JPH05162012A - Reaming vibration finishing method for holes in high hardness materials - Google Patents

Abstract

(57) [Summary] [Purpose] To finish the hole of high hardness material with high accuracy. [Structure] A shank 8 of a reamer 6 having hard abrasive grains fixed to a blade portion 7 is gripped by a chuck 9, and a work 1 is placed on a mounting surface of a work support plate 3 having a tool escape hole 4 formed therein. Next, after aligning the hole 2 of the work 1 with the axis of the reamer 6 and making the reamer 6 face the hole 2 of the work, the reamer is rotated at a rotation speed of 10 m / min to 300 m / min to start grinding. At the same time, the workpiece or reamer has an axial amplitude of 0.1 mm to 3.0 mm and a frequency of 5 Hz to 500 mm.
Finish the hole of high hardness material while giving low frequency vibration of Hz.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a machining method for vibrating and finishing a hole of a high hardness material with a reamer having hard abrasive grains such as CBN and diamond fixed to a blade portion by electrodeposition or the like.

[0002]

2. Description of the Related Art For the hole finishing of a high hardness material hardened to HRc 50 or higher or tempered to HRc 30 to 50, inner surface grinding with a grindstone or honing is usually performed. Further, in finishing the holes of the high hardness material, it is often required to finish the holes of the work with high accuracy. For example, when the work is a gear or a die, the hole position is used as a reference for processing, and therefore the hole position must be maintained with high accuracy. In order to grind such a hole in a work, it is necessary to hold the work firmly and with high accuracy, but it is extremely difficult to hold the work in this way. Therefore, there is a possibility that the position of the machining hole may be displaced or the machining hole may be eccentric, resulting in a large deviation between the machining hole and the outer circumference of the work, resulting in insufficient work accuracy.

That is, in the internal grinding, the surface roughness is 1 to 2
Rz and circularity are 2 to 4.5 μm, but runout accuracy is 4
It becomes 0 to 60 μm, and there is a limit to high precision. on the other hand,
In the honing finishing process, it is possible to perform high-precision machining with a surface roughness of 1-2 Rz and a roundness of 1-2 μm, but it takes a long time and requires a large number of machining axes. In order to improve the efficiency, the processing machine becomes large, and the machine is expensive, resulting in an increase in production cost. In order to solve such a problem, various reamers have been invented (hardly electrodeposited) with hard abrasive grains (referred to as abrasive grains such as CBN or diamond) fixed to the reamer blade (for example, actual Kaihei 3). -40058).

[0004]

Such a reamer is held by a floating chuck, and the grinding allowance is 0.1 mm,
Approximately 4500 revolutions at a cutting speed of 200 m / min (φ
I tried processing with a 15 mm ream). However, in the processing of steel with hardness HRc55, the work hole accuracy is also poor,
In addition, chips were clogged between the abrasive grains and the abrasive grains were peeled off, resulting in extremely short tool life. As a result of investigating the cause, it was found that elongated chips adhered between the abrasive grains to cause chip clogging, the abrasive grains fell off, and the electrodeposition layer peeled off.

[0005]

In order to solve the above problems, the present invention applies axial vibration to either a rotating reaming tool or a work fixed to a work support plate. In this case, the vibration is a low frequency of 5 Hz to 500 Hz, an amplitude of 0.1 mm to 3.0 mm, and 10 m / min.
From 300 m / min to 300 m / min as a processing condition, grinding was performed to cut chips into small pieces. For this reason, the accuracy of machining hole, the accuracy of position, the tool life, and the machining efficiency are improved.

In the grinding process, there is a method of utilizing high frequency vibration (for example, JP-A-62-162451) or a method of superposing ultrasonic vibration and low-frequency vibration (JP-A-63-62661). However, unlike the present invention, when high frequency vibration is used, the vibration frequency is 10 KHz or more and the amplitude is 0.03 to 0.12 mm / min, which is a minute vibration, and the purpose is to prevent welding, reduce cutting torque, and perform high-efficiency machining. It is what The present invention relates to the reamer machining method as described above, and moreover, the workpiece has an amplitude of 0.1 mm to 3.0 mm and a frequency of 5 Hz to 500 in the axial direction of the reamer.
High-hardness material is finished while giving low-frequency vibration of Hz, and low-frequency vibration is extremely effective in the cutting action of chips in the reaming method, which is a cutting process.
The present application is a novel invention made based on such knowledge.

