GB2118468A - Improvements in or relating to roll stands - Google Patents

Abstract

The chock 34 of the lower work roll 36 is fitted with telescopic supports 1, 6 engageable with blocks 45. The supports are capable of resiling during rolling but become rigid during roll changing so as to prevent contact between the roll surfaces. <IMAGE>

Description

SPECIFICATION Improvements in or relating to roll stands The upper and lower rolls of a stand of a rolling mill may constitute a set which is removable as a unit.

During the insertion and removal of the rolls it is very important to ensure that the cylindrical surface of the upper roll does not rest on that of the lower roll. Various devices have hitherto been proposed and used for holding the upper roll above the lower roll during roll changing but none has proved satisfactory.

To overcome this problem, it is proposed that use should be made of supports which are capable of holding the upper roll at a fixed distance above the lower roll during the roll changing operation, but which can resile during the rolling operation.

Although the present proposal has particular application to a Konti-tandem train, in which the rolls are changed while rolled material remains in the stands, it is of quite general application. Each of the supports may be in the form of a telescopic assembly having a housing associated with either the upper or lower work roll, although it is preferred for it to be mounted on the service side chock of the lower roll.

Within the housing is an extension component, conveniently in the form of a pin. Assuming the housing is fixed to the lower chock then, during the rolling operation, the pin may be pressed down into the housing of each support against a spring bias as the upper chock bears down upon it. A locking arrangement is provided within the housing and is activated to secure the pin in a raised position during the roll changing operation. Conveniently, the locking arrangement is actuated and deactuated by a toothed segment which is supported rotatably by the housing and meshes with a toothed rack in the roll stand. In this way, a very simple locking arrangement may be employed.

The locking arrangement may include lugs which project from the pin and are supported on a shoulder within a sleeve which is rotatable by the toothed segment. Vertically extending grooves in the sleeve allpw the pin to be depressed when the sleeve is rotated sufficientlyfarto align with the grooves.

The manufacture of the pin may be simplified by forming the lugs on a nut which is screwed onto the pin. The housing may have a vertical passage extending throughout its length and be sealed by upper and lower covers which have openings dimensioned to permit the passage of the pin. The lower cover may be fast with the toothed segment and be secured to the sleeve by means of screws.

The pin may be biased in the vertically upward direction by a compression spring extending between a collar on the pin and an internal shoulder within the sleeve. The collar on the pin abuts against the upper cover of the housing when the pin is in its uppermost position.

Preferably, the toothed segment meshes with the rack in such a way that the sleeve turns about the pin by 90" during movement of the roll set. The rack may be stationary and arranged in the roll counterbalancing block, although it falls within the scope of the present proposal for the rack to be actuated to re-set the support. To prevent the sleeve moving of its own accord relative to the pin, under the influence of vibrations for example, it may be held in place by a detent when the support is in its relaxed condition, in which the lugs are aligned with the grooves in the sleeve.

In the drawings: Figure 1 is an axial section through a support in accordance with the present proposal, Figure 2 is a cross-section taken on the line I-I in Figure 1, Figure 3 is a cross-section taken on the line ll-ll in Figure 1, Figure 4 is a view through the window of the stand showing the service side of the stand on the left of the drawing, and the drive side on the right of the drawing, and Figure 5 is a plan view of the service side of the stand, showing the parts associated with the lower roll on the left side and the parts associated with the upper roll on the right side of the drawing.

Referring initially to Figure 4 and 5, a four-high roll stand has a frame with windows 28 accommodating upper and lower support rolls 32, 32A and upper and lower work rolls 35 and 36. The support rolls are mounted in fitting members or chocks 29 and the work rolls in fitting members or chocks 33 and 34. In accordance with Konti rolling mill practice, the work rolls are replaced at intervals. The operation is performed using pairs of rails 37 pertaining to the upper work roll and pairs of rails 38 pertaining to the lower work roll. The rails 38 are rigidly fixed in the roll stand window 28 whereas the rails 37 have fixed and rigid central portions to which are pivoted movable end portions 37a both on the service and drive sides of the stand. The end portions 37a may be adjusted in position by piston and cylinder units 47,49 mounted on the crossbeams 48 of the stand.

