JP7681702B2 - Elastic abrasive and its manufacturing method - Google Patents

Description

The present invention relates to an elastic abrasive material and a method for manufacturing the same that are effective for surface treatment of workpieces having complex surface shapes such as metal molds and drills, which are metal processed products.

Conventionally, proposed elastic abrasives include an abrasive in which a core made of gelatin is impregnated with water, causing multiple abrasive grains to adhere to the core by the adhesive force generated by the incorporation of water, and the core is then collided with the workpiece in a moisture-retaining, elastic state to polish its surface (Patent Document 1); an abrasive in which an artificial composition such as synthetic resin foam or rubber is used as a core and an abrasive powder layer is provided on the surface of this core using a non-hardening adhesive as a binder (Patent Document 2); and an abrasive in which abrasive grains are mixed and dispersed in a base material that is an elastic body with low resilience, thereby reducing the resilience modulus and preventing recoil upon collision with the processed surface (Patent Document 3).

When blast polishing workpieces with complex surface shapes, such as metal molds and drills, which are metal processed products, it is necessary to obtain a high polishing power capable of removing cutting marks and electric discharge machining marks, as well as to prevent a decrease in polishing power due to the abrasive falling off during the polishing process.

However, while the elastic abrasives generally available up to now are capable of producing semi-finishes and mirror finishes, they have limitations in removing cutting marks and electrical discharge machining marks that occur during the manufacture of metal dies, etc. As a result, the removal of cutting marks and electrical discharge machining marks from metal processed products such as metal dies and drills with complex surface shapes is currently carried out by hand grinding, which also poses problems with work efficiency.

Patent No. 3376334 Patent No. 3800610 Patent No. 4901184

The present invention aims to provide an elastic abrasive that has high abrasive power by improving the adhesion between the base material and the abrasive, preventing the abrasive from falling off, and solving the problem of a decrease in abrasive power, and is effective for surface treatments such as blast polishing of workpieces with complex surface shapes, and to provide a method for manufacturing the same.

In order to solve the above problem, the elastic abrasive of the present invention is characterized in that an abrasive is attached to an elastic base material using an adhesive, a heat-cured aggregate granule is formed, and then an abrasive is again attached to the aggregate granule using an adhesive and heat-cured (Claim 1).

The present invention is configured such that an abrasive material is attached to an elastic base material with an adhesive, which is then heated and hardened, and then an abrasive material is again attached to the abrasive material with an adhesive and heated and hardened. Therefore, during blast polishing, for example, the abrasive material is deformed to fit the shape of the workpiece and polished, and as the outer periphery is worn away, new granules appear from the inside, allowing the abrasive material to maintain a high polishing power for a long period of time.

One embodiment of the present invention is characterized in that the elastic base material is an elastomer, the adhesive is a solvent-based thermosetting resin, and the abrasive is alumina, silicon carbide, zirconia, CBN, or diamond (Claim 2).

The elastic base material is a carrier for the abrasive material. In order to avoid causing deep scratches in the workpiece, the base material must be elastic. It is preferable that the elastic base material be the above-mentioned elastomer.

The shape can be circular or any other shape, and the surface condition can be smooth, but it is more preferable for it to have some unevenness. Having unevenness increases the surface area, which allows for a larger amount of abrasive to be attached, resulting in a high abrasive power.

The adhesive holds the abrasive. Examples of solvent-based thermosetting resins include urethane resin, epoxy resin, silicone resin, urea resin, and unsaturated polyester resin, with urethane resin being preferred. The lower the adhesive hardness, the more flexible it is, and a pencil hardness of B or less is preferred.

The pencil hardness is measured in accordance with JIS K 5600-5-4:1999 (scratch hardness pencil method) by pressing a pencil of known hardness against the coating to measure the hardness of the coating. Adhesives with a pencil hardness of 4B or less are more preferable. Adhesives with a pencil hardness of more than B may cause deep scratches in the workpiece.

The abrasive has an abrasive power. In order to obtain a high abrasive power, it is preferable that the average particle size is 20 to 100 μm (Claim 3). If the average particle size is less than 20 μm, it is difficult to obtain a high abrasive power to remove cutting marks or electric discharge machining marks, and if it is more than 100 μm, a decrease in abrasive power due to grain fall becomes an issue.

