JP5445211B2 - Polishing method - Google Patents

Description

The present invention relates to a polishing method for an inner surface of a cavity of a mold, and more particularly to a polishing method in a case where a cavity has a spiral groove formed on the inner surface of a round hole.

Conventionally, an object with a spiral protrusion formed on the outer periphery of a round shaft (for example, a worm or male screw)
Many of the molds for injection molding have cavities formed by electric discharge machining. The mold in which the cavity is formed by such electric discharge machining has a fine uneven surface on the inner surface of the cavity, and the inner surface of the cavity is not a smooth surface, so the rough inner surface of the cavity is transferred to the injection molded product. In order to improve the quality and durability of injection-molded products, improvements have been demanded.

In order to meet such a demand for improving the mold, it is conceivable to employ a polishing method using a polishing apparatus 100 as shown in FIG.

The polishing apparatus 100 shown in FIG. 24 has an abrasive (non-fluid to magnetic fluid) between the polishing surface 101 and the tip polishing portion (magnetic sphere) 103 of the polishing shaft 102 supported so as to be orthogonal to the polishing surface 101. The one in which magnetic abrasive grains are dispersed) is held by a magnetic field. And this FIG.
The polishing apparatus 100 shown in FIG. 1 has a polishing shaft 102 parallel to the surface 101 to be polished and in two directions perpendicular to each other (
The surface to be polished 101 is polished with high accuracy by three-dimensional microvibration in the direction (Z direction) perpendicular to the surface to be polished 101 (X direction, Y direction) (see Patent Document 1). ).

JP-A-5-162064

However, the polishing method performed by the polishing apparatus 100 shown in FIG. 24 can be applied to the polishing of the surface 101 to be polished exposed to the outside, but an object (for example, a worm having a spiral projection formed on the outer periphery of a round shaft). It is not applicable to polishing a mold cavity for injection molding (or a male screw) (a cavity in which a spiral groove is formed on the inner surface side of a round hole that is not exposed to the outside).

Therefore, the present invention provides a polishing method suitable for polishing a spiral groove formed on the inner peripheral side of a cavity having a round hole shape, among cavities of a mold.

The present invention relates to a method for polishing an inner surface of a cavity of a mold. In this invention,
The cavity has a spiral groove formed on the inner periphery of a round hole. The spiral groove of the polishing tool fits in the spiral groove with a gap. In the gap,
An abrasive having fluidity is filled. The polishing tool is (1) vibrated in a state where a load is applied in a direction in which the protrusion is pressed against the surface to be polished of the spiral groove, and the protrusion is the surface to be polished of the spiral groove. (2) is relatively rotated about the axis of the round hole with respect to the mold so as to be the same lead as the lead of the spiral groove, and By being moved relative to the mold along the direction in which the axis of the round hole extends, (3) the surface to be polished of the spiral groove is polished with the abrasive.

In the polishing method of the present invention, the polishing tool is vibrated two-dimensionally so as to draw an elliptical shape or a perfect circle shape, or is vibrated three-dimensionally so as to draw a Lissajous figure.

The protrusion of the polishing tool according to the polishing method of the present invention may be cut out in a range of at least 180 degrees along the inner peripheral direction of the round hole.

In the polishing method of the present invention, the polishing tool may be formed with an abrasive material storage part for storing the abrasive material. Then, when the abrasive in the gap decreases, the abrasive in the abrasive reservoir may be supplied to the gap.

According to the present invention, the spiral projection of the polishing tool that has been vibrated is moved along the spiral groove of the cavity to fill the gap between the surface to be polished of the cavity groove and the projection of the polishing tool. The polished abrasive is rubbed against the surface to be polished, the surface to be polished of the spiral groove of the cavity is uniformly polished, and the surface to be polished becomes a smooth surface.

It is a figure which shows the relationship between the cavity shape of a metal mold | die, and a polishing tool. It is a figure which shows the manufacturing process of an abrasive tool. It is a front view which shows typically the grinding | polishing apparatus of a metal mold | die. 4A and 4B are diagrams showing a mold fixing part side of the polishing apparatus of FIG. 3, FIG. 4A showing a plan view of the mold fixing part side, and FIG. 4B showing a front view of the mold fixing part side. ing. It is a top view which shows the relationship between a processing head and a support | pillar part. It is the perspective view which looked at the vibration generating part from diagonally downward. It is a figure explaining a vibration locus in case a polishing tool vibrates two-dimensionally. It is a figure explaining the vibration locus in case a polishing tool vibrates three-dimensionally. It is a figure which shows the modification 1 of an abrasive | polishing tool. It is a figure which shows the modification 2 of an abrasive tool. It is a figure which shows the modification 3 of an abrasive tool. It is a figure which shows the modification 4 of an abrasive tool. 13A is a cross-sectional view of the polishing tool cut along the line A1-A1 in FIG. 12B, and FIG. 13B is an enlarged view of a portion indicated by C1 in FIG. FIG. It is a figure which shows the modification 1 of the grinding | polishing apparatus of a metal mold | die, and is a figure corresponding to FIG. It is a figure which shows the manufacturing process which concerns on the manufacture example 1 of an abrasive tool. It is a figure which shows the grinding | polishing tool and metal mold | die used for grinding | polishing experiment. It is a figure which shows the modification 5 of an abrasive tool. FIG. 18A is a diagram showing the relationship between the polishing tool and the die cut along the line A2-A2 in FIG. 17B, and FIG. 18B is A3-A3 in FIG. 17B. It is a related figure of the grinding tool shown by cut along a line, and a metal mold. It is a figure which shows the modification 6 of an abrasive tool. It is a figure which shows the manufacturing process which concerns on the manufacture example 2 of an abrasive tool. It is a flowchart figure explaining a part of manufacturing process which concerns on the manufacture example 2 of an abrasive tool. It is a figure which shows the modification 2 of the grinding | polishing apparatus of a metal mold | die, and is a figure corresponding to FIG. It is a figure which shows the modification 3 of the grinding | polishing apparatus of a metal mold | die, and is a figure corresponding to FIG. It is the perspective view which looked at the conventional grinding | polishing apparatus from diagonally upward.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Mold and polishing tool)
FIG. 1 is a diagram showing the relationship between the shape of the cavity 2 of the mold 1 and the polishing tool 3.

As shown in FIG. 1, a mold 1 has a cavity 2 for injection molding of a worm formed by electric discharge machining. The cavity 2 of the mold 1 forms an external shape of the worm, and a spiral groove 5 is formed on the inner periphery of the round hole 4. The spiral groove 5 is for forming the teeth of the worm, and the cross-sectional shape in FIG. 1 is substantially triangular. The groove side surfaces 5a and 5b that form the groove 5 having a substantially triangular cross section correspond to the tooth surface of the worm, and have a rough surface having a rough surface formed by minute irregularities by electric discharge machining. Therefore, when the worm is injection-molded with the die 1 which has been subjected to the electric discharge machining, the tooth surface of the worm becomes a shape in which the shape of the groove side surfaces 5a and 5b of the cavity 2 is transferred, and the tooth surface of the worm becomes a matte surface It will be rough. Therefore, in the present embodiment, the polishing tool 3 that fits with a slight gap is fitted to the inner surface (groove side surfaces 5a, 5b) of the cavity 2, and the inner surface (groove side surfaces 5a, 5b) of the cavity 2 and the polishing tool 3 Paste-like abrasive 7 in the gap 6
(For example, diamond paste containing diamond abrasive grains having a particle diameter of 1 μm),
The polishing tool 3 is vibrated slightly and is polished by the polishing material 7 so that the groove side surfaces 5a and 5b become smooth surfaces.

(Abrasive tool manufacturing process)
FIG. 2 is a diagram illustrating a manufacturing process of the polishing tool 3. First, the stopper 8 is put on the lower end side of the cavity 2 of the mold 1 (see FIG. 2A). Next, the support shaft 10 is inserted into the cavity 2 of the mold 1 so that the axis 11 of the support shaft 10 of the polishing tool 3 and the axis 12 of the cavity 2 of the mold 1 are aligned (FIG. 2 ( a) and FIG. 2 (b)). The support shaft 10 is a bottomed cylindrical body made of metal (for example, iron) in which a space 13 that can accommodate a cartridge heater (not shown) is formed. Next, a cartridge heater (not shown) is accommodated in the space 13 of the support shaft 10, a liquid resin (for example, epoxy resin) 14 is injected into the cavity 2, and the liquid resin 14 is heated by the cartridge heater, so that the liquid resin 14 fluidity is ensured (see FIG. 2C). Then, after the liquid resin 14 is filled in the cavity 2, the energization to the cartridge heater (not shown) is stopped, the heating of the resin by the cartridge heater is stopped, and the cartridge heater is removed from the space 13 (FIG. 2 (c) )reference). Thereafter, when the resin inside the cavity 2 is cooled, the resin shrinks, and a polishing tool 3 made of a resin material to which the inner surface of the cavity 2 is transferred is formed (see FIG. 2D). At this time, if the inner diameter of the cavity 2 is 5 mm between the inner surface of the cavity 2 and the polishing tool 3, a minute gap 6 of about 50 μm (25 μm in the radial direction) is formed. The spiral projection 15 of the polishing tool 3 is formed in the spiral groove 5 of
Are fitted with a small gap 6. Next, the plug 8 is removed from the cavity 2 of the mold 1,
The polishing tool 3 is extracted from the cavity 2 of the mold 1 (see FIG. 2D).

The polishing tool 3 formed in this manner is attached to the polishing apparatus 16 of the mold 1 shown in FIGS. 3 to 4 and used for polishing the mold 1.

