US2938706A

US2938706A - Roll changing device

Info

Publication number: US2938706A
Application number: US442041A
Authority: US
Inventors: Langen Mathias
Original assignee: Loewy Engineering Co Ltd
Current assignee: Loewy Engineering Co Ltd
Priority date: 1953-07-09
Filing date: 1954-07-08
Publication date: 1960-05-31
Anticipated expiration: 1977-05-31
Also published as: FR1103957A; GB750425A; DE969430C

Description

May 31, 1960 M. LANGEN ROLL CHANGING DEVICE 4 Sheets-Sheet l Filed July 8, 1954 ATTORNEYS lgs/VENTOR Mcnhlos Lungen M, LANGEN ROLL CHANGIN May 31, 1960 G DEVICE 4 Sheets-Sheet 2 Filed July 8, 1954 VVV VVV fr /r v ON ATTORNEYS M. LANGEN ROLL CHANGIN May 31, 1960 G DEVICE 4 Sheets-Sheet 3 Filed July 8. 1954 ATTORNEYS M. LANGEN ROLL CHANGING May 31, 1960 DEVICE 4 Sheets-Sheet 4 Filed July 8. 1954 H vz/E/vroR Mo'rhlas Lungen ATTORNEYS RLL CHANGING DEVICE Mathias Langen, Parkstone, Dorset, England, assignor to The Loewy Engineering Company Limited, Loudon, England, a corporation of Great Britain Filed July 8, 1954, Ser. No. 442,041

Claims priority, application Great Britain July 9, 1953 2 Claims. (Cl. 254-106) This invention relates to a roll changing device for a rolling mill and, in particular, to a roll changing device in which the rolls are inserted into the mill stand or withdrawn therefrom by being moved sideways with respect to the mill stand.

Roll changing devices of this type are particularly useful in connection with rolling mills in which the separating forces are considerable, such as four-high mills, and where, consequently, large screwdown gears are required, as the sideways movement of the rolls makes it possible for the rolling mill housings to have closed tops, whereby their strength and rigidity are greatly improved, particularly in that part which accommodates the Screwdown gear.

A roll changing device of the type above referred to comprises generally a movable support or carrier in the form of a Sledge receiving the rolls, together with any attachments, Such as their bearings or chocks, the sledge being adapted to be moved sideways with respect to the rolling mill Stand along a track to a point outside and adjacent the mill stand where the rolls can be taken oi the Sledge and replaced by another roll assembly.

The weight of a roll assembly to be carried by the sledge is often very heavy, and the forces required for moving the Sledge with a roll assembly loaded thereon are therefore considerable.

Various proposals have been made in the past for displacing the Sledge of a roll changing device sideways into and out of a rolling mill stand. None of these was, however, quite satisfactory.

Movement of the Sledge by ropes connected to'the lifting tackle of a travelling crane lacked precise control, a disadvantage which was particularly apparent when moving the rolls into position inside the mill Stand. The use of ropes necessitated also the arrangement of pulleys at both sides of the mill stand. This was inconvenient because space at least on one side of the mill is always restricted by the rolling mill drive.

It has further been proposed to provide a roll changing device with shifting means, permanently connected to the Sledge, whereby a more precise control of its movement is achieved.

These means consisted either of a nut traversing a threaded spindle, or of a hydraulic cylinder with a double-acting piston displaceable therein. The length of the spindle and that of the cylinder were determined by the distance between the two extreme positions of the Sledge. If this distance was great, as in the case of mills having rolls of great barrel length, the spindle and the cylinder became Very expensive and cumbersome. Building up a long cylinder from a number of shells joined endwise together was found to be inexpedient for various reasons.

It is an object of the present invention to provide a roll changing device for rolling mill stands comprising a movable support or a carrier in the form of a Sledge,

States Patent C rerice having improved means for Shifting said sledge in or out of the rolling mill stand.

The shifting means according to the invention are of the hydraulic type and they comprise accordingly a pres- Sure-fluid cylinder and a double-acting piston. Of these two elements, one is connected directly to the Sledge, while the other canslide along a track and be immobilized at spaced-apart and pre-selected points 'on that track. The track for the slidable 'element may be the same as that for the sledge.

The element 'connected to the Sledge is preferably formed by the double-acting piston, and the slidable element formed by the cylinder, although the arrangement can be reversed. Displacement of the piston in the cylinder, with the cylinder locked to the track, will result in a corresponding displacement of the Sledge along its track. Displacement of the piston in the cylinder, with the cylinder free to slide along the track and the sledge loaded with a set of rolls, will result in -a corresponding displacement of' the cylinder along the track, as the piston and the Sledge will be immobilized by the weight of the rolls on the Sledge. In this way, the cylinder can be moved towards or away from the mill stand by a distance equal to the stroke of the piston.

