JP2008246656A - Bar transfer system and machine tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably transfer a bar of an extremely small diameter (for example, less than 1 mm) along a bar receiving hole of a rotating main spindle made in an extremely small diameter (for example, about 2 mm) without increasing its residual quantity. <P>SOLUTION: This bar transfer device 10 is furnished with a bar supporting part 14 having an axis 14a and a moving part 16 to move with the bar supporting part 14 along the axis 14a by holding the bar supporting part 14 free to rotate around the axis 14a as its center. The bar supporting part 14 is furnished with a holder 24 connected to the moving part 16 free to rotate around the axis 14a as its center and an extending bar 26 held by frictional force on the holder 24 and extending in a direction to separate from the moving part 16 along the axis 14a, and the extending bar 26 has a supporting surface 28 supporting the bar. The bar supporting part 14 has dimensions that the holder 24 can not be inserted into the bar receiving hole of the rotating main spindle of the machine tool along the whole of a previously specified transfer distance. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a bar material transfer device for transferring a bar material as a workpiece to a machine tool. Furthermore, this invention relates to the machine tool provided with the bar material conveying apparatus.

  An automatic bar feeder that feeds a long, thin bar-shaped workpiece (that is, a bar) to a machine tool such as an automatic lathe progressively and intermittently by a desired machining amount is known, for example, as a bar feeder. ing. This type of automatic bar feeder is a rail mechanism that linearly guides a bar along its axis on a stationary machine installed adjacent to a machine tool, and under the guidance of the rail mechanism. And a bar material transfer device for transferring the bar material.

  The bar material transport device equipped in the bar material automatic feeder is a bar material support part that supports the rear end of the bar material in the transfer direction, and a straight line with the bar material support part along the rail mechanism under the driving force of the drive source. A moving unit that moves. The bar support part is configured to be able to rotate at a high speed following the bar with respect to the moving part while the rotation main shaft of the machine tool holding the bar with the chuck rotates at high speed together with the bar. In general, the rod transfer device can be inserted into the rod receiving hole of the rotating spindle together with the rod for the purpose of reducing the unworkable length (ie remaining amount) of the rod fed to the rotating spindle of the machine tool. It has the shape of a long and narrow bar.

  As a conventional bar material transfer device, a bar material supporting part is provided with a holder that stably holds the rear end of the bar material, and this holder is a moving part (also referred to as a push bar) having a bar-like form as a whole. A configuration in which the units are rotatably connected is common. This bar material transfer device is configured such that the moving part is received together with the bar material and the holder in the bar material receiving hole of the rotating main shaft as the processing of the bar material progresses. In this configuration, the rod-shaped moving part has a certain thickness because of the dimensional requirements of the bearing structure with respect to the holder and the purpose of reducing the deflection in the rod material receiving hole of the rotating spindle. On the other hand, in recent machine tools, due to the miniaturization of the rotating spindle and its rotation drive system, the inner wall surface of the rod receiving hole of the rotating spindle and the outer peripheral surface of the moving part of the bar transferring device inserted into the bar receiving hole Is designed to be as small as possible. As a result, during the turning of the bar material, the stationary moving part easily comes into contact with the inner wall surface of the bar receiving hole of the rotating spindle that rotates at high speed, and the vibration generated in the moving part during such contact causes the bar to move. There is a concern that the processing accuracy of the material is reduced.

  In order to solve the above-described problems, in the bar transport device equipped in the bar automatic feeder, the rear end of the bar is attached to the tip of the bar-shaped member that can be inserted into the bar receiving hole of the rotary spindle of the machine tool. There has been proposed a configuration in which a holder to be held is fixed and a rear end of a rod-like member is rotatably connected to a moving unit connected to a drive source (see, for example, Patent Document 1). The bar material transfer device described in Patent Document 1 includes a gripper that grips the rear end of the bar, a bar-shaped feed rod having a gripper fixed to the front end, and a holding member that rotatably holds the rear end of the feed rod. Is provided. In this configuration, the gripper and the feed rod function as a bar support portion having a rotation axis, and can be inserted into the bar receiving hole of the rotation main shaft together with the bar. In addition, the holding member rotatably supports the bar support part (gripper and feed rod) and moves together with the bar support part along the rotation axis of the bar support part under the driving force of the drive source. It functions as a part.

Japanese Patent No. 3641305

  The bar material transfer device disclosed in Patent Document 1 is configured such that a feed rod formed so as to be insertable into a bar material receiving hole of a rotation main shaft is rotatable with respect to a moving unit integrally with a gripper supporting the bar material. Since the configuration is adopted, even when the feed rod comes into contact with the inner wall surface of the rod receiving hole of the rotating spindle during the turning of the rod, vibration generated in the feed rod can be reduced. On the other hand, the feed rod is required to have a certain thickness because of the dimensional requirements of the bearing structure with respect to the holding member (moving part) and the purpose of reducing the swirl in the rod receiving hole of the rotating main shaft. .

  Specifically, an example of the bearing structure described in Patent Document 1 is to insert a shaft portion protruding from the front end of the holding member into a concave portion provided at the rear end of the feed rod via a bearing. For this reason, it is difficult to reduce the outer diameter of the feed rod to a level of 5 mm or less (for example, 2 mm) from the viewpoint of imparting dimensions and rigidity capable of installing the bearing to the recess. In another example of the bearing structure described in Patent Document 1, a small-diameter shaft portion protruding from the rear end of the feed rod is inserted into a through hole provided in the holding member via a bearing. Therefore, it is difficult to reduce the outer diameter of the feed rod to a level of 5 mm or less from the viewpoint of forming a shaft portion having sufficient rigidity.

  In recent years, in the field of machine tools such as an automatic lathe, there is an increasing demand for processing a rod with an extremely small diameter (for example, 1 mm or less) with high accuracy by ultra-high speed rotation (for example, about 20000 rpm). Here, for example, in turning, the relative speed between the bar and the tool blade edge (that is, the peripheral speed of the bar) is the same even for bars having different outer diameters in order to maintain the machining conditions for the bar. It is desirable to be constant. That is, the outer diameter of the bar and the rotation speed of the rotary spindle have an inversely proportional relationship, and the rotation speed increases as the bar becomes thinner. As a result, rods with extremely small diameters that cannot retain their own shape against their own weight or centrifugal force tend to run out under ultra-high-speed rotation during turning. There is a concern of causing vibration and damage to the surface of the bar.

