U.S. patent application number 09/733936 was filed with the patent office on 2001-11-15 for processing apparatus and method.
This patent application is currently assigned to TDK Corporation. Invention is credited to Ishizaki, Kazuo, Itoh, Hiroyuki, Joji, Tatsuo, Ohtsu, Yoshifumi.
Application Number | 20010041509 09/733936 |
Document ID | / |
Family ID | 18533740 |
Filed Date | 2001-11-15 |
United States Patent
Application |
20010041509 |
Kind Code |
A1 |
Ishizaki, Kazuo ; et
al. |
November 15, 2001 |
Processing apparatus and method
Abstract
An apparatus main body has a surface plate, a vertical shaft and
an arm coupled to the vertical shaft such that it can move in the
vertical direction. A spline shaft is attached to the arm such that
it can move in the vertical direction. A keeper for holding a
workpiece is attached to the lower end of the spline shaft. A
reference position sensor for detecting the position of the top
surface of a reference base as a reference position and a workpiece
dimension sensor for detecting the position of the top surface of
the keeper as a position associated with a dimension of the
workpiece are attached to the arm. During a process on the
workpiece, the absolute dimension of the workpiece is recognized
based on information detected by the sensors, and the processing
operation is controlled such that the dimension will become a
desired value.
Inventors: |
Ishizaki, Kazuo; (Tokyo,
JP) ; Joji, Tatsuo; (Tokyo, JP) ; Ohtsu,
Yoshifumi; (Tokyo, JP) ; Itoh, Hiroyuki;
(Tokyo, JP) |
Correspondence
Address: |
Oliff & Berridge PLC
P. O. Box 19928
Alexandria
VA
22320
US
|
Assignee: |
TDK Corporation
|
Family ID: |
18533740 |
Appl. No.: |
09/733936 |
Filed: |
December 12, 2000 |
Current U.S.
Class: |
451/41 |
Current CPC
Class: |
B24B 49/10 20130101;
B24B 37/345 20130101; B24B 49/04 20130101 |
Class at
Publication: |
451/41 |
International
Class: |
B24B 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 13, 2000 |
JP |
2000-005052 |
Claims
What is claimed is:
1. A processing apparatus comprising: a processing machine which
performs a predetermined process on a workpiece; a first detector
which detects a reference position; a second detector which detects
a position associated with a dimension of the workpiece which
changes as a result of the process; and a controller which
recognizes the dimension of the workpiece based on the reference
position detected by the first detector and the position detected
by the second detector and controls the processing machine such
that the dimension of the workpiece becomes a predetermined
value.
2. A processing apparatus according to claim 1, wherein the
processing machine polishes the workpiece.
3. A processing apparatus according to claim 1, wherein the first
detector and the second detector are attached to the same arm.
4. A processing apparatus according to claim 1, wherein the first
detector and the second detector intermittently perform a detecting
operation.
5. A processing apparatus according to claim 1, wherein the
controller recognizes the dimension of the workpiece based on the
result of detection performed plural times by the first detector
and the second detector.
6. A processing method for processing a workpiece utilizing a
processing apparatus having a processing machine which performs a
predetermined process on the workpiece, a first detector which
detects a reference position and a second detector which detects a
position associated with a dimension of the workpiece which changes
as a result of the process, the method comprising the steps of:
detecting the reference position with the first detector and
detecting the position associated with the dimension of the
workpiece which changes as a result of the process with the second
detector; recognizing the dimension of the workpiece based on the
reference position detected by the first detector and the position
detected by the second detector; and performing the process by
controlling the processing machine based on the recognized
dimension such that the dimension of the workpiece becomes a
predetermined value.
7. A processing method according to claim 6, wherein the processing
machine polishes the workpiece.
8. A processing method according to claim 6, wherein the first
detector and the second detector are attached to the same arm.
9. A processing method according to claim 6, wherein the detecting
step intermittently detects the positions.
10. A processing method according to claim 6, wherein the
recognizing step recognizes the dimension of the workpiece based on
the result of detection performed plural times by the first
detector and the second detector.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a processing apparatus and
method for automatically performing processes such as polishing on
workpieces made of ceramics or the like to form them into desired
dimensions.
