JPH02185374A - Synthetic grindstone - Google Patents

Abstract

PURPOSE:To cause no crack even if inputting at winter time, by giving a polyhydric alcohol at 1-5% in wt.% to the structure consisting of the mixing body of a specified matrix and the abrasive grain into particle existing by relatively connecting in the matrix and forming a continuous state actually. CONSTITUTION:A grindstone 1 is input under water, left for more than 12 hours, made in a completely wet state and stabilized by expanding about 2% max. In such case, a polyhydric alcohol acts as a penetrant because of being sticked, no distortion due to expansion is caused because of water being penetrated into the internal part rapidly and so crack is generated. Then, when the polishing of an aluminum disk is performed by utilizing this grindstone 1, it is filled up uniformly and compactly in the matrix resin having excellent water resistance and abrasive grain holding power, the abrasive grain fine particle connected each other shows a sharp sharpness, the abrasive grain particle is subjected to self-reproducing and cloggings are reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is a metal plate having a flat surface, such as a soft metal such as an aluminum alloy master disk (hereinafter referred to as an aluminum disk) that is a material for a magnetic disk base. It relates to a synthetic whetstone used for surface grinding and polishing, that is, polishing.

(Prior art) Conventionally, a relatively soft metal plate with a flat surface,
For example, surface polishing of aluminum disks, etc. can be done by machining using a precision lathe, so-called lapping using a slurry of fine powder such as silicon carbide, or processing using a synthetic grindstone such as a resinoid grindstone or a urethane grindstone. was common.

However, machining using precision lathes, etc. has different finishing accuracy and work efficiency depending on the skill level of the worker, and is generally poor in workability. The efficiency was noticeably low.

In addition, in the case of lapping processing using a slurry of fine abrasive particles such as silicon carbide, it is economically disadvantageous due to the large amount of slurry lost and used, and it also contaminates the surrounding working environment and workers, and furthermore, There is a problem in that processing high concentration waste liquid requires a lot of effort and cost.

In place of the lapping method using such a fine abrasive powder slurry, processing using a synthetic grindstone is rapidly becoming popular in recent years. However, synthetic whetstones, such as vitrified or resinoid hard whetstones, have insufficient polishing performance and cannot obtain sufficient finishing precision, lack search power, or cause undesirable phenomena such as clogging. However, there were problems such as inability to obtain a certain level of performance with high efficiency. In other words, when polishing flat surfaces, especially aluminum disks, etc., which require both flatness and surface precision, the surface of the object to be polished and the surface of the abrasive material are brought into contact with each other. It is necessary to advance the
For example, when using a resinoid-based or urethane-based synthetic whetstone with an independent pore structure, polishing debris, fallen abrasive grains, etc. due to the polishing action can easily enter the pores, causing clogging, which may affect the sustainability of the polishing effect. This results in chipping and frequent dressing (surface renewal) work.

On the other hand, those using polyvinyl acetal resin with continuous pores as a bonding material are easy to discharge polishing debris, fallen abrasive grains, etc. to the outside of the pores, and are less likely to cause clogging, making them excellent synthetic grindstones. Although it is generally known, it has relatively poor water resistance and is not suitable for such precision polishing applications.

In addition, products containing a cured thermosetting resin for the purpose of imparting water resistance are also available in Japanese Patent Publications No. 3B-1898 and No. 83-
It was proposed in various publications such as No. 8762, and is known as a water-resistant synthetic whetstone. In particular, in the latter invention, by changing the blending ratio of the thermosetting resin, an abrasive material with properties ranging from elastic to rigid can be obtained.
In particular, fine-grained whetstones were said to be useful for polishing soft, hard, and difficult-to-cut materials, but their grinding power was still insufficient, and they were particularly useful for polishing soft metal plates with flat surfaces. It was not suitable for flat surface polishing of aluminum disks, etc.

Furthermore, it compensates for the lack of chemical resistance and anti-pressure of polyvinyl acetal grinding wheels, and also serves as an adhesion for abrasive materials.

In order to increase the bonding force, a method of adding silicic acid gel to the matrix has been proposed in Japanese Patent Publication No. 5B-22443, but conventional synthetic grindstones manufactured by this method also have the same effect on the precision of soft metal plates. It could not be said that it was suitable for polishing.

