JPH10249720A - Polishing work method of flat workpiece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continuously perform the polishing process while keeping the performance, by supplying the slurry including the free abrasive grain while continuously conveying a carrier which holds a number of plate-shaped workpieces between the pads, and respectively pressing the pads onto the surfaces of the workpieces, for simultaneously and continuously polishing the both parallel faces. SOLUTION: A carrier 1 holding the disc-shaped workpieces W in the pocket parts 6, is passed through between the pads 2, 3 which are opposite to each other and rotates in the direction B, C opposite to each other. A pair of pads 2, 3 are respectively pasted on the metallic plates 7 for supporting the pad, and rotated in the directions B, C opposite to each other by a rotary driving shaft, and the angle of the pads to the workpiece is adjusted. The pressing force of the pads 2, 3 to the workpieces is controlled by the adjustment of the stroke of the rotary driving shaft. Further the pads 2, 3 comprise the slurry supply ports 4, so that the slurry (polishing fluid including free abrasive grain) is supplied to the interfaces of the pads 2, 3 and the workpieces from the external during the polishing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing method for a flat work, and more particularly to a polishing method suitable for finishing both surfaces of a soft flat work such as an aluminum substrate for a magnetic disk. It is about the method.

[0002]

2. Description of the Related Art Conventionally, optical lenses, Si wafers,
Alternatively, there is a polishing method as a method of finishing (polishing) a surface such as a magnetic disk made of aluminum, glass, resin, carbon, or the like to a mirror surface or a surface having geometric accuracy.

[0003] As is well known, the finishing accuracy of a Si wafer is determined by a flatness NTV (non linear thickness varia).
Option) High accuracy of 2 μm or less is required. In addition, a substrate for a magnetic disk used in a storage device such as a computer requires a surface roughness of 0.013 μm Ra (130 以下 Ra) or less in accordance with a demand for higher density.

[0004] In polishing a flat workpiece requiring high surface finishing accuracy, in other words, when it is desired to reduce the surface roughness by polishing two parallel surfaces of the flat workpiece, Excellent polishing method. In general, according to this polishing method, a smaller surface roughness is obtained than in other grinding processes or the same type of lapping process as a loose abrasive process, and the process accuracy is excellent.

[0005] This polishing method is, for example,
"Metal Handbook" (issued by Maruzen on March 31, 1990, 1207-1209)
Page), or "Ultra-precision production technology large volume 2 practical technology"
(Published by Fuji Techno System on August 23, 1994, 233 to 23
As described in (p. 9), this is one type of free abrasive grain processing in which free abrasive grains are polished with a slurry in which free abrasive grains are mixed with a polishing liquid together with lapping. More specifically, several μm
Processing is performed at an appropriate polishing pressure using a polisher or a polishing cloth (hereinafter referred to as a pad) of a soft material tool such as a synthetic resin, artificial leather, fiber, pitch, or the like with the following fine abrasive grains. For this reason, compared with lapping processing using abrasive grains of 1 to several tens of μm and a lap of a hard material tool such as cast iron, the abrasive grains are brought into contact with the plate-like workpiece while being elastically held by the pad. Therefore, more accurate polishing can be performed.

A mechanism for polishing two parallel surfaces (both surfaces) of the flat workpiece is a polishing plate applying mechanism or an upper and lower platen (metal plate) provided with a micrometer.
The pad is adhered to the pad, and the pad and the flat work held in the carrier that rotates and revolves are slid relative to each other, and the slurry containing loose abrasive grains is supplied to the surface to be polished of the flat work to perform polishing. Is what you do.

As described above, the polishing method is excellent in that the obtained surface roughness can be made smaller than other finishing methods. However, the processing method supplies a plate-like workpiece one by one to a polishing machine. The processing is performed in a single-wafer system for processing and discharging, or in a batch system in which a plate-shaped workpiece is collectively carried into and out of the carrier, and the operation of the polishing machine is stopped during these operations.

On the other hand, there is a double-head grinding method as a finishing method having high productivity. This double-head grinding method is originally used mainly for finishing hard metal materials such as iron and steel, for example, for finishing mechanical parts such as bearings, and holds a workpiece to be ground on a disk-shaped or band-shaped carrier. And, together with the target workpiece,
The disk-shaped or band-shaped carrier is continuously passed between a pair of grinding wheels rotating at a high speed of several hundred rpm to continuously grind the surface of a target workpiece.

