GB1563660A - Device for coupling a mandrel to a mandrel-bearing slide in a piercing and rolling mill - Google Patents

Description

(54) A DEVICE FOR COUPLING A MANDREL TO A MANDREL-BEARING SLIDE IN A PIERCING AND ROLLING MILL (71) We, INNOCENTI SANTEUS TACCHIO S.p.A. an Italian joint stock Company, located at 20, via A. Franchi, Brescia, Italy, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to a device for coupling the mandrel to the mandrelbearing slide in a rolling and pressure piercing mill.

A rolling and pressure piercing mill, which will hereinafter be indicated by the symbol PPM, is a machine used for converting square steel bars into round, axially pierced blooms. The machine substantially comprises a stand with two grooved rolls, a rod or mandrel which extends along the rolling axis from the outlet side of the stand and bears a piercing bit at one end. and a pusher at the inlet side of the stand for pushing the square bare for piercing between the rolls against the piercing bit so that the bar is simultaneously pierced in the axial direction and rolled on the mandrel.

The other end of the chuck rod or mandrel engages and is secured in a suitable seat formed in a mandrel-bearing slide movably guided in the direction parallel to the rolling axis and actuated by hydraulic cylinders. By means of the slide and the associated hydraulic cyclinders, the mandrel is rigidly held in an operating position in which the piercing bit is held between the grooved rolls during operation of the PPM and is moved back into an inoperative position at the end of the simultaneous piercing and rolling operations, by sliding along the rolling axis.

In the non-operative position, in the prior art, the mandrel is removed, i.e. extracted from the rolled bloom thereon, after which the mandrel is cooled and the piercing bit is checked and lubricated. After these operations, the mandrel is brought back to an operating position for piercing and simultaneously rolling a new square bar.

The series of operations for recovering and re-using the mandrel takes a relatively long time, during which the PPM must remain inoperative since, during the aforementioned operations, the mandrel is held in the inoperative position on the rolling axis and it is impossible to insert a new mandrel in the rolling stand for a subsequent piercing and rolling operation.

In view of the known high hourly productive capacity of a PPM, the aforementioned inoperative time is clearly a serious technical disadvantage.

This disadvantage could be obviated by performing the aforementioned operations in one or more side stations which are at a distance and therefore do not interfere with the rolling axis. In that case, the rolling stand will rapidly be made accessible and available for positioning a second mandrel after the piercing bit thereof has been checked and lubricated. In this manner, the inoperative time of the PPM can be limited to the time required for removing the mandrel, together with the rolled bloom thereon, from the inoperative position on the rolling axis to the first of the aforementioned stations in which the recovery and re-use operations are performed.However, existing devices used for coupling and securing a mandrel to the mandrel-bearing slide are such that the releasing and uncoupling operations necessary for transferring the mandrel to the recovery stations are comparable in length with the times at present taken by the mandrel re-use and recovery operations performed along the rolling axis.

The invention is based on the problem of constructing a device for coupling the mandrel to the mandrel-bearing slide in a PPM, having structural and operating characteristics such that. at the end of an operation for simultaneously rolling and piercing a square bar, the mandrel can rapidly be released from the slide and moved from the rolling axis so that the rolling stand is quickly available for positioning a second mandrel, thus substantially and advantageously reducing the inoperative time of the PPM.

To this end, according to the invention there is provided a device for coupling a mandrel to a mandrel-bearing slide in a piercing and pressure rolling mill (PPM) comprising a female guide open at top and bottom and secured to the slide, a male counter-guide secured to one end of the mandrel and adapted to be engaged or released by sliding vertically into or out of the female guide through the open top and respectively open bottom thereof, and bolt means for removably securing the male counter-guide in the female guide.

The main advantage of the invention consists in the speed and ease with which, at the end of an operation for simultaneously rolling and piercing a bar, the mandrel, after being moved back into the inoperative position, can be released from the mandrelbearing slide and removed from the rolling axis, and in the speed and ease with which a new mandrel, after its piercing bit has been checked and lubricated, can be inserted into the slide and moved into the operating position in which the piercing bit is between the rolls. It is only necessary to remove the locking means or bolt, since the mandrel, owing to gravity, slips off the slide and drops away-from the rolling axis, and the new mandrel can be positioned in place of the preceding mandrel by fitting it into the slide and moving it vertically downwards, where it is secured by the bolt means.

