Grinding Tools

Abstract

To provide a grinding tool that suppresses variations in the pressing force of a grinding stone against a workpiece. [Solution] The grinding tool comprises a housing (80), a slider (71) extending from the inside to the outside of the housing (80) and supported by the housing (80) so as to be slidable in the axial direction of a central axis (210) of the housing (80), a grinding wheel (50) arranged outside the housing (80) and attached to the slider (71), and an elastic member (90) that applies an elastic force to the slider (71) in the axial direction of the central axis (210) of the housing (80).

Description

[Technical Field]

[0001] The present invention relates to a grinding tool. [Background technology]

[0002] For example, Japanese Patent No. 7514257 (Patent Document 1) discloses a machine tool equipped with a work spindle and a tool spindle. The work spindle holds a workpiece having a spherical portion, and the tool spindle holds a cup-shaped grinding wheel for grinding the spherical portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7514257 specification Summary of the Invention [Problem to be solved by the invention]

[0004] In the machine tool disclosed in Patent Document 1, the workpiece and cup-shaped grinding wheel are rotated by the workpiece spindle and tool spindle, respectively, while the cup-shaped grinding wheel is pressed against the workpiece to grind the spherical portion of the workpiece. However, if the cup-shaped grinding wheel wears out, if thermal displacement occurs in the tool spindle, or if the workpiece dimensions before grinding contain errors, variations will occur in the pressing force of the cup-shaped grinding wheel against the workpiece.

[0005] An object of the present invention is to provide a grinding tool that suppresses variations in the pressing force of a grinding stone against a workpiece. [Means for solving the problem]

[0006] A grinding tool according to the present invention comprises a housing, a slider extending from the inside to the outside of the housing and supported by the housing so as to be slidable in the axial direction of the central axis of the housing, a grinding wheel disposed outside the housing and attached to the slider, and an elastic member that applies an elastic force to the slider in the axial direction of the central axis of the housing. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a grinding tool that suppresses variations in the pressing force of the grinding stone against the workpiece. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. [Figure 2] 1 is a perspective view showing a grinding tool according to an embodiment of the present invention. [Figure 3] FIG. 3 is a cross-sectional view showing the grinding tool in FIG. 2 (before machining the workpiece). [Figure 4] FIG. 3 is a cross-sectional view showing the grinding tool in FIG. 2 (during machining of a workpiece). [Figure 5] FIG. 3 is an exploded view showing the grinding tool in FIG. 2. [Figure 6] 5 is a cross-sectional view showing a modified example of a coolant supply hole in the grinding tool in FIG. 4. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the accompanying drawings, in which the same or corresponding elements are designated by the same reference numerals.

[0010] Fig. 1 is a front view of a machine tool, showing the interior of the machine tool through a cover body that forms the exterior of the machine tool.

[0011] Referring to Figure 1, machine tool 100 is a multi-tasking machine equipped with both a milling function for machining a workpiece by bringing a rotating tool into contact with a stationary workpiece, and a turning function for machining a workpiece by bringing a tool into contact with a rotating workpiece. Machine tool 100 is an NC (Numerically Controlled) machine tool in which various operations for machining a workpiece are automated by numerical control using a computer. As an example, grinding tool 10 in this embodiment can be applied to grinding a workpiece using machine tool 100, which is a multi-tasking machine.

[0012] First, we will explain the configuration of machine tool 100. In this specification, for the sake of convenience in explaining the configuration of machine tool 100, an axis that is parallel to the rotation axis of the workpiece and extends horizontally will be referred to as the "Z-axis," an axis that is perpendicular to the Z-axis and extends horizontally will be referred to as the "Y-axis," and an axis that extends vertically will be referred to as the "X-axis."

[0013] Machine tool 100 has a bed 16, a first workpiece spindle 21, a second workpiece spindle 26, a tool spindle 41, and a tool rest 30. First workpiece spindle 21, second workpiece spindle 26, tool spindle 41, and tool rest 30 are arranged in a machining area 160. Machining area 160 is a space where workpiece machining is performed, and is sealed by a cover (not shown) to prevent foreign matter such as chips or cutting oil generated during workpiece machining from leaking outside of machining area 160.

[0014] The bed 16 is a base member for supporting the first work spindle 21, the second work spindle 26, the tool spindle 41, the tool rest 30, etc., and is installed on the floor of a factory, etc. The bed 16 is made of metal such as cast iron.

