Machine tool and control method for machine tool

Abstract

To provide a machine tool configured so that an aperture of a rotary guide bush is automatically adjusted with an adjustment nut and the rotary guide bush rotates in synchronization with a spindle, in which a gap between the rotary guide bush and a bar material is automatically adjusted, and a control method of a machine tool.SOLUTION: A control device has a guide bush aperture determining part that determines an adjustment amount of a gap, on the basis of a rotation angle of a rotary guide bush driving motor at the time when a spindle holds a bar material and the spindle is rotated in a state where the rotary guide bush driving motor is not excited or on the basis of a rotation angle of a spindle driving motor at the time when the rotary guide bush holds the bar material and a guide bush body of the rotary guide bush is rotated in a state where the spindle driving motor is not excited.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a machine tool for adjusting the gap between a bar and a rotary guide bush, and a control method for the machine tool.

Background Art

[0002] Conventionally, there has been known a machine tool provided with a guide bush that is disposed in front of a spindle and supports and guides a bar held by the spindle. In order to stably and accurately machine a bar, it is necessary to adjust the size of the gap between the bar and the guide bush (also referred to as the opening adjustment of the guide bush), and a technique for automatically performing the opening adjustment of the guide bush is known (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003] [

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the machine tool described in Patent Document 1, when adjusting the opening of the guide bush, an adjustment nut (also referred to as a drawbar) that is screwed into the guide bush is used. Here, although the guide bush in Patent Document 1 does not rotate synchronously with the spindle, in addition to avoiding seizure of the bar on the guide bush, in the case of a rotary guide bush that rotates the guide bush synchronously with the spindle in order to avoid deterioration of the surface properties of the bar, it is desirable to automatically adjust the gap between the rotary guide bush and the bar in order to stably and accurately machine the bar.

[0005] Therefore, the present invention solves the problems of the prior art described above, and that is, the object of the present invention is to provide a machine tool and a control method for the machine tool that automatically adjust the gap between the rotary guide bush and the rod when the opening of the rotary guide bush is adjusted by an adjustment nut and the rotary guide bush rotates synchronously with the spindle. [Means for solving the problem]

[0006] The invention according to claim 1 is a machine tool comprising: a spindle that rotatably holds a rod; a spindle drive motor that rotationally drives the spindle; a rotary guide bush that allows and supports the rotation of the rod extending from the spindle around its axis of rotation and movement in the direction of the axis of rotation, and rotates synchronously with the spindle; a rotary guide bush drive motor that drives the rotary guide bush; an encoder that detects the rotation angle of the rotary guide bush drive motor or the spindle drive motor; and a control device that controls the operation of the spindle and the rotary guide bush, wherein the rotary guide bush includes a guide bush holder fixed to a guide bush support base, and allows the rod to rotate around its axis of rotation and movement in the direction of rotation while being rotatable relative to the guide bush holder. The aforementioned problems are solved by having a guide bush opening determination unit that determines the amount of adjustment of the gap based on the rotation angle of the rotary guide bush drive motor when the spindle is rotated with the rod material being held by the spindle and the spindle drive motor is not energized, or based on the rotation angle of the spindle drive motor when the guide bush body of the rotary guide bush is rotated with the rod material being held by the rotary guide bush and the spindle drive motor is not energized.

[0007] The invention according to claim 2 solves the aforementioned problems by, in addition to the configuration of the machine tool described in claim 1, having the encoder detect the rotation angle of the rotary guide bush drive motor, and having the guide bush opening determination unit determine the amount of adjustment of the gap based on the rotation angle of the rotary guide bush drive motor.

[0008] The invention according to claim 3 further solves the aforementioned problems by adding, in addition to the configuration of the machine tool described in claim 1 or claim 2, a rotating jig that engages with the adjustment nut of the rotary guide bush and rotates the adjustment nut is attached to the rod material.

[0009] The invention according to claim 4 comprises a spindle that rotatably holds a rod, a spindle drive motor that rotationally drives the spindle, a rotary guide bush that allows and supports the rod extending from the spindle to rotate around its axis of rotation and move in the direction of the axis of rotation, and rotates synchronously with the spindle, a rotary guide bush drive motor that drives the rotary guide bush, an encoder that detects the rotation angle of the rotary guide bush drive motor, and a control device that controls the operation of the spindle and the rotary guide bush, wherein the rotary guide bush comprises a guide bush holder fixed to a guide bush support base, a guide bush body that is rotatable relative to the guide bush holder and allows and supports the rod to rotate around its axis of rotation and move in the direction of the axis of rotation, and the rod and the guide bush A control method for a machine tool having an adjustment nut that is screwed onto the guide bush body and rotates the guide bush body to adjust the size of the gap when adjusting the gap with the bush body, the method includes the steps of: holding the rod material with the spindle; rotating the spindle around the axis of rotation; measuring the rotation angle of the rotary guide bush drive motor in an unexcited state resulting from the rotation of the spindle with the encoder; determining the amount of gap adjustment based on the rotation angle of the rotary guide bush drive motor measured by the encoder; and rotating the spindle around the axis of rotation to rotate the guide bush body relative to the adjustment nut so that the gap adjustment amount is determined. This method solves the aforementioned problems.

[0010] The invention according to claim 5 comprises a spindle that rotatably holds a rod, a spindle drive motor that rotationally drives the spindle, a rotary guide bush that allows and supports the rod extending from the spindle to rotate around its axis of rotation and move in the direction of the axis of rotation, and rotates synchronously with the spindle, a rotary guide bush drive motor that drives the rotary guide bush, an encoder that detects the rotation angle of the spindle drive motor, and a control device that controls the operation of the spindle and the rotary guide bush, wherein the rotary guide bush comprises a guide bush holder fixed to a guide bush support base, a guide bush body that is rotatable relative to the guide bush holder and allows and supports the rod to rotate around its axis of rotation and move in the direction of the axis of rotation, and the rod and the guide bush body A control method for a machine tool having an adjustment nut that screws onto the guide bush body and adjusts the size of the gap when adjusting the gap between the bar and the spindle, the method includes the steps of: holding the bar with the spindle; rotating the guide bush body around a rotation axis; measuring the rotation angle of the spindle drive motor in an unexcited state, which is generated by rotating the guide bush body, using the encoder; determining the amount of gap adjustment based on the rotation angle of the spindle drive motor measured by the encoder; and rotating the guide bush body around a rotation axis to rotate the guide bush body relative to the adjustment nut so that the determined amount of gap adjustment is achieved, thereby solving the aforementioned problems. [Effects of the Invention]

[0011] According to the machine tool of the invention described in claim 1, the control device has a guide bush opening determination unit that determines the amount of gap adjustment based on the rotation angle of the rotary guide bush drive motor when the spindle is rotated with the rod material held by the spindle and the rotary guide bush drive motor is not energized, or based on the rotation angle of the spindle drive motor when the guide bush body of the rotary guide bush is rotated with the rod material held by the rotary guide bush and the spindle drive motor is not energized, thereby enabling rotation of either the spindle drive motor or the rotary guide bush drive motor, which is rotatable. Because the variation in the rotation angle of the drive motor or the rotary guide bush drive motor is based solely on the rotation of the rod accompanying the rotation of either the spindle drive motor or the rotary guide bush drive motor, the signal-to-noise ratio is higher compared to the case where the size of the gap between the rotary guide bush and the rod is adjusted based on the load of the spindle drive motor when the spindle holding the rod is rotated by the spindle drive motor. In a structure where the opening of the rotary guide bush is adjusted by an adjustment nut and the rotary guide bush rotates synchronously with the spindle, the gap between the rotary guide bush and the rod can be automatically adjusted with high precision.

[0012] According to the machine tool of the invention of claim 2, in addition to the effects of the machine tool of the invention of claim 1, the encoder detects the rotation angle of the rotary guide bush drive motor, and the guide bush opening determination unit determines the amount of gap adjustment based on the rotation angle of the rotary guide bush drive motor. Therefore, since the amount of gap adjustment is determined using the rotation angle of the guide bush body, which has a smaller moment of inertia than the moment of inertia of the spindle, the amount of gap adjustment can be determined with greater accuracy compared to the case where the amount of gap adjustment is determined based on the rotation angle of the spindle drive motor.

[0013] According to the machine tool of the invention of claim 3, in addition to the effects of the machine tool of the invention of claim 1 or claim 2, a rotating jig that engages with the adjustment nut of the rotary guide bush and rotates the adjustment nut is attached to the rod. As the rod is rotated while the rotating jig is engaged with the adjustment nut, the adjustment nut of the rotary guide bush rotates, allowing the gap between the rotary guide bush and the rod to be adjusted automatically and with high precision.

[0014] According to the machine tool control method of the invention of claim 4, the method includes the steps of: holding a bar stock with the spindle; rotating the spindle around the rotation axis; measuring the rotation angle of the rotary guide bush drive motor in an unexcited state, which is generated by rotating the spindle, using an encoder; determining the amount of gap adjustment based on the rotation angle of the rotary guide bush drive motor measured by the encoder; and rotating the spindle around the rotation axis to rotate the guide bush body relative to the adjustment nut so that the determined amount of gap adjustment is achieved. As a result, the fluctuation in the rotation angle of the rotary guide bush drive motor, which is rotatable when the spindle drive motor is driven to rotate, is based solely on the rotation of the bar stock accompanying the rotation of the spindle drive motor. Therefore, the signal-to-noise ratio is higher compared to the case where the size of the gap between the rotary guide bush and the bar stock is adjusted based on the load of the spindle drive motor when the spindle holding the bar stock is driven to rotate by the spindle drive motor. In the case where the opening of the rotary guide bush is adjusted by the adjustment nut and the rotary guide bush rotates synchronously with the spindle, the gap between the rotary guide bush and the bar stock can be automatically adjusted with high precision.

