US2133445A - Method for cutting and forming sheet material - Google Patents

Description

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1 INVEA/of? HENRY. GUER/A/ ATTORNEY Oct. 18, 1938. H E GUERIN METHOD FOR CUTTING Patented Oct. 18, 1938 UNITED STATES METHOD FOR CUTTING AND FORLIING SHEET MATERIAL Henry E. Guerin, Los Angeles, Calif., as'signor to Douglas Aircraft Company, Inc., Santa Monica, Calif., a corporation of Delaware Application December '1, 1935, semi No.s3,346

11 claims. l(ci. 11a-51) My invention relates 'to a method for producing cut and formed articles from sheet material in a single operation, and the present invention constitutes a continuation in part of my c'opending application, Serial No. 39,696, tiled September 9, 1935, for Method and apparatus for cutting sheet metal, which issued into Letters Patent No. 2,055,077 on September 22, 1936. In my previous application above noted I disclose the manner of cutting blanks from sheet metal by the use of a simple cutting die in a press having a body of .yieldable plastic material, such as a rubber or ,f composition having rubbery qualities, and the subsequent forming of these blanks to desired crosssectional shape.

My invention also includes a method wherein sheet metal may be not only cut but also formed during the same operation so that when the invention is practiced a sheet of metal may be 20. placed in the apparatus of my invention, the apparatus operated, and an article of the desired size, shape, and configuration produced by such operation. In the performance of my invention, therefore, I may cut the sheet metal to a desired size and it may be formed or otherwise worked upon in other apparatus; I may in the practice of my invention cut the sheet metal to the desired conguration and then form it during the same operation or sequence of steps and thus produce the nished article; or in the performance of my method I may first form the sheet of metal to the desired shape and thereafter cut it to the desired size and configuration, thus producing the article of the desired shape; and also in the performance of my invention the forming and cutting steps may be simultaneously performed in order to produce articles of the desired size, shape, and conguration.

It is an object of my present invention to accomplish the cutting of the blank and the form, ing of the same to desired cross-sectional shape in a single operation in which a single die accomplishes both the cutting and the forming of the sheet material. Y

It is a further object of the invention to provide a method for producing formed articles from sheet material wherein pressure is applied to the sheet to move the same, wherein the movement of different parts of the sheet is limited or controlled in such a manner that the sheet will be deformed from its original cross-sectional shape to a desired cross-sectional shape, and wherein one part of the sheet is held against movement along a line of division so that the movement of the adjacent part of said sheet under said pressure will cause the sheet to be severed along the line of division.

It is a further object of the invention to provide a simple die member having a forming portion o0 provided with a shape or contour which is to be imparted to the sheet, and having a cutting edge so formed that the sheet will be cut along prescribed lines as the result of pressure oi.' the sheet against the die by the yieldable plastic material. In the preferred practice of the invention this 5 yieldable plastic material consists of a body of rubber which, when it is placed under pressure, will form itself around the die member in such a manner that a sheet of material, such for example as duralumin, placed between the body of 10 rubber and the die member will be forced against the die member under great pressure so that the sheet will assume the form of the die member and will be cut by the cutting edges of the die member.

In the practice of the invention the sequence of the steps of forming and cutting may vary considerably. For example, the initial movement of the sheet by the rubber material under compression may shape a part of the sheet and then 20 subsequent to this shaping of the sheet may produce the cutting action, or the\initial movement of the sheet with relationto the die member may result in the cutting of thesame and then the. formation. of the sheet to a desired cross section 25 by the pressing of the sheet against the surface of the forming portion of the die member; or, on the other hand, the cutting and shaping operations may be alternated; that is, the first movement of the sheet relative to the die by the rub- 30 ber material ,will cut one portion of the sheet, the second movement will shape a portion of the sheet, and the third movement will accomplishf,

another cutting operation.

It is another object of my invention topro- 35 vide a method by which sheet metal is formed and cut in which the sheet of metal is .gripped and secured against a die member by means of a body of flowable material in order that those portions 40 of the sheet which are to constitute the nished article will be protected from tensile and bending strains to which the surplus portion of the sheet is subjected during the subsequent cutting operation. 45

It is a still further object of my invention to provide a method in which the sheet of metal is first gripped by a body of iiowable material and is thereafter cut, and as a nal operation is formed to the desired shape. 50

AIt is another object of my inventionto provide a process in which the body of ilowable material is employed to first completely form thev sheet into the desired vshape and to thereafter separate the surplusage of the sheet in vorder that the 55 sheet will first be formed to the desired configuration and thereafter cut to the desired size.