Other features and advantages of the invention will be clear from the following detailed description of an embodiment of the device for coupling the mandrel to the associated mandre-bearing slide in a PPM, with reference to the accompanying drawings in which: Figure I is a diagrammatic plan view of the outlet side of a PPM machine: Figure 2 shows a larger-scale section along line II - II in Figure 1; Figure 3 and 4 are persepctive, partly cut-away views of a device for coupling the mandrel to the mandrel-bearing slide according to the invention, and Figure 5 shows a horizontal axial section.

on a larger scale. of the coupling device shown in the preceding Figures.

In the drawings. reference 1 diagrammatically indicates the rolling stand of a known rolling and pressure piercing mill or PPM in which two grooved rolls (known and therefore not shown) co-operate with a piercing bit 2 to convert a square bar (not shown) into an axially pierced round bloom S.

Piercing bit 2 is coaxially secured to one end of a chuck rod or mandrel 3, the axis of which coincides with the rolling axis A; the mandrel extends from the outlet side la of stand 1 for a given length. At the other end, mandrel 3 is coupled to a mandrel-bearing slide 4 by a device according to the invention described in detail hereinafter. Slide 4 is borne by a frame 5 and guided so that it can slide in the direction parallel to the rolling axis A, actuated by a pair of hydraulic cylinders 6,6.

When mandrel 3 is in the operating position and its piercing bit 2 is between the roll S, it is rigidly held by a plurality of pairs of known clamps 7, 7 and 7a, 7a borne by frame 5 on vertical pivots 8, in symmetrical positions with respect to the rolling axis A.

The clamps are actuated by corresponding hydraulic cylinders 9, 9 and 10, 10. Near at least the first pair of clamps 7, 7 frame 5 bears photocell means (not shown) which, when bloom S advances on mandrel 3, actuates cyclinders 9, 9 and 10, 10 so that the clamps are automatically opened so that the bloom can move between them.

During the time when mandrel 3 is in the operating position, slide 4 is held in a corresponding operating position, both by the hydraulic thrust of cylinders 6. 6 and by the mechanical action of removable stop means, which are known and therefore not shown.

In Figure 2, reference 11 denotes a holder substantially in the form of a trough having an upwardly facing concavity and extending for a given length parallel to the rolling axis A and below the pairs of clamps 7, 7 and 7a, 7a. Trough 11 is rigidly held by the free ends 12a of a plurality of identical sectional arms 12 extending at an angle to frame 5, the other ends 12b of the arms being coaxially secured to a shaft 13 secured parallel to the rolling axis A of frame 5. Shift 13 can be angularly moved around its longitudinal axis by one or more levers 14 actuated by hydraulic cylinder group 15. Consequently trough 11 can be angularly moved around the axis of shaft 13, from a horizontal position immediately underneath the pairs of clamps 7, 7 and 7a, 7a to a lowered position indicated by broken lines in Figure 2. In the last-mentioned position, trough 11 is slightly below the level of the higher end 16a of an inclined plane 16 comprising e.g a plurality of bars 17. The lower end 16b of the inclined plane, which extends laterally outside frame 5, is at the same level and co-operates with a loading plane (not shown) of a station diagrammatically indicated at 18, fitted with conventional devices (not shown), for releasing the mandrel, i.e.

axially extracting the mandrel 3 from the rolled bloom S. Reference 19 diagrammatically indicates a station adapted in conventional manner to cool the mandrel and check and lubricate the piercing bit 2. A bridge or similar structure diagrammatically indicated at 20 extends at an angle to the rolling axis A over stations 19, 18 and frame 5, described hereinbefore. A crane 21 can move over structure 20 and is provided with conventional means for gripping, removing, raising and conveying a mandrel 3 parallel to itself.

In Figures 3 - 5, the general reference 22 denotes a device according to the invention for coupling mandrel 3 to the mandrelbearing slide 4. The device comprises a substantially parallelepipedal body 23 coaxially secured, e.g. by welding, to the end 3a of mandrel 3. Advantageously mandrel 3 is of the kind having an axial bore 24 of given diameter which coaxially bears, in known manner, a duct 25 co-operating with aperture 24 to form a gap 26. Duct 25 is used for conveying cooling water to the piercing bit 2, whereas gap 26 forms a duct for returning and discharging the cooling water.

Body 23 has an axial bore made up of three successive portions 27, 28 and 29. End 3a of mandrel 3 is coaxially secured in Portion 27. The central bore portion 28 is large and forms a chamber containing liquid in communication with gap 26 and the exterior of body 23, via a pair of opposite ducts 30, 31 formed in body 23. A cup 32 which opens towards slide 4 is coaxially secured in bore portion 29. The bottom 32a of cup 32 is formed with a bore 33 holding an end 25a of the cooling-water duct 25. An annular gasket 34 is secured in cup 32 in contact with bottom 32a.

