JPH0360632B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a grindstone holder that constitutes a grindstone head used in a rotary surface grinder. (Prior Art) As shown in the explanatory diagram in FIG. 1, a grinding wheel head 1 used in a rotary surface grinding machine conventionally grinds grinding wheel pieces 3 mounted in an annular arrangement at equal intervals along the outer peripheral surface of an annular holder 2. The surface 3a had a rectangular shape, was attached to a grinding machine spindle (not shown), and the maximum allowable rotation speed was about 1200 revolutions per minute. If the grinding surface 3a of the grindstone piece 3 is rectangular as described above, while rotating the grindstone head 1 in the direction shown by arrow a in FIG. When grinding oil is injected towards the grinding wheel, the grinding oil that hits the grinding wheel piece 3 is refracted backward in the direction of movement of the grinding wheel piece, and at the same time flows out along with the grinding oil that is directly dissipated outside by centrifugal force through the gap between the grinding wheel pieces 3 and 3. There was a tendency for the particles to be discharged before entering between the grinding surface 3a of the grindstone and the object to be ground. In addition, the rectangular grinding surface 3a having the same width from the front end to the rear end in the direction of travel means that chips generated on the front end remain between the grinding surface 3a and the object to be ground while reaching the rear end. This results in a state where the grinding chips ride on the chips generated by the grinding wheel itself, leading to a decrease in grinding efficiency, and harmful resistance is generated between the grinding wheel piece 3 and the object to be ground, making it difficult to perform high-precision grinding. Ta. Furthermore, since the grindstone piece 3 having a rectangular cross section is used, there is a problem in that it is difficult to stably position the grindstone piece 3 when it is attached to the annular holder 2. In order to solve the above-mentioned problems and meet the demands of the industry, the applicant of the present application published Utility Model Publication No. 10630/1983, which has developed a grinding wheel piece with a grinding surface whose width is narrower at the rear than at the front in the direction of grinding progress. A holding wheel head is disclosed. (Problems to be Solved by the Invention) When grinding using conventional grindstones and grindstone pieces was analyzed, it was found that there were the following drawbacks. That is, since one side of the grinding wheel piece that substantially performs grinding is parallel to the jetting direction of the grinding fluid and does not touch the grinding surface, the penetration of the grinding fluid into the portion along the outside is insufficient, resulting in increased wear. In particular, the grinding resistance at the outward corner portions becomes large, resulting in wedge-shaped wear. It was found that due to this wear and tear, the part that actually performs the grinding action becomes the inner half of the grinding surface, which lowers the grinding ratio and adversely affects dimensional accuracy. It was also found that the inner half of the grinding surface was particularly susceptible to clogging due to insufficient penetration of the grinding fluid. Based on the above-mentioned viewpoints, the basic purpose of the present invention is to solve the various problems caused by the grinding wheel and the grinding wheel head in the rotary surface grinding machine, and furthermore, it provides a grinding wheel holder for fixing the grinding wheel pieces. I will not provide it. (Solution Means) That is, the holder for a rotary surface grinder of the present invention has the following features:
It consists of an annular holder body having a plurality of recesses on its outer circumferential surface for receiving the grindstone pieces, and a grindstone piece fixing fitting, and the recesses have a pair of sloped surfaces whose mutual spacing decreases toward the center of the annular holder body. A bisector of a portion corresponding to the intersection of the pair of slopes coincides with or almost coincides with the radius line of the annular holder main body, and the pair of slopes abuts on both sides of each of the grindstone pieces fitted in the recess. The grindstone piece fixing fitting is characterized in that it presses the grindstone piece within the recess in the radial direction. In particular, by configuring the bottom surface of this recess so that it does not come into contact with the grindstone piece, the grindstone piece can be stably fixed in a predetermined position. The grindstone pieces to be mounted in an annular arrangement at regular intervals on the annular holder are preferably shaped like irregular columns having a grinding portion approximating an isosceles triangle in which a portion corresponding to the apex angle and a portion corresponding to the base angle are shaved off, respectively, and the orientation of each grindstone piece is as follows. Fix each piece so that the bottom part faces outward. When the grinding wheel head consisting of the grinding wheel holder set in this way is attached to a rotary surface grinder and surface grinding is performed, one side of the isosceles on the front side in the direction of rotation is used to turn the grinding wheel head outward from the center of the annular holder. While giving the injected grinding oil an inward return component,
The width of the latter half of the rotating direction gradually decreases as it reaches the rear end, which quickly removes the generated chips to the outside of the grinding surface, improves the outward removal ability by jetting grinding oil, and improves the shape by excluding corners. The hardness and durability of the grindstone pieces are also improved by forming them into approximately isosceles triangular shapes. (Preferred Embodiment) Next, the grindstone holder of the present invention will be described along with an example of a corresponding grindstone piece according to an embodiment with reference to the drawings. First, the grindstone piece is shown in plan view in Figure 2.
