JP2019104066A - Spindle device and machine tool - Google Patents

Abstract

To provide a spindle device which adopts a non-contact bearing and enables improvement of measurement accuracy even when a contact sensor is attached to a spindle to measure a workpiece.SOLUTION: This spindle device 100 includes: a spindle 10; a non-contact bearing 20 which supports the spindle 10 in a non-contact manner so that the spindle 10 can rotate around a center axis; a drive part 30 which rotationally drives the spindle 10; and a tool holding part 40 which is provided at one end part of the spindle 10 and detachably holds a tool 1 or a contact sensor 2 for measuring a workpiece 3. The non-contact bearing 20 is configured to be switchable to a measurement state P2, in which movement of the spindle 10 is inhibited, by supporting the spindle 10 in a contact state when the contact sensor 2 is attached to the tool holding part 40.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a spindle device and a machine tool, and more particularly to a spindle device and a machine tool having a spindle on which a sensor for measuring a workpiece can be mounted instead of a tool.

  Conventionally, a spindle device provided with a spindle capable of mounting a sensor for measuring a workpiece instead of a tool is known (see, for example, Patent Document 1).

  Patent Document 1 discloses a spindle device provided with a spindle, a bearing for rotatably supporting the spindle, a motor for rotationally driving the spindle, and a tool clamping mechanism provided at the tip of the spindle. At the tip of the spindle, either the tool for processing the workpiece or the measuring head for measuring the diameter of the processing location of the workpiece can be exchanged and detached by the tool clamping mechanism.

  Although not specified in the above-mentioned Patent Document 1, it is considered that the bearing of the main shaft is a contact type ball bearing.

Unexamined-Japanese-Patent No. 2006-326804

  Here, as the bearing of the spindle device, in addition to a contact type rolling bearing such as a ball bearing, a non-contact bearing such as a static pressure fluid bearing may be adopted. Non-contact bearings are characterized in that they have low coefficient of friction and low heat generation as compared with contact type bearings, but have low bearing rigidity and can easily move the main shaft by a gap with the bearings due to external force. Therefore, in a spindle device adopting a non-contact bearing, when mounting a contact sensor as a measuring head on a spindle to measure a workpiece, the spindle is displaced due to the contact reaction force from the workpiece, and accurate measurement There is a problem that it becomes difficult. Therefore, in a spindle device adopting a non-contact bearing, it is desirable that measurement accuracy can be improved even when a workpiece is measured by mounting a contact sensor on the spindle.

  The present invention has been made to solve the problems as described above, and one object of the present invention is to measure a workpiece by mounting a contact sensor on a main shaft in a main spindle device adopting a non-contact bearing. It is an object of the present invention to provide a spindle device and a machine tool capable of improving the measurement accuracy even when performing.

  The spindle device according to the first aspect of the present invention comprises a spindle, a non-contact bearing rotatably supporting the spindle in a non-contact manner about a central axis, a drive unit for rotationally driving the spindle, and one end of the spindle And a tool holding portion for detachably holding a contact sensor for measuring a workpiece or a tool for processing a workpiece, and the non-contact bearing supports the main shaft in a contact state when the contact sensor is mounted. It is configured to be switchable to a measurement state that suppresses movement of

  In this spindle device, by configuring the non-contact bearing as described above, when measuring the work by mounting the contact sensor on the tool holding portion, the non-contact bearing is switched to the measurement state, and the non-contact bearing is The spindle can be supported in contact. Therefore, when the contact reaction force of the contact sensor acts on the main shaft, positional deviation of the main shaft due to the contact reaction force can be suppressed as compared with the case where the main shaft is held in the non-contact state. Although there are various methods for suppressing positional deviation depending on the relationship between the contact direction of the non-contact bearing and the main shaft and the action direction of the contact reaction force, movement restriction by directly supporting the contact reaction force on the bearing surface, contact As a result, there is an increase in frictional resistance, and the generation of adhesion due to surface contact between the bearing surface and the opposing surface on the spindle side.

  That is, when the main shaft is brought into contact with the non-contact bearing in the direction of action of the contact reaction force, the main shaft supported by the bearing surface of the non-contact bearing no longer moves. Can be suppressed. When the main shaft is brought into contact with the non-contact bearing in the direction intersecting the contact reaction force, the movement of the main shaft can be suppressed by the increase of the frictional force at the contact point. When the main shaft is brought into contact with the non-contact bearing in the direction opposite to the contact reaction force, the main shaft can be supported by the generation of adhesion between the bearing surface and the opposing surface on the main shaft side. That is, generally, the bearing surface and the opposing surface on the main shaft side are smoothed by lapping or the like, and therefore, once the bearing surface and the opposing surface come in surface contact, they are strongly in contact and the movement of the spindle can be suppressed. As a result of these, by performing measurement in a state in which the noncontact bearing is switched to the measurement state, in the spindle device adopting the noncontact bearing, even when the workpiece is measured by mounting the contact sensor on the spindle, measurement accuracy is improved. It can be improved.

  In the spindle device according to the first aspect, preferably, the non-contact bearing includes an axial bearing portion axially supporting the spindle from both axial sides and a radial bearing portion radially supporting the spindle. In the state, the axial bearing surface of the axial bearing portion and the axially opposed surface of the main shaft are configured to be in contact with each other in the axial direction. According to this structure, the axial bearing surface and the axially facing surface of the main shaft can be brought into surface contact in the axial direction. As a result, due to the close contact between the surfaces, it is possible to effectively suppress the displacement of the main shaft against the contact reaction force in the axial direction from the contact sensor and also against the contact reaction force in the radial direction. Further, since the axial position of the main shaft is positioned at the contact position with the axial bearing surface of the non-contact bearing, the axial position accuracy of the main shaft can be improved. As a result, it is possible to measure the workpiece with higher accuracy.

  In this case, preferably, the axial bearing portion includes one non-contacting axial bearing surface for supporting the main shaft from one end and the other axial bearing surface for supporting the main shaft from the other end opposite to the one end. The bearing is configured such that, in the measurement state, the one axial bearing surface is separated from the main shaft, and the other axial bearing surface is in contact with the axial opposing surface of the main shaft. According to this structure, the other axial bearing surface comes in contact with the axial opposing surface of the spindle from the other end side, so that the contact reaction force in the axial direction from the contact sensor pushes the spindle (toward the other end of the spindle Also in the case of acting in the direction), the movement of the spindle can be reliably prevented. Then, the axial position of the main shaft can be positioned at the contact position with the other axial bearing surface. As a result, it is possible to realize both the prevention of positional deviation due to the contact reaction force and the improvement of the positional accuracy in the axial direction of the spindle in the measurement state.

  In a configuration in which the noncontact bearing includes an axial bearing portion and a radial bearing portion, preferably, the noncontact bearing is a hydrostatic fluid bearing, and further comprising a fluid circuit that controls pressure supply to the hydrostatic fluid bearing, The fluid circuit brings the axial bearing surface into contact with the axially facing surface by weakening or interrupting the supply pressure of either one of the one end and the other end of the axial bearing portion relative to the other one. It is configured. According to this structure, the axial bearing surface can be easily brought into contact with the axially facing surface simply by adjusting (weakening or blocking) the pressure supplied to the hydrostatic fluid bearing. Further, since it is only necessary to use a fluid circuit for supporting the main shaft in a noncontact manner by the hydrostatic fluid bearing, the device configuration is not complicated even when the axial bearing surface and the axially facing surface are brought into contact with each other.

  In this case, preferably, the hydrostatic fluid bearing is a hydrostatic air bearing, and the fluid circuit includes a switching valve that switches between supply and shutoff of air pressure to either one of the axial bearings. According to this structure, it is possible to easily switch to the measurement state in which the axial bearing surface and the axial facing surface are in contact with each other with a simple configuration in which only the switching valve is provided.

  The spindle device according to the first aspect of the present invention preferably further includes a biasing unit that brings the spindle into contact with the non-contact bearing by biasing the spindle in the axial direction in the measurement state. According to this structure, it is possible to easily switch to the measurement state by the biasing unit. When a dedicated biasing unit is provided to bring the spindle into contact with the noncontact bearing, the biasing force is set in accordance with the magnitude of the contact reaction force from the contact sensor, whereby the displacement of the spindle can be reduced. It can be suppressed sufficiently.