Two identical vertical plates 35, 36 are secured at the front of slide 4 and are spaced apart by a distance equal to the width of parallelepipedal body 23. Plates 35, 36 have bent square opposite end portions 35a, 36a and thus the plates have a substantially chelate shape.

The distance between the bent ends 35a, 36a of the wall portions 4a in front of slide 4 and between the plates is slightly greater than the length of body 23 measured in the axial direction of mandrel 3. The aforementioned portion 4a of the front walls of slide 4 together with the opposite plates 35, 36 substantially form a feminine guide open at top and bottom and adapted for slidably receiving body 23, which substantially comprises a male counter-guide. As shown in Figures 3 and 4, body 23 (the counter-guide) can slide into or out of the female guide, but only in the vertical direction. Slide 4 has an axial duct 37 of given diameter (Figure 1) extending coaxially with the rolling axis A.

Duct 37 has a mouth 37a which opens into the portion 4a of the front wall of the slide between plates 35 and 36. A hollow cylindrical rod 38 is coaxially and slidably mounted in duct 37 and ends in a partspherical head 38a having a diameter equal to the inner diameter of cup 32, with which it is adapted to engage. More particularly, head 38a terminates at the front in a flat surface, whereas the diameter of the cylindrical cavity defined by rod 38 is substantially equal to the inner diameter of the cooling-water duct 25.

At the end remote from head 38a, rod 38 is secured in known manner (not shown) to a source of water under pressure. A known device (not shown), e.g. a rack and pinion, is secured in slide 4 and can be manually actuated by a hand lever 40 (Figure 1) and is used for effecting sliding movement of cylindrical rod 38 to bring the part-spherical head 38a into and out of engagement with the cup 32.

The aforementioned briefly-described apparatus, incorporating the device according to the invention for coupling the mandrel to the mandrel-bearing slide, operates as follows: During operation of the PPM (Figure 1) mandrel 3 is firmly held in the operating position by the plurality of clamps 7, 7 and 7a, 7a actuated by the associated cylinders 9, 9 and 10, 10 and by the mandrel-bearing slide 4 and associated cylinders 6, 6. The parallelepipedal body 23 secured to the rear end of mandrel 3 is secured in the corresponding seat formed by plates 35, 36 and by the bolt comprising the hollow cylindrical rod 38, whose spherical head 38a is completely inserted in cup 32 and pressed against gasket 28 (Figure 5).

During operation of the PPM, the piercing bit 2 is continually cooled by the flow of cooling water supplied to the bit via the hollow rod 38 and duct 25. The cooling water is discharged through the gap 26, the central chamber 28 of body 23, ducts 30, 31 formed in the body 23 and through apertures 41, 42, formed in plates 35, 36 respectively and positioned in line with ducts 30 and 31.During operation of the PPM, trough 11 is in the horizontal position immediately under clamps 7, 7 and 7a, 7a whereas a new mandrel (not shown) is held in station 19 after it has been cooled and its piercing bit has been checked and lubricated. when the PPM is stopped at the end of an operation for piercing and rolling a bar. the mandrel-bearing slide 4 is moved back into an inoperative position by the corresponding hydraulic cylinders 6, 6 and carries with it the mandrel 3 and the pierced bloom S thereon, During the backward motion, which is adjusted so that bit 2 is properly held outside stand 1, mandrel 3 and the bloom S are secured by the plurality of clamps 7, 7 and 7a. 7a.After reaching the aforementioned inoperative position, the hollow cylindrical rod or bolt 38 is moved back, using the hand lever 40 until the spherical head 38a is completely released by cup 32 of mandrel body 23; at the same time, clamps 7, 7 and 7a, 7a are opened by actuating the corresponding cylinders 9, 9 and 10, 10.

Mandrel 3 and the associated bloom S rolled thereon falls on to the trough 21 underneath and mandrel body 23 simultaneously slides vertically off the corresponding seat formed by plates 35 and 36.

At this stage, hydraulic cylinder 15 moves trough 11 to the lowered position shown by broken lines in Figure 2, in which mandrel 3 and bloom S are discharged on to the inclined plane 16 and transferred by gravity to the mandrel removing stations 18.

At the same time as trough 11 is lowered, crane 21 removes the mandrel from station 19 after its piercing bit has been checked and lubricated and conveys it perpendicularly to the rolling axis A. Subsequently, crane 21 lowers the new mandrel until it parallelepipedal end body 23 slides into and engages the seat formed by plates 35, 36 of slide 4.

