GB2238971A

GB2238971A - Reducing mill

Info

Publication number: GB2238971A
Application number: GB9023137A
Authority: GB
Inventors: H L Bortoli; P Day; P W Flavell; T E E King
Original assignee: Rollsec Ltd
Current assignee: Rollsec Ltd
Priority date: 1989-10-25
Filing date: 1990-10-24
Publication date: 1991-06-19
Also published as: GB8924036D0; GB9023137D0

Abstract

Flat strip is rolled into a tubular intermediate product, and is then passed through a reducing mill having a plurality of passes, each pass comprising at least three work rolls 30, 31, 32 engaging the workpiece at angularly spaced positions in a common plane. The final product may be welding rod. <IMAGE>

Description

Title: "Reducing Mill" Description of Invention This invention relates to a reducing mill.

A previously known reducing mill has comprised a series of roll passes, each pass acting on a workpiece sequentially to reduce the crosssectional area of the workpiece, each pass comprising a pair of opposed work rolls, the axes of rotation of the rolls of adjacent pairs being mutually inclined around a pass line of the mill at 90 . For example, if the rolls of a first pass were disposed so that their axes of rotation were horizontal, then the rolls of the next adjacent pass would be orientated so that their axes of rotation are vertical and so on throughout the series.

It has been found that when the workpiece is a tube an inconsistent wall thickness may occur in the resultant product.

An object of the invention is to provide a new and improved reducing mill whereby the above mentioned problem is overcome or is reduced.

According to the present invention we provide a reducing mill having a plurality of passes, each pass comprising at least three work rolls adapted operatively to engage a workpiece at angularly spaced positions and in a common plane.

The axes of the rolls of one pass may be inclined about a pass line of the mill to the axes of the rolls of the or another pass.

The axes of rotation of the rolls of said one pass may be inclined at an angle of 180 about said pass line to the axes of rotation of the or another pass.

Preferably each pass comprises three rolls, the axes of rotation of the adjacent rolls of the pass being mutually inclined, about said pass line, at 12cup.

Where each pass comprises three rolls, one roll of one pass may be rotatable about a horizontal axis disposed above a pass line of the mill whilst one roll of the or another pass may be rotatable about a horizontal axis disposed below said pass line of the mill.

At least one roll of at least one pass may be driven and preferably all the rolls of all the passes are driven so that each successive roll exerts a tractive force on a workpiece and so transports the workpiece through the mill.

Alternatively, or in addition, a separate transport means may be provided to transport a workpiece through the mill.

Preferably the rolls of each pass are arranged to effect at least a 5% reduction in the cross-sectional area of the workpiece prior to entry into the pass.

The rolls of the passes may be arranged so that there is no change in shape of the workpiece on passage through each pass.

The reducing mill in accordance with the invention may be provided in combination with means to introduce a further component into a tubular blank and means to feed the thus occupied blank to said reducing mill according to the first aspect of the invention.

The combination may include means to form an initial workpiece of strip configuration to an intermediate product of tubular configuration and means to join the adjacent edges of the thus formed intermediate product and thus provide said tubular blank.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings wherein: FIGURE 1 is a diagrammatic representation of an apparatus embodying the invention; FIGURE 2 is a diagrammatic plan view, to an enlarged scale, showing part of a reducing mill embodying the invention with parts omitted for clarity; FIGURE 3 is a section on the line 3-3 of Figure 2 to an enlarged scale, and FIGURE 4 is a part section on the line 4-4 of Figure 2, drawn to the same scale as Figure 3.

Referring now to Figure 1, an apparatus is shown which comprises a tube forming station 10 at which a blank 11 in the form of a flat strip is drawn from a coil supply 12 and formed, for example by rolling in conventional manner, to provide a generally tubular intermediate product 13 which passes to a filling station 14 whereat the tube is filled with a further component. For example, where the finished component is to comprise a welding rod, with suitable flux powder or a combination of powder and welding wire of suitable composition. Thereafter the adjacent edges of the strip 11 are brought adjacent to each other and are joined together, for example by welding, adhesive or other suitable means at a joining station 15 to provide a tubular blank 16.The resuitant thus occupied tubular blank 16 is then passed through a reducing mill 17 which may comprise one continuous section or any desired number of sections and the single or each of a plurality of sections may comprise any desired number of passes, for example, between five and fifty passes. In the present example each pass is designed to provide a reduction in cross-sectional area of the workpiece in excess of 5%.

Each pass comprises three rolls 30, 31, 32 disposed equi-angularly around a pass line P of the mill. In the example illustrated, in Figure 2, the first pass A, see Figure 4, has the roll 30 orientated so that it is rotatable about a horizontal axis H1-H1 which is disposed above the pass line P whilst the rolls 31, 32 are inclined at 12cup to the roll 30. The next adjacent pass B, see Figure 3, is arranged so that the roll 30 is rotatable about a horizontal axis H2-H2 disposed below the pass line P and again the rolls 31, 32 are orientated at 120 to the roll 30. This alternate disposition of the roll 30 above and below the pass line P is repeated for all passes throughout the mill.

Each roll 30, 32 is carried on an associated shaft 30 - 322 which is carried in bearings 33 carried in a frame 34. The shaft 30. is provided with a driving flange 35 and has a pair of bevel gears 36,37 fixed to the shaft 30g.

