Tool holder and machine tool

Abstract

Provided are a tool holder to which a plurality of cutting tools can be attached and which can suppress the occurrence of interference between the cutting tools and a workpiece, and a machine tool.　A tool holder according to the present disclosure can be attached to a rotating tool post. The tool holder comprises: a first attachment portion to which a first cutting tool is attached, and which is provided on one side in a Z-axis direction parallel to the axis of rotation of the tool post in a state in which the tool holder is attached to the tool post; and a second attachment portion to which a second cutting tool is attached and which is provided on the other side in the Z-axis direction. The tool holder 23 holds the first cutting tool at a position offset from the second cutting tool in a Y-axis direction orthogonal to the Z-axis direction.

Description

Tool Holder and Machine Tool

[0001] The present disclosure relates to a tool holder attached to a rotary tool post and a machine tool.

[0002] Conventionally, there is a tool holder that holds a cutting tool for a rotary tool post. Patent Document 1 below describes a tool holder in which a cutting tool is inserted into a tool insertion hole and the inserted cutting tool is held with respect to the tool post.

[0003] Japanese Patent Application Laid-Open No. 2023-136201

[0004] The development of cutting tools is progressing day by day, and a variety of cutting tools have been developed. When the number of cutting tools used for machining a workpiece is greater than the number of cutting tools that can be attached to the tool post, it becomes necessary to replace the cutting tool during machining. Therefore, if a plurality of cutting tools can be attached to one tool holder, the number of cutting tools that can be attached to the tool post can be increased. However, when a plurality of cutting tools are attached to one tool holder, there is a risk that other cutting tools may interfere with the workpiece during machining with an arbitrary cutting tool.

[0005] The present disclosure has been made in view of the above problems, and an object thereof is to provide a tool holder and a machine tool that can attach a plurality of cutting tools and suppress the occurrence of interference between the cutting tool and the workpiece.

[0006] In order to solve the above problems, this specification discloses a tool holder that can be attached to a rotating tool post, and in a state where the tool holder is attached to the tool post, a first attachment portion provided on one side in the Z-axis direction parallel to the rotation axis of the tool post, to which a first cutting tool is attached, and a second attachment portion provided on the other side in the Z-axis direction, to which a second cutting tool is attached, and holds the first cutting tool at a position offset from the second cutting tool in the Y-axis direction orthogonal to the Z-axis direction.

[0007] According to the tool holder and the machine tool of the present disclosure, a plurality of cutting tools can be attached, and the occurrence of interference between the cutting tool and the workpiece can be suppressed.

[0008] A perspective view of a machine tool according to the first embodiment. A side view of a machine tool according to the first embodiment. A block diagram of a machine tool according to the first embodiment. An enlarged view of the portion of the turret device according to the first embodiment in which the tool post is provided. An exploded perspective view showing the first cutting tool removed from the tool holder according to the first embodiment. A plan view of the tool holder according to the first embodiment, viewed from the outer circumferential surface. A side view of the tool post and tool holder according to the first embodiment, viewed from one side in the Y-axis direction, showing the tool holder positioned in the indexing position. A plan view of the tool holder of a comparative example, viewed from the outer circumferential surface. A plan view of the tool holder according to the second embodiment, viewed from the outer circumferential surface. A plan view of the tool holder according to the third embodiment, viewed from the outer circumferential surface.

[0009] (First Embodiment) Hereinafter, a tool holder 23, which is an embodiment of the tool holder of the present disclosure, will be described with reference to the drawings. Figure 1 shows a perspective view of the machine tool 10 according to the first embodiment. Figure 2 shows a side view of the machine tool 10 as seen from the workpiece spindle device 12 side in the Z-axis direction. Figure 3 shows a block diagram of the machine tool 10. Note that Figure 1 shows the machine tool 10 with the device cover and the gripping device of the workpiece spindle device 12 removed. Also, Figure 2 shows the turret device 13 with the tool post 21 and part of the cover of the turret device 13 removed. In the following description, the machine tool 10 will be described based on the view from the front.

[0010] As shown in Figures 1 to 3, the machine tool 10 is a so-called NC lathe and includes a bed 11, a workpiece spindle device 12, a turret device 13, a slide device 14, an auxiliary device 15, an operation panel 16 (see Figure 3), and a control device 17 (see Figure 3). The bed 11 is a slant-type bed having a guide surface 11A that is inclined toward the chip collection section (not shown) in front of the device.

[0011] The workpiece spindle unit 12 is located on the left side of the machine tool 10 and can be fitted with a gripping device (not shown) for gripping a workpiece. The workpiece spindle unit 12 performs the operation of driving the gripping device to grip the workpiece and the operation of releasing the workpiece. The workpiece spindle unit 12 rotates the workpiece gripped by the gripping device around the spindle which is in the machine width direction. As the gripping device, for example, a configuration in which the workpiece is gripped with multiple claws or a collet chuck can be used. The turret unit 13 is located on the right side of the machine tool 10 and performs machining on the workpiece gripped by the workpiece spindle unit 12 using a cutting tool 22 attached to the tool post 21. The cutting tool 22 is for example, a cutting tool or a rotary tool. As will be described later, the tool post 21 can be fitted with a tool holder 23, and the tool holder 23 can hold multiple cutting tools 22. The tool post 21 can also be fitted with a tool holder of a different type than the tool holder 23 described later.

