JPH0818238B2 - Polishing tool manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a polishing tool, and more particularly to a method for manufacturing a polishing tool capable of performing polishing processing with high surface accuracy using magnetic polishing abrasive grains. . Such a polishing tool is used for polishing optical elements such as lenses, prisms and mirrors.

[Prior Art and Problems Thereof] In general, an optical element such as a lens, a prism and a mirror has a functional surface, that is, a surface through which light is transmitted and / or reflected after shaping a material such as glass or metal into a predetermined outer shape. It is manufactured by polishing to gradually reduce the surface roughness and at the same time to a predetermined surface accuracy.

In the polishing step, a polishing method using free abrasive grains or a polishing method using fixed abrasive grains is adopted.

The polishing using loose abrasive grains is performed mainly by rolling the abrasive grains while pressing a polishing tool having a surface with a predetermined surface accuracy against the object to be polished with the free abrasive grains as a medium. In the polishing method using the loose abrasive grains, even if the surface accuracy of the polishing tool is relatively low, there is an advantage that the surface accuracy of the object to be polished can be made relatively good by appropriately setting the polishing conditions. However, there is a difficulty that it requires the skill of an operator to set appropriate polishing conditions.

On the other hand, the polishing using the fixed abrasive grains has the abrasive grains fixed to at least the surface of a polishing tool having a predetermined surface accuracy, and is mainly used for scratching the abrasive grains while pressing the tool against an object to be polished. Based on this, polishing is performed. In this polishing method using fixed abrasive grains, the surface precision of the polishing tool is reflected in the surface precision of the object to be polished relatively faithfully, so the production of polishing tools is more difficult than the case of polishing using loose abrasive grains. Although somewhat troublesome, it has an advantage that the work piece can be easily polished to a predetermined surface accuracy once the tool is manufactured.

Therefore, the polishing tool used in polishing with the fixed abrasive is conventionally manufactured by dispersing the abrasive in the abrasive holding member (bonding material) and then hardening the binder to fix the abrasive. In many cases, the surface of the tool that comes into contact with the object to be polished and is involved in the polishing process is often given a predetermined accuracy by post-processing if high surface accuracy is required.

However, since the processing of the tool surface after the binder is hardened is the processing of the abrasive grain containing body, there is considerable difficulty. In addition, even if the post-processing like this makes the shape as a whole closer to the desired shape, the tip of a certain abrasive grain is microscopically protruded from the desired surface, or the tip of a certain abrasive grain is more than the desired surface. It may be retracted, and a sufficiently high precision cannot be obtained.

When polishing is performed using such a conventional fixed-abrasive polishing tool, it is difficult to achieve sufficiently high surface accuracy, and in addition, it often causes scratches on the surface of the object to be polished. is there.

Therefore, it is an object of the present invention to provide a polishing tool capable of performing polishing processing with good surface accuracy without causing surface defects such as scratches.

[Means for Solving the Problems] According to the present invention, the above-described object is to arrange abrasive grains having magnetism on a reference surface, and to apply a magnetic force from the reference surface side so that the abrasive grains are used as a reference. A polishing tool, characterized in that an external force other than a magnetic force is applied to the surface while making the abrasive grain distribution on the reference surface uniform, and thereafter the abrasive grains on the reference surface are transferred to a holder. It is achieved by the manufacturing method of.

[Examples] Specific examples of the present invention will be described below with reference to the drawings.

1 to 4 are schematic process diagrams showing a first embodiment of a polishing tool manufacturing method according to the present invention. In these drawings, the same members are designated by the same reference numerals.

In FIG. 1, 2 is a reference body. An upper surface of the reference body is processed into a plane (reference plane) with sufficiently high accuracy by lapping or the like and has a sufficiently fine surface roughness.
The reference body 2 is made of a magnetic material, and a coil 4 is wound around the lower portion of the reference body 2 in the up-down direction, whereby an electromagnet is formed by using the reference body 2 as a yoke. Reference numeral 6 denotes a coil cover, which is attached to the reference body 2.

The electromagnet is driven by the drive unit 8. The driving unit includes a battery 10, a variable resistor 12 and a switch 14, which allows the current flowing through the coil 4 to be adjusted appropriately.

Reference numeral 16 is a vibration generator, which is used to apply a vibration of several tens to several hundreds Hz to the reference body 2 and the cover 6.

First, the abrasive grains 20 are scattered on the reference surface of the reference body 2.
The abrasive grains have magnetism. Examples of such magnetic polishing abrasive grains include those in which the surface of diamond abrasive grains is coated with nickel.

Next, the variable resistance value of the electromagnet drive unit 8 is appropriately set, and the switch 14 is turned on. As a result, the electromagnet acts and the magnetic polishing abrasive grains 20 are attracted to the reference surface of the reference body 2. At the same time, the vibration generator 16 is activated to apply a vibration mainly in the lateral direction to the reference body 2. As a result, the distribution of the abrasive grains on the reference surface 2 is made uniform over the entire surface, and particularly the slender abrasive grains are aligned in the vertical direction. The amount of the abrasive grains at the time of spraying is determined so that the uniform distribution of the abrasive grains on the reference surface and the desired distribution density can be obtained by this uniform distribution. Alternatively, the amount of abrasive grains during the above-mentioned spraying may be excessive, and an external force such as a wind force may be uniformly applied to remove excess abrasive grains when the distribution is uniform. Further, by turning on and off the action of the electromagnet by the driving unit 8 and the vibration by the vibration generating unit 16 at appropriate times, a desired uniform distribution can be achieved.