On the service side i of the stand, the rail end portions pivot about the joint shown at 51 and slope downwards from this joint. After insertion of the new roll set, the end portions 37a may be moved from the positions shown in full lines into the positions indicated by chain lines by retracting the piston and cylinder units, in order to make space available for the movement of the chocks during operation of the rolls.

During the removal of the roll set which takes place with the wheels 40 of the chocks 34 running on the rails 38, and the wheels 40a of the chocks 33 running along the rails 37, the upper work roll assembly is lowered onto the lower work roll assembly as the wheels 40a run down the sloping rail portion 37a. If it were not for the provision of the devices to be hereinafter described, this movement would lead to the upper work roll 35 coming to rest on the lower work roll 36. In order to maintain the constant clearance between the rolls, even when the are outside the roll stand, the lower chock on the service side I has two telescopic supports 1, one of which is shown on the left hand half of Figure 4.The chock on the drive side as shown in the right hand half of Figure 4 is provided with catches 41 on the lower chock which strike against stops 42 on the upper chock when the roll set moves on the wheels 40 and are either raised or lowered.

Referring now in more detail to Figure 5, the left and right hand halves of which show the upper and lower parts of the stand, it will be seen that each of the supports 1 has a housing with a flange which is bolted onto the lower chock 34 by means of bolts in holes 44 seen in Figure 2. Within the housing is a vertically movable pin 6 capable when raised of engaging in a pocket 46 in a block 45 bolted on a projection 43 of the upper chock 33 in line with the pin 6, see the right hand half of Figure 5. The pin is biased in the upwards direction by spring pressure, and the support has an unlocked condition in which the pin can resile against the spring pressure, and a locked position in which the pin is held rigidly in its upper position. Atoothed segment 13 of the support meshes with a rack 15 arranged on the adjacent roll counter-balancing blocks 39.Consequently, as the roll set is drawn out or moved into the stand, the segment rotates and changes the condition of the support. In this way, the pin is permitted to resile while the roll set is in its working position within the stand, and is rigid while the roll set is in movement.

The support 1 is shown in more detail in Figures 1, 2 and 3, where it will be seen to include a housing 2 which is of rectangular cross-section in the region above the dashed line L. Below this line, the housing is of cylindrical cross-section, as depicted at 2a in Figure 3. Bolts used to secure the housing in place pass through holes 44 in a flange 33 arranged generally at the level of the line L in Figure 1.

Extending throughout its length the housing has a cylindrical bore which receives a cylindrical sleeve 4.

The sleeve rotates in bearings 2b and at its lower end projects slightly below the lower extremity of the housing. The housing is closed at its upper and lower ends by covers 7 and 8 which have circular openings 9 and 12 for the passage and vertical movement of a pin or bolt 6. The lower cover 8 is secured to the sleeve 4 by screws 14 and is in one piece with the toothed segment 13, whereby the sleeve 4 is caused to rotate as the segment rolls along the rack 15. Extending throughout the length of the sleeve is a bore through which passes the pin 6. The pin has a shoulder 16 which abuts against the cover 7 to limit upwards movement of the pin and to serve as an abutment for a compression spring 5 which bears at its lower end against an internal shoulder 17 of the sleeve.The upper portion 6b of the pin is of greater diameter than the lower portion 6a, and the latter is threaded to allow a nut 22 to be screwed into a position abutting the annular surfaces between the two pin portions. The nut has diametrically opposite lugs 19 as best seen in Figure 2. Extending between the lower end of the sleeve and a support shoulder 24 are diametrically opposite grooves 18 dimensioned to allow the passage therethrough of the lugs 19. When the sleeve occupies the position shown in Figure 2, the lugs rest on the support shoulder and the pin is held in the illustrated, raised position, or in any event in an extended position. When the sleeve is rotated through 90" by cooperation of the toothed segment 13 and rack 15, the lugs overlie the grooves and the pin can be depressed against the force of the spring 5.