In the above description, the liquid resin is heated by the cartridge heater. However, the present invention is not limited to this, and the mold 1 is heated by an external heat source such as a hot plate and injected into the cavity 2 of the mold 1. The liquid resin may be heated.

(Die polishing equipment)
3 to 4 show the polishing apparatus 16 of the mold 1. Of these, FIG.
It is a front view which shows the whole polishing apparatus 16 of this. 4 is a view showing the mold fixing unit 17 side of the polishing apparatus 16 of FIG. 3, and FIG. 4 (a) is a plan view of the mold fixing unit 17 side, and FIG.
Shows a front view of the mold fixing portion 17 side.

As shown in FIG. 3, the polishing apparatus 16 has a slide table 20 that can move in the left-right direction (± X direction) along the upper surface 18 a of the base 18. Rotary table 21, X-Y direction position fine adjustment table 22 (22A, 22B),
And each table is stacked in the order of the mold holding table 23. Further, the polishing apparatus 16
As will be described in detail later, the processing head 24 to which the polishing tool 3 is attached is connected to the guide rail 2.
5 and 25 can be moved up and down (moved in the ± Z direction).

As shown in FIGS. 3 and 4, the slide table 20 has a quadrangular planar shape, and can be slid in the left-right direction by a first table slide mechanism 26 driven by a first motor M1. The first table slide mechanism 26 is, for example, the first motor M1.
A power train mechanism such as a gear train or a ball screw driven by the motor, and a guide rail that guides the slide table 20 moved by the power train mechanism along the left-right direction of the upper surface 18a of the base 18. ing. The first motor M <b> 1 is a stepping motor that operates based on a control signal from a CPU as the control means 27.

The rotary table 21 is supported on the slide table 20 side so that it can rotate. A rotary support shaft 28 located at the center of rotation is rotated by a second motor M2 via a rotary power transmission mechanism 30 such as a gear train. It is designed to rotate. The second motor M2 is a stepping motor that operates based on a control signal from a CPU as the control means 27. The rotary table 21 is rotationally driven in both forward and reverse directions (± R directions).

The XY direction position fine adjustment table 22 can move the mold holding table 23 in two orthogonal directions (X axis and Y axis) on the plane 21 a on the upper side of the rotary table 21. The axis 12 of the cavity 2 of the mold 1 fixed to the holding table 23 and the axis 28a of the rotary table 21 can be matched. Here, the X-Y direction position fine adjustment table 22 includes an X direction position fine adjustment table 22A stacked on the rotary table 21, and a Y direction position fine adjustment table stacked on the X direction position fine adjustment table 22A. 22B. And these X direction position fine adjustment tables 2
Both the 2A and Y-direction position fine adjustment table 22B have a quadrangular planar shape. Note that the X-direction position fine adjustment table 22A and the Y-direction position fine adjustment table 22B may be stacked in the reverse order on the rotary table 21. Here, since the X-axis and Y-axis of the XY direction position fine adjustment table 22 are for the plane 21 a of the rotary table 21, the rotary table 21.
Is rotated with respect to the X axis and the Y axis on the upper surface 18a of the base 18.

The X-direction position fine adjustment table 22A is slidable along one of two orthogonal axes on the plane 21a of the rotary table 21 by the second table slide mechanism 31 driven by the third motor M3. It has become. Second table slide mechanism 31
Is constituted by a power transmission mechanism (not shown) such as a gear train or a ball screw driven by the third motor M3, and a guide rail (not shown) installed on the flat surface 21a of the rotary table 21. The X-direction position fine adjustment table 22A is moved along The third motor M3 is a stepping motor that operates based on a control signal from a CPU as the control means 27.

Further, the Y-direction position fine adjustment table 22B can be slid along one of the two orthogonal axes on the plane 21a of the rotary table 21 by the third table slide mechanism 32 driven by the fourth motor M4. It is like that. The third table slide mechanism 32 includes, for example, a power transmission mechanism (not shown) such as a gear train or a ball screw driven by the fourth motor M4, and is disposed on the upper surface 22a of the X-direction position fine adjustment table 22A. Y-direction position fine adjustment table 22 along the installed guide rail (not shown)
B is moved (moved in a direction orthogonal to the moving direction of the X-direction position fine adjustment table). The fourth motor M4 is a stepping motor that operates based on a control signal from a CPU as the control means 27.

The mold holding table 23 has a quadrangular shape in the same manner as the XY position fine adjustment table 22 and is formed in the same size as the XY position fine adjustment table 22, and is finely adjusted in the Y direction position. It is fixed on the table 22B. In the center of the mold holding table 23,
A mold housing recess 33 in which the mold 1 is housed with a slight gap is formed. The mold accommodating recess 33 has a rectangular shape similar to the planar shape of the mold 1, and a tool relief hole 34 having a diameter larger than the outer diameter of the polishing tool 3 is formed in the center of the mold accommodating recess 33 and the mold. It is formed so as to communicate with the rear surface side of the holding table 23. The mold 1 is configured such that the two orthogonal side surfaces are pressed against the two orthogonal side surfaces of the mold housing recess 33 and are fastened and fixed to the mold holding table 23 with bolts (not shown). As a result, the mold 1 is fixed in a state of being positioned in the mold accommodating recess 33 of the mold holding table 23. Mold holding table 2
3, the plane shape may be a circular shape instead of the square shape. Moreover, when the planar shape of the mold 1 is circular, the mold accommodating recess 33 may have a circular shape similar to the planar shape of the mold 1.

The processing head 24 is attached to a support column 35 erected on the base 18 so as to be vertically movable (movable in the ± Z direction). The processing head 24 is attached to the column portion 35 via the processing head drive means 36, and is moved up and down by the processing head drive means 36 along the guide rails 25, 25 extending in the vertical direction of the column portion 35. It is supposed to be. Processing head 2
4 includes a fixed plate 38 connected to the processing head driving means 36 and the fixed plate 3.
8 has a vibration generating part 41 suspended by a suspension means 40 and a polishing tool mounting part 42 (for example, a holder equipped with a collet chuck) installed at the lower end side central part of the vibration generating part 41. doing. The support shaft 10 of the polishing tool 3 is detachably fixed to the polishing tool mounting portion 42.

As shown in FIGS. 3 and 5, the suspending means 40 is installed on the fixed plate 38, and is arranged around the shaft center 11 of the polishing tool 3 at three equal intervals (120 ° intervals). Yes.
The suspension means 40 includes a suspension bolt 43 and a compression coil spring 44. Among them, the suspension bolt 43 is formed on the tip side (lower end side) of the shaft 46 such that the shaft 46 extending downward from the head 45 passes through the guide hole 47 of the fixing plate 38 so as to be slidable from above to below. The male screw 46a is the female screw 48 of the support plate 48 of the vibration generating portion 41.
screwed into a. The suspension bolt 43 is biased upward by a compression coil spring 44 disposed in a compressed state between the head 45 having a larger diameter than the shaft 46 and the upper surface of the fixed plate 38 (elasticity). Has been raised.) Here, the vibration generating unit 41
At least one of the upper surface of the support plate 48 and the lower surface of the fixed plate 38 is coated with silicone oil having a vibration damping effect. Therefore, the support plate 48 of the vibration generating unit 41 is pressed against the fixed plate 38 via the silicone oil layer 50 by the spring force of the compression coil spring 44. That is, the support plate 48 and the fixed plate 38 of the vibration generating unit 41 are elastically integrated via the silicone oil layer 50 by the spring force of the compression coil spring 44.

Also, as shown in FIG. 3, a load cell 51 is attached across the support plate 48 and the fixed plate 38 of the vibration generating unit 41 in the vicinity of the suspending means 40. As shown in FIG. 5, the load cell 51 is located adjacent to the radially outward side of the suspending means 40, and is installed at three locations at equal intervals along the circumferential direction, like the suspending means 40. Yes. And
The load cell 51 measures the force acting on the polishing tool 3 via the vibration generating unit 41, and the load variation acting on the vibration generating unit 41 (the load in the plane perpendicular to the support shaft 10 of the polishing tool 3). Fluctuation) is measured. The measurement results of the three load cells 51 are input to the control means 27 in an A / D converted state. The load cell 51 uses, for example, LMA-A manufactured by Kyowa Denki Co., Ltd.

FIG. 6 is a diagram illustrating details of the vibration generating unit 41 that minutely vibrates the polishing tool 3. This FIG.
The vibration generating portion 41 shown in FIG. 1 includes a polishing tool mounting portion 42 that holds the polishing tool 3 and a support plate 48.
Are provided with three piezoelectric actuators 52 and six tension coil springs 53. The piezoelectric actuators 52 are arranged at equal intervals around the support shaft 10 of the polishing tool 3 and obliquely upward so as to expand from the end on the polishing tool mounting portion 42 side toward the end on the support plate 48 side. It is arranged so as to extend toward and form a predetermined angle with respect to the support plate 48. Further, in the vicinity of both sides of each piezoelectric actuator 52, one tension coil spring 53 is disposed along the piezoelectric actuator 52 (two in total). A pair of tension coil springs 53 provided with a piezoelectric actuator 52 in between.
Is stretched over the polishing tool mounting portion 42 and the support plate 48 in a pulled state, and a spring force is always generated so as to compress the piezoelectric actuator 52 along the axial direction. Here, when a voltage is applied, the piezoelectric actuator 52 converts electrical energy into mechanical energy, and expands and contracts. Therefore, each piezoelectric actuator 52 of the vibration generating unit 41 is controlled by the control means 27 to control the amount of expansion / contraction (displacement), and is attached to the tip side that is the free end. The tool attachment portion 42 and the polishing tool 3 can be vibrated two-dimensionally or three-dimensionally. In addition,
As the two-dimensional vibration, for example, as shown in FIGS. 7A and 7B, the vibration locus 54 of the polishing tool 3 becomes an ellipse (elliptical vibration), or as shown in FIG. A vibration in which the vibration locus 54 of the polishing tool 3 becomes a perfect circle (a perfect circular vibration) can be considered. As the three-dimensional vibration, for example,
The planar vibration trajectory 54 has an 8-shape as shown in FIG. 8A, the front-side vibration trajectory 54 has a substantially U-shape as shown in FIG. 8B, and the side-side vibration trajectory. The vibration which draws the Lissajous figure whose 54 is an ellipse shape as shown in FIG.8 (c) can be considered. Further, as the piezoelectric actuator 52, for example, ASB510C801NP0 (total length: about 78.4) manufactured by NEC TOKIN
mm, recommended drive voltage DC 100 V).

