Tool heads, machine tools, tool arbors, and tool units

Abstract

We provide tool heads, machine tools, tool arbors, and tool units that facilitate high-speed rotation of tools. [Solution] The tool head 20 comprises a tool arbor 21, a tool 50, a first spindle, a second spindle, a first balancer 25, and a second balancer 26. The tool arbor, tool, first spindle, second spindle, first balancer, and second balancer are arranged coaxially with the axis of rotation. At least a portion of the first balancer is positioned between the tool and the first spindle in the axial direction. At least a portion of the second balancer is positioned between the tool and the second spindle in the axial direction. At least a portion of the first balancer is positioned radially inward from the radial inner end of the tool.

Description

Technical Field

[0001] The present invention relates to a tool head, a machine tool, a tool arbor, and a tool unit.

Background Art

[0002] Conventionally, machine tools for machining workpieces are known. A machine tool includes a tool head that holds and rotates a tool. A conventional machine tool equipped with a tool head is described in, for example, Patent Document 1.

[0003] The tool head of Patent Document 1 includes a first spindle shaft, a second spindle shaft, a first balancing device, and a second balancing device. The tool is disposed between the first spindle shaft and the second spindle shaft. The first balancing device is disposed between the spindle bearing and the tool-side end of the first spindle shaft. The second balancing device is disposed between the spindle bearing and the tool-side end of the second spindle shaft.

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The first balancing device of Patent Document 1 radially surrounds the first spindle shaft. Also, the second balancing device of Patent Document 1 radially surrounds the second spindle shaft. In such a structure, the mass of the balancing device is distributed at locations radially away from the rotation axis. As a result, the moment of inertia of the balancing device increases. Therefore, the tool head of Patent Document 1 is not suitable for high-speed rotation.

[0005] Therefore, an object of the present invention is to provide a tool head, a machine tool, a tool arbor, and a tool unit that are easily capable of rotating a tool at high speed. [Means for solving the problem]

[0006] The first invention comprises a cylindrical tool arbor extending axially along a rotation axis, a cylindrical tool held on the outer surface of the tool arbor, a first spindle rotatably supporting a unit including the tool arbor on one side axially from the tool, a second spindle rotatably supporting a unit including the tool arbor on the other side axially from the tool, a first balancer correcting the mass balance about the rotation axis on one side axially from the tool, and a mass balance about the rotation axis on the other side axially from the tool. A tool head comprising a tool arbor, the tool, the first spindle, the second spindle, the first balancer, and the second balancer are arranged coaxially with the axis of rotation, at least a portion of the first balancer is positioned axially between the tool and the first spindle, at least a portion of the second balancer is positioned axially between the tool and the second spindle, and at least a portion of the first balancer is positioned radially inward from the radial inner end of the tool.

[0007] The second invention is a tool arbor formed to extend along a rotation axis and having a cylindrical tool held on its outer circumferential surface, wherein one axial end of the tool arbor is configured to accommodate at least a portion of a first balancer radially inward, and the other axial end of the tool arbor is configured to have a counter flange, capable of accommodating at least a portion of a second balancer radially inward, fixed coaxially with the tool arbor, the tool being held between the axial end and the other axial end, and at least a portion of the first balancer being positioned radially inward from the outer circumferential surface. [Effects of the Invention]

[0008] According to the first and second inventions, at least a portion of the first balancer is positioned radially inward from the radially inward end of the tool. This allows the mass of the first balancer to be distributed closer to the axis of rotation. As a result, the tool can be rotated at high speed more easily. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a front view of the machine tool. [Figure 2] Figure 2 is a plan view of the machine tool. [Figure 3] Figure 3 is a longitudinal cross-sectional view of the tool head. [Figure 4] Figure 4 is a partial longitudinal cross-sectional view of the tool head near the first balancer. [Figure 5] Figure 5 is a partial longitudinal cross-sectional view of the tool head near the second balancer. [Figure 6] Figure 6 is a longitudinal cross-sectional view of the tool head according to the first modified example. [Figure 7] Figure 7 is a longitudinal cross-sectional view of the tool head according to the second modified example. [Figure 8] Figure 8 is a longitudinal cross-sectional view of the tool, tool arbor, counter flange, first balancer, and second balancer according to the third modified example. [Figure 9] Figure 9 is a longitudinal cross-sectional view of a tool, tool arbor, counter flange, first balancer, and second balancer relating to another example of the third modified example. [Modes for carrying out the invention]

[0010] <1. Configuration of machine tools> Figure 1 is a front view of a machine tool 1 according to one embodiment. Figure 2 is a plan view of the machine tool 1 near the workpiece 9 and the tool head 20. The machine tool 1 is a device that processes the workpiece 9 with a tool 50. The machine tool 1 is, for example, a grinding machine that grinds the workpiece 9. Note that in Figures 1 to 7, the dimensions of the actual product may differ from the dimensions in the drawings in order to facilitate understanding of the gist of the invention.

[0011] Workpiece 9 is a workpiece that will become a gear, for example, by grinding to create a high-quality tooth surface shape. Workpiece 9 is roughly cylindrical and has multiple teeth 91 on its outer surface. Hereinafter, the central axis of workpiece 9 will be referred to as "workpiece axis X1".

[0012] As shown in Figures 1 and 2, the machine tool 1 comprises a workpiece rotation mechanism 10, a tool head 20, a moving mechanism 30, and a control unit 40. The workpiece rotation mechanism 10, the tool head 20, and the moving mechanism 30 are mounted on a common bed 90.

[0013] The workpiece rotation mechanism 10 is a mechanism that rotates the workpiece 9 around the workpiece axis X1. The workpiece rotation mechanism 10 includes a pair of clampers that hold the workpiece 9 and a motor that rotates the clampers. In this embodiment, the workpiece 9 rotates while being held in a position where the workpiece axis X1 is facing vertically. However, the orientation of the workpiece axis X1 does not necessarily have to be vertical.

[0014] The tool head 20 is a mechanism that holds and rotates the tool 50. The tool 50 is, for example, a grinding wheel. The tool 50 is roughly cylindrical and has a helical groove 51 on its outer surface. Hereinafter, the central axis of the tool 50 will be referred to as the "tool axis X2". The tool head 20 holds the tool 50 in a position where the tool axis X2 is positioned horizontally. The tool head 20 then rotates the tool 50 around the tool axis X2. The detailed structure of the tool head 20 will be described later. However, the tool head 20 may also hold the tool 50 in a position where the tool axis X2 is not horizontal.

[0015] The moving mechanism 30 is a mechanism for moving the tool head 20 relative to the workpiece 9. The moving mechanism 30 includes a first moving mechanism 31, a second moving mechanism 32, and a third moving mechanism 33. The first moving mechanism 31 moves the tool 50 relative to the workpiece 9 in a direction parallel to the workpiece axis X1. The second moving mechanism 32 moves the tool 50 relative to the workpiece 9 in a direction parallel to the tool axis X2. The third moving mechanism 33 moves the tool 50 toward and away from the workpiece 9.

