JP2023056367A - Machine tool - Google Patents

Abstract

To reduce the replacement frequency of a support member of an elongated workpiece.SOLUTION: A machine tool 100 includes: a main shaft part 1; a tail stock 2; and a chuck internal center 3. The main shaft part 1 has: a penetration port 17 to which an elongated workpiece W may be inserted; and a chuck 15 which holds the elongated workpiece W. The tail stock 2 is disposed so as to face the main shaft part 1 and contacts with a front end E1 of the elongated workpiece W protruding forward from the main shaft part 1 to support the elongated workpiece W. The chuck internal center 3 may move within the penetration port 17 according to a length of the elongated workpiece W and supports a rear end E2 at the opposite side of the front end E1 of the elongated workpiece W.SELECTED DRAWING: Figure 1

Description

The present invention relates to a machine tool for machining long workpieces.

2. Description of the Related Art A machine tool that processes a long work (referred to as a long work) is known (see Patent Literature 1, for example). This machine tool has a main shaft that grips one end in the longitudinal direction of the long work and rotates the long work, and a centering of the long work that is brought into contact with the other end of the long work away from the main shaft. and a tailstock.

2. Description of the Related Art Some machine tools for machining long works include a spindle that grips a long work with a part of the long work inserted therein. In addition to the main shaft and the tailstock, this machine tool further includes an in-chuck center that abuts on the end of the long workpiece on the side closer to the main shaft. In this machine tool, before being gripped by the spindle, the long workpiece is supported with the tailstock in contact with the end on the side farther from the spindle and the center in the chuck in contact with the end on the side closer to the spindle. be done.

JP 2010-99751 A

In conventional machine tools, the center inside the chuck cannot be moved. I had to change accordingly. That is, in the conventional machine tool, it was necessary to change the center in the chuck each time a long work having a different length was processed.

SUMMARY OF THE INVENTION An object of the present invention is to reduce the frequency of replacement of the center in the chuck in a machine tool for machining long workpieces.

A plurality of aspects will be described below as means for solving the problem. These aspects can be arbitrarily combined as needed.
A machine tool according to one aspect of the present invention is a machine tool for machining a long work. The machine tool includes a spindle, a first support member, and an in-chuck center. The main shaft has a through hole into which a long work can be inserted, and a chuck that grips the long work. The tailstock is arranged so as to face the main shaft and supports the long work by coming into contact with the front end of the long work protruding forward from the main shaft. The center in the chuck is movable inside the through-hole according to the length of the long work, and supports the rear end of the long work opposite to the front end.

In the machine tool described above, the center in the chuck is movable inside the through-hole according to the length of the long work. As a result, when the front end of a long workpiece is supported by the tailstock and the rear end of the long workpiece is supported by the center in the chuck, the distance between the tailstock and the center in the chuck is adjusted to the length of the long workpiece. You can change it accordingly. As a result, there is no need to replace the center in the chuck for each long work in order to support long works of different lengths by the tailstock and the center in the chuck. Since it is not necessary to replace the center in the chuck for each long workpiece, the frequency of replacement of the center in the chuck can be reduced.

The tailstock may be retracted from the front end of the long work when machining the front end of the long work. Thereby, it is possible to prevent interference between the tailstock and the processing blade when processing the front end of the long work.

The tailstock may contact the front end of the long work when machining the outer peripheral surface of the long work. As a result, when machining the outer peripheral surface of the long work without interference between the tail stock and the machining blade, the front end of the long work can be supported by the tail stock and the long work can be held more stably.

The tailstock may be movable synchronously with the center in the chuck. As a result, a long work of any length can be moved while the front end of the long work is supported by the tailstock and the rear end is supported by the center in the chuck.

The center in the chuck may be movable to a position protruding from the through hole when the work is supplied or discharged. Thereby, a long work can be supported outside the spindle.

The chuck may be opened when the work is set on the spindle, and closed to grip the work when the work is processed. Thereby, the work can be set on the spindle and gripped.