[0015] According to the machine tool control method of the invention of claim 5, the method includes the steps of: holding the rod material with the spindle; rotating the guide bush body around the rotation axis; measuring the rotation angle of the spindle drive motor in an unexcited state, which is generated by rotating the guide bush body, with an encoder; determining the amount of gap adjustment based on the rotation angle of the spindle drive motor measured by the encoder; and rotating the guide bush body around the rotation axis to rotate the guide bush body relative to the adjustment nut so that the determined amount of gap adjustment is achieved. As a result, when the rotary guide bush drive motor is driven to rotate, the fluctuation in the rotation angle of the spindle drive motor, which is rotatable, is based solely on the rotation of the rod material accompanying the rotation of the rotary guide bush drive motor. Therefore, the signal-to-noise ratio is higher compared to the case where the size of the gap between the rotary guide bush and the rod material is adjusted based on the load of the spindle drive motor when the spindle holding the rod material is driven to rotate by the spindle drive motor. In the case where the opening degree of the rotary guide bush is adjusted by the adjustment nut and the rotary guide bush rotates synchronously with the spindle, the gap between the rotary guide bush and the rod material can be automatically adjusted with high precision. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic diagram of an automatic lathe, which is one embodiment of a machine tool according to the present invention. [Figure 2] This is a diagram showing the configuration of the rotary guide bush, front spindle, and rear spindle. [Figure 3] Figure 2 shows a perspective view of the adjustment nut. [Figure 4] Figure 2 is a perspective view of the holding jig shown. [Figure 5] Figure 2 is a perspective view of the rotating jig shown. [Figure 6A] A flowchart showing the procedure for adjusting the gap size between the rod and the rotary guide bush. [Figure 6B] A flowchart showing the preparation steps, as shown in Figure 6A. [Figure 6C] A flowchart showing the gap adjustment process, as shown in Figure 6A. [Figure 7A] Schematic diagram of the state where the bar is inserted through the front spindle. [Figure 7B] Schematic diagram of the state where the bar is inserted up to the rotary guide bush. [Figure 7C] Schematic diagram showing the state where the front spindle is advanced to engage the rotary jig and the adjusting nut. [Figure 8] Schematic diagram showing the state where the engagement between the rotary jig and the adjusting nut is released. [Figure 9] Schematic diagram of the rotary jig and the bar shown in Fig. 8 as seen from the rear. [Figure 10A] Schematic diagram showing the state where the front spindle is advanced to engage the rotary jig and the adjusting nut. [Figure 10B] Schematic diagram for explaining the process of adjusting the gap between the bar and the guide bush body by rotating the front spindle. [Figure 11A] Flowchart showing the procedure for adjusting the size of the gap between the bar and the rotary guide bush. [Figure 11B] Flowchart showing the gap adjustment process shown in Fig. 11A. [Figure 12A] Flowchart showing the procedure for adjusting the size of the gap between the bar and the rotary guide bush. [Figure 12B] Flowchart showing the preparation process shown in Fig. 12A. [Figure 12C] Flowchart showing the gap adjustment process shown in Fig. 12A. [Figure 13A] Schematic diagram of the state where the bar is inserted through the front spindle. [Figure 13B] Schematic diagram of the state where the bar is inserted up to the rear spindle. [Figure 13C] Schematic diagram showing the state where the rear spindle is retracted to engage the rotary jig and the adjusting nut. [Figure 14] Schematic diagram showing the state where the engagement between the rotary jig and the adjusting nut is released. [Figure 15] Schematic diagram of the rotary jig and the bar shown in Fig. 14 as seen from the rear. [Figure 16A] Schematic diagram showing the state where the rear spindle is retracted to engage the rotary jig and the adjusting nut. [Figure 16B] A schematic diagram illustrating the process of adjusting the gap between the rod and the guide bush body by rotating the rear spindle. [Figure 17A] A flowchart showing the procedure for adjusting the gap size between the rod and the rotary guide bush. [Figure 17B] A flowchart showing the gap adjustment process, as shown in Figure 17A. [Figure 18A] A flowchart showing the procedure for adjusting the gap size between the rod and the rotary guide bush. [Figure 18B] A flowchart showing the gap adjustment process, as shown in Figure 18A. [Figure 19] A schematic diagram showing the state in which the engagement between the rotating jig and the adjustment nut has been released. [Figure 20] Figure 19 is a schematic diagram of the rotating jig and rod shown from the rear. [Figure 21A] A schematic diagram showing the rear spindle retracted and engaged with the rotating jig and adjustment nut. [Figure 21B] A schematic diagram illustrating the process of adjusting the size of the gap between the rod and the guide bush body by rotating the front spindle. [Figure 22A] A flowchart showing the procedure for adjusting the gap size between the rod and the rotary guide bush. [Figure 22B] A flowchart showing the preparation steps, as shown in Figure 23A. [Figure 22C] A flowchart showing the gap adjustment process, as shown in Figure 23A. [Figure 23] A schematic diagram showing the state in which the engagement between the rotating jig and the adjustment nut has been released. [Figure 24] Figure 23 is a schematic diagram of the rotating jig and rod shown from the rear. [Figure 25A] A schematic diagram showing the front spindle advanced and engaged with the rotating jig and adjustment nut. [Figure 25B] A schematic diagram illustrating the process of adjusting the gap between the rod and the guide bush body by rotating the rear spindle. [Modes for carrying out the invention]

[0017] The present invention relates to a machine tool comprising: a spindle that rotatably holds a rod; a spindle drive motor that rotationally drives the spindle; a rotary guide bush that allows and supports the rotation of the rod extending from the spindle around its axis of rotation and movement in the direction of the axis of rotation, and rotates synchronously with the spindle; a rotary guide bush drive motor that drives the rotary guide bush; an encoder that detects the rotation angle of the rotary guide bush drive motor or the spindle drive motor; and a control device that controls the operation of the spindle and the rotary guide bush, wherein the rotary guide bush comprises a guide bush holder fixed to a guide bush support base, and a guide bush that is rotatable relative to the guide bush holder and allows and supports the rotation of the rod around its axis of rotation and movement in the direction of the axis of rotation. The rotary guide bush has a main body and an adjustment nut that rotates the guide bush body to adjust the size of the gap between the rod and the guide bush body and screws into the guide bush body, and the control device has a guide bush opening determination unit that determines the amount of gap adjustment based on the rotation angle of the rotary guide bush drive motor when the spindle is rotated with the rod held by the spindle and the spindle drive motor is not energized, or based on the rotation angle of the spindle drive motor when the guide bush body of the rotary guide bush is rotated with the rod held by the rotary guide bush and the spindle drive motor is not energized, and the specific embodiment of the rotary guide bush can be anything as long as it automatically adjusts the gap between the rotary guide bush and the rod.

[0018] Furthermore, any specific embodiment of the above-mentioned machine tool may be any, as long as it includes the steps of: holding the rod material with the spindle; rotating the spindle around the rotation axis; measuring the rotation angle of the unexcited rotary guide bush drive motor, which is generated by rotating the spindle, with an encoder; determining the amount of gap adjustment based on the rotation angle of the rotary guide bush drive motor measured by the encoder; and rotating the spindle around the rotation axis to rotate the guide bush body relative to the adjustment nut so as to achieve the determined amount of gap adjustment, thereby automatically adjusting the gap between the rotary guide bush and the rod material. Alternatively, any specific embodiment of the above-mentioned machine tool may be any, as long as it includes the steps of: holding the rod material with the spindle; rotating the guide bush body around the rotation axis; measuring the rotation angle of the spindle drive motor in an unexcited state, resulting from the rotation of the guide bush body, using an encoder; determining the amount of gap adjustment based on the rotation angle of the spindle drive motor measured by the encoder; and rotating the guide bush body around the rotation axis so as to achieve the determined amount of gap adjustment, thereby rotating the guide bush body relative to the adjustment nut, thereby automatically adjusting the gap between the rotary guide bush and the rod material. [Examples]

[0019] Hereinafter, a machine tool 100, which is an embodiment of the present invention, will be described based on Figures 1 to 25B.

[0020] <1. Overview of Machine Tools> First, an overview of the machine tool 100 will be described based on Figures 1 to 5. Figure 1 is a schematic diagram of an automatic lathe, which is one embodiment of a machine tool according to the present invention.

[0021] The machine tool 100 is an automatic lathe and, as shown in Figure 1, is equipped with a rectangular bed 110 that is mounted on the floor surface F. Hereinafter, the direction perpendicular to the bed 110 will be referred to as the "Y direction," the longitudinal direction of the bed 110 in a plan view will be referred to as the "Z direction," and the short direction of the bed 110 in a plan view will be referred to as the "X direction."

[0022] The bed 110 is equipped with a front spindle 120 that rotatably holds the bar stock W, a front spindle feed mechanism 130 that moves the front spindle 120 in the Z1 direction parallel to the Z direction, a rotary guide bush 140 that allows and supports the rotation of the bar stock W extending from the front spindle 120 around the rotation axis L and movement in the direction of the rotation axis L, a guide bush support base 150 that is installed in front of the front spindle 120 and supports the rotary guide bush 140, a rear spindle 160 that is positioned opposite the front spindle 120 and the rotary guide bush 140 and rotatably holds the bar stock W, and a rear spindle feed mechanism 170 that moves the rear spindle 160 in the Z2 direction parallel to the Z direction and the X2 direction parallel to the X direction.

[0023] Here, the front spindle 120 and the bar stock W are freely movable in the Z1 direction, and "forward" in the context of the front spindle 120 and the bar stock W means the direction in which the front spindle 120 and the bar stock W move toward the rear spindle 160, while "rear" in the context of the front spindle 120 and the bar stock W means the direction in which the front spindle 120 and the bar stock W move toward the rear spindle 160. Furthermore, "forward" in the context of the rotary guide bush 140 means the direction in which the rotary guide bush 140 approaches the rear spindle 160, and "rearward" in the context of the rotary guide bush 140 means the direction in which the rotary guide bush 140 moves away from the rear spindle 160. Furthermore, the rear spindle 160 is freely movable in both the X2 and Z2 directions. "Forward" in the context of the rear spindle 160 means the direction in which the rear spindle 160 approaches the front spindle 120, and "rearward" in the context of the rear spindle 160 means the direction in which the rear spindle 160 moves away from the front spindle 120.

