US3546908A - Hydraulically adjustable rolling mill having a transducer unaffected by piston deformation - Google Patents

Description

Dec. 15, 1970 J. L. RUSSELL 3,546,903 Y HYDRAULICALLY ADJUSTABLE ROLLING MILL HAVING A TRANSDUCER UNAFFECTED BY PISTON DEFORMATION Filed May 9, 1968 8 Sheets-Sheet 1 o a Q S a J. L. RUSSELL Dec. 15, 1976 HYDRAULICALLY ADJUSTABLE ROLLING MILL HAVING A TRANSDUCER UNAFFECTED BY PISTON DEFORMATION' a Sheets-Sheet 2 Filed May 9, 1968 Dec. 15, 1970 7' J. LLRUSSELL V r 3,546,908

HYDRAULICALLY ADJUSTABLE ROLLING MILL HAVING A TRANSDUCER UNAFFECTED BY PISTON DEFORMATION Filed May 9, 1968 8 Sheets-Sheet 3 Dec. 15, 1970 J. L. RUSSELL 3,546,908

HYDRAULICALLY ADJUSTABLE ROLLING MILL HAVING A TRANSDUCER UNAFFECTED' BY PISTON DEFORMATION Filed May 9; 1968 I 8 Sheets-Sheet 4 RAM AND

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ROS/HON TRANSDUCER SERVO VALVE SERVO AMPLIFIER L. RUSS LE ROLLING ELL 3,546,908

MILL HAVING A TRANSDUCER DEFORMATION Dec. 15, 1970 J HYDRAULICALLY ADJUSTAB UNAFFECTED BY PISTON 8 Sheets-Sheet 5 Filed May 9, 1968 ril ,llllflllllfllllllll uv Dec. 15, 1970 J. RUSSELL 3,546,908

HYDRAULICALLY ADJUSTABLE ROLLING MILL HAVING A TRANSDUCER UNAFFECTED BY PISTON DEFORMATION Filed May 9, 1968 8 Sheets-Sheet 6 1970 J. L. RUSSELL 3,546,908

HYDRAULICALLY ADJUSTABLE ROLLING MILL HAVING A TRANSDUCER UNAFFECTED BY PISTON DEFORMATION Filed Mgy 9, 1968 I a Sheets-Sheet 7 3,546,908 Inc A TRANSDUCER TION 8 Dec. 15, 1970 J. L. RUSSELL HYDRAULICALLY ADJUSTABLE ROLLING MILL A UNAFFECTED BY PISTON DEFO Filed May 9, 1968 Sheets-Sheet 8 United States Patent Ofice 3,546,908 Patented Dec. 15, 1970 3,546,908 HYDRAULICALLY ADJUSTABLE ROLLING MILL HAVING A TRANSDUCER UNAFFECTED BY PISTON DEFORMATION James Langley Russell, Clifton, England, assignor to British Aircraft Corporation (Operating) Limited, London, England, a British company Filed May 9, 1968, Ser. No. 728,014 Claims priority, application Great Britain, May 10, 1967, 21,792/67 Int. Cl. B21b 37/08 US. Cl. 7221 Claims ABSTRACT OF THE DISCLOSURE A rolling mill including a servo mechanism responsive to the spacing between the rolls for controlling a hydraulic mechanism which in turn adjusts the roll spacings.

A piston and cylinder, especially of the large diameter-short stroke size, incorporates a two part seal that permits tilting relative movement while maintaining hydraulic pressure. A transducer is effectively isolated from deformation of the piston by a bar incorporated in the underface of the piston.

, There is a growing demand from the sheet metal industries for metal strip that is accurate and uniform both in gauge, that is in thickness, and in width. This invention is concerned with mechanism for achieving accuracy and uniformity in gauge, but is also applicable to a mill which rolls material having a shaped profile in section.

According to this invention, a mill for rolling material comprises work rolls between which the material can be rolled, means mounting the rolls in a manner to permit adjustment of the spacing between them, hydraulic mechanism for effecting the adjustment, and servo mechanism for controlling the hydraulic mechanism which servo mechanism is responsive to the spacing between the rolls to maintain a selected setting of the spacing between the rolls.

With such a mill, the servo mechanism will act to cause the hydraulic mechanism to return the rolls to a selected spacing should, in use, the rolls tend to depart from that selected spacing.

