US3831242A

US3831242A - Rolling mill work roll assemblies

Info

Publication number: US3831242A
Application number: US00394882A
Authority: US
Inventors: R Oxlade
Original assignee: British Iron and Steel Research Association BISRA
Current assignee: British Iron and Steel Research Association BISRA
Priority date: 1968-12-10
Filing date: 1973-09-06
Publication date: 1974-08-27
Anticipated expiration: 1991-08-27
Also published as: GB1373594A; GB1298065A; FR2025796A1; DE1961942C3; DE1961942B2; DE1961942A1; US3803683A; SE367137B; US3851365A

Abstract

A method of manufacturing a rolling mill work roll assembly which comprises a work roll held in position on a hollow shaft member by the shaft member being in a stressed condition to exert radial loading and preferably also axial loading on the work roll. The grip is sufficient to transmit normal driving torque. The method comprises axially stretching the shaft by hydraulic pressure means acting within the hollow, and this causes reduction of the diameter of the hollow shaft to permit insertion and removal of the shaft into and from the work roll bore. The hollow shaft has a larger diameter than the work roll bore when not so stretched. After insertion the hydraulic pressure is removed and the shaft assumes the above stressed condition.

Description

United States Patent [191 Oxlade [451] Aug. 27, 1974 ROLLING MILL WORK ROLL ASSEMBLIES [75] Inventor: Roy Ronald Oxlade, London,

England [73] Assignee: The British Iron and Steel Research Association, London, England [22] Filed: Sept. 6, 1973 [21] Appl. No.: 394,882

Related US. Application Data [62] Division of Ser. No. 881,801, Dec. 3, 1969.

[30] Foreign Application Priority Data Dec. l0, 1968 Great Britain 58650/68 [52] US. Cl. 29/l48.4 D, 29/452 [51] Int. Cl B23p 11/00, B2ld 39/00 [58] Field of Search 29/l48.4 D, .452, 148.4 R,

[56] References Cited UNITED STATES PATENTS 3,577,6l9 5/1971 Strandel 29/l48.4 D

3,633,259 [/1972 Nikanen 29/l48.4 D

Primary Examiner-Thomas l-l. Eager Attorney, Agent, or Firm-Sughrue, Rothwell, Mion, Zinn & Macpeak ABSTRACT A method of manufacturing a rolling mill work roll assembly which comprises a work roll held in position on a hollow shaft member by the shaft member being in a stressed condition to exert radial loading and preferably also axial loading on the work roll. The grip is sufficient to transmit normal driving torque. The method comprises axially stretching the shaft by hydraulic pressure means acting within the hollow, and this causes reduction of the diameter of thehollow shaft to permit insertion and removal of the shaft into and from the work roll bore. The hollow shaft has a larger diameter than the work roll bore when not so stretched. After insertion the hydraulic pressure is removed and the shaft assumes the above stressed condition.

4 Claims, 4 Drawing Figures r I 403318 42 32 21 so 1 ROLLING MILL WORK ROLL ASSEMBLIES This application is a division of my application Ser. No. 881,801 filed Dec. 3, 1969.

This invention relates to methods of manufacturing work roll assemblies for use in rolling mills. Particular applications for such assemblies may be found in two high or in four or more high rod or bar mills, embodiments of the latter being disclosed for example in US. Pat. Nos. 3,587,267; 3,611,531 and 3,613,428.

It is generally desirable that mill work rolls be removable so that they can be exchanged for different rolls to permit a variety of rod or bar sizes and shapes to be rolled on the same mill and also to permit worn rolls to be replaced. The work rolls are accordingly removably carried on roll drive shafts which are rotatably mounted and driven in the mill frame. The mounting of the roll on the shaft so as to facilitate the ready removal thereof whilst still enabling the roll to withstand the heavy rolling loads without damage to the mounting or shaft is a continuing problem for the mill designer.

An object of the invention is accordingly to provide a method of manufacturing a work roll assembly so that it is readily removable from the drive shaft.

