TWI648128B - Grinding body for barrel grinding - Google Patents

Abstract

The invention provides a method for producing a striking mark on a workpiece due to contact between a workpiece (workpiece) and a grinding body (medium) during barrel grinding, and the contact state of the workpiece with the medium changes as the grinding time passes. Less barrel grinding media. This barrel polishing medium is composed of a mixture in which abrasive grains are dispersed in a resin which is a matrix. The barrel polishing medium includes a cylindrical straight body portion having a bottom surface formed by one end surface, and a reduced diameter portion continuously reduced in diameter from the other end surface of the straight body portion, and the bottom surface and the side surface of the straight body portion The intersection portion, the boundary portion between the straight body portion and the reduced diameter portion, and the vertical cross section including the apex of the reduced diameter portion form a convex curve.

Description

Grinding body for barrel grinding

The present invention relates to a polishing body for performing barrel polishing processing such as burr removal and smooth processing of a workpiece into a barrel polishing apparatus together with a workpiece.

Since the past, the barrel grinding process has been used for scale removal, burr removal, film removal, burr removal, tool mark removal, and processing scars of the workpiece (hereinafter referred to as "workpiece"). Removal, R surface formation, gloss processing, and smoothing processing. In the barrel grinding process, the workpiece and a plurality of polishing bodies (hereinafter referred to as "media") are put into the barrel grinding tank of the barrel grinding device, and the grinding tank is rotated or vibrated, whereby the workpiece and the medium are in a flowing state, and the workpiece is used. Grinding with collision and contact with the medium. The medium can be appropriately selected depending on the shape of the workpiece, the material, and the purpose of the polishing process. As a material of the medium, ceramics, metals, resins (for example, described in Patent Documents 1 to 3) and the like can be preferably used.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. Hei. No. Hei. No. Hei. No. 2007-268686.

Grinding with a ceramic or metal medium can be performed with good polishing force, but there is a case where a scratch or a scratch is caused by a collision between the workpiece and the medium due to a difference in the material of the workpiece. On the other hand, since the resin is used as the medium of the substrate, since the hardness is lower than that of the ceramic or the metal, there is an advantage that it is difficult to produce a strike mark on the workpiece. However, compared with a medium composed of ceramic or metal, the weight of the workpiece is less than that of the medium, and the grinding force is low. Moreover, since the wear resistance is low, the grinding force is reduced as the grinding time passes through the medium. In particular, when the contact state between the workpiece and the medium changes due to the change in the shape of the medium due to wear (partial wear), not only the grinding force is lowered, but also the corner portion of the workpiece cannot be in contact with the medium due to the difference in the shape of the workpiece. Therefore, the entire workpiece cannot be uniformly polished.

In view of the above problems, the medium for barrel polishing according to the first aspect of the invention is characterized in that the medium is composed of a resin to be a matrix and abrasive grains dispersed in the resin, and the medium has a cylindrical shape in which an end surface forms a bottom surface of the medium. a straight body portion and a reduced diameter portion continuously formed from the other end surface of the straight body portion to form a vertex of the apex of the medium, and a cross portion of the bottom surface and a side surface of the straight body portion and the straight body portion A boundary curve is formed between the boundary portion of the reduced diameter portion and the vertical cross section including the apex of the reduced diameter portion. By setting the shape of the medium to the shape of the straight body portion and the diameter reducing portion, it is possible to reduce the shape of the medium in the same shape as the medium passes through the polishing time. Thereby, the change of the contact state between the workpiece and the medium can be reduced, so Hold the same grinding state. Further, by forming the intersecting portion, the boundary portion, and the vertical cross section including the vertex as a convex curve (that is, a shape in which the corner portions are smooth curved surfaces), the workpiece is not damaged when colliding with the workpiece.

According to a second aspect of the invention, in the barrel polishing medium according to the first aspect of the invention, the reduced diameter portion is reduced in diameter toward the apex in at least two stages. By reducing the diameter of the reduced diameter portion toward the apex in a plurality of stages, the block can be placed into the workpiece and the medium in the barrel grinding tank (water and grinding aid (compound in the case of wet barrel grinding) ))) The fluidity is improved, and the polishing can be performed efficiently.

According to a third aspect of the invention, the medium for barrel polishing according to the first or second aspect of the invention, wherein a ratio of a diameter of the bottom surface to a distance from the bottom surface to the apex is 1:0.5 to 1:1.5.

