JPS63180463A - Polishing device - Google Patents

Abstract

PURPOSE:To prevent a work surface from being damaged, in a float polishing device for making non-contact polishing, by setting the rotational center of a work to coincide with that of a surface plate at the time of starting with a low rotational speed or at the time of stopping operation so that both the work and the surface plate can rotate at the same speed. CONSTITUTION:A work stand 5 is firstly set in the central position of a surface plate 2 so that both a machining head 3 including a work 12 attached thereto and a polishing surface plate 2 are rotated at the same speed and the rotational speed is increased. When the rotational speed exceeds a certain level, the work stand 5 is moved along a sliding stand 7 to an eccentric position so that a float polishing process may be carried out by means of polishing liquid 15 staying inside a machining bath 1. Then, when the operation is stopped after completion of polishing process, the work stand 5 is slidden from the polishing position to the central position slowly in about 30min and the rotational speed is reduced while both rotational speeds of the machining head 3 and polishing surface plate 2 being maintained at the same level in the central position. Thus, a polished surface with high accuracy can be obtained in this way, without any scratch on the surface of work even though the surface of the work may touch the surface plate.

Description

Detailed Description of the Invention ■Technical Field The present invention provides a float polishing device that performs non-contact polishing, in which the speed decreases when the surface plate starts and ends rotating.
This prevents the workpiece from coming into contact with the surface plate and damaging the workpiece surface when dynamic pressure is insufficient.

b) Float polishing method The float polishing method was first proposed by Yoshiharu Namba et al.

Namba, Y, and Tsuvra, Ho,
Ultra-Fine Finishing of'
5apphire Single Crystal.

Annals of the CIRP, 26/1.
825 (1977) and Namba, Y. and Tsuwa, H7, M.
echanism andSome Applicat
ions of' Ultra-Fine Finis
hing 1lAnnals of CIRP, 27
1.511 (1978) and others.

A method of completely polishing Mn-Zn ferrite, Ni-Zn ferrite, etc. using a float polishing method has been proposed by Namba et al.

JP-A No. 55-44787 (S, published on August 29, 1987)
It is.

As the abrasive grains, MgO particles with a particle size of 0.1 μm or less are proposed. Oxides Al2O3,5in2, Cr2O3, ZnO1Fe that are considered to have potential as abrasive grains
203, Fe3041, etc. were all deemed unsuitable.

Al2O3, 5i02, Cr2O3 are too hard abrasive grains
b means that the surface roughness becomes too large.

If Fe2O3 or Fe3O4 is used as the abrasive grain, a mirror polished surface cannot be obtained.

The polishing speed of CaCO3 and ZnO is too slow. For this reason, it has been concluded that it is better to use MgOf: abrasive grains. They also suggest adding glycerin to the polishing solution to increase its viscosity.

Polishing surface plate is suitable for tin, aluminum, brass, etc.
It is said that it will be made. In addition, it is necessary to increase the fluid pressure noise, and increasing the fluid speed will cause surface wobbling and reduce machining accuracy, so it is proposed that a helical groove be carved on the polishing surface plate.

This invention is US Pat. No. 4,858,295 (November 9, 1982).

Namba proposed a float polishing method in which hydrochloric acid and Fe2O3 are mixed with pure water to create a polishing liquid. Japanese Patent Publication No. 55-8
No. 8561 (S, published 55.6.24). Again, the entire Mn--Zn ferrite is polished, but physical polishing using abrasive grains and chemical polishing using chemicals are used in combination. The cases of HCI, Na, and CI were tested, and HC
It states that e is preferable.

When Fe2O3K' abrasive grains are used, the polishing speeds on the crystal planes (1118 (100) and (110) of Mn-Zn ferrite are different. The polishing speeds are faster in this order. If the polishing speed is not the same on all surfaces, Polycrystalline workpieces cannot be polished flat.

However, HC,5 has all crystal planes (110], (100)
, (Ill), that is, in the reverse order of the Fe2O3 case.

Therefore, Fe2O3 and HCl are used in combination, and the polishing effects of both are combined in a complementary manner so that any crystal plane can be polished at the same speed.

In the float polishing method, Namba et al.
This is called the "hydrodynamic bearing state."

In other words, the fluid functions as a thrust bearing.