Further objectsand advantages of the invention will be brought out in the following part of the specification.

Referring to the drawings, which are for i1- lustrative purposes only,

Fig. 1 is a fragmentary sectional view showing a portion of a press with a. die therein for practicing the invention in one of its embodiments.

Fig. 2 is a fragmentary plan view, to reduced scale, of the die used in Fig. 1.

Fig. 3 is a fragmentary perspective view showing the part produced by the Imeans shown in Fig. 1.

Fig. 4 is an enlarged cross-sectional view of another die which may be used in the practice of the invention.

Fig. 5 is a plan view of Fig. 4, to reduced scale.

Fig. 6 is a perspective-view showing the type of article which may be produced by the die shown in Fig. 4.

Fig. 7 is a cross section of another die wherein the cutting and shaping operations are alternated.

Fig. 8 is a cross-sectional view of another form of die embodying the invention, wherein the entire cutting operation is accomplished before the shaping operation. I

In Fig. 1 I show the bed I3 of a press Il having a head I2 to which a body I3 of yieldable plastic material I3a is secured. This body I3 is of a semi-fluid character found in a number of different substances, such, for example, as rubber which yields and likewise flows when a pressure is applied thereto, heavy tars which will likewise ow due to their semi-fluid character, and heavy paste or putty-like materials which have some resistance to deformation but due to their plasticity will deform or flow under pressure. Such materials can best be described as fluid-like or iiowable materials. In the preferred practice of the invention, however, the body of yieldable plastic material is a rubber or rubber compound; the characteristics, that is the resilience, of which may be selected in accordance with the type of sheet material to be operated upon.

The table I II has a side wall I4 extending around the periphery thereof for limiting the lateral expansion of the body I3 when the head I2 of the press II is forced toward the base or table I3. On the table I3 I show a forming member or die I5 comprising an elongated body I8 of suitable metal, such as tool steel which may be hardened after its formation. This body I6 has a plurality of relatively shallow depressions I1 in the upper face 20 thereof and a recess or opening I8 in the bottom of each depression I1 and preferably in centralized relation thereto. The upper end of each opening I8 is defined by a sharp annular edge or corner I 9 constituting a cutting edge, and within each of the openings I3 an electing member 2| in the form of a body of rubber may be placed. Around the periphery of -the upper face 23 is a rounded corner 22, and in the exterior side wall of the lbody Ii a cutting edge or shoulder 23 is formed, with an adjacent depression 24.

A sheet 25 of suitably ductile material is placed upon the die I5 in flat condition, as indicated by dotted lines 26. The head I2 is then lowered under pressure so that the yieldable plastic body I3 will engage the sheet 25 and press the same downwardly, with the result that the dotted line areas 21 over the recesses I1 will be deiiected downwardly into the recesses l1, and'u peripheral portions 23 and 23 will be swung downwardly over the corner 22 which, as previously explained, extends peripherally around the body I6. The portions of the sheet now lying across the openings I8 will be deflected downwardly by the yieldable material, as indicated by dotted lines 32, and when the downward deflection indicated at 3211s suillcient, the pressure of the yieldable material of the body I3 will cause the metal to part along the cutting edge I9 at the upper end of each opening I3 with the result that a severed disc 33 will be forced downwardly into the opening I3 as shown, leaving holes 34 in the sheet 25 concentric with the depressed portions 35 of the sheet 25 which have resulted from the forcing of the sheet into the depressions I1. It will be perceived that the sheet 25 has been first formed or bent into the depressions I1 and that this forming has been followed by the cutting out of circular areas or discs 33. The edge portions 23 and 29 of the sheet 25 are formed downwardly across the sides of the body I6, and then. due to the lateral flowing of the yieldable plastic material, or rubber, under the heavy pressure employed, the outer portions of the edges 23 and 23 are caused to part across the cutting edges 23 resulting from the forcing of the sheet into the depression 24 lying below the cutting edge or shoulder 23.

