CN213645372U

CN213645372U - Mandrel chuck device for feeding swing mechanism of seamless steel pipe cold rolling mill

Info

Publication number: CN213645372U
Application number: CN202022201915.2U
Authority: CN
Inventors: 陈涛
Original assignee: Baowu Special Metallurgy Co Ltd
Current assignee: Baowu Special Metallurgy Co Ltd
Priority date: 2020-09-30
Filing date: 2020-09-30
Publication date: 2021-07-09
Anticipated expiration: 2030-09-30

Abstract

A mandrel chuck device for a feeding and rotating mechanism of a seamless steel pipe cold rolling mill comprises a main shaft fixed by a positioning seat, wherein a rotating sleeve is sleeved at the middle position of the main shaft, a mandrel chuck device component is arranged at the front section position of the main shaft, a chuck sleeve is sleeved at the front section position of the main shaft, a cylindrical sleeve-shaped supporting guide sleeve is directionally arranged on the main shaft in the front section of the chuck sleeve from the end position of the front section of the main shaft, a jaw block is assembled in a T-shaped groove of the chuck sleeve, a sliding seat is arranged at the rear section position of the chuck sleeve, a rolling bearing is arranged in the sliding seat, a shifting fork swing rod is arranged at the lower part of the sliding seat and is connected with a hydraulic cylinder, a distance ring is sleeved on the end barrel body of the rear section of the chuck sleeve, and the positions of the chuck sleeve, the supporting guide sleeve and the sliding seat are limited and fixed by the, the supporting ring is a circular ring with a concentric different-diameter step hole and is assembled on the rear end part of the chuck sleeve.

Description

Mandrel chuck device for feeding swing mechanism of seamless steel pipe cold rolling mill

Technical Field

The utility model relates to a ferrous metallurgy machinery production facility field especially relates to a be applied to two roller periodic seamless steel pipe cold rolling mills of production seamless steel pipe and feed the plug chuck device in the rotation mechanism.

Background

Seamless steel pipes are common metallurgical metal products. The seamless steel pipe cold rolling technology is a main mode for producing, preparing and processing seamless steel pipes at present due to the characteristics of high rolling precision, high speed, high productivity, high yield, easy production organization and process technology adjustment and the like.

The seamless steel tube cold rolling production equipment is divided into two-roller type and multi-roller type according to the number of rollers, wherein the two-roller periodic cold rolling tube is used for carrying out normal-temperature cold deformation processing on a blank tube through a deformation tool consisting of a top, a core rod and a hole pattern, and is a seamless steel tube cold rolling mill which is most widely applied due to the characteristics of compact structure, large rolling force, high production capacity and the like.

The two-roller periodic cold pilger mill is a commonly used seamless steel pipe cold rolling device at present, and mainly comprises a feeding swing mechanism, a rolling mechanism, a transmission mechanism, a mandrel swing mechanism, a lathe bed supporting mechanism, a feeding and blanking mechanism, a hydraulic system, a process lubricating system, an electric automatic control system, a pneumatic system, an auxiliary mechanism and the like. The feeding and rotating mechanism consists of a mandrel chuck device, a mandrel fine-tuning device, a corner input and output device, a feeding and rotating cam device, a worm gear (worm) rod pair, a feeding swing rod device, a box body, a hydraulic pressure system, a lubricating system and the like, is arranged in the feeding and rotating gear box body in a set manner, has the using function of decomposing power output by a main motor into horizontal feeding motion and synchronous rotating motion in seamless steel pipe rolling, outputs the feeding (namely horizontal displacement) and rotating (namely radial rotation) synchronous motion required by rolling deformation of the seamless steel pipe, and outputs corresponding vector kinetic energy after speed reduction and direction change.

The mandrel chuck device in the prior art mainly comprises a main shaft, a rotating sleeve, a chuck, a positioning seat and other parts, the overall length is about 2m, the mandrel chuck device is in a slender structure, wherein the main shaft is a slender hollow shaft, the chuck comprises a guide cylinder, a supporting guide sleeve, a rolling bearing, a distance ring, an end cover, a jaw block body, a shifting fork swing rod and other elements, the rotating sleeve comprises a cylinder body, a rolling bearing, a gear, a distance ring, a supporting ring and other elements, and the positioning seat comprises a gear, a rolling bearing, a sliding seat and other elements; the chuck, the rotary sleeve and the positioning seat are sequentially and directionally installed on the main shaft, a shifting fork oscillating bar outside the chuck is connected with a hydraulic cylinder, and the chuck is driven to horizontally reciprocate on the main shaft through the horizontal reciprocating motion of a piston rod of the hydraulic cylinder, so that the opening and closing functions of a core rod jaw block body are realized; the positioning seat is connected with the mandrel fine adjustment mechanism, so that the function of axial adjustment of the mandrel is realized. The jaw block body is opened to provide a passage for the core rod and the seamless steel pipe coated on the outer circumferential surface of the core rod to enter the middle lathe bed, and the jaw block body is closed to lock the core rod, so that the core rod is prevented from escaping in the horizontal direction and is driven to rotate.