The polishing machine as a device is explained in "Namba, Tsuwa, Wada - Development of ultra-precision surface polishing machine" Proceedings of the 1985 Autumn Conference of the Japan Society of Precision Machinery, 608 pages, 907-309. ' is an outer diameter of 460III1
11 Inner diameter 12ON, 2m pitch on the surface, 1 step width,
A spiral groove with a depth of 0.1-0.2 m is dug. The rotational speed of the tin surface plate can be continuously variable up to 500 rpm. The diameter of the workpiece head is 180 mm;
Can completely polish workpieces up to 80a+3. The rotational speed of the workpiece head can be continuously variable up to a maximum of goo rpm.

As for the reviews regarding float polishing,
Yoshiharu Nanba Whisper Float Polishing “Optics 136 (1)
984]454°.

■Problems to be solved by the invention The non-contact polishing method uses the dynamic pressure of a fluid to slightly lift the workpiece off the surface plate, polishing the workpiece with abrasive grains in the entire fluid, and polishing the workpiece with high precision. This is a method to create a polished surface.

The workpiece and surface plate are rotated at high speed to obtain dynamic pressure.

Since dynamic pressure is proportional to the square of the velocity of the fluid, it can be sufficiently lifted when rotating at high speed.

However, when the surface plate and the workpiece begin to rotate, there is no other means of applying pressure to the fluid, so the dynamic pressure becomes O, and the workpiece cannot rise from the surface plate.

The same applies when stopping the surface plate and workpiece.

Furthermore, at the beginning and end of rotation, the number of rotations may be insufficient and the dynamic pressure may be insufficient.

In this case, since the workpiece and the surface plate come into contact with each other, there is a fear that scratches may occur on the surface of the workpiece.

In order to solve this problem, it is conceivable to pull up the entire workpiece together with the workpiece head, separate it from the surface plate surface, and stop the rotation after a sufficient gap has been created.

Also, at the start of rotation, the entire workpiece is pulled up together with the workpiece head, the surface plate and workpiece head are rotated, and when a sufficient number of revolutions is reached, the workpiece head is moved onto the surface plate. A possible solution is to lower the amount of water.

However, such a method is highly risky.

As shown in FIG. 3, the workpiece head shaft is connected to the motor rotation shaft by a free joint.

A bottle 10 is provided protruding from the lower part of the motor rotating shaft 8.

This is for transmitting rotational force to the workpiece head shaft 6. A union nut 9 is inserted through the intermediate portion of the motor rotating shaft 8. A female thread 14 is cut into the inner peripheral surface of the union nut 9.

The workpiece head shaft 6 has the workpiece head 3 fixed to its lower end, and a male thread 13 with a groove 11 cut therein is formed at its upper end. The groove 11 and the bin 10 of the motor rotating shaft 8 are provided at corresponding positions. The bottle 10 fits into the groove 11.

A shaft hole 16 is bored in the center of the upper part of the workpiece head shaft 6.

To function as a free joint, the pin 10 of the motor rotation shaft 8 is fitted into the groove 11 of the workpiece head shaft 6, and the union nut 9 is screwed into the male thread 13 of the workpiece head shaft 6.

In this way, the rotational force of the motor rotating shaft 8 is transmitted to the workpiece head shaft 6 through the pin 10 and the groove 11, but the workpiece head shaft 6 can be vertically displaced to some extent.

It is an essential condition for float polishing that the workpiece head shaft 6 can freely move up and down. This is because the work must be lifted by the dynamic pressure of the fluid.

Such free joints do not restrict vertical movement, so
When the workpiece head in a rotating state is lowered onto the surface plate, the workpiece head shaft 6 is tilted due to a sudden increase/decrease in rotational force and a shearing force on the shaft. Even if the axis is only slightly tilted, an impact force is generated on the outer edge of the workpiece, causing the workpiece to be chipped or damaged.

Such unstable operations should be avoided as much as possible.

Purpose: To prevent scratches on the workpiece surface even if the workpiece comes into contact with the polishing surface plate due to insufficient dynamic pressure of the fluid when the rotation of the polishing surface plate and workpiece head starts and stops. It is an object of the present invention to provide a polishing apparatus that has the following characteristics.

