Air Spindle Device

Abstract

To measure a displacement amount of a spindle during processing and execute the processing work with high accuracy using a measurement result.SOLUTION: An air spindle device 100 comprises: a housing 50; a spindle 10 which is provided in the housing 50; and a radial bearing 31 and a thrust bearing 32 which support the spindle 10 via the air. A displacement amount of the spindle 10 is obtained by an x direction displacement meter 41, a y direction displacement meter 42 and a z direction displacement meter 43. A control unit 130 drives a movement mechanism 110 in the direction of correcting the displacement amount on the basis of the displacement amount of the spindle 10.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an air spindle device including a housing and a spindle rotatably supported within the housing via air. [Background technology]

[0002] 2. Description of the Related Art Conventionally, an air spindle device is known that includes a housing and a spindle that is rotatably supported within the housing via air.

[0003] Due to its structure, it is difficult for an air spindle device to give rigidity to the spindle and rotate it at high speed. For this reason, the spindle may displace within the housing during machining, but no technology has been developed to measure the displacement of the spindle within the housing, and the displacement of the spindle during machining may prevent high-precision machining. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-104066 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure has been made in consideration of these points, and aims to provide an air spindle device that can measure the amount of spindle displacement during machining and can utilize this amount of spindle displacement to perform highly accurate machining operations. [Means for solving the problem]

[0006] The present disclosure relates to an air spindle device comprising: a housing; a spindle rotatably mounted within the housing and holding a tool; a radial bearing mounted in the housing and supporting the spindle in the radial direction via air; a thrust bearing mounted in the housing and supporting the spindle in the axial direction via air; an x-direction displacement meter, a y-direction displacement meter, and a z-direction displacement meter that determine the amount of displacement of the spindle in each of the x-direction, y-direction, and z-direction relative to the housing; a moving mechanism that drives the housing; and a control unit, wherein the control unit controls the moving mechanism in a direction that corrects the amount of displacement of the spindle in each of the x-direction, y-direction, and z-direction based on signals from the x-direction displacement meter, the y-direction displacement meter, and the z-direction displacement meter.

[0007] The present disclosure is an air spindle device in which the control unit determines the load applied to the tool based on signals from the x-direction displacement gauge, the y-direction displacement gauge, and the z-direction displacement gauge.

[0008] The present disclosure is an air spindle device in which the x-direction displacement gauge and the y-direction displacement gauge are embedded in the radial bearing provided in the housing and determine the distance between the outer peripheral surface of the spindle.

[0009] The present disclosure is an air spindle device in which the z-direction displacement meter is embedded in the thrust bearing provided in the housing and determines the distance between the thrust bearing and a flange provided on the spindle.

[0010] The present disclosure is an air spindle device, wherein the z-direction displacement meter determines the displacement of the upper end of the spindle. Effect of the Invention

[0011] As described above, according to the present disclosure, the amount of displacement of the air spindle can be measured during machining, and this amount of displacement can be used to perform machining with high precision. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram showing an air spindle device according to the present disclosure. [Diagram 2] Figure 2 is an overall configuration diagram of a machine tool equipped with an air spindle device. [Diagram 3] FIG. 3 is an enlarged view of FIG. 1 showing the x-direction displacement gauge and the y-direction displacement gauge. [Figure 4] FIG. 4 is an enlarged view of FIG. 1 showing the z-displacement sensor. [Figure 5A] FIG. 5A is a diagram showing a change in the amount of displacement in the x direction according to the present disclosure. [Figure 5B] FIG. 5B is an enlarged view of FIG. 5A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] First, the entire machine tool equipped with the air spindle device according to the present disclosure will be described.

[0014] As shown in Fig. 1 and Fig. 2, the air spindle device 100 is a device for rotating a tool 1 attached to one end of the spindle 10 by driving the spindle 10 to rotate around a central axis, thereby machining a workpiece 3 that is a workpiece. The air spindle device 100 is assembled to a machine tool 200, and moves relative to the workpiece 3 by a moving mechanism 110 provided in the machine tool 200. The machine tool 200 is a numerically controlled (NC) machine tool, and controls the relative motion (position and speed) between the tool 1 and the workpiece 3 by numerical information, and executes a series of operations related to machining by a program 132. Specifically, the machine tool 200 is a machining center equipped with the air spindle device 100 and a tool exchange device 120, and various types of machining such as drilling, boring, and milling can be performed by changing the tool 1 to the air spindle device 100.