The machining head drive means 36 is rotatable about the fifth motor M5, the ball screw shaft 55 that is rotationally driven by the fifth motor M5, and one end side (the upper end side in FIG. 3) of the ball screw shaft 55. And a ball screw shaft support portion 56 that supports the ball screw shaft 55 so as to suspend it. The other end side (the lower end side in FIG. 3) of the ball screw shaft 55 is engaged so as to penetrate the ball screw nut 57 fixed to the fixing plate 38 of the processing head 24 (see FIG. 5). . When the ball screw shaft 55 is rotated by the fifth motor M5, the processing head driving means 36 moves the processing head 24 to the guide rails 25 and 25 according to the rotation direction of the ball screw shaft 55. The processing head 24 can be moved downward (−Z direction) along the guide rails 25, 25. The fifth motor M5 is a stepping motor that operates based on a control signal from a CPU as the control means 27.

In the above description, the first motor M1 to the fifth motor M5 have been described as stepping motors, but the stepping motor may be replaced with an AC servomotor. In the above description, manual fine adjustment screws or the like are used in place of the third motor M3 and the fourth motor M4, and the X direction position fine adjustment table 22A and the Y direction position fine adjustment table 22B are finely adjusted manually. You may do it.

(Polishing process using mold polishing equipment)
The cavity 2 of the mold 1 is polished as follows by using the polishing apparatus 16 of the mold 1 configured as described above.

First, the mold 1 to be polished is fixed in a state of being positioned in the mold receiving recess 33 of the mold holding table 23.

Next, the rotary table 21 is rotated, the deflection of the inner peripheral surface of the cavity 2 of the mold 1 is measured with a dial gauge or the like, and the second motor M2 and the third motor M3 are moved so that the deflection becomes zero. The XY direction position fine adjustment table 22 is moved by operating, and the axis 2 of the rotary table 21 is moved.
8a and the axis 12 of the cavity 2 are aligned.

  Thereafter, a paste-like abrasive 7 is applied to the inside of the cavity 2 of the mold 1.

  Next, the support shaft 10 of the polishing tool 3 is fixed to the polishing tool mounting portion 42 of the processing head 24.

Next, by operating the fifth motor M <b> 5, the processing head 24 is lowered so that the lower end of the polishing tool 3 is close to the upper surface of the mold 1.

Next, the second motor M 2 and the fifth motor M 5 are controlled to rotate by the control means 27, so that the spiral protrusion 15 formed on the outer peripheral side of the polishing tool 3 is formed on the inner surface of the cavity 2. The rotation amount per unit time of the rotary table 21 that is rotated by the second motor M2 is controlled so that it can be moved along the groove 5, and the unit of the machining head 24 that is lowered by the fifth motor M5. The amount of movement per time is controlled. As a result, the polishing tool 3 descends with respect to the mold 1 that rotates together with the rotary table 21 so as to have the same lead as the spiral groove 5 of the cavity 2, and the spiral protrusion 15 is spirally formed in the cavity 2. Groove 5
Move relatively inside. That is, the polishing tool 3 moves relative to the mold 1 so as to descend while rotating. Then, as shown in FIG. 1, the upper surface 3a of the polishing tool 3
Is substantially coincident with the upper surface 1a of the mold 1 or when the upper surface 3a of the polishing tool 3 is lowered to a position protruding slightly from the upper surface 1a of the mold 1, the operation of the second motor M2 and the fifth motor M5 is stopped. The position of the polishing tool 3 is defined as a polishing start position.

Next, by applying a voltage to each piezoelectric actuator 52 by the control means 27 and controlling the deformation amount of each piezoelectric actuator 52, the polishing tool 3 is microvibrated in two dimensions or three dimensions (for example, the polishing tool 3). The gap 6 between the protrusion 15 of the groove and the groove side surfaces 5a and 5b which are the polished surfaces is 2
If it is 5 μm, the amplitude is 20 μm smaller than the dimension of the gap 6 and the frequency is 2
(Vibration of about 00 Hz). Here, in FIGS. 7A and 7B, the polishing tool 3 is elliptically vibrated in the YZ plane of FIG. 3 (the plane including the Z axis and perpendicular to the paper surface in FIG. 3). Shows the case. Moreover, FIG.7 (c) has shown the case where the grinding | polishing tool 3 is made to carry out a perfect circle vibration within the YZ plane of FIG. FIG. 8 shows an example in which the polishing tool 3 is three-dimensionally microvibrated (microvibration so as to draw a Lissajous figure). That is, the polishing tool 3 is
It is vibrated so as to draw a figure 8 shape in the XY plane of FIG. 4 (see FIG. 8A),
It is vibrated so as to draw a substantially U shape in the YZ plane of FIG. 3 (see FIG. 8B),
FIG. 4 shows a mode in which vibration is performed so as to draw an elliptical shape in the XZ plane of FIG. 3. 7 to 8, the protrusion 15 of the polishing tool 3 vibrates so as to be closest to the groove side surfaces 5a and 5b that become the polished surface at the point P, and the groove side surface 5a that is the polished surface. , 5
It vibrates so as to repeat approach and separation to b. As the polishing tool 3 vibrates in this way, the paste-like abrasive 7 filled in the gap 6 between the projection 15 of the polishing tool 3 and the groove side surfaces 5 a and 5 b of the cavity 2 is spiraled by the polishing tool 3. The surface to be polished of the cavity 2 is rubbed along the vibration trajectory 54 of the polishing tool 3 while being pressed by the protrusions 15 in the shape of the groove 2 (the groove side surfaces 5a and 5b of the spiral groove 5). The groove side surfaces 5a and 5b are polished.

Next, the polishing tool 3 moves the slide table 21 to either the + X direction side or the −X direction side so that the polishing resistance (polishing load) acts on either the + X direction side or the −X direction side. Or move to the other side. The movement of the slide table 21 at this time is such that the control means 27 controls the operation of the first motor M1 based on the measurement values of the three load cells 51 so that the polishing resistance acting on the polishing tool 3 is within a predetermined range. Is controlled. Simultaneously with the movement of the slide table 21 to the + X direction side or the −X direction side, the fifth motor M5 is operated, and the polishing tool 3 is relative to the mold 1 in the Z-axis direction. It is also possible to increase the polishing load in the normal direction of the groove side surfaces 5a and 5b at the location where the projection 15 of the polishing tool 3 and the groove side surfaces 5a and 5b are pressed.

Next, the second motor M2 and the fifth motor M5 are rotationally controlled again by the control means 27, so that the lower surface 3b of the polishing tool 3 is substantially the same as the lower surface 1b of the mold 1 (the lower end of the cavity 2) or The polishing tool 3 is moved along the spiral groove 5 of the cavity 2 while slightly vibrating by the piezoelectric actuators 52 until the lower surface 3b of the polishing tool 3 slightly protrudes from the lower surface 1b of the mold 1. At this time, the greatest polishing resistance acts on the polishing tool 3 because of the + X direction side and the −X direction.
The groove side surface 5b is located on either side of the direction side and below the spiral groove 5. In this way, by relatively moving the polishing tool 3 within the cavity 2, the main polishing location (the portion of the protrusion 15 of the polishing tool 3 that is located on either the + X direction side or the −X direction side). Therefore, the groove located below the spiral groove 5 of the cavity 2 can be moved without causing uneven polishing. The side surface 5b can be uniformly polished, and the textured rough surface generated by the electric discharge machining can be made smooth.

The control means 27 sets the plate thickness of the mold 1 (the length along the axis 12 of the cavity 2) to L1,
When the length of the polishing tool 3 in the direction along the axis 11 is L2, and the distance by which the polishing tool 3 is lowered from the polishing start position is L3, L3 = L1-L2 or L3 = L1 + ΔL-L2. Then, the rotation of the second motor M2 and the fifth motor M5 is stopped. The position of the polishing tool 3 at this time is defined as a polishing folding position. Note that the polishing tool 3 is continuously vibrated by the piezoelectric actuators 52 even when reaching the polishing folding position.

Thereafter, the control means 27 reversely rotates the second motor M2 and the fifth motor M5, and causes the polishing tool 3 finely vibrated by each piezoelectric actuator 52 to move from the polishing return position to the polishing start position in the spiral groove of the cavity 2. 5 is moved. Thus, by relatively moving the polishing tool 3 in the cavity 2, the main polishing location can be moved along the spiral groove 5 of the cavity 2.
The groove side surface 5a located on the upper side of the spiral groove 5 can be uniformly polished, and the textured rough surface generated by the electric discharge machining can be made smooth.