In order to solve these problems,
Publication No. 480 proposes a synthetic whetstone in which the relationship between the surface hardness and abrasive grain count of a polyvinyl acetal-based whetstone is limited, and silicic acid gel is added to the matrix. It simultaneously satisfies excellent flatness and high surface precision for surface polishing. This synthetic whetstone is usually placed in water before being installed in a polishing machine, left to stand for 12 hours or more, allowed to reach a completely wet state, swelled by a maximum of 2%, and stabilized before being disposed of. However, when this synthetic whetstone is put into water during the winter,
There was a problem in that before the water penetrated into the inside of the whetstone, the whetstone would crack due to distortion due to swelling, causing the whetstone to break. Therefore, in the winter, it is necessary to store the whetstone at room temperature and then put it into water before use, making it impossible to use the whetstone immediately, and an improvement has been desired.

(Problems to be Solved by the Invention) The present inventors have completed the present invention as a result of intensive research in view of the above-mentioned technical current situation and problems. This is applied to soft metal plates finished to satisfy both excellent flatness and high surface precision, especially aluminum disks, and especially annular disks made of special aluminum alloys used for extremely precise applications. To provide a synthetic whetstone that can be used and does not crack even when put into water in winter.

(Means for Solving the Problems) The above object is to provide a structure having a three-dimensional network structure with continuous fine pores, which structure is formed by curing polyvinyl acetal resin and at least one thermosetting resin. A structure consisting of a matrix made of a homogeneous mixture of amorphous material and silicate, and a mixture of abrasive fine particles that are interconnected and exist in a substantially continuous state in the matrix,
This can be achieved by using a synthetic grindstone characterized by applying 1 to 5% by weight of polyhydric alcohol, its derivative, or its polymer.

The hardened body forming a fine three-dimensional network structure of the grinding wheel of the present invention has a completely different structure from the closed cell structure of resinoid-based and l/tan-based artificial grinding wheels, and there are no closed cells and three-dimensional branches are formed in the voids. It has a structure that looks like it has been stretched out, and the pores are infinitely connected. Therefore, the abrasive grains and polishing layer that result from polishing work are easily discharged from the system through these gaps (and even if they are captured, they are deposited in the air bubbles, as seen in other closed-cell whetstones). , it is difficult to cause undesirable phenomena such as clogging.In the case of a closed cell structure, the polishing effect lacks sustainability due to clogging, and frequent dressing operations (surface renewal) are required.

The above-mentioned effects can be sufficiently obtained within the range of average pore diameter of 10 to 100 μm; below this range, the pores are too dense and phenomena such as clogging tend to occur. Moreover, if it exceeds this range, the structure will be too rough and there will be some difficulty in terms of uniformity of physical properties.

Further, the porosity is preferably in the range of 80 to 8% by volume. If it is less than 60% by volume, closed cells will be present, and if it exceeds 88% by volume, the strength will be somewhat insufficient.

A synthetic whetstone using a hardened polyvinyl acecool resin, a thermosetting resin, and an amorphous silicate as a binder for abrasive grains is known from Japanese Patent Application Laid-open No. 81-192480. The whetstone is water resistant because it contains a hardened thermosetting resin, and because it is also made with amorphous silicate, it has extremely favorable grinding power as a whetstone for polishing soft metals. Less wear and tear, and
This provides performance that makes it difficult to cause undesirable phenomena such as clogging. The toughness (stickiness) characteristic of polyvinyl acetal synthetic grinding wheels can be reduced by using a hardened thermosetting resin and an amorphous silicate together with polyvinyl acetal resin as described above as a matrix which is a binding material. This results in a synthetic whetstone having appropriate brittleness, and in particular, silicate amorphous has the excellent effect of imparting appropriate brittleness to the whetstone and improving its grinding power.

The thermosetting resin referred to in the present invention includes melane-based resin,
Examples include phenolic resins, urea resins, thermosetting urethane resins, and epoxy resins, but melamine resins and phenol resins are usually used.

In the present invention, the amorphous silicate refers to a gel-like substance produced by the action of acid on various silicates made of silicon dioxide and various bases. In the case of Na2O x8i01-
It is represented by the chemical formula yHlo, and Na1O
It is preferable to use those having a molar ratio of /8i0t of 2 and 4. In this case, the general formula of the gel-like substance is an inorganic polymer represented by intermolecular crosslinking to form an amorphous three-dimensional compound. In addition to this, aluminum hydroxide or the like may be used as the base.

The above-mentioned binder matrix plays the role of effectively holding the abrasive fine particles that are the main material of polishing, and during polishing work, one abrasive grain polishes the surface and is eliminated from the system. At the same time, new abrasive grains are self-generated and the polishing process continues.In other words, the grindstone performs polishing while wearing itself, but by using the silicate amorphous material mentioned above, the matrix itself also has a slight grinding force. The grinding force can be significantly improved, and at the same time, the wear of the grindstone itself can be reduced.