The pin is connected with the upper cover 7 by a feather key 20 to prevent the pin from rotating with the sleeve 4, the cover being suitably locked in position relative to the housing. When the sleeve occupies the unlocked position, it is held in position by a detent mechanism including a ball 26 and spring 25, which urges the ball into a depression 27.

The risk of the support becoming locked as the result of vibrations in thereby reduced.

Operation takes place as follows: During operation of the Konti roll train of which the illustrated stand forms a part, the lugs 19 overlie the grooves 18, and the pin 6 moves up and down in accordance with movement of the upper work roll relative to the lower work roll. After the train has been shut down, the roll gap is firstly relaxed by driving the positioning spindle or adjusting the ram position on the underside of the stand. To enable the pin 6 of each support 1 to enter its uppermost position under the force of the spring 5, the work roll counter-balancing system is firstly disconnected and, if provided, the pressure plate between the upper roll chock 29 and the upper adjusting spindle is removed. This is necessary in order to obtain sufficient space to remove the upper work roll 35.

The support and work roll counter-balancing system are then reconnected so that the ram 52 lifts the upper support roll chock 29 and the ram 52a lifts the upper work roll chock 33. The piston and cylinder units 47,49 are extended to align the rail end portion 37a with the main part of the rail 37. As the work roll counter-balance system is disconnected (the rams 52a are deactivated), the upper work roll 35 is lowered by way of the wheels 40a of the chocks 33 onto the upper rails 37. In parallel, the lower support roll 32 and the lower work roll 36 are lowered so that the wheels 40 of the lower work roll chocks 34 engage the rails 38.

The rolls 35,36 are moved by means of a displacement ram of the roll exchange device which is not shown. During this operation, the toothed segment 13 of each support 1 runs in mesh with the toothed racks 15 to cause the raised pins 6 to be locked in position as the lugs 19 are brought into position above the shoulder 24 on rotation of the sleeve 4. The pin 6 engages the passage 46 in the opposing block 45 as the weight of the upper work roll 35 is applied to it, but the pin cannot descend under the weight of the roll. As the work rolls 35,36 are withdrawn further, the spacing catches 41 on the drive side meet the stops 42 on the service side and are raised by them. Once the work rolls 35, 36 leave the roll stand by way of the rolls 37,38, the upper work roll 35 drops under guidance provided by the inclined end portions 37a of the supports 1 and 41 of the lower work roll 36. In the movable roll set thus formed, the upper work roll 35 rests on the lower work roll 36 at a constant distance determined independently of the roll diameter and without the roll surfaces being in contact.

The roll exchange device includes a sliding platform movable transversely in front of the stand with roll exchange cars. Once the set of rolls removed from the stand is supported on the platform, it is moved away and a new set of rolls is likewise brought into position in front of the stand. The new set is then driven into the window 28 while the spacing catches 41 on the chocks on the drive side are automatically folded back by the stops 42 and thus clear a space between the chocks as they enter the stand.

In the stand, the lower work roll 36 runs by the wheels 40 on the rails 38, and the upper rolls run on the rails 37. As soon as the toothed segments of the supports 1 engage the toothed racks, the sleeves begin to turn relative to the pins. Following rotation of the sleeves by 90 , at which time the rolls are within the housing, the supports are unlocked and the lugs 19 are in line with the grooves 18.

To continue operation of the rolling mill the necessary additional preparations are carried out, such as moving the rail end portions 37Ato their outward positions, and connecting the counterbalancing systems, until the desired roll gap is finally adjusted. During the rolling operation, the pins 6 of the supports are pressed down by the pockets 46 of the blocks 45 so that the lugs 19 move within the grooves 18 and are guided by them.

