Roll for a rolling mill

Abstract: A roll for a rolling mill comprises a roll body (20) including a portion (19) which affords a rolling surface and is integral with a cylindrical bearing portion (18) for rotationally supporting the roll at each end thereof. The roll body (20) affords an internal bore in each longitudinal half thereof, the inner portion (23,24) of which is tapered and receives at least one piston (25 to 28) which together with a shaft (29,30) in the outer portion (21,22) of the bore defines at least two liquid chambers (33 to 37) to which pressurised liquid may be selectively applied to move the piston longitudinally into and out of contact with the tapering surface of the associated bore to deform the rolling surface.

Description: The present invention relates to a roll for a rolling mill of the type having a rolling surface of variable shape and is concerned with that type of roll which comprises a roll body including a portion which affords a rolling surface, a cylindrical bearing portion for rotationally supporting the roll at each end thereof, the roll body affording an internal longitudinally tapering surface on each longitudinal half thereof and at least one longitudinally movable piston which partially defines at least two liquid chambers to which pressurised fluid may be selectively applied to move the piston into and out of contact with the associated tapering surface to deform the rolling surface. Figures 1 and 2, which are a sectional side view and a schematic view illustrating the application of forces to the roll, respectively, show a known roll of this type. A sleeve 3 which affords a rolling surface is fitted, e.g. by shrink or expansion fitting, to the central barrel of a roll core 2 with cylindrical bearing portions at each end by means of which the roll is rotatably supported in bearings 1. The roll has an annular recess in each end which is partly defined by an inwardly directed annular tapered surface 4 on the sleeve 3 which is divergent towards the respective end of the sleeve 3 and also partly defined by the outwardly directed cylindrical surface of the core 2. Each recess 5 is thus defined between the core 2 and respective tapered surface 4. Piston rings 6 and 7, each having a tapered outer surface, are axially slidably fitted over the core 2 and within each recess. The recess 5 has a liquid-tight seal comprising a sealing ring 8 and pressurised liquid chambers 9,10 and 11 are thus defined between the closed end of the recess 5 and the ring 6, between the rings 6 and 7 and between the rings 7 and 8, respectively. Chambers 9,10 and 11 communicate with liquid passages 12,13 and 14, respectively, which are formed in the core 2 and communicate with an external source of pressurised liquid. In use, liquid is supplied to the chambers 9,10 and 11 and pressure may be applied to or released from the liquid thus causing the tapered piston rings 6 and 7 to be axially displaced and thereby urged into engagement with or disengaged from the inner surfaces of the respective recess 5. Accordingly, the sleeve 3 may be deformed and the shape of the rolling surface altered. A known roll of the type described above is disclosed in, for example, US Patent No.4599770. Such rolls may be used in a rolling mill as work rolls, intermediate rolls and/or back-up rolls and are useful when rolling workpieces with a variety of widths. Furthermore, the variable shape of the rolls enables the thickness of a workpiece to be varied along its width. However, the type of roll described above has the following disadvantage: When rolling forces F are applied to the roll, the roll is deflected as shown in Figure 2. In the example of Figure 2 the inside (the upper surface in Figure 2) of the core 2 is distorted less than the outside (the lower surface in Figure 2) of the core 2. However, the sleeve 3 is distorted to substantially the same degree on each side. The sleeve 3 is thus axially displaced or deformed with respect to the core 2 by an amount indicated by reference numeral 15 in Figure 2. Once such sliding axial displacement occurs between the roll core 2 and the sleeve 3, the roll remains deflected even when the rolling forces are removed since the displacement is fixed by virtue of the tight fit between the sleeve 3 and the core 2. In subsequent rolling operations, the deformed roll rotates eccentrically which results in a non-uniform thickness distribution over the length of the workpiece. It is thus the primary object of the present invention to provide a roll for a rolling mill of the type referred to above which will return to its undeformed state when the rolling forces are removed after having been deflected by the application of rolling forces. Another type of roll is disclosed in US4557028, which comprises a sleeve, with integral bearing portions, which is cast around a central arbor so that the arbor becomes integral with the bearing portions of the sleeve, and a small space is left between the central portion of the arbor and the inside of the sleeve. The shape of the sleeve may be altered by inflating this space using pressurised fluid fed through channels in the arbor. The preamble of Claim 1 is based on US4599770, however. According to the present invention a roll of the type referred to above is characterised in that the roll body is integral with the bearing portions. In other words, the roll comprises a roll body including a portion, which affords a rolling surface, said roll body affording tapered spaces extending longitudinally in bearing portions for rotationally supporting said portion and in said portion and at least one longitudinally moveable piston engageable and disengageable in said spaces which defines at its opposite sides liquid chambers to which pressurised fluid