shaping the body section of the iianged member, yielding means normally maintaining the slidable member in a depressedrelation relative to said body member, spaced rollers mounted in a xed position in the body member above the aforesaid depressed position of said slidable member and arranged to extendslightly beyond the angularly related anges of the hanged member adjacent said side surface of the male die, and means for moving the punch mechanism relative to the male die to shape the flanged member between the upper shaping surface of the male die and the lower surface of said slidable member and thereafter to exert a rolling force on the angularly related flanges positioned in engagement with the side surface of the male die.

6. A die mechanism comprising a die member constructed to receive and support a anged member with the anges of the member extending along the sides thereof, a punch mechanism movable relative to the die member and comprising a body member and a member movable v relative to the body member, yielding means urging the movable member in a depressed relation relative to the body member, the relatively j,

movable member of the punch mechanism c0- operating with the die member to deform the flanged member during an initial movement of the punch mechanism relative to the die member, a pair'of spaced rollers mounted for rotation in a fixed position inthe body member of the punch mechanism to engage the anges of the flanged member extending along the sides of the die member to exert rolling pressure thereonv after said initial movement of the punch relative to the die member, and means for moving the punch mechanism relative to the die member.

'7. A die mechanism comprising a die member constructed to receive and support a fianged member with the flange of the member extending along the side thereof, a punch mechanism movable relative to the die member and comprising a body member and a member movable relative to the body member, yielding means urging the movable member in a depressed relation relative to the body'member, the relatively movable member of the punch mechanism cooperating with the die member to deform the hanged mem-y ber during an initial movement of the punch mechanism relative to the die member, a forming roller mounted for rotation in a fixed position in the body member of the punch mechanism to engage the flange of the hanged member extending along the side of the die member to exert rolling pressure thereon after said initial movement of the punch relative to the die member, auxiliary rollers mounted for rotation in a xed position between said forming roller and the body member, and means for moving the punch mechanism relative to the die member.

HARVEY W. FINZEL.

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