  In the spindle device according to the first aspect, preferably, a determination unit that determines that the contact sensor is attached to the tool holding unit from the tool replacement device, and noncontact when the contact sensor is attached to the tool holding unit And a control unit that performs control to switch the bearing to the measurement state. According to this structure, the measurement state can be switched to the measurement state when it is determined that the contact sensor is attached to the tool holding unit, regardless of whether measurement before the start of machining by the tool or measurement during the machining. As a result, it is not necessary for the user to switch to the measurement state, and the non-contact bearing can be reliably switched to the measurement state at the time of measurement by the contact sensor.

  In the spindle device according to the first aspect, preferably, the tool holder has a straight shank tool and a collet member capable of directly holding a contact sensor. According to this structure, unlike the case of attaching and detaching the collet-equipped tool (contact sensor), it is possible to miniaturize the tool while reducing the number of parts because it is not necessary to provide the collet chuck for each tool (contact sensor). Therefore, even when the tool changer is provided with the contact sensor, the size of the device does not increase.

  In the spindle device according to the first aspect, preferably, the drive unit includes an induction motor, and the noncontact bearing is configured to stop the rotation of the spindle by contact with the spindle in the measurement state. Here, when the induction motor is adopted, the spindle spins if the spindle is not driven. Therefore, when the contact sensor is mounted on the tool holding portion, if the central axis of the spindle and the central axis of the contact sensor do not coincide exactly, the tip of the contact sensor will swing and measurement will occur due to variations in the contact position. It becomes a factor to reduce the accuracy. Therefore, according to the above configuration, the workpiece can be measured by the contact sensor in a state in which the rotation of the spindle is reliably stopped in the measurement state, so that special motor control is performed in the configuration adopting the induction motor. Measurement accuracy can be easily improved without.

  The machine tool according to the second aspect of the present invention comprises the spindle device according to any of the first aspect, a moving mechanism for relatively moving the spindle device and the work, a tool and a contact sensor to the spindle of the spindle device. And a tool changer which detachably holds.

  In this machine tool, by configuring as described above, as in the case of the spindle device according to the first aspect, when the contact sensor is mounted on the tool holding portion to measure the workpiece, the non-contact bearing is measured The main shaft can be supported in a contact state, so that when the contact reaction force of the contact sensor acts on the main shaft, compared to the case where the main shaft is held in a non-contact state, Misalignment can be suppressed. As a result, in a machine tool provided with a spindle device employing non-contact bearings, measurement accuracy can be improved even when the contact sensor is mounted on the spindle to measure a workpiece.

  According to the present invention, as described above, in a spindle device adopting a non-contact bearing, measurement accuracy can be improved even when a workpiece is measured by mounting a contact sensor on the spindle.

BRIEF DESCRIPTION OF THE DRAWINGS It is the model which showed the whole structure of the machine tool provided with the spindle apparatus by 1st Embodiment. 1 is a schematic vertical sectional view showing a spindle device according to a first embodiment. It is a typical expanded sectional view of a tool attaching part for explaining composition of a tool attaching part, and tool exchange. It is a schematic diagram of a spindle device for explaining a processing state. It is a schematic diagram of a spindle device for explaining a measurement state. It is a flowchart for demonstrating the flow of the measurement process using a contact sensor. They are a figure (A) showing measurement of a reference gauge, and a figure (B) showing measurement of a work. It is a typical longitudinal section showing a spindle device by a 2nd embodiment. It is a schematic diagram of the spindle apparatus for demonstrating the measurement state in 2nd Embodiment. It is a schematic diagram showing the 1st modification of a tool attaching part. It is the schematic diagram which showed the holding | grip state (A) of the 2nd deformation | transformation of a tool holding | maintenance part, and the cancellation | release state (B). It is a schematic diagram which showed the modification of the measurement state shown in FIG.

  Hereinafter, embodiments of the present invention will be described based on the drawings.

First Embodiment
A spindle device 100 according to a first embodiment and a machine tool 200 provided with the spindle device 100 will be described with reference to FIGS. 1 to 5.

(Overview of spindle device and machine tool)
As shown in FIG. 1, the spindle device 100 rotates the tool 1 mounted on one end of the spindle 10 by rotationally driving the spindle 10 (see FIG. 2) about the central axis, and the workpiece is a workpiece It is an apparatus for processing a certain work 3. The spindle device 100 is assembled to the machine tool 200, and is moved relative to the work 3 by the moving mechanism 110 provided in the machine tool 200. The machine tool 200 is a numerical control (NC) machine tool, which controls the relative movement (position and velocity) between the tool 1 and the workpiece 3 with numerical information, and executes a series of operations related to machining by the program 132. Specifically, the machine tool 200 is a machining center provided with the spindle device 100 and the tool changer 120, and can perform various kinds of machining such as drilling, boring and milling by replacing the tool 1 with the spindle device 100. .

  In the first embodiment, as an example, an example will be described in which the workpiece 3 is a mold for an optical lens and the machine tool 200 performs precision processing of the mold. The spindle device 100 and the machine tool 200 according to the first embodiment can measure the workpiece 3 with high accuracy by the contact sensor 2 and is therefore particularly suitable for performing precision machining such as production of a mold requiring high accuracy. It is.

  The machine tool 200 includes a spindle device 100, a moving mechanism 110, and a tool changer 120. Moreover, the machine tool 200 (spindle apparatus 100) includes a control unit 130 that controls these units.

  The moving mechanism 110 is configured to move the spindle device 100 and the workpiece 3 relative to each other. The machine tool 200 relatively moves the spindle device 100 and the work 3 in at least three orthogonal axial directions at least in the vertical direction and in two directions orthogonal to each other in the horizontal plane. As for relative movement between the spindle device 100 and the work 3, only one of the spindle device 100 and the work 3 may move, or both the spindle device 100 and the work 3 may move. In the example of FIG. 1, the moving mechanism 110 moves the spindle device 100 in the Z direction, which is the vertical direction, and in the X direction in the horizontal plane (left and right direction in FIG. 1). It is moved in the orthogonal Y direction (front and back direction perpendicular to the paper surface of FIG. 1).

  FIG. 1 shows an example in which the machine tool 200 is a portal machining center. The machine tool 200 includes a table 140 on which the work 3 is installed, and a bed 141 which supports the table 140 movably in the Y direction. The machine tool 200 includes a pair of columns 142 disposed on both sides of the bed 141 in the X direction, and a cross bar 143 hung around the upper ends of the pair of columns 142. The cross bar 143 extends in the X direction so as to straddle above the table 140 and the bed 141. The cross bar 143 supports the saddle 144 movably in the X direction. The saddle 144 supports the head 145 provided with the spindle device 100 movably in the Z direction.

  The moving mechanism 110 includes a Z-axis moving mechanism 111 for moving the head 145 in the Z direction, an X-axis moving mechanism 112 for moving the saddle 144 in the X direction, and a Y-axis moving mechanism 113 for moving the table 140 in the Y direction. Equipped with Each of Z-axis moving mechanism 111, X-axis moving mechanism 112 and Y-axis moving mechanism 113 includes, for example, a servomotor 114 having a built-in position detector and a linear motion mechanism (not shown) driven by servomotor 114. . In addition, the moving mechanism 110 may be provided with a moving axis more than three axes. For example, the moving mechanism 110 rotates the head 145 around the axis in the Y direction (inclination of the tool 1 of the spindle device 100 with respect to the horizontal plane) and rotates the table 140 around the Z axis (workpiece 3) may be provided with a rotation axis).

  The tool changer 120 has a function of holding a plurality of types of tools 1 in a removable manner, and changing the tools 1 mounted on the spindle 10 of the spindle device 100. In the first embodiment, the tool changer 120 releasably holds the contact sensor 2 in addition to the tool 1. That is, the tool changer 120 is configured to detachably hold the tool 1 and the contact sensor 2 with respect to the spindle 10 of the spindle device 100.

  The tool changer 120 shown in FIG. 1 includes a magazine 121 holding the tool 1 and the contact sensor 2, and a motor 122 driving the magazine 121. The magazine 121 is formed in a disk shape, and has a plurality of holding holes (not shown) along the circumferential direction on the outer peripheral portion. The magazine 121 can hold the tool 1 or the contact sensor 2 in the state of being able to be pulled upward in the respective holding holes. The motor 122 is configured to rotate the magazine 121 around a central rotation axis.