  In order to suppress the whirling of the bar during turning, it is necessary to reduce as much as possible the gap between the inner peripheral surface of the bar receiving hole of the rotating spindle and the outer peripheral surface of the bar. The For example, in order to effectively suppress the swinging of a bar with an extremely small diameter of 1 mm or less, it is necessary to form the inner diameter of the bar receiving hole with a small diameter of about 2 mm. Therefore, even for the bar feeder of the automatic bar feeder, such ultra-thin bar is stable without increasing the remaining amount along the bar receiving hole of the rotating main shaft. Must be able to be transported automatically. However, the above-described bar material transfer device disclosed in Patent Document 1 cannot meet such a demand because it is difficult to reduce the outer diameter of the feed rod to an extremely fine level. Furthermore, in consideration of processing various bar materials with different outer diameters with machine tools, the bar material transfer device also has a structure (for example, bar material) that can stably transfer bar materials with different outer diameters individually. However, the rod material transfer device disclosed in Patent Document 1 cannot meet this requirement.

  It is an object of the present invention to provide a rod transfer device for transferring a rod as a work material to a machine tool, along a rod receiving hole of a rotating spindle having a small diameter (for example, about 2 mm). An object of the present invention is to provide a rod transfer device that can stably transfer a rod having a diameter (for example, 1 mm or less) without increasing the remaining amount.

  Another object of the present invention is a bar material transfer device for transferring a bar material as a work material to a machine tool, and has a structure that can stably transfer bar materials having different outer diameters individually. It is to provide a bar material transfer device.

  Still another object of the present invention is to machine a bar with a very small diameter (for example, 1 mm or less), which is stably fed, with a high precision by ultra-high speed rotation (for example, about 20000 rpm) in a machine tool equipped with a bar material transfer device. It is to provide a machine tool that can be used.

  In order to achieve the above-mentioned object, the invention according to claim 1 includes a bar support part having an axis, and a bar support part rotatably supported around the axis, and together with the bar support part along the axis. In the bar transport apparatus including the moving unit that moves, the bar support unit includes a holder that is rotatably connected to the moving unit about the axis, and is held by the frictional force to the holder, and the moving unit along the axis And an extension bar extending in a direction away from the extension bar, and the extension bar has a support surface for supporting the bar at the end thereof.

  According to a second aspect of the present invention, there is provided the bar transfer device according to the first aspect, wherein the bar is transferred over a predetermined transfer distance along the bar receiving hole of the rotary spindle of the machine tool. The material support part extends over a part of the transfer distance, and the extension bar supporting the bar on the support surface is inserted into the bar receiving hole, while the holder is not inserted into the bar receiving hole over the entire transfer distance. Thus, a bar material transfer device having a lengthwise dimension is provided.

  The invention according to claim 3 is the bar material transfer device according to claim 2, further comprising an inner tube that can be installed in the bar material receiving hole of the rotating main shaft, and the inner tube is an extension in which the bar material is supported on the support surface. Provided is a bar transport device that receives a bar and suppresses radial displacement of the bar and the extension bar inside the bar receiving hole.

  According to a fourth aspect of the present invention, in the bar material transfer device according to the third aspect, the rotation main shaft has a chuck for gripping the bar material, and the inner tube has a tip portion that can be disposed in the chuck. A bar material transfer device is provided.

  A fifth aspect of the present invention is the rod material transfer device according to any one of the second to fourth aspects, further comprising a guide member that can be installed between the moving portion and the rotation main shaft, and the guide member is an extension. Provided is a bar transporting device for centering and supporting a bar supported on a support surface of a bar and an extension bar so as to be slidable along an axis.

  A sixth aspect of the present invention is the rod material transfer device according to any one of the first to fifth aspects, wherein the connection is provided between the holder and the moving part and detachably connects the holder to the moving part. Provided is a bar transport device further comprising a structure.

  According to a seventh aspect of the present invention, in the bar material transfer device according to the sixth aspect, the second material can be connected to the moving portion instead of the holder and can hold the bar material having a diameter larger than that of the extension bar by a frictional force. Provided is a bar transport device further comprising a holder.

  The invention according to claim 8 is the bar material transfer device according to any one of claims 1 to 7, wherein the support surface of the extension bar includes a holding surface for holding the bar material by a frictional force. A transfer device is provided.

  Invention of Claim 9 is a machine tool which comprises a rotation main axis | shaft and the bar material transfer apparatus attached to a rotation main axis | shaft, A bar material transfer apparatus is described in any one of Claims 1-8. A machine tool characterized by being a bar material transfer device is provided.

  According to the first aspect of the present invention, since the extension rod is configured to be held by frictional force on the holder that is rotatably connected to the moving portion, there is no need to provide a bearing structure on the extension rod itself, Therefore, the extension rod can be easily reduced in diameter. Therefore, in a machine tool to which the rod material transfer device is applied, the rod of the rotating spindle can be used to perform high-precision machining at an ultrahigh speed (for example, about 20000 rpm) on the rod W having an extremely small diameter (for example, 1 mm or less). Even when the material receiving hole is formed with a small diameter of about 2 mm capable of suppressing the swinging of the bar material, the rod material of the rotating main shaft having such a reduced diameter can be received by the extension rod of the bar material supporting portion. A very thin rod can be stably transferred along the hole without increasing the remaining amount.

  According to the second aspect of the present invention, it is possible to more reliably and stably transfer a very thin rod member along the rod receiving hole of the rotating spindle having a reduced diameter.

  According to the third aspect of the present invention, even if the rotation main shaft has a bar receiving hole that can receive a bar having the maximum diameter set in advance, the internal space of the intubation tube receives the actual bar receiving Since it acts as a hole, it is possible to effectively suppress the whirling of ultra-thin rods and correspondingly elongated extension rods during high-speed rotation, and to further improve machining accuracy by machine tools Can do.

  According to the fourth aspect of the present invention, in order to reduce the remaining amount of the bar to the maximum, even when the extension bar advances to the vicinity of the chuck to transfer the bar, The swinging of the bar and the extension bar can be prevented more reliably.

  According to the fifth aspect of the present invention, it becomes possible to easily insert a very small-diameter rod into the rod receiving hole of the rotation spindle of the machine tool, and during the high-speed rotation of the ultra-fine rod and the extension rod. It is possible to effectively suppress the swinging of the machine tool and further improve the processing accuracy of the machine tool.

  According to invention of Claim 6, according to the change of the outer diameter of the bar object to be transferred, the bar support part including the holder of the corresponding dimension and the extension bar is appropriately exchanged and connected to the moving part. Thus, rods having different outer diameters can be stably transferred individually.

