JP2002346924A - Work holder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a work holder capable of measuring the shape of work under machining. SOLUTION: This work holder 31 has a pair of supporting pads 312 supporting a work W with fluid hydrostatic pressure. The work W is supported by both supporting pads 312, driven to rotate by both driving rollers 313, 314, and ground by a straight cup grinding wheel 11 (, 21) at front and back surfaces thereof. At each measuring position near the center of the work W, near an edge side, and between the center and the edge side, a displacement sensor 50 (c, e, m) is provided. The displacement sensors 50 can inprocess measure the thickness at the measuring position during machining of the work W.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a processing apparatus for processing a disk-shaped work such as a silicon wafer or a glass disk, and relates to a work holder for holding the work in a rotated state.

[0002]

2. Description of the Related Art Conventionally, a double-headed grinding machine has been known as a processing apparatus for processing a thin disk-shaped work.
This double-headed grinding machine is provided with a pair of cup-shaped grindstones whose grinding action surfaces face each other coaxially and in parallel, and a spindle mechanism for rotating these grindstones coaxially at high speed. In addition, this double-headed grinding machine is a work holder that holds the work in a rotated state and inserts the work between both whetstones.
Have.

[0003] In this double-headed grinding machine, when the work is inserted between the two grindstones by the work holder, these two grindstones are brought close to each other while being rotated at a high speed, so that the entire surface of both sides of the work is reduced. Grind the area.

[0004] The work must be processed in accordance with predetermined specifications in terms of thickness and shape. For this reason, conventionally, an operator measures the shape of the work after the grinding is completed (in-line measurement) and checks whether the work satisfies the specifications. When the work does not meet the specifications, the operator re-grinds or discards the work and adjusts the setting of the double-headed grinding machine so that the work to be subsequently grounded satisfies the specifications. .

[0005]

However, according to the prior art, the double-headed grinding machine is adjusted on a trial and error basis based on the shape of the workpiece that has been ground.
It was difficult to strictly control the shape of the work. Further, as a result of the grinding, the work that does not satisfy the specifications is re-ground or discarded, so that it takes time to process the work, and it is difficult to improve the yield of the work.

Therefore, it is an object of the present invention to provide a work holder capable of measuring the shape of a work being processed.

[0007]

The work holder according to the present invention employs the following structure to solve the above-mentioned problems.

That is, the work holder comprises a rotation holding portion for rotating a disk-shaped work in a predetermined disk-shaped region, and a space between the front and back surfaces of the work at a predetermined measurement position in the disk-shaped region. And a measuring unit that measures

With this configuration, the interval between the front and back surfaces of the work, that is, the thickness of the work is measured while the rotation holding unit holds the work while rotating it.
Further, even when the workpiece is being processed by the processing device, the measuring section of the work holder can measure the thickness of the workpiece.

If the measuring unit can measure the distance between the front and back surfaces of the workpiece at a plurality of measurement positions at different distances from the center on the front and back surfaces of the disc-shaped region, respectively, The shape of the work is estimated based on the thickness of the work at the measurement position.

The measuring section may include a pair of displacement sensors arranged corresponding to the measuring position.
Further, the displacement sensor may be a contact-type displacement sensor having a contact that comes into contact with the workpiece, or may be a non-contact-type displacement sensor such as a laser focus displacement meter or an eddy current displacement sensor.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

<Overall Configuration> FIG. 1 is a schematic configuration diagram showing a double-headed grinding machine. First, the overall configuration of a double-headed grinding machine will be described with reference to FIG. This double-headed grinding machine is equivalent to a processing device and includes a first spindle device 1, a second spindle device 2, and a work holding device 3 having a work holder 31 according to the present embodiment.

The first spindle device 1 has a cup-shaped grindstone 11 and a spindle 12 for rotating the grindstone 11 at high speed. The tip surface of the cup-shaped grindstone 11 is formed as a ring-shaped flat surface, and the flat surface is an operation surface. In addition, this grindstone 11 corresponds to a working portion. In addition, a part other than the grindstone 11 of the spindle device 1 corresponds to a processing drive unit. The grinding wheel 11 is fixed to the main shaft portion 12 with its central axis directed in the Z direction in FIG. The configuration of the main shaft portion 12 will be described later in detail.

The spindle device 1 is guided by a linear guide 41 provided on the bed 4 so as to be slidable in the rotation axis direction of the main shaft portion 12 (thrust direction: Z direction in FIG. 1). Further, the spindle device 1
The slide mechanism 13 is provided. This slide mechanism 13
Is an actuator that slides the spindle device 1 in the direction of the rotation axis of the main shaft portion 12. As the slide mechanism 13, for example, as shown in FIG.
A hydraulic cylinder mechanism may be utilized.

The slide mechanism 13 shown in FIG.
A cylinder 131, a piston 132 fitted in the cylinder 131, and a piston rod 133 fixed to the piston 132 are provided.

The cylinder 131 is provided in a housing chamber 14 which is formed in the housing of the spindle device 1 in a substantially cylindrical shape. Specifically, one end of the cylinder 131 (the left end in FIG. 1) is
1 is fixed to the wall surface on the left side of FIG.
In addition, a through hole is formed in the side wall. The piston rod 133 is fitted into the through hole, and has one end protruding leftward in FIG. The protruding end of the piston rod 133 is fixed to a fixing portion 42 protruding from the base 4.

Then, when the slide mechanism 13 is driven by hydraulic pressure, the spindle device 1 moves in the Z direction in FIG. Then, the spindle 12 and the grindstone 11 of the spindle device 1 move in the Z direction in FIG. 1 while rotating at a high speed.

The second spindle device 2 has the same configuration as the first spindle device 1. That is, the spindle device 2 includes a grindstone 21, a main shaft 22, and a slide mechanism 23.

The two spindle devices 1 and 2 are arranged on the bed 4 with their grinding wheels 11 and 21 coaxially opposed to each other, and move in the left-right direction in FIG. When these spindle devices 1 and 2 move, respectively, the main spindles 12 and 22 also move. Therefore, in a state where the grindstones 11 and 21 are fixed to the main shaft portions 12 and 22, respectively, the distance between the grindstones 11 and 21 can be freely adjusted.

The work holding device 3 has a work holder 31 for holding the work W in a rotated state, and a holder support mechanism 32 for arranging the work holder 31 between the respective spindle devices 1 and 2. The configuration of the work holding device 3 will be described later in detail.

<Structure of Spindle Apparatus> FIG. 2 is a diagram showing a part related to control of the spindle apparatus 1 in the control system of the double-headed grinding machine. The spindle device 2 is controlled in the same manner as the spindle device 1.

As shown in FIG. 2, the spindle device 1 has a drive supply unit 1 for driving a slide mechanism 13 thereof.
5 and a linear sensor 16. Note that the slide mechanism 13 and the drive supply unit 15 correspond to an advance / retreat drive mechanism. The drive supply unit 15 includes the slide mechanism 13
By supplying the fluid to the cylinder 131, the slide mechanism 13 is operated, and the spindle device 1 is moved to the position shown in FIG.
In the Z direction. The linear sensor 16 is
The position of the spindle device 1 in the left-right direction in FIG. 1 is detected. The linear sensor 16 may be constituted by a linear encoder or a laser interferometer.