Fig. 3 shows a rear view as seen from the arrow in Fig. 2, and Fig. 4 shows a horizontal view with the portion corresponding to the apex angle and two portions corresponding to the base angle removed, as shown by reference numeral 4 in the side view as seen from the arrow in Fig. 3. The cross section is shaped like an irregular column with an isosceles triangle approximation, and the material is, for example, white fused alumina WA461 in a vitrified grinding wheel or cubic boron nitride abrasive grains. Of course, the material of the grindstone differs depending on whether the object to be ground is metal or glass, and also depends on the type of metal and grinding conditions. Select and use different materials. On the other hand, the annular holder to which the grindstone piece 4 is mounted is
In the embodiment of the present invention shown in FIG. 5, which is a plan view showing only a part of the attached grinding wheel pieces 4, as indicated by reference numeral 5, 12 The concave portions 6 are equally divided, and the convex portions 7 between the concave portions 6 are each fitted with a metal fitting 8 for holding down the grindstone. The intersecting angle α of the pair of slopes 6b of each of the recesses 6 is made to match the angle corresponding to the apex angle of the grindstone piece 4 so that the isosceles 9a and 9b surfaces of the grindstone piece 4 are in close contact. Further, each recess 6 opens outward with a symmetrical opening so that when the grinding wheel piece 4 is fitted, the bisector of the slope 6b at the portion corresponding to the intersection angle coincides with the radius line of the annular holder 5. . (However, if necessary, this bisector line may be placed at a slight angle with the radius line of the annular holder 5.) The metal fitting 8 has its left and right center portions facing the convex portion 7 of the movable holder 5. Then, as shown in the cross-sectional view of FIG. 5 in FIG. do. This metal fitting 8 is formed to have the same height as the annular holder 5, and has cutout steps 12, 12 on the left and right sides for holding down the isosceles triangular base portion 11 of the grindstone piece 4 fitted in the recess 6. The bottom portion 11 of the illustrated grinding wheel piece 4 is an arcuate surface centered on the center of the annular holder 5 (which is a virtual point and coincides with the spindle axis of a rotary surface grinder (not shown)), and extends into the recess 6. When mounted, it forms a part of the circumferential surface concentric with the inner circumferential surface and outer circumferential surface of the annular holder 5. (However, the part corresponding to the bottom of the whetstone piece is
The radius of curvature may be smaller than the outer peripheral surface of the annular holder 5, or the radius of curvature may be linear. ) In this embodiment, the annular holder 5 has an inner diameter of 250 mm,
Outer diameter 340mm, height 80mm, angle α between both slopes 6b of recess 6 is 94°, width of bottom 6a perpendicular to the radius line.
