JP2011073125A - Turret device of machine tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a turret device of a machine tool reducing abrasion by mutual rubbing between a turret and a turret support base when rotating the turret by a simple adjustment in assembling. <P>SOLUTION: The turret 1 is rotatably supported by a fixed turret support shaft 3 arranged on the turret support base 2 via a bearing 4 capable of a preload. A first annular dentition 11 is arranged in the turret 1, a second annular dentition 12 is arranged on the turret support base 2 and a third annular dentition 13 is arranged in an advancing-retreating member 6, respectively. The advancing-retreating member 6 is moved in the clamp direction by a clamp driving source 15, and in a state of meshing the third annular dentition 13 with the first and second annular dentition 11 and 12, a contact support surface 36 for receiving pressure in the axial direction of the turret 1 by contacting with the turret 1, is arranged on the turret support base 2. A screw part 40 is formed on a peripheral surface of the turret support shaft 3, and a preload applying ring 41 is arranged for applying the preload to the bearing 4 by threadedly engaging with this screw part 40. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a turret device for a machine tool such as a turret lathe.

  As a turret device provided in a machine tool such as a turret lathe, the turret is rotatably installed with respect to the turret support, and the turret support and the turret are respectively moved in the axial direction to the concentric annular teeth. By engaging the annular dentition provided on the member, the turret can be rotated with respect to the turret support base, and the turret can be rotated with respect to the turret support base by releasing the above engagement. (For example, Patent Document 1).

  In this type of turret device, when the turret is clamped at the time of processing or the like, in order to maintain rigidity, the rear surface of the turret comes into contact with a contact support surface provided on the front side of the turret support base, and the turret support base is It is supported by receiving axial pressure. In the unclamped state, the advancing / retreating member moves to the side away from the turret support than in the clamped state, and the contact between the rear surface of the turret and the contact support surface of the turret support is weakened. You can rotate. However, since the rear surface of the turret and the contact support surface of the turret support base are not completely separated, there has been a problem that both surfaces are rubbed and worn when the turret is rotated.

  As a countermeasure for the above problem, a turret is rotatably supported on a fixed turret support shaft provided on a turret support base via a preloadable bearing, and a fixed-side raceway of the inner and outer raceways in the bearing, for example, By giving the inner ring a preload in the direction in which the advancing and retracting member moves in the clamped state, when the unclamped state is reached, the turret is pushed away from the turret support base via the rolling elements and the outer ring by the preload, The rear surface of the turret is separated from the contact support surface of the turret support.

  The magnitude of the preload of the bearing varies greatly depending on a slight difference in the axial position of the fixed-side raceway. Therefore, in order to obtain the optimum preload, it is necessary to adjust the axial position of the fixed-side raceway for each machine. Traditionally, this adjustment has been performed using shims during assembly of the machine.

JP 2000-93201 A

  However, since the adjustment using the shim is performed by adjusting the thickness while cutting the shim, it takes time and the assembly efficiency is poor.

An object of the present invention is to provide a turret device for a machine tool that can reduce wear caused by friction between a turret and a turret support during rotation of the turret by simple adjustment during assembly.
Another object of the present invention is to make it easier to adjust the preload.
Still another object of the present invention is to make it difficult to loosen the preload-applying ring for adjusting the preload so that the preload can be kept constant.

  The turret device for a machine tool according to the present invention supports a turret rotatably on a fixed turret support shaft provided on a turret support base via a preloadable bearing. And a second annular tooth row concentric with the first annular tooth row and facing in the same direction is provided on the turret support. Both the first and second teeth A third annular tooth row that can mesh with the annular tooth row is provided on an advance / retreat member that is movable forward and backward in the axial direction with respect to the turret support shaft, and a clamp drive source that advances and retracts the advance / retreat member is provided. A contact support surface that receives the axial pressure of the turret by contacting the turret in a state where the advancing and retreating member is moved in the clamping direction and the third annular tooth row is engaged with the first and second annular tooth rows. Turret It provided lifting table, to form the threaded portion on the circumferential surface of the turret support shaft, provided with a preloading ring to give a preload to the bearing screwed into the screw portion.

  According to this configuration, the advancing / retracting member is moved in the clamping direction by the clamp driving source, and the third annular tooth row of the advancing / retreating member is changed to the first annular tooth row of the turret and the second annular tooth row of the turret support base. By engaging, the turret is in a clamped state in which it is fixed to the turret support so as not to rotate. The turret is moved relative to the turret support by moving the advancing and retracting member in the direction opposite to the clamping direction to release the engagement between the third annular tooth row, the first annular tooth row, and the second annular tooth row. Rotating unclamped state. In the clamped state, the turret comes into contact with the contact support surface of the turret support, and the turret support receives and supports the axial pressure of the turret.