The drive supply unit 15 and the linear sensor 1
Numeral 6 is connected to the control unit 5 of the double-sided grinding machine. The control unit 5 recognizes the position of the spindle device 1 by monitoring the output from the linear sensor 16, and controls the drive supply unit 15 to move the spindle device 1 to an arbitrary position in the Z direction in FIG. Can be slid.

Next, the spindle 12 of the spindle device 1
Will be described. The main shaft 12 corresponds to a rotation mechanism. FIG. 3 is a longitudinal sectional view schematically illustrating the configuration of the main shaft portion 12. The main shaft portion 12 includes a fixed shaft 121
And an outer ring 122. The fixed shaft 121 has a cylindrical small-diameter portion and a cylindrical large-diameter portion that is larger and flatter than the small-diameter portion and coaxially and integrally. The fixed shaft 121 is fixed to a housing (not shown) of the spindle device 1.

The outer ring 122 has an outer shape substantially similar to the fixed shaft 121 and larger than the fixed shaft 121. The outer ring 122 has a slightly larger space inside the outer ring 122 than the outer ring 122. And
In the outer ring 122, the fixed shaft 121 is loosely fitted substantially coaxially in the space. The fixed shaft 122 includes a plurality of static pressure pads 123 as described later with reference to FIG.
(A, b) to 127 (a, b) are fixed respectively. The outer ring 122 is connected to these static pressure pads 123
(A, b) to 127 (a, b) The shaft is supported on the fixed shaft 121 via a fluid hydrostatic film formed of fluid ejected from (a, b) so as to be rotatable at high speed.

The cup-shaped grindstone 11 is coaxially fixed to the right end of the outer ring 122 in FIG. In addition, as shown in FIG. 2, the spindle 12 includes a spindle motor 128 connected to the controller 5. The main shaft motor 128 includes an outer ring 122 supported by hydrostatic pressure.
Is rotated at high speed. When the outer ring 122 rotates at a high speed, the grindstone 11 fixed to the outer ring 122 also rotates at a high speed about its central axis. The working surface of the grindstone 11 rotates within a predetermined machining circle. The grinding wheel 11 is selected in advance so that the diameter of the processing circle is equal to or larger than the radius of the workpiece to be ground.
However, in the example shown in the present embodiment, the radius of the processing circle and the radius of the work substantially match.

FIG. 4 is a perspective view showing the vicinity of the fixed shaft 121 of the main shaft portion 12. As shown in FIG. FIG. 5 is an explanatory diagram illustrating control of the main shaft portion 12 in the radial direction, and FIG. 6 is an explanatory diagram illustrating control of the main shaft portion 12 in the thrust direction. Hereinafter, FIG.
The spindle 12 will be further described with reference to FIGS. As shown in FIG. 4, the main shaft portion 12 includes two pairs of radial static pressure pads 123a, 123b;
a, 124b and three pairs of thrust static pressure pads 125
a, 125b; 126a, 126b; 127a, 127
b.

Each of these radial static pressure pads 123a, 123a
23b, 124a, and 124b are respectively arranged at equal intervals on the outer periphery of the small diameter portion of the fixed shaft 121. The radial static pressure pads 123a and 123b are symmetric with respect to the center axis of the fixed shaft 121. Similarly,
Both radial static pressure pads 124a and 124b are fixed shaft 1
21 are symmetrical with respect to the central axis. One pair of the radial static pressure pads 123a and 123b corresponds to a pair of the first radial static pressure pads, and the other radial static pressure pad 1
The pair of 24a and 124b corresponds to a pair of second radial static pressure pads.

Further, each thrust static pressure pad 125a, 1
Reference numerals 26a and 127a are fixed to one surface (the left side in FIGS. 3 and 4) of the large diameter portion of the fixed shaft 121, respectively, and each of the thrust static pressure pads 125b, 126b, 1
27b is fixed to the other surface (the right side in FIGS. 3 and 4) of the large diameter portion of the fixed shaft 121, respectively. In addition, each thrust static pressure pad 125a, 126a, 127
a indicates each of the thrust static pressure pads 125b, 126b, 12
7b are arranged so as to face each other.

Further, as shown in FIG.
Reference numeral 2 includes two radial servo valves 123V, 124V and three thrust servo valves 125V, 126V, 127V connected to the control unit 5, respectively. As shown in FIG. 5, the first radial servo valve 123V has a pair of ports, one of which communicates with the radial static pressure pad 123a, and the other of which communicates with the radial static pressure pad 123b. Let me. The servo valve 123V supplies a fluid such as water to one port at a desired pressure and supplies a fluid such as water to the other port at a desired pressure.

Second radial servo valve 124V
Has a pair of ports, with one port communicating with the radial static pressure pad 124a and the other port communicating with the radial static pressure pad 124b. The servo valve 124V supplies a fluid such as water to one port at a desired pressure, and supplies a fluid such as water to the other port at a desired pressure.

The control unit 5 controls the servo valve 123
By controlling V, each of the static pressure pads 123a, 123a
The pressure of the fluid supplied to 3b is adjusted individually.
Then, the outer ring 122 is displaced in a predetermined first radial direction in a horizontal plane. Similarly, the control unit 5
Controls the pressure of the fluid supplied to each of the static pressure pads 124a and 124b individually by controlling the servo valve 124V. Then, the outer ring 122 is displaced in the first radial direction and in the second radial direction perpendicular to the center axis of the fixed shaft 121, respectively.

That is, while the outer ring 122 is rotated at a high speed by the spindle motor 128, the controller 5 controls each of the servo valves 123V and 124V to control the outer ring 122.
Can be arbitrarily displaced in the radial direction within a range that does not make contact with the fixed shaft 121.

As shown in FIG. 6, the first thrust servo valve 125V has a pair of ports, one of which is in communication with the thrust static pressure pad 125a, and the other of which is connected to the thrust static pressure pad 125a. 125b. And this servo valve 125V is
A fluid such as water is supplied to one of the ports at a desired pressure, and a fluid such as water is supplied to the other port at a desired pressure.

Second servo valve for thrust 126V
Has a pair of ports, with one port communicating with the thrust static pressure pad 126a and the other port communicating with the thrust static pressure pad 126b. The servo valve 126V supplies a fluid such as water to one port at a desired pressure, and supplies a fluid such as water to the other port at a desired pressure.

Third servo valve for thrust 127V
Has a pair of ports, with one port communicating with the thrust static pressure pad 127a and the other port communicating with the thrust static pressure pad 127b. The servo valve 127V supplies a fluid such as water to one port at a desired pressure, and supplies a fluid such as water to the other port at a desired pressure.

The control unit 5 controls the servo valve 125
By controlling V, each of the static pressure pads 125a,
The pressure of the fluid supplied to 5b is adjusted individually.
Similarly, the control unit 5 individually controls the pressure of the fluid supplied to each of the static pressure pads 126a and 126b by controlling the servo valve 126V. Further, the control unit 5 controls the servo valve 127V,
The pressure of the fluid supplied to each of the static pressure pads 127a and 127b is individually adjusted.

When adjusted in this manner, the outer ring 122
It will be displaced in the thrust direction. That is, the control unit 5
Are the servo valves 125V, 126V, 127 with the outer ring 122 rotated at a high speed by the spindle motor 128.
By controlling V, the outer ring 122 can be arbitrarily displaced in the thrust direction within a range that does not make contact with the fixed shaft 121. Further, the control unit 5 controls each servo valve 12
5V, 126V, and 127V are individually controlled to control the outer ring 12
2 is individually displaced at the positions of the two static pressure pads 125a and 125b, at the positions of the two static pressure pads 126a and 126b, and at the position of the two static pressure pads 127a and 127b, thereby changing the attitude of the outer ring 122. be able to.