In the present invention, the lower limit of the amplitude is 0.1 mm, the frequency is 5 Hz, and the rotation speed is 10 m / min.
The hole has a small diameter and the outer diameter of the blade of the reamer used for this is 2
In the case of mm or less, the rigidity of the blade portion is small and the chips cannot be divided, and the chips are clogged between the cutting edge abrasive grains,
This is because processing becomes impossible. Also, the amplitude is 3.0m
m, frequency is low frequency vibration of 500 Hz, rotation speed 3
The upper limit of 00 m / min is that the grinding allowance increases when the hole diameter of the work is large and the outer diameter of the blade of the reamer is 100 mm or more, and when the amplitude is 3.0 mm or more, the accuracy and surface roughness of the processed hole are large. This is because the degree becomes very bad.

[0008]

[Operation] 5Hz for either the reamer or the work
To 500 Hz and an axial low frequency vibration with an amplitude of 0.1 mm to 3.0 mm, and a rotation speed of 10 m / min to 300 m / min, the elongated chips ground by the abrasive grains are divided, It becomes small fine chips and is discharged outside without being clogged between the abrasive grains. For this reason, the processing hole accuracy and the position accuracy are secured.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENT An example of an apparatus for carrying out the method of the present invention will be described with reference to FIG. Reference numeral 1 is a disk-shaped work placed and fixed on the work support plate 3. The work support plate 3 is provided with a tool relief hole 4 communicating with the hole 2 of the work 1 and further supported by the vibration table 5. The reamer 6 used in the present invention has a relief portion 7a, a cylindrical portion 7b having a diameter slightly larger than the hole 2 of the workpiece, and a taper-like biting portion 7c having a diameter increasing from the tip to the cylindrical portion 7b. It is composed of a blade portion 7 and a cylindrical handle 8 continuous with the blade portion 7. Further, the blade portion 7 has a hard abrasive grain (CB
N, diamond, etc.) are electrodeposited. The shank 8 is held by the work supporting plate 3 and the floating chuck 9 located above the vibrating table 5.

To perform the reaming process, the hole 2 of the work is exposed to the hole 4 of the work support plate 3, and then a not-shown vertically movable guide matching the axis L-L of the reamer 6 is provided. The work hole is positioned through the vibration table 5 through the hole 4 of the work support plate 3 and the work through hole 2. Then
The work 1 is fixed to the work support plate 3. When the work 1 is fixed, the guide (not shown) is lowered to the vibration table 5. Next, while rotating the reamer 6, the work hole 1
The reamer 6 is gradually passed through while finishing the through hole 2 of No. 2 and the processing is completed when the blade portion 7 has completely passed through the through hole 2 of the work 1.

(Example 1) For example, S which is a chrome steel material
In order to finish grinding the inner peripheral surface of the hole 2 of the work 420 made of Cr420, the work 1 is first fixed to the support plate 3, and the reamer 6 is cut at a cutting speed of 10 m / min as shown by an arrow B. Three
A rotation of 00 m / min is given, and further, it is sent in the direction of arrow A, and at the same time, the vibration table 5 has an axial amplitude of 0.1 mm to
A low frequency vibration of 3.0 mm and a frequency of 5 Hz to 500 Hz was applied.

[0012] Specifically, according to the present invention, the work specifications are hardness HRc60, processing hole diameter φ15.4 mm, processing hole length 28 mm, machining allowance 0.002-0.05 mm SCr420 material, the vibration frequency. 50Hz, single amplitude 0.8m
When processed under the processing conditions of m, moving speed of 40 mm / min, and rotation speed of 800 rpm, a torque of 40 to 52.5 kg
cm, thrust 10 to 22.5 kgf, it was possible to process without trouble. In this case, it was confirmed that the chips were finely divided. Further, the processing accuracy is a surface roughness of 0.9 to 1.5R.
z, roundness 1 to 2.5 μm, variation of processed hole diameter 8 μ
m, and the deflection was 15 μm (MAX).