[0024] The bar material W to be machined by the machine tool 100 is a long, round bar-shaped workpiece, which is supplied from the rear end of the front spindle 120 using a pusher of a bar feeder (not shown), and is supported by a rotary guide bush 140 so as to be rotatable around the rotation axis L via the front spindle 120, and is fed toward the rear spindle 160. Furthermore, the tip of the bar feeder's pusher is equipped with a finger chuck that grips the rear end of the bar material W.

[0025] Furthermore, the machine tool 100 is equipped with a control device 180 that controls the operation of the front spindle 120, the rotary guide bush 140, and the rear spindle 160.

[0026] <2. Components of a machine tool> Next, we will explain in detail each component of the machine tool 100 described above, based on Figures 1 to 5. Figure 2 is a diagram showing the configuration of the rotary guide bush, front spindle, and rear spindle; Figure 3 is a perspective view of the adjustment nut shown in Figure 2; Figure 4 is a perspective view of the holding jig shown in Figure 2; and Figure 5 is a perspective view of the rotating jig shown in Figure 2.

[0027] <2.1. Front spindle> As shown in Figure 1, the front spindle 120 includes a headstock 121 mounted on the front spindle feed mechanism 130 and movable in the Z1 direction, a front spindle body 122 rotatably supported on the headstock 121, a front spindle drive motor 123 that rotates the front spindle body 122, and an encoder 124 that detects the rotation angle of the front spindle drive motor 123.

[0028] The front spindle body 122 is supported by the headstock 121 with the Z1 direction shown in Figure 1 as its axis, and as shown in Figure 2, it is capable of gripping (holding) the rod material W rotatably around the rotation axis L via the chuck 122a. The chuck 122a is positioned concentrically with the front spindle body 122 and rotates integrally with the front spindle body 122. In other words, the axis of rotation L of the bar material W coincides with the center of rotation of the front principal spindle 120.

[0029] The front spindle drive motor 123 is a so-called "electric motor" that has a stator and a rotor, and generates a magnetic field when either one rotates, and produces driving force through the change in that magnetic field.

[0030] <2.2. Front spindle feed mechanism> The front spindle feed mechanism 130 includes a Z1 rail 131 fixed to the bed 110 and extending in the Z1 direction, a Z1 slider 132 mounted on the Z1 rail 131 and slidable along the Z1 direction, and a Z1 motor 133 that slides the Z1 slider 132. The headstock 121 of the front spindle 120 is mounted on the Z1 slider 132.

[0031] <2.3. Rotary Guide Bushing> As shown in Figure 1, the rotary guide bush 140 is installed by being inserted into a guide bush support base 150 which has a rotary guide bush insertion hole 150a that is concentric with the front main shaft 120.

[0032] As shown in Figure 2, the rotary guide bush 140 comprises a hollow cylindrical guide bush holder 141 inserted and fixed into the rotary guide bush insertion hole 150a of the guide bush support base 150, a guide bush sleeve 142 fitted inside the guide bush holder 141, a bearing 143 positioned between the guide bush holder 141 and the guide bush sleeve 142 to rotatably support the guide bush sleeve 142 relative to the guide bush holder 141, and a cylindrical guide bush body 144 fitted inside the guide bush sleeve 142. The guide bush body 144 has an adjustment nut 145 that screws into a male thread 144a formed on the rear end portion of the guide bush body 144, a timing pulley 146 that is inserted into the rear end side of the guide bush holder 141 and is rotatable relative to the guide bush holder 141, a retaining nut 147 that engages with the guide bush sleeve 142 to prevent the timing pulley 146 from coming off, a flange 148 that is fixed to the guide bush support base 150 to prevent the timing pulley 146 from coming off, and a rotary guide bush drive motor 149 that rotates the guide bush body 144.

[0033] The guide bush holder 141 includes a hollow cylindrical guide bush holder body 141a that is inserted into the rotary guide bush insertion hole 150a of the guide bush support base 150, and an annular bearing retainer 141b that is attached to the rear end of the guide bush holder body 141a and works together with the guide bush holder body 141a to position the bearing 143 in the front-rear direction.

[0034] The inner circumference of the front end portion of the guide bush sleeve 142 has a taper 142a formed thereon, where the inner diameter gradually decreases towards the rear. Furthermore, the guide bush sleeve 142 has a through-hole 142c formed radially, into which a set screw 142b is screwed. Furthermore, a key 142d that engages with the timing pulley 146 is embedded on the outer circumference of the rear end portion of the guide bush sleeve 142.

[0035] As shown in Figure 2, the guide bush body 144 supports and guides the rod W so as to allow rotation around the rotation axis L and movement in the direction of the rotation axis L. A slot 144b extending in the Z direction is formed at the front end portion of the guide bush body 144.

[0036] Furthermore, a taper 144c is formed on the outer circumference of the front end portion of the guide bush body 144, which gradually decreases in outer diameter towards the rear, corresponding to the taper angle of the taper 142a of the guide bush sleeve 142. A groove 144d extending towards the rear is formed behind this taper 144c. This groove 144d is formed to gradually deepen towards the rear and extends until it reaches the male thread 144a.

[0037] Furthermore, a set screw 142b, which is screwed into the through-thread hole 142c of the guide bush sleeve 142, is inserted into this groove 144d. Therefore, the set screw 142b and the groove 144d engage, allowing the guide bush body 144 to move back and forth only in the Z direction relative to the guide bush sleeve 142, and also allowing the guide bush body 144 to rotate together with the guide bush sleeve 142 around the rotation axis L. In other words, when the set screw 142b and the groove 144d engage, the guide bush body 144 becomes rotatable relative to the guide bush holder 141.

[0038] The adjustment nut 145 (also called a drawbar) is hollow and cylindrical, located behind the guide bush body 144, and is rotatable relative to the guide bush sleeve 142. As shown in Figure 2, a female thread 145a with a predetermined pitch is formed on the inner circumference of the front end portion of the adjustment nut 145, and this female thread 145a is screwed into a male thread 144a formed on the rear end portion of the guide bush body 144.

[0039] Therefore, by rotating the adjustment nut 145 around the rotation axis L, the guide bush body 144 moves forward and backward relative to the guide bush sleeve 142. When the guide bush body 144 retracts relative to the guide bush sleeve 142, the taper 144c is pushed by the taper 142a, and the front end portion of the guide bush body 144 bends toward the rod W side due to the slot 144b, thus reducing the opening of the front end portion of the guide bush body 144. On the other hand, when the guide bush body 144 moves forward relative to the guide bush sleeve 142, the pressure from the taper 142a is released and the front end portion of the guide bush body 144 expands outward, thus increasing the degree of opening of the front end portion of the guide bush body 144.

[0040] In other words, the amount of displacement of the guide bush body 144 in this embodiment (the same as the opening degree of the rotary guide bush 140 and the opening degree of the front end portion of the guide bush body 144) is determined by the amount of rotation relative to the adjustment nut 145. In other words, the adjustment nut 145 allows you to adjust the size of the gap between the rod W and the guide bush body 144 by rotating the guide bush body 144.

[0041] Furthermore, as shown in Figure 3, multiple engagement holes 145b1 (for example, three) are formed on the rear surface 145b of the adjustment nut 145.

[0042] The timing pulley 146 is cylindrical and, as shown in Figure 2, is rotatably inserted into the rear end side of the bearing retainer 141b of the guide bush holder 141.

[0043] A keyway 146a is formed on the inner circumference of the front end portion of the timing pulley 146, which engages with the key 142d of the guide bush sleeve 142. Furthermore, a belt positioning groove 146b is formed on the outer circumference of the timing pulley 146, and the timing belt V is wrapped around this belt positioning groove 146b.

[0044] The female thread formed on the inner circumference of the retaining nut 147 engages with the male thread formed on the outer circumference of the rear end portion of the guide bush sleeve 142. The female thread of the retaining nut 147 and the male thread of the guide bush sleeve 142 are threaded together, preventing the timing pulley 146 from coming out to the rear, as shown in Figure 2.

[0045] The flange 148 is an annular member and, as shown in Figure 2, is fixed to the guide bush support base 150 by fixing bolts B.

[0046] The rotary guide bush drive motor 149 is an electric motor, similar to the front spindle drive motor 123, and has an encoder 149a for detecting the rotation angle of the rotary guide bush drive motor 149. Furthermore, a timing pulley 149b, around which the timing belt V is threaded, is attached to the tip of the rotary guide bush drive motor 149.

[0047] Therefore, when the rotary guide bush drive motor 149 rotates, the timing pulley 146 of the rotary guide bush 140 rotates via the timing belt V, the guide bush sleeve 142 rotates via the key 142d that engages with the timing pulley 146, and the guide bush body 144 rotates via the set screw 142b mounted on the guide bush sleeve 142.

[0048] <2.4. Guide bush support base> The guide bush support base 150 is fixed to the bed 110. As shown in Figure 1, the guide bush support base 150 houses the timing pulley 149b attached to the tip of the rotary guide bush drive motor 149.

[0049] Furthermore, a tool rest movement mechanism 151 for mounting the tool rest 152 is provided on the rear side of the guide bush support base 150, on the side facing the main spindle 160. The tool post movement mechanism 151 allows the tool post 152 to be moved in the X and Y directions. The blade post 152 is fitted with a blade 152a whose tip is pointed towards the axis of rotation L. Therefore, by moving the front spindle 120 in the direction of the rotation axis L and moving the tool post 152 in the X or Y direction, the bar material W can be machined with the cutting tool 152a.

[0050] <2.5. Back main axis> As shown in Figure 1, the rear spindle 160 includes a headstock 161 mounted on the rear spindle feed mechanism 170 and movable in the Z2 and X2 directions, a rear spindle body 162 rotatably supported on the headstock 161, a rear spindle drive motor 163 that rotates the rear spindle body 162, and an encoder 164 that detects the rotation angle of the rear spindle drive motor 163.

[0051] The rear spindle body 162 is supported by the headstock 161 with its axis in the Z2 direction, which is parallel to the Z1 direction shown in Figure 1, and as shown in Figure 2, it is capable of rotatably gripping (holding) the rod material W via the chuck 162a. The chuck 162a is configured concentrically with the rear spindle body 162 and is rotatable integrally with the rear spindle body 162.

