JPH05318284A - Method and device for positioning rotary table for machining - Google Patents

Abstract

PURPOSE:To make wide range adjustment of the position of a rotary table precisely at a high speed, in which splashing oil or the like is prevented from intrusion into the device. CONSTITUTION:A locating method and a device associate therewith are to position a rotary table 1 on which a work to be machired 4 is placed relative to a traveling table 2, wherein a pattern to serve for locating is provided on the rotary table 1 and image formed on an image formation surface using an optical means, and the formed image is subjected to specified processing. From the result, the moving amount is calculated, and the rotary table 1 is fed till a specified position at coarse spacings, followed by fine feed at narrower spacings. Thus adjustment of the rotational position is generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a machining rotary table positioning device for positioning a rotary table on which a work is placed and set.

[0002]

2. Description of the Related Art In a video head grinding process, a video head is set on a rotary table which is rotationally adjustable on a moving table, and the video head is positioned at an alignment adjusting position with respect to the moving table. In this state, the movable table and the rotary table are moved to a processing position to perform a predetermined grinding process.

Here, in the grinding of the track processing of the video head, a processing tolerance of about ± 1 μm is required, but in order to achieve high density recording of a digital video head or the like, about ± 0.3 to 0.5 μm. Is required. That is,
For example, if the accuracy of the rotary table is ± 0.1 μm and the length of the work (video head) is 40 mm, the tilt angle θ of the work is about 1.1 seconds. Therefore, the position adjustment of the rotary table at the alignment adjustment position has a great influence on the processing accuracy.

Therefore, conventionally, various methods have been proposed in which the position of a rotary table on which a work is placed is detected and the rotary table is rotated with respect to a movable table to perform alignment adjustment. As a drive source for rotating the rotary table, a DC motor, a piezoelectric element (piezo element),
Also, there are those using a combination of a pulse motor and a speed reducer, etc., but conventionally, control is performed with the same drive source and at the same speed.

[0005]

However, when a direct current motor is used as a drive source, there is a problem that the resolution is low and it is not suitable for high precision positioning. Also,
When only the piezoelectric element is used, there is a problem that the movable range is extremely small and the adjustment is possible only in the angular range of about 0.3 seconds. Further, in the case where the pulse motor and the speed reducer are used in combination, there is a problem that the resolution is reduced about 100 times as compared with the piezoelectric element.

Therefore, there has been a long-felt need for a positioning method and apparatus capable of accurately performing position adjustment over a wide range and at high speed.

Further, this type of apparatus is often used in a space where cooling oil or the like scatters during grinding. For this reason, it is also required to have a structure in which the scattered oil or the like does not enter the inside of the apparatus and adversely affects the circuit components and the like.

The present invention has been made in view of the above problems, and an object thereof is to make it possible to accurately adjust the position of a rotary table over a wide range and at high speed, and to scatter oil or the like inside the apparatus. It is an object of the present invention to provide a positioning method and a device for a processing table that does not intrude into the work.

[0009]

In order to achieve the above object, the present invention is to position a rotary table on which a work is placed with respect to a movable table, and to provide a positioning pattern on the rotary table. , This pattern is imaged on the image plane by optical means, and image processing is performed.
From this, the amount of movement is calculated, and the rotary table is coarsely fed to the specific position at large intervals, and then finely moved at intervals smaller than the coarse motion to adjust the rotational position. Further, the positioning pattern is provided on the work, and the rotary position is adjusted after the work is set on the rotary table, thereby further improving the positioning accuracy. Furthermore, if the fine movement feed is performed by driving a piezoelectric element and the rotational position of the rotary table is detected by a position detection sensor to perform position control in real time, position correction during machining is also possible and high precision is achieved. Can be processed. In addition, when the optical means is provided with an automatic focus adjusting means, it is possible to automatically focus the image forming surface of the optical means, and it is possible to completely automate the rotational positioning work. A means for forming the upper surface of the movable table facing the rotary table as an inclined surface that decreases as it goes outward, and for ejecting air from the inside to the outside in the gap between the rotary table and the movable table, Providing a waterproof wall formed by hanging the outer peripheral portion of the rotary table along the side surface of the moving table until the tip is located below the upper surface of the moving table; and providing drain grooves on the upper surface of the moving table. Thus, the waterproof means in the non-contact state is formed, and it is possible to reliably prevent the splashed oil or the like from entering through the gap between the rotary table and the movable table at these portions.