  By rotation of the magazine 121, the desired holding hole of the magazine 121 can be positioned at the tool change position with respect to the spindle device 100. Thereby, the machine tool 200 moves the spindle device 100 to the tool replacement position above the magazine 121, removes the tool 1 or the contact sensor 2 attached to the spindle device 100, and sets it in the holding hole of the tool replacement position. It is possible to mount the tool 1 or the contact sensor 2 held in the holding hole moved to the tool change position to the spindle device 100.

  The control unit 130 is configured to perform operation control of the entire machine tool 200. The control unit 130 is configured by a processor such as a CPU. The control unit 130 includes a storage unit 131 in which various programs 132 for controlling the machine tool 200 including the machining program of the work 3 are stored. The processor executes the program stored in the storage unit 131, whereby the processor operates as the control unit 130 of the machine tool 200. Thus, the control unit 130 performs operation control of the spindle device 100, operation control of the moving mechanism 110, and operation control of the tool changer 120. Control unit 130 is provided, for example, on a control panel of machine tool 200, and is connected to a display unit (not shown) and an input unit (not shown) of the control panel.

(Spindle device)
As shown in FIG. 2, the spindle device 100 includes a spindle 10, a noncontact bearing 20, a drive unit 30, and a tool holding unit 40. The spindle device 100 is packaged as an assembly in which the respective components are accommodated in a housing 50.

  The main shaft 10 is a shaft member provided at the center of the substantially cylindrical housing 50 so as to extend vertically. The main shaft 10 may be a solid shaft member, but in the example of FIG. 2 has a hollow (see FIG. 3) cylindrical shape. The spindle 10 is rotationally driven about the central axis by the drive unit 30 and rotates the tool 1 mounted on a tool holding unit 40 provided at one end (spindle end) of the spindle 10. In the following, for convenience, the side on which the tool holding portion 40 of the spindle 10 is disposed is referred to as one end side (Z1 direction), and the side opposite to the tool holding portion 40 of the spindle 10 is referred to as the other end side (Z2 direction).

  The main shaft 10 is provided with a collar portion 11 protruding radially outward on the outer peripheral surface. The collar portion 11 has a constant thickness and is formed in a disk shape. In the flange portion 11, on the surfaces on one end side (Z1 direction side) and the other end side (Z2 direction side) in the axial direction, an axial facing surface 11a axially facing the non-contact bearing 20 is formed. The main shaft 10 is provided with a shaft portion 12 having a constant outer diameter. The shaft portion 12 is provided with a radial opposing surface 12 a that radially faces the non-contact bearing 20. In addition, the position of the collar part 11 is specifically limited, The collar part 11 may be arrange | positioned with respect to the axial part 12 at one end side (Z1 direction side).

  The tool holding unit 40 is provided at one end of the spindle 10, and is configured to detachably hold the tool 1 for processing the work 3 or the contact sensor 2 for measuring the work 3. The tool holder 40 holds the tool 1 or the contact sensor 2 by engaging the inserted tool 1 or the contact sensor 2 at one end of the hollow spindle 10. The details of the tool holding unit 40 will be described later.

  The non-contact bearing 20 is configured to support the main shaft 10 rotatably about a central axis in a non-contact manner. The non-contact bearing 20 is configured to support the main shaft 10 rotatably about a central axis in a non-contact manner at least when the main shaft 10 is rotationally driven. In other words, when the tool 1 is mounted, the non-contact bearing 20 is configured to be in a processing state P1 (see FIG. 4) that rotatably supports the spindle 10 in a non-contact state. And, in the first embodiment, when the contact sensor 2 is mounted, the non-contact bearing 20 is switchable to the measurement state P2 (see FIG. 5) which suppresses the movement of the main shaft 10 by supporting the main shaft 10 in the contact state. It is configured. As the noncontact bearing 20, a hydrostatic fluid bearing using oil or air as a working fluid, or a magnetic bearing can be employed. In the first embodiment, the non-contact bearing 20 is a hydrostatic fluid bearing, in particular, a hydrostatic air bearing. The static pressure air bearing is a bearing that introduces pressurized gas into the clearance CL between the bearing and the main shaft, and supports in a non-contact manner the load (self weight and contact reaction force) acting on the main shaft 10 by balancing the gas pressure. .

  The noncontact bearing 20 includes an axial bearing portion 21 supporting the main shaft 10 from both sides in the axial direction, and a radial bearing portion 22 supporting the main shaft 10 in the radial direction.

  The axial bearing portion 21 has a pair of axial bearing surfaces disposed on both sides in the axial direction with respect to the flange portion 11 of the main shaft 10. That is, the axial bearing portion 21 includes one axial bearing surface 21a supporting the main shaft 10 from one end and the other axial bearing surface 21b supporting the main shaft 10 from the other end. The first axial bearing surface 21 a and the second axial bearing surface 21 b are both examples of the “axial bearing surface” in the claims. The one axial bearing surface 21a and the other axial bearing surface 21b are each formed in an annular shape as viewed in the axial direction, and are axially opposed to the axial opposing surface 11a of the flange 11 with a minute gap CL therebetween. It is provided. Compressed air is supplied to the axial bearing portion 21 from an air pressure source (positive pressure source) 60 through a fluid circuit 70 described later and a passage portion 51 of the housing 50. Each of the one axial bearing surface 21a and the other axial bearing surface 21b is provided with a throttle hole (not shown) for discharging compressed air to the gap CL with the axial facing surface 11a. As a result, the axial bearing portion 21 balances the pressure of the working fluid (air) supplied from the one side axial bearing surface 21 a and the other side axial bearing surface 21 b to both axial sides of the collar portion 11, thereby the shaft of the main shaft 10. It is possible to provide support in the direction (axial direction) without contact.

  The radial bearing portion 22 has a radial bearing surface 22 a formed concentrically with the shaft portion 12 of the main shaft 10. The radial bearing surface 22 a is provided to be opposed to the radial opposing surface 12 a of the main shaft 10 with a minute gap CL therebetween. Compressed air is supplied to the radial bearing portion 22 via the passage portion 51. The radial bearing surface 22a is provided with a throttle hole (not shown) for releasing the compressed air into a gap CL with the radial opposing surface 12a. Thereby, the radial bearing portion 22 supports the main shaft 10 in the radial direction (radial direction) by balancing the pressure of the working fluid (air) supplied from the radial bearing surface 22a to the gap CL between the radial opposing surface 12a. It is possible to do without contact.

  In addition, two radial bearing portions 22 are provided at positions separated along the axial direction of the main shaft 10. Thereby, the inclination of the main spindle 10 is prevented. The radial bearing portion 22 at the other axial end side is provided in a bearing main body having an L-shaped cross section in common with the axial bearing portion 21.

  These bearing surfaces (one axial bearing surface 21a, the other axial bearing surface 21b, radial bearing surface 22a) and the opposing surfaces of the main shaft 10 (axial) in order to suppress pressure fluctuation and pressure fluctuation during rotational driving of the main shaft 10. The opposing surface 11a and the radial opposing surface 12a are constituted by a lapped surface. That is, these bearing surfaces and the opposing surfaces are formed with extremely small surface roughness and high dimensional accuracy. The size of the clearance CL between the axial bearing portion 21 and the radial bearing portion 22 with respect to the main shaft 10 is, for example, about 8 μm or more and 20 μm or less. The size of the clearance CL between the axial bearing portion 21 and the main shaft 10 and the size of the clearance CL between the radial bearing portion 22 and the main shaft 10 may be different.

  The spindle device 100 includes a fluid circuit 70 that controls pressure supply to the non-contact bearing 20, which is a hydrostatic fluid bearing. The fluid circuit 70 communicates with the non-contact bearing 20 and is connected to an external air pressure source 60 via a pressure control valve 71 (see FIG. 4). As a result, compressed air of a predetermined pressure is supplied to the non-contact bearing 20 via the fluid circuit 70. The air pressure supplied is, for example, about 0.3 MPa or more and about 0.7 MPa or less.

  The drive unit 30 is configured to rotationally drive the main shaft 10. The driving unit 30 is connected to the other end of the main shaft 10, and is configured to directly rotate the main shaft 10 about the central axis. The driving unit 30 is an electric motor capable of rotating at a high speed of about 60000 rpm, and is a built-in motor incorporated in the housing 50. Although a motor can employ | adopt a synchronous motor, an induction motor, etc., in 1st Embodiment, the drive part 30 is comprised by the induction motor. The induction motor generates an induced current in the rotor 32 by the rotating magnetic field generated in the stator 31, and rotates the rotor 32 by the interaction of the magnetic field generated by the induced current and the rotating magnetic field of the stator 31. The rotor 32 is fixed to the main shaft 10. The stator 31 is fixed to the housing 50 so as to surround the radially outer side of the rotor 32.

