GB2109717A - Cold working of metal rod or wire - Google Patents

Abstract

Apparatus for the cold working of hot rolled steel rod comprises a set of freely rotatable pulleys 72 around which the rod runs. The set of pulleys as a whole is driven for orbital revolution. The rod is twisted in one direction as it enters the pulley system and in the opposite direction as it leaves. The rod is pulled through the pulley system by a rotatable coiler 78 downstream of the system against braking effort imparted to the rod upstream of the system whereby the rod is pulled through under tension. Control of the transverse dimensions of the rod is imparted by a sensor 74 downstream of the pulley system, the output from which is used to adjust the tension imparted by the braking pulley 76. The apparatus operates also to descale and straighten the rod continuously and is particularly useful in the production of steel rod for welded mesh in reinforcing concrete. <IMAGE>

Description

SPECIFICATION Apparatus for the cold working of metal rod or wire.

This invention relates to apparatus 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 specified value. For rod used in concrete reinforcing meshes the ratio specified 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 desirable to control the final diameter of the cold worked rod accurately to ensure that no unnecessary weight of material is incorporated in a particular length, whilst maintaining the diameter within a standard specification.

It is an object of the invention to provide apparatus for the cold working of hot rolled metal rod which is utilisable to cold work such rod and control the diameter of the cold worked rod.

In accordance with the invention there is provided apparatus for the cold working of metal rod which has been produced by hot rolling comprising 3 pulley system having one or more rotatable pulleys around which the rod is passed continuously from an input side to an output side thereof, the pulley system being orbital about an axis other than the axis of rotation of the or each pulley whereby the rod is continuously twisted in one direction at the input side of the pulley system and is continuously twisted in the opposite direction at the output side thereof, a transverse dimension sensor downstream of the orbital pulley system and means actuable in response to said sensor to control tension in the rod as it is being twisted to elongate the rod and thereby control the sensed transverse dimension. For a circular bar the transverse dimension sensed is its diameter.

Said tension applying means conveniently comprises an adjustable brake upstream of the orbital pulley system, the degree of braking effort effected by said brake on the rod being responsive to the output from said sensor. The sensor conveniently comprises a non-contacting gauge, possibly a laser gauge, directed at the rod downstream of the orbital pulley system.

Preferably there is provided driven take-up means in the form of a rotatable coiler for continuously winding the cold worked rod into a coil thereof and drive means linking the coiler to the orbiting pulley system whereby the rod is pulled by the coiler through the pulley system at a speed having a predetermined ratio to the speed of orbiting of the pulley system.

The orbital pulley system may comprise a pair of freely rotatable pulleys having their axes of rotation skewed relative to each other either side of an axis normal to the orbital axis of rotation of the system. Alternatively the orbital pulley system may comprise three freely rotatable pulleys having their axes of rotation parallel to one another and normal to the orbital axis of rotation of the system.

The contra-twisting of the rod as it is continuously fed through the orbital pulley system 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. Also, the transverse dimension and thus the weight per unit length is controlled within fine limits with the result that excess weight of material in the final product is kept to a minimum.

Other features of the invention will become apparent from the following description given herein solely by way of example with reference to the accompanying drawings wherein Figure 1 is a top perspective view of a general arrangement of cold working apparatus constructed in accordance with the invention Figure 2 is a side view of an alternative form of such apparatus Figure 3 is a plan view of the apparatus of Figure 2 and Figure 4 is a diagram of the gauge control system.

Referring to Figure 1, the apparatus is shown mounted on a fixed base frame including two coaxial plummer block bearings 10 and 12 for a hollow rotatable shaft 14. Outboard of the downstream bearing 12 a stirrup shaped yoke 16 is mounted on the end of the shaft 14 for rotation therewith. The yoke includes two opposed parallel side plates between which are mounted two freely rotatable pulleys 18 and 20 carried in the yoke adjacent one edge thereof whilst at the other edge a counter-balance weight 22 is mounted.