As described above, the control unit 5 controls each of the servo valves 123V to 127V to thereby control the outer ring 1
Adjust the position and posture of 22. Each of these servo valves 123V to 127V corresponds to a fluid supply mechanism.

FIG. 7 is a view for explaining the principle of a so-called opposed pad hydrostatic bearing. In FIG. 7, the static pressure pads 123a,
A pair 123b and an outer ring 122 as a pressure receiving pair are schematically shown. Note that the actual outer ring 122 rotates outside the fixed shaft 121, but in FIG. 7, for convenience of illustration, the outer ring 122 includes the two static pressure pads 123a,
It is shown in the state interposed between 123b. Further, other static pressure pads 124 (a, b) to 127 (a, b)
Are controlled according to the same principle as the pair of the static pressure pads 123 (a, b).

The servo valve 123V supplies a fluid at a supply pressure Ps to one of its ports. The fluid supplied to one port of the servo valve 123V is:
It is supplied to one of the static pressure pads 123a through a pipe.
Note that the input throttle coefficient to the static pressure pad 123a is kc
And The operation amount when changing the supply pressure Ps is set to ΔPs, and the operation amount when changing the input throttle coefficient kc is set to Δkc. The pressure in the recess of the static pressure pad 123a is Pr, and the clearance reduction coefficient of the static pressure pad 123a is kp.

Similarly, the servo valve 123V supplies the fluid at the supply pressure Ps' to the other port. The fluid supplied to the other port of the servo valve 123V passes through the pipeline to the other static pressure pad 123b.
Supplied to Note that the input throttle coefficient to the static pressure pad 123b is kc '. And this static pressure pad 12
The pressure in the recess 3b is Pr '.

Further, the static pressure pads 123a (, 123
The total area in b) is A, and the static pressure pad 123a
The pressure receiving effective area at (, 123b) is defined as Ap. The time is t, the change in the inflow amount of the fluid at one of the static pressure pads 123a is ΔQi, the change in the outflow amount of the fluid is ΔQo, and the static pressure pad 123a and the outer race 122
Is defined as h, the relationship between the two is expressed by the following equation (1).
It is represented by

A · (dh / dt) = ΔQi−ΔQo (1) where ΔQi and ΔQo are: ΔQi = Δ [kc · (Ps−Pr)] = (Ps0−Pr0) · Δkc + kc0 · (ΔPs− ΔPr) is a ... (2a) ΔQo = Δ ( kp · h 3 · Pr) = 3 · kp · h0 2 · Pr0 · Δh + kp · h0 3 · ΔPr ... (2b).

The change in the inflow amount of the fluid at the other static pressure pad 123b is represented by ΔQi ′, and the change in the outflow amount of the fluid is represented by ΔQo ′.
Assuming that the gap with 2 is h ′, Δh = −Δh ′ (3)

Further, considering the operation of the outer ring 122, the following holds: Ap (ΔPr−ΔPr ′) = M ＝ s ²・ Δh (4) Here, M is the mass of the outer ring 122 as the pressure receiving body, and s is the domain of the image function in the Laplace transform.

[0048] formula (1), (2a) and (2b) than, Gh '(s) · Δh = Gp s' (s) · ΔPs-ΔPr + Gkc '(s) · Δkc ... (5a) Gh' (s) _{· Δh '= Gp s' (} s) · ΔPs'-ΔPr '+ Gkc' (s) · Δkc '... (5b) here, Gh' = (3 · kp · h0 2 · Pr0 + A · s) / (kc + kp + h0 3 _{) Gp s '= kc0 / (} kc0 + kp · h0 3) Gkc' = a (Ps0-Pr0) / (kc0 + kp · h0 3).

[0049] formula (5a) and (5b), is substituted into the formula (3), ΔPr + ΔPr ' = Gp s' (s) · (ΔPs + ΔPs') + Gkc' (s) · (Δkc + Δkc ') ... (6) is can get.

The equation (4) and _{(6), ΔPr = Gp s} '(s) · (ΔPs + ΔPs') / 2 + Gkc '(s) · (Δkc + Δkc') / 2 + M · s · Δh / (2 · Ap ) ... (7) are substituted into the formula (5), Gh (s) · Δh = Gp s (s) · (ΔPs-ΔPs') + Gkc '(s) · (Δkc + Δkc') ... (8) here, ^{gh = M · s 2 + {} 2 · A · Ap / (kc0 + kp · h0 3)} · s + (6 · Ap · kp · h0 2 · Pr0) / (kc0 + kp · h0 3) Gp s = Ap · kc0 / ^{(kc0 + kp · h0 3)} Gkc = Ap · (Ps0-Pr0) is ^{/ (kc0 + kp · h0 3} ).

As described above, in the pair of opposing static pressure pads 123a, 123b, one of the supply pressures Ps,
The gap h can be freely adjusted by changing at least one of the other supply pressure Ps ′, the supply throttle kc, and the supply throttle kc ′. That is, the control unit 5
Controls the servo valve 123V so that the supply pressure Ps,
By changing Ps 'or the supply throttles kc, kc', the outer ring 122 can be freely moved toward or away from one of the static pressure pads 123a.

Further, the control unit 5 controls the servo valve 1
Along with 23V, other servo valves 124V to 127V
To control the position and orientation of the outer ring
It can be adjusted freely within a range in which 22 does not abut on fixed shaft 121. Since the position and orientation of the outer ring 122 are uniquely determined according to the states of the servo valves 123V to 127V, the control unit 5 accurately determines the position and orientation of the outer ring 122 based on open loop control. Can be adjusted.

However, the control unit 5 determines the position and orientation of the outer ring 122 obtained based on the measurement by using the servo valve 123V.
By feeding back to the command for ~ 127V, it is possible to suppress a decrease in rigidity in accordance with the change in the gap h and to speed up the operation for the command.
Note that, instead of the position and posture of the outer ring 122, the recess internal pressure Pr may be measured.

As shown in FIG. 2, the spindle device 12 of this embodiment has an X sensor 123S, a Y sensor 124S, and three Z sensors 125S, 126S, 127S for acquiring the position and orientation of the outer ring 122. Is provided. Each of these sensors 123S to 127S may be composed of, for example, a capacitance type sensor.

The X sensor 123S is connected to each static pressure pad 123
The position of the outer ring 122 in the operation direction (X direction in FIG. 3) by the a and 123b is measured. The Y sensor 124S is
The position of the outer ring 122 in the operation direction (Y direction in FIG. 3) of each of the static pressure pads 124a and 124b is measured. And the control part 5 can acquire the position of the outer ring 122 in the X direction and the Y direction, respectively, based on the output signals from the X sensor 123S and the Y sensor 124S.

The Z sensor 125S is connected to each static pressure pad 125
The position of the outer race 122 in the direction of movement of the outer ring 122 is measured by the a and 125b. The Z sensor 126S is connected to each static pressure pad 12
The position in the direction of movement of the outer ring 122 by 6a and 126b is measured. The Z sensor 127S is connected to each static pressure pad 1
The position of the outer ring 122 in the direction of movement of the outer ring 122 is measured by 27a and 127b. Each of these Z sensors 125S-127
S measures the position of the outer ring 122 in the Z direction in FIG. 3, but the measured value also changes depending on the attitude of the outer ring 122. For this reason, the control unit 5 determines, based on the output signals from these Z sensors 125S to 127S,
The position of the outer ring 122 in the Z direction, and the outer ring 122
Posture can be obtained.