[0015] The first work spindle 21 and the second work spindle 26 are capable of holding a workpiece. The first work spindle 21 is driven by a motor to rotate about a central rotation axis 110 parallel to the Z axis. The first work spindle 21 is provided with a chuck 22 that operates by hydraulic pressure or the like and that detachably holds the workpiece.

[0016] The second work spindle 26 is disposed opposite the first work spindle 21 in the Z-axis direction. The second work spindle 26 is driven by a motor to rotate about a rotation center axis 120 that is parallel to the Z-axis and extends in a straight line with the rotation center axis 110. The second work spindle 26 is provided with a chuck 27 that is operated by hydraulic pressure or the like and that detachably holds a workpiece.

[0017] The first workpiece spindle 21 is fixed to the bed 16. The second workpiece spindle 26 is movable in the Z-axis direction by various feed mechanisms, guide mechanisms, and motors.

[0018] The tool spindle 41 can hold a tool. The tool spindle 41 is driven by a motor to rotate around a rotation center axis 140 parallel to the X-axis in a reference posture described below. The tool spindle 41 has a built-in clamping mechanism (not shown) that operates by hydraulic pressure or the like and that detachably holds a tool.

[0019] The tool spindle 41 can also rotate about a rotation center axis 130 that is parallel to the Y axis (B-axis rotation). The rotation center axis 130 intersects with a rotation center axis 140. The rotation range of the tool spindle 41 is, for example, within a range of ±120° based on a reference attitude (the attitude of the tool spindle 41 shown in FIG. 1) in which the spindle end surface 42 of the tool spindle 41 faces in the −X-axis direction (downward).

[0020] The tool spindle 41 can be moved in the X-axis, Y-axis, and Z-axis directions by various feed mechanisms, guide mechanisms, and motors. Although not shown in Fig. 1, an automatic tool changer (ATC) for automatically changing the tool held by the tool spindle 41 and a tool magazine for storing replacement tools are provided around the first work spindle 21.

[0021] Tool rest 30 can hold multiple tools. Tool rest 30 is a turret-type tool rest that moves multiple tools in a circumferential direction around a central rotation axis 150, indexing the tools to be used for machining to a predetermined workpiece machining position. Central rotation axis 150 extends parallel to the central axis of rotation of the workpiece in machine tool 100.

[0022] The tool post 30 has a swivel unit (turret) 31 and a tool post base 32. The swivel unit 31 is attached to the tool post base 32. The swivel unit 31 protrudes from the tool post base 32 in the axial direction of a swivel central axis 150. The swivel unit 31 is supported by the tool post base 32 so as to be rotatable about the swivel central axis 150. The swivel unit 31 swivels about the swivel central axis 150 by transmitting rotation from a motor (not shown) mounted on the tool post base 32. A plurality of tools are attached to the swivel unit 31 and lined up in the circumferential direction around the swivel central axis 150.

[0023] The tool rest 30 can be moved in the X-axis direction and the Z-axis direction by various feed mechanisms, guide mechanisms, and motors.

[0024] 1, a grinding tool 10 according to the present embodiment is held by a tool spindle 41. A workpiece W to be ground by the grinding tool 10 is held by a first workpiece spindle 21. The workpiece W has a spherical surface 170.

[0025] During grinding of the workpiece W, the workpiece W is rotated around the rotation center axis 110 by the first workpiece spindle 21, while the grinding tool 10 is rotated around the rotation center axis 140 by the tool spindle 41. By moving the tool spindle 41 and rotating it around the B axis, a grinding stone 50 of the grinding tool 10 (described later) is pressed against a spherical surface 170 of the workpiece W. By moving the tool spindle 41 in the X-axis and Z-axis directions and rotating the tool spindle 41 around the B axis in synchronization with this movement, the grinding stone 50 is moved along the spherical surface 170 of the workpiece W while being pressed against the spherical surface 170.

[0026] For example, the rotation speed of the workpiece W is in the range of 100 / min to 500 / min, and the rotation speed of the grinding tool 10 is in the range of 2500 / min to 4000 / min. The rotation speed of the grinding tool 10 is higher than the rotation speed of the workpiece W.