[0003] 2. Description of the Related Art
[0004] Processing apparatuses for processing workpieces made of
ceramics or the like include polishing apparatuses such as
grinding, lapping and polishing apparatuses. Some of such
processing apparatuses including polishing apparatuses have an
automatic sizing function for automatically controlling a
processing operation to form a workpiece into desired dimensions.
For example, there are four types of conventional processing
apparatuses having the automatic sizing function as described
below.
[0005] A processing apparatus of a first type acquires a certain
signal from a workpiece (e.g., the resistance of a resistor
embedded in the workpiece) and recognizes the present state
(thickness, the distance to a target position, etc.) of the
workpiece based on the signal to control a processing
operation.
[0006] A processing apparatus of a second type controls a
processing operation based on only a signal from a machine control
system (e.g., information on the directions of three orthogonal
spindles and the rotating direction).
[0007] A processing apparatus of a third type controls a process by
setting a processing time based on processing conditions, and the
method of control depends on the judgement of the operator or
know-how.
[0008] A processing apparatus of a fourth type recognizes a process
starting position and controls a processing operation based on
displacement from the same position.
[0009] Steps for a polishing process operation utilizing a
processing apparatus of the third type will now be described with
reference to the flow chart in FIG. 9 as an example of steps for a
polishing process operation utilizing a polishing apparatus
according to the related art. In the process operation, the
dimensions of a workpiece is first measured, and a processing time
is set in the processing apparatus according to the same (step
S201). At this time, the processing time is set such that the
dimensions of the workpiece become predetermined dimensions larger
than desired dimensions in order to prevent the workpiece from
being over-polished. Next, the workpiece is secured to a keeper for
holding the workpiece (step S202). The keeper is then secured to
the processing apparatus (step S203). Next, the workpiece is
processed (step S204). The processing apparatus then determines
whether the processing time has reached the set tome or not (step
S205). If not (N), the process at step S204 is continued. If the
processing time has reached the set time (step S205; Y), the
process is stopped, and the dimensions of the workpiece are
measured and evaluated (step S206). Next, it is determined whether
the evaluation has been passed or not (step S207). If not (N), a
processing time is newly set (step S208), and the process returns
to step S204 to perform further processing. If the evaluation has
been passed (step S207; Y), the process operation is
terminated.
[0010] A processing apparatus of the first type has a problem in
that it inevitably involves a pre-process to allow the acquisition
of a signal from a workpiece. Further, some products cannot be
processed using a processing apparatus of the first type.
[0011] A processing apparatus of the second or fourth type has a
problem in that it becomes more costly as processing accuracy is
improved because the accuracy of the machine control system
(rigidity against a slide, temperature characteristics, etc.) must
be improved in order to improve processing accuracy. A processing
apparatus of the second or fourth type cannot be used as a
processing apparatus such as a chemimechanical polishing (CMP)
apparatus in which an elastic body such as a polishing cloth (pad)
is interposed between a workpiece and a surface plate. In the case
of a processing apparatus of the fourth type, it is essential to
provide a step of comparing the data of the current processing
position and the data of the process starting position in order to
detect displacement from the process starting position, which
results in a problem in that the number of processing steps is
increased.
[0012] A processing apparatus of the third type has a problem in
that the processing accuracy is low because it has significant
variation of processing depending on the state of the surface
plate, slurry and the like and the operator. Further, it has a
problem in that a workpiece must be measured before and after
processing without fail and in that it has low operating efficiency
because the processing step (step S204) and measurement/evaluation
step (S206) must normally be repeated two or more times as apparent
from FIG. 9.
SUMMARY OF THE INVENTION
[0013] It is an object of the invention to provide a processing
apparatus and method for automatically processing a workpiece into
desired dimensions which make it possible to improve processing
accuracy and efficiency without any need for a special
pre-process.