Since it is no longer necessary to replace the center in the chuck that supports the long work for each long work having a different length, the frequency of replacement of the center in the chuck can be reduced.

The figure which shows the whole structure of a machine tool. The figure which shows the structure of a moving mechanism. FIG. 4 is a diagram (part 1) schematically showing the principle of movement of the center in the chuck by the movement mechanism; FIG. 2 is a diagram (part 2) schematically showing the movement principle of the center in the chuck by the movement mechanism; The figure which shows the functional block structure of a control part. FIG. 1 is a diagram (part 1) schematically showing the operation of the machine tool until a long workpiece is machined; FIG. 2 is a diagram (part 2) schematically showing the operation of the machine tool until the long workpiece is machined; FIG. 4 is a diagram showing the arrangement of the first support member when processing the first end of a long work; FIG. 11 is a diagram (part 1) schematically showing the operation of taking out a long workpiece after processing; FIG. 2 is a diagram (part 2) schematically showing the operation of taking out a long workpiece after processing; FIG. 6 is a diagram showing an example of a state in which long works of different lengths are supported by the first support member and the center in the chuck.

1. First Embodiment (1) Overall Configuration of Machine Tool A machine tool 100 will be described below. The machine tool 100 grips one end side of a long work (hereinafter referred to as a long work W) by a chuck provided on a main shaft, and performs processing such as cutting, drilling, etc. on the other end side of the long work W. It is a lathe for The spindle can hold a part of the long work W inserted therein.

The overall configuration of the machine tool 100 will be described with reference to FIG. FIG. 1 is a diagram showing the overall configuration of a machine tool 100. As shown in FIG. The machine tool 100 includes a spindle portion 1 , a tailstock 2 , a chuck center 3 , a first turret 4 , a second turret 5 , and a control portion 6 .

The main shaft portion 1 grips a long work W to be processed and rotates it around its axis. The spindle section 1 has a headstock 11 , a spindle 13 and a chuck 15 . The spindle 13 is rotatably supported by the headstock 11 . The main shaft 13 is rotated by being driven by a main shaft motor 19 (FIG. 5). The chuck 15 is provided on the side of the spindle 13 facing the tail stock 2 and grips the long workpiece W. As shown in FIG.

The headstock 11, the spindle 13, and the chuck 15 are provided with a through hole 17 passing through them. A part of the long work W in the longitudinal direction can be inserted into the through hole 17 . The chuck 15 can grip the long work W partly inserted into the through hole 17 .

The tailstock 2 is a member with a conical tip. The tailstock 2 is attached to the support base 21 so that the tip thereof coincides with the center position of the main shaft 13 . The support base 21 is driven by a first servomotor 25 (FIG. 5) to move along a guide 23 so as to advance and retreat with respect to the main shaft portion 1 . As the support base 21 moves, the tailstock 2 also advances and retreats with respect to the main shaft portion 1 .

The in-chuck center 3 is a member with a conical tip. The in-chuck center 3 is attached to the tip of the attachment shaft 31 and is inserted into the through hole 17 from the headstock 11 side. The position of the tip of the in-chuck center 3 coincides with the center position of the spindle 13 . The mounting shaft 31 can be moved along the longitudinal direction in which the through-hole 17 extends by a moving mechanism 33 (FIG. 2), which will be described later. As the mounting shaft 31 moves in the longitudinal direction of the through-hole 17 , the chuck center 3 moves along the longitudinal direction of the through-hole 17 inside the through-hole 17 .

As shown in FIG. 1, the sharp tip of the tailstock 2 contacts the front end E1 of the long work W, and the sharp tip of the center 3 in the chuck is the rear end E2 of the long work W opposite to the front end E1. , the tailstock 2 and the in-chuck center 3 can support the long workpiece W from both ends.