[0027] Fig. 2 is a perspective view showing a grinding tool in an embodiment of the present invention. Fig. 3 is a cross-sectional view showing the grinding tool in Fig. 2 (before machining a workpiece). Fig. 4 is a cross-sectional view showing the grinding tool in Fig. 2 (during machining a workpiece). Fig. 5 is an exploded assembly view showing the grinding tool in Fig. 2.

[0028] 2 to 5 show a central axis 210, which is an imaginary straight line. The central axis 210 corresponds to the central axis of the housing 80, which will be described later. The grinding tool 10 extends along the central axis 210. The central axis 210 corresponds to the central axis of rotation of the grinding tool 10. The grinding tool 10 rotates around the central axis 210 by the tool spindle 41. When the grinding tool 10 is held by the tool spindle 41, the central axis 210 extends in a straight line in alignment with the central axis 140 of rotation of the tool spindle 41.

[0029] 2 to 5 show the front side and rear side in the axial direction of central axis 210. The front side in the axial direction of central axis 210 corresponds to the side of grinding tool 10 where grinding wheel 50 is located, and the rear side in the axial direction of central axis 210 corresponds to the opposite side from the front side. A workpiece to be ground is placed at a position on the front side of grinding tool 10 in the axial direction of central axis 210, and tool spindle 41, which is a device for holding grinding tool 10, is placed at a position on the rear side of grinding tool 10 in the axial direction of central axis 210.

[0030] 2 to 5, grinding tool 10 in this embodiment is held by tool spindle 41 via tool holder 91. Tool holder 91 holds grinding tool 10 and is clamped by tool spindle 41. Tool holder 91 has a hollow shape with a through hole 250 extending along central axis 210. As shown in FIG. 2, tool holder 91 has a shank 93. The shank 93 of tool holder 91 is clamped by tool spindle 41. The shank 93 is arranged on one end side of tool holder 91 along central axis 210. As an example, FIG. 2 shows tool holder 91 in which shank 93 is a CAPTO shank. The size of the shank is not particularly limited.

[0031] The grinding tool 10 includes a housing 80 , a slider 71 , a grindstone 50 , and an elastic member 90 .

[0032] Housing 80 extends around central axis 210. Slider 71 extends from the inside of housing 80 to the outside. Slider 71 is supported by housing 80 so as to be slidable in the axial direction of central axis 210. Grindstone 50 is disposed outside housing 80. Grindstone 50 is attached to slider 71. Elastic member 90 applies an elastic force to slider 71 in the axial direction of central axis 210.

[0033] The tool holder 91 (shank 93) is disposed at one end of the grinding tool 10 along the central axis 210, and the grinding wheel 50 is disposed at the other end of the grinding tool 10 along the central axis 210. The grinding wheel 50 has a grinding wheel case 52. The grinding wheel case 52 has an overall cylindrical shape centered on the central axis 210.

[0034] Grindstone case 52 has a front portion 52f and a rear portion 52r. Front portion 52f and rear portion 52r are aligned in the listed order from the front side to the rear side in the axial direction of central axis 210. The inner diameter of rear portion 52r (diameter of the inner peripheral surface of rear portion 52r) centered on central axis 210 is smaller than the inner diameter of front portion 52f (diameter of the inner peripheral surface of front portion 52f) centered on central axis 210. A radial step is provided between the inner peripheral surface of front portion 52f and the inner peripheral surface of rear portion 52r, centered on central axis 210.

[0035] The grinding wheel 50 further has a grinding wheel body 53. The grinding wheel body 53 is the part that grinds the workpiece, and contains abrasive grains and a binder that binds the abrasive grains together. The grinding wheel body 53 is supported by the grinding wheel case 52. The grinding wheel body 53 is connected to the front end of the grinding wheel case 52 (front part 52f). The grinding wheel body 53 extends in the circumferential direction about the central axis 210. The grinding wheel body 53 extends intermittently in the circumferential direction about the central axis 210.

[0036] Grindstone body 53 has contact surface 54. Contact surface 54 is provided at the corner between the inner circumferential surface of grindstone body 53 and the front end face of grindstone body 53. Contact surface 54 has a diameter (inner diameter) that increases with increasing distance from grindstone case 52 in the axial direction of central axis 210.

