JPH04322969A - Tooling-dressing method of diamond grinding wheel - Google Patents

Abstract

PURPOSE:To provide a novel method, capable of tooling and dressing a diamond grinding wheel on a grinding machine at high efficiency. CONSTITUTION:In two diamond grinding wheels, there is differentiated rupture strength against the extent of compressive force in a grain bonding layer, and both these wheels are made contact with each other in a state of being rotated. The bonding layer lower in the strength is separated by dint of the compressive force being produced in a contact position, thus dressing takes place.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for truing and/or dressing a diamond grinding wheel with high efficiency.

0002

[Prior art and its problems] Conventional grinding wheels using alumina or silicon carbide abrasive grains can be trued and/or dressed easily and with high accuracy on a grinding machine using a diamond dresser. Truing and dressing of CBN grinding wheels is also possible when using a rotary dresser. Processing using these grindstones achieves stable grindstone performance and long dresser life, making mass production processing and full-form processing possible through grinding.

On the other hand, when truing or dressing a diamond grindstone with diamond abrasive grains bonded to it using a diamond dresser, the wear of the dresser is large because the cutting edges are made of materials with the same hardness, and the contact between the two increases. There is a problem in that severe rubbing occurs in the areas where the actual cutting depth is extremely small.

FIG. 3(a) shows the amount of machining relative to the cutting rate when a diamond grinding wheel using a resin bond is dressed with a diamond rotary dresser, and the wear amount of the dresser is determined by the amount of dressing of the grinding wheel. are occurring in the same amount. Moreover, about 90% of the total cutting depth is uncut due to elastic deformation, and the amount of dressing actually obtained is extremely small.

[0005] For this reason, conventional truing and dressing operations for diamond grinding wheels have been carried out without using a diamond dresser, such as by bringing a non-diamond grinding wheel into contact and scraping off only the bonding layer, or by using electrical discharge machining or electrolytic action. It is taken. However, in such a method,
There are problems such as the work is extremely time consuming, dressing on the grinding machine is difficult, and the surface shape and runout of the diamond grindstone cannot be precisely formed.

[0006] In this way, the conventional diamond grinding wheel
It is difficult to form a highly accurate grindstone surface by truing, and in order to obtain surface quality such as surface roughness of the workpiece, it is necessary to finely adjust the particle size of the abrasive grains of the diamond grindstone. That is, in order to obtain good surface quality, it is necessary to use diamond abrasive grains with a fine particle size.

[0007] However, such a reduction in the diameter of the abrasive grains inevitably leads to a reduction in machining efficiency and a shortening of the life of the grinding wheel, which is a factor that makes it difficult to apply diamond grinding wheels to mass production processing by grinding.

[0008] In addition, poor grinding wheel surface accuracy due to truing and dressing makes it difficult to use diamond grinding wheels for profile grinding, which requires high shape accuracy and run-out accuracy.
There are also problems that make highly efficient profile grinding with a diamond grinding wheel difficult.

The present invention was made in view of the above-mentioned problems, and it is possible to perform truing and dressing of a diamond grinding wheel with high efficiency and precision, making it possible to apply the diamond grinding wheel to mass production processing and profile grinding. The purpose is to provide a method to do so.

0010

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a method in which two diamond grinding wheels whose abrasive grain bonding layers have different fracture strengths against compressive force are brought into contact while being rotated relative to each other. was adopted.

[0011] In a diamond dresser, the diamond abrasive grains are strongly bound together by metal bonding, electroplating, etc., so considering the processing conditions for the whetstone, the abrasive grains do not fall off from the bonding layer like in normal grinding work. Processing is performed by applying compressive force to the grinding wheel from a dresser, and the compressive force destroys the bonding layer of the grinding wheel or separates the bonding layer and the abrasive grains. it is conceivable that.

[0012] In other words, the reason why diamond grinding wheels using conventional resin bonds or metal bonds could hardly be trued by a diamond dresser is that the abrasive bonding layer formed by resin bonds or metal bonds deforms elastically when compressive force is applied. alone, not destroyed or separated,
This is thought to be because the structure is such that it cannot be processed using the compressive force from the dresser.

