JPS6031601B2 - Turning machine tool turret - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a turning machine tool in which a tool holder for selectively holding an outer diameter cutting tool and an inner diameter cutting tool is provided on each surface of a turret head so as to be pivotally indexable. Hakama Umayasho 4916, which is related to a tool post and is an earlier application filed by the same applicant.
No. 5713 ``Related to improvements in the union of cutting tools in turning machine tools.

In recent years, the number of tools stored in the tool rest of a numerically controlled lathe has tended to increase in response to the functions of the numerical control device.

In other words, numerically controlled lathes can machine workpieces of any shape by changing the command tape, so the turret can also be equipped with a large number of tools to accommodate this.
It has become necessary to be able to respond to a variety of types of work with different settings. However, if a large number of inner and outer ridge cutting tools are simply arranged alternately on each side of the tool post, the workpiece and two types of tools will be separated within the cutting area of each inner and outer ridge cutting tool. Because of the coexistence of these tools, there is an inconvenience that the tools on both sides of the tool in the machining area will interfere with the workpiece, which limits the shape and size of the workpiece, and the turret inevitably has to become larger. .

The turret of the present invention solves the above-mentioned problems of the secondary turret, and is based on the basic idea of the turret of the earlier patent application No. 49-65713, ``On each side of the turret head,
The tool holder holding the inner light cutting tool and the outer light cutting tool is provided so as to be pivotally indexable, so that the inner light cutting tool or the outer light cutting tool can be pivoted to the cutting position as necessary. This is a further development of the blade union with a compact structure that eliminates interference.

That is, the first object of the tool rest of the present invention is to enable any combination of internal cutting tools and external cutting tools to be mounted on a pivotably indexable tool holder, thereby enabling specific When the outer diameter cutting tool is machining, all other tools are retreated from the machining area and do not interfere with the workpiece, and when a specific inner diameter cutting tool is machining, To provide a tool rest in which all other tools are retracted from a machining area and do not interfere with a workpiece.

In addition, the pivotable tool holder has flexibility in the number of external cutting tools and internal cutting tools that can be attached to provide a tool rest that can handle a wider variety of workpieces. be. A second object of the tool post of the present invention is that the tool holder, which is pivotally indexable on each side of the turret head, is mounted with its pivot center axis shifted from the pivot center of the turret head. Compared to the stand, more than 4.
To provide a tool post which allows an inner diameter cutting tool of the same length to be attached with a small swing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a turret for a turning machine tool according to the present invention will be described in detail below with reference to the drawings.

As shown in FIGS. 1 and 2, a carriage 2 is guided so as to be slidable in a direction parallel to the spindle axis on two guide surfaces IA and IB parallel to the spindle axis on the top surface of the bed. A cross slide 3 is provided on the shaft 2 so as to be slidable in a direction perpendicular to the spindle axis.

A turret support base 4 is fixed on the cross slide 3,
A four-sided drum-shaped turret head 5 is mounted on the turret support base 4 so as to be pivotable and indexable about a rattan line parallel to the main axis. On the right end surface of the turret head 5 and the left end surface of the turret support base 4, there are indexing teeth 6A that engage with each other in order to directly determine the indexing position of the turret head 5.
6B is installed. A gear 8 is attached to the rear end of the rotation center shaft 7 of the turret head 5, and a gear 1 is attached to the output shaft of an indexing motor 9 shown in FIGS.
It meshes with 0. A piston 11 is inserted on the rear outer periphery of the rotation center shaft 7 and is sandwiched between the stepped portion of the outer periphery of the rotation center shaft 7 and the end face of the gear 8. The piston 11 is slidably inserted into a cylinder hole 12 formed by a large-diameter stepped portion and a cover at the rear of the turret support base 4, and extends in the vertical direction integrally with the rotation center shaft 7. Therefore, when pressure oil is applied to the right cylinder chamber of the piston 11, the pivot shaft 7 integrated with the piston 11 moves forward, and the indexing teeth 6A and 6B disengage, causing the indexing motor to move forward. 9 to index the required turret surface to the processing position. Next, when pressure oil is poured into the left cylinder chamber, the pivot shaft 7 integrated with the piston 11 moves backward, the indexing teeth 6A and 6B engage, and the indexing and positioning operation of the turret head 5 is completed. do. As shown in FIGS. 1 and 5, in order to call the turret surface of the turret head 5 to the machining position, four rows of dogs D
-1 to D-4 are provided.

