JP4463505B2 - Tool attachment for machine tools - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tool attachment used for a machine tool.
[0002]
[Prior art]
In general, in a machine tool such as a grinding machine that grinds the surface of a workpiece, a tool such as a grindstone is mounted on a spindle of a spindle device to grind the surface of the workpiece. However, when a tool is mounted directly on the tip of the spindle, a large tool must be used, so that machining cannot be performed depending on the type of workpiece. For this reason, there is one in which a tool attachment including a small tool that rotates using the rotational motion of the spindle is detachably mounted on the tip of the spindle device. The tool attachment is rotatably supported via a support shaft and a bearing on a tool holder mounted on the housing of the spindle device and a mounting arm provided on the tool holder, and supports the tool. And a power transmission mechanism that is mounted inside the tool holder and transmits the rotational movement of the spindle to the tool.
[0003]
[Problems to be solved by the invention]
However, in the conventional tool attachment, the rotating support cylinder that supports the tool on the outer peripheral surface of the support shaft is supported by the radial ball bearing, and the thrust load of the rotating support cylinder is supported by the hydrostatic bearing mechanism. It was supposed to be. For this reason, there existed a problem that the length dimension to the radial direction and axial direction of a rotation support cylinder became large, and the front-end | tip part (tool holding part) of the said attachment arm enlarged. When the tip end of the mounting arm is enlarged, the tip end of the mounting arm easily interferes with the workpiece when machining the inner peripheral surface of the hole formed inside the workpiece, so that the workability is lowered.
[0004]
The objective of this invention is providing the tool attachment used for the machine tool which can achieve size reduction of the front-end | tip part of the attachment arm of a tool attachment.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the invention according to claim 1 is directed to a tool holder that is detachably mounted on a spindle device of a machine tool, and a static pressure supported by a tip end portion of a tool mounting arm of the tool holder. a supporting shaft for the bearing, the is rotatably supported by the static pressure with respect to the outer peripheral surface of the support shaft, and a rotary support cylinder body can be mounted a tool, provided in the tool holder, and the spindle of the spindle device A power transmission mechanism that is operatively connected to rotate the rotating support cylinder, and fits a grindstone as the tool to the outer peripheral surface of the rotating support cylindrical body in the axial direction with respect to the outer peripheral surface of the support shaft. A pair of hydrostatic bearing surfaces having a taper shape whose diameter changes as it goes is provided on both sides of the grindstone, and the inner circumferential surface of the rotating support cylinder is also tapered corresponding to both hydrostatic bearing surfaces. wherein a pair of hydrostatic bearing surface forming a Jo And summarized in that provided so as to be positioned on opposite sides of the stone.
[0007]
According to a second aspect of the present invention, in the first aspect, the pair of inner and outer hydrostatic bearing surfaces are formed so as to have a larger diameter from the central portion in the axial direction of the support shaft toward the outer side. The gist is that a discharge passage for discharging the fluid that has finished the static pressure operation to the outside is formed inside the shaft, and its inlet is opened in the outer peripheral surface of the intermediate portion of the support shaft.
[0008]
According to a third aspect of the present invention, in the first or second aspect , the tool holder is detachably attached to the front end portion of the housing that supports the spindle of the spindle device and covers the front end portion of the spindle. And a mounting arm mounted on the outer periphery of the case so as to bend when viewed from the axial direction of the spindle.
[0009]
According to a fourth aspect of the present invention, in any one of the first to third aspects, a support shaft is provided on the left side plate and the right side plate provided at the tip of the mounting arm, and the left side plate and the right side plate are It is summarized that an annular groove is formed on the inner side surface for forming a slit that suppresses discharge of the fluid that has entered the peripheral edge portions of both ends of the rotating support cylinder and finished the static pressure operation to the outside. And
[0010]
According to a fifth aspect of the present invention, in any one of the first to fourth aspects, a belt that is hung on a pulley formed on an outer peripheral surface of the rotary support cylinder is hung inside the tool holder. A driving pulley is supported, and a driven pulley is provided in the vicinity of the driving pulley, and the driven pulley is rotationally driven by a driving pulley mounted on the spindle and a belt hung between the driven pulley. The summary is as follows.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a machine tool provided with the tool attachment of the present invention will be described with reference to the drawings.