(Support) Structure The position of the workpiece head can be changed in the diametrical direction, and at the beginning and end of rotation, the workpiece head is aligned with the center of the entire surface plate, and during steady rotation, the workpiece head is aligned with the center of the entire surface plate. Allow it to return to position.

In this way, the rotational movement of the workpiece head and surface plate can be
The beginning and end of rotation can be perfectly matched.

Therefore, the workpiece will not be damaged by contact with the surface plate.

This will be explained with reference to FIGS. 1 and 2.

The processing tank 1 includes a circular bottom plate and a side wall portion continuous with the circumference of the bottom plate. The processing tank 1 has the function of holding the entire polishing liquid 15.

A polishing surface plate 2 is provided inside the processing tank 1 .

There is a surface plate main shaft 4 at the bottom of the surface plate 2, which fully supports the polishing surface plate and the processing tank 1.

There is a drive device (not shown) that rotates the surface plate main shaft 4. The processing tank 1, the polishing surface plate 2, and the surface plate main shaft 4 rotate together. The polishing liquid 15 is pressed against the side wall surface of the processing tank 1 by centrifugal force.

Of course, a thin layer of polishing liquid 15 is also present on the polishing surface plate 2.

A workpiece (workpiece) 12 is attached to the lower surface of the workpiece head 3. The workpiece head 3 has a workpiece head shaft 6
is fixed to the bottom edge of.

The workpiece head shaft 6 is connected to the workpiece table 5 by a free joint S.
It is connected to a motor rotating shaft 8 suspended below.

There is a motor (not shown) inside the work table 5, and the rotating shaft 8 is rotated by the motor. As already mentioned, the free joint S has a structure 2 as shown in FIG. 3, and transmits rotational force, but allows vertical displacement of the workpiece head 3. Eventually, the motor in the worktable 5 rotates the workpiece head 3 and the workpiece 12.

Due to the rotation, the fluid under the workpiece head 3 creates a dynamic pressure that causes the workpiece head 3 to lift off the surface of the polishing platen 2. Since appropriate viscosity is required, the polishing surface plate 2 is often provided with a thin spiral groove. Further, a liquid may be added to the polishing liquid 15 to increase its viscosity.

An important point in the present invention is that the work table 5 is connected to the polishing surface plate 2.
It is possible to move in the diametrical direction.

A slide table 7 is provided in the diametrical direction of the polishing surface plate 2. The work table 5 can be moved to any position on the slide table 7. The choice of moving mechanism is arbitrary.

A rack is provided inside and on the side of the slide table 7, and the work table 5
Install a pinion on the side and engage the stiffness,
The binion may also be rotated.

The work table 5 may be moved by pulling the work table 5 with a wire from both sides and winding and unwinding the wire.

In addition, a screw shaft is installed horizontally through the slide base,
A female thread is provided on a part of the work table to be screwed into the screw shaft. The screw shaft may be rotated at the end of the slide base.

In this way, the mechanism for moving the work table 5 is arbitrary.

Of course, the work table 5 must be supported so as to allow horizontal movement relative to the slide table 7. The work table 5 may simply be slid on the slide table 7. Further, a roller may be attached to the work table so that it rolls on the upper surface of the slide table 7.

The work table 5 can be located at an eccentric position W away from the center of the surface plate, as shown in FIG. When in the W position, perform all normal polishing operations.

As shown in FIG. 2, the work table 5 is aligned with the center line 00' of the surface plate.
It is also possible to have a position that corresponds to . Let this position be the U position.

At the beginning and end of the rotation, the work table 5 is placed in the U position, and the rotation speed Φ of the workpiece head 3 and the rotation speed Φ of the surface plate are made the same.

The workpiece head 3' attached to the workpiece 11 for force application is attached to the motor rotating shaft 8 of the workpiece table 5 using a free joint S.

A polishing liquid consisting of free abrasive grains, pure water, etc. is supplied to the processing tank 1.

The work table 5 is moved along the slide table 7 and adjusted to the U position. Here, the polishing surface plate 2 and the workpiece head 3ft are started at the same time so that they have the same rotational speed.

Φ=Φ.

Since the relative speed is 0, even if the workpiece 12 is in contact with the polishing surface plate 2, the lower surface of the workpiece 12 will not be damaged by the surface plate 2.

Since the liquid is biased toward the outer wall due to centrifugal force, all of the liquid must be supplied to the center. As a method, there is a method of sending the workpiece from the center of the shaft through the center of the plate to the center of the shaft.