According to the present invention there is provided a method of manufacturing a rolling mill work roll assembly, said assembly comprising a hollow shaft member which is coaxially secured to or formed integrally with a work roll drive shaft which extends co-axially in a bore of a work roll, said work roll including an annular member formed to define a rolling groove or surface of the work roll, said method including applying a force axially to stretch said shaft member to cause sufficient diametrical reduction thereof to permit insertion thereof into its assembled position in said work roll bore, said shaft member when not so stretched having a diameter too large to permit such insertion, and removing said applied force to cause the shaft member to assume a stressed condition in which it exerts radial loading outwardly on said work roll to provide radial location of said work roll with respect to said shaft member.

In preferred embodiments of the invention the annular member is supported on both sides by sleeve members. Accordingly the ring member may be of, e.g. tungsten carbide and the sleeve of, e.g. steel. The tungsten carbide provides a long, accurate roll groove life, which resists wear, thermal shock and rolling fatigue. The roll groove thus has the advantages of tungsten carbide but the roll as a whole is not so heavy or as expensive as a solid tungsten carbide roll would be. Moreover if the annular member is damaged, it is readily replaceable, without the necessity of replacing the steel sleeve member. A damaged tungsten carbide solid roll would have to be scrapped as a whole. The provision of a composite roll in this manner which can readily be dis-assembled, also provides thefadvantages of ease of handling, and the storage bulk of the mill inventory of different groove size rolling mer'ribers is reduced. Finally the composite roll can, in some forms, be more adequately cooled in use.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

FIG. 1 is a longitudinal section of a work roll which forms part of an assembly according to the invention for use in a four or more high rod or bar mill,

FIGS. 2 and 3 are longitudinal sections of .work roll assemblies according to the invention, also for use in a four or more high mill, and 1 FIG. 4 is a longitudinal section showing embodiments of an assembly for use in a two high mill.

FIG. 1 shows a composite work roll fabricated as first and second separable supporting sleeve parts indicated generally at 10 and 11, and a ring or sleeve member 12 provided with a single circumferential rolling groove 13. The sleeves have

axial bores

14 and 15. The first sleeve has an outer end portion presenting a recess 16 for a purpose to be described below. The inner end portion of the first sleeve presents an annular seat 17 accurately perpendicular to the roll axis, and a vestigial spigot 18 radially inward of the seat 17.

The second sleeve 11 has an outer end portion adapted to locate the roll axially and radially on a work roll shaft as will be explained below. The inner end portion of the second sleeve presents an annular surface 20 perpendicular to the roll axis, and a frusto conical spigot 21 radially inward of the seat 20. Spigot 21 converges away from the sleeve 11 and terminates in an annular face 22 opposed to an annular face 23 presented by the end face of the spigot 18.

The ring member 12 has a constant cross-section in the general shape of a trapezium. The parallel annular side faces 30, 31 are perpendicular to the roll axis. The axial length of the ring is equal or marginally less than the summed axially lengths of spigots l8 and 21.

The inner surface of the central aperture of the ring 12 is a frusto conical surface 32'over the major portion of its axial length, the cone angle, axial length and datum diameter of surface 32 being substantially equal to the corresponding external dimensions of spigot 21. The remainder of the inner surface of the central aperture of ring 12 is a cylindrical surface 33 substantially equal in diameter and axial length to the diameter and axial length of spigot 18.

Two diametrically opposed pairs. of registering axially directed key-

ways

40, 41 are provided, the key-ways of each pair being formed in the inner surface of the ring 12 and in the outer surface of the spigot 2l.'A key member 42 is shaped for sliding movement into each said pair of key-ways.

The outer end portion of the second sleeve 11 is constructed in the same manner as the equivalent end portion of the work roll particularly described in and with reference to FIGS. 2 and 3 of the drawings of our copending Pat. application Ser. No: 52086/67. Briefly the end portion presents an axial recess 50 shaped to receive a work roll shaft spigot, an annular seating surface 51 radially outward of the recess 50, and a curved wall key member 52 extending circumferentially of the part 11 to slightly less than 180 of the roll circumference. Recess 50 locates the roll radially on the shaft spigot, surface 51 locates the roll axially on the shaft seat, and key member 52 mates with a key-way and an optional wedge associated with a work roll shaft substantially to prevent backlash between the roll and its shaft.