In the production practice, the cold rolling deformation processing movement process of the seamless steel tube mainly comprises the horizontal movement and the rotary movement of the tube blank, in the cold rolling deformation processing, the horizontal movement is the main movement, the rotary movement is the auxiliary movement, both the horizontal movement and the rotary movement are intermittent movement, and when the working machine frame is positioned at the foremost station and the last station in the machine base, the working machine frame is started and stopped simultaneously. Wherein: the horizontal motion is intermittent linear motion, a feeding rotary mechanism outputs power through a three-wire lead screw to drive a feeding chuck to move forwards (namely the direction of a rolling mechanism) to push a pipe blank, and the whole branch pipe blank is rolled from head to tail. The rotary motion is intermittent synchronous rotary motion, on one hand, the feed rotary mechanism transmits rotary power to the mandrel rotary mechanism, and the tube blank is subjected to intermittent rotary motion according to set parameters through clamping force of the front and rear chucks on the tube blank; on the other hand, the mandrel chuck device in the feeding rotary gear box body locks and drives the mandrel and the top head arranged at the foremost end of the mandrel to perform synchronous rotary motion, the function of the device is to ensure the coaxiality in the rolling deformation processing of the seamless steel tube, and the numerical value of the rotary motion is the rotary quantity of the tube blank rolling. Therefore, in terms of the working condition structure and function of the feeding and rotating mechanism, the mandrel chucking device mainly plays roles of locking and synchronous rotation of the mandrel, and is the only device in the feeding and rotating mechanism which directly participates in rolling deformation through the mandrel (namely, a plug) as a carrier, and the operation stability of the mandrel chucking device not only affects the output precision of the feeding and rotating mechanism, but also directly affects the operation state of the rolling mechanism.

For a mandrel chucking device, the stability of the operation of the chuck is a difficulty which affects the entire mandrel chucking device. The chuck is internally provided with three groups of jaw blocks, a bearing sleeve and the like in an equal division mode, elements such as a rolling bearing, a shifting fork oscillating bar and the like are arranged on the outer side of the chuck, horizontal reciprocating motion is realized under the driving of a hydraulic cylinder, synchronous rotation is realized under the driving of a rotary sleeve, and the locking and driving functions of the core rod are realized through the three groups of jaw blocks. Thus, in production practice, the chuck is the primary failure point for mandrel chuck assemblies, with the chuck sleeve swell being the most problematic equipment failure in the field. The expansion of the chuck sleeve means that the horizontal displacement of the guide cylinder on the main shaft is abnormal, and the hydraulic cylinder cannot drive the guide cylinder to move horizontally. The main reason is that the guide cylinder has a heavy weight of about 150kg, various elements are assembled inside and outside, the total weight exceeds 300kg, and the chuck sleeve needs to horizontally displace on the main shaft twice when one pipe blank is rolled. And the clearance fit tolerance of the guide cylinder and the main shaft is controlled to be 0.05-0.08 mm, once the guide cylinder is worn, the guide cylinder can generate a forward tilting phenomenon due to the unbalance of a weight structure, the end part of the guide cylinder is just like a scraper knife scraping the outer circumferential surface of the main shaft, rib-shaped burrs are generated, and finally, the stagnation and incarceration faults of the chuck sleeve on the main shaft are caused. The failure disposal needs to open a feeding rotary gear box body, replace wear failure parts such as clamping heads and the like, the labor and time consumption is high, the downtime is long, and the general downtime needs three working days.

The core rod chuck device after treatment does not eliminate the hidden trouble of failure from the source, and after a certain time of use, still can appear the stagnant and rising and inlay the pause trouble, consequently need carry out configuration optimization to current core rod chuck device, eliminate the hidden trouble of equipment trouble that produces because of dop sleeve slope from the source, promote equipment function precision to build.