may be selectively applied to deform the rolling surface, characterised in that the roll body and the bearing portions are formed by an integral member. It is preferred that a bore extends axially into the roll body from each end thereof and that the inner portion of each bore is longitudinally tapered and accommodates at least one piston and the outer portion of each bore accommodates a shaft, each shaft defining together with the adjacent piston a pressurised fluid chamber. In one embodiment of the invention the two bores communicate at the longitudinal centre of the roll body, whereby there is effectively only a single bore which passes through the entire length of the roll body, and the two pistons adjacent the longitudinal centre of the roll body together define a pressurised fluid chamber. In an alternative embodiment the inner ends of the two bores are separated by a web which together with the two adjacent pistons defines two pressurised fluid chambers. A respective liquid passage communicating with each pressurised fluid chamber is required in order to apply fluid pressure to the piston or one of the pistons defining that fluid chamber and these preferably pass through one or each shaft and communicate with a rotary joint adapted to be connected to a source of pressurised fluid. In other words, liquid passages are formed in one or both of the shafts and respectively communicate with a rotary joint connected to a source of pressurised fluid. The liquid passages may all pass through a single liquid supply rod which extends through one shaft and the pistons and into the other shaft or alternatively they may be formed directly in one or both shafts and pass through the pistons. The rotary joint preferably comprises a substantially cylindrical member having liquid passages formed therein which open at the outer peripheral surface thereof and a member having a substantially cylindrical recess for relatively rotationally accommodating said cylindrical member and having further liquid passages formed therein which are opened at the inner peripheral surface of the recess, annular grooves being formed at the interface between said members to connect the said liquid passages with the said further liquid passages. In one embodiment liquid supply passages are formed in a liquid suuply rod extending through one shaft and through the pistons, said liquid supply passages being opened to a respective pressurised fluid chamber. Further features and details of the invention will be apparent from the following description of four specific embodiments of the invention which is given by way of example with reference to Figures 3 to 16 of the accompanying drawings, in which: Figure 3 is a longitudinal section through the first embodiment of the present invention; Figure 4 is a scrap longitudinal section, on an enlarged scale, of one of the rotary joints of the first embodiment; Figures 5 to 10 are diagrammatic front elevations, partly in section, of a number of four-high rolling mills incorporating rolls of the first embodiment; Figure 11 is a front elevation of a two-high rolling mill incorporating rolls of the first embodiment; Figure 12 is a front elevation of a five-high rolling mill incorporating rolls of the first embodiment; Figure 13 is a front elevation of a six-high rolling mill incorporating rolls of the first embodiment; Figure 14 is a longitudinal section through the second embodiment of the present invention; Figure 15 is a longitudinal section through the third embodiment of the present invention; and Figure 16 is a longitudinal section through the fourth embodiment of the present invention. Referring firstly to Figures 3 and 4, the first embodiment of the present invention comprises a roll body 20 having a central barrel 19 which affords a rolling surface and a cylindrical bearing portion 18 at each end which, in use, is supported by a bearing 16 in a bearing box 17. The roll body 20 has axially extending cylindrical spaces 21 and 22 bored in it at each end adjacent which are frusto-conical spaces 23 and 24 bored on each side of its centre. The frusto-conical spaces are contiguous with the cylindrical spaces 21 and 22 thereby providing a bore extending over the entire length of the roll body 20. The diameter of the frusto-conical spaces 23 and 24 decreases progressively towards the centre of the barrel 19. The frusto-conical spaces 23 and 24 accommodate axially movable tapered pistons 25 to 28 whose outer surfaces contact the inner surfaces of the frusto-conical spaces 23 and 24. The cylindrical spaces 21 and 22 accommodate cylindrical shafts 29 and 30 which have threaded bores 31 in them at the ends of the roll body in which screws, e.g. set screws 32, are received. The frusto-conical spaces 23 and 24 are thus tightly sealed against the passage of liquid. The shafts 29 and 30 and the pistons 25 and 28 have cut away portions on their inner surfaces and the two central pistons 26 and 27 are separated by a projection on the inside surface of the bore within the roll body and/or by the extent of inward axial movement permitted by their geometry. First, second, third, fourth and fifth pressurised liquid chambers 33 to 37 are thus defined between the shaft 29 and the piston 25, between the pistons 25 and 26, between the pistons 26 and 27, between the pistons 27 and 28 and between the pistons 28 and 30, respectively. A liquid supply rod 38 for supplying a liquid under pressure extends axially from one end of the roll body 20 through the shaft 30 and the pistons 28,27,26 and 25 and into the shaft 29. The rod 38 has a recess 39 at the end adjacent the end of the roll body 20 which accommodates a bearing 41 which rotatably supports a rotary joint 40. The rotary joint 40 has a number of annular grooves 42 