[0010]

According to this structure, the rotary table is coarsely fed to a specific position at large intervals to perform a rough rotational position adjustment, and then finely moved at intervals smaller than the coarse motion to raise the height. Since the rotational position is adjusted accurately, the position of the rotary table can be adjusted over a wide range and at high speed with high accuracy. In addition, since the position is detected by pattern recognition, it is possible to support multiple models by changing the pattern recognition software. Furthermore, since the non-contact waterproofing means is provided between the rotary table and the moving table, it is possible to prevent oil or water that has been scattered and formed into a granular or mist state from entering the inside of the apparatus. Moreover, since the waterproofing is performed without contact, it is possible to perform waterproofing without stick-slip caused by abrasion of the seal portion.

[0011]

Embodiments of the present invention will be described in detail below with reference to the drawings. 1 to 3 show a main part of a positioning device for a rotary table for processing as an embodiment of the present invention. FIG. 1 is a schematic sectional view seen from the front side, and FIG. 2 is seen from the side direction. FIG. 3 is a schematic sectional view showing the same, and FIG. 3 is an enlarged view of a portion A in FIG. 1 to 3, a rotary table 1 for machining is provided with a cross roller bearing 3 and a bearing 19 (see FIG. 2) on a movable table 2 which is movable on an X axis connecting an alignment adjusting position and a machining position described later. It is rotatably attached via.

More specifically, the rotary table 1 has a mounting surface 5 on which the work 4 (see FIG. 1) is mounted and positioned and set, and on the back side of the mounting surface 5, the mounting surface 5 is mounted. A cylindrical portion 6 having an outer diameter smaller than that of the mounting surface 5 and formed concentrically with the mounting surface 5 is integrally provided with the lower surface opened. Further, the mounting surface 5 is provided with a vacuum hole (not shown) for an air chuck, which is connected via an air pipe 7 to a vacuum pump (not shown). And, in this turntable 1, the mounting surface 5
When the workpiece 4 is placed on the workpiece via the jig 51 and the vacuum pump is further driven, the workpiece 4 can be vacuum-sucked and chucked on the mounting surface 5 via the jig 51, and when the vacuum pump is stopped. The structure is such that the chuck can be released.

The work 4 shown by the alternate long and short dash line in FIG.
Indicates a state in which the workpiece is chucked on the mounting surface 5 in this way and is ground by the grinding wheel 8 at the grinding position. In this state, component forces in the three directions of symbols F _X , F _Y and F _Z are transmitted to the rotary table 1 side via the work 4, and the grinding resistances F _X , F _Y and F _Z fluctuate intricately during machining. However, due to this fluctuation, a moment acts to move the rotary table 1 in the rotational direction.

Here, a mark as a positioning pattern is provided on the upper surface of the work 4 described above.
In this pattern, for example, as shown in FIG. 4, eight marks 9 are divided into two groups (9A, 9B) on the left and right, or as shown in FIG. 9A and 9B), or one strip-shaped mark 10 is formed as shown in FIG. 6, and both patterns are formed in the feed direction 11 (FIG. 4) of the grinding wheel 8. That is, the movable table 2 is provided so as to be parallel to the moving X axis.

On the other hand, the moving table 2 is formed as a cylinder whose upper surface is opened. Further, the cylindrical portion 6 of the rotary table 1 is inserted through the opening of the upper surface 12, and the upper surface 1
2 and the lower surface 5a on the rotary table 1 side with a slight gap provided, the cross roller ring 3 and the bearing 1
The peripheral surface and the lower surface of the rotary table 1 are rotatably held via the shaft 9. Further, a labyrinth seal 14 is provided between the inner surface of the moving table 2 and the outer peripheral surface of the tubular portion 6 of the rotary table 1 and above the cross roller ring 13. It is arranged to prevent oil and water from further entering through a slight gap existing between the upper surface 12 and the lower surface 5a of the turntable 1.