Through the retrieval, "a cold pilger mill's chuck device that advances" that patent number is ZL200920214003.X most approximate, nevertheless it the utility model discloses it is different, the utility model discloses an install and feed in the rotation mechanism box, play the supporting and fixed and synchronous rotation function to the plug when seamless steel pipe is rolled. The feeding chuck device of the cold pilger mill is arranged on a lathe bed at the front side of a feeding rotary mechanism and has the function of pushing a seamless steel pipe blank to enter a rolling mechanism at a constant speed for deformation processing, and the seamless steel pipe blank and the rolling mechanism are completely different in structure, installation position and use function.

SUMMERY OF THE UTILITY MODEL

In order to solve the problems in the prior art, the utility model provides a mandrel chuck device for a feeding and rotating mechanism of a seamless steel tube cold rolling mill, which aims at the technical improvement of the mandrel chuck device in the feeding and rotating mechanism of the prior two-roller periodic seamless steel tube cold rolling mill, the design is reasonable, the structure is compact, the wear resistance is realized, the damage to the contact surface of a main shaft is small, the original matching precision is not damaged, the supporting function is continuous and stable, the supporting ring can be periodically replaced, the reasonable movement gap between the main shaft and the chuck sleeve is always ensured to be kept, the safety, the reliability, the practicability and the high efficiency are realized, the requirement of the cold rolling ordered production of a seamless steel tube production line is met, the production promoting function has certain elimination and cost reduction, the function precision construction is promoted, in addition, the utility model has strong universality, the mandrel chuck device in the feeding and rotating mechanism of the prior similar two, has certain reference and application values.

The utility model discloses a plug chuck device for seamless steel pipe cold rolling mill feeds rotation mechanism, its concrete structure is as follows:

the utility model provides a plug chuck device for seamless steel pipe cold rolling mill feeds rotation mechanism, includes the main shaft by positioning seat fixed position, its characterized in that:

the middle position of the main shaft is sleeved with a rotating sleeve, the front section of the main shaft is provided with a mandrel chuck device assembly, and the main shaft is axially positioned and locked by the mandrel chuck device assembly.

According to the utility model discloses a plug chuck device for seamless steel pipe cold rolling mill feeds rotation mechanism, a serial communication port, plug chuck device subassembly include supporting guide pin bushing, jaw piece, dop sleeve, sliding seat, antifriction bearing, pull out fork pendulum rod, distance ring and supporting ring, it specifically does, spindle anterior segment position department cup joints and has set up the dop sleeve, install cylindrical telescopic supporting guide pin bushing on the inside spindle of dop sleeve anterior segment from the tip position department of spindle anterior segment orientation, the jaw piece then assembles at the telescopic T type inslot of dop, the sliding seat sets up at the telescopic rear end position of dop, be provided with antifriction bearing in the sliding seat, and the lower part of this sliding seat is provided with pulls out the fork pendulum rod, this fork pendulum rod has connected the pneumatic cylinder, and cup joint on the tip stack shell of dop sleeve rear end and be provided with the distance ring, through this distance ring with the telescopic rear end position of dop sleeve, The positions of the supporting guide sleeve and the sliding seat are limited and fixed, the supporting ring is a circular ring with a concentric different-diameter step hole, and the supporting ring is assembled on the rear end part of the chuck sleeve.

The supporting guide sleeve meeting the corresponding rolling specification requirement is directionally installed on the main shaft in the front section of the chuck sleeve through the design, and finally the jaw block meeting the main shaft outer diameter requirement is directionally assembled and fixed in the T-shaped groove of the chuck sleeve, so that the on-line assembly of the mandrel chuck device is completed, the seamless steel pipe cold rolling production can be put into, and the locking function of the main shaft can be realized by replacing the supporting guide sleeve and the jaw block for seamless steel pipes of different specifications.

In addition, the supporting ring of one of the key points is designed to play a role in axial positioning and supporting, so that the chuck sleeve is continuously and stably, reasonable movement clearance between the main shaft and the chuck sleeve can be always ensured by regularly replacing the supporting ring, the supporting ring is wear-resistant and has small damage to the contact surface of the main shaft, and the requirement of ordered production of a seamless steel pipe cold rolling production line is met.