  In the example of FIG. 2, the spindle device 100 includes a switching mechanism 80 for switching between the chuck (grip) and the release (grip release) of the tool 1 by the tool holding unit 40. The switching mechanism 80 is an actuator 81 provided on the other end side (Z2 direction side) with respect to the main axis 10 and a push rod inserted into the hollow main axis 10 and extending from the other end side to the vicinity of the tool holding portion 40 And 82. The actuator 81 is constituted by, for example, a pneumatic or hydraulic piston, an electric solenoid or the like, and advances and retracts the push rod 82 in the axial direction.

(Replace tool)
In the configuration example of the first embodiment shown in FIG. 3, the tool holding unit 40 is configured to be able to hold the tool 1 or the contact sensor 2 by directly gripping the tool 1 or the shank 1a (2a) of the contact sensor 2 ing. That is, the tool holding portion 40 has the collet member 41 capable of directly holding the straight shank tool 1 and the contact sensor 2.

  Specifically, the tool holding portion 40 includes a collet member 41, a hollow cylindrical sleeve 42 fixed to one end of the main shaft 10, a disc spring 43, and a collet nut 44. One end side of the sleeve 42 is a chuck hole tapered so that the inner diameter decreases toward the other end side (Z2 direction side), and the collet member 41 is inserted. The collet member 41 has a cylindrical shape capable of holding the shank portion 1a (2a) on the inner peripheral side, and is inserted into the sleeve 42 from one end side (Z1 direction side) of the sleeve 42. One end side portion of the collet member 41 is formed in a taper shape corresponding to the chuck hole of the sleeve 42 so that the outer diameter decreases toward the other end.

  The collet member 41 is formed with a notch 41 a extending in the axial direction from the intermediate position to one end. The collet member 41 penetrates the inside of the sleeve 42 and extends to the other end side, and a collet nut 44 is provided at the other end of the collet member 41. The collet member 41 is biased toward the other end (the Z2 direction side) by a disc spring 43 provided between the sleeve 42 and the collet nut 44. As a result of urging the collet member 41 to the back side (Z2 direction side) of the tapered chuck hole of the sleeve 42 by the disc spring 43, one end portion (portion where the notch 41a is formed) of the collet member 41 is in the radial direction It is compressively deformed inward to reduce the inner diameter. The radial compression force acts on the tool 1 or the shank 1a (2a) of the contact sensor 2 inserted into one end of the collet member 41, whereby the tool 1 or the contact sensor 2 is clamped.

  When the push rod 82 is advanced toward the tool holding portion 40 by the actuator 81 of the switching mechanism 80, the tip of the push rod 82 contacts the other end of the collet member 41, and the collet member 41 is one end side (Z1 direction side) It is pushed towards. The switching mechanism 80 compresses the disc spring 43 to push the collet member 41 toward the one end by a predetermined amount by applying a pressing force larger than the biasing force of the disc spring 43. The compression force in the radial direction weakens as much as the collet member 41 is pushed out from the tapered chuck hole, so the gripping force of the shank 1 a (2 a) of the tool 1 or the contact sensor 2 weakens. As a result, by the operation of the actuator 81, the holding of the tool 1 or the contact sensor 2 can be released (released).

  The tool 1 and the contact sensor 2 are held in the magazine 121 of the tool changer 120 with the shank portion 1a (2a) directed upward (in the Z1 direction). At the time of tool change, the machine tool 200 moves the spindle device 100 above the holding hole at the tool change position under the control of the control unit 130 and advances the push rod 82 to the shank portion 1a (2a). Insert inside of Then, the machine tool 200 causes the collet member 41 to grasp the tool 1 or the shank portion 1 a (2 a) of the contact sensor 2 by retracting the push rod 82. Thereby, the tool 1 or the contact sensor 2 is held by the tool holder 40. When returning the tool 1 or the contact sensor 2 to the tool changer 120, the machine tool 200 advances the push rod 82 to place the tool 1 or the contact sensor 2 in the original holding hole at the tool change position. The holding by the holding unit 40 is released.

  The tool 1 has a blade 1b for processing the work 3 formed at one end (Z1 direction) and a shank 1a at the other end (Z2). The contact sensor 2 has a touch probe 2 b at one end, and a shank 2 a is provided at the other end of the contact sensor 2. The contact sensor 2 detects the contact of the touch probe 2b with the object to be measured. The contact sensor 2 incorporates, for example, a strain gauge, and detects contact based on strain due to stress caused by contact between the touch probe 2b and an object to be measured. The contact sensor 2 incorporates a wireless communication unit, and outputs a detection signal to a not-shown receiving unit disposed at a predetermined position in the machine tool 200. Based on the output of the contact sensor 2, it is possible to precisely measure the contact position between the touch probe 2b and the object to be measured.

(Processing condition and measurement condition)
Next, a machining state when the tool 1 is mounted on the spindle device 100 and machining is performed, and a measurement state in which the contact sensor 2 is mounted on the spindle device 100 and the workpiece 3 is measured will be described.

  As described above, in the first embodiment, when the tool 1 is mounted, the non-contact bearing 20 is in the processing state P1 (see FIG. 4) that rotatably supports the spindle 10 in a non-contact state. At the same time, it is configured to be switchable to a measurement state P2 (see FIG. 5) that suppresses the movement of the spindle 10 by supporting the spindle 10 in a contact state.

<Processing status>
First, in the processing state P1, as shown in FIG. 4, with the fluid circuit 70, the compressed air from the air pressure source 60 comprises the one axial bearing surface 21a of the axial bearing portion 21 and the other axial bearing surface 21b. Supplied to both. Thereby, the main shaft 10 is axially supported in a non-contact state with respect to the axial bearing portion 21. Further, in the processing state P1, the compressed air from the air pressure source 60 is supplied to each radial bearing surface 22a of the two radial bearing portions 22. Thereby, the main shaft 10 is radially supported in a non-contact state with respect to the radial bearing portion 22. As a result, the main shaft 10 has the central axis in a state in which the movement in the axial direction (Z direction) and the radial direction (XY direction) is restrained in a noncontact manner by the air pressure supplied to the clearance CL with the noncontact bearing 20. It is rotatably supported around.

  In this state, the spindle 10 is rotationally driven by the drive unit 30, and the tool 1 mounted on the spindle 10 is rotated at high speed. Then, the spindle device 100 and the workpiece 3 are relatively moved by the moving mechanism 110, and cutting is performed by bringing the tool 1 into contact with the workpiece 3.

<Measurement status>
On the other hand, as shown in FIG. 5, in the non-contact bearing 20, in the measurement state P2, the axial bearing surface (the other axial bearing surface 21b) of the axial bearing portion 21 and the axial opposing surface 11a of the main shaft 10 are in the axial direction It is configured to contact the.

  That is, the supply pressure to the non-contact bearing 20 is adjusted such that the main shaft 10 and the non-contact bearing 20 come into contact with each other. In the measurement state P2, the fluid circuit 70 weakens or cuts off the supply pressure of one of the one end side (Z1 direction side) and the other end side (Z2 direction side) of the axial bearing portion 21 than the other one. By doing this, the axial bearing surface and the axial facing surface 11a are configured to be in contact with each other.

  More specifically, in the first embodiment, the fluid circuit 70 includes a switching valve 72 that switches between supply (on) and shutoff (off) of air pressure to either one of the axial bearings 21. That is, in the measurement state P2, the supply of air pressure to either one of the axial bearing portions 21 is cut off by the switching valve 72, so that the main shaft 10 moves to the cut off side, and the axial bearing surface and the axial opposing surface 11a And contact.

  In the fluid circuit 70, a flow passage 73 communicating with the restriction hole of the one axial bearing surface 21a and a flow passage 74 communicating with the restriction hole of the other axial bearing surface 21b are separately provided. The switching valve 72 is disposed on the flow passage 74 communicating with the throttle hole of the other axial bearing surface 21b. Therefore, the supply and interruption of the compressed air to the other axial bearing surface 21b can be switched by the switching valve 72 while the supply of the compressed air is continued to the one axial bearing surface 21a. By interrupting the supply of compressed air to the other axial bearing surface 21b, only the portion of the clearance CL between the one axial bearing surface 21a and the other becomes high pressure, and the main shaft 10 moves to the other axial bearing surface 21b side .