[0037] The housing 80 has an overall cylindrical shape centered on the central axis 210. The housing 80 has a flange portion 81 and a housing main body 82. The housing main body 82 has a cylindrical shape centered on the central axis 210. The flange portion 81 is connected to the front end of the housing main body 82 (a front portion 82f described below). The flange portion 81 spreads out in a brim-like shape from the housing main body 82 centered on the central axis 210. The flange portion 81 has a ring shape centered on the central axis 210.

[0038] Housing main body 82 has a front portion 82f and a rear portion 82r. Front portion 82f and rear portion 82r are aligned in the listed order from the front side to the rear side in the axial direction of central axis 210. The inner diameter of front portion 82f (diameter of the inner circumferential surface of front portion 82f) centered on central axis 210 is larger than the inner diameter of rear portion 82r (diameter of the inner circumferential surface of rear portion 82r) centered on central axis 210.

[0039] The housing 80 is detachable from the tool holder 91. When the housing 80 is attached to the tool holder 91, the housing main body 82 is disposed in the through-hole 250 of the housing 80, and the flange portion 81 abuts against the tool holder 91 in the axial direction of the central axis 210.

[0040] The slider 71 has an overall cylindrical shape centered on a central axis 210. The slider 71 extends in the axial direction of the central axis 210 from the inside to the outside of the housing 80. The grindstone 50 is attachable to and detachable from the slider 71.

[0041] The slider 71 has a first slider portion 72, a second slider portion 75, and a third slider portion 77. The first slider portion 72, the second slider portion 75, and the third slider portion 77 are arranged in the listed order from the front side to the rear side in the axial direction of the central axis 210.

[0042] The first slider portion 72 and the third slider portion 77 are disposed outside the housing 80. The housing 80 is disposed between the first slider portion 72 and the third slider portion 77 in the axial direction of the central shaft 210. The first slider portion 72 is disposed at a position protruding from the front end of the housing 80 in the axial direction of the central shaft 210. The third slider portion 77 is disposed at a position protruding from the rear end of the housing 80 in the axial direction of the central shaft 210.

[0043] An internal thread 72s is provided on the inner peripheral surface of the first slider portion 72. An external thread 77s is provided on the outer peripheral surface of the third slider portion 77.

[0044] The second slider portion 75 extends from the inside to the outside of the housing 80. The second slider portion 75 protrudes from the front end of the housing 80 in the axial direction of the central axis 210, and is connected to the first slider portion 72 at its protruding tip.

[0045] The second slider portion 75 has a large diameter portion 75j and a small diameter portion 75k. The large diameter portion 75j and the small diameter portion 75k are aligned in the listed order from the front side to the rear side in the axial direction of the central axis 210. The outer diameter of the large diameter portion 75j (the diameter of the outer peripheral surface of the large diameter portion 75j) centered on the central axis 210 is larger than the diameter of the small diameter portion 75k (the diameter of the outer peripheral surface of the small diameter portion 75k) centered on the central axis 210. A radial step is provided between the outer peripheral surfaces of the large diameter portion 75j and the small diameter portion 75k, centered on the central axis 210.

[0046] The second slider portion 75 is supported by the housing 80 so as to be slidable in the axial direction of the central axis 210. The outer peripheral surface of the large diameter portion 75j is in sliding contact with the flange portion 81 and the inner peripheral surface of the front portion 82f of the housing main body 82. The outer peripheral surface of the small diameter portion 75k is in sliding contact with the inner peripheral surface of the rear portion 82r of the housing main body 82.

[0047] A seal member 98 is attached to the outer peripheral surface of the small diameter portion 75k. The seal member 98 extends annularly about the central axis 210. The seal member 98 seals the gap between the small diameter portion 75k and the rear portion 82r of the housing main body 82.

[0048] An accommodation space 220 is formed inside the housing 80. The accommodation space 220 is formed between the small diameter portion 75k and the front portion 82f of the housing main body 82 in the radial direction centered on the central axis 210. The accommodation space 220 is formed between the large diameter portion 75j and the rear portion 82r of the housing main body 82 in the axial direction of the central axis 210.

[0049] The first slider portion 72 has a front portion 72f, an intermediate portion 72m, and a rear portion 72r. The front portion 72f, the intermediate portion 72m, and the rear portion 72r are arranged in this order from the front side to the rear side in the axial direction of the central axis 210. The outer diameter of the intermediate portion 72m (the diameter of the outer peripheral surface of the intermediate portion 72m) centered on the central axis 210 is larger than the outer diameter of the front portion 72f (the diameter of the outer peripheral surface of the front portion 72f) centered on the central axis 210. The outer diameter of the rear portion 72r (the diameter of the outer peripheral surface of the rear portion 72r) centered on the central axis 210 is larger than the outer diameter of the intermediate portion 72m (the diameter of the outer peripheral surface of the intermediate portion 72m) centered on the central axis 210.