When the polishing tool 3 reaches from the polishing return position to the polishing start position, the control means 27 stops the operation of the second motor M2 and the fifth motor M5.

Thus, when the polishing tool 3 reciprocates between the polishing start position and the polishing folding position,
One cycle of the polishing process is completed. The control means 27 reciprocates the polishing tool 3 along the spiral groove 5 of the cavity 2 in accordance with the number of cycles of the polishing process inputted in advance, and both grooves of the spiral groove 5 of the cavity 2. The side surfaces 5 a and 5 b are polished with a paste-like abrasive 7.

(Modification 1 of the polishing tool)
FIG. 9 is a diagram illustrating a first modification of the polishing tool 3.

In the polishing tool 3 shown in FIG. 9, an epoxy resin is coated on the outer peripheral side of the master electrode 60 used when the cavity 2 of the mold 1 is subjected to electric discharge machining, and the outer peripheral side of the master electrode 60 is coated with an epoxy resin film 61. It is intended to cover. The master electrode 3 has a shaft hole 62 penetrating the central portion along the shaft center 10, and the solid support shaft 10 is fitted and fixed to the shaft hole 62. Since the master electrode 60 is used when the cavity 2 of the mold 1 is subjected to electric discharge machining, the spiral protrusion 15 engages with the spiral groove 5 of the cavity 2 with a gap (see FIG. 1). ). Further, the resin coating 61 is formed on the protrusion 15 and the groove side surface 5 of the polishing tool 3.
It is formed to such a thickness that a minute gap 6 is formed between a and 5b.

In the polishing tool 3 according to the first modified example, the epoxy resin coating 61 on the outer peripheral surface repeatedly holds and drops the abrasive grains of the abrasive 7, and the groove side surface 5 a of the spiral groove 5 of the cavity 2, 5b
Can be efficiently polished (see FIG. 1).

In addition, the polishing tool 3 according to the first modification is entirely formed of an epoxy resin because the master electrode 60 is made of metal (for example, copper) and the support shaft 10 is a solid round bar. FIG.
Compared with the polishing tool 3 according to the embodiment, the rigidity can be increased, and efficient and reliable polishing is possible.

In the polishing tool 3 according to the first modification, an epoxy resin coating 61 is formed on the outer peripheral surface of the master electrode 60, but the coating 61 may be omitted. That is, the master electrode 60 may be the polishing tool 3.

(Modification 2 of the polishing tool)
FIG. 10 is a diagram illustrating a second modification of the polishing tool 3. FIG. 10A is a diagram corresponding to FIG. 1, and is a diagram showing the relationship between the shape of the cavity 2 of the mold 1 and the polishing tool 3. FIG. 10B is a view of the polishing tool 3 shown in FIG. 10A as viewed from above, and is a plan view of the polishing tool 3. In addition, the polishing tool 3 according to the second modification example, except for the part described below,
Since the basic configuration is the same as that of the polishing tool 3 shown in FIG. 1, the same reference numerals are given to the components corresponding to those of the polishing tool 3 shown in FIG. 1, and the explanation of the polishing tool 3 shown in FIG. A duplicate description is omitted.

As shown in FIG. 10, the polishing tool 3 according to the second modification has a spiral protrusion 15 of the polishing tool 3 shown in FIG. 1 along the circumferential direction (along the inner periphery of the round hole 4) 180. A substantially fan-shaped notch 63 is formed by notching. The notch 63 of the polishing tool 3 is provided with the polishing tool 3
The upper surface 3a to the lower surface 3b are formed.

According to the polishing tool 3 according to the second modified example, the polishing material 7 fed to the upper surface 3a of the polishing tool 3 is removed via the notch 63 by performing the polishing operation on the cavity 2 of the mold 1. Thus, it can be efficiently returned (dropped) into the cavity 2.

Moreover, according to the polishing tool 3 according to the second modification, the protrusion 15 left without being cut out.
The load for polishing (polishing load) is concentrated on the groove side surface, whereby the groove side surfaces 5a and 5b can be efficiently polished, and the groove side surfaces 5a and 5b can be uniformly polished without causing uneven polishing.

Further, according to the polishing tool 3 according to the second modification, a large amount of the abrasive 7 can be stored between the notch 63 and the inner surface of the cavity 2, and the notch 63 has the protrusion 15 and the groove side surface 5 a. , 5
It also functions as an abrasive reservoir for supplying the abrasive 7 to the gap 6 with b.

As long as the rigidity of the polishing tool 3 can be ensured, the polishing tool 3 may be cut out larger than the cutout portion 63 shown in FIG.

(Modification 3 of the polishing tool)
FIG. 11 is a diagram illustrating a third modification of the polishing tool 3. FIG. 11A is a diagram corresponding to FIG. 1 and shows a relationship between the shape of the cavity 2 of the mold 1 and the polishing tool 3. FIG. 11B is a view of the polishing tool 3 shown in FIG. 11A as viewed from above, and is a plan view of the polishing tool 3. In addition, the polishing tool 3 according to the third modification, except for the part described below,
Since the basic configuration is the same as that of the polishing tool 3 shown in FIG. 1, the same reference numerals are given to the components corresponding to those of the polishing tool 3 shown in FIG. 1, and the explanation of the polishing tool 3 shown in FIG. A duplicate description is omitted.

As shown in FIG. 11, the polishing tool 3 according to Modification 3 is formed with a through hole 64 that penetrates from the upper surface 3a to the lower surface 3b of the polishing tool 3 shown in FIG.

According to the polishing tool 3 according to the third modified example, the polishing material 7 sent to the upper surface 3a of the polishing tool 3 is passed through the through hole 64 by performing the polishing operation on the cavity 2 of the mold 1. It is possible to efficiently return (drop) into the cavity 2.

Further, according to the polishing tool 3 according to the third modification, the abrasive 7 can be stored inside the through hole 64, and when the abrasive 7 inside the cavity 2 is insufficient, the abrasive 7 in the through hole 64 is used. Is returned to the internal space of the cavity 2, and the abrasive 7 can be supplied to the gap 6 between the protrusion 15 and the groove side surfaces 5a, 5b. That is, the through hole 64 of the polishing tool 3 according to the third modification also functions as an abrasive reservoir that supplies the polishing material 7 to the polishing location, like the notch 63 of the polishing tool 3 according to the second modification. To do.

As long as the rigidity of the polishing tool 3 can be ensured, the through hole (round hole) 64 shown in FIG. 11 may be a long hole, or a plurality of through holes 64 may be formed.

(Modification 4 of the polishing tool)
FIG. 12 shows a polishing tool 3 according to the fourth modification. FIG. 12A is a diagram corresponding to FIG. 1, and is a diagram showing a relationship between the shape in the cavity 2 of the mold 1 and the polishing tool 3. FIG. 12B is a view of the polishing tool 3 shown in FIG. 12A as viewed from above, and is a plan view of the polishing tool 3. Further, the polishing tool 3 according to the present modification 4 has the same basic configuration as the polishing tool 3 shown in FIG. 1 except for the parts described below, and therefore corresponds to the polishing tool 3 shown in FIG. Constituent parts are denoted by the same reference numerals, and descriptions overlapping with those of the polishing tool 3 shown in FIG. 1 are omitted.

As shown in FIG. 12B, the polishing tool 3 according to the fourth modification example has a tip point of the spiral projection 15 (a point where the tip 15b and the center line 66 intersect) as a reference point B1 for convenience. The notched portion 65 is formed by notching the spiral protrusion 15 within a range of 180 ° clockwise from the reference point B1. As shown in FIG. 12B, the notch 65 of the polishing tool 3 has a spiral projection 15, 1 at a position B 2 rotated 90 ° clockwise from the reference point B 1.
5 is a groove bottom 15a, and is cut into an arc shape so that the spiral protrusion 15 gradually decreases from the reference point B1 toward the position B2. Further, the notch 65 of the polishing tool 3 is formed as shown in FIG.
), When the position of the tip 15b of the spiral projection 15 at a position rotated 180 ° clockwise from the reference point B1 is B3, the position of the spiral projection 15 from the position B3 toward the position B2 is as follows. The spiral projection 15 is cut off in an arc shape so as to gradually decrease. The notch 65 of the polishing tool 3 is formed along the axial direction of the support shaft 10 from the upper surface 3a to the lower surface 3b of the polishing tool 3 as in the polishing tool 3 shown in FIG. 12 (a)).

Further, as shown in FIG. 12 (b), the polishing tool 3 is rotated 18 clockwise from the reference point B1.
In the range of 0 ° to 270 °, the groove bottom 15a between the spiral protrusions 15 and 15 is cut so that the groove bottom 15a ′ between the spiral protrusions 15 and 15 is deeper than the groove bottom 15a of the other part. Polishing relief recesses 67 are formed in the groove bottom 15a by cutting off (cutting) with a tool (see FIG. 13). That is, in the polishing tool 3, the position B3 of the groove bottom 15a is set so that the depth of the groove bottom 15a between the spiral protrusions 15 and 15 becomes maximum at a position B5 of 225 ° in the clockwise direction from the reference point B1.
The groove depth is gradually increased in a substantially crescent shape from 'and B4' toward the position B5 'of the groove bottom 15a.

12A and 12B exemplify a round bar-shaped solid shaft as the support shaft 10 of the polishing tool 3, the present invention is not limited to this, and a pipe-shaped hollow shaft is used as the support shaft 10 of the polishing tool 3. May be used.