  By applying a preload in the direction in which the advancing / retreating member moves in the clamped state to the fixed-side raceway of the bearing inner and outer races in the bearing by the preload imparting ring, the rolling element is moved by the preload when the unclamped state is reached. The turret can be pushed away from the contact support surface of the turret support by pushing the turret away from the turret support via the rotating raceway. Accordingly, when the turret is rotated in the unclamped state, it is possible to prevent the turret from coming into contact with the contact support surface of the turret support base. Since the preloading ring is screwed into the threaded part formed on the peripheral surface of the turret support shaft to apply preload to the bearing, the preload can be adjusted simply by rotating the preloading ring around the turret support shaft. can do.

In addition, it is good also as a structure which makes the back surface of a turret contact the contact support surface which faces the front side of a turret support stand, and receives the axial direction pressure of a turret with a turret support stand. Alternatively, the thread portion of the turret support shaft may be a male thread portion formed on the outer periphery of the turret support shaft, and a preload imparting ring may be screwed onto the male thread portion. If it is set as these structures, each member of a turret apparatus can be made into a comparatively simple and simple shape, and each member can be functionally arrange | positioned.
In the case of the above configuration, the present invention can be rephrased as follows. That is, the turret device for a machine tool according to the present invention rotatably supports a turret on a fixed turret support shaft provided on a turret support base via a preloadable bearing, and a turret front side on the rear surface of the turret. And a first annular tooth row in which teeth are arranged around the center of rotation, and a second annular tooth row concentric with the first annular tooth row and facing in the same direction is provided on the turret support. And a third annular tooth row that can mesh with both of the second annular tooth rows is provided in an advance / retreat member that is movable forward and backward in the axial direction with respect to the turret support shaft, and a clamp drive source for moving the advance / retreat member forward and backward is provided. With this clamp drive source, the advancing / retracting member is advanced to the turret back surface side, and the third annular tooth row is engaged with the first and second annular tooth rows to contact the back surface of the turret and Axial direction The provided contact support surface on the turret support base for receiving, forming a male thread portion on the outer periphery of the turret support shaft, is provided with a preloading ring to give a preload to the bearing screwed to the male screw portion.

  In this invention, the preload applying ring applies a preload to the bearing by contacting the inner ring of the bearing and pressing the inner ring in a direction away from the contact support surface (that is, a direction opposite to the clamping direction). Good thing.

  The turret is supported on the turret support shaft via a bearing. The preload imparting ring is screwed into a threaded portion formed on the peripheral surface of the turret support shaft. For this reason, if the preload applying ring is configured to apply the preload to the bearing by pressing the inner ring of the bearing away from the contact support surface, the axial acting force of the preload applying ring can be smoothly transmitted to the inner ring of the bearing. And a simple configuration.

  In this invention, a circumferential groove is provided on a circumferential surface of the preload imparting ring facing the turret support shaft, and the preload imparting ring is divided into a bearing side portion and an anti-bearing side portion that are connected by a bottom wall of the circumferential groove. In addition, at a plurality of locations in the circumferential direction of the preloading ring, a bolt insertion hole is provided in the anti-bearing side portion, and a female screw hole that is aligned with the bolt insertion hole is provided in the bearing side portion. A plurality of locking bolts that are inserted into the female screw holes and screwed into the female screw holes may be provided.

  By providing a circumferential groove on the circumferential surface facing the turret support shaft of the preloading ring and dividing the preloading ring into a bearing side part and an anti-bearing side part connected by the bottom wall of the circumferential groove, the preloading ring However, it is easy to bend in the part with a circumferential groove. Therefore, the locking bolt is inserted into the bolt insertion hole on the anti-bearing side, and the locking bolt is inserted into the female screw hole on the bearing side with the head of the locking bolt in contact with the end surface of the anti-bearing side. By screwing, the preload imparting ring bends at a portion where there is a circumferential groove, and the axial distance between the bearing side portion and the non-bearing side portion is shortened. In other words, the distance between the bearing-side portion and the non-bearing-side portion of the female thread portion provided on the inner periphery of the preload imparting ring changes. As a result, the thread of the female thread part of the preload imparting ring is partially pressed against the thread of the male thread part of the turret support shaft, so that the preload imparting ring is less likely to loosen against the male thread part, and the preload can be maintained constant. .

