JPS6039511B2 - Jet injection grinding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a jet grinding method that solves the problem of deterioration in shape accuracy caused by an increase in the temperature of a workpiece (object to be ground).

Grinding involves complex processing phenomena and theoretical understanding is slow, so the ``hunch'' of skilled workers on site plays a large role.

However, in recent years, the pursuit of engineering and the demand for high precision and high efficiency have increased rapidly, and theoretical studies and new technological developments are being actively carried out from various fields.

One of the new technologies is the jet liquid grinding method. As shown in Fig. 1, this is done by injecting grinding fluid 5 at high pressure from a medium-thick slit 4 provided in a nozzle 3 to the contact point (grinding point) between the grinding wheel 1 and the workpiece 2. , which attempts to actively remove the grinding heat that is an impediment to increasing the efficiency of grinding, and the following additional effects can be expected.

'E Prevention of deterioration of product surface properties (structure, residual stress, etc.). '.

} Prevents dimensional accuracy from decreasing due to grinding heat. Shiichi: Extending the life of the whetstone. However, there are various obstacles on the way to practical application of this grinding method.

One of these is the problem of reduced precision in product shape due to workpiece escape caused by jet impact.

This will be explained with reference to FIG. Note that for convenience of explanation, the grindstone is moved, but in reality, the workpiece moves in the direction of the grindstone axis. In the jet injection grinding method, grinding fluid 5
is injected at high pressure (for example, in Tsubaki Seki No. 48-7469y, the injection pressure is 2k9/m or more), a force Fj is generated on the workpiece 2 or the grinding wheel 1 to separate them. If the rigidity around the workpiece 2 and one axis of the grinding wheel is K, and the grinding back force is Fr, then the relief amount of the workpiece 2 is d
W is different from the d side of the normal liquid injection method, which is the d side of the liquid injection method, and the d side of the jet liquid injection method, which means that the amount of escape increases in the latter case.

This escape of the workpiece 2 has a negative effect on the shape accuracy of the product, but especially in traverse grinding (grinding that applies feed in the direction of the grinding wheel axis), as shown in Figure 2A, the edge of the workpiece 2 2 of 1/It is necessary to grind the work 2 again after missing the mirror land, and since the amount of relief of the work 2 is different between the edge and the center, the surface becomes convex in the middle,
Shape accuracy decreases.

Therefore, generally speaking, no depth of cut is made at the end of grinding.
Only a portion corresponding to the relief amount of the workpiece 2 is removed, that is, the surface is ground until dW&0→Fr20 to obtain a predetermined shape accuracy and surface roughness.

This is called spark-out, but in the jet injection grinding method, even if the grinding speed is Fr20, plowing of grain occurs at the ends and thighs of the workpiece 2, reducing shape accuracy.

In order to prevent this decrease and fully utilize the effect of the jet injection method, it is necessary to reduce the thickness of the slit 4 of the nozzle 3 to reduce the gap between the grinding points (the grinding wheel is a foam-containing abrasive grain aggregate). It is effective to allow all of the grinding fluid to pass through the gap (because of this, there is a gap) and to prevent the fluid from scattering above or to the sides of the grinding point.

However, a problem arises here.

This is because the overall temperature of the workpiece 2 increases, and in this case, the shape accuracy also decreases. That is, when looking at the flow of the grinding fluid injected from the nozzle 3, normally, as shown in Fig. 3, one flow 5a passes through the gap between the grinding wheel 1 and the workpiece 2 and removes the heat at the grinding point. However, the other flow 5b cannot completely enter the above-mentioned gap and flows down along the surface of the workpiece 2 while cooling it.

Therefore, if the thickness of the slit 4 of the nozzle 3 is narrowed as described above, there will be almost no grinding fluid along the surface of the workpiece 2, which will increase the temperature of the workpiece 2 and reduce the shape accuracy of the product. do. The present invention provides a jet grinding method that suppresses the temperature rise of the workpiece and solves the problem of deterioration in shape accuracy caused by this.
When grinding is performed by spraying a grinding fluid onto the contact point between a grindstone and a workpiece, the cooling fluid is sprayed onto the contact point and, separately from the contact point, the cooling fluid is sprayed directly onto the surface of the workpiece. It is characterized by supplementary dripping of cooling grinding fluid.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

In FIG. 4, 1 is a grindstone, 2 is a workpiece, and a grinding fluid 5 is injected from a slit 4 of a nozzle 3 to the contact point between them. In this invention, a workpiece cooling nozzle 6 is provided separately from the nozzle 3, and the grinding fluid 7 is injected onto the surface of the workpiece 2 from there to cool the entire workpiece 2. Unlike the grinding liquid 5 of the nozzle 3, this grinding liquid 7 only needs to drip onto the surface of the workpiece 2, regardless of the injection pressure. The structure of the nozzles 3 and 6 is preferably as shown in FIG. 5, for example.