Preferably the axes of the pulleys 18 and 20 are skewed relative to each other either side of an axis normal to the axis of the shaft 14.

The shaft 14, and hence the pulley system 18-20, is driven for rotation in the bearings 10 and 12 by a belt drive 24 from an input drive shaft 26 from a take-up rotatable coiler downstream of the apparatus.

As shown in the drawing, rod to be cold worked is fed through the apparatus in the direction of the arrows, entering through a guide tube 28 and guide pulley 30, passing around the lower sheave 32 of a double sheave pulley, around a restraint pulley 34 so that is angled and restrains the rod against rotation, through the rotatable shaft 14, around the pulley system 1 8-20, round a further restraint pulley 36 downstream of the apparatus to restrain the downstream part of the rod against rotation, and exiting to the coiler around the upper sheave 38 of the double sheave pulley.From this upper sheave 38 the rod is fed to the coiler whose motor not only drives the coiler to wind the cold worked rod thereon but also drives the pulley system 1 8-20 for orbital rotation about the axis of the hollow shaft 14 via the input shaft 26 and drive belt 24. Thus the rod is pulled by the coiling means through the pulley system at a speed having a predetermined ratio to the speed of orbiting of the pulley system and, when the coiler motor stops, the orbiting pulley system also stops thus obviating the possibility of orbital twisting being accidentally imparted to the rod when the rod is not acutally running through the system.

The double sheave pulley comprises two sheaves 32 and 38 which together are fully rotatable and which are rotatable with respect to each other against a controllable degree of friction braking between the two sheaves. The degree of braking is adjusted by adjusting a clamp load acting between the two sheaves on friction linings interposed between them. The effective diameter of the upper sheave 38 at the output side of the rod is slightly larger than that of the input sheave 32 so that the linear rod speed at the output would, without slippage be higher than that of the input. This causes the input to drag behind the output and for slip to occur between the two sheaves. Thus tension, dependent on the controllable friction drag, is generated in the rod passing through the pulley system.The work done against the frictional drag is at the difference in speeds between the two sheaves and thus is much less than would be required by a simple friction drag at the input to the system.

Thus rod is fed continuously through the system from a stock coil thereof and is twisted in one direction between the restraint pulley 34 and the orbital pulley system 1 8-20 at the input side thereof and is then twisted in the opposite direction between the restraint pulley 36 and the pulley system at the output side thereof, thereby imparting a substantial degree of cold working to the rod.

An alternative form of the apparatus is shown in Figures 2 and 3 of the drawings comprising a frame structure having a pair of aligned apertured plummer block bearings 40 and 42 thereon between which is mounted an orbital pulley system comprising three in-line freely rotatable pulleys 44-46-48. The pulleys are mounted in a yoke 50 with their axes of rotation parallel to one another and normal to the orbital axis of rotation of the system i.e. the axis of the centre lines of bearings 4042. The yoke 50 with its freely rotatable pulleys 44-46-48 is driven for orbital rotation through a gear wheel system 52 from an input drive shaft 54 itself driven from the motor which drives the coiler (not illustrated).

Rod to be cold worked enters the apparatus around a guide pulley 56, over a brakable rotational restraint pulley 58, through the upstream plummer block bearing 40, around the pulley system 44-46-48, through the downstream plummer block bearing 42 and exits to the coiler around a further restraint pulley 60 and guide pulley 62. Substantially as previously described with reference to Figure 1, the motor driving the coiler acts to pull the rod through the orbital pulley system at a speed having a predetermined ratio to the speed of orbiting of the pulley system. Predetermined tension is imparted to the rod by the brakable pulley 58 which has means associated therewith for adjusting the degree of braking effort imparted to the rod.

