JPS6047067B2 - Dressing method for spherical grinder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to cup-shaped grinding and a dressing method for a spherical grinder that grinds a spherical part of a workpiece by forming and dressing stones into a spherical shape with a cup-shaped multi-stone diamond dresser. A dressing method has been established so that the pitch of the dress marks that appear on the stone surface during dressing becomes a dress pitch suitable for each arbitrary processing condition such as rough, medium, and finishing.

In grinding, there are three types of contact between the stone and the workpiece: point, line, and surface contact, and processing takes this into account, but cup-shaped grinding and dressing the stone into a spherical shape are used. Since spherical grinders use surface contact, the pitch of the dress mark on the surface of the stone, that is, the dress pitch, is the most important factor that affects grinding efficiency and product accuracy.
It is no exaggeration to say that the success or failure of spherical surface machining is largely determined by whether or not this is properly regulated.

However, in the past, redressing was done manually using a single-stone diamond dresser or a stitch bar, and it was not possible to arbitrarily adjust the dressing pitch, which is the most important factor mentioned above, to the optimum value, so it was unavoidable. Since coarse-grained stones were used for rough processing and dense-grained stones were used for finishing, the grinding efficiency was improved by simply changing the stones depending on the processing conditions. It was difficult to hope for. Attempts have also been made to dress the stone by creating a spherical surface using a cup-shaped rotary diamond dresser, but if the dressing conditions are inappropriate, the stone surface becomes smooth and the dressing effect is lost. The present invention has been made in view of the above points, and uses the cup-shaped multistone diamond dresser, which has the same effect as the cup-shaped rotary diamond dresser, as a means for creating a spherical surface, and keeps the rotation speed or the number of diamonds constant. The above-mentioned optimal dressing is performed by appropriately combining the ingredients based on the law.

In general, the roughness of the surface to be ground changes depending on the size of the dress pitch, as shown in Figure 1, but as mentioned above, in the case of surface contact machining, phenomena such as falling off of the stone, clogging, and burning are likely to occur, resulting in roughness. It is necessary to make the condition of the stone surface appropriate, especially the dress pitch, depending on the processing conditions such as medium and finishing. For example, in the case of hardened bearing steel, the values shown in Table 1 are empirically desirable.

Now, FIGS. 2 and 3 are schematic diagrams showing the case of grinding concave and convex spherical surfaces, respectively. In the case of cup-shaped grinding, the surface 1a of the stone 1 is polished into convex and concave spherical surfaces, respectively, by cup-shaped multi-stone diamond dresser 3. The dress will be molded into the dress.

Its spherical center 0 coincides with the spherical center of the workpiece 5, and the axis of rotation of the cup-shaped grinding stone (hereinafter simply referred to as stone) 1 is A-0-.
A is on the same plane as the rotational axis 0-B of the cup-shaped multi-stone diamond dresser (hereinafter simply referred to as the dresser) 3 and the rotational axis C10-C of the workpiece 5, and intersects with each other at the spherical center 0. There is. Note that the reference numeral 2 represents a stone, and the reference numeral 4 represents a rotation drive device for the dresser. For example, as shown in FIGS. 4 and 5, the dresser 3 has several diamonds 31, 32, 33, etc. planted in a main body 30 at equal intervals on the circumference of a diameter d, and the dresser 3 is fitted with a set screw 6. Points 31a, 32a
, 33a, . . . with the same height and fixed with setscrews 7 are used. Figure 6 is a plan view showing the mutual relationship between the stone surface and the diamond-embedded surface of the dresser during dressing. A stone surface 1a with an outer diameter D where a point 31a moves on the circumference of a diameter d from point e to e'' and rotates at a number of revolutions per minute in the direction of the arrow in the figure.
The dress mark when crossing the line will look like a spiral line e-f.

Now, if the rotational speed ratio P1n of both is an integer 1, the dress mark by the dress point 31a is necessarily only one e-f. However, in reality, a dress mark having an inclination angle symmetrical to the dress mark e-f is carved, resulting in a so-called twill, but the symmetrical mark is not included in the calculation here. If z diamonds are planted at equal intervals on the circumference of a diameter d as described above, the number of dress marks formed by these dress points 31a, 32a, 33a, etc. will not necessarily be as follows. Not an individual. That is, in this case, the denominator a of an irreducible fraction is the number of dress marks, with the rotational speed ratio 1 of the stone and dresser being the numerator and the number z of diamonds being the denominator. for example,
If N=1500 rpm, n=20r'Pm, and z=6, there are two dress marks because it is a rotation. In this case, if there are only five z's, then there is only one dress mark.