[0016] The first moving mechanism 31, the second moving mechanism 32, and the third moving mechanism 33 are realized by, for example, a motor and a ball screw that converts the rotation of the motor into a linear motion. With these first moving mechanism 31, second moving mechanism 32, and third moving mechanism 33, the moving mechanism 30 can move the tool 50 relative to the workpiece 9 in any direction in three-dimensional space.

[0017] Note that the moving mechanism 30 may have a fourth moving mechanism that adjusts the intersection angle between the tool axis X2 and the workpiece axis X1.

[0018] The control unit 40 is a unit that controls the operations of each part of the machine tool 1. The control unit 40 is constituted by, for example, a computer having a processor such as a CPU, a memory such as a RAM, and a storage unit such as a hard disk drive. A computer program for controlling the operations of the machine tool 1 is stored in the storage unit.

[0019] The control unit 40 is electrically connected to the workpiece rotation mechanism 10, the tool head 20, and the moving mechanism 30 described above. The control unit 40 controls the operations of these parts according to the above computer program. Thereby, the processing of the workpiece 9 in the machine tool 1 proceeds.

[0020] <2. Detailed Configuration of Tool Head> Next, the detailed configuration of the tool head 20 described above will be explained.

[0021] FIG. 3 is a longitudinal sectional view of the tool head 20. As shown in FIG. 3, the tool head 20 includes a tool 50, a tool arbor 21, a first spindle 232, a second spindle 242, a first balancer 25, and a second balancer 26. The tool 50, the tool arbor 21, the first spindle 232, the second spindle 242, the first balancer 25, and the second balancer 26 are arranged coaxially with the rotation axis A.

[0022] In the following, the direction along the rotation axis A of the tool head 20 will be referred to as the "axial direction D". Furthermore, the side of the tool 50 facing the first spindle 232 will be referred to as "one side of the axial direction D", and the side of the tool 50 facing the second spindle 242 will be referred to as "the other side of the axial direction D". Furthermore, the direction perpendicular to the rotation axis A of the tool head 20 will be referred to as the "radial direction". Furthermore, the direction along the arc centered on the rotation axis A of the tool head 20 will be referred to as the "circumferential direction".

[0023] As shown in Figure 3, the tool head 20 of this embodiment comprises a tool 50, a tool arbor 21, a counter flange 22, a first spindle unit 23, a second spindle unit 24, a first balancer 25, a second balancer 26, a first collector member 27, and a second collector member 28.

[0024] The tool arbor 21 is a cylindrical component that holds the tool 50. The tool arbor 21 extends axially D along the rotation axis A of the tool head 20. The tool 50 is held on the outer surface of the tool arbor 21. When the tool 50 is held in the tool arbor 21, the tool axis X2 of the tool 50 coincides with the rotation axis A of the tool head 20.

[0025] As shown in Figure 3, the tool arbor 21 of this embodiment has a small-diameter cylindrical portion 211, a first cylindrical portion 212, and a first enlarged diameter portion 213. The small-diameter cylindrical portion 211 is cylindrical with respect to the axis of rotation A and has a smaller diameter than the first cylindrical portion 212. The small-diameter cylindrical portion 211 is inserted radially inward into the tool 50. As a result, the tool 50 is held on the outer surface of the small-diameter cylindrical portion 211. However, the tool 50 may be held on the outer surface of the small-diameter cylindrical portion 211 via other members.

[0026] The first cylindrical portion 212 is positioned on one side in the axial direction D compared to the small-diameter cylindrical portion 211. The first cylindrical portion 212 is cylindrical with respect to the axis of rotation A. The diameter of the first cylindrical portion 212 is larger than the diameter of the small-diameter cylindrical portion 211. More specifically, the outer diameter of the first cylindrical portion 212 is larger than the outer diameter of the small-diameter cylindrical portion 211. Also, the inner diameter of the first cylindrical portion 212 is larger than the inner diameter of the small-diameter cylindrical portion 211.

[0027] One end of the tool 50 in the axial direction D contacts the first cylindrical portion 213. The other end of the tool 50 in the axial direction D contacts the nut 217 attached to the small-diameter cylindrical portion 211. In other words, the tool 50 is sandwiched between the nut 217 and the first cylindrical portion 213 in the axial direction D. This positions the tool 50 in the axial direction D.

[0028] The first enlarged diameter portion 213 is the part that connects the small diameter cylindrical portion 211 and the first cylindrical portion 212. The first enlarged diameter portion 213 expands radially from one end of the small diameter cylindrical portion 211 in the axial direction D toward the other end of the first cylindrical portion 212 in the axial direction D. The first enlarged diameter portion 213 is an annular shape centered on the axis of rotation A.

[0029] Furthermore, the tool arbor 21 of this embodiment further has a first flange portion 214. The first flange portion 214 extends radially outward from one end of the first cylindrical portion 212 in the axial direction D. The first flange portion 214 is fixed to the first collector member 27, which will be described later.

[0030] One axial end of the tool arbor 21 is configured to accommodate at least a portion of the first balancer 25 radially inward. In this embodiment, a portion of the first balancer 25 is accommodated radially inward of the first cylindrical portion 212. However, the entire first balancer 25 may be accommodated radially inward of the first cylindrical portion 212. Furthermore, the shape of the tool arbor 21 for accommodating at least a portion of the first balancer 25 radially inward may be other shapes, such as a polygonal cylinder.

[0031] The other axial end of the tool arbor 21 is configured to allow the counter flange 22 to be fixed. In this embodiment, the connecting portion 221 of the counter flange 22, described later, is inserted inside the small-diameter cylindrical portion 211 of the tool arbor 21. This fixes the tool arbor 21 and the counter flange 22 coaxially. However, the configuration of the tool arbor 21 for fixing the counter flange 22 may be in other forms. For example, the other axial end of the tool arbor 21 may be insertable into a hole provided in the counter flange 22. Alternatively, the other axial end of the tool arbor 21 may be able to fix the counter flange 22 with a bolt.

[0032] The tool 50 is held on the outer circumferential surface 211a of the small-diameter cylindrical portion 211 between one axial end and the other axial end of the tool arbor 21 described above. In this embodiment, the small-diameter cylindrical portion 211 that holds the tool 50 is cylindrical, i.e., hollow. This reduces the mass of the tool arbor 21 compared to when the part that holds the tool 50 is solid.

[0033] The counter flange 22 is a component connected to the tool arbor 21 on the other side of the tool 50 in the axial direction D. As shown in Figure 3, the counter flange 22 has a connecting portion 221, a second cylindrical portion 222, and a second enlarged diameter portion 223.

