JP2001246560A - Grinding method using electrodeposited grinding wheel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extend a grinding wheel life as long as possible in a grinding method using electrodeposited grinding wheel in which a prescribed re-truing is performed in order to extend the precisely grindable grinding wheel life, and keep the quality of machining high. SOLUTION: When the finish surface roughness Rz of a workpiece reaches a preset upper limit value (47 μm), the abrasive surface of the electrodeposited grinding wheel is subjected to a truing with a prescribed depth of cut and a prescribed lead in order to make the finish surface roughness Rz of the workpiece fine again. When the depth of cut is set smaller than the depth of cut in the previous re-truing, the life of the electrodeposited grinding wheel can be extended while keeping the finish surface roughness Rz of the workpiece, compared with the case where the depth of cut of the re-truing is constant. When the lead is set faster than the lead in the previous re-truing, the increase in power consumption accompanied by the increase in frequency of re-truing can be suppressed, so that the quality of machining can be kept high.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grinding method using an electrodeposition grindstone in which superabrasive grains are fixed on a base metal in a state of one abrasive layer by electroplating.

[0002]

2. Description of the Related Art Electrodeposited grindstones in which superabrasive grains such as CBN abrasive grains or diamond abrasive grains are fixed on a base metal in a single abrasive layer state by electroplating are known. Such electrodeposited whetstones are usually grown so that the plating metal deposited on the base metal fills the gaps between the superabrasive grains and the plated metal firmly grips the superabrasive grains. In the electrodeposited grinding wheel constructed in this way, the super-abrasive grains are firmly fixed in an ideal state with their tips sufficiently exposed. It is frequently used in

[0003] The electrodeposited grinding stone cannot be used in the field of precision grinding, which requires fine surface roughness, because the amount of projection of the superabrasive grains is not uniform due to variations in the attitude and diameter of the superabrasive grains. Further, since the abrasive layer is in the state of one abrasive layer, there is a drawback that the life is shorter than that of other types of grinding wheels.

[0004] The present applicant has filed Japanese Patent Application No. Hei 11-3 filed earlier.
No. 5562 describes a method for grinding an electrodeposited whetstone that has solved the above-mentioned disadvantages. According to this electrodeposition grinding wheel grinding method,
In the initial truing process, prior to grinding, the cutting edge is created with the same amount of superabrasive protrusions,
In the subsequent grinding process, it is possible to perform precision grinding with good surface roughness of the work material, and when the surface roughness of the work material reaches a preset upper limit, in the re-truing process, Truing for reducing the surface roughness of the workpiece is performed again on the ground surface of the electrodeposited grindstone, so that the precision grinding life of the electrodeposited grindstone can be extended.

[0005]

In the re-truing step of the prior application, if the truing is performed again on the ground surface of the electrodeposited grindstone, the processing life of the electrodeposited grindstone is prolonged regardless of the truing cut amount. In order to achieve the object, the truing cut amount is not particularly limited, and the embodiment discloses a case where the truing cut amount is a predetermined constant value. However, in order to maximize the life of the electrodeposition grindstone, it is desired that the cut amount in one retruing step is as small as possible.

In general, the larger the power consumption value during grinding, the larger the residual stress value of the work material, that is, the lower the processing quality. Therefore, the power consumption value during grinding even after re-truing increases. However, in the method disclosed in the above-mentioned prior application, the power consumption value increases every time re-truing is performed.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electrodeposition grinding wheel on which predetermined re-truing is performed in order to extend the life of a grinding wheel capable of precision grinding. In the grinding method used, it is to extend the life of the grinding wheel as much as possible or to maintain the processing quality at a high level.

[0008]

As a result of repeated studies to achieve the above object, the present inventors have found that when re-truing is repeatedly performed, the truing cut amount is reduced in accordance with the number of re-truing operations. If the surface roughness of the work material ground by the re-truing electrodeposited whetstone is maintained, and the cross-sectional area of the grinding allowance until the next re-truing does not reduce the truing depth It was found that increasing the truing lead in re-truing reduces the increase in power consumption due to the increase in the number of re-truings. The present invention has been made based on such findings.

