JP2011093046A - Projection material for blast work and blasting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection material for blast work and a blasting method by which a surface of a workpiece can be mirrored or smoothened in a very short period of time without generating a satin-finished-like unevenness on the surface of the workpiece comparing with conventional techniques such as polishing with a polishing paper or a polishing cloth. <P>SOLUTION: In the blasting method, the projection material is projected to the surface of the workpiece by a blasting apparatus, wherein the projection material is formed by bonding polishing particles one another, and the each polishing particle is formed with abrasive materials having a diameter of 0.1-300 μm supported on a surface of a thermoplastic resin particle having a diameter of 1-500 μm. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a projection material for reducing the surface roughness of a surface to be processed and making the surface to be processed as a mirror surface or a glossy surface in blasting in which a projection material is sprayed onto the surface to be processed.

Conventionally, as a polishing method for reducing the surface roughness of the surface to be processed and making the surface to be processed into a mirror surface or a glossy surface, polishing with polishing paper or polishing cloth, polishing with buff, lapping, etc. In addition, polishing by contact with rotating abrasive grains has been used. However, in any of the polishing methods, a considerable processing time is required until the processed surface is finished to a mirror surface or a glossy surface. Therefore, attempts have been made to reduce the processing time by applying blasting to the processing.

Blasting is a method of processing a surface to be processed by spraying a projection material such as ceramics, metal, or resin onto the surface to be processed. Although the processed surface can be processed in a short time, a satin-like unevenness is likely to be formed on the processed surface due to the collision of the projection material, which is not suitable for making the processed surface into a mirror or glossy surface.

In order to suppress the formation of textured irregularities and to make the surface to be processed mirror or glossy, for example, Patent Document 1 discloses a projection material in which gelatin is used as a core, and abrasive and water are contained therein. It has been proposed to use However, since the water in the projection material evaporates during blasting, a textured surface unevenness is formed on the surface to be processed, and therefore it is necessary to replenish the projection material with water regularly. Therefore, the blasting apparatus becomes complicated (for example, see Patent Document 2).

In Patent Document 3, it is proposed to use a projection material obtained by mixing 10 to 90% by mass of an abrasive with rubber or a thermoplastic elastomer. However, when the content of the abrasive is small, the life as a projection material is short due to, for example, clogging, and it is necessary to frequently replace it with a new one from a blasting apparatus, resulting in poor efficiency. On the other hand, when the content of the abrasive is large, for example, when it is 70% by mass or more, the abrasive is easily removed from the rubber or elastomer, and the new surface appears, so that the above-mentioned clogging does not occur and the projection is performed. Although it has a long life as a material and has a good polishing ability continuously, the abrasive material is relatively expensive, which increases the price of the projection material.

JP 2001-207160 A JP 2009-190108 A JP 2006-159402 A

The present invention has been made to solve the above-described problems, and suppresses the formation of matte-like irregularities on the processed surface, and the processed surface is mirror-finished or glossed. Therefore, it is possible to provide a low-cost projection material that does not require a special apparatus for maintaining the polishing ability and has a stable and stable polishing ability even when used for a long time.

In order to solve the above-mentioned problems, the invention according to claim 1 is composed of abrasive particles in which an abrasive material having a diameter of 0.1 to 300 μm is carried on the surface of particles of a thermoplastic resin having a diameter of 1 to 500 μm. The technical means that the abrasive particles are formed as a bonded body is used.

According to the invention described in claim 1, for example, as shown in FIG. 1, particles (abrasive particles 10) on which the abrasive material 12 is supported on the surface of the thermoplastic resin particles 11 are bonded to form a bonded body. The projection surface can be suitably used as a blasting material for making the surface to be processed a mirror surface or a glossy surface. In addition, the abrasive particles may contain not only abrasives but also substances necessary for production.

According to a second aspect of the present invention, in the blasting projection material according to the first aspect, a technical means is used in which the thermoplastic resin is soft polyvinyl chloride.