For this reason, the double-head grinding method has a higher grinding speed than the polishing method or other double-sided lapping method. Further, unlike the polishing method, there is no need to stop the operation of the double-sided grinding machine when the aluminum substrate is carried into and out of the carrier, and continuous grinding of the aluminum substrate is possible. Therefore, the double-sided grinding method is extremely high in productivity,
It is more advantageous than other grinding methods.

This double-ended grinding method itself is disclosed in, for example, Japanese Patent Publication No. 55-37378 and Japanese Patent Laid-Open No. 6-304854. First, Japanese Patent Publication No. 55-373
Japanese Patent Publication No. 78 discloses that a metal thin plate piece for a precision component or a ceramic thin plate piece for an IC is conveyed by an endless belt-shaped carrier for continuous grinding by a double-head grinding method.

[0011] In this publication, a belt made of a metal strip having pocket portions substantially adapted to the size of a workpiece at equal intervals is used as a carrier and is run linearly or endlessly.
The mechanism is such that a workpiece moving while being held by a carrier is machined from both front and back sides by a rotating disk-shaped grindstone. Also, the workpiece is automatically inserted and ejected by
It is attached to and detached from the carrier pocket to ensure continuous processing.

Next, Japanese Patent Application Laid-Open No. 6-304854 discloses a double-head grinding method having a disc-shaped carrier different from the belt-shaped carrier. The double-headed grinding apparatus of the publication discloses a disk-shaped carrier in which a plurality of pockets capable of accommodating a workpiece on an arc are provided at equal intervals between a pair of grinding wheels arranged opposite to each other, This is a configuration in which both sides of the workpiece stored in the pocket of the carrier are continuously ground.
This publication also discloses a loading pusher and an unloading pusher for storing and removing a workpiece in and from a pocket to ensure continuous processing.

The present inventors have improved these conventional double-ended grinding methods for grinding relatively hard materials such as iron, steel, and ceramics for finishing of relatively soft materials such as aluminum substrates. did. That is, the used grindstone is changed from a hard grindstone such as a vitrified grindstone or a resinoid grindstone to an elastic grindstone such as a PVA grindstone, and a flat plate such as an aluminum substrate is formed by a double-head grinding method using an endless belt-shaped carrier or a disc-shaped carrier. The method of continuously finishing (grinding) a workpiece is described in Japanese Patent Application Nos. 8-83820 and 8-85165.
And Japanese Patent Application No. Hei 8-117923.

With this improvement, the surface roughness required for an aluminum substrate as a magnetic disk is 0.02 μm Ra.
(Rmax of 0.2 μm) can be achieved. By the way, when the aluminum substrate is subjected to double-head grinding using the hard grindstone, the achievable surface roughness is at most
It is up to about 1-2 μmRa.

[0015]

However, in the case of, for example, a magnetic disk to which the present invention is applied, the required surface roughness is becoming smaller and smaller with the further increase in density, and recently, the magnetic disk having a surface roughness of 0.013 μm Ra or less is required. Is also needed. On the other hand, in the double-head grinding method using the PVA-based grindstone, although the removal amount can be increased, it is difficult to cope with the further miniaturization of the required surface roughness with respect to the production of the grindstone described later. Difficult due to fundamental structural constraints.

In the above polishing method, removal is performed with a small cutting pressure and a small cutting depth by using free abrasive grains in the slurry. However, as described above, the supply, processing, and discharge of the flat workpiece to the polishing machine are performed in a single-wafer system or a batch system, so that the productivity is low and the productivity is further improved. I ca n’t hope
There are serious challenges.

Accordingly, an object of the present invention is to make the polishing process continuous while maintaining the performance (advantage) of the polishing processing method capable of finishing with higher precision such as achieving the required surface roughness. An object of the present invention is to provide a polishing method capable of improving productivity of finishing work of a workpiece by the continuity.

[0018]

For this purpose, in the present invention, a polishing method is provided in which a carrier holding a large number of flat workpieces at predetermined intervals is continuously placed between pads rotating opposite to each other. While passing the slurry, the slurry containing loose abrasive grains is supplied to the surface of the pad, and each pad is pressed against the surface of the plate-like workpiece to simultaneously and continuously grind the parallel surfaces of the plate-like workpiece. Improve to do.