The first turret 4 is rotatable around an axis parallel to the longitudinal direction of the main shaft portion 1 . A workpiece gripper 41 is attached to the peripheral surface of the first turret 4 . The workpiece gripper 41 can grip a predetermined position of the long workpiece W in the longitudinal direction. The workpiece gripper 41 is, for example, a device such as a gantry loader capable of gripping an article. The long work W can be supplied to the vicinity of the chuck 15 of the main shaft part 1 by turning the first turret 4 while the work gripping part 41 grips the long work W. As shown in FIG.

The second turret 5 is rotatable around an axis parallel to the longitudinal direction of the main shaft portion 1 . A processing blade 51 is attached to the peripheral surface of the second turret 5 . By turning the second turret 5 to which the machining blade 51 is attached to bring the machining blade 51 into contact with the part of the long work W to be machined and rotating the long work W, the long work W can be machined. . The processing blade 51 is, for example, a cutting tool. A plurality of processing blades 51 may be attached to the peripheral surface of the second turret 5 .

The control unit 6 is a computer system including a CPU, storage devices (RAM, ROM, SSD, HDD, etc.), and various interfaces, and controls each component of the machine tool 100 . The control unit 6 receives a user's operation using, for example, an operation panel, and controls the machine tool 100 based on the operation. Part or all of the control of the machine tool 100 by the control unit 6 may be realized by the control unit 6 executing a program stored in the storage device of the control unit 6. It may be implemented by hardware that

(2) Moving Mechanism of In-Chuck Center The moving mechanism 33 for moving the in-chuck center 3 will be described with reference to FIG. FIG. 2 is a diagram showing the configuration of the moving mechanism 33. As shown in FIG. The moving mechanism 33 has an end plate 331 , a stopper 332 , a drive shaft 333 , a rotating member 334 , a second servomotor 335 and a hydraulic cylinder 336 .

The mounting shaft 31 is fixed to one end of the end plate 331, and the shaft 337 of the hydraulic cylinder 336 is fixed to the other end. The end plate 331 contacts the stopper 332 . A hydraulic cylinder 336 applies pressure to the end plate 331 toward the stopper 332 via a shaft 337 .

One end of a drive shaft 333 is fixed to the stopper 332 . A thread is formed on the longitudinal side surface of the drive shaft 333 . The drive shaft 333 is screwed onto the rotating member 334 .

The rotating member 334 is rotated by the rotation of the output rotating shaft of the second servomotor 335 . The rotation of the output rotary shaft of the second servomotor 335 is transmitted to the rotating member 334 by the transmission belt 338 .

The principle of moving the in-chuck center 3 by the moving mechanism 33 having the above configuration will be described below with reference to FIGS. 3 and 4. FIG. 3 and 4 are diagrams schematically showing the principle of movement of the in-chuck center 3 by the movement mechanism 33. FIG.

As shown in FIG. 3 , when the rotating member 334 is rotated in a predetermined direction by driving the second servomotor 335 , the driving shaft 333 is moved to move the stopper 332 closer to the rotating member 334 . When the stopper 332 approaches the rotating member 334 , the terminal plate 331 in contact with the stopper 332 also moves in the direction approaching the rotating member 334 . As the end plate 331 moves toward the rotary member 334 , the in-chuck center 3 attached to the attachment shaft 31 moves inside the through hole 17 in a direction protruding from the through hole 17 .

On the other hand, as shown in FIG. 4, when the second servomotor 335 drives the rotating member 334 to rotate in a direction opposite to the predetermined direction, the drive shaft 333 moves to separate the stopper 332 from the rotating member 334 . move in the desired direction. When the stopper 332 separates from the rotating member 334 , the terminal plate 331 in contact with the stopper 332 also moves away from the rotating member 334 . As the end plate 331 moves away from the rotating member 334 , the chuck center 3 attached to the attachment shaft 31 moves inside the through hole 17 in the direction of being drawn into the through hole 17 .