(Modification 1 of the mold polishing apparatus)
FIG. 14 shows a part of the polishing apparatus 16 (on the mold fixing portion 17 side) modified so that the polishing tool 3 as shown in FIG. 12 can be manufactured on the mold holding table 23. 3 shows a first modification of the polishing apparatus 16 for the mold 1 shown in FIGS. 3 to 4. FIG. Note that the polishing apparatus 16 shown in FIG. 14 has a mold holding table 2 fixed on the X-Y direction position fine adjustment table 22.
3 is the same as that of the polishing apparatus 16 shown in FIGS.
The components corresponding to those of the polishing apparatus 16 shown in FIG. 3 are denoted by the same reference numerals, and the description overlapping with the description of the polishing apparatus 16 shown in FIGS.

In the polishing apparatus 16 shown in FIG. 14, the mold holding table 23 is divided into a mold housing block 68 and a mold heating block 70.

As shown in FIG. 14A, the mold housing block 68 has a mold housing recess 33 at the center thereof.
Is formed. The mold accommodating recess 33 has a rectangular shape similar to the planar shape of the mold 1, and the mold 1 is accommodated with a slight gap, and the surface (upper surface) 68 a of the mold accommodating block 68. To the back surface (lower surface) 68b. The mold 1 presses the two orthogonal side surfaces against the two orthogonal side surfaces of the mold accommodating recess 33, and
The back surface (lower surface) 1b is pressed against the front surface (upper surface) 70a of the mold heating block 70 and is fastened and fixed to the mold housing block 68 by a bolt (not shown). As a result, the mold 1 is placed in the XY plane (see FIG. 14A) and the XZ plane (see FIG. 14B) in the mold housing recess 33 of the mold housing block 68. Is held on the mold holding table 23 so that the shift movement does not occur.

As shown in FIG. 14B, the mold heating block 70 is divided into an upper block 71 that contacts the mold receiving block 68 and a lower block 72 that contacts the XY position fine adjustment table 22. The upper block 71 and the lower block 72 are integrated with a sheet-like heat insulating material 73 interposed therebetween.

As shown in FIG. 14B, the upper block 71 has a polishing tool 3 in the center portion on the upper side.
A tool escape hole 34 having a diameter larger than the outer diameter of the bottom and having a bottom is formed, and a heater accommodating recess 74 having a size surrounding the mold accommodating recess 33 is formed in a central portion on the lower side thereof. The tool relief hole 34 is opened on the upper surface (surface opposite to the mold housing block 68) of the upper block 71 so that the tip side of the polishing tool 3 can be accommodated. The heater housing recess 74 is open on the lower surface (surface facing the lower block 72) of the upper block 71,
The tool relief hole 34 is in communication. The heater housing recess 74 houses a panel heater (ceramic heater) 75 having a planar shape larger than the planar shape of the mold 1. The panel heater 75 is connected to the energizing connector 7 attached to the outer surface of the upper block 71.
6 is electrically connected. The panel heater 75 is connected to an external power source 80 via an external power cord 77 and an energization control switch 78 connected to the energization connector 76. A temperature sensor 81 for measuring the temperature of the upper block 71 is detachably attached to the upper block 71. Then, the detection result (temperature data of the upper block 71) by the temperature sensor 81 is input to the control means 27. The control means 27 controls the energization control switch 78 based on the data from the temperature sensor 81 (detection result of the temperature sensor 81) by a full-wave phase control method using a triac, and the panel heater 7
5 is controlled to maintain the temperature of the upper block 71 at a predetermined temperature. The panel heater 75 does not protrude outwardly from the heater accommodating recess 74 (downward from the lower surface of the upper block 71).

As shown in FIG. 14 (b), the lower block 72 has a spring accommodating recess 82 formed on the upper side (the surface facing the upper block 71), and a compression coil spring 83 is provided in the spring accommodating recess 82. Contained. The compression coil spring 83 housed in the spring housing recess 82 of the lower block 72 constantly biases the panel heater 75 upward and presses the panel heater 75 against the upper block 71.

When the polishing apparatus 16 having such a structure is used for manufacturing the polishing tool 3, the temperature sensor 81 is attached to the upper block 71 and the energization connector 76 of the upper block 71 is provided.
On the other hand, when the external power cord 77 is connected to the mold 1, the temperature sensor 81 is removed from the upper block 71 and the external power cord 77 is removed from the energizing connector 76 of the upper block 71 when used for polishing the mold 1. It has become.

In this polishing apparatus 16, the upper block 71 forms a groove or a slit so as to surround the heater housing recess 74, and a panel heater 75 housed in the heater housing recess 74.
If it is difficult to transfer the heat to the outside of the region surrounded by the grooves or slits, the mold 1 can be heated more efficiently by the panel heater 75.

(Production Example 1 of a polishing tool using a polishing apparatus)
Hereinafter, the usage example of the polishing apparatus 16 shown in FIG. 14 and the manufacturing example 1 of the polishing tool 3 will be described with reference to FIG.

First, as shown in FIG. 15 (a), a stopper 8 is plugged on the lower end side of the cavity 2 of the mold 1, and the mold 1 with the stopper 8 is accommodated in the mold accommodating recess 33 of the mold accommodating block 68. To fix with a bolt (not shown) (see FIG. 14B). After that, the temperature sensor 81 is attached to the upper block 71 of the mold heating block 70, the external power cord 77 is connected to the energization connector 76, the energization control switch 78 is turned on, and the panel power heater 75 is switched from the external power source 80. Energized,
The upper block 71 and the mold 1 are heated by the panel heater 75 (see FIG. 14B). The heat of the upper block 71 heated by the panel heater 75 is blocked by the heat insulating material 73 from being transferred to the lower block 72.
It becomes possible to utilize efficiently for heating. Here, a heat insulating sheet (not shown) is disposed at the bottom of the spring accommodating recess 82 of the lower block 72, and the heat of the panel heater 75 is applied to the compression coil spring 8.
The heat transfer to the lower block 72 via 3 may be blocked by a heat insulating sheet.

Next, as shown in FIG. 15 (b), after fixing one end side of the support shaft 10 to the polishing tool mounting portion 42 of the polishing apparatus 16, the processing head 24 is lowered (see FIG. 3) to polish. The other end side of the support shaft 10 fixed to the tool mounting portion 42 is inserted into the cavity 2 of the mold 1. The support shaft 10 has the other end (tip) 10 a abutting against the plug 8 or the other end 10 a is the plug 8.
Is inserted into the cavity 2 of the mold 1 until it is located with a slight gap. Further, the XY direction position fine adjustment table 22 is finely adjusted so that the axis 11 of the support shaft 10 is positioned at the center of the cavity 2, and the center of the axis 11 of the support shaft 10 and the center of the cavity 2 are aligned. Is done.

Next, when the temperature of the upper block 71 reaches a predetermined temperature, liquid resin (for example, epoxy resin) 14 is injected into the cavity 2 as shown in FIG. At this time, the liquid resin 14 injected into the cavity 2 of the mold 1 does not impair the fluidity because the entire mold 1 is heated by the panel heater 75 (see 14 (b)). After that, after the cavity 2 of the mold 1 is filled with the liquid resin 14, energization is performed until the liquid resin 14 is solidified (for example, at 100 ° C. for about 2 hours in the case of an epoxy resin). It is turned off and the power supply to the panel heater 75 is cut off (see 14 (b)).

Next, when the temperature of the upper block 71 and the mold 1 is sufficiently lowered, the resin in the cavity 2 is solidified around the support shaft 10 and contracts as shown in FIG. The polishing tool 3 made of a resin material to which is transferred is formed so as to be integrated with the support shaft 10.

Next, the temperature sensor 81 is removed from the upper block 71, and the external power cord 77 is removed from the energizing connector 76 (see FIG. 14B). Thereafter, the rotary table 21 is rotated, the processing head 24 is raised (see FIGS. 3 and 14), and the polishing tool 3 is taken out from the cavity 2 of the mold 1 (see FIG. 15 (e)). . Thereafter, the stopper 8 is taken out from the mold 1 (see FIG. 15E).

Next, a tool post (not shown) is attached to the surface 68a of the mold housing block 68, a cutting tool (cutting tool) 84 is fixed to the tool post, the rotary table 23, the X-Y direction position fine adjustment table 22, and the processing tool. By controlling the operation of the head 24, the polishing tool 3 fixed to the polishing tool mounting portion 42 of the machining head 24 is cut with a cutting tool 84, and a polishing relief recess 67 is formed in the groove bottom 15 a of the polishing tool 3. (See FIGS. 3 and 12 to 14). Here, the cut-out portion 65 of the polishing tool 3 is cut by the operator's manual work using a blade such as a knife without using the polishing device 16 (the protrusion 15 is cut off). The cutting of the notch 65 can be automated using a tool fixed to a tool post (not shown) attached to the surface 68a of the mold housing block 68. As a result, the polishing tool 3 shown in FIG.
Is completed. The protrusion 15 of the polishing tool 3 has a shape in which the shape (spiral groove 5) in the cavity 2 for forming the worm is transferred. When the pressure angle of the worm teeth is 20 °, the protrusion 15 is spiral. The angle of inclination of the groove side surfaces 15c and 15d is about 20 ° (the tip angle of the protrusion 15 is about 40 °).
)become. When this case is described as an example, the polishing escape recess 67 of the polishing tool 3 is
Since it is necessary to minimize the interference between the groove side surfaces 15c and 15d and the cutting tool 84 and to secure the strength of the cutting edge of the cutting tool 84, cutting is performed with the cutting tool 84 having a cutting edge angle of 30 ° (FIG. 13).
(See (b)).

