US2143429A - Apparatus for forming sheet metal forms - Google Patents

Description

Jan. 10, 1939.

J. L. AUBLE APPARATUS FOR FORMING SHEET METAL FORMS I Filed Oct. 14, 1956 4 Sheets-Sheet l 2 I z 1 F //%fig 53 [3 230 I C 30 o 23h 5 40 33 23a 42 L 38 g Q :19 22: B 2.9 o 55 41 22 51 37 o 20 A 23 o o Ell-1.1.

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Jan. 10, 1939. AUBL; 2,143,429

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Jan. 10; 1939. J. L. AUBLE 2,143,429

APPARATUS FOR FORMING SHEET METAL FORMS Filed Oct 14, 1956 4 Sheets-Sheet 3 INVENTOR. 63.3 JAMES [1.AUBLE.

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J. L. AUBLE APPARATUS FOR FORMING SHEET METAL FORMS Filed Oct. 14, less 4-,Sheets-Sheet 4 Jan. 10, 1939.

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ATTORN Patented Jan. 10, 1939 PATENT OFFICE 2,143,429 APPARATUS FOR FORMING SHEET LIETAL FORMS James. L. Auble, Cincinnati, Ohio, assignor to Frank Tea & Spice Company, Cincinnati, Ohio,

a corporation of Ohio Application October 14, 1936, Serial No. 105,550

2 Claims.

My invention relates to theart of drawing and forming sheet metal into forms by a series of forming operations without removing the piece being formed from the drawing and forming means.

This application is a continuation in part of my copending application Serial No. 68,904, filed March 14, 1936, and entitled Apparatus for and method of forming sheet metal forms.

The forming of sheet metal in various forms by the pressure against a sheet of metal by a multiple telescoping die, is not new. Such an arrangement is suggested in the patent to Schimmelbusch No, 783,390. In my Patent No, 1,919,287, of July 25, 1933, mechanism is illustrated which also operates on the above-noted principle. My invention relates to improvements in such forming mechanism in which the tendencies of the metal sheet to buckle and flow unevenly are avoided.

In the forming of sheet metal in mechanism such as that to which my invention relates, the' pressure of a die is applied against the sheet which forces the metal into a female die or mold. If the sheet is held with a fixed clamping action, the difliculty of adjusting the tension makes it likely that the sheet is either held too firmly, in

which event the metal actually contacted by the die will be drawn out too thin, or if the sheet is not held firmly enough, the complete sheet will be pressed, without sufficient drawing of the metal into the female mould, and with the metal lation to the movements necessary to complete the forming operation, in which the frictional retarding action on the sheet being formed is pneumatically controlled.

Because of the pneumatic control of the frictional sheet holding devices, I am' enabled to draw and form metal forms in which the action of the male forming die and the female die is a direct reciprocating action, without any relative rotative movement of the various parts OI the dies with relation one to another.

In my Patent No. 1,919,287, there is disclosed a forming mechanism for sheet metal forms having telescoping rotative parts which act in sequence and position themselves so as to permit the formation of the objectsformed in sequential operations without removing the piece from the forming device until it has been completely formed. While such mechanism is effective, the movement of the parts of the male die mechanism requires a worm actuating drive. In my present invention, a straight reciprocating movement, such as can be brought about in an ordinary toggle press, replaces the old worm drive action, and this permits much greater speed of operation. Further, the pneumatic frictional holding back of the metal sheet permits sufiicient slippa e to cause the metal to flow evenly.

Because of the pneumatic control of the frictional holding of the metal plate during the forming operation, a greater adjustability controlling the flow of the metal is permitted, simply by a variation in the air pressure with which the friction clamping plates are actuated.

The above objects and other objects to which reference will be made in the ensuing disclosure, I accomplish by that certain combination and arrangement of parts of which I have illustrated a preferred embodiment.

Referring to the drawings:

Figure 1 is a vertical sectional view with some parts diagrammatically indicated, of the forming apparatus mounted on a toggle press.

Fig. 2 is a bottom plan view of a portion of one of the latching devices illustrated in Fig, 1.

Fig, 3 is a sectional view of the parts of the mechanism, after the first stage of the forming operation.

Fig. 4 is a vertical sectional view of the parts after the third stage of the forming operation.

Fig. 5 is a bottom plan view of the male die assembly illustrated in Fig. 1, taken from the position indicated by the arrows 5, 5.

Fig. 6 is a perspective view of a sheet metal plate after the first forming operation.

Fig. 7 is a perspective view of the sheet metal plate after the second forming operation.

Fig. 8 is a perspective view of a sheet metal form after the third forming operation.

Fig. 9 isa perspective view of the final form of the sheet metal object.

Fig. 10 is a vertical sectional view of a slightly modified form of apparatus showing details from which the plan of operation will be readily understood.