AOn the left-hand side of the body I3 of Fig. 1 I show a shoulder 31 below the depression 24 against which the outer portion 33 of the edge 23 is pressed by the yieldable material in a manner to grip the same. Below the cutting edge 23 the edge portion of the sheet 25 indicated at 23a is first deflected inwardly as indicated by dotted lines, and then further lateral movement of the yieldable material in rightward direction causes the .edge portion to be cut. At the right side of the body I6 I show how the depression 24 may be formed without the use of the shoulder 31, but with the bottom Wall 38 of the depression extending perpendicular to the lower face of the body I5. Where the peripheral cutting edge of the die is formed in this manner, the extreme edge portion of the plate 25 indicated by dotted lines 4I is first deflected inwardly into engagement at 42 with the bottom wall 33 of the recess 24, after which the cutting action taires place at the cutting edge 23, and the edge portion 4I is forced by the yieldable material I3a into the position in which it is shown by full lines 4Ia.

'I'he result of the operation previously described produces a formed article 43 shown in Figs. 1 and 3 and a residue or scrap consisting of the discs 33 and the severed peripheral edge of the original sheet 25 indicated by the numerals 33 and 4Ia in Fig. 1. The formed article 43 in the present instance may consist of a lightweight strut or structural member to be used in airplane construction, this member being lightened by the punching of holes 34 and strengthened by the formation of the depressed portions 35.

In Fig. 4 I show a practice of the invention wherein a sheet is cut before the forming operation. In this practice of the invention I employ the press I I in conjunction with a die 44 consistlng of a central circular block 45 having an upwardly and outwardly faced cutting edge 43, a forming block 41 disposed around the central body or cutting block 45, and an outer cutting block 43 disposed around but spaced from the member 41 and having an inwardly and upwardly faced cutting edge or shoulder 49. The inner portion of the forming block 41 is cut away to form a depression or recess 5I around the body 45 and adJacent the cutting edge 43 thereof,

there being a rounded annular corner or shoulder 52 at the upper edge of the wall portion of the member 41 defining the depression or recess Likewise. the forming block 41 has a peripheral rounded corner 53 lying in spaced rela-- tion to thecutting edge 48 of the outer cutting block 48. The members 45, 41, and 48 may be separately machined and mounted upon a supporting plate 54.`

In the practice of the invention here described, a sheet 55 is placed upon the upper face of the die 44 in such position that the edge portions 56 thereof will lie upon the upper faces 51 of the outer cutting block 48. When the table i8 and the head i2 of the press are moved relatively together or toward each other,- the yieldable material |3a: will force the sheet 55 downwardly, and, as indicated by dotted lines 58 and 58, will initially depress those portions of the sheet 55 lying over the recess 5| and over the recess 6| between the members 41 and, 48. At this time the pressure of the yieldable ,material |3a will grip the sheet tightly against the upper face 51 of the block 48, the upper face 62 of the forming block 41, and the upper face 63 of the central body 45, thereby preventing lateral movement or displacement of those portions of the sheet engaging such upper faces of the die 44. After the initial downward deflection of the unsupported portions of the sheet 55, indicated by dotted lines 58 and 58, the yieldable material |3a will cause the severing of the sheet along the cutting edges 46 and 48. In other words, the yieldable material |3a in moving downwardly relative to the cutting edges will have a cutting effect. The subsequent downward movement of the yieldable material |3a into the recesses 5| and 6| will bend the portions 58 and 58 downwardly over the rounded corners y52 and 53 into engagement with the wall of the forming member 41, as indicated in full lines 58a and 58a. The operation above described results in the production of a formed article 62a, such as shown in Figs. 4 and 6, having an opening 63a and a flange 68, and scrap consisting of a centrai disc 64 and the outer edge portion 56 of the original sheet 55.

Also, in the practice of tlie invention, it is conceived that cutting and forming may be accomplished simultaneously and also in an alternating manner. For example, in Fig. '1 I show a die having a forming body 18 mounted on a plate 1|, this body 18 having a depression 12 and a central opening 13 extending downwardly from the bottom of the depression 12'. Likewise,