Note that these sensors 123S to 127S
The position and orientation of the outer ring 122 obtained by
The position and orientation are based on 21. Note that the slide mechanism 13 changes only the position of the fixed shaft 121 in the Z direction in FIGS. 1 and 3, but does not change its posture. Therefore, the control unit 5 acquires the position of the fixed shaft 121 based on the output signal from the linear sensor 16, and based on the output signals from the sensors 123S to 127S, determines the position of the outer ring 122 based on the fixed shaft 121 and By obtaining the posture, the position and the posture of the outer ring 122 can be obtained. The control unit 5 can adjust the outer ring 122 to a desired position and posture with high rigidity and high response by performing feedback control using the acquired position and posture of the outer ring 122.

<Structure of Work Holding Apparatus> Next, the structure of the work holding apparatus 3 will be described with reference to FIG. The work holding device 3 includes a work holder 31 that holds the work W, and a holder support mechanism 32 that supports the work holder 31. Note that the holder support mechanism 3
2 moves the work holder 31 in the X direction in FIGS. 1 and 8 by being guided and moved by a guide (not shown).

Hereinafter, the structure of the work holder 31 will be described.
It will be described in detail. The work holder 31 includes a frame 311,
And a pair of support pads 312 (, 312 ′).

The frame 311 is a substantially flat member having a cutout capable of accommodating the work W in a state facing a predetermined area on the outer periphery of the work W. In the frame 311, a portion on the opposite side of the center of the notch protrudes leftward in FIG. 8, and the protruding portion is attached to the holder support mechanism 32. Further, a pair of drive rollers 313 and 314 that are in contact with an edge of the work W in a state where the work W is stored in the notch is attached to the frame 311.

Further, at one end of the frame 311,
The first work support mechanism H1 is attached. First
Has a link member H11, a driven roller H12, and an air cylinder H13. The link member H11 has a substantially triangular plate-like outer shape, and a driven roller H12 is axially supported near one vertex (first vertex). The link member H11 is axially supported by the frame 311 in the vicinity of one vertex (second vertex) of a pair of vertices other than the first vertex. And
The link member H11 can be rotationally displaced within the XY plane in FIG. 8, and the driven roller H12 can be driven to rotate with its rotation axis directed in the Z direction in FIG.

An air cylinder H13 is connected near the vertices (third vertices) other than the first and second vertices of the three vertices of the link member H11.
The air cylinder H13 is connected to the link member H11.
Is rotationally displaced. Due to the rotational displacement of the link member H11, the driven roller H12 is moved to either the holding position where it rotatably abuts the end face of the work W stored in the frame 311 or the open position where it is separated from the work W. Will be taken.

Similarly, the second work supporting mechanism H2 has a link member H21, a driven roller H22, and an air cylinder H23, and is attached to the other end of the frame 311. The driven roller H22 assumes one of a holding position where the driven roller H22 rotatably abuts the end face of the work W stored in the frame 311 and an open position separated from the work W. In addition, these driven rollers H12,
The work W is inserted into and removed from the work holder 31 in a state where H22 is set to the open position. The work W is held in the work holder 31 in a state where the driven rollers H12 and H22 are set at the holding positions, respectively.

In FIG. 8, the end of the work W held by the work holder 31 is located close to the center axis of the grindstone 11. That is, although not shown in FIG. 8, the work W is inserted between the two grindstones 11 and 21. The position of the work holding device 3 in this state is called a grinding position.

On the other hand, the work holding device 3 can be moved from the grinding position to the left in FIG. 8 (the direction opposite to the arrow in the X direction) and stopped at a predetermined retracted position. With the work moving mechanism 3 in the retracted position, the work W held by the work holder 31 has been retracted from both grindstones 11 and 21. In a state where the work holding device 3 is in the retracted position and the air cylinders H13 and H23 have moved the driven rollers H12 and H22 to the open position via the link members H11 and H21, the work W is held in the work holder. 31.

Each of the support pads 312 (, 312 ′) is formed in a substantially flat plate shape, and when the work W is accommodated in the cutout of the frame 311, the work W
Has a shape capable of opposing a substantially semicircular region on the side close to the frame 311 on each of the front and back surfaces of.

Further, each support pad 312 (, 31
2 ′) has three protruding portions formed so as to protrude outward, and each of these protruding portions is attached to the frame 311 respectively. Each support pad 312, 312 ′ has a shape in which the tip is cut out in a gentle arc so as not to interfere with the center portion of the work W stored in the frame 311. In addition, each support pad 312 (, 312 ′) has a plurality of pockets respectively formed on opposing surfaces thereof. Each pocket is a shallow and flat groove, and has an opening (not shown) for ejecting a fluid such as pressurized water.

Then, in a state where the work W is held in the notch of the frame 311, each support pad 312 (,
312 ') face the workpiece W with a slight gap. In this state, fluid is supplied to each pocket through the ejection holes. Then, this fluid is filled in each pocket and flows through the gap between each support pad 312 (, 312 ′) and the work W. That is, the work W is supported by both support pads 312 (, 3
12 '), it is supported by the hydrostatic pressure.

When the work holding device 3 takes the grinding position, the right end in FIG. 8 of the work W held by the work holder 31 is rotatable by the third work support mechanism H3. Supported. The work support mechanism H3 includes a pair of driven rollers H31 and H32, and a support member H33.

The driven rollers H31 and H32 are supported by a support member H33 so that their rotation axes can be driven to rotate in the Z direction in FIG. 8 in parallel with each other.
The support member H33 is fixed to the base 4 via a mounting member (not shown). However, this support member H3
3 may be fixed to either of the spindle devices 1 and 2 instead of being fixed to the base 4.

Further, the work holding device 3 includes a motor (not shown), and rotates both driving rollers 313 and 314 in the same direction via a belt or a gear. Also,
The work holding device 3 includes a rotation detector 315 that measures the rotation speed of the work W. This rotation detector 315
Includes a detection roller and an encoder that rotate in contact with the edge of the workpiece W. And the rotation detector 3
The fifteen rollers are arranged so as to come into contact with the workpiece W at a position close to one drive roller 313.

When the work holding device 3 is located at the grinding position and the driven rollers H12 and H22 are set at the holding positions, the work W is moved between the rollers 313 and 3
Driven by 14 rotates. Each driven roller H
12, H22, H31, and H32 support the work W while being driven and rotated by the work W. In addition, the work W includes both support pads 312 and 312 ′.
It is supported by hydrostatic pressure between them. Accordingly, the work W rotates at a predetermined position between the two grindstones 11 and 21. That is, the work W rotates within a predetermined disc-shaped region. In addition, both support pads 312, 312 ', both drive rollers 313, 314, and each driven roller H12, H2
2, H31 and H32 correspond to the rotation holding unit. Then, the rotation detector 315 detects the rotation speed of the work W by rotating the roller by bringing the roller into contact with the edge of the work W.