In addition, the abrasive fine particles referred to in the present invention include diamond,
Grinding abrasive materials such as boron nitride, silicon carbide, fused alumina, garnet, emery, cerium oxide, chromium oxide, etc., consisting of compounds or single substances with grinding power,
This refers to abrasives classified by an appropriate method to the particle size specified in JI8 standard Re O01, and is a cemented carbide ceramic abrasive selected from the group consisting of silicon carbide, fused aluminum, chromium oxide, and cerium oxide. It is desirable to select at least one type of grain.

Furthermore, the key point of the present invention is the coordination and distribution state of abrasive grains having polishing performance. In other words, in this type of synthetic whetstone, the abrasive grains existing on the polishing surface are rubbed off, fall off, and are discharged from the system repeatedly, and the whetstone reduces its own thickness while increasing the surface of the object to be polished. However, if the ratio of abrasive grains is small, each abrasive grain will exist independently, and after that abrasive grain falls off, from a microscopic perspective, only the binder will remain. Scrub the surface with. In other words, since the rubbing is performed in areas with low abrasive force, the sharpness (grinding force) is poor. Especially when the purpose is to polish the surface of a soft metal such as an aluminum disk, as in the present invention,
Such a phenomenon is undesirable and tends to lead to problems such as surface unevenness and polishing unevenness.

In the present invention, in order to avoid such undesirable phenomena, individual abrasive grains do not exist independently in the matrix, but are interconnected with adjacent abrasive grains, forming a substantially continuous state. It needs to be distributed. The state of such abrasive grains is such that the matrix of the grinding wheel has a continuous pore structure with an average pore diameter of 10 to 100 μm, which is uniformly connected in three dimensions with a high porosity of 60 to 86% by volume,
This is due to the fact that a sufficient amount of abrasive grains of appropriate particle size are arranged in the fine skeleton of such a matrix, so to speak, and uniformly distributed. Also,
To ensure such coordination and distribution, the preferred abrasive grain size is at least 800, and the content is 25% by weight or more of the weight of the mixture, more preferably 60% by weight or more of the weight of the mixture. Further, it is preferable that the lower the abrasive grain count, that is, the larger the diameter of the abrasive grains, the higher the hardness.

The polyhydric alcohol applied to the structure described above is added as a water penetrating agent, and water quickly penetrates into the structure, preventing distortion due to swelling and preventing cracks. It is something.

Here, polyhydric alcohol refers to polyhydric alcohol or
It refers to its derivatives or its polymers,
Usually glycerin or glycols.

Petriol (for example, trade name "Clareisobrene Chemical"), ethanolamine, etc. are used. Among these, those that are nonvolatile (having extremely low vapor pressure), have low toxicity, and are highly hygroscopic are particularly preferred.

The grindstone according to the present invention is manufactured by the following method.

That is, the average degree of polymerization is 500 to 200G, wt [8G
An aqueous solution is prepared by mixing mol% or more of polyvinyl alcohol, one or more of its derivatives or modified products, and an aqueous solution or non-aqueous solution of a precursor consisting of a thermosetting resin monomer, oligomer or polymer, etc. An emulsion, etc., and an aqueous solution or colloid of silicate are added and stirred uniformly, and then abrasive grains, aldehydes as a crosslinking agent, acids as a catalyst, starch as a pore forming agent, etc. are added to form a uniform viscous slurry. is made of W4 and cast into a predetermined mold. Thereafter, the product is reacted and solidified in a frying bath or other bath at a temperature of 40 to 100° C. day and night, and then taken out and washed with water to remove excess aldehydes, acids, and pore forming agents. The intermediate thus obtained has the shape of a grindstone, but the resin has not undergone a curing reaction and its performance is insufficient.

Therefore, it is necessary to heat this intermediate at a temperature of about 100°C to evaporate the moisture, dry it, and then perform a heat treatment (curing) to cure the resin. It differs slightly depending on the type and type. Generally 10
The curing reaction is almost completed by curing at 0 to 260°C for 20 to 100 hours.

If the curing is insufficient, the toughness will be greatly affected, and if the curing conditions are harsh and the curing progresses too much, thermal decomposition will occur at the same time, which is likely to cause undesirable phenomena, so conditions must be selected carefully.

In order to avoid rapid temperature rise during curing, it is also effective to raise the temperature in stages or to perform it in an inert gas atmosphere to suppress local oxidation and deterioration.