(3) Functional Block Configuration of Control Unit A functional block configuration of the control unit 6 that controls the machine tool 100 will be described with reference to FIG. FIG. 5 is a diagram showing a functional block configuration of the control section 6. As shown in FIG. Some or all of the functional blocks described below may be implemented by the control unit 6 executing a program stored in the storage device, or may be implemented by hardware that constitutes the control unit 6. . The control unit 6 has a spindle control unit 61, a tailstock control unit 62, an in-chuck center control unit 63, a work supply control unit 64, and a machining blade control unit 65 as functional blocks.

The spindle control unit 61 controls the rotation of the spindle 13 by controlling the spindle motor 19 . Further, the spindle control unit 61 controls opening and closing of the chuck 15 . The tailstock controller 62 controls the movement of the support base 21 to which the tailstock 2 is attached by controlling the first servomotor 25 . The in-chuck center control unit 63 controls the movement of the in-chuck center 3 by controlling the second servo motor 335 .

The work supply control unit 64 controls the supply of the long work W to the machine tool 100 and the discharge from the machine tool 100 . Specifically, when supplying the long work W to the machine tool 100, the work supply control unit 64 causes the work gripping unit 41 to grip the long work W, and then rotates the first turret 4. , the long work W gripped by the work gripping portion 41 is supplied between the main shaft portion 1 and the tailstock 2 .

On the other hand, when discharging the long work W, the work supply control section 64 rotates the first turret 4 to move the work gripping section 41 to a position between the main shaft section 1 and the tailstock 2, and then , the long workpiece W arranged between the main shaft portion 1 and the tailstock 2 is gripped by the workpiece gripping portion 41 . Further, the work supply control unit 64 rotates the first turret 4 in the opposite direction to move the work gripping unit 41 gripping the long work W out of the position between the spindle 1 and the tail stock 2. position.

The machining blade control unit 65 rotates the second turret 5 to bring the machining blade 51 into contact with the work placed between the main shaft 1 and the tailstock 2, or to move the machining blade 51 out of the work after machining. move to position. When a plurality of processing blades 51 are attached to the peripheral surface of the second turret 5, the processing blade control unit 65 rotates the second turret 5 up to an angle corresponding to the position of the peripheral surface to which the processing blade 51 to be used is attached. The turret 5 is rotated to bring the machining blade 51 into contact with the work.

(4) Machining Operation in Machine Tool (4-1) Operations until Long Work is Machining Below, the machining operation of the long work W using the machine tool 100 having the above configuration will be described. First, with reference to FIGS. 6A and 6B, the operation until the long work W is processed will be described. 6A and 6B are diagrams schematically showing operations of the machine tool 100 until the long workpiece W is machined. Below, the operation will be described taking as an example the case where the outer peripheral surface of the long work W is machined by the machine tool 100 .

First, the work supply control unit 64 instructs the work gripping unit 41 to grip the long work W to be processed. The workpiece gripper 41 grips the long workpiece W at its center of gravity. After that, the first turret 4 is rotated to place the long work W between the main shaft portion 1 and the tailstock 2 as shown in FIG. 6A (a).

Since the work gripping portion 41 grips the long work W at the center of gravity, the long work W is stable between the main shaft portion 1 and the tailstock 2 without deviating from the center of the main shaft 13 . are placed.

After placing the long work W between the main shaft 1 and the tailstock 2, the main shaft control unit 61 opens the chuck 15 and places the long work W on the main shaft 1 as shown in (b) of FIG. 6A. can be set. Further, while the long work W is gripped by the work gripping unit 41, the chuck center control unit 63 drives the second servomotor 335 so that the front end of the chuck center 3 reaches the rear end E2 of the long work W. The center 3 in the chuck is moved until it abuts against (the end portion on the side closer to the main shaft portion 1).

As shown in (b) of FIG. 6A , the long work W is arranged with the rear end E2 positioned outside the main shaft portion 1 . Therefore, the chuck center controller 63 moves the chuck center 3 to a position where the front end of the chuck center 3 protrudes from the through hole 17 . The in-chuck center control unit 63 determines the amount of protrusion of the in-chuck center 3 from the through hole 17 according to the length of the long work W gripped by the work gripping unit 41 .