Several mills for rolling metal according to the invention will now be described, reference being made to the accompanying diagrammatic drawings in which:

FIG. 1 is a section on the line 11 of FIG. 2;

FIG. 2 is a view of a rolling mill in the direction 2-2 of FIG. 1 with certain parts omitted;

FIG. 3 is an enlarged view of the hydraulic actuating mechanism, partly in section;

FIG. 4 is an enlarged view of part of FIG. 3;

FIG. 5 shows the circuit of the servo mechanism;

FIG. 6 is a part section through an alternative hydraulic actuating mechanism;

FIG. 7 is an enlarged view of part of FIG. 6;

FIG. 8 is a view of the actuator with an end wall removed to show the electrical and hydraulic mechanism; and

FIG. 9 is a part section through the actuator.

Referring first to FIGS. 1 to 5 which show one steel rolling mill, a fixed mill housing is shown at 10. The housing is fixed by suitable means 10a to a fixed support 10b (not shown in FIG. 2). Upper and lower work rolls 11, 12 and a back-up roll 13 are mounted in the housing 10. There may be a fixed backing roll, similar to roll 13, for the roll 12. The rolls '11, 12, 13 are on rotatable spindles 11a, 12a, 13a respectively which are carried on bearings in mountings 11b, 12b, 13b. The mounting 12b is fixed. The roll 11 is adjustable vertically with respect to the roller 12, as is the roll 13, to vary the spacing between the rolls 11 and .12 to thereby vary the gauge or thickness of the steel after it has passed through the work rolls 11, 12. To achieve this the mountings 11b, 13b are vertically adjustable in the housing 10. The spindles are mounted by bearings in chocks 11a, 12d, 13d. The chocks 11a, 13d are vertically adjustable in guides 130.

The steel is reduced in thickness as it passes between the work rolls 11, 12 and the mountings of the rolls 11, 12, 13 must be able to withstand the consequent forces between the rolls for example up to 6000 tons. The rolls 11, 12, are rotated by suitable driving mechanism for example electric motors 40. The two motors 40 are synchronised together by known mechanism whereby they rotate at the same speed. Other suitable driving means could be used, as will be known to the skilled man. Electrically driven screw jacks 14, mounted on the housing 10, and driven by an electric motor shown diagrammatically at 14a, are used to provide coarse adjustment of the spacing between the rolls 11 and '12. The above details are generally conventional and will not be described further.

In the mill according to the invention, fine adjustment of the spacing is effected by hydraulic actuators .15 disposed between the screw jacks 14 and the mountings 13b for the back-up rolls 13.

Each hydraulic actuator 15 comprises a lower housing part 16, FIG. 3, which bears on the mounting 13b for the back-up roll 13 and an upper part 17 which can be engaged by the extensible part of the screw jack, shown diagrammatically at 18. The jack '18 engages an abutment pad 19 having a curved upper surface and which is screwed into the upper part 17. Passages 20, 2.1 extend through the lower part 16 and communicate respectively with upper and lower chambers '22, 23 defined between the parts 16 and 17. An annular seal 24 prevents escape of hydraulic fluid from chamber 22 and a similar seal 25 prevents communication between the chambers 22 and 23. The seals 24, 25 are carried in recesses formed between the part 17 and further parts 26, 27 secured by bolts 28 to the part 17. Hydraulic fluid is supplied through the passages 20, 21 under the control of a servo valve 30 mounted on a fixed part and under the control of a position transducer 31 shown diagrammatically in FIG. 3. A servo amplifier 32 is included in the servo circuit. When it is desired to move the roll 11 closer to the roll 12, either to select the initial setting or in response to a signal from the position transducer 31, hydraulic pressure is supplied under the control of a manually operable valve 30b from a pressure source 30a through the valve 30 to the chamber 23 causing the cylinder .16 to move downwardly relative to the piston 17. Likewise, when it is desired to move the roll 11 away from the roll 12, hydraulic pressure in chamber 23 is reduced under operation of servo valve 30. Thus the actuators 15 not only provide fine adjustment of the initial setting, but in association with the other parts act to maintain that setting during use.

The pad 19 allows the piston 17 to rotate when the screw jack 14 is rotated during coarse adjustment of the spacing between the rolls 11, 12.