Dog D-"Well, the dogs D-2 and D-3 are for checking the clamping and unclamping of the turret head 5, the dogs D-2 and D-3 are for calling the turret surface, and the dog D-4 is for stopping the turret indexing. Limit switches -1 to LS-4 are provided on the turret support base 4 in correspondence with -1 to D-4.As shown in the first, second, third, and fourth figures, On each surface of the turret head 5, there is a
A bearing sleeve 13 is inserted and fixed, and a pivot 15 of a tool holder 14 is inserted into the bearing sleeve 13 so as to be pivotable. As shown in FIGS. 2 and 3, the tool holder 14 has a pivot 15.
A concave groove 16 parallel to the axis of the gaiyo cutting tool 1 is formed.
7 is attached with two bolts 18. Further, the tool holder 14 has a tool mounting hole 19 perpendicular to the groove 16, and in FIGS. is shown inserted and attached with two bolts 21. Furthermore, FIG. 8-A and FIG. 8-B show a state in which the outer diameter cutting tool 17 is attached to the work odor attachment hole 19 via the outer diameter cutting tool holder 22. That is, the outer tool holder 22 has the concave groove 16 of the tool holder 14.
A concave groove 23 having the same shape as the outer diameter cutting tool 17 is formed.
is attached by two bolts 24. The outer tool holder 22 has the same features as the inner diameter cutting tool 20,
The shank portion 22A is inserted into the work odor attachment hole 19 and fixed to the tool holder 14 with a bolt 21. Therefore, from the normal tip position of the outside tool and the inverted tip position of the inside tool shown in Figures 1 and 2, the cutting force that each tool receives at the cutting position is as shown by the arrow in Figure 7-1A. It works as shown. Therefore, the inner diameter cutting tool 20 and the outer diameter cutting tool 17 can be selectively attached to the tool holder 14, and by positioning the tool holder 14 by 90 degrees as described later, the required tools can be attached. It can be brought to the processing position. In order to accurately index and position the tool holder 14 by 90 degrees,
As shown in FIG. 2, a clutch is formed on the end surface of the tool holder 4 and the end surface of the bearing sleeve 13 so as to engage with each other.

That is, two 45-degree fan-shaped peaks 25A and 25B are formed to protrude from the end surface of the tool holder 14, and the bearing sleeve 13
There are two 45 degree fan-shaped peaks 26A, 26 on the end surface side of the
8 is protrudingly molded. Therefore, the tool holder 14 is
When pivoted by 0 degrees, the peaks 25A, 25 on the tool holder 14 side
The side surface of B comes into contact with the side surfaces of the peaks 26A, 26B on the side of the bearing tube 13, and accurate indexing and positioning is performed. Next, the pivot mechanism of the tool holder 14 will be explained. 1st, 2nd
As shown in FIG. 4, a pinion 15A is formed at the rear of the pivot shaft 15 of the tool holder 14. As shown in FIG. A cylindrical rack 28 having a square notch groove 27 is inserted into the center of rotation of the turret head 5, and the pinions 15A of the three tool holders 14 on the turret surface other than the machining position are engaged with the cylindrical rack 28. Pivoting of the three tool holders 14 other than the machining position is prevented. As shown in FIG. 1, a first piston 29 is inserted into the pivot shaft 7 so as to be slidable in the axial direction, and the tip of the first piston 29 is attached to the cylindrical rack 28. A square portion is formed to slidably fit into the square notch groove 27. A rack 30 is formed at the square end of the first piston 29, and meshes with the pinion 15A of the tool holder 14 indexed to the machining position. Therefore, pressure oil is selectively sent to the cylinder chambers before and after the first piston 29, and the first piston 29
By sliding 9 back and forth, the tool holder 14 indexed to the machining position can be pivoted 90 degrees. A cover 31 attached to the right end surface of the turret support base 4 has a shaft 33 attached to the center of the rotation center shaft 7 via a plate 32.
is installed.

The first piston 29 is connected to the key 3 at the tip of the shaft 33.
4 so that it can slide in the axial direction and be prevented from rotating. Therefore, the rack 30 at the tip of the first piston 29 and the cylindrical rack 28 are always kept at a constant position regardless of the pivoting movement of the pivot shaft 7. A second piston 35 is inserted into the pivot shaft 7 behind the first piston 29 so as to be slidable in the axial direction.