Further, the work holder 31 has three pairs of displacement sensors 50e, 50e '; 50m, 50m'; 50c, 50 as a measuring section for measuring the sectional shape of the work W.
c ′. Each of these displacement sensors 50e, 50
e ′; 50 m, 50 m ′; 50 c, 50 c ′ are a pair of sensor mounting members 31 fixed to the frame 311.
6,316 '. These sensor mounting members 316 and 316 'are desirably made of a low thermal expansion material.

FIG. 9 is a sectional view taken along line 9-9 in FIG. The sensor mounting member 316 has a general shape in which a rectangular plate-shaped base portion and a projecting portion extending parallel to the base portion are integrally connected.

As shown in FIG. 8, the sensor mounting member 3
The base portion 16 is fixed near the drive roller 314 in the frame 311. The projecting portion of the sensor attachment member 316 is spaced from the support pad 312 by a predetermined distance from the edge of the workpiece W toward the center.
It is overhanging.

Then, three displacement sensors 50e, 50m and 50c are mounted on the sensor mounting member 316. The displacement sensor 50e is arranged at a position (measurement position) near the edge of the work W. The displacement sensor 50c is
It is arranged at a position (measurement position) near the center of the work W. The displacement sensor 50m includes both of the displacement sensors 50e,
It is arranged at a position (measurement position) between 50c. In addition,
The distance between the displacement sensor 50m and the displacement sensor 50e, and
The distance between the displacement sensor 50m and the displacement sensor 50c is equal to each other. The two displacement sensors 50e and 50c are disposed at positions retreated from the support pad 312. On the other hand, the displacement sensor 50m is arranged in a through hole 312a formed in the support pad 312.

Similarly, the other sensor mounting member 316 '
Is configured in the same manner as the sensor mounting member 316, and is fixed to the frame 311 so that the sensor mounting member 316 is symmetrical with respect to the plane on which the workpiece W rotates. Further, three displacement sensors 50e ', 50m', and 50c 'are provided on the sensor mounting member 316'.
However, each displacement sensor 50 with respect to the plane on which the workpiece W rotates
e, 50m, and 50c, respectively, so as to be symmetrical.

FIG. 10 is a schematic view showing a displacement sensor. FIG. 10 shows that both displacement sensors 50c and 50c '
FIG. 9 is a diagram viewed in the direction of arrow 10 in FIG. As shown in FIG. 10A, the displacement sensor 50c
Has an elongated main body portion 51 and a contact 52 attached to the tip of the main body portion 51.

The longitudinal direction of the main body portion 51 is
, And is fixed to the sensor mounting member 316. The contact 52 has a rotationally symmetric shape with its tip smoothly projecting, and its axis is aligned with the longitudinal direction of the main body 51. The contact 52 is guided by the main body 51 so as to be displaceable only in the axial direction, and is urged by a spring (not shown) in the direction of the tip in the axial direction. Further, the displacement sensor 50c has a bellows 53 for protecting a region near the distal end of the main body portion 51 from the base end side of the contact 52.
Is provided.

The sensor mounting member 316 has a cylinder mechanism L disposed adjacent to the displacement sensor 50c.
1 is fixed. The cylinder mechanism L1 is formed of, for example, an air cylinder and has a rod that can move forward and backward. The cylinder mechanism L1 is fixed to the sensor mounting member 316 so that the rod advances and retreats in a direction parallel to the longitudinal direction of the main body 51 of the displacement sensor 50c. FIG. 10A shows the cylinder mechanism L1.
FIG. 10 shows a state in which the rod is projected.
(B) shows a state in which the cylinder mechanism L1 has the rod immersed therein.

Further, a retraction member L2 is fixed to the tip of the rod of the cylinder mechanism L1. This retraction member has a long prismatic portion, a rectangularly projecting leftward portion in FIG. 10 from the tip of the prismatic portion, and a further projecting leftward portion in FIG. 10 from the projecting portion. The pullback plate L21 is integrally provided.

The pull-back plate L21 has a rectangular plate-like outer shape and has a small hole. The contact 5 of the displacement sensor 50c is inserted into the small hole of the pullback plate L21.
2 are fitted. The small hole of the pull-back plate L21 is formed in a tapered shape extending toward the base end of the contact 52 in the axial direction. The contact 52 fits into the small hole of the pull-back plate L21 and the tip thereof is connected to the pull-back plate L21.
21.

The other displacement sensor 50c 'has the same configuration as the displacement sensor 50c.
0c and symmetrically with respect to a predetermined plane on which the workpiece W rotates,
It is fixed to the sensor mounting member 316 '. Further, a cylinder mechanism L1 and a retraction member L2 are similarly provided corresponding to the displacement sensor 50c '.

As shown in FIG. 10A, the contacts 52 of the displacement sensors 50c and 50c 'project from the pull-back plates L21 and are in contact with the work W. In this state, the two contacts 52, 52 are loosely fitted to the two retraction plates L21, L21, respectively, but are not in contact with the two retraction plates L21, L21.

If the workpiece W is not interposed between the two contacts 52, 52, the two contacts 52 come into contact with each other. Even in this state, both contacts 52, 5
2 do not contact the two return plates L21 and L21, respectively.
In the state shown in FIG. 10A, the two return plates L21 and L21 face each other with a predetermined space therebetween, and do not contact the work W. This FIG.
The state of the two displacement sensors 50c and 50c 'shown in FIG.

Then, when the two cylinder mechanisms L1 and L1 retract their rods, the two return plates L21 and L21
Are separated from each other while abutting against the contacts 52 and 52 and pulling the contacts 52 and 52 back toward the base end thereof. This state is shown in FIG. The two displacement sensors 50c, 50 shown in FIG.
The state of c 'is called a standby state.

The two displacement sensors 50e, 50e 'and the two displacement sensors 50c, 50c' have the same configuration as the two displacement sensors 50c, 50c ', respectively.

FIG. 11 is a diagram showing a portion related to control of the displacement sensor 50 and the cylinder mechanism L1 in the control system of the double-headed grinding machine. As shown in FIG. 11, the control unit 5 of the double-headed grinding machine controls the displacement sensors 50 (50e, 50e).
e '; 50m, 50m'; 50c, 50c '), and the position of each contact 52 can be obtained based on the output signal. Further, the control unit 5 controls each of the cylinder mechanisms L1 so that each of the displacement sensors 50
Can be set to a measurement state or a standby state.

When the work holder 31 does not hold the work W, the control unit 5
By setting 0 to the measurement state, the opposing contacts 52 are brought into contact with each other, and so-called zero point adjustment is performed based on the output signal from the displacement sensor 50 in this state. Specifically, the control unit 5 includes the two displacement sensors 50c,
In a state where the contacts 52c 'are in contact with each other, the output signals from the displacement sensors 50c and 50c' are respectively obtained, and the value of the output signal is recognized as a reference value (point 0).

Thereafter, in a state where the work holder 31 holds the work W, the control unit 5 sets each of the displacement sensors 50 to the measurement state, so that both the displacement sensors 50c,
The contacts 52c ′ are brought into contact with the workpiece W, respectively. Then, the control unit 5 obtains the output signals from both the displacement sensors 50c, 50c 'in this state and compares them with the reference value, so that the two contactors 52, 52 are contacted with each other from the contact position. Can be accurately recognized. Further, the control unit 5 can obtain the distance between the front and back surfaces of the work W (the thickness of the work W) at the positions of the both contacts 52 by adding the displacements of the two contacts 52, 52. it can.