Fig. 11 is a detail view of the cam track shown in Fig. 10.

Fig. 12 is a horizontal sectional view of the valves employed in the apparatus shown in Fig. 10.

- Fig. 13 is a horizontal sectional view of the valve shown in Fig. 12 in open position.

Referring to the drawings, the upper head of the press is indicated as a platen secured to the actuating parts of the press by means of bolts 2. The female die elements are mounted on the lower platen or base plate 3 of the press.

The female die 4, illustrated in Fig. 1, is secured to the base plate 3 by means of bolts 5. The shape of the female die is as indicated. The first stage opening has inwardly curving walls 6, and a downwardly extending annular wall I.

An inwardly beveled annular portion 8 connects with the second stage die opening, which has a downwardly depending annular wall 9. Another inwardly inclining ledge |0 forms a continuous wall with the third stage female die opening Still another inwardly inclined ledge l2 connects the wall continuously with the final stage female die opening I 3, in which the final shape of the drawn and formed article is accomplished.

An opening M in the base plate 3 permits the upward passage of the ejector ram |5, which, after the article is formed. ejects it upwardly and outwardly from the female die.

Extending upwardly from and threaded into the die 4, is the latch guide bar l6. Further mounted ,on the base plate is the bracket H, which carries the cam track member l8, which, at proper intervals in the drawing and forming operation, cuts ofi the air from the frictional clamping plates.

The upper platen carries a head l9, having a cylindrical inner wall 20. Within the cylinder 20 are the cylinder heads 2|, 22 and 23. The cylinder heads retain compression within the cylinder because of annular washers 2|a, 22a and 23a. held in position by annular rings 2|b, 22b, and 23b. The cylinder heads carry the concentrically mounted male die members 24, 25, and 26. These dies telescope one within the other inversely in the relation in which they have been referred to, and the main male ram 21 is reciprocated in the opening within the inner male die member 26.

Compression cylinders A, B, and C are formed in which air enters through ports 28, 29 and 30. Valves 5|, 52 and 53, having rocking actuating arms 54, 55 and 56, control the release of air through ports 28, 29 and 30. The heads 22 and 23 which respectively carry the male die members 24 and 25, are retained in their relative position with relation .to the head I, by means of the difference in the air pressure in the different chambers, as will be later explained. The heads are locked against receding movement, by means of a series of latch members 31, 38 which are normally pressed inwardly by means of springs 39, 40.

As will be subsequently described, during the operation of the mechanism, after the heads 22 and 23 have completed their initial downward strokes and the compressed gas in the cylinders which have actuated them is exhausted, the latches are released by means of'trigger arms 4|, 42, which engage the member l6, the trigger 4| being actuated at the bottom of the cam surface of the member l6, in the position indicated at Ma, while the trigger 42 is actuated in a position on the cam surfaceindicated at 42 As best shown in Fig. 10, the valves 3|, 32, 33 are connected by means of the flexible tubes 3la, 32a, 33a to pressure reducing valves 3|b, 32b, 33b. These reducing and regulating valves are supplied with compressed gas from a pressure main 3|c having a source of gas under pressure such as the pressure tank 3|d.

The valves 3|, 32, and 33 are normally open so that pressure of, for example, 60 to lbs. exist in cylinder A, 40 to -60 lbs. in cylinder B and 10 to 40 lbs. in cylinder C.

The structure of the valves 3|, 32 and 33 is best shown in Figs. 12 and 13. Fig. 12 shows the valve open in the position in which air is exhausted from the cylinders. Fig. 13 shows the valve closed in which position the pressure automatically controlled by the regulating valves 3|b, 32b, and 33b is permitted to flow to the respective cylinders.

Explaining the structure and operation of one of these relief valves, the valve, the casing of which is illustrated at 3| has an outlet p0I't3Ie, an inlet port 3|) and a pressure relief port 3| g. A valve stem 3|h has an intake valve disc 3li, and a release valve disc 3|7' which discs seat and close the ports 3| f and 3|g respectively. A spring 3| k urges the valve disc 3|z against its seat. A plunger 3|l has a rounded exposed end which abuts a set screw 3|m which extends through a pivoted arm 34, which carries on its free end a cam roller 3l0. A spring 3|p exerts a pull on the arm 3|n sufiicient to overcome the pressure of the spring 3|k and hold the inlet port 3| i normally open. When the roller 3| 0 engages the cam track I8 the arm 3|n is rocked thereby relieving the tension of the spring 3|p holding the inlet port 3lf open. The port 3|f is then closed by the compression spring 3|7c and at the same time the relief port 3| g is opened.

The valves 3|, 32 and 33 all have a similar construction and operate in the same manner.

