JPH07227756A - Method and device for polishing work - Google Patents

Abstract

PURPOSE:To accurately polish work into a desired thickness. CONSTITUTION:A probe 17 detects the transition of an upper surface plate 1 that is lowered as the thickness of work 6 decreases, and thereby the thickness of the work 6 under machining is measured, and the machining is temporarily stopped when the thickness equals a reference desired value that is slightly greater than a final desired value. The work 6 stopped has its true thickness measured by a true thickness measurement means 21 while being held on a carrier 5, and the amount of wear of the upper surface plate l is calculated from the difference between the true thickness and the reference desired value, and the final desired value is reset based on the amount of wear, and the work is machined again until its thickness reaches the final desired value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing method and apparatus for polishing a work to a predetermined thickness.

[0002]

2. Description of the Related Art An automatic sizing device is used when a work is polished to a predetermined thickness by using a flat polishing device such as a lapping machine or a polishing machine. For such a sizing device, an indirect measuring method that detects displacement and weight change of the upper surface plate during processing and converts it into the thickness of the work, and directly measures the thickness of the work during processing. There is a direct measurement method.

As an indirect measurement type sizing device, for example, Japanese Patent Publication No. Sho 64-4126 discloses a device using a magnescale. This detects the displacement of the upper surface plate that descends with the decrease of the work thickness by the probe,
Convert the amount of displacement into the work thickness and compare it with the target value,
The processing is stopped when the thickness becomes equal to the target value.

However, in such a measuring method,
Since the wear of the upper surface plate is detected as a displacement, the thickness of the work measured by the wear amount becomes thicker than the actual thickness, and there is a drawback that an accurate sizing cannot be performed.

Therefore, there has been proposed a sizing device which detects not only the displacement amount of the upper surface plate but also the abrasion amount and corrects the displacement amount by the abrasion amount (see Japanese Patent Laid-Open No. 62-188671). ) Is a method that indirectly determines the thickness of the work from the amount of displacement of the upper surface plate, so it is difficult to completely eliminate the influence of abrasive grains, etc., which are present between the surface plate and the work. It was

On the other hand, as a direct measuring type sizing device,
It is known to measure the thickness of a work using ultrasonic waves. This is to attach an ultrasonic transducer to the upper surface plate of the polishing device, measure the thickness of the work from the time until ultrasonic waves are projected from this transducer to the work and the echo is received. The thickness of the work can be measured.

However, in the method of measuring the thickness of a work by using ultrasonic waves during processing, noise is generated by the abrasive grains contained in the abrasive slurry, and a measurement error is likely to occur, and If you try to sample the signal related to the thickness while constantly flowing water to the detection site in order to reduce the influence of the abrasive grains, there will be a problem that the polishing accuracy decreases, such as scratching the work because the abrasive concentration changes. .

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polishing method capable of reliably polishing a work to a predetermined thickness and a polishing apparatus for carrying out the method.

[0009]

In order to solve the above-mentioned problems, the first polishing method of the present invention is to make a carrier, which is meshed with a sun gear and an internal gear, driven like a planetary gear, to hold a work. In a polishing method of polishing the work by sandwiching it from both sides by an upper surface plate and a lower surface plate until a predetermined thickness is obtained; as a dimensional target value for processing, a value smaller than a final target value as a finished thickness of the work The step of setting a thick reference target value; the step of polishing the workpiece; the thickness of the workpiece being processed is measured from the displacement of the upper surface plate that descends as the thickness of the workpiece decreases, and the thickness is the above-mentioned reference target. The process of stopping the processing halfway when it becomes equal to the value; the process of measuring the actual thickness of the workpiece stopped at a predetermined position while being held by the carrier by the actual thickness measuring means; the actual thickness of the workpiece and the reference target Is it a difference from the value? It is characterized by having a step of calculating the wear amount of the surface plate and setting a final target value based on the wear amount; a step of reworking until the work thickness reaches the final target value. .