[0052] As shown in Figure 2, a retaining jig 165 for holding the rod material W is detachably attached to the chuck 162a. As shown in Figures 2 and 4, the holding jig 165 consists of a C-shaped spindle mount 165a attached to the rear spindle body 162, a C-shaped spindle holder 165b for holding the spindle W, and a connecting bolt 165c that connects the spindle mount 165a and the spindle holder 165b, forming a C-shaped member when viewed from the front spindle 120 side.

[0053] As shown in Figure 2, the spindle mount 165a has an inner diameter that is approximately equal to the outer diameter of the rear spindle body 162. Furthermore, as shown in Figure 4, the spindle mount 165a is fastened to the rear spindle body 162 by inserting a tightening bolt 165d through a through hole formed in the circumferential direction of the spindle mount 165a and screwing it into a threaded hole opposite to the through hole. As a result, the spindle mount 165a rotates together with the rear spindle body 162.

[0054] The rod holder 165b has a through hole that extends in the Z2 direction. The connecting bolt 165c is inserted through this through hole and screws into the threaded hole formed on the front surface 165a1 of the spindle mount 165a, thereby integrating the bar holder 165b with the spindle mount 165a. Furthermore, since the rod holder 165b is a C-shaped ring, the inner diameter φ of the rod holder 165b is variable, as shown in Figure 2. The inner diameter of the rod holder 165b is adjusted by inserting an adjustment bolt 165e through a through hole formed perpendicular to the circumferential direction of the rod holder 165b and screwing it into the threaded hole 165b1 opposite the through hole.

[0055] The rear spindle drive motor 163 is an electric motor, similar to the front spindle drive motor 123.

[0056] <2.6. Rear spindle feed mechanism> As shown in Figure 1, the rear spindle feed mechanism 170 consists of an X2-direction feed structure 171 mounted on the bed 110 and a Z2-direction feed structure 172 mounted on the X2-direction feed structure 171.

[0057] The X2 direction feed structure 171 includes an X2 rail 171a fixed to the bed 110 and extending in the X2 direction, an X2 slider 171b mounted on the X2 rail 171a and slidable along the X2 direction, and an X2 motor 171c that slides the X2 slider 171b.

[0058] The Z2-direction feed structure 172 includes a Z2 rail 172a fixed to the X2 slider 171b and extending in the Z2 direction, a Z2 slider 172b mounted on the Z2 rail 172a and slidable along the Z2 direction, and a Z2 motor 172c that slides the Z2 slider 172b. The headstock 161 of the rear spindle 160 is mounted on the Z2 slider 172b.

[0059] <2.7. Control Devices> The rotation of the front spindle 120, rotary guide bush 140, and rear spindle 160, and the movement of the front spindle feed mechanism 130 and rear spindle feed mechanism 170 are controlled by the control device 180. The control device 180 includes a control unit 181 and an input unit 182, which are connected via a bus.

[0060] The control unit 181 consists of a CPU, memory, etc., and loads various programs and data stored in ROM into RAM, for example, and executes this program. In other words, the operation of the machine tool 100 is controlled by a program loaded into the control unit 181. The rotation of the front spindle 120, rotary guide bush 140, and rear spindle 160, as well as the movement of the front spindle feed mechanism 130 and rear spindle feed mechanism 170, can be set by program or by input to the input unit 182.

[0061] Furthermore, the control unit 181 includes a motor control unit 181a, a guide bush opening degree determination unit 181b, and a data table 181c.

[0062] The motor control unit 181a controls the operation of the front spindle drive motor 123, the rear spindle drive motor 163, the rotary guide bush drive motor 149, the Z1 motor 133, and the Z2 motor 172c when adjusting the gap between the rod W and the rotary guide bush 140 (i.e., the guide bush body 144). Furthermore, the motor control unit 181a of the control device 180 synchronizes the rotational drive of the front spindle drive motor 123 or the rotational drive of the rear spindle drive motor 163 with the rotational drive of the rotary guide bush drive motor 149.

[0063] The guide bush opening determination unit 181b determines the amount of adjustment for the gap between the rod W and the guide bush body 144 by referring to the data table 181c, based on one of the following: the rotation angle of the front spindle drive motor 123 measured by the encoder 124, the rotation angle of the rotary guide bush drive motor 149 measured by the encoder 149a, or the rotation angle of the rear spindle drive motor 163 measured by the encoder 164. More specifically, the guide bush opening determination unit 181b estimates the size of the gap between the bar W and the guide bush body 144 based on one of the rotation angles of the front spindle drive motor 123, the rotary guide bush drive motor 149, or the rear spindle drive motor 163. It then calculates the difference between this estimated gap size and the optimal gap size, and determines the amount of rotation of the rear spindle 160, i.e., the amount of adjustment for the gap between the bar W and the guide bush body 144, based on this difference.

[0064] Data table 181c stores data corresponding to the size of the gap between the rod W and the guide bush body 144, and one of the following rotation angles: the rotation angle of the front spindle drive motor 123, the rotation angle of the rotary guide bush drive motor 149, or the rotation angle of the rear spindle drive motor 163, depending on the material and diameter of the rod W.

[0065] <2.8. Rotating fixtures> As shown in Figure 2, the machine tool 100 is equipped with a rotating jig 190 for rotating an adjustment nut 145 that adjusts the size of the gap between the rod W and the guide bush body 144.

[0066] The rotating jig 190 is C-shaped and ring-shaped, as shown in Figure 5, and has a rod W inserted inside, as shown in Figure 2. Furthermore, this rotating jig 190, like the rod holder 165b, has a variable inner diameter. The inner diameter of the rotating jig 190 is adjusted by inserting a tightening bolt 191 through a through hole formed perpendicular to the circumferential direction of the rotating jig 190 and screwing it into a threaded hole 190a opposite to the through hole.

[0067] Furthermore, an engagement pin 192 is provided on the front surface 190b of the rotary jig 190, which engages with the engagement hole 145b1 of the adjustment nut 145 of the rotary guide bush 140.

[0068] <3. Gap Adjustment Procedure> Next, based on Figures 1 to 25B, the procedure for adjusting the size of the gap between the rod W and the rotary guide bush 140, that is, the gap between the rod W and the guide bush body 144, using a machine tool 100 which is one embodiment of the present invention, will be explained with six specific examples. The specific examples shown below are merely examples, and the procedure for adjusting the gap between the rod W and the guide bush body 144 is not limited to these examples.

[0069] <3.1. First specific example: Utilizing the rotation angle of the rotary guide bush drive motor> First, a first specific example using the front spindle 120 and rotary guide bush 140 of the machine tool 100 will be described based on Figures 6A to 10B. Figure 6A is a flowchart showing the procedure for adjusting the size of the gap between the rod and the rotary guide bush; Figure 6B is a flowchart showing the preparation process shown in Figure 6A; Figure 6C is a flowchart showing the gap adjustment process shown in Figure 6A; Figure 7A is a schematic diagram showing the state in which the rod is inserted through the front spindle; Figure 7B is a schematic diagram showing the state in which the rod is inserted up to the rotary guide bush; Figure 7C is a schematic diagram showing the state in which the front spindle is advanced and the rotating jig and the adjustment nut are engaged; Figure 8 is a schematic diagram showing the state in which the rotating jig and the adjustment nut are disengaged; Figure 9 is a schematic diagram showing the rotating jig and rod shown in Figure 8 viewed from the rear; Figure 10A is a schematic diagram showing the state in which the front spindle is advanced and the rotating jig and the adjustment nut are engaged; and Figure 10B is a schematic diagram illustrating the process of adjusting the size of the gap between the rod and the guide bush body by rotating the front spindle.

[0070] <3.1.1.Preparation process> (Step S10) First, the machine tool 100 performs the preparation steps shown in Figure 6B.

[0071] (Step S11) In the preparation process, the rod W is inserted from the rear end of the front main shaft 120 using a pusher of a bar feeder (not shown) (see Figure 7A), and then inserted through the rotating jig 190 and the rotary guide bush 140 in that order. At this time, the rotation center of the front main shaft 120 is aligned with the rotation center of the rotary guide bush 140 (guide bush body 144).

[0072] (Step S12) Next, as shown in Figure 7B, the rotating jig 190 is tightened and fixed to the rod W, so that the rotating jig 190 and the rod W rotate together around the rotation axis L. When the rotating jig 190 is fixed to the rod W, the rod W protrudes forward from the rotary guide bush 140.

[0073] (Step S13) Next, as shown in Figure 7C, the front spindle 120 grips (holds) the rod W and moves forward to insert the engagement pin 192 of the rotating jig 190 into the engagement hole 145b1 of the adjustment nut 145 of the rotary guide bush 140. When the engaging pin 192 of the rotating jig 190 is inserted into the engaging hole 145b1 of the adjustment nut 145 of the rotary guide bush 140, the orientation of the adjustment nut 145, that is, the rotational position of the guide bush body 144 and the rotational position of the front main shaft 120 are set to a predetermined position (hereinafter referred to as the "reference angular position").

[0074] Furthermore, when the front spindle 120 moves forward, if the positions of the engagement hole 145b1 of the adjustment nut 145 and the engagement pin 192 of the rotating jig 190 are misaligned in the rotational direction, the rod W (i.e., the front spindle 120 holding the rod W) or the adjustment nut 145 (i.e., the guide bush body 144) is rotated until the engagement hole 145b1 of the adjustment nut 145 and the engagement pin 192 of the rotating jig 190 are aligned.

[0075] (Step S14) Next, the front spindle 120 is retracted from the rotary guide bush 140 until the rotating jig 190 disengages from the adjustment nut 145, resulting in the state shown in Figure 8.

[0076] <3.1.2. Inspection Process> (Step S20) Next, in this state, the excitation of the rotary guide bush drive motor 149 is turned off. Therefore, the guide bush body 144 is rotatable with respect to the rod W.

[0077] (Step S21) Then, the front main shaft 120 is rotated in a predetermined direction by a predetermined angle. In other words, the front main shaft 120 is rotated to rotate the rod W from the reference angular position P to the angular position P1 by a predetermined angle θ, as shown in Figure 9.

