39results about "Tailstocks/centres" patented technology

This application discloses a fixing device for a double-ended stud bolt used in machine tools, relating to the technical field of machine tool fixtures. It includes a machine tool body, a chuck rotatably mounted on the machine tool body, an abutment member, and a tailstock slidably mounted on the machine tool body. The chuck is perpendicular to the sliding direction of the tailstock. The abutment member is rotatably mounted on the tailstock, with an abutment hole at one end away from the mounting rod, the center of which is at the same height as the center of the chuck. The chuck clamps one end of the double-ended stud bolt, and then the tailstock slides, causing the abutment member on the tailstock to abut against the other end of the double-ended stud bolt. One end of the double-ended stud bolt is held by the chuck, while the other end directly abuts against the abutment hole. This eliminates the need for pre-drilling and cutting off the drilled portion, simplifying the processing flow and improving production efficiency. Furthermore, it eliminates the need to reserve space for cutting off the drilled portion, saving production costs.

The present application belongs to the technical field of machine tool equipment, and in particular to a top pin structure of a vertical cradle five-axis turning and milling combined machine tool, comprising a machine tool, wherein the base of the machine tool is arranged in a U shape with the opening direction facing upwards. The structure, by arranging the top pin mechanism, significantly improves the accuracy and motion stability of the top pin pressure adjustment, the rolling contact design of the main and auxiliary balls greatly reduces the friction loss in the force transmission process, and the fine adjustment of the top pin pressure can be realized through the threaded transmission of the threaded rod, meeting the pressing needs of different material rods; the pre-compression structure of the spring provides stable pre-tightening force and realizes fast resetting of the top pin, avoiding jamming; the design of the guide sleeve and the hard alloy contact end limits the radial swing of the top pin, ensures the coaxiality of the top pin and the material rod, reduces the machining eccentricity error, and on the other hand, enhances the wear resistance of the top pin and prolongs the service life; the overall structure makes the top pin bear force evenly, effectively avoids the displacement of the material rod under pressure, and improves the workpiece size accuracy.

The application relates to the technical field of machining machine tools and discloses an intelligent turning machining machine tool based on multi-station numerical control, which comprises a machine tool body, a clamping mechanism arranged at one end of the machine tool body, a sliding rail arranged at the bottom of the clamping mechanism, a movable base slidingly installed on the sliding rail, a cutter mounting rack arranged at the top of the movable base, a cutting tool arranged on the cutter mounting rack through fasteners and a tailstock slidingly installed on the sliding rail, a chip breaking component is detachably arranged at the top of the cutter mounting rack, the chip breaking component comprises a high-pressure cooling assembly and a chip blocking assembly arranged on the high-pressure cooling assembly, and the chip blocking assembly comprises a baffle slidingly installed on the high-pressure cooling assembly. The baffle can move forward and backward and deflect in an angle along with the impact of the cutting chip through design, and the high-pressure cooling assembly can exert instantaneous impact load at the bending point of the cutting chip, so that the chip breaking effect is further strengthened, and the problem that the cutting chip slips on the surface of the baffle or cannot be broken is effectively avoided.

The utility model discloses a numerical control lathe tailstock stopper relates to lathe processing technical field. Including lathe bed, the top of lathe bed is slid and is installed with tailstock, and the top one end middle fixed mounting of lathe bed has the first stud for preventing tailstock and is used, the one end below of tailstock is provided with the limiting component for fixing tailstock position, and can adjust the spacing size, the utility model discloses through the base and the first stud fixed, complete the fixation of limiting component, the worm and the screw rod transmission structure push the top rod piece and tailstock welded fixed, form rigid mechanical locking, replace traditional friction brake, rotate the turntable drive worm gear drive, the locking force that the screw rod and fixed plate screw cooperation produces, can resist workpiece top tight counterthrust and centrifugal force, avoid tailstock displacement, need not rely on friction plate, through mechanical structure rigid fixed tailstock, prevent the locking failure caused by brake component wear, reach the effect that prevent tailstock deviation.

A machine tool includes: a tool rest (31) having a holder (36) that can hold a workpiece; a tool spindle (41); and a controller (51) that controls the machine tool. The controller (51) controls the tool spindle (41) to machine the workpiece to obtain an intermediate machined workpiece (W') including a first portion (160), a second portion (170), and a coupling portion (180) that couples the first portion (160) and the second portion (170), controls the tool rest (31) to hold the first portion (160) by the holder (36), and controls the tool spindle (41) to cut the coupling portion (180), with the first portion (160) held by the holder (36).