[0050] The slider 71 (first slider portion 72) is provided with a plurality of notches 74. The plurality of notches 74 are provided at intervals from one another in the circumferential direction centered on the central axis 210. The plurality of notches 74 are provided in the rear portion 72r. The notches 74 open in the axial direction of the central axis 210 facing a base 87 of a detent 86 (described later), and have a notch shape recessed from the outer peripheral surface of the rear portion 72r.

[0051] The grinding tool 10 further includes a presser plate 61. The presser plate 61 is disposed outside the housing 80. The presser plate 61 presses the grindstone case 52 against the slider 71 in the axial direction of the central axis 210.

[0052] The presser plate 61 has a flange portion 62 and a threaded portion 63. The threaded portion 63 has a cylindrical shape centered on the central axis 210. The threaded portion 63 is composed of a male thread extending along the central axis 210. The flange portion 62 is continuous with the front end portion of the threaded portion 63. The flange portion 62 spreads out from the threaded portion 63 in a flange-like shape centered on the central axis 210. The flange portion 62 has a ring shape centered on the central axis 210.

[0053] The grindstone 50 is attached to the slider 71 by a presser plate 61. The rear portion 52r of the grindstone case 52 is fitted onto the outer periphery of the front portion 72f of the first slider portion 72. The rear portion 52r abuts against the middle portion 72m of the first slider portion 72 in the axial direction of the central axis 210.

[0054] The threaded portion 63 is connected to the front end of the slider 71. The threaded portion 63 is disposed inside the first slider portion 72 and is threadedly engaged with the female thread 72s. The flange portion 62 abuts against a step between the inner peripheral surface of the front portion 52f and the inner peripheral surface of the rear portion 52r in the axial direction of the central axis 210. The rear portion 52r is sandwiched between the flange portion 62 and the intermediate portion 72m in the axial direction of the central axis 210 by the tightening force of the threaded portion 63 against the female thread 72s.

[0055] The elastic member 90 is made of a coil spring. The elastic member 90 extends spirally around the central axis 210. The elastic member 90 is disposed inside the housing 80. The elastic member 90 is accommodated in the accommodation space 220 in a state in which it is compressed and deformed in the axial direction of the central axis 210. The elastic member 90 applies an elastic force to the slider 71 from the rear side to the front side in the axial direction of the central axis 210.

[0056] The grinding tool 10 further includes a nut 96. The nut 96 is disposed outside the housing 80. The nut 96 is fitted onto the outer periphery of the third slider portion 77 and is threaded onto the male threads 77s. The nut 96 abuts against the housing 80 (the rear portion 82r of the housing main body 82) in the axial direction of the central axis 210, thereby preventing the slider 71, to which the elastic force from the elastic member 90 is applied, from slipping out forward in the axial direction of the central axis 210.

[0057] The grinding tool 10 further includes a detent 86. The detent 86 is provided on the housing 80. The detent 86 restricts the relative rotation of the housing 80 and the slider 71.

[0058] The anti-rotation device 86 has a base 87 and a plurality of protrusions 88. The base 87 has a ring shape centered on a central axis 210. The base 87 is disposed between the flange 81 and the first slider portion 72 in the axial direction of the central axis 210. The base 87 is fitted onto the outer periphery of the second slider portion 75 (large diameter portion 75j). The base 87 is fastened to the flange 81 using a plurality of bolts B (see FIG. 5).

[0059] The multiple protrusions 88 are provided at intervals from one another in the circumferential direction centered on central axis 210. The protrusions 88 protrude forward from flange portion 81 in the axial direction of central axis 210. The multiple protrusions 88 are respectively disposed in the multiple cutouts 74. By disposing the multiple protrusions 88 in the multiple cutouts 74, relative rotation of housing 80 and slider 71 about central axis 210 is restricted. The protrusions 88 are slidable relative to the cutouts 74 in the axial direction of central axis 210.