According to the second aspect of the present invention, in order not to form the textured unevenness on the surface to be processed due to the collision of the blasting projection material, it is necessary to be moderately soft. Polyvinyl chloride is an inexpensive material whose hardness can be adjusted by the amount of plasticizer added. The soft polyvinyl chloride of the present invention refers to a material containing 5% by mass or more of a plasticizer, and this is a blasting projection material having a hardness that does not form a textured unevenness on the surface to be processed during blasting. It can be used suitably. In addition, when projecting for blasting, a large amount of fine particles (projection material and dust of the workpiece cut by blasting) are scattered in the blasting chamber, and there is a risk of dust explosion. Polyvinyl chloride is known to be a flame retardant material, and by using it as a projection material, the risk of dust explosion can be reduced.

According to a third aspect of the invention, there is used a technical means in the blasting projection material according to the first or second aspect, wherein the diameter of the projection material is 0.01 to 3 mm.

According to invention of Claim 3, when the length of the said blast processing projection material is less than 0.01 mm, the cutting force for making a to-be-processed surface into a mirror surface or a smooth surface cannot be obtained sufficiently. And the projection amount at the time of projecting to a workpiece by a blast processing apparatus is not stabilized. In addition, when the thickness exceeds 3 mm, a textured surface unevenness is generated on the surface to be processed. Therefore, the formation of the textured surface unevenness on the surface to be processed due to the collision of the blasting projection material is suppressed, and the surface to be processed is mirror-finished or smooth The diameter of the blasting projection agent for surfaceization is preferably in the range of 0.01 to 3 mm. In addition, the projection material includes not only a substantially spherical shape but also an irregularly shaped object having a long side and a short side, such as a cylindrical shape. In the case of such a projection material, the diameter here refers to the length of the long side.

According to a fourth aspect of the present invention, there is used a technical means that the blasting projection material according to any one of the first to third aspects has a void inside the projection material.

According to the invention described in claim 4, for example, as shown in FIG. 2, since the gap W is provided inside the projection material 1, the bonding force between the abrasive particles is weak, and the projection material as a whole is moderately brittle. Turn into. Dust generated by blasting enters between the abrasive particles and / or between the abrasive materials to reduce the polishing ability (clogging), but when the projection material collides with the workpiece, some of the abrasive particles are By dropping off, a new surface of abrasive particles carried on the surface of the abrasive material always appears on the surface of the projection material, and the entire projection material can maintain the polishing power. In blasting, since the projection material colliding with the workpiece is circulated and used, it is possible to obtain a projection material that maintains a high polishing force for a long time in such use.

According to a fifth aspect of the present invention, in the blasting projection material according to any one of the first to fourth aspects, at least a part of the projection material has a gap having a communication structure. The technical means is used.

According to the fifth aspect of the present invention, as described above, the projection material has a high polishing force over a long period of time by having a gap inside the projection material. The shape of the voids is effective for both independent structures (independent structures) and continuous void structures (communication structure), but at least partly has a communication structure for blasting. At this time, the removal of the abrasive particles when the projection material collides with the object to be processed easily proceeds.

The invention according to claim 6 uses the technical means that in the blasting projection material according to claim 4, the proportion of the voids in the projection material is 70% by volume or less.

According to the invention of claim 6, as described above, by having voids inside the projection material, it always keeps a new surface of abrasive particles appearing on the surface of the projection material, but the proportion of voids exceeds 70% by volume. And, since the bond between the abrasive particles becomes too weak, and when the projection material collides with the workpiece, the whole or most of the projection material is decomposed (crushed) into abrasive particles, so the ratio of the voids in the projection material Needs to be 70% by mass or less. In addition, by appropriately selecting the void ratio in the range of 70% by volume or less according to the workpiece and the target surface roughness, the workpiece can be efficiently mirror-finished or smoothened. A blasting projection material can be obtained.

The invention according to claim 7 uses technical means in which the blasting projection material according to claim 4 or 5 is impregnated with a liquid serving as a polishing aid and sprayed onto the workpiece.