[0012]
FIG. 5 shows the front of the machine tool, and FIG. 6 shows the plane of the machine tool. As shown in FIG. 5, a workpiece W indexing device 12 is mounted on the upper surface of the bed 11 so as to be positioned at the left end. A work support table 14 is mounted on the turning drive mechanism 13 of the indexing device 12 so as to be rotatable in the horizontal direction around the vertical axis. A workpiece W is supported on the upper surface of the workpiece support table 14, and the workpiece W is indexed and rotated to a desired position by the workpiece support table 14 that is indexed and rotated by the turning drive mechanism 13. The turning drive mechanism 13 is detachably mounted on the bed 11 by a clamp mechanism 15.
[0013]
On the side of the bed 11 (the back side in the direction orthogonal to the paper surface of FIG. 5), there is installed a spindle device 21 that is numerically controlled in the X, Y, and Z directions by an X, Y, and Z drive mechanism (not shown). ing. A tool attachment 22, which will be described in detail later, is detachably mounted on the front surface of the spindle device 21, and the workpiece W is polished by a tool 23 such as a grindstone provided on the tool attachment 22.
[0014]
A guide rail 24 is laid on the upper surface of the bed 11 so as to be positioned to the right of the indexing device 12, and a centering device 25 is installed on the guide rail 24 so as to be capable of reciprocating in the X-axis direction. . Then, the clamping state of the clamping mechanism 15 is released, the indexing device 12 is inverted 90 degrees, and the work chuck 26 is opposed to the core pushing rod 27 of the centering device 25 so that the workpiece chuck 26 and the center pushing While the workpiece W is gripped with the rod 27, the outer peripheral surface of the workpiece W is machined by the tool 23 while the workpiece W is indexed and rotated around the horizontal axis.
[0015]
A rotation support device 31 is mounted on the upper surface of the bed 11 so as to be positioned on the right side of the guide rail 24. The rotation support device 31 includes a rotation drive mechanism 32 fixed to the upper surface of the bed 11 and a rotation table 33 supported on the upper surface of the rotation drive mechanism 32. Then, the tool attachment 22 is removed from the spindle device 21, and the workpiece W supported on the rotary table 33 is machined by another tool (for example, a milling cutter) 35 supported by the tool attachment 34 attached to the spindle device 21. It has become.
[0016]
A tool dressing device 41 is mounted on the upper surface of the bed 11 so as to be positioned on the right side of the rotation support device 31 so as to dress the tool gripped by the tool gripping device 42.
[0017]
Next, the configuration of the tool attachment 22 attached to the spindle device 21 will be described.
FIG. 2 shows the front surface of the tool attachment 22, and FIG. 3 shows a longitudinal section of the tool attachment 22. As shown in FIG. 3, the spindle device 21 is provided with a housing 51, and a spindle 52 is rotatably supported by the housing 51. A tapered portion 52a and a male threaded portion 52b are formed at the tip of the spindle 52, and the driving pulley 53 fitted to the tapered portion 52a is fastened and fixed at a predetermined position by a nut 54 screwed into the male threaded portion 52b. Has been.
[0018]
A bracket 61 is detachably mounted on the front surface of the spindle device 21 by a plurality of bolts 62 shown in FIG. A flange 64a of a case 64 constituting a tool holder is fastened and fixed to the bracket 61 by a bolt 65. As shown in FIG. 2, the case 64 is formed by a cylindrical portion 64b covering the drive pulley 53 attached to the tip of the spindle 52 and a part of the outer peripheral portion of the cylindrical portion 64b bulging outward in the radial direction. It is comprised by the bulging part 64c made.
[0019]
A support plate 66 is attached to the bottom of the bulging portion 64c with bolts 67 in the horizontal direction. As shown in FIG. 4, a bracket 68 is attached to the upper surface of the support plate 66 with bolts 69, and a support shaft 70 is supported on the bracket 68 in parallel with the spindle 52. A pulley 72 is rotatably supported on the support shaft 70 via a bearing 71. A belt 73 is mounted between the driven pulley portion 72a and the driving pulley 53. When the driving pulley 53 is rotated, the pulley 72 is rotated. 72 is rotated. A driving pulley portion 72b for rotating the tool 23 is integrally formed on the outer periphery of the pulley 72.