Although the liquid supply systems are the same in this case, they may be different. First, to explain the nozzle 3, the nozzle body 3
Place the base plate 3b on the surface a, and bolt the nozzle cover 3c to it. 3d is a pre-pressure chamber to adjust the flow of liquid, 3e
is a land, and it is desirable that the surface roughness be sufficiently smooth, for example, less than 1.

With the above, the middle 1, with the thickness equal to the thickness of the base plate 3b,
A nozzle 3 with a slit 4 is formed. On the other hand, the nozzle 6 may be of the shape of a crushed pipe, for example, and its base is branched from the base of the nozzle 3, and a liquid volume adjustment valve 6a is attached thereto.

After being pressurized by a pump (not shown), the grinding fluid enters the nozzle 3 from A, and is injected in the direction B through the pre-pressure chamber 3e and the slit 4, and the other through the valve 6a.
It flows out from the tip of the nozzle 6 in the direction C. When the jet injection cutting method is carried out using these nozzles 3 and 6, the following effects can be obtained.

The above table shows the experimental results comparing one embodiment of the present invention with a jet liquid grinding method that does not cool the workpiece (Comparative Examples 1 and 2) and a conventional ordinary liquid injection method.
6 peaks 8V (3000×18 medium), SUJ2 is used for work 2, and the jet pressure is 8.2k9/me. According to the results in the table, for example, a nozzle with a slit thickness of 0.5 and a nozzle with a slit thickness of 0.2 have almost the same cooling effect at the grinding point, that is, the depth of cut when burns occur is almost the same.
The nozzle on the 0.2 side is F, which reduces the shape accuracy of the workpiece.
j is 1/2.5 times that of a 0.5 sail nozzle, which is advantageous in terms of shape accuracy.

However, the overall temperature of the workpiece is about the same as that of a 0.5mm nozzle, and from this point the shape accuracy may deteriorate. Therefore, as shown in Example 1, when the workpiece cooling nozzle 6 is used, the overall temperature of the workpiece is reduced to the same level as in Comparative Example 1 of willow with a slit thickness of 0.5, and the shape accuracy due to the temperature rise of the workpiece is reduced. The decline can be prevented.

Note that the present invention is not limited to the embodiments described above, and various embodiments can be adopted without changing the gist. It is also applicable to grinding methods other than the traverse method. In summary, in this invention, while injecting cooling grinding fluid to the grinding point,
Separately from this, cooling grinding fluid is poured directly onto the workpiece surface as an auxiliary, so there is less deterioration in shape accuracy caused by Fj, less thermal damage at the grinding point, and an increase in the overall temperature of the workpiece. It is possible to implement the jet liquid grinding method with less deterioration in shape accuracy based on the method.

Brief explanation of the drawings Fig. 1 is a schematic process diagram of the conventional jet injection grinding method, Fig. 2 A is an explanatory diagram of the phenomenon of workpiece escape that occurs in the same grinding method, and the opening in the figure is an illustration of the phenomenon caused by the same phenomenon. FIG. 3 is a block diagram showing the surface shape of a workpiece whose shape accuracy has decreased due to the grinding process, and FIG. 3 is a process diagram illustrating the flow path of the grinding fluid in FIG.

FIG. 4 is a process diagram illustrating the flow path of the grinding fluid in an embodiment of the present invention, and FIG. 5 is an exploded perspective view showing an example of a nozzle for the grinding fluid. 1...Whetstone, 21...
... Workpiece, 3... Nozzle (for cooling the grinding point), 4.
...Slit, 5,7... Grinding fluid, 6...
...Nozzle (for cooling the workpiece). Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. When grinding is performed by injecting a grinding fluid to the contact point between the grindstone and the workpiece, while injecting the cooling grinding fluid to the contact point, and separately from the contact point, apply cooling fluid directly to the surface of the workpiece. A jet injection grinding method characterized by supplementary pouring of grinding fluid.