[0015] In this embodiment, for example, a mold for an optical lens is considered as an example of the workpiece 3, and the mold is precisely machined by the machine tool 200. The air spindle device 100 and the machine tool 200 are capable of measuring the workpiece 3 with high accuracy, and are therefore particularly suitable for precision machining that requires high accuracy, such as the manufacture of molds.

[0016] 2 includes an air spindle device 100, a moving mechanism 110, and a tool exchange device 120. Furthermore, the machine tool 200 and the air spindle device 100 include a control unit 130 that controls each of these components.

[0017] The moving mechanism 110 is configured to move the air spindle device 100 and the workpiece 3 relatively. In this case, the moving mechanism 110 can move the air spindle device 100 and the workpiece 3 relatively in three orthogonal axial directions, at least the up-down direction and two directions perpendicular to each other in a horizontal plane. When the air spindle device 100 and the workpiece 3 are moved relatively, only one of the air spindle device 100 and the workpiece 3 may move, or both the air spindle device 100 and the workpiece 3 may move. In this embodiment, as shown in FIG. 2, the moving mechanism 110 holds the air spindle device 100 and moves the air spindle device 100 in the z direction, which is the up-down direction, and the x direction in a horizontal plane (the left-right direction in FIG. 2), and moves the workpiece 3 in the y direction (the front and back directions perpendicular to the paper surface in FIG. 2) perpendicular to the x direction in the horizontal plane.

[0018] A specific configuration of the moving mechanism 110 will be described below. As shown in FIG. 2, the machine tool 200 is a gate-type machining center. The machine tool 200 includes a table 140 on which the workpiece 3 is placed, and a bed 141 that supports the table 140 movably in the y direction. The machine tool 200 also includes a pair of columns 142 arranged on both sides of the bed 141 in the x direction, and a crossbar 143 that is hung across the upper ends of the pair of columns 142, and the crossbar 143 extends in the x direction so as to straddle the top of the table 140 and the bed 141. The crossbar 143 supports a saddle 144 movably in the x direction. The saddle 144 supports a head 145 that holds the air spindle device 100 movably in the z direction.

[0019] In this embodiment, the moving mechanism 110 includes a z-axis moving mechanism 111 that moves the head 145 in the z direction, an x-axis moving mechanism 112 that moves the saddle 144 in the x direction, and a y-axis moving mechanism 113 that moves the table 140 in the y direction. Each of the z-axis moving mechanism 111, the x-axis moving mechanism 112, and the y-axis moving mechanism 113 includes, for example, a servo motor 114 with a built-in position detector, and a linear motion mechanism (not shown) driven by the servo motor 114. The moving mechanism 110 may include more than three moving axes. For example, the moving mechanism 110 may include a rotation axis that rotates the head 145 around an axis in the y direction (tilting the tool 1 of the air spindle device 100 with respect to a horizontal plane) and a rotation axis that rotates the table 140 around the z axis (rotating the workpiece 3 in a horizontal plane).

[0020] The tool exchange device 120 has a function of removably holding a plurality of types of tools 1 and replacing the tool 1 attached to the spindle 10 of the air spindle device 100. The tool exchange device 120 also removably holds a contact sensor 2 in addition to the tool 1. That is, the tool exchange device 120 is configured to hold the tool 1 and the contact sensor 2 detachably with respect to the spindle 10 of the air spindle device 100.

[0021] As shown in Fig. 2, the control unit 130 is configured to perform overall operation control of the machine tool 200. The control unit 130 is configured with a processor such as a CPU. Specifically, the control unit 130 includes a storage unit 131 in which various programs 132 for controlling the machine tool 200, including a machining program for the workpiece 3, are stored. The processor executes the programs stored in the storage unit 131, whereby the processor operates as the control unit 130 of the machine tool 200. In this way, the control unit 130 performs operation control of the air spindle device 100, operation control of the moving mechanism 110, and operation control of the tool exchange device 120. The control unit 130 is provided, for example, in a control panel of the machine tool 200, and is connected to a display unit (not shown) and an input unit (not shown) of the control panel.