After the re-machining, the actual thickness of the work is measured and compared with the final target value. If they are equal, the machining is terminated. If the actual thickness is larger than the final target value, the wear amount of the surface plate Based on the above, the final target value may be reset and reworking may be performed.

In the second polishing method of the present invention, a carrier is held by a carrier that meshes with a sun gear and an internal gear and is driven like a planetary gear, and the work is supported on both sides by an upper surface plate and a lower surface plate. In the polishing method of sandwiching and grinding to a predetermined thickness; estimating the processing time until the work thickness reaches a reference target value slightly thicker than the final target value, and setting that processing time as the target value The step of polishing the workpiece; the step of stopping the processing halfway when the set processing time has elapsed; the actual thickness of the workpiece stopped at a predetermined position is held by the carrier by the actual thickness measuring means. Process of measuring as it is; calculating the processing speed from the actual thickness of the work, the thickness before processing and the processing time until then, estimating the processing time from the calculated processing speed to the final target value and resetting Process; It is characterized in that it has a; step for rework only boss was processed time period.

After the re-machining, the actual thickness of the work is measured and compared with the final target value. If they are equal, the machining is terminated. If the actual thickness is larger than the final target value, the final target value is reached. It is also possible to reset the processing time of and re-process.

The polishing apparatus for carrying out the first method is a sun gear and an internal gear that are coaxially arranged and can be driven and rotated in a predetermined direction; A plurality of workpiece holding carriers that mesh with each other and are driven in the shape of a planetary gear; upper and lower surface plates that can be driven and rotated to grind the workpieces held by the carrier from both sides;
Driving means for driving the sun gear, the internal gear, the upper surface plate and the lower surface plate; the thickness of the workpiece being processed is measured from the displacement of the upper surface plate which descends as the thickness of the workpiece decreases, and the thickness is Sizing means to stop the processing when it becomes equal to the target value;
An actual thickness measuring means for measuring the actual thickness of the work when the machining is stopped due to the sizing means working; measured when the machining is stopped due to the sizing means working And a control means for calculating the wear amount of the surface plate from the difference between the actual thickness of the work and the target value at that time and setting the final target value based on the wear amount. It is a thing. The actual thickness measuring means is an ultrasonic detector for measuring the thickness of the workpiece by ultrasonic waves in a non-contact manner, and a water supply mechanism for supplying water between the ultrasonic detector and the workpiece during the actual thickness measurement. And measuring the actual thickness of the work through a measurement hole formed in the upper surface plate. According to a preferred aspect of the present invention, the ultrasonic detector and the water supply hole of the water supply mechanism in the actual thickness measuring means are provided in the measuring head at the tip of the arm that is movable up and down and rotatable by the driving unit, During processing, the measuring head occupies a standby position apart from the upper surface plate, and is rotated to the position of the measurement hole of the upper surface plate when measuring the actual thickness of the work. It is desirable that the polishing apparatus be provided with a fixed position stopping means for stopping the carrier at a predetermined rotation position and revolving position when the processing is stopped. The fixed position stopping means detects a mark provided on the upper surface plate to stop the upper surface plate at a desired rotation position, and a revolving carrier to detect the carrier. It has a revolution position sensor for stopping at the revolution position and a rotation position sensor for stopping the carrier at a required rotation position by detecting a mark provided on the carrier.