On the other hand, by creating a difference in the fracture strength of the bonding layer against compressive force between the two diamond grinding wheels,
By bringing the two grindstones into contact and applying compressive force, the bonding layer of one of the grindstones can be broken and separated from the abrasive grains due to the difference in breaking strength. In this case, by replacing a diamond grinding wheel with a high breaking strength with a diamond dresser and a grinding wheel with a small breaking strength with the diamond grinding wheel to be processed, the diamond grinding wheel can be trued with high efficiency by the mechanical contact method using the dresser.

In the above method, the breaking strength of the bonding layer against compressive force is determined by the hardness and transverse rupture strength between the bonding layers. In other words, the bonding layer of a diamond grinding wheel with low breaking strength (hereinafter simply referred to as a diamond grinding wheel) is made to have a higher hardness than the bonding layer of a diamond grinding wheel with high breaking strength that acts as a cutting tool (hereinafter referred to as a diamond dresser). When the force is set low, the strength at which the bonding layer of the diamond grinding wheel undergoes plastic failure due to compressive force can be significantly reduced compared to the bonding layer of the dresser, and high machining efficiency can be obtained.

In addition to the above characteristics, if the bonding layers of the diamond grinding wheel and diamond dresser are both made of materials with high Young's modulus, the elastic deformation of both bonding layers when compressive force is applied is reduced. be able to. Therefore, the uncut portion due to elastic deformation as shown in FIG. 3A can be greatly reduced, and highly efficient and highly accurate machining can be performed.

In order to most effectively obtain the properties of the bonding layer described above, the main component of the bonding layer of the diamond grinding wheel should be made of glass, and the main component of the bonding layer of the diamond dresser should be made of metal bond or electroplated. It is best to use a metallic material such as. That is, both glassy and metallic bonding layers have a high Young's modulus, and the above-mentioned difference in breaking strength can be easily imparted between them. On the other hand, resin bonding layers such as conventional resin bonds have large elastic deformations due to their low Young's modulus, and in addition, it is difficult to adjust the breaking strength against compressive force. Processing that can significantly change the fracture strength and Young's modulus is required.

[0017] In addition, in the conventional bonding layer formed by resin bonding or metal bonding, as shown in Fig. 1b, the spaces between the abrasive grains 1 are all filled with the bond 2, and the surface is trued as shown by the line y. However, the structure is such that the abrasive grains 1 and the bond 2 are flush with each other, and the diamond abrasive grains 1 cannot act as a cutting edge. Therefore, after truing, it was necessary to perform dressing again to make the abrasive grains 1 protrude from the bond 2. On the other hand, as shown in FIG. 1a, if a large number of pores 3 are uniformly contained inside the bonding layer, the diamond abrasive grains 1 can be transferred to the bond 2 by simply truing the surface of the grinding wheel as shown by the line x. A rake surface protrudes from the surface and can form a cutting edge. In other words, it becomes a structure that allows dressing.

In order to uniformly form pores in the bonding layer as described above, it is preferable that the main component of the bond be glassy. That is, when diamond abrasive grains are mixed with a bond mainly composed of glass powder or the like, and the bond is melted to bond the abrasive grains, the glassy bond 2 will bond to the abrasive grains 1 due to surface tension, as shown in FIG. 1a. Vitrification concentrates on the contact areas between the abrasives and the surfaces of the abrasive grains, and a large number of pores 3 are formed inside.

As a specific example, the bond is a mixture of glass powder or silicate mineral powder, SiC or Al2O3 powder as a filler, and a pore-forming material made of wax or heat sublimation material; After diamond abrasive grains are mixed into the bond, the bond is fired to a temperature higher than that at which the bond melts and becomes vitrified to form a bonding layer. In this case, it is preferable to mix the filler in an amount of 7-85% by weight and the pore-forming material in an amount of 0-40% by weight based on the weight of the entire bond. As a result, the bonding layer can contain pores in a range of 5 to 45% by volume, and high dressing processability can be obtained.