[0022] Next, an air spindle device 100 according to the present disclosure will be described. As shown in Fig. 1, the air spindle device 100 according to the present disclosure includes a housing 50, a spindle 10 rotatably provided within the housing 50, and a tool 1 held at the lower end of the spindle 10. In this case, the tool 1 is attached and held at the lower end of the spindle 10 via a tool holding portion 40.

[0023] Of these, the spindle 10 is supported in the radial direction via air by a radial bearing 31 provided in the housing 50. Similarly, the spindle 10 is supported in the axial direction via air by a thrust bearing 32 provided in the housing 50.

[0024] The thrust bearing 32 and the radial bearing 31 form the air bearing mechanism 20 .

[0025] 1, the spindle 10 has a shaft portion 11 of a predetermined length and a flange portion 12 provided midway along the shaft portion 11 and having a diameter larger than that of the shaft portion 11. The spindle 10 is disposed in a storage hole 50A in a housing 50.

[0026] 1, air bearing mechanism 20 has a bearing member 30 that is fixed within accommodation hole 50A of housing 50 and rotatably supports spindle 10 via an air gap, and this bearing member 30 consists of radial bearing 31 and thrust bearing 32 described above. Of these, radial bearing 31 has an inner diameter that provides a predetermined radial gap 33 between it and the outer circumferential surface of shaft portion 11, and has air ejection holes 34 for ejecting air into radial gap 33. Furthermore, thrust bearing 32 is formed integrally with radial bearing 31, has a predetermined thrust gap 35 between it and the end face of flange portion 12, and has air ejection holes 36 for ejecting air into thrust gap 35.

[0027] As described above, housing 50 is formed with storage hole 50A for storing spindle 10 in the central axial direction, and air supply port 23 for the air bearing is formed on the outside of housing 50. Moreover, air supply path 25 is formed inside housing 50, which communicates from air supply port 23 for the air bearing to air ejection holes 34 and 36 of radial bearing 31 and thrust bearing 32.

[0028] The air spindle device 100 also includes an air source 60 which supplies air to the radial bearing 31 and thrust bearing 32, and a fluid circuit 70 which is connected between the air source 60 and the air bearing air supply port 23 and controls the pressure supply of air to the air bearing air supply port 23. In this way, compressed air at a predetermined pressure is supplied from the air source 60 via the fluid circuit 70 to the radial bearing 31 and thrust bearing 32. The supplied air pressure may be, for example, about 0.3 MPa or more and about 0.7 MPa or less.

[0029] Next, the driving unit 80 that drives the spindle 10 will be described. The driving unit 80 drives the spindle 10 to rotate. The driving unit 80 is connected to the upper end of the spindle 10 and is configured to directly drive the spindle 10 to rotate around the central axis. The driving unit 80 is an electric motor capable of high-speed rotation of about 60,000 rpm, and is a built-in motor built into the housing 50. The motor can be a synchronous motor or an induction motor, and specifically, the driving unit 80 is configured by such an induction motor. The induction motor generates an induced current in the rotor 82 by a rotating magnetic field generated in the stator 81, and rotates the rotor 82 by the interaction between the magnetic field generated by the induced current and the rotating magnetic field of the stator 81. The rotor 82 is fixed to the spindle 10, while the stator 81 is fixed inside the housing 50 so as to surround the radial outside of the rotor 82.

[0030] As shown in FIGS. 1 to 4, an x-direction displacement meter 41 and a y-direction displacement meter 42 are provided at the lower portion of the housing 50 for determining the amount of displacement of the spindle 10 relative to the housing 50 in the x and y directions, respectively.

[0031] The x-direction displacement gauge 41 and the y-direction displacement gauge 42 are used to determine the displacement amounts of the spindle 10 in the x and y directions, and are disposed at positions spaced 90° apart in a plan view on the outer periphery of the spindle 10 in Figures 1 and 3. The x-direction displacement gauge 41 is disposed to extend horizontally within an opening 41A formed by penetrating the housing 50 and the radial bearing 31 in the horizontal direction, and the x-direction displacement gauge 41 is used to determine the horizontal distance between the outer periphery of the shaft portion 11 of the spindle 10.