The utility model relates to the technical field of special fixture of automobile parts, specifically discloses a special fixture for hard turning of shaft parts for machine -added equipment, and the machine -added equipment has the floating chuck connected with it to make floating chuck can follow the part movement in the processing process, the special fixture for hard turning includes first needle and second needle, first needle and second needle are located at both ends of the part respectively to respectively resist the end face of the part, wherein, first needle is arranged in the clamping jaw of floating chuck, thereby, the technical problem that the insufficient clamping precision and the machining quality difficult to guarantee existing in the current automobile parts machining process are solved.

The utility model provides an inclined bed body line rail numerical control lathe tailstock relates to numerical control lathe field. Including U type frame, the inside of U type frame is provided with the adjusting mechanism that can adjust tailstock, the adjusting mechanism includes with U type frame one side fixedly connected with motor, the output shaft of motor is fixedly connected with first rotation axis, the outer fixed surface of first rotation axis is connected with first spur gear, the outer surface of first spur gear is also engaged with second spur gear. This numerical control lathe tailstock passes through motor, first rotation axis, first spur gear, second spur gear, third spur gear, sliding sleeve, fixed ring, adjusting block, fourth spur gear, rotating handle and the cooperation of threaded rod, when the worker operates, the staff can adjust tailstock body, can drive first spur gear and second spur gear and rotate through motor, and the staff rotates rotating handle and can move third spur gear and fourth spur gear, realize to the left and right adjustment of lathe tailstock.

The utility model provides a disc tailstock of a numerical control machine tool, which comprises a tailstock body, the front side of the tailstock body is rotatably matched with a turntable, the bottom of the tailstock body is fixedly provided with a connecting base, the top of the tailstock body is fixedly provided with an oil storage tank, and the front side of the oil storage tank is provided with an oil transportation frame communicated with the oil storage tank. An opening and closing assembly is arranged in the oil conveying frame, a gap is formed between the rotary disc and the tailstock body, and an oil conveying pipe which is communicated with the oil conveying frame and located in the gap is arranged at the bottom of the oil conveying frame. Through the design of the opening and closing assembly, the cooperation of the annular opening and closing block and the oil conveying pipe connecting port and the cooperation of the reset function of the spring, the oil conveying channel can be automatically closed when lubricating liquid is not added, the design that the operation disc is linked with the spiral conveying blade and the annular opening and closing block is adopted, and an operator only needs to simply rotate the operation disc; therefore, lubricating liquid conveying and channel opening and closing control can be synchronously achieved.

This utility model belongs to the field of CNC lathe servo tailstock technology, specifically a high-precision servo tailstock for CNC lathes, including a support platform; a movable tailstock is slidably connected to the top of the support platform; a servo motor is fixedly connected to the side wall of the support platform; a lead screw is fixedly connected to the output end of the servo motor; the lead screw is threadedly connected to the middle of the movable tailstock; a lubrication mechanism is installed on the side wall of the movable tailstock; a dustproof mechanism is installed on the side wall of the movable tailstock; the lubrication mechanism includes a first liquid storage tank, a fixed rod, a rotating cylinder, a piston, a transmission block, a spring, an inlet pipe, an outlet pipe, and a one-way valve; the first liquid storage tank is located on the top of the support platform; through the above structure, lubricating liquid can be automatically sprayed onto the lead screw near the movable tailstock when the movable tailstock moves, thereby achieving lubrication between the lead screw and the movable tailstock, reducing component wear and the operating load of the servo motor.

This utility model discloses a tailstock locking device for lathes, including a tailstock slide plate, a nut seat, several wedges, and several fixing members. The tailstock slide plate has a connecting through hole and a recess. The recess is located on one side of the connecting through hole and communicates with it. The extension direction of the recess is perpendicular to the sliding direction of the tailstock body. The nut seat at least partially passes through the connecting through hole, and the side of the nut seat and the recess form a wedge-shaped groove. The wedges are adapted to the wedge-shaped groove. Several wedges are arranged at intervals along the same straight line in the wedge-shaped groove. The wedges have wedge-shaped inclined surfaces, and the recess has an inner inclined surface adapted to the wedge-shaped inclined surface. Each fixing member is configured to pass through the corresponding wedge and be securely connected to the recess. When the fixing member moves the wedge, the wedge-shaped inclined surface of the wedge and the inner inclined surface of the recess are in close contact to lock the nut seat in the connecting through hole. This solves the problems of high assembly requirements and unstable connection in traditional lathe tailstock fixing methods.

