JP2001170861A - Centerless grinding blade - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the rise in the manufacturing cost of blades, and reduce the wear, in particular the partial wear of the top face of a blade, in centerless grinding. SOLUTION: In centerless grinding using a blade supporting a work piece put between a grinding wheel and a regulating wheel, the top face of the blade 10 is formed of a hard abrasive layer 2 containing either one or both of diamond abrasives and CBN abrasives, and the percentage contents of abrasives in the hard abrasive layer 2 is made more greater on the inlet side than on the outlet side of the workpiece on the top face of the blade 10. Thus, the wear on the inlet side is suppressed to reduce the partial wear.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centerless grinding blade used for centerless grinding a round or cylindrical workpiece.

[0002]

2. Description of the Related Art There is a centerless grinding as a grinding process suitable for the outer circumference grinding of a small diameter round bar or a pipe. In this centerless grinding, as shown in FIG. 3, a grinding wheel 20 for grinding the workpiece W, and an adjustment wheel 2 which faces the grinding wheel 20 in a state of holding the workpiece W and applies a braking force to the workpiece W.
1 and a centerless grinding machine provided with a blade 22 for supporting the workpiece W, which is provided between the grinding wheel 20 and the adjusting wheel 21. As shown by arrows in the figure, the grinding wheel 20 and the adjusting wheel 21 Are rotated in the same direction, the workpiece W is rotated in the opposite direction, and the outer periphery of the workpiece W is ground by the grinding wheel 20.

In this centerless grinding, the adjusting wheel 21
The workpiece W is placed on the top surface 22 a of the blade 22 because the
It moves in the direction of arrow A while sliding on the top. At this time, a spiral wound may be generated on the workpiece W due to a scratch generated on the top surface 22a of the blade 22 due to abrasion or the like, and various attempts have been made to improve the occurrence of such a scratch. .

[0004] Since the top surface of the blade is required to have wear resistance to a workpiece, abrasive grains falling off a grinding wheel, or cutting chips, the material of the blade may be cast iron, hard steel, or cemented carbide. Hard materials such as are often used, and those whose top surface is formed of an abrasive layer using diamond abrasive grains or CBN abrasive grains, various ceramics, and the like are also used.

[0005] For example, Japanese Patent Application Laid-Open No. 54-137796 discloses a metal bond segment grindstone in which a grindstone layer in which diamond or CBN abrasive grains are fixed by a metal bond and a metal layer containing no abrasive grains are integrally fixed. A blade glued on gold is described. It is said that this blade significantly improves wear resistance and durability.

[0006]

Incidentally, the wear of the blade top surface in actual centerless grinding is not uniform over the entire top surface, and the degree of wear varies depending on the portion. In particular, when viewed in the longitudinal direction of the blade top surface, the degree of wear is greater at the entrance side of the workpiece than at the exit side. Therefore,
If the wear on the inlet side reaches the life limit, the life will end even if other parts can be used. In addition, if uneven wear occurs on the blade top surface, the workpiece vibrates at the time of grinding, which causes poor machining accuracy and uneven wear of the grinding wheel. When uneven wear of the grinding wheel occurs, the service life of the wheel decreases, and the number of times of dressing increases, and the working efficiency decreases. Therefore, it is very important to prevent uneven wear of the blade top surface.

A problem to be solved by the present invention is to reduce wear on the top surface, particularly uneven wear, in centerless grinding while suppressing an increase in blade manufacturing cost.

[0008]

The centerless grinding blade of the present invention is a blade for supporting a workpiece between a grinding wheel and an adjustment wheel in centerless grinding,
The top surface of the blade is formed of a hard abrasive layer containing one or both of diamond abrasive grains and / or CBN abrasive grains, and the content of the abrasive grains in the hard abrasive layer is determined based on the exit side of the workpiece on the blade top surface. It is characterized in that the entrance side is made larger than that on the entrance side.