On the other hand, in an attempt, the same material as described above was used, and the moving speed was 40 mm / min and the rotation speed was 80 without vibration.
When the finish processing is performed under the processing condition of 0 rpm, the torque is 1
At 38 kgcm and thrust of 40 kgf, chips were not divided and welding was generated on the reamer, which caused abnormal noise, so that none of them could be machined.

(Embodiment 2) Next, first, the bite portion 7c.
(Rough machining part) Vibration frequency 50Hz, Amplitude 0.8m
m, rotation speed 800 rpm, feed at 40 mm / min, and after passing through the biting portion 7c and entering the large diameter cylindrical portion 7b, the vibration frequency is 20 Hz and the amplitude is 0.4 mm.
As a result, when the processing was performed as it was without changing the rotation speed and the feed, the finished surface roughness was improved to 0.7 Rz. This is because a large part of the stock removal is removed in the chamfered portion 7c which is a rough processing portion, and the large diameter cylindrical portion 7b which is a finishing portion.
In the above, it is due to the effect of improving the surface roughness.

In the embodiment, the blade portion 7 of the reamer uses a tool in which hard abrasive grains are fixed to the outer periphery of a cylindrical portion 7b having a bite 7c at its tip, but the invention is not limited to this. It goes without saying that a groove in the axial direction or a twist groove may be provided on the outer circumference, or a ream of ordinary shape to which hard abrasive grains are fixed may be used. Further, in the above-mentioned embodiment, the table is subjected to low frequency vibration, but instead of this, the reamer side, that is, the low frequency vibration is applied to the chuck and rotated to perform hole finishing. Good results have been obtained. Although the chuck also uses a floating chuck in the embodiment, a fixed shaft chuck may be used instead.

[0016]

[Effect] In the vibration finishing method of a high hardness material according to the present invention, as described above, the tool is rotated and the grinding is performed while vibrating the work or the tool at a low frequency. Grinding chips can be divided and subdivided for grinding.Therefore, as shown in the example, there are many excellent effects such as high precision hole finishing without chip clogging and longer tool life. Was obtained.

[Brief description of drawings]

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

[Explanation of symbols]

 1. ． ． ． ． ． ． Work 2. ． ． ． ． ． ． Work hole 3. ． ． ． ． ． ． Work support plate 4. ． ． ． ． ． ． Tool escape hole 5. ． ． ． ． ． ． Vibration table 6. ． ． ． ． ． ． Reamer 7. ． ． ． ． ． ． Blade 8. ． ． ． ． ． ． Shank 9. ． ． ． ． ． ． Chuck

 ─────────────────────────────────────────────────── (72) Inventor Hideo Igarashi 20 Ishigane, Toyama, Toyama, Toyama Prefecture Fujikoshi Co., Ltd. (72) Inventor Tadao Matsui 20, Ishigane, Toyama, Toyama, Japan Fujikoshi, Ltd.

Claims (3)

[Claims] 1. A shank of a reamer having hard abrasive grains fixed to a blade is gripped by a chuck capable of rotating and moving up and down, and a work is placed on a mounting surface of a work supporting plate having a tool escape hole, Then, the hole of the work and the axis of the reamer are aligned, the reamer is opposed to the hole of the work, and then the reamer is rotated at a rotation speed of 10 m / min to 300 m / min,
Simultaneously with the start of grinding, the workpiece has an amplitude of 0.1 mm to 3.0 mm in the axial direction of the reamer and a frequency of 5 Hz to 500 Hz.
A reaming vibration finishing method for a hole of a high hardness material, characterized by finishing a high hardness material while giving a low frequency vibration of Hz. 2. A low-frequency vibration having an amplitude of 0.1 mm to 3.0 mm and a frequency of 5 Hz to 500 Hz is applied to the chuck holding the reamer in the axial direction of the reamer.
A reaming vibration finishing method for the hole of the high hardness material described. 3. A reaming vibration finishing process for a hole of a high hardness material according to claim 1 or 2, wherein the frequency and the amplitude of the chamfered portion during machining are larger than the frequency and the amplitude of the cylindrical portion during machining. Method.