The above-mentioned FIG. 6 shows an example case where z=6. That is, the dress marks by the dress points 31a, 33a, 35a are e-f, and the dress marks by the dress points 32a, 34a are
, 36a are like g-h. However, the distance between them, ie, the dress pitch P, is given by the following equation (1). Time t for the diamond to pass through ee''
is the number of revolutions N'' at which the stone rotates within this time. Therefore, if the number of dress marks is a, then the pitch P is,
Now, the number of revolutions N and n of the carcass and dresser are determined by the rotational speed ratio Nl
n is determined to be an integer ratio (1), and the stone diameter D and the diameter d of the diamond planting or embedding circle of the dresser are determined;
Using the number z of diamonds as a parameter, the number a of dress marks is determined as described above, and this is substituted into the above equation (1) to determine the dress pitch P. When tabulated, for example, as shown in Table 2 is obtained.

Table 2 As is clear from this table, all other specifications are the same, but if the number of diamonds z is 4 or 9, do you want a rough finish or replace the number of diamonds with 7 or 8? Alternatively, in the dresser shown in FIGS. 4 and 5, the diamonds 31, 32, etc. may be replanted to the predetermined number, or the set screws 7 and push screws 6 may be used to set the required number of diamonds 31, 32, etc. By increasing or decreasing the number of diamonds by making the heights of the diamond dress points the same and retracting the others more than this, it is suitable for medium processing, and if the number is 11 in the same way, it is suitable for finishing processing. Can be dressed on a dress pitch.

Further, if the rotation speed n of the dresser is further set as a parameter in Table 2, Table 3 is obtained.

Table 3 According to this table, when n = 20 rpm, it is exactly the same as in Table 2 above, and a dresser with 9 diamonds is suitable for rough machining as mentioned above, but it simply shows the rotation speed with the same dresser. 30r'Pm with known transmission means
If the speed is changed to 15 rpm, the dressing pitch becomes 0.42Tr0n, which is suitable for medium machining, and if the speed is similarly changed to 15 rpm, the dressing pitch becomes 0.217r0fL, which is suitable for finishing.

As detailed above, the present invention enables cup-shaped grinding and spherical forming dressing of a spherical grinder using stones, which were conventionally considered difficult, to be performed easily according to the processing conditions such as rough, medium, and finishing. Moreover, since it can be carried out with high efficiency and high precision, it is possible to greatly improve the grinding efficiency and the precision of the surface roughness, shape, etc. of the product.

Furthermore, since the dress mark obtained by the spherical shaping dressing as in the present application is a twill pattern as described above, stable finished surface roughness can be expected due to the twill pattern.

[Brief explanation of the drawing]

Figure 1 is a characteristic diagram showing the relationship between the dressing pitch of the dovetail surface and the effective roughness of the ground surface. Figure 2 is a schematic diagram showing the positional relationship between the dovetail, dresser, and workpiece when grinding a concave spherical surface. ,
FIG. 3 is a schematic diagram of the above when grinding a convex spherical surface, FIG. 4 is a front view showing an example of a cup-shaped multi-stone diamond dresser used in the present invention, FIG. 5 is a side view of the same dresser, and FIG.
The figure is a plan view showing the mutual relationship between the stone surface and the dressing point of the dresser and the dress mark. Explanation of symbols, 1: Cup-shaped grinding and stone, 3: Cup-shaped multi-stone diamond dresser, 5: Workpiece, 31, 32, 33
・・：Diamond, 31a, 32a, 33a・・
...: Dress point.

Claims (1)

[Claims] 1. In a spherical grinding machine that grinds a spherical part of a workpiece by forming and dressing stones into a spherical shape with a cup-shaped multi-stone diamond dresser, the rotation axis of the dresser intersects with the rotation axis of the stone, and The number of diamonds implanted or buried in the dresser is selected so that the intersection point coincides with the spherical center of the spherical surface of the stone, and the rotational speed ratio of the stone and the dresser is an integer ratio. is increased or decreased under any rotational speed ratio of the above-mentioned rotational speed ratio, and according to the dressing, the dressing pitch of the stone and the stone surface is made into a dressing pitch suitable for each arbitrary processing condition such as rough, medium, finishing, etc. Dressing method for spherical grinding machine.