In order to selectively slide the first piston 29 and the second piston 35, the ratchet 33 has an oil passage 36A communicating with the rear cylinder chamber of the second piston 35, and an oil passage 36A that connects the first piston 29 and the second piston 35. An oil passage 368 communicating with the cylinder chamber between the first piston 35 and the first piston 35 is formed, and an oil passage 368 communicating with the front cylinder chamber of the first piston 29 is formed at the center of rotation 7.
is formed. When oil is supplied to the oil passages 36A and 36C and the oil passage 36B is connected to the tank side, the first piston 29 retreats and the second piston 35 moves forward.

Therefore, the tool holder 14 indexed to the machining position is
As shown in FIG. 2, the outer diameter cutting tool 17 attached to the groove 16 of the tool holder 14 is pivoted to the cutting position. However, due to the difference in pressure receiving area between the first piston 29 and the second piston 35, the first piston 29 comes into contact with the front end of the second piston 35 and stops, and does not retreat any further. When the first piston 29 is retracted to this position, the teeth of the rack 30 at the tip of the first piston 29 and the cylindrical rack 28 are aligned. In this state, there is some backlash between the teeth of the rack 30 and the pinion 15A. Therefore, the turret head 5
When rotating and indexing to call up a new turret surface, the pinion 15A of the tool holder 14 indexed to the machining position
The other tool holders 14 are smoothly transferred from the rack 30 to the cylindrical rack 28, and the other tool holders 14 are smoothly transferred from the cylindrical rack 28 to the third rack. When the oil passage 36A is connected to the tank side while pressure oil is being supplied to the oil passage 36C, the first piston 29 pushes the second piston 35 and retreats a little further from the previous position, moving the tool holder 14 into the Wakachien position. The side surfaces of the ridges 25A, 25B of the clutch are supported by the sides of the other ridges 26A, 26B, thereby achieving accurate pivot positioning of 90 degrees. As shown in Figures 2 and 4,
In order to prevent the tool holder 14 from slipping out of the turret head 5, a circular groove 37 is formed on the outer periphery of the intermediate portion of the pivot shaft 15 of each tool holder 14 in an angular range slightly larger than 90 degrees, and the pin 38 is inserted into the circular groove 37. The groove 37 is filled with iron. Furthermore, as shown in FIGS. 4 and 6, the turret support base 4
A positioning pin 39 for the tool holder 14 is provided on the left end surface of the tool holder 14.
is slidably inserted parallel to the bag line of the pivot axis 7. Further, on the outer periphery of the intermediate portion of the pivot shaft 15 of the tool holder 14, there is a positioning hole 40 into which the positioning pin 39 is inserted.
A, 40B are drilled at angular intervals slightly smaller than 90 degrees. Moreover, as shown in FIG. 6, the center of the positioning pin 39 is closer to the turning center of the turret head 5 than the center of the positioning holes 40A, 40B. When the tool holder 14 is inserted into the center of rotation of the turret head 5, the tool holder 14 is pulled toward the center of rotation of the turret head 5, and the clutch peaks 25A,
Since the side surface of 25B is turned in the direction of pressing against the side surface of peaks 26A and 26B, it is strongly clamped against the turret head 5. As shown in FIGS. 5 and 9, the turret support base 4 is formed with a small cylinder 41 for checking the pivot positioning process of the tool holder 14.
A piston 42 is slidably inserted.

When the piston 42 protrudes, its tip presses the limit switch LS-5 to confirm operation. Figures 1 and 2
As shown in the figure, a cutting agent supply passage 43 is provided at the axis of the shaft 33.
is formed.

Further, a distributor 44 is fixed to the front surface of the turret head 5, and at the center of the distributor 4,
A pipe 45 is inserted. Since the pipe 45 is fixed to the cylindrical rack 28 with a pin, the cutting agent is supplied via the pipe 45 and the distributor 44 to the cutting agent passage 46 on the turret surface side indexed to the processing position. The block 47 attached to each turret surface has a pipe 48A for supplying cutting agent to the Gaiyo cutting tool 17,
A pipe 48B for supplying a cutting agent to the inner diameter cutting tool 2 is attached, and the cutting agent is effectively supplied to each indexed inner and outer diameter tool through the cutting agent passage 46. The tool rest of the present invention has the above-mentioned configuration, but the ninth
The operation will be explained according to the hydraulic circuit diagram shown in the figure and the flowchart shown in FIG.