The polishing is basically performed by using a slurry and a pad of a soft material tool. Therefore,
It is the free abrasive grains in the slurry that exert a processing action,
Paying attention to this abrasive grain, the removal processing can be performed with a small cutting pressure and a small cutting depth. Therefore, since the processing unit is small, the processing efficiency is low, but the obtained surface roughness is small, and a good finished processed surface satisfying the required surface roughness can be obtained.

When this is compared with the double-head grinding method using the above-mentioned elastic grindstone, the elastic grindstone such as the PVA grindstone is
A binder is a resin composition mainly composed of polyvinyl alcohol (PVA) or the like, and a melamine and a phenol-based refining resin mixed appropriately as a binder.
A grindstone in which abrasive grains such as C, C, and WA are embedded. As described above, a grinding wheel such as a PVA-based grinding wheel is used as a hard grinding wheel such as a vitrified grinding wheel or a resinoid grinding wheel because the binder is a soft resin and is porous having many pores in the binder. In comparison, it is a grindstone with high elasticity and toughness.

Therefore, when grinding a soft workpiece such as pure aluminum or an aluminum alloy (hereinafter simply referred to as aluminum), the elasticity and toughness of the individual abrasive are high due to the binder itself and the presence of pores. The actual cutting load of the grains is buffered, and as a result, the processing unit is reduced, so that a surface having a small surface roughness is obtained. Further, due to the function of the pores described above, it is also excellent in discharging property of dropped abrasive grains and minute aluminum grinding debris.

However, compared to the free abrasive grains in the polishing process, the PVA-based grindstone is a fixed abrasive grain restrained by a binder, and the cutting pressure of each abrasive grain is limited by the restraint. However, the cutting depth tends to be large. Also, the minimum size of the abrasive grains is generally about 1 to 0.5 μm because of the technical restrictions for manufacturing the abrasive grains into a grindstone and making it usable as a grindstone.

On the other hand, the abrasive grains used in the polishing method are free abrasive grains mixed with the polishing liquid, and there are no restrictions on the production of a grindstone such as a PVA grindstone. For this reason, as long as it is possible to produce abrasive grains of a desired particle size, a small abrasive grain size can be freely selected, and in terms of the abrasive grains, a finer surface roughness can be realized than the double-head grinding method. .

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The size of free abrasive grains in the present invention is appropriately selected depending on polishing conditions and target surface accuracy (surface roughness). It is preferred to use loose abrasives of ~ 2.0 µm. If the average particle size of the free abrasive grains is too small, the polishing efficiency is remarkably reduced and the removal amount (processing amount) is also reduced, so that polishing may not be performed. On the other hand, if the average particle size of the free abrasive grains is too large, the surface roughness 0.01
A surface accuracy of 3 μmRa or less cannot be obtained.

As described above, in the polishing method,
The point is to use a slurry containing free abrasive grains, but in the continuation of the polishing method, it is preferable to take into account a new problem that occurs when the free abrasive grains are used. The present inventors have found that when performing continuous polishing using a circulating endless carrier, a phenomenon in which the surface roughness of a workpiece increases with the processing time or scratches increase may occur. I found that.

Therefore, as a result of investigating the cause, the slurry used inevitably adheres to the carrier and the peripheral equipment during the polishing process. It has been found that it has an adverse effect on the finishing accuracy of the product.

That is, in the present invention, a belt-shaped or disk-shaped endless carrier is circulated and used in order to make the polishing process continuous. During the period in which the slurry is rotated once or around the carrier and re-enters between the pads together with a new workpiece, a phenomenon is likely to occur in which the abrasive grains agglomerate, dry and solidify on the carrier surface. When the hardened abrasive grains are again put between the pads, they are melted by the new slurry and fall off from the carrier, but the abrasive grains once aggregated do not immediately disperse. Therefore, when the agglomerated abrasive grains enter between the pads, they behave as if they are a single abrasive grain having a large particle diameter. In order to polish the workpiece, the surface roughness of the workpiece is increased (deteriorated). Or cause scratching.

Therefore, in order to make the polishing process continuous according to the present invention, the endless carrier is washed to remove the attached slurry before and / or after passing the endless carrier between the pads. Is particularly preferred. In addition, since the slurry at the time of the polishing process is scattered and adheres to the peripheral devices of the carrier, there is a possibility that these slurries may fall or fly on the carrier or the pad. For this reason, it is more preferable that these carrier peripheral devices are also washed together so that the slurry does not adhere so that the slurry does not have the same adverse effect as the slurry attached to the carrier.