[0032] The signal from the x-direction displacement gauge 41 is sent to the control unit 130 .

[0033] The y-direction displacement gauge 42 is disposed at a position spaced 90° from the x-direction displacement gauge 41 in a plan view. In this embodiment, an opening 42A is formed penetrating the housing 50 and the radial bearing 31 in the horizontal direction at a position spaced 90° from the opening 41A in a plan view. The y-direction displacement gauge 42 is provided to extend horizontally within this opening 42A, and the horizontal distance to the outer circumferential surface of the shaft portion 11 of the spindle 10 can be obtained by this y-direction displacement gauge 42. A signal from the y-direction displacement gauge 42 is sent to the control unit 130.

[0034] Further, in the housing 50, a portion above the flange portion 12 is provided with a z-direction displacement meter 43 for determining the amount of displacement of the spindle 10 relative to the housing 50 in the z direction.

[0035] In this embodiment, an opening 43A is provided above the flange portion 12 of the spindle 10, penetrating the housing 50 and the thrust bearing 32 in the vertical direction, and a z-direction displacement meter 43 is disposed to extend vertically within this opening 43A. The z-direction displacement meter 43 can determine the vertical distance between the flange portion 12 of the spindle 10. A signal from the z-direction displacement meter 43 is sent to the control unit 130.

[0036] In addition, any displacement gauges may be used as the x-direction displacement gauge 41, y-direction displacement gauge 42, and z-direction displacement gauge 43, which are used to determine the displacement of the spindle 10 in the x-direction, y-direction, and z-direction relative to the housing 50, as long as they can measure the distance between the spindle 10.

[0037] For example, the x-direction displacement gauge 41, the y-direction displacement gauge 42, or the z-direction displacement gauge 43 may be a capacitance type sensor, an eddy current type sensor, or a laser light irradiation type sensor.

[0038] In addition, in this embodiment, an example has been shown in which the z-direction displacement meter 43 is provided inside the housing 50 and used to determine the distance between the flange portion 12 of the spindle 10, but this is not limited to the above. The z-direction displacement meter 43 may be provided on the upper part of the housing 50 and the vertical distance between the upper end of the spindle 10 may be determined using this z-direction displacement meter 43.

[0039] Next, the operation of this embodiment having the above configuration will be described.

[0040] 1, compressed air (also called compressed air) from an air source 60 is sent to the housing 50 side via a fluid circuit 70, and the compressed air is supplied from an air bearing air supply port 23 of the housing 50 to both the radial bearing 31 and the thrust bearing 32. As a result, the spindle 10 is supported in a non-contact manner in the radial direction by the radial bearing 31 via air, and is supported in a non-contact manner in the axial direction by the thrust bearing 32 via air. As a result, the spindle 10 is supported rotatably around the central axis by the air pressure supplied to the radial bearing 31 and the thrust bearing 32, with movement in the axial direction (Z direction) and radial directions (XY directions) restricted in a non-contact manner.

[0041] In this state, the spindle 10 is rotationally driven by the drive unit 80, and the tool 1 attached to the spindle 10 rotates at high speed. Then, the air spindle device 100 and the workpiece 3 are moved relative to each other by the movement mechanism 110, and the tool 1 is brought into contact with the workpiece 3, whereby cutting is performed on the workpiece 3.

[0042] During this time, the x-direction displacement meter 41 measures the horizontal distance to the outer circumferential surface of the shaft portion 11 of the spindle 10, the y-direction displacement meter 42 measures the horizontal distance to the outer circumferential surface of the shaft portion 11 of the spindle 10, and the z-direction displacement meter 43 measures the vertical distance to the flange portion 12 of the spindle 10. The signals from the x-direction displacement meter 41, the y-direction displacement meter 42 and the z-direction displacement meter 43 are sent to the control unit 130.

[0043] The measurement results from the x-direction displacement meter 41, the y-direction displacement meter 42, and the z-direction displacement meter 43 sent to the control unit 130 correspond to the x-direction displacement amount, the y-direction displacement amount, and the z-direction displacement amount of the spindle 10 relative to the housing 50, respectively, and these x-direction displacement amount, y-direction displacement amount, and z-direction displacement amount are stored in the memory unit 131 of the control unit 130.