Abrasives include alumina, silicon carbide, zirconia, CBN, diamond, etc., but silicon carbide is preferred from the standpoint of abrasive performance and cost.

One embodiment of the present invention is characterized by the addition of an antistatic agent and a metal soap (Claim 4).

The addition of an antistatic agent improves the conductivity of the elastic abrasive. Examples of antistatic agents include carbon black, conductive polymers, and surfactants, with carbon black being preferred. The elastic abrasive that is struck against the workpiece during blast polishing becomes charged by static electricity generated upon impact. The accumulated static electricity then causes the elastic abrasive to adhere to the walls inside the blasting device. If the amount of this adhesion increases, circulation efficiency decreases, leading to reduced workability.

Conventionally, countermeasures have been taken such as humidification and periodic spraying of antistatic liquid, but these are time-consuming and lead to reduced workability. The objective of this invention is to provide an elastic abrasive that does not adhere to wall surfaces for long periods of time by adding an antistatic agent during the manufacturing process of the elastic abrasive.

The metal soap is added to prevent the elastic abrasives from agglomerating together. When the elastic abrasives hit the workpiece during blast polishing, they tend to agglomerate together due to the heat generated by the collision energy. When the elastic abrasives agglomerate together, problems occur such as clogging in the nozzle or the elastic abrasives remaining in the temporary storage tank and not being able to circulate.
An object of the present invention is to provide an elastic abrasive which does not aggregate for a long period of time by adding a metal soap during the production process of the elastic abrasive.

The method for producing an elastic abrasive of the present invention is characterized by the steps of mixing and stirring an elastic base material and an adhesive to form an adhesive layer around the elastic base material, mixing and stirring the elastic base material with the adhesive layer formed thereon and an abrasive to adhere the abrasive to the adhesive layer, heating and hardening to form an aggregate granule, and replacing the elastic base material with the aggregate granule, and repeating the above three steps (Claim 5).

According to the manufacturing method of the present invention, an abrasive material can be attached to an elastic base material with an adhesive, the resulting aggregate granules are heated and hardened, and then an abrasive material can be attached again with an adhesive and heated and hardened to provide the elastic abrasive material of the present invention.

One embodiment of the method for manufacturing an elastic abrasive of the present invention is characterized in that the elastic base material is an elastomer, the adhesive is a solvent-based thermosetting resin, and the abrasive is alumina, silicon carbide, zirconia, CBN, or diamond (Claim 6).

One embodiment of the method for manufacturing an elastic abrasive of the present invention is characterized in that the average particle diameter of the abrasive is 20 to 100 μm (claim 7).

One embodiment of the method for manufacturing an elastic abrasive of the present invention is characterized by the addition of an antistatic agent and a metal soap (claim 8).

According to the present invention, the adhesion between the base material and the abrasive is improved, the abrasive is prevented from falling off, and a high abrasive power is achieved by solving the problem of a decrease in abrasive power, making it suitable for the surface treatment of workpieces having complex surface shapes and also improving work efficiency.

1 is a schematic diagram showing the configuration of an elastic abrasive material of the present invention. 1 is a table showing test results of the polishing amounts of one-process products and two-process products. 13 is a comparative SEM photograph of a product of one process and a product of two processes. This is a comparison photograph of the workpiece before and after blasting. 1 is a comparative SEM photograph of an elastic abrasive material before and after blasting treatment.

<Structure of the present invention>
An embodiment of the present invention will be described below. Fig. 1 is a schematic diagram showing the structure of an elastic abrasive material of the present invention.

In Figure 1, a is an elastic base material, and b is an abrasive adhered to the elastic base material a with an adhesive. Also in the figure, 1 is an aggregate granule that has been previously heat-cured, and 2 is an elastic abrasive of the present invention to which an abrasive has been attached again with an adhesive and then heat-cured.

When the elastic abrasive 2 of the above configuration is used for blast polishing, etc., as it wears down from the outer periphery, new abrasive 1 appears from the inside, maintaining a high polishing power for a long period of time.