According to a fourth aspect of the invention, the medium for barrel polishing according to the first or second aspect, wherein a ratio of a diameter of the bottom surface to a distance from the bottom surface to the apex is 1:0.8 to 1:1.0. By selecting the length from the bottom surface to the apex from 0.5 to 1.5 times, preferably 0.8 to 1.0 times the diameter of the bottom surface, it is possible to polish without scratching the workpiece.

The fifth invention is the medium for barrel polishing according to any one of the first to fourth aspects, wherein the circular cross section has a diameter of 1 to 40 mm. Thereby, the uneven portion and the corner portion of the workpiece can be polished well.

The medium for barrel polishing according to any one of the first to fifth aspects of the present invention, wherein the resin has a Vickers hardness of 10 to 30 HV. Thereby, it is possible to perform polishing without imparting a strike mark to the workpiece.

The medium for barrel polishing according to the sixth aspect of the invention, wherein the abrasive grains are contained in an amount of 30 to 70% by mass based on the polishing medium. Thereby, the medium can obtain sufficient grinding power.

The eighth aspect of the invention is the medium for barrel polishing according to the sixth or seventh aspect, wherein the medium has a mass of 0.01 to 50 g and a specific gravity of 1.5 to 2.5. By this feature, the collision energy between the workpiece and the medium can be sufficiently obtained, so that the medium can obtain sufficient grinding force.

Thus, the medium of the present invention can provide a medium for barrel grinding without imparting a strike mark to the workpiece, and has a high grinding force for a long period of time.

Furthermore, the medium of the present invention can be preferably used for dry barrel grinding processing in which the workpiece and the medium are put into the barrel grinding tank, and the grinding is performed in a flowing state, and the workpiece, the medium, and the water to be processed. And, if necessary, the compound is put into the barrel grinding tank and the wet barrel grinding processing which performs the grinding in the flow state is performed.

Hereinafter, embodiments for carrying out the invention will be described using the drawings. Furthermore, the directions in the upper, lower, left and right directions in this document indicate the directions in the figure.

The medium 01 is composed of a straight body portion 11 having a continuous circular cross section, and a reduced diameter portion 12 which is continuous with the straight body portion and which is located at an upper portion thereof and whose outer shape surface (or side surface) is continuously reduced in diameter. The medium becomes wearer as the barrel grinding time passes, but the medium as a whole wears evenly during wear. When the same shape is reduced, the change of the grinding force caused by the abrasion of the medium is small, but when the whole wear is not evenly worn, that is, when the partial wear occurs, as the grinding time passes, the workpiece and the medium are The change in the contact state causes a large difference in the grinding force. For example, in the case of barrel grinding by a medium of a quadrangular prism shape, the collision energy concentrates on the corner portion of the medium and gradually becomes a cylindrical shape or a spherical shape. Therefore, the polishing force of the initial medium differs greatly from the polishing force of the deformed medium. Therefore, when the barrel is ground by the deformed medium, the grinding state of the workpiece is insufficient or uneven. By setting the shape of the medium to the shape of this embodiment, it is possible to prevent partial wear.

Further, the bottom surface (the lowermost portion in FIG. 1(A)) 11a of the straight body portion 11 and the intersection portion 01a formed by the side surface 11b orthogonal to the bottom surface 11a, the straight body portion 11 and the reduced diameter portion 12 The boundary portion 01b and the vertical cross section including the vertex 01c of the reduced diameter portion 12 each form a convex curve (R surface). As described above, the barrel grinding is performed by colliding and contacting the workpiece with the medium in the barrel grinding tank. When the intersection portion 01a, the boundary portion 01b, and the vertex 01c form an acute angle, the workpiece may form a strike mark or be damaged when the workpiece comes into contact with the medium. Further, when the workpiece collides with the medium, the acute angle portion becomes a base point and the medium is broken.

As shown in FIG. 3, the reduced diameter portion 12 is reduced in diameter toward the apex. For example, in the reduced diameter portion 12 of FIG. 3(A), the vertical cross section having the apex is a semi-elliptical shape. The reduced diameter portion of Fig. 3(B) is formed at the same inclination angle with the side surface facing upward, and is inclined sharply in the vicinity of the upper end. In the reduced diameter portion of Fig. 3(C), the inclination angle is changed stepwise toward the upper side. In this embodiment In the state, as shown in FIGS. 1 and 2, the diameter is reduced in four stages (a to d in FIG. 2). Furthermore, the single-dot chain lines of Fig. 2 indicate the boundaries of different reduction ratios. By changing the reduction ratio of the reduced diameter portion 12 (i.e., the inclination angle of the side surface) in at least two stages or more, the partial wear can be further reduced. Moreover, when the barrel is polished, the fluidity of the block can be improved.