[0044] Next, the determination unit 133 of the control unit 130 determines the load applied from the workpiece 3 to the tool 1 based on the x-direction displacement amount, the y-direction displacement amount, and the z-direction displacement amount in the memory unit 131 .

[0045] Specific results of the amount of displacement in the x direction obtained by the x direction displacement meter 41 are shown in FIG. 5A and FIG. 5B.

[0046] 5A is a diagram showing a change in the amount of displacement in the x direction, and FIG. 5B is an enlarged view of FIG. 5A.

[0047] As shown in Figures 5A and 5B, when a machining operation is performed on a workpiece 3 using tool 1, immediately after tool 1 comes into contact with workpiece 3, the amount of displacement in the x direction rises sharply in response to the load applied to tool 1 from the workpiece 3, and this amount of displacement in the x direction remains a constant value.

[0048] Next, when the tool 1 separates from the workpiece 3 and ends contact, the amount of displacement in the x direction decreases.

[0049] In this case, it is known that the x-direction displacement amount is proportional to the x-direction load applied from the workpiece 3 to the tool 1. Therefore, the discrimination unit 133 of the control unit 130 can determine the x-direction load applied from the workpiece 3 to the tool 1 based on the x-direction displacement amount.

[0050] Similarly, the discrimination unit 133 of the control unit 130 can determine the load in the y direction applied to the tool 1 from the workpiece 3 based on the amount of y-direction displacement sent from the y-direction displacement meter 42 .

[0051] Similarly, the discrimination unit 133 of the control unit 130 can determine the load in the z direction applied to the tool 1 from the workpiece 3 based on the amount of z direction displacement sent from the z direction displacement meter 43 .

[0052] In this embodiment, the discrimination unit 133 of the control unit 130 further corrects the positional deviation of the tool 1 with respect to the workpiece 3 based on the amount of displacement in the x direction, the amount of displacement in the y direction, and the amount of displacement in the z direction.

[0053] That is, when the spindle 10 has an amount of displacement in the x direction, the y direction, and the z direction with respect to the housing 50, this means that the position of the tool 1 with respect to the workpiece 3 is misaligned.

[0054] In this embodiment, the discrimination unit 133 of the control unit 130 drives and controls the movement mechanism 110 based on the x-direction displacement amount, the y-direction displacement amount, and the z-direction displacement amount. In this case, the movement mechanism 110 moves the entire air spindle device 100 including the housing 50 slightly in the x-direction, the y-direction, and the z-direction.

[0055] Specifically, the x-axis moving mechanism 112 of the moving mechanism 110 moves the entire air spindle device 100, including the housing 50, slightly in a direction that corrects the x-direction displacement amount (in a direction that offsets the x-direction displacement amount), thereby correcting the x-direction positional deviation of the tool 1 relative to the workpiece 3.

[0056] For example, when the displacement amount of the spindle 10 relative to the housing 50 in the x direction is "+a", the entire air spindle device 100 including the housing 50 is moved slightly in the x direction by "-a". This makes it possible to correct the positional deviation of the tool 1 relative to the workpiece 3 in the x direction.

[0057] Similarly, the y-axis moving mechanism 113 of the moving mechanism 110 moves the entire air spindle device 100, including the housing 50, slightly in a direction that corrects the y-direction displacement amount (in a direction that offsets the y-direction displacement amount), thereby correcting the y-direction positional deviation of the tool 1 relative to the workpiece 3.

[0058] In addition, the z-axis moving mechanism 111 of the moving mechanism 110 moves the entire air spindle device 100, including the housing 50, slightly in a direction that corrects the z-direction displacement amount (in a direction that offsets the z-direction displacement amount), thereby correcting the z-direction positional deviation of the tool 1 relative to the workpiece 3.

