GB2129722A - Pipe-rolling mills - Google Patents

Abstract

A pipe rolling mill includes a plurality of fixed bases each supporting a mill housing 2 which in turn carries a pair of rolls. Each pair of rolls is mounted on a roll replacement carriage 4 respectively, which is movable on a first set of fixed rails 3 on the respective housing 2 in a direction perpendicular to the rolling path. Associated with each set of rolls are two shift carriages 23 having rails 24 on their upper surfaces. Supported on the rails 24 of one of the shift carriages 23 is a retraction carriage 26. Situated on the other shift carriage 23 is a further carriage 4 carrying fresh rolls. To change the working rolls, the retraction carriage 26 pulls the operative carriage 4 up the rails 3 onto the rails 24 on the shift carriage and itself moves onto fixed rails 24'. After disconnecting the carriages 4,26 the shift carriages 23 are moved parallel to the rolling path by a hydraulic piston and cylinder unit thereby aligning the second roll replacement carriage 4 on the second shift carriage 23 with the rails 3,24'. The carriage 26 then lowers the replacement carriage 4 into the working position. <IMAGE>

Description

SPECIFICATION Plprolling mills The present invention relates to pipe-rolling mills and is concerned with such mills including apparatus for replacing the rolls when the mill is in a pipe production line and relates in particular to a mandrel mill or a sizing mill for the production of seamless tubes.

A sizing mill is disposed as the last stage in a continuous pipe production line so as to produce pipes with a predetermined outer diameter and the required parameters, such as straightness and surface quality or smoothness. When the outer diameter of the pipes being produced is to be varied or if any rolling defects such as surface flaws are found or if the rolls become worn or damaged, the rolls must be replaced by new ones, sometimes at frequent intervals.

Figure 8.is a diagrammatic elevation of a known sizing mill stand which has a pair of stationary supports b and b' with flat mounting surfaces oppositely inclined at 45" to the vertical. Respective mill housing assemblies a and a' are mounted on these inclined mounting surfaces and roll shafts e and e' are coupled by respective couplings c and c' to driving means d and d' to be rotated thereby. The assemblies a and a' are securely anchored to the stationary supports b and b' by means of bolts so that when the rolls are to be replaced the bolts must be loosened and removed and the assemblies a and a' must be lifted away from the stationary supports b and b' by means of a crane or the like.After the replacement of the rolls, the assemblies a and a' must be lifted again by a crane or the like and lowered on the stationary supports b and b'. Thereafter the fine position adjustments of the assemblies a and a' relative to the adjacent mill stands must be carried out before they are securely mounted on the stationary bases b and b'. It will therefore be apparent that the idle time of this sizing mill stand will inevitably be relatively long with a resultant decrease in productivity. Furthermore, since a crane or the like is used to remove the assemblies a and a' from the stationary bases b and b' and then to replace the former upon the latter, it is necessary for someone to engage the eyes of the ropes with the hook of the crane. Such operations are hazardous and need many operating personnel.

In order to overcome the above and other problems, there has been proposed a method of roll replacement in which a mill housings mounted on a carriage which can travel in the longitudinal direction of the rolling mill, i.e. parallel to the rolling path.

When the rolls are to be replaced, the mill housing on the carriage is moved along the rolling path to a predetermined location where the mill housing is transferred onto another carriage which can travel in a direction perpendicular to the rolling path, whereby the mill housing can be removed from the rolling path and its rolls can be replaced. However, this method has certain problems which will be described below. Firstly, when the mill housing is removed from the rolling mill in the manner described above, the lubricating oil feed lines and the hydraulic lines connected to hydraulic jacks for roll balancing must be disconnected. As a result, the replacement time is relatively long. In addition, a number of reserve or spare mill housings must be provided which are very expensive.As a consequence, not only the installation cost but also the operational cost are inevitably very high.

Accordingly it is an object of the present invention to provide a pipe rolling mill in which it is possible easily and rapidly to replace the rolls so that the operational idle time of the rolling mill can be reduced to a minimum, whereby high productivity can be ensured. It is also an object to eliminate the requirement for engaging the eyes of the ropes with the hook of the crane, whereby the roll replacement can be accomplished safely, labour savings can be attained, the replacement costs can be reduced to a minimum and inspection and maintenance of the rolling mill facilitated.