According to the utility model discloses a plug chuck device for seamless steel pipe cold rolling mill feeds rotation mechanism, a serial communication port, the dop sleeve divide into anterior segment and back end, be cylindrical, 3 departments are offered to the tip of anterior segment and are equidistant 120 circumference distributions and are provided with the T type groove of 45 angle of direction of leanin, the back end passes through connecting bolt and links together with the anterior segment, forms one set of cylinder structure, the telescopic anterior segment external diameter of dop is greater than the back end external diameter, and the telescopic anterior segment internal diameter of dop is the same with the back end internal diameter.

The external diameter of the front section of the chuck sleeve is larger and is used for setting a T-shaped groove which is inclined inwards by 45 degrees and has a guide angle, and the rear section of the chuck sleeve is a positioning section and is fixed in a position limiting way through a distance ring.

According to the utility model discloses a plug chuck device for seamless steel pipe cold rolling mill feeds rotation mechanism, a serial communication port, the jack catch piece total three, its concrete shape is the T type wedge that has the oil groove for processing on cockscomb structure, the top inclined plane for the bottom, the jack catch piece is the assembly of equidistant 120 circumference distributing types respectively in the telescopic three T type inslots of dop, and the jack catch piece agrees with each other with T type groove, will support guide pin bushing, dop sleeve and main shaft and fix together.

Different main shafts can be matched through the clamping jaw blocks with different heights and sizes, and the locking function of the main shafts with different specifications is met through synchronous adjustment.

Use the utility model discloses a plug chuck device for seamless steel pipe cold rolling mill feeds rotation mechanism has obtained following beneficial effect:

1. the utility model discloses a plug chuck device for seamless steel pipe cold rolling mill feeds rotation mechanism can be according to the overall arrangement and the service function requirement of each component of plug chuck device, optimize and adjust reasonable fit clearance between dop sleeve and main shaft, and accessible supporting ring plays the supporting role, prevent that the effect of inclining forward of dop sleeve is lasting stable, and the supporting ring can regularly be changed to the accessible, guarantee to keep reasonable movement clearance between main shaft and the dop sleeve all the time, in addition, copper alloy supporting ring realizes axial positioning through the ring channel, wear resistance is good and little to the main shaft contact surface damage, do not destroy the cooperation precision, avoid the rib burr to produce;

2. the mandrel chuck device for the feeding and rotating mechanism of the seamless steel pipe cold rolling mill has reasonable design, compact structure, safety, reliability, practicability and high efficiency, meets the requirement of ordered production of a seamless steel pipe cold rolling production line, has certain functions of eliminating faults, reducing cost and promoting production and promotes functional precision construction;

3. the utility model discloses a plug chuck device commonality that is used for seamless steel pipe cold rolling mill to feed rotation mechanism is strong, through adjustment supporting ring geometric dimensions, applicable in the seamless steel pipe cold rolling mill of each model of present widely used, to the improvement that present similar two roller periodic seamless steel pipe cold rolling mill fed the plug chuck device in rotation mechanism, has certain reference, using value.

Drawings

FIG. 1 is a schematic diagram showing the detailed structure of a mandrel chucking device for a feeding rotary mechanism of a seamless steel tube cold rolling mill according to the present invention;

FIG. 2 is a diagram showing the effect of the mandrel chucking device of the feeding rotary mechanism of the seamless steel tube cold rolling mill according to the present invention;

fig. 3 is a schematic diagram showing a specific structure of a chuck sleeve (front section) of a mandrel chuck device for a feeding rotary mechanism of a seamless steel tube cold rolling mill according to the present invention;

fig. 4 is a schematic structural diagram of a jaw block of a mandrel chuck device for a feeding rotation mechanism of a seamless steel tube cold rolling mill of the present invention.

In the figure: 1-main shaft, 2-positioning seat, 3-rotating sleeve, A-mandrel chuck device component, A1-supporting guide sleeve, A2-clamping jaw block, A3-clamping head sleeve, A4-sliding seat, A5-rolling bearing, A6-shifting fork swing rod, A7-distance ring, A8-supporting ring, A21-oil groove and A31-T groove.

Detailed Description

The mandrel clamping device for the feeding and turning mechanism of the seamless steel tube cold rolling mill of the present invention will be further described with reference to the accompanying drawings and embodiments.

Examples

The mandrel chuck device for the feeding and rotating mechanism of the seamless steel tube cold rolling mill is used for the cold rolling production deformation processing of nickel-based alloys and duplex stainless steel seamless tubes in steel tube factories of certain steel companies and is used on model numbers such as LG-220H, LG-150H, LG-110H, LG-60H, LG-30H and the like of the seamless steel tube cold rolling production line.