  With such a configuration, in the first embodiment shown in FIG. 5, in the non-contact bearing 20, one axial bearing surface 21a is separated from the main shaft 10 and the other axial bearing surface 21b is the main shaft 10 in the measurement state P2. It is comprised so that the axial opposing surface 11a may be contacted. The main shaft 10 is moved to the other axial end side (Z2 direction) by the size (about 8 μm to about 20 μm) of the gap CL between the other axial bearing surface 21b and the axial facing surface 11a. As a result, the other axial bearing surface 21b and the axially facing surface 11a come into surface contact.

  In the measurement state P2, the axial opposing surface 11a of the main shaft 10 contacts the other axial bearing surface 21b, so the axial direction (Z direction) position of the main shaft 10 is the other axial bearing surface 21b and the axial opposing surface 11a. It is accurately positioned by the contact position of. Further, an external force to the other axial end side (Z2 direction) of the main spindle 10 is supported by the axial bearing portion 21 and movement of the main spindle 10 is restricted so that the main spindle 10 can not move further to the other end side.

  Here, the induction motor is different from a synchronous motor in which permanent magnets are provided on a rotor, and only a conductor is provided, so that the rotor 32 (spindle 10) is in a state of free rotation when the motor is not driven. On the other hand, as described above, since the bearing surface of the non-contact bearing 20 and the opposing surface of the main shaft 10 are smoothed by lapping, respectively, the other axial bearing surface 21b and the axial opposing surface are axially opposed The surface 11a is in close contact with the surface 11a. Therefore, in the measurement state P2, the rotation of the spindle 10 is stopped. As described above, the non-contact bearing 20 is configured to stop the rotation of the main shaft 10 by the contact with the main shaft 10 in the measurement state P2. Similarly, in the measurement state P2, movement of the main shaft 10 in the radial direction is suppressed by the close contact between the other axial bearing surface 21b and the axial facing surface 11a.

  In this state, the spindle device 100 and the work 3 are moved relative to each other by the moving mechanism 110, and the contact sensor 2 is brought into contact with the object to be measured such as the workpiece 3 to measure the dimensions of the object to be measured and the coordinate system of the moving mechanism 110. An accurate measurement of the contact position at

  As the measurement by the contact sensor 2, for example, measurement of the outer shape and position of the work 3 (see FIG. 7) and measurement of the shape of the work surface are performed. For example, the external shape of the rectangular parallelepiped work 3 is measured by the contact in the horizontal direction (radial direction of the main shaft 10) with the four side surfaces in the horizontal direction and the contact in the vertical direction (axial direction of the main shaft 10) with the upper surface. For example, the shape of the processing surface formed on the upper surface of the work 3 is brought into contact with the plurality of measurement points in the surface of the processing surface in the vertical direction (axial direction of the main spindle 10) The distribution is measured by approximating the distribution of three-dimensional positions of points and determining the shape of the surface to be processed.

  Therefore, particularly when the contact sensor 2 is brought into contact in the axial direction (Z direction) from the upper side of the object to be measured, toward the other end side (Z2 direction) in the axial direction due to the contact between the contact sensor 2 and the object A directed contact reaction force FR (see FIG. 5) acts on the main shaft 10. Due to the structure of the contact sensor 2, the pressing force against the object to be measured is about 0.1 N to 1 N in the horizontal direction, but is about 1 N to about 7 N in the axial direction. In the first embodiment, by bringing the other axial bearing surface 21b into contact with the axial facing surface 11a in the measurement state P2, the contact reaction force FR in the axial direction is supported, and displacement of the main shaft 10 is prevented. In the measurement in the horizontal direction, since the pressing force is small, the positional deviation in the radial direction is sufficiently prevented by the close contact between the other axial bearing surface 21b and the axial facing surface 11a.

  After switching to the measurement state P2, when returning to the processing state P1, as shown in FIG. 4, the other axial bearing is switched by switching the switching valve 72 so as to supply compressed air to the other axial bearing surface 21b. The contact between the surface 21b and the axial facing surface 11a can be released to switch to the processing state P1.

  The switching between the processing state P1 and the measurement state P2 is controlled by the control unit 130 according to whether the mounted object mounted on the spindle 10 is the tool 1 or the contact sensor 2. That is, in the first embodiment, the spindle device 100 includes the determination unit 133 that determines that the contact sensor 2 is attached to the tool holding unit 40 from the tool replacement device 120. The control unit 130 is configured to perform control to switch the non-contact bearing 20 to the measurement state P2 when the contact sensor 2 is attached to the tool holding unit 40.

  When the control unit 130 performs control to execute a series of machining operations according to a program 132 that defines machining operations by the machine tool 200, the discrimination unit 133 is attached with the tool 1 or with the contact sensor 2 attached. Determine if it is. When the determination unit 133 determines that the contact sensor 2 is attached, the control unit 130 controls the switching valve 72 of the fluid circuit 70 to shut off the compressed air to the other axial bearing surface 21b. When the determination unit 133 determines that the tool 1 is mounted, the control unit 130 controls the switching valve 72 of the fluid circuit 70 to supply compressed air to the other axial bearing surface 21b.

  In the first embodiment, the determination unit 133 is configured as one of functional blocks by the control unit 130 executing the control program, and is realized by software. A processor separate from the control unit 130 may be provided, and the determination unit 133 may be configured by hardware.

<Measurement operation control>
Next, measurement operation control will be described using the contact sensor 2 with reference to FIG. Here, an example in which the position and shape of the workpiece 3 are measured when the workpiece 3 is machined by the machine tool 200 will be described.

  In step S1, the control unit 130 mounts the contact sensor 2 on the tool holding unit 40 according to the program 132.

  In step S <b> 2, the determination unit 133 determines whether the contact sensor 2 is attached to the tool holding unit 40 of the spindle 10. If the contact sensor 2 is not attached, the measurement operation is not started.

  When the contact sensor 2 is mounted, the control unit 130 proceeds to step S3 and switches the non-contact bearing 20 to the measurement state P2. That is, the switching valve 72 is switched to shut off the supply of compressed air to the throttle hole of the other axial bearing surface 21b. As a result, the non-contact bearing 20 and the main shaft 10 come into contact with each other, and the movement of the main shaft 10 is suppressed.

  Next, in steps S <b> 4 and S <b> 5, the control unit 130 performs zero point adjustment (calibration) by measuring the reference gauge 4 using the contact sensor 2.

  As shown in FIG. 1, the reference gauge 4 is disposed, for example, on a table 140 on which the work 3 is installed. In FIG. 1, the reference gauge 4 is shown at a position aligned with the work 3 in the X direction for convenience of illustration, but the reference gauge 4 may be arranged at a position aligned with the work 3 in the Y direction, for example .

  The reference gauge 4 shown in FIG. 7A is a jig manufactured in advance with a high dimensional accuracy by using a ceramic or the like, and has, for example, an annular shape. The control unit 130 controls the moving mechanism 110 to bring the touch probe 2b of the contact sensor 2 into contact with a plurality of locations on the inner circumferential surface of the reference gauge 4 in the measurement state P2, and the reference position in the horizontal plane (in the XY plane) Get coordinates. Further, the control unit 130 brings the touch probe 2b of the contact sensor 2 into contact with the upper surface of the reference gauge 4, and acquires reference position coordinates in the Z direction.

  In step S5, the control unit 130 sets the horizontal direction (XY direction) and the vertical direction (Z direction) zero point based on the acquired reference position coordinates of the reference gauge 4. This zero point becomes the reference position in the position and shape measurement of the workpiece 3.

  In step S6, the control unit 130 measures the position and the shape of the work 3 using the contact sensor 2. The control unit 130 controls the moving mechanism 110 in the measurement state P2 to bring the touch probe 2b of the contact sensor 2 into contact with the respective outer side surfaces (four side surfaces) of the workpiece 3 as shown in FIG. 7B. , Measure the horizontal position of the work 3 on each side. Further, the control unit 130 brings the touch probe 2 b of the contact sensor 2 into contact with the upper surface of the workpiece 3 and measures the height position (Z direction position) of the upper surface of the workpiece 3. In addition, the control unit 130 brings the touch probe 2b of the contact sensor 2 into contact with a plurality of measurement points set on the work surface of the workpiece 3, and measures the shape of the work surface. Thereby, the position and the shape of the workpiece 3 are precisely measured with reference to the zero point set by the reference gauge 4.