The control unit 5 controls the two displacement sensors 50
c, 50c ′, the thickness near the center of the work W (center thickness Tc) is obtained, and based on the output signals from both displacement sensors 50e, 50e ′, the vicinity of the edge of the work W is obtained. And the thickness (intermediate thickness Tm) at a position intermediate the center and the edge of the workpiece W based on the output signals from the displacement sensors 50m and 50m '. can do.

<Relationship between Work Shape and Posture of Grinding Stone> Based on the center thickness, edge thickness, and intermediate thickness (Tc, Te, Tm) acquired as described above, the control unit 5 executes the process shown in FIG. , The shape of the work W can be estimated as described later. The shape of the work W is determined by the two whetstones 11 and 12.
Of the work W relative to the front and back surfaces.

Hereinafter, the posture of the grindstone 11 and the shape of the work W will be described with reference to FIGS. As shown in FIG. 12, when the rotation axis of the grindstone 11 is parallel to the rotation axis of the work W, the work W is ground into a flat disk shape. That is, assuming a virtual center plane of the work W perpendicular to the rotation axis of the work W, when the inclination angle θ between the virtual center plane and the working surface of the grindstone 11 is θ = 0 °, the work W is flat. Grinded into a disk shape. The inclination angle θ is equal to the angle between the rotation axis of the work W and the rotation axis of the grindstone 11.
The state of the grindstone 11 shown in FIG. 12 corresponds to a reference state. A plane (ZX plane) including the rotation axis of the grindstone 11 and the rotation axis of the workpiece W in the reference state corresponds to the reference plane.

On the other hand, as shown in FIG.
Is equal to θ = θ1, the workpiece W is not ground into a flat disk shape. Note that θ1 is a small angle larger than 0. The shape of the work W is determined by the inclination angle θ and its phase α. 13 to 16,
Each of the inclination angles θ is θ = θ1, but the phases α are different from each other.

The phase α of the inclination angle θ is determined by the angle between the surface swept by the inclination angle θ and the ZX plane. FIG.
As shown in FIG. 3, when the rotation axis of the workpiece W is parallel to the Z direction in FIG. 13, the rotation axis of the grindstone 11 is parallel to the ZX plane, and the left edge of the grindstone 11 in FIG. The phase α of the inclination angle θ when the position is closer to the work W than the other parts is α = 0.

FIG. 14 shows that the phase α is α = 30 °, that is,
The phase α, which is the angle between the sweep plane and the ZX plane, of the inclination angle θ is α = 30 °.

FIG. 15 shows a state in which the phase α is α = 120 °, that is, the phase α which is the angle between the sweep plane and the ZX plane with the inclination angle θ is α = 120 °.

FIG. 16 shows a state in which the phase α is α = 180 °, that is, the phase α which is the angle between the sweep plane and the ZX plane with the inclination angle θ is 180 °.

Then, based on the inclination angle θ and the phase α, the shape of the work W can be expressed by the following equation (9) Δt = r _W · sin [α-sin ^-1 {r _W / (2 · R _G )}] It is determined based on (9). Note that in equation (9), Δt
Is the distance r from the center on the front surface (back surface) of the work W.
_This is the distance between the virtual center plane of the work W and the front surface (back surface) of the work, where _W is a variable. R _G is the radius of the grindstone 11. The thickness T of the work W is the sum of the distance (Δt) between the virtual center plane and the front surface of the work W and the distance (Δt) between the virtual center plane and the back surface of the work W. The shape of the workpiece W according to the inclination angle θ and its phase α is determined by the equation (9).

Hereinafter, the phase α and the shape of the work W will be described more specifically. FIG. 17 shows that the inclination angle θ is θ = θ1.
FIG. 9 is a schematic diagram illustrating a vertical cross-sectional shape of a work W corresponding to a phase α when (> 0).

FIG. 17A shows the phase α as shown in FIG.
Shows the shape of the work W when α = 0. In this case, the relationship between the center thickness Tc, the edge thickness Te, and the intermediate thickness Tm of the workpiece W is Tc <Tm <Te.
(Corresponding to the first condition).

FIG. 17B shows the phase α as shown in FIG.
Shows the shape of the work W when α = 30 °. In this case, the relationship between the center thickness Tc, the edge thickness Te, and the intermediate thickness Tm of the work W is Tc> Tm and Te> Tm (corresponding to the second condition).

FIG. 17C shows the phase α as shown in FIG.
Shows the shape of the work W when α = 120 °. In this case, the relationship between the center thickness Tc, the edge thickness Te, and the intermediate thickness Tm of the work W is expressed as Tc>Tm>
Te and Tc−Tm ≒ Tm−Te (corresponding to the third condition)
It is.

FIG. 17D shows the phase α as shown in FIG.
Shows the shape of the work W when α = 180 °. In this case, the relationship between the center thickness Tc, the edge thickness Te, and the intermediate thickness Tm of the work W is expressed as Tc>Tm>
Te and Tc-Te ≒ Tm-Te (corresponding to the fourth condition)
It is.

When the phase α is α = 90 °, the shape of the work W does not correspond to any of the above-mentioned FIGS.

As described above, the posture of the grindstone 11 and the work W
Since the relationship between the displacement sensors 50c and 50c '; 50e and 50e';
m, the center thickness T of the workpiece W obtained by 50 m '
c, the edge thickness Te, and the intermediate thickness Tm, the grinding wheels 11, 21 characterized by the inclination angle θ and the phase α thereof.
Posture can be recognized.

First, if Tc = Te = Tm, it is estimated that the work W is ground flat. That is, the inclination angle θ is estimated to be θ = 0. On the other hand, in other cases, the inclination angle θ is estimated to be θ ≠ 0. When the inclination angle is θ ≠ 0, the control unit 5 estimates the phase α and the inclination angle θ according to the following procedure.

First, the control unit 5 determines the center thickness T of the workpiece W.
The relationship between c, the edge thickness Te, and the intermediate thickness Tm is examined.
The center thickness Tc, the edge thickness Te, and the intermediate thickness T
When the relationship of m is Tc <Tm <Te, FIG.
As shown in FIG. 17A, the phase α is α = 0.
Is determined. In this case, the inclination angle θ is calculated based on the following equation (10) θ = 2 · (Te−Tc) / ( _RG · sin (π / 3)) (10)

When the relationship between the center thickness Tc, the edge thickness Te, and the intermediate thickness Tm is Tc> Tm and Te> Tm, as shown in FIGS. 14 and 17B. The phase α is determined to be α = 30 °. In this case,
The inclination angle θ is calculated based on the following equation (11) θ = 2 · (Te + Tc−2 · Tm) / (2 · _RG · (1−cos (π / 12))) (11) .

The relationship between the center thickness Tc, the edge thickness Te, and the intermediate thickness Tm is such that Tc>Tm> Te and Tc−T
When m ≒ Tm-Te, the phase α is determined to be α = 120 ° as shown in FIGS. 15 and 17C. In this case, the inclination angle θ is calculated based on the following equation (12) θ = (Tc−Te) / (2 · _RG · sin (π / 12)) (12)

The relation between the center thickness Tc, the edge thickness Te, and the intermediate thickness Tm is Tc>Tm> Te and Tc−T
When e ≒ Tm−Te, as shown in FIGS. 16 and 17D, the phase α is determined to be α = 180 °. In this case, the inclination angle θ is calculated based on the following equation (13) θ = 2 · (Te−Tc) / ( _RG · sin (π / 3)) (13)

Note that the relationship between the center thickness Tc, the edge thickness Te, and the intermediate thickness Tm is not Tc = Te = Tm, and does not correspond to any of the states (A) to (D) in FIG. First
To the fourth condition are not satisfied), the phase angle α is α
= 90 °. In this case, the inclination angle θ is based on the following equation (14) θ = (Te−Tc) / (2 · _RG · sin (π / 12) · cos (π / 6)) (14) Is calculated.