Further, the polishing apparatus for carrying out the second method comprises a sun gear and an internal gear which are coaxially arranged and can be driven to rotate in a predetermined direction; and mesh with the sun gear and the internal gear. And a plurality of workpiece holding carriers that are driven like planetary gears; drive and rotatable upper and lower surface plates that sandwich the workpieces held by the carrier from both sides; the sun gear, the internal gear, and the upper Driving means for driving the surface plate and the lower surface plate; a sizing means configured to set a target value of the work thickness as a processing time, and stopping the processing when the set processing time elapses; sizing means Means for measuring the actual thickness of the work when the work is stopped due to the fact that the work is held by the carrier; the actual thickness of the work and the thickness before the work and the processing time until then. When calculating the processing speed from To, estimates the processing time from the calculated machining speed to a final target value, control means for setting the processing time; is intended to characterized in that it comprises a. The actual thickness measuring means is an ultrasonic detector for measuring the thickness of the workpiece by ultrasonic waves in a non-contact manner, and a water supply mechanism for supplying water between the ultrasonic detector and the workpiece during the actual thickness measurement. And measuring the actual thickness of the work through a measurement hole formed in the upper surface plate. According to a preferred aspect of the present invention, the ultrasonic detector and the water supply hole of the water supply mechanism in the actual thickness measuring means are provided in the measuring head at the tip of the arm that is movable up and down and rotatable by the driving unit, During processing, the measuring head occupies a standby position apart from the upper surface plate, and is rotated to the position of the measurement hole of the upper surface plate when measuring the actual thickness of the work. It is desirable that the polishing apparatus be provided with a fixed position stopping means for stopping the carrier at a predetermined rotation position and revolving position when the processing is stopped. The fixed position stopping means detects a mark provided on the upper surface plate to stop the upper surface plate at a desired rotation position, and a revolving carrier to detect the carrier. It has a revolution position sensor for stopping at the revolution position and a rotation position sensor for stopping the carrier at a required rotation position by detecting a mark provided on the carrier.

[0015]

[Operation] The polishing of the work is stopped halfway, the actual thickness of the work is measured, and the final target value is reset in consideration of the wear amount of the surface plate until then, or the work is reprocessed. Or
Since the processing time from the processing speed up to that time to the final target value is estimated and the processing is performed again for the estimated processing time, the work can be surely polished to a predetermined thickness.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described in detail below with reference to the drawings. FIGS. 1 to 3 show a first embodiment of a polishing apparatus, which is coaxially arranged. A plurality of carriers 5 which are provided with upper and lower surface plates 1 and 2, a sun gear 3 and an internal gear 4, and are driven by both gears 3 and 4 in a planetary gear shape.
The work 6 held by the above is sandwiched between the upper and lower surface plates 1 and 2 from both sides and polished.

The two surface plates 1 and 2 and the gears 3 and 4 are connected to a drive source 7 including a motor and the like via drive shafts 1a to 4a arranged coaxially and driven by a controller 8. Are controlled. Of these, the lower platen 2 and both gears 3 and 4 are attached to the upper ends of the respective drive shafts 2a to 4a, while the upper platen 1 extends from a lifting cylinder (not shown) attached to the machine body. A surface plate suspension 11 mounted on a vertically movable rod 9 via a self-aligning bearing 10, and a plurality of studs 1 suspended from the surface plate suspension.
2. Attached via the relay plate 13 fixed to the lower end of the stud, and by engaging the locking member 14 on the relay plate 13 with the driver 1b at the upper end of the drive shaft 1a in the lowered position shown in the drawing, It is adapted to be driven via the driver 1b.

A probe 17 of a sizing device is attached to the upper inner end of the upper surface plate drive shaft 1a. This sizing device detects, with the probe 17, the displacement of the upper surface plate 1 which is descending as the thickness of the work 6 is reduced during processing.
The thickness of the work 6 is calculated from the amount of displacement, and compared with a target value that is input in advance to the controller 8, and when the thickness becomes equal to the target value, the machining is automatically stopped. .

The probe 17 is of a contact type which is composed of a magnetic scale or the like, and the stylus 17a is brought into contact with the detection plate 15 on the lower surface of the surface plate suspension 11 on the upper surface plate 1, and the detection plate 15 or upper surface. The displacement of the surface plate 1 is converted into an electric signal by the stylus 17a and taken out. A non-contact type probe such as an air gauge can also be used.