The utility model discloses a kind of easily replaced poking centre, including installation handle, and the one end of installation handle is rotatably connected with poking end disc.The utility model, when needing to replace centre, simultaneously push two sides push rod, make push rod pass baffle and drive plug rod to overcome spring elasticity and remove plug-in slot inside, so that centre can rotate, so that centre can drive clamping block to remove the inside of clamping slot by rotation, disassembly is completed to centre, then the centre that needs to be installed is taken out, when centre enters installation slot, centre pushes plug rod and overcomes spring elasticity and shrinks into plug rod slot, simultaneously clamping block enters clamping slot, after being rotated, make clamping block be clamped into L-shaped clamping slot, simultaneously plug rod slot and plug-in slot are just aligned, spring drives plug rod and inserts plug-in slot, avoid centre to drive clamping block to remove the inside of clamping slot by rotation, the installation of centre can be completed, by the installation structure of the centre, centre can be quickly disassembled and assembled, so as to disassemble and assemble maintenance or replace to centre.

This utility model provides a machining fixture for bearing seats, comprising a machining fixture positioning plate, a three-jaw chuck, and a lathe tailstock center. The machining fixture positioning plate is a circular plate-shaped workpiece structure with a central opening. The three-jaw chuck is fixedly mounted on one side of the machining fixture positioning plate. The lathe tailstock center is fixedly mounted on the other side of the back of the machining fixture positioning plate. This fixture utilizes the workpiece process positioning datum to design a lathe fixture that can be used on a hydraulic or conventional chuck with a clamping body, relying on the tailstock center for clamping force, to complete the integrated machining of the plane and outer diameter on a lathe, better ensuring the perpendicularity and parallelism requirements of the mounting surface.

The utility model relates to five axle tailstock structure technical field, concretely relates to a tailstock oil pipe straight -line connection mechanism, include: support unit, including tailstock, rotate nested unit, including coaxial nested hollow axle core, shaft stem, axle core rotatable installation in tailstock through bearing, and the shaft stem rotatoryly installs in the inside of axle core, liquid passage unit is for the oil duct that sets up along the axial direction of shaft stem, and both ends of oil duct all are sealed intercommunication with external pipeline through connecting piece. The shaft stem rotatoryly installs in the inside of axle core through bearing. The number of bearing of installing the shaft stem is two, and is first bearing and second bearing respectively, and the inside of axle core is provided with first annular groove, second annular groove along its axial direction both ends respectively, and first bearing, second bearing correspond press -pack in first annular groove, second annular groove. The utility model uses the shaft stem that is provided with oil duct to replace the oil pipe of prior art and place in the inside of axle core, to solve the problem of prior art, and the practicality is strong.

The present application relates to the technical field of machining, in particular to a high-precision machining method for a stainless steel slender valve rod, comprising: pretreating a stainless steel slender valve rod blank and forming a rotary reference hole; clamping the workpiece in a one-clamp-one-top manner and setting a follow-up tool rest, the pre-tightening force of the tailstock center being set according to the workpiece rigidity grade and the machining stage, the pre-tightening force in the finishing stage being smaller than that in the semi-finishing stage; completing semi-finishing and finishing in a one-time clamping state; performing online finishing machining on the lathe while maintaining the clamping state; and completing machining by cutting off the reserved margin at both ends. By establishing a hierarchical correspondence between the pre-tightening force and the workpiece rigidity and the machining stage, the present application realizes accurate quantitative control of the pre-tightening force, and cooperates with the one-time clamping and online finishing integrated process to effectively solve the problems of easy deformation and difficult precision control in the machining of the stainless steel slender valve rod.