[0034] The connecting portion 221 is inserted radially inward into the tool arbor 21. The connecting portion 221 has a support mechanism that supports the tool arbor 21. The support mechanism supports the small-diameter cylindrical portion 211 of the tool arbor 21 from the inside. This allows the counter flange 22 to be precisely fixed to the tool arbor 21. For example, a hydraulic mandrel can be used as the support mechanism. However, other mechanisms such as an expandable collet may also be used as the support mechanism.

[0035] The second cylindrical portion 222 is positioned on the other side of the axial direction D from the connecting portion 221. The second cylindrical portion 222 is cylindrical with respect to the axis of rotation A. The diameter of the second cylindrical portion 222 is larger than the diameter of the connecting portion 221. More specifically, the outer and inner diameters of the second cylindrical portion 222 are larger than the outer diameter of the connecting portion 221.

[0036] The second enlarged diameter portion 223 is the part that connects the connecting portion 221 and the second cylindrical portion 222. The second enlarged diameter portion 223 expands radially from the other end of the connecting portion 221 in the axial direction D toward the one end of the second cylindrical portion 222 in the axial direction D. The second enlarged diameter portion 223 is an annular shape centered on the axis of rotation A.

[0037] Furthermore, the counter flange 22 of this embodiment further has a second flange portion 224. The second flange portion 224 extends radially outward from the other end of the second cylindrical portion 222 in the axial direction D. The second flange portion 224 is fixed to the second collector member 28, which will be described later.

[0038] The counter flange 22 is configured such that at least a portion of the second balancer 26 can be accommodated radially inward. In this embodiment, a portion of the second balancer 26 is accommodated radially inward of the second cylindrical portion 222. However, the entire second balancer 26 may be accommodated radially inward of the second cylindrical portion 222. Furthermore, the shape of the counter flange 22 for accommodating at least a portion of the second balancer 26 radially inward may be other shapes, such as a polygonal cylinder.

[0039] The first spindle unit 23 is positioned on one side of the tool 50 in the axial direction D. As shown in Figure 3, the first spindle unit 23 includes a first housing 231, a first spindle 232, a first bearing 233, and a motor 234. The first spindle 232, the first bearing 233, and the motor 234 are housed inside the first housing 231.

[0040] The first spindle 232 is a shaft extending axially D along the axis of rotation A. The first spindle 232 is supported in the first housing 231 via a first bearing 233. The motor 234 is electrically connected to the control unit 40. The motor 234 rotates the first spindle 232 based on the drive current supplied from the control unit 40. The first spindle 232 rotates about the axis of rotation A.

[0041] The first spindle 232 and the tool arbor 21 are connected via a first collector member 27, which will be described later. This allows the first spindle 232 to rotatably support the unit including the tool arbor 21. When the first spindle 232 rotates due to the motor 234, the first collector member 27 and the tool arbor 21 also rotate around the rotation axis A.

[0042] The second spindle unit 24 is located on the other side of the axial direction D relative to the tool 50. As shown in Figure 3, the second spindle unit 24 comprises a second housing 241, a second spindle 242, and a second bearing 243. The second spindle 242 and the second bearing 243 are housed inside the second housing 241.

[0043] The second spindle 242 is a shaft extending axially D along the axis of rotation A. The second spindle 242 is supported in the second housing 241 via a second bearing 243. This allows the second spindle 242 to rotate about the axis of rotation A.

[0044] The second spindle 242 and the counter flange 22 are connected via a second collector member 28, which will be described later. As a result, the second spindle 242 rotatably supports the unit including the tool arbor 21. When the tool arbor 21 is rotated by the motor 234, the counter flange 22, the second collector member 28, and the second spindle 242 also rotate around the axis of rotation A.

[0045] In the tool head 20 of this embodiment, the tool 50 is supported by a first spindle 232 located on one side in the axial direction D and a second spindle 242 located on the other side in the axial direction D. This double-support structure allows the tool 50 to be rotated with high precision.

[0046] The first balancer 25 is a mechanism that corrects the mass balance around the rotation axis A on one side of the tool 50 in the axial direction D. As shown in Figure 3, the first balancer 25 has a solid shaft 251 and one or more weights 252. The solid shaft 251 extends in the axial direction D along the rotation axis A. The weights 252 are arranged on the outer surface of the solid shaft 251. Note that the first balancer 25 may have a configuration other than the combination of a solid shaft 251 and weights 252.

[0047] The tool head 20 has a vibration sensor 236. The vibration sensor 236 detects a mass imbalance around the rotation axis A of the rotating body including the tool 50. Based on the detection results of the vibration sensor 236, the first balancer 25 adjusts the circumferential position of the weight 252 on the outer surface of the solid shaft 251. In this way, the first balancer 25 corrects at least one of the static balance and dynamic balance of the rotating body including the tool 50.

[0048] The second balancer 26 is a mechanism that corrects the mass balance around the rotation axis A on the other side of the tool 50 in the axial direction D. As shown in Figure 3, the second balancer 26 has a solid shaft 261 and one or more weights 262. The solid shaft 261 extends in the axial direction D along the rotation axis A. The weights 262 are arranged on the outer surface of the solid shaft 261. Note that the second balancer 26 may have a configuration other than the combination of a solid shaft 261 and weights 262.

[0049] The second balancer 26 adjusts the circumferential position of the weight 262 on the outer surface of the solid shaft 261 based on the detection results of the vibration sensor 236. In this way, the second balancer 26 corrects at least one of the static balance and dynamic balance of the rotating body including the tool 50.

[0050] In the examples shown in Figures 3 and 4, the vibration sensor 236 is installed on the outer circumferential surface of the first housing 231. However, the tool head 20 may have two or more vibration sensors 236. In that case, the second vibration sensor 236 may be installed on the outer circumferential surface of the second housing 241.

[0051] When both ends of the tool 50 are supported, multiple mass imbalances are likely to occur in the rotating body, and an imbalance due to a couple may occur. In this embodiment, it is also possible to correct the two-plane dynamic balance by synchronous control of the first balancer 25 and the second balancer 26.

[0052] The tool 50 wears down as it processes the workpiece 9. In particular, the wear of the tool 50 is significant when the tool 50 is a grinding wheel. However, this machine tool 1 can compensate for the change in mass balance due to the wear of the tool 50 using the first balancer 25 and the second balancer 26. Therefore, it is possible to suppress the runout caused by the eccentricity of the worn tool 50. Furthermore, when the tool 50 is replaced, the change in mass balance can also be adjusted using the first balancer 25 and the second balancer 26.

[0053] The first collector member 27 is a member that holds the conductor connected to the first balancer 25. The first collector member 27 is positioned on one side of the tool arbor 21 in the axial direction D. The first collector member 27 is fixed to one end of the tool arbor 21 in the axial direction D by bolts. The first collector member 27 is also fixed to the other end of the first spindle 232 in the axial direction D by bolts.