Then, the control unit 5 controls the grinding wheels 11 and 12 based on the inclination angle θ and the phase α estimated as described above.
In addition to recognizing the relative position and posture of the work W, the work W is ground into a desired shape.

Specifically, if the control unit 5 is to grind the work W into a flat disk shape, the servo valve 123
V, 124 V, 125 V, 126 V, and 127 V are controlled to adjust the inclination angle θ of both grinding wheels 11 and 21 to θ = 0.
Then, the work W is ground into a flat disk shape.

In some cases, it is preferable that the workpiece W is ground into a predetermined shape other than the flat shape in view of the relationship with the processes after the grinding process by the double-headed grinding machine. In such a case, the control unit 5 controls each servo valve 123V, 124
By controlling V, 125V, 126V, and 127V to adjust the inclination angle θ and the phase α of both grindstones 11, 21, the work W can be ground into a desired shape.
That is, the work W is processed into a desired shape selected from, for example, FIGS. 17A to 17D.

<Procedure of Grinding Process> The process of grinding the work W into a desired shape by the double-headed grinding machine will be described below. First, the operator adjusts the dressing of the grinding wheels 11 and 21 and the like, and then instructs the control unit 5 to adjust the zero point of each displacement sensor 50. The work holding device 3 is set at the retracted position, and the work holding device 3
The work W is not held in the work holder 31 of FIG.
When receiving the instruction for the zero point adjustment, the control unit 5 sets each displacement sensor 50 to the measurement state. Then, the corresponding contacts 52 of each displacement sensor 50 contact each other. Then, the control unit 5 controls each displacement sensor 50 in this state.
0 of each of these displacement sensors 50 based on the output signal from
Perform point adjustment. After this zero point adjustment, each displacement sensor 50
Is set to the standby state.

Thereafter, the control section 5 causes the work holder 31 to hold the work W before grinding by a robot (not shown), and moves the work holding device 3 to the grinding position. At the same time, the control unit 5 rotates the grindstones 11 and 21 at high speed by rotating the spindle motor 128. At this point, the postures of the grinding wheels 11 and 21 are not adjusted.

Then, the control section 5 proceeds with the grinding process according to the flowchart of FIG. In the first step S1 after the start of the flowchart of FIG. 18, the control unit 5 controls the drive supply unit 15 while monitoring the output from the linear sensor 16 so that the two spindle devices 1 and 2 are separated at a predetermined cutting speed. Make them approach each other. Then, when the two spindle devices 1 and 2 reach the predetermined interval, the control unit 5 advances the processing to S2. This interval is
The interval is set to such an extent that the two grindstones 11 and 21 abut on the entire area of the front and back surfaces of the work W (so-called full contact). In the following S2 to S7, the spindle devices 1 and 2 are kept close to each other.
However, the control unit 5 may make the cutting speed constant,
It may be changed.

In S2, the control unit 5 continues the grinding,
Each displacement sensor 50 is set to a measurement state. Then, the contact 52 of each displacement sensor 50 comes into contact with the workpiece W, and the control unit 5 determines the center thickness Tc, the edge thickness Te, and the edge thickness Te of the workpiece W.
And the intermediate thickness Tm. Note that the control unit 5 continues to acquire the output signals from each displacement sensor 50 while the work W rotates several times, and determines the average value of the acquired output signals as the thickness value (Tc, Te, Tm). . Then, immediately after the center thickness Tc, the edge thickness Te, and the intermediate thickness Tm are determined, the control unit 5 sets each displacement sensor 50 to a standby state.

In the next S3, the control section 5 determines whether or not the work W is in a desired state. That is, the control unit 5 determines the center thickness Tc, the edge thickness Te,
Then, it is determined whether or not the intermediate thickness Tm matches a predetermined target value. Note that the target value is individually determined in correspondence with each of the center thickness Tc, the edge thickness Te, and the intermediate thickness Tm. And the control unit 5
Advances the process to S7 if the workpiece W is in a desired state, and advances the process to S4 otherwise.

In S4, the control unit 5 acquires the attitude of the grindstones 11 and 21 based on the center thickness Tc, the edge thickness Te, and the intermediate thickness Tm acquired in S2. That is, the control unit 5
Calculates the inclination angle θ and the phase α thereof, which characterize the relative attitude of the grindstones 11 and 21 with respect to the workpiece W, as described above.

In the next S5, the control unit 5 adjusts the postures of the two grindstones 11 and 21 based on the inclination angle θ and the phase α obtained in S4 so that the work W has a desired shape. That is, the control unit 5 monitors the outputs from the X sensor 123S, the Y sensor 124S, and the Z sensors 125S, 126S, and 127S while controlling the servo valves 123V and 12S.
4V, 125V, 126V, 127V are controlled respectively,
The postures of the grindstones 11 and 21 are respectively adjusted so that the inclination angle θ and the phase α have desired values.

In the next S6, the control unit 5 controls the two grinding wheels 11,
While maintaining the posture of S21 adjusted in S5, grinding is continued for a predetermined time. Then, after a predetermined time has elapsed, the control unit 5 returns the processing to S2.

In S7, since it is determined that the work W has been ground to a desired state in S3, the control unit 5
The final grinding is executed and the processing is terminated. That is, the control unit 5
Continues grinding for at least one rotation of the workpiece W,
The process ends. In addition, even if the contact mark by the contact 52 of the displacement sensor 50 remains on the front and back surfaces of the workpiece W,
The contact marks disappear by the final grinding. That is, the surface of the work W is finished in a smooth state.

As described above, the control unit 5 controls the displacement sensors 5
Work W based on measurement by 0 (in-process measurement)
The workpiece W can be ground into a desired shape by monitoring the shape of the workpiece and adjusting the postures of the two grindstones 11 and 21. Since the control unit 5 monitors the shape of the work W,
Until the workpiece W approaches a desired shape, the cutting speed can be increased, and when the workpiece W approaches the desired shape, the cutting speed can be reduced. Then, the yield of the work W is kept high, and the time required for grinding is reduced.

Thereafter, similarly, the unprocessed work W is ground. The zero point adjustment of each displacement sensor 50 may be performed every time, or may be performed after grinding is performed a predetermined number of times.

<Modification> Although the displacement sensor 50 in the above embodiment is a contact displacement sensor having a contact 52, the displacement sensor 50 may be a non-contact displacement sensor. That is, this non-contact type displacement sensor is
A non-contact type displacement sensor provided with a displacement acquisition unit that measures a displacement component in a direction parallel to the rotation axis of the workpiece W without contacting the workpiece W. For example, the non-contact displacement sensor may be a laser focus displacement meter or an eddy current displacement sensor. in this way,
If a non-contact sensor is used, the processing of the final grinding (S7) in the flowchart of FIG. 18 becomes unnecessary.