[0020]
The support plate 66 can be adjusted in position by a horizontal position adjusting mechanism 74 shown in FIG. As shown in FIG. 4, the height of the support shaft 70 and the pulley 72 can be adjusted by a vertical position adjustment mechanism 75 provided between the bracket 68 and the support shaft 70.
[0021]
As shown in FIGS. 2 to 4, a mounting arm 81 is mounted downward on the lower surface of the support plate 66. As shown in FIG. 4, the mounting arm 81 is attached to the left side plate 82 located on the left side, a plurality of spacers 83, 84, 85 joined to the right side surface of the left side plate 82, and the right side surface of the spacer 85. And a right side plate 86. A hydrostatic bearing mechanism 90 that supports the tool 23 is mounted between the lower ends of the left and right plates 82 and 86. The hydrostatic bearing mechanism 90 will be described below.
[0022]
As shown in FIG. 4, shaft support holes 82a and 86a are formed at the lower ends of the left side plate 82 and the right side plate 86, and a support shaft 91 is supported through the shaft support holes 82a and 86a. As shown in FIG. 1, the support shaft 91 includes a small-diameter shaft portion 91a penetrating the shaft support hole 82a, a large-diameter shaft portion 91b integrally formed at the right end of the small-diameter shaft portion 91a, and the large-diameter shaft. A taper portion 91c formed integrally with the right end portion of the portion 91b. The support shaft 91 is formed integrally with the right end portion of the taper portion 91c, and is attached to the shaft support hole 86a, the left end portion of the small diameter shaft portion 91a, and the right end portion of the attachment shaft portion 91d. Male screw portions 91e and 91f formed integrally with each other. A nut 92 is screwed to the male screw portion 91e, a nut 93 is screwed to the male screw portion 91f, and a lower end portion of the right side plate 86 is sandwiched between the taper portion 91c and the nut 93 to support the shaft. 91 is fixed at a predetermined position.
[0023]
A taper member 94 is interposed on the outer peripheral surface of the small-diameter shaft portion 91 a of the support shaft 91 so as to be positioned between the large-diameter shaft portion 91 b and the left side plate 82. The left end surface of the taper member 94 is joined to the right end surface of the left side plate 82, and the right end surface of the taper member 94 is regulated by the left end surface of the large-diameter shaft portion 91 b through a spacer 89. Then, by rotating the nut 92 in the tightening direction, the taper member 94 and the spacer 89 are sandwiched between the right side surface of the left side plate 82 and the left end surface of the large-diameter shaft portion 91b, and the taper member 94 is predetermined. It is fixed in position.
[0024]
A rotation support cylinder 95 is rotatably supported on the outer peripheral surfaces of the support shaft 91 and the taper member 94. A driven pulley portion 95a is integrally formed on the outer peripheral surface of the rotation support cylinder 95, and a belt 96 is hung between the driving pulley portion 72b of the pulley 72 and the driven pulley portion 95a. A flange portion 95 b is integrally formed on the outer peripheral surface of the rotation support cylinder 95, and the position of one side surface of the tool 23 fitted to the outer periphery of the rotation support cylinder 95 is regulated. A male screw portion 95c is formed on the outer peripheral surface of the rotary support cylinder 95, and the right side surface of the tool 23 is pressed toward the flange portion 95b by a ring-shaped nut 97 screwed into the male screw portion 95c. The tool 23 is clamped at a predetermined position.
[0025]
A tapered hydrostatic bearing surface 95d is also formed on the inner peripheral surface of the rotary support cylinder 95 so as to correspond to the tapered hydrostatic bearing surface 94a formed on the outer peripheral surface of the tapered member 94. ing. A tapered hydrostatic bearing surface 95e is formed on the inner peripheral surface of the rotary support cylinder 95 so as to correspond to the tapered portion 91c. An annular groove 94b is formed on the hydrostatic bearing surface 94a so as to be located on a circumference centered on the axis of the support shaft 91, and static pressure is applied by the annular groove 94b and the hydrostatic bearing surface 95d. An annular first pocket 98 is formed. Similarly, an annular groove 91g is formed in the tapered portion 91c so as to be positioned on a circumference centering on the axis of the support shaft 91, and a circle for applying a static pressure by the annular groove 91g and the hydrostatic bearing surface 95e. An annular second pocket 99 is formed.
