Method Of Shaping Sheet Material

Abstract

The subject matter concerns a method of shaping sheet material in the fabrication of articles therefrom having modified corner areas resulting from bending the sheet to a desired shape of the product, the sheet being relieved, that is, thinned down, prior to bending on the ultimate inside of the bend whereby the corresponding corner area at the apex of the angle is drawn in and sharp corners are avoided or suitably reduced.

Description

The invention concerns a method of shaping sheet material particularly directed to producing an indented corner. Under normal conditions of shaping by bending a sheet material a sharp corner area commonly results which in the further operations of fabricating the intended article may interfere with the automatic machine manipulations. Also such corner shapes often are undesirable in the final product from the standpoint of appearance and comfort in handling. Accordingly, various operations have been employed to reduce the corner area such as by machining off or coining or stamping down the external surface at the corner either prior to or after its formation. Such operations however usually complicate the fabricating operations and add to the overall cost and manufacturing steps.

The present invention provides a very effective and much simplified procedure for accomplishing the corner indentation. Basically, it embodies the step of relieving in advance the area at the eventual apex of the angle formed by the bend on the side which becomes the inside of the angle formed by the bending step. The operation of relieving the area may be any one of known mechanical steps such as by cutting away material at the critical area or by stamping or coining. As a result, the stresses produced by the bending are such as to cause the remaining thinner area to be automatically drawn in at the apex of the angle thereby indenting the corner below the normal outer surface of the sheet at that area.

The principles of the invention and the physical phenomena will be made more fully apparent from representative applications as described hereinafter and depicted in the drawings in which:

FIGS. 1a, 1b and 1c illustrate the basic features of the invention. FIG. 1a being a section of the original flat sheet material, FIG. 1b showing the material bent around the relieved area and FIG. 1c is a cross-sectional view taken on the plane I c - of FIG. 1b.

FIGS. 2a to 2d illustrate another application of the principles of the invention in which FIG. 2a is a section of the original sheet material, FIG. 2b shows the sheet is formed into a part having two angles, and FIGS. 2c and 2d are cross-sections taken on the planes II c and II d respectively of FIG. 2.

FIGS. 3a to 3c correspond to FIGS. 1a to 1c respectively and show a different form of relieved area.

FIG. 4a is a view in perspective of a shell for an injector blade dispenser embodying the features of the invention; and FIG. 4b is an end view thereof on an enlarged scale.

FIGS. 5a to 5c correspond to FIGS. 1a to 1c but include an opening through the sheet material in association with the relieved area.

FIGS. 6a to 6c likewise correspond to FIGS. 1a to 1c but illustrate a tapered form of relieved area.

Referring to FIGS. 1a to 1c which illustrate the basic features of the invention, FIG. 1a depicts a section of sheet material 10 having a relieved area 11 on one side, the area in this case being half moon shape. The relieved area may be formed in any suitable manner as by machining away the area or by coining or stamping. The method may be applied to any desired sheet material having for best results substantial ductility as, for example, a metal such as aluminum, iron or copper or alloys thereof. The sheet is bent into a desired angle needed for the ultimate product, FIG. 1b showing it bent 90.degree. into a right angle about an axis 12. The relieved area 11 corresponds to the compression side of the neutral axis 13 and the remaining area 14 at the apex of the angle comprises the tension area. As the plastic deformation occurs the tensed area 14, due to the resulting vector forces, displaces inward toward the bend axis as illustrated in FIG. 1b resulting in an indentation 15 extending around the apex of the angle. The indentation decreases progressively as the area 11 merges into the adjacent unrelieved areas of the sheet.

The precise final shape or result depends upon factors which may be varied such as the ductility of the material, the bend angle and the configuration of the relief, that is the depth, width and length. For purposes of description and understanding, it may be noted that the relief length in FIG. 1 is indicated by the dimension 16 and may be defined as the total distance of the relief along the bend axis, and the relief width may be defined as the sum of the distances at each side from the bend axis perpendicular to the axis indicated by the dimension 17 in FIG. 1a.

With respect to the depth of the relief, if the material has been relieved to or past the neutral axis, the remaining area 14 is completely under tension and if relieved only part of the distance to the neutral axis it is predominantly under tension.

In the application of the invention illustrated in FIGS. 2a to 2d, the relieved area 20 is more extended in width than in FIG. 1a and the sheet is bent at two areas of different angle resulting in the indented corner areas 21 and 22.

FIGS. 3a to 3c illustrate the invention in which the sheet 30 has the full basic material thickness at each side of the relieved area 31. In other words, the relieved area 31 is spaced entirely inwardly from the opposite edges 32 and 33 of the sheet 30 resulting in an intermediate indented area 34. Similarly to the effect produced in the preceding forms, the indented area reduces progressively as it merges into the adjacent portions of the sheet as indicated at 34a.

Thus far the disclosure has been directed to the general principles of the invention as an indication of a manner in which it may be applied in the fabrication of various articles. FIGS. 4a and 4b illustrate one practical application of the subject matter in the fabrication of a shell or casing for an injector blade dispenser. The shell 40 has corners 41 which are formed in the manner illustrated in general in FIGS. 1a to 1c. The method results in the avoidance or reduction of sharp or protruding corners as an advantage in the final product; and in the manufacturing process of shaping and loading the dispenser 40 it is of distinct advantage in eliminating interfering engagement or hang-up at stages in the shaping and handling and loading of the dispenser.

Various other applications of the invention may be employed. FIGS. 5a to 5c illustrate a sheet 50 having a relieved area 51 and an opening through the sheet material at 52 in a form in this case of a slot, the slot extending through the bend axis 53 at the apex. As a result, after bending, the indentation 54 at the corner is uniform because of the interruption at the opening 52 as distinguished from the progressive tapered draw-in shape shown in the previous examples.

FIGS. 6a to 6c illustrate the result with a tapered relief. In other words, the sheet 60 has a relief 61 which is tapered as indicated particularly in FIG. 6c at 62 which results in a tapered indentation 63 which is at a maximum at the extreme edge 64.

Various applications of the principles of the invention have been described above and illustrated in the drawings and it will be apparent that further variations may be resorted to dependent upon the circumstances and accordingly it is intended that all matter contained herein shall be interpreted as illustrative and not in a limiting sense.

Claims

What is claimed is:

1. A method of shaping sheet material comprising relieving the material at an area at one side of the sheet, and bending the sheet about an axis through said area with the area on the inside of the bend, thereby drawing in the sheet material at the apex of the angle formed by the bend.

2. A method of shaping sheet material in accordance with claim 1 in which the relieved area is at an edge of the sheet extending inwardly a substantial distance therefrom.

3. A method of shaping sheet material in accordance with claim 1 in which the relieved area is of limited width and located entirely within the edges of the sheet along said axis and the drawn in area is accordingly entirely within the edges of the sheet.

4. A method of shaping sheet material in accordance with claim 1 in which the drawn in area at the apex decreases progressively into the sheet as the relieved area merges into the unrelieved areas of the sheet.

5. A method of shaping sheet material in accordance with claim 1 in which an opening is preformed in the sheet at an edge of the relieved area extending through the apex of the angle and the drawn in area at the apex is substantially uniform in amount extending into said opening.

6. A method of shaping sheet material in accordance with claim 1 in which said material is of a character having substantial ductility.

7. A method of indenting inwardly the corner area of a bent sheet of material comprising relieving the material on one side of the sheet at an area to become said corner area, and bending the sheet through said relieved area with the area on the inside of the bend.