JP3088537B2 - Finishing method and processing device for holes of high hardness material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention, CBN, by reamer fixed hard abrasive grains such as like the blade portion to the electrodeposition diamond working method and vibrating finishing holes in hardened steel
It relates to a processing device .

[0002]

2. Description of the Related Art Hole finishing of a hardened material hardened to HRc 50 or more or tempered to HRc 30 to 50 is usually carried out by inner grinding or honing with a grindstone. In addition, it is often required to finish the hole of the work with high accuracy in finishing the hole of the hard material. For example, when the work is a gear or a mold, the machining is performed based on the hole position, so that the machining must be performed while maintaining the hole position with high precision. In order to grind the hole of such a work, it is necessary to hold the work firmly and with high precision, but it is extremely difficult to hold the work in this way. For this reason, there is a possibility that the position of the processing hole is displaced or the processing hole is eccentric, and the deflection between the processing hole and the outer periphery of the work becomes large, so that satisfactory work accuracy cannot be obtained.

[0003] That is, in the internal grinding, the surface roughness is 1-2.
Rz, roundness is 2 to 4.5 μm, but runout accuracy is 4
The thickness is 0 to 60 μm, and there is a limit to achieving higher precision. on the other hand,
Honing finish processing enables high precision processing with a surface roughness of 1 to 2 Rz and a roundness of about 1 to 2 μm. However, the processing time is too long, and the number of processing axes is increased in processing. In order to improve efficiency, the processing machine becomes large, and the production cost is increased because the machine is expensive. In order to solve such a problem, various reamers in which hard abrasive grains (referred to as abrasive grains such as CBN or diamond) are fixed (actually electrodeposited) to the reamer blade portion have been invented (for example, Japanese Utility Model Application Laid-Open No. HEI 3-103). -40058).

[0004]

Such a reamer is gripped by a floating chuck, and the grinding allowance is 0.1 mm.
At a cutting speed of 200 m / min, the number of revolutions is about 4500 revolutions (φ
(15 mm reamer). However, when machining steel having a hardness of HRc55, the work hole accuracy is poor,
In addition, the chips were clogged between the abrasive grains and the abrasive grains were separated, resulting in a remarkably short tool life. As a result of investigating such a cause, it was found that elongated chips adhered between the abrasive grains and clogged the chips, the abrasive grains fell off, and the electrodeposition layer was peeled off.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is a processing method for finishing a hole in a high-hardness material by a reamer having hard abrasive grains fixed to a blade portion. A first processing step and a second processing step, at least one of the work and the reamer is subjected to low frequency vibration in the first processing step and the second processing step, and the vibration of the first processing step is performed. The number and amplitude
By making the vibration frequency and amplitude larger than those described above, machining hole accuracy, position accuracy, tool life, and machining efficiency are improved. Furthermore, it provided a roughing unit and a finishing unit in the reamer, the first processing step and processed in the roughing portion of the reamer, pressurizing the second processing step in the finishing portion of the reamer
It is good to work . Further, according machining method for carrying out, a processing apparatus for finishing a hole having a high hardness material by causing the Lee Ma that fixing the hard abrasive grains on the cutting unit rotating and vertical movement, supporting the workpiece Work supporting means, a reamer having a rough machining portion and a finishing portion, and a positioning means for performing positioning of a hole formed in the work and an axis of the reamer,
At least one of the workpiece and the reamer, a low-frequency vibration imparting means for applying a low-frequency vibration different from the time of processing by the rough processing part of the reamer and the time of processing by the finishing part, The above-mentioned problem was solved by providing.

In the grinding process, there is a method of utilizing high frequency vibration (for example, Japanese Patent Application Laid-Open No. 62-162451) or a method of superposing ultrasonic vibration and low frequency vibration (Japanese Patent Application Laid-Open No. 63-62661). However, unlike the present invention, when high frequency vibration is used, the frequency is 10 KHz or more and the amplitude is 0.03 to 0.12 mm / min, which is fine vibration, and is intended to prevent welding, reduce cutting torque, and perform high-efficiency processing. It is what it was. Further, the structure becomes complicated to generate high frequency and low frequency. The present invention relates to a reamer processing method as described above, and finishes a hard material while applying low-frequency vibration to a work or a reamer in the axial direction of the reamer. Further, the frequency and amplitude of the first processing step are reduced. , Second
The frequency and amplitude of the machining process
Ri is obtained by utilizing efficiently depending on the processing conditions an effective low-frequency vibration to cutting action of the chips in the reaming process is a cutting process, the present application is a novel invention has been completed based on this finding.