In use the three parts l0, l1 and 12 of the work roll, and key members 42, are assembled as shown in the drawings. The work roll is then mounted to a work roll shaft by means of a hydraulic hollow bolt (not shown) extending from within an axial bore in the shaft and through

bores

14 and 15 of the work roll. A nut is threaded on the end of the bolt. A radial face of the nut bears against the annular face within the recess 16 of part 10. When the nut has been tightened on the bolt and the bolt has been de-pressurised to relax into a state of considerable axial tension, it will be seen that the

parts

10, 11 of the roll are urged axially together into pre-loaded engagement. The annular seat 17 on part provides axial support and location in one axial direction for the ring shape part 12. Support and location for part 12 in the other axial direction is provided basically by tapered spigot 21 engaging tapered surface 32 of ring 12. This latter engagement also provides radial support and location for ring 12 on part 11.

Parts

10 and 12 are located radially by the engagement of vestigial spigot 18 and surface 33. Backlash between ring 12 and part 11 which is the driven part of the roll is substantially prevented by friction assisted by key members 42, which also serve to drive the ring 12.

The support parts llland 11 would normally be of steel and the ring member 12 of tungsten carbide. An advantage of this embodiment is thus that the ring member 12, which is the part containing the groove 13 and thus most subject to wear in use, can be made of considerably harder and longer lasting material than the remainder of the work roll. Expense of making the whole roll of hard wear resistant material is thus avoided, and similarly it may be possible to achieve a work roll whose

support parts

10, 11 and ring 12 wear at substantially the same rate, although part 12 is subject to greater wear in use. Moreover the roll is separable into parts and thus a worn ring can readily be replaced. ln addition the ring 12 can readily be replaced by a ring defining a differently shaped rolling groove 13. In another embodiment ring 12 may be provided with two or more rolling grooves.

Furthermore tungsten carbide is approximately twice as heavy as steel, so the weight of a solid tungsten carbide roll would render the roll difficult to handle. Finally,

parts

10 and 11, which in use roll on a back up roll surface, could be formed of a fatigue resistant steel not suitable for roll groove material but with longer life when serving only to define a back up work roll contact surface.

If necessary, instead of or in addition to keying, the roll part may be glued or brazed together and/or the roll may be glued or brazed to the drive shaft.

Referring now to FIG. 2 there is shown a longitudinal section of a work roll assembly for a four or more high rod or bar mill comprising a work roll mounted on a hollow shaft member 60 secured to a drive shaft 61. The work roll comprises a ring member 62 defining a rolling groove 63. The ring member 62 is axially l0- cated and supported by two

sleeve members

64, 65. The three

members

62, 64, 65 are mounted on hollow shaft member 60 which has a threaded end portion 66 received in a threaded recess 67 in the end of the drive shaft 61. A head flange 68 on the hollow shaft member engages sleeve 64, and an annular seat 69 on the end of shaft 61 engages sleeve 65. Consequently flange 68 and seat 69 provide axial location in both directions for the work roll.

The member 60 serves as a form of hydraulically expansible bolt. In its unassembled unstressed state its diameter is slightly greater than the diameter of the bore through the parts of the composite work roll. In order to insert the member 60 through the bores, the member 60 is axially stretched by hydraulic pressure means acting internally thereof. The axial stretching is accompanied by a diametrical shrinkage sufficient to permit the three roll parts to be mounted on the member 60. The member 60 is then threaded into the drive shaft 61 and tightened thereon by simple mechanical means, this is, no special effort is made to tighten it very securely. The hydraulic pressure within the hollow is then released, thus causing the member 60 to expand in diameter, so far as it is able, and to shrink in axial length, to assume a stressed condition.