Further, in the present invention, it is preferable to use the double-headed grinding method using the above-mentioned elastic grindstone improved by the present inventors as preprocessing of the polishing method. Although the polishing method itself has excellent surface accuracy, it has a problem that the removal amount cannot be increased (the processing amount cannot be increased) as compared with other polishing / grinding processes. Therefore,
Pre-processing is required to increase the removal amount and achieve high efficiency as a finishing processing step. Conventionally, the lapping or the like has been used for this pre-processing. However, this lapping process is also a batch type, similar to the conventional polishing method. Even if the productivity is improved only by the polishing process, if the productivity of the pre-process does not increase, the productivity of the entire finishing process can be improved. Does not lead to

Therefore, in the present invention, in order to improve the productivity of the entire finishing process, it is preferable that the pre-processing is also performed continuously in accordance with the continuous polishing process. For this reason, as a pre-process excellent in continuity, a double-headed grinding method using the elastic grinding stone is used. That is,
The double head grinding method and the polishing method can be combined into one continuous finishing line to increase the removal amount and reduce the number of handling steps such as attaching and detaching the workpiece to and from the carrier. In addition, a highly accurate workpiece can be obtained with higher efficiency and higher efficiency.

An embodiment of the apparatus used in the polishing method of the present invention will be described below with reference to FIGS. First, in FIGS. 1A and 1B, reference numeral 10 denotes a polishing apparatus of the present invention. Reference numeral 1 denotes a workpiece carrier, which is moved by a carrier moving mechanism shown in FIGS.

The carrier 1 made of a band-shaped metal has a plurality of pockets 6 formed at predetermined intervals in the longitudinal direction and formed with holes through which a disk-shaped workpiece W such as an aluminum substrate is engaged. The carrier 1 is rotated counterclockwise in the directions of arrows B and C while holding the disk-shaped workpiece W in the pocket portion 6 so that the carrier 1 is passed between the pads 2 and 3 disposed opposite to each other. Is configured.

A loading mechanism 8 for sequentially engaging the aluminum substrate 2 with the pocket portion 1a is provided on one side on the left side of the carrier 1 in the figure, and an anchor for removing the aluminum substrate 2 from the pocket portion 1a is provided on the other right side. A loading mechanism 9 is provided. Although the loading 8 or the unloading mechanism 9 is not shown in detail, a commonly used known mechanism can be appropriately used.

The pair of pads 2 and 3 are attached to a metal plate 7 for supporting the pads, respectively. The pair of pads 2 and 3 are rotated in mutually opposite directions B and C by a rotary drive shaft (not shown), and are rotated with respect to the workpiece. The angle of the pad is adjusted. In addition, the pressing force of the pads 2 and 3 against the workpiece is
It is controlled by adjusting the stroke of the rotary drive shaft. Further, the pads 2 and 3 are provided with a slurry supply port 4, and a slurry (a polishing liquid containing free abrasive grains) is externally supplied to the interface between the pads 2 and 3 and the workpiece during polishing.

With the above configuration, continuous polishing of the target workpiece can be performed, but there is a problem that the slurry inevitably adheres to the carrier when the slurry is supplied and the polishing is continuously performed. To solve this problem, as described above, before and / or after passing the endless carrier between the pads, a mechanism for cleaning the endless carrier and removing the attached slurry is necessary, This mechanism will be described next.

FIGS. 2 to 5 show an embodiment of a mechanism for cleaning the endless carrier.
The loading mechanism 8 and the unloading mechanism 9 are the same as those shown in FIGS. 1 (a) and 1 (b). First, in FIG. 2, a cleaning mechanism 11 for cleaning an endless carrier
Is a pair of cylindrical rotating brushes 13 having a length sufficient to wash the passing endless carrier from both sides and covering the entire carrier width, and a contact surface of the rotating brush 13 with the endless carrier and its vicinity. And a nozzle 12 (a pair is arranged from both sides of the carrier toward the endless carrier) for supplying the cleaning water to the carrier. Then, the rotating brush is rotated by a motor (not shown) and pressed against the surface of the carrier 1 to remove the adhered slurry.

The mechanism for cleaning the carrier itself is not limited to this. In short, any known brush or sponge in place of a brush can be used as long as it can continuously clean the surface of the traveling carrier 1. Can be appropriately selected. If the slurry can be removed, only water and / or a cleaning agent may be used without using a means such as wiping or rubbing with a brush or a sponge.

