US2055077A

US2055077A - Method and apparatus for cutting sheet metal

Info

Publication number: US2055077A
Application number: US39696A
Authority: US
Inventors: Henry E Guerin
Original assignee: Douglas Aircraft Co Inc
Current assignee: Douglas Aircraft Co Inc
Priority date: 1935-09-09
Filing date: 1935-09-09
Publication date: 1936-09-22
Anticipated expiration: 1953-09-22

Description

H. E. UERIN I 2,055,077.

Sept. 22, 1936.

METHOD AND APPARATUS FOR CUTTING SHEET METAL Filed Sept.' 9, 1935 2 Sheets-Sheet 1 uw/f/vroe/ f/E/veY 5 fiuzre/N ATTOQNE K Sept. 22, 1936. H, Rm 2,055,077

I I METHOD AND APPARATUS FOR CUTTING SHEET METAL H I Filedisept. 9, 1935 2 Sheets-Sheet w A 4 27 v 4/ 10 .411 27 A 22 43 ii 3 5 20 1;

ATTOENEK Patented Sept. 22, 1936 UNITED STATES PATENT OFFICE METHOD AND APPARATUS FOR CUTTING SHEET METAL Application September 9,1935, Serial No. 39,696

17 Claims. (Cl. 16417) My invention relates to a method and apparatus for cutting blanks from sheet material and forming the same to final shape.

It is an object of the invention to provide a method and apparatus of simple and economical character wherein sheet material may be cut mechanically to form a blank of desired shape and then formed to give a desired sectional configuration, it being an especial feature of the invention that it avoids the necessity of making companion punch and die parts which, even in their simplest form, involve a relatively large amount of labor and expense.

It is a further object of the invention to provide a method and apparatus of the above character in which, instead of relatively costly companion punch and die members, simple blocks or bodies are used for both cutting and forming operations on sheet metal, and it is a further object to provide, for use with these blocks, a means for applying to the sheet metal, which is placed in cooperating relation to the blocks, a body of resilient substance adapted to conform under pressure to the shape or contour of the blocks and to apply to the sheet metal ample pressure for performance of the operations to be made thereon either for the purpose of cutting or forming the sheet metal.

It is a further object of the invention to provide a simple and novel press in which the cutting or forming blocks may be placed and used for performing the various operations on the sheet metal, without the necessity ofsecuring these blocks or of aligning the same with cooperating die parts.

It is a further object of the invention to provide a method of cutting sheet metal, in which the use of high priced companion punch and die members is avoided. In the present invention, as hereinabove indicated, the method is practiced by the use of simple cutting and forming blocks. The invention is of especial utility in those industries in which relatively small quantities of punched and formed sheet metal Parts are made, and wherein the relatively small number of such parts does not warrant the relatively great expense of making complementary punches and dies. For example, in the manufacture of airplanes, various sizes and shapes of sheet metal parts are used, but it is very rare that a large quantity of any one of the punched and formed sheet metal parts is made, this being due in part to the fact that the number of airplanes of each type made and sold is not very large and that there is a constant change in design and size of the parts used. In my present invention the cutting of forming blocks may be cheaply made and may be immediately put into use for the purpose of manufacturing the desired sheet metal parts. These cutting and forming blocks are of such character that they may be machined from flat steel plate, and are of such character that they may be laid upon the bed of the forming press without the need for securing elements or the exercise of skill as in the mounting of punches and dies in ordinary punch presses.

It is a further object of the invention to provide a method and apparatus for cutting and forming parts from sheet metal, wherein the design of the manufactured parts will not be influenced to such a great extent as heretofore by expediency in the making of punches and dies for the parts to be formed.

In the old process of shearing and forming parts from sheet metal, designs of the parts were in many instances controlled by the desire to keep the dies in as simple form as possible. For example, holes punched in the parts for the purpose of lightening the same were in the most part made round, since this involves the least expensive type of machining operation on the punch and die. My invention, however, makes it possible to cheaply use more complicated contours and to make the lightening holes in the sheet metal parts of any desired shape.

A further object of the invention is to provide a method and apparatus of the above character which will lend itself to the ready forming of beads or channels in parts, such as panels formed of sheet metal, so as to stiffen the same against buckling and vibration, this type of stiffening means being much less expensive than the riveting onto the panel or part of supplementary reinforcing parts, such as metal strips or angles.

