GB2234923A

GB2234923A - Anchors

Info

Publication number: GB2234923A
Application number: GB9012049A
Authority: GB
Inventors: Jeffrey Woodcock
Original assignee: Unifix Ltd
Current assignee: Unifix Ltd
Priority date: 1989-05-31
Filing date: 1990-05-30
Publication date: 1991-02-20
Also published as: GB9012049D0; GB8912482D0

Abstract

An anchor bolt 1 is formed in a continuous operation from wire stock by cutting (Stage I) to form a blank 7. The blank is then cold forged to form an enlarged head 4 (Stage II). The blank is then cleaned and degreased and is then form rolled to produce a thread 3, a radial abutment 6, and an unthreaded neck 9 between the abutment 6 and the head 4 which is of slightly less diameter than the original diameter of the blank 8 (Stage III). The finished blank is then heat treated prior to having a protective finish applied by any suitable process such as electro-zinc plating or by mechanical galvanization, (Stage IV). A split stainless steel sleeve 5 is then forced over the blank at the neck 9 (Stage V). <IMAGE>

Description

ANCHORS The invention relates to anchors, particularly those of the kind which are insertable into a hole in a substrate and then rotated to expand an expansion member carried by the anchor to secure it in the hole. Such anchors are often knows as insit bolts.

Such bolts are often difficult, and therefore expensive, to manufacture as they have a head, usually a frusto-conical end opposite the head, a screw thread and a loose member which is the expansion member mounted adjacent the frusto-conical end.

It is an object of the invention to seek to mitigate this disadvantage.

According to the invention there is provided a method of manufacturing an anchor including an expansion member, comprising the steps of providing a cylindrical metal workpiece of a required length, upsetting one end to provide an enlargement, forming a thread formation over a required length thereof, and heat treating the blank.

The step of providing the cylindrical metal workpiece of the required length may be by cutting the workpiece from a wire which may then be preformed as by cold forging to provide the step of upsetting one end to form the enlargement. The enlargement may be frusto-conical in configuration.

The step of providing the thread formation may be a form rolling step.

There may be an additional step subsequent to the heat treating step whereby the blank is protected by the application of a protective finish. The protective finish may be applied by an electro zinc plating process, or by a mechanical galvanizing process.

Between the form rolling step and the preforming step there may be a step of cleaning the blank. This step may comprise cleaning and degreasing the blank prior to the form rolling step.

Finally, there may be a step whereby an expansion member, which may be a cylindrical longitudinally split stainless steel clip is mounted on the blank, to form the complete expansion member, or insit bolt.

The method steps may be carried out sequentially in an automated, continuous or semi-continuous process.

It will be understood that the invention extends to an expansion member, maoe by the method hereinbefore defined.

A method of forming an expansion anchor or insit bolt is diagrammatically illustrated, by way of example, with reference to the accompanying schematic representation of stages in the method of making an insit bolt according to the invention.

Referring to the drawings, there is shown schematically a method of making an anchor or insit bolt 1 which comprises a shank 2 having a threaded part 3 which in use carries a nut (not shown), an enlarged.part or head 4, and an expansion member in the form of a substantially cylindrical stainless steel sleeve or clip 5 which is split longitudinally, the facing edges of the split being parallel and on two facing substantially planar parts of the sleeve so that they project beyond the outside diameter of the head 4. The sleeve 5 is freely rotatable on the shank 2 between the head 4 and a radial abutment 6.

The bolt 1 is formed in a continuous forming operation from a cold forged wire stock of the required diameter by cutting, (Stage I) to form a blank 7. The wire blank 7 is then preformed to upset one end to form the enlarged head 4 (Stage II). The blank 8 so formed is then cleaned and degreased and the clean blank 8 is then form rolled to produce the thread 3 and the radial abutment 6, which operation produces an unthreaded neck 9 between the abutment 6 and the head 4 which is of slightly less diameter than the original diameter of the blank 8.

This is Stage III. The finished blank is then heat treated prior to having a protective finish applied by any suitable process such as electrozinc plating or by mechanical galvanization, (Stage IV). The stainless steel sleeve or clip 5 is then forced over the blank at the neck 9 by springing-apart of the facing edges of the split, which then returns towards one another when they have passed the diameter of the neck, Stage V.

The finished product is then ready for use when a nut is threaded onto the end of the shank opposite the enlarged head 4.

In use of the bolt 1, the enlarged head 4 is inserted into a hole in a substrate so that the threaded end protrudes from the hole, the hole being of just sufficient diameter to take the bolt and sleeve. When the nut is rotated the shank 2 is effectively "drawn" out of the hole but this is prevented by the sleeve 5, trapped between the abutment 6 and head 4. To accommodate the turning motion, the sleeve has effectively to be shortened, so it expands radially, the edges then biting into the material surrounding the hole firmly to anchor the bolt in the hole.

Claims

1. A method of manufacturing an anchor comprising the steps of providing a cylindrical metal workpiece of a required length, upsetting one end to provide an enlargement, forming a thread formation over a required length thereof, and heat treating the workpiece.

2. A method according to Claim 1, the step of providing the cylindrical metal workpiece of the required length comprising cutting the workpiece from a wire and subsequently preforming the wire by cold forging to provide the step of upsetting one end to form the enlargement.

3. A method according to Claim 2, the upsetting step providing an enlargement of frusto-conical configuration.

4. A method according to any preceding Claim, the step of providing the thread formation being a form rolling step.

5. A method according to any preceding Claim, including an additional step subsequent to the heat treating step whereby the blank is protected by the application of a protective finish.

6. A method according to Claim 5, the step of applying the protective finish being by an electro-zinc plating process.

7. A method according to Claim 5, the step of applying the protective finish being by a mechanical galvanizing process.

8. A method according to any of Claims 4 to 7, including between the form rolling step and the preforming step a step of cleaning the blank.

9. A method according to any preceding Claim, including a step whereby an expansion member is mounted on the blank to form a complete expansion member.

10. A method according to Claim 9, including the step of mounting a cylindrical longitudinally split stainless steel clip on the blank to form the expansion member.

11. A method according to any preceding Claim, carried out sequentially in an automated, continuous or semi-continuous process.

12. A method of manufacturing an anchor, substantially as hereinbefore described in the accompanying drawings.

13. An anchor made by the method according to any preceding Claim.

14. An anchor, the expansion member comprising a longitudinally split cylindrical steel clip.

15. An anchor, substantially as hereinbefore described with reference to the accompanying drawings.