As described above, the wear of the blade top surface is greater at the inlet side of the workpiece than at the outlet side. Therefore, by increasing the abrasive content at the inlet side relative to the outlet side, uneven wear at the inlet side is reduced. Can be prevented. In this case, the increasing rate of the abrasive content from the outlet side to the inlet side may be changed stepwise, or may be changed linearly or in a curved line. The material of the blade body is not particularly limited, and commonly used iron, cemented carbide, or a combination thereof can be used.

When the abrasive content of the hard abrasive layer is changed stepwise, a plurality of chips having different abrasive content are sequentially arranged in the longitudinal direction of the blade top surface to form the hard abrasive layer. Can be. In this case, in order to suppress a sharp change in the abrasive content at the seam of the chip, the seam line of the adjacent chip is 30 to 70 with respect to the longitudinal direction of the blade top surface.
It is desirable to arrange them so that they are inclined at an angle.

[0011]

FIG. 1 is a perspective view of a blade showing an embodiment of the present invention, and FIG. 2 is a plan view showing a tip arrangement of a hard abrasive layer on the top surface of the blade.

The blade 10 of the present embodiment has a hard abrasive layer 2 formed at the tip of a main body 1 to serve as a top surface. The main body 1 is made of steel (JIS G4051 S45C), and has a length of 320 mm and a thickness of 10 mm. Hard abrasive layer 2 has width 6
2a to 2h whose upper surface is inclined in the thickness direction of the main body 1 in mm.
Are arranged in the longitudinal direction of the blade, and each of the chips 2a to 2h is arranged such that the seam line T of the adjacent chip is inclined by 60 degrees with respect to the longitudinal direction of the blade top surface.
, And the abrasive content is increased in the order of the chips 2h to 2a.

More specifically, each of the chips 2a to 2h is a hard abrasive layer made of a diamond abrasive and a metal component as a binder, and the planar shape of the chips 2b to 2g has an included angle (inclination angle) θ of 60 degrees. Is a parallelogram (diamond), and chip 2
The planar shapes of a and 2h are trapezoids having a hypotenuse of 60 degrees.

The content of diamond abrasive grains for each tip is as follows: tips 2a and 2b have an abrasive grain concentration of 200;
And 2d have an abrasive concentration of 180, chips 2e and 2f have an abrasive concentration of 160, and chips 2g and 2h have an abrasive concentration of 140. By changing the degree of concentration of the abrasive grains in the longitudinal direction of the blade top surface in this manner, the abrasion resistance becomes larger at the inlet side than at the outlet side when the workpiece advances in the direction of arrow A in FIG. In addition, uneven wear on the inlet side is prevented.

By preventing the uneven wear of the blade top surface, the vibration of the workpiece during the grinding process is reduced and the processing accuracy is improved, and the uneven wear of the grinding wheel is suppressed and the life of the grinding wheel is improved. In addition, the number of dressings is reduced, and the work efficiency is improved. Also, by reducing the concentration of abrasive grains at other portions of the blade top surface on the workpiece inlet side, it is possible to reduce the amount of expensive diamond abrasive grains used.

The above embodiment is an example of the blade of the present invention, and the present invention is not limited to the above embodiment, and the overall shape of the blade and the shape of the chip of the hard abrasive layer , The number and the like can be appropriately changed.

[Test Example] Same shape as the invention product 1 except that the blade (invention product 1) of the embodiment of the present invention shown in FIG. Blades of the material (Invention 2), the overall shape is the same as that of Invention 2 and the blade (comparative product) in which the abrasive content of each chip of the hard abrasive layer is constant and the overall shape is the same as that of Invention 2 Blade with top surface made of hard alloy tip (conventional product)
Was used to perform a grinding test of a round bar. The grinding conditions are shown below, and the test results are shown in Table 1.