  According to the invention described in claim 7, by connecting the second holder to the moving part instead of the bar support part, an outer diameter (for example, 5 mm or more) that can be stably transferred even by a conventional bar transfer apparatus. ) Can be stably transferred in the same manner while being held in the second holder, so that the versatility of the bar transfer device is expanded.

  According to invention of Claim 8, a bar can be stably hold | maintained by the frictional force on the support surface of an extension bar, without preventing diameter reduction of an extension bar.

  According to the ninth aspect of the present invention, it is possible to process a rod with a very small diameter (for example, 1 mm or less) that is stably fed with high accuracy by ultra-high speed rotation (for example, about 20000 rpm).

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Corresponding components are denoted by common reference symbols throughout the drawings.
Referring to the drawings, FIGS. 1 and 2 are diagrams illustrating a bar transport device 10 according to an embodiment of the present invention, and FIGS. 3 and 4 are one embodiment of the present invention with a bar transport device 10 attached thereto. It is a figure which shows the machine tool.

  The bar material transfer device 10 is a device for transferring a bar material W (FIGS. 2 and 4) as a material to be processed to a machine tool 12 such as an automatic lathe, and a bar material support portion having an axis 14a. 14 and a moving part 16 that supports the bar support 14 so as to be rotatable about the axis 14a in the direction of the arrow α, and moves in the direction of the arrow β along with the bar 14 along the axis 14a. Configured (FIG. 1). The bar material transfer device 10 has a bar material receiving hole 22 (FIG. 3) of the rotary spindle 20 of the machine tool 12 under the guidance of a rail mechanism 18 (FIG. 3) of an automatic bar material feeder attached to the machine tool 12. ), The bar W can be transferred over a predetermined transfer distance.

  As shown in FIG. 1, the bar support portion 14 of the bar transfer device 10 is held by the holder 24 by a friction force and a holder 24 connected to the moving unit 16 so as to be rotatable about the axis 14a. And an extension bar 26 extending in a direction away from the moving part 16, and a support surface 28 for supporting the bar W (FIG. 2) is formed at the end of the extension bar 26. Further, the moving unit 16 is connected to a drive source 30 such as an electric motor via a power transmission mechanism 32 such as a chain / sprocket, and the rod is moved along the rail mechanism 18 (FIG. 3) under the driving force of the drive source 30. It moves linearly together with the material support part 14. The rod material transfer device 10 is an elongated rod shape that can be inserted together with the rod material W into the rod material receiving hole 22 of the rotation spindle 20 for the purpose of reducing the remaining amount of the rod material W fed to the rotation spindle 20 of the machine tool 12. It has the form.

  As shown in FIG. 2, the holder 24 of the bar support 14 includes a bottomed holding hole 34 that is recessed in the center along the axis 14 a, and an outer side along the axis 14 a on the opposite side of the holding hole 34. And a support shaft 36 projecting from the head (FIG. 2A). The holder 24 is configured to be elastically deformable so as to expand the holding hole 34 in the radial direction, and the inner peripheral surface of the holding hole 34 is frictionally engaged with a predetermined length region of the base end of the outer peripheral surface 26 a of the extension rod 26. It functions as a holding surface 34a. The holding hole 34 has an inner diameter slightly smaller than the outer diameter of the extension rod 26 in an unloaded state where the extension rod 26 is not held. Therefore, when the base end predetermined length region of the extension rod 26 is inserted into the holding hole 34 with a predetermined pressing force, the holding hole 34 expands in diameter, and the holding surface 34a becomes the outer peripheral surface 26a of the extension rod 26 under its elastic restoring force. So that the holder 24 holds the extension rod 26 stably and securely by the frictional force. Further, the extension rod 26 can be detached from the holder 24 by applying a tensile force that overcomes the friction force between the two to the front in the axial direction with respect to the extension rod 26 held by the holder 24.

  The extension bar 26 of the bar support portion 14 is a bar-like element that extends linearly along the axis 14a. As will be described later, the extension bar 26 extends into the bar receiving hole 22 of the rotary spindle 20 of the machine tool 12 over the entire length thereof. It has an insertable dimension (FIG. 1). A bottomed recess 38 extending along the axis 14 a is provided at the end of the extension bar 26, and the inner peripheral surface of the recess 38 supports a base end predetermined length region of the bar W. (FIG. 2B). The recess 38 of the extension rod 26 may have a stepped shape for allowing a very thin rod W to be smoothly inserted into the recess 38 as shown in the figure, for example. More specifically, the recess 38 is disposed on the bottom side adjacent to the introduction portion 38a in the axial direction and has an inner diameter slightly larger than the outer diameter of the bar W. A holding portion 38b having an inner diameter substantially equal to the diameter, and a holding surface 39 for stably holding the bar W by frictional force is formed on the inner surface of the holding portion 38b. Alternatively, it is possible to ensure easy introduction and stable support of the bar W by forming the recess 38 in a tapered shape whose inner diameter gradually decreases from the inlet toward the bottom.

  The moving unit 16 includes a bottomed cavity 40 that receives the support shaft 36 of the holder 24 of the bar support 14, and a bearing mechanism 42 for rotatably supporting the holder 24 is installed in the cavity 40. (FIG. 2A). In the illustrated embodiment, the bearing mechanism 42 includes a thrust bearing (ball bearing) 44 installed at the proximal end of the support shaft 36 of the holder 24 and a pair of radial bearings (needle) installed at the longitudinal intermediate portion of the support shaft 36. Bearing) 46. The bearing mechanism 42 stably supports the holder 24 that rotates at high speed around the axis 14 a at the same speed as the rotary spindle 20 of the machine tool 12 by the plurality of bearings 44 and 46.

  As shown in FIG. 3, the bar transport device 10 is configured to move the rotating spindle 20 rearward in the bar feeding direction in a state where the axis 14 a of the bar support 14 matches the axis 20 a of the rotating spindle 20 of the machine tool 12. Is installed at a predetermined position. In the initial state in which the unused bar W (FIG. 4) is supplied to the rotary spindle 20 of the machine tool 12 by the automatic bar feeder, the entire bar support 14 of the bar transport device 10 is rotated. It arrange | positions at the bar material transfer direction back of the main axis | shaft 20. FIG. As the processing of the bar W in the machine tool 12 progresses, the extension bar 26 of the bar support 14 is gradually received in the bar receiving hole 22 of the rotary spindle 20, and finally, for example, FIG. The end position of the predetermined transfer distance as shown in FIG. On the other hand, the holder 24 of the bar support part 14 is arranged behind the rotation main shaft 20 in the bar transfer direction even when the extension bar 26 reaches the end position of the predetermined transfer distance. In other words, the bar transfer device 10 supports the bar W on the support surface 28 over a part of the preset transfer distance with respect to the bar W to be processed in the dimensional relationship with the rotary spindle 20 of the machine tool 12. While the extension rod 26 is inserted into the rod receiving hole 22 of the rotary main shaft 20, the length dimension is set such that the holder 24 is not inserted into the rod receiving hole 22 over the entire transfer distance. The part 16 is configured to have.