According to the present invention a pipe rolling mill includes a plurality of mill stands each having a mill housing and a pair of rolls, the pairs of rolls together defining a rolling path, each pair of rolls being mounted on a roll replacement carriage which is movable on first travel guide means on the respective mill housing substantially perpendicular to the rolling path, each mill stand being associated with two shift carriages, each having second travel guide means, a retraction carriage which is selectively connectable to the roll replacement carriage and adapted to run on the second travel guide means and means to move the shift carriages substantially parallel to the rolling path between a first position in which the second travel guide means of one shift carriage connects the first travel guide means to third travel guide means disposed more remote from the rolling path than the second travel guide means and a second position in which the second travel guide means of the other shift carriage connects the first travel guide means to the third travel guide means.

Thus, in use each pair of operative rolls is mounted on a roll replacement carriage which preferably may be secured in its operative position and released when the rolls are to be exchanged.

When the rolls are to be exchanged, the retraction carriage on one of the shift carriages is connected to the roll replacement carriage and pulls it up the first travel guide means, e.g. rails, on the millstand-and on to the second travel guide means, e.g. rails, on the shift carriage and itself moves onto the third travel guide means, e.g. fixed rails. The shift carriage is moved in the direction of the rolling path and the other shift carriage which carries a second roll replacement carriage with replacement rolls is moved into alignment with the first and third travel guide means. The previous process is reversed and the replacement rolls put into position. The rolls on the first roll replacement carriage can be exchanged at leisure whilst the rolling mill is operating.

The third travel guide means may move with the shift truck but this would require two retraction carriages per mill stand and it is therefore preferred that the third travel guide means are fixed.

In practice, the pair of rolls are generally disposed alternately in one of two orientations differing by 90"C. This will generally mean that the retraction carriages and shift carriages will be situated on both sides of the rolling path and offset from one another.

The mill housings are generally mounted on inclined surfaces of the mill stands and thus the first travel guide means will generally extend downwardly, e.g.

at about 45 , to the rolling path.

Further features and details of the present invention will be apparent from the following description of one specific embodiment which is given by way of example only with reference to the following drawings, in which Figure I is a plan view of an apparatus for replacing rolls in a pipe-rolling mill according to the present invention; Figure 2 is an end view in the direction of the arrows II in Figure 1; Figure 3 shows a retraction carriage and a rollreplacement carriage in the roll replacement position for replacement of roll; Figure 4 is a sectional view on the line IV-IV in Figure 2; Figure 5shows reduction screws removed from the bearing box shown in Figure 4; Figure 6 is a sectional view on the line VI-VI in Figure 4; and Figure 7 is a sectional view taken on line VII-VII in Figure 4.

As best seen in Figure 2, the pipe rolling mill has a plurality of stationary bases 1 each having a mounting surface downwardly inclined at about 45" towards the path along which pipes are to be rolled (rolling path) and spaced apart along both sides of the rolling path in such away thattheir inclined supporting or mounting surfaces are of alternating sense, that is to say the mounting surfaces on one side of the rolling path are longitudinally offset from those on the other side, as best shown in Figure 1. A mill housing 2, which has opened sections, is mounted on the inclined mounting surface of each stationary base 1.A pair or rails 3 is laid on the bottom member of each mill housing 2 in such a way that they extend perpendicular to the rolling path of pipes being rolled orto the longitudinal direction of the rolling mill when viewed from above, but they are inclined downwards at about 45" to extend substantially parallel to the inclined supporting surface of the associated stationary base 1 when viewed from one end of the rolling mill. A rollreplacement carriage 4 has wheels 5 engaging the rails 3 and thus can travel along the rails 3.

As best seen in Figures 2 or 3, the carriage 4 is U-shaped in-cross section when viewed from one end of the rolling mill and its upstanding side walls and base are adapted to support roll bearing boxes 6 when replacing the associated rolls. As best seen in Figures 4, 5 or 7, one side wall of the carriage is provided with openings through which the shaft 7 of the associated rolls extend. As seen in Figures 4 or 5, the base of the carriage 4 is formed with openings 9 through which reduction screws 8 can be extended into the carriage 4 when the latter is brought to a predetermined position on the rails 3. The reduction screws 8 are mounted on the mill housing 2.