In FIG. 2, the cleaning mechanism 11 is provided downstream of the polishing apparatus 10. 3 to 5 show examples in which the configuration of the cleaning mechanism 11 is the same as that in FIG. 2, but the positions at which the cleaning mechanism 11 is provided are respectively changed. FIG. 3 shows an intermediate point of the endless carrier, and FIG. 5 is provided on both the upstream side and the downstream side of the polishing apparatus 10 in FIG.

As described above, an appropriate number of the cleaning mechanisms 11 may be provided at appropriate positions on the carrier. Cleaning mechanism 1 like 2,
1 is preferably provided downstream of the polishing apparatus 10. Also, as shown in FIG.
If the cleaning mechanism 11 is provided on the upstream side of the pad, foreign matter (frictional powder generated between each part guiding the carrier, dust in the air, dust, etc.) adhering during one round of the carrier is generated between the pads. This is preferable because it is possible to reliably prevent the occurrence of scratches caused by entering. Therefore, as shown in FIG.
Providing a cleaning mechanism on both the upstream side and the downstream side of the polishing apparatus 10 is more preferable in terms of improving the surface roughness and preventing the occurrence of scratches while performing continuous polishing.

The polishing apparatus shown in FIGS. 1 to 5 only shows an example in which a pair of opposing pads is arranged in one stage between a loading mechanism and an unloading mechanism for a workpiece. When the polishing process needs to be performed stepwise, a plurality of pad pairs are arranged in series along the carrier 1 and the roughness of the free abrasive grains in the supply slurry in each pad pair is gradually reduced. Or you may make it the roughness of the same free abrasive grain.

FIG. 6 discloses a polishing apparatus having a disc-shaped carrier different from the belt-shaped carrier. The polishing apparatus shown in FIG. 1 rotates a disc-shaped carrier 1 in which a plurality of pockets 6 capable of accommodating a workpiece on an arc are provided at equal intervals between a pair of pads 2 and 3 arranged opposite to each other. Then, both surfaces of the workpiece W stored in the pocket 6 of the carrier 1 are continuously ground. In this figure, too, a loading mechanism 8 and an unloading mechanism 9 for appropriately selecting a means such as a pusher for storing and removing the workpiece W in the pocket 6 and removing the workpiece W from the pocket 6 are provided in order to ensure continuous processing. .

The disc-type carrier cleaning mechanism shown in FIG. 6 includes a rotating brush 13 rotating around a rotation axis perpendicular to the carrier, and a nozzle 12 for supplying cleaning water toward the working surface of the brush. Consists of Also, this cleaning mechanism,
The carrier is provided after the disc-shaped carrier is passed between the pads. However, like the belt-shaped carrier, the carrier may be provided before entering between the pads and / or after exiting from between the pads.

FIG. 7 shows a double-headed grinding method using an elastic grindstone as a pre-processing of the polishing method. Shown is a continuous apparatus. With this configuration, it is possible to improve the productivity of the entire finishing process in accordance with the continuation of the polishing process.

In FIG. 7, reference numeral 20 denotes an apparatus for performing double-head grinding, which is provided on the upstream side of the polishing apparatus 10. In FIG. 1, a cleaning mechanism 11 includes a downstream side of a polishing apparatus 10 and a double-sided grinding apparatus 20.
And a polishing apparatus 10.
Among them, the double-ended grinding device 20 and the polishing device 10
The purpose of the cleaning mechanism 11 is to carry out pre-cleaning in order to prevent the falling-off abrasive grains in the double-headed grinding device 20 from being mixed into the polishing device 10, and in this case, a rotating brush or the like is brought into contact therewith. Therefore, there is a possibility that the workpiece may be damaged or the workpiece may be pushed out of the carrier. Therefore, only the cleaning water supply nozzle is provided as shown in FIG. In addition, in the example of FIG. 7, the device configuration is substantially the same as in FIGS. 2 to 5 except that a load mechanism 8 is provided on the upstream side of the double-headed grinding device 20 in addition to the cleaning mechanism.

FIG. 8 shows an embodiment of the double-headed grinding device 20.
(A) and (b) show. In the figure, the carrier 1 of the workpiece is moved in the direction of the right arrow A in the figure by the carrier moving mechanism shown in FIGS. The carrier 1 made of a band-shaped metal is the same as that shown in FIG. 1 described above, and a pair of elastic grindstones arranged opposite to each other and rotated in the opposite direction while holding the disk-shaped workpiece W in the pocket portion 6. It is configured to be passed between 22, 23.
On one side of the carrier 1 on the left side in the figure, a loading mechanism 8 for sequentially engaging the aluminum substrate 2 with the pocket portion 1a is provided.

