# US 2018/0021907 A1 · Spindle device and machine tool

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- Number: US 2018/0021907 A1
- Document ID: US20180021907A1
- Status: Published application
- Kind: A1
- Application number: 15/546,485
- Filed: 2016-02-15
- Published: 2018-01-25
- Earliest claimed: 2015-02-16
- Assignees: Nsk Ltd.
- Applicants: Nsk Ltd.
- Inventors: Hidekazu SUZUKI; Atsushi ISHIKAWA
- Web page: https://patentgrep.com/patent/US20180021907A1

## CPC

- B23Q 11/12: Arrangements for cooling or lubricating parts of the machine (B23Q11/14 takes precedence {; movable work or tool supports using fluid bearings or fluid cushion supports B23Q1/38; cooling or lubricating means used in the working area B23Q11/10})
- B23Q 1/70: Stationary or movable members for carrying working-spindles for attachment of tools or work {(B23Q1/01 takes precedence; designed to be moved by using particular mechanisms B23Q1/44)}
- B23Q 5/10: driven essentially by electrical means
- B23Q 11/127: {for cooling motors or spindles}
- B23Q 2220/006: Spindle heads
- B23Q: DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING (tools of the kind used in lathes or boring machines B23B27/00); MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT

## Abstract

A cooling gas is fed from an ejection nozzle into the interior of a through-hole which is formed in a radially central portion of a main spindle, and which penetrates through said main spindle in an axial direction. The cooling gas passes through radial venting holes provided in a plurality of locations, in the circumferential direction, in an axially intermediate portion of the main spindle, is fed into axial venting holes provided in a plurality of locations, in the circumferential direction, extending from one axial-direction end of the main spindle to an intermediate portion thereof, is caused to flow through the axial venting holes, and is discharged from discharge holes.

## Claims

### Claim 1

A spindle device comprising:
a housing;
a spindle of which a part close to one axial end is rotatably supported to the housing by a rolling bearing or a rolling bearing unit and of which one axial end portion is mounted with a tool when using; and
an electric motor configured to rotatively drive the spindle;
wherein the electric motor is configured such that an inner peripheral surface of a stator supported to the housing faces an outer peripheral surface of a rotor supported and fixed to an axially intermediate portion of the spindle;
wherein a radially central portion of the spindle is formed with a through-hole configured to axially penetrate the spindle,
wherein radial venting holes configured to communicate an outer peripheral surface and an inner peripheral surface of the spindle are provided at a plurality of circumferential locations of a part closer to one axial side than a part, to which the rotor is supported and fixed, of the axially intermediate portion of the spindle,
wherein axial venting holes configured to communicate one axial end face of the spindle and inner peripheral surfaces of the respective radial venting holes are respectively provided at a plurality of circumferential locations of one axial end portion to the axially intermediate portion of the spindle,
wherein discharge holes configured to communicate the outer peripheral surface of the spindle and inner peripheral surfaces of the respective axial venting holes are respectively provided at a plurality of circumferential locations of a part positioned closer to one axial side than a part, to which the rolling bearing or the rolling bearing unit is externally fitted, of a part close to one axial end of the spindle.
wherein an outer diameter-side opening of each radial venting hole is closed by an inner peripheral surface of the rolling bearing or the rolling bearing unit or another member externally fitted and fixed to the outer peripheral surface the spindle,
wherein one axial end portion of the housing is provided with a closing plate,
wherein an inner peripheral surface of the closing plate closely faces the outer peripheral surface of a part, which is between the part to which the rolling bearing or the rolling bearing unit is externally fitted and the part at which the respective discharge holes are provided, of the part close to one axial end of the spindle via an annular gap,
wherein an outer diameter side opening of each discharge hole is positioned at a more radially inner side than one axial side opening of the annular gap, and
wherein when using the spindle device, a cooling gas is fed from the other axial opening of the through-hole and is discharged from each discharge hole through each axial venting hole and each radial venting hole.

### Claim 2 (depends on 1)

The spindle device according to claim 1,
wherein the respective radial venting holes are provided at a plurality of circumferential locations of a part, which is between the part to which the rolling bearing or the rolling bearing unit is externally fitted and the part to which the rotor is supported and fixed, of the axially intermediate portion of the spindle, and
wherein the outer diameter-side opening of each radial venting hole is closed by an outer peripheral surface of a sleeve to which finish processing is performed after the sleeve is externally fitted and fixed to an outer peripheral surface of the part, which is between the part to which the rolling bearing or the rolling bearing unit is externally fitted and the part to which the rotor is supported and fixed, of the axially intermediate portion of the spindle.

### Claim 3 (depends on 1)

A machine tool comprising the spindle device according to claim 1.

### Claim 4 (depends on 2)

A machine tool comprising the spindle device according to claim 2.