[0012] In the following explanation, as shown in Figures 1 and 2, the direction along the spindle of the workpiece spindle device 12 will be referred to as the Z-axis direction, the direction perpendicular to the Z-axis direction and along the guide surface 11A of the bed 11 that moves the turret device 13 will be referred to as the X-axis direction, and the direction perpendicular to the X-axis direction and the Z-axis direction will be referred to as the Y-axis direction. Also, for convenience of explanation, the direction in which the machine width direction is horizontal to the mounting surface of the device, based on the view of the machine tool 10 from the front, will be referred to as the left-right direction.

[0013] Each device, such as the workpiece spindle unit 12 and the turret unit 13, is mounted on a bed 11 that serves as the base, and is covered by a device cover (not shown in the illustration). This device cover is equipped with a sliding door for accessing the machining chamber and an operation panel 16. The user can change the workpiece and cutting tools 22 by opening and closing the sliding door. The operation panel 16 is a user interface and includes, for example, a touch panel and operating switches.

[0014] The sliding device 14 is a device that slides the turret device 13 in the X, Y, and Z axes. The sliding device 14 includes an X-axis sliding device 25, a Y-axis sliding device 26, and a Z-axis sliding device 27. The Z-axis sliding device 27 is, for example, equipped with a ball screw mechanism, and rotates a screw shaft using a Z-axis motor 27A located on the left side of the machine tool 10, causing a Z-axis slider 27B attached to the screw shaft to slide in the Z-axis direction. The Z-axis motor 27A is, for example, a servo motor. The control device 17 can move the Z-axis slider 27B to any position in the Z-axis direction by controlling the Z-axis sliding device 27.

[0015] The X-axis slide device 25 is mounted on the Z-axis slider 27B and, like the Z-axis slide device 27, is equipped with a ball screw mechanism. The X-axis slide device 25 drives the X-axis motor 25A, which is located at the rear of the machine tool 10, to slide the X-axis slider (not shown) in the X-axis direction.

[0016] Similarly, the Y-axis slide device 26 is mounted on the X-axis slider and is equipped with a ball screw mechanism. The Y-axis slide device 26 slides the Y-axis slider 26B using a Y-axis motor 26A located on the upper part of the machine tool 10. The Y-axis slide device 26 slides the Y-axis slider 26B along the vertical direction which is perpendicular to the mounting surface on which the machine tool 10 is installed. Therefore, as shown in Figure 2, the sliding direction of the Y-axis slider 26B is the direction in which the angle between it and the X-axis direction, which is the sliding direction of the X-axis slider, is 45 degrees (hereinafter referred to as the Yt direction).

[0017] A turret device 13 is attached to the Y-axis slider 26B. The control device 17 controls the X-axis slide device 25, the Y-axis slide device 26, and the Z-axis slide device 27 to move the turret device 13 to any position in each of the XYZ axes. This allows the control device 17 to move the cutting tool 22, which has been indexed to the indexing position, to any position in each of the XYZ axes. In this embodiment, when the control device 17 moves the turret device 13 in the Y-axis direction, it drives both the X-axis slide device 25 and the Y-axis slide device 26, and slides the turret device 13 in the Y-axis direction by combining the amount of movement in the X-axis direction and the amount of movement in the Yt direction.

[0018] The auxiliary device 15 is positioned opposite the workpiece spindle device 12 in the Z-axis direction. The auxiliary device 15 includes, for example, a ball screw mechanism for sliding in the Z-axis direction. The auxiliary device 15 can be fitted with a tailstock device that pushes the workpiece from the opposite side of the gripping device of the workpiece spindle device 12, or a gripping mechanism that grips the workpiece separately from the workpiece spindle device 12.

[0019] Furthermore, as shown in Figure 3, the control device 17 includes a numerical control device 31 and a PLC 32. The numerical control device 31 includes a CPU 33 and a storage device 34. The storage device 34 includes, for example, RAM, ROM, flash memory, HDD, etc. Note that the configuration of the storage device 34 is not limited to the above configuration, and may include an SSD instead of an HDD, for example.

[0020] Furthermore, the machine tool 10 includes a control device 17 and a plurality of drive circuits 20 that connect each of the above-mentioned devices (work spindle device 12, turret device 13, slide device 14, auxiliary device 15, and control panel 16). The numerical control device 31 can control each device via the drive circuits 20 by executing an NC program 35 stored in the storage device 34 using the CPU 33. The drive circuits 20 are, for example, driver circuits (servo amplifiers). The PLC 32 is a Programmable Logic Controller. The PLC 32 executes, for example, a ladder program and processes signals from sensors and the like using a ladder circuit. The PLC 32 is connected to the numerical control device 31 via a communication bus 37 and performs signal input and output with the numerical control device 31.

[0021] (Regarding the tool holder 23) Next, the tool holder 23 will be described. Figure 4 is an enlarged view of the part of the turret device 13 where the tool post 21 is provided, showing the state in which the tool holder 23 is attached. As shown in Figures 1 and 4, the turret device 13 has a tool post 21 that is, for example, a roughly regular dodecagonal prism. Twelve side surfaces of the tool post 21 are provided with holder mounting parts 41 to which cutting tools 22 and tool holders 23 can be attached. Figure 4 shows the state in which the tool holder 23 is attached to one of the twelve holder mounting parts 41.