[0007] The low frequency vibration in the present invention is a vibration.
Number is 5Hz to 500Hz, amplitude is 0.1mm to 3.0
mm is preferred. Also, the processing hole has a small diameter and is used for this.
If the outer diameter of the blade of the reamer is
The cutting performance is too small to cut chips.
Chips are clogged and processing becomes impossible.
0.1mm, frequency 5Hz, reamer rotation speed 10m
/ Min is preferably the lower limit. Also, holes in the work
When the diameter is large and the outer diameter of the reamer blade is 100 mm or more
Grinding allowance increases and amplitude is set to 3.0 mm or more
The accuracy and surface roughness of the machined hole and surface roughness are very poor,
3.0 mm, the frequency is low frequency vibration of 500 Hz.
It is preferable to set the upper limit of the rotation speed of the motor to 300 m / min.
New

[0008]

When a low frequency vibration in the axial direction is applied to one of the reamer and the work and the rotation is applied, the elongated chips ground by the abrasive grains are divided, and the small chips are removed. And is discharged outside without clogging between the abrasive grains. At this time, the frequency and amplitude of the first processing
By increasing the frequency and amplitude of the process,
Set appropriate chip discharge conditions according to the respective machining conditions.
Can be obtained, and a considerable part of the allowance is
Then, the surface roughness is improved in the second processing step. Re
A roughing part and a finishing part are provided on the
Processing at the roughing part (biting part) of the reamer
2 processing in the finishing part (cylindrical part) of the reamer
In this case, the accuracy of the processing hole and the accuracy of the position are ensured.

[0009]

FIG. 1 shows an example of an apparatus for carrying out the method of the present invention. Fig. 1 shows hard abrasive grains fixed on the blade.
By rotating the reamer and moving it up and down,
A processing device that finishes a hole.
This is a disk-shaped work placed and fixed on the work support plate 3 as a means . Wa - the click support plate 3 is formed in the workpiece 1
The hole 2 and the tool relief hole 4 communicating is bored, even lower
It is supported by a vibration table 5 which is a frequency vibration applying means . The reamer 6 used in the present invention has a relief portion 7a and a cylindrical portion 7 which is a finished portion having a slightly larger diameter than the hole 2 of the work.
b, a tapered shape having a large diameter from the tip toward the cylindrical portion 7b
It comprises a blade 7 having a biting portion 7c which is a rough processing portion , and a cylindrical handle 8 continuous with the blade 7.
Further, hard abrasive grains (CBN, diamond, etc.) are electrodeposited on the outer periphery of the blade portion 7. The shank 8 is held by a floating chuck 9 located above the work support plate 3 and the vibration table 5. Vibrating table
5 is low when processing by the finishing part and when processing by the rough processing part
The frequency oscillation conditions are different.

[0010] To perform the reaming finish processing, first,
Positioning of the hole 2 of the workpiece by the non-aligning means
Do. That is, after the hole 2 of the work is made to face the hole 4 of the work support plate 3, a vertically movable guide (not shown) that matches the axis LL of the reamer 6 is moved from the vibration table 5 to the work. The work hole 2 is positioned by penetrating the hole 4 of the support plate 3 and the work through hole 2. Next, the work 1 is fixed to the work support plate 3. When the work 1 is completely fixed, the guide (not shown) is lowered to the vibration table 5. Next, while the reamer 6 is being rotated, the through hole 2 of the work hole 1 is gradually passed through the reamer 6 while grinding and finishing, and the processing is completed when the blade portion 7 has completed passing through the through hole 2 of the work 1. I do.

(Example 1) For example, in order to finish the inner peripheral surface of the hole 2 of the work 1 made of chromium steel material SCr420, the work 1
Is fixed to the support plate 3, and the reamer 6 is rotated at a cutting speed of 10 m / min to 300 m / min as shown by the arrow B, and is further fed in the direction of the arrow A, and at the same time the amplitude of the axial A low frequency vibration of 0.1 mm to 3.0 mm and a frequency of 5 Hz to 500 Hz was applied.

[0012] shows this in detail, word over click specifications hardness HRC60, processing hole diameter Fai15.4Mm, machining hole length 28
mm, SCr420 with a stock removal of 0.002 to 0.05 mm
The material was subjected to a frequency of 50 Hz, a single amplitude of 0.8 mm, and a moving speed of 4.
When processing was performed under the processing conditions of 0 mm / min and a rotation speed of 800 rpm, processing was successfully performed at a torque of 40 to 52.5 kgf · cm 2 and a thrust of 10 to 22.5 kgf . In this case, it was confirmed that the chips were finely divided. The processing accuracy was 0.9 to 1.5 Rz, the roundness was 1 to 2.5 μm, the variation in the processing hole diameter was 8 μm, and the runout was 1
It improved to 5 μm (MAX).