In this way, the chuck center 3 can be moved to a position where it protrudes from the through hole 17 , so that the chuck center 3 can support the long workpiece W arranged outside the spindle portion 1 . Further, since the chuck center 3 can be moved to any position, the amount of protrusion of the chuck center 3 from the through hole 17 can be adjusted. That is, since it can move to any position, it can contact the rear end E2 of the long work W of any length.

After the in-chuck center 3 is brought into contact with the rear end E2 of the long work W, the tailstock control unit 62 drives the first servomotor 25 to move the tailstock as shown in FIG. 2 abuts on the front end E1 of the long work W (the end on the side closer to the tailstock 2).

As described above, the tail stock 2 abuts the front end E1 and the chuck-in-center 3 abuts the rear end E2, whereby the long work W is supported at both ends thereof by the tail-stock 2 and the chuck-in-center 3. be.

After the long work W is supported by the tail stock 2 and the center 3 in the chuck, the work supply control unit 64 instructs the work gripping unit 41 to release the long work W from gripping.

After the work gripping portion 41 releases gripping of the long work W, the long work W supported by the tailstock 2 and the center 3 in the chuck is moved toward the spindle portion 1 . In this embodiment, while the rear end E2 side of the long work W is inserted into the through hole 17, the long work W is moved to a position where the front end E1 of the long work W projects forward from the main shaft portion 1. FIG. That is, the front end E1 side of the long work W protruding from the main shaft portion 1 is the portion of the long work W to be processed.

Specifically, the in-chuck center control unit 63 drives the second servo motor 335 to move the in-chuck center 3 in the direction of drawing it into the through hole 17 . Also, the tailstock control unit 62 drives the first servomotor 25 to move the tailstock 2 toward the main shaft unit 1 . At this time, as shown in (d) of FIG. 6B , the tailstock control unit 62 moves the tailstock 2 in synchronization with the movement of the chuck center 3 by the chuck center control unit 63 . Specifically, the tailstock control unit 62 moves the tailstock 2 at the same moving speed as the in-chuck center 3 .

By moving the tailstock 2 and the center in the chuck synchronously in this way, the tailstock 2 and the center in the chuck 3 can be moved while maintaining the mutual distance. As a result, the tailstock 2 and the chuck center 3 can move the long work W toward the through hole 17 while supporting the long work W of any length.

As shown in (e) of FIG. 6B, after the rear end E2 side of the long work W is inserted into the through hole 17 by the tailstock 2 and the chuck center 3, the spindle control unit 61 closes the chuck 15. , the chuck 15 grips the long workpiece W.

After the long work W is gripped by the chuck 15, the processing blade control unit 65 rotates the second turret 5 to bring the processing blade 51 into contact with the outer peripheral surface of the long work W to be processed. After that, the main shaft control unit 61 rotates the main shaft 13 by driving the main shaft motor 19 . As a result, the long work W gripped by the chuck 15 rotates around the longitudinal axis, and the outer peripheral surface of the long work W is machined by the machining blade 51 .

When the front outer peripheral surface of the long work W is the portion to be processed, if the processing blade 51 does not interfere with the tail stock 2, the tail stock 2 is positioned on the main shaft as shown in (e) of FIG. 6B. It may be in contact with the front end E1 of the long work W projecting forward from the portion 1 . As a result, the long workpiece W being processed can be held more stably.

On the other hand, as shown in FIG. 7, when the portion to be processed of the long work W is the front end E1, the processing blade 51 interferes with the tailstock 2. As shown in FIG. Therefore, when machining the front end E1, the tailstock control unit 62 moves the support base 21 away from the long work W before the machining blade 51 is brought into contact with the front end E1 of the long work W. to retract the tailstock 2 from the front end E1. FIG. 7 is a diagram showing the arrangement of the tailstock 2 when machining the front end E1 of the long work W. As shown in FIG.