[0022] The turret device 13 includes a shaft portion 43 that supports the tool post 21. The shaft portion 43 has a cylindrical shape aligned in a direction parallel to the Z-axis direction and is rotatably supported relative to the main body of the turret device 13. The turret device 13 also has a turret motor 13A (see Figure 3) that rotates the tool post 21. The turret device 13 drives the turret motor 13A based on the control of the control device 17, and rotates the shaft portion 43, thereby rotating the tool post 21 around a rotation axis parallel to the Z-axis direction. By rotating the tool post 21, the turret device 13 switches the cutting tool 22 used to process the workpiece. Figure 4 shows the state in which the tool holder 23 is positioned at the indexing position, which is the position where the cutting tool 22 used to process the workpiece is indexed. In the following description of the tool holder 23, the description will be based on the state in which the tool holder 23 is positioned at the indexing position.

[0023] Each of the multiple holder mounting sections 41 is provided with multiple threaded sections 44 into which bolts are screwed. The tool holder 23 is attached to the holder mounting section 41 via a spacer 45 that adjusts the position of the cutting tool 22 in the X-axis direction. The spacer 45 is fixed to the holder mounting section 41 by screwing bolts into the threaded sections 44.

[0024] The tool holder 23 is a metal component and has a base portion 51, an arm portion 52, and a tool holding portion 53. The base portion 51 is a thin plate in the X-axis direction and is fixed to the spacer 45 by bolts 54. The arm portion 52 extends from the base portion 51 radially outward along the X-axis direction from the tool post 21. The tip of the arm portion 52 is provided with the tool holding portion 53.

[0025] The tool holder 53 has a predetermined thickness in the X-axis direction and is substantially plate-shaped, extending in the Y-axis and Z-axis directions. The tool holder 53 has, for example, two first mounting portions 55A and 55B and two second mounting portions 55C and 55D. A cutting tool 22 is detachably attached to each of the first and second mounting portions 55A to 55D. In the following description, the cutting tools 22 attached to each of the first and second mounting portions 55A to 55D will be referred to in this order as the first cutting tool 22A, the first cutting tool 22B, the second cutting tool 22C, and the second cutting tool 22D. Also, when referring to all cutting tools collectively, they will be written as cutting tool 22.

[0026] Each of the first and second cutting tools 22A to 22D is, for example, a tool that meets the specifications of a so-called quick-change mechanism, and is a cutting tool having a tip 58 and a tool mounting portion 59 to which the tip 58 is fixed. As the specifications of the quick-change mechanism, for example, the CAPTO (registered trademark) specifications can be adopted. However, as the specifications of the quick-change mechanism, other specifications such as BT shank, BBT shank, and HSK shank may be adopted, not limited to the CAPTO (registered trademark) specifications. The tips 58 of each of the first and second cutting tools 22A to 22D will be referred to in this order as tips 58A, 58B, 58C, and 58D. Also, the tool mounting portions 59 of each of the first and second cutting tools 22A to 22D will be referred to in this order as tool mounting portions 59A, 59B, 59C, and 59D. The first and second mounting portions 55A to 55D have the same configuration, although their positions and orientations differ. Furthermore, the first and second cutting tools 22A to 22D have the same structure for attaching to their respective mounting parts. For this reason, the following description will mainly focus on the first mounting part 55A and the first cutting tool 22A, and descriptions of the other mounting parts and cutting tools will be omitted as appropriate.

[0027] Furthermore, the first and second cutting tools 22A to 22D can be throwaway cutting tools, brazed cutting tools, solid cutting tools, etc. Also, the first and second cutting tools 22A to 22D are not limited to cutting tools, but may also be drilling tools such as drills that meet the specifications for a quick change mechanism. Also, the first and second cutting tools 22A to 22D are not limited to tools that meet the specifications for a quick change mechanism, but may also be configured in which a clamp or wedge-shaped liner is inserted into a groove to fix the shank (shank portion). Therefore, various cutting tools that can be attached to the tool holder 23 can be used as cutting tools in this disclosure. Also, the first and second mounting parts 55A to 55D may have different configurations from each other. Therefore, the first and second cutting tools 22A to 22D may also have different configurations from each other.

[0028] Figure 5 shows the first cutting tools 22A and 22B removed from the tool holder 23. Note that Figure 5 shows second cutting tools 22C and 22D of a different type than those in Figure 4. As shown in Figure 5, the first cutting tool 22A has a tool mounting portion 59A to which the tip 58A is attached, a substantially cylindrical flange portion 62, and a shank portion 63. The tip 58A is attached to the tip of the tool mounting portion 59A, and the flange portion 62 is provided at the base end of the tool mounting portion 59A. The shank portion 63 is provided on the base end side surface of the flange portion 62.

