Device for guidance of wire blanks to wire rollers.

Technical field: The present invention relates to a device for guidance of wire blanks to wire rollers in a wire rolling mill.

Technical background

In wire rolling mills guiding rollers are used to direct the wire blanks into the forming rolls. The guiding rollers conventionally comprise cylinder-shaped rollers of hardened steel, steel based composite material or hard metal, which guiding rollers have grooves for the wire along their circumference. Each roller has precision machined outsparings which serve as supporting surfaces for ball bearings. These supporting surfaces can either be an integral part of the guiding roller or they can be in the form of a separate part which is affixed in a groove or the like by means of a locking spring. Conventional ball bearings are then affixed against the supporting surface for the ball bearings.

Due to heavy wear of the guiding rollers, the guiding rollers have to be machined at short intervals, which neccessiates stop of the wire rolling mill. In new wire rolling mills the rolling speed is substantially increased, from 60 meter pr. second, which earlier was considered as high speed rolling, to above 100 meters pr. second. Steel ball bearings for such high speed seem to be complicated and costly, and their lifetime will probably be very limited.

Disclosure in Invention

It is an object of the present invention to provide more simple guiding rollers for wire rolling as an alternative to steel bearings and which has a substantially more simple design and gives a better performance.

Accordingly, the present invention relates to a guiding roller for guiding wire blanks to the forming rolls of a wire rolling mill, which guiding roller comprises a cylinder shaped guiding roller having a central opening extending throughout the roller, characterized in the the guiding roller comprises an inner central ring which constitutes an integral part of the guiding roller and where the inner surface of the guiding roller together with the sidewalls of the inner central ring constitute ball races for ball bearings arranged on each side of the inner central ring.

According to the present invention the guiding roller itself constitutes the outer ball races for the ball bearings, which gives a substantial simplification of the guiding roller.

According to a preferred embodiment, the guiding roller, the balls of the ball bearings and the inner ball races for the ball bearings are made from a ceramic material. As ceramic material it can be used for instance alumina, zirconia, silicon carbide, silicon nitride and ceramic composite materials comprising two or more different ceramic materials. Such a guiding roller where all parts are made from ceramic material will have substantial advantages compared to guiding rollers made from steel, steel based composite material or hard metal and conventional steel ball bearings Thus the guiding rollers according to the present invention made only from ceramic material will have low weight and high wear - and corrosion resistance compared to conventional guiding rolls.

Brief Description of the Drawings

Figure 1 is a cross section of a guiding roller according to the prior art

Figure 2 is a cut taken along line A-A in figure 1,

Figure 3 is a cross section of a guiding roller according to the present invention, and where,

Figure 4 is a cut taken along line B-B in Figure 3.

Figures 1 and 2 show a conventional guiding roller for use in wire rolling. The guiding roller comprises a cylinder-shaped guiding roller 1 made from steel or a ceramic material. The guiding roller 1 has a groove 2 about its circumference for guiding the wire blank. The guiding roller is further equipped with an inwardly extending central part 3 which has presision machined outsparings serving as supporting surfaces for two ball bearings 4, 5. The ball bearings 4, 5 are conventional ball bearings made from steel and having outer ball races 6, inner ball races 7 and balls 8. The guiding roller is mounted on an axle which runs through the ball bearings 4, 5 whereby the guiding roller can freely rotate about the axle.

The guiding roller according to the present invention is shown in Figure 3 and 4.

The guiding roller shown in Figures 3 and 4 comprises a cylinder-shaped guiding roller 10, preferably made form a ceramic material, having an inner central part 11, which together with the inner surface of the guiding roller, constitute outer ball races for ball bearings 12, 13 where the balls 14 in the ball bearings 12, 13 are kept in place by means of the central inner part 11 and inner ball races 15. The inner surface of the guiding roller 10 is machined on each side of the inner central part 11 in order to form

the mentioned outer ball races for the ball bearings 12, 13. Both the balls 14 and the inner ball races are preferably made from a ceramic material. As ceramic material it is used for instance, alumina, zirconia, silicon carbide, silicon nitride, or ceramic composite materials made from two or more different ceramic materials. In the same way as for conventional guiding rollers the circumference of the guiding roller has a groove 16 for guiding the wire blank.

The guiding roller according to the present invention thus represents a substantial simplification of known guiding rollers as the ball bearings constitute an integral part of the guiding roller. By making all parts of the guiding roller from a ceramic material one can further obtain an acceptable duration of the guiding roller even at a substantial increased rolling speed compared to conventional rolling speed used in wire rolling.