Next, the production method of the present invention will be described.
Elastic base material: Thermoplastic elastomer Adhesive: Solvent-based thermosetting urethane resin Abrasive: Silicon carbide Additive: Carbon black Additive: Metal soap <Manufacturing process>
A solvent-based thermosetting urethane adhesive containing a metal soap was prepared and mixed and stirred with an elastic base material to form the adhesive layer around the elastic base material (first step). Next, the elastic base material with the adhesive layer formed thereon, silicon carbide as an abrasive, and carbon black as an additive were added and mixed and stirred to attach the abrasive to the adhesive layer of the elastic base material (second step).
Next, the elastic base material to which the abrasive was attached was heated and cured to obtain an aggregate granule (third step).Furthermore, the elastic base material was replaced with the aggregate granule, and the above three steps were repeated (fourth step).

Details of the fourth step include a step of adding an adhesive to the aggregate granules and mixing and stirring them to form an adhesive layer around the aggregate granules, a step of adding an abrasive to the aggregate granules and mixing and stirring them to adhere the abrasive, and a step of heating and hardening the aggregate granules with the abrasive attached.

Next, the performance evaluation of the present invention will be described.
<Performance evaluation>
Fig. 2 is a test result table of the polishing amount of the one-step product and the two-step product. Fig. 2 shows that a high polishing power was obtained by performing the granulation process twice in the manufacturing method of the present invention.

In the figure, the one-process product is an elastic abrasive that has undergone steps 1 to 3 of the manufacturing process, and the two-process product is an elastic abrasive that has undergone steps 1 to 4 of the manufacturing process. The total amount of material used is the same for both the one-process product and the two-process product.

The test conditions were as follows: a blower blasting device (AB-1-LAP type) manufactured by Sankyo Rikagaku Co., Ltd. was used, the blower pressure when spraying the elastic abrasive was 40 kPa, the nozzle diameter was 10 mm, 300 g of elastic abrasive, and the elastic abrasive grain size was GC600. With the nozzle and workpiece fixed, the distance between the nozzle tip and the workpiece was 15 cm, and the spray angle was 60°, and spraying was performed for 90 minutes.

The target workpiece was S45C. The amount of polishing was calculated from the difference in the weight of the workpiece before and after polishing. As a result, it was found that the polishing power of the two-process product was approximately 1.9 times higher than that of the one-process product.

Figure 3 shows comparative SEM images of a one-process product and a two-process product. When observed, it can be seen that the abrasive is more embedded in the adhesive in the one-process product than in the two-process product. This is because in the one-process product, the amount of adhesive is greater relative to the amount of elastic base material, causing the adhesive to seep out onto the surface of the abrasive. As a result, there is a lot of aggregation of the elastic abrasives themselves, which also causes a decrease in yield. As the abrasive is embedded in the adhesive, its polishing function is reduced, resulting in the one-process product having a smaller polishing power than the two-process product.

Figure 4 shows a comparison photograph of the surface before and after blasting. In detail, blasting was performed on a workpiece made of high-speed steel (YXM-1) with an EDM finish, and the abrasive power and finished surface were evaluated.

The polishing test was carried out using a blower abrasive machine (AB-1-LAP type) manufactured by Sankyo Rikagaku Co., Ltd., with a blower pressure of 40 kPa when spraying the elastic abrasive, a nozzle diameter of 10 mm, approximately 1 kg of elastic abrasive, and elastic abrasive grain size GC220. The workpiece was held in the hand with the nozzle fixed, and spraying was carried out for 5 minutes at any spray distance and angle. A laser microscope manufactured by KEYENCE was used to evaluate the finished surface. As a result, it was confirmed that a surface roughness of Ra: 4.7 μm before processing could be smoothed down to Ra: 0.8 μm in a short time.