The body 20 of the polishing apparatus is provided with an actual thickness measuring means 21 for measuring the actual thickness of the work 6. The actual thickness measuring means 21 measures the thickness of the work using ultrasonic waves in a non-contact manner and without taking out the work, and is installed on the machine body 20 as shown in detail in FIG. Drive unit 22, a horizontal arm 23 supported by the drive unit 22 so as to be vertically movable and rotatable, and a measuring head 24 provided at the tip of the horizontal arm 23. An ultrasonic detector 26 that projects an ultrasonic wave to the work 6 through a measurement hole 25 formed in the upper surface plate 1 and receives an echo from the work.
A water supply hole 27 for supplying water as an ultrasonic wave propagation medium into the measurement hole 25 during measurement, an air vent hole 28 for discharging air in the measurement hole 25 at the time of water supply, and the measurement head 24 on the upper surface plate 1
And a sealing member 29 for contacting in a fluid-tight manner with the ultrasonic detector 26 is connected to the control device 8 via a cable 26a, and the water supply hole 27 is provided with a water supply pipe 27a.
It is connected to the water supply source 30 via.

Although not shown in the figure, the drive unit 22 is provided with an air cylinder and a motor. The air cylinder raises and lowers the horizontal arm 23, and the motor rotates the axis of the air cylinder by a required angle. Is designed to
When the actual thickness is not measured, the horizontal arm 23
The measurement head 24 at the leading end occupies the standby position separated from the upper surface plate 1 by being raised by a predetermined distance from the measurement position of FIG.

The actual thickness measuring means 21 comprises a probe 17
Measuring the actual thickness of the workpiece 6 when the sizing device is activated and the machining is stopped because the thickness of the workpiece 6 being processed equal to the reference target value is measured.
The measured actual thickness is input to the control device 8, the wear amount of the upper surface plate 1 is calculated from the difference between the actual thickness and the reference target value, and the work size 6 of the work 6 is set in the sizing device based on the wear amount. The final target value, which is the finished thickness, is set. Then, the machining is started again, and the machining is performed until the thickness of the work 6 becomes equal to the final target value.

Both the reference target value and the final target value are set in advance in the sizing device, and the final target value is reset (corrected) when the wear amount of the upper surface plate 1 is calculated. You can

In order to always stop the upper surface plate 1 and the carrier 5 at a fixed position when the processing is stopped by the above-mentioned sizing device, that is, the upper surface plate 1 has the measuring hole 25 by the actual thickness measuring means 21. Stop so that it comes to the measurement position,
A fixed position stop device is provided for stopping the carrier 5 so that one of the workpieces 6 comes to a position corresponding to the measurement hole 25. This fixed position stop device is the upper surface plate 1
A rotational position sensor 3 for detecting the rotational position of the upper surface plate 1 by a detected piece 31 as a mark attached to the outer periphery of the
2, a revolving position sensor 33 that detects when the carrier 5 revolves to a predetermined position, and a small hole 34 as a mark formed in the carrier 5 at a required number of intervals to detect the carrier 5. A rotation position sensor 35 for detecting a rotation position and a rotation position sensor 35 are attached respectively, and each of these sensors is connected to the control device 8 described above, and a position detection signal output from each sensor to the control device 8 causes an upper surface plate. 1 and the carrier 5 are stopped at a predetermined rotation position and revolution position. Each of the above sensors 32,
Any detection method using magnetism, light, or the like can be used as 33 and 35.

In the flat surface polishing apparatus of the first embodiment having the above-mentioned structure, prior to the polishing process of the work 6, the controller 8 controls the final target as the finished thickness of the work 6 as the dimensional target value for the process. A reference target value that is slightly thicker than the value is set, and zero adjustment of the sizing device is performed.
This zero point adjustment lowers the upper surface plate 1 to the lowest point without loading the work 6 between the upper and lower surface plates 1 and 2, and sets the position of the upper surface plate 1 at that time detected by the probe 17 to the zero point. It is done by doing.

