JP2003240006A - Main shaft support structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a main shaft support structure preventing a trouble such as galling of a main shaft bearing even if a main shaft is a high speed main shaft by appropriately controlling temperature rise of the main shaft bearing without causing malfunction such as loss of retaining capacity of the main shaft bearing and environmental pollution due to discharge of oil. <P>SOLUTION: Outer rings 58, 68 of the main shaft bearings 5, 6 are fitted in a ferrous metal outer ring case 9. The outer ring case 9 is supported by an outer shell member 10 composed of material of high thermal conductivity such as aluminum alloy and an outer surface 10D of the outer shell member 10 is used as a natural radiation surface. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle support structure, and more particularly to a high speed spindle support structure.

[0002]

2. Description of the Related Art In recent years, in order to process free-form surfaces such as molds at high speed, it has been desired to increase the speed of the spindle, and the required spindle speed is about 20,000 rpm and feed rate is 2.
It has reached about 0 m / min. When the spindle speed is increased,
Regardless of how the spindle bearing is lubricated, the amount of heat generated by the spindle bearing increases.

The main shaft bearing holds the main shaft by the inner ring and holds the outer ring by the outer ring case made of steel or casting, and the steel or casting easily accumulates heat and has the ability to release the amount of heat generated by high speed rotation. Due to the lack, the bearing temperature rises, the main shaft bearing tends to "scratch", and the normal operation tends to stop.

For this reason, conventionally, cooling oil is made to flow through the outer ring case or the main shaft, or the main shaft bearing is lubricated and cooled by an oil mist.

[0005]

However, in order to suppress the rise in bearing temperature using oil, it is necessary to control the temperature of the oil and adjust the flow rate, and also to change the viscosity of the oil due to changes in temperature and to use oil. There are various problems such as adverse effects on the environment due to.

On the other hand, when a material having a high thermal conductivity such as aluminum alloy is used for the outer ring case of the main shaft bearing, the heat release capability is increased, but a material having a high thermal conductivity such as aluminum alloy is a steel material. Since it has a large coefficient of thermal expansion and is easily deformed by heat as compared with cast iron, it loses its ability to hold the spindle bearing due to heat generation of the spindle bearing and cannot be used.

The present invention has been made in order to solve the above-mentioned problems, and does not cause problems such as loss of holding ability of the main shaft bearing, and does not cause environmental pollution due to oil discharge. An object of the present invention is to provide a spindle support structure that appropriately suppresses the temperature rise of the spindle bearing and prevents the spindle bearing from causing an obstacle such as "galling" even in a high-speed spindle.

[0008]

In order to achieve the above object, a spindle support structure according to the present invention is a spindle support structure in which a spindle is rotatably supported by a spindle bearing in which the spindle is fitted to an inner ring. The outer ring of the bearing is fitted to the outer ring case made of a ferrous metal, and the outer ring case is surrounded and supported by an outer shell member made of a material having a higher thermal conductivity than the outer ring case, for example, an aluminum alloy or a copper alloy. The outer surface of the outer shell member is a natural heat dissipation surface.

According to this main shaft support structure, since the outer ring case is made of iron-based metal, the holding ability of the main shaft bearing is guaranteed, and the outer ring case is surrounded and supported by the outer shell member made of the high thermal conductivity material. As a result, natural heat is radiated from the outer surface of the outer shell member, effective natural cooling is performed, and the temperature rise of the spindle bearing is suppressed.

Further, an air passage is provided between the outer ring case and the outer shell member, and air is passed through the air passage, whereby the cooling effect of the main shaft bearing is further improved.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows one embodiment of a spindle support structure according to the present invention.

In FIG. 1, reference numeral 1 denotes a build-in type spindle 1, to which a rotor 2 of a build-in spindle motor is fixed. A stator 4 of a built-in spindle motor is attached to a cast iron spindle head (motor case) 3.

The main shaft 1 has a rolling bearing 2 on the front end side.
It is rotatably supported by individual spindle bearings 5 and 6. Main shaft bearings 5 and 6 are inner rings 5A and 6A, respectively.
Is fitted to the outer circumference of the main shaft 1, in other words, the inner rings 5A, 6
The spindle 1 is fitted to A. The inner rings 5A and 6A are the main shaft 1
The stepped portion 1A formed on the outer periphery of the inner ring, the inner ring sleeve 7 arranged between the inner rings 5A and 6A, and the stepped sleeve 8 fixed by shrink fitting on the outer periphery of the main shaft 1 perform the fixing in the thrust direction. It is being appreciated.

The main shaft bearings 5 and 6 have outer rings 5 respectively.
B and 6B are fitted into the inner tubular portion 9A of the tubular outer ring case 9. The outer ring case 9 is made of steel or iron-based metal such as cast iron. A tubular outer shell member 10 with a flange is fitted around the outer ring case 9, and the outer ring case 9 is supported by the outer shell member 10 so as to be surrounded.