Grinding conditions Workpiece: Material JIS G4401 SK-5 Dimension before grinding 15.0mmφ × 60mm Length Dimension after grinding 14.7mmφ Rotational peripheral speed: Grinding wheel 1800m / min Adjustment wheel 28m / min

[0019]

[Table 1]

As can be seen from Table 1, the life of the comparative blade is the longest in terms of the life alone. However, the blade of the comparative product has a high concentration of abrasive grains in the entire hard abrasive layer, and due to uneven wear on the inlet side of the workpiece, the life of the other parts is still life even though it is still usable It is a thing. Uneven wear on the top surface also affects the processing accuracy. The blade of the invention product 1 has the same degree of abrasive grain concentration in the hard abrasive layer on the inlet side of the workpiece as the blade of the comparative product, so that the life of the blade is almost the same, and the concentration of abrasive grains in other parts is Since the degree was low, there was no uneven wear on the top surface, thereby reducing the vibration of the workpiece and obtaining good machining accuracy. In addition, since the degree of concentration of the abrasive grains was low except at the entrance side, the amount of abrasive used was smaller than that of the comparative product, and the same life could be achieved at lower cost. Invention 2 also Invention 1
As in the above, there was no uneven wear, so good processing accuracy was obtained, but due to the difference in the hardness of the abrasive layer at the seam of each chip, a minute step was generated at the seam and interfered with the workpiece,
As a result, the seam was chipped and the life of the blade was slightly shortened. Since the top surface of the conventional product is made of a cemented carbide, the life of the blade is shorter than that of the invention products 1 and 2 and the comparison product whose top surfaces are formed by a hard abrasive layer using diamond abrasive grains.

[0021]

According to the present invention, the following effects can be obtained.

(1) The top surface of the centerless blade is formed of a hard abrasive layer containing either or both of diamond abrasive grains and CBN abrasive grains. By making the inlet side of the workpiece larger than the outlet side of the workpiece on the top surface, uneven wear on the inlet side of the workpiece can be prevented.

(2) By sequentially disposing a plurality of chips having different abrasive grain contents in the longitudinal direction of the blade top surface, the abrasive grain content of the hard abrasive layer can be reduced without manufacturing difficulty. It can be changed stepwise.

(3) The seam line between the chips having different abrasive grain contents is 30 to 70 with respect to the longitudinal direction of the blade top surface.
By arranging them so as to be inclined at an angle, it is possible to suppress a sharp change in the abrasive content at the joint of the chips.

[Brief description of the drawings]

FIG. 1 is a perspective view of a blade showing an embodiment of the present invention.

FIG. 2 is a front view of the blade of FIG. 1;

FIG. 3 is an explanatory view showing a centerless grinding process.

[Explanation of symbols]

 Reference Signs List 1 main body 2 hard abrasive layer 2a to 2h tip 10 blade 20 grinding wheel 21 adjustment wheel 22 blade 22a top surface T seam line θ included angle (inclination angle) W Workpiece

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Teiji Hirashima 210 Noritake Diamond, Tanushimaru-cho, Ukiha-gun, Fukuoka Prefecture Inside Noritake Diamond Co., Ltd. F term (reference) 3C034 AA01 BB71 DD20 3C043 AA08 CC03 DD05 DD12

Claims (3)

[Claims] 1. A blade for supporting a workpiece between a grinding wheel and an adjustment wheel in centerless grinding,
The top surface of the blade is formed of a hard abrasive layer containing one or both of diamond abrasive grains and / or CBN abrasive grains, and the content of the abrasive grains in the hard abrasive layer is determined based on the exit side of the workpiece on the blade top surface. A centerless grinding blade with a larger inlet side than that. 2. The centerless grinding according to claim 1, wherein a plurality of chips having different abrasive grain contents are sequentially arranged in the longitudinal direction of the blade top surface to change the abrasive content of the hard abrasive layer in a stepwise manner. For blades. 3. The centerless grinding blade according to claim 2, wherein the seam line of the adjacent chips is disposed so as to be inclined by 30 to 70 degrees with respect to the longitudinal direction of the blade top surface.