[0029] Furthermore, the first mounting portion 55A has an insertion hole 65, a sleeve 66, a locking mechanism 67, and a locking bolt 68. The insertion hole 65 is formed in the tool holding portion 53 along a direction parallel to the Z-axis direction. The tool holding portion 53 has openings for the insertion hole 65 formed in a pair of opposing end faces 53A and 53B in the Z-axis direction. In the case of Figure 5, the front end face 53A has two openings for the insertion hole 65, each of the first mounting portions 55A and 55B. The rear end face 53B has two openings for the insertion hole 65, each of the second mounting portions 55C and 55D.

[0030] A sleeve 66 is attached to the opening of each insertion hole 65. The sleeve 66 is attached to the insertion hole 65 with a portion of it inserted into the hole. The sleeve 66 has a plate-like portion that surrounds the opening of the insertion hole 65, and this plate-like portion is fixed to the end face 53A (or end face 53B) by a plurality of bolts 69. A through hole 66A is formed in the sleeve 66. The through hole 66A is formed by penetrating the plate-like portion of the sleeve 66 in a direction parallel to the Z-axis direction. The shank portion 63 of the first cutting tool 22A is, for example, a polygon taper shank, and the cross-sectional shape of the through hole 66A is shaped to match the cross-sectional shape of the shank portion 63, and is approximately triangular in shape (see Figure 5).

[0031] The first cutting tool 22A is installed with its shank portion 63 inserted into the sleeve 66 through the through hole 66A. The locking mechanism 67 is a device for fixing the shank portion 63 inserted into the sleeve 66. The locking bolts 68 are attached to the outer circumferential surface 53C, which is the outer surface of the tool holding portion 53 in the X-axis direction. The locking bolts 68 are, for example, hexagon socket head bolts, and four of them are provided, corresponding to the positions of the locking mechanisms 67 at the first and second mounting portions 55A to 55D.

[0032] The locking mechanism 67 switches between a state in which the first cutting tool 22A is fixed and a state in which it is released, for example, in response to the rotation of the locking bolt 68. The shank portion 63 has a hole formed in its base end face with an opening. The locking mechanism 67 has a locking part (not shown) that is inserted into the hole in the shank portion 63 from the opening in its base end face, and this locking part is provided with claws. When the locking bolt 68 is rotated clockwise, for example, the locking mechanism 67 fixes the first cutting tool 22A by spreading and pulling in the claws of the locking part inserted into the shank portion 63. Also, when the locking bolt 68 is rotated counterclockwise, the locking mechanism 67 releases the locking of the shank portion 63 by the claws of the locking part. This allows the user to quickly replace the first cutting tool 22A by rotating the locking bolt 68 with a hex wrench or the like. Similarly, the other mounting parts (first and second mounting parts 55B to 55D) are equipped with a locking mechanism that switches between a state in which the first and second cutting tools 22B to 22D are fixed and a state in which they are released, depending on the rotation of the lock bolt 68.

[0033] Figure 6 shows a plan view of the tool holder 23 as seen from the outer circumferential surface 53C side. As shown in Figures 4 to 6, the tool holding portion 53 has first mounting portions 55A and 55B on one side in the Z-axis direction (left side in Figure 6) and second mounting portions 55C and 55D on the other side (right side in Figure 6). The tool holder 23 holds the first cutting tools 22A and 22B in the Y-axis direction at an offset position from the second cutting tools 22C and 22D. In this disclosure, the position of the cutting tool is, for example, the position of the cutting edge of the cutting tool (the position where the cutting tool and the workpiece come into contact). By offsetting the positions of the cutting edges of each cutting tool 22 in the Y-axis direction, the tool holder 23 prevents the cutting edge of the other cutting tool 22 from coming into contact with the workpiece being machined while one cutting tool 22 is machining.

[0034] More specifically, the first and second mounting sections 55A to 55D are each positioned offset from each other in the Y-axis direction. In the example shown in Figure 6, the second mounting section 55C (second cutting tool 22C), the first mounting section 55A (first cutting tool 22A), the second mounting section 55D (second cutting tool 22D), and the first mounting section 55B (first cutting tool 22B) are arranged in that order from one side to the other in the Y-axis direction (from the top to the bottom of Figure 6). The cutting edge positions of each cutting tool 22 are offset in the Y-axis direction. As a result, by holding the first cutting tools 22A and 22B attached to the first mounting sections 55A and 55B, respectively, and the second cutting tools 22C and 22D attached to the second mounting sections 55C and 55D, respectively, in offset positions in the Y-axis direction, it is possible to suppress interference between other cutting tools 22 and the workpiece while processing with any of the cutting tools 22.

[0035] Figure 7 is a side view of the tool post 21 and tool holder 23 as seen from one side in the Y-axis direction, showing the tool holder 23 positioned in the indexing position. Note that Figure 7 shows different types of first cutting tools 22B and second cutting tools 22D than those in Figure 4. As shown in Figure 7, for example, the case of machining a cylindrical workpiece W that is long in the Z-axis direction will be described. When surface machining of the workpiece W is performed with one of the first cutting tools 22A and 22B, for example, in the Z-axis direction, the tip 73 of the workpiece W will be in a position beyond the tips 58C and 58D of the second cutting tools 22C and 22D (a position to the right of tip 58D in Figure 7). For this reason, when machining with the first cutting tools 22A and 22B, there is a risk that the second cutting tools 22C and 22D will interfere with the workpiece W.