[0060] A seal member 97 is attached to the end face of the flange portion 81. The seal member 97 extends in an annular shape centered on the central axis 210. A seal member 98 seals the gap between the base portion 87 and the flange portion 81.

[0061] A coolant circulation hole 230 is provided in the presser plate 61. The coolant circulation hole 230 is a through-hole that extends along the central axis 210 and passes through the presser plate 61. The front end of the coolant circulation hole 230 communicates with the space inside the grinding wheel 50 (front portion 52f). A coolant circulation hole 240 is provided in the slider 71. The coolant circulation hole 240 is a through-hole that extends along the central axis 210 and passes through the slider 71. The front end of the coolant circulation hole 240 communicates with the space inside the grinding wheel 50 (front portion 52f) through the coolant circulation hole 230. The rear end of the coolant circulation hole 240 communicates with a through-hole 250 in the tool holder 91.

[0062] 3, before workpiece machining, when the grinding wheel 50 is not in contact with the workpiece W, the slider 71 is pushed forward in the axial direction of the central shaft 210 by the elastic force of the elastic member 90. At this time, the first slider portion 72 (rear portion 72r) of the slider 71 is spaced apart from the base 87 of the anti-rotation stopper 86 in the axial direction of the central shaft 210. The nut 96 abuts against the housing 80 (rear portion 82r of the housing main body 82) in the axial direction of the central shaft 210.

[0063] 4, during grinding of the workpiece W, the grinding tool 10 is positioned relative to the workpiece W so that the center of the spherical surface 170 of the workpiece W is located on an extension of the central axis 210 and the contact surface 54 is pressed against the spherical surface 170. At this time, the slider 71 is pushed rearward in the axial direction of the central axis 210 while resisting the elastic force of the elastic member 90. The elastic force of the elastic member 90 is applied from the grinding wheel 50 to the spherical surface 170 of the workpiece W.

[0064] The first slider portion 72 (rear portion 72r) of the slider 71 moves closer to the base portion 87 of the anti-rotation stopper 86 in the axial direction of the central shaft 210. At this time, the protrusion 88 and the notch 74 move relatively in the axial direction of the central shaft 210, while maintaining the state in which the protrusion 88 is disposed in the notch 74. The second slider portion 75 (small diameter portion 75k) of the slider 71 protrudes from the rear end portion of the housing 80. The nut 96 moves away from the housing 80 (rear portion 82r of the housing main body 82).

[0065] The housing 80 rotates integrally with the tool holder 91, which is clamped by the tool spindle 41, around the central axis 210. The rotation stopper 86 prevents the slider 71 from rotating relative to the housing 80, and the slider 71 also rotates around the central axis 210.

[0066] As the workpiece W is ground, coolant is supplied from the tool spindle 41 to the grinding tool 10. The coolant from the tool spindle 41 passes through the through-hole 250, the coolant circulation hole 240, and the coolant circulation hole 230 of the tool holder 91 in this order, and enters the space within the grinding wheel 50. The coolant is supplied to the contact surface 54 of the grinding wheel body 53 that comes into contact with the spherical surface 170 of the workpiece W.

[0067] To summarize the configuration of grinding tool 10 in the embodiment of the present invention described above, grinding tool 10 in the present embodiment comprises housing 80, slider 71 extending from the inside to the outside of housing 80 and supported by housing 80 so as to be slidable in the axial direction of central axis 210 of housing 80, grinding wheel 50 arranged outside housing 80 and attached to slider 71, and elastic member 90 that applies an elastic force to slider 71 in the axial direction of central axis 210 of housing 80.

[0068] With this configuration, when grinding the workpiece W, the slider 71 slides in the axial direction of the central axis 210 while resisting the elastic force from the elastic member 90. As a result, even if wear of the grinding wheel 50 progresses or a dimensional error occurs in the workpiece, the elastic force of the elastic member 90 is applied from the grinding wheel 50 to the workpiece W, so that variation in the pressing force of the grinding wheel 50 against the workpiece W can be suppressed.

[0069] Furthermore, grinding wheel 50 has a shape that extends in the circumferential direction centered on central axis 210. Slider 71 is provided with coolant flow holes 240 that extend along central axis 210, communicate with the interior of grinding wheel 50, and allow coolant to flow therethrough.

[0070] According to this configuration, the coolant is supplied to the inside of the grinding wheel 50 through the coolant flow holes 240. This allows the coolant to be delivered to the point of the workpiece W being machined by the grinding wheel 50 more efficiently.