[0014] A processing apparatus according to the invention
comprises:
[0015] a processing machine which performs a predetermined process
on a workpiece;
[0016] a first detector which detects a reference position;
[0017] a second detector which detects a position associated with a
dimension of the workpiece which changes as a result of the
process; and
[0018] a controller which recognizes the dimension of the workpiece
based on the reference position detected by the first detector and
the position detected by the second detector and controls the
processing machine such that the dimension of the workpiece becomes
a predetermined value.
[0019] In the processing apparatus according to the invention, the
first detector detects the reference position; the second detector
detects the position associated with the dimension of the workpiece
which changes as a result of the process; and the controller
recognizes the dimension of the workpiece based on the positions
detected by the two detectors and controls the processing machine
such that the dimension of the workpiece becomes the predetermined
value.
[0020] The processing machine of the processing apparatus according
to the invention may polish the workpiece.
[0021] The first detector and second detector of the processing
apparatus according to the invention may be mounted on the same
arm.
[0022] The first detector and second detector of the processing
apparatus according to the invention may intermittently perform the
detecting operation.
[0023] The controller of the processing apparatus according to the
invention may recognize the dimension of the workpiece based on the
result of detection performed plural times by the first detector
and the second detector.
[0024] A processing method according to the invention is a method
for processing a workpiece utilizing a processing apparatus having
a processing machine which performs a predetermined process on the
workpiece, a first detector which detects a reference position and
a second detector which detects a position associated with a
dimension of the workpiece which changes as a result of the
process, the method comprising the steps of:
[0025] detecting the reference position with the first detector and
detecting the position associated with the dimension of the
workpiece which changes as a result of the process with the second
detector;
[0026] recognizing the dimension of the workpiece based on the
reference position detected by the first detector and the position
detected by the second detector; and
[0027] performing the process by controlling the processing machine
based on the recognized dimension such that the dimension of the
workpiece becomes a predetermined value.
[0028] In the processing method according to the invention, the
processing machine may polish the workpiece.
[0029] In the processing method according to the invention, the
first detector and second detector may be mounted on the same
arm.
[0030] In the processing method according to the invention, the
detecting step may intermittently detect the positions.
[0031] In the processing method according to the invention, the
recognizing step may recognize the dimension of the workpiece based
on the result of detection performed plural times by the first
detector and the second detector.
[0032] Other objects, features and advantages of the invention will
become sufficiently apparent from the following description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] FIG. 1 is a front view of a processing apparatus according
to an embodiment of the invention showing a general configuration
thereof.
[0034] FIG. 2 is a front view of a major part of the processing
apparatus according to the embodiment of the invention showing a
state thereof during an adjusting operation.
[0035] FIG. 3 is a front view of the major part of the processing
apparatus according to the embodiment of the invention showing a
state thereof during a processing operation.
[0036] FIG. 4 is a block diagram showing a circuit configuration of
the processing apparatus according to the embodiment of the
invention.
[0037] FIG. 5 is a flow chart of steps of the processing operation
utilizing the processing apparatus according to the embodiment of
the invention.
[0038] FIG. 6 is a distribution diagram showing an example of
distribution of the thicknesses of a plurality of workpieces before
a process using the processing apparatus according to the
embodiment of the invention.
[0039] FIG. 7 is a distribution diagram showing an example of
distribution of the thicknesses of the plurality of workpieces
after the process using the processing apparatus according to the
embodiment of the invention.
[0040] FIG. 8 is an illustration showing a comparison between the
thicknesses of the plurality of workpieces before and after the
process using the processing apparatus according to the embodiment
of the invention.
[0041] FIG. 9 is a flow chart showing an example of steps of a
polishing process operation utilizing a polishing process apparatus
according to the related art.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0042] An embodiment of the invention will now be described in
detail with reference to the drawings.
[0043] FIG. 1 is a front view of a processing apparatus according
to an embodiment of the invention showing a general configuration
thereof. Each of FIGS. 2 and 3 is a front view of a major part of
the processing apparatus according to the embodiment of the
invention. FIG. 2 shows a state during an adjusting operation, and
FIG. 3 shows a state during a processing operation.