  The turret device for a machine tool according to the present invention supports a turret rotatably on a fixed turret support shaft provided on a turret support base via a preloadable bearing. And a second annular tooth row concentric with the first annular tooth row and facing in the same direction is provided on the turret support. Both the first and second teeth A third annular tooth row that can mesh with the annular tooth row is provided on an advance / retreat member that is movable forward and backward in the axial direction with respect to the turret support shaft, and a clamp drive source for moving the advance / retreat member forward and backward is provided. A contact support surface that receives the axial pressure of the turret by contacting the turret in a state where the advancing and retreating member is moved in the clamping direction and the third annular tooth row is engaged with the first and second annular tooth rows. Turret A screw part is formed on the peripheral surface of the turret support shaft, and a preload-applying ring is provided to preload the bearing by preloading the screw part. Wear due to friction between the turret and the turret support during rotation can be reduced.

  In the case where the preload-applying ring applies preload to the bearing by contacting the inner ring of the bearing and pressing the inner ring in a direction away from the contact support surface, the preload adjustment is further simplified. Can do.

  The preload application ring is divided into a bearing side portion and a non-bearing side portion, each of which is provided with a circumferential groove on a circumferential surface facing the turret support shaft, and the preload application ring is connected to the bottom wall of the circumferential groove. At a plurality of locations in the circumferential direction of the applying ring, a bolt insertion hole is provided on the side opposite to the bearing, and a female screw hole that is aligned with the bolt insertion hole is provided on the bearing side, and is inserted into each bolt insertion hole. When a plurality of locking bolts to be screwed into the female screw holes are provided, the preloading ring is difficult to loosen, and the preload can be kept constant.

It is sectional drawing of the turret apparatus of the machine tool concerning one Embodiment of this invention. (A) is the elements on larger scale of the turret apparatus, (B) is a figure which shows the different state of the same part. It is the III section enlarged view of FIG. It is sectional drawing of a preload provision ring. (A) is a figure which shows the state of a bearing when the turret apparatus is in a clamped state, (B) is a figure which shows the state of a bearing when it is in an unclamped state.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of the turret device. In this figure, for the sake of simplicity, what is regarded as an integral part even though it is actually composed of a plurality of parts is shown as one part. This turret device is used as a tool post for a turret lathe, for example. The turret device includes a turret 1 on which a plurality of tools (not shown) are mounted on an outer peripheral surface, and the turret 1 is rotatably supported by a turret support base 2. Specifically, a hollow turret support shaft 3 that protrudes toward the turret front side is fixed to the turret support base 2, and the turret 1 is rotatable on the outer periphery of the turret support shaft 3 via a pair of bearings 4 and 5. Supported by

  The turret 1 is switched by the clamp mechanism 10 between a clamp state in which the rotation of the turret support base 2 is restricted and an unclamped state in which the turret support base 2 can rotate. FIG. 1 shows a clamped state of the turret.

  As shown in FIG. 2 in an enlarged manner, the clamping mechanism 10 includes a first annular tooth row 11 provided on the turret 1, a second annular tooth row 12 provided on the turret support 2, a turret 1 and And a third annular tooth row 13 provided on an annular advance / retreat member 6 that can advance and retract in the axial direction with respect to the turret support 2. The first annular tooth row 11 is formed on a first tooth row forming member 7 fixed to the back surface portion of the turret 1, and teeth are arranged around the rotation center O (FIG. 1) facing the front side of the turret. Yes. The second annular tooth row 12 is formed on the second tooth row forming member 8 fixed to the front portion of the turret support 2, and teeth that are concentric with the first annular tooth row 11 and face in the same direction are arranged. It is out. The third annular tooth row 13 is formed on the back surface of the advance / retreat member 6 and can be engaged with both the first and second annular tooth rows 11 and 12. The cross-sectional shape in the circumferential direction of the teeth of each annular tooth row 11, 12, 13 is, for example, a trapezoidal shape.

  The advance / retreat member 6 is advanced and retracted by a clamp drive source 15. In the case of this example, the clamp drive source 15 is a fluid pressure cylinder such as a hydraulic pressure using the advance / retreat member 6 as a piston. The inner peripheral surface of the advance / retreat member 6 has a stepped cylindrical shape, and a clamp side cylinder chamber 16 and an unclamp side cylinder chamber 17 are provided between the inner peripheral surface of the advance / retreat member 6 and the outer peripheral surface of the turret support shaft 3. Is formed. These cylinder chambers 16 and 17 communicate with fluid passages 18 and 19, respectively. Except for the locations of the cylinder chambers 16 and 17, the inner peripheral surface of the advance / retreat member 6 and the outer peripheral surface of the turret support shaft 3 are slidably contacted in the axial direction, and the seal members 20, 21, 22 are interposed at the contact locations. It is.