The diametrical expansion causes the member 60 to exert substantial radial loading on the

work roll members

62, 64 and 65 whereby to locate them radially (provided their relative bore diameters are correctly chosen in relation to the bolts diameter); and the axial shrinkage causes the member 60 to exert substantial axial loading on the work roll members by means of flange 68 and seat 69.

It should be noted that the threaded portion on the head of the hollow shaft member 60 serves for attachment of a valved pressure device through which the hydraulic pressure fluid is forced to build up on the head of a plunger. The tail of the plunger engages the inner end of the hollow, whereby to cause the hydraulic pressure to act directly to stretch the bolt and permit its diameter readily to shrink as described. When in use the hollow in the bolt is protected from dirt by a dust cap shown e.g., at 88 in FIG. 3.

If desired additional location can be afforded by keying means, such as mating spigots, on the roll members and the drive shaft, one such being shown schematically at 70.

The torsional drive of the roll is transmitted by virtue of a combination of the axial clamping force and the radial grip which effectively also comprehends circumferential location by friction. The drive from the drive shaft 61 to the roll is provided by the key 71, similar to that described in relation to FlG. 1. If desired two or more similar keys spaced circumferentially may be used. The torque transmission capability can be enhanced, if desired, by keying means acting between the assembled parts, e. g., knurling the outer surface of the member 60, providing keys between the roll sleeves, or by glueing or brazing mating surfaces of the roll sleeves, or the outer peripheries of the three

members

62, 64 and 65 can be provided with mating noses and recesses.

Referring now to FIG. 3, two embodiments are shown in the upper and lower halves of the drawing respectively. In each embodiment a hollow shaft member acts in a similar manner to the hollow shaft member 60 described in relation to FIG. 2, except that in this case it is formed integrally with the drive shaft 61. Consequently, it is not possible to place the work roll

sleeves

81, 82 and 83 on the hollow shaft member from the right hand end thereof. In the upper half of the figure the valved pressure device, which threads on the head 84 of the hollow shaft member, is of larger diameter than the bore of the

sleeves

81, 82 and 83. Thus the sleeve cannot be mounted from the left hand end when the member 80 is pressurized.

To solve this difficulty the hollow shaft member is either given a gradual taper (not shown) or is stepped as shown at 85 and 86. The sleeves are of appropriate internal diameters as shown. To assemble the assembly, the sleeves are placed on the unpressurized unstressed member 80 onto diameters displaced one step to the left of their final position. The valved pressure device can then be attached to threaded portion 84 and the member pressurized. The sleeves can then be moved one step to the right onto their final positions as shown, and the bolt then depressurized to assume a stressed condition to provide location as described above in relation to FIG. 2. In this case a nut 87 or other locking device serves the purpose of flange 68.

In the lower half of FIG. 3 the inner diameter of the hollow shaft member 80 is threaded at 89 and the valved pressure device for use in pressurizing the bolt is dimensioned to be wholly of less diameter than the bores of the sleeves. Consequently the sleeves can then be placed in position on the member 80 over the pressure device, thus avoiding the need for

steps

85 and 86.

Referring now to FIG. 4, there is shown a work roll assembly for a two high mill, and four embodiments are partly illustrated in this Figure.

In the first embodiment a plurality of work roll grooved rings 90 are spaced along a hollow shaft member 91 and are maintained in position, radially and axially, simply by the stressed condition in member 91 exerting sufficient radial loading thereon. The torque transmission capability can be enhanced if required by knurling the member 91 or providing flats or keys between the ring bore and the member 91, or by glueing or brazing the rings to the member 91. Cooling of this embodiment would be very efficient since cooling fluid could penetrate the annular grooves between adjacent rings 90.

The hollow shaft member is shown as formed integrally with a drive shaft 92 and is supported for rotation on two chocks 93, provided with suitable roller bearings 94. The chocks and member 91 are axially mutually located by virtue of the slow taper of shaft portions 95, and by end nuts 96.

FIG. 4 also shows, in its lower half, rings 90 spaced by spacing rings 97. The sequence of

alternate rings

90 and 97 are axially clamped and located between a flange 98 on the member 91 and a nut 99, which is tightened before de-pressurizing of the hollow shaft member 91 in a similar manner as described before. In this embodiment, of course, the radial loading by member 91 is not essential, since the axial loading and location can be sufficient to transmit the necessary torque.