[0044] The processing apparatus according to the present embodiment
has an apparatus main body 1 for performing a polishing process on
workpieces and a control panel 2 for inputting information on the
workpieces and processing conditions and showing various
indications. The polishing process includes grinding, lapping and
polishing. The apparatus main body 1 has three surface plates 3,
two vertical shafts 4 provided on each of the surface plates 3 and
an arm 5 provided on each of the shafts 4. The arms 5 are coupled
to the vertical shafts 4 such that they can move in vertical and
horizontal (forward and backward) directions.
[0045] Spline shafts 6 are attached to the arms 5 such that they
can move in the vertical direction. Keepers 7 for holding
workpieces are attached to the lower ends of the spline shafts 6.
Weights 8 are attached to the spline shafts 6 in the vicinity of
the upper ends thereof.
[0046] Reference position sensors 11 as the first detector which
detects reference positions and workpiece dimension sensors 12 as
the second detector which detects positions associated with
dimensions of the workpieces which change as a result of a process
are attached to the arms 5. In the present embodiment, the
dimensions of the workpieces which change as a result of a process
are the thicknesses of the workpieces. The reference position
sensors 11 are provided in positions outside the periphery of the
surface plates 3. The workpiece dimension sensors 12 are provided
in positions above the keepers 7. Reference bases 13 in the form of
blocks for indicating reference positions are provided under the
reference position sensors 11. The reference position sensors 11
detect the positions of the top surfaces of the reference bases 13.
The workpiece dimension sensors 12 detect positions of the top
surface of the keeper 7 as the positions associated with the
dimensions of the workpieces which change as a result of a
process.
[0047] The reference position sensors 11 and workpiece dimension
sensors 12 may be contact type sensors or non-contact type sensors.
The "TESA Module" manufactured by TESA Corp. or the like may be
used as the contact type sensor. The "Microsense" manufactured by
ADE Corp. may be used as the non-contact type sensor. Sensors
having good temperature characteristics are preferably used as the
sensors 11 and 12 because there may be temperature changes in the
vicinity of the sensors 11 and 12 during processing. For example,
such sensors with good temperature characteristics include glass
scale type sensors (e.g., sensors manufactured by Union Tool
Corp.).
[0048] FIG. 4 is a block diagram showing a circuit configuration of
the processing apparatus according to the present embodiment. FIG.
4 shows only parts associated with one of the arms 5. As shown in
FIG. 4, the processing apparatus has a driving portion 15 for
driving the surface plate 3 and arm 5, and a control portion 16 for
controlling the driving portion 15. The control panel 2, the
reference position sensor 11 and the workpiece dimension sensor 12
are connected to the control portion 16. The control portion 16
controls the driving portion 15 according to information on the
workpiece, processing conditions, etc. input from the control panel
2 and controls the driving portion 15 such that a dimension of the
workpiece becomes a predetermined value by recognizing the
dimension of the workpiece based on a reference position detected
by the reference portion sensor 11 and a position detected by the
workpiece dimension sensor 12. The control portion 16 also causes
the control panel 2 to display information of the dimension of the
workwpiece and so on thus recognized. For example, the control
portion 16 is constituted by a computer. The control portion 16
corresponds to the controller of the present invention.
[0049] A description will now be made on an operation of the
processing apparatus according to the embodiment and a processing
method according to the present embodiment. The processing
apparatus according to the present embodiment performs an adjusting
operation as described below before it processes a workpiece. As
shown in FIG. 2, in the adjusting operation, the keeper 7 having a
known reference thickness is attached to the lower end of the
spline shaft 6, and the keeper 7 is put in contact with the top
surface of the surface plate 3. Next, the reference position sensor
11 detects the position of the top surface of the reference base 13
as a reference position, and the workpiece dimension sensor 12
detects the position of the top surface of the keeper 7. The
control portion 16 recognizes and memorizes the relative positional
relationship between the reference position and the position of the
top surface of the keeper 7 based on the information of the
positions detected by the sensors 11 and 12. The surface plate 3
may be kept stationary or rotated when the adjusting operation is
performed. However, it is preferable to rotate the plate 3 for the
reason described later. The adjustment is not required to be
carried out prior to each processing operation and may be carried
out at an appropriate frequency.