The work 6 is polished by the respective carriers 5 with the upper surface plate 1 being raised, as in a known flat surface polishing apparatus.
Hold the workpiece 6 and lower the upper surface plate 1 to lower the workpiece 6.
Is sandwiched between the lower platen 2 and the upper platen 1 and a desired working pressure is applied to the work 6 by the upper platen 1, and in that state, both gears 3,
4 and both surface plates 1 and 2 are rotated at a predetermined direction and speed. At this time, the actual thickness measuring means 21
Is not in the measurement position as shown in FIGS. 1 and 2, but is rotated to a standby position that does not interfere with the processing.

During the processing, the upper surface plate 1 gradually descends as the thickness of the work 6 decreases, but the displacement amount is constantly detected by the probe 17 via the detection plate 15, and the detected displacement is detected. The thickness of the workpiece 6 being machined is obtained from the quantity and compared with a reference target value in the controller 8.
Then, when the thickness of the work 6 becomes equal to the reference target value, the sizing device is activated to stop the processing midway.

When stopping the above-mentioned processing, the respective surface plates 1 and 2 are
The fixed position stop device operates when the gears 3 and 4 are decelerated to a low speed rotation state, and when the measurement hole 25 of the upper surface plate 1 reaches the actual thickness measurement position, the rotation position sensor 32 detects the detected position. The upper surface plate 1 and the lower surface plate 2 are stopped at their rotational positions by detecting the piece 31, and when the carrier 5 reaches a predetermined revolution position, the revolution position sensor 33 causes the carrier 5 to move.
Is detected and both gears 3 and 4 stop, the carrier stops at its revolution position, and then the internal gear 4
And the sun gear 3 rotate at the same speed and in opposite directions at a low speed, the carrier 5 rotates at a fixed position, and when one of the workpieces 6 comes to a position corresponding to the measurement hole 25, the rotation position sensor The carrier 5 stops at its rotation position when 35 detects the small hole 34.

Subsequently, the horizontal arm 23 of the actual thickness measuring means 21 rotates from the standby position toward the measuring position, and
By descending by a predetermined distance, as shown in FIG. 2, the measurement head 24 at the tip comes into contact with the upper surface of the upper surface plate 1 at the position of the measurement hole 25. Then, while supplying water into the measurement hole 25 through the water supply hole 27, ultrasonic waves are projected from the ultrasonic detector 26 to the work 6 and the echo from the work 6 is received, whereby the actual thickness of the work 6 is obtained. Is measured. The measured actual thickness is input to the control device 8, the wear amount of the surface plate is calculated from the difference between the actual thickness and the reference target value, and the final target value is set based on the wear amount. When the final target value is preset in the control device 8, the corrected value is reset.

When the actual thickness is measured and the final target value is set, the water supply is stopped, the actual thickness measuring means 21 is rotated again to the standby position, and the polishing apparatus is restarted. Processing is restarted. Then, when the thickness of the work 6 becomes equal to the final target value, the sizing device operates and the processing ends.

The measurement of the actual thickness is performed by interrupting the processing, and water is supplied only during the measurement, and the abrasive slurry is supplied again when the processing is restarted. The supply of water during measurement does not adversely affect the polishing accuracy. Further, since the actual thickness of the work 6 can be measured in a non-contact manner, the work is not scratched and it is not necessary to take out the work, so that the working time is short and the work is performed for measuring the actual thickness. Even if the process is interrupted, it has little effect on the entire processing time.

As described above, after the re-machining is started, the machining may be terminated when the thickness of the workpiece 6 detected by the probe 17 becomes equal to the final target value and the sizing device operates. However, the actual thickness of the work 6 is measured again, the steps of comparing with the final target value, resetting the final target value, and reworking are repeated until the actual thickness becomes equal to the final target value, and they become equal. It is also possible to finish the processing when it is done.

FIG. 4 shows a second embodiment of the polishing apparatus of the present invention. In the second embodiment, the thickness of the workpiece 6 being processed by the first embodiment is measured by the probe 17, Whereas the sizing device is made to work based on the thickness,
Estimate the processing time until the work 6 reaches the desired thickness,
The difference is that the sizing device is made to work based on the processing time. The details will be described below, but since the basic structure of the polishing apparatus is the same as that of the first embodiment, the same parts are designated by the same reference numerals and the description thereof is omitted.