. the body 18 may have a groove 14 in the upper face thereof around the depression 12. Mollnted on the plate 1| is an outer cutting block 15 separated from the body 18 by a recess 16 and having an inwardly faced cutting edge 11. A plate v18 placed upon the upper face of the die shown in Fig. '7 and forced downwardly by means of the body I3 of yieldable material |3a will first have portions thereof deflected downwardly into the recesses 12 and 16 as indicated by dotted lines 18 and 8|, and at the same time a portion of the sheet 18 may be deflected into the channel 14 so as to form a beadr 82. Further downward movement of the body of yieldable material |3a will cause the 'sheet to shear at the cutting edge 11 and will cause a further deflection of the central portion of the sheet into the recess 12 -until the portions 8|a and 83 of the sheet are forced into tight engagement with'the corresponding surfaces of the body 18, after which there will be a cutting t the cutting edge 85 formed in the body 18 at t; e upper end of the opening 13 so that a disc 86 will be severed from the sheet 18 and will drop into the opening 13 which is preferably expanded downwardly to permit the disc 86 to drop freely through the aligned opening 81 of the plate 1| when the die is lifted from the table of the press It will be recognized that in the practice of the invention the actions of cutting and forming are nearly instantaneous so that it is difllcult .to state in some instances which of the acts is accomplished first.

In Fig. 8 I show a die 88 having an annular channel 8| cut in the upper face thereof so as to leave a central upstanding wall 82 having a peripheral cutting edge 83 and an outer upstanding wall 84 having an inner cutting edge 85. The bottom wall 86 of the depression 8| may be suitably contoured', as by the formation of channels 81 and 88, to a form which is desired to be imparted to that portion of a metal sheet which is forced into the channel 8|. In the use of the die of Fig. 8 a plate 88 is first placed upon the upper face-of the die 88, and the body I3 of "yieldable material |3a is then forced downwardly, deecting the unsupported portion |88 of the plate 88 into the channel 8| through a position indicated by dotted lines ,|8| and finally into a position against the bottom wall 86 of the channel 8|, as indicated in full lines |88a. When the unsupported portion |88 is in approximately the position indicated by dotted lines |8I, a cutting action will take place at the cutting edges 83 and 85, and the ring of sheet metal thus formed will move downwardly into engagement `with the bottom wall 86 of the depression 8|,

after which the yieldable material 3a will deform the metal ring into the channels 81 and 88, thereby producing a formed metal article such as indicated by the full lines |88a.

In the foregoing detailed description of my invention- I have described various forms of my invention capable of producing satisfactory results. It should be understood, however, that the forms of my invention illustrated herein have been chosen merely for the purpose of teaching those skilled in the art as to how my invention may be practiced. Various modifications and alterations may be made not only in the apparatuswhich I have illustrated and described but also in the method which has been disclosed herein. In view of these facts I do not wish my invention to be narrowly construed so that it will be limited to the precise method and apparatus disclosed herein, but wish my invention to be broadly construed so as to include all methods and apparatus which come within the broad principles and scope of my invention, which invention is broadly defined by the claims appended hereto.

I claim as my invention:

l. A method of cutting and shaping sheet metal, including: placing a sheet of metal over a die having a top wall, a side wall, a rounded corner between said top wall and side wall, said side wall comprising an upper sheet-engaging portion, a shoulder extending inwardly from the lower end of said portion, said sheet engaging portion andsaid shoulder merging in a cutting edge spaced a desired distance below said top wall, and a second sheet-engaging portion extending downwardly from said shoulder; applying pressure to said sheet of metal through a flowable material to cause a portion of said sheet to be bent to conform to the shape of said rounded corner, to hold said sheet of metal against said sheet engaging portions on opposite sides of said cutting edge, and to cause said metal to part along said cutting edge.

2. A method ofhcutfing and shaping sheet metal, including: placing a sheet of metal over a die having a top wall, an exterior side wall, a rounded corner joining said top wall with said side wall, said side wall being provided with a cutting edge spaced. a desired distance below said top wall and with sheet-engaging portions above and below said cutting edge; applying pressure to said sheet of metal through a flowable material to cause a portion of said sheet to be bent to conform to the shape of said rounded corner, to hold said sheet of metal against said sheet-engaging portions, and to cause said metal to part along said cutting edge.

3. A method of cutting and shaping sheet metal, including: placing a sheet of metal over a die having `a top wall, a side wall, a portion of a desired shape joining said top wall with said side wall, said side wall being provided with offset sheet-engaging portions and a cutting edge intermediate said sheet-engaging portions, applying pressure to said sheet of metal through a fiowable material to cause a portion of said sheet to be bent to conform in shape to said portion of desired shape, to hold said sheet of metal against said offset sheet-engaging portions, and to cause said metal to part along said cutting edge.

