JPH1133917A - Super abrasive grain grinding wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain the abrasive grain holding force, and to maintain excellent abrasive grain performance by specifying the coated amount of the abrasive grains of a super abrasive grains grinding wheel used for constant pressurization type double head grinding at a specified velocity of grinding wheel, at a specified ratio. SOLUTION: An abrasive grain layer, which is formed of diamond super abrasive grains 13 and resin bond 14, is fixed to a surface of a disc-shaped base of cast material. At the time of grinding work at 100 m/min of velocity of a grinding wheel at the most outside thereof, which is remarkably lower in comparison with a general grinding wheel, mechanical impact for generating the loose-out of the abrasive grains is small, and the abrasive grains, which are worn and flattened, is not fallen, and lowering of the grinding performance is easy to be generated. At this stage, quantity of nickel coating 15 in relation to the whole of weight of the abrasive grains 13, which includes the coating material, is set at 15-35%. With this composition, the abrasive grains 13 fall at a stage that a sharp part of the tip of the abrasive grains 13 are worn and flattened, and a new abrasive grain 13 appear. As a result, excellent grinding performance can be maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a superabrasive grindstone, and more particularly to a superabrasive grindstone used for double-head grinding of a constant pressure pressurizing method at a grindstone peripheral speed of 100 m / min or less.

[0002]

2. Description of the Related Art In a super-abrasive grinding wheel made of diamond or CBN abrasive, depending on the type of a bonding material (bond),
There are metal (M), resinoid (B), vitrified (V), and electrodeposited (P) grinding wheels, and the most suitable grinding wheel is selected and used depending on the type of workpiece and the grinding mode.

[0003] Among them, a resinoid bonded grindstone using a resin as a binder is mainly manufactured by mixing a phenolic resin-based resinoid and diamond abrasive grains and hot-pressing them. Resinoid bond whetstones are more elastic than whetstones using other bonds,
Although it is suitable for finishing when processing quality such as ground surface roughness is required, there is a drawback in that the abrasive holding power is inferior to metal bond whetstones.

For this reason, when used for hard-to-cut materials such as cemented carbides, cermet tools, and ceramic tools, which require a particularly sharp abrasive cutting edge, nickel is applied to the surface of the abrasive to prevent the abrasive from falling off. Metal coating such as is applied.

[0005] By applying a metal coating to the surface of the abrasive grains, the bonding area between the bond and the abrasive grains is increased, the strength near the abrasive grains is increased, and bond deterioration due to the heat generated by the abrasive grains is prevented. As a result, the holding power of the abrasive grains can be increased. Also, the greater the amount of metal coating, the higher the abrasive grain holding power.

A technique for applying a metal coating to the surface of an abrasive grain as described above is disclosed in, for example, JP-A-53-30095.
JP-A-53-34191 and JP-A-56-3182.
And Japanese Patent Application Laid-Open No. 61-178180.

[0007] The amount of the metal coating applied to the surface of the abrasive grains is determined so as to exhibit the above-mentioned predetermined effect, and is usually about 55% by weight of the total weight of the abrasive grains including the coating material. % Are used. If the amount of the metal coating is too small, it is impossible to obtain a predetermined abrasive holding power, and if the amount of the metal coating is too large, the grinding resistance becomes large. Therefore, usually about 55% by weight is used as described above. ing.

[0008]

However, in the case of using a superabrasive grindstone having a metal coating on the surface of the abrasive grain, there is no problem in general grinding with a grindstone peripheral speed of about 1500 to 3000 m / min. In particular, in double-head grinding with a constant-pressure pressurization method in which the grinding wheel peripheral speed is 100 m / min or less, there is a problem that a material having good grinding performance at the beginning gradually deteriorates in sharpness.

Therefore, the problem to be solved in the present invention is:
In particular, in a super-abrasive grindstone used for double-head grinding of a constant pressure pressurization method with a grinding wheel peripheral speed of 100 m / min or less, a means capable of maintaining excellent grinding performance while maintaining abrasive holding force is provided. Is to do.

[0010]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems. As a result, since the time at which the abrasive grains fall off is correlated with the peripheral speed of the grinding wheel, the coating amount of the metal coating is specified. By setting the range, it is presumed that it is possible to maintain excellent abrasive performance while maintaining the abrasive grain holding force, and as a result of experiments, the present invention has been completed.

That is, the present invention relates to a super-abrasive grindstone having abrasive grains whose surfaces are coated with a metal and used for double-head grinding of a constant-pressure pressing method at a grinding wheel peripheral speed of 100 m / min or less. The metal coating amount is 15 to 35% by weight of the total weight of the abrasive grains including the coating material.

[0012] In the double-head grinding of the constant pressure pressurizing method mainly used for double-sided machining of a cutting tip, the peripheral speed of the grinding wheel is 100 m / min or less and the peripheral speed of the grinding wheel is 1500
It is only about 3 to 7% of the peripheral speed of the grinding wheel in general grinding at about 3000 m / min. Therefore, the conventional metal coating amount as described above may adversely affect the grinding performance.

That is, in order for the superabrasive grindstone to always maintain good grinding performance, it is necessary that the worn abrasive grains fall off at an appropriate time and new abrasive grains appear on the surface. Although indispensable, as described above, the detachment of the abrasive grains has a correlation with the coating amount of the metal coating applied to the surface of the abrasive grains.

In general, the preferred time for the abrasive grains to fall off is when the abrasive grains have moderately worn and the sharpness has deteriorated.
If it comes off earlier than this, the whetstone will be severely worn, resulting in poor durability. On the other hand, if the abrasive grains are in a state of large abrasion at the tip and do not fall off even in a state of reduced sharpness, the wear of the grindstone is reduced, but the sharpness is extremely reduced.