In addition, on the upper surface 12 side, as shown in an enlarged view in FIG. 3, waterproof means composed of an inclined surface 12a,
A waterproof means composed of the drain groove 15 and a waterproof means composed of the air blowing portion 16 are provided, and these non-contact type waterproof means are provided between the upper surface 12 of the moving table 2 and the lower surface 5a of the rotary table 1. The oil and water are prevented from further entering through the gap.

That is, the waterproofing means by the inclined surface 12a is formed as an inclined surface which decreases as it goes from the inner side to the outer side, so that oil or the like scattered on the inclined surface 12a is discharged to the outside along the inclination. You can

The drain groove 15 is formed so as to circulate around the upper surface 12, and oil or the like that has penetrated along the inclined surface 12a is dropped into the drain groove 15 and further the drain hole 1
It can be discharged to the outside through 5a.

The waterproofing means consisting of the air blowing portion 16 has an air blowing pipe 16a having one end opened in the middle of the inclined surface 12a and the other end communicating with an air compressor (not shown). Then, the air supplied from the air compressor is
Upper surface 12 of moving table 2 and lower surface 5a of rotary table 1
The air is blown out into the gap between and, and the air is blown outward from the inside of the gap, and the blowout of the air 17 forcibly pushes out splashes of oil or the like that try to enter the gap. Is ready for

In addition to these waterproofing means, the rotary table 1 is placed between the moving table 2 and the rotary table 1.
As a waterproofing means formed by circling the outer peripheral portion of the movable table 2 along the side surface of the movable table 2 so that its tip is located below the upper surface 12 of the movable table 2 to cover the front surface of the gap. The waterproof wall 18 is provided.
In this waterproofing means, the front surface of the gap is covered with the waterproof wall 18, whereby the passage to the gap is bent, and splashing of oil or the like makes it difficult for the splashes of oil or the like to enter the gap, thereby achieving waterproofing.

Therefore, between the movable table 2 and the rotary table 1, the gap between the upper surface 12 of the movable table 2 and the lower surface 5a of the rotary table 1 is formed to be a minimum and a waterproof means. In addition to the above, the waterproof means by the waterproof wall 18, the waterproof means by the air blowing portion 16, the waterproof means by the inclined surface 12a, and the drain groove 15 are provided.
The sealing means and the labyrinth seal 14 seal the non-contact type waterproofing means except for the sealing by the labyrinth seal 14, and the waterproofing means prevents oil or oil from entering the seal moving table 2. Water can be reliably sealed. That is, waterproofing is performed without contact, so that waterproofing can be performed without stick-slip due to wear of the seal portion.

A rotary drive unit 20 (see FIG. 8) is provided in the movable table 2 thus sealed. The rotary drive unit 20 includes a coarse feed system 21 (see FIG. 8) that can coarsely feed the rotary table 1 at large intervals.
And a fine movement feed system 22 (see FIGS. 1, 2, 7, and 8) capable of fine movement feed at a smaller interval than the coarse movement feed system 21.

Although not shown, the coarse feed system 21 is formed of a stepping motor and a ball screw or the like interposed between the stepping motor and the stepping motor. The rotary table 1 is structured so that it can be roughly positioned over a wide range and rapidly.

On the other hand, the fine movement feed system 22 is shown in FIG.
2, and as shown in the schematic configuration in FIG. 7, a piezoelectric element (PZT) 23 fixedly attached to the movable table 2 side through a holder 25 is provided as a drive source. The two are connected via a ball joint 24. The piezoelectric element 23 is provided with a piezoelectric element driver 26 (see FIG. 7) after the rotary table 1 is roughly positioned by the coarse feed system 21.
Driven by, and performs highly accurate positioning with respect to the coarse feed system 21 with a resolution of about 1/100.