[0054] The second collector member 28 is a member that holds the conductor connected to the second balancer 26. The second collector member 28 is located on the other side of the counter flange 22 in the axial direction D. The second collector member 28 is fixed to the other end of the counter flange 22 in the axial direction D by bolts. The second collector member 28 is also fixed to one end of the second spindle 242 in the axial direction D by bolts.

[0055] <3. Regarding the first balancer> Next, the first balancer 25 described above will be explained in more detail. Figure 4 is a partial longitudinal cross-sectional view of the tool head 20 near the first balancer 25.

[0056] As shown in Figure 4, the first balancer 25 is positioned between the tool arbor 21 and the first collector member 27. More specifically, the first balancer 25 is housed in the space formed between the tool arbor 21 and the first collector member 27 by the connection between the tool arbor 21 and the first collector member 27. At least a portion of the first balancer 25 is positioned between the tool 50 and the first spindle 232 in the axial direction D.

[0057] The first balancer 25 is fixed to the first collector member 27 by bolts 253. Therefore, the first balancer 25 rotates together with the tool arbor 21 and the first collector member 27. However, the first balancer 25 may also be fixed to the tool arbor 21 by bolts.

[0058] At least a portion of the first balancer 25 is positioned radially inward from the radially inner end of the tool 50. That is, at least a portion of the first balancer 25 is positioned radially inward from the outer circumferential surface 211a of the small-diameter cylindrical portion 211 of the tool arbor 21 that holds the tool 50. This allows the mass of the first balancer 25 to be distributed closer to the axis of rotation A. In other words, the first balancer 25 in this embodiment is not configured as a cylindrical shape with a diameter larger than the inner diameter of the tool 50, but rather at least a portion of its mass is distributed radially inward from the radially inner end of the tool 50. This reduces the moment of inertia of the first balancer 25. Therefore, it becomes easier to rotate the tool 50 at high speed.

[0059] Furthermore, in this embodiment, the radial outer end 25E of the first balancer 25 is positioned radially inward from the radial outer end of the tool 50. That is, the inner surface of the first cylindrical portion 212 that holds the first balancer 25 is positioned radially inward from the radial outer end of the tool 50. By reducing the outer diameter of the first balancer 25 in this way, the moment of inertia of the first balancer 25 can be made smaller. Therefore, the tool 50 can be rotated at a higher speed.

[0060] The radial outer end 25E of the first balancer 25 may be positioned radially inward from the radial inner end of the tool 50. That is, the entire first balancer 25 may be positioned radially inward from the radial inner end of the tool 50. In this case, the mass of the first balancer 25 is concentrated closer to the axis of rotation A, so the moment of inertia of the first balancer 25 becomes smaller. This makes it easier to rotate the tool 50 at a higher speed.

[0061] Furthermore, in this embodiment, the first balancer 25 has a columnar solid shaft 251 instead of a cylindrical hollow shaft. This allows the mass of the first balancer 25 to be distributed closer to the axis of rotation A. Therefore, the moment of inertia of the first balancer 25 can be made smaller. As a result, the tool 50 can be rotated at a higher speed.

[0062] At least a portion of the solid shaft 251 is positioned radially inward from the radially inward end of the tool 50. This allows the moment of inertia of the first balancer 25 to be reduced. As a result, the tool 50 can be rotated at a higher speed.

[0063] Furthermore, in this embodiment, a portion of the first balancer 25 is positioned radially inward of the first cylindrical portion 212 of the tool arbor 21. That is, at least a portion of the first balancer 25 is positioned radially inward of the tool arbor 21. In this way, the mass of at least a portion of the first balancer 25 is distributed radially inward of the tool arbor 21. This makes it possible to reduce the moment of inertia of the first balancer 25. As a result, it becomes easier to rotate the tool 50 at a higher speed.

[0064] The outer surface of the first balancer 25 contacts the inner surface of the first cylindrical portion 212. This positions the first balancer 25 radially. The other end face of the first balancer 25 in the axial direction D faces the first enlarged diameter portion 213 of the tool arbor 21 with a small gap in the axial direction D. However, the other end face of the first balancer 25 in the axial direction D may be brought into contact with the first enlarged diameter portion 213 of the tool arbor 21 in the axial direction D. In other words, the first balancer 25 may be in contact with the first enlarged diameter portion 213 in the axial direction D. If this is done, the first balancer 25 can be positioned in the axial direction D using the first enlarged diameter portion 213.

[0065] As shown in an enlarged view in Figure 4, the tool arbor 21 has a first tapered surface 215. The first tapered surface 215 is inclined with respect to the axial direction D and the radial direction. In this embodiment, the first tapered surface 215 is a conical surface centered on the axis of rotation A. The first collector member 27 is in contact with the first tapered surface 215. This allows the first collector member 27 to be precisely positioned relative to the tool arbor 21 in the axial direction D and the radial direction.

[0066] The first balancer 25 is positioned in the space formed by the precise positioning of the tool arbor 21 and the first collector member 27 by the first tapered surface 215. This allows the first balancer 25 to be precisely positioned in the axial direction D and the radial direction. Furthermore, the first balancer 25 can be precisely positioned coaxially with respect to the rotation axis A.

[0067] The tool head 20 of this embodiment includes a first housing 231 that accommodates a first spindle 232. The radial outer end 25E of the first balancer 25 is positioned radially inward from the radial outer end of the first housing 231. By reducing the outer diameter of the first balancer 25 in this way, the moment of inertia of the first balancer 25 can be made smaller. Therefore, the tool 50 can be rotated at a higher speed.

[0068] At least a portion of the first balancer 25 may be positioned radially inward of the first housing 231. In this case, the mass of at least a portion of the first balancer 25 is distributed radially inward of the first housing 231. This makes it possible to reduce the moment of inertia of the first balancer 25. As a result, the tool 50 can be rotated at a higher speed. In addition, the axial position D of the first balancer 25 and the axial position D of the first housing 231 overlap at least partially. This makes it possible to reduce the axial length D of the tool head 20.

[0069] The tool head 20 of this embodiment includes a first bearing 233 that supports the first spindle 232. The radial outer end 25E of the first balancer 25 is positioned radially inward from the radial inner end of the first bearing 233. By reducing the outer diameter of the first balancer 25 in this way, the moment of inertia of the first balancer 25 can be made smaller. Therefore, the tool 50 can be rotated at a higher speed.

[0070] <4. Regarding the second balancer> Next, the second balancer 26 described above will be explained in more detail. Figure 5 is a partial longitudinal cross-sectional view of the tool head 20 near the second balancer 26.

[0071] As shown in Figure 5, the second balancer 26 is positioned between the counter flange 22 and the second collector member 28. More specifically, the second balancer 26 is housed in the space formed between the counter flange 22 and the second collector member 28 by the connection between the counter flange 22 and the second collector member 28. At least a portion of the second balancer 26 is positioned between the tool 50 and the second spindle 242 in the axial direction D.

