GB1577853A - Metal sheet having a circular screw-receiving aperture - Google Patents

Description

(54) METAL SHEET HAVING A CIRCULAR SCREW-RECEIVING APERTURE (71) We, A. RAYMOND, a Kommanditgesellschaft organised and existing under the laws of the Federal Republic of Germany of Teichstrasse 57, D-7850 Loerrach, Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a metal sheet being a circular screw receiving aperture.

If a sheet metal screw is to be screwed into an aperture of a metal sheet, then the edge of the aperture must be helical corresponding in pitch to the screw thread pitch, so that the metal sheet must be made thicker than the thread pitch. The shape can only be obtained by deforming the metal sheet around the aperture.

A type of deformation known and used for this purpose comprises a conical protruberance pressed out of the sheet concentrically to the aperture.

This known sheet metal screw thread is used where the spatial conditions of the sheet blank are not too severely restricted for using this thread type. Due to the pressing out of the thread form, the sheet metal portions are deformed to a greater or lesser extent around the aperture, so that in the case of narrow width sheet metal blanks, such as for example strips or webs, sheet metal screw threads of this type become virtually un usable.

Accordingly the present invention provides a metal sheet having a circular aperture to receive a screw, wherein an annular area surrounding the aperture is divided by a radial cut and the edges of the cut are separated by pressing the annular area out from the sheet in opposite directions in either side of the cut by equal amounts, so that the edges of the cut are respectively equally inclined in opposite directions to the sheet and the edge of the aperture forms a helix for engaging the thread of the screw.

The helix piie;n in the metal sheet is fPlus 'impressed half to one side and half to the 'other side of the sheet, and is distributed over a circumference substantially of 360 degrees.

Due to the limited space requirements, such a sheet metal screw receiving aperture can be used with particular advantege in narrow width sheet metal webs. However, it can also advantageously be used at joints where it is important to be able to fix or screw the sheet metal screw into the thread impression from either side.

The invention is explained hereinafter with reference to embodiments described with reference to the accompanying drawings, wherein: Figure 1 is a side elevation of a sheet metal strip with a helix for engaging a thread of a screw, according to the invention, Figure 2 is a plan view of the sheet metal strip of Figure 1, Figure 3 shows an embodiment of the invention applied to two narrow sheet metal webs, connected at an angle to a component, with a sheet metal screw, and Figure 4 is a section on the lines C-D in Figure 3 on an enlarged scale.

Figures 1 and 2 of the accompanying drawings show a narrow width thick strip of sheet metal 2 having a circular aperture therein in the form of a helix 1 to receive a screw. This helix or thread 1 is formed by dividing an annular area surrounding the aperture, by a radial cut (Figure 2) and pressing the metal of the annular area on opposite sides of the cut, out from the strip of sheet metal 2 in opposite directions by equal amounts. Thus, as shown in Figure 1, the edges of the cut are respectively equally inclined in opposite directions to the strip 2 and the edge of the aperture forms the helix 1 for engaging the thread of a screw. This helix or thread 1 is so arranged and distributed in strip 2 that the entire thread pitch S is half depressed (sl) or half raised (S2) from one surface B of the sheet.For all practical purposes the thread 1 extends over 360 degrees.

This method of constructing the thread 1 in the sheet metal strip 2 has, in addition to the space saving advantage, the advantage of permitting a sheet metal screw 7 to be screwed into the thread having a pitch S, both from side A and from side B of strip 2.

A use of the invention is shown in Figures 3 and 4 relative to a fitting 3, used in furniture for fastening wooden boards. This fitting is provided with two narrow sheet metal webs 2a and 2b, which project at rightangles to a part of the fitting. Each of the two facing webs 2a and 2b has a screw thread 1 constructed according to Figures 1 and 2 with the same thread pitch S in which is screwed a sheet metal screw 7. When screw 7 is screwed in direction R, its tip 8 presses against a holding claw 4 resiliently mounted on fitting 3.

The section through the screw holder shown in Figure 4 illustrates particularly clearly the space-saving location of the sheet metal screw thread 1 according to the invention in extremely narrow width sheet metal webs 2a and 2b, which are hardly wider than the head 9 of sheet metal screw 7.

WHAT WE CLAIM IS:- 1. A metal sheet having a circular aperture to receive a screw, wherein an annular area surrounding the aperture is divided by a radial cut and the edges of the cut are separated by pressing the annular area out from the sheet in opposite directions on either side of the cut by equal amounts, so that the edges of the cut are respectively inclined in opposite directions to the sheet and the edge of the aperture forms a helix for engaging the thread of the screw.

2. A metal sheet having a circular aperture to receive a screw, constructed and arranged substantially as hereinbefore described and shown in the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (2)

**WARNING** start of CLMS field may overlap end of DESC **. This method of constructing the thread 1 in the sheet metal strip 2 has, in addition to the space saving advantage, the advantage of permitting a sheet metal screw 7 to be screwed into the thread having a pitch S, both from side A and from side B of strip 2. A use of the invention is shown in Figures 3 and 4 relative to a fitting 3, used in furniture for fastening wooden boards. This fitting is provided with two narrow sheet metal webs 2a and 2b, which project at rightangles to a part of the fitting. Each of the two facing webs 2a and 2b has a screw thread 1 constructed according to Figures 1 and 2 with the same thread pitch S in which is screwed a sheet metal screw 7. When screw 7 is screwed in direction R, its tip 8 presses against a holding claw 4 resiliently mounted on fitting 3. The section through the screw holder shown in Figure 4 illustrates particularly clearly the space-saving location of the sheet metal screw thread 1 according to the invention in extremely narrow width sheet metal webs 2a and 2b, which are hardly wider than the head 9 of sheet metal screw 7. WHAT WE CLAIM IS:-

1. A metal sheet having a circular aperture to receive a screw, wherein an annular area surrounding the aperture is divided by a radial cut and the edges of the cut are separated by pressing the annular area out from the sheet in opposite directions on either side of the cut by equal amounts, so that the edges of the cut are respectively inclined in opposite directions to the sheet and the edge of the aperture forms a helix for engaging the thread of the screw.

2. A metal sheet having a circular aperture to receive a screw, constructed and arranged substantially as hereinbefore described and shown in the accompanying drawing.