Further, in the fine movement feed system 22, when the position of the rotary table 1 is moved by the vibration during grinding or the like during the positioning of the rotary table 1 and after the positioning is completed, the piezoelectric element 23 is expanded and contracted. A position detection sensor 27 that can detect and know Then, the current position signal 28 of the rotary table 1 is constantly taken out from the position detection sensor 27 and the central processing unit (CP
U) 29, the central processing unit 29 judges whether or not the position of the rotary table 1 can be adjusted based on the current position signal 28, and when the adjustment is necessary, the feedback command value 36 is given to the piezoelectric element driver 26 to make the piezoelectric element The piezoelectric element 23 is driven via the driver 26 so that the rotary table 1 can be always held at a predetermined position even during processing. The position detection sensor 27 employs a semi-closed system for measuring expansion and contraction of the piezoelectric element 23, but a rotary encoder is provided on the rotary table 1 to provide a full-closed loop system, or a force is measured using a strain gauge. However, it is safe to give feedback.

FIG. 8 shows a state in which the positioning device for the rotary table for processing is arranged at the alignment adjustment position and the alignment of the rotary table 1 is being adjusted. At this alignment adjustment position, the microscope unit 30 and the CCD (solid-state image pickup device) arranged on the image plane of the microscope unit 30 are provided above the placement surface 5 on which the workpiece 4 is air chucked via the jig 51. ) 31 and the like is provided so that it can be connected to the positioning device main body side of the processing rotary table. In addition, the microscope unit 30
Has a built-in automatic focus adjustment means, which is controlled by an automatic focus adjustment circuit (AF circuit) 33.

That is, the microscope unit 30 automatically adjusts the focus position to the upper surface of the work 4 placed on the mounting surface 5 on which the above-mentioned pattern is formed, and forms an image on the CCD 31. The taken-out signal is taken into the central processing unit 29 to perform image processing, and the central processing unit 2
9, the AF circuit 33, the coarse feed system 21, and the fine feed system 22 are controlled based on the processing result. Although the present embodiment discloses the structure in which the central processing unit 29 is used in the positioning device of the processing rotary table, the central processing unit 29 may be provided separately.

FIG. 9 is a flowchart showing the alignment adjustment procedure at the alignment adjustment position. Therefore,
The positioning operation of the machining rotary table at the alignment adjustment position will be described below with this flowchart.

First, as shown in FIG. 8, the work 4 is fixed and set on the jig 51 attached to the mounting surface 5 by an air chuck. In this case, it is assumed that the work 4 has a pattern formed by the marks 9 shown in FIG. 4 on its upper surface, and this pattern is the feed direction 1 of the grinding wheel 8.
1 (see FIG. 4), that is, the work 4 is set on the jig 51 so as to be substantially parallel to the moving direction (X axis) of the moving table 2. Then, in the pattern on the work 4, the first mark group 9A has the first measurement point 3
4, the second mark group 9B has the second measurement point 3
5 are arranged respectively.

Next, the movable table 2 is manually moved on the X axis to bring the first measurement point 34 of the pattern into the visual field of the microscope unit 30 (step 101).

Then, preparation for alignment adjustment is completed, and alignment adjustment is started (step 1
02).

When the alignment adjustment is started, first the autofocus operation of the microscope unit 30 is started (step 103). Subsequently, the first mark group (marker 1) 9A at the first measurement point 34 imaged on the CCD 31 is read out and image-processed,
It is temporarily stored in a memory or the like (not shown) (step 10
4).

Next, the autofocus is returned to the start position (step 105), the moving table 2 is moved on the X axis, and the second measurement point 35 of the pattern is brought into the visual field of the microscope unit 30 (step 106).

Then, the autofocus operation of the microscope unit 30 is started again (step 107), and then the first mark group (marker 2) 9B at the second measurement point 35 imaged on the CCD 31 is read out. Image processing is performed (step 108).

The information read out in step 108 is processed together with the information stored in step 104 to obtain the pattern inclination angle θ (see FIG. 4), and the rotary table 1 is rotated. The quantity is calculated (step 109).