This utility model relates to a fall prevention device for small box clamps in the field of aluminum electrolysis technology. It includes a wrench assembly with a hook plate. The upper end of the hook plate is rotatably connected to the lower part of the wrench assembly via a pivot. The lower end of the hook plate has a receiving groove. A locking assembly is fitted to the hook plate, comprising a fixing frame, a roller, and a linkage rod. The fixing frame is fixed to the upper part of the wrench assembly and connected to the roller via a connecting rod. The lower end of the linkage rod is fixedly connected to the hook plate and is angled to correspond to the roller. This utility model effectively improves the safety of the device, significantly reducing equipment damage and personal injury caused by falls. While ensuring safety, it does not add extra operating steps, ensuring efficient and continuous production and avoiding a decrease in production efficiency due to safety measures. The purely mechanical design has no electrical components, possesses excellent dust resistance and high-temperature resistance, high reliability, and significantly reduces maintenance costs.

A yoke clamping system (10) is provided for clamping a workpiece between two clamping inserts (101,201) for a grinding machine (1) which has a driven rotary axis (3) with a clamping cylinder (4) and a machine table (2), wherein the yoke clamping system (10) has: - a quill assembly (100) with a quill that can be received into the clamping cylinder (4) of the driven rotary axis (3) of the grinding machine (1) and actuated by this clamping cylinder (4), which carries a clamping insert, and - a tailstock (200) that can be fixed to the machine table (2) and which carries the other clamping insert, as well as a grinding machine (1) with such a yoke clamping system (10) and a method for using such a yoke clamping system (10)

This utility model discloses a highly stable clamping tip, relating to the field of tip technology. It includes a tip shank, a tip seat mounted above the tip shank, a tip head disposed inside the upper end of the tip seat, and a mounting groove formed inside the lower end of the tip head. The tip head also has several connecting grooves formed at equal angles inside, and the mounting grooves and connecting grooves are interconnected. A mounting base is fixedly mounted inside the tip seat, engaging with the mounting groove. Several sets of mounting blocks are slidably mounted inside the mounting base at equal angles, with each mounting block engaging with a corresponding connecting groove. A release element is installed between the mounting block and the tip seat, used to disengage the mounting block from the connecting groove. This highly stable clamping tip allows for quick tip head replacement through the mounting blocks and release element, and improves its stability and firmness during operation under centrifugal force.

An enhanced flanged live center includes a live center housing and a reinforcing member. The live center housing includes a front bearing cavity and a rear tapered shank for insertion into a tapered hole in a machine tool tailstock. The reinforcing member includes a flange ring and a reinforcing ring. The flange ring is fixed to the outer circumferential surface of the front bearing cavity. The reinforcing ring is C-shaped, and its two ends are connected by a second fastener, allowing the reinforcing ring to grip the outside of the machine tool tailstock. The flange ring and the reinforcing ring are connected by a first fastener, allowing the load borne by the front bearing cavity to be transferred to the machine tool tailstock through the reinforcing member. The enhanced flanged live center, with its reinforcing member for connecting to the machine tool tailstock, reduces the deflection of the live center and enhances its stability, thus improving the accuracy of the live center during rotation.

This invention relates to the field of machining auxiliary equipment technology, and provides a reversible double-center alignment device, including a reference handle, a first center base, a first center, a horizontal rotating rod, a second center base, and a second center. The first center base consists of an integrally connected base body, a rotating shaft with mutually perpendicular axes, and a rotating seat. The reference handle is rotatably fitted onto the outside of the rotating shaft and fixed by a vertical locking nut. One end of the horizontal rotating rod is rotatably fitted onto the outside of the rotating seat and fixed by a horizontal locking nut. The other end of the horizontal rotating rod is fitted onto the outside of one end of the second center base and fixed by a base limiting bolt. The first center is coaxially assembled onto the inside of the rotating seat via a center connecting sleeve, and the second center is coaxially assembled onto the inside of the second center base via a center fixing sleeve. This reversible double-center alignment device can quickly and accurately complete the reversible alignment of multiple planes, significantly saving alignment auxiliary time.

The utility model relates to numerical control machine tool technical field, concretely is a kind of radial runout suppression device of numerical control machine tool spindle, including the U-shaped seat, the top of the U-shaped seat is fixedly connected with support cylinder, the inside of support cylinder is provided with centre assembly, the centre assembly includes the movable cylinder of sliding joint with support cylinder, the one end of movable cylinder is rotatably connected with centre body, one end of support cylinder is provided with clamp, the clamp includes the clamping cylinder of rotatable connection with support cylinder.The utility model in, by traditional centre outside still be provided with clamping cylinder, when the one end of part does not satisfy centre installation, can use the inside multiple screw rods of clamping cylinder two cooperation arc plate clamping and fixing the one end of part, certainly for the part still can use centre body to be clamped to the centre hole, to realize clamp and centre assembly cooperation can satisfy the part clamping of the centre hole or not to open the centre hole.