According to the seventh aspect of the present invention, for example, the appearance of a new surface of abrasive particles on the surface of the projection material is promoted, or fine powder enters (clogs) between abrasive materials or between abrasive particles and between abrasive materials. In order to maintain high polishing ability for a long time by preventing the occurrence of seizure of the workpiece due to polishing, to prevent the projection material and workpiece from being charged by blasting, or to eliminate static electricity Depending on the purpose, blasting can be performed using a projection material in which the gap is impregnated with a polishing aid. The polishing aid can be appropriately selected from water, an inorganic material, an organic material, or a mixture thereof according to the purpose of use and the material of the projection material and the workpiece. The impregnation here includes not only simply including a polishing aid in the projection material, but also includes holding the microcapsules containing the polishing aid inside the projection material.

According to the present invention, compared to conventional techniques such as polishing paper or polishing cloth, the surface of the workpiece can be mirror-finished or flattened without generating textured irregularities in a very short time. In addition, it is possible to obtain a blasting projection material capable of maintaining a high polishing power for a long time.

In particular, by selecting soft polyvinyl chloride as the thermoplastic resin, when performing blasting on the surface to be processed, it is possible to suppress the formation of satin-like irregularities and to provide a blasting projection material with low dust explosiveness. It can be obtained inexpensively.

Moreover, the projection material for blasting which has a high grinding | polishing capability over a long time can be obtained by having a 70 volume% or less space | gap inside a projection material.

Further, by impregnating the inside of the gap with a liquid as a polishing aid, various effects during blasting, for example, maintaining a high polishing ability for a long time, preventing charging of a projection material or a workpiece, Effects such as static elimination can be obtained, and efficient blasting can be performed.

It is a schematic diagram of the blasting projection material in the present invention. (A) is a general view of a projection material, (B) is a sectional view of abrasive particles. It is a schematic diagram of the cross section of the projection material for blasting in this invention. It is a flowchart for demonstrating embodiment in this invention. It is explanatory drawing of the transformation to the abrasive particle of embodiment in this invention. (A) is a schematic diagram, (B) is an enlarged view of abrasive particles. 5 is a schematic diagram of a blasting projection material used in Comparative Example 1. FIG.

An embodiment of the present invention will be described with reference to FIGS. In this embodiment, soft polyvinyl chloride is used as the thermoplastic resin, and green carborundum (SiC) is used as the abrasive.

First, polyvinyl chloride (PVC) polymer particles 51 as a thermoplastic resin raw material, a plasticizer mainly composed of a phthalate ester compound, calcium carbonate 55 as a forming aid for soft polyvinyl chloride, an abrasive The material 54 was mixed at a predetermined ratio at room temperature on a mass basis to obtain a mixture. The soft polyvinyl chloride in the present invention refers to a plasticizer content of 5% by mass or more of the entire soft polyvinyl chloride as described above. Although depending on the amount of abrasives supported and the proportion of voids in the bonded body described later, the plasticizer content can be particularly preferably used at 50 to 70% by mass with respect to the entire soft polyvinyl chloride. . In the present embodiment, the mixing ratio (PVC: plasticizer: calcium carbonate: abrasive) is set to 20: 30: 20: 30.

The mixture is put into an extrusion apparatus 20 set at a heating temperature of 200 ° C. The extrusion molding apparatus is composed of a cylinder 31 having a heating means 32 and a die 33 (a mold having a passage hole having a shape targeted for molding).

The mixture is heated by passing through a cylinder in an extruder. At this time, the PVC particles are slightly softened, and the plasticizer enters the particles to form soft polyvinyl chloride particles 52. On the other hand, most of the abrasive is not taken up to the center of the soft polyvinyl chloride particles and is carried near the outer periphery of the soft polyvinyl chloride particles. Further, most of the calcium carbonate as a forming aid is also carried on the outer periphery of the soft polyvinyl chloride particles. The particles thus formed become the abrasive particles 50. Further, the abrasive particles are softened by being continuously heated, and the abrasive particles are bonded to each other at a contact point to form a bonded body.