  When fluid flows into the clamp-side cylinder chamber 16 from the fluid path 18, the advance / retreat member 6 moves forward to the turret back side, and the third annular tooth row 13 becomes the first annular tooth row 11 and the second annular tooth row 12. Mesh with. Thereby, the first tooth row forming member 7 in which the first annular tooth row 11 is formed and the second tooth row forming member 8 in which the second annular tooth row 12 is formed are the third ring shape. They are coupled to each other via the advancing / retracting member 6 on which the tooth row 13 is formed, and the rotation of the turret 1 relative to the turret support 2 is restricted. That is, the clamped state shown in FIG.

  When the fluid flows from the fluid path 19 into the unclamping cylinder chamber 17 from the clamped state, the advance / retreat member 6 moves backward to the turret front side, and the third annular tooth row 13, the first annular tooth row 11 and the second annular tooth row 11. Is disengaged from the annular tooth row 12. Thereby, the coupling between the first dentition forming member 7 and the second dentition forming member 8 is released, and the turret 1 can be rotated with respect to the turret support 2. That is, the unclamped state shown in FIG.

  In FIG. 1, the turret support 2 is provided with a turret indexing mechanism 25 for indexing a target tool to a predetermined index position by rotating the turret 1 around the rotation center O while the turret 1 is unclamped. It has been. The turret indexing mechanism 25 includes an axial turret drive shaft 26 rotatably provided at a position eccentric from the rotation center O of the turret support 2 and a turret rotation motor (not shown) that rotates the turret drive shaft 26. The pinion gear 27 attached to the end of the turret drive shaft 26 on the front side of the turret is meshed with an external gear 28 provided on the turret 1. When the turret drive shaft 26 is rotated by the drive motor, the rotation is transmitted to the turret 1 through the gears 27 and 28, and the turret 1 rotates. The external gear 28 is fixed to the turret 1 together with the first tooth row forming member 7 by a fixture (not shown).

  Of the tools installed on the turret 1, a rotating tool (not shown) is rotated by the tool rotating mechanism 30. The tool rotation mechanism 30 is provided through the turret support shaft 3 and is rotatably supported by a pair of bearings 31. The tool rotation mechanism 30 is provided orthogonal to the tool drive shaft 32. A drive shaft 33 to be supported, a transmission mechanism 34 that transmits and connects the tool drive shaft 32 and the drive shaft 33, a tool rotation motor (not shown) that rotates the tool drive shaft 31, and the like are configured. The transmission mechanism 34 includes a pair of bevel gears 34a and 34b, for example.

  On the surface of the turret support 2 on the front side of the turret, a contact support surface 36 that contacts the back surface 35 of the turret 1 in a clamped state and receives the axial pressure of the turret 1 is provided. In this example, the contact support surface 36 is a surface with which the back surface of the first dentition forming member 7, which is a part of the turret 1, is in contact with the back surface of the external gear 28. Alternatively, it may be a surface that contacts the back surface of the turret 1 other than the above.

  Of the bearings 4 and 5 that support the turret 1, at least the bearing 4 that supports the front-side collar 1 a of the turret 1 is a preloadable rolling bearing. In this example, it is a deep groove ball bearing, but it may be an angular ball bearing. A preload is applied to the preloadable bearing 4 by a preload applying mechanism 37. The preload applying mechanism 37 is shown in an enlarged manner in FIG.

As shown in FIG. 3, the outer ring 4 a of the bearing 4 is positioned by being sandwiched from both sides in the axial direction by a step surface 1 aa formed on the inner periphery of the front side collar 1 a of the turret 1 and the outer ring positioning member 38. . The outer ring positioning member 38 is fixed to the front-side collar portion 1a by a bolt 39.
On the other hand, the axial position of the inner ring 4 b of the bearing 4 is restrained by an annular preloading ring 41 (FIG. 4) that is screwed into a male screw portion 40 formed on the outer periphery of the turret support shaft 3. The preload imparting ring 41 is screwed to the male screw portion 40 by a female screw portion 42 formed on the inner periphery. The preload imparting ring 41 is obtained by integrating two divided bodies 41a and 41b arranged in the axial direction, and an inner ring 4b is fitted to the outer periphery of one divided body 41a. One of the divided bodies 41a has a flange portion 41aa protruding outward, and the other divided body 41b has an annular protrusion 41ba protruding from the outer diameter end toward the flange portion 41aa. The protrusion 41ba sandwiches the inner ring 4a of the bearing 4 from both sides in the axial direction.