[0059] As described above, according to this embodiment, the control unit 130 can determine the x-direction load applied from the workpiece 3 to the tool 1 based on the x-direction displacement amount sent from the x-direction displacement meter 41, can determine the y-direction load applied from the workpiece 3 to the tool 1 based on the y-direction displacement amount sent from the y-direction displacement meter 42, and can determine the z-direction load applied from the workpiece 3 to the tool 1 based on the z-direction displacement amount sent from the z-direction displacement meter 43.

[0060] Furthermore, the control unit 130 controls the movement mechanism 110 based on the x-direction displacement amount, the y-direction displacement amount, and the z-direction displacement amount, and the movement mechanism 110 moves the entire air spindle device 100 including the housing 50 slightly in the x-direction, the y-direction, and the z-direction. In this case, the movement mechanism 110 moves the entire air spindle device 100 including the housing 50 slightly in a direction that corrects (cancels) the x-direction displacement amount, the y-direction displacement amount, and the z-direction displacement amount. This makes it possible to correct the positional deviation in the x-direction, the y-direction, and the z-direction of the tool 1 relative to the workpiece 3. This makes it possible to perform high-precision machining of the workpiece 3 using the tool 1.

[0061] In addition to the x-direction displacement meter 41, the y-direction displacement meter 42, and the z-direction displacement meter 43 shown in the above embodiment, a y-direction rotational displacement meter for determining the rotational displacement of the spindle 10 about the y-direction axis relative to the housing 50, and a z-direction rotational displacement meter for determining the rotational displacement of the spindle about the z-direction axis relative to the housing 50 may be provided. In this case, the entire air spindle device 100 having the housing 50 can be moved slightly based on signals from the y-direction rotational displacement meter and the z-direction rotational displacement meter so as to eliminate the rotational displacement about the y-direction axis and the z-direction axis by the movement mechanism 110, thereby correcting the positional deviation in the rotational direction about the y-direction axis and the z-direction axis. [Explanation of symbols]

[0062] 1 tool 3 Work 10 Spindle 11 Shaft 12 Flange 20 Air bearing mechanism 23 Air supply port for air bearings 25 Air supply line 30 Bearing materials 31 Radial bearing 32 Thrust bearing 33 Radial clearance 34 Air outlet 35 Thrust clearance 36 Air outlet 40 Tool holding part 41 x-direction displacement gauge 41A opening 42 y-direction displacement gauge 42A opening 43 z-direction displacement gauge 43A aperture 50 Housing 50A Storage hole 60 Air Source 70 Fluid circuit 80 Drive unit 81 Stator 82 Rotor 110 Moving mechanism 111 z-axis movement mechanism 112 x-axis movement mechanism 113 y-axis movement mechanism 130 Control section

Claims

1. In the air spindle device, Housing and a spindle rotatably mounted within the housing and configured to hold a tool; a radial bearing provided in the housing and configured to radially support the spindle via air; a thrust bearing provided in the housing and configured to axially support the spindle via air; an x-direction displacement meter, a y-direction displacement meter, and a z-direction displacement meter for determining displacement amounts in the x-direction, y-direction, and z-direction of the spindle relative to the housing; A moving mechanism that drives the housing; A control unit. the moving mechanism includes an x-axis moving mechanism, a y-axis moving mechanism, and a z-axis moving mechanism; An air spindle device in which the control unit controls the x-axis movement mechanism, the y-axis movement mechanism, and the z-axis movement mechanism of the movement mechanism in directions that correct the displacement amounts of the spindle in each of the x-direction, y-direction, and z-direction based on signals from the x-direction displacement meter, the y-direction displacement meter, and the z-direction displacement meter.

2. 2. The air spindle device according to claim 1, wherein the control unit determines the load acting on the tool based on signals from the x-direction displacement gauge, the y-direction displacement gauge, and the z-direction displacement gauge.

3. 3. The air spindle device according to claim 1, wherein the x-direction displacement gauge and the y-direction displacement gauge are embedded in the radial bearing provided in the housing, and measure a distance between an outer peripheral surface of the spindle.

4. 4. The air spindle device according to claim 1, wherein the z-direction displacement meter is embedded in the thrust bearing provided in the housing, and determines a distance between the thrust bearing and a flange provided on the spindle.

5. 4. The air spindle device according to claim 1, wherein the z-direction displacement meter determines the displacement of an upper end of the spindle.

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