  After the measurement is completed, in step S7, the control unit 130 determines whether to perform correction processing. For example, in FIG. 7B, when it is confirmed by the measurement result that the workpiece 3 after processing is formed into a desired shape, correction processing is unnecessary, and the control unit 130 ends the measurement processing. . If the workpiece 3 is not formed in the desired shape, the control unit 130 advances the process to step S8.

  In step S8, the control unit 130 causes the tool changer 120 to mount the tool 1 on the tool holding unit 40 instead of the contact sensor 2. In step S9, the determination unit 133 determines whether or not the tool 1 is attached to the tool holding unit 40 of the spindle 10. If the tool 1 is not attached, the machining operation is not started.

  When the tool 1 is mounted, the control unit 130 switches the non-contact bearing 20 from the measurement state P2 to the processing state P1 in step S10. That is, the switching valve 72 is switched to supply compressed air to the throttle hole of the other axial bearing surface 21b. As a result, the non-contact bearing 20 and the main shaft 10 are separated, and the main shaft 10 is rotatably supported in a non-contact state.

  Thereafter, the control unit 130 executes machining operation control in accordance with the control program. That is, the control unit 130 causes the drive unit 30 to rotate the spindle 10 at a high speed, and causes the workpiece 3 to be processed based on the position information and the shape information obtained by the measurement.

  The measurement of the workpiece 3 can be performed at a predetermined timing during processing. The timing at which the measurement of the workpiece 3 is to be performed is determined by the program 132 that defines the processing operation. Therefore, when the contact sensor 2 is mounted on the spindle 10 (step S1) to measure the workpiece 3 during processing, the workpiece 3 is measured by carrying out the steps S2 to S6. When the position and shape of the unmachined workpiece 3 are measured before machining the workpiece 3, steps S1 to S6 are performed to measure the position and shape of the workpiece 3, and steps S8 to S10 are performed to measure the tool , And processing of the work 3 is started based on the measurement result.

(Effect of the first embodiment)
In the first embodiment, the following effects can be obtained.

  In the first embodiment, as described above, the non-contact bearing 20 is configured to be switchable to the measurement state P2 in which the movement of the main shaft 10 is suppressed by supporting the main shaft 10 in the contact state when the contact sensor 2 is attached. Therefore, when measuring the work 3 by mounting the contact sensor 2 on the tool holding unit 40, the non-contact bearing 20 is switched to the measurement state P2 and the non-contact bearing 20 supports the spindle 10 in a contact state. Can. Therefore, when the contact reaction force FR of the contact sensor 2 acts on the main shaft 10, positional deviation of the main shaft 10 due to the contact reaction force FR can be suppressed as compared with the case where the main shaft 10 is held in a non-contact state. .

  Specifically, for example, in the spindle device 100 that performs high-speed rotation with a spindle rotational speed of about 60000 rpm, usually, the rigidity of the static pressure air bearing is about 10 N / μm to about 20 N / μm in the axial direction (axial direction) Ru. On the other hand, when the touch probe 2b is pressed in the axial direction with respect to the object to be measured, the pressing force is about 1 N to about 7 N as described above. When the rigidity is 10 N / μm and the pressing force is 7 N, the main shaft 10 is displaced by 0.7 μm, which makes it difficult to perform accurate measurement with the accuracy required for the mold. On the other hand, according to the configuration of the first embodiment, since the main shaft 10 is mechanically brought into contact with the non-contact bearing 20 in the acting direction of the contact reaction force FR, the positional deviation of the main shaft 10 is effectively made. It can be suppressed. As a result, by performing measurement in a state in which the noncontact bearing 20 is switched to the measurement state P2, in the spindle device 100 adopting the noncontact bearing 20, the contact sensor 2 is mounted on the spindle 10 to measure the work 3 Even in this case, the measurement accuracy can be improved.

  In the first embodiment, as described above, in the measurement state P2, the axial bearing surface (the other axial bearing surface 21b) of the axial bearing portion 21 and the axially facing surface 11a of the main shaft 10 contact in the axial direction As described above, since the non-contact bearing 20 is configured, the axial bearing surface (the other axial bearing surface 21b) and the axially facing surface 11a of the main shaft 10 can be brought into surface contact in the axial direction. As a result, due to the close contact between the surfaces, it is possible to effectively suppress the positional deviation of the main shaft 10 against both the contact reaction force FR in the axial direction from the contact sensor 2 and the contact reaction force in the radial direction. Further, since the axial position of the main shaft 10 is positioned at the contact position with the axial bearing surface of the non-contact bearing 20, the positional accuracy in the axial direction of the main shaft 10 can be improved. As a result, the workpiece 3 can be measured with higher accuracy.

  In the first embodiment, as described above, in the measurement state P2, the one axial bearing surface 21a is separated from the main shaft 10, and the other axial bearing surface 21b is in contact with the axial opposing surface 11a of the main shaft 10. The noncontact bearing 20 is configured. As a result, the other axial bearing surface 21b on the other end side (Z2 direction side) contacts the axial opposing surface 11a of the main shaft 10, so the contact reaction force FR in the axial direction from the contact sensor 2 (see FIG. 5) Also in the case of acting in the direction of pushing in 10 (direction Z2), the movement of the main shaft 10 can be reliably prevented. And the axial direction position of the main axis | shaft 10 can be positioned in a contact point with the other side axial bearing surface 21b. As a result, it is possible to realize both the prevention of the positional deviation due to the contact reaction force FR and the improvement of the positional accuracy in the axial direction of the spindle 10 in the measurement state P2.

  Further, in the first embodiment, as described above, by blocking the supply pressure of one of the one side and the other side of the axial bearing portion 21 (the other side), the axial bearing surface is blocked. (The other side axial bearing surface 21b) and the axial opposing surface 11a are configured to be in contact with each other. Thereby, the axial bearing surface and the axial opposing surface 11a can be easily brought into contact with each other only by adjusting (shutting off) the supply pressure to the hydrostatic fluid bearing. Further, since it is only necessary to use the fluid circuit 70 for supporting the main shaft 10 in a noncontact manner by the hydrostatic fluid bearing, the device configuration may be complicated even when the axial bearing surface and the axial opposing surface 11a are in contact with each other. Absent. Note that instead of blocking the supply pressure to the other side, the supply pressure to the other side may simply be set lower than the supply pressure to one side. If the pressure supplied to the other side is sufficiently smaller than the pressure supplied to one side, the axial bearing surface and the axial facing surface 11a can be brought into contact with each other by the pressure difference. Therefore, if the axial bearing surface and the axial facing surface 11a can be brought into contact with each other, it is not necessary to completely shut off the supply pressure to the other side.

  In the first embodiment, as described above, the fluid circuit 70 is provided with the switching valve 72 that switches between supply and shutoff of the air pressure to either one of the axial bearing portions 21. Thus, with a simple configuration in which only the switching valve 72 is provided, it is possible to easily switch to the measurement state P2 in which the axial bearing surface and the axial facing surface 11a are in contact with each other.

  In the first embodiment, as described above, the determination unit 133 for determining that the contact sensor 2 is attached to the tool holding unit 40 from the tool replacement device 120 and the contact sensor 2 attached to the tool holding unit 40 And a control unit 130 for performing control to switch the non-contact bearing 20 to the measurement state P2. As a result, it is possible to switch to the measurement state P2 when it is determined that the contact sensor 2 is attached to the tool holding unit 40 regardless of measurement before starting processing with the tool 1 or measurement during processing. As a result, it is not necessary for the user to switch to the measurement state P2, and the non-contact bearing 20 can be reliably switched to the measurement state P2 at the time of measurement by the contact sensor 2.

  In the first embodiment, as described above, the tool holder 40 is provided with the collet member 41 capable of directly holding the straight shank tool 1 and the contact sensor 2. Thus, unlike the case where the collet equipped tool 1 (contact sensor 2) is attached or detached, the tool 1 can be miniaturized while reducing the number of parts since it is not necessary to provide a collet chuck for each tool 1 (contact sensor 2) . Therefore, even when the contact sensor 2 is provided in the tool 1 replacement device, the device configuration does not increase in size.