Figure 5 shows comparative SEM photographs of the elastic abrasive before and after blasting. This test was conducted to confirm the grain shedding performance of the elastic abrasive of the present invention. The test conditions were as follows: a blower blasting device (AB-1-LAP type) manufactured by Sankyo Rikagaku Co., Ltd. was used, the blower pressure when spraying the elastic abrasive was 40 kPa, the nozzle diameter was 10 mm, the elastic abrasive was approximately 1 kg, and the elastic abrasive grain size was GC600. With the nozzle and the workpiece fixed, the distance between the nozzle tip and the workpiece was 15 cm, and the spray angle was 60°, and spraying was performed for 10 hours. S45C was used as the target workpiece.

The surface condition of the elastic abrasive was observed using SEM photographs before and after the polishing test. As a result, it was confirmed that the surface condition of the elastic abrasive was almost the same before and after the polishing test.

The present invention makes it possible to effectively perform surface treatment of workpieces having complex surface shapes, and has great industrial applicability, such as eliminating the need for hand sharpening of cutting marks and electric discharge machining marks on metal workpieces such as metal dies and drills.

a Elastic base material b Abrasive 1 Granulated aggregate 2 Elastic abrasive

Claims (10)

a plurality of aggregate granules each including a plurality of elastic base materials made of a single material, an adhesive layer formed around each of the plurality of elastic base materials, and a plurality of abrasives attached to an outer surface of each of the plurality of elastic base materials via the adhesive layer;
A new adhesive layer formed around each of the plurality of aggregate granules;
and a plurality of new abrasives attached to the outer surfaces of the plurality of abrasive aggregates via the new adhesive layer, the plurality of abrasive aggregates being integrally present in a state in which they are bonded to each other,
The elastic abrasive is characterized in that the elastic abrasive is configured so that new aggregated granules appear from the inside as the outer periphery is worn away during blast polishing. The elastic abrasive material according to claim 1, characterized in that the elastic base material is an elastomer, the adhesive layer and the new adhesive layer are both solvent-based thermosetting resins, and the abrasive material is alumina, silicon carbide, zirconia, CBN, or diamond. The elastic abrasive material according to claim 1 or 2, characterized in that the average particle size of the abrasive material is 20 to 100 μm. The elastic abrasive material according to claim 1 or 2, further comprising an antistatic agent and a metal soap. 3. The elastic abrasive material according to claim 1, wherein both the adhesive layer and the new adhesive layer have a flexibility of B or less in pencil hardness as defined in JIS K5600-5-4:1999. mixing and stirring a plurality of elastic base materials made of a single material with an adhesive to form a first adhesive layer around each of the plurality of elastic base materials;
a step of mixing and stirring the plurality of elastic base materials on which the first adhesive layer is formed and a plurality of abrasives to adhere the plurality of abrasives to the first adhesive layer formed around each of the plurality of elastic base materials;
a step of heat-curing the first adhesive layer to form a plurality of aggregate granules;
a step of mixing and stirring the plurality of granules with new adhesive to form a second adhesive layer around each of the plurality of granules;
a step of mixing and stirring the plurality of abrasive aggregates on which the second adhesive layer has been formed and a plurality of new abrasive aggregates, thereby adhering the plurality of new abrasive aggregates to the second adhesive layer formed around each of the plurality of abrasive aggregates;
a step of obtaining an elastic abrasive material in which the plurality of granules are integrally present in a state of being adhered to each other by heating and curing the second adhesive layer;
A method for producing an elastic abrasive comprising the steps of:
The method for producing an elastic abrasive is characterized in that the elastic abrasive is configured so that new aggregate granules appear from the inside in the process of being worn away from the outer periphery during blast polishing. The method for producing an elastic abrasive material according to claim 6, characterized in that the elastic base material is an elastomer, the adhesive and the new adhesive are solvent-based thermosetting resins, and the abrasive material is alumina, silicon carbide, zirconia, CBN or diamond. The method for producing an elastic abrasive according to claim 6 or 7, characterized in that the average particle size of the abrasive is 20 to 100 μm. The method for producing an elastic abrasive according to claim 6 or 7, further comprising the addition of an antistatic agent and a metal soap. The method for producing an elastic abrasive according to claim 6 or 7, characterized in that both of the first adhesive layer and the second adhesive layer constituting the elastic abrasive have a flexibility of B or less on the pencil hardness scale as defined in JIS K5600-5-4:1999.

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