A preload can be applied to the bearing 4 by adjusting the screwing position of the preload applying ring 41 with respect to the male thread portion 40 and shifting the axial position of the inner ring 4b with respect to the outer ring 4a. In addition, the magnitude of the preload can be changed by changing the shift amount. In this embodiment, the bearing 4 is preloaded by pressing the inner ring 4b toward the front side of the turret at the end face of the split body 41b of the preload imparting ring 41.
Alternatively, the inner ring 4 b may be directly fitted to the outer periphery of the turret support shaft 3 and the inner ring 4 b of the bearing 4 may be pressed by the preload applying ring 41.

  As shown in FIG. 4, the preload imparting ring 41 of this embodiment is provided with a circumferential groove 43 on the inner periphery, and a bearing side portion 44 and an anti-bearing side portion 45 that are connected by the bottom wall of the circumferential groove 43. It is divided into and. Therefore, the female thread portion 42 is also divided into a bearing side portion 42a and an anti-bearing side portion 42b. In addition, bolt insertion holes 46 penetrating in the axial direction are provided in the anti-bearing side portion 45 at a plurality of locations in the circumferential direction, and female screw holes 47 aligned with the bolt insertion holes 46 are provided in the bearing side portion 43.

By providing the circumferential groove 43 on the inner periphery of the preload imparting ring 41, the preload imparting ring 41 is easily bent at a position where the circumferential groove 43 is present. Therefore, as shown in FIG. 3, the locking bolt 48 is inserted into the bolt insertion hole 46, and the locking bolt 48 is inserted into the female screw in a state where the head of the locking bolt 48 is in contact with the end surface of the non-bearing side portion 45. By screwing into the hole 47, the preload imparting ring 41 bends at a location where the circumferential groove 43 is present, and the axial distance between the bearing side portion 44 and the non-bearing side portion 45 is shortened. That is, the distance between the bearing-side portion 42a and the non-bearing-side portion 42b of the female screw portion 42 changes and functions as a double nut. As a result, since the thread of the female thread portion 42 of the preload imparting ring 41 is partially pressed against the thread of the male thread portion 40 of the turret support shaft 3, the preload imparting ring 41 is less likely to loosen against the male thread portion 40, Preload can be kept constant.
As in the above configuration, the female thread portion 42 of the preload imparting ring 41 is not divided into the bearing side portion 42a and the non-bearing side portion 42b whose axial distance can be changed. A similar locking effect can also be obtained by providing a body lock nut (not shown) overlapping the preloading ring 41 and screwing the lock nut into the male threaded portion 40 of the turret support shaft 3.

  A front cover 50 that covers the front surfaces of the bearing 4, the outer ring positioning member 38, and the preload imparting ring 41 is attached to the front side collar 1 a of the turret 1 by bolts 51. A support shaft cover 52 is attached to the front surface of the turret support shaft 3.

  In this turret device, the turret 1 is clamped, and the preload applying mechanism 37 applies a preload in the direction indicated by the arrow in FIG. 5A to the inner ring 4 b of the bearing 4. The direction of this preload is the direction in which the advance / retreat member 6 moves in the clamped state, that is, the direction in which the advance / retreat member 6 moves when switching from the clamped state to the unclamped state. The adjustment of the preload by the preload applying mechanism 37 can be easily performed by simply rotating the preload applying ring 41 around the turret support shaft 3. Further, the preload can be kept constant by screwing the locking bolt 48 into the female screw hole 47.

  By applying preload to the bearing 4 in this way, when the unclamped state is reached, the turret 1 is pushed away from the turret support 2 via the rolling elements 4c and the outer ring 4a of the bearing 4 by the preload, The rear surface 35 of the turret 1 is separated from the contact support surface 36 of the turret support 2. Thereby, when rotating the turret 1 in an unclamped state, it is possible to prevent the rear surface 35 of the turret 1 and the contact support surface 36 of the turret support base 2 from coming into contact with each other and wearing away.