In this way, when the front end E1 of the long work W is processed, the tail stock 2 can be retracted from the front end E1 of the long work W. Interference with the stock 2 can be prevented. As for the processing of the front end E1 of the long work W, for example, there is a drilling process of the front end E1.

In this embodiment, the chuck center 3 can be moved to any position in the through-hole 17 . Therefore, as described above, when the tailstock 2 is retracted from the front end E1 during machining of the long work W, regardless of the length of the long work W, the main shaft portion of the long work W The center 3 in the chuck can be brought into contact with the rear end E2 of the long work W while reducing the amount of protrusion from 1. As a result, even when the long work W is not supported by the tail stock 2, the in-chuck center 3 can be brought into contact with the rear end E2 to ensure the stability of the long work W as much as possible.

(4-2) Ejecting Operation of Long Work After Processing Next, the operation of ejecting the long work W after processing from the spindle portion 1 will be described with reference to FIGS. 8A and 8B. 8A and 8B are diagrams schematically showing the discharge operation of the long work W after processing.

After finishing the machining of the long work W, as shown in (a) of FIG. pull it away from the When the tailstock 2 is retracted from the front end E1 during machining of the long workpiece W, the tailstock controller 62 drives the first servomotor 25 until the tip of the tailstock 2 contacts the front end E1. The support base 21 is moved.

After that, the spindle control unit 61 opens the chuck 15 and releases the grip of the long workpiece W by the chuck 15 . As a result, the long workpiece W after processing is in a state of being supported by the tail stock 2 and the center 3 in the chuck.

After releasing the grip of the long work W by the chuck 15 , the long work W is moved to a position where the center of gravity of the long work W can be gripped by the work gripper 41 . Specifically, as shown in (b) of FIG. 8A , the chuck center control unit 63 drives the second servomotor 335 to move the chuck center 3 in the direction of protruding from the through hole 17 . Also, the tailstock control unit 62 drives the first servomotor 25 to move the tailstock 2 away from the main shaft unit 1 .

At this time, as in the case of moving the long work W toward the through hole 17 , the tail stock control unit 62 moves the tail stock 2 in synchronization with the movement of the chuck center 3 by the chuck center control unit 63 . move. As a result, the tailstock 2 and the center 3 in the chuck can move in the direction of discharging the long work W from the through hole 17 while supporting the long work W of any length.

After the center of gravity of the long work W moves to a position facing the first turret 4, as shown in (c) of FIG. 41 is moved to the position of the long work W. After that, the work supply control unit 64 instructs the work gripping unit 41 to grip the long work W. FIG. As described above, at this point, the long work W has moved to a position where the center of gravity of the long work W can be gripped by the work gripper 41 . Therefore, the work gripping part 41 can grip the position of the center of gravity of the long work W. As shown in FIG.

After the long workpiece W is gripped by the workpiece gripper 41, the tailstock controller 62 drives the first servomotor 25 to remove the tailstock 2 from the long workpiece W as shown in (d) of FIG. 8B. Move them away from each other. Further, the chuck center control unit 63 drives the second servomotor 335 to move the chuck center 3 away from the long workpiece W. As shown in FIG. As a result, the support of the long workpiece W by the tailstock 2 and the center 3 in the chuck is released.

After releasing the support of the long work W by the tail stock 2 and the chuck center 3 , the work supply control unit 64 rotates the first turret 4 to move the work gripping unit 41 . As a result, the long work W gripped by the work gripping portion 41 is ejected from the position between the main shaft portion 1 and the tailstock 2, as shown in (e) of FIG. 8B.

As described above, in the machine tool 100 , the chuck center 3 can move inside the through hole 17 according to the length of the long work W. As a result, when the long work W is supported by the tail stock 2 and the center 3 in the chuck, the distance between the tail stock 2 and the center 3 in the chuck is changed to correspond to the length of the long work W. can.

Specifically, when a long work (long work W) is to be processed, as shown in FIG. Then, the center 3 in the chuck can be brought into contact with the rear end E2 of the long work W.