As mentioned above, resins other than polyvinyl alcohol may be mixed (bleached) at the stage of the reaction stock solution, or may be cured after the intermediate is impregnated with the liquid precursor after the reaction is completed. When two or more resins are used together, a method may be used in which one resin is premixed and the other resin is post-treated, and the method is not particularly limited. Furthermore, it is also effective to use a catalyst to promote thermal curing.

The liquid resin can be an aqueous solution, a solution dissolved in an organic solvent, an emulsion, or a resin stock solution.
From the viewpoint of workability and ease of controlling the mixing ratio,
The method using an aqueous solution is most preferred.

Methods for applying polyhydric alcohol to the cured product thus obtained include a coating method, a spray method, a liquid supply roll coating method, and the like. Then, a synthetic grindstone can be obtained by drying the cured product to which polyhydric alcohol is attached at a temperature of 40'C to 80C.

(Function) After the grindstone obtained as described above is molded into a desired shape, it is placed in water and left to stand for 12 hours or more to reach a completely wet state and swell by a maximum of about 2%. After stabilization, it is used for surface polishing of soft metals, but especially when used for extremely precise purposes such as surface polishing of special aluminum alloy annular disks such as aluminum disks, the thickness before and after polishing, that is, the amount of grinding. is highly accurate (defined, flatness,
Since the variation in thickness is extremely suppressed, it cannot be applied to general polishing equipment, but is preferably used by being attached to extremely precise equipment, such as a double-sided lapping polisher. Here, a double-sided lapping type polishing machine is equipped with circular or ring-shaped metal surface plates on both the upper and lower surfaces, and one or more objects to be polished are sandwiched between them and crimped, and both the upper and lower surface plates are rotated in opposite directions. When applying the grindstone of the present invention, it is first placed in water and left for at least 12 hours to completely wet the surface of the object to be polished. This is achieved by allowing the material to swell by a maximum of 2% and stabilize. At that time, since polyhydric alcohol (containing conductors and polymers) is attached, the polyhydric alcohol acts as a penetrant and water quickly penetrates into the interior, so distortion due to swelling does not occur, and therefore No cracks will occur.

Next, the grindstone is attached to both surface plates so that it forms a uniform surface. During operation, polishing is performed by flowing an appropriate amount of a polishing aid liquid to wet the polishing surface, but the liquid used here, the so-called polishing liquid, is water,
These include water containing some kind of surfactant, or organic solvents.

Thus, when the grinding wheel of the present invention 1ζ is installed in a double-sided lapping type polishing machine to polish, for example, an aluminum disk, the grindstone is evenly and densely impregnated into the matrix resin, which has excellent water resistance and abrasive grain retention. The fine particles of abrasive grains connected to each other, together with the surface hardness of the grinding wheel derived from the appropriate hardness, elasticity, and brittleness of the abrasive grain count and matrix, exhibit sharp cutting ability, that is, abrasive power, and the abrasive grains Even if the particles fall off sequentially due to the abrasive action of ζ, new abrasive grains connected behind appear on the surface, and the abrasive surface is immediately renewed and regenerated, and the abrasive debris and fallen abrasive grains are discharged from continuous fine pores. Because it is easy to remove, it is difficult to cause clogging, so high polishing power is maintained for a long period of time. In addition, due to the above-mentioned special coordination and distribution state of the fine abrasive grains of the grinding wheel of the present invention, during grinding work,
The abrasive grains contact and rub against each other over the entire flat surface of the object to be polished, without causing any rubbing phenomenon caused only by the matrix resin, and a uniform polishing action is always performed. Therefore, the grinding wheel of the present invention can polish a soft metal plate having a flat surface without polishing unevenness.
It efficiently provides high smoothness and excellent finished surface accuracy.

(Example) Embodiments of the present invention will be described below with reference to Examples.

The polishing apparatus, measuring equipment, object to be polished, etc. used in this example are as follows.

・Polishing device: Double-sided grinder manufactured by Speed FAM (Model 8FDL 9B-588G) ・Surface roughness meter: Surface roughness meter manufactured by Tokyo Seimitsu Co., Ltd. (Model:
Surfcom 5siA) - Polishing material: An annular plate made of aluminum alloy as described in JI8-Standard Mumuro 086. The polishing conditions and measurement conditions are as follows.

・Polishing conditions: ・Pressure 100 fl/Cm" ・Polishing time...5 minutes/batch ・Upper surface plate rotation speed...20 R/M (counterclockwise) ・Lower...a OR/M (clockwise) )・Carrier l...t Oa/M (clockwise)・Water supply rate...51/min・Surface accuracy measurement conditions (WCM)・Cutoff value...5.8mm or less・Measurement length... 80 mm Note that Ra * Rmax e WOM here indicates the parameter of the following equation.