[0078] (Step S22) When the rod W is rotated by a predetermined angle θ from the reference angular position P to the angular position P1, the rotary guide bush drive motor 149 is de-energized, and therefore the guide bush body 144 is rotatable relative to the rod W.

[0079] Therefore, as described above, if the gap between the rod W and the guide bush body 144 is narrow when the rod W rotates by a predetermined angle θ from the reference angular position P to the angular position P1, the rod W and the guide bush body 144 may come into contact, and this contact with the rod W may cause the guide bush body 144 to rotate together with the rod W. As the guide bush body 144 rotates, the guide bush sleeve 142, which is integrated with the guide bush body 144 by a set screw 142b, rotates, and the timing pulley 146, which engages with the key 142d embedded in the guide bush sleeve 142, rotates. Then, the rotation of the timing pulley 146 is transmitted from the timing belt V to the timing pulley 149b of the rotary guide bush drive motor 149, causing the rotary guide bush drive motor 149 to rotate. Conversely, if the gap between the rod W and the guide bush body 144 is too large when the rod W rotates by a predetermined angle θ from the reference angular position P to the angular position P1, the rod W and the guide bush body 144 will not make contact, and the guide bush body 144, i.e., the rotary guide bush drive motor 149, may not rotate.

[0080] Therefore, in step S22, with the rod material W held by the front spindle 120 and the excitation of the rotary guide bush drive motor 149 turned off, it is determined whether the rotation angle of the guide bush body 144, that is, the rotary guide bush drive motor 149, is within a predetermined angular range.

[0081] If the rotation angle of the rotary guide bush drive motor 149 is within a predetermined angle range, the size of the gap between the rod W and the guide bush body 144 is considered to be the optimal size, and the adjustment of the size of the gap between the rod W and the guide bush body 144 is completed.

[0082] On the other hand, if the rotation angle of the rotary guide bush drive motor 149 falls below the lower limit of a predetermined angle range, the gap between the rod W and the guide bush body 144 is too large, and therefore the process proceeds to step S23, requiring adjustment of the gap between the rod W and the guide bush body 144. Furthermore, if the rotation angle of the rotary guide bush drive motor 149 exceeds the upper limit of a predetermined angle range, the gap between the rod W and the guide bush body 144 is too small, and therefore the process proceeds to step S23, requiring adjustment of the gap between the rod W and the guide bush body 144.

[0083] (Step S23) In step S23, the front spindle 120 is rotated to rotate the rod W from angular position P1 back to the reference angular position P (i.e., in the opposite direction to step S21).

[0084] (Step S24) Next, the rotary guide bush drive motor 149 is energized. As a result, a holding torque is applied to the rotary guide bush drive motor 149, and this holding torque affects the timing pulley 146 of the rotary guide bush 140, so that the timing pulley 146 will not rotate even if you try to rotate it.

[0085] (Step S25) Next, the rotary guide bush drive motor 149 is rotated to return the rotational position of the guide bush body 144 to the reference angular position determined in step S13, so that the rotating jig 190 can be inserted into the adjustment nut 145 of the rotary guide bush 140.

[0086] <3.1.3. Gap Adjustment Process> (Step S30) Next, the process proceeds to step S30, where the gap adjustment process is performed to adjust the size of the gap between the rod W and the guide bush body 144 as shown in Figure 6C.

[0087] (Step S31) First, the front spindle 120 is advanced until the rotating jig 190 is inserted into the adjustment nut 145 of the rotary guide bush 140, bringing it to the state shown in Figure 10A.

[0088] (Step S32) In this state, as shown in Figure 10B, the front main shaft 120 is rotated by a predetermined amount in a predetermined direction based on the output result from the guide bush opening determination unit 181b. The rotation of the front spindle 120 causes the rod W to rotate, and the rotating jig 190 fixed to the rod W rotates by a predetermined amount in a predetermined direction.

[0089] Since the timing pulley 146 does not rotate, the guide bush sleeve 142, which is engaged with the timing pulley 146 by key 142d, and the guide bush body 144, which is engaged with the guide bush sleeve 142 by set screw 142b, also do not rotate. However, when the rotating jig 190 rotates, the adjustment nut 145 that engages with the rotating jig 190 also rotates. Since the adjustment nut 145 cannot move in the Z direction due to the guide bush sleeve 142 and the rotating jig 190, the guide bush body 144 that is screwed with the adjustment nut 145 moves back and forth in the Z direction relative to the guide bush sleeve 142 and the adjustment nut 145 in accordance with the rotation direction of the adjustment nut 145, and the size of the gap between the rod W and the guide bush body 144 is adjusted.

[0090] (Step S33) After the gap between the rod W and the guide bush body 144 changes by a predetermined amount, the front spindle 120 is retracted to disengage the rotating jig 190 from the adjustment nut 145 of the rotary guide bush 140, and the process returns to step S20.

[0091] The above steps are repeated as appropriate until the rotation angle of the rotary guide bush drive motor 149 falls within a predetermined angle range.

[0092] <3.2. Second specific example: Utilizing the rotation angle of the front spindle drive motor> Next, a second specific example using the front spindle 120 and rotary guide bush 140 of the machine tool 100 will be described based on Figures 8, 11A, 11B, etc. Figure 11A is a flowchart showing the procedure for adjusting the size of the gap between the rod and the rotary guide bush, and Figure 11B is a flowchart showing the gap adjustment process shown in Figure 11A. Since the second example includes some of the same procedures as the first example, the steps that are the same as those in the first example will be omitted from the explanation and will use the same step numbers as the first example.

[0093] <3.2.1. Inspection Process> (Step S20A) After the preparation process (step S10), the state shown in Figure 8 is reached. In this state, the excitation of the front spindle drive motor 123 is turned off. Therefore, the front spindle body 122 and the front spindle drive motor 123 are rotatable relative to the bar material W.

[0094] (Step S21A) Then, the rotary guide bush drive motor 149 is driven to rotate the guide bush body 144 of the rotary guide bush 140 by a predetermined angle in a predetermined direction (i.e., by a predetermined angle θ from the reference angular position P to angular position P1).

[0095] (Step S22A) When the guide bush body 144 rotates by a predetermined angle θ from a reference angular position P to angular position P1, if the gap between the rod W and the guide bush body 144 is narrow, the rod W and the guide bush body 144 may come into contact, and this contact with the rod W may cause the rod W to rotate together with the guide bush body 144. As the rod W rotates, the front spindle body 122, which is gripping the rod W, rotates, and the front spindle drive motor 123, which rotates the front spindle body 122, also rotates. Conversely, if the gap between the rod W and the guide bush body 144 is too large when the guide bush body 144 rotates by a predetermined angle θ from the reference angular position P to the angular position P1, the rod W and the guide bush body 144 will not make contact, and the rod W, i.e., the front spindle drive motor 123, may not rotate.

[0096] Therefore, in step S22A, while the rod material W is held by the guide bush body 144 of the rotary guide bush 140 and the excitation of the front spindle drive motor 123 is turned off, it is determined whether or not the rotation angle of the front spindle drive motor 123 is within a predetermined angle range.

[0097] If the rotation angle of the front spindle drive motor 123 is within a predetermined angle range, the size of the gap between the rod W and the guide bush body 144 is considered to be the optimal size, and the adjustment of the gap size between the rod W and the guide bush body 144 is completed.

[0098] On the other hand, if the rotation angle of the front spindle drive motor 123 falls below the lower limit of the predetermined angle range, the gap between the rod W and the guide bush body 144 is too large, and therefore the process proceeds to step S23A, requiring adjustment of the gap between the rod W and the guide bush body 144. Furthermore, if the rotation angle of the front spindle drive motor 123 exceeds the upper limit of a predetermined angle range, the gap between the rod W and the guide bush body 144 is too small, and therefore the process proceeds to step S23A, requiring adjustment of the gap between the rod W and the guide bush body 144.

[0099] (Step S23A) In step S23A, the rotary guide bush drive motor 149 is rotated to rotate the guide bush body 144 from angular position P1 back to reference angular position P (i.e., in the opposite direction to step S21A).

[0100] (Step S24A) Next, the front spindle drive motor 123 is energized. As a result, a holding torque is applied to the front spindle drive motor 123 and the rotary guide bush drive motor 149. Even if the front spindle drive motor 123 is driven, the holding torque of the rotary guide bush drive motor 149 prevents the rod W from rotating.

[0101] (Step S25A) Next, the front spindle drive motor 123 is rotated to return the rotational position of the front spindle 120 to the reference angular position P defined in step S13, so that the rotating jig 190 can be inserted into the adjustment nut 145 of the rotary guide bush 140.

[0102] <3.2.2. Gap Adjustment Process> (Step S30A) Next, proceed to step S30A and perform the various steps of the gap adjustment process shown in Figure 11B.

[0103] (Step S32A) After step S31 is performed, the guide bush body 144 is rotated by a predetermined amount in a predetermined direction based on the output result from the guide bush opening determination unit 181b.

[0104] Since the rod W has stopped rotating, the rotating jig 190 also stops rotating, and therefore the adjustment nut 145 also stops rotating. Therefore, when the guide bush body 144 is rotated by a predetermined amount in a predetermined direction, the guide bush body 144 moves back and forth in the Z direction relative to the guide bush sleeve 142 and the adjustment nut 145 in accordance with the rotation direction of the adjustment nut 145, and the size of the gap between the rod W and the guide bush body 144 is adjusted.

[0105] Then, after performing step S33, the above steps are repeated as appropriate until the rotation angle of the front spindle drive motor 123 falls within a predetermined angle range.