The minimum thickness of the inner circumferential surface 5a and the bottom surface 6a is 19 mm, and the height of the grindstone piece 4 attached to this is 150 mm. (The angle α can be approximately 90 to 120 degrees, and can be increased as the size of the grindstone increases.) Since the grindstone holder of the present invention is constructed as described above, the slopes of each recess 6 of the annular holder 5 Fit the corresponding surfaces 9a and 9b of the whetstone pieces 4 into the respective parts 6b, and fix each whetstone piece 4 with the metal fittings 8 with the lower surfaces (surfaces to be ground) of the whetstone pieces 4 aligned on the same horizontal plane. (See Figures 5 and 6) Assemble. Note that the grindstone pieces to be used are not necessarily limited to those shown in the drawings, and the thickness in the radial direction, the apex angle, etc. can be varied to some extent. Next, the operation of the grindstone holder of the present invention will be explained with reference to the explanatory diagram shown in FIG. As described above, all the recesses 6 of the annular holder 5 are
When the grindstone piece 4 is attached to the spindle of a rotary surface grinder (not shown), the grindstone piece 4 is tightly positioned and fixed on both slopes 6b of the recess 6 of the annular holder 5, and the grindstone piece 4 rotates (during surface grinding). There is no slippage, high accuracy is achieved, and tightening positioning is simple and easy. Furthermore, it becomes possible to use a triangular cross-section grindstone, and in that case, the following effects are also added. When the grinding wheel head of the present invention is rotated in the direction shown by arrow a in FIG. The part that hits the front side 9a in the direction of rotation travels around the inside of the grinding wheel piece 4 so as to be pushed back inward by the inward pressing force, and then a part of the part contacts the grinding surface of the grinding wheel piece 4 and the object to be ground. When it comes out of the grinding surface again, it is scattered outward together with the grinding oil that passes between the front and rear grindstone pieces 4 in the rotating direction. On the other hand, if the grinding surface of the grinding wheel piece 4 is shaped like an isosceles triangle and the isosceles 9a and 9b are set facing inward, the width of the latter half in the direction of rotation narrows as it reaches the rear end, so that Generated chips are promptly discharged outside the grinding surface. In this way, since no chips remain between the grinding surface and the workpiece in the latter half of the grinding surface, no harmful resistance is generated during grinding, and phenomena such as slipping or lifting due to chips that adversely affect the finish do not occur. Furthermore, if the grinding piece 4 is made into an irregular column with a horizontal cross-sectional shape of an approximately isosceles triangle, and the part corresponding to the apex angle and the part corresponding to the base angle are shaved off, the strength of the shape is high and it can withstand long-term use. Furthermore, if a granular grindstone piece is used whose horizontal cross-sectional shape is the same as the lowermost grinding surface, it can be used until it becomes quite short. (Comparative Experiment) In order to examine the grinding performance of the grindstone held in the grindstone holder according to the present invention, a comparison was made with the grindstone held in the grindstone holder according to Utility Model Publication No. 10630/1983.
The material and cross-sectional area of each grindstone were the same. S45C tempered material with hardness HRB92 was used for the workpiece, and the machined surface dimensions were 300mm x 300mm and the thickness was 30mm. For grinding, use Sanshin fully automatic rotary surface grinder SPG600 model, place the center of the workpiece above at the center of the table, rotate the table at 20 revolutions per minute, and rotate in the opposite direction to the table rotation direction. The grinding wheel head was rotated at 1091 revolutions per minute. Noritake Cool AFT 100x liquid is used as the grinding fluid, and the grinding speed is 25 times per minute.
Sprayed on the machined surface with a small amount. cutting speed per minute
0.2 mm, and the workpiece was first ground once under the above conditions as sacrificial grinding, and after the grindstone surface was stabilized, a grinding test was conducted. The total depth of cut was 0.5 mm, and spark-out was performed for 40 seconds. In the measurements, the roughness of the finished surface was measured using the ○ marks on the machined surface shown in FIG. 8, and the flatness was measured using the ● marks. The position X marked by ○ is 75mm deeper than the edge of the workpiece, and the position Y marked ● is 10mm deeper. Finished surface roughness, flatness, amount of grinding, amount of grinding wheel wear,
Other measurement results are shown in Table 1.

[Table] (Note) Grinding sound indicates the average sound during grinding.
The sound before grinding was 79db.