As best seen in Figure 5, coaxial nuts 10 are threadably engaged with the upper and lower end of the mill housing 2 with their axes parallel with the vertical axis of the mill housing 2 and the reduction screws 8 are threadedly engaged with respective nuts 10. A worm wheel 12 is rotatably supported in a respective worm wheel shaft box 11 mounted at the upper and lower ends, respectively, of the mill housing and the associated reduction screw 8 is fitted into a centre hole of the worm wheel 12 and securely retained therein by means of a spline key 13. The worm wheel 12 is in mesh with a worm 37 which in turn is driven by an electric motor 14 (see Figure 2).

As best shown in Figures 4,6 or 7, a clamp guide 15 with a U-shaped guide groove is bolted to the portion of the mill housing 2 for engagement with the roll shaft box 6 and a clamping member 16 is fitted into the guide groove for sliding movement in the longitudinal direction of the pipe-rolling mill. The portion at the midpoint between the wends of the clamping member 16 extends toward the axis of the mill housing 2 and carries a hydraulic cylinder 17 which, when actuated, is adapted to shift the clamping member 16 in the longitudinal direction of the rolling mill. The piston rod 18 of the hydraulic cylinder 17 is pivotally connected to a pin 19 which is attached to the mill housing 2 and the clamp guide 15.Thus, when the clamping member 16 is extended toward the axis of the mill housing, it engages with the raised or projecting portion of the roll shaft box 6, thereby preventing shifting in the axial direction of the roll 21.

As best seen in Figure 1, disposed on bpth sides of the rolling path are shift carriages 23 which can be shifted in the longitudinal direction of the pipe rolling mill by respective hydraulic cylinders 22, respectively. Situated on each of the carriages 23 are pairs of rails 24 which extend perpendicular to the longitudinal axis of the pipe rolling-mill. There are twice as many pairs of rails 24 as there are mill stands. A rack 25 extends parallel to-each rail 24 and a retraction carriage 26 with a driving device 27 rides on each pair of rails 24. A pinion which is driven by the driving device 27 meshes with the rack 25 to move each retraction carriage 26 back and forth along the associated pair of rails 24. A coupling member comprising a hook 29 is pivotally connected at one end to the end nearest to the rolling path of the carriage 26 (see Figure 2) and is operatively coupled to a hydraulic cylinder 30 mounted on the retraction carriage 26. Thus, on actuation of the hydraulic cylinder 30, the hook 29 engages with or disengages from a pin 31 extending from there end of the carriage 4.

Throughout the Figures, reference numeral 32 denotes an electric motor for driving a roll; 33, a reduction gear; 34, a coupling for connecting the output shaft of the reduction gear 33 and å spindle 35; and 36, a coupling for connecting the spindle 35 to the roll shaft 7. Stopper means (not shown) are provided on the mill housing 2 so that when the carriage 4 rides down the rails 3 on-the mill housing 2, it is held stationary at a predetermined position reference numeral 24' designates a pair of rails in line with the rails 24 on the carriage 23 so that the carriage 23 can be transferred from the rail pair 24 to the rail pair 24' and 25' designates a rack in mesh with a pinion 28 carried by the retraction carriage 26.

The pairs of rails 24 and racks 25' are held stationary.

During normal pipe-rolling operation, the carriage 4 on which the operative rolls 21 are mounted rides on the pair of rails 3 on the mill housing 2 and is held stationary at a predetermined position by means of the stopper means (not shown) described above.

The retraction carriage 26 rides on the pair of rails 24 on a shift carriage 23 in line with the rails 3 and the hydraulic cylinder 30 is so actuated that the hook 29 is disengaged from the engaging pin 31 on the carriage 4.

The mill stands are also provided with a further respective roll-engagement carriage 4 in addition to that supporting the operative rolls, which rides on the pair of rails 24 on the carriage 23 and carries new rolls.

If the rolls 21 of one stand are to be replaced, the hydraulic cylinder 30 is actuated to cause the hook 29 to engage with the engaging pin 31 of the carriage 36 connecting the shaft 7 of the roll 21 and the spindle 35 is shifted in the axial direction so that the shaft 7 is disconnected from the spindle 35. The upper reduction screw 8 is raised and the lower reduction screw 8 is lowered as shown in Figure 5.