This arrangement and mode of operation permits the movement of the Sledge along its track by a total distance which is a multiple of the stroke of the piston relative to the cylinder, simply by alternately admitting pressure-fluid to opposite sides of the piston and freeing or locking the cylinder to the track at alternate Strokes of the piston.

It will be realised that, in this way, the length of the stroke of the piston, and accordingly the length of the cylinder required for moving the sledge in or out of the mill Stand by a given distance, can be greatly reduced and need only be a fraction of the stroke which would otherwise be required to move the Sledge by the same distance. The Shifting means according to the invention are therefore comparatively simple and inexpensive and do not require excessive space for their accommodation adjacent the rolling mill stand.

According to a further feature of the invention, control means are provided for alternately admitting pressure-duid to opposite Sides of the double-acting cylinder.

Locking means may be provided for immobilizing the slidable elements at spaced-apart and pre-selected points along its track. These locking means may be in the form of pivoted pawls engageable in notches provided at spacedapart and pre-selected points along the track.

The invention will now be described by way of example with reference to the accompanying drawings, which show one embodiment of the invention:

Fig. 1 is a front elevation showing a roll changing device according to the invention applied to a four-high rolling mill, with its hydraulic shifting means in section.

Figs. 2, 3, 4, 5 and 6 show, on a somewhat larger scale, various positions which the hydraulic Shifting means take up during a movement away from and towards the rolling mill stand.

Fig. 7 is a plan view of the roll changing device of Fig. 1.

Fig. 8 is a cross-section through the hydraulic shifting means according to line 8 8 of Fig. l.

Fig. 9 is a cross-section through the hydraulic shifting means according to line 9--9 of Fig. 1.

Referring to Fig. 1, the rolling mill, to which the roll changing device according to the invention is applied, is generally designated with 10. It is shown here as a fourhigh mill comprising

work rolls

11, 12 and back-up rolls 13, 14. The chocks for the four rolls 11 to 14 are not separately shown as they are immaterial for the 'present first pull-out movement of the sledge 20.

invention; -they areV-locatedvwithin the spaces 15 and 16 at both sides of the rolls. The four rolls and their chocks form together the roll assembly 17 and will be referred to as such in the following description.

The roll' changing device comprises a sledge 20 which ,is adapted to receive the roll assembly 17 and which can be moved together with a roll assembly into and sideways out of the rolling mill stand 10. The sledge 20 is movable along a track 21 by hydraulic shiftingV means generally designated-by 22. These means comprise a cylinder element 23 and a double-acting piston element 24. The piston has a piston rod 25 which, at its end, carries a hook 26 adapted to enter a notch 27 in the sledge 20. The cylinder 23 is displaceable along the same track as the sledge 20, and its base-plate 28 is provided to this end with shoes 29v slidable along the track V21 (Fig. 9).

- Attached to the cylinder 23, at both of its sides, are double-acting pawls 30 which can swing in opposite directions about pins 31 formed on cylinder bosses 32 (Fig. 8). These pawls co-operate with notches 33 arranged on the track 21 at stations A, B and C which are spaced-apart by a distance equal to the stroke length of the piston 24. AtV each of these three stations there are on each side of the track two notches 33 which form together dovetails 34 on the track 21. The notches 33 on the mill stand side of the dove-tail 34 are engaged by the pawls 30 during the inward travel of the Sledge and the notches at the opposite side of the dove-tail at the outward travel of the Sledge. Each pawl 30 has accordingly two lugs with inclined faces 35 which can be alternately made to engage` one of the two notches 33 at opposite sides of a dove-tail 34 by tilting a pawl 30 about its pivot pin 31. Tilting of the pawls 30 is effected by means of weighted rocking arms 36 attached tothe pawls.V The transition from a notch 33 to the upper level of the track 21 is formed by a slope 37 which acts as a cam-face for tilting a pawl on its becomingdisengaged from a notch, so that Ythe pawl can ride and pressure-fluid is, therefore, admitted to the right of the piston 24, whilst the pressure-fluid on the leftof the piston is exhausted. This results in a movement of the cylinder 23 to the right, i.e., away from the mill stand 10, with the piston 24 remaining stationary, as the weight of the roll assembly carried by sledge 20 is much in excess of that of the cylinder 23 and immobilizes the sledge and the piston. During this movement, the pawls 30 ride over the slopes 37 of the notches 33 whereby the pawls are tilted slightly. The stroke of the cylinder 23 during this step has the same length as that.of the piston 24 during the iirst pull-out movement, the cylinder 23 occupying at the end of its stroke theposition shown in Fig. 3vwith the pawls 30 engaging the notches at station B, whereby they immobilize the cylinder in its new position.

The hydraulicY shifting device 22 is now ready for another stroke of the piston 24. This is effected by reversing again the connections of the hydraulic cylinder 23 by means of the hydraulic control valve 44, pressureiiuid being admitted to the left of the piston 24 yand exhausted from the right, in the same way as during the iirst step. The piston, together With the sledge 20, is thereby moved Yaway'from the mill stand 10 by another stroke length, its position at the end of the stroke and that of the Sledge hook 26 beingV indicated in dotted lines in lig. 3. This is the second pull-out movement.