[0020] On the other hand, the processing conditions for performing truing and dressing using a diamond grinding wheel and a diamond dresser having a bonding layer with the above-described structure need to be limited in consideration of wear of the dresser and the influence of processing heat. There is a need to do this under certain conditions. The following is
Recommended conditions for processing whetstones using a diamond rotary dresser are shown below.

[0021] The dressing direction is set so that the diamond grindstone and the rotary dresser are in the same direction at the point of contact.

■ The circumferential speeds of the grindstone and the dresser are in the range of 0<a<10 when the circumferential speed ratio (a) of both is taken with the circumferential speed of the grindstone as the denominator and the circumferential speed of the dresser as the numerator. Set to .

■ When performing truing and dressing by traversing the rotary dresser (moves laterally with respect to the grinding wheel surface) as shown in FIG. 2a, one of the dressers
The depth of cut per pass is 1 to 10 μm, and the traverse amount (F) of the dresser per rotation of the grinding wheel is F = (0.01 to 10 μm), where the contact width of the dresser to the grinding wheel is (b)
The range is 0.02)×b・μm/rev.

[0024] When using a rotary dresser for truing and dressing with plunge cutting as shown in Fig. 2b, the cutting speed should be set at 0.005 to 0.005 per revolution of the grinding wheel.
Set in the range of 0.5 μm/rev.

[0025]

【Example】

<Experiment 1> Four types of diamond whetstone test items (A, B
, C, and D) were manufactured, and the dressing performance using a diamond rotary dresser was compared with a conventionally used resin-bonded diamond grindstone.

The test products (A, B, C, D) were prepared by mixing glass powder and silicate mineral powder as binder raw materials with a thermal sublimation material as a pore-forming material in an amount of 0 to 40% of the binder raw material weight,
The formulation includes SiC (particle size #500) as a filler.
The powder was mixed in a weight ratio shown in Table 1 with respect to the weight of the binder raw material, and the mixture was mixed with diamond abrasive grains, and then fired at a temperature higher than the temperature at which the binder raw material melted.

[0027]

[Table 1]

Each test article (A to D) prepared had a diamond particle size of #400 and a diamond concentration of 100, and the mechanical properties of each test article are as shown in Table 1. On the other hand, the resin-bonded diamond grindstone used for comparison had a diamond grain size of #325 and a diamond concentration of 100.

On the other hand, the diamond rotary dresser uses a metal bond type and has a diamond particle size of #4.
0 and diamond concentration of 100 were used. The mechanical properties of the bonding layer of this dresser are shown in Table 1.

The comparison results are shown in FIG. As shown in this figure, while the conventional resin bonded diamond grinding wheel cannot be trued or dressed at all with a diamond rotary dresser, each test item (A, B, C, D)
showed an extremely high dressing rate, although there were slight differences depending on the composition.

<Experiment 2> Fig. 4 shows the machining results when surface grinding of cemented carbide was performed using the above-mentioned test piece A that was trued with a diamond rotary dresser and a resin bonded diamond grindstone that was trued and dressed using the conventional method. . In addition, in FIG. 4, Fn is the normal direction grinding resistance, and Ft is the tangential direction grinding resistance.

As shown in the figure, although the test specimen A has a slightly higher grinding resistance than the resin-bonded diamond grindstone, it has a large grinding ratio and exhibits excellent grinding performance.
It can be seen that the dressing was done well.

<Experiment 3> FIGS. 5 and 6 show the results of dressing the diamond grindstone of test item B using two types of diamond rotary dressers, a metal bond type and an electroplating type. Here, Fig. 5 shows the dressing rate with respect to the cutting depth ratio, and Fig. 6 shows the dressing rate for ceramics (Si3 N4
) shows the grinding resistance when grinding.

As shown in the figure, both types of dressers exhibited great truing and dressing properties. From now on, the specifications of the dresser should be such that the bonding layer of the abrasive grains is made of metal by metal bonding or electroplating, and the diamond grain size is in the range of #18 to 80 and the diamond concentration is in the range of 75 to 220. It is desirable to have one.