[0071] The elastic member 90 is made of a coil spring disposed inside the housing 80. With this configuration, the elastic member 90 can be prevented from being exposed to the processing atmosphere.

[0072] The grinding tool 10 also includes a detent 86 that is provided on the housing 80 and is capable of restricting relative rotation between the housing 80 and the slider 71. With this configuration, the relative rotation between the housing 80 and the slider 71 is restricted, thereby enabling the grinding wheel 50 attached to the slider 71 to rotate more reliably.

[0073] Moreover, the grindstone 50 is for spherical grinding. With this configuration, in the grinding tool 10 including the grindstone 50 for spherical grinding, it is possible to suppress variations in the pressing force of the grindstone 50 against the workpiece W.

[0074] Fig. 6 is a cross-sectional view showing a modified example of the coolant supply hole in the grinding tool in Fig. 4. Referring to Fig. 6, in this modified example, a coolant circulation hole 236 is further provided in the presser plate 61. The front end of the coolant circulation hole 236 communicates with the space inside the grinding wheel 50 (front portion 52f). The rear end of the coolant circulation hole 236 communicates with the coolant circulation hole 230.

[0075] The coolant circulation holes 236 extend in a direction oblique to the central axis 210. The distance from the central axis 210 to the coolant circulation holes 236 in the radial direction centered on the central axis 210 increases from the upstream side to the downstream side of the coolant flow in the coolant circulation holes 236. The angle formed by the coolant circulation holes 236 with respect to the central axis 210 may be set so that the contact surface 54 is located on a straight line extending from the coolant circulation holes 236.

[0076] A plurality of coolant circulation holes 236 are formed in the pressing plate 61. The plurality of coolant circulation holes 236 are provided at intervals from one another in the circumferential direction about the central axis 210.

[0077] According to this configuration, it becomes possible to more efficiently deliver the coolant to the point where the workpiece W is machined by the grinding wheel 50, thereby improving the discharge of grinding chips.

[0078] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0079] 10 Grinding tool, 16 Bed, 21 First work spindle, 22, 27 Chuck, 26 Second work spindle, 30 Turret, 31 Swivel section, 32 Turret base, 41 Tool spindle, 42 Spindle end face, 50 Grinding wheel, 52 Grinding wheel case, 52f, 72f, 82f Front section, 52r, 72r, 82r Rear section, 53 Grinding wheel body, 54 Contact surface, 61 Presser plate, 62, 81 Flange section, 63 Threaded section, 71 Slider, 72 First slider section, 72m Middle section, 72s Female thread, 74 Notch, 75 Second slider section, 75j Large diameter section, 75k Small diameter section, 77 Third slider section, 77s Male thread, 80 Housing, 82 Housing body, 86 Anti-rotation section, 87 Base, 88 protrusion, 90 elastic member, 91 tool holder, 93 shank, 96 nut, 97, 98 sealing member, 100 machine tool, 110, 120, 140 rotation center axis, 130, 150 swivel center axis, 160 machining area, 170 spherical surface, 210 central axis, 220 accommodation space, 230, 240 coolant flow hole, 250 through hole, B bolt, W workpiece.

Claims

1. Housing and a slider extending from the inside of the housing to the outside and supported by the housing so as to be slidable in an axial direction of a central axis of the housing; a grindstone disposed outside the housing and attached to a front end of the slider in an axial direction of the central axis of the housing; an elastic member that applies an elastic force to the slider in the axial direction of the central axis of the housing, the slider is provided with a coolant flow hole extending along the central axis of the housing and through which coolant supplied toward the grinding wheel can flow; The slider is disposed at a rear end of the slider in an axial direction of the central axis of the housing, and has an end face through which the coolant flow hole opens.

2. the grindstone has a shape extending in a circumferential direction about the central axis of the housing, 2. The grinding tool according to claim 1, wherein the coolant flow hole communicates with the inside of the grindstone at the front end of the slider.

3. 3. The grinding tool according to claim 1, wherein the elastic member is a coil spring disposed inside the housing.

4. 3. The grinding tool according to claim 1, further comprising a rotation stopper provided on the housing, capable of restricting relative rotation between the housing and the slider.

5. 3. The grinding tool according to claim 1, wherein the grinding wheel is for spherical grinding.

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