[0026]
The tapered hydrostatic bearing surface 91h and the hydrostatic bearing surface 95e formed on the outer periphery of the tapered portion 91c are formed to have a larger diameter as they approach the right side plate 86. The hydrostatic bearing surface 94 a and the hydrostatic bearing surface 95 d formed on the taper member 94 are formed to have a larger diameter as they approach the left side plate 82. The pair of hydrostatic bearing surfaces 94a and 95d and the hydrostatic bearing surfaces 91h and 95e are formed to have larger diameters as they go outward from the axial center of the support shaft 91.
[0027]
A first fluid supply for supplying a fluid such as a coolant or lubricating oil that applies a static pressure to the pockets 98 and 99 is applied to the left and right plates 82 and 86, the support shaft 91, and the taper member 94. A passage 100 and a second fluid supply passage 101 are formed. As shown in FIG. 4, both the fluid supply passages 100 and 101 are formed so as to penetrate the inside of the left side plate 82 and the right side plate 86 and guide a static pressure fluid downward from a fluid supply device (not shown). The two pockets 98 and 99 are supplied.
[0028]
As shown in FIG. 1, between the outer peripheral surface of the large-diameter shaft portion 91 b of the support shaft 91 and the inner peripheral surface of the rotary support cylinder 95, the static pressure action is finished from both the pockets 98 and 99 and leaks out. A fluid recovery passageway 102 for joining the fluids thus formed is formed. A fluid discharge passage 103 is formed in the support shaft 91 so as to communicate with the fluid recovery passage 102, and an inlet thereof opens to the fluid recovery passage 102 (an outer peripheral surface of an intermediate portion of the large-diameter shaft portion 91b). Is opened in the end face of the male screw portion 91f.
[0029]
As shown in FIG. 1, an annular groove 82 b for entering the left end portion of the rotating support cylinder 95 is located on the inner surface of the left side plate 82 on a circumference centering on the axis of the support shaft 91. The first slit 104 is formed between the bottom surface of the annular groove 82 b and the left end surface of the rotary support cylinder 95. Similarly, an annular groove 86b for entering the right end portion of the rotary support cylinder 95 is also formed on the inner surface of the right side plate 86 so as to be positioned on the circumference centering on the axis of the support shaft 91. A second slit 105 is formed between the bottom surface of 86 b and the right end surface of the rotation support cylinder 95. The fluid leaking outward from the pockets 98 and 99 is discharged to the outside through the both slits 104 and 105.
[0030]
Next, the operation of the machine tool configured as described above will be described.
In FIG. 5, in order to machine the workpiece W supported by the workpiece support table 14 of the indexing device 12, the turning drive mechanism 13 is driven to index and rotate the workpiece support table 14 and the workpiece W. Next, the inner peripheral surface of the workpiece W is machined by the tool 23 attached to the tool attachment 22 while numerically controlling the spindle device 21 by an X, Y, Z axis drive mechanism (not shown). Further, the clamp of the clamp mechanism 15 is released, the turning drive mechanism 13 of the indexing device 12 is inverted by 90 degrees, the work W is held between the centering device 25, and the outer surface of the work W is moved by the tool 23. Process.
[0031]
On the other hand, after removing the tool attachment 22 from the spindle device 21, the tool attachment 34 is mounted on the spindle device 21, and the workpiece W supported on the rotary table 33 of the rotary support device 31 is processed by the tool 35.
[0032]
Next, the operation of the tool attachment 22 will be described. When the spindle 52 is rotated in FIG. 2, the pulley 72 is rotated via the drive pulley 53 and the belt 73, and the rotation support cylinder 95 and the belt 96 are rotated. The tool 23 is rotated and the workpiece W is machined by the tool 23.
[0033]
When a fluid is supplied from a fluid supply device (not shown) to the fluid supply passages 100 and 101 provided in the mounting arm 81 shown in FIG. 4, this fluid is supplied to the pockets 98 and 99 shown in FIG. The support cylinder 95 is supported by static pressure, and the rotation support cylinder 95 is smoothly rotated.