A sizing device 39 is incorporated in the control device 38 for controlling the drive source. This sizing device 39 is a method of estimating a target value of the thickness of the work 6 as a processing time until the thickness is reached, and setting it, and when the set processing time elapses, the processing is performed. It is configured to stop.

The machine body 20 is provided with an actual thickness measuring means 21 for measuring the actual thickness of the work 6. The actual thickness measuring means 21 has the same configuration as that of the first embodiment, and when the sizing device operates and the machining is stopped by the passage of the set machining time, The ultrasonic detector 26 measures the actual thickness of the work 6, and the measured actual thickness is input to the control device 38. In the control device 38, the actual thickness of the work 6 is compared with the set final target value. If the actual thickness of the work 6 is larger than the final target value, the actual thickness of the work 6 and the thickness before machining are compared. Then, the machining speed is calculated from the machining time and the machining time up to that time, and the machining time from the calculated machining speed to the final target value is estimated and reset. Then, the processing is started again, and the processing is performed for the reset processing time. When the actual thickness of the work 6 is equal to the final target value, the processing is completed.

When the processing is stopped as described above, the upper surface plate 1
And the carrier 5 is always stopped at a constant position, that is, the upper surface plate 1 is stopped so that the measuring hole 25 is located at the measuring position by the actual thickness measuring means 21, and the carrier 5 is stopped by any one of the workpieces 6. A fixed position stop device is provided in order to stop the measuring hole 25 so as to come to a position corresponding to the measuring hole 25. Since this fixed position stopping device is the same as that of the first embodiment, the same parts are designated by the same reference numerals and the description thereof will be omitted.

In the flat surface polishing apparatus of the second embodiment having the above-mentioned structure, prior to the processing, the processing time until the thickness of the work 6 reaches the reference target value slightly thicker than the final target value is the past experience. The sizing device 39 is estimated based on
Is set to. When the set processing time elapses, the processing temporarily stops, but at this time, the fixed position stop device operates in the same manner as in the case of the first embodiment, and any one of the workpieces 6
Stops at a position corresponding to the measurement hole 25 of the upper surface plate 1.

Subsequently, the actual thickness measuring means 21 is rotated to the measurement position shown in the figure, and the ultrasonic wave is projected from the ultrasonic detector 26 onto the work 6 and the echo from the work 6 is received. The actual thickness of the work 6 is measured.
The measured actual thickness is input to the control device 38, and the work 6
The actual thickness of the workpiece 6 is compared with the final target value. However, since the actual thickness of the workpiece 6 is larger than the final target value at this point, the actual thickness of the workpiece 6 and the thickness before machining and the machining time until then are compared. The processing speed is calculated, the processing time from the calculated processing speed to the final target value is estimated, and the processing time is reset.

Then, the polishing apparatus is activated again to start the processing, and when the processing is performed for the reset processing time, the sizing apparatus is activated to stop the processing. Although the machining may be ended here, the actual thickness of the work 6 is measured again and compared with the final target value, and when they are equal, the machining is terminated, and when the actual thickness is larger than the final target value, It is also possible to configure so that the processing time up to the final target value is reset and reprocessing is performed, and thereafter this step is repeated until the actual thickness and the final target value become equal.

In each of the above embodiments, a water-based abrasive slurry is used and water is supplied when the actual thickness of the work is measured. However, an oil-based abrasive slurry is used and the actual thickness is The oil may be supplied at the time of measurement.

Also, the actual thickness measuring means is used as the measuring head 24.
The measurement head 24 may be mounted on the measurement hole 25 of the upper surface plate 1 without being configured to rotate between the measurement position and the standby position. In this case, the ultrasonic detector 26 and control are performed. The connection with the devices 8 and 39 and the connection between the water supply hole 27 and the water supply source 30 may be performed via appropriate rotary joints.