The ratio (Y/X) of the height Y of the medium (the distance between the vertex 01c and the bottom surface 11a) to the diameter X of the bottom surface 11a is set to 0.5 to 1.5, more preferably 0.8 to 1.0. It is difficult to cause partial wear when the medium passes through the barrel grinding time and maintain the same grinding state for a long time. Further, the diameter X of the bottom surface can be appropriately selected depending on the size of the workpiece, and if it is selected from 1 to 40 mm, the corner portion of the workpiece having irregularities can be satisfactorily polished. Further, as a problem in the barrel polishing, there is a case where the medium is engaged in the concave portion or the corner portion of the workpiece in the barrel grinding according to the shape of the workpiece, but by selecting the diameter X of the bottom surface from the above range, the phenomenon.

The medium 01 is composed of a resin to be a matrix and abrasive grains dispersed in the resin. If the resin is too hard, a collision mark will be generated on the workpiece due to collision with the workpiece. If it is too soft, the resin will be deformed during collision with the workpiece, and sufficient polishing force cannot be obtained. In order to make it difficult to generate a scratch on the workpiece and obtain a sufficient polishing force, it is preferable to select the hardness (Vickers hardness) of the above resin from the range of 10 to 30 HV. Further, the above resin may preferably be a thermoplastic resin (for example, a nylon resin, a polystyrene resin, a polypropylene resin, a polyamide resin, an AS (acrylonitrile-styrene) resin, or the like) or a heat hardening. Resin (eg phenolic resin, no Saturated polyester resin, polyurethane resin, epoxy resin, and urea resin, etc.).

If the content of the abrasive grains is too high, the hardness of the medium itself is high, and a strike mark is generated on the workpiece by collision with the workpiece. Further, if the content ratio is too low, sufficient polishing force for polishing the workpiece cannot be obtained. In order to make it difficult to generate a scratch on the workpiece and obtain a sufficient polishing force, it is preferred to select the content of the abrasive grains in a range of from 30 to 70% by mass based on the medium. As the abrasive grains, a known material (for example, alumina, ceria, strontium carbide, iron oxide, boron oxide, zirconium, chromium oxide, diamond, corundum, and the like, or the like) may be preferably used. A molded product of raw materials, etc.). Further, a mixture of two or more kinds of the above materials may be used. Further, the particle size of the abrasive grains can be appropriately selected depending on the type of the abrasive grains, the size of the medium, the properties of the workpiece, and the purpose of polishing.

If the weight of the medium is too heavy, the collision energy with the workpiece is too high, and a collision mark is generated on the surface of the workpiece due to collision with the workpiece. Further, if the weight is too light, the collision energy with the workpiece is too low, and sufficient polishing force cannot be obtained. Preferably, the weight of the medium is selected from the range of 0.01 to 50 g, and more preferably the weight of the medium is selected from the range of 0.02 to 40 g. Further, it is preferred to select the specific gravity (true specific gravity) from the range of 1.5 to 2.5, and more preferably to select the specific gravity (true specific gravity) from the range of 1.8 to 2.2. In the case of barrel grinding, a plurality of identical media are usually charged and subjected to grinding. By selecting the above specific gravity from the range, it is possible to uniformly disperse the medium with respect to all the workpieces while performing processing on a plurality of workpieces, and to uniformly grind the workpieces with respect to all the workpieces.

[Examples]

A change in the shape of the medium caused by barrel grinding was investigated using a centrifugal barrel grinding apparatus (EC-2 type: manufactured by Shinto Industries Co., Ltd.). The abrasive grains are dispersed in a mixture of a thermosetting resin having a Vickers hardness of 25 HV so as to be 60% by mass of the whole, and two kinds of media forming the shape described in the embodiment are formed (formation of the bottom surface 13a) Diameter X: 6 mm, ratio of the height Y of the medium to the diameter X of the bottom surface 11a (Y/X): a medium having a shape of 1.0 (Example 1), and a diameter X forming the bottom surface 11a: 6 mm, medium A medium (Example 2) in which the ratio Y (Y/X) of the height Y to the diameter X of the bottom surface 11a is 1.3. Further, as a comparative example, a medium having the following shape was formed using the above mixture. The molding method is appropriately selected from known methods such as casting molding and extrusion molding depending on the shape of the molding.