[0106] <3.3. Third specific example: Utilizing the rotation angle of the rotary guide bush drive motor> Next, a third specific example using the rear spindle 160 and rotary guide bush 140 of the machine tool 100 will be described based on Figures 12A to 16B. Figure 12A is a flowchart showing the procedure for adjusting the size of the gap between the rod and the rotary guide bush; Figure 12B is a flowchart showing the preparation process shown in Figure 12A; Figure 12C is a flowchart showing the gap adjustment process shown in Figure 12A; Figure 13A is a schematic diagram showing the state in which the rod is inserted through the front spindle; Figure 13B is a schematic diagram showing the state in which the rod is inserted all the way to the rear spindle; Figure 13C is a schematic diagram showing the state in which the rear spindle is retracted and the rotating jig and adjustment nut are engaged; Figure 14 is a schematic diagram showing the state in which the rotating jig and adjustment nut are disengaged; Figure 15 is a schematic diagram showing the rotating jig and rod shown in Figure 14 viewed from the rear; Figure 16A is a schematic diagram showing the state in which the rear spindle is retracted and the rotating jig and adjustment nut are engaged; and Figure 16B is a schematic diagram illustrating the process of adjusting the size of the gap between the rod and the guide bush body by rotating the rear spindle. Since the third example includes some of the same procedures as the first example, the steps that are the same as those in the first example will be omitted from the explanation and will use the same step numbers as the first example.

[0107] <3.3.1. Preparation process> (Step S100) First, the machine tool 100 performs the preparation steps shown in Figure 12B.

[0108] (Step S110) In the preparation process, with the rotation center of the rear spindle 160 aligned with the rotation center of the front spindle 120 and the rotation center of the rotary guide bush 140 (guide bush body 144), the rod W is inserted from the rear end of the front spindle 120 using a pusher of a bar feeder (not shown) (see Figure 13A), and then inserted in the order of the rotating jig 190, rotary guide bush 140, and rear spindle 160.

[0109] (Step S130) After step S12 is performed, as shown in Figure 13B, the retaining jig 165 of the rear spindle 160 is tightened to the rod W using the adjustment bolt 165e of the retaining jig 165, thereby gripping (holding) it with the rear spindle 160.

[0110] (Step S140) Next, as shown in Figure 13C, with the rear spindle 160 gripping the rod W, the rear spindle 160 is retracted to insert the engagement pin 192 of the rotating jig 190 into the engagement hole 145b1 of the adjustment nut 145 of the rotary guide bush 140. When the engaging pin 192 of the rotating jig 190 is inserted into the engaging hole 145b1 of the adjustment nut 145 of the rotary guide bush 140, the orientation of the adjustment nut 145, that is, the rotational position of the guide bush body 144 and the rotational position of the rear main shaft 160 are set to a predetermined position (hereinafter referred to as the "reference angular position").

[0111] Furthermore, when the rear spindle 160 retracts, if the positions of the engagement hole 145b1 of the adjustment nut 145 and the engagement pin 192 of the rotating jig 190 are misaligned in the rotational direction, the rod W (i.e., the rear spindle 160 holding the rod W) or the adjustment nut 145 (i.e., the guide bush body 144) is rotated until the engagement hole 145b1 of the adjustment nut 145 and the engagement pin 192 of the rotating jig 190 are aligned.

[0112] (Step S150) Next, the rear spindle 160 is advanced toward the rotary guide bush 140 until the rotating jig 190 disengages from the adjustment nut 145, resulting in the state shown in Figure 14.

[0113] <3.3.2. Inspection Process> (Step S210) Next, after performing step S20, the rear spindle 160 is rotated in a predetermined direction by a predetermined angle. In other words, the rear main shaft 160 is rotated to rotate the rod W from the reference angular position P to the angular position P1 by a predetermined angle θ, as shown in Figure 15.

[0114] (Step S220) When the rod W is rotated by a predetermined angle θ from the reference angular position P to the angular position P1, the rotary guide bush drive motor 149 is de-energized, and therefore the guide bush body 144 is rotatable relative to the rod W.

[0115] In this state, similar to the first specific example, the rotary guide bush drive motor 149 may or may not rotate due to the rotation of the rod W. Therefore, in step S220, with the rod material W held by the rear spindle 160 and the excitation of the rotary guide bush drive motor 149 turned off, it is determined whether the rotation angle of the guide bush body 144, that is, the rotary guide bush drive motor 149, is within a predetermined angle range.

[0116] If the rotation angle of the rotary guide bush drive motor 149 is within a predetermined angle range, the size of the gap between the rod W and the guide bush body 144 is considered to be the optimal size, and the adjustment of the size of the gap between the rod W and the guide bush body 144 is completed.

[0117] On the other hand, if the rotation angle of the rotary guide bush drive motor 149 falls below the lower limit of the predetermined angle range, or if the rotation angle of the rotary guide bush drive motor 149 exceeds the upper limit of the predetermined angle range, the process proceeds to step S230, as in the first specific example, because it is necessary to adjust the size of the gap between the rod W and the guide bush body 144.

[0118] (Step S230) In step S230, the rear spindle 160 is rotated to rotate the rod W from angular position P1 back to the reference angular position P (i.e., in the opposite direction to step S210). Then proceed to steps S24 and S25.

[0119] <3.3.3. Gap Adjustment Process> (Step S300) Next, the process proceeds to step S300, where the gap adjustment process is performed to adjust the size of the gap between the rod W and the guide bush body 144 as shown in Figure 12C.

[0120] (Step S310) First, the rear spindle 160 is retracted until the rotating jig 190 is inserted into the adjustment nut 145 of the rotary guide bush 140, bringing it to the state shown in Figure 16A.

[0121] (Step S320) Then, as shown in Figure 16B, with the rod material W held by the rear spindle 160, the rear spindle 160 is rotated by a predetermined amount in a predetermined direction based on the output result from the guide bush opening determination unit 181b. The rotation of the rear spindle 160 causes the rod W to rotate, and the rotating jig 190 fixed to the rod W rotates by a predetermined amount in a predetermined direction, thereby adjusting the size of the gap between the rod W and the guide bush body 144, similar to the first specific example.

[0122] (Step S330) After the gap between the rod W and the guide bush body 144 changes by a predetermined amount, the rear spindle 160 is advanced to disengage the rotating jig 190 from the adjustment nut 145 of the rotary guide bush 140, and the process returns to step S200.

[0123] The above steps are repeated as appropriate until the rotation angle of the rotary guide bush drive motor 149 falls within a predetermined angle range.

[0124] <3.4. Fourth specific example: Utilizing the rotation angle of the rear spindle drive motor> Next, a fourth specific example using the rear spindle 160 and rotary guide bush 140 of the machine tool 100 will be described based on Figures 14, 17A, 17B, etc. Figure 17A is a flowchart showing the procedure for adjusting the gap size between the rod and the rotary guide bush, and Figure 17B is a flowchart showing the gap adjustment process shown in Figure 17A. Since the fourth example includes some of the same procedures as the second and third examples, the steps that are the same as those in the second and third examples will be omitted from the explanation and will be given the same step numbers as in the second and third examples.

[0125] <3.4.1. Inspection Process> (Step S200A) After the preparation process (step S100), the state shown in Figure 14 is reached. In this state, the excitation of the rear spindle drive motor 163 is turned off. Therefore, the rear spindle body 162 and the rear spindle drive motor 163 are rotatable relative to the rod W. Next, step S21A is performed.

[0126] (Step S220A) If the gap between the rod W and the guide bush body 144 is narrow when the guide bush body 144 rotates by a predetermined angle θ from the reference angular position P to the angular position P1 in step S21A, the rod W and the guide bush body 144 may come into contact, and this contact with the rod W may cause the rod W to rotate together with the guide bush body 144. As the rod W rotates, the rear spindle body 162, which is gripping the rod W, rotates, and the rear spindle drive motor 163, which rotates the rear spindle body 162, also rotates. Conversely, if the gap between the rod W and the guide bush body 144 is too large when the guide bush body 144 rotates by a predetermined angle θ from the reference angular position P to the angular position P1, the rod W and the guide bush body 144 will not make contact, and the rod W, i.e., the rear spindle drive motor 163, may not rotate.

[0127] Therefore, in step S220A, while the rod material W is held by the guide bush body 144 of the rotary guide bush 140 and the excitation of the rear spindle drive motor 163 is turned off, it is determined whether or not the rotation angle of the rear spindle drive motor 163 is within a predetermined angle range.

[0128] If the rotation angle of the rear spindle drive motor 163 is within a predetermined angle range, the size of the gap between the rod W and the guide bush body 144 is considered to be the optimal size, and the adjustment of the gap size between the rod W and the guide bush body 144 is completed.

[0129] On the other hand, if the rotation angle of the rear spindle drive motor 163 falls below the lower limit of the predetermined angle range, the gap between the rod W and the guide bush body 144 is too large, and therefore the process proceeds to step S23A, requiring adjustment of the gap between the rod W and the guide bush body 144. Furthermore, if the rotation angle of the rear spindle drive motor 163 exceeds the upper limit of a predetermined angle range, the gap between the rod W and the guide bush body 144 is too small, and therefore the process proceeds to step S23A, requiring adjustment of the gap between the rod W and the guide bush body 144.

[0130] (Step S240A) Following step S23A, the rear spindle drive motor 163 is energized. As a result, a holding torque is applied to the rear spindle drive motor 163 and the rotary guide bush drive motor 149. Even if the rear spindle drive motor 163 is driven, the holding torque of the rotary guide bush drive motor 149 prevents the rod W from rotating.

[0131] (Step S250A) Next, the rear spindle drive motor 163 is rotated to return the rotational position of the rear spindle 160 to the initial position determined in step S130, so that the rotating jig 190 can be inserted into the adjustment nut 145 of the rotary guide bush 140.

[0132] <3.4.2. Gap Adjustment Process> (Step S300A) Next, proceed to step S300A and perform the various steps of the gap adjustment process shown in Figure 17B.

[0133] Then, after performing steps S310, S32A, and S330, the above steps are repeated as appropriate until the rotation angle of the rear spindle drive motor 163 falls within a predetermined angle range.