The mechanism is shown in a position ready to start a forming operation in Figs. 1 and 10, in which the metal plate 43 to be formed is located on the top of the female die member 4. As the head I descends downwardly, an annular shearing edge 44, which forms part of an annular member 45, trims off the edges of the metal. Prior to the actual forming of the metal plate, the lower cylinder head 46 bears frictionally against the surface 43 of the sheet outside that which covers the opening 1, the pressure down wardly being controlled by the regulating valve 3|b and as stated, usually ranging from 60 to 100 lbs.

The frictional clamping of the lower surface of the head 46 is maintained against the metal by the air pressure in the compression cylinder A. This same pressure, until released, holds the head 22 back against the latch 31.

The first stage ofthe forming occurs when the head moves sufficiently far down to cause the male dies 24, 25 and 26 to be depressed within the first stage forming chamber, as indicated in Fig. 3. During this downward movement of the head carrying the telescoping male dies, the frictional retainment of the area of the sheet 43 around the die chamber opening caused by the air pressure in the cylinder A,- is sufiicient to permit the metal to be evenly drawn down into the first stage die chamber. When this stage is reached, the arm 34, which controls the air to the compression cylinder A is cut off and exhausted from the cylinder by contact with the cam track l8, as indicated in Fig. 3.

The second and third forming operations are carried out in a similar manner, and since the illustration in Fig. 4 shows the parts in the position after the third forming operation, this operation only will be described. It will be noted that during the second forming operation, the outwardly beveled lower edge of a the male die 24 frictionally clamps and retards the passage of the metal by engaging the formed sheet between its outwardly beveled edge and the inwardly extending annular ledge 8 of the female 'die.

Prior to the start of the third forming operation, the outwardly flaring lower edge of the male die 25 will bear against the inwardly inclined shoulder ill of the second stage die chamher. This will permit the metal to be drawn down in the third forming operation, so that it will flow evenly. The compression chamber C holds the die 25 in position during the third forming operation.

As the die- 26 reaches the lower limit of its stroke and before the air from the cylinder C has been cut of! and exhausted, the ram 21 descends within the female die l3 and completes the final forming of the metal. The head I is then moved upwardly, as illustrated, withdrawing the ram and male dies and an upward stroke of the ram l5, causes the ejection of the formed metal object in its final form.

During the operation the frictional clamping due to the pneumatic pressure causes suflicient heat to bring about an even flow of metal in the drawing operation. r

In Figs. 6 to 9 the form of the metal after each operation is shown. In'Fig. 6, the metal sheet 43 has been formed as shown at "a. This is the form of the metal after the first forming operation with the parts of the mechanism as shown in Fig. 3.. In Fig. 'I the metal is formed as indicated at "b. In Fig. 8 the metal is formed as indicated at c. If the parts illustrated in Fig. 4 were to be moved upwardly and the metal container were to be withdrawn from the female die chamber I I it would have the form illustrated at "c in Fig. 8. The final form of the container is shown at "at in Fig. 9.

I have illustrated the forming of a metal container of rectangular shape, this being one of the more diificult shapes to form but it will be apparent that by a change in shape of the dies other forms such as square. octagonal, and round may be made.

In the claims which follow I do not limit the application of the forming operation either to any particular shape or size nor do I limit its application to a forming operation of any definite number of steps such as the four forming steps described. Any multiple number of forming operations may be accomplished by utilizing the pneumatic clamping principle involved, and by my arrangement I am able to so regulate the air pressure in the respective cylinders that the desired frictional clamping pressure for successive draws may be obtained. Thus my arrangement provided for a nicety of drawing operations not possible in the constant and uniform hold-down arrangement of Schimmelbusch in his Patent No. 783,390.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. In sheet forming apparatus in which meta is formed, a female die having successive die chambers of decreasing cross dimensions and a male die comprising a series of telescoping male die elements each fitting within a successive die chamber during a forming operation therein, pneumatic means which may be regulated to a difierent pressure for each die for retaining each of said telescoping male die elements in frictional clamping engagement with metal being formed during the forming operation in the next successive die chamber, said pneumatic means comprising a series of cylinder heads within compression cylinders each cylinder head carrying a male die element, and means for releasing the pneumatic pressure within said cylinders during successive stages of the forming operations.

2. Sheet forming apparatus comprising a female die having a series of die chambers formed therein of decreasing cross dimensions, a frictional clamping member for retarding the metal of a sheet as it is drawn in said die chamber, regulatable pneumatic means for actuating said clamping member and a series of telescoping male dies for successively forming the metal of a sheet in said series of die chambers, said series of male dies being reciprocable through an opening in said clamping member, and independently regulatable and pneumatic means for actuating one of said male die members to cause it to effect a clamping pressure on a sheet being drawn during the reciprocation or another male die member through said first noted male die member.

JAMES L. AUBLE.

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