<Experiment 4> Figures 7 to 14 show proper truing and testing using the diamond grinding wheel of test item B and a metal bond type diamond rotary dresser.
The results of a test examining dressing processing conditions are shown.

FIGS. 7 and 8 show a study of the influence of the dressing direction. As shown in the figure, good results were obtained when the dresser was oriented in the same direction at the point of contact between the grindstone and the dresser.

FIGS. 9 and 10 examine the influence of the circumferential speed ratio of the diamond grindstone and the diamond rotary dresser. Good results were obtained when the circumferential speed ratio a (dresser circumferential speed/grindstone circumferential speed) was in the range of 0<a<10.

FIGS. 11 and 12 show the results of examining the influence of the cutting depth of the dresser. Good results were obtained in the cutting depth range of 1 to 10 μm.

FIGS. 13 and 14 show a study of the influence of the feed speed of the dresser. From the results in the figure, when traversing the dresser, the traverse amount F = (0
．． 01~0.02)×bμm/rev, on the other hand,
When the dresser is plunge-feeded, good results can be obtained when the feed rate is in the range of 0.005 to 0.5 μm/rev per rotation of the grindstone.

[0040]

[Effect] As described above, according to the method of the present invention, truing and dressing can be performed simply by bringing two diamond grindstones into contact while rotating, so that truing and dressing can be performed easily and efficiently on a grinding machine. You can perform polishing work on diamond whetstones.

Therefore, by utilizing the present invention, it is possible to apply a diamond grindstone to mass production processing by grinding, and the field of specifications for diamond grindstones can be greatly expanded.

[Brief explanation of drawings]

[Fig. 1] A is a diagram schematically showing the internal structure of a bonding layer, and b is a diagram showing another example of the structure.

[Figure 2] a is a diagram showing an example of machining a grindstone and a dresser, b is a diagram showing another machining example

[Figure 3] Comparison diagram of the dressing rate of diamond grinding wheels due to differences in bonding layers

[Figure 4] Comparison diagram of grinding performance due to different bonding layers

[Figure 5]
Comparison chart of dressing rates for different rotary dressers

[Figure 6] Comparison diagram of grinding resistance immediately after dressing due to different rotary dressers

[Figure 7] Comparison diagram of dressing rate due to different dressing directions

[Figure 8] Comparison diagram of grinding resistance immediately after dressing due to different dressing directions

[Figure 9] Comparison diagram of dressing rate due to different speed ratios

[Figure 10] Comparison diagram of grinding resistance immediately after dressing due to differences in speed ratio

[Figure 11] Comparison diagram of dressing rate due to different cutting depths

[Figure 12] Comparison diagram of grinding resistance immediately after dressing due to differences in depth of cut

[Figure 13] Comparison diagram of dressing rate due to different feed speeds

[Figure 14] Comparison diagram of grinding resistance immediately after dressing due to differences in feed speed

[Explanation of symbols]

1 Abrasive grain 2 Bond 3. Pores

Claims (4)

[Claims] 1. A method for truing and dressing a diamond grinding wheel, which comprises bringing two diamond grinding wheels whose abrasive bonding layers have different fracture strengths against compressive force into contact while being rotated relative to each other. [Claim 2] The bonding layer of one of the two diamond grinding wheels is set to have a property of being harder and more easily crushed than the bonding layer of the other grinding wheel, and both of the bonding layers are set to have a high 2. The method of truing and dressing a diamond grinding wheel according to claim 1, wherein the diamond grinding wheel is formed of a diamond grindstone material. 3. The truing dressing for a diamond grinding wheel according to claim 2, wherein the main component of the bonding layer of one of the grinding wheels is glass, and the main component of the bonding layer of the other grinding wheel is metal. Method. 4. Claim 2 or 3, wherein a large number of pores are uniformly present in the bonding layer of one of the grindstones.
The truing and dressing method for diamond grinding wheels described in .