- This is very important in the manufacture of parts which are to be used in the construction of airplanes, since in this form of construction parts having the same strength and stiifness as those originally reinforced by the application of stiffeners to the faces thereof can be now made much lighter so that a great saving in weight in the finished airplane is accomplished. In addition to lightening the structure, the facility with which complete metal parts are formed from a single sheet of metal contributes to other savings in production, labor, and cost. The decrease in the number of parts, decrease in time spent on computation and design, and the decrease in the amount of drafting to be done constitute an important saving which my present invention makes possible.

Further objects and advantages of the invention will be made evident throughout the following part of the specification.

Referring to the drawings, which are for illustrative purposes only,

Fig. 1 is a vertically sectioned view showing a simple and preferred form of apparatus wherein my new method may be practiced.

Fig. 2 is a plan view of the table of the device shown in Fig. 1.

Fig. 3 is a perspective view of a cutting block of a type to be used for the cutting of a blank for an airplane rib.

Fig. 4 is a schematic view showing the shearing block on the table of the press with a piece of sheet metal thereon prior to the lowering of the head of the press.

Fig. 5 is a view showing the second step or action in the cutting of the metal plate.

Fig. 6 is an enlarged fragmentary view for illustrating the manner in which forces are applied in the cutting operation.

Fig. 7 is a view showing the third or final step in the cutting of the metal plate to form a blank.

Fig. 8 is a fragmentary plan view taken as indicated by the arrow 8 of Fig. 7 to show a portion of the cut blank and the position of a guide pin which forms a guide opening in the blank.

Fig. 9 is an enlarged fragmentary cross section taken as indicated by the line 9--9 of Fig. 8.

Fig. 10 is a view similar in character to Fig. 1, but showing a forming block on the table of the press with the previously cut sheet metal blank thereon.

Fig. 11 is an enlarged plan view taken as indicated by the arrow ll of Fig. 10.

Fig. 12 is a view showing the second step in the forming of the metal blank over the forming block.

Fig. 13 is a view showing the forming operation completed.

Fig. 14 is a perspective view of the completed formed sheet metal rib having utility in the construction of an airplane wing:

In the apparatus which I have shown in Figs. 1 and 2 I employ two cooperating parts 20 and 2| which are adapted to be moved relatively together and apart under pressure to accomplish results which will be hereinafter described. The member 20 may be considered a support or table. and the member 2| may be termed a head which moves relative to the table 20. Supported by the table 20 are a plurality of shaping

blocks

22, 23, and 24. Although these blocks may be integrally formed with the table 20, it is preferred that they be made separately and that in the ordinary use thereof may be merely laid upon the upper face 25 of the table 20 without the necessity for use of securing means such as bolts or screws. The

blocks

22, 23, and 24 are broadly designated by the term shaping blocks, but specifically the block 22 is a. cutting block, the block 23 is a forming block, and the blocks 24 may be either cutting or forming blocks, as desired. From the foregoing it will be perceived that the use of the term shaping relates to the idea of cutting the edges of the plate to a desired contour and also bending the plate, as by the formation of ribs, beads, or flanges, to change the cross-sectional shape thereof.

Secured to the lower face 25 of the head 2| is a fiat layer or body 21. of a yieldable resilient or semi-fluid material which is best tharacterized by the terms "rubbery, "fluid-like or "flowable. This wall or body 21 is preferably made of a rubber or rubber compound, but may be of synthetic composition having rubbery characteristics such as resilience and the tendency to deform in a manner to surround a body against whieh'it is pressed. When the head 2| and the table 20 are moved relatively together, as by the lowering of the head 2|, the yieldable rubbery material of the wall 21 is forced against the

blocks

22, 23, and 24 and against the exposed upper face of the table 20, and when suflicient pressure is applied, the rubbery material conforms itself to the external surfaces of the

blocks

22, 23, and 24 or the metal sheets which are placed upon and shaped by the blocks. To constrain the rubber wall 21 from lateral expansion when it is under vertical pressure, a peripheral wall 28 is provided, this wall being preferably secured to the head 2| and being of such size that it will pass downwardly along the side faces 23 of the table 20 when the head 2| is lowered, the result being that the rubber wall 21 is contained within a completely closed space prior to and during the time the rubber wall 21 is in engagement with the

blocks

22, 23, and 24 and the upper face 25 of the table 20.