Next, as shown in FIG. 2, the reference body 2 holding the abrasive grains uniformly distributed as described above is turned upside down while the electromagnet is still operating, and the abrasive grain holding member is held. Opposite 22. In FIG. 2, the abrasive grain holding member 22 is a plate 24.
Supported by The holding member 22 is a viscoelastic body such as tar pitch. The pitch is heated to 50 to 60 ° C. to be in a softened state.

Next, as shown in FIG. 3, the reference body 2 is brought into contact with the softened holding body 22 and pressed with an appropriate pressure. In this pressed state, the holder pitch is cured by natural cooling or forced cooling.

Next, when the switch 14 of the drive unit 8 is turned off to stop the action of the electromagnet and the reference body 2 is removed, the abrasive grains 20 are transferred to the surface portion of the holding body 22 as shown in FIG. Then, it is fixedly held to obtain a fixed abrasive polishing tool.

In this embodiment, the steps shown in FIGS. 2 to 4 may be performed with the vertical direction reversed.

Since the tool obtained as described above is based on the transfer of the reference surface, the surface formed by the tip of the abrasive grain 20 is an accurate flat surface corresponding to the shape of the reference surface, and the protruding abrasive grain is Needless to say, there is no abrasive grain that has been drawn in because it is surely positioned by magnetic force. Moreover,
Since the abrasive grains 20 are arranged in the direction perpendicular to the surface by the action of magnetic force, the polishing efficiency is extremely good.

FIG. 5 is a schematic view showing a second embodiment of the polishing tool manufacturing method according to the present invention.

This embodiment is different from the first embodiment only in that the step of FIG. 1 in the first embodiment is performed by inclining the reference body 2 as shown in FIG.

In this embodiment, vibration is applied to the reference body 2 in a slanted state, whereby excess abrasive grains can be removed by the action of gravity. The degree of removal of the abrasive grains can be adjusted by appropriately setting the tilt angle.

FIG. 6 is a schematic view showing a third embodiment of the polishing tool manufacturing method according to the present invention.

This embodiment is also different from the first embodiment only in that the reference body 2 is turned upside down as shown in FIG. 6 in the step of FIG. 1 in the first embodiment.

In the above-mentioned embodiment, the polishing surface of the polishing tool is a flat surface, and thus the reference surface is a flat surface.However, the present invention shows that the polishing surface of the polishing tool is a concave or convex spherical surface or an aspherical surface other than a flat surface. Of course, it can be applied to the case. In this case, it is sufficient to use the reference body 2 having the reference surface of the corresponding curved surface with the concavo-convex opposite.

Although the tar pitch is exemplified as the abrasive grain holding member 22 in the above-mentioned embodiment, in the present invention, as the holding member,
Other pitches and even other suitable binders can be utilized. Examples of such a binder include thermoplastics such as vinylol chloride and polypropylene, and when these are used, they are appropriately softened by being heated to appropriate temperatures during transfer.

The grain size of the polishing abrasive grains in the present invention can be appropriately determined according to the degree of desired surface roughness, and from the fine grain size for obtaining an optical surface to the matte surface degree and the surface referred to as the ground surface. It may be any one up to the particle size for obtaining the roughness.

EFFECTS OF THE INVENTION According to the present invention as described above, it is possible to manufacture a fixed-abrasive polishing tool in which the tips of the abrasive grains are precisely adapted to the surface of the desired shape, and therefore Even if the classification is insufficient, it is possible to carry out polishing with good surface accuracy without causing surface defects such as scratches.

Further, according to the present invention, since the abrasive grains are arranged substantially at right angles to the reference surface by the action of the magnetic force, it is possible to obtain the polishing tool having the polishing abrasive grains arranged substantially at right angles to the surface and having good polishing efficiency. .

Furthermore, according to the present invention, since the distribution density of the abrasive grains can be appropriately set by appropriately adjusting the magnetic force and / or other external force at the time of sucking the abrasive grains to the reference surface, a tool having a desired degree of concentration can be provided. It can be easily manufactured.

[Brief description of drawings]

1 to 4 are schematic process diagrams showing a polishing tool manufacturing method according to the present invention. 5 and 6 are schematic views showing a polishing tool manufacturing method according to the present invention. 2: Reference body, 4: Coil, 6: Cover, 8: Drive part, 16: Vibration generating part, 20: Abrasive grain, 22: Abrasive grain holding member, 24: Plate.

Claims (3)

[Claims] 1. An abrasive grain having magnetism is arranged on a reference surface,
A magnetic force is applied from the reference surface side to apply an external force other than the magnetic force while attracting the polishing abrasive grains to the reference surface to make the abrasive grain distribution on the reference surface uniform, and thereafter, the abrasive grains on the reference surface. A method for manufacturing an abrasive tool, comprising transferring the particles to a holder. 2. The method for manufacturing a polishing tool according to claim 1, wherein an external force other than the magnetic force is generated by applying vibration to the reference surface. 3. Transfer transfer of abrasive grains to a holding body presses a softened holding body against a reference surface in a state where a magnetic force is applied to the abrasive grains, then hardens the holding body, and thereafter magnetic force to the abrasive grains. The method for producing a polishing tool according to claim 1, which is carried out by stopping the action of step 1) and separating the reference surface from the holder.