The bevel gear 36 meshes with a similar bevel gear 38 fixed to the shaft 322 whilst the bevel gear 37 meshes with a similar bevel gear 39 fixed to the shaft 31ss. Thus drive communicated via the flange 35 to the shaft 302 is communicated to the shaft 312 and 323 by the bevel gears. The flange 35 is driven via a universal shaft 40 from a common drive shaft 41 rotated by a motor 41 which may be, for example, an electric or a hydraulic motor. A separate motor is provided for each pass and is a variable speed motor and the motors are arranged so that the rolls of each successive pass are rotated faster so as to apply a tractive force to the workpiece 17 as it is increased in length on passage through the mill.

The rolls 30 - 32 are of conventional configuration and made, for example of high carbon high chrome steel hardened to approximately 60 65 Rockwell "C* scale. Each roll 30 - 32 has a workpiece engaging surface part 43 of a shape to conform to the surface of the workpiece. In the present case the workpiece is a tube T of circular internal and external configuration and thus the surfaces 43 are of part circular configuration extending through approximately a 12cup arc and of a radius so as to effect approximately at least a 5% reduction in cross-sectional area of the tube T.

The workpiece engaging surfaces 43 are bounded by inclined flanks 44 which are arranged to mutually engage, as best shown in Figure 4, so as to define in the pass line a closed rolling surface thereby avoiding displacement of material of the workpiece in a radially outward direction which would otherwise form ridges or "feathering". By disposing the rolls of alternate passes alternately as described hereinbefore any tendency to feathering which may occur due to imprecise matching of the surfaces 43 is avoided.

Although in the above described example the case of three rolls inclined at 12cup has been described, if desired each pass may comprise a greater number of rolls. In addition, irrespective of the number of rolls the angular orientation of the rolls of adjacent passes may be different to that described hereinbefore and the disposition of passes of rolls at different locations along the length of the reduction mill may be varied from that described hereinbefore. For example, two or more adjacent rolls may have the same orientation and be followed downstream of the mill by at least one roll pass with rolls of a different orientation. In either case the different disposition of rolls may be different to the 180" difference described and illustrated.For example, rolls of different orientation may vary by, for example 30 or 60 or any other suitable number of degrees. Further, rolls of different disposition may be disposed at an increasingly different angle along the length of the tube mill, either consecutively or at spaced locations.

Although the case of a tube of circular configuration has been described hereinbefore, if desired the workpiece may be of other configuration, for example it may be a solid bar and the workpiece whether tubular or solid may be of non-circular external configuration, for example hexagonal or other polygonal configuration, the working surface 43 of the rolls being suitably configured to achieve the desired reduction in size without effecting a change in shape of the workpiece.

Although the reducing mill has been described hereinbefore as part of an apparatus in which flat strip is formed to a welded tube and then the tube is filled with a further component, if desired the reducing mill may be provided in any other apparatus or may stand alone.

If desired, instead of driving the rolls of each pass to transport the workpiece 17 through the mill, the rolls of only some passes, or of only one pass may be driven. Moreover, only one or two rolls of the pass or passes may be driven. Alternatively, a separate transport means, such as a pair of two or more rolls at least one of which is driven, or other transport means, may be positioned upstream or downstream, or at an intermediate position, of the mill instead of, or in addition to, driving at least one roll of one or more passes of the mill.

The features disclosed in the foregoing description, or the following daims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, or a class or group of substances or compositions, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

CLAIMS:

1. A reducing mill having a plurality of passes, each pass comprising at least three work rolls adapted operatively to engage a workpiece at angularly spaced positions and in a common plane.

2. A mill according to Claim 1 wherein the axes of the rolls of one pass are inclined about a pass line of the mill to the axes of the rolls of the or another pass.

3. A mill according to Claim 2 wherein the axes of rotation of the rolls of said one pass are inclined at an angle of 18cop about said pass line to the axes of rotation of the or another pass.

4. A mill according to any one of the preceding claims wherein each pass comprises three rolls, the axes of rotation of the adjacent rolls of the pass being mutually inclined, about said pass line, at 12cup.

5. A mill according to Claim 4 wherein one roll of one pass is rotatable about a horizontal axis disposed above a pass line of the mill whilst one roll of the or another pass is rotatable about a horizontal axis disposed below said pass line of the mill.

6. A mill according to any one of the preceding claims wherein at least one roll of at least one pass is driven to transport the workpiece through the mill.

7. A mill according to Claim 6 wherein all the rolls of all the passes are driven so that each successive roll exerts a tractive force on a workpiece and so transports the workpiece through the mill.

8. A mill according to any one of the preceding claims wherein a separate transport means is provided to transport the workpiece through the mill.

9. A mill according to any one of the preceding claims wherein the rolls of each pass are arranged to effect at least a 5% reduction in the crosssectional area of the workpiece prior to entry into the pass.

10. A mill according to any one of the preceding claims wherein rolls of the passes are arranged so that there is no change in shape of the workpiece on passage through each pass.

11. A mill according to any one of the preceding claims in combination with means to introduce a further component into a tubular blank and means to feed the thus occupied blank to said reducing mill.

12. A mill according to Claim 11 further comprising means to form an initial workpiece of strip configuration to an intermediate product of tubular configuration and means to join the adjacent edges of the thus formed intermediate product and thus provide said tubular blank.

13. A mill substantially as hereinbefore described with reference to the accompanying drawings.

14. Any novel feature or novel combination of features described herein and/or shown in the accompanying drawings.