The rotary drive shaft 21 of the grindstone rotates the elastic grindstone at a high speed and adjusts the angle of the elastic grindstone. In addition, the cutting amount of the elastic grindstones 22 and 23 is set to
The stroke is controlled by adjusting the stroke to maintain the gap between the grinding wheels. The adjustment of the stroke may be used as a means for maintaining a constant gap between the grindstones when the workpiece passes and separates from the elastic grindstone.

As shown in FIG. 8 (b), a workpiece rotation braking means 24 is provided at each of the pair of grindstones 22 and 23 at the entrance and exit sides of the carrier 1. The workpiece rotation braking means 24 brakes the rotation of the disk-shaped workpiece when the disk-shaped workpiece enters between the whetstones and when the disk-shaped workpiece passes and separates from the whetstone. It is a means for preventing the occurrence of grinding streaks in different directions on both grinding surfaces, and at the same time, preventing the end face of the disc-shaped workpiece from being scratched and ensuring the surface accuracy of the workpiece. . Further, if the workpiece rotation braking means 24 is operated only from one side of the workpiece, it may affect the attitude of the workpiece. Therefore, as shown in FIG.
As shown in FIG. 2B, the work is provided on both sides of the work so as to oppose each other.

The workpiece rotation braking means 24 is provided with an elastic resin, for example, rubber, having a lower hardness than the disk-shaped workpiece W at the tip of a coil spring 24a which is a pressing mechanism for pressing with a constant force having one end fixed. A block-shaped solid brake body 24b is attached to the disk-shaped workpiece W by the elastic force of the coil spring 24a.
, The rotation of the disk-shaped workpiece W is braked. In this case, the workpiece rotation braking means 24 is provided only on one side of the carrier 1. However, if the workpiece rotation braking means 24 is provided on both sides of the carrier 1, the disc-shaped workpiece W can be moved from both sides. Since it is pressed, it is preferable for improving the grinding accuracy of the disk-shaped workpiece W. As the pressing mechanism, for example, a leaf spring, an air cylinder, or a mechanism using elasticity of rubber may be used.

The workpiece rotation braking means may be a roller-shaped solid or disk-shaped workpiece having a lower hardness than that of the disk-shaped workpiece, such as an elastic resin rolling on the surface of the disk-shaped workpiece. There are thin-plate resin whose tip contacts the surface of the object, and brushes that contact the surface of the disc-shaped workpiece in a state where the tip is bent in the moving direction of the carrier. May be provided together with a pressing mechanism that presses the surface with a constant force.

The double-sided surface grinders of FIGS. 7 to 8A and 8B are only examples in which a pair of elastic grindstones are arranged in a single stage between a loading mechanism and an unloading mechanism for a workpiece. Although not shown, for example, when it is necessary to perform the grinding stepwise from rough grinding processing to finish grinding processing, the roughness of the grindstone is sequentially reduced along the carrier 1 or the same grindstone is roughened. A plurality of elastic grinding stone pairs may be arranged in a plurality of stages, in series or in parallel along the traveling direction of the workpiece. In this case, from the rough grinding to the finish grinding, the same elastic grindstone, for example, a PVA grindstone may not be used, but a normal hard grindstone may be used for the rough grind and the PVA grindstone may be used for the finish grind. Further, the size (diameter) of the grindstone may be increased, the width of the carrier 1 may be increased, and the workpieces may be arranged in a plurality of rows, or the carriers 1 may be arranged in a plurality of rows in parallel.

[0051]

【Example】

[Example 1] A JIS 5086-based aluminum alloy for a magnetic disk having an outer diameter of 90 mm and an initial thickness of 0.9 mm, using a polishing apparatus provided with a cleaning mechanism 11 shown in FIG. An example in which a substrate made by polishing is shown. The carrier used was an endless belt made of stainless steel having a hole (pocket) for holding a substrate and having a thickness of 0.5 mm and a width of 150 mm. The polishing conditions were such that a pad (outside diameter φ585 mm, inside diameter φ40 mm) which was generally commercially available for polishing aluminum was used as the pad, and the rotation speed was 50 rpm, and the opposing pads were rotated in opposite directions. The control of the cut amount of the pad to the aluminum alloy substrate is as follows:
This was performed with a pressing force (pressure) against the substrate. The slurry used was also mixed with a commercially available polishing liquid for aluminum containing abrasive grains having an average particle diameter of 1.6 μm, and the total flow rate of the slurry supplied to each pad was 40 ml / min.