[0036] Figure 8 shows a plan view of the tool holder 123 of the comparative example. In the tool holder 123, the first mounting portion 55A and the second mounting portion 55C are located at the same position in the Y-axis direction, and the first mounting portion 55B and the second mounting portion 55D are located at the same position. As shown by the dashed line in Figure 8, the position of the cutting edge of the tip 58A of the first cutting tool 22A mounted on the tool holder 123 coincides with the position of the cutting edge of the tip 58B of the second cutting tool 22C in the Y-axis direction. Similarly, the cutting edge positions of the first cutting tool 22B and the second cutting tool 22D coincide. In this configuration, when the workpiece W is being machined with the first cutting tool 22A, the second cutting tool 22C comes into contact with the workpiece W, making it impossible to perform the machining properly. In particular, if different types of cutting tools (such as a surface machining tool and a boring tool) are attached to the first cutting tools 22A and 22B and the second cutting tools 22C and 22D, the protrusion of the cutting edges will be different, which increases the likelihood of contact with the workpiece W.

[0037] In contrast, as shown in Figures 4 to 6, the cutting edge positions of the tips 58A to 58D in the first embodiment are offset from each other in the Y-axis direction. Therefore, interference between other cutting tools 22 and the workpiece W can be suppressed while machining the workpiece W with any of the cutting tools 22.

[0038] Furthermore, the first and second mounting portions 55A to 55D are provided at positions symmetrical to the center 71 of the tool holder 23. More specifically, the center 71 is the center of the tool holding portion 53 in the Y-axis direction and the Z-axis direction. In the Z-axis direction, the center 71 is the midpoint of the pair of end faces 53A and 53B. Also, notches 53D and 53E are formed at the ends of the tool holding portion 53 in the Y-axis direction. The end face 53F of the second mounting portion 55C in the Y-axis direction protrudes outward in the Y-axis direction more than the end face 53G of the first mounting portion 55A in the Y-axis direction. Each of the end faces 53F and 53G is formed along a direction parallel to the Z-axis direction, and a notch 53D is formed at the connecting portion of the end faces 53F and 53G. Similarly, the end face 53H of the first mounting portion 55B in the Y-axis direction protrudes outward in the Y-axis direction from the end face 53I of the second mounting portion 55D in the Y-axis direction, and a notch 53E is formed at the connection portion of the end faces 53H and 53I. By providing such notches 53D and 53E, the tool holder 23 can be made lighter while maintaining its balance. However, the tool holder 23 may also be configured without the notches 53D and 53E. For example, the tool holder 23 may be configured without the notch 53D, with the end faces 53F and 53G being flush.

[0039] The center 71 is the midpoint of the end faces 53F and 53I in the Y-axis direction, and also the midpoint of the end faces 53G and 53H. When the tool holder 53 is cut by a plane passing through the center 71 and parallel to the Z-axis and X-axis directions, one side (the side with the first and second mounting parts 55A and 55C) and the other side (the side with the first and second mounting parts 55B and 55D) in the Y-axis direction have the same shape. For example, when the tool holder 23 is rotated 180 degrees around the center 71, the positions of the first mounting part 55A and the second mounting part 55D are swapped, and the positions of the second mounting part 55C and the first cutting tool 22B are swapped.

[0040] Therefore, for example, the first mounting portion 55A is located on the opposite side in the Y-axis direction from the second mounting portion 55D, with the center 71 of the tool holder 23 in the Y-axis direction in between. This arrangement allows the first and second mounting portions 55A and 55D to be offset in a balanced manner by arranging them with the center 71 of the tool holder 23 in the Y-axis direction in between. The center of gravity of the tool holder 23 when the first and second cutting tools 22A and 22D are attached can be aligned with the center 71. Similarly, the first mounting portion 55B is located on the opposite side in the Y-axis direction from the second mounting portion 55C, with the center 71 in between.

[0041] Furthermore, for example, a straight line (shown as a dashed line in Figure 6) passing through the cutting edges of each tip 58A to 58D and parallel to the Z-axis direction is defined as the position where each mounting part is arranged in the Y-axis direction. This straight line is, for example, a straight line passing through the center of the insertion hole 65 in the Y-axis direction. When the position of each mounting part is defined in this way, the first mounting part 55A is located at a distance of first offset amount OS1 from the center 71 along a direction parallel to the Y-axis direction toward one side in the Y-axis direction (upper side in Figure 6). The second mounting part 55D is located at a distance of second offset amount OS2 from the center 71 along a direction parallel to the Y-axis direction toward the other side in the Y-axis direction (lower side in Figure 6). The second offset amount OS2 is the same as the first offset amount OS1. The first and second offset amounts OS1 and OS2 are, for example, several tens of millimeters.