[0009]

The gist of the first invention for achieving the above object is that truing is performed at a predetermined cutting amount so that the protruding amounts of superabrasive grains are uniform. A grinding step of grinding the workpiece using the electrodeposited whetstone, and each time the surface roughness of the workpiece reaches an upper limit set in advance by performing the grinding step, the surface roughness is reduced. A grinding process using an electrodeposited grindstone that repeatedly performs a truing process of forming a cutting edge by again truing a predetermined cutting amount and a predetermined lead on the grinding surface of the electrodeposited grindstone to make it finer again. The method is to reduce the cutting amount in the re-truing step from the previous cutting amount in the re-truing step.

[0010]

In this way, when the surface roughness of the workpiece to be ground in the grinding step reaches a predetermined upper limit, the grinding of the electrodeposited grinding wheel is performed in the re-truing step. A predetermined cutting amount and a predetermined lead truing are again applied to the surface, but since the cutting amount is smaller than the cutting amount in the previous re-truing process, the cutting amount of re-truing is constant. As compared with the case, the life of the electrodeposited grindstone becomes longer while the finished surface roughness of the work material is maintained.

[0011]

According to a second aspect of the present invention, there is provided a truing apparatus having a truing process having a predetermined cutting amount so that the protruding amounts of superabrasive grains are uniform. A grinding step of grinding a work material using an electrodeposited whetstone, and each time the surface roughness of the work material reaches a preset upper limit value by performing the grinding step, the surface roughness is reduced again. In order to perform the re-truing step of creating a cutting edge by applying a predetermined cutting amount and a predetermined lead to the grinding surface of the electrodeposited grinding wheel again, a grinding method using an electrodeposited grinding wheel is performed. The object of the present invention is to make the lead in the re-truing step faster than the lead in the previous re-truing step.

[0012]

In this manner, when the surface roughness of the workpiece to be ground in the grinding step reaches a predetermined upper limit, the grinding of the electrodeposited grinding wheel is performed in the re-truing step. A predetermined cut amount and a predetermined lead truing are applied to the surface again, but since the lead is made faster than the lead in the previous retruing process, power consumption increases with an increase in the number of times of retruing. Therefore, the processing quality can be maintained at a high level.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a perspective view showing an electrodeposition grindstone 10 used in one application example of the present invention. This electrodeposited whetstone 10
A metal-made base metal 12 having a disc shape, and a grinding surface 16 on the outer peripheral surface of which a CBN abrasive grain 14 having a particle size of, for example, about 80 is fixed by electrodeposition with a thickness of one particle layer. It has.

FIG. 2 is a diagram illustrating a grinding method using the electrodeposited grindstone of the present invention, and FIG. 3 is a diagram illustrating a state of a ground surface of the electrodeposited grindstone in the grinding method of FIG. (A) shows the state before the initial truing step 20;
(b) shows the state after the initial truing step 20, (c)
Shows the state after the re-truing step 24. FIG.
In the initial truing step 20 of step S1 (hereinafter, step is omitted), truing is performed on the electrodeposited grindstone 10 with a predetermined cutting amount ΔA using, for example, a diamond rotary dresser. The cutting amount ΔA in the initial truing step 20 is, for example, the surface roughness Rz (ten-point average roughness) of the workpiece in the grinding step 22 described below.
(μm)) is set to 2.5 μm or less. As shown in FIG. 3 (a), the state of the ground surface 16 before the initial truing is performed is such that the protrusion amount B of the CBN abrasive grains 14 with respect to the surface of the nickel plating layer 18 is not uniform. When the work material is ground, the required surface roughness cannot be obtained. However, once the initial truing is applied,
As shown in FIG. 3B, the protrusion amount B of the CBN abrasive grains 14 is made substantially constant.

In a subsequent grinding step 22 of S2, a workpiece (not shown) is ground by using the electrodeposited grindstone 10 in which the amount of protrusion B is made substantially constant in the initial truing step 20 or the re-truing step 24 in S4 described later. Processing is performed. Since the protrusion amount B of the CBN abrasive grains 14 is set to be substantially constant, precision grinding is performed so that the surface roughness Rz (= ten-point average roughness (μm)) of the work material becomes, for example, 4.0 μm or less. .