Comparative Example 1: Spherical medium having a diameter of 6 mm.

Comparative Example 2: A cube medium having a length of 6 mm on one side.

Comparative Example 3: A rectangular parallelepiped medium having a square bottom surface of 6 mm in length and a longitudinal section orthogonal to the bottom surface of 9 mm in length.

Comparative Example 4: A medium composed of a straight body portion and a reduced diameter portion, the diameter of the bottom surface 13a: 6 mm, and the ratio of the height Y of the medium to the diameter X of the bottom surface 11a (Y/X): 0.3.

Comparative Example 5: A medium composed of a straight body portion and a reduced diameter portion, the diameter X of the bottom surface 13a: 6 mm, and the ratio (Y/X) of the height Y of the medium to the diameter X of the bottom surface 11a: 1.7.

Performing to remove the workpiece painted black (bottom 10 × 10, thickness 2 The film (coating film) of mm, the intersection of the R surface of 1.0 mm and the length of 10 mm) is used for the purpose of grinding.

The ratio of the medium to the workpiece is 5.0 in terms of a volume ratio (volume of the entire medium/volume of the entire workpiece), and is respectively placed in four barrel grinding grooves having a hexagonal cross section, and the medium is used as the barrel grinding tank. The volume is 1/2 of the volume. Thereafter, the barrel grinding tank was placed in the above-described centrifugal barrel polishing apparatus, and the barrel grinding tank was operated at a rotation speed of 200 rpm and a revolution speed of 200 rpm for 0.5 hour. After the completion of the grinding process, the barrel grinding tank is removed from the centrifugal barrel grinding device, and after the workpiece is taken out from the barrel grinding tank, the same amount of the workpiece is again put into the barrel grinding tank, and then the grinding process is performed in the same manner. In response to these operations, the polishing process was performed 70 times, and the "shape of the medium", the "strike mark of the workpiece", the "processing of the workpiece", and the "polishing force" in the first polishing and the 70th polishing were evaluated. Each evaluation is as follows.

The shape of the medium is visually observed, and is approximately the same as the shape of the initial shape (the size may be different), and is set to ○. When it is confirmed that there are some changes, it is set to Δ, and when the shape is large, the difference is set to × .

Strike marks of the workpiece: It is visually observed, and is set to ○ when the strike mark is not confirmed, and is set to × when the strike mark is confirmed.

Processing of the workpiece: When the film of the corner portion of the L-shaped portion of the workpiece is removed by visual observation, it is set to ○, and when the film of the corner portion is not removed, it is set to ×.

Grinding force: The change in weight before and after the grinding process was measured.

The evaluation results after barrel grinding were carried out as follows. So you know: Ben In the medium of the invention, there is no partial wear of the medium and a decrease in the amount of polishing accompanying the polishing time, and the barrel grinding can be performed well even in the corner portion of the workpiece.

Shape of the medium: Regarding the shape of the medium after the 70-time grinding process, Example 1, Example 2, and Comparative Example 1 were smaller than the initial stage, but no large change in shape was observed. On the other hand, Comparative Example 2 was close. In the spherical shape, Comparative Example 3 is close to the ellipsoid. In Comparative Examples 4 and 5, the ratio (Y/X) of the diameter X to the height Y described above was changed to about 0.5 and about 1.4, respectively.

Strike marks of the workpiece: No impact marks on the workpiece were observed in any barrel grinding by the medium.

Processing of workpieces: In Examples 1 and 2, the corners of the workpiece were processed in the first and the 70th barrel grinding. In Comparative Example 1, the corners of the workpiece were not processed in any of the barrel grindings, and in Comparative Examples 2 to 5, the corners of the workpiece were processed in the first barrel grinding, but in the 70th grinding. When the corner portion of the workpiece is not finished, it is understood that the contact with the corner portion of the workpiece is insufficient due to the partial wear of the medium.