Figure 2 shows that the centre pulley 46 of the three freely rotatable pulleys in the orbital system is withdrawable downwardly of the yoke 50 to facilitate initial threading of the rod through the system and is thereafter moved upwardly into the position shown in Figure 2 so that, in the orientation of the yoke shown in this drawing, the wire passes over the centre pulley 46 and under the two outer pulleys 44 and 48.

Thus, in use, the rod is fed from a stock coil thereof continuously through the apparatus and is twisted in one direction between the brakable pulley 58 and the pulley system at the input side thereof and is then twisted in the opposite direction as it leaves the output side of the pulley system between it and the guide pulley 60 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 have previously been ribbed transversely, as in known practice in use of reinforcing rod for concrete. The rod is not only cold worked but effectively descaled as it passes through the apparatus. If the rod is also pulled through the apparatus by a straight line puller rather than being coiled onto a rotating pulley, the untwisting at the output side of the pulley system straightens the rod prior to cutting to length and welding into mesh.

Figure 4 is a block diagram of the gauge control system as applied to the apparatus of either Figure 1 or Figures 2 and 3. The control apparatus comprises a sensor 70, which may conveniently be a laser gauge or other form of non-contacting gauge, directed at the wire downstream of the orbital pulley system 72. The output from the sensor 70 is supplied to a control and calibration unit 74 which generates a brake control signal and applies it to the braking means 76. Braking means 76 represents either the braking means between the sheaves 32 and 38 of the double sheave pulley of Figure 1 or the single braking pulley 58 of Figures 2 and 3. As previously described, the rod is pulled through the orbital pulley system 72 by the coiler 78 under tension imparted to the rod by the braking means 76. The gauge of the rod downstream of the orbital pulley system 72 is detected by the sensor 70 and, if the gauge of the rod varies from a predetermined value, the output from the sensor adjusts the braking tension on the rod at the input side of the orbital pulley system.

The increased tension in the rod occurs in the regions where the rod is being deformed by twisting as a result of which less tension is needed to stretch the rod longitudinally and reduce its cross-section than would be the case with only a direct tensile load on the rod. The control system is set so that the tension and thus the extension of the rod matches the requirement for reduction in cross-section of the rod to very fine limits.

Claims (6)

1. Apparatus for the cold working of metal rod which has been produced by hot rolling comprising a pulley system having one or more rotatable pulleys around which the rod is passed continuously from an input side to an output side thereof, the pulley system being orbital about an axis other than the axis of rotation of the or each pulley whereby the rod is continuously twisted in one direction at the input side of the pulley system and is continuously twisted in the opposite direction at the output side thereof, a transverse dimension sensor downstream of the orbital pulley system and means actuable in response to said sensor to control tension to the rod upstream of the pulley system.

2. Apparatus as claimed in Claim 1 wherein said tension applying means comprises an adjustable brake upstream of the orbital pulley system, the degree of braking effort effected by said brake on the rod being responsive to the output from said sensor.

3. Apparatus as claimed in either one of Claims 1 or 2 wherein said sensor comprises a noncontacting gauge such as a laser gauge directed at the rod.

4. Apparatus as claimed in any one of the preceding claims wherein there is provided driven take-up means for continuously pulling the cold worked rod through the orbital pulley system and drive means linking the take-up means to the pulley system whereby the rod is pulled by the take-up means through the pulley system at a speed having a predetermined ratio to the speed of orbiting of the pulley system.

5. Apparatus as claimed in Claim 4 wherein the take-up means comprises a rotatable coiler for continuously winding the cold worked wire thereon.

6. Apparatus as claimed in any one of the preceding claims wherein the orbital pulley system comprises a pair of freely rotatable pulleys having their axes of rotation skewed relative to each other either side of an axis normal to the orbital axis of rotation of the system.

.7. Apparatus as claimed in any one of Claims 1 to 5 wherein the orbital pulley system comprises three freely rotatable pulleys having their axes of rotation parallel to one another and normal to the orbital axis of rotation of the system.