FIG. 4 shows the mechanism for feeding through the workpiece head.

As the rotational speed increases, the fluid speed also increases and the fluid pressure increases. Near the center, the flow velocity is low because the radius is small. However, the fluid pressure still rises to some extent.

Therefore, the workpiece 12 is lifted up by the dynamic pressure.

Even when floating, the velocity is constant = θ. Therefore, the relative speed between the workpiece 12 and the surface plate is zero.

Next, the work table 5 is moved along the slide table 7 to the eccentric position W. During the movement, a relative speed occurs between the workpiece 12 and the surface plate. However, at this time, the workpiece has already risen from the surface plate 2 and is not in contact with it, so the lower surface of the workpiece 12 will not be damaged. As the eccentric distance increases, the fluid pressure also increases, so that the lifting of the workpiece 12 increases.

Fabric example The present invention was fully implemented in a float polishing device.

A slide motor for moving the work table is provided on the tool rest outside the processing tank 1.

The screw is removed by the slide motor. A ball screw is fixed to the work table, and a threaded rod is screwed into the ball screw. The work table can be moved 1■ by the slide motor.
/Navy Blue You can slide it at low speed.

First, the work table 5 is set at the center U position.

The workpiece head 3 and polishing surface plate 2 are rotated at the same speed. As the rotation speed increases and reaches a certain level,
The work table 5 was slid and moved to an eccentric position. The distance of UW is 100-150M.

Ordinary polishing was performed at eccentric position W.

When stopped, move from the eccentric position W to the center position, approximately 30 minutes to 1 (7).
I took a few minutes to slide the work table. At the center position U, the rotational speed was decreased while maintaining the relationship φ=e.

In this type of polishing, the workpiece and the polishing surface plate remained in a non-contact state, and no scratches such as those caused by the grooves of the surface plate rubbing against the machined surface of the workpiece were observed.

■ Effects At low rotational speeds, when starting or stopping, the center of rotation of the workpiece and the center of rotation of the surface plate are completely aligned and rotated at the same speed, so even if the surface of the workpiece contacts the surface plate, it will not occur. The strainer does not damage the work surface.

In particular, conventionally, the workpiece surface was scratched during the stopping process, but this does not occur with the present invention.

A high precision polishing surface can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of the polishing apparatus of the present invention during normal polishing. FIG. 2 is a longitudinal sectional view of the polishing apparatus of the present invention at the end or beginning of polishing. FIG. 3 is an exploded perspective view showing the structure of a free joint between the motor rotation shaft and the workpiece head shaft. FIG. 4 is a cross-sectional view of an example mechanism for supplying liquid through a workpiece head. 1... Processing tank 2... Polishing surface plate 3... Workpiece head 4... Rotating main shaft 5... Working table 6...
Workpiece head shaft 7... Slide stand 8... Motor rotation axis 9... Union nut 10... Bin 11... Groove 12... Workpiece 13... Male thread 14... Female thread 15... Polishing liquid 16... Shaft hole S... Free joint W... Eccentric position U... Center position

Claims (1)

[Claims] A surface plate main shaft 4 that can be rotated by a drive mechanism, and a surface plate main shaft 4
A polishing surface plate 2 fixed to the top, a processing tank 1 attached integrally with the polishing surface plate 2 for holding polishing liquid, a workpiece head 3 to which a workpiece 12 is to be attached on the lower surface, and a workpiece head. 3 is fixed to the lower end of the workpiece head shaft 6, a free joint S connecting the workpiece head shaft 6 to the motor rotation shaft 8 in a manner that allows vertical displacement and propagates rotation, and a motor rotation shaft 8.
a work table 5 that holds a motor that provides rotational force to the work table 5; a slide table 7 that supports the work table 5 so as to be movable in parallel and is installed in the diametrical direction of the polishing surface plate; At the end and beginning of rotation of the polishing surface plate 2, the workpiece head 3 is moved to the center position U of the polishing surface plate 2, and the workpiece head and the polishing surface plate are moved in parallel. A polishing apparatus characterized in that the relative rotational speed of the workpiece 12 and the surface plate 2 is approximately 0 by making the rotational speeds of the workpiece 12 and the surface plate 2 the same.