In Fig. 3 I show a perspective view of the cutting block 22 which is intended for the cutting of a sheet of metal so as to form a blank which may be further formed by the bending of the edges thereof so as to produce flanges, the final product in this instance being a formed metal rib 3| for use in the wing of an airplane. The block 22 comprises a flat body 32 of metal, such, for example, as tool steel, which body 32 may be cut from a fiat plate. The body 32 is provided with an external or peripheral vertical face 33 which meets the upper face 34 of the body 32 at an upwardly and outwardly disposed corner or edge 35 which is relatively sharp, or, in other words, is sufflciently sharp to cause the desired cutting operation. This cutting edge 35 has the contour of the periphery of the blank which is to be cut from a sheet of metal. The body 32 may be otherwise machined so as to provide openlugs 36 which are defined by vertical walls 31 which meet with the upper face 34 of the body 32 so as to form cutting edges 38.

The cutting block 22 may be very economically formed, since it is merely cut from a fiat plate, and the openings 36 therein may be made of any desired shape without great additional cost over the cost .of forming simple circular holes. As shown in Fig. 3, these openings 36 may be made oval or rectangular, or a composition of oval and rectangular, as shown at 39 in Fig. 3.

The process of cutting the blank from sheet metal is carried on as follows. The cutting block 22 is laid upon the upper face 25 of the table 20, as indicated in the schematic diagram, Fig. 4, and a metal sheet 4| is placed on the upper sur face thereof. This sheet 4| is of such size that it will have edges 42 which project beyond the peripheral cutting edge 35 of the cutting block 22 such distance that when the downward movement of the rubbery wall 21 bends these edges downwardly into engagement with the upper face 25 of the table 20, as shown in Fig. 5, the extreme or peripheral portions 43 of the edges 42 will be gripped or clamped between the portions 44 of the wall 21 and the face 25 of the table 20, as best shown in Fig. 6. At the same time, the portions 45 of the wall 21 over each opening 31 or 39 of the block 22 will force the unsupported portions 41 of the sheet 4| downwardly into engagement with 'the face 25 of the table 23 as shown in Fig. 5.

Then, as best illustrated in Fig. 6, the increase of compression in the rubbery material of the wall 21 'will be applied to the unsupported portio'n'sof the sheet 4i adjacent the cutting edges 35'and 38 of the block 22, as indicated by arrows 43 in Fig. 6. This compression causes tension in the unsupported portion of the sheet and a concentration of forces at the plane A-,-A which finally results in the parting of the sheet 4| at the cutting edges of the cutting block 22 when the downward pressure exerted by the rubbery material becomes suflicient to accomplish this result. When this occurs, the scrap or excess metal is forced downwardly against the face 25 of the table 20, as indicated at 53 in Fig. 'l, and the sheet metal blank 5| which has been formed by the cutting operation resides on the upper face of the block 22, this blank having the same shape as the upper face 34 of the block 22. It will of course be understood that the above steps illustrated in Figs. 5, 6, and 7 occur in such rapid succession as to be substantially instantaneous.

In the preferred practice of the invention a pair of guide pins 53 are employed in upwardly projecting relation on the cutting block 22, and a. similar pair of pins are projected upwardly from the face of the forming block 23. In the first instance the guide pins 53 of the cutting block 22 engage openings in the metal sheet 4i and prevent any lateral slippage thereof relative to the cutting block 22, and in the second instance the guide pins 53 of the forming block 23 engage the openings 54 of the blank 5i, as shown in Fig. 11, so as to hold this blank 5| in centralized relation to the forming block 23. The forming block 23 shown in Figs. 10 to 14 inclusive is made of such size relative to the cutting block 22 and to'the blank 5| formed by the cutting block that edges 55 and 56 of the blank 5i will project over the peripheral edges 51 of the body 23 and over the edges 58 of openings 31 therein. The extension of the

edge portions

55 and 56 of the blank 5i, as shown in Figs. 10 and 11, corresponds to the width of the flanges to be formed on the blank 5i around the periphery thereof and around the openings thereof.

