JP2018024063A - Spindle device of machine tool - Google Patents

Abstract

An object of the present invention is to effectively suppress vibration without changing machining conditions. A spindle device (1) includes a spindle (2) to which a tool is detachable, a spindle (2) rotatably supported in a housing via bearings (4, 4), a motor (3) for rotating the spindle (2), and a controller for controlling the motor (3). a vibration damping collar 15 provided in the spindle 2 and movable back and forth in the direction of the rotation axis of the spindle 2; machining conditions including the rotation speed of the spindle 2 and dimensions of the tool; and bearings. A calculation device 24 that analyzes the vibration mode of the main shaft 2 based on the bearing characteristics including the support stiffness and damping coefficient of 4, and moves the damping collar 15 to the initial position in the rotation axis direction based on the analysis result of the calculation device 24 moving means (disc spring 16, pressure chamber 17, pressure oil supply path 18, control valve 20, hydraulic unit 21, NC device 26). [Selection drawing] Fig. 1

Description

  The present invention relates to a spindle device of a machine tool that can suppress vibrations generated during machining.

  In a machine tool that performs processing while rotating a tool or a workpiece, so-called chatter vibration is generated during the processing, and problems such as deterioration of finishing accuracy of the processed surface, tool wear, and tool chipping occur. As a method for suppressing such chatter vibration, for example, in Patent Document 1, when occurrence of chatter vibration is detected based on vibration in a time domain detected by a vibration sensor or the like, it is optimal to use k value and phase information. An invention that calculates the rotational speed, specifies the type of chatter vibration from the phase information, and changes chatter vibration that is different from chatter vibration specified in the past, and recalculates the optimal rotational speed by changing the k value. It is disclosed. Further, in Patent Document 2, a mechanism for supplying oil from three or more locations in the circumferential direction to a gap between the housing and the main shaft is provided in the housing that supports the main shaft, and the radial vibration direction of the main shaft detected by the displacement sensor is provided. The invention which suppresses the vibration of the main shaft by changing the hydraulic pressure and the oil amount according to the above is disclosed.

Japanese Patent No. 4743646 JP 2011-235404 A

  In the invention of Patent Literature 1, since vibration suppression involves a change in processing conditions such as rotational speed, there is a risk that processing accuracy may be reduced and processing time may be extended. In the invention of Patent Document 2, since the direction of hydraulic pressure supply is constant and cannot be changed, effective damping may not be performed depending on the generated vibration.

  Therefore, an object of the present invention is to provide a spindle device for a machine tool that can effectively suppress vibration without changing machining conditions.

In order to achieve the above-mentioned object, the invention according to claim 1 is characterized in that a tool is detachable and is supported rotatably in a housing via a bearing, a motor for rotating the spindle, and the motor. A spindle device of a machine tool comprising a control device for controlling,
A vibration damping member provided in the main shaft and capable of moving back and forth in the direction of the rotation axis of the main shaft, a machining condition including a rotation speed of the main shaft and dimensions of the tool, a bearing including a support rigidity and a damping coefficient of the bearing. Vibration analyzing means for analyzing the vibration form of the main shaft based on characteristics, and moving means for moving the damping member to a predetermined position in the rotation axis direction based on the analysis result of the vibration analyzing means. It is characterized by.
According to a second aspect of the present invention, in the configuration of the first aspect, the apparatus further includes vibration detection means for detecting vibration generated in the main shaft during machining, and the vibration analysis means is the machining detected by the vibration detection means. The vibration means is analyzed, and the moving means moves the damping member to a position different from the predetermined position based on the analysis result of the vibration analyzing means.
According to a third aspect of the present invention, in the configuration of the first or second aspect, the damping member is accommodated in a hollow portion formed in the main shaft so as to be movable back and forth, and the moving means is disposed in the hollow portion. An urging means for urging the damping member to either one of the front and rear sides, a pressurizing chamber formed on the opposite side of the urging means across the damping member, and supplied with fluid; And a fluid pressure adjusting mechanism capable of adjusting a fluid pressure to the pressurizing chamber.