[0134] <3.5. Fifth specific example: Utilizing the rotation angle of the rotary guide bush drive motor> Next, a fifth specific example using the front spindle 120, rotary guide bush 140, and rear spindle 160 of the machine tool 100 will be described based on Figures 13, 18A to 21B. Figure 18A is a flowchart showing the procedure for adjusting the size of the gap between the rod and the rotary guide bush; Figure 18B is a flowchart showing the gap adjustment process shown in Figure 18A; Figure 19 is a schematic diagram showing the state in which the engagement between the rotating jig and the adjustment nut is released; Figure 20 is a schematic diagram showing the rotating jig and rod shown in Figure 19 viewed from the rear; Figure 21A is a schematic diagram showing the state in which the rear spindle is retracted and the rotating jig and the adjustment nut are engaged; and Figure 21B is a schematic diagram illustrating the process of adjusting the size of the gap between the rod and the guide bush body by rotating the front spindle. Since the fifth specific example includes some of the same procedures as the first and third specific examples, the steps that are the same as those in the first and third specific examples will be omitted from the explanation and will be given the same step numbers as those in the first and third specific examples.

[0135] <3.5.1. Preparation process> (Step S100) First, the machine tool 100 performs the preparation process S100.

[0136] Furthermore, when the rear spindle 160 retracts, if the positions of the engagement hole 145b1 of the adjustment nut 145 and the engagement pin 192 of the rotating jig 190 are misaligned in the rotational direction, the gripping of the rod W is switched from the rear spindle 160 to the front spindle 120, and the rod W (i.e., the front spindle 120 holding the rod W) or the adjustment nut 145 (i.e., the guide bush body 144) is rotated until the engagement hole 145b1 of the adjustment nut 145 and the engagement pin 192 of the rotating jig 190 are directly facing each other.

[0137] <3.5.2. Inspection Process> (Step S2100) After performing step S100 and reaching the state shown in Figure 19, step S200 is performed to switch the grip of the bar material W from the rear spindle 160 to the front spindle 120, and rotate the front spindle 120 by a predetermined angle in a predetermined direction. In other words, the front main shaft 120 is rotated to rotate the rod W from the reference angular position P to the angular position P1 by a predetermined angle θ, as shown in Figure 20.

[0138] Subsequently, the process proceeds to step S22. If the rotation angle of the rotary guide bush drive motor 149 is within a predetermined angle range, the adjustment of the gap between the rod W and the guide bush body 144 is considered to be the optimal size. In step S22, if the rotation angle of the rotary guide bush drive motor 149 falls below the lower limit of the predetermined angle range, or if the rotation angle of the rotary guide bush drive motor 149 exceeds the upper limit of the predetermined angle range, the process proceeds to steps S23, S24, and S25, as in the first specific example, by adjusting the size of the gap between the rod W and the guide bush body 144.

[0139] <3.5.3. Gap Adjustment Process> (Step S3000) After performing step S25, the process proceeds to step S3000, where various steps of the gap adjustment process are performed to adjust the size of the gap between the rod W and the guide bush body 144 as shown in Figure 18B.

[0140] (Step S3100) First, the gripping of the rod W is switched from the front spindle 120 to the rear spindle 160, and the rear spindle 160 is retracted until the rotating jig 190 is inserted into the adjustment nut 145 of the rotary guide bush 140, resulting in the state shown in Figure 21A.

[0141] (Step S3200) Then, as shown in Figure 21B, the gripping of the rod W is switched from the rear spindle 160 to the front spindle 120, and the front spindle 120 is rotated by a predetermined amount in a predetermined direction based on the output result from the guide bush opening determination unit 181b. The rotation of the front spindle 120 causes the rod W to rotate, and the rotating jig 190 fixed to the rod W rotates by a predetermined amount in a predetermined direction, thereby adjusting the size of the gap between the rod W and the guide bush body 144, similar to the first specific example.

[0142] (Step S3300) After the gap between the rod W and the guide bush body 144 changes by a predetermined amount, the grip of the rod W is switched from the front spindle 120 to the rear spindle 160, the rear spindle 160 is advanced to disengage the rotating jig 190 from the adjustment nut 145 of the rotary guide bush 140, and the process returns to step S200.

[0143] The above steps are repeated as appropriate until the rotation angle of the rotary guide bush drive motor 149 falls within a predetermined angle range.

[0144] <3.6. Sixth specific example: Utilizing the rotation angle of the rotary guide bush drive motor> First, a sixth specific example using the front spindle 120, rotary guide bush 140, and rear spindle 160 of the machine tool 100 will be described based on Figures 22A to 25B. Figure 22A is a flowchart showing the procedure for adjusting the size of the gap between the rod and the rotary guide bush; Figure 22B is a flowchart showing the preparation process shown in Figure 23A; Figure 22C is a flowchart showing the gap adjustment process shown in Figure 23A; Figure 23 is a schematic diagram showing the state in which the rotating jig and the adjustment nut are disengaged; Figure 24 is a schematic diagram showing the rotating jig and rod shown in Figure 23 viewed from the rear; Figure 25A is a schematic diagram showing the state in which the front spindle is advanced and the rotating jig and the adjustment nut are engaged; and Figure 25B is a schematic diagram illustrating the process of adjusting the size of the gap between the rod and the guide bush body by rotating the rear spindle. Note that the sixth example includes some of the same procedures as the first, third, and fifth examples; therefore, the steps that are the same as those in the first, third, and fifth examples will be omitted from the explanation, using the same step numbers as the first, third, and fifth examples.

[0145] <3.6.1.Preparation process> (Step S1000A) First, the machine tool 100 performs the preparation steps shown in Figure 23B.

[0146] (Step S1400A) After performing steps S110, S12, and S130, the grip of the bar stock W is switched from the rear spindle 160 to the front spindle 120. With the front spindle 120 gripping (holding) the bar stock W, the front spindle 120 is advanced to insert the engagement pin 192 of the rotating jig 190 into the engagement hole 145b1 of the adjustment nut 145 of the rotary guide bush 140. When the engaging pin 192 of the rotating jig 190 is inserted into the engaging hole 145b1 of the adjustment nut 145 of the rotary guide bush 140, the orientation of the adjustment nut 145, that is, the orientation of the guide bush body 144, is set to a predetermined orientation.

[0147] Furthermore, when the front spindle 120 moves forward, if the positions of the engagement hole 145b1 of the adjustment nut 145 and the engagement pin 192 of the rotating jig 190 are misaligned in the rotational direction, the rod W (i.e., the rear spindle 160 holding the rod W) or the adjustment nut 145 (i.e., the guide bush body 144) is rotated until the engagement hole 145b1 of the adjustment nut 145 and the engagement pin 192 of the rotating jig 190 are aligned.

[0148] (Step S1500A) Next, the front spindle 120 is retracted from the rotary guide bush 140 until the rotating jig 190 disengages from the adjustment nut 145, resulting in the state shown in Figure 23.

[0149] <3.6.2. Inspection Process> (Step S2100A) After performing step S200, the gripping of the bar material W is switched from the front spindle 120 to the rear spindle 160, and the rear spindle 160 is rotated in a predetermined direction by a predetermined angle. In other words, the rear main shaft 160 is rotated to rotate the rod W from the reference angular position P to the angular position P1 by a predetermined angle θ, as shown in Figure 24.

[0150] Subsequently, the process proceeds to step S22. If the rotation angle of the rotary guide bush drive motor 149 is within a predetermined angle range, the adjustment of the gap between the rod W and the guide bush body 144 is considered to be the optimal size. In step S220, if the rotation angle of the rotary guide bush drive motor 149 falls below the lower limit of the predetermined angle range, or if the rotation angle of the rotary guide bush drive motor 149 exceeds the upper limit of the predetermined angle range, the process proceeds to steps S230, S24, and S25, as in the first specific example, by adjusting the size of the gap between the rod W and the guide bush body 144.

[0151] <3.6.3. Gap Adjustment Process> (Step S3000A) After performing step S25, the process proceeds to step S3000A, where the gap adjustment process is carried out to adjust the size of the gap between the rod W and the guide bush body 144 as shown in Figure 22C.

[0152] (Step S3100A) First, the gripping of the rod W is switched from the rear spindle 160 to the front spindle 120, and the front spindle 120 is advanced until the rotating jig 190 is inserted into the adjustment nut 145 of the rotary guide bush 140, resulting in the state shown in Figure 25A.

[0153] (Step S3200A) Then, the gripping of the rod W is switched from the front spindle 120 to the rear spindle 160, and with the rod W held by the rear spindle 160, the rear spindle 160 is rotated by a predetermined amount in a predetermined direction based on the output result from the guide bush opening determination unit 181b, as shown in Figure 25B. The rotation of the rear spindle 160 causes the rod W to rotate, and the rotating jig 190 fixed to the rod W rotates by a predetermined amount in a predetermined direction, thereby adjusting the size of the gap between the rod W and the guide bush body 144, similar to the first specific example.

[0154] (Step S3300A) After the gap between the rod W and the guide bush body 144 changes by a predetermined amount, the grip of the rod W is switched from the rear spindle 160 to the front spindle 120, the front spindle 120 is retracted to disengage the rotating jig 190 from the adjustment nut 145 of the rotary guide bush 140, and the process returns to step S20.

[0155] The above steps are repeated as appropriate until the rotation angle of the rotary guide bush drive motor 149 falls within a predetermined angle range.