Grinding force: in the barrel grinding by the medium in which the shape is changed by grinding (Comparative Examples 2 to 5), the surface roughness of the workpiece after the first grinding and the 70th grinding is the same as that of the workpiece after the first grinding When the diameter is greatly increased, it is understood that the shape change due to partial wear reduces the polishing force. Further, the workpiece polished by the medium of Comparative Example 1 was not significantly different between the first time and the 70th time, but the surface roughness was larger than that of the workpiece polished by the workpieces of Examples 1 and 2. From this, it is understood that the medium of Comparative Example 1 does not have sufficient polishing force. On the other hand, by the embodiment 1 and the embodiment 2 The surface roughness of the workpiece polished is significantly smaller than that before polishing, and the difference between the surface roughness of the workpiece after the first polishing and the 70th polishing is small, and it is known that the surface roughness is good for a long time. Grinding force. In particular, compared with the polishing using the medium of Example 2, the medium of Example 1 had a small difference after the first polishing and the 70th polishing, and it was found that the medium of Example 1 was more preferable.

[Industry availability]

The barrel grinding medium of the present invention can be preferably used in either dry barrel grinding or wet barrel grinding. Moreover, it can be preferably used not only in the centrifugal barrel polishing described in the examples, but also preferably in the known barrel grinding by a vibrating barrel grinding device, a flow barrel grinding device, a rotary barrel grinding device, or the like. The device is being ground.

The present application is based on Japanese Patent Application No. 2011-084231, filed on Apr. 6, 2011, the content of which is incorporated herein.

Further, the present invention can be more completely understood by the detailed description of the specification. However, the detailed description and specific examples are intended to be illustrative of the invention The reason for this is that the manufacturer understands that various changes and changes can be made from the detailed description.

The Applicant is not intended to present any of the stated embodiments to the public. In the case of the changes or substitutions disclosed, it may not be within the scope of the patent application in the language as part of the invention.

In the description of the specification or the scope of the claims, the use of the singular and plural referents are to be construed as the singular and plural. The use of any exemplifications or exemplifications of the invention, such as "the" or "an", is intended to be construed as a limitation of the scope of the invention.

01‧‧‧Abrased body (medium)

01a‧‧‧Intersection

01b‧‧‧Borders

01c‧‧‧ vertex

11‧‧‧ Straight body

11a‧‧‧ bottom

11b‧‧‧ side

12‧‧‧ Reduced diameter

Fig. 1 is an explanatory view showing the shape of a medium in the embodiment. Fig. 1(A) is a front view, and Fig. 1(B) is an arrow view (bottom view) taken along line A-A in Fig. 1(A).

Fig. 2 is an explanatory view showing the shape of a medium in the embodiment.

Fig. 3 is an explanatory view showing the shape of the medium of the present invention.

Claims (6)

A polishing body for barrel polishing, which is composed of a resin to be a matrix and abrasive grains dispersed in the resin, wherein the polishing body includes a cylindrical straight body having an end surface forming a bottom surface of the polishing body. a portion having a diameter reduced continuously from the other end surface of the straight body portion to form a reduced diameter portion of the apex of the polishing body; and a cross portion of the bottom surface and a side surface of the straight body portion, the straight body portion and the contraction portion The corner portion of the boundary portion of the diameter portion and the vertical cross section including the apex of the reduced diameter portion form a convex curve, and the reduced diameter portion has a first curvature radius, a second curvature radius, a third curvature radius, and a fourth curvature The fourth radii of the radius are reduced toward the apex, the second radii of curvature is larger than the first radii of curvature, the third radii of curvature is larger than the second radii of curvature, and the fourth radii of curvature is smaller than the third radii of curvature The abrasive grains are contained in an amount of 30 to 70% by mass based on the polishing body. The polishing body for barrel polishing according to the first aspect of the invention, wherein a ratio of a diameter of the bottom surface to a distance from the bottom surface to the apex is 1:0.5 to 1:1.5. The polishing body for barrel polishing according to the second aspect of the invention, wherein a ratio of a diameter of the bottom surface to a distance from the bottom surface to the apex is 1:0.8 to 1:1.0. The abrasive body for barrel polishing according to claim 2, wherein the circular cross section has a diameter of 1 to 40 mm. The abrasive body for barrel grinding according to item 2 of the patent application scope, wherein the above The resin has a Vickers hardness of 10 to 30 HV. The abrasive body for barrel polishing according to claim 5, wherein the mass of the polishing body is 0.01 to 50 g, and the specific gravity is 1.5 to 2.5.