The seals 24, 25 which are best shown in FIG. 4 although the O-rings and seals are omitted from the left hand side for clarity, comprise annular metal members 40 which are restrained against axial movement and have two circular (in plan) grooves 41a of rectangular cross section in each axial face, each groove receiving an O-ring 41, and having two grooves 42 in their curved radial surfaces 43. Each groove 42 receives a sealing ring comprising an outer polytetrafluoroethylene (P.T.F.E.) member 44 which is fixed to and urged radially outwardly by a rubber expander member 45. The radial surface 43 is formed as part of a sphere and the arrangement is such that the piston 17 may tilt relatively to the axis and the seals 24, will still remain. effective without leaking or jamming. This arrangement is particularly suitable for a piston such as that shown which has a comparatively large ratio of diameter to axial length. The stroke of the piston 17 may be for example up to 0.1 inch, and it may tilt up to 0.1 inch without leakage or jamming, that is to say the surface 43 during tilting may move axially 0.1 inch.

The piston 17 acts as a high efliciency thrust bearing.

Robust and well protected terminations are used for the hydraulic and electrical connections to the apparatus.

The position transducer may be of any suitable design and as shown comprises a position responsive member 51 controlling the movement of a hydraulic piston 33 in a cylinder 34 fixed to cylinder 46 and which is connected to the valve 30, through the amplifier 32, so that the valve may respond to the output from the cylinder 34.

The servo circuit is shown in FIG. 5 and is a known arrangement which need not be further described. The load is the one exerted by the feed stock as it passes between the rolls 11, 12.

An alternative and preferred arrangement is shown in FIGS. 6 to 9. Parts similar to those of FIGS. 1 to 5 are given the same reference numerals. The pad 19 is held to the part 17 by a number of bolts and its surface is coated with P.T.F.E. to give a sliding contact between it and the jack 14. Up to 3000 tons force may be transmitted between these parts. A ring of bolts 46 holds a wedge-shaped member 47 to the part 17 and a single annular seal 50, generallysimilar to the seals 24, 25 but with O-rings only on its lower face and having flat periphery, is disposed between the member 47 and a downwardly facing shoulder 48 formed in a recess 49 in the part 17. The seal 50 has two grooves 41a in its lower face and two grooves 42 in its flat radial face. These grooves 41a and 42 contain rings 41 and rings 44, 45 as in FIG. 4. An annular cover 81 is held to the part 17 by bolts 52. The cover prevents entry of dirt between the relatively movable parts 16, 17.

The wedge-shaped member 47 is formed with grooves 53 which receive sealing O-rings.

The pad 19 may be force lubricated through channels 54. A drain is shown at 54a.

Hydraulic fluid is fed to the chamber 23 through an inlet 21.

It is possible that because of the tremendous axial loads (up to 3000 tons) existing in the actuator during operation, there may be a tendency for the piston part 17 to bow thereby causing the transducer to give an incorrect position reading. This is largely avoided in the arrangement of FIGS. 6 to 9. A trough 55 is formed in the lower face of the part 17 and a fiat bar 56 is bolted to the base of the trough by bolts 57. The upper surface of the bar 56 is formed with two longitudinal ridges 58 extending across the bar. The upper surfaces of the ridges are each at the location of zero deflection of the piston 17. The tranducer responds to the under face of the bar 56. The piston 17 may bow into the space between the base of the trough and the upper face of the bar 56.

The position transducer is best seen in FIG. 7 and has a central rod 60 the upper end of which engages the underface of the bar 56. The rod 60/ can slide in a bore in a member 61 fixed by bolts 62 to the part 16. A cap 63 is fixed by bolts 64 to the member 61 and surrounds the upper end of the rod 60. Annular seals are shown at 65. The rod 60 is biased into engagement with the bar 56 by a spring 66 acting between a shoulder 67 in the member 61 and a land 68 on the rod. Seals are shown at 68a.

Fixed to the rod 60 is a central extension 69 forming a magnetic core for a stator 70 connected through cables 71 to the servo amplifier. Movement of the core 69 axially from a null position causes an electrical error signal to be sent to the servo amplifier 32 to operate the servo valve in known manner to supply hydraulic fluid to the cylinder 16 to effect the appropriate adjustment of the spacing between rolls 11 and 12. This electrical arrangement is in contradistinction to the hydraulic arrangement of FIGS. 1 to 5.