If the machining by the outside diameter cutting tool 17 on the turret surface that has been indexed to the machining position in the previous process is completed, the cross slide 3 and the gear IJ cutter 2 will be moved to the turret by the tape command. When the head 5 is rotated and indexed, the outer diameter and inner diameter cutting tools 17 and 20 are in a position where they do not interfere with the workpiece, and the tool holder 4
When pivoting, the outer and inner diameter cutting tools 17, 20 retreat to a position where they do not interfere with the workpiece.

Next, when a tool change command is issued from the numerical control device, the solenoids S of the solenoid valves 51 and 52 shown in FIG.
OLC and SOLD remain deenergized, and solenoids SOLA and SOLB of solenoid valves 49 and 50 are energized.

Therefore, since pressure oil is supplied to the right cylinder chamber of the piston 11 through the oil passage 54A, the pivot shaft 7 of the turret head 5 moves forward together with the piston 11, and the index tooth 6A moves forward together with the piston 11.
, 6B are disengaged.

At the same time, since the pressure oil from the oil passage 54A is integrated into the front cylinder chamber of the positioning pin 39 through the oil passage 55C, the positioning pin 39 is connected to the tool holder 1 in the machining & layer.
4 through the positioning hole 40A or 40B, and the tool holder 14 can be moved. When the positioning pin 39 is completely removed, pressure oil is supplied to the front cylinder chamber of the first pinion piston 29 of the tool holder 4 through the oil passage 55D, the solenoid valve 50, and the oil passage 36C.

The cylinder chamber between the first piston 29 and the second piston 35 is already connected to the oil passage 36B and the solenoid valve 5.
0, it is connected to the tank side via an oil passage 56, and pressure oil is supplied to the rear cylinder chamber of the second piston 36 through the oil passage 36A. Therefore, if the tool attached to the tool attachment hole 19 of the tool holder 14 has been indexed in the previous step, the first piston 29 will move back and pivot the tool holder 14 by about 90 degrees. The first piston 29 comes into contact with the front end of the second piston 35 and stops.
In addition, when the outer wall cutting tool 17 attached to the groove 16 of the tool holder 14 has been indexed in the previous step, the first piston 29 moves forward slightly together with the second piston 35, and The piston 35 of No. 2 stops at the position where it comes into contact with the stepped portion of the cylinder chamber. As mentioned above, regardless of the pinion position of the tool holder 14 in the previous process, the rack 3
0 and the teeth of the cylindrical rack 28, the turret head 5 can be rotated and indexed. As mentioned above,
When the turret head 5 floats up, the limit switch LS-1 for confirming clap and unclap is turned FF to confirm unclap, and at the same time, the piston 42 is protruded by the pressure oil passing through the oil passage 57, and the limit switch LS-5 is activated. Turn on. The next operation is started by the AND condition of these two IJ mitt switches. That is, the turret surface number commanded by the control device and the currently indexed turret surface number are compared, and if they match, the operation of rotating the turret head 5 is omitted and the operation described later is immediately performed. The pivoting movement of the tool holder 14 is started.

If they do not match, the solenoids S○LA and SOLB of solenoids 4 9 and 5 0 will be turned OFF as at the start.
N, Solenoid SOLD of solenoid valve 52 is OFF.
Leave it at F, solenoid SOL of solenoid valve 51
Since only C is turned on, pressure oil is supplied to the index motor 9 through the oil passage 36D and the solenoid valve 51, and the turret head 5 rotates. When the commanded turret surface is called, the solenoid SOL of the solenoid valve 52
Since D changes to ○N and the tank side passage of the indexing motor 9 is narrowed, the indexing motor 9 is decelerated.

Subsequently, when the turret index stop dog D-4 steps on the limit switch -4, the solenoid valves 51 and 52 are activated.
Because the solenoids SOLC and SOLD are both turned off,
The supply of oil to the motor 9 is stopped, and the turning operation of the turret head 5 is stopped. Next, the tool holder 14 is pivoted, and in the embodiment of the present invention, a total of eight internal and external tools are attached, and among them, the groove 16 of the tool holder 14
The numbers of the tools attached to the tool holder 14 are determined as TI to T4, and the numbers of the tools attached to the tool attachment hole 19 of the tool holder 14 are determined as T5 to T8.