If the surface roughness Rz of the work material reaches a preset upper limit value, for example, 4.0 μm by performing the precision grinding process on the plurality of work materials in the grinding step 22, the process is continued. In S3, it is determined whether or not the electrodeposition grindstone 10 has reached the end of its life. This decision, for example,
Based on the fact that the power consumption value kW for rotating and driving the electrodeposition grindstone 10 exceeds a preset value, or
The determination is made based on whether or not the protrusion amount B of the BN abrasive grains 14 has become equal to or less than a predetermined value (for example, 30 μm).

If the determination in S3 is affirmative, the grinding by the electrodeposition grindstone 10 is terminated. If the determination is negative, the re-truing step 24 in S4 follows.
In order to re-fine the surface roughness Rz of the work material, re-truing of a predetermined cut amount ΔC (ΔC <ΔA) and a predetermined lead L (mm / row (row = revolution of wheel)) This is performed on the grinding surface 16 of the electrodeposition grindstone 10.

The truing in the retruing step 24 is a so-called micro truing in which the cut amount ΔC is set to a very small amount, and the cut amount ΔC is determined by the surface roughness of the work material processed by the grinding surface 16. Rz is set to a value sufficiently lower than the preset upper limit value of the grinding (for example, 2 μm).
m). Also,
The cut amount ΔC is set to a value equal to or smaller than the cut amount ΔC in the previous retruing step 24. When the cutting amount ΔC is set to a value smaller than the cutting amount ΔC in the previous retruing step 24, the life of the electrodeposition grindstone 10 is extended as compared with the case where the cutting amount ΔC is the same constant value every time. can do. That is, the electrodeposition whetstone 10
Can be used effectively. Further, even if the cut amount ΔC is reduced as the number of times of re-truing increases, the surface roughness Rz of the work material can be sufficiently reduced.

The reason why the cut amount ΔC can be reduced as the number of times of retruing increases can be considered as follows. That is, the distance from the tip of the abrasive grain in the depth direction (the direction of the nickel plating layer 18) is a predetermined value (for example, 3).
0 μm), the area obtained by dividing the area of the abrasive grains when the electrodeposited grindstone 10 is cut on the surface which is 0 μm) by the area of the ground surface is defined as an abrasive grain area ratio (%). , The area ratio of the abrasive grains of the electrodeposition grindstone 10 increases. As the area ratio of the abrasive grains increases, more cutting edges are created with a smaller cutting amount ΔC. Therefore, the cut amount ΔC can be reduced as the number of times of retruing increases.

The lead L in the re-truing step 24 is set to a value equal to or faster than the lead L in the previous re-truing step 24. As described above, as the re-truing is performed, the abrasive grain area ratio increases, so that the power consumption value tends to increase. However, when the lead L in the re-truing is increased, the increase in the power consumption value can be suppressed. FIG. 4 is a conceptual diagram showing a crushing form of the CBN abrasive grains 14 in the retruing in comparison with a case where the truing lead L is slow and a case where the truing lead L is slow. (b) is a case where the truing lead L is fast. As shown in FIG. 4, the faster the truing lead L, the higher the CB
Since the crushing form of the N abrasive grains 14 becomes large, an increase in the power consumption can be suppressed by increasing the lead L.

Then, the re-truing step 2 of the above S4
After the execution of step 4, the grinding step 22 of S2 is executed again.

Next, a description will be given of a truing cut amount test in which the cut amount ΔC is reduced when the number of times of retruing increases. In this test, using an electrodeposited whetstone on which CBN abrasive grains 14 having a grain size of # 80 were electrodeposited, the target finish surface roughness Rz at the initial stage of the grinding process was set to 2 μm, and precision grinding was performed under the following grinding conditions. When the surface roughness of the cut material becomes 4 μm, re-truing was performed four times under the following truing conditions. The cut amount ΔC in the re-truing was such that the cut amount in one pass was constant, and the total cut amount was changed by changing the number of passes. In the first and second re-truing, the number of pass was set to three, in the third re-truing, the number of pass was set to two, and in the fourth re-truing, the number of pass was set to one. The results are shown in FIGS.