  In the first embodiment, as described above, the drive unit 30 is configured of an induction motor, and the non-contact bearing 20 is configured to stop the rotation of the main shaft 10 by contact with the main shaft 10 in the measurement state P2. Do. As described above, when the induction motor is adopted, the spindle 10 slips if the spindle 10 is not driven. Therefore, when the contact sensor 2 is mounted on the tool holding portion 40, the tip of the contact sensor 2 will swing if the central axis of the main shaft 10 and the central axis of the contact sensor 2 do not coincide exactly. And the contact position with the reference gauge 4 become a factor which reduces measurement accuracy. Therefore, with the above configuration, measurement of the work 3 by the contact sensor 2 can be performed in a state in which the rotation of the spindle 10 is reliably stopped in the measurement state P2, so that special motor control can be performed in the configuration employing an induction motor. The measurement accuracy can be easily improved without

  Further, in the first embodiment, by configuring the machine tool 200 including the spindle device 100 configured as described above, in the machine tool 200 including the spindle device 100 adopting the non-contact bearing 20, the contact sensor 2 is used as the spindle Even in the case of measuring the workpiece 3 by attaching it to 10, the measurement accuracy can be improved.

Second Embodiment
Next, a spindle device 101 according to a second embodiment will be described with reference to FIGS. 8 and 9. In the second embodiment, unlike the first embodiment in which the measurement state P2 is switched to the measurement state P2 by interrupting the pressure supply to the other axial bearing surface 21b of the axial bearing portion 21, the main shaft 10 is biased in the axial direction. The configuration in which the urging unit 210 is provided will be described. In the second embodiment, the configuration other than the spindle device 101 is the same as that of the first embodiment, and thus the description thereof is omitted. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

  As shown in FIG. 8, in the spindle device 101 of the second embodiment, the spindle 10 and the non-contact bearing 20 are biased in the measurement direction P2 (see FIG. 9) by urging the spindle 10 in the axial direction (Z direction). And a biasing unit 210 for bringing the two into contact with each other.

  The biasing unit 210 applies an external force to the main shaft 10 and presses the non-contact bearing 20. Thereby, in the measurement state P2 (see FIG. 9), the main shaft 10 and the non-contact bearing 20 come into contact with each other. Even if the contact reaction force FR of the touch probe 2b acts on the main shaft 10 by the contact between the main shaft 10 and the non-contact bearing 20, the movement of the main shaft 10 is suppressed.

  The biasing unit 210 is not particularly limited as long as it can apply an external force to the spindle 10. In the example of FIG. 8, the biasing unit 210 is disposed on the other end side (Z2 direction side) in the axial direction with respect to the drive unit 30 and configured to bias the main shaft 10 by air pressure. That is, compressed air is supplied to the biasing unit 210 via the fluid circuit 70. The biasing portion 210 faces the balance ring 33 provided at the other axial end of the rotor 32, and has an annular supply surface 211 in which the push rod 82 is inserted. The biasing unit 210 is configured to discharge compressed air to the balance ring 33 from a throttle hole (not shown) provided on the supply surface 211.

  As shown in FIG. 9, the fluid circuit 70 can switch between pressure supply and shutoff to the urging unit 210 by the switching valve 220. As a result, in the on (supply) state of the switching valve 220, the balance ring 33, the rotor 32 and the main shaft 10 connected to them are axially moved to one end side (Z1 direction) by the air pressure supplied from the biasing unit 210. It is energized towards. Thereby, when the switching valve 220 is switched to the on state, the non-contact bearing 20 is configured to be switched to the measurement state P2 in which the movement of the main shaft 10 is suppressed by supporting the main shaft 10 in the contact state.

  When the switching valve 220 is in the off (cut off) state, the supply of compressed air is cut off to release the bias, and the main shaft 10 is rotatably supported by the noncontact bearing 20 in a noncontact manner. Thereby, when the switching valve 220 is switched to the off state, the non-contact bearing 20 is configured to be switched to the processing state P1 that rotatably supports the main spindle 10 in the non-contact state, as shown in FIG. .

  Thus, in the example of FIG. 9, the biasing portion 210 is configured to bring the one side axial bearing surface 21a into contact with the axial opposing surface 11a by biasing the main shaft 10 to one end side (Z1 direction). It is done.

  Therefore, in the case of the second embodiment, in the measurement state P2, on the other end side (Z2 direction side) that is the acting direction of the contact reaction force FR in the axial direction with respect to the flange portion 11 of the main shaft 10, the other side axial A gap is generated between the bearing surface 21b. Therefore, when the contact reaction force FR is larger than the biasing force FF of the biasing unit 210, the main shaft 10 may be displaced to the other end side.

  In that case, the pressure on the other end side of the axial bearing portion 21 is increased along with the decrease of the clearance CL between the other axial bearing surface 21b and the axial opposing surface 11a, so that the self weight of the main shaft 10, the biasing force FF and the other end side The displacement of the main shaft 10 is considered to be stopped at a position where the resultant force with the pressure FP and the contact reaction force FR are balanced. In such a case, the main shaft 10 is positioned in the axial direction at the contact position between the one axial bearing surface 21a and the axial opposing surface 11a, and displacement occurs by a predetermined contact reaction force FR. If the contact reaction force FR acts, the amount of displacement also becomes the same.

  Therefore, when the pressing force by the touch probe 2b is equal between the time of measurement of the reference gauge 4 (see FIG. 7A) and the time of measurement of the work 3 (see FIG. 7B), the contact reaction force FR is also equal. The displacement amounts of the main shaft 10 are also equal. That is, at the time of measurement of the reference gauge 4, the zero point adjustment is performed in a state in which the main shaft 10 is displaced in the axial direction by a predetermined amount by the contact reaction force FR. Since measurement is performed in a state of displacement by a fixed amount, as a result, measurement of the workpiece 3 is possible without being affected by the displacement of the main shaft 10 in the axial direction.

  Therefore, in the second embodiment, the control unit 130 causes the movement mechanism 110 (see FIG. 1) to perform measurement by the contact sensor 2 with the same pressing force when measuring the reference gauge 4 and when measuring the workpiece 3. Control).

  In the second embodiment, in the measurement state P2, the control unit 130 weakens or shuts off the supply pressure to the throttle hole of the one axial bearing surface 21a in the axial bearing portion 21. As a result, the first axial bearing surface 21a and the axially facing surface 11a can be brought into close contact with each other to generate an adhesion force between the two, so that the movement of the main shaft 10 due to the contact reaction force FR can be effectively suppressed.

  In addition, preferably, the biasing unit 210 is configured to bias with a biasing force FF that is larger than an axial pressing force on the workpiece 3 when the workpiece 3 is measured by the contact sensor 2. Thereby, even if the contact reaction force FR of the touch probe 2b acts on the spindle 10, the movement of the spindle 10 can be reliably suppressed.

  The remaining structure of the second embodiment is similar to that of the aforementioned first embodiment.

(Effect of the second embodiment)
In the second embodiment, the following effects can be obtained.

  In the second embodiment, as in the first embodiment, when the contact sensor 2 is mounted, the non-contact bearing 20 is switched to the measurement state P2 in which the movement of the main shaft 10 is suppressed by supporting the main shaft 10 in the contact state. In the case where the contact sensor 2 is mounted on the tool holding portion 40 and measurement of the work 3 is performed by configuring the non-contact bearing 20 to the measurement state P2, the non-contact bearing 20 contacts the main shaft 10 Support. Therefore, when the contact reaction force FR of the contact sensor 2 acts on the main shaft 10, positional deviation of the main shaft 10 due to the contact reaction force FR can be suppressed as compared with the case where the main shaft 10 is held in a non-contact state. .

  In the second embodiment, as described above, in the measurement state P2, the biasing portion 210 that brings the main shaft 10 into contact with the non-contact bearing 20 by biasing the main shaft 10 in the axial direction is provided. As a result, the biasing unit 210 can easily switch to the measurement state P2. Further, in the case of providing a dedicated biasing unit 210 for bringing the main shaft 10 and the non-contact bearing 20 into contact with each other, the biasing force FF is set in accordance with the magnitude of the contact reaction force FR from the contact sensor 2. The positional deviation of the main spindle 10 can be sufficiently suppressed.

  The other effects of the second embodiment are the same as those of the first embodiment.

(Modification)
It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is indicated not by the description of the embodiments described above but by the claims, and further includes all modifications (modifications) within the meaning and scope equivalent to the claims.

  For example, in the first and second embodiments, an example is shown in which the tool holding portion 40 includes the collet member 41 capable of directly holding the tool 1 and the straight shank (shank portion 1a (2a)) of the contact sensor 2. The present invention is not limited to this. In the present invention, the tool holder 40 may not have the collet member 41. For example, in the spindle device, a configuration is known in which the collet member is provided not on the tool holder but on the side of the tool.