[0042] According to this, by making the first and second offset amounts OS1 and OS2 the same, the control content for switching between the first and second cutting tools 22A and 22D can be simplified. For example, the center 71 is the position that is the center of the holder mounting portion 41 in the Y-axis direction. The control device 17 controls the position of the cutting edges of the first and second cutting tools 22A to 22D, which are positioned at the indexing position with respect to this center 71. In this case, when switching between the first and second cutting tools 22A and 22D, the first cutting tool 22A can be indexed by sliding the tool post 21 to one side by the first offset amount OS1 in the Y-axis direction with respect to the center 71. Also, the second cutting tool 22D can be indexed by sliding the tool post 21 to the other side by the same first offset amount OS1 (second offset amount OS2) with respect to the center 71. This reduces the workload of creating the NC program 35 that moves the tool post 21 in the Y-axis direction to index the cutting tool 22, and also reduces the likelihood of setting errors in the parameters.

[0043] Furthermore, the second mounting portion 55C is provided at a position offset to one side in the Y-axis direction (upper side in Figure 6) relative to the first mounting portion 55A. Similarly, the second mounting portion 55D is provided at a position offset to one side in the Y-axis direction (upper side in Figure 6) relative to the first mounting portion 55B. In this configuration, the direction in which the second mounting portion 55C is positioned relative to the first mounting portion 55A and the direction in which the second mounting portion 55D is positioned relative to the first mounting portion 55B can be unified. This makes it possible to miniaturize the tool holder 23 compared to a configuration in which the mounting portions are positioned in opposite directions, as shown in Figure 10, which will be described later. Furthermore, in the first embodiment, by providing notches 53D and 53E while shifting them in the same direction, the tool holder 23 can be made even smaller and lighter.

[0044] Further, the second attachment portion 55C is provided at a position separated from the first attachment portion 55A by a third offset amount OS3 on one side in the Y-axis direction along a direction parallel to the Y-axis direction. Also, the second attachment portion 55D is provided at a position separated from the first attachment portion 55B by a fourth offset amount OS4 on one side in the Y-axis direction along a direction parallel to the Y-axis direction. And the third offset amount OS3 is the same as the fourth offset amount OS4. According to this, by making the third and fourth offset amounts OS3 and OS4 the same, the control content for switching the four cutting tools 22 can be simplified. By unifying the offset amounts, the creation load of the NC program 35 for moving the tool rest 21 in the Y-axis direction to determine the cutting tool 22 can be reduced, and setting mistakes of parameters can be decreased. For example, when switching the first and second cutting tools 22B and 22C, the second cutting tool 22C can be determined by sliding the tool rest 21 in the Y-axis direction by a predetermined offset amount (OS1 + OS3) to one side based on the center 71. Conversely, the first cutting tool 22B can be determined by sliding the tool rest 21 in the Y-axis direction by the same offset (OS2 + OS4) to the other side based on the center 71. The third and fourth offset amounts OS3 and OS4 are, for example, several tens of mm. Also, in the first embodiment, the third and fourth offset amounts OS3 and OS4 are values that are several mm smaller (shorter) than the first and second offset amounts OS1 and OS2.

[0045] Also, as shown in FIG. 7, in the state where the tool holder 23 is attached to the holder attachment portion 41, the distance L from the holder attachment portion 41 to the first attachment portions 55A and 55B in the X-axis direction is the same as the distance from the holder attachment portion 41 to the second attachment portions 55C and 55D. Note that the broken lines in FIG. 7 indicate the positions of the respective attachment portions, similar to the broken lines in FIG. 6.

[0046] For example, if the first and second cutting tools 22A to 22D of different types are held at the same position in the X-axis direction, the protrusion amount of the cutting edge of each cutting tool 22 in the X-axis direction is different. Therefore, there is a risk that the cutting tool 22 on the opposite side in the Z-axis direction may interfere with the workpiece W during machining with any cutting tool 22. On the other hand, in the present embodiment, by holding the first and second cutting tools 22A to 22D at positions offset in the Y-axis direction, even if the cutting tools 22 have different protrusion amounts of the cutting edges, the occurrence of interference with the workpiece W can be suppressed.

[0047] Furthermore, when the distance L from the holder mounting portion 41 to each mounting portion in the X-axis direction becomes long, there is a risk that the rigidity of the mounting portion may decrease. Therefore, when the distance L in the X-axis direction is adjusted according to the protrusion amount of the cutting edge of each cutting tool 22, the rigidity of the mounting portion with a long distance L decreases. On the other hand, according to the tool holder 23 of the first embodiment, the distance L from the holder mounting portion 41 to the first mounting portions 55A and 55B is the same as the distance L from the holder mounting portion 41 to the second mounting portions 55C and 55D, and the first and second mounting portions 55A to 55D can be arranged at the same position in the X-axis direction. In other words, by offsetting each cutting tool 22 in the Y-axis direction, it is not necessary to arrange each mounting portion at different positions in the X-axis direction in order to prevent interference between each cutting tool 22 and the workpiece W. As a result, the difference in rigidity between the mounting portions can be eliminated.

[0048] In addition, the slide device 14 of the machine tool 10 includes a Y-axis slide device 26 that slides the tool post 21 in the Y-axis direction. The control device 17 can, for example, index the first cutting tools 22A and 22B or the second cutting tools 22C and 22D to the indexing position by controlling the Y-axis slide device 26 to move the tool post 21 in the Y-axis direction after indexing the center 71 of the tool holder 23 to the indexing position. Thereby, the number and types of cutting tools 22 that can be attached to one tool post 21 can be increased, and the occurrence of interference between the unnecessary cutting tool 22 and the workpiece W can be suppressed.