Next, the autofocus is returned to the start position (step 110), and the rotational position adjustment of the rotary table 1 is started (step 112).

In this rotational position adjustment, the coarse movement feed system 21 using the stepping motor as a drive source is first controlled based on the rotation amount obtained in step 109, and the coarse movement feed system 21 is controlled.
In the state where the processing accuracy is about ± 1 μm, that is, the rotation is adjusted to a specific position. Then, while controlling the fine movement feed system 22 using the piezoelectric element 23 as a drive source and performing the confirmation operation in the middle (step 113), the fine movement feed system 22 is rotated until a machining accuracy of about ± 0.1 μm is obtained. The alignment is adjusted and locked by means not shown, and the alignment at the alignment adjustment position is completed (step 114).

In this way, the machining table positioning device, which has been rotationally positioned, moves on the X-axis while being held in this locked state and is conveyed to the grinding position, where the workpiece 4 is ground. Processing is done. The work 4 shown in FIG. 1 is in a state where it is carried to the processing position in this way and is ground by the grinding wheel 8. And
During this grinding process, component forces in the three directions of F _X , F _Y and F _Z in FIG. 1 are transmitted to the rotary table 1 side via the work 4.
When the grinding resistances F _X , F _Y , and F _Z fluctuate in a complicated manner, and this fluctuation moves the rotary table 1 in the rotational direction, this is detected by the position detection sensor 27, and the central processing unit 29 using the high-speed CPU 29. , Is corrected by the control of the piezoelectric element 23 via the piezoelectric element driver 26. As a result, positioning during processing is guaranteed, and accurate processing becomes possible.

Therefore, in this positioning method, for example, the rotary table is coarsely fed at large intervals up to a position where a machining accuracy of about ± 1 μm is obtained, that is, to a "specific position" to roughly adjust the rotary position. Then, fine-motion feed is performed at intervals smaller than the coarse-motion feed, and
Since the highly accurate rotational position adjustment is performed so that about 0.1 μm is obtained, the position of the rotary table can be accurately adjusted over a wide range and at a high speed. The “specific position” may be within the range where the final adjustment of the rotational position is possible with the piezoelectric element 23. Further, since the positioning pattern (marks 9 and 10) is provided on the work 4 and the rotation position is adjusted after the work 4 is set on the rotary table 1, the positioning accuracy is further improved. At the same time, since position detection is performed by pattern recognition, different workpieces can be easily handled by changing pattern recognition software. Furthermore, since the fine movement feed system 22 is driven by the piezoelectric element 23 and the rotational position of the rotary table 1 is detected by the position detection sensor 27, position control is performed in real time.
The accuracy at the time of processing can be guaranteed, and more accurate processing becomes possible. In addition, since an automatic focus adjustment function is provided as the optical unit 32, it is possible to automatically focus on the CCD 31 arranged in the portion that becomes the image forming surface of the microscope unit 30, and perform rotational positioning. Full automation of work is also possible.

In the above embodiment, the case where the invention is applied to an apparatus for performing a grinding process has been described, but it can be similarly used when the work 4 is set by a processing apparatus other than this.

[0041]

As described above, according to the present invention, the rotary table is coarsely fed to a specific position at a large interval to perform a rough rotational position adjustment, and subsequently, an interval smaller than the coarse feed is performed. Since the fine adjustment is performed to precisely adjust the rotational position, it is expected that the position of the rotary table can be accurately adjusted over a wide range and at high speed. In addition, since the position is detected by pattern recognition, it is possible to support multiple models by changing the pattern recognition software. Further, since a non-contact waterproofing means is provided between the rotary table and the moving table, splashed oil, water, etc. can be reliably prevented from entering the inside of the device, and the circuit parts, etc. can be protected. .. Moreover, since the waterproofing is performed without contact, it is possible to perform waterproofing without stick-slip caused by abrasion of the seal portion.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional front view showing a main part of a positioning device for a processing rotary table shown as an embodiment of the present invention.