[0050] For processing the workpiece, as shown in FIG. 3, the
workpiece 20 held by the keeper 7 is put in contact with the
surface plate 3, and the surface plate 3 is rotated to polish the
workpiece 20. During the processing operation, the reference
position sensor 11 detects the reference position, and the
workpiece position sensor 12 detects the position of the top
surface of the keeper 7. The control portion 16 recognizes the
relative positional relationship between the reference position and
the position of the top surface of the keeper 7 based on the
information of the positions detected by the sensors 11 and 12.
This positional relationship is compared with the positional
relationship that has been recognized and memorized at the
adjusting operation. The absolute dimension (thickness) of the
workpiece 20 is thereby recognized.
[0051] Steps of the processing operation will now be described with
reference to the flow chart in FIG. 5 and to FIG. 3. During the
processing operation, the workpiece 20 is first secured to the
keeper 7 by means of thermal adhesion, vacuum absorption or the
like (step S101). The thickness of the keeper 7 used here is the
same as that of the keeper 7 used at the adjustment and is
therefore known. The keeper 7 is then secured to the processing
apparatus as shown in FIG. 3 (step S102). Then, information on the
workpieces such as the length and the number of the workpieces 20
and processing conditions are input using the control panel 2. The
input of processing conditions includes setting of a desired
dimension of the workpiece 20 after the process. Next, a workpiece
processing operation and a dimension recognizing operation are
carried out (step S103). For the processing operation, the
workpiece 20 held by the keeper 7 is put into contact with the
surface plate 3, and the surface plate 3 is rotated to polish the
workpiece 20. During the processing operation, the control portion
16 controls the driving portion 15 according to the input
information and conditions and recognizes the dimension (thickness)
of the workpiece 20 based on the reference position detected by the
reference position sensor 11 and the position detected by the
workpiece dimension sensor 12. Next, the control portion 16
determines whether the dimension of the workpiece 20 has reached
the set dimension or not to determine whether to terminate the
process or not (step S104). If the process is not to be terminated
(N), the step S103 is continued. If the dimension of the workpiece
20 has reached the set dimension and the process is to be
terminated (step S104; Y), the process by the processing apparatus
is terminated. Finally, the dimension of the workpiece is measured
and evaluated (step S105) to terminate the processing
operation.
[0052] When the sensors 11 and 12 are non-contact type sensors, the
position detection with the sensors 11 and 12 during the processing
operation may be performed continuously or intermittently. When the
sensors 11 and 12 are contact type sensors, the position detection
with the sensors 11 and 12 during the processing operation is
preferably performed intermittently to suppress the wear of the
sensors 11 and 12. When the position detection with the sensors 11
and 12 is performed intermittently, as shown in FIG. 3, the arm 5
is moved up and down to put the sensors 11 and 12 in contact with
the reference base 13 and keeper 7 only when the position detection
is carried out.
[0053] When the position detection with the sensors 11 and 12 is
performed intermittently, the cycle of detection may be shortened
stepwise as the dimension of the workpiece approaches the set
value.
[0054] When the dimension of the workpiece is measured based on the
values detected by the sensors 11 and 12, the position detection
with the sensors 11 and 12 may be performed plural times for each
measurement to identify the dimension of the workpiece by carrying
out a calculation using a statistic technique at the control
portion 16 based on a plurality of detection values. This makes it
possible to recognize the absolute dimension of the workpiece 20
with improved accuracy.