The utility model relates to the technical field of a tailstock, and discloses a tailstock mechanism with a brake, which comprises an upper tailstock body, a clamping plate main body is fixedly arranged on the outer side of the upper tailstock body, a clamping device main body is arranged on the outer side of the clamping plate main body, a lower tailstock body is fixedly arranged below the upper tailstock body, and a brake is arranged on the lower tailstock body. And a position sensor is arranged below the clamping plate main body. According to the tailstock mechanism with the brake, the upper tailstock body and the lower tailstock body are made of gray cast iron materials, so that the upper tailstock body and the lower tailstock body have excellent wear resistance and shock absorption performance, and the wear resistance and the shock absorption performance of the device are improved; the tensile strength of the clamping plate is remarkably improved compared with common steel, the extremely high mechanical stress of a hydraulic clamping device is improved, then the stability of the structure is improved, meanwhile, through the sprayed nickel-based alloy coating, the high-temperature oxidation resistance and toughness are achieved, and the temperature resistance of the clamping plate body is improved.

The application discloses a tailstock and a machine tool. The tailstock comprises a main body, a tailstock assembly, a pressure measuring assembly and a driving assembly. The main body is provided with a receiving cavity which penetrates the main body along a first direction. The tailstock assembly is arranged in the receiving cavity and comprises a tip which extends out of the main body along the first direction. The tailstock assembly can reciprocate along the first direction and the opposite direction. A sealed cavity is arranged between the tailstock assembly and the main body. The cavity wall of the sealed cavity comprises at least part of the inner circumference of the main body and part of the outer circumference of the tailstock assembly. The volume of the sealed cavity can change with the movement of the tailstock assembly relative to the main body. The pressure measuring assembly is arranged in the main body and is connected to the sealed cavity to measure the pressure of the sealed cavity. The driving assembly is connected to the tailstock assembly to drive the tailstock assembly to reciprocate at a variable speed. The operator can adjust the speed of the driving assembly in driving the tailstock assembly to move in time by observing the pressure of the sealed cavity measured by the pressure measuring assembly, so that the pressure applied by the tailstock assembly to the workpiece can be adjusted, and thus the machining precision of the workpiece can be improved.

A yoke clamping system (10) for clamping a workpiece between two clamping inserts (101, 201) for a grinding machine (1) having a driven rotating shaft (3) with a clamping cylinder (4) and a machine table (2) is provided, wherein the yoke clamping system (10) comprises:a quill assembly (100) with a quill which can be accommodated in the clamping cylinder (4) of the driven rotating shaft (3) of the grinding machine (1) and can be actuated using said clamping cylinder (4), which quill carries the one clamping insert, anda tailstock (200) which can be fixed to the machine table (2) and which carries the other clamping insert,and a grinding machine (1) with such a yoke clamping system (10) and a method for using such a yoke clamping system (10)

The application provides a clamping device for machining a thin-walled rotary gyroscope structural member with internal threads, a tapered mandrel is connected with a locking cover through threads, an internal tapered surface of a tapered hole sleeve is matched with a tapered surface of the tapered mandrel, the tapered hole sleeve has an external thread structure and is connected with internal threads of a part to be clamped, a thin-walled rotary gyroscope part to be machined is screwed into the external threads of the tapered hole sleeve, the part is positioned by a locking cover end surface pressing against a left end surface of the part, and a right end surface of the part is pressed against by a conventional center. The application positions through cooperation of a tapered surface and a fastening assembly, has high repeated positioning accuracy, has small cumulative error in multiple clamping, and can ensure coaxial clamping each time.

This invention belongs to the field of rotor machining technology, specifically a screw compressor rotor helical groove machining device. It includes a machine bed, a worktable, and a mounting frame. Multiple symmetrically arranged X-axis guide rails are fixedly connected to the top of the machine bed. An X-axis servo motor is fixedly connected to one end of the machine bed. The output end of the X-axis servo motor is threadedly connected to an X-axis lead screw. A support seat is threaded onto the X-axis lead screw. Multiple Y-axis guide rails are fixedly connected to the top of the support seat. The worktable is slidably connected to the top of the Y-axis guide rails. A Y-axis servo motor is fixedly connected to one end of the support seat. The output end of the Y-axis servo motor is fixedly connected to a Y-axis lead screw. The worktable has threaded openings corresponding to the Y-axis lead screw. This invention solves the problem of the previous single-category machining capability, enabling the machining of other four-axis rotary products. Even without a rotary table, it can process suitable products as a three-axis machining center, broadening the machining range and improving equipment utilization.