On the other hand, when a short workpiece W′ is to be machined, as shown in FIG. can abut against the rear end E2' of the work W'. FIG. 9 is a diagram showing an example of a state in which works of different lengths are supported by the tail stock 2 and the center 3 in the chuck.

As a result, in the machine tool 100, since the long works W having different lengths are supported by the tailstock 2 and the chuck center 3, there is no need to replace the chuck center 3 for each long work W. Since it is not necessary to replace the center 3 in the chuck for each long workpiece W, the frequency of replacement of the center 3 in the chuck is reduced.

2. Features of Embodiments The above embodiments can also be described as follows.
A machine tool (for example, machine tool 100) includes a spindle (for example, spindle 1), a tailstock (for example, tailstock 2), and a chuck internal center (for example, chuck internal center 3). The main shaft has a through hole (for example, through hole 17) into which a long work (for example, long work W) can be inserted, and a chuck (for example, chuck 15) that holds the long work. The tailstock is arranged so as to face the main shaft, and supports the long work by coming into contact with the front end (for example, front end E1) of the long work projecting forward from the main shaft. The center in the chuck is movable inside the through-hole according to the length of the long work, and supports the rear end (for example, the rear end E2) of the long work opposite to the front end.

In the machine tool described above, the center in the chuck is movable inside the through-hole according to the length of the long work. As a result, when the front end of a long work is supported by the tailstock and the rear end of the long work is supported by the center in the chuck, the distance between the tailstock and the center in the chuck is adjusted to the length of the long work. You can change it accordingly. As a result, there is no need to replace the center in the chuck for each long work in order to support long works of different lengths by the tailstock and the center in the chuck. Since it is not necessary to replace the center in the chuck for each long workpiece, the frequency of replacement of the center in the chuck can be reduced.

3. Other Embodiments Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the gist of the invention. In particular, multiple embodiments and modifications described herein can be arbitrarily combined as needed.

The moving mechanism 33 for moving the chuck center 3 (mounting shaft 31) is not limited to the structure described with reference to FIGS. If there is, it may have any configuration.

INDUSTRIAL APPLICABILITY The present invention can be widely applied to machine tools that machine long workpieces.

100 Machine Tool 1 Spindle 11 Headstock 13 Spindle 15 Chuck 17 Through-hole 19 Spindle Motor 2 Tailstock 21 Support Base 23 Guide 25 First Servo Motor 3 Center in Chuck 31 Mounting Shaft 33 Movement Mechanism 331 Terminal Plate 332 Stopper 333 Drive Shaft 334 Rotating member 335 Second servo motor 336 Hydraulic cylinder 337 Shaft 338 Transmission belt 4 First turret 41 Work gripper 5 Second turret 51 Machining blade 6 Control unit 61 Spindle control unit 62 Tail stock control unit 63 Chuck center control unit 64 Work supply control unit 65 Machining blade control unit W Long work E1 Front end E2 Rear end

Claims (6)

A machine tool for machining long workpieces,
a main shaft portion having a through hole into which the long work can be inserted, and a chuck for gripping the long work;
a tailstock arranged to face the main shaft portion and supporting the long work by contacting a front end of the long work protruding forward from the main shaft portion;
a chuck-inside center that is movable inside the through-hole according to the length of the long work and that supports the rear end of the long work opposite to the front end thereof;
machine tool. 2. The machine tool according to claim 1, wherein the tailstock retracts from the front end of the long work when machining the front end of the long work. 2. The machine tool according to claim 1, wherein said tailstock is in contact with said front end of said long work during machining of the outer peripheral surface of said long work. The machine tool according to any one of claims 1 to 3, wherein said tailstock is movable in synchronization with said chuck center. 5. The machine tool according to any one of claims 1 to 4, wherein the center in the chuck is movable to a position protruding from the through-hole when a work is supplied or discharged. 6. The machine tool according to any one of claims 1 to 5, wherein said chuck is opened when setting a work on said spindle portion, and closed to grip said work when said work is machined.

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