According to the present invention, the vibration form of the main shaft is analyzed based on the machining conditions and the bearing characteristics, and the vibration damping member is moved to a predetermined position based on the analysis result, so that the vibration damping is not changed without changing the machining conditions. The damping effect by the member can be exhibited and effective vibration suppression can be performed.
In particular, the vibration generated during machining is analyzed, and the vibration control member is moved to a position different from the predetermined position based on the analysis result, so that the natural frequency of the main shaft can be continuously varied during machining, and the vibration can be effectively performed. Can be suppressed.

It is explanatory drawing of the spindle apparatus of a machine tool. It is a flowchart of position control of a damping color.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an explanatory diagram showing an example of a spindle device provided in a machine tool such as a machining center. In this spindle device 1, reference numeral 2 denotes a spindle, which is rotatably supported by a motor 3 through bearings 4 and 4 in a housing (not shown). The main shaft 2 is hollow, and a draw bar 5 is urged to a retreat position by a pressing mechanism 6 using a disc spring 7, 7... Provided at the rear of the main shaft 2. It is provided in the state that was done. The draw bar 5 clamps the tool holder 9 at the front end of the main shaft 2 by clamping the chuck mechanism 8 provided at the front portion of the main shaft 2 in the retracted position, and the chuck mechanism 8 is moved forward by a hydraulic mechanism (not shown). Perform unclamping operation. Reference numeral 10 denotes a coolant supply path provided at the axis of the draw bar 5.

Further, a hollow portion 12 that is partitioned by a partition plate 11 located at the front end of the pressing mechanism 6 is formed on the front side of the pressing mechanism 6 in the main shaft 2, and a vibration damping mechanism 13 is formed in the hollow portion 12. Is provided. The vibration control mechanism 13 includes a fixed collar 14 through which the draw bar 5 passes and is fixed to the front end of the hollow portion 12, and a vibration control collar as a vibration control member that passes through the draw bar 5 behind and is movable in the axial direction. 15, a plurality of disc springs 16, 16... That are interposed between the fixed collar 14 and the damping collar 15 and bias the damping collar 15 backward, and the rear of the damping collar 15. And a pressurizing chamber 17 formed between the partition plate 11. A pressure oil supply path 18 whose front end communicates with the pressurizing chamber 17 is formed in the draw bar 5 outside the coolant supply path 10 over the range of the front and rear strokes of the draw bar 5.
The damping collar 15 is made of a cylindrical steel material, and ring-shaped grooves are formed on the inner and outer circumferences, and resin seal members 19 and 19 are incorporated in the grooves to form the pressurizing chamber 17. It is sealed.

  The pressure oil supply path 18 is connected to the hydraulic unit 21 via the control valve 20, and the pressure oil sent from the hydraulic unit 21 is supplied to the pressurizing chamber 17 via the pressure oil supply path 18. Therefore, the front / rear position of the damping collar 15 is determined at a position where the urging force of the disc springs 16, 16... Balances with the hydraulic pressure from the pressurizing chamber 17. The bending rigidity and damping characteristics of the main shaft 2 can be changed by moving the damping collar 15 back and forth in the axial direction by changing the hydraulic pressure from the pressurizing chamber 17.

Next, the control system of the spindle device 1 will be described.
Reference numeral 22 denotes a control device, which is provided with an input device 23, an arithmetic device 24, a storage device 25, and an NC device 26.
The input device 23 allows an operator to input machining conditions such as the rotational speed of the spindle 2 and tool dimensions, and allows a vibration detection signal from a vibration detection means such as a vibration sensor (not shown) provided in the housing to be input. Yes.
The arithmetic unit 24 as a vibration analyzing means determines the vibration mode of the main shaft 2 based on the machining conditions including the rotational speed and the tool size input from the input unit 23 and analysis data described later recorded in the storage unit 25. Based on the analyzed vibration form and the spring constant of the disc spring 16, the hydraulic pressure to the pressurizing chamber 17 for moving the damping collar 15 to the position where the damping effect is maximized is determined. Further, the vibration from the vibration sensor is analyzed to determine whether chatter vibration has occurred.