[0049] Incidentally, the correspondence between the terms used in the first embodiment and the terms used in the claims will be explained below. The first mounting parts 55A and 55B of the first embodiment are examples of the first first mounting part and the second first mounting part. The second mounting parts 55C and 55D are examples of the first second mounting part and the second second mounting part.

[0050] As described above, the first embodiment provides the following effects. In one aspect of the first embodiment, the tool holding portion 53 of the tool holder 23 includes, when the tool holder 23 is attached to the tool post 21, first mounting portions 55A, 55B provided on one side in the Z-axis direction parallel to the rotation axis of the tool post 21, and second mounting portions 55C, 55D provided on the other side. The tool holder 23 holds the first cutting tools 22A, 22B in the Y-axis direction at an offset position from the second cutting tools 22C, 22D.

[0051] According to this, by holding each cutting tool 22 in an offset position in the Y-axis direction, the position of the cutting edge of each cutting tool 22 is shifted, and interference between the second cutting tools 22C and 22D, which are on the opposite side in the Z-axis direction, and the workpiece W can be suppressed while the workpiece W is being machined with the first cutting tools 22A and 22B. Similarly, interference between the first cutting tools 22A and 22B and the workpiece W can be suppressed while the workpiece W is being machined with the second cutting tools 22C and 22D. The types of cutting tools 22 that can be attached to the tool post 21 are limited by the number of holder mounting parts 41. If multiple cutting tools 22 can be attached to a single tool holder 23, as in the tool holder 23 of this embodiment, the types of cutting tools 22 that can be attached to the tool post 21 can be increased.

[0052] However, if different types of cutting tools 22, for example, a first cutting tool 22A for surface machining and a second cutting tool 22C for groove machining, are mounted on a single tool holder 23, the amount of cutting edge protrusion in the X-axis direction will differ. That is, while using one of the above-mentioned cutting tools 22, there is a high possibility that the other cutting tool 22 in the Z-axis direction will interfere with the workpiece W. Therefore, when mounting first and second cutting tools 22A to 22D of different types on a tool holder 23, it is extremely beneficial to use a tool holder 23 that holds them offset in the Y-axis direction.

[0053] The configuration of the tool holder 23 in the first embodiment described above is merely an example. For example, the tool holder 23 may be configured such that the base portion 51 is directly attached to the holder mounting portion 41. Alternatively, the tool holder 23 may be configured such that the positions of the first mounting portion 55A and the second mounting portion 55C are the same in the Y-axis direction, and the positions of the cutting edge of the first cutting tool 22A and the cutting edge of the second cutting tool 22C are offset in the Y-axis direction. Specifically, the tool holder 23 may be configured such that the insertion holes 65 of the first mounting portion 55A and the second mounting portion 55C are formed in different directions.

[0054] (Second Embodiment) Next, a second embodiment of the present disclosure will be described. The tool holder 23 of the first embodiment described above had four mounting parts for attaching the cutting tool 22, but the configuration of the tool holder of the present disclosure is not limited to this. For example, the tool holder 23 may have three or five or more mounting parts. Alternatively, it may have only two (one pair) mounting parts, as shown in Figure 9 of the tool holder 23A of the second embodiment. The tool holder 23A of the second embodiment differs from the tool holder 23 of the first embodiment in that it has, for example, a first mounting part 55A and a second mounting part 55D, but does not have a first mounting part 55B or a second mounting part 55C. The first mounting part 55A is provided, for example, at a position offset by an offset amount (OS1 + OS2) in the Y-axis direction from the second mounting part 55D. Even with this configuration, the cutting edge positions of chips 58A and 58D can be shifted, thereby suppressing interference between the workpiece and chips not being used for machining.

[0055] (Third Embodiment) Next, a third embodiment of the present disclosure will be described. In the first embodiment, the second mounting portion 55C, the first mounting portion 55A, the second mounting portion 55D, and the first mounting portion 55B were arranged in that order from one side to the other in the Y-axis direction. In contrast, as shown in Figure 10, the tool holder 23B of the third embodiment differs from the first embodiment in that the first mounting portion 55A, the second mounting portion 55C, the second mounting portion 55D, and the first mounting portion 55B are arranged in that order from one side to the other in the Y-axis direction. The first and second mounting portions 55A to 55D are provided at positions offset from each other in the Y-axis direction, similar to the first embodiment. Even with this configuration, the positions of the cutting edges of the tips 58A to 58D can be shifted, and interference between the workpiece and tips not used for machining can be suppressed.

[0056] It goes without saying that this disclosure is not limited to the embodiments described above, and various improvements and modifications are possible without departing from the spirit of this disclosure. For example, the sliding direction of the X-axis slide device 25 and the sliding direction of the Y-axis slide device 26 in the above embodiments may be 90 degrees apart. In the second embodiment shown in Figure 9, the first mounting portion 55A and the second mounting portion 55D may be provided on the same side with respect to the center 71 in the Y-axis direction. The first offset amount OS1 and the second offset amount OS2 may be different values. The third offset amount OS3 and the fourth offset amount OS4 may be different values. In the X-axis direction, the distance L from the holder mounting portion 41 to the first mounting portions 55A and 55B does not have to be the same as the distance from the holder mounting portion 41 to the second mounting portions 55C and 55D. The tool holder 23 may be configured such that one pair of mounting parts, which are located on opposite sides in the Z-axis direction, are positioned at an offset location in the Y-axis direction. Therefore, the tool holder 23 may have a combination of mounting parts, which are located on opposite sides in the Z-axis direction and are positioned at a location that is not offset in the Y-axis direction. The Y-axis sliding device 26 is not limited to a ball screw mechanism, but may also be other sliding mechanisms such as a linear motor.

