JP2009285777A - Spindle device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spindle device which is high in rigidity, capable of suppressing chatter vibration, simple in structure, less in the number of components, and miniaturized. <P>SOLUTION: The spindle device is rotatingly supported at two parts in the axial direction of a spindle 2 by radial bearings 4, 6 to a housing 1, and a tool 3 is fitted to one end of the spindle 2 projected from the housing 1. The radial bearing 4 on the side close to the tool 3 is a hydrostatic bearing, and the radial bearing 6 on the other side is a control type radial magnetic bearing. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a spindle device for machine tools.

  In a spindle device for machine tools, two axial directions of a spindle disposed in a housing are rotatably supported by radial bearings. As this radial bearing, generally, a highly rigid and highly accurate passive bearing such as a rolling bearing, a hydrostatic bearing, and a hydrodynamic bearing is used.

  In the case of such a conventional spindle device, spindle vibration called chatter vibration may occur during machining of a workpiece by a tool depending on machining conditions. This chatter vibration causes problems such as deterioration in accuracy of the finished surface of the workpiece. Chatter vibration is considered to occur when the frequency of the machining force and the resonance frequency of the spindle coincide with each other, and the conventional preventive measure is to reduce the rotation speed of the spindle to a region where chatter vibration does not occur. For this reason, there existed a problem that processing efficiency fell.

  On the other hand, a spindle apparatus has also been proposed in which two axial positions of the spindle are rotationally supported by a control type radial magnetic bearing which is an active type bearing. In the case of a spindle device using a control type radial magnetic bearing, a damping effect can be imparted by control, so chatter vibration can be suppressed, but there is a problem that rigidity deterioration is unavoidable compared to a passive type bearing. there were.

In order to solve such a problem, there has been proposed one that uses two sets of hydrostatic magnetic compound bearings in which an aerostatic bearing and a control type radial magnetic bearing are integrated to rotate and support two axial directions of the spindle. (For example, refer to Patent Document 1).
Japanese Patent No. 3609613

  However, the hydrostatic magnetic composite bearing has a problem that the structure is complicated, the number of parts is large, and the apparatus is enlarged.

  An object of the present invention is to provide a spindle device that solves the above problems, has high rigidity, can suppress chatter vibration, has a simple structure, has a small number of parts, and can be miniaturized.

  The spindle device according to the present invention is a spindle device in which two axial directions of the spindle are rotatably supported by a radial bearing with respect to the housing, and the tool is attached to one end of the spindle protruding from the housing. The hydrostatic bearing is characterized in that the radial bearing on the opposite side is a controlled radial magnetic bearing.

  In the spindle device of the present invention, the machining force is supported by a highly rigid hydrostatic bearing, and chatter vibration can be suppressed by a control type radial magnetic bearing.

  The spindle device of the present invention has only one set of hydrostatic bearing and control type radial magnetic bearing, and has a simpler structure and a smaller number of parts than the case of using two sets of hydrostatic magnetic compound bearings. Less is required and the apparatus can be miniaturized.

  Preferably, the hydrostatic bearing is configured to rotatably support the spindle in the radial direction and the axial direction.

  In this way, it is not necessary to separately provide an axial bearing, and the structure can be simplified and the apparatus can be downsized.

  According to the spindle device of the present invention, as described above, it is highly rigid, can suppress chatter vibration, has a simple structure, has a small number of parts, and can be miniaturized.

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

  FIG. 1 is a longitudinal sectional view showing a main part of a spindle device for machine tools.

  In the following description, the top and bottom of FIG. 1 is the top and bottom, the left side of the figure is the front, the right side is the back, and the left and right when viewing the front from the back is the left and right.

  The spindle device is a horizontal type in which the horizontal spindle (2) rotates inside the horizontal housing (1), and is arranged so that the orientation of the spindle (2) is the front-rear direction.

  The axial direction of the spindle (2), that is, the longitudinal axis (axial axis) is the Z axis, the vertical direction of the two radial (radial direction) control axes (radial control axes) orthogonal to the Z axis and orthogonal to each other The X axis is the control axis, and the Y axis is the left and right control axis.

  The front part of the spindle (2) protrudes forward from the housing (1), and the tool (3) is fixed to the front end part thereof.

  The hydrostatic bearing (4), built-in type electric motor (5), control type radial magnetic bearing (6), radial displacement sensor unit (7) and protective bearing (touchdown bearing) (8) are housed in the housing (1). Is provided.