The upper edges 60 and GI formed at the periphery and around the openings of the forming block 23 are rounded off, and when the resilient or yieldabie' wall 21 is forced downwardly as the result of the downward movement of the head 2i, the pressure of the rubbery material will bend the

edges

55 and 56, as shown in Fig. 12, downwardly over the rounded edges and BI, and as the pressure in the wall 21 is increased, the tendency for the rubbery material to conform to the exterior of the block 23 will, as shown in Fig. 13, force the'edges 55 and 55 tightly against the vertical faces 51 and 53 of the body 23. In this manner the

edges

55 and 55 are brought into positions in which they will form flanges around the edges of the blank 5|, thereby transforming the blank 5i into a finished wing rib 3| such as shown in Fig, 14.

If stiffening ribs are required in the formed metal plate, or in a flat metal plate, the block, such as either the

block

22 or 23, used in shaping such plate may have suitable walls formed thereon against which the rubbery material of the wall 21 will conform or shape the sheet metal. For example, in Figs. 10 to .13 inclusive, 1 have shown grooves 64 in the upper face of the forming block 23. When compression is applied to the rubbery material of the wall 21, the sheet metal of the blank 5| is forced into these grooves 54 so as to form beads or ribs in the otherwise flat wall portion of the wing rib 3i.

Although I have herein shown and described my invention in simple and practical form, it is recognized that certain parts or elements thereof are representative of other parts, elements, or mechanisms which may be employed in substantially the same manner to accomplish substantially the same results; therefore, it is to be understood that the invention is not to be limited to the details disclosed herein but is to be accorded the full scope of the following claims.

I claim as my invention:

1. A device of the character described, including: a table member having a cutting block thereon, said block comprising a wall of hard material having cutting shoulders of relative sharpness; a head carrying a body of fluid-like material; means for forcing said head and said table member together with sufficient pressure to deform said fluid-like material around said block; and a peripheral wall around the edge portions of said body of fluid-like material to prevent spreading of said body of fluid-like material.

2. A device of the character described. including: a table member having a receiving surface; a cutting block adapted to be placed on said receiving surface of said table member; a head member adapted to be moved toward and away from said table member; a body of fluid-like material of substantially greater thickness than said cutting block adapted to be forced toward said receiving surface of said table member by said head member; means for forcing said head member and said table member together; and a peripheral wall to constrain said body of fluidlike material against lateral expansion.

3. A method of cutting sheet material, comprising:' placing a sheet of said material on a block having a cutting edge formed by top and side faces thereof; and forcing a body of rubbery material against saidsheet undersuch high' pressure as to force said rubbery material in a direction across the side faces of said block.

4. A method of cutting sheet metal, including: deforming the sheet of metal over a cutting edge; holding the edge portion of said sheet of metal from moving inward toward said cutting edge; and yieldably applying pressure through a flowable material to said sheet of metal adjacent said cutting edge to cause the metal to part therealong.

5. A method of cutting sheet metal, including: deforming the sheet of metal over a cutting edge; holding the edge portion of said sheet of metal from moving inwardly toward said cutting edge; and yieldably applying pressure through a flowable material to said sheet of metal between said cutting edge and the point of holding of the edge portion of said sheet of metal to cause the metal to part therealong.

6. A method of cutting sheet material comprising placing on a cutting block having a cutting edge formed between a top wall and a side wall thereof a sheet of such size that it will project beyond said cutting edge to a position adjacent a surface spaced from said cutting edge, moving a wall of fluid-like material toward said block so as to press said sheet against said top wall and said surface to grip said sheet, and continuing the movement-and pressure of said fluid-like material to move the portion of said sheet between said surface and said cutting edge relative to said cutting edge and thereby cause the same to part from the main portion of said sheet.

7 A method of cutting sheet material including placing the sheet material on a cutting block having a cutting edge so that a portion of said sheet extends beyond said cutting edge into position to engage a surface spaced from said cutting edge, applying a body of fluid-like material against the sheet material to force it against the cutting block and the extending portion thereof against said surface to hold thesheet material, and applying additional pressure against the body of fluid-like material to build up suflicient pressure on the sheet material between said surface and the cutting edge to cause the sheet material to part along the cutting edge.