[0057] Furthermore, the configuration of the machine tool 10 in the above embodiment is just one example. For example, the machine tool 10 may be configured to include multiple turret devices 13 and workpiece spindle devices 12. The machine tool 10 may also be a lathe with a front spindle. The machine tool 10 may also be a horizontal lathe or a vertical lathe. Furthermore, the machine tool 10 is not limited to a lathe, but may also be other types of processing equipment such as a machining center, milling machine, or drilling machine. The machine tool 10 may also be a composite machine tool equipped with multiple types of processing equipment, such as a lathe and a machining center. Furthermore, the machine tool 10 may also be configured to include a loader or articulated robot for transporting workpieces.

[0058] Furthermore, the scope of this disclosure is not limited to the dependencies described in the claims. For example, this specification also discloses a technical concept in which "the tool holder according to claim 1 or claim 2" in claim 4 is changed to "the tool holder according to any one of claims 1 to 3". Also, for example, this specification also discloses a technical concept in which "the tool holder according to claim 1 or claim 2" in claim 5 is changed to "the tool holder according to any one of claims 1 to 4". Also, for example, this specification also discloses a technical concept in which "a tool post to which the tool holder according to claim 1 or claim 2 can be attached" in claim 8 is changed to "a tool post to which the tool holder according to any one of claims 1 to 7 can be attached".

[0059] 10 Machine tool, 17 Control device, 21 Tool post, 23, 23A, 23B Tool holder, 22A, 22B First cutting tool, 22C, 22D Second cutting tool, 26 Y-axis slide device, 41 Holder mounting section, 55A, 55B First mounting section (first first mounting section, second first mounting section), 55C, 55D Second mounting section (first second mounting section, second second second mounting section), 71 Center, OS1 First offset amount, OS2 Second offset amount, OS3 Third offset amount, OS4 Fourth offset amount, L Distance, W Workpiece.

Claims

1. A tool holder that can be attached to a rotating tool post, comprising: a first mounting portion provided on one side in the Z-axis direction parallel to the rotation axis of the tool post, to which a first cutting tool is attached, and a second mounting portion provided on the other side in the Z-axis direction, to which a second cutting tool is attached, wherein the tool holder holds the first cutting tool in an offset position from the second cutting tool in the Y-axis direction perpendicular to the Z-axis direction.

2. The tool holder according to claim 1, wherein the first mounting portion is provided on the opposite side from the second mounting portion, with the center of the tool holder in the Y-axis direction in between.

3. The tool holder according to claim 2, wherein the first mounting portion is provided at a position located at a distance of a first offset amount to one side in the Y-axis direction from the center of the tool holder, along a direction parallel to the Y-axis direction, and the second mounting portion is provided at a position located at a position located at a distance of a second offset amount to the other side in the Y-axis direction from the center of the tool holder, along a direction parallel to the Y-axis direction, and the second offset amount is the same as the first offset amount.

4. The tool holder according to claim 1 or 2, wherein the tool holder is attachable to the holder mounting portion of the tool post, and in the X-axis direction perpendicular to both the Y-axis direction and the Z-axis direction, the distance from the holder mounting portion to the first mounting portion is the same as the distance from the holder mounting portion to the second mounting portion.

5. The tool holder according to claim 1 or claim 2, comprising a plurality of first mounting portions and a plurality of second mounting portions, wherein each of the plurality of first mounting portions and the plurality of second mounting portions is provided at a position offset from one another in the Y-axis direction.

6. The tool holder according to claim 5, wherein each of the plurality of first mounting portions comprises a first first mounting portion and a second first mounting portion, and each of the plurality of second mounting portions comprises a first second mounting portion and a second second mounting portion, the first second mounting portion is provided at a position offset to one side in the Y-axis direction with respect to the first first mounting portion, and the second second mounting portion is provided at a position offset to one side in the Y-axis direction with respect to the second first mounting portion.

7. The tool holder according to claim 6, wherein the first mounting portion is provided at a position separated from the first mounting portion by a third offset amount to one side in the Y-axis direction, along a direction parallel to the Y-axis direction, and the second mounting portion is provided at a position separated from the second mounting portion by a fourth offset amount to one side in the Y-axis direction, along a direction parallel to the Y-axis direction, and the third offset amount is the same as the fourth offset amount.

8. A machine tool comprising: a tool post to which the tool holder described in claim 1 or claim 2 can be attached; a Y-axis sliding device for sliding the tool post in the Y-axis direction; and a control device for controlling the Y-axis sliding device to move the tool post in the Y-axis direction and to index the first cutting tool or the second cutting tool to a position for machining the workpiece.

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