As the piston 17 moves upwardly (as shown in FIG. 7) pressure fluid will flow from chamber 23 to space 71 and thence down annular passage 72 around the upper part of member 61, through channel 73 in member 61 to the annular space which houses the spring 66 so that the spring is assisted by the fluid pressure in keeping the rod in engagement with the bar 56.

A drain for fluid which may leak past seals is shown at 74.

Thus the transducer core 69 will not move relative to the stator unless the piston 17 has moved physically in the axial sense, as distinct from simply bending or bowing.

FIG. 8 shows the electrical and hydraulic pack fixed to part 16. A hydraulic filter is shown at 60, hydraulic supply and return at 62, electrical connections at 63, an electronics pack for the various controls at 64 and a hydraulic accumulator at 65.

In an alternative arrangement, the cylinder part 16 could be above the piston part 17.

In the arrangements described above, the hydraulic actuator enables the axis of the jack 18 to be slightly offset from or inclined to the axis of the actuator whilst still enabling the mill to function. This is because the part 17 may tilt to a certain extent whilst still remaining effective.

Also a pressure tranducer can be made responsive to the pressure in the chamber 23 to give a reading of the load on the mill, without the transducer itself experiencing that load as it would do if it were disposed between the jack and the roll 13.

The actuator could be incorporated in a mill which had rolls shaped to roll workpieces which are shaped in section, e.g. T-shaped, and acts to control the crosssection of the rolled workpiece.

The actuator can be included in mills which roll metal, e.g. steel or aluminium, and it may find application in mills which roll plastics material.

I claim:

1. A mill for rolling material comprising work rolls between which the material can be rolled, means mounting the rolls in a manner to permit adjustment of the spacing between them, hydraulic means including a cylinder and a piston having a relatively short stroke and large diameter relationship for effecting such adjustment, means for sealing the piston and cylinder, servo means including a position transducer for controlling the hydraulic means, the servo means being responsive to the spacing between the rolls to maintain a selected setting of the spacing between the rolls, the face of the piston having a recessed portion with a base, a bar fixed in the recessed portion, two parallel longitudinal ribs projecting from the bar and engaging the base of the recess, the position transducer being responsive to the location of the bar, whereby any bowing of the piston during operation will not substantially effect the position transducer.

2. A mill for rolling material as in claim 1 where the means for sealing further includes a first annular member mounted to the piston and restrained against axial movement relative to the piston, and a second annular two part member mounted in the first annular member for radial movement relative to the first annular member, one part of the second annular member having an outer sealing face urged radially outward with respect to the piston by the other part of the second annular member and into sealing engagement with the wall of the cylinder, the outer surface of the first annular member being spaced from the wall of the cylinder enabling the first annular member to tilt relatively to the cylinder.

3. A mill for rolling material as in claim 1 where the piston is located above the cylinder and has fixed to its upper end a pad with a curved upper surface, the means for mounting the rolls including a screw jack engaging the curved surface of the pad whereby axial adjustment of the screw jack provides coarse adjustment of the setting between the Work rolls.

4. A mill for rolling material as in claim 3 where the means for sealing the piston and cylinder is located in the piston and includes at least two members, the first member having an outer sealing face contacting the cylinder wall and the second member radially urging the first member into contact with the cylinder wall.

5. A mill for rolling material comprising work rolls between which the material can be rolled, means mounting the rolls in a manner to permit adjustment of the spacing between them, hydraulic means including a cylinder and a piston having a relatively short stroke and large diameter relationship for effecting such adjustment, means for sealing the piston relative to the cylinder, servo means including a position transducer for controlling the hydraulic means, the servo means being responsive to the of the spacing between the rolls, the means for sealing 6 further includes a first annular member mounted to the spacing between the rolls to malntain a selected setting piston and restrained against axial movement relative to the piston, and a second annular two part member mounted in the first annular member for radial movement relative to the first annular member, one part of the second annular member having an outer sealing face urged radially outward with respect to the piston by the other part of the second annular member and into sealing engagement with the wall of the cylinder, the outer surface of the first annular member being spaced from the wall of the cylinder, enabling the first annular member to tilt relatively to the cylinder.

References Cited UNITED STATES PATENTS 2,040,755 5/1936 Meyer 72-6 2,573,353 10/1951 Nieman 72245X 3,285,049 11/1966 Neumann 72246 3,286,495 11/1966 Diolot 728 3,389,588 6/1968 Reinhardt et al. 728

MILTON S. MEHR, Primary Examiner US. Cl. X.R. 72245

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