to 46 which communicate with an external source of pressurised liquid (not shown) via respective liquid passages 47 to 51 in the rotary joint 40. The liquid supply rod 38 has liquid passages 52 to 56 which communicate with respective annular grooves 42 to 46 and also with respective pressurised liquid chambers 33 to 37. Thus, liquid under pressure can be supplied from the external liquid source to the liquid chambers 33 to 37 through the liquid passages 47 to 51, the annular grooves 42 to 46 and the liquid passages 52 to 56; the liquid in the chambers 33 to 37 may also be discharged back into the external liquid source. Annular seals 57 on the inner surface of the recess 39 engage the rotary joint 40 between adjacent annular grooves 42 to 46, as shown in Figure 4. When liquid is supplied under pressure to the second and fourth chambers 34 and 36, the pistons 26 and 27 are urged in the axial direction towards the centre of the roll body 20 and they thus exert a radially outward force on the inner surface of the frusto-conical spaces 23,24 at the centre thereof. As a result, a small portion at the centre of the roll body 20 is forced to expand, as indicated by the broken lines A in Figure 3. When liquid is supplied under pressure to the first and fifth liquid chambers 33 and 37 whilst the second and fourth chambers are pressurised as described above, the tapered pistons 25 and 28 are forced in the axial direction towards the centre of the roll body 20. As a result a larger portion of the roll body is forced to expand, as indicated by the broken line B in Figure 3. When liquid is supplied under pressure to the third liquid chamber 35, the tapered pistons 25 to 28 are forced to move in the axial direction away from the centre of the roll body 20 and are thereby disengaged from the surfaces of the frsuto-conical spaces 23,24. The roll body then returns to its original undeformed cylindrical shape, free of irregularities. Thus by varying the pressure applied to each liquid chamber 33 to 37, the tapered pistons 25 to 28 may be engaged with or disengaged from the surfaces of the tapered spaces 23 and 24 so that the outer configuration or shape of the roll body 20 can be varied at will. When a rolling force is applied to the roll body 20, it is of course deflected in the usual manner. However, since the barrel 19 is integral with the cylindrical bearing portions 18, instead of being a sleeve mounted on a core which is supported in bearings, there is no relative sliding displacement between the barrel 19 and the bearing portions 18. Accordingly, when the rolling force is removed, the roll body 20 can return to its original undeformed state. Shafts 29 and 30, fitted into each end of the roll body 20, are rigidly supported in the region of the bearings 16 and are therefore substantially free from deflection. The only parts of the shafts which may be deformed are those extending into the region of the barrel 19, designated C, and these are relatively small. Moreover, the surfaces of the shafts 29 and 30 are relatively near the axis of the roll body 20 and are accordingly deflected less. In addition, the shafts 29 and 30 are attached to the roll body 20 only by the screws 32 and there is no substantial contact pressure against the inner surfaces of the cylindrical spaces 21,22 in distinction to the prior construction where there is a shrink or expansion fit between the core and the sleeve. The shafts can thus easily return to their original state if any relative sliding displacement should have occurred between the shafts and the inner surfaces of the cylindrical spaces 21,22. Accordingly, the presence of the shafts does not prevent the roll body from recovering from deflection after the rolling force has been removed. It should be noted that even when the shafts 29 and 30 are in fact shrink-fitted or expansion-fitted into the roll body 20, the displacement of the shafts 29 and 30 relative to the roll body 20 is negligible, for the reasons outlined above. Referring next to Figure 5, a four-high rolling mill comprises work rolls 59 which engage a workpiece 58 and back-up rolls 60 which apply a rolling force to the work rolls. In this mill, the back-up rolls are variable shaped rolls of the type described above. When the workpiece 58 to be rolled is narrow, the inner tapered pistons 26 and 27 are forced inwards and engage with the surfaces of the frusto-conical spaces while the outer tapered pistons 25 and 28 are disengaged. Each of the back-up rolls 60 then has a central raised portion of slightly larger diameter than the remainder of the barrel, as shown by the broken line A in Figure 3. The raised portion defines the effective length of the roll along which rolling forces are transmitted to the workpiece 58 through the work roll 59. In order to roll a somewhat wider workpiece 58, all the tapered pistons 25,26,27 and 28 are forced inwards. Each of the back-up rolls 60 then has a rather larger raised central portion than when only the inner pistons are forced inwards, as described above. The raised portion in this case is indicated by the broken line B in Figure 3. In order to roll an even wider workpiece 58, the tapered pistons 25,26,27 and 28 are all disengaged. Each roll 60 is then undeformed and the rolling forces are transmitted along the entire length of the barrel 19. Thus the formation of a crown on the workpiece 58 can be prevented by adjusting the back-up rolls so that the rolling forces are transmitted to the work rolls only over a length which corresponds to the width of the workpiece 58. The tapered pistons 25 to 28 can be engaged or disengaged independently from each other so that the back-up rolls 60 may assume a variety of shapes. As a result, it is possible to control the distribution of the thickness