[0072] The second balancer 26 is fixed to the second collector member 28 by bolts 263. Therefore, the second balancer 26 rotates together with the counter flange 22 and the second collector member 28. However, the second balancer 26 may also be fixed to the counter flange 22 by bolts.

[0073] At least a portion of the second balancer 26 is positioned radially inward from the radially inner end of the tool 50. This allows the mass of the second balancer 26 to be distributed closer to the axis of rotation A. In other words, the second balancer 26 in this embodiment is not configured as a cylindrical shape with a diameter larger than the inner diameter of the tool 50, but rather at least a portion of its mass is distributed radially inward from the radially inner end of the tool 50. This reduces the moment of inertia of the second balancer 26. Therefore, it becomes easier to rotate the tool 50 at high speed.

[0074] Furthermore, in this embodiment, the radial outer end 26E of the second balancer 26 is positioned radially inward from the radial outer end of the tool 50. By reducing the outer diameter of the second balancer 26 in this way, the moment of inertia of the second balancer 26 can be made smaller. Therefore, the tool 50 can be rotated at a higher speed.

[0075] The radial outer end 26E of the second balancer 26 may be positioned radially inward from the radial inner end of the tool 50. That is, the entire second balancer 26 may be positioned radially inward from the radial inner end of the tool 50. In this case, the mass of the second balancer 26 is concentrated closer to the axis of rotation A, so the moment of inertia of the second balancer 26 becomes smaller. This makes it easier to rotate the tool 50 at a higher speed.

[0076] Furthermore, in this embodiment, the second balancer 26 has a columnar solid shaft 261 instead of a cylindrical hollow shaft. This allows the mass of the second balancer 26 to be distributed closer to the axis of rotation A. Therefore, the moment of inertia of the second balancer 26 can be made smaller. As a result, the tool 50 can be rotated at a higher speed.

[0077] The solid shaft 261 is positioned radially inward from the radially inward end of the tool 50. This allows the moment of inertia of the second balancer 26 to be reduced. As a result, the tool 50 can be rotated at a higher speed.

[0078] Furthermore, in this embodiment, a portion of the second balancer 26 is positioned radially inward of the second cylindrical portion 222 of the counter flange 22. That is, at least a portion of the second balancer 26 is positioned radially inward of the counter flange 22. In this way, the mass of at least a portion of the second balancer 26 is distributed radially inward of the counter flange 22. This makes it possible to reduce the moment of inertia of the second balancer 26. As a result, the tool 50 can be rotated at a higher speed.

[0079] The outer surface of the second balancer 26 contacts the inner surface of the second cylindrical portion 222. This positions the second balancer 26 radially. One end face of the second balancer 26 in the axial direction D faces the second enlarged diameter portion 223 of the counter flange 22 with a small gap in the axial direction D. However, one end face of the second balancer 26 in the axial direction D may be brought into contact with the second enlarged diameter portion 223 of the counter flange 22 in the axial direction D. In other words, the second balancer 26 may be in contact with the second enlarged diameter portion 223 in the axial direction D. If this is done, the second balancer 26 can be positioned in the axial direction D using the second enlarged diameter portion 223.

[0080] As shown in an enlarged view in Figure 5, the counter flange 22 has a second tapered surface 225. The second tapered surface 225 is inclined with respect to the axial direction D and the radial direction. In this embodiment, the second tapered surface 225 is a conical surface centered on the axis of rotation A. The second collector member 28 is in contact with the second tapered surface 225. This allows the second collector member 28 to be precisely positioned relative to the counter flange 22 in the axial direction D and the radial direction.

[0081] The second balancer 26 is positioned in the space formed by the precise positioning of the counter flange 22 and the second collector member 28 by the second tapered surface 225. This allows the second balancer 26 to be precisely positioned in the axial direction D and the radial direction. Furthermore, the second balancer 26 can be precisely positioned coaxially with respect to the rotation axis A.

[0082] The tool head 20 of this embodiment includes a second housing 241 that accommodates a second spindle 242. The radial outer end 26E of the second balancer 26 is positioned radially inward from the radial outer end of the second housing 241. By reducing the outer diameter of the second balancer 26 in this way, the moment of inertia of the second balancer 26 can be made smaller. Therefore, the tool 50 can be rotated at a higher speed.

[0083] At least a portion of the second balancer 26 may be positioned radially inward of the second housing 241. In this case, the mass of at least a portion of the second balancer 26 is distributed radially inward of the second housing 241. This makes it possible to reduce the moment of inertia of the second balancer 26. As a result, the tool 50 can be rotated at a higher speed. In addition, the axial position D of the second balancer 26 and the axial position D of the second housing 241 overlap at least partially. This makes it possible to reduce the axial length D of the tool head 20.

[0084] The tool head 20 of this embodiment includes a second bearing 243 that supports the second spindle 242. The radial outer end 26E of the second balancer 26 is positioned radially inward from the radial inner end of the second bearing 243. By reducing the outer diameter of the second balancer 26 in this way, the moment of inertia of the second balancer 26 can be made smaller. Therefore, the tool 50 can be rotated at a higher speed.

[0085] The machine tool 1 of this embodiment is equipped with such a tool head 20, which allows the tool 50 to rotate at high speed. Therefore, the tool 50 can be brought into high-speed sliding contact with the workpiece 9. In particular, when machining a workpiece 9 with steps, such as a two-stage gear, it is difficult to increase the diameter of the tool 50, so it is necessary to rotate a small-diameter tool 50 at high speed. In such cases, the tool head 20 of this embodiment is particularly useful.

[0086] <5. Variation> Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment.

[0087] <5-1. First variation> Figure 6 is a longitudinal cross-sectional view of a tool head 20 according to the first modified example. In the example of Figure 6, the first spindle 232 has a first flow path 235 extending in the axial direction D. Specifically, a hole that becomes the first flow path 235 is formed inside the first spindle 232. The machine tool 1 flows coolant through the first flow path 235. This cools the first spindle 232 and the first bearing 233. Therefore, the first spindle 232 can be rotated at high speed, and the temperature of the first spindle 232 and the first bearing 233 can be suppressed.

[0088] The first balancer 25 is positioned in a different axial direction D than the first spindle 232. Specifically, one end of the first balancer 25 in the axial direction D is positioned further axially D than the other end of the first spindle 232 in the axial direction D. Therefore, as shown in Figure 6, a first flow path 235 can be formed in the first spindle 232. Thus, by flowing coolant through the first flow path 235, the first spindle 232 and the first bearing 233 can be cooled. As a result, the tool 50 can be rotated at a higher speed. In addition, thermal expansion occurring in the axial direction D can be reduced.