  In the unclamped state, as shown in FIG. 5B, the bearing 4 is stable in a neutral state in which the axial positions of the outer ring 4a and the inner ring 4b are aligned and the rolling element 4c is located at the center of the raceway surface. Therefore, the turret 1 is rotatable with respect to the turret support 2 and the turret support shaft 3. The separation distance between the back surface 35 of the turret 1 and the contact support surface 36 of the turret support 2 in the unclamped state is very small, and the turret 1 does not jump out to the front side so that it can be easily seen. Therefore, the turret 1 does not become unstable.

  In summary, this turret device is provided with the preload imparting mechanism 37, so that the wear of the back surface 35 of the turret 1 and the contact support surface 36 of the turret support base 2 during rotation of the turret 1 can be reduced, and Since the preload adjustment of the bearing 4 by the preload applying mechanism 37 is easy, the assembly work can be performed efficiently. Further, when the front cover 50 of the turret 1 is removed, the preload imparting ring 41 and the locking bolt 48 are exposed to the outside, so that the preload adjustment of the bearing 4 can be easily performed even after the assembly of the machine.

  In this embodiment, since the preload is applied to the inner ring 4 a of the bearing 4, the axial acting force of the preload imparting ring 41 that engages with the male screw portion 40 formed on the outer periphery of the turret support shaft 3 is applied to the inner ring 4 a. It can transmit smoothly and can be set as a simple structure. Further, a preload may be applied to the outer ring 4b of the bearing 4.

  In this embodiment, the rear surface 35 of the turret 1 is in contact with the contact support surface 36 facing the front surface side of the turret support 2, so that the turret support 2 receives the contact support pressure of the turret 1. On the contrary, the front surface of the turret 1 may contact the contact support surface facing the back side of the turret support 2 so that the turret support 2 receives the contact support pressure of the turret 1.

  Furthermore, in this embodiment, a male thread portion 40 is formed on the outer periphery of the turret support rod 3 and a preload imparting ring 41 is screwed to the male thread portion 40, but a female thread portion is formed on the inner periphery of the turret support rod 3. And you may screw the preload provision ring 41 in this internal thread part.

DESCRIPTION OF SYMBOLS 1 ... Turret 2 ... Turret support stand 3 ... Turret support shaft 4 ... Bearing 6 ... Advance / retreat member 7 ... 1st tooth row formation member 8 ... 2nd tooth row formation member 10 ... Clamp mechanism 11 ... 1st annular tooth row DESCRIPTION OF SYMBOLS 12 ... 2nd annular tooth row 13 ... 3rd annular tooth row 15 ... Clamp drive source 35 ... Back surface 36 of a turret ... Contact support surface 37 ... Preload imparting mechanism 40 ... Male thread part 41 ... Preload imparting ring 43 ... Circumferential groove 44 ... bearing side 45 ... anti-bearing side 46 ... bolt insertion hole 47 ... female screw hole 48 ... locking bolt

Claims (3)

  A turret is rotatably supported on a fixed turret support shaft provided on the turret support base via a preloadable bearing, and a first annular tooth row in which teeth are oriented in the axial direction and around the rotation center. And a second annular tooth row concentric with the first annular tooth row and facing in the same direction is provided on the turret support, and a third ring tooth that can mesh with both the first and second annular tooth rows is provided. An annular tooth row is provided on an advance / retreat member that is movable forward and backward in the axial direction with respect to the turret support shaft, a clamp drive source for moving the advance / retreat member is provided, and the advance / retreat member is moved in the clamp direction by the clamp drive source. A contact support surface that contacts the turret and receives axial pressure of the turret in a state where a third annular tooth row is engaged with the first and second annular tooth rows is provided on the turret support, and the turret support is provided. Axis circumference To form the threaded portion, the machine tool of the turret device provided with preloading ring screwed on the threaded portion to give a preload to the bearing.   2. The turret device for a machine tool according to claim 1, wherein the preload applying ring is configured to apply a preload to the bearing by contacting the inner ring of the bearing and pressing the inner ring in a direction away from the contact support surface.   The preload application ring is divided into a bearing side portion and a non-bearing side portion, each of which is provided with a circumferential groove on a circumferential surface facing the turret support shaft, and the preload application ring is connected to the bottom wall of the circumferential groove. At a plurality of locations in the circumferential direction of the applying ring, a bolt insertion hole is provided on the side opposite to the bearing, and a female screw hole that is aligned with the bolt insertion hole is provided on the bearing side, and is inserted into each bolt insertion hole. The turret device for a machine tool according to claim 1 or 2, further comprising a plurality of locking bolts screwed into the female screw holes.

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