They pass through the die at the tip while being heated, are discharged out of the apparatus, and are cooled in the atmosphere. In this example, a thread-like molded body 40 having a diameter of about 1 mm was obtained.

The molded body was cut into a length of about 1 mm to obtain a blasting projection material.

As described above, the blasting projection material preferably has a void of 70% by volume or less. Although depending on the injection speed of the projection material in blasting and the material and shape of the workpiece, the range of 30 to 60% by volume is more preferable. Further, the shape of the gap is not particularly limited, but it is preferable that at least a part has a communication structure. In this embodiment, the projection material has a gap having a communication structure of about 35% by volume.

The projection material thus obtained was put into a pneumatic blasting apparatus. There are two types of pneumatic blast devices: a suction type (gravity type) and a pressurization type (direct pressure type). In this embodiment, the suction type will be described as an example.

The suction-type blasting apparatus includes a blasting chamber, a blasting nozzle, a compressed air supply device, a classification device, and a dust collecting device. By supplying compressed air to the blasting nozzle set in the blasting chamber with a compressed air supply device, negative pressure (suction force) is generated inside the nozzle. By injecting the projection material into this negative pressure flow, the projection material is mixed into the compressed air and becomes a mixed air current, which is ejected from the ejection port of the nozzle.

The nozzle is set at a predetermined distance from the processing surface and inclined at 45 ° with respect to the processing surface. The projecting material ejected from the nozzle outlet collides with the work surface at high speed, and the work surface is polished. At the same time, some of the abrasive particles fall off due to the collision with the surface to be processed.

The ejected projection material, the cut surface of the surface to be processed, and dust such as abrasive particles that have fallen off the projection material are transferred to a classifier. Therefore, the reusable projection material is transferred to the projection material hopper, and again injected into the nozzle. On the other hand, dust and non-reusable projection material are collected by a dust collector.

In order to process the entire surface to be processed, the projection material was sprayed for a predetermined time while moving the nozzle or the workpiece. After spraying for a predetermined time, the injection of the projection material is stopped, the workpiece is taken out from the blasting chamber, and the workpiece is cleaned by air blow, water washing, etc., and the mirror surface processing or gloss surface processing is completed.

(Example of change)
The raw material of the thermoplastic resin is not limited to this example. Depending on the material and shape of the workpiece, it can be appropriately selected from known materials such as polyethylene, polypropylene, and thermoplastic elastomer.

Further, the abrasive is not limited to this embodiment, and projection used in general blasting according to the material and shape of the workpiece, the target machining time, the surface roughness required for the workpiece surface, etc. Materials, abrasives used in general polishing methods, such as ceramics such as white alundum, glass and diamond, metals such as iron and stainless steel, calcium carbonates and sulfides It is possible to appropriately select from inorganic systems such as walnuts, plant systems such as walnuts and peaches, and the like.

Moreover, the manufacturing method of this projection material is not limited to a present Example, For example, you may obtain by grind | pulverizing after shape | molding to a comparatively big bulk, and you may shape | mold by another well-known method.

Further, by adjusting the heating temperature at the time of molding and the pressure for extruding the raw material, the voids inside the projection material can be adjusted, and naturally the voids can be eliminated. In this case, since the abrasive is present at the interface between the abrasive particles, the removal of the abrasive particles proceeds with the abrasive as a base point during blasting, and a new surface of the abrasive particles appears.

Moreover, the ratio and structure of the space | gap contained in this projection material can also be adjusted by mixing a foamable hollow particle etc. in the said mixture.

The blasting is not limited to the pneumatic method, and a known method such as a centrifugal method in which the projection material collides with the workpiece by rotating the impeller can be selected.

Further, the angle formed by the nozzle and the surface to be processed can be arbitrarily set within a range of 0 to 180 ° including vertical.