Hereinafter, a sensor unit having a laser focus displacement meter will be described more specifically. FIG.
9 is a work holder 3 having the sensor unit 60.
It is a block diagram showing 1 '. This work holder 31 ′
The configuration of the work holder 31 of the above embodiment shown in FIG. 8 is characterized in that the sensor unit 60 of the present modification is provided. It should be noted that the work holder 31 ′ of the present modification is
Does not have the contact-type displacement sensor 50 described above. For this reason, the support pad 3 of the work holder 31 'of the present modification is
18 (, 318 ′), a through hole for the displacement sensor 50 is not formed.

FIG. 20 is a sectional view taken along the line JJ in FIG. As shown in FIG. 20, the sensor unit 60 includes a laser focus displacement meter (hereinafter, abbreviated as displacement meter) 61. The displacement meter 61 is a non-contact sensor that includes a laser light source and an objective lens (not shown) and vibrates the objective lens at a high speed in the optical axis direction to sweep a predetermined area in the beam axis direction of the laser beam. .

The sensor unit 60 further includes a guide member 62 fixed to the frame 311, a motor 63, and a ball screw 64. The guide member 62, the motor 63, and the ball screw 64 correspond to a sensor slide mechanism. As shown in FIG. 19, a predetermined measurement line segment F is virtually set from the center to the edge of the disk-shaped region where the workpiece W rotates. The guide member 62 guides the displacement meter 61 movably along the measurement line segment F.

As shown in FIG. 20, the motor 63
The male screw of the ball screw 64 is attached to the output shaft of the guide member 62. The internal thread of the ball screw 64 is fixed to the displacement meter 61.

The sensor unit 60 is provided so as to correspond to the surface of the work W. Further, a sensor unit 60 ′ configured similarly to the sensor unit 60 is provided corresponding to the back surface of the work W. As shown in FIG. 20, the sensor unit 60 ′
Are arranged symmetrically with the sensor unit 60 with respect to the plane on which the workpiece W rotates.

The two sensor units 60, 60 'are
Each is connected to the control unit 5. Then, the control unit 5 drives the motors 63, 63 respectively to rotate the male screws of the ball screws 64, 64, thereby moving the displacement meters 61, 61 in synchronization with the measurement line segment F.
These two displacement meters 61 do not contact the workpiece W,
The position of each of the front and back surfaces of the work W is acquired, and a signal indicating the position is transmitted to the control unit 5. And the control unit 5
Acquires the distance between the front and back surfaces of the work W along the measurement line F based on the positions of the front and back surfaces of the work W along the measurement line F. That is, the thickness of the work W along the measurement line F is scanned and measured.

Since the work W is ground rotationally symmetrically, when scan measurement is performed along the measurement line F extending from the center of the work to the edge as described above, the cross-sectional shape of the work W becomes substantially complete. Is obtained. Then, the control unit 5 controls both the spindle devices 1 and 2 based on the shape acquired by the scan measurement, and processes the work W into a desired shape.

[0135]

According to the work holder of the present invention configured as described above, it is possible to measure the thickness of the work during machining, so that the finished shape of the work is strictly managed, and Yield also improves.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a double-headed grinding machine according to an embodiment of the present invention.

FIG. 2 is a diagram showing a control system relating to a spindle device.

FIG. 3 is a longitudinal sectional view schematically showing a configuration of a main shaft portion.

FIG. 4 is a perspective view showing the vicinity of a fixed shaft of a main shaft portion.

FIG. 5 is an explanatory diagram showing control of a main shaft portion in a radial direction.

FIG. 6 is an explanatory view showing control of a main shaft portion in a thrust direction.

FIG. 7 is an explanatory view of the principle of an opposed pad hydrostatic bearing.

FIG. 8 is a configuration diagram of a work holding device.

9 is a sectional view taken along line 9-9 in FIG.

FIG. 10 is a schematic diagram showing a displacement sensor.

FIG. 11 is a diagram showing a control system relating to a displacement sensor and a cylinder mechanism.

FIG. 12 is an explanatory view showing a posture of a grindstone.

FIG. 13 is an explanatory diagram showing a posture of a grindstone.

FIG. 14 is an explanatory diagram showing a posture of a grindstone.

FIG. 15 is an explanatory diagram showing a posture of a grindstone.

FIG. 16 is an explanatory diagram showing a posture of a grindstone.

FIG. 17 is an explanatory view showing a shape of a work.

FIG. 18 is a flowchart illustrating a grinding process according to an embodiment of the present invention.

FIG. 19 is a configuration diagram showing a work holder according to a modified example.

20 is a sectional view taken along line JJ in FIG. 19;

[Explanation of symbols]

1, 2 Spindle device 11, 21 Cup-type grindstone 12 Main shaft portion 121 Fixed shaft 122 Outer ring 123 (a, b), 124 (a, b) Radial static pressure pad 125 (a, b) to 127 (a, b) Thrust Static pressure pad 123V to 127V Servo valve 128 Spindle motor 3 Work holding device 31 Work holder 312 Support pad 313,314 Drive roller 50 Displacement sensor 52 Contact

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) // B24B 49/04 B24B 49/04 Z (72) Inventor Yoshiyuki Tomita Yuyugaoka 63rd, Hiratsuka-shi, Kanagawa No. 30 Sumitomo Heavy Industries Machinery Co., Ltd. Hiratsuka Works (72) Inventor Kazutaka Hara 63-30 Yuyogaoka, Hiratsuka-shi, Kanagawa Prefecture Sumitomo Heavy Industries Machinery Co., Ltd. Hiratsuka Works (72) Inventor Shinichiro Tsukahara Hiratsuka, Kanagawa Prefecture 63-30 Yuyogaoka Sumitomo Heavy Industries Machinery Co., Ltd. Hiratsuka Office F-term (reference) 3C029 BB02 3C034 AA08 BB75 BB92 CA05 CA12 3C043 BC06 CC04 DD05

Claims (7)

[Claims] 1. A rotation holding section for rotating a disk-shaped work in a predetermined disk-shaped area, and a measurement section for measuring an interval between the front and back surfaces of the work at a predetermined measurement position in the disk-shaped area. A work holder comprising: 2. The apparatus according to claim 1, wherein the measuring unit measures the distance between the front and back surfaces of the work at a plurality of measurement positions at different distances from the center on the front and back surfaces of the disc-shaped region. 1. The work holder according to 1. 3. The measuring section determines the distance between the front and back surfaces of the work at the measurement position near the center, the measurement position near the edge, and the measurement position between the center and the edge on the front and back surfaces of the disc-shaped region. 3. The method according to claim 2, wherein each measurement is performed.
Work holder as described. 4. The work holder according to claim 1, wherein the measurement section includes a pair of displacement sensors arranged corresponding to the measurement position. 5. The displacement sensor according to claim 1, wherein the displacement sensor is a contact-type displacement sensor having a contact that measures a displacement component in a direction parallel to a rotation axis of the work by coming into contact with the work. Item 5. The work holder according to Item 4. 6. A non-contact type displacement sensor comprising a displacement acquisition device for measuring a component of displacement in a direction parallel to a rotation axis of the work without contacting the work. The work holder according to claim 4, wherein 7. A sensor slide mechanism for moving said non-contact type displacement sensor along a predetermined measurement line segment in said disc-shaped area; and controlling said sensor slide mechanism to produce said non-contact type displacement sensor. While moving along the measurement line segment, a control unit that acquires the interval between the front and back surfaces of the work along the measurement line segment based on the component of the displacement measured by the non-contact displacement sensor, 7. The apparatus according to claim 6, further comprising:
Work holder as described.