As described above, since the polishing tool 3 can be manufactured using the polishing apparatus 16 (without being removed from the polishing apparatus 16), the polishing tool 3 is polished as compared with the case where the polishing tool 3 is manufactured in a state of being removed from the polishing apparatus 16. The polishing accuracy is improved to the extent that no mounting error occurs when the tool 3 is mounted to the polishing device 16.

Further, as described above, according to the manufacturing example 1 of the polishing tool 3, the entire mold 1 can be heated to a constant temperature by the panel heater 75, and the liquid injected into the cavity 2 of the mold 1. Since the fluidity of the entire resin 14 can be secured, the shape in the cavity 2 is transferred with high accuracy, and the high-precision polishing tool 3 is formed.

Therefore, if the polishing tool 3 according to the modification 4 is formed according to the manufacturing example 1 of the above-described polishing tool 3, the spiral groove 5 of the cavity 2 of the mold 1 is highly accurate by the polishing tool 3 according to the modification 4. It becomes possible to polish.

(Polishing method using polishing tool according to modification 4)
As shown in FIG. 12B, the polishing tool 3 according to the modification 4 has a groove bottom polishing position at a position rotated 30 ° clockwise from the position B3 (210 ° clockwise from the reference point B1). B6
The groove bottom polishing position B6 is pressed against the mold 1 with a desired polishing force to polish the groove bottom 5c of the spiral groove 5 in the cavity 2 of the mold 1 (see FIG. 12A). . The groove bottom polishing position B6 of the polishing tool 3 corresponds to a portion where the polishing escape recess 67 is formed. Therefore, when the polishing tool 3 polishes the mold 1 at the groove bottom polishing position B 6, the inner peripheral end 5 d of the spiral groove 5 in the cavity 2 becomes the groove bottom 15 a of the polishing escape recess 63 of the polishing tool 3. It is possible to reliably polish the groove bottom 5c of the spiral groove 5 in the cavity 2 of the mold 1 with the tip 15b of the spiral projection 15 of the polishing tool 3 and the abrasive 7 without interfering with '. become(
(Refer FIG. 12 (a), (b)).

Further, as shown in FIG. 12B, the polishing tool 3 according to the modified example 4 uses a position rotated 30 ° counterclockwise from the reference point B1 as the groove side surface and the groove inner peripheral edge polishing position B7. Then, the groove side surface and groove inner peripheral edge polishing position B7 is pressed against the mold 1 with a desired polishing force, and the groove side surfaces 5a and 5b of the spiral groove 5 and the inner periphery of the groove 5 in the cavity 2 of the mold 1 are pressed. The end (inner peripheral end of the cavity 2) 5d is polished. Here, the groove 5 having a substantially triangular cross section is polished in two steps: a step of polishing the upper groove side surface 5a and the inner peripheral end 5d and a step of polishing the lower groove side surface 5b and the inner peripheral end 5d. . For example, when the polishing tool 3 relatively moves downward in the cavity 2, the polishing tool 3 is pressed against the lower groove side surface 5b with a desired polishing force, and the lower groove side surface 5b and the inner peripheral end 5d. Is polished with the polishing tool 3 and the abrasive 7. On the contrary, when the polishing tool 3 relatively moves upward in the cavity 2, the polishing tool 3 is pressed against the upper groove side surface 5a with a desired polishing force, and the upper groove side surface 5a and The inner peripheral end 5d is polished by the polishing tool 3 and the polishing material 7 (see FIG. 12A).

According to the polishing method using the polishing tool 3 according to the modified example 4 described above, different portions (the groove side surfaces 5a and 5b, the groove bottom 5c, and the inner peripheral end 5d) of the spiral groove 5 in the cavity 2 are formed. It becomes possible to polish reliably so that it may become the same surface property.

Further, according to the polishing method using the polishing tool 3 according to the modification 4, two types of polishing tools for polishing the groove side surfaces 5a and 5b and the inner peripheral end 5d and the polishing tool for polishing the groove bottom 5c are prepared. There is no need.

Note that the polishing tool 3 has a two-dimensional vibration (elliptical vibration,
The inside of the cavity 2 of the mold 1 is polished in a state in which three-dimensional vibration as shown in FIG.

In the polishing tool 3 shown in FIG. 12B, the groove bottom polishing position is not limited to the position B6. For example, the position B5 may be the groove bottom polishing position. Moreover, in the polishing tool 3 shown in FIG. 12B, the groove side surface and the groove inner peripheral edge polishing position are not limited to the position B7,
For example, a position rotated 45 ° counterclockwise from the reference point B1 may be used as the groove side surface and groove inner peripheral end polishing position.

(Example of polishing experiment using polishing tool according to modification 4)
The experimental contents of polishing the spiral groove 5 in the cavity 2 of the mold 1 with the polishing tool 3 according to the modification 4 are as follows.

The mold 1 used in this polishing experiment is a plate-like body made of chrome alloy stainless steel, having a rectangular planar shape and a plate thickness L1 of 8 mm (see FIG. 14). A cavity 2 is formed at the center of the mold 1, and a spiral groove 5 is formed in the cavity 2 by electric discharge machining.
(See FIGS. 14 and 16). The cavity 2 of this mold 1 is for forming a worm having a module of 0.45, a pressure angle of 20 °, a lead angle of 6 ° and a number of strips of 1 and an inner diameter D1 of 3.2 mm. The valley diameter D is 5.2 mm, the pitch between the grooves 5 and 5 is 1.4 mm, and the opening angle θ of the grooves 5 is about 40 ° (the inclination angle of the groove side surfaces 5a and 5b is about 20 °).
(See FIG. 16). Table 1 summarizes the details of the shape of the polished surface of the mold 1.

The polishing tool 3 according to the modified example 4 is formed of an epoxy resin, and FIG.
It is formed through the manufacturing process (e) (see FIGS. 12 and 16). That is, the polishing tool 3 has a shape in which the shape in the cavity 2 of the mold 1 has been transferred, and the spiral protrusion 15 has been transferred to the spiral groove 5 in the cavity 2. The polishing tool 3 is solidified and contracted in the cavity 2 of the mold 1 and has an outer dimension D0 smaller than the valley diameter D of the cavity 2 by 50 μm (25 μm in the radial direction). Thus, it engages with the inner surface of the cavity 2 with a slight gap (see FIGS. 12 and 16).
The polishing tool 3 has an axial length L2 of 3 mm.

The gap between the polishing tool 3 and the cavity 2 is filled with an oil-based diamond paste containing diamond abrasive grains having a particle size of 1 μm (see FIG. 12A).

In this experiment, after the polishing tool 3 is engaged in the cavity 2 of the mold 1, the vibration generating unit 41 of the polishing apparatus 16 generates an eight-shaped three-dimensional vibration having an intersecting angle of 90 °. The polishing tool 3 and the mold 1 were moved relative to each other (see FIG. 8). In this experiment, the stroke of the polishing tool 3 is such that the upper surface 3 a of the polishing tool 3 is changed from the upper surface 1 a of the mold 1 to 1.
. A position protruding upward by 5 mm is defined as a polishing start position, and a position where the lower surface 3b of the polishing tool 3 protrudes downward by 1.5 mm from the lower surface 1b of the mold 1 is defined as a polishing folding position. Set to 8 mm to position. When the polishing tool 3 reciprocates between the polishing start position and the polishing turn-back position, the groove side surface 5a of the spiral groove 5 of the mold 1 is obtained.
A polishing force of 2N is applied along the normal line direction or the normal line direction of the groove side surface 5b. In addition, when the movement direction of the polishing tool 3 is reversed, the action direction of the polishing force is reversed in conjunction with a change in the movement direction of the polishing tool 3. Accordingly, as shown in FIG. 12B, the polishing tool 3 has a relative movement direction in the cavity 2 when polishing the groove side surfaces 5a, 5b and the inner peripheral end 5d at the groove side surface and groove inner peripheral end polishing position B7. Accordingly, the groove side surface 5a and the groove side surface 5b are polished alternately. Further, the polishing tool 3 has a groove bottom polishing position B6 as shown in FIG.
Thus, the groove bottom 5c is polished. The polishing time of the mold 1 by the polishing tool 3 was 90 minutes, and the polishing tool 3 was moved at a speed of 2.8 mm / min with respect to the Z-axis direction of the mold 1 (FIG. 12A). FIG. 16). Table 2 summarizes the polishing experimental conditions of the mold 1 using the polishing tool 3 according to Modification 4.

As a result of the polishing experiment of the mold 1 using the polishing tool 3 according to the modified example 4 as described above, the mold 1
The surface roughness of the groove side surfaces 5a and 5b near the upper surface 1a of the surface is 0.236 μm Ra before the experiment (before polishing), whereas the arithmetic average roughness after the experiment (after polishing) is 0. .064
Improved to μm. The surface roughness of the groove side surfaces 5a and 5b from the lower surface 1b of the mold 1 is 0.223 μm before the experiment (before polishing), whereas after the experiment (after polishing).
The arithmetic average roughness of was improved to 0.072 μm. Table 3 summarizes the experimental results.

(Variation 5 of the polishing tool)
FIG. 17 shows a polishing tool 3 according to the fifth modification. The polishing tool 3 shown in FIG. 17 is different from the polishing tool 3 according to the modified example 4 except that the formation position of the polishing escape recess 67 is different from that of the polishing tool 3 according to the modification 4.
Other configurations are the same as those of the polishing tool 3 according to the modified example 4 (see FIG. 12). Therefore, in the description of the polishing tool 3 according to the modification 5, the same components as those of the polishing tool 3 according to the modification 4 are denoted by the same reference numerals, and the description overlapping with the modification 4 is omitted. Note that FIG. 17A is the same as FIG.
It is a figure corresponding to a) and is a figure which shows the relationship between the shape in the cavity 2 of the metal mold | die 1 and the polishing tool 3. FIG. FIG. 17B is a view of the polishing tool 3 shown in FIG. 17A as viewed from above, and is a plan view of the polishing tool 3.