The new mandrel is locked in the lastmentioned position after the spherical head 38a of bolt 38 has been completely inserted into cup 32. when the mandrel is held by clamps 7. 7 and 7a. 7a. After mandrel 3 has been secured. crane 21 releases it and returns to its starting position, during which time slide 4 moves forward under the action of cylinders 6. 6 and conveys the mandrel into the operating position in which its piercing bit is between the rolls in stand 1.

At this stage, the PPM is ready to pierce and simultaneously roll a new bar. During the new operating cycle of the PPM, the mandrel-removing operation is performed in station 18 and the mandrel, after being freed from the corresponding bloom. is conveyed to the cooling station 19.

WHAT WE CLAIM IS: 1. A device for coupling a mandrel to a mandrel-bearing slide in a piercing and pressure rolling mill (PPM) comprising a female guide open at top and bottom and secured to the slide. a male counter-guide secured to one end of the mandrel and adapted to be engaged or released bq sliding vertically into or out of the female guide through the open top and respectively open bottom thereof. and bolt means for removably secure the male counter-guide in the female guide.

2. A device according to Claim 1 wherein the bolt means comprise a rod borne by the mandrel-bearing slide so that it can slide in the direction of the rolling axis, the end of the rod facing the mandrel having a head adapted to engage substantially by fitting in to a cylindrical seat formed in the counterguide and coaxial with the rolling axis.

3. A device according to Claims 1 or 2 wherein the counter-guide comprises a para Ilelepipedal body co-axially secured to one end of the mandrel and the female guide substantially comprises a pair of vertical plates secured at the front to the mandrelbearing slide and having a chelate form owing to the presence of bent square ends.

4. A device substantially as hereinbefore described, with reference to, and as shown in, the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. using the hand lever 40 until the spherical head 38a is completely released by cup 32 of mandrel body 23; at the same time, clamps 7, 7 and 7a, 7a are opened by actuating the corresponding cylinders 9, 9 and 10, 10. Mandrel 3 and the associated bloom S rolled thereon falls on to the trough 21 underneath and mandrel body 23 simultaneously slides vertically off the corresponding seat formed by plates 35 and 36. At this stage, hydraulic cylinder 15 moves trough 11 to the lowered position shown by broken lines in Figure 2, in which mandrel 3 and bloom S are discharged on to the inclined plane 16 and transferred by gravity to the mandrel removing stations 18. At the same time as trough 11 is lowered, crane 21 removes the mandrel from station 19 after its piercing bit has been checked and lubricated and conveys it perpendicularly to the rolling axis A. Subsequently, crane 21 lowers the new mandrel until it parallelepipedal end body 23 slides into and engages the seat formed by plates 35, 36 of slide 4. The new mandrel is locked in the lastmentioned position after the spherical head 38a of bolt 38 has been completely inserted into cup 32. when the mandrel is held by clamps 7. 7 and 7a. 7a. After mandrel 3 has been secured. crane 21 releases it and returns to its starting position, during which time slide 4 moves forward under the action of cylinders 6. 6 and conveys the mandrel into the operating position in which its piercing bit is between the rolls in stand 1. At this stage, the PPM is ready to pierce and simultaneously roll a new bar. During the new operating cycle of the PPM, the mandrel-removing operation is performed in station 18 and the mandrel, after being freed from the corresponding bloom. is conveyed to the cooling station 19. WHAT WE CLAIM IS:

1. A device for coupling a mandrel to a mandrel-bearing slide in a piercing and pressure rolling mill (PPM) comprising a female guide open at top and bottom and secured to the slide. a male counter-guide secured to one end of the mandrel and adapted to be engaged or released bq sliding vertically into or out of the female guide through the open top and respectively open bottom thereof. and bolt means for removably secure the male counter-guide in the female guide.

2. A device according to Claim 1 wherein the bolt means comprise a rod borne by the mandrel-bearing slide so that it can slide in the direction of the rolling axis, the end of the rod facing the mandrel having a head adapted to engage substantially by fitting in to a cylindrical seat formed in the counterguide and coaxial with the rolling axis.

3. A device according to Claims 1 or 2 wherein the counter-guide comprises a para Ilelepipedal body co-axially secured to one end of the mandrel and the female guide substantially comprises a pair of vertical plates secured at the front to the mandrelbearing slide and having a chelate form owing to the presence of bent square ends.

4. A device substantially as hereinbefore described, with reference to, and as shown in, the accompanying drawings.