[0156] <4. Effects of machine tool 100> According to the machine tool 100 described above, the control device 180 has a guide bush opening determination unit 181b that determines the amount of gap adjustment based on the rotation angle of the rotary guide bush drive motor 149 when the spindle is rotated with the rod material W held by the spindle (front spindle 120 in the first and fifth specific examples, and rear spindle 160 in the third and sixth specific examples) without the rotary guide bush drive motor 149 being energized, thereby rotating the spindle drive motor (front spindle drive motor 123 in the first and fifth specific examples, and rear spindle drive motor 163 in the third and sixth specific examples) Because the rotation angle of the rotary guide bush drive motor 149, which is freely rotatable when driven, is based solely on the rotation of the rod W accompanying the rotational drive of the spindle drive motor, the signal-to-noise ratio is higher compared to the case where the size of the gap between the rotary guide bush and the rod is adjusted based on the load of the spindle drive motor when the spindle holding the rod is rotated by the spindle drive motor. In a structure where the opening of the rotary guide bush 140 is adjusted by the adjustment nut 145 and the rotary guide bush 140 rotates synchronously with the spindle, the gap between the rotary guide bush 140 and the rod W can be automatically adjusted with high precision. Alternatively, the control device 180 has a guide bush opening determination unit 181b that determines the amount of gap adjustment based on the rotation angle of the spindle drive motor when the guide bush body 144 of the rotary guide bush 140 is rotated while the rod W is held by the rotary guide bush 140 and the spindle drive motor (front spindle drive motor 123 in the second example, rear spindle drive motor 163 in the fourth example) is not energized, thereby the rotation angle of the spindle drive motor which is rotatable when the rotary guide bush drive motor 149 is rotated. Since the fluctuation is based solely on the rotation of the rod W accompanying the rotational drive of the rotary guide bush drive motor 149, the signal-to-noise ratio is higher compared to the case where the size of the gap between the rotary guide bush and the rod is adjusted based on the load of the spindle drive motor when the spindle holding the rod is rotated by the spindle drive motor. In a structure where the opening of the rotary guide bush 140 is adjusted by the adjustment nut 145 and the rotary guide bush 140 rotates synchronously with the spindle, the gap between the rotary guide bush 140 and the rod W can be automatically adjusted with high precision.

[0157] Furthermore, in the first, third, fifth, and sixth specific examples, the encoder 149a detects the rotation angle of the rotary guide bush drive motor 149, and the guide bush opening determination unit 181b determines the amount of gap adjustment based on the rotation angle of the rotary guide bush drive motor 149. Since the amount of gap adjustment is determined using the rotation angle of the guide bush body 144, which has a smaller moment of inertia than the moment of inertia of the main spindle, the amount of gap adjustment can be determined with greater accuracy compared to the case where the amount of gap adjustment is determined based on the rotation angle of the main spindle drive motor.

[0158] Furthermore, in the first and third specific examples, the rotation of the rod W around the rotation axis and the movement in the direction of the rotation axis are performed on the same main spindle (front main spindle 120 in the first example, and rear main spindle 160 in the third example), so that the gap between the rotary guide bush 140 and the rod W can be automatically adjusted with high precision using a minimal device configuration.

[0159] <Variation> Although a machine tool that is one embodiment of the present invention has been described above, the machine tool of the present invention is not limited to the machine tool of the embodiment described above.

[0160] For example, in the embodiment described above, the front spindle drive motor 123 was mounted on the headstock 121, but the front spindle drive motor does not have to be mounted on the headstock; for example, it may be mounted on the bed and rotate-drive the front spindle body via a transmission mechanism. The same applies to the rear spindle drive motor and the rotary guide bush drive motor.

[0161] For example, in the embodiment described above, the machine tool 100 was equipped with a front spindle 120 and a rear spindle 160. However, when performing the first and second specific examples of the procedure for adjusting the size of the gap between the bar stock W and the guide bush body 144, the machine tool does not need to have a rear spindle. [Explanation of Symbols]

[0162] 100... Machine tools 110 ··· Bed 120...Front spindle 121 ... Headstock 122...Front spindle body 122a ··· Chuck 123 ··· Front spindle drive motor 124 ··· Encoder 130 ··· Front spindle feed mechanism 131 ··· Z1 rail 132 ··· Z1 Slider 133 ··· Z1 motor 140 ··· Rotary guide bush 141 ··· Guide bush holder 141a ··· Guide bush holder body 141b ··· Bearing retainer 142 ··· Guide bush sleeve 142a ··· Taper 142b ··· Set screw 142c ··· Through-hole screw 142d ··· Key 143 ··· Bearing 144... Guide bush body 144a ··· Male screw 144b ··· Sliced 144c ··· Taper 144d...groove 145... Adjustment nut 145a ··· Female thread 145b... Rear 145b1... Engagement hole 146... Timing pulley 146a ··· Keyway 146b... Belt positioning groove 147 ··· Retaining nut 148 ··· Flange 149 ··· Rotary guide bush drive motor 149a ··· Encoder 149b... Timing pulley 150 ··· Guide bush support base 150a ··· Rotary guide bush insertion hole 151... Tool post movement mechanism 152... Knife rest 152a ··· Blades 160... Rear spindle 161 ... Headstock 162... Rear spindle body 162a ··· Chuck 163 ··· Rear spindle drive motor 164 ··· Encoder 165 ··· Holding fixture 165a... Spindle attachment 165a1... Front 165b... Material holder 165b1... Screw hole 165c ··· Connecting bolts 165d ··· Tightening bolt 165e ... Adjustment bolt 170 ··· Rear spindle feed mechanism 171 ··· X2 directional feed structure 171a ··· X2 rail 171b ··· X2 Slider 171c ··· X2 motor 172 ··· Z2 directional feed structure 172a ··· Z2 rail 172b ··· Z2 Slider 172c ··· Z2 motor 180 ··· Control device 181 ··· Control Unit 181a ··· Motor control unit 181b ··· Guide bush opening determination section 181c ··· Data Table 182 ··· Input Unit 190 ··· Rotary jig 190a ··· Screw hole 190b...Front 191... Tightening bolt 192 ··· Engaging pin W ··· Bar material F...Floor surface L ··· Rotation axis φ ··· Inner diameter of the rod holder V... Timing belt D1... Distance from the rotating jig to the adjustment nut D2... Distance from the rod to the holding jig B ··· Fixing bolt P... Reference angle position

Claims

1. A main shaft that holds the rod material in a rotatable manner, A spindle drive motor that rotates the spindle, A rotary guide bush that allows and supports the rotation of the rod material extending from the main spindle around the rotation axis and movement in the direction of the rotation axis, and rotates synchronously with the main spindle, A rotary guide bush drive motor for driving the rotary guide bush, An encoder for detecting the rotation angle of the rotary guide bush drive motor or the spindle drive motor, A machine tool comprising a control device for controlling the operation of the spindle and the rotary guide bush, The rotary guide bush comprises a guide bush holder fixed to a guide bush support base, a guide bush body that is rotatable relative to the guide bush holder and supports the rod material while allowing rotation around the rotation axis and movement in the direction of the rotation axis, and an adjustment nut that is screwed onto the guide bush body to adjust the size of the gap between the rod material and the guide bush body, A machine tool characterized in that the control device has a guide bush opening determination unit that determines the amount of adjustment of the gap based on the rotation angle of the rotary guide bush drive motor when the spindle is rotated with the rod material held by the spindle and the rotary guide bush drive motor is not energized, or based on the rotation angle of the spindle drive motor when the guide bush body of the rotary guide bush is rotated with the rod material held by the rotary guide bush and the spindle drive motor is not energized.

2. The encoder detects the rotation angle of the rotary guide bush drive motor, The machine tool according to claim 1, characterized in that the guide bush opening determination unit determines the amount of adjustment for the gap based on the rotation angle of the rotary guide bush drive motor.

3. The machine tool according to claim 1 or 2, characterized in that a rotating jig for engaging with the adjustment nut of the rotary guide bush and rotating the adjustment nut is mounted on the rod.

4. A main shaft that holds the rod material in a rotatable manner, A spindle drive motor that rotates the spindle, A rotary guide bush that allows and supports the rotation of the rod material extending from the main spindle around the rotation axis and movement in the direction of the rotation axis, and rotates synchronously with the main spindle, A rotary guide bush drive motor for driving the rotary guide bush, An encoder for detecting the rotation angle of the rotary guide bush drive motor, The system includes a control device for controlling the operation of the main spindle and the rotary guide bush, A control method for a machine tool comprising: a rotary guide bush; a guide bush holder fixed to a guide bush support base; a guide bush body that is rotatable relative to the guide bush holder and supports the rod material while allowing rotation around the rotation axis and movement in the direction of the rotation axis; and an adjustment nut that rotates the guide bush body to adjust the size of the gap between the rod material and the guide bush body and that screws into the guide bush body, wherein the rotary guide bush includes a guide bush holder fixed to a guide bush support base; a guide bush body rotatable relative to the guide bush holder and supporting the rod material; and an adjustment nut that screws into the guide bush body. The steps include: holding the rod material with the main shaft, The steps include rotating the main shaft around the rotation axis, The steps include: measuring the rotation angle of the rotary guide bush drive motor in an unexcited state, which is generated by rotating the main shaft, using the encoder; The steps include determining the amount of adjustment for the gap based on the rotation angle of the rotary guide bush drive motor measured by the encoder, The steps include rotating the main shaft around the rotation axis to rotate the guide bush body relative to the adjustment nut so that the determined amount of gap adjustment is achieved, A method for controlling machine tools, including the control method for machine tools.

5. A main shaft that holds the rod material in a rotatable manner, A spindle drive motor that rotates the spindle, A rotary guide bush that allows and supports the rotation of the rod material extending from the main spindle around the rotation axis and movement in the direction of the rotation axis, and rotates synchronously with the main spindle, A rotary guide bush drive motor for driving the rotary guide bush, An encoder for detecting the rotation angle of the spindle drive motor, The system includes a control device for controlling the operation of the main spindle and the rotary guide bush, A control method for a machine tool comprising: a rotary guide bush; a guide bush holder fixed to a guide bush support base; a guide bush body that is rotatable relative to the guide bush holder and supports the rod material while allowing rotation around the rotation axis and movement in the direction of the rotation axis; and an adjustment nut that rotates the guide bush body to adjust the size of the gap between the rod material and the guide bush body and that screws into the guide bush body, wherein the rotary guide bush includes a guide bush holder fixed to a guide bush support base; a guide bush body rotatable relative to the guide bush holder and supporting the rod material; and an adjustment nut that screws into the guide bush body. The steps include: holding the rod material with the main shaft, The steps include rotating the guide bush body around the rotation axis, The steps include: measuring the rotation angle of the spindle drive motor in an unexcited state, which is generated by rotating the guide bush body, using the encoder; The steps include determining the amount of adjustment for the gap based on the rotation angle of the spindle drive motor measured by the encoder, The steps include rotating the guide bush body around the rotation axis so that the adjustment amount of the gap is determined, thereby rotating the guide bush body relative to the adjustment nut, A method for controlling machine tools, including the control method for machine tools.

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