  According to the bar transfer device 10 having the above-described configuration, the extension bar 26 formed so as to be inserted into the bar receiving hole 22 of the rotary spindle 20 of the machine tool 12 so as to reduce the remaining amount of the bar W is provided at the end thereof. Since the bar W supported on the support surface 28 is integrally rotatable with respect to the moving portion 16, the inner wall surface of the bar receiving hole 22 of the rotary spindle 20 during turning of the bar W is provided. Even when the extension rod 26 comes into contact with the extension rod 26, vibration generated in the extension rod 26 can be reduced. In addition, since the extension rod 26 is configured to be held by the friction force on the holder 24 that is rotatably connected to the moving portion 16, it is not necessary to provide a bearing structure on the extension rod 26 itself. The diameter can be easily reduced. In particular, in the illustrated embodiment, the support surface 28 at the end of the extension bar 26 includes a holding surface 39 that holds the bar W by frictional force, so that the outer diameter of the extension bar 26 is set to the outside of the bar W. The diameter can be approximated as much as possible. In order to secure the mechanical strength of the extension rod 26 with a reduced diameter, it is advantageous that the extension rod 26 is made of a rigid material such as stainless steel for springs.

  Therefore, in the machine tool 12, the rod receiving hole 22 of the rotary spindle 20 is provided so that high-precision machining can be performed at a very high speed (for example, about 20000 rpm) on the rod W having an extremely small diameter (for example, 1 mm or less). Even in the case where the rod W is formed to have a small diameter of about 2 mm capable of suppressing the swing of the rod W, the rod transfer device 10 is rotated by such an extension by the extension rod 26 of the rod support portion 14. A very thin rod W can be stably transferred along the rod receiving hole 22 of the main shaft 20 without increasing the remaining amount. Such a special effect produced by the rod material transfer device 10 is that the holder 24 of the rod material support portion 14 has the rod of the rotating spindle 20 over the entire transfer distance determined in advance with respect to the rod material W to be transferred. By adopting a configuration in which the material is not inserted into the material receiving hole 22, it becomes more reliable.

  The bar transport apparatus 10 according to the embodiment of the present invention further includes a connection structure 48 provided between the holder 24 of the bar support 14 and the moving unit 16 and detachably connecting the holder 24 to the moving unit 16. be able to. In the illustrated embodiment, the connection structure 48 is formed in the vicinity of the end of the support shaft 36 of the holder 24 in a position near the bottom of the groove 50 formed annularly along the outer peripheral surface and the cavity 40 of the moving part 16. The lateral hole 52 is constituted by a retaining ball 54 that is accommodated in the annular groove 50 of the support shaft 36 of the holder 24 so as to be engageable.

  The lateral hole 52 of the moving part 16 passes through the wall part defining the cavity part 40 in the radial direction and opens outward. A movable lid 56 that opens and closes the outward opening of the lateral hole 52 is provided outside the moving unit 16. The movable lid 56 is in a closed position for closing the outward opening of the lateral hole 52, and holds the retaining ball 54 in a retaining position in which a part thereof protrudes inside the cavity 40, while opening the outward opening of the lateral hole 52. In the open position, the entire retaining ball 54 is allowed to be drawn into the lateral hole 52. Therefore, when the holder 24 is connected to the moving part 16 at an appropriate position, the latching ball 54 is engaged with the annular groove 50 of the support shaft 36 in a rollable manner by arranging the movable lid 56 in the closed position. Thus, it functions as a retainer for the holder 24. Further, when the movable lid 56 is moved to the open position, the engagement between the retaining ball 54 and the annular groove 50 of the support shaft 36 can be released, so that the holder 24 can be detached from the moving portion 16.

  In consideration of processing various bar materials W having different outer diameters in the machine tool 12, the bar material transfer device 10 having such a configuration supports the bar materials W having different outer diameters individually and stably. A plurality of types of extension rods 26 having surfaces 28 (that is, recesses 38) (ie, different outer diameters) and a plurality of types of extension rods 26 that individually hold the plurality of types of extension rods 26 (ie, different inner diameters of the holding holes 34). The holder 24 can be prepared in advance. Then, according to the change of the outer diameter of the bar W to be transferred, the bar support part 14 including the holder 24 and the extension bar 26 having the corresponding dimensions is appropriately exchanged and connected to the moving part 16, Bars W having different diameters can be stably transferred individually.

  The machine tool 12 has a configuration in which the bar transfer device 10 is attached to the rotary spindle 20 in advance, so that the bar W having a very small diameter (for example, 1 mm or less) that is stably fed is rotated at an extremely high speed (for example, about 20000 rpm). Can be processed with high accuracy. Hereinafter, the configuration of the main part of the machine tool 12 according to an embodiment of the present invention will be described with reference to FIGS. 3 and 4. The illustrated machine tool 12 has a configuration of a single-axis automatic lathe provided with a single rotary spindle 20, but a multi-axis automatic lathe provided with a plurality of rotary spindles that can be indexed to a predetermined work position is also available. A bar material transfer device 10 can be attached.

  The rotating spindle 20 of the machine tool (for example, NC lathe) 12 is a hollow cylindrical body having a central axis 20a, and is rotatably mounted on the spindle stock 58 via a plurality of bearings 60. In the illustrated embodiment, a built-in servo motor 62 is incorporated in the spindle stock 58 as a drive source for the rotary spindle 20. The rotation main shaft 20 is concentrically installed at the axial front end (left end in the drawing) region, and concentrically adjacent to the chuck 64 and driven by a drive unit (for example, a piston / cylinder device) 66. And an actuating member 68 for opening and closing the chuck 64. When turning the bar W, the bar-shaped W is moved from the rear end (right end in the figure) of the rotary spindle 20 to the inside of the spindle (that is, the bar receiving hole) by an automatic bar feeder equipped with the bar transfer device 10. 22) is fed in the axial direction, and the rotary spindle 20 rotates at high speed about the axis 20a in a state where the bar W is firmly held by the chuck 64.