Although continuous polishing was performed under the above conditions, when the cleaning mechanism 11 shown in FIG. 2 was used, all (300) aluminum alloy substrates subjected to polishing had a surface roughness It was maintained at a level of 100 to 130 ° Ra. In this example, despite the use of relatively large abrasive grains of 1.6 μm, a surface roughness of 130 ° Ra or less was obtained. As finer abrasive grains were used,
A smaller surface roughness is obtained. On the other hand, for comparison,
Polishing was performed under the same conditions without using the cleaning mechanism 11 of FIG. As a result, in several aluminum alloy substrates after the start of processing, the surface roughness was 100 to 130 ° Ra.
However, when the carrier has traveled one or more rounds and processed after 5 minutes (100 sheets),
The surface roughness of the aluminum alloy substrate is 130-260Å
Ra sometimes increased, and the number of scratches that could be visually confirmed also increased. This is because, as described above, since the carrier is used in a circulating manner, the adhered slurry is deposited on the carrier and adversely affects the polishing process. Therefore, the continuity of the polishing process is guaranteed,
It can be seen that it is preferable to wash the carrier in order to improve the yield.

Example 2 A JIS 5086-based aluminum alloy for magnetic disks was used under the same conditions as in Example 1 by using a polishing apparatus having a disc-shaped carrier shown in FIG. An example in which an alloy substrate is continuously polished is shown. When the cleaning mechanism 11 of FIG. 6 is used, all the processed (30
0) Aluminum alloy substrate has a surface roughness of 100 to 1
It was maintained at a level of 30 Ra. On the other hand, for comparison, polishing was performed under the same conditions without using the cleaning mechanism 11 of FIG.
When the aluminum alloy substrate has been run for at least 3 minutes (100 sheets) and has been processed until the elapse of 3 minutes
In some cases, 0ÅRa was large, and the number of scratches that could be visually confirmed also increased.

In Examples 1 and 2, the degree of surface roughness is slightly different even if a buff or a nonwoven fabric, a polishing cloth such as a polyester film substrate with a nonwoven fabric attached thereto, or a polishing paper is used instead of the pad. However, the same effect can be obtained depending on whether or not the carrier is washed.

[Embodiment 3] Next, an example in which a double-headed grinding method using an elastic grindstone is used as a pre-processing of a polishing method will be described. As the apparatus, an apparatus shown in FIG. 7 that combines the double-sided grinding method and the polishing method and performs the processing continuously in one line was used. In this case, the double-sided grinding conditions were as follows: GC # 3000, outer diameter φ585 mm,
Using a disk-shaped PVA grinding wheel with an inner diameter of φ40 mm, the rotation speed of the grinding wheel is 800 rpm, and a total of 3
The depth of cut was controlled by NC so as to remove 0 μm. Then, a water-soluble grinding fluid was continuously supplied to the processing surface from the center hole of the PVA grinding wheel rotating in the opposite direction. In addition, the carrier shown in FIG.
(B) a workpiece rotation braking means (using a coil spring 4a having a spring constant of 3 N / m;
b was pressed against the aluminum substrate W at 0.1 N) to perform grinding. The cleaning of the carrier is performed by a cleaning mechanism 1 provided on the downstream side of the polishing apparatus 10 shown in FIG.
Among them, the rotating brush 13 was not used because the work piece might be damaged, and only the washing water (supply nozzle 12) was used. Polishing conditions were the same as those in Example 1, and a JIS 5086-based aluminum alloy substrate for a magnetic disk was continuously polished.

Under the above conditions, first, for comparison, 30 μm was obtained by polishing only, without using double-headed grinding.
However, the pad was burned due to overload, and could not be processed. Therefore, it can be seen that in the polishing method of the present invention, when the removal amount (processing amount) of the finishing processing is large, it is better to insert a pre-processing such as double-sided grinding.

Further, for comparison, a processing with a removal amount of 30 μm was performed only by double-head grinding without using polishing. As a result, the removal amount was 30 μm in total on both sides of the workpiece.
Although a removal amount of m could be obtained, the surface roughness of the workpiece could only be as high as about 150 to 180 ° Ra.