Therefore, the tool numbers commanded by the control device are TI to T4.
In this case, the tool holder 14 and the turret head 5 are clamped. That is, the solenoids SOLA and SOLB of the solenoid valves 49 and 50 are OF.
F, pressure oil is supplied to the left cylinder chamber of the piston 11 via the oil passage 54B, the pivot shaft 7 moves backward, the index teeth 6A and 6B engage, and the turret head 5
An indexing clamp is performed. At the same time, Mr. Oil is in the oil passage 5.
6, the first through the solenoid valve 50 and the oil passage 36C.
The oil is supplied to the front cylinder chamber of the piston 29, and the oil passage 3
6A and 36B are connected to the tank side, so the first piston 29 pushes the second piston 35 and retreats a little further from the previous position, pivoting the tool holder 14 slightly, and moving the tool holder 14 side. The sides of the crests 25A, 25B of the clutch are supported by the sides of the other crests 26A, 26B to perform accurate positioning of the crests. When the pivot positioning of the tool holder 14 indexed to the machining position is completed, the oil passage 36C
, 56 increases, the sequence valve 5
Pressure oil is applied to the positioning pin 3 through the positioning pin 3 and the oil passage 55A.
9 into the rear cylinder chamber, and the positioning pin 39 is inserted into the positioning hole 40A.

Therefore, the tool holder 14 is pulled toward the center of rotation of the turret head 5, and the clutch mounts 25A, 2
Since the side surface of the turret head 5B is turned in a direction that presses the side surface of the ridge portions 26A and 26B, the turret head 5 is strongly clamped. When the positioning pin 39 jumps into the positioning hole 40A, pressure oil passes through the oil passage 55B and enters the small cylinder 41.
to retract the piston 42, the piston 42
The tip of will leave the limit switch LS-5. As mentioned above, it is completely specified by the AND condition of the signal indicating that the clamping of the work odor holder 14 is completed (Yama-ichi 5 turns OFF) and the signal that the clamping of the turret head 5 is completed (Melon-1 turns ON). It is confirmed that the indexing operation of the tool is completed, and the machining operation using the indexed tool is started. Next, when the tool number commanded by the control device is T5 to T8, the tool holder 14 is pivoted 90 degrees and clamped, and the turret head 5 is clamped.

That is, the solenoid SOLA of the solenoid valve 49
is turned off, and the solenoid SO of solenoid valve 50 is turned off.
Since LB is turned on, pressure oil is supplied to the left cylinder chamber of the piston 11, as in the case of TI to T4 described above.
An indexing clamping of the turret head 5 is performed. At the same time, pressure oil is supplied between the first piston 29 and the second piston 35 through the oil passage 54B, the oil passage 56, the solenoid valve 50, and the oil passage 36B, and the oil passages 36C, 3
6A is connected to the tank side, so the first piston 2
9 moves forward to pivot the tool holder 14 by 90 degrees, so that the side surfaces of the clutch ridges 25A, 25B on the tool holder 14 side are supported by the side surfaces of the other ridges 26A, 26B. When the positioning of the tool holder 14 is completed, the oil passage 36B
, 56 increases, the sequence valve 53 and the oil passage 55A increase as in the case of the TI-T4 described above.
Pressure oil flows into the rear cylinder chamber of the positioning pin 39 through the positioning pin 39, causing the positioning pin 39 to jump into the positioning hole 40B, thereby completing the clamping of the tool holder 14.

When the positioning pin 39 jumps into the positioning hole 40B,
As in the case of TI to T4 described above, the tip of the piston 42 moves away from the limit switch -5. Therefore, a signal (LS
-5 turns OFF) and the signal indicating completion of clamping of the turret head 5 (LS-1 turns ON), it is confirmed that the indexing operation of the specified tool is completely completed, and the indexing operation is completed. Machining operation by the tool is started.
In the embodiment of the present invention, a pivoting indexing type tool holder is arranged on all turret surfaces, but even when a part of the turret surface is equipped with this tool holder, interference between the tool and the workpiece may occur. This has the effect of increasing the number of tools.

According to the present invention, a tool holder capable of selectively holding an outer ridge cutting tool and an inner ridge cutting tool is provided on each surface of the turret head that can be pivoted and indexed,
The structure allows the external cutting tool or the internal light cutting tool to be pivoted to the cutting position, positioned, and clamped as required, so each surface of the turret head can be fully utilized to create a large number of internal and external flea cuts. Cutting tools can be stored in bags in an extremely compact manner.