  As shown in an enlarged view in FIG. 4, the chuck 64 is a hollow cylindrical body that can receive the bar W supplied to the rotary main shaft 20 therein, and elastically deforms at the axial front end (left end in the figure). A possible grip 70 is provided. A plurality of slits (not shown) are formed in the gripping portion 70 of the chuck 64, thereby giving the gripping portion 70 a structure capable of elastically changing the inner diameter dimension. A substantially cylindrical bar gripping surface 72 is formed on the inner peripheral surface of the gripping portion 70, and a frustoconical pressure receiving surface that gradually increases in diameter toward the front end in the axial direction is formed on the outer peripheral surface of the gripping portion 70. 74 is formed. The gripping portion 70 receives a pressing force inward in the radial direction on the pressure receiving surface 74, so that the bar gripping surface 72 is elastically bent from the initial open position and the diameter of the bar gripping surface 72 is reduced. It can be firmly and securely held. Further, when the pressing force on the pressure receiving surface 74 is released, the gripping portion 70 is elastically restored to the open position, the diameter of the bar gripping surface 72 is expanded, and the bar W is removed from the gripping portion 70 in this state. To be released.

  The chuck 64 further has an abutting surface 76 that extends in an annular shape perpendicular to the central axis 20a of the rotary main shaft 20 adjacent to the large-diameter end (left end in the figure) of the pressure receiving surface 74 of the grip portion 70. On the other hand, an annular cap 80 having a locking surface 78 that can be engaged with the contact surface 76 of the chuck 64 is detachably attached to the front end in the axial direction of the rotating main shaft 20.

  The actuating member 68 is a hollow cylindrical body that is concentrically accommodated in the rotating main shaft 20 while being immovable in the rotating direction and movable in the axial direction with respect to the rotating main shaft 20, and has an internal space penetrating in the axial direction. It functions as a bar material receiving hole 22. In the illustrated embodiment, the actuating member 68 includes a first cylindrical element 68A on the axial front end side that receives the chuck 64 in a concentric arrangement so as to be movable relative to the axial direction, and an axial rear end side connected to the drive unit 66. The second cylindrical element 68B and the third cylindrical element 68C interposed between the first cylindrical element 68A and the second cylindrical element 68B are combined with each other. 68 A of 1st cylindrical elements have the truncated-cone-shaped press surface 82 which can be engaged with the pressure receiving surface 74 of the holding part 70 of the chuck | zipper 64 in the axial direction front end area | region of the internal peripheral surface. A return spring 84 is installed between the first cylindrical element 68A and the chuck 64 to elastically bias the chuck 64 in the direction of pushing out the chuck 64 from the first cylindrical element 68A.

  In the machine tool 12 having the above-described configuration, when the bar W is gripped by the chuck 64 of the rotary spindle 20, the operating member 68 is displaced forward in the axial direction with respect to the chuck 64 by the driving force of the driving unit 66 and pressed. The surface 82 is pressed against the pressure receiving surface 74. At this time, the abutment surface 76 of the chuck 64 abuts on the locking surface 78 of the cap 80, so that the chuck 64 cannot move forward in the axial direction within the rotary main shaft 20. Accordingly, the chuck 64 is elastically deformed by the pressing force applied from the pressing surface 82 of the operating member 68 to the pressure receiving surface 74 so that the inner diameter dimension of the bar gripping surface 72 is reduced. Hold firmly. In this state, the rotary spindle 20 rotates at a high speed, and the bar W is turned by a tool (not shown). During this time, the bar support part 14 of the bar transfer apparatus 10 receives a rotational force from the bar W rotating at a high speed and rotates at a high speed with respect to the moving part 16. And the vibration of the bar W is suppressed by the above-described characteristic configuration of the bar transfer device 10, and the ultra-fine bar W can be turned with high accuracy.

  When one machining step for the bar W is completed and the workpiece is cut off, the driving force of the driving portion 66 is released, and the operating member 68 is axially moved in the rotation main shaft 20 by the elastic biasing force of the return spring 84. Move backwards. Along with this, the pressing force of the chuck 64 on the gripping portion 70 is eliminated, and the gripping portion 70 is elastically restored to increase the inner diameter dimension of the bar gripping surface 72 to release the bar W. In this state, the moving part 16 of the bar material transfer device 10 advances by a predetermined distance, and the bar material W is transferred forward in the axial direction by a length to receive the next processing step. In the present application, as described above, the actuating member 68 that obtains the gripping force of the chuck 64 by moving forward in the axial direction with respect to the chuck 64 within the rotary main shaft 20 is referred to as an “extrusion-type actuating member”. . On the other hand, as will be described later, an operation member of a type that obtains gripping force of the chuck by moving rearward in the axial direction integrally with the chuck within the rotation main shaft is referred to as a “retractable operation member”.

  Incidentally, a machine tool such as an automatic lathe is generally configured to grip and process various bar materials having different outer diameters on a rotary main shaft having a bar receiving hole having the same inner diameter. Therefore, the outer diameter dimension range of the bar material which can be processed is set for each machine tool, and the rotary main shaft having the bar material receiving hole capable of receiving the maximum diameter bar material is mounted in advance. In such a configuration, even if a rod having an extremely small diameter (for example, 1 mm or less) is transferred along the rod receiving hole of the rotation main shaft by the rod transferring apparatus according to the present invention, the outer peripheral surface of the rod and the rod Since the gap with the inner peripheral surface of the receiving hole is large, there is a concern that it is difficult to suppress the swinging of the bar during high-speed rotation.

  In order to cope with such a problem, the bar feeder 10 according to the embodiment of the present invention may further include an inner tube 86 that can be installed in the bar receiving hole 22 of the rotary spindle 20 of the machine tool 12 (FIGS. 3 to 3). (See FIG. 5). In this case, the inner tube 86 has an axial through hole 88 having an inner diameter slightly larger than the outer diameter of the bar W and the extension bar 26, and the through hole 88 is connected to the axis 14 a of the bar support portion 14 and the rotation main shaft. In the state of being concentrically arranged on both of the 20 axis lines 20 a, the extension bar 26 that supports the bar W is received on the support surface 28, and the diameters of the bar W and the extension bar 26 inside the bar receiving hole 22 are received. Suppress directional displacement.