FIG. 2 is a schematic vertical sectional side view showing a main part of the positioning device shown in FIG.

FIG. 3 is an enlarged view of part A of FIG.

FIG. 4 is a diagram showing an example of marks forming a pattern.

FIG. 5 is a diagram showing another example of marks forming a pattern.

FIG. 6 is a diagram showing still another example of marks forming a pattern.

FIG. 7 is a diagram for explaining the operation of the fine feed system.

FIG. 8 is a schematic configuration layout diagram at an alignment adjustment position.

FIG. 9 is a flowchart showing an alignment adjustment procedure at an alignment adjustment position.

[Explanation of symbols]

 1 rotary table 2 movable table 4 work 5 mounting surface 9 mark 10 mark 12 upper surface 12a inclined surface 15 drain groove 15a drain hole 16 air blowing part 18 waterproof wall 20 rotary drive part 21 coarse feed system 22 fine feed system 23 piezoelectric element 27 position detection sensor 29 central processing unit 32 optical means

Claims (11)

[Claims] 1. A positioning method of a rotary table for processing for positioning a rotary table on which a work is placed with respect to a movable table, wherein a positioning pattern is provided on the rotary table, and the pattern is formed by an optical means on an imaging plane. The image is processed and image-processed, the moving amount is calculated from this, the rotary table is coarsely fed to a specific position at large intervals, and then finely moved at intervals smaller than the coarse motion to adjust the rotational position. A method of positioning a rotary table for processing, characterized in that 2. The positioning of the rotary table for processing according to claim 1, wherein the positioning pattern is provided on the work, and the rotary position is adjusted after the work is set on the rotary table. Method. 3. The method of positioning a rotary table for processing according to claim 1, wherein a piezoelectric element is used as a drive source for the fine movement feed. 4. The method of positioning a rotary table for processing according to claim 3, further comprising a position detection sensor for detecting a rotational position of the rotary table, and performing position control in real time by the output of the position detection sensor. 5. A positioning device for a machining rotary table for positioning a rotary table on which a work is placed with respect to a movable table, wherein a positioning pattern is provided on the rotary table, and the rotary table is coarsely moved at large intervals. A rotation driving unit having a coarse movement feeding system for feeding, and a fine movement feeding system for finely feeding the rotary table at intervals smaller than the coarse movement feeding system; and an optical unit for forming an image of the pattern on an image forming surface. A central processing unit that performs image processing on the pattern formed on the image forming surface and calculates the amount of movement of the rotary table to control the rotary drive unit. For processing, the rotary feed unit is controlled by the processing unit so that the rotary feed operation is performed to a specific position and then the rotary feed operation in the fine movement feed system is sequentially performed. The rolling table of the positioning device. 6. The coarse movement feed system is formed by a stepping motor and a ball screw interposed between the rotary table and the stepping motor, and the fine movement feed system is formed by a piezoelectric element. Rotary table positioning device for machining. 7. The fine feed system is provided with a position detection sensor for inputting a signal corresponding to the position of the rotary table to the central processing unit, and means for performing position control in real time by the output of the detection sensor. The positioning device for the rotary table for processing according to claim 6. 8. The positioning device for a machining rotary table according to claim 5, wherein the optical means is provided with an automatic focus adjusting means. 9. A positioning device for a rotary table for processing, comprising a rotary table on which a work is placed, which is rotatably supported by a movable table via a bearing, wherein an upper surface of the movable table facing the rotary table moves outwardly. The processing rotary table is formed as a descending inclined surface, and means for ejecting air from the inside to the outside of the gap is provided in the gap between the rotary table and the moving table. Positioning device. 10. The processing according to claim 9, further comprising a waterproof wall formed by suspending an outer peripheral portion of the rotary table along a side surface of the moving table to a state in which a tip end is positioned lower than an upper surface of the moving table. Rotary table positioning device. 11. The positioning device for a rotary table for processing according to claim 9, wherein a drain groove having a drain hole is provided on an upper surface of the movable table facing the rotary table over substantially the entire circumference.