(Example)
In the above embodiment, ZEST 1300Z (manufactured by Shin-Daiichi PVC Co., Ltd.) is used for the polymer particles of polyvinyl chloride, Vinicizer 90 (manufactured by Kao Corporation) is used for the plasticizer, and NS # 400 (Nitto) is used for the forming aid. GC # 4000 (manufactured by Shinto Kogyo Co., Ltd.) was used as the abrasive. Using these as raw materials, the blast projection material obtained by the method of the above embodiment has a processed surface of φ40 mm using a blast processing apparatus MY-30 (manufactured by Shinto Kogyo Co., Ltd.), and has a hardness of It sprayed on the S55C heat treatment goods of HRC50-55 (JISG0202). The injection conditions were such that the injection pressure was 0.3 MPa, the distance between the nozzle and the processing surface was 100 mm, and the angle between the nozzle and the processing surface was 45 degrees.

The blasting process was defined as one cycle when the entire amount of the injected blasting material was projected toward the workpiece. In the blasting apparatus used, since the thrown projection material is circulated and used through a classifier instead of batch processing, the number of cycles is calculated using Equation 1.

After spraying a predetermined cycle onto a plate made of the same material as the workpiece (empty punching), the workpiece was put into a blasting chamber and blasted (Example 1). For each evaluation, a new workpiece was prepared and processed for evaluation.

Further, as shown in FIG. 5, a projection material 60 having a distribution with a diameter of 0.1 to 1 mm and in which the abrasive material 62 is distributed in the thermoplastic resin particles 61 is created, and blasting similar to that of the first embodiment is performed. (Comparative Example 1). Specifically, acrylic resin was used as the resin constituting the thermoplastic resin particles 61, and GC # 4000 (manufactured by Shinto Kogyo Co., Ltd.) was used as the abrasive 62. The acrylic resin and the abrasive were mixed at a mass ratio of 7: 3, and were prepared by heating and mixing them.

The obtained processed surface was evaluated for surface roughness and gloss. The surface roughness was measured with a surface roughness meter SURFCOM 1500SD (manufactured by Tokyo Seimitsu Co., Ltd.) for arithmetic average roughness Ra, maximum height Ry, and ten-point average roughness Rz (JIS B0601-1994). The glossiness was visually evaluated. The gloss was evaluated as ◯ when the gloss increased compared to the untreated product, Δ when equal to the untreated product, and x when the gloss was less than the untreated product. Moreover, the evaluation which combined surface roughness and glossiness was made into comprehensive evaluation, and it was set as (circle) when it is better than an untreated product, (triangle | delta) when equivalent to an untreated product, and x when worse than an untreated product.

The results of Example 1 are shown in Table 1, and Comparative Example 1 is shown in Table 2. The zero cycle is a process using a projection material that has not been idle shot.

In Example 1, it can be seen that the numerical value of the surface roughness of the surface to be processed that has been processed with the projection material without blanking is reduced, and the processing surface is being mirror-finished. Moreover, glossiness also became favorable. In addition, even when blasting is performed using a blasting material that has been blown 2200 cycles, the same surface roughness and glossiness are obtained, so that the blasting material according to the present invention can be used repeatedly over a long period of time. It can be seen that it has a high polishing ability. In addition, the surface roughness at the time of processing with the projection material that was not blanked was slightly worse than the case of processing with the projection material that was blanked for 270 cycles, for example, In the projection material manufacturing process, clogging due to the formation aid and soft polyvinyl chloride entering between the abrasive materials, the abrasive material being pushed into the soft vinyl chloride particles by the die of the extrusion molding machine, or the abrasive material It is considered that the abrasive is not sufficiently exposed on the surface of the projection material due to falling off, etc., and performing a process of exposing abrasive particles having sufficient abrasive by performing a slight blanking In some cases, it may be preferable.

On the other hand, in the comparative example, the numerical value of the surface roughness of the treated surface that was processed using the projection material that was not blanked was slightly decreased compared to the untreated product, and there was no significant difference in glossiness. It was. When the treatment was carried out with a blasting material that had been 650 cycles idle, the surface roughness and gloss were worse than those of the untreated product. The same was true for 1130 cycles and 1600 cycles. This is because as the blasting process, the dust generated from the workpieces entered between the abrasives and clogged, and as a result, the surface of the projection material became very hard due to the dust layer. It is thought that this is the result of the formation of a satin-like unevenness when it collides with the surface.