The utility model discloses a tail top device for hobbing cutter processing, including base, the upper end of base is located at the both sides position department and is installed guide rail main part, adopts pneumatic tail top device, when replacing different specification cutter, need not like traditional device to carry out the complicated repeated dismounting and mounting operation to tail top, utilize lathe control cylinder's gas state to drive cylinder piston reciprocating motion, simplify tail top traditional complex control process simultaneously, in actual operation, only need through lathe to complete horizontal direction pneumatic regulation, cooperate manual needle installation block and carry out vertical direction position adjustment, can realize accurate clamping to work piece, not only improved work piece clamping's precision and consistency significantly, still greatly shortened equipment debugging time, let lathe can more efficiently put into processing procedure, improved lathe whole's processing efficiency actually, satisfy modern manufacturing industry's demand to high precision, high efficiency production fully.

A yoke clamping system (10) for clamping a workpiece between two clamping inserts (101, 201) is provided for a grinding machine (1) which has a driven rotary axis (3) with a clamping cylinder (4) and a machine table (2), wherein the yoke clamping system (10) comprises: - a quill assembly (100) with a quill that can be received into the clamping cylinder (4) of the driven rotary axis (3) of the grinding machine (1) and actuated by this clamping cylinder (4), which carries one clamping insert, and - a tailstock (200) that can be fixed to the machine table (2) and which carries the other clamping insert, as well as a grinding machine (1) with such a yoke clamping system (10) and a method for using such a yoke clamping system (10).

The application discloses a lathe cutting device for processing an elongated piston rod and relates to the technical field of lathe processing.The four limiting rods are distributed on the two sides of the clamp to form a stable rectangular support structure, and the movable clamp does not shake or deviate horizontally during the cutting process, so that the repeated accuracy during processing and the workpiece positioning stability are improved, which is particularly important for the elongated piston rod, vibration or bending caused by a high slenderness ratio is prevented, the sleeve ring and the limiting rod do not hinder the axial rotation of the piston rod, and the rotation processing, such as turning an external circle, threading or polishing, is supported, the clamping is still stable when the piston rod rotates, the processing accuracy is not affected, the clamping stability and the rotation freedom are considered, the limiting rod and the sleeve ring form multi-point constraint, even if there is vibration during the processing, the piston rod can be prevented from deviating, the processing safety is ensured, and the application is particularly suitable for high-speed cutting conditions.

This invention discloses a turning fixture for polyurethane wear-resistant components, comprising: a mandrel, at least two clamping blocks, and a locking assembly. A baffle is fitted around the mandrel. The two clamping blocks are slidably fitted around the mandrel along its axial direction. The component is fitted around the mandrel and located between the two clamping blocks. One clamping block is in limiting contact with the baffle. The locking assembly is fitted around the mandrel and located on the side of the other clamping block opposite to the baffle. The locking assembly and the side of the other clamping block opposite to the baffle are elastically in limiting contact, thereby clamping the component. This invention effectively clamps components that are elastic, reducing machining difficulty and improving machining accuracy.

To provide a composite working machine in which a tailstock unit can be moved without requiring a large power source and which can therefore materialize miniaturization as an entire device.SOLUTION: The composite working machine according to the present invention comprises: a tool spindle 110 to which a tool 112 is fitted in a replaceable manner; a workpiece spindle 120 to which a workpiece W is fitted in a replaceable manner; a Z-axis drive mechanism 140 which moves the workpiece spindle 120 in a Z-axis direction being a rotational axis direction of the workpiece W; a tailstock unit 130 which can move in the Z-axis direction; a pilot bar 160 which connects the workpiece spindle 120 and the tailstock unit 130 to each other in such a manner that relative spacing in the Z-axis direction between the workpiece spindle 120 and the tailstock unit 130 can be changed; and a clamp drive source 170 that moves the pilot bar 160 forward and backward in the Z-axis direction to change the above relative spacing.SELECTED DRAWING: Figure 1