[0089] Furthermore, in the example shown in Figure 6, the second spindle 242 has a second flow path 245 extending in the axial direction D. Specifically, a hole that becomes the second flow path 245 is formed inside the second spindle 242. The machine tool 1 flows coolant through the second flow path 245. This cools the second spindle 242 and the second bearing 243. Therefore, the second spindle 242 can be rotated at high speed, and the temperature of the second spindle 242 and the second bearing 243 can be suppressed.

[0090] The second balancer 26 is positioned in a different axial direction D than the second spindle 242. Specifically, the other end of the second balancer 26 in the axial direction D is positioned one side in the axial direction D than one end of the second spindle 242 in the axial direction D. Therefore, as shown in Figure 6, a second flow path 245 can be formed in the second spindle 242. Thus, by flowing coolant through the second flow path 245, the second spindle 242 and the second bearing 243 can be cooled. As a result, the tool 50 can be rotated at a higher speed. In addition, thermal expansion occurring in the axial direction D can be reduced.

[0091] The structure shown in Figure 6 reduces thermal expansion in the axial direction D between the first spindle 232 and the second spindle 242, thereby reducing the change in coaxiality between the first spindle 232 and the second spindle 242. Consequently, a decrease in the rotational accuracy of the tool 50 can be suppressed.

[0092] In the example shown in Figure 6, the other end of the second balancer 26 in the axial direction D is positioned on the other side of the axial direction D compared to one end of the second housing 241 in the axial direction D. That is, at least a portion of the second balancer 26 overlaps with the second housing 241 in the axial direction D. This reduces the axial length D of the tool head 20.

[0093] <5-2. Second variation> Figure 7 is a longitudinal cross-sectional view of the tool head 20 according to a second modified example. In the example shown in Figure 7, the radial outer end 25E of the first balancer 25 is positioned radially inward from the radial outer end of the first spindle 232. By reducing the outer diameter of the first balancer 25 in this way, the moment of inertia of the first balancer 25 can be made smaller. Therefore, the tool 50 can be rotated at a higher speed.

[0094] However, in the example shown in Figure 7, the radial outer end 25E of the first balancer 25 is positioned radially outward from the radial inner end of the tool 50. This allows the radial size of the first balancer 25 to be sufficiently large even when the radial size of the tool 50 is small. Therefore, the first balancer 25 makes it easier to correct the mass balance and rotational balance of the tool head 20.

[0095] Furthermore, in the example shown in Figure 7, the radially outer end 26E of the second balancer 26 is positioned radially inward from the radially outer end of the second spindle 242. By reducing the outer diameter of the second balancer 26 in this way, the moment of inertia of the second balancer 26 can be made smaller. Consequently, the tool 50 can be rotated at a higher speed.

[0096] However, in the example shown in Figure 7, the radially outer end 26E of the second balancer 26 is positioned radially outward from the radially inner end of the tool 50. This allows the radial size of the second balancer 26 to be sufficiently large even when the radial size of the tool 50 is small. Therefore, the second balancer 26 makes it easier to correct the mass balance and rotational balance of the tool head 20.

[0097] Furthermore, in the example shown in Figure 7, the tool arbor 21 has a solid columnar portion 216 instead of the small-diameter cylindrical portion 211 as in the embodiment described above. The columnar portion 216 is cylindrical with the rotation axis A as its center. The columnar portion 216 is inserted radially inward into the tool 50. As a result, the tool 50 is held on the outer surface of the columnar portion 216. By making the portion of the tool arbor 21 that holds the tool 50 solid in this way, the outer diameter of that portion can be made smaller than in the case of a hollow tool arbor. Therefore, it can accommodate tools 50 with smaller diameters.

[0098] <5-3. Third Variation> Figures 8 and 9 are longitudinal cross-sectional views of the tool 50, tool arbor 21, counter flange 22, first balancer 25, and second balancer 26 according to the third modified example. In the embodiment described above, the first balancer 25 was fixed to the first collector member 27. In contrast, in the example of Figures 8 and 9, the first balancer 25 is fixed to the tool arbor 21. Specifically, the first balancer 25 is fixed to one axial end of the tool arbor 21 by a bolt 253.

[0099] Furthermore, in the embodiment described above, the second balancer 26 was fixed to the second collector member 28. In contrast, in the examples of Figures 8 and 9, the second balancer 26 is fixed to a counter flange 22 fixed to the other axial end of the tool arbor 21. Specifically, the second balancer 26 is fixed to the counter flange 22 by bolts 263.

[0100] In this way, the tool 50, tool arbor 21, counter flange 22, first balancer 25, and second balancer 26 can be integrated as a tool unit 60. Therefore, the tool unit 60 can be pre-balanced using the first balancer 25 and second balancer 26 before being attached to the spindle, and then the tool unit 60 can be attached to the spindle. This allows the balancing adjustment using the first balancer 25 and second balancer 26 after attachment to the spindle to be performed in a short amount of time.

[0101] Furthermore, in the third modified example shown in Figures 8 and 9 above, the first balancer 25 and the second balancer 26 can be integrated with the tool unit 60, and these first balancer 25 and second balancer 26 can also be replaced. Therefore, the size of the first balancer 25 and the second balancer 26 can be changed to match the size of the tool 50. For example, when using a tool 50 with a smaller radial size, the first balancer 25 and the second balancer 26 can be replaced with ones that have a smaller radial size to match. This makes it possible to rotate the first balancer 25 and the second balancer 26 themselves at high speed.

[0102] <5-4. Other variations> In the above embodiment, a grinding wheel was given as an example of the tool 50. However, the "tool" in the present invention is not limited to a grinding wheel for grinding, but may also be a cutter for cutting, etc.

[0103] Furthermore, the elements that appear in the above embodiments and modifications may be combined as appropriate, to the extent that no contradictions arise.

[0104] <6. Summary> This technology can be configured as follows:

[0105] (1) A cylindrical tool arbor extending axially along the axis of rotation; a cylindrical tool held on the outer surface of the tool arbor; a first spindle rotatably supporting the unit including the tool arbor on one side axially from the tool; a second spindle rotatably supporting the unit including the tool arbor on the other side axially from the tool; a first balancer correcting the mass balance around the axis of rotation on one side axially from the tool; and a second balancer correcting the mass balance around the axis of rotation on the other side axially from the tool. A tool head comprising a tool arbor, the tool, the first spindle, the second spindle, the first balancer, and the second balancer are arranged coaxially with the axis of rotation, at least a portion of the first balancer is positioned axially between the tool and the first spindle, at least a portion of the second balancer is positioned axially between the tool and the second spindle, and at least a portion of the first balancer is positioned radially inward from the radial inner end of the tool.

[0106] (2) A tool head as described in (1), wherein the radially outer end of the first balancer is positioned radially inward from the radially outer end of the tool.

[0107] (3) A tool head according to (1), wherein at least a portion of the second balancer is positioned radially inward from the radially inward end of the tool.

[0108] (4)(3) A tool head as described above, wherein the radially outer end of the second balancer is positioned radially inward from the radially outer end of the tool.