R, ... center line average roughness f (x) indicates the roughness curve.

Rmax ... Maximum height Rmax = Pmax - Vmin PmjaX ... Maximum peak height vm in the roughness curve
ln # # Maximum valley depth WOM・
... 3-wave maximum swell WOM = Pmax Vmin PmaX ... Maximum mountain height in 3-wave swell curve Vmin ... # l R
No. 800 silicon carbide powder was selected as the Otani depth abrasive grain. No. 800 has an average particle size of 18 to 22 μm. Completely saponified polyvinyl alcohol with a degree of polymerization of 1700 was made into an aqueous solution, and a predetermined amount of water-soluble phenol resin PR-961 manufactured by Jumin Durez was added to the solution, as well as sulfuric acid as a catalyst, formaldehyde as a crosslinking agent, and formaldehyde as a pore-forming agent. After adding cornstarch and a predetermined amount of a silicate aqueous solution containing silicon dioxide and soda ash,
A uniform slurry liquid was prepared by mixing with the abrasive grains described above. This slurry liquid was cast into a predetermined mold, and reacted and solidified at 60° C. overnight. Thereafter, it was washed with water to remove excess acid, formaldehyde, cornstarch, etc., and dried to obtain an intermediate for a synthetic grindstone. This was heat-treated at a temperature of 130° C. for about 60 hours to obtain the desired grindstone. In addition, an aqueous solution of 8M-700 manufactured by Showa Kobunshi ■ was prepared as an aqueous melamine resin, and the intermediate was impregnated into this, squeezed to a predetermined amount, dried, and heat-treated at a temperature of 130°C for about 50 hours. I did this and got a structure.

The structure thus obtained has a thickness of 5 as shown in FIG.
Cut and mold into a 9 mm approximately fan-shaped shape (1), and add glycerin (DG manufactured by Daiichi Kogyo Seiyaku ■) with a pure concentration of 6.10.
, 15 wt% aqueous solution was applied by spraying, and 50%
It was dried at ~80°C to obtain a synthetic whetstone of an example of the present invention.

The composition of the grindstone used in this example is shown in Table 1.

After the synthetic whetstone thus obtained was left in the air at 14°C for 24 hours, the bottom of the whetstone was immersed in water at 20°C, the time until the water penetrated to the top of the whetstone was measured, and the condition of the grinding surface was inspected. did.

Next, this synthetic grindstone was joined to a metal mounting plate (2), and attached to the upper and lower lapping machines of the polishing device using bolts. The material to be polished was fixed using a carrier, and polished under predetermined conditions of the polishing device. Water was used as the polishing liquid (coolant), and after polishing for a predetermined period of time, the surface shape of the polished material was inspected.

The results are shown in Table 1.

(Leaving space below) -...None No. +...Slightly present Table ++...Present As is clear from Table 1, the synthetic whetstone of the present invention allows water to penetrate immediately even when it is placed in water. Therefore, no cracks occur. It also has appropriate grinding power and shows good results in terms of surface precision. RmaX is Ra
It shows a value of approximately 11, indicating that there are few scratches and a good finish.

(Effects of the Invention) As detailed above, the synthetic whetstone according to the present invention does not require storing the whetstone at room temperature (usage atmosphere) during the winter and then putting it into water, and it can be used immediately when needed, resulting in improved workability. will improve.

In addition, the synthetic whetstone according to the present invention has made it possible to efficiently and economically obtain soft metal plates, such as aluminum disks, which have both excellent flatness and surface precision. It will be able to fully cope with the quality improvement and rapid increase in demand for high-precision finished aluminum disks as information storage media due to the development of the equipment industry, etc., and the increase in polishing work efficiency will make it possible to reduce production processing costs. The contribution to industry is enormous.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a lapping machine of a lapping type polishing machine for explaining how the grindstone of the present invention is used. (1)...Whetstone, (2)...Mounting plate, (5)...
Wrapping board. Diagram

Claims (1)

[Claims] (1) A structure having a three-dimensional network structure with continuous fine pores, the structure being a homogeneous mixture of a polyvinyl acetal resin, a cured product of at least one thermosetting resin, and an amorphous silicate. A polyhydric alcohol, a derivative thereof, or a polymer thereof is added by weight to a structure consisting of a mixture of a matrix consisting of 1. A synthetic whetstone characterized by having a ratio of 1 to 5%.