4. A method of cutting and shaping sheet metal, including: placing a sheet of metal over a die having a top wall, exterior side walls, a portion of a desired shape connecting said top wall with each of said side walls, each of said side walls being provided with offset sheet-engaging portions and a cutting edge between said sheetengaging portions; applying pressure to said sheet of metal through a owable material to cause said sheet to be bent to conform in shape to said portions of desired shape, to hold said sheet of metal against said offset sheet-engaging portions and to cause said metal to part alongsaid cutting edges.

5. A method of cutting and shaping sheet metal, including: placing a sheet of metal over a die having a top wall, an exterior side wall, a rounded corner connecting said top wall and said side wall, said side wall being provided with a cutting edge, a sheet-engaging portion above said cutting edge, and a sheet-engaging shoulder below and spaced from said cutting edge; and applying pressure to said sheet of metal through a flowable material to cause a portion of said sheet to be bent to conform to the shape of said rounded corner, to hold said sheet of metal against said sheet-engaging portion and sheet-engaging shoulder, and to cause said metal to part along said cutting edge.

6. A method of cutting andv shaping sheet metal, including: placing a sheet of metal over a die having a top surface with a shallow depression of a desired shape formed therein, and an opening in the bottom of said depression, the upper edge of said opening being defined by a cutting edge; and applying pressure to said sheet of mefal through a owable material to hold said sheet against said top surface, to cause the metal overlying said depression to conform to the shape of said depression, and to cause said metal to part along said cutting edge.

7. A method of cutting and shaping sheet metal, comprising: placing a sheet of metal over a die having a top surface with a shallow depression of a desired shape formed therein, an opening in the bottom of said depression, the upper edge of said opening being defined by a cutting edge, and an ejecting member in said 5 opening; applying pressure to said sheet of metal through a flowable material to hold said sheet ,against said top surface, to cause the metal overlying said depression to conform to the shape of said depression and then part along said cutting edge, forcing the severed portion o! said sheet into said opening; and then relieving the pressure applied by said flowable material to permit said ejecting member to eject said severed portion.

8. A method of cutting and shaping sheet metal l5 including: placing a sheet of metal over a die having a top wall and an exterior side wall with a rounded comer between said top wall and side wall,

said top wall having a shallow depression of a desired shape formed therein and an opening in the bottom of said depression, the upper edge of said opening being defined by a cutting edge, said side wall being provided with sheet-engaging portions and a cutting edge intermediate said sheetengaging portions; and applying pressure to the sheet of metal through a flowable material to press said sheet against said die to cause the same to conform to the shape of said depression and said rounded corner and to be severed along the cutting edges of said top and side walls. 9. A method of cutting and shaping sheet metal, including: placing a sheet of metal over a die having a central cutting block having a periphleral cutting edge, and a forming block having a depression of a desired shapedisposed around said central cutting block; applying pressure to said sheet of metal through a fiowable medium to grip said sheet upon opposite sides of the cutting edge of said cutting block, and applying additional pressure to said sheet through said flowable medium to cause said sheet to be severed along said cutting edge and to cause said sheet to conform El) tllgie shape of the depression of said forming l 1o. A method of cutting and shaping sheet 45 metal, including: placing a sheet of metal over a die having a top wall provided with a shallow recess having side and bottom walls of a desired, shape and a part projecting above the plane of said bottom wall and terminating in a cutting 5 edge; vapplying pressure to said sheet of metal through a flowable medium to grip said sheet against said top wall and against the top of said projecting part, and applying additional pressure to said sheet through said nowable medium to cause said sheet to be severed along said cutting edge and to cause said sheet to conform to the shape of said shallow recess.

11. A method of cutting and shaping sheet metal, including: placing a sheet of metal over a die member having a recess formed in a top wall thereof, said recess having side walls which terminate in cutting edges and having a bottom wall contoured to impart a desired shape to that portion of a sheet of metal which is severed by said cutting edges and is forced into said recess; and applying pressure to said sheet of metal through a flowable material to grip said sheet against said top wall and to rst cause the metal to part along said cutting edge and to thereafter cause the severed portion of the metal to be forced into said recess and to conform to the shape of the bottom of said recess.

HENRY E. GUERIN. 7s

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