of the workpiece along its width. Generally, in a four-high rolling mill, the back-up rolls are supported at their ends by vertically immovable supports while the work rolls are supported at their ends by vertically movable supports. Therefore, eccentric rotation of the work rolls, if it occurs, will not adversely affect the distribution of thickness of a workpiece along its length. The bearing portions of the work rolls will move vertically as the rolls rotate to compensate for their eccentricity, and the height at which the rolling force is applied to the workpiece will remain constant. However, eccentric rotation of the back-up rolls will cause the height of the work rolls and thus the height at which the rolling force is applied to vary in the vertical direction and thus adversely effect the distribution of the thickness of the workpiece along its length. However, when the rolls according to the present invention are used in the rolling mill as described above, this problem does not occur since the back-up rolls do not develop an eccentricity, for the reasons already described. Referring to Figure 6, a four-high rolling mill may have work rolls 59 in accordance with the invention. Alternatively, the back-up and work rolls 59 and 60 may be in accordance with the invention, as shown in Figure 7. A roll according to the invention may be used as one of a pair of back-up rolls 60 (Figure 8) or work rolls 59 (Figure 9). The invention is also applicable to rolling mills having shift capability, that is the capability for the work rolls to be moved laterally of the direction of movement of the workpiece. Such a mill is shown in Figure 10. Furthermore, the rolls in accordance with the present invention may be used as work rolls 59 in a two-high rolling mill as shown in Figure 11; they may also be used in three-high rollings mills; they may also be used as, for example, intermediate rolls 115 in a five-high rolling mill as shown in Figure 12; they may also be used as, for example, intermediate rolls 115 in a six-high rolling mill as shown in Figure 13. Roll bending systems may of course be incorporated in the rolling mills shown in Figures 6 to 13. The second embodiment shown in Figure 14 is substantially the same as the first embodiment described above with reference to Figures 3 and 4 except that the pressurised liquid is supplied to the liquid chambers 33 to 37 without the use of liquid supply rods. The liquid chamber 63 is defined between a projection 61 of the piston 25 and a recess 62 in the shaft 29. Similarly, a liquid chamber 66 is defined between the projection 64 and the piston 27 and the recess 65 in the piston 28; and a liquid chamber 69, between the projection 67 on the piston 28 and a recess 68 in the shaft 30. Rotary joints 70 and 71 are attached to opposite ends of the roll body 20. Thus liquid is supplied under pressure from the rotary joint 70 to the first liquid chamber 33 through a liquid passage 72 in the shaft 29. Similarly, liquid is supplied under pressure from the rotary joint 70 to the second liqud chamber 34 through a liquid passage 73 in the shaft 29, the liquid chamber 63 and the liquid passage 74 in the piston 25. Liquid is also supplied under pressure from the rotary joint 71 to the third liquid chamber 35 through a liquid passage 75 in the shaft 30, a liquid chamber 69, a liquid passage 76 in the piston 28, a liquid chamber 66 and a liquid passage 77 in the piston 27. In like manner, liquid is supplied from the rotary joint 71 to the fourth liquid chamber 36 through a liquid passage 78 in the shaft 30 and a liquid passage 79 in the piston 28. Liquid is also supplied from the rotary joint 71 to the fifth liquid chamber 37 through a liquid passage 80 in the shaft 30. The second embodiment is substantially the same as the first embodiment apart from the features referred to above and has the same advantages and effects. The third embodiment shown in Figure 15 is substantially the same as the first and second embodiments except that the tapered pistons 25 to 28 are located nearer to the ends of the barrel 19 and the third liquid chamber 35 shown in Figure 3 and Figure 14 is divided into two liquid chambers 82 and 83 by a solid portion or web 81. In the third embodiment the ends of the barrel 19 may be forced to expand under the influence of the pistons 25 to 28 rather than the centre portion, as in the first and second embodiments. Reference numeral 84 designates a projection on the piston 26; 85, a through-hole in the piston 25 through which the projection 84 extends. Numeral 86 designates a recess in the shaft 29; 87, a liquid chamber defined between the projection 84 and the recess 86; 88, a projection on the piston 27; 89, a through-hole in the piston 28 through which the projection 88 extends; 90, a recess in the shaft 30, 91, a liquid chamber defined between the projection 88 and the recess 90; and 92 to 101, liquid passages. Liquid can be supplied under pressure to the liquid chambers 33,34,82,83,36 and 37 in a manner substantially similar to that described in relation to the second embodiment. The fourth embodiment shown in Figure 16 is substantially the same as the first to third embodiments except that the tapered pistons 26 and 27 of these embodiments are replaced by a single tapered piston 102. Reference numeral 103 represents a projection on the piston 25; 104, a recess in the shaft 29; 105, a liquid chamber defined between the projection 103 and the recess 104; 106, a projection on the piston 28; 107, a recess in the shaft 30; 108, a liquid chamber defined between the projection 106 and the recess 107; and 109 to 114, liquid passages. As in the second or third embodiment, liquid can be supplied under pressure to the liquid chambers 33,34,36 and 37, respectively.