The hydraulic pressure-huid connections are thereupon again reversed by means of the control valve 44 which results in the displacement of the cylinder, 23 along the track 21 whilst the sledge 20 remains stationary owing to the weight of the roll assembly 17 (Fig. 4).

. The cylinder 23 moves until the pawls 30 enter the freely along the track'21 until it drops'into the next notch 33. Hydraulic pressure-fluid is supplied to the cylinder 23 by means of

flexible hoses

38, 39 which are connected at their ends to

lixed pipes

40, 41 and 42, 43 respectively. The `admission of pressure-huid to the cylinder 23 is controlled by a hand-operated valve 44, or any other suitable means.Y A pump, not shown here, is provided as a source of supplyof pressure-fluid. f Y

' 4T'he stops 45 and 46 at opposite ends of the track-21 `preventover-travel of the shifting means 22 in vboth VVdirections.

Stops

45, 46 co-operate with ears 47 protruding from the four corners of the base-plate'28. Y

The track 21 for the shifting means 22 is preferably located in a pit below iloor level, a second somewhat deeper pit being provided alongside the track for accommodating the loops formed by the flexible hoses 38 and 39 (Figs.

o sand9),

(The operation of the hydraulic shifting means 22 will now be-described in detail with reference Ytothe Figs. 2,

3, 4,V 5 and V6: Before the removal of a Vroll assembly 17 from the mill stand 10, the parts have the positions shown inFig. 2,

witlrthe hydraulic cylinder 23 being immobilized on the Y track V21 through the pawls 30 engaging the'notches 33 wat A. In this position, the ears 47 are close to the stops 45 on the track 21, although not in actual contact with them.

Pressure-fluid is now admitted to the left of piston 24, whereby the latter is moved towards the right. This kcauses the sledge 20, with a roll assembly 17, to be pulled out of the rolling mill stand 10 by'a distance corresponding Vto the stroke of the piston. The positions of the piston 24 at the end of the stroke and of the sledge hook 26 Vare indicated inl dotted lines in Fig. 2. This step forms the The Vcontrol valve 44 is now operated .so as to reverse Vthe pressure and exhaust-connections to the cylinder 23 notches 33 at station C. In this position, the 'ears 47 at the right-hand end of the base-plate 28 are very close to thestops 46, although not in actual engagement with them.

This is followed by a further reversal of the pressure- Vfluid connections, resulting in a displacement of the piston 24 along the track 21 whilst the cylinder 23 is immobilized through the pawls 30 having entered the notches at station C. This forms the third pull-out movement. The Sledge 20V is now in a position in which the roll assembly 17 can be'lifted therefrom and'replaced by another rollas'sembly which is to take the place of the iirstY one in the mill stand 10. v

For. the return movement of the Sledge 20, pressurefluid is admitted tothe right-hand side of piston 24. VVThis will cause the cylinder 23 to movev a short distance to the right until the ears 47 and-the stops 46 are in engage- -mentwith each other (Fig. 5), whereby the pawls 30 are caused to become disengaged from their notches 33 at C. The pawls 30 can then be swung about their Y pivot pins 31 by Vmeans ofthe actuatinglevers 36,'as

soV

,arrangement of the shifting means.

together with the sledge 20, to move to the left. Fig. 5

shows the piston 24 and the sledge 20 in their positions at the end of lthis stroke. This completes the lirst pushback movement. Y

The cylinder 23 is now moved towards the mill stand 10 by reversing the position of the controlvalve 44, with the sledge being immobilized` owing .to the weight of the roll assembly. The cylinder travels back until its pawls 30 enter the notches 33 at B. The alternate movements of piston 24 and cylinder 23 are-repeated, as indicatedin Fig. 6, until the cylinder has reached the position in which its pawls 30 enter the notches 33'at A, and until the sledge 20 is inside the rolling mill stand 10.

It will be seen that the entire stroke of the Sledge 20 between its two extreme positions is carried out in three steps. This Yresults in reducing the stroke requiredfrom the piston and, thereby, also the length of the cylinder, by two-thirds, with a consequent simplicatlon inthe It is preferred to move the cylinder 23V at a higher the variable delivery type is very Well suited to these conditions as this type of pump gives a high output at slow speeds, and a small output at high speeds.

of shifting means having a The invention is capable of embodiments other than those shown here. The operation of the shifting means can be made automatic by providing electric limit switches alongside the track which actuate the hydraulic control valve for the pressure-duid if and vwhen the cylinder and What I claim is:

1. In combination, a horizontal track and self-propelled shifting means carried by said track for shifting a load along said track, said shifting means comprising a double comparatively short stroke.'

ment of said load, and said latching means when moved to said upon admission of pressure fluid to one of the sides of