(Trueing conditions) Truer: SD40Q75M (φ60 × U1) Lead: 0.1 mm / r. o. w Depth of cut ΔC: φ4 μm / pass × (1-3) pass

(Grinding conditions) Wheel (grinding wheel): CB80PA5 (D405 × T25 × H127)
× U10) Grinding method: wet plunge grinding (up cut) Work material: SCM435 (HRC48) (φ60 × t5) Grinding wheel peripheral speed: 45 m / s Work material peripheral speed: 0.45 m / s Cutting speed: Z ′ = 10mm ³ / mm · s Cutting allowance: Grinding allowance cross-sectional area = 100mm ² Spark out: 10rev Grinding fluid: Soluble type SA1000CB (× 5
0)

FIG. 5 is a graph showing the relationship between the cross-sectional area of the grinding allowance per unit circumferential length of the wheel in the continuous grinding until the finished surface roughness Rz of the workpiece becomes 4 μm after the fourth re-truing. Finished surface roughness (ie surface roughness)
It is a figure showing change of Rz and change of power consumption value (kW). As shown in FIG. 5, when comparing the first and second re-truing operations in which the number of passes is 3 times, when re-truing is repeated, the finished surface roughness Rz at the initial grinding after re-truing becomes fine, It can be seen that the power consumption value increases, and the cross-sectional area for grinding until the next retruing, that is, the truing interval, tends to be long. The tendency for the power consumption value to increase and the truing interval to increase is that the number of passes is 2
The same applies to the third re-truing, which has been reduced to three times, and the fourth re-truing, which has reduced the number of passes to one. The truing interval after the third re-truing and the fourth re-truing is 3
It was almost the same as the case where the number of passes in the third and fourth retruing was set to three. Also, the finished surface roughness Rz at the initial stage of grinding after re-truing was determined to be 3 passes.
The same fineness as after the first and second re-truing is maintained.

FIG. 6 shows the residual stress values of the work material after the initial truing and after each re-truing until the grinding allowance cross-sectional area per unit circumferential length of the wheel was 0.786 mm ² / mm. FIG. As shown in FIG. 6, the surface of the work material was about 500MP in each case.
The compressive stress a is acting, and no tensile stress is seen inside the work material.

Next, a description will be given of a truing lead test in which the truing lead L is increased each time the number of times of re-truing increases. In this test, every time the work material was ground by a certain amount under the same grinding conditions as the above-mentioned truing cut amount test, the work material was continuously ground while performing re-truing four times under the following truing conditions. Things. Truing lead L for each truing
From the initial truing to the second re-truing, the speed was increased with the number of truing, and in order to compare the result, the same as the initial truing was returned in the third re-truing, and the fourth re-truing was performed in the third Faster than re-truing. That is, the truing lead L in each truing is such that the initial truing is 0.05 (mm / row), the first re-truing is 0.1 (mm / row), and the second truing is 0.2 (mm / row). ) The third re-truing is 0.05
(mm / row) 4th re-truing is 0.1 (mm / ro
w).

(Trueing conditions) Truer: SD40Q75M (φ60 × U1) Lead: 0.05, 0.1, 0.2 mm / r. o.
w Cutting depth ΔC: φ4 μm / pass × 3pass

FIG. 7 shows the results of the test performed as described above.
9 to FIG. FIG. 7 is a diagram showing a change in the finished surface roughness Rz of the work material and a change in the power consumption value (kW) with respect to the grinding allowance cross-sectional area per unit circumferential length of the wheel in the truing lead test. In the above-described truing depth of cut test in which the truing lead L is constant, as shown in FIG. 5, the power consumption value increases every time re-truing is performed.
As shown by the second retruing, increasing the truing lead L for each truing suppresses an increase in the power consumption value. Further, when the truing lead L is returned to 0.05 (mm / row) in the third re-truing, the initial finished surface roughness Rz after truing is reduced again. That is, it can be seen that the finished surface roughness Rz can be controlled by the truing leads L.