As shown in FIG. 17B, in the polishing tool 3 according to the fifth modification, the polishing escape recess 67 of the polishing tool 3 according to the fourth modification is rotated by 15 ° counterclockwise about the axis 11. In the range of 165 ° to 255 ° clockwise from the reference point B1,
The groove bottom 15a between the spiral protrusions 15 and 15 is scraped off (cut) with a cutting tool so that the groove bottom 15a 'between the spiral protrusions 15 and 15 is deeper than the groove bottom 15a of the other part. , Groove bottom 1
A polishing escape recess 67 is formed in 5a. That is, the polishing tool 3 has a spiral projection 1
The position of the groove bottom 15a between positions B3 ′ and B4 ′ of the groove bottom 15a and the position B5 ′ of the groove bottom 15a is such that the depth of the groove bottom 15a between 5 and 15 is maximum at a position B6 of 210 ° clockwise from the reference point B1. The groove depth is gradually increased in a crescent shape.

(Polishing method 1 using an abrasive tool according to modification 5)
First, as a first polishing step, as shown in FIG. 17B, the polishing tool 3 according to the modified example 5 is 30 ° clockwise from the position B3 (210 ° clockwise from the reference point B1). The rotated position is used as the groove bottom polishing position B6. The groove bottom polishing position B6 is pressed against the mold 1 with a desired polishing force (F1), and the spiral groove 5 in the cavity 2 of the mold 1 is grooved. The bottom 5c is polished (see FIGS. 17A and 18A). The groove bottom polishing position B6 of the polishing tool 3 corresponds to the deepest portion of the polishing escape recess 67. Therefore, when the polishing tool 3 performs the polishing operation of the mold 1 at the groove bottom polishing position B6, the spiral groove 5 in the cavity 2 is obtained.
The inner peripheral end 5d of the polishing tool 3 does not interfere with the groove bottom 15a ′ of the polishing escape recess 67 of the polishing tool 3,
The spiral protrusion 1 of the polishing tool 3 is formed on the groove bottom 5c of the spiral groove 5 in the cavity 2 of the mold 1.
5 can be reliably polished by the tip 15b of 5 and the abrasive 7. Here, polishing power (F1
) Is a force acting in a virtual plane orthogonal to the axis 11 in FIG. 17A (the XY plane in FIG. 17B).

Next, as a second polishing step, the polishing tool 3 according to the modified example 5 has a groove side surface and a groove at positions rotated by 30 ° counterclockwise from the reference point B1, as shown in FIG. The groove side surface 5a of the spiral groove 5 in the cavity 2 of the mold 1 is used by pressing the groove side surface and the groove inner peripheral end polishing position B7 against the mold 1 with a desired polishing force. 5b and the inner peripheral end 5d of the groove 5 (the inner peripheral end of the cavity 2) are polished (see FIGS. 17A and 18B). Here, the groove 5 having a substantially triangular cross section is polished in two steps: a step of polishing the upper groove side surface 5a and the inner peripheral end 5d and a step of polishing the lower groove side surface 5b and the inner peripheral end 5d. . For example, when the polishing tool 3 relatively moves downward in the cavity 2, the polishing tool 3 moves to the lower groove side surface 5.
b is pressed with a desired polishing force (force F2 perpendicular to the groove side surface 5b), and the lower groove side surface 5b and the inner peripheral edge 5d are the polishing tool 3 (the groove side surface 15c of the protrusion 15 and the groove bottom 15a) and the polishing material. 7 is polished. On the contrary, when the polishing tool 3 relatively moves upward in the cavity 2, the polishing tool 3 applies a desired polishing force to the upper groove side surface 5a (force F2 perpendicular to the groove side surface 5a). The upper groove side surface 5a and the inner peripheral edge 5d are pressed by the polishing tool 3 (the groove side surface 15d of the protrusion 15).
, Groove bottom 15a) and polishing material 7 (see FIGS. 17A and 18B).

According to such a polishing method using the polishing tool 3 according to the modified example 5, different portions (the groove side surfaces 5a, 5b, the groove bottom 5c, and the inner peripheral end 5d) of the spiral groove 5 in the cavity 2 are formed. It becomes possible to polish reliably so that it may become the same surface property.

Further, according to the polishing method using the polishing tool 3 according to the modified example 5, two types of polishing tools for polishing the groove side surfaces 5a and 5b and the inner peripheral end 5d and the polishing tool for polishing the groove bottom 5c are prepared. There is no need.

Note that the polishing tool 3 has a two-dimensional vibration (elliptical vibration,
The inside of the cavity 2 of the mold 1 is polished in a state in which three-dimensional vibration as shown in FIG.

Moreover, after finishing the above-mentioned 1st thru | or 2nd grinding | polishing process (coarse grinding | polishing process) using the diamond paste whose particle size of the abrasive tool 3 made from an epoxy resin and a diamond abrasive grain is 3 micrometers, grinding | polishing made from urethane resin You may make it perform the above-mentioned 1st thru | or 2nd grinding | polishing process (finish grinding | polishing process) repeatedly using the tool 3 and the diamond paste whose particle size of a diamond abrasive grain is 1 micrometer. In addition, the polishing tool 3 made of urethane resin is molded by using a mold after the rough polishing process.

(Polishing method 2 using an abrasive tool according to Modification 5)
In the first polishing step using the polishing tool 3 according to the modified example 5 described above, depending on the polishing conditions (for example, the polishing force F1 is 2N, the polishing tool 3 is vibrated in the XY plane,
When using a diamond paste with a diamond grain size of 3 μm),
All of the groove bottom 5c, the groove side surfaces 5a and 5b, and the inner peripheral end 5d of the spiral groove 5 in the cavity 2 of the mold 1 can be polished simultaneously. In such a case, the second polishing step may be omitted.

The polishing tool 3 may be provided with circular vibration along the spiral groove 5 of the mold 1.

(Modification 6 of the polishing tool)
FIG. 19 is a plan view showing Modification 6 of the polishing tool 3 and corresponding to FIG. The polishing tool 3 shown in FIG. 19 has the same configuration as that of the polishing tool 3 according to the modification 5 except that the formation position of the polishing escape recess 67 is different from that of the polishing tool 3 according to the modification 5. Yes (see FIG. 17B). Therefore, in the description of the polishing tool 3 according to the modification 6, the same components as those of the polishing tool 3 according to the modification 5 are denoted by the same reference numerals, and the description overlapping with the modification 5 is omitted.

In the polishing tool 3 shown in FIG. 19, the polishing escape recess 67 of the polishing tool 3 according to the modified example 5 is rotated 60 ° clockwise about the axis 11, and the reference point B1
Between the spiral protrusions 15 and 15 so that the groove bottom 15a ′ between the spiral protrusions 15 and 15 is deeper than the groove bottom 15a of the other part in the range of 45 ° to 135 ° in the counterclockwise direction. The groove bottom 15a is scraped off (cut) with a cutting tool, and a polishing relief recess 67 is formed in the groove bottom 15a.

The polishing tool 3 according to Modification 6 can be used in place of the polishing tool 3 according to Modification 5 in “Polishing method 2 using the polishing tool according to Modification 5”.

And as shown in FIG. 19, the planar shape of the polishing tool 3 according to Modification 6 is centerline 85.
Therefore, if the intersection B6 ′ between the center line 85, the tip 15b of the protrusion 15 and the center line 85 is set as the polishing position, the polishing resistance acts in line symmetry with respect to the center line 85. become.

(Production Example 2 of a polishing tool using a polishing apparatus)
Hereinafter, Production Example 2 of the polishing tool 3 using the polishing apparatus 16 shown in FIG. 14 will be described with reference to FIGS.
A description will be given based on FIG.

First, as shown in FIG. 20 (a), a stopper 8 is plugged on the lower end side of the cavity 2 of the mold 1, and the mold 1 with the stopper 8 is accommodated in the mold accommodating recess 33 of the mold accommodating block 68. Then, the mold 1 is fixed in the mold accommodating recess 33 with a bolt (not shown) (see FIG. 14B).

Next, a liquid resin is injected into the cavity 2 of the mold 1 (Step S1 in FIG. 21, FIG. 20).
(See (a)).

Next, the turntable 21 is rotated to apply centrifugal force to the liquid resin injected into the cavity 2 of the mold 1 (see step S2 in FIG. 21, FIG. 14B). As a result, the liquid resin having a high specific gravity is pressed against the inner surface of the cavity 2 by centrifugal force, and the bubbles having a low specific gravity move to the center (axis 12) side of the cavity 2. As a result, the shape of the inner surface of the cavity 2 is transferred to the polishing tool 3 with high accuracy, the shape accuracy of the polishing tool 3 is improved, and bubbles that adversely affect the shape accuracy and strength of the polishing tool 3 are reduced.

After rotating the rotary table 21 for a predetermined time, the rotation of the rotary table 21 is stopped (see steps S3 to S4 in FIG. 21 and FIG. 14B). Note that the rotation speed and rotation time of the turntable 21 are determined to be optimum values depending on the shape of the cavity 2 and the material of the liquid resin.