  In FIG. 10, the tool holding portion 40 has a holding hole into which the tool holding collet 310 to which the tool 1 is fixedly attached is inserted, and the rotary outer cylinder 320 is screwed to the main shaft 10 and tightened. A tool holding collet 310 is configured to be held.

  In FIG. 11, the tool holding portion 40 has a holding hole into which the tool holding collet 330 to which the tool 1 is fixedly attached is inserted, and the tool holding collet 330 is moved by advancing and retracting the drawbar 340 provided inside the spindle 10. Are configured to switch between holding and releasing the holding. The tool holding collet 330 has a tapered shank portion 331. When the tool holding collet 330 is inserted into the inside of the tool holding portion 40, the axial center position and the axial center direction are restricted by the abutment of the tapered surface. The drawbar 340 is provided instead of the push rod 82 shown in FIG. As shown in FIG. 11A, when the draw bar 340 is retracted, the lock lot 341 provided on the draw bar 340 presses the clamp claw 350 radially outward, and the clamp claw 350 is engaged with the shank portion 331 on the outer peripheral side. The tool 1 is gripped (clamped). As shown in FIG. 11B, when the draw bar 340 is advanced, the pressing of the clamp claw 350 by the lock lot 341 is released, and the engagement between the shank portion 331 and the clamp claw 350 is released (released). .

  In the present invention, the tool holder 40 having the configuration of FIG. 10 or FIG. 11 may be provided. However, in the configuration in which the tool holding portion 40 has the collet member 41 capable of directly holding the straight shank (shank portion 1a (2a)) of the tool 1 and the contact sensor 2, one for each tool 1 or contact sensor 2 Since the tool 1 and the contact sensor 2 are directly gripped by the collet member 41 attached to the main shaft 10 in a state of being accurately positioned, there is no need for providing a tool holding collet, and the axial center position and axial direction It is preferable at the point which can suppress a shift | offset | difference and it can fix with high precision.

  In the first and second embodiments, an example (example in which the main shaft 10 is brought into contact with the axial bearing portion) with respect to the non-contact bearing 20 in the axial direction (axial direction) has been shown. It is not limited to. In the present invention, the main shaft 10 may be in contact with the non-contact bearing 20 in the radial direction (radial direction). That is, in the radial bearing portion 22, a plurality of throttle holes are provided at equal angular intervals over the entire circumference, and the main shaft 10 does not contact in the radial direction due to the balance of static pressure by compressed air discharged from the respective throttle holes. Be supported. Therefore, the radial opposing surface 12 a of the main shaft 10 can be brought into contact with the radial bearing surface 22 a of the radial bearing portion 22 by blocking the pressure supply to any one or more of the plurality of throttle holes of the radial bearing portion 22. it can. In this case, the movement of the main shaft 10 can be suppressed by the increase of the frictional force at the contact point between the radial opposing surface 12a and the radial bearing surface 22a. The main shaft 10 may be in contact with both the axial bearing portion 21 and the radial bearing portion 22 in combination with the configuration shown in the first or second embodiment.

  In the first embodiment, an example is shown in which the axial opposing surface 11 a of the main shaft 10 is brought into contact with the other axial bearing surface 21 b by blocking the pressure supply to the throttle hole of the other axial bearing surface 21 b. However, the present invention is not limited to this. As shown in FIG. 12, the axial opposing surface 11a of the main shaft 10 may be in contact with the one axial bearing surface 21a by blocking the pressure supply to the throttle hole of the one axial bearing surface 21a.

  Further, in the second embodiment, an example is shown in which the one axial bearing surface 21a and the axial opposing surface 11a are brought into contact by urging the main shaft 10 to the one end side (Z1 direction) by the urging unit 210. The present invention is not limited to this. In the second embodiment, conversely, the urging portion 210 urges the main shaft 10 to the other end side (Z2 direction), whereby the axial opposite of the main shaft 10 to the other side axial bearing surface 21b is achieved. The surface 11a may be in contact. In this case, the main shaft 10 and the non-contact bearing 20 are in the same contact state (see FIG. 5) as in the first embodiment.

  Moreover, although the example which is comprised so that the urging | biasing part 210 urges the main axis | shaft 10 non-contactedly by pneumatic pressure was shown in the said 2nd Embodiment, this invention is not limited to this. The biasing unit 210 may be configured to bias the main shaft 10 in direct contact with the main shaft 10 by, for example, a pneumatic or hydraulic piston, an electric solenoid, or the like.

  Further, in the first and second embodiments, an example is shown in which the supply pressure of one of the one side and the other side of the axial bearing portion 21 is weakened or blocked compared to the other one in the measurement state P2. However, the present invention is not limited to this. In the present invention, for example, a negative pressure source is provided separately from the positive pressure source in the pneumatic pressure source 60, and a negative pressure is supplied to either one side or the other side of the axial bearing portion 21, A positive pressure may be supplied to one side. Also by this, the main shaft 10 can be brought into contact with the non-contact bearing 20.

  In the first and second embodiments, although the example of the portal machining center is shown, the machine tool of the present invention is a vertical machining center not having a portal structure, or a horizontal machining center in which the main spindle 10 is provided in the horizontal direction. It may be

DESCRIPTION OF SYMBOLS 1 tool 2 contact sensor 3 work 10 main axis 11a axial opposite surface 20 non-contact bearing 21 axial bearing portion 21a one side axial bearing surface (axial bearing surface)
21b Other axial bearing surface (axial bearing surface)
Reference Signs List 22 radial bearing unit 30 drive unit 40 tool holding unit 41 collet member 70 fluid circuit 72 switching valve 100, 101 spindle device 110 moving mechanism 120 tool changer 130 control unit 133 determination unit 200 machine tool 210 urging unit P1 processing state P2 measurement State

Claims (10)

With the spindle
A non-contact bearing rotatably supporting the main shaft around a central axis in a non-contact manner;
A drive unit that rotationally drives the spindle;
A tool holding unit provided at one end of the spindle and detachably holding a contact sensor that measures a workpiece or a tool that performs machining on the workpiece;
The non-contact bearing is configured to be switchable to a measurement state in which movement of the main spindle is suppressed by supporting the main spindle in a contact state when the contact sensor is mounted. The noncontact bearing is
And an axial bearing portion axially supporting the main shaft from both axial sides, and a radial bearing portion radially supporting the main shaft,
The spindle device according to claim 1, wherein in the measurement state, an axial bearing surface of the axial bearing portion and an axially facing surface of the spindle are in axial contact with each other. The axial bearing portion includes a first axial bearing surface supporting the main shaft from one end, and a second axial bearing surface supporting the main shaft from the other end opposite to the first end.
The non-contact bearing is configured such that, in the measurement state, the one axial bearing surface is separated from the main shaft, and the other axial bearing surface is in contact with an axial opposing surface of the main shaft. Spindle device described in. The non-contact bearing is a hydrostatic fluid bearing,
The fluid circuit further includes a fluid circuit that controls pressure supply to the hydrostatic fluid bearing,
The fluid circuit is configured such that the axial bearing surface and the axial facing surface are separated by weakening or blocking the supply pressure of one of the one end side and the other end side of the axial bearing portion compared to the other one. The spindle device according to claim 2, wherein the spindle device is configured to be in contact. The hydrostatic fluid bearing is a hydrostatic air bearing,
5. The main shaft device according to claim 4, wherein the fluid circuit includes a switching valve that switches between supply and shutoff of air pressure to either one of the axial bearing portions.   The spindle device according to any one of claims 1 to 3, further comprising: a biasing unit that brings the spindle and the non-contact bearing into contact by biasing the spindle in an axial direction in the measurement state. . A determination unit configured to determine that the contact sensor has been attached to the tool holding unit from a tool changer;
The spindle device according to any one of claims 1 to 6, further comprising: a control unit that performs control to switch the non-contact bearing to the measurement state when the contact sensor is attached to the tool holding unit. .   The spindle device according to any one of claims 1 to 7, wherein the tool holding portion has a collet member capable of directly holding the straight shank tool and the contact sensor. The drive unit includes an induction motor
The spindle device according to any one of claims 1 to 8, wherein the non-contact bearing is configured to stop the rotation of the spindle by contact with the spindle in the measurement state. The spindle device according to any one of claims 1 to 9,
A moving mechanism for relatively moving the spindle device and the workpiece;
A tool changer which detachably holds the tool and the contact sensor with respect to the spindle of the spindle device.

Images