GB2051284A - Riveted Bush - Google Patents

Abstract

A riveted bush has a head 1 and a shank 2 provided externally with knurling to give increased resistance to rotation of the bush in a hole in sheet metal, and to extraction from the hole. <IMAGE>

Description

SPECIFICATION Improved Rivet Bush This invention relates to a rivet bush.

A rivet bush is an internally screw threaded bush which is applied to a hole in relatively thin sheet metal or other material to allow a bolt to be screwed into the sheet. Bushes of this type have been known for many years. When assembled the bush must not rotate relative to the sheet and must also resist being pulled out of the hole.

Provided that the bush has a head which is of hexagonal or other polygonal shape, the corners of the head tend to bite into the sheet when the bush is riveted in place and prevent rotation of the bush. However, in the event that the bush has a head of circular cross-section, it is preferred to provide some means for preventing rotation of the bush. In one known form of bush, the annular surface of the head which makes contact with the sheet material is provided with serrations extending radially. In another known form of bush, the shank which extends into the hole is provided with serrations which extend axially. In yet another known form of bush the peripheral surface of the head is provided with serrations which extend axially and which terminate in sharp projections on the end of the head which bites into the sheet material.

We have discovered that surprisingly, the resistance of a rivet bush to rotation and to extraction from its hole may be improved substantially by the simple expedient of providing the shank with an external surface which is knurled.

The invention which is defined more particularly in the appended claims will now be described in greater detail by way of example with reference to the accompnying drawings in which Figure 1 is a partly sectioned side view of rivet bush embodying the invention and, Figure 2 is a view similar to Figure 1 but of the bush applied to a sheet of metal.

Referring to Figure 1, a rivet bush made from metal stock of circular cross-section has a head 1 and a shank 2. A bore extends through the bush and is screw threaded at 2 within the head and tapers at 3 within the shank. The end surface 4 of the bush may be counter-sunk or dished to avoid damage to the screw threads during the riveting operation. The annular portion 5 adjoining the shank is undercut. During manufacture, the peripheral external surface of the shank is provided with a diamond knurl by means of a suitable tool.

Referring now to Figure 2, the bush is applied to sheet metal by drilling a hole in the sheet, inserting the shank, and expanding the latter using suitable riveting tools. The knurling on the shank results in the bush having less tendency to rotate or pull out of the hole than the bushes of known type. Modifications are possible to the bush shown in the drawing, thus, for example, the invention may be applied to a tank-type bush in which the bore is closed at the end 4 of the head.

Also, the head may be hexagonal in shape, rather than circular. Although it is preferred for the peripheral surface of the shank to be cylindrical, it may be frusto-conical. For some applications, a bush having a plain bore may be preferred.

Claims

1. A rivet bush having a head and a shank, a bore extending through the bush, the peripheral surface of the shank being provided with knurling.

2. A rivet bush substantially in accordance with any embodiment or modification of the invention claimed in Claim 1 and herein described or illustrated.

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

Claims (2)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improved Rivet Bush This invention relates to a rivet bush. A rivet bush is an internally screw threaded bush which is applied to a hole in relatively thin sheet metal or other material to allow a bolt to be screwed into the sheet. Bushes of this type have been known for many years. When assembled the bush must not rotate relative to the sheet and must also resist being pulled out of the hole. Provided that the bush has a head which is of hexagonal or other polygonal shape, the corners of the head tend to bite into the sheet when the bush is riveted in place and prevent rotation of the bush. However, in the event that the bush has a head of circular cross-section, it is preferred to provide some means for preventing rotation of the bush. In one known form of bush, the annular surface of the head which makes contact with the sheet material is provided with serrations extending radially. In another known form of bush, the shank which extends into the hole is provided with serrations which extend axially. In yet another known form of bush the peripheral surface of the head is provided with serrations which extend axially and which terminate in sharp projections on the end of the head which bites into the sheet material. We have discovered that surprisingly, the resistance of a rivet bush to rotation and to extraction from its hole may be improved substantially by the simple expedient of providing the shank with an external surface which is knurled. The invention which is defined more particularly in the appended claims will now be described in greater detail by way of example with reference to the accompnying drawings in which Figure 1 is a partly sectioned side view of rivet bush embodying the invention and, Figure 2 is a view similar to Figure 1 but of the bush applied to a sheet of metal. Referring to Figure 1, a rivet bush made from metal stock of circular cross-section has a head 1 and a shank 2. A bore extends through the bush and is screw threaded at 2 within the head and tapers at 3 within the shank. The end surface 4 of the bush may be counter-sunk or dished to avoid damage to the screw threads during the riveting operation. The annular portion 5 adjoining the shank is undercut. During manufacture, the peripheral external surface of the shank is provided with a diamond knurl by means of a suitable tool. Referring now to Figure 2, the bush is applied to sheet metal by drilling a hole in the sheet, inserting the shank, and expanding the latter using suitable riveting tools. The knurling on the shank results in the bush having less tendency to rotate or pull out of the hole than the bushes of known type. Modifications are possible to the bush shown in the drawing, thus, for example, the invention may be applied to a tank-type bush in which the bore is closed at the end 4 of the head. Also, the head may be hexagonal in shape, rather than circular. Although it is preferred for the peripheral surface of the shank to be cylindrical, it may be frusto-conical. For some applications, a bush having a plain bore may be preferred. Claims

1. A rivet bush having a head and a shank, a bore extending through the bush, the peripheral surface of the shank being provided with knurling.

2. A rivet bush substantially in accordance with any embodiment or modification of the invention claimed in Claim 1 and herein described or illustrated.