Claims: A roll for a rolling mill comprising a roll body (20) including a portion (19), which affords a rolling surface, a cylindrical bearing portion (18) for rotationally supporting the roll at each end thereof, the roll body (20) affording an internal longitudinally tapering surface (23,24) on each longitudinal half thereof and at least one longitudinally movable piston (25,26,27,28) which partially defines at least two liquid chambers (33 to 37) to which pressurised fluid may be selectively applied to move the piston into and out of contact with the associated tapering surface to deform the rolling surface, characterised in that the roll body (20) is integral with the bearing portions (18). A roll as claimed in claim 1 in which a bore (21,23;22,24) extends axially into the roll body (20) from each end thereof, characterised in that the inner portion (23,24) of each bore is longitudinally tapered and accommodates at least one piston (25,26,27,28) and the outer portion (21,22) of each bore accommodates a shaft (29,30), each shaft (29,30) defining together with the adjacent piston (25,28) a pressurised fluid chamber (33,37). A roll as claimed in claim 2, characterised in that the two bores (21,23;22,24) communicate at the longitudinal centre of the roll body (20) and that the two pistons (26,27) adjacent the longitudinal centre together define a pressurised fluid chamber (35). A roll as claimed in claim 2, characterised in that the inner ends of the two bores (21,23;22,24) are separated by a web (81) which together with the two adjacent pistons (26,27) defines two pressurised fluid chambers (82,83). A roll as claimed in any one of claims 2 to 4, characterised in that liquid passages (52 to 56;72,73 75,76;93,95,97,99;109,110,112,114) extend through one or each shaft (29,30) and communicate with respective pressurised fluid chambers (33 to 37) and with a rotary joint (40) adapted to be connected to a source of pressurised fluid. A roll as claimed in claim 5, characterised in that the rotary joint (40) comprises a substantially cylindrical member having liquid passages (47 to 51) therein which terminate at the peripheral surface thereof and a member (38) which affords a cylindrical recess accommodating the cylindrical member and having liquid passages (52 to 56) which terminate at the cylindrical surface of the recess, one of the members being rotatable and the other being fixed, in use, each passage (42 to 46) communicating with a respective passage (52 to 56) via a respective annular groove (42 to 46) formed in one of the said surfaces. A roll as claimed in claim 5 or claim 6, characterised in that a liquid supply rod (38) in which liquid supply passages (52 to 56) are formed extends through one shaft (30) and through the pistons (25 to 28) and that the liquid passages (52 to 56) extend through the supply rod (38) and communicate with a respective pressurised fluid chamber (33 to 37). A roll as claimed in claim 5 or claim 6, characterised in that liquid supply passages (72,73,75,78) extend through the two shafts (29,30) and communicate with a respective pressurised fluid chamber (33 to 37) either directly or through a further fluid passage (74,76,77,79) passing through one of the pistons.

Inventors: IMAI ISAO, KATO HEIJI, NITANDA MASAO, OYAUCHI TSUKASA, YOSHIDA MASUJIRO, IMAI, ISAO, KATO, HEIJI, NITANDA, MASAO, OYAUCHI, TSUKASA, YOSHIDA, MASUJIRO
Applicants: ISHIKAWAJIMA HARIMA HEAVY IND, ISHIKAWAJIMA-HARIMA  JUKOGYO KABUSHIKI KAISHA
Application year: 1990
Main classification: B21B27
IPC codes: B21B27