  The hydrostatic bearing (4) supports the spindle (2) in a non-contact manner in the radial direction and the axial direction, and is disposed on the front side of the spindle (2) closest to the tool (3). The hydrostatic bearing (4) includes a front radial bearing (10) and a rear thrust bearing (11). The inner peripheral surface (12) of the radial bearing portion (10) is a cylindrical surface facing the outer peripheral surface of the spindle (2), and the recess (13) is provided at a plurality of locations that equally divide the inner peripheral surface in the circumferential direction. Is formed. Although illustration is omitted, oil is supplied to these recesses (13) through the oil flow path, so that the spindle (2) is supported in a non-contact manner in the radial direction. The thrust bearing portion (11) includes two thrust surfaces (15) facing the front and rear end surfaces near the outer periphery of the flange portion (14) formed on the spindle (2). Recesses (16) are formed at a plurality of locations equally divided in the circumferential direction. Although illustration is omitted, oil is supplied to these recesses (16) through an oil flow path, and thereby the spindle (2) is supported in a non-contact manner in the axial direction.

  The radial magnetic bearing (6) supports the spindle (2) in a non-contact manner in the radial direction, and is disposed at the rear of the spindle (2) farther from the tool (3) than the hydrostatic bearing (4). Yes. The radial magnetic bearing (6) has a pair of upper and lower radial electromagnets (17) arranged so as to sandwich the spindle (2) from both sides in the X-axis direction, and the spindle (2) from both sides in the Y-axis direction. A pair of left and right radial electromagnets (not shown) are provided.

  The radial displacement sensor unit (7) is for detecting a radial displacement of the spindle (2) from the flying target position, and is disposed immediately behind the radial magnetic bearing (6). The unit (7) includes a pair of upper and lower radial displacement sensors (18) arranged so as to sandwich the spindle (2) from both sides in the X axis direction in the vicinity of the radial electromagnet (17) in the X axis direction, and the Y axis direction. A pair of left and right radial displacement sensors (not shown) are provided in the vicinity of the radial electromagnet so as to sandwich the spindle (2) from both sides in the Y-axis direction.

  The displacement of the spindle (2) in the X-axis direction is detected from the output of the pair of radial displacement sensors (18) in the X-axis direction, and the output of the spindle (2) is detected from the output of the pair of radial displacement sensors in the Y-axis direction. A displacement in the Y-axis direction is detected. Based on these displacements, the spindle (2) is moved to the target position by controlling the excitation current supplied to the pair of radial electromagnets (17) in the X-axis direction and the pair of radial electromagnets in the Y-axis direction. Is supported in a non-contact manner.

  The electric motor (5) is for rotating the spindle (2) at a high speed, and is disposed between the hydrostatic bearing (4) and the radial magnetic bearing (6). The electric motor (5) includes a stator (19) on the housing (1) side and a rotor (20) on the spindle (2) side.

  The protective bearing (8) is for mechanically supporting the spindle (2) when the spindle (2) is not supported by the radial magnetic bearing (6), and is provided after the radial displacement sensor unit (7). Arranged on the side. The protective bearing (8) consists of a rolling bearing, in this example two angular ball bearings. The outer ring of each bearing is fixed to the housing (1), and the inner ring is spaced apart from the outer peripheral surface of the spindle (2). Are arranged.

  In the above spindle apparatus, the processing force is supported by the highly rigid hydrostatic bearing (4), and chatter vibration can be suppressed by the control type radial magnetic bearing (6).

  And it has only one set of hydrostatic bearing (4) and control type radial magnetic bearing (6), and the structure is simpler than the case of using two sets of hydrostatic magnetic compound bearings. Therefore, the apparatus can be miniaturized.

  In addition, the hydrostatic bearing (4) supports the spindle (2) in the radial and axial directions, so there is no need to provide a separate axial bearing, and the structure can be simplified and the device can be downsized. It is.

  However, it is also possible to separately provide an axial bearing as a hydrostatic bearing that rotatably supports the spindle (2) only in the radial direction.

  The overall configuration of the spindle device or the configuration of each unit is not limited to that of the above embodiment, and can be changed as appropriate.

FIG. 1 is a longitudinal sectional view of a spindle apparatus showing an embodiment of the present invention.

Explanation of symbols

(1) Housing
(2) Spindle
(3) Tool
(4) Hydrostatic bearing
(6) Control type radial magnetic bearing



Since the drawings attached to the request form were small and difficult to understand, the drawings and their descriptions may be incorrect. Please check carefully.

Claims (2)

In a spindle apparatus in which two axial directions of the spindle are rotatably supported by a radial bearing with respect to the housing, and a tool is attached to one end of the spindle protruding from the housing.
A spindle device characterized in that the radial bearing on the side close to the tool is a hydrostatic bearing and the radial bearing on the opposite side is a control type radial magnetic bearing.   2. The spindle apparatus according to claim 1, wherein the hydrostatic bearing is configured to rotatably support the spindle in a radial direction and an axial direction.

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