[0109] (5) A tool head according to any one of (1) to (4), wherein the first balancer and the second balancer each have a solid shaft extending in the axial direction and one or more weights disposed on the outer surface of the solid shaft.

[0110] (6) A tool head according to any one of (1) to (5), wherein at least a portion of the first balancer is positioned radially inward of the tool arbor.

[0111] (7)(6) The tool head according to (6), wherein the tool arbor has a small diameter cylindrical portion inserted radially inward of the tool, a first cylindrical portion positioned on one side in the axial direction of the small diameter cylindrical portion and having a larger diameter than the small diameter cylindrical portion, and a first enlarged diameter portion connecting the small diameter cylindrical portion and the first cylindrical portion, the outer surface of the first balancer is in contact with the inner surface of the first cylindrical portion, and the first balancer is in contact with or opposite the first enlarged diameter portion in the axial direction.

[0112] (8)(7) The tool head further comprises a first collector member disposed on one axial side of the tool arbor and holding a conductor connected to the first balancer, wherein the tool arbor has a first tapered surface inclined with respect to the axial and radial directions, and the first collector member is in contact with the first tapered surface.

[0113] (9) A tool head according to any one of (1) to (8), further comprising a counter flange connected to the tool arbor on the other axial side of the tool, wherein at least a portion of the second balancer is positioned radially inward of the counter flange.

[0114] A tool head according to (10)(9), wherein the counter flange has a connecting portion inserted radially inward of the tool arbor, a second cylindrical portion disposed on the other axial side of the connecting portion and having a larger diameter than the connecting portion, and a second enlarged diameter portion connecting the connecting portion and the second cylindrical portion, the outer surface of the second balancer contacts the inner surface of the second cylindrical portion, and the second balancer contacts or faces the second enlarged diameter portion in the axial direction.

[0115] (11)(10) tool head, further comprising a second collector member disposed on the other axial side of the counter flange and holding a conductor connected to the second balancer, wherein the counter flange has a second tapered surface inclined with respect to the axial and radial directions, and the second collector member is in contact with the second tapered surface.

[0116] A tool head according to (12), (10), or (11), wherein the connecting portion has a support mechanism for supporting the tool arbor.

[0117] (13) A tool head according to any one of (1) to (12), wherein the first spindle has a first flow path extending in the axial direction.

[0118] (14) A tool head according to any one of (1) to (13), wherein the second spindle has a second flow path extending in the axial direction.

[0119] (15) A tool head according to any one of (1) to (14), further comprising a first housing for housing the first spindle, wherein the radially outer end of the first balancer is positioned radially inward from the radially outer end of the first housing.

[0120] A tool head according to (16)(15), wherein at least a portion of the first balancer is positioned radially inward of the first housing.

[0121] (17) A tool head according to any one of (1) to (16), further comprising a second housing for housing the second spindle, wherein the radially outer end of the second balancer is positioned radially inward from the radially outer end of the second housing.

[0122] (18)(17) A tool head, wherein at least a portion of the second balancer is positioned radially inward of the second housing.

[0123] (19) A tool head according to any one of (1) to (18), further comprising a first bearing supporting the first spindle, wherein the radially outer end of the first balancer is positioned radially inward from the radially inner end of the first bearing.

[0124] (20) A tool head according to any one of (1) to (19), further comprising a second bearing supporting the second spindle, wherein the radially outer end of the second balancer is positioned radially inward from the radially inner end of the second bearing.

[0125] (21) A tool head as described in any one of (1) to (20), wherein the tool is a grinding wheel.

[0126] (22) A machine tool equipped with a tool head as described in any one of (1) through (21).

[0127] (23) A tool arbor formed to extend along a rotation axis and having a cylindrical tool held on its outer circumferential surface, wherein one axial end of the tool arbor is configured to accommodate at least a portion of a first balancer radially inward, and the other axial end of the tool arbor is configured to be fixed coaxially with the tool arbor to a counter flange capable of accommodating at least a portion of a second balancer radially inward, the tool being held between the axial end and the other axial end, and at least a portion of the first balancer being positioned radially inward from the outer circumferential surface.

[0128] A tool arbor according to (24)(23), wherein at one axial end, it has a first cylindrical portion on its inner surface that holds the first balancer, and the inner surface of the first cylindrical portion is positioned radially inward from the radially outer end of the tool.

[0129] A tool arbor as described in (25)(23), comprising: a small-diameter cylindrical portion inserted radially inward of the tool; a first cylindrical portion disposed on one side in the axial direction of the small-diameter cylindrical portion and having a larger diameter than the small-diameter cylindrical portion; and a first enlarged diameter portion connecting the small-diameter cylindrical portion and the first cylindrical portion, wherein the outer surface of the first balancer is in contact with the inner surface of the first cylindrical portion, and the first balancer is in contact with or facing the first enlarged diameter portion in the axial direction.

[0130] A tool arbor according to (26)(23), wherein the tool arbor has a solid columnar portion that is inserted radially inward of the tool.

[0131] A tool arbor according to (27)(23), wherein the tool arbor has a hollow, small-diameter cylindrical portion that is inserted radially inward into the tool.

[0132] A tool arbor according to any one of (28)(23) to (27), wherein the tool is a grinding wheel.

[0133] A tool unit comprising a tool arbor as described in any one of (29)(23) to (28), a first balancer fixed to one axial end, a counter flange fixed to the other axial end, a second balancer fixed to the counter flange, and a tool held on the outer circumferential surface. [Industrial applicability]

[0134] This invention can be used in tool heads and machine tools. [Explanation of Symbols]

[0135] 1: Machine tool 9: Work 10: Workpiece rotation mechanism 20: Tool head 21: Tool arbor 22: Counterflange 23: First spindle unit 24: Second spindle unit 25: First Balancer 25E: Radial outer end of the first balancer 26: Second Balancer 26E: Radial outer end of the second balancer 27: First collector member 28: Second collector member 30: Movement mechanism 31: 1st movement mechanism 32:Second movement mechanism 33:Third movement mechanism 40: Control Unit 50:Tools 51: Groove 60: Tool Unit 90: Bed 91: Teeth 211: Small diameter cylindrical part 211a: Outer surface 212: First cylindrical part 213: 1st enlarged diameter part 214: First flange section 215: First tapered surface 216: Columnar part 221: Connection part 222: Second cylindrical part 223:Second enlarged diameter part 224: Second flange section 225: Second tapered surface 231: Housing No. 1 232: First spindle 233: First bearing 234: Motor 235: First channel 236: Vibration sensor 241: Second Housing 242: Second spindle 243: Second bearing 245: Second channel 251: Solid shaft of the first balancer 252: Weight of the first balancer 261: Solid shaft for the second balancer 262: Weight of the second balancer A: Rotation axis D: Axial direction X1: Work axis X2: Tool axis

Claims

1. A cylindrical tool arbor extending axially along the axis of rotation, A cylindrical tool held on the outer surface of the tool arbor, A first spindle rotatably supports the unit including the tool arbor on one axial side of the tool, A second spindle rotatably supports the unit including the tool arbor on the other axial side of the tool, A first balancer that corrects the mass balance around the rotation axis on one side in the axial direction from the tool, A second balancer is provided on the other axial side of the tool, which corrects the mass balance around the rotation axis, A tool head equipped with, The tool arbor, the tool, the first spindle, the second spindle, the first balancer, and the second balancer are arranged coaxially with the rotation axis. At least a portion of the first balancer is positioned axially between the tool and the first spindle, At least a portion of the second balancer is positioned axially between the tool and the second spindle, A tool head wherein at least a portion of the first balancer is positioned radially inward from the radially inward end of the tool.