This Figure also shows rings 90 spaced by spacing rings 100 which are trapezium shaped in cross-section and taper inwardly, the taper matching outer bevels 101 on the rings 90. Spacing rings 102 are also shown, which are trapezium spaced and taper outwardly, the taper matching undercut bevels 103 on the rings 90. The rings 100 are usually preferable since their hoop stress in use exerts compression on the rings 90, whereas rings 102 cause extra tension in rings 90. When the rings 90 are of tungsten carbide, compressional forces are more suitable to the material. In the latter two embodiments the angles of the trapezium are chosen to compensate for any difference between the co-efficients of thermal expansion of the material of the work roll rings and the material of the hollow shaft member.

Many advantages of the above described embodiment have already been given, but finally it should be noted in addition that the use of composite work rolls which are radially loaded or axially loaded, or preferably both, by a stressed hollow shaft member, leads to a stiffer work roll assembly (where stiffness means the deflection of a selected point per unit load) than many of the assemblies in use at the present time.

The drawings have shown work rolls with rolling grooves. In applying the invention to flat strip mills, the work rolls would have cylindrical rolling surfaces instead of the grooves.

I claim:

II. A method of manufacturing a rolling mill work roll assembly, said assembly comprising a hollow shaft member which is co-axially secured to or formed integrally with a work roll drive shaft and which extends co-axially in a bore of a work roll, said work roll including an annular member formed. to define a rolling groove or surface of the work roll, said'method including applying a force axially to stretch said shaft member to cause sufficient diametrical reduction thereof to permit insertion thereof into its assembled position in said work roll bore, said shaft member when not so stretched having a diameter too large to permit such insertion, and removing said applied force to cause the shaft member to assume a stressed condition in which it exerts radial loading outwardly on said work roll to provide radial location of said work roll with respect to said shaft member.

2. A method as claimed in claim 1 wherein said applied force is removed to cause the shaft member to assume a stressed condition in which it causes exertion of both radial loading outwardly on said work roll and axially compressive loading between the axially opposite end faces of the work roll whereby to provide respectively radial location and axial location of said work roll with respect to said shaft member.

3. A method as claimed in claim 1 wherein said axial stretching force is applied by hydraulic pressure means acting internally of said hollow shaft member.

4. A method of manufacturing a rolling mill work roll assembly, said assembly comprising a hollow shaft member which is co-axially secured to or formed integrally with a work roll drive shaft and which extends co-axially in a bore of a work roll, said work roll including an annular member formed to define a rolling groove or surface of the work roll, said method including applying a force axially to stretch said shaft member to cause sufficient diametrical reduction thereof to permit insertion thereof into its assembled position in said work roll bore, said shaft member when not so stretched having a diameter too large to permit such insertion, providing first and second axial loading means in engagement with the respective axially opposite end faces of the annular member while the hollow shaft member is in said inserted and stretched condition, and subsequently removing said applied force to cause the hollow shaft member to assume a stressed condition in which simultaneously the hollow shaft member exerts radial loading outwardly on said work roll to provide radial location of said work roll with respect to said hollow shaft member and said axial loading means exert axially compressive loading between said axially opposite end faces of the work roll to provide axial location of said work roll with respect to said hollow shaft member.

Claims

1. A method of manufacturing a rolling mill work roll assembly, said assembly comprising a hollow shaft member which is coaxially secured to or formed integrally with a work roll drive shaft and which extends co-axially in a bore of a work roll, said work roll including an annular member formed to define a rolling groove or surface of the work roll, said method including applying a force axially to stretch said shaft member to cause sufficient diametrical reduction thereof to permit insertion thereof into its assembled position in said work roll bore, said shaft member when not so stretched having a diameter too large to permit such insertion, and removing said applied force to cause the shaft member to assume a stressed condition in which it exerts radial loading outwardly on said work roll to provide radial location of said work roll with respect to said shaft member.