  According to such a configuration, even if the rotation main shaft 20 has the rod receiving hole 22 capable of receiving a rod with the maximum diameter set in advance, the diameter is reduced in accordance with the outer diameter of the rod W. Since the axial through hole 88 of the inner tube 86 that can be used acts as an actual bar receiving hole, the bar W having an extremely small diameter (for example, 1 mm or less) and the extension bar 26 that has been correspondingly reduced in diameter can be rotated at high speed. The inside whirling can be effectively suppressed. If the whirling of the bar W can be suppressed, not only can the vibration of the rotating spindle 20 and the damage to the surface of the bar W be prevented, but also the movement amount of the moving unit 16 of the bar transfer device 10 can be controlled with high accuracy. Therefore, the processing accuracy by the machine tool 12 can be further improved.

  In particular, in the case where the bar material transfer device 10 is applied to a machine tool 12 having a rotating spindle 20 having a bar material receiving hole 22 having a general inner diameter, the outer diameter of the bar material W is, for example, 1. When it becomes 5 mm or less, the installation of the inner intubation 86 works extremely effectively. In addition, a plurality of types of inner intubation tubes 86 having different inner diameters are prepared so that the outer diameter of the bar W to be transferred can be changed, and the inner intubation tube 86 can be appropriately replaced according to the outer diameter of the bar W. Anyway. In general, an inner tube 86 having an inner diameter of about 2 mm is used for a rod W (for example, an unused length of about 2.5 m) made of a free-cutting steel material or a brass material with an extremely small diameter (for example, about 1 mm or less). Although it is assumed to be used, depending on the material (for example, resin material) of the bar W, it may be advantageous to use the inner tube 86 regardless of the thickness of the bar W.

  More specifically with respect to the illustrated embodiment, the inner tube 86 is installed concentrically in the bar receiving hole 22 of the actuating member 68 installed on the rotary spindle 20 using a plurality (three in the figure) of spacers 90. The The spacers 90 are made of, for example, an annular element, and are fixed to a predetermined position on the outer peripheral surface of the inner intubation 86 by, for example, brazing. In the illustrated embodiment, a spacer 90 is provided in each of the first to third cylindrical elements 68 </ b> A to 68 </ b> C of the operating member 68, and the spacer 90 stably centers the intubation tube 86 with respect to the operating member 68. To support. Such a configuration is adapted to a combination structure that is specific to the above-described extrusion-type actuating member 68 in the machine tool 12 and that is capable of relative displacement in the axial direction of the first to third cylindrical elements 68A to 68C.

  In this case, as shown in FIG. 6, the inner tube 86 is fixed to the actuating member 68 on the shoulder surface 22a formed in the bar receiving hole 22 in the vicinity of the rear end of the second tubular element 68B. A nut 90 that abuts the front end surface 90a of the spacer 90 provided in the inner wall 68B and engages with the rear end surface 90b of the spacer 90 in the female thread portion 22b provided in the bar material receiving hole 22 behind the shoulder surface 22a. This can be ensured by screwing 92. In this configuration, if the nut 92 is detached from the second cylindrical element 68B, the inner insertion tube 86 can be pulled out together with the spacer 90 from the rod receiving hole 22 in the axial direction rearward. In order to facilitate the insertion of the inner tube 86 into the bar receiving hole 22, the outer diameters of the plurality of spacers 90 are sequentially changed from those arranged rearward in the axial direction to those arranged forward in the axial direction. It is advantageous to reduce the inner diameters of the plurality of seating surfaces 22c of the bar material receiving holes 22 that receive the spacers 90 sequentially forward in the axial direction corresponding to the spacers 90 (FIGS. 4 and 6).

  4 and FIG. 5, the axially forward end of the inner tube 86 is disposed behind the first cylindrical element 68A of the actuating member 68 that houses the chuck 64 and the return spring 84, and the third cylindrical element 68C. Are supported via spacers 90. On the other hand, as shown in FIG. 7, the inner intubation tube 86 may be configured to have a tip portion 86 a that can be disposed in the chuck 64 installed on the rotary spindle 20 of the machine tool 12. In this configuration, the intubation tube 86 extends axially forward from the spacer 90 provided in the third cylindrical element 68C, and the distal end portion 86a thereof extends into the internal space of the first cylindrical element 68A and the chuck 64. Inserted. With such a configuration, in order to reduce the remaining amount of the bar W to the maximum, even when the extension bar 26 moves forward to transfer the bar W to the vicinity of the gripping portion 70 of the chuck 64, The swinging of the bar W and the extension bar 26 during high-speed rotation can be more reliably prevented.

  The rod material transfer device 10 according to the embodiment of the present invention may further include a guide member 94 that can be installed between the moving unit 16 and the rotary main shaft 20 of the machine tool 12 (see FIGS. 3 and 8). In this case, the guide member 94 has an axial through hole 96 having an inner diameter slightly larger than the outer diameters of the bar W and the extension bar 26, and the through hole 96 serves as an axis of the bar support 14 and the rotary spindle 20. In a state of being arranged concentrically with 14a and 20a, the extension rod 26 and the rod W supported on the support surface 28 of the extension rod 26 are centered and supported so as to be slidable along the axis 14a of the rod support portion 14. . With such a configuration, it becomes possible to easily insert a rod W having a very small diameter (for example, 1 mm or less) into the rod receiving hole 22 (particularly, the through hole 88 of the inner tube 86) of the rotary spindle 20 of the machine tool 12, Further, it is possible to effectively suppress the swinging of the ultra-thin rod member W and the extension rod 26 during high-speed rotation, thereby further improving the processing accuracy of the machine tool 12.

  More specifically with respect to the illustrated embodiment, the guide member 94 is aligned with the axis 14a of the bar support 14 on the base 98 (FIG. 3) disposed in front of the rail mechanism 18 of the bar automatic feeder. It is installed so that it can rotate around the axis line. Further, another guide member 94 is also installed on the headstock 58 of the machine tool 12 at a position rearward of the rotary spindle 20 so as to be rotatable about an axis line that coincides with the axis line 20 of the rotary spindle 20. Each guide member 94 has a tapered guide surface 100 that gradually increases in diameter toward the rear end in the axial rear end region of the through hole 96.

  In addition, when adopting the configuration in which the above-described inner tube 86 is installed in the bar receiving hole 22 of the rotary spindle 20 of the machine tool 12, the guide member 94 installed on the spindle base 58 is detachable from the spindle base 58. Advantageously, it is supported by a mounting member 102 to be mounted. In addition, when the machine tool 12 has a machine configuration capable of moving the headstock 58 in a direction parallel to the axis 20a of the rotary spindle 20, the guide member 94 installed on the base 98 (FIG. 3) is provided with the headstock 58. The guide member 94 is disposed at a distance that allows the spindle stock 58 to move. The maximum travel distance of the headstock 58 varies depending on the machine configuration of the machine tool 12, and is, for example, 150 mm to 300 mm.