Next, in order to investigate the influence of the ratio of the voids contained in the projection material of the present invention, Matsumoto Microfemer F-100 (manufactured by Matsumoto Yushi Seiyaku Co., Ltd.) as a hollow particle foaming agent in the raw material in the above embodiment. In a raw material (PVC, plasticizer, filler, abrasive), and other conditions were produced by the same method as in Example 1, and the porosity was 52% by volume (Example 2) and 75% by mass (comparison). The projection material of Example 2) was obtained. Using these projection materials, the SK-3 material having a hardness of HRC62 was used as an object to be processed, and the same blanking and blasting treatment as in Example 1 was performed. In the evaluation, the wear rate was calculated in addition to the surface roughness evaluation and the gloss evaluation. The consumption rate was calculated from the amount of blasting apparatus charged after collecting the projection material in the blasting apparatus after a predetermined number of idle shots.

The results are shown in Table 3. In the projection material having a porosity of 52% by volume, the surface roughness and gloss were improved as compared with the untreated product. Further, the consumption rate of the projection material was 48% by mass after 800 cycles of idle shots. On the other hand, in the projection material having a void ratio of 75% by volume, the surface roughness and gloss were not improved, and the consumption rate of the projection material was 35% by mass in 220 cycles and 55% by mass in 430 cycles. This is because, when the voids contained in the projection material increase, the bonding force between the abrasive particles becomes weak, and the collision energy when the projection material collides with the workpiece surface becomes the crushing energy of the projection material, which is sufficient for the workpiece surface This is considered to result from the inability to impart a sufficient polishing force.

According to the present invention, it is possible to make a mirror surface or a smooth surface without generating a satin-like unevenness on the surface of the workpiece in a very short time compared to conventional techniques such as polishing with polishing paper or polishing cloth. became. For example, it can be applied to mirror the cavity surface of a mold. The cavity surface of the mold requires a highly accurate surface. In addition, seizure of the molding material occurs as it is used. Therefore, for example, the cleaning of the molding material by image sticking or the like can be performed by a known method such as a conventional shot blasting method or a surface polishing method, and then can be mirrored according to the present invention. Of course, if the adhesion of the residue on the cavity surface is not so strong and can be sufficiently removed by spraying the projection material of the present invention, cleaning and mirroring may be performed simultaneously in the present invention.

As other applications, for example, it can be applied to various mirror surface or smooth surface applications, including pretreatment of a base material when a film such as DLC is applied.

1 Projection material (aggregate)
DESCRIPTION OF SYMBOLS 10 Abrasive particle 11 Thermoplastic resin 12 Abrasive material 20 Kneading apparatus 30 Pressure extrusion molding apparatus 40 Molded body (molded body by aggregate of abrasive particles)
50 Abrasive particles 60 Projection material (Comparative Example 1)
W gap

Claims (7)

It consists of abrasive particles having a diameter of 0.1 to 300 μm carried on the surface of thermoplastic resin particles having a diameter of 1 to 500 μm,
A blasting projection material, characterized in that it is formed as a bonded body in which the abrasive particles are bonded together. The blasting projection material according to claim 1, wherein the thermoplastic resin is soft polyvinyl chloride. The blasting projection material according to claim 1, wherein a diameter of the projection material is 0.01 to 3 mm. The blasting projection material according to any one of claims 1 to 3, wherein a gap is formed inside the projection material. The blasting projection material according to any one of claims 1 to 4, wherein at least a part of the projection material has a gap having a communication structure. The blasting projection material according to any one of claims 4 to 5, wherein a ratio of the voids in the projection material is 70% by volume or less. A blasting method comprising impregnating the blasting projection material according to any one of claims 4 to 6 with a liquid serving as a polishing aid and spraying the blasting material onto a workpiece.