On the other hand, under the above-mentioned conditions, the polishing example of the present invention using the double-headed grinding method as a pre-processing of the polishing method was carried out. As a result, all 800 aluminum alloy substrates continuously processed were obtained. Was able to obtain a removal amount of 30 μm in total on both surfaces of the workpiece, and the surface roughness was maintained at a level of 100 to 130 ° Ra. Therefore, it can be seen that when combined with the double-sided grinding, there is a synergistic effect that the surface roughness can be reduced and the removal amount can be increased.

Further, in any of the polishing examples of the present invention in which this double-head grinding is used, the work rotation braking means 24 shown in FIG. There were no grinding marks in different directions on the surface of the alloy substrate, and no damage on the end face of the workpiece.

[0060]

As described above, according to the polishing processing method of the present invention, the processing steps can be continued while maintaining the performance of the polishing processing method capable of polishing with less surface roughness with higher accuracy. be able to. Moreover, the surface accuracy of the workpiece can be maintained even when the number of processed workpieces is increased or when the workpiece is continuously operated for a long time. Therefore, it is possible to greatly contribute to improvement of productivity such as automation of finishing of a workpiece corresponding to required quality, and automation of a production system in which processes before and after finishing are integrated.

[Brief description of the drawings]

FIGS. 1A and 1B are explanatory views showing the principle of a polishing method according to the present invention and showing a state in which a workpiece is continuously passed between pads to perform a polishing process. FIG.

FIG. 2 is an explanatory view showing an embodiment of a belt-type carrier type apparatus used in the polishing method of the present invention.

FIG. 3 is an explanatory view showing another embodiment of a belt-type carrier type device used in the polishing method of the present invention.

FIG. 4 is an explanatory view showing another embodiment of a belt-type carrier type apparatus used in the polishing method of the present invention.

FIG. 5 is an explanatory view showing another embodiment of a belt type carrier type apparatus used in the polishing method of the present invention.

FIG. 6 is an explanatory view showing an embodiment of a disc-shaped carrier type device used in the polishing method of the present invention.

FIG. 7 is an explanatory view showing another embodiment of the polishing method of the present invention and showing an outline of an apparatus for performing double-disc grinding before polishing.

FIG. 8 is an explanatory view showing an outline of a double-head grinding apparatus used in the polishing method of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Carrier 2, 3 ... Pad 4 ... Slurry supply port 5 ... Slurry 6 ... Carrier pocket part 7 ... Plate 8 ... Loader 9 ... Unloader 10 ... Polishing apparatus 11 ... Cleaning mechanism 12 ... Cleaning water supply nozzle 13 ... Rotation Brush 14 Carrier 15, 16 Carrier driving means 20 Double-head grinding machine 21 Elastic grindstone rotation drive shaft 22, 23 Elastic grindstone 24 Workpiece rotation braking means W Disc-shaped workpiece

Continued on the front page (72) Inventor Hidetaka Yamaguchi 1-5-5 Takatsukadai, Nishi-ku, Kobe City Inside Kobe Steel Research Institute, Kobe Steel Co., Ltd. (72) Inventor Nobuhiro Hara 1-5-5, Takatsukadai, Nishi-ku, Kobe City No.Kobe Steel Works, Kobe Research Institute

Claims (6)

[Claims] 1. A slurry containing loose abrasive grains is supplied to the surface of a pad while continuously passing a plurality of carriers holding a plurality of flat workpieces at predetermined intervals between pads rotating opposite to each other. A polishing method, wherein each pad is pressed against the surface of a plate-shaped workpiece, and polishing of both parallel surfaces of the plate-shaped workpiece is performed simultaneously and continuously. 2. The method according to claim 1, wherein the carrier is an endless carrier that is circulated and used, and the carrier is washed and attached to the carrier before and / or after the endless carrier is passed between the pads. The polishing method according to claim 1, wherein the slurry is removed. 3. An elastic grindstone rotating opposite to the pad is disposed on the upstream side of the pad and on the traveling path of the carrier.
2. A double-head grinding process for continuously passing a plate-like workpiece held by the carrier between the elastic whetstones and simultaneously and continuously grinding both parallel surfaces of the plate-like workpiece.
Or the polishing method according to 2. 4. The polishing method according to claim 3, wherein the elastic grindstone is a PVA grindstone. 5. The polishing method according to claim 1, wherein the flat workpiece is aluminum. 6. The polishing method according to claim 5, wherein the aluminum is an aluminum substrate for a magnetic disk.