The outer shell member 10 is made of a material having a higher thermal conductivity than that of the steel material or the cast metal forming the outer ring case 9, for example, an aluminum alloy or a copper alloy, and the outer ring case 9 is attached to the inner cylindrical portion 10A. When fitted, the entire outer circumference of the outer ring case 9 is tightly surrounded by the tubular portion 10B in a heat conductive relationship.
The flange portion 10C is fixed to the tip portion of the spindle head 3 by a bolt or the like not shown. Outer shell member 1
The outer surface 10D, which is exposed to the outside air, is set to 0 as a natural heat dissipation surface.

An air passage 12 is formed between the outer ring case 9 and the outer shell member 10 by a groove 11 formed in the inner peripheral surface (inner tubular portion 10A) of the outer shell member 10. High pressure air at a room temperature level is supplied to the air passage 12 from a high pressure air source (not shown).

A ring member 13 is attached to the outer periphery of the tip of the main shaft 1, and an outer ring holding ring 14 and an end cover 15 are attached to the tip surfaces of the outer ring case 9 and the outer shell member 10, respectively. A seal structure is configured. Outer ring 5B of main shaft bearings 5 and 6,
6B is an outer ring retaining ring 14, an outer ring sleeve 16,
The step portion 9B formed on the inner circumference of the outer ring case 9 fixes the thrust direction. Further, an inner ring member 17 is attached to the stepped sleeve 8, an outer ring case 9 and an outer ring member 18 are attached to the outer shell member 10, and these form a labyrinth seal structure between the main shaft bearing portion and the main shaft motor portion. ing.

According to the above configuration, the heat generated in the main shaft bearings 5 and 6 with the rotation of the main shaft 1 is transferred to the main shaft 1 and the outer ring case 9. The heat transferred to the outer ring case 9 is transferred from the outer peripheral surface of the outer ring case 9 to the outer shell member 10 in close contact with the outer peripheral surface by heat conduction. The outer shell member 10 is made of an aluminum alloy or a copper alloy, and has a higher thermal conductivity than steel materials and castings that form the outer ring case 9, so that the outer shell member 10 receives heat more efficiently than the entire outer circumference of the outer ring case 9 and enters the outside air. The exposed outer surface 10D is naturally cooled by using a natural heat radiation surface.

Further, the outer ring case 9 and the outer shell member 10
Is also cooled (air-cooled) by the high-pressure air flowing through the air passage 12.

The operation and effect of the main shaft support structure having the above-mentioned structure can be summarized as follows: Outer rings 5B and 6 of the main shaft bearings 5 and 6, respectively.
Since B is fitted in the outer ring case 9 made of a ferrous metal, there is no problem such as loss of the holding ability of the main shaft bearings 5 and 6 even if the temperature rises.

The outer ring case 9 is surrounded and supported by an outer shell member 10 made of a material having high thermal conductivity, and the outer surface 10 of the outer shell member 10 is surrounded.
Since natural heat is dissipated from D, effective natural cooling is performed, the temperature rise of the spindle bearings 5 and 6 is suppressed, and the spindle bearings 5 and 6 are "scratched" even in high-speed spindles.
It does not cause problems such as. Further, the air flowing through the air passage 12 cools the outer ring case 9 and the outer shell member 10 to further improve the cooling effect of the main shaft bearings 5 and 6, so that the main shaft bearings 5 and 6 may be damaged by "striking" or the like. It will be even harder to occur.

Since no oil mist or the like is used, it is not necessary to control the temperature of oil or adjust the flow rate, and there is no risk of environmental pollution due to oil discharge.

As can be understood from the above description, according to the main shaft support structure of the present invention, the outer ring case is made of iron-based metal, so that the holding ability of the main shaft bearing is assured and the outer ring case is ensured. Is surrounded and supported by an outer shell member made of a high thermal conductivity material, and natural heat is radiated from the outer surface of the outer shell member. Therefore, effective natural cooling is performed, the temperature rise of the main shaft bearing is suppressed, and the main shaft bearing is suppressed. Is "Kajiri"
It will not cause problems such as.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a spindle support structure according to the present invention.

[Explanation of symbols]

1 spindle 5, 6 Spindle bearing 9 outer ring case 10 Outer shell member 12 air passages

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Claims (3)

[Claims] 1. A spindle support structure in which a spindle is rotatably supported by a spindle bearing having a spindle fitted in an inner ring, wherein an outer ring of the spindle bearing is fitted in an outer ring case made of a ferrous metal, and the outer ring case is A spindle support structure, which is surrounded and supported by an outer shell member made of a material having a higher thermal conductivity than that of an outer ring case, and the outer surface of the outer shell member is a natural heat dissipation surface. 2. The spindle support structure according to claim 1, wherein the outer shell member is made of an aluminum alloy or a copper alloy. 3. The spindle support structure according to claim 1, wherein an air passage is provided between the outer ring case and the outer shell member.