The storage device 25 stores in advance analysis data including the shape of the main shaft 2, bearing characteristics including the support rigidity and damping coefficient of the bearing 4, the spring constant of the disc spring 16, and the hydraulic pressure determined by the arithmetic device 24. Remember. A machining program is also stored.
The NC device 26 controls the motor 3 and the like according to the machining program stored in the storage device 25, and controls the control valve 20 so that the pressurizing chamber 17 becomes the hydraulic pressure stored in the storage device 25. Here, the pressure oil supply path 18, the control valve 20, the hydraulic unit 21, and the NC device 26 are the fluid pressure adjusting mechanism of the present invention, and the configuration including the disc spring 16 is the moving means of the damping collar 15. .

In the spindle device 1 configured as described above, the control device 22 analyzes the vibration form of the spindle 2 based on the analysis data described above, and determines the vibration suppression color from the analyzed vibration form and the spring constant of the disc spring 16. The position control which moves 15 and exhibits the damping effect is executed. Hereinafter, the position control of the damping collar 15 will be described based on the flowchart of FIG.
First, in S1, the rotational speed of the spindle 2 and the tool dimensions are input by the input device 23, and the machining conditions are set.
Next, in S <b> 2, the arithmetic device 24 analyzes the vibration form of the spindle 2 based on the machining conditions input from the input device 23 and the analysis data stored in the storage device 25 and stores it in the storage device 25. To do.

Next, in S3, the hydraulic pressure applied to the pressurizing chamber 17 for moving the damping collar 15 to the position where the damping effect is maximized is calculated from the analyzed vibration form and the spring constant of the disc spring 16. And stored in the storage device 25.
Then, in S4, the NC device 26 sends a command to the control valve 20 so as to obtain the hydraulic pressure stored in the storage device 25, and moves the damping collar 15 to the initial position. This initial position is the position of the antinode of the maximum amplitude of the analyzed vibration.

After moving the damping collar 15 to the initial position in this way, processing is started in S5.
When chatter vibration is detected in S6 during machining, the calculation device 24 specifies the chatter frequency by performing FFT analysis on the vibration of the spindle 2 and additional information obtained from the vibration detection means in S7. ), The fluctuation frequency f _{color of the} hydraulic pressure added to the damping collar 15 is determined by multiplying the specified chatter frequency f _chatter by an arbitrary coefficient α.
f _color = α · f _chatter (1)
Next, in S8, the NC device 26 having obtained the fluctuation frequency of the additional hydraulic pressure from the arithmetic unit 24 changes the hydraulic pressure to be applied by controlling the control valve 20 based on the fluctuation frequency, so that the damping collar 15 is moved from the initial position. Slide forward or backward.
Since the vibration form is changed by the movement of the damping collar 15, chatter vibrations generated at the initial position are suppressed.

  Thereafter, when it is confirmed in S9 that the machining has been completed, the position control is terminated. If the machining is not finished, the process returns to S6 to determine the detection of chatter vibration, and if it is detected, the vibration frequency of the additional hydraulic pressure is determined again in S7, the additional hydraulic pressure is changed in S8, and the damping collar 15 is moved forward or Slide to. If chatter vibration is not detected in S6, the end of machining is confirmed in S9, and if not finished here, the process returns to S6 to again determine the detection of chatter vibration. If the processing is finished, the position control is finished.

  Thus, according to the spindle device 1 of the machine tool of the above embodiment, the damping collar 15 provided in the spindle 2 and movable back and forth in the rotation axis direction of the spindle 2, the rotation speed of the spindle 2 and the dimensions of the tool. And a calculation device 24 that analyzes the vibration form of the spindle 2 based on the bearing characteristics including the support rigidity and damping coefficient of the bearing 4, and the damping collar 15 is rotated based on the analysis result of the calculation device 24. By including moving means (a disc spring 16, a pressurizing chamber 17, a pressure oil supply path 18, a control valve 20, a hydraulic unit 21, and an NC device 26) that move to a predetermined position (initial position) in the axial direction. Without changing the conditions, the damping effect by the damping collar 15 can be exhibited and effective vibration suppression can be performed.

  In particular, here, chatter vibration generated during machining is analyzed by the arithmetic unit 24, and the damping collar 15 is moved to a position different from the initial position based on the analysis result, so that the natural frequency of the main shaft 2 can be set during machining. Chatter vibration can be effectively suppressed by continuing to vary.

In addition, in the said form, although the