GB2109719A

GB2109719A - Cold working of metal rod or wire

Info

Publication number: GB2109719A
Application number: GB08134665A
Authority: GB
Inventors: Peter Gough Davies
Original assignee: Allied Steel and Wire Ltd
Current assignee: Allied Steel and Wire Ltd
Priority date: 1981-11-18
Filing date: 1981-11-18
Publication date: 1983-06-08

Abstract

A process for the cold working of hot rolled steel rod is carried out on apparatus comprising one or more freely rotatable pulleys 18 driven by a motor 26 for orbital revolution for imparting a substantial degree of cold working to the rod as it is fed continuously through the apparatus. The rod is twisted in one direction as it enters the pulley system and is then twisted in the opposite direction as it leaves the system. The process and apparatus operate also to descale and straighten the rod continuously and are particularly useful in the production of rod for welded mesh in reinforcing concrete. <IMAGE>

Description

SPECIFICATION Apparatus for the cold working of metal rod or wire This invention relates to a process for the cold working of metal rod or wire.

It is conventional to refer to metal which has been reduced in cross-section into a final elongated form by rolling as rod and to refer to rod material which has subsequently been reduced in cross-section by drawing through a die as wire.

Throughout this specification including the claims, the term rod is used generically to include rod material which has been drawn into wire.

It is known that the cold working of for example steel rod will improve its mechanical properties, in particular its tensile strength, and such cold working is usually effected either by rolling or drawing. Thus in the production of steel rod for use in forming welded mesh for concrete reinforcement, the material may initially be hot rolled and then cold drawn or cold rolled in order to achieve the necessary standard specification relating to its tensile strength. Such specifications usually state that the ratio of the ultimate tensile stress to the proof stress shall be more than a specific value. For rod used in concrete reinforcing meshes the ratio is 1.05:1.

Such rods may have a smooth surface or may be provided with surface deformations such as ribs to improve their keying or bonding capability to the concrete.

The most convenient way of introducing surface deformations such as ribs is during the hot working stage, but these deformations do not survive the normal cold working techniques of cold drawing or cold rolling. Deformations can be introduced during a final cold rolling operation but their production requires excessive local working of the material and there is a high mechanical energy requirement. It is difficult or impossible to provide suitable deformations in a cold drawing operation.

It is known to hot roll deformations into reinforcing material, to cut the material into bars of finite length and then cold work by twisting.

This procedure is not suitable for long lengths of rod which are normally stored in coil form.

It is an object of the invention to provide a process for the cold working of hot rolled metal rod and which is utilisable to cold work such rod having either a smooth or ribbed surface.

In accordance with the invention there is provided a process of continuously cold working a hot rolled metal rod comprising continuously feeding the rod through a cold working station at which the rod is twisted in one direction about its axis and is then twisted in the opposite direction about its axis.

Preferably the rod is a steel rod suitable for use in welded mesh in reinforcing concrete and it may have either a smooth surface or a ribbed surface.

The process preferably comprises the steps of passing the rod continuously around the pulley system having one or more rotatable pulleys around which the rod runs continuously from an input side to an output side thereof and continuously orbiting the pulley system about an axis other than the axis of rotation of the or each pulley whereby the rod is twisted in one direction at the input side of the pulley system and is then twisted in the opposite direction at the output side thereof.

The rod is conveniently fed around a restraint pulley before it enters the input side of the pulley system and preferably both the orbiting pulley system and the restraint pulley are driven in synchronism whereby the speed of orbiting of the pulley system is at a predetermined rate with respect to the speed of input of the rod to the pulley system from the restraint pulley.

This contra-twisting of the rod achieves several results: firstly a substantial degree of cold working is imparted to the rod; secondly the rod is effectively descaled and thirdly the rod is straightened.

Other features of the invention will become apparent from the following description given herein solely by way of example with reference to the accompanying drawing which is a perspective view of one form of apparatus enabling the process for the cold working of steel wire in accordance with the invention to be effected.

As illustrated in the drawing, the apparatus includes a fixed frame 10 upon which are mounted two plummer block bearings 12 and 14 for a hollow rotatable shaft 32. Each of the bearings 12 and 14 is centrally apertured with the apertures in alignment with each other. Outboard of the bearing 14, a stirrup shaped yoke is mounted on the end of the shaft 32; the yoke including two opposed parallel side plates 16 between which are mounted two freely rotatable pulleys 18. The pulleys 18 are carried in the yoke adjacent one edge thereof whilst at the other edge counter-balance weights 20 are mounted. In this embodiment the axes of the pulleys 18 are skewed slightly relative to each other either side of an axis normal to the axis of shaft 32.