[0055] For example, during the rotation of the surface plate 3,
swell of the surface plate 3 and keeper 7 may cause swell in the
position of the top surface of the keeper 7. In order to prevent
the dimension of the workpiece 20 recognized based on the values
detected by the sensors 11 and 12 from changing as a result of the
swell, the dimension of the workpiece 20 may be recognized as
follows. First, the adjusting operation is performed with the
surface plate 3 rotated. At this time, signals indicating rotating
positions of the surface plate 3 are generated, and the timing of
detection with the sensors 11 and 12 is determined based on the
signal to perform the position detection with the sensors 11 and 12
at a plurality of rotating positions of the surface plate 3. Thus,
the absolute position of the top surface of the keeper 7 including
swell or the relationship between the rotating positions of the
surface plates 3 and the absolute position of the top surface of
the keeper 7 is recognized. For example, the relationship is
expressed by a sine curve where the rotating positions of the
surface plate 3 are plotted along the abscissa axis and the
absolute position of the top surface of the keeper 7 is plotted
along the ordinate axis. During the processing operation, the
absolute position of the top surface of the keeper 7 including
swell or the relationship between the rotating position of the
surface plate 3 and the absolute position of the top surface of the
keeper 7 is similarly recognized by performing the position
detection with the sensors 11 and 12 in a plurality of rotating
positions of the surface plate 3. For example, the relationship is
also expressed by a sine curve. Then, the relationship recognized
during the adjusting operation is compared with the relationship
recognized during the processing operation, which makes it possible
to accurately recognize the absolute dimension of the workpiece 20
from which any swell component has been removed. When the
relationship recognized during the adjusting operation and the
relationship recognized during the processing operation are
compared, corresponding parts between the relationships may be
accurately identified and compared with each other by correlating
the two relationships (e.g., two sine curves) or by using other
means.
[0056] Workpieces 20 to be processed by the processing apparatus
according to the present embodiment include, for example, a
material for a thin film magnetic head. The material will now be
briefly described.
[0057] In general, a flying type thin film magnetic head used in a
magnetic disk drive or the like is constituted by a slider formed
with a thin film magnetic head element at the rear end thereof. In
general, a slider has a rail portion whose surface serves as a
medium facing surface (air bearing surface) and a taper portion or
step portion in the vicinity of the end on an air inflow side
thereof. The rail portion is slightly floated above the surface of
a recording medium such as a magnetic disk by a stream of air that
flows in through the taper portion or step portion.
[0058] In general, sliders are manufactured by cutting a wafer in
one direction, the wafer having a plurality of rows of sections to
become sliders (hereinafter referred to as slider sections) each
including a thin film magnetic head element. Materials referred to
as "bars" on which the slider sections are arranged in a row are
thereby formed, and the bars are cut into sliders. A surface of a
bar which is to become a medium facing surface (hereinafter
referred to as "medium facing surface" for convenience) is
subjected to processes such as lapping and formation of a rail
portion. Such processes may be performed before or after the
formation of the bar.
[0059] In the process of manufacturing a slider as described above,
the final thickness of the slider or the profile of the medium
facing surface may be controlled by lapping the surface of the bar
opposite to the medium facing surface before or after the
processing of the medium facing surface of the bar, or by lapping
two surfaces of a block in which two rows of the slider sections
are arranged with the medium facing surfaces thereof facing each
other, the two surfaces of the block being opposite to the medium
facing surfaces respectively. The processing apparatus according to
the present embodiment may be used for lapping the surface of such
a bar or block opposite to the medium facing surface.
[0060] As described above, with the processing apparatus or method
according to the present embodiment, an absolute dimension of a
workpiece is recognized, and a process is automatically performed
such that the dimension of the workpiece becomes a predetermined
value. This makes it possible to automatically process the
workpiece such that it will have a desired dimension and to process
the workpiece with high accuracy without any need for a special
pre-process for allowing the acquisition of a signal from the
workpiece.
[0061] In the present embodiment, there is provided the reference
position sensor 11 for detecting a reference position and the
workpiece dimension sensor 12 for detecting a position associated
with a dimension of a workpiece that changes as a result of a
process. The absolute dimension of the workpiece is recognized
based on information detected by both of the sensors 11 and 12.
Therefore, the present embodiment makes it possible to easily
recognize the absolute dimension of the workpiece by comparing the
information detected by the sensors 11 and 12 without any
unnecessary improvement of the accuracy of a machine control
system, which consequently makes it possible to improve processing
accuracy.