[0042]

As described above, according to the present invention, the polishing of a workpiece is stopped halfway, the actual thickness of the workpiece is measured, the wear amount of the surface plate until then is determined, and the final target value is reset. Then, the work is re-machined, or the machining speed up to that time is calculated, the machining time up to the final target value is estimated, and the work is re-machined for the estimated machining time. The thickness can be surely polished, and
Since the actual thickness can be measured without taking out the work, the working time for the measurement is short, and even if the processing is interrupted for measuring the actual thickness, it has little influence on the entire processing time.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment of a polishing apparatus according to the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is a plan view showing a state where the upper surface plate of FIG. 1 is removed.

FIG. 4 is a sectional view of a second embodiment of a polishing apparatus according to the present invention.

[Explanation of symbols]

1 Upper Surface Plate 2 Lower Surface Plate 3 Sun Gear 4 Internal Gear 5 Carrier 6 Work 7 Drive Source 8, 38 Control Device 17 Sizing Device Probe 21 Actual Thickness Measuring Means 22 Drive Unit 23 Horizontal Arm 24 Measuring Head 25 Measuring Hole 26 Ultrasonic Detector 27 Water Supply Hole 29 Water Supply Source 31 Detected Piece 32 Rotation Position Sensor 33 Revolution Position Sensor 34 Small Hole 35 Rotation Position Sensor 39 Sizing Device

Claims (14)