[0034]
2 and 3, the attachment position of the tool attachment 22 attached to the spindle device 21 is changed as follows. That is, when the bracket 61 is supported by a crane or the like in FIG. 2 and the bolt 62 is removed from the spindle device 21 and the tool attachment 22 is rotated 90 degrees clockwise around the spindle 52, the mounting arm 81 Is displaced so as to be directed in the horizontal direction as indicated by a two-dot chain line in FIG.
[0035]
According to the tool attachment used for the machine tool of the above embodiment, the following features can be obtained.
(1) In the above embodiment, the tool 23 is attached to the tip of the mounting arm 81 via the hydrostatic bearing mechanism 90, and the hydrostatic bearing surfaces 91h and 94a that are tapered with respect to the support shaft 91 and the taper member 94 are provided. The rotary support cylinder 95 is provided with hydrostatic bearing surfaces 95d and 95e. Since the radial and thrust loads acting on the rotary support cylinder 95 are shared by the hydrostatic bearing surfaces 91h and 94a, the radial and thrust dimensions of the rotary support cylinder 95 can be shortened. The size of the hydrostatic bearing mechanism 90 can be reduced. As a result, the tip portion of the attachment arm 81 of the tool attachment 22 can be reduced in size, and the workability of the workpiece W can be improved.
[0036]
(2) In the above embodiment, the tool attachment 22 is attached to the spindle device 21 so that the attachment posture can be changed, and the case 64 and the attachment arm 81 are attached to the bracket 61 so as to be bent. For this reason, compared to the configuration in which the axis of the mounting arm 81 intersects the axis of the spindle 52, the dimension in which the mounting arm 81 protrudes horizontally from the spindle device 21 when the mounting posture of the tool attachment 22 is changed. Therefore, it is possible to reduce the size of the machine tool.
[0037]
(3) In the above embodiment, the annular grooves 82b and 86b are formed on the inner side surfaces of the left side plate 82 and the right side plate 86, and the slits 104 and 105 are formed between the rotary support cylindrical body 95. The load in the thrust direction of the rotary support cylinder 95 can be shared using the fluid leaked from 99 to the outside.
[0038]
In addition, you may change this embodiment as follows.
As shown in FIG. 7, a horizontal cylindrical hydrostatic bearing member 106 is fitted to the outer peripheral surface of the support shaft 91 by shrink fitting, for example, instead of the tapered member 94. Further, instead of the tapered portion 91c, a horizontal cylindrical hydrostatic bearing portion 91i is integrally formed. Of the outer peripheral surface of the support shaft 91, the outer peripheral surface between the hydrostatic bearing member 106 and the hydrostatic bearing portion 91i is defined as a first hydrostatic bearing surface 91j. In addition, the second hydrostatic bearing surface 106a is crossed with the first hydrostatic bearing surface 91j with respect to the hydrostatic bearing member 106 (or orthogonal in this example), and the third hydrostatic bearing surface is formed on the hydrostatic bearing portion 91i. 91k is formed so as to intersect (or orthogonally intersect in this example) with the first hydrostatic bearing surface 91j. A fourth hydrostatic bearing surface 95f is formed on the inner peripheral surface of the rotary support cylinder 95 corresponding to the first hydrostatic bearing surface 91j, and corresponding to the second and third hydrostatic bearing surfaces 106a and 91k. Fifth and sixth hydrostatic bearing surfaces 95h and 95i are formed on the rotary support cylinder 95. Further, the pockets 95j and 95k are positioned so as to be located on the circumference centering on the axis of the support shaft 91 with respect to the fourth hydrostatic bearing surface 95f, the fifth hydrostatic bearing surface 95h, and the sixth hydrostatic bearing surface 95i. , 95l.
[0039]
Also in this example, the dimensions of the rotary support cylinder 95 in the radial direction and the thrust direction can be shortened as in the above embodiment, and the hydrostatic bearing mechanism 90 can be downsized.
[0040]
The rotation driving mechanism of the tool 23 provided on the case 64 and the mounting arm 81 may be changed to a power transmission mechanism other than the belt transmission mechanism.
○ The tapered hydrostatic bearing surface 91h, the hydrostatic bearing surface 94a, and the hydrostatic bearing surfaces 95d and 95e are tapered in the direction opposite to that of the above-described embodiment, that is, the smaller the distance from the central portion of the support shaft 91. You may make it.
[0041]
The technical ideas that can be grasped from the above embodiment and other examples will be described below.