The supports 1 may be used in the conventional exchange of work rolls even if there is no material in the stand. In this case, the supports are advantageously provided on the drive side.

Of course, the supprts may be inverted and fixed to the upper chock. The rotary member can be arranged with the telescopically movable part, or the grooves and lugs relocated.

Claims (11)

1. A method of changing the work rolls of a roll stand, wherein the rolls are introduced into and removed from the stand on rails, wherein the upper roll is supported relative to the lower roll by supports adapted to have a rigid condition during the roll changing operation, and a resilient condition during the rolling operation.

2. A roll stand comprising upper and lower work rolls, a chock or fitting of one of which is associated with supports engageable with the chock or fitting of the other; each support comprising a telescopic assembly capable of being places selectively in a rigid condition and a resilient condition.

3. A stand according to claim 2, wherein the other chock or fitting is associated with a block having a pocket for receiving a part of the telescopic assembly.

4. A stand according to claim 2 or claim 3, wherein each support is operated so as to change its condition by a toothed segment meshing with a rack.

5. A stand according to claim 4, wherein the rack is fixed in the stand and rotates the segment by 90" during movement of the chock or fitting.

6. A support according to claim 4 or claim 5, wherein the rack is fixed in the roll counter-balancing block.

7. A support for use in the method of claim 1 or the stand of any of claims 2 to 6, comprising a housing having a rectangular upper portion and a cylindrical lower portion with flanges for attachment to the roll chock or fitting, a rotatable sleeve within the housing, the sleeve being fast with a toothed segment, a pin extending through the sleeve and being biased upwards by a compression spring, the pin being provided with diametrically opposite lugs, and the sleeve having grooves capable of receiving the lugs in an adjusted position of the sleeve produced by rotation of the toothed segment.

8. A support according to claim 7, wherein the lugs are provided on a nut screwed onto the pin.

9. A support according to claim 7 or claim 8, wherein the housing is sealed by covers having openings for the passage of the pin, the lower cover being fast or integral with the toothed segment and secured to the sleeve.

10. A support according to any of claims 7 to 9, wherein the compression spring extends between an internal projection of the sleeve and a collar of the pin, which collar bears against the upper cover of the housing when the pin is biased by the spring into its uppermost position.

11. A stand according to any of claims 7 to 10, wnerein each support includes a detent mechanism for holding the sleeve in the position in which the pin is capable of resiling.

11. A support according to any of claim 7 to 10, including a detent mechanism for holding the sleeve in the position in which the pin is capable of resiling.

12. A method substantially as hereinbefore described with reference to the accompanying drawings.

13. A roll stand substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

14. A support substantially as hereinbefore described with reference to and as illustrated in Figures 1 to 3 of the accompanying drawings.

New claims or amendments to claims filed on 10 June1983 Superseded claims 6-11,14 New or amended claims:

6. A stand according to claim 4 or claim 5, wherein the rack is fixed in the roll counter-balancing block.

7. A stand according to any of claims 2 to 6, wherein each support comprises a housing having a rectangular upper portion and a cylindrical lower portion with flanges for attachment to the roll chock or fitting, a rotatable sleeve within the housing, the sleeve being fast with a toothed segment, a pin extending through the sleeve and being biased upwards by a compression spring, the pin being provided with diametrically opposite lugs, and the sleeve having grooves capable of receiving the lugs in an adjusted position of the sleeve produced by rotation of the toothed segment.

8. A stand according to claim 7, wherein the lugs of each support are provided on a nut screwed onto the pin.

9. A stand according to claim 7 or claim 8, wherein the housing of each support is sealed by covers having openings for the passage of the pin, the lower cover being fast or integral with the toothed segment and secured to the sleeve.

10. A stand according to any of claims 7 to 9, wherein the compression spring of each support extends between an internal projection of the sleeve and a collar of the pin, which collar bears against the upper cover of the housing when the pin is biasod by the spring into its uppermost position.