FIG. 8 shows the finished surface roughness Rz of the work material with respect to the area ratio of the abrasive grains in the truing lead test.
FIG. 4 is a diagram showing a change in power consumption and a change in power consumption value (kW). As shown in FIG. 8, the area ratio of the abrasive grains increases as the number of times of retruing increases, but it can be seen that the increase in the power consumption value is suppressed even when the area ratio of the abrasive grains increases.

FIG. 9 shows the residual stress values of the workpiece after the initial truing and after each re-truing until the grinding allowance cross-sectional area per unit circumferential length of the wheel was 0.786 mm ² / mm. FIG. As shown in FIG. 9, in each case, a compressive stress acts on the surface of the work material, and no tensile stress is observed inside the work material.

As described above, according to the grinding method shown in FIG. 2, when the surface roughness Rz of the workpiece to be ground in the grinding step 22 reaches a predetermined upper limit,
In the re-truing step 24, a predetermined cutting amount ΔC and a predetermined lead L are trued again on the grinding surface 16 of the electrodeposited grindstone 10, and the cutting amount ΔC is reduced by the cutting in the previous re-truing step 24. If the amount is smaller than the amount ΔC, the life of the electrodeposited grindstone can be extended while maintaining the finished surface roughness Rz of the work material, as compared with the case where the cutting amount of retruing is a constant value.

According to the grinding method shown in FIG.
Surface roughness Rz of work material ground in grinding step 22
Reaches a preset upper limit, in the re-truing step 24, the grinding surface 16 of the electrodeposited grindstone 10 is again trued with a predetermined cutting amount ΔC and a predetermined lead L, If the lead L is made faster than the lead L in the previous retruing step 24, an increase in power consumption due to an increase in the number of times of retruing can be suppressed, so that high quality processing can be maintained.

As described above, one embodiment of the present invention has been described with reference to the drawings. However, the present invention can be implemented in another mode different from the above embodiment.

For example, in the above embodiment, when the number of retruing increases, the truing lead L is kept constant and the cutting amount ΔC is decreased, and the number of retruing increases, and the number of retruing increases. Every,
Although the truing lead test in which the truing lead L is increased while the cutting amount ΔC is constant has been described, both the cutting amount ΔC and the truing lead L may be changed. That is, the cutting amount ΔC in the re-truing step 24 is made smaller than the cutting amount ΔC in the previous re-truing step 24, and the truing lead L
May be faster than the previous truing lead L.
For example, as shown in Table 1, reducing the cutting amount ΔC from the previous retruing step 24 and making the truing lead L faster than the previous retruing step 24 may be appropriately combined. . By doing so, it is possible to extend the life of the electrodeposition grindstone 10 that can be precisely ground as much as possible while appropriately suppressing an increase in the power consumption value.

(Table 1) 回 数 Number of retruing times Trueing lead L Depth of cut ΔC (mm / row) １ 1 0.05 φ4.0 μm × 3 pass 2 0.05 φ4.0 μm × 2 pass 3 0.1 φ4.0 μm × 2 pass 4 0.1 φ4.0 μm × 1 pass 5 0.2 φ4.0 μm × 1 pass ───── ─────────────────────────────

In the above-described embodiment, the surface roughness is determined by the ten-point average roughness Rz, but may be determined by the maximum height Ry.

In the above embodiment, the CBN abrasive grains 14
Is # 80, but abrasive grains of other particle sizes such as # 40 may be used.

In the above embodiment, the grinding wheel peripheral speed is 4
Although the normal peripheral speed was 5 m / s, for example, 200 m / s
The peripheral speed may be as high as the standard.

Further, the electrodeposited whetstone 10 of the above-described embodiment has a C
Although the BN abrasive 14 was provided with the ground surface 16 electrodeposited thereon, the ground surface 16 may be electrodeposited with diamond abrasive.

Also, the electrodeposited grinding wheel 10 of the above-described embodiment is formed in a disk shape with a cylindrical grinding surface 16 as shown in FIG. It may be configured in a complicated shape such as

The re-truing step 2 shown in FIG.
In 4, the rotary dresser was used for retruing, but another type of dresser such as a blade type may be used if there is no problem in the holding force of the CBN abrasive grains 14.

