JPS5976771A - Dressing device for grindstone - Google Patents

Abstract

PURPOSE:To permit to control the protruding amount of cutting edge by a method wherein only the abrasive grain binder of a grindstone of an electro-conductive material is removed by a chemical etching method. CONSTITUTION:Only the binder of the abrasive grain of the grindstone 9, made of the electro-conductive material 19, is removed selectively in the device consisting of a fixing plate 10, holding the grindstone 9 and being connected with a rotating shaft 11, a tank 15, storing chemical reacting liquid 14 for dipping the grindstone 9, a heater 15, heating the chemical reacting liquid 14 to a given temperature and keeping the temperature, and a mixing fan 17. According to this method, the protruding amount of the diamond cutting edge from the layer of the binder may be controlled and a good sharpness may be continued for a long period of time without being loaded even in case of deep groove working.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to the dressing of thin-blade sintered metal-bonded diamond grinding wheels intended for cutting and grooving hard and brittle materials such as ferrite, quartz, sapphire, and various semiconductor materials. It is related to the device.

Conventional structure and its problems Thin-blade sintered Rubondo diamond grindstones are used for trunk processing of various magnetic heads, cutting and grooving of tuning fork crystal units for wristwatches, etc. Due to strict requirements for geometrical accuracy and a damaged layer under the machined surface, fine diamond abrasive grains with an abrasive grain size of #1000 or more are often used. However, when this level of fine abrasive grains are used, the grinding wheel tends to become loose, especially due to clogging of the abrasive grains on the side of the grinding wheel.
After being used for a short time, the sharpness deteriorates, making it impossible to continue cutting operations.

As yet, there has been no effective dressing method for a grindstone once it has reached the above state, so the grindstone has been discarded even though it has many diamond layers inside.

The specific structure of the conventional dressing device for a grindstone will be described below. FIG. 1 shows a first conventional embodiment. 1st
In the figure, 1 is a thin-blade sintered metal-bonded diamond grindstone, 2 is a temporary grindstone fixing plate for connecting the grindstone to a rotating shaft 3, and 4 is a workpiece.

First, a new grindstone is connected to the rotating shaft 3 via the grindstone fixing plate 2, and then the grindstone 1 is rotated at a predetermined circumferential speed. Next, the grindstone 1 is cut into the workpiece 4 to form dummy grooves 6 and 6. At this time, the outer circumferential runout and lateral runout of the grindstone are corrected to some extent, and the uneven amount of abrasive grain protrusion on the surface of the grindstone is also smoothed out. When the shape accuracy and dimensional accuracy of the machined groove are stabilized by dummy machining the actual workpiece in this way, the actual machining starts from step 7 onwards.

The method of dressing the grindstone by making a dummy cut on the product is not a good idea because it has the following drawbacks.

1. The material loss of the product (processed material) is large.

2. This dressing method does not provide stable machining accuracy.

3. Since redressing is not possible, the life of the grinding wheel cannot be extended.

Next, FIGS. 2(al) and (b) show the configuration diagram of the second conventional embodiment. First, in FIG. The fixing plate 4 that connects the grindstone has a GC inside it.
It is a dressing rod containing grinding abrasive grains such as WA. First, the grindstone 1 is rotated at a predetermined circumferential speed, and the dressing rod 4 is cut in the direction X perpendicular to the rotating shaft 3 to dress the outer circumferential surface 6 of the grindstone. In Fig. 2 (false), the dressing rod 4 cut into the grindstone 1 is viewed from a direction perpendicular to the rotating shaft 3 (second appearance). Next, while rotating the grindstone 1, the dressing rod 4 is slightly moved left and right in the direction Y parallel to the rotating shaft 3, thereby dressing the outer peripheral blade side surface 6 of the grindstone 1. However, in the above configuration, the thickness of the grinding wheel 1 is thin,
Due to its lack of rigidity, when the dressing rod 4 is inserted into the Y direction of the side surface of the outer peripheral blade of the grinding wheel 1, the grinding wheel 1 escapes in the direction of the cut, resulting in a dressing effect on the side surface of the peripheral blade of the grinding wheel. It has already been confirmed that the
Abrasive grains tend to fall off during dressing, which is one of the factors that shortens the life of the grindstone.

Purpose of the Invention In view of the above-mentioned drawbacks, the present invention aims to improve the dressing effect of the side surface of the outer peripheral edge of the grindstone, thereby improving the machining dimensional accuracy of products that particularly require deep groove machining, and further extending the life of the grindstone. The purpose is to

Structure of the Invention The present invention includes a grindstone, a fixed plate that holds the grindstone and connects it to a rotating shaft, a drive motor that rotates the rotating shaft, a chemical reaction liquid that immerses the grindstone, a tank that stores the same, In a device consisting of a heater for heating and holding a chemical reaction solution at a constant temperature and a stirring structure, the principle of chemical etching is applied to select only the binder of the abrasive grains of the grinding wheel made of conductive material. This has the special effect of controlling the amount of protrusion of the diamond cutting edge from the binder layer and maintaining good cutting quality for a long time without clogging, even when machining deep grooves. has.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 3 shows an embodiment of the present invention relating to the dressing device to which the principle of chemical etching is applied.

The dressing device includes a grinding wheel 9 and a rotating shaft 1 that holds the grinding wheel 9.
1, a drive motor 12 and a belt 13 that rotate the rotating shaft, a chemical reaction liquid 14 in which the grindstone is immersed, a tank 16 that stores this, and a tank 16 that keeps the chemical reaction liquid at a constant temperature. It is composed of a heater 16 for heating and holding, a power source 16, and a stirring device 17. In the apparatus configured as described above, the chemical reaction liquid 14 in the tank 15 is heated to an appropriate temperature by the heater 16 in advance, and the inside of the tank 16 is sufficiently stirred by the stirring device 17 to maintain a uniform temperature distribution therein. I'll keep it.

Next, the grindstone 9 is immersed in the chemical reaction liquid 14 in the tank 15,
By rotating the rotary shaft 11 by the drive motor 12 and belt 13, the grindstone 9 connected thereto by the fixed plate 1o rotates at a predetermined circumferential speed. At this time, the rotating shaft 11 may be installed vertically in the tank 16 as shown in the figure, or may be installed horizontally. By performing the above processing, the binder that binds the abrasive grains, which is generally made of copper-based metal in the case of thin-blade sintered metal pound grinding wheels like this example, is removed from the chemical reaction solution. As the diamond abrasive grains, which are poor conductors, remain as they are, the diamond abrasive grains gradually protrude from the surface of the whetstone. As an example of processing conditions, 70
There is processing in sulfuric acid solution at ℃. Figure 4(a), 11)
) shows the protrusion of abrasive grains under the above processing conditions.

In Fig. 4(a), 18 is a diamond abrasive grain, and 19 is a diamond abrasive grain.
is a conductive abrasive grain binder, and as time passes in the sulfuric acid solution, only the conductive binder undergoes selective chemical corrosion, and the diamond abrasive grains 18 protrude from the surface of the binder. . Further, FIG. 4 ($) shows the relationship between the abrasive grain protrusion amount and the chemical etching time, and there is a vague linear relationship between the two. Therefore, under certain processing conditions,
By accurately managing the etching time, it is possible to control the amount of abrasive grains protruding from the surface of the grindstone.

Next, when deep groove machining is performed using a thin-blade sintered metal pound diamond grinding wheel that adopts the dressing method shown in this example, the machining accuracy and the grinding wheel life are compared with the above-mentioned grindstone that uses the conventional dressing method. The effect on this will be explained.

In FIG. 5, 2o is the cross section of the cutting groove, 21 is the cross section of the workpiece, W is the width of the cutting groove, L is the depth of the cutting groove, and Δ
L is a symbol representing the amount of deviation between the perpendicular from the surface of the workpiece and the center line of the cutting groove. In FIG. 6, W/L-0,
The relationship between the machining time T and the cutting groove width W in the case of No. 04 is shown by comparing the conventional example and the example according to the present invention. As is clear from FIG. 6, the grindstone employing the dressing method of this embodiment can maintain higher groove width machining accuracy. Next, in FIG. 7, the machining accuracy of the straightness ΔL/L of the cutting groove is shown for the grinding wheel adopting the dressing method of this example,
This is shown in comparison with a grindstone that uses a conventional dressing method. It can be seen that the grindstone employing the dressing device of this example has better straightness accuracy than the grindstone employing the conventional dressing method.

Next, FIG. 8 shows the results of an evaluation experiment regarding the life of the grindstone. When the conventional dressing method is adopted, the dressing effect is not sufficient, and the grinding resistance does not decrease due to dressing, but rather continues to increase and reaches the end of its life after a relatively short period of time. On the other hand, the dressing effect of this example is clear, and it can be seen that immediately after dressing, the grinding resistance is reduced due to the dressing effect, and the life of the grindstone is greatly extended.

Effects of the Invention As described above, according to the present invention, it is possible to control with high precision the amount of protrusion of the diamond abrasive grains inherent in the side surface of the peripheral blade of a thin-blade sintered metal pound diamond grinding wheel from the grinding wheel surface, which is effective. Due to the dressing effect, especially
In deep groove machining, a significant improvement in machining accuracy can be obtained, and its practical effects are significant.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a conventional dressing device, FIGS. 2(a) and (b) are a front view and a partially sectional side view showing other conventional dressing devices, respectively, and FIG. 3 is a perspective view showing a conventional dressing device. A configuration diagram of a dressing device in one embodiment, FIG.
Figure Φ) is a graph showing the effect of the dressing device according to the present invention on controlling the abrasive grain protrusion amount, Figure 6 is a cross-sectional view of the cutting groove, and Figure 6 is a graph showing the effect of the dressing device according to the present invention on the cutting groove width accuracy. FIG. 7 is a graph showing the effect of the dressing device according to the present invention on the straightness accuracy of the cutting groove, and FIG. 8 is a graph showing the effect of the dressing device according to the present invention on the life of the grinding wheel. 9...Whetstone, 10...Fixing plate, 11.
... Rotating shaft, 12 ... Drive motor, 13
...Belt, 14...Chemical reaction liquid, 1
5...tank, 16...power supply, 17...
...For stirring. Figure 2 Figure 3 Figure 4 I and ζ rnin ) Figure 8 16 kakus (mεn2

Claims (1)

[Claims] A thin-blade sintered metal-bond diamond grinding wheel is made of abrasive grains made of defective conductor diamond and a conductive binder that binds the abrasive grains, and this thin-blade sintered metal-bond diamond grinding wheel is held and rotated around a rotating shaft. a fixing plate that can be installed, a drive unit that drives the rotating shaft, a chemical reaction liquid that can immerse the grindstone and corrode only the binder, and a tank that stores this chemical reaction liquid. A grindstone dressing device comprising a stirrer and a heater for uniformly heating the chemical reaction liquid.