Next, as shown in FIG. 20 (b), after fixing one end side of the support shaft 10 to the polishing tool mounting portion 42 of the polishing apparatus 16, the processing head 24 is lowered (see FIG. 3) to polish. The other end side of the support shaft 10 fixed to the tool mounting portion 42 is inserted into the cavity 2 of the mold 1 (FIG. 2).
1 step S5). The support shaft 10 is inserted into the cavity 2 of the mold 1 until the other end (tip) 10 a abuts against the plug 8 or the other end 10 a is located with a slight gap with respect to the plug 8. Further, the XY direction position fine adjustment table 22 is finely adjusted so that the axis 11 of the support shaft 10 is positioned at the center of the cavity 2, and the center of the axis 11 of the support shaft 10 and the center of the cavity 2 are aligned. Is done.

Next, as shown in FIG. 14B, the temperature sensor 81 is attached to the upper block 71 of the mold heating block 70, and the external power cord 77 is connected to the energizing connector 76, and the energization control switch 78 is turned on. Then, the panel heater 75 is energized from the external power source 80, and the upper block 71 and the mold 1 are heated by the panel heater 75 (step S6 in FIG. 21).

Next, energization is performed for a predetermined time (for example, about 2 hours at 100 ° C. for epoxy resin) so that the mold 1 is held at a predetermined temperature until the liquid resin in the cavity 2 of the mold 1 is solidified (
Next, the energization control switch 78 is turned off, the energization to the panel heater 75 is interrupted, and the heating of the mold 1 is stopped (step S9 in FIG. 21).
(Refer FIG.14 (b)).

Next, when the temperature of the upper block 71 and the mold 1 is sufficiently lowered, the resin 14 in the cavity 2 is solidified around the support shaft 10 and contracted as shown in FIG. The polishing tool 3 made of a resin material having the inner surface transferred is formed in a state of being integrated with the support shaft 10.

Next, the temperature sensor 81 is removed from the upper block 71, and the external power cord 77 is removed from the energizing connector 76 (see FIG. 14B). Thereafter, the rotary table 21 is rotated, the processing head 24 is raised (see FIGS. 3 and 14), and the polishing tool 3 is taken out from the cavity 2 of the mold 1 (see FIG. 20 (d)). . Thereafter, the stopper 8 is taken out from the mold 1 (see FIG. 20D).

The polishing tool 3 taken out from the cavity 2 of the mold 1 in this way is the notch 65 and the polishing escape recess 6 in the same manner as in “Production Example 1 of a polishing tool using a polishing apparatus”.
7 is processed.

As described above, since the polishing tool 3 can be manufactured using the polishing apparatus 16 (without being removed from the polishing apparatus 16), the polishing tool 3 is polished as compared with the case where the polishing tool 3 is manufactured in a state of being removed from the polishing apparatus 16. The polishing accuracy is improved to the extent that no mounting error occurs when the tool 3 is mounted to the polishing device 16.

Further, as described above, according to the manufacturing example 2 of the polishing tool 3, since the centrifugal force is applied to the liquid resin injected into the cavity 2 of the mold 1, the shape in the cavity 2 is High-precision polishing tool 3 is formed with high-precision transfer.

Therefore, the polishing tool 3 formed based on the manufacturing example 2 of the polishing tool 3 described above can polish the spiral groove 5 of the cavity 2 of the mold 1 with high accuracy.

(Modification 2 of the mold polishing apparatus)
FIG. 22 shows a second modification of the mold polishing apparatus 16. The mold polishing apparatus 16 shown in FIG. 22 is a modification of the mold polishing apparatus 16 shown in FIG. 14, and its basic configuration is the same as that of the mold polishing apparatus 16 shown in FIG. . Therefore, in the mold polishing apparatus 16 according to the second modification, the same components as those of the mold polishing apparatus 16 shown in FIG. 14 are denoted by the same reference numerals, and the mold polishing apparatus shown in FIG. The description overlapping with the description of 16 is omitted.

The mold polishing apparatus 16 according to the second modification uses diamond liquid, which has better fluidity than diamond paste, as an abrasive, and a substantially cylindrical abrasive holding member 86 on the upper surface of the mold 1. The inside of the abrasive material holding member 86, the gap between the cavity 2 of the mold 1 and the polishing tool 3, and the tool relief hole 34 are filled with diamond liquid to polish the inside of the cavity 2 of the mold 1. An abrasive (diamond liquid) is constantly supplied to the location.

The abrasive holding member 86 is formed so as to have an inner diameter dimension that causes a sufficient gap between the outer surface of the polishing tool 3.

(Modification 3 of the mold polishing apparatus)
FIG. 23 shows a third modification of the mold polishing apparatus 16. The mold polishing apparatus 16 shown in FIG. 23 is a modification of the mold polishing apparatus 16 shown in FIG. 22, and its basic configuration is the same as that of the mold polishing apparatus 16 shown in FIG. . Therefore, in the mold polishing apparatus 16 according to the third modification, the same components as those of the mold polishing apparatus 16 shown in FIG. 22 are denoted by the same reference numerals, and the mold polishing apparatus shown in FIG. The description overlapping with the description of 16 is omitted.

The mold polishing apparatus 16 according to the third modification uses diamond liquid, which is more fluid than diamond paste, as an abrasive, and includes a tool relief hole 34 and a pump 87 installed outside as an abrasive. Connected by a recovery pipe 88, a pump 87 and an abrasive supply nozzle 90
Are connected by an abrasive supply pipe 91. The operation of the pump 87 is controlled by the control means 27.

Here, the abrasive recovery pipe 88 is disposed on the rotation axis of the rotary table 21, and the base 18, the slide table 20, the rotary table 21, and the XY direction position fine adjustment table 22.
, The lower block 72, the compression coil spring 83, the hollow disk-like panel heater 75 ′, and the upper block 71 are connected to the tool escape hole 34.

In such a mold polishing apparatus 16 according to the third modification, the diamond liquid supplied from the abrasive supply nozzle 90 into the abrasive holding member 86 is recovered from the tool escape hole 34, and the diamond liquid is recovered by the pump 87. Circulating and polishing material (
Diamond liquid) is always supplied.

(Other variations)
The polishing apparatus 16 according to the above embodiment is a mode in which the processing head 24 is moved up and down, but is not limited to this. The rotary table 21, the XY direction position fine adjustment table 22, and the mold are not limited thereto. The holding table 23 may be moved up and down integrally, and the processing head 24 may be fixed to the support column 35. The polishing apparatus 16 having such a configuration is provided with the polishing tool 3.
On the other hand, the mold 1 moves up and down while rotating.

In the polishing method according to the above embodiment, the spiral groove 5 has a substantially triangular cross-sectional shape, but is not limited thereto, and the cross-sectional shape is rectangular, trapezoidal, or substantially semicircular. It can also be applied to.

Further, the polishing method according to the above embodiment exemplifies polishing of the mold 1 provided with the cavity 2 for injection molding the worm. However, the polishing method is not limited to this, and a cavity for injection molding of the male screw is provided. The present invention can be widely applied to polishing of a mold having a cavity in which a spiral groove is formed on the inner periphery of a round hole, such as polishing of a provided mold.

In addition, the numerical values and material names exemplified in the above-described embodiments and the like are examples for facilitating understanding of the contents of the invention, and are not limited to this illustration, and optimum numerical values and materials are determined according to polishing conditions. Selected.

Moreover, in the said embodiment, although the grinding | polishing apparatus 16 illustrated the aspect which the slide table 20 slides to a X direction, the slide table 20 may slide to a Y direction.

Moreover, although the polishing tool which concerns on the said embodiment and each modification illustrated the aspect shape | molded using an epoxy resin as a resin material, it is not restricted to this, It seems to shape | mold using other resin materials, such as a urethane resin. It may be.

Moreover, although this invention illustrated diamond paste and diamond liquid as an abrasive | polishing material which has fluidity | liquidity, it is not restricted to this, The abrasive | polishing material in which the abrasive grain harder than the metal mold | die 1 was contained in the fluid is applied. It is also possible.

DESCRIPTION OF SYMBOLS 1 ... Mold, 2 ... Cavity, 3 ... Polishing tool, 4 ... Round hole, 5 ... Groove, 5a, 5b
...... Surface side (inner surface, surface to be polished), 6 ... gap, 7 ... abrasive, 12 ... axial center, 15 ... projection, 63 ... notch (abrasive storage part), 64 ... Through hole (Abrasive storage part)

Claims (6)

In the polishing method of the mold cavity inner surface,
The cavity is one in which a spiral groove is formed on the inner periphery of a round hole,
In the spiral groove, the spiral projection of the polishing tool fits with a gap,
The gap is filled with an abrasive having fluidity,
The polishing tool is (1) vibrated in a state where a load is applied in a direction in which the protrusion is pressed against the surface to be polished of the spiral groove, and the protrusion is against the surface to be polished of the spiral groove. (2) The mold is rotated relative to the mold around the axis of the round hole so that the lead is the same as the lead of the spiral groove. By being moved relative to the mold along the direction in which the axis of the round hole extends, (3) the surface to be polished of the spiral groove is polished with the abrasive.
A polishing method characterized by the above. The polishing method according to claim 1, wherein the polishing tool is vibrated two-dimensionally so as to draw an elliptical figure. The polishing method according to claim 1, wherein the polishing tool is vibrated two-dimensionally so as to draw a perfect circle. The polishing method according to claim 1, wherein the polishing tool is vibrated three-dimensionally so as to draw a Lissajous figure. The polishing method according to claim 1, wherein the protrusion is cut out in a range of at least 180 degrees along an inner circumferential direction of the round hole. An abrasive material storage part for storing the abrasive material is formed in the polishing tool, and when the abrasive material in the gap decreases, the abrasive material in the abrasive material storage part is supplied to the gap. The polishing method according to claim 1.

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