  The bar transfer device 10 according to the embodiment of the present invention may further include a second holder 104 that can be connected to the moving unit 16 instead of the holder 24 of the bar support 14 (see FIG. 9). In this case, the second holder 104 includes a bottomed holding hole 106 that can hold a bar W ′ having a diameter larger than that of the extension bar 26 by a frictional force. According to such a configuration, by connecting the second holder 104 to the moving part 16 instead of the bar support part 14, the outer diameter (for example, 5 mm or more) that can be stably transferred even by a conventional bar transfer apparatus. ) Can be stably transferred in the same manner while being held in the second holder 104, so that the versatility of the bar transfer device 10 is expanded.

  More specifically with respect to the illustrated embodiment, the second holder 104 has substantially the same size and shape as the holder 24 of the bar support portion 14 except for the inner diameter of the holding hole 106, and supports the holder 24. It is detachably connected to the moving part 16 via a support shaft 108 having the same structure as the shaft 36. When the bar holder 10 is equipped with the second holder 104, in the machine tool 12, the above-described inner tube 86 is not installed in the bar receiving hole 22 of the rotary spindle 20, and the large diameter bar W A chuck 64 ′ (FIG. 10) capable of firmly holding ′ is mounted on the rotary spindle 20. Further, the above-described guide member 94 is not installed on the head stock 58, but instead, a fixed guide member 94 ′ (FIG. 9) capable of guiding the large-diameter bar W ′ is attached to the head stock 58. In this state, the bar material transfer device 10 moves forward in the axial direction, whereby the bar material W ′ is transferred forward along the bar material receiving hole 22 of the rotary main shaft 20.

  Here, the bar receiving hole 22 of the rotary spindle 20 of the machine tool 12 is configured to have an inner diameter capable of receiving the second holder 104 and the moving unit 16 of the bar transfer device 10. Therefore, as the processing of the bar W ′ in the machine tool 12 progresses, the second holder 104 and the moving unit 16 of the bar transfer device 10 are gradually received in the bar receiving hole 22 of the rotary spindle 20, Finally, the terminal position of a predetermined transfer distance as shown in FIG. 10 is reached. As shown in the figure, the second holder 104 and the moving part 16 of the bar material transfer device 10 have dimensions that cannot enter the first cylindrical element 68A of the operating member 68 provided in the rotary main shaft 20. Therefore, the remaining amount of the bar W ′ is increased as compared with the above-described configuration (see, for example, FIG. 4) in which the bar W is supported by the bar support 14 (the holder 24 and the extension bar 26).

  The bar material transfer device according to the present invention is applicable not only to the machine tool 12 provided with the above-described extrusion-type operation member 68 but also to a machine tool provided with a retractable-type operation member. Hereinafter, with reference to FIGS. 11 to 13, the configuration of the machine tool 110 according to the second embodiment of the present invention provided with such a retractable type operating member will be described in relation to the configuration of the bar transfer device 10. To do. The machine tool 110 is substantially the same as the machine tool 12 described above, except that the machine tool 110 includes a retractable operation member that obtains the gripping force of the chuck by moving backward in the axial direction integrally with the chuck within the rotation main shaft. Therefore, corresponding constituent elements are denoted by common reference numerals and description thereof is omitted.

  A rotation spindle 112 of a machine tool (for example, an NC lathe) 110 is a hollow cylindrical body having a central axis 112a, and is rotatably mounted on the spindle stock 58 via a plurality of bearings 60. The rotation main shaft 112 is concentrically installed in the axial front end (left end in the drawing) region, concentrically adjacent to the chuck 114, and driven by a drive unit (for example, a piston / cylinder device) 66. And an actuating member 116 for opening and closing the chuck 114. When turning the bar W, the bar W is fed into the main shaft in the axial direction from the rear end (right end in the figure) of the rotary spindle 112 by an automatic bar feeder equipped with the bar transfer device 10. Then, the rotation main shaft 112 rotates at high speed about the axis 112a while the bar W is firmly held by the chuck 114.

  As shown in an enlarged view in FIG. 12, the chuck 114 is a hollow cylindrical body that can receive the bar W supplied to the rotating main shaft 112 therein, and elastically deforms at the axial front end (left end in the figure). A possible grip 118 is provided. A plurality of slits (not shown) are formed in the grip portion 118 of the chuck 114, thereby giving the grip portion 118 a structure capable of elastically changing the inner diameter dimension. A substantially cylindrical bar gripping surface 120 is formed on the inner peripheral surface of the gripping portion 118, and a frustoconical pressure receiving surface that gradually increases in diameter toward the front end in the axial direction is formed on the outer peripheral surface of the gripping portion 118. 122 is formed. The gripping portion 118 receives a pressing force inward in the radial direction on the pressure receiving surface 122, so that the bar gripping surface 120 is elastically bent from the initial open position, and the bar gripping surface 120 is reduced in diameter. It can be firmly and securely held. Further, when the pressing force on the pressure receiving surface 122 is released, the gripping portion 118 is elastically restored to the open position and the bar gripping surface 120 is expanded in diameter, and the bar W is moved from the gripping portion 118 in this state. To be released.

  A frustoconical pressing surface 124 that can be engaged with the pressure receiving surface 122 of the grip portion 118 of the chuck 114 is formed in the front end region in the axial direction of the inner peripheral surface of the rotation main shaft 112. Further, a rotation stopper having a known structure is provided between the rotation main shaft 112 and the chuck 114 so that the chuck 114 and the operation member 116 rotate integrally with the rotation main shaft 112.

  The actuating member 116 is a hollow cylindrical body that is concentrically accommodated in the rotating main shaft 112 while being immovable in the rotating direction and movable in the axial direction with respect to the rotating main shaft 112, and has an internal space penetrating in the axial direction. It functions as a bar material receiving hole 22. In the illustrated embodiment, the actuating member 116 includes a first cylindrical element 116 </ b> A on the axial front end side that is fixedly connected to the axial rear end of the chuck 114 in a concentric arrangement, and an axial rear end connected to the drive unit 66. The second tubular element 116B on the end side is configured to be fixedly combined with each other.