(1) In a tool attachment comprising a case that is removably attached to a spindle device of a machine tool and an attachment arm provided on the outer periphery of the case, the tool attachment arm is attached to the case from the axis of the spindle device. Tool attachment used for offset machine tools.
[0042]
【The invention's effect】
As described above in detail, the present invention can reduce the size of the tip of the attachment arm of the tool attachment and can improve the workability of the workpiece.
[Brief description of the drawings]
FIG. 1 is an enlarged plan sectional view embodying a hydrostatic bearing structure of a tool attachment for a machine tool according to the present invention.
FIG. 2 is a front view of a tool attachment.
FIG. 3 is a longitudinal sectional view of a tool attachment.
FIG. 4 is a longitudinal sectional view of a main part of a tool attachment.
FIG. 5 is a front view showing the entire machine tool.
FIG. 6 is a plan view showing the entire machine tool.
FIG. 7 is a cross-sectional plan view of a main part showing another example of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 21 ... Main shaft apparatus, 23, 35 ... Tool, 51 ... Housing, 52 ... Spindle, 53 ... Drive pulley, 64 ... Case, 70, 91 ... Support shaft, 72 ... Pulley, 73, 96 ... Belt, 81 ... Mounting arm, 82 ... left side plate, 82b, 86b, 91g, 94b ... annular groove, 86 ... right side plate, 91h, 94a, 95d, 95e ... hydrostatic bearing surface, 91j ... first hydrostatic bearing surface, 95 ... rotating support cylinder, 95f: fourth hydrostatic bearing surface, 95h: fifth hydrostatic bearing surface, 104, 105: slit, 106a: second hydrostatic bearing surface.

Claims (5)

A tool holder that is detachably attached to the spindle device of the machine tool;
A support shaft for a hydrostatic bearing supported at the tip of a tool mounting arm of the tool holder;
A rotatably supported, and can be mounted to the tool rotational support cylinder body by hydrostatic against the outer peripheral surface of the support shaft,
A power transmission mechanism provided on the tool holder and operatively connected to a spindle of the spindle device to rotate the rotation support cylinder;
Fitting the grinding wheel an outer peripheral surface of the rotating support cylinder as said tool, said pair of hydrostatic bearing surface forming a tapered shape diameter changes as it goes in the axial direction with respect to the outer circumferential surface of the support shaft A pair of hydrostatic bearing surfaces, which are provided on both sides of the grindstone and are also tapered on the inner peripheral surface of the rotary support cylinder corresponding to both hydrostatic bearing surfaces, are located on both sides of the grindstone. The tool attachment used for the machine tool characterized by having provided. 2. The pair of inner and outer hydrostatic bearing surfaces according to claim 1, wherein the inner and outer hydrostatic bearing surfaces are formed so as to have a larger diameter from the central portion in the axial direction of the support shaft toward the outer side, and the hydrostatic operation is performed inside the support shaft. A tool attachment used for a machine tool in which a discharge passage for discharging the finished fluid to the outside is formed, and an inlet thereof is opened in an outer peripheral surface of an intermediate portion of a support shaft. 3. The case according to claim 1, wherein the tool holder is detachably attached to a front end portion of a housing that supports a spindle of a spindle device and covers the front end portion of the spindle, and a spindle is attached to an outer peripheral portion of the case. The tool attachment used for the machine tool comprised by the attachment arm with which it was mounted | worn so that it might bend seeing from the axial direction. 4. The support shaft according to claim 1, wherein a support shaft is provided on a left side plate and a right side plate provided at a distal end portion of the mounting arm, and the rotation support cylinder is provided on an inner side surface of the left side plate and the right side plate. A tool attachment used for a machine tool in which an annular groove is formed to form a slit for suppressing discharge of a fluid that has entered a peripheral edge portion of a body and finished a static pressure operation to the outside. 5. The drive pulley according to claim 1, wherein a drive pulley that hangs a belt that is hooked on a pulley that is formed on an outer peripheral surface of the rotary support cylinder is supported inside the tool holder. A driven pulley is provided in the vicinity of the driven pulley. The driven pulley is used for a machine tool that is driven to rotate by a driving pulley mounted on the spindle and a belt that is hung between the driven pulley. Tool attachment.

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