2. A tool head according to claim 1, The radial outer end of the first balancer is positioned radially inward from the radial outer end of the tool, in the tool head.

3. A tool head according to claim 1, A tool head wherein at least a portion of the second balancer is positioned radially inward from the radially inward end of the tool.

4. A tool head according to claim 3, The radial outer end of the second balancer is positioned radially inward from the radial outer end of the tool head.

5. A tool head according to any one of claims 1 to 4, The first balancer and the second balancer are, A solid shaft extending in the axial direction, One or more weights are arranged on the outer surface of the solid shaft, A tool head having

6. A tool head according to any one of claims 1 to 4, At least a portion of the first balancer is a tool head positioned radially inward of the tool arbor.

7. A tool head according to claim 6, The aforementioned tool arbor is A small diameter cylindrical portion inserted radially inward into the tool, A first cylindrical portion is positioned on one side in the axial direction from the aforementioned small-diameter cylindrical portion and has a larger diameter than the aforementioned small-diameter cylindrical portion, A first enlarged diameter portion connecting the small diameter cylindrical portion and the first cylindrical portion, It has, The outer surface of the first balancer is in contact with the inner surface of the first cylindrical portion. The first balancer is a tool head that contacts or faces the first enlarged diameter portion in the axial direction.

8. A tool head according to claim 7, A first collector member is positioned on one axial side of the tool arbor and holds the conductor connected to the first balancer. Furthermore, The tool arbor has a first tapered surface that is inclined with respect to the axial and radial directions, A tool head in which the first collector member contacts the first tapered surface.

9. A tool head according to any one of claims 1 to 4, A counter flange connected to the tool arbor on the other axial side of the tool. Furthermore, At least a portion of the second balancer is a tool head positioned radially inward of the counter flange.

10. A tool head according to claim 9, The aforementioned counter flange is A connecting portion inserted radially inward of the tool arbor, A second cylindrical portion is located on the other side in the axial direction from the aforementioned connecting portion and has a larger diameter than the aforementioned connecting portion, A second enlarged diameter portion connects the aforementioned connecting portion and the second cylindrical portion, It has, The outer surface of the second balancer is in contact with the inner surface of the second cylindrical portion. The second balancer is a tool head that contacts or faces the second enlarged diameter portion in the axial direction.

11. A tool head according to claim 10, A second collector member is positioned on the other axial side of the counter flange and holds the conductor connected to the second balancer. Furthermore, The counter flange has a second tapered surface that is inclined with respect to the axial and radial directions. A tool head in which the second collector member contacts the second tapered surface.

12. A tool head according to claim 10, The connecting portion is a tool head having a support mechanism for supporting the tool arbor.

13. A tool head according to any one of claims 1 to 4, The first spindle is a tool head having a first flow path extending in the axial direction.

14. A tool head according to any one of claims 1 to 4, The second spindle is a tool head having a second flow path extending in the axial direction.

15. A tool head according to any one of claims 1 to 4, First housing for housing the first spindle Furthermore, The radial outer end of the first balancer is positioned radially inward from the radial outer end of the first housing, and this is a tool head.

16. A tool head according to claim 15, At least a portion of the first balancer is a tool head positioned radially inward of the first housing.

17. A tool head according to any one of claims 1 to 4, Second housing housing the second spindle Furthermore, The tool head is positioned such that the radially outer end of the second balancer is radially inward from the radially outer end of the second housing.

18. A tool head according to claim 17, At least a portion of the second balancer is a tool head positioned radially inward of the second housing.

19. A tool head according to any one of claims 1 to 4, The first bearing supporting the first spindle Furthermore, The tool head is positioned such that the radially outer end of the first balancer is radially inward from the radially inner end of the first bearing.

20. A tool head according to any one of claims 1 to 4, The second bearing supporting the second spindle Furthermore, The tool head is positioned such that the radially outer end of the second balancer is located radially inward from the radially inner end of the second bearing.

21. A tool head according to any one of claims 1 to 4, The aforementioned tool is a grinding wheel, or a tool head.

22. A machine tool comprising the tool head described in any one of claims 1 to 4.

23. A tool arbor formed to extend along a rotation axis, with a cylindrical tool held on its outer surface, The axial end of the tool arbor is configured to accommodate at least a portion of the first balancer radially inward, The other axial end of the tool arbor is configured such that a counter flange capable of housing at least a portion of the second balancer radially inward can be fixed coaxially with the tool arbor. The tool is held between the axial end and the other axial end. A tool arbor in which at least a portion of the first balancer is positioned radially inward from the outer circumferential surface.

24. A tool arbor according to claim 23, At one end in the axial direction, the first cylindrical portion holds the first balancer on its inner surface. It has, The inner surface of the first cylindrical portion is a tool arbor, which is positioned radially inward from the radially outer end of the tool.

25. A tool arbor according to claim 23, The tool comprises a small-diameter cylindrical portion inserted radially inward, A first cylindrical portion is positioned on one side in the axial direction from the aforementioned small-diameter cylindrical portion and has a larger diameter than the aforementioned small-diameter cylindrical portion, A first enlarged diameter portion connecting the small diameter cylindrical portion and the first cylindrical portion, It has, The outer surface of the first balancer is in contact with the inner surface of the first cylindrical portion. The first balancer is a tool arbor that contacts or faces the first enlarged diameter portion in the axial direction.

26. A tool arbor according to claim 23, A solid columnar portion inserted radially inward of the tool A tool arbor having a tool arbor.

27. A tool arbor according to claim 23, A hollow, small-diameter cylindrical portion inserted radially inward into the tool. A tool arbor having a tool arbor.

28. A tool arbor according to any one of claims 23 to 27, The aforementioned tool is a grinding stone, a tool arbor.

29. A tool arbor according to any one of claims 23 to 27, The first balancer fixed to one end in the axial direction, The counter flange fixed to the other end in the axial direction, The second balancer fixed to the counter flange, The tool held on the outer peripheral surface, A tool unit equipped with these tools.

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