As a result, the reduction screws 8 are removed from the roll shaft boxes 6. Thereafter the hydraulic cylinder 17 is actuated so that the clamping member 16 is moved away from the roll shaft box 6 and the former is disengaged from the raised or projecting portion of the latter. Then the driving device 27 of the retraction carriage 26 is actuated so that the pinion 28 is rotated. As a result, the carriage 4 is pulled up the rails 3 on the mill housing 2 and then leaves these and rides on the pair of rails 24 on the carriage 23. In this embodiment, the retraction carriage 26 moves or retracts from the rails 24 to the fixed rails 24'.

When the carriage 4 with the rolls 21 is lifted away from the rails 3 onto the rails 24, the hook 29 of the retraction carriage 26 is disengaged from the engaging pin 31 of the carriage 4 and consequently the carriages 4 and 26 are disconnected from each other.

Thereafter the associated hydraulic cylinder 22 is actuated so that the shift carriage 23 is caused to move in the longitudinal direction of the rolling mill until the rail pair 24 on which the carriage 4 carrying the reserve rolls rides is in alignment with the rails 3 on the mill housing 2 along which the other carriage 4 has been lifted. Then the new carriage 4 which carries the reserve rolls 21 is connected to the retraction or traction carriage 26 by engaging the hook 29 with the engaging pin 31 of the new carriage 4. The driving device 27 on the retraction carriage 26 is then actuated so that the new carriage 4 carrying the new rolls 21 is transferred from the rails 24 on the associated carriage 23 onto the rails 3 on the mill housing 2.When the new carriage 4 reaches the predetermined position in the mill housing 2, the clamping member 16 is so actuuted as to engage with the raised or projecting portion of the roll shaft box 6 so that the shaft box 6 is securely held against the housing 2. Thereafter the upper reduction screw 8 is lowered while the lower reduction screw 8 is lifted so that their ends engage with the corresponding roll shaft boxes 6. Next the spindle 35 is lifted so that its upper end is inserted into the coupling 36, whereby the spindle 35 is connected to the roll shaft 7. In this case, the retraction carriage 26 has left the rail pair 24' and is riding on the rails 24 of the replacement shift carriage 23. Thus the replacement of the rolls has been accomplished.Since the hooks 29 of the remaining carriages 26 remain disengaged from the engaging pins 31 of the associated carriages 4, the roll replacement operation is not disturbed.

The present invention has been described with reference to the replacement of one roll pair, but it is to be understood that all the roll pairs can be replaced simultaneously. In addition, instead of the driving device described for moving the retraction carriage, a hydraulic cylinder or a chain drive system may be employed as needs demand and various other modifications can be effected.

The advantages of a pipe rolling mill in accordance with the present invention may be summarized as follows: it is possible quickly to replace some, all or any desired one of the roll pairs so that the idle time is shortened and consequently high productivity can be ensured. Disconnecting the various hydraulic lines and re-connection thereof can be eliminated so that a full automatic roll replacement operation can be accomplished. Reserve stands can be reduced in number as compared with the known mill so that the initial installation cost can be reduced accordingly.

Engaging and disengaging the eyes of the ropes and hooks can be eliminated so that the roll replacement operation is very much safer than previously.

Claims (4)

1. A pipe rolling mill including a plurality of mill stands each having a mill housing and a pair of rolls, the pairs of rolls together defining a rolling path, each pair of rolls being mounted on a roll replacement carriage which is movable on first travel guide means on the respective mill housing substantially perpendicularto the rolling path, each mill stand being associated with two shift carriages, each having second travel guide means, a retraction carriage which is selectively connectable to the roll replacement carriage and adapted to run on the second travel guide means and means to move the shift carriages substantially parallel to the rolling path between a first position in which the second travel guide means of one shift carriage connects the first travel guide means to third travel guide means disposed more remote from the rolling path than the second travel guide means and a second position in which the second travel guide means of the other shift carriage connects the first travel guide means to the third travel guide means.

2. A mill as claimed in Claim 1 in which the third travel guide means is fixed.

3. A mill as claimed in Claim 1 or Claim 2 including a further roll replacement carriage associ ated with each mill stand, carrying replacement rolls and resting on the second travel guide means of one of the associated shift carriages.

4. A pipe rolling mill substantially as specifically herein described with reference to Figures 1 to 8 of the accompanying drawings.