As described above, when the peripheral speed of the grinding wheel is about 1500 to 3000 m / min as in general grinding, the coating amount of the metal coating is about 55%, and there is no problem that the abrasive grains fall off at an appropriate time. . However, in the grinding process in which the peripheral speed of the outermost periphery of the grindstone is 100 m / min, which is extremely slow as compared with a general grindstone, there is little mechanical impact to induce grain shedding, and even when the abrasive grains are worn and flattened. The abrasive grains do not fall off, leading to a decrease in sharpness.

Based on the above presumption, the inventor of the present invention varied the amount of the metal coating and, based on the relationship between sharpness and wear of the grindstone, determined that the above-described appropriate metal which maintained the abrasive holding force and maintained excellent grinding performance was maintained. The amount of coat was found.

Here, as the metal for the metal coating, nickel, copper, cobalt, titanium or the like can be used, but nickel is particularly desirable from the viewpoint of balance between sharpness and life, and coating cost.

[0018]

FIG. 1 is a perspective view of a superabrasive grindstone according to an embodiment of the present invention, and FIG. 2 is a schematic view showing an abrasive layer surface portion of the superabrasive grindstone of FIG. a) is the state before use,
(B) shows a worn state during use.

In FIG. 1, reference numeral 10 denotes a disk-shaped base metal made of a casting, 11 denotes an abrasive layer made of diamond super-abrasive grains fixed to one surface of the base metal 10 and a resin bond, and 12 denotes a base metal 1.
0 and a mounting through hole formed in the center of the abrasive layer 11. The abrasive layer 11 is formed by bonding abrasive grains 13 having a nickel coating amount of 30% by weight with a resin bond 14. In use, a grindstone is attached to a rotating shaft of a grinder such as a parallel plane honing grinder, and the grindstone layer 11 is slid while being pressed against the work surface to process the work surface.

The state of the surface layer portion of the abrasive grain layer is such that, before use or immediately after dressing, as shown in FIG. 2A, the abrasive grains 13 coated with nickel 15 are exposed on the surface (in this case, The nickel coating at the tip is considerably removed by sharpening.), The abrasive grains 13 exposed on the surface by use
Wears, as shown in FIG. 2 (b), the sharp portion at the tip of the abrasive grain 13 becomes flat, and the sharpness decreases. At this point, in the conventional grindstone having a large amount of nickel coating, the abrasive grains are hard to fall off, so that the state of sharpness decreases for a long time. As a result, the abrasive grains 13 fall off and new abrasive grains appear on the surface, so that good sharpness is maintained.

[0021]

EXAMPLES In order to confirm the effects of the present invention, in order to confirm the effects of the present invention, the grindstone of the above embodiment (the present invention), a grindstone without nickel coating (comparative product 1), and a 55% by weight nickel-coated grindstone as in the prior art (comparative) A processing experiment was performed using the product 2). The experimental conditions are shown below.

Grinding machine: Parallel plane honing grinder Grinding wheel rotation speed: 60 rpm Grinding wheel peripheral speed: 28 to 66 m / min Grinding stone: Dimension 350 ^D × 45 ^T × 145 ^H × 100 ^W mm Diamond abrasive grain Grain size # 270 Concentration 75 Bonding Material Resin bond Work material: Cutting tip made of silicon nitride ceramic Work material size: 13.2 × 13.2 × 5.2 ^T mm Work material grinding size: 0.4 mm Number of batches processed: 20

In this grinding method, the sharpness is the best immediately after sharpening, and the sharpness gradually decreases with an increase in the amount of grinding. Therefore, when the processing time of one batch exceeds 300 seconds, the sharpness reduction point is determined. Thereafter, the method of restarting the grinding was repeated three times, and the total number of work materials that could be processed and the amount of wheel wear were compared. Table 1 shows the results.

[0024]

[Table 1]

From the experimental results, it was confirmed that the grindstone of the product of the present invention had a large total number of processed pieces and relatively little grindstone wear. If there is no nickel coating or the coating amount is too small, the total number of processed parts is small and the wear of the grindstone increases. If the nickel coating amount is too large, the grinding wheel wear will be improved,
The total number of processed parts is greatly reduced. The optimum range of the nickel coating amount with a large total processing number and little grinding wheel wear was 15 to 35% by weight of the total weight of the abrasive grains including the coating material.

[0026]

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

(1) In the grinding process in which the peripheral speed of the grinding wheel is slow,
Good sharpness is maintained because the worn abrasive grains fall off moderately and new abrasive grains appear on the surface.

(2) Since sharpness after dressing is maintained, processing efficiency is improved.

(3) By reducing the number of dressings,
Grinding wheel wear due to sharpening is reduced, and the grinding wheel life is improved.

[Brief description of the drawings]

FIG. 1 is a perspective view of a superabrasive grinding wheel according to an embodiment of the present invention.

FIGS. 2A and 2B are schematic diagrams showing a surface layer portion of an abrasive grain layer of the superabrasive grinding wheel of FIG. 1, wherein FIG. 2A shows a state before use and FIG. 2B shows a worn state during use.

[Explanation of symbols]

 Reference Signs List 10 base metal 11 abrasive layer 12 mounting through hole 13 abrasive 14 resin bond 15 nickel coating

Claims (2)

[Claims] 1. A super-abrasive grindstone having abrasive grains whose surfaces are metal-coated and used for double-head grinding with a constant pressure pressurization method at a grinding wheel peripheral speed of 100 m / min or less, wherein the metal coating amount of the abrasive grains Is 15 to 35% by weight of the total weight of the abrasive grains including the coating material. 2. The superabrasive grinding wheel according to claim 1, wherein said metal is nickel.