When a specific external cutting tool is machining, all other tools are evacuated from the machining area, and when a specific internal cutting tool is machining, all other tools are evacuated from the machining area. Therefore, there is no interference with the workpiece in any machining process, and there is no restriction on the diameter of the workpiece. In the present invention, since the external cutting tool and the internal cutting tool can be selectively attached to the pivotable tool holder, flexibility is provided in the number of tools to be attached, and a wider variety of types can be provided. can be used for various types of work.

The present invention is configured such that the center axis of movement of the tool holder, which is pivotally indexable on each side of the turret head, is mounted offset from the center of rotation of the turret head. It is possible to attach an internal diameter cutting tool of the same length by swinging it around.

As mentioned above, the tool rest of the present invention can mount a large number of tools for cutting inside and outside diameters in an extremely compact manner, and since it is not limited by the shape of the workpiece, it can be cut into any shape by replacing the tape. This makes it possible to machine a number of workpieces, thereby significantly improving the functionality of the numerically controlled lathe.

In addition, since the external cutting tool and the internal cutting tool can be selectively attached to the same tool holder, for example, the cutting edges of the internal cutting tool and the external light cutting tool can be brought close to each other. When moving from to internal cutting, the extra stroke in the direction perpendicular to the spindle axis can be reduced.

According to the present invention, the use of the outer diameter cutting tool and the inner diameter cutting tool is carried out by the pivoting device of the tool holder, and the positioning and clamping of the pivoting device is carried out inside the turret head, so that chips, dust, etc. Therefore, the accuracy of pivot positioning of the tool holder does not deteriorate.

As stated above, the present invention is not limited to the basic structure shown in the examples, and modifications are expected within the scope of the technical idea of the present invention as described in the claims. .

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of the tool rest of the turning machine tool of the present invention, Fig. 2 is a partially sectional front view of the turret, Fig. 3 is a longitudinal sectional view of the tool holder, and Fig. 4 is the tool holder. Fig. 5 is a cross-sectional view showing the positioning mechanism of the turret surface and the arrangement of limit switches related to clamping, and Fig. 6 shows the phase relationship between the positioning pin and the positioning hole of the tool holder. Developed view, Figure 7-A is a front view of the clutch on the bearing cylinder side, Figure 7-B is a front view of the clutch on the tool holder side, and Figure 8-A is a front view of the clutch on the tool holder side. 8-B is a front view of the same, FIG. 9 is a hydraulic circuit diagram of the tool post of the present invention, and FIG. 10 is an operation flowchart of the tool post of the present invention. In the figure, 4...turret support base, 5...
... Drum type turret head, 7 ... Rotating center axis, 9 ... Indexing motor, 14 ...
・Tool holder, 15... Pivot, 16... Concave register, 17
...Outer diameter cutting tool, 19...Work odor installation hole, 2
0...Internal cutting tool, 39...Positioning pin, 40A, 40B. ...Positioning hole. Figure 4 Figure 6 Boat map N Team Figure 5 Little brother wa map-A Porridge map-B Figure 8-A Figure 8-B Plan? illustrator o diagram

Claims (1)

[Scope of Claims] 1. A turret support stand mounted on a sliding stand movable in directions parallel and perpendicular to the spindle axis relative to the headstock spindle, and a turret support stand mounted on the turret support stand for rotation and indexing. a power drive for pivotally indexing the turret head; a power drive for pivotally indexing the turret head; a tool for external cutting and an internal cutting tool pivotally indexable on each side of the turret head; When using a tool holder that can selectively hold a tool, and one tool held in the tool holder of the turret head provided at the center of rotation of the turret head and indexed to the cutting position, one of the tools is used. The tool holder is pivoted to a position where the cutting edge of the tool matches the center height of the workpiece and the other tool does not interfere with the workpiece, and when the other tool is used, a pivoting device for pivoting the tool holder to a position where the cutting edge matches the center height of the workpiece and one tool does not interfere with the workpiece; and a pivoting device for pivoting the tool holder to the turret head at the pivoted position. A tool rest for a turning machine tool, comprising a positioning device provided on a joint surface between a tool holder and a turret head for positioning, and a clamp device for clamping the tool holder so as to press it against a mounting surface of a turret. 2. The tool post for a turning machine tool according to claim 1, wherein a separate outer diameter cutting tool is attached in place of the inner diameter cutting tool.