  In the machine tool 110 having the above-described configuration, when the bar W is gripped by the chuck 114 of the rotary main shaft 112, the operation member 116 is displaced rearward in the axial direction integrally with the chuck 114 by the driving force of the driving unit 66. Then, the pressure receiving surface 122 of the chuck 114 is pressed against the pressing surface 124 of the rotating main shaft 112. As a result, the chuck 114 is elastically deformed by the pressing force applied to the pressure receiving surface 122 from the pressing surface 124 of the rotating spindle 112 so that the inner diameter dimension of the bar holding surface 120 is reduced, and the bar Hold W firmly. In this state, the rotary spindle 112 rotates at a high speed, and the bar W is turned by a tool (not shown). During this time, the bar support part 14 of the bar transfer apparatus 10 receives a rotational force from the bar W rotating at a high speed and rotates at a high speed with respect to the moving part 16. And the vibration of the bar W is suppressed by the above-described characteristic configuration of the bar transfer device 10, and the ultra-fine bar W can be turned with high accuracy.

  When one machining step for the bar W is completed and the workpiece is cut off, the drive unit 66 is driven in the reverse direction, and the operating member 116 moves integrally with the chuck 114 in the axial direction in the rotation main shaft 112. . Along with this, the pressing force of the chuck 114 on the gripping portion 118 is removed, and the gripping portion 118 is elastically restored so as to increase the inner diameter dimension of the bar material gripping surface 120 to release the bar material W. In this state, the moving part 16 of the bar material transfer device 10 advances by a predetermined distance, and the bar material W is transferred forward in the axial direction by a length to receive the next processing step.

  In the machine tool 110 having the above-described configuration, when the rod material transfer device 10 includes the above-described inner tube 86, the inner tube 86 has the through hole 88 through the axis 14 a of the rod material support portion 14 and the axis of the rotary main shaft 112. A plurality of (two in the figure) spacers 90 are fixedly installed in the bar receiving holes 22 of the operating member 116 installed on the rotation main shaft 112 in a state of being concentrically arranged on both of the 112a. In this case, each spacer 90 can be integrally formed with the inner intubation 86 in advance as shown.

  An annular contact member 126 is fixedly provided in the first cylindrical element 116 </ b> A of the operating member 116 adjacent to the rear end of the chuck 114. The inner tube 86 is held concentrically by the actuating member 116 when the spacer 90 at the front end in the axial direction is brought into contact with the contact member 126 in a state where complementary conical surfaces are in close contact with each other as shown in the figure. In this state, similarly to the machine tool 12 described above, the inner tube 86 is fixed to the operating member 116 by screwing the nut 92 to the rear end of the second cylindrical element 116B. Furthermore, as shown in FIG. 13, an internal intubation tube 86 having a distal end portion 86 a that can be disposed in the chuck 114 can be provided in the operation member 116.

It is a front view of the bar material transfer apparatus by one Embodiment of this invention, Comprising: The length direction dimension of an extension bar is reduced and shown. It is the figure which expands and shows the principal part of the bar | burr material transfer apparatus of FIG. 1, (a) The fragmentary sectional view of a holder and a moving part, (b) The fragmentary sectional view of an extension rod. It is sectional drawing of the machine tool by one Embodiment of this invention which attached the bar | burr material transfer apparatus of FIG. It is an expanded sectional view of the principal part of the machine tool of FIG. It is sectional drawing of the internal intubation which the bar | burr material transfer apparatus of FIG. 1 has. It is an expanded sectional view of the principal part of the machine tool of FIG. It is an expanded sectional view of the principal part of the machine tool of FIG. 3, and shows the modification of an intubation. It is sectional drawing which shows the guide member which the bar material transfer apparatus of FIG. 1 has with a part of machine tool. It is sectional drawing which shows the modification of the bar | burr material transfer apparatus of FIG. 1 with a part of machine tool. It is an expanded sectional view of the principal part of the machine tool to which the bar material transfer apparatus of FIG. 9 is applied. It is sectional drawing of the machine tool by other embodiment of this invention which attached the bar | burr material transfer apparatus of FIG. It is an expanded sectional view of the principal part of the machine tool of FIG. It is an expanded sectional view of the principal part of the machine tool of FIG. 11, and shows the modification of an intubation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Bar material transfer device 12,110 Machine tool 14 Bar material support part 16 Moving part 20, 112 Rotation main shaft 22 Bar material receiving hole 24 Holder 26 Extension bar 28 Support surface 39 Holding surface 48 Connection structure 64, 114 Chuck 68, 116 Operation Member 86 Intubation 90 Spacer 94 Guide member 104 Second holder

Claims (9)

In a bar transport device comprising: a bar support part having an axis; and a moving part that rotatably supports the bar support part around the axis and moves with the bar support part along the axis. ,
The bar support part is
A holder coupled to the moving part so as to be rotatable about the axis;
An extension bar held by the frictional force on the holder and extending in a direction away from the moving part along the axis,
The extension bar has a support surface for supporting the bar at its end;
A bar transport device characterized by the above.   2. The bar support device according to claim 1, wherein the bar support is configured to transfer the bar over a predetermined transfer distance along the bar receiving hole of the rotation spindle of the machine tool. The extension bar supporting the bar on the support surface is inserted into the bar receiving hole while the holder is not inserted into the bar receiving hole over the entire transfer distance. The bar material transfer device according to claim 1, which has a lengthwise dimension.   The tube further includes an inner tube that can be installed in the bar receiving hole of the rotating main shaft, the inner tube receiving the extension bar that supports the bar on the support surface, and the inner tube in the bar receiving hole. The bar material transfer device according to claim 2, wherein radial displacement of the bar material and the extension bar is suppressed.   The bar rotating apparatus according to claim 3, wherein the rotation main shaft has a chuck for gripping a bar, and the inner tube has a tip portion that can be disposed in the chuck.   The guide member further includes a guide member that can be installed between the moving portion and the rotation main shaft, and the guide member slides the extension rod and the bar supported on the support surface of the extension rod along the axis. The bar material transfer device according to any one of claims 2 to 4, wherein the bar material transfer device is movably centered and supported.   The bar material transfer device according to any one of claims 1 to 5, further comprising a connection structure that is provided between the holder and the moving unit and detachably connects the holder to the moving unit.   The bar transport apparatus according to claim 6, further comprising a second holder that can be connected to the moving unit instead of the holder and can hold a bar having a diameter larger than that of the extension bar by a frictional force.   The bar material transfer device according to claim 1, wherein the support surface of the extension bar includes a holding surface that holds the bar material by a frictional force. In a machine tool comprising a rotating spindle and a bar material transfer device attached to the rotating spindle,
A machine tool, wherein the bar material transfer device is the bar material transfer device according to any one of claims 1 to 8.

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