As shown in fig. 1 to 3, a mandrel chuck device for a feeding and rotating mechanism of a seamless steel tube cold rolling mill comprises a spindle 1 fixed by a positioning seat 2, a rotating sleeve 3 is sleeved at the middle position of the spindle, a mandrel chuck device assembly a is arranged at the front section position of the spindle, and the spindle is axially positioned and locked by the mandrel chuck device assembly.

The mandrel chuck device component A comprises a supporting guide sleeve A1, a jaw block A2, a chuck sleeve A3, a sliding seat A4, a rolling bearing A5, a shifting fork swing rod A6, a distance ring A7 and a supporting ring A8, and is characterized in that the front section of a main shaft 1 is sleeved with the chuck sleeve, the cylindrical sleeve-shaped supporting guide sleeve is directionally installed on the main shaft in the front section of the chuck sleeve from the end position of the front section of the main shaft, the jaw block is assembled in a T-shaped groove A31 of the chuck sleeve, the sliding seat is arranged at the rear section of the chuck sleeve, the rolling bearing is arranged in the sliding seat, the shifting fork swing rod is arranged at the lower part of the sliding seat and is connected with a hydraulic cylinder, the distance ring is sleeved on the end barrel body of the rear section of the chuck sleeve, the positions of the guide sleeve, the supporting sleeve and the sliding seat are limited and fixed through the distance ring, the supporting ring is a concentric different-diameter step, the support ring is mounted on the rear end of the chuck sleeve.

In this embodiment, the material of the support guide sleeve is Q235A, preferably HB 229-269 by thermal treatment, the material of the sliding seat is Q235A, preferably HB 220-255 by thermal treatment.

Dop sleeve A3 divide into anterior segment and back end, and is cylindrically, and 3 departments have been seted up to the tip of anterior segment and have been the equidistant 120 circumference and distribute and be provided with the T type groove A31 of 45 angle of direction of leanin, and the back end passes through connecting bolt and links together with the anterior segment, forms one set of barrel structure, and the telescopic anterior segment external diameter of dop is greater than the back end external diameter, and the telescopic anterior segment internal diameter of dop is the same with the back end internal diameter.

In the embodiment, the chuck sleeve is made of 42CrMo, heat treatment quenching and tempering processing is preferably performed on HB 262-302, the chuck sleeve is of a cylindrical structure, T-shaped grooves are processed on the end plane of the front section of the chuck sleeve according to trisection, the T-shaped grooves incline by 45 degrees from outside to inside, and the purpose is to be matched with the jaw clamps.

The clamping jaw blocks A2 are three in total, the specific shape of the clamping jaw blocks is a T-shaped wedge-shaped block with a sawtooth bottom and an oil groove processed on the inclined plane of the top, the clamping jaw blocks are respectively assembled in three T-shaped grooves A31 of the clamping head sleeve A3 in a distributed mode at intervals of 120 degrees in a circumference mode, the clamping jaw blocks are mutually matched with the T-shaped grooves, and the supporting guide sleeve, the clamping head sleeve and the main shaft are fixed together.

In this embodiment, the material of the jaw block is 42CrMo, the heat treatment thermal refining HB 229-269 is preferable, the bottom of the jaw block is equally divided into 4-5 saw teeth, and the top inclined surface is provided with oil grooves.

The utility model discloses a concrete process when on-spot assembly of a plug chuck device for seamless steel pipe cold rolling mill feeds rotation mechanism as follows:

the whole set of mandrel chuck device for the feeding rotary mechanism of the seamless steel pipe cold rolling mill of the utility model is arranged on the upper part of the box body of the feeding rotary mechanism, the specific position is that the end of a main shaft 1 is fixed on the box body by a positioning seat 2, a rotary sleeve 3 is connected with a mandrel fine-tuning device, a hydraulic cylinder is connected by a shifting fork swing rod A6, then an upper cover of the box body of the feeding rotary mechanism is fastened, a supporting guide sleeve A1 meeting the corresponding rolling specification requirement is directionally arranged on the main shaft in the front section of a chuck sleeve A3 from the end position of the front section of the main shaft, then three jaw bodies A2 meeting the main shaft external diameter requirement are directionally assembled in three T-shaped grooves A31 of the chuck guide cylinder for fixing, finally a distance ring A7 and a supporting ring A8 are sequentially arranged, the positioning and fastening of each part are confirmed, thus the assembly on-line of the mandrel chuck device on-, and seamless steel pipes of different specifications can realize the locking function of the core rod by replacing the supporting guide sleeve and the jaw body.