On the other hand, in the trial, the same material as described above was used, without applying vibration, at a moving speed of 40 mm / min and a rotation speed of 80.
After finishing at 0 rpm, torque 1
At 38 kgf · cm 2 and thrust 40 kgf, the chips were not divided, and welding was generated on the reamer, and an abnormal sound was generated. In the present invention,
In order to improve the machined surface, the following was done.

(Embodiment 2) Next, the biting portion 7c (rough processing portion) is processed at a frequency of 50 Hz, an amplitude of 0.8 mm, a rotation speed of 800 rpm, and a feed of 40 mm / min.
After passing through the large-diameter cylindrical portion 7b, the vibration frequency becomes 2
When the processing was carried out as it was without changing the number of revolutions and feed at 0 Hz and an amplitude of 0.4 mm, the finished surface roughness was 0.4 mm.
Improved to 7Rz. This is due to the fact that a considerable portion of the allowance is removed in the biting portion 7c, which is a rough processing portion, and the large-diameter cylindrical portion 7b, which is a finishing portion, has a surface roughness improving effect.

In the embodiment, the blade 7 of the reamer uses a tool having hard abrasive grains fixed to the outer periphery of a cylindrical portion 7b having a bite 7c at the tip. However, the present invention is not limited to this. It goes without saying that an axial groove or a twist groove may be provided on the outer periphery or a hardened abrasive grain fixed to a regular-shaped reamer may be used. Further, in the above embodiment, the table is given low-frequency vibration. Alternatively, the hole can be finished by rotating the table on the reamer side, that is, by giving low-frequency vibration to the chuck and rotating the table. Good results were obtained. Although the chuck uses a floating chuck in the embodiment, a fixed shaft chuck may be used instead.

[0016]

According to the vibration finishing method for a hard material according to the present invention, the tool is rotated as described above to cause the work or the tool to vibrate at a low frequency, and further, the frequency and amplitude of the first processing step are performed.
Is made larger than the frequency and amplitude of the second processing step.
And grinding, so that the optimal conditions
To separate slender grinding chips cut with hard abrasive grains
Can be removed and efficiently removed in the first processing step?
Removed part of the surface, improving surface roughness in the second processing step
Therefore, as shown in the examples, many excellent effects were obtained, such as high-precision hole finishing without chip clogging and prolonging the tool life. In addition, reamer
Rough processing part and finishing part are provided in the first processing step.
If the second processing step is a finishing step,
The one that secures hole accuracy and position accuracy and improves machining efficiency
It became. Further, since only low-frequency vibration is used, the structure is simpler and easier to control than a combination of high frequency and low frequency.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a relationship between an apparatus used to carry out the method of the present invention and a work.

[Explanation of symbols]

1. . . . . . . Work 2. . . . . . . Work hole 3. . . . . . . 3. Work support means (work support plate) . . . . . . Tool relief hole 5. . . . . . . Vibration table 6. . . . . . . Reamer 7. . . . . . . Blade part 7b. . . . . . Finishing part (cylindrical part) 7c. . . . . . Rough processing part (biting part) . . . . . . Shank 9. . . . . . . Chuck

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hideo Igarashi 20 Ishigane, Toyama City, Toyama Prefecture Fuji Koshiuchi Co., Ltd. (72) Inventor Tadao Matsui 20 Ishikin, Toyama City, Toyama Prefecture Fuji Koshiuchi Co., Ltd. 56) References JP-A-2-106237 (JP, A) JP-B-58-27063 (JP, B2) JP-B-50-20716 (JP, B1) JP-B 62-40123 (JP, B2) 37-21595 (JP, Y1) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23D 75/00

Claims (3)

(57) [Claims] 1. A processing method for finishing a hole of a high-hardness material using a reamer in which hard abrasive grains are fixed to a blade portion, wherein when finishing the hole, a first processing step and a second processing step are performed. In the first processing step and the second processing step, at least one of the workpiece and the reamer is subjected to low frequency vibration, and the frequency and amplitude of the first processing step are
A method for finishing a hole in a hardened material, wherein the frequency and amplitude are made larger than the frequency and amplitude of the second processing step . 2. The reamer has a rough processing part and a finishing part, the first processing step is processing in a rough processing part of the reamer, and the second processing step is processing in a finishing part of the reamer. finishing method of the high-hardness material of the hole according to claim 1, wherein the machining der Rukoto. 3. A processing apparatus for finishing a hole having a high hardness material by causing the Lee Ma that fixing the hard abrasive grains times are rotation and vertical movement to the blade portion, a workpiece support means for supporting the workpiece, rough A reamer having a processing part and a finishing part, positioning means for positioning a hole formed in a work and an axis of the reamer, and at least one of the work and the reamer, a rough processing part of the reamer. And a low-frequency vibration applying means for applying a low-frequency vibration different from that during processing and during processing by the finishing unit.