US2739557A - Method and apparatus for deep drawing of metals - Google Patents

Description

March 2?, W56 w. w. smusrrz METHOD AND APPARATUS FOR DEEP DRAWING OF METALS 2 Sheets-Sheet 1 Filed June 4, 1951 LPN $070k bhme/m 14/ 59%06/72 W. W. STAUBETZ Mamh 2?, 1956 METHOD AND APPARATUS FOR DEEP DRAWING OF METALS 2 Sheets-Sheet 2 Filed June 4, 195} United States PatentO METHOD AND APPARATUS FOR DEEP DRAWING F METALS Wilhelm Walter Staubitz, Preston, Ontario, Canada, as-

signor of one-half to Charles Nevin House, Preston, Ontario, Canada Application June 4, 1951, Serial No. 229,681

4 Claims. (Cl. 113-46) This invention relates to the deep drawing of sheet metal and more particularly to a method and apparatus for producing a deep draw in a single operation.

in convention drawing of sheet metal the depth to which a cylindrical shell or cup can be drawn without annealing is of the order of two thirds the diameter of the shell. If deeper draws are required the shell is removed after its initial drawing and annealed to remove strains set up in the metal. The scale formed on annealing must then be pickled off and a further drawing then effected to increase the shell depth.

It has been proposed to eliminate strain in the metal by drawing the shell or cup successively in different directions, that is, drawing it into a shallow cup or shell in one direction and turning this shallow cup or shell inside out by drawing in the opposite direction into a deeper shell of small diameter and repeating these operations until the final depth and diameter are reached.

While such latter method has satisfactorily eliminated strain without annealing, the method involves a number of sequential steps and appreciable handling of the shell and further, has required a number of dies, and where pro- I duction is required several pressers were necessary.

The principal object of this invention is to enable a deep draw which previously required several operations to be effected in a single operation with a single die arrangement and press to provide an important saving in time and expense.

Another object of the invention is to more eliectively work the metal of the shell being drawn than heretofore to relieve the metal of undesirable stresses.

A further important object is to form the shell bottom simultaneously with the drawing operation.

Again another object is to provide an apparatus of relatively simple form to accomplish the deep draw as aforesaid in a single operation. I

The principal feature of the invention resides-in forming a composite die arrangement wherein a single stroke of the press without interruption of movement of the die parts carried by the ram of the press in sequence cuts the metal blank, draws it into a shallow cylindrical shell or cup and then reverses the shallow shell into a deeper shell of smaller diameter while thoroughly working the metal of the walls of the shell during reversal to provide a most effective normalizing action, relieving stress in the metal to thereby permit the deep draw.

A further important feature resides in forming as a bottom of the cylindrical die member into which the shell is finally drawn as a forming die to shape the shell bottom under the stroke of the press ram.

Another feature resides in mounting this latter forming die as a displaceable member moving under the ram stroke to begin bottom forming of the shell adjacent the point of reversal of the metal under drawing.

Still a further feature resides in mounting the die parts for ready replacement and/or interchanging.

These and other objects and features will be apparent from the accompanying drawings in which Figure 1 is a vertical mid-sectional view of a deep drawing apparatus for carrying out the deep draw according to the invention.

Figure 2 is a plan view of the lower portion of the apparatus partly broken away.

Figure 3 is a plan view of the upper moving portion of the apparatus partly broken away.

Figure 4 is a fragmentary vertical sectional detail showing the upper movable die part and punch advanced in the first step of the draw.

Figure 5 is a view similar to Figure 4 showing a further step of the draw.

Figure 6 is a complete mid-vertical sectional view showing the position of the die parts upon completion of the draw.

With reference to the drawings, 1 represents the base of the machine which may be the bed plate of a press and on this is mounted a die block base 2 which carries an outer annular stationary die part 3 and a concentric inner annular stationary die part or member 4.

The outer die part 3 includes a ring 5 removably secured thereto by screws 6 and presenting an annular cutting edge 7.

The upper edge 8 of the inner die part 4 is rounded to form a drawing surface over which the metal of the shell is adapted to be drawn when the shell is being reversed.

Anchoring the inner stationary die part t in concentric relation with the die part 3 are screws 9 and slidably mounted in the annular opening 10 between the die parts 3 and 4 is a follower or presser ring Lil carried by the rods or pins 12 which are adapted to operate through openings 13 in the base 1 against suitable spring or hydraulic pressure (not shown).

Within the inner die part 4 is a bottom-forming die member 14 mounted on a rod or pin 15 again operating through the base of the machine 1 against a suitable pressure.

At the corners of the die block base 2 are cylindrical guides 16 reinforced by webs 1'7. Mounted to slide on guide posts 18 extending upwardly from the guides 16 is an upper die assembly 19 having cylindrical guides 20 to receive the guide posts and reinforcing webs 2i.

Included in the die assembly 19 is an outer annular die support 22 carrying the die ring member 23 removably secured to the end thereof by screws 24 arranged in slots 25 in the wall of the support 22.

Secured concentrically within the support 22 is a punch 26 having a bottom-forming .die end portion 27. The upper die assembly 19 may be suitably operated by the ram of the press diagrammatically designated at 28.

The functioning of the apparatus in producing a deep draw is as follows:

With the upper die assembly 19 elevated, as shown in Figure 1 and the lamina 29 of sheet metal introduced therebetween, the downward movement of the die assembly will blank the sheet metal into a disc by virtue of the cutting action of the annular edge 7 of the lower die ring 5 and the outer annular edge 3% of the upper die ring 23. Further downward movement of the upper die assembly forcing the following or presser ring 11 to retract will turn the metal of the blank downwardly over the upper edge 8 of the die part 4 to form a shallow shell S as shown in Figure 4.

After completion of this shell S the continuing downward movement of the upper die assembly 19 under action of a suitable press brings the punch 25 into contact with the bottom of the shell. Then as the downward movement continues the punch 26 will effect the drawing of the shell in reverse direction over the rounded upper edge 8 of the inner stationary die part 4 to turn the shell than the shell S.

Figure-5 shows the shells partially formed and Figure 6 showsthe complete formation.

As the punch and completeupper die assembly 19 move downwardly the bottom portion 32 will be forced against the bottom-forming die part 14; and the co-operationof' this part with the bottom-forming'end'of thepunch" 27 forms the bottom into the shape of a bottom former 14 with indents corresponding'to the protuberance's 32 on the die member 14 simultaneously with the reverse draw.

Thus in a single stroke of the press successive' draws in opposite directions and the-formingoperation are accomplished to provide a product which has heretofore required several separate operations.

It will be noted that the die support'22 and its ring 23' move together with the punch 26, which movement is accommodated by the reciprocal mounting of'the' follower or presser ring 11 and'the bottom former 14, which latter members are displaced against a suitable resisting force.

As has been pointed out, it is not new in the art to relieve internal stressing of drawn metal by working the metal through operation of a reverse draw, but the present invention permits the application of suchprinciple' to providing in a single stroke of the press a; deeperdraw than previously possible and such a result is obtained through the extremely complete working of the metal in the press stroke. To afford this increased working'it'will be seen that the metal of the blank formed from the lamina 28 is first formed over the edge 8 of the inner stationary die part 4 and is drawn between the die ring member 23 of the upper die assembly and the follower ring 11 around the inner peripheral drawing edge 33' or" the ring 23, and then subsequently is drawn in reverse direction over the edge 8 against the tendency of the annular support 22 to continue drawing the blank in its initial direction under frictional force.

The result is a complete re-arrangement of the molecular structure of the metal under such working to relieve crystallization of the metal occasioned in the initial forming over the edge 8.

It will be noted that while the metal is being reversed it is not subjected to any critical bending stresses by virtue of the radius of curvature of the upper edge 8 of the inner stationary die part4 and also by virtue of rounding of the drawing edge 33.

It will further be noted that during the reversal of the shell the annular die support 22 of the upper die assembly is being positively advanced in the downward direction while the walls of the shellare beingmoved upwardly, not only increasing the working of the metal but eliminating the necessity of mounting the punch 26 on the upper die assembly for movement relative the annular die part 23.

While a particular construction of apparatus is illustrated herein, it will be appreciated that variations in the apparatus may be made while eflfecting a working offthe metal in accordance. with the invention to atfordfina deep draw in a single stroke of the press without departing from the scope of the appended claims.

What I claim as my invention is: v

1. In a blank cutting anddeep drawing apparatus, an annular movable die part and .a concentric punch rigidly, secured thereto, a pair of concentric annular stationary die parts to receive said movable die part and punch, .said' movable die part being arranged'to enter between said' stationary die parts prior to entry of'saidpunch to draw a shallow shell, and said punch being arranged relative the leading face of said movable die partrto thereafter engage and reversely draw said shell over the inner of'said annular stationary die parts while said'shell' 'is in frictional contact with and moves in opposition to the movement of' said movable die part, the stroke of said movable die part and punchbeing of a length sufiicient'tocarry said' punch into said stationary'die parts to complete the reverse draw of said shell means" foroperatingf said" movable die part and' punchin unison throughoutthe" drawing and subsequent reverse drawing of'saidsheil and.

a bottom-forming die arranged within the inner of said stationarydie partsandurged under pressure to the outer end thereof, said punch on entering the inner of said stationary die parts being adapted to displace said bottomforming die against its pressure to simultaneously form the bottom of the shell as it is being reversely drawn.

2. Apparatus as claimedinclaim 1 in which a follower ring is yieldably mounted between said-annular stationary die parts, and a; bottom formingdie part is arranged withinthe inner of said stationary die parts and said punch being-formed witha co operating:bottom-forming end to force a deep" drawn shell against said bottomforming die part.

3. A compound die adapted'to draw shapes successively in opposite directions comprising a pair of annular concentric stationary'die parts; the" outer having an inner peripheral cutting edge and the inner feathering to a rounded drawing edge, an annular moving die part having an integral punch arranged concentrically therein mounted in concentric relation with the stationary die-parts with said annular moving die' part adapted to enter between said stationary die parts and said punch being adapted to sub'sequently'entertheinner of said stationary die parts, a follower ring arranged between said stationary die'parts and movable'under pressure of said annular moving die parts, means for moving said annular moving die part andpuncha distance sutficient to carry said punch home withinsaid inner annular'statio'nary die part to first efiect a drawing of a blank cut'by said peripheral'cutting edge and-to thereafter reversely draw the metal of the blank into said-inner stationary die partunder action of said press while said moving annular die part continues to move with the punch in frictional contact with and in opposition to the movement of said blank to increase the working of the metal of the'blank as it is being reversely drawn and a bottom-forming die arrangedwithin the inner of said stationary die parts and'urged under pressure to the outer end thereof, said punch on'entering the inner of said stationary die parts displacing said bottom-forming,

die against its pressure to simultaneously form the bottom of theblank as it is being reversely drawn.

4; A drawing die adapted'for use with a standard press having stationaryand movable parts, comprising a first unit including a die body and a diep'ost, said body and post being held in axial alignment and against relative movement, and a second unit comprisin'g'a sleeve, said units being adapted formounting on the base and ram members of 'said press so as to be movable towardsand away from each other, said die body havinga cavity for receivingsaid sleeve, said cavity and said sleeve having co-operable drawing'surfaces so that a'blank positioned therebetween is drawn into a cup-shaped shell by relative movement of said'units to introduce said sleeve into said cavity, said sleeve having a recess for receiving said post, a bottom-forming die arrangedin said recess and urged under pressure to the outward end of said sleeve, said sleeve and said post having co-operable interior and exterior drawing surfaces so'that said shell is inverted and drawn into a reduced cup-shaped shell by relative movement of said units to introduce said post into said sleeve, and said post on'being introduced into said sleeve displacing said bottom-forming die inwardly of said recess against its outward pressure to shape the shell as it is being inverted and drawn into its reduced cup shape.

2 References Cited in the file of this patent UNITED STATES PATENTS 368,526 Fowler Aug. 16, 1887 460,551 Bodge Oct. 6, 1891 460,594 Norton Oct. 6, 1891 483,008 Norton Sept. 20, 1892 1,636,1l0 Rode July .19, 1927 1,649,841 May NOV. 22, 1927 1,837,720" Luce etalL Dec. 22; 1931 2,602,411 Schnell July 8, 1952"

Claims (1)

1. IN A BLANK CUTTING AND DEEP DRAWING APPARATUS, AN ANNULAR MOVABLE DIE PART AND A CONCENTRIC PUNCH RIGIDLY SECURED THERETO, A PAIR OF CONCENTRIC ANNULAR STATIONARY DIE PARTS TO RECEIVE SAID MOVALBE DIE PART AND PUNCH, SAID MOVALBE DIE PARTS PRIOR TO ENTRY OF SAID PUNCH TO DRAW SATIONARY DIE PARTS PRIOR TO ENTRY OF SAID PUNCH TO DRAW A SHALLOW SHELL, AND SAID PUNCH BEING ARRANGED RELATIVE THE LEADING FACE OF SAID MOVALBE DIE PART TO THEREAFTER ENGAGE AND REVERSELY DRAW SAID SHELL OVER THE INNER OF SAID ANNULAR STATIONARY DIE PARTS WHILE SAID SHELL IS IN FRICTIONAL CONTACT WITH AND MOVES IN OPPOSITION TO THE MOVEMENT OF SAID MOVABLE DIE PART, THE STROKE OF SAID MOVABLE DIE PART AND PUNCH BEING OF A LENGTH SUFFICIENT TO CARRY SAID PUNCH INTO SAID STATIONARY DIE PARTS TO COMPLETE THE REVERSE DRAW OF SAID SHELL MEANS FOR OPERATING SAID MOVABLE DIE PART AND PUNCH IN UNISON THROUGHOUT THE DRAWING AND SUBSEQUENT REVERSE DRAWING OF SAID SHELL AND A BOTTOM-FORMING DIE ARRANGED WITHIN THE INNER OF SAID STATIONARY DIE PARTS AND URGED UNDER PRESSURE TO THE OUTER END THEREOF, SAID PUNCH ON ENTERING THE INNER OF SAID STATIONARY DIE PARTS BEING ADAPTED TO DISPLACE SAID BOTTOMFORMING DIE AGAINST ITS PRESSURE TO SIMULTANEOUSLY FORM THE BOTTOM OF THE SHELL AS IT IS BEING REVERSELY DRAWN.

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