8. A method of cutting sheet metal which comprises confining in a relatively closed space a die member having a cutting edge, a relatively thick body of fluid-like material, and a sheet of metal to be cut placed between said die member and said fluid-like material and having a portion extending outwardly from said cutting edge into position to engage a surface spaced from said cutting edge; and forcibly reducing the size of said space so as to cause said body of fluidlike material to grip said sheet of metal on opposite sides of said cutting edge to restrain lateral movement of said sheet of metal and to thereafter apply sufiicient pressure to the sheet of metal between said cutting edge and said surface to cause said sheet of metal to part along said cutting edge.

9. A method of cutting sheet metal which comprises confining in a relatively closed space a die member having a cutting edge, a relatively thick body of fluid-like material, and a sheet of metal to be cut placed between said die member and said fluid-like material and having a portion extending outwardly from said cutting edge into position to engage a surface spaced from said cutting edge; and forcibly reducing the size of said space so as to cause said body of fluidlike material to grip said sheet of metal on opposite sides of said cutting edge to restrain lateral movement of said sheet of metal and to thereafter produce tension in the portion of said sheet of metal extending outwardly from said cutting edge, as a result of the confining of said body of said fluid-like material adjacent thereto, suificient to cause said sheet of metal to part along said cutting edge.

10. A method of cutting sheet metal which comprisesconfining in a relatively closed space a die member having a cutting edge, a relatively thick body of flowable material, and a sheet of metal to be cut placed between said die member and said fiowable material and having a portion extending outwardly from said cutting edge into position to engage a surface spaced from said cutting edge; and forcibly reducing the size of said space so as to cause said body of fiowable material to grip said sheet of metal on opposite sides of said cutting edge to prevent lateral movement of said sheet of metal and to thereafter produce a concentration of forces along the said cutting edge, as a result of the confining of said body of flowable material ad acent thereto, sumcient to cause said sheet of metal to part along said cutting edge.

11. A method of cutting sheet metal including holding said sheet of metal on opposite sides of a cutting edge so that said sheet metal is held at a position spaced from said cutting edge on at least one side of said cutting edge, and forcing a body of fluid-like material against said sheet of metal adjacent said cuttting edge to place the adjacent portion of said sheet of metal under sufiicient tension to cause the same to part along said cutting edge.

12. A method of cutting sheet metal including holding said sheet of metal on opposite sides of a cutting edge to form a pocket adjacent said cutting edge, and yieldably forcing a part of said sheet of metal into said pocket to place the adjacent portion of said sheet of metal under sufficient tension to cause the same to part along said cutting edge.

13. A method of cutting sheet metal including pressing a body of fluid-like material against said sheet metal to hold the same on opposite sides of a cutting edge so that the metal is held at a place spaced from said cutting edge on at least one side of said cutting edge, and applying additional pressure to said body of fluid-like material to produce sufficient unbalance of pressure between the places of holding of said sheet metal to place the adjacent portion of said sheet of metal under suificient tension to cause the same to part along said cutting edge.

14. A method of cutting sheet metal including holding said sheet metal between relatively rigid means having a pocket adjacent a cutting edge and a body of fluid-like material, and applying suflicient pressure to said body of fluid-like material to force a part of said sheet metal into said pocket to place the adjacent portion of said sheet of metal under sufficient tension to cause the same to part along said cutting edge.

15. A method of cutting sheet metal including holding said sheet of metal on opposite sides of an adjacent cutting edge and pocket, and creating suilicient unbalance of pressure on .said sheet of metal at said pocket to force a part of said sheet of metal into said pocket to place the adjacent portion of said sheet of metal under sufiicient tension to cause the same to part along said cutting edge.

16. A method of cutting sheet metal including forcing a body of fluid-like material against a sheet of said metal positioned to engage a cutting edge and a surface spaced therefrom to hold the same against lateral movement, and applying additional pressure to said body of fluid-like material to produce sufficient unbalance of pressure on said sheet between the cutting edge and said surface to bend the adjacent portion of said sheet of metal and to place the same under sufflcient tension to cause the same to part along said cutting edge.

17. A method of cutting sheet metal which comprises forcing a confined body of flowable material against a piece of said sheet metal so as to force said sheet metal against a cutting edge having surfaces on opposite sides thereof, at least one of which is spaced from said cutting edge to form a pocket adjacent said cutting edge, and applying suificient additional force to said confined body of flowable material to force a portion of said sheet metal into said pocket and cause the same to part along said cutting edge.

HENRY E. GUERIN.