Observing the ground surface of each grinding wheel piece after grinding, it is found that there is almost no adhesion of grinding chips to the grinding wheel piece held in the grinding wheel holder according to the present invention, whereas that held in the grinding wheel holder according to Utility Model Publication No. 53-10630. It was found that many grinding chips were attached to the grinding wheel pieces along the ridge line facing the center of rotation of the grinding surface. From this observation, it can be said that cooling and cleaning are performed more adequately in the present invention, and the grinding wheel surface is less clogged. Furthermore, when observing the machined surface of the workpiece, it was found that the size of the concentric pattern streaks that appeared at the center of the workpiece held in the whetstone holder of Utility Model Publication No. 53-10630 was approximately 1.5 times larger than that of the present invention. . From this result, it can be seen that the flatness of the grinding surface of the grinding wheel piece held in the grinding wheel holder of the present invention is relatively maintained during grinding, whereas the grinding wheel piece held in the grinding wheel holder of Utility Model Publication No. 53-10630 It was found that the shape of the grinding surface of the piece was such that the top of the grinding wheel head facing outward in the radial direction was worn in a wedge shape, making it impossible to maintain the grinding surface flat. Furthermore, it was found that the grinding wheel piece held in the grinding wheel holder of the present invention had a 40% better grinding ratio and much better flatness compared to the grinding wheel piece held in the grinding wheel holder of Utility Model Publication No. 53-10630. . Generally, in order to improve flatness, it is necessary to grind with a small load, but in the present invention, even though the load is higher than that of the grindstone held in the whetstone holder of Utility Model Publication No. 53-10630, the flatness can be improved. Good results were obtained. (Effects of the Invention) As is clear from the above description, the grinding wheel holder of the present invention can solve the problems of conventional grinding wheel pieces and grinding wheel holders for rotary surface grinders, can stably hold the grinding wheel pieces in a predetermined position, and can provide a high Accurate, high-speed surface grinding becomes possible. In addition, since the rotation speed, which was conventionally limited to about 1200 revolutions per minute, can be increased to about 1800 revolutions per minute, the finished surface can be improved and many other excellent effects are brought about. Moreover, even when compared with the grinding wheel piece and grinding wheel head of Utility Model Publication No. 10630/1983 filed by the present applicant, the grinding wheel piece and grinding wheel holder according to the present invention are 40% superior in grinding ratio, and have less adhesion of grinding chips. Since there are no wedge-shaped defects, the effect is that the flatness is high and the finished surface roughness is relatively small. This seems to indicate that the grindstone piece and grindstone holder according to the present invention have a better flow of grinding fluid. The most important aspect of the present invention is that the flatness can be kept to 5 μm under high loads. In the present invention, a grindstone piece fitted into a recess formed in an annular holder body is brought into contact with a pair of inclined surfaces on both sides of the grindstone piece, the distance of which decreases toward the center of the holder body of the recess. Since the holder is supported by pressing the holder in the radial direction with the one-piece fixing fitting, the grindstone piece can be firmly fixed and held to the holder in the direction of rotation thereof, that is, in the grinding direction of the grindstone piece. Furthermore, in the present invention, since the grindstone piece is supported on the holder by two-point support (typically two-sided support) in the circumferential direction of the holder, the grindstone piece attached to the holder is The shape does not need to exactly match the shape of the recess. For example, even if the side surface of the grindstone piece is not flat but slightly arcuate, it can be easily and firmly fixed and held. In addition, since the grindstone piece can be fitted and supported in the recess and then tightened with the grindstone piece fixing fitting, the attachment of the grindstone piece is easy.

[Brief explanation of drawings]

Fig. 1 is an operation explanatory diagram schematically showing an example of a conventional grinding wheel head, Fig. 2 is a plan view of a grinding wheel piece used in the present invention, Fig. 3 is a back view as seen from the arrow in Fig. 2, and Fig. 4 is a diagram showing the third
5 is a plan view of an embodiment of the grindstone head of the present invention with some parts omitted, and FIG.
FIG. 7 is a schematic diagram illustrating the operation of the grindstone head of the present invention, and FIG. 8 is a plan view of a workpiece ground in a comparative experiment. 4... Grindstone piece, 5... Annular holder, 6... Concave portion (6b... slope), 7... Convex portion, 8... Metal fitting, 9
a, 9b...isosceles, 10...volt.

Claims (1)

[Claims] 1. Consists of an annular holder main body having a plurality of recesses on the outer peripheral surface for receiving grindstone pieces, and a grindstone piece fixing fitting, and the recesses are spaced apart from each other toward the center of the annular holder main body. It has a pair of decreasing slopes, a bisector at a portion corresponding to the intersection of the pair of slopes coincides with or almost coincides with the radius line of the annular holder body, and the pair of slopes corresponds to the diameter of the grinding wheel piece fitted into the recess. A grindstone holder for a rotary surface grinder, characterized in that the grindstone piece fixing fittings are abutted on both sides and press the grindstone pieces in the recess in the radial direction. 2. The holder for a rotary surface grinder according to claim 1, wherein the recess has a bottom surface that does not come into contact with a grindstone piece fitted into the recess.