[0062] As shown in FIG. 9, when processing time is controlled to
provide a workpiece with a desired dimension, operating efficiency
is low because a processing step and a measurement/evaluation step
are repeated two or more times. On the contrary, according to the
present embodiment, the efficiency of a processing operation can be
improved because accurate recognition of the absolute dimension of
a workpiece makes it possible to provide the workpiece with a
desired dimension at one processing step. For example, the present
embodiment makes it possible to improve the efficiency of a
processing operation by 1.5 times or more (in other words, to
reduce the time of the processing operation to {fraction (2/3 )} or
less) when compared to the case in which the processing time is
controlled.
[0063] According to the present embodiment, since there is no need
for measuring and setting dimensions of a workpiece prior to a
process, there is no possibility of occurrence of measuring and
setting errors by an operator. Further, since the present
embodiment eliminates the need for a measurement and evaluation
step in the middle of a process, it is possible to prevent any
reduction of quality attributable to electrostatic discharge (ESD),
corrosion, etc.
[0064] According to the present embodiment, the two sensors 11 and
12 can be kept in a constant positional relationship whether the
surface plate 3 is stopped or rotated because the two sensors 11
and 12 are attached to the same arm 5. This allows a further
improvement of the accuracy of recognition of the absolute
dimension of a workpiece and makes it possible to improve
processing accuracy further.
[0065] A description will now be made with reference to FIGS. 6
through 8 on a difference in distribution of thicknesses of
workpieces before and after a process using the processing
apparatus according to the present embodiment. FIG. 6 shows an
example of distribution of the thicknesses of a plurality of
workpieces before a process using the processing apparatus
according to the present embodiment. FIG. 7 shows distribution of
the thicknesses of the same plurality of workpieces after the
process using the processing apparatus according to the embodiment.
In FIGS. 6 and 7, the ordinate axis represents the thickesses of
the workpieces, and the abscissa axis represents the number of
workpieces. In the case of a process performed according to a
conventional method in which processing time is controlled, the
distribution of the thicknesses of the workpieces after the process
is similar to that shown in FIG. 6.
[0066] FIG. 8 is an illustration showing a comparison between the
thicknesses of the plurality of workpieces before and after the
process using the processing apparatus according to the embodiment.
In FIG. 8, the ordinate axis represents the thickesses of the
workpieces, and the abscissa axis represents each of the
workpieces. In FIG. 8, the dots in the upper part represent
thicknesses before the process, and the dots in the lower part
represent thicknesses after the process. It is apparent from FIGS.
6 through 8 that the processing apparatus according to the present
embodiment can accurately process a workpiece such that a dimension
of the workpiece becomes a desired value. According to the present
embodiment, dimensional variations can be reduced to about one half
of that in the case wherein processing time is controlled such that
a workpiece will have a desired dimension.
[0067] The present invention is not limited to the above described
embodiment and may be modified in various ways. For example, each
of the first detector and second detector may have a plurality of
sensors so as to detect the position from an average of values
detected by the plurality of sensors.
[0068] The present invention is not limited to materials for a thin
film magnetic head and may be used for processing various kinds of
workpieces.
[0069] As described above, in the processing apparatus or method
according to the invention, a reference position is detected by the
first detector; a position associated with a dimension of a
workpiece is detected by the second detector; and the dimension of
the workpiece is recognized based on the positions detected by the
two detectors to control the processing machine such that the
dimension of the workpiece becomes a predetermined value. This
makes it possible to automatically process a workpiece such that it
will have a desired dimension and to improve processing accuracy
and efficiency without any need for a special pre-process.
[0070] In the processing apparatus or method according to the
invention, when the first detector and second detector are attached
to the same arm, the first detector and second detector can be kept
in a constant positional relationship. This allows an improvement
of the accuracy of recognition of a dimension of a workpiece and
makes it possible to improve processing accuracy further.
[0071] In the processing apparatus or method according to the
invention, when a dimension of a workpiece is recognized based on
the result of detection with the first detector and second detector
performed plural times, it is possible to recognize the dimension
of the workpiece with improved accuracy.
[0072] It is apparent from the above description that the present
invention may be carried out in various modes and modifications.
Therefore, the present invention may be carried out in modes other
than the above-described best mode for carrying out the invention
within the range of equivalence of the appended claims.
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