[Claims] 1. A work is held by a carrier which is meshed with a sun gear and an internal gear and is driven like a planetary gear, and the work is sandwiched by an upper platen and a lower platen from both sides to a predetermined thickness. In a polishing method for polishing; a step of setting a reference target value slightly thicker than a final target value as a finished thickness of a workpiece as a dimension target value for processing; a step of polishing a workpiece; a thickness of a workpiece The process of measuring the thickness of the workpiece being machined from the displacement of the upper surface plate that descends with the decrease of, and stopping the machining midway when the thickness becomes equal to the reference target value above; A step of measuring the actual thickness while it is held on the carrier by the actual thickness measuring means; the wear amount of the surface plate is calculated from the difference between the work actual thickness and the reference target value, and the final value is calculated based on the wear amount. The work to set the target value And a step of reworking until the thickness of the work reaches a final target value. 2. After the re-machining, the actual thickness of the work is measured and compared with a final target value. When they are equal, the machining is terminated, and when the actual thickness is larger than the final target value, the The method for polishing a work according to claim 1, further comprising the step of resetting a final target value based on the amount of wear and performing rework. 3. A work is held by a carrier that meshes with a sun gear and an internal gear and is driven like a planetary gear, and the work is sandwiched by an upper surface plate and a lower surface plate from both sides until a predetermined thickness is achieved. In a polishing method for polishing; a step of estimating a processing time until the thickness of a work reaches a reference target value slightly thicker than a final target value, and setting the processing time as a target value; a step of polishing a work; A step of stopping the processing halfway when the set processing time has elapsed; a step of measuring the actual thickness of the workpiece stopped at a predetermined position while being held by the carrier by the actual thickness measuring means; The process of calculating the processing speed from the thickness, the thickness before processing and the processing time until then, and estimating and resetting the processing time from the calculated processing speed to the final target value; only the reset processing time Rework And a step of polishing the work. 4. After the re-machining, the actual thickness of the work is measured and compared with a final target value. When they are equal, the machining is terminated, and when the actual thickness is larger than the final target value, the final target value is reached. 4. The method of polishing a work according to claim 3, further comprising the step of resetting the processing time up to and performing the processing again. 5. A sun gear and an internal gear that are coaxially arranged and can be driven and rotated in a predetermined direction; a plurality of workpiece holders that mesh with the sun gear and the internal gear and are driven in a planetary gear shape. Carrier; drive-rotatable upper platen and lower platen for sandwiching the work held by the carrier from both sides; drive means for driving the sun gear, internal gear, upper platen and lower platen; Sizing means that measures the thickness of the workpiece being machined from the displacement of the upper surface plate that descends with the decrease in thickness, and stops the processing when the thickness becomes equal to the target value; Thickness measuring means for measuring the actual thickness of the workpiece when the workpiece is stopped by the carrier; the actual thickness of the workpiece measured when the sizing means is activated and the machining is stopped. From the difference between the target value and And a control means for resetting the final target value on the basis of the amount of wear of the work polishing apparatus. 6. An actual thickness measuring means for supplying water between an ultrasonic detector for measuring the thickness of a work by ultrasonic waves in a non-contact manner and water between the ultrasonic detector and the work during the actual thickness measurement. 6. The work polishing apparatus according to claim 5, wherein the work polishing apparatus is configured to measure the actual thickness of the work through a measurement hole formed in the upper surface plate. 7. The ultrasonic detector and the water supply hole of the water supply mechanism in the actual thickness measuring means are provided in a measuring head at the tip of an arm that can be moved up and down and rotated by a drive unit, and during machining of a workpiece. 7. The measuring head occupies a standby position distant from the upper surface plate and is configured to rotate to the position of the measurement hole of the upper surface plate when measuring the actual thickness of the work. The polishing apparatus for a work according to. 8. The work according to claim 5, further comprising a fixed position stopping means for stopping the carrier at a predetermined rotation position and revolving position when the processing is stopped. Polishing equipment. 9. The fixed position stopping means detects a mark provided on the upper surface plate to stop the upper surface plate at a desired rotational position, and a revolving carrier to detect the revolving carrier. 9. A revolution position sensor for stopping the carrier at a required revolution position, and a rotation position sensor for stopping the carrier at a required revolution position by detecting a mark provided on the carrier. The polishing apparatus for a work according to. 10. A sun gear and an internal gear that are coaxially arranged and can be driven and rotated in a predetermined direction; a plurality of workpiece holdings that mesh with the sun gear and the internal gear and are driven in a planetary gear shape. Carrier; drive-rotatable upper platen and lower platen for sandwiching the work held by the carrier from both sides; drive means for driving the sun gear, internal gear, upper platen and lower platen; Sizing means configured to set the target value of thickness as the processing time, and stopping the processing when the set processing time elapses; the actual thickness of the workpiece when the processing stops due to the sizing means Actual thickness measuring means for measuring the thickness while the work is held by the carrier;
Control means for calculating a machining speed from the actual thickness of the work, the thickness before machining and the machining time until then, estimating the machining time from the calculated machining speed to the final target value, and setting the machining time A polishing apparatus for a work, comprising: 11. An actual thickness measuring means for supplying water between an ultrasonic detector for measuring the thickness of a workpiece by ultrasonic waves in a non-contact manner and water between the ultrasonic detector and the workpiece during the actual thickness measurement. 11. The workpiece polishing apparatus according to claim 10, wherein the workpiece polishing apparatus is configured to measure the actual thickness of the workpiece through a measurement hole formed in the upper surface plate. 12. An ultrasonic detector in the actual thickness measuring means and a water supply hole of a water supply mechanism are provided in a measuring head at the tip of an arm which is movable up and down and rotatable by a drive unit, and is used during machining of a workpiece. The measuring head occupies a standby position distant from the upper surface plate, and is configured to rotate to the position of the measurement hole of the upper surface plate when measuring the actual thickness of the work. A polishing device for the work described. 13. The work according to claim 10, further comprising a fixed position stopping means for stopping the carrier at a predetermined rotation position and revolving position when the processing is stopped. Polishing equipment. 14. A fixed position stopping means detects a mark provided on the upper surface plate to stop the upper surface plate at a required rotational position, and a revolving carrier to detect the revolving carrier. 14. A revolution position sensor for stopping the carrier at a required revolution position, and a rotation position sensor for stopping the carrier at a required revolution position by detecting a mark provided on the carrier. The polishing apparatus for a work according to.