The utility model discloses a plug chuck device for seamless steel pipe cold rolling mill feeds rotation mechanism can be according to the overall arrangement and the service function requirement of each component of plug chuck device, optimize and adjust reasonable fit clearance between dop sleeve and main shaft, and accessible supporting ring plays the supporting role, prevent that the effect of inclining forward of dop sleeve is lasting stable, and the supporting ring can regularly be changed to the accessible, guarantee to keep reasonable movement clearance between main shaft and the dop sleeve all the time, in addition, copper alloy supporting ring realizes axial positioning through the ring channel, wear resistance is good and little to the main shaft contact surface damage, do not destroy the cooperation precision, avoid the rib burr to produce; the utility model has reasonable design, compact structure, safety, reliability, practicality and high efficiency, meets the requirement of the seamless steel pipe cold rolling production line for ordered production, has certain functions of eliminating faults, reducing cost and promoting production and promotes the construction of functional precision; the utility model discloses the commonality is strong, and through adjustment supporting ring geometric dimensions, applicable in the seamless steel pipe cold rolling mill of each model of present widely used, to the improvement that present similar two roller periodic seamless steel pipe cold rolling mill fed the plug chuck device in the rotation mechanism, has certain reference, using value.

The utility model discloses a seamless steel pipe that is used for seamless steel pipe cold rolling mill to feed rotation mechanism's plug chuck device is applicable to various models.

Claims

1. The utility model provides a plug chuck device for seamless steel pipe cold rolling mill feeds rotation mechanism, includes by main shaft (1) of positioning seat (2) fixed position, its characterized in that:

the middle position of the main shaft (1) is sleeved with a rotating sleeve (3), the front section of the main shaft is provided with a mandrel chuck device assembly (A), and the main shaft is axially positioned and locked by the mandrel chuck device assembly.

2. The mandrel chucking device for the feed rotation mechanism of the seamless steel pipe cold rolling mill as claimed in claim 1, wherein the mandrel chucking device assembly (a) comprises a support guide sleeve (a1), a jaw block (a2), a chuck sleeve (A3), a sliding seat (a4), a rolling bearing (a5), a shifting fork pendulum rod (a6), a distance ring (a7) and a support ring (A8), and is characterized in that the chuck sleeve is sleeved at the front section of the main shaft (1), the cylindrical sleeve-shaped support guide sleeve is installed on the main shaft at the front section of the chuck sleeve from the end position of the front section of the main shaft, the jaw block is installed in the T-shaped groove (a31) of the chuck sleeve, the sliding seat is arranged at the rear section of the chuck sleeve, the rolling bearing is arranged in the sliding seat, the shifting fork pendulum rod is arranged at the lower part of the sliding seat, and the shifting fork pendulum rod is connected with a hydraulic cylinder, and a distance ring is sleeved on the barrel body at the end part of the rear section of the chuck sleeve, the positions of the chuck sleeve, the supporting guide sleeve and the sliding seat are limited and fixed through the distance ring, the supporting ring is a circular ring with a concentric different-diameter step hole, and the supporting ring is assembled on the end part of the rear section of the chuck sleeve.

3. The mandrel chucking device for the feed rotation mechanism of the seamless steel tube cold rolling mill as claimed in claim 2, wherein the chuck sleeve (A3) is divided into a front section and a rear section, both of which are cylindrical, the end of the front section is provided with 3T-shaped grooves (a31) which are circumferentially distributed at equal intervals of 120 ° and are provided with guide angles inclining inwards by 45 °, the rear section is connected with the front section through connecting bolts to form a sleeve type structure, the outer diameter of the front section of the chuck sleeve is larger than that of the rear section, and the inner diameter of the front section of the chuck sleeve is the same as that of the rear section.

4. The mandrel chucking device for a feed turning mechanism of a cold rolling mill for seamless steel pipes as claimed in claim 2, wherein the number of said jaw blocks (a2) is three, and the detailed shape thereof is a T-shaped wedge block with a serrated bottom and an oil groove (a21) formed on the top slope, the jaw blocks are respectively assembled in three T-shaped grooves (a31) of the chuck sleeve (A3) in a circumferentially distributed manner at equal intervals of 120 °, and the jaw blocks are engaged with the T-shaped grooves to fix the support guide sleeve, the chuck sleeve and the main shaft together.