At the input side of the apparatus there is a relatively large diameter driven restraint pulley 22 the lower edge of which is in alignment with the axis of the bearings 12 and 14. A V-groove in pulley 22 provides drive between the rod and pulley. Rod curved round the pulley acts as a lever arm to hold it against rotation of the pulley.

Located above and forward of the restraint pulley 22 is a freely rotatable guide pulley 24 onto which is fed the rod W from a convenient source such as a reel thereof. The direction of input of the rod W is shown by the arrow in the drawing.

At the rear of the apparatus there is mounted an air or electrically actuated controllable torque motor 26 which drives the restraint pulley 22 through a suitable gear box 28. The motor 26 is also coupled to rotate the shaft 32 and the yoke so that the rotatable pulleys 18 carried thereon are orbitable about the axis of the bearings 12 and 14. The pulley system is thus driven in synchronism with the restraint pulley 22 to provide a predetermined speed of orbiting with respect to the speed of input of the rod pulley 22.

The rod is pulled through the apparatus, for example from a rotating spool. If the rod is arranged to grip the restraint pulley 22 it transmits energy via the gear box 28 to the shaft of the motor 26 and hence to the yoke shaft 32, to contribute to the energy required for twisting.

In use, the rod W to be cold worked runs from a stock steel thereof around the two pulleys 24-22, through the hollow rotatable shaft 32, and around both pulleys 18 in the pulley system before exiting around a reaction pulley 34. The rod meets up with the pulley 34 at a point on the axis of shaft 32. thus the output of the rod at pulley 34 is co-axial with its input from pulley 22. Rod leaving pulley 34 at an angle acts as a lever arm to hold the rod against rotation. The rod passes continuously through the apparatus and is twisted in one direction between the restraint pulley 22 and the orbiting pulley system and is then twisted in the opposite direction as it passes between the output side of the pulley system and the reaction pulley thereby imparting a substantial degree of cold working to the rod.

Cold worked rod produced by the apparatus is particularly suitable for use in concrete reinforcing mesh where cut lengths of the cold worked rod have to be welded together. In particular the rod fed through the apparatus may be ribbed transversely, as is known practice in use of reinforcing rod for concrete, and the skewed axes of the orbiting pulleys 18 particularly ensure that such ribbed rod does not snag or chafe upon itself between the input and output sides of the pulley system. Also the rod is effectively descaled and straightened whereby it may be immediately cut and welded for use in concrete reinforcing mesh.

It will be appreciated that other arrangements of pulleys may be provided in the pulley system provided that they are orbitable in the manner hereinbefore described; in particular it may be convenient to provide three separate freely rotatable pulleys in the pulley system having their axes of rotation parallel to one another and normal to the orbital axes of the pulley system. Also, although not illustrated herein, it may be possible to utilise a single pulley in the yoke in which case it may be convenient to provide such pulley with a frusto-conical surface to avoid snagging or chafing of the rod as it passes around the pulley.

Claims

1. A process of continuously cold working a hot rolled metal rod comprising continuously feeding the rod through a cold working station at which the rod is twisted in one direction about its axis and is then twisted in the opposite direction about its axis.

2. A process according to Claim 1 wherein the rod is a steel rod.

3. A process according to Claim 1 or Claim 2 wherein the rod has a smooth surface.

4. A process according to Claim 1 or Claim 2 wherein the rod has s ribbed surface.

5. A process according to any one of the preceding claims wherein, at the cold working station, the rod is passed around a pulley system having one or more rotatable pulleys around which the rod runs continuously from an input side to an output side thereof and wherein the pulley system is orbited about an axis other than the axis of rotation of the or each pulley whereby the rod is twisted in one direction at the input side of the pulley system and is then twisted in the opposite direction at the output side thereof.

6. A process according to Claim 5 wherein the rod is fed over a restraint pulley before it enters the input side of the pulley system whereby the rod is twisted in one direction between the restraint pulley and the pulley system as the rod enters the input side thereof and is then twisted in the opposite direction as it leaves the output side of the pulley system.

7. A process according to Claim 6 wherein both the orbiting pulley system and the restraint pulley are driven in synchronism with each other whereby the speed of orbiting of the pulley system is at a predetermined rate with respect to the speed of input of the wire to the pulley system from the restraint pulley.