What has been described above is merely an embodiment of the present invention, and the present invention can be variously modified without departing from the gist thereof.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an electrodeposition grindstone used in a grinding method according to one embodiment of the present invention.

FIG. 2 is a process diagram illustrating a grinding method using the electrodeposition grindstone of FIG.

3A and 3B are diagrams illustrating a state of a ground surface of an electrodeposited grindstone in the grinding method of FIG. 2, wherein FIG. 3A shows a state before an initial truing step, and FIG. 3B shows a state after an initial truing step. (C) shows the state after the re-truing step.

FIG. 4 is a conceptual diagram showing a crushing form of CBN abrasive grains in re-truing when the truing lead L is slow and when the truing lead L is fast, and FIG. b) is a case where the truing lead L is fast.

FIG. 5 is a diagram showing a change in finished surface roughness Rz of a work material and a change in power consumption value with respect to a grinding allowance cross-sectional area per wheel unit circumferential length in a truing cut depth test.

FIG. 6 is a graph showing the relationship between the cutting depth of the workpiece after the initial truing and after each re-truing in the truing depth-of-cut test, until the grinding allowance cross-sectional area per wheel unit circumferential length is 0.786 mm ² / mm. It is a figure which shows a residual stress value.

FIG. 7 is a diagram showing a change in finished surface roughness Rz and a change in power consumption value with respect to a grinding allowance cross-sectional area per wheel unit circumferential length in a truing lead test.

FIG. 8 is a diagram showing a change in finished surface roughness Rz of a work material and a change in power consumption value with respect to an abrasive grain area ratio in a truing lead test.

FIG. 9 shows the residual stress of the workpiece after the initial truing and after each retruing in the truing lead test, until the grinding allowance cross-sectional area per wheel unit circumferential length becomes 0.786 mm ² / mm. It is a figure showing a value.

[Explanation of symbols]

 10: Electroplated whetstone 14: CBN abrasive grains (super abrasive grains) 22: Grinding process 24: Retruing process

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B24D 3/00 320 B24D 3/00 320B 3/06 3/06 B (72) Inventor Shinjiro Sakuragi Nagoya, Aichi Prefecture No. 36, Noritake Shinmachi, Nishi-ku, Nishi-ku, Japan Noritake Co., Ltd. Limited (72) Inventor Kenji Noda 3-36, Noritake Shinmachi, Nishi-ku, Nagoya-shi, Aichi F-term (reference) 3C034 AA20 CA05 CA09 CA16 CB12 DD05 DD20 3C047 AA02 AA04 AA05 AA11 AA13 AA15 3C063 AA02 AB03 BB02 BB24 BC02 BG01 BG07 CC13 CC30

Claims (2)

[Claims] 1. A grinding step for grinding a work material using an electrodeposited whetstone having a predetermined cutting amount of truing and a superabrasive grain having a uniform projection amount, and the grinding step is performed by executing the grinding step. Each time the surface roughness of the workpiece reaches the preset upper limit value, in order to reduce the surface roughness again, a predetermined cutting amount and a predetermined lead truing are performed on the grinding surface of the electrodeposited grindstone. A grinding method using an electrodeposited whetstone that repeatedly performs a re-truing step of applying a cutting edge again to form a cutting edge, wherein the cutting amount in the re-truing step is calculated from the cutting amount in the previous re-truing step. Grinding method using an electrodeposited whetstone, characterized in that the grinding is also reduced. 2. A grinding step for grinding a workpiece using an electrodeposited whetstone having a predetermined cutting amount of truing and a superabrasive grain having a uniform protrusion amount, and the grinding step is performed by executing the grinding step. Each time the surface roughness of the workpiece reaches the preset upper limit value, in order to reduce the surface roughness again, a predetermined cutting amount and a predetermined lead truing are performed on the grinding surface of the electrodeposited grindstone. A grinding method using an electrodeposited grindstone that repeatedly performs a re-truing step of creating a cutting edge by applying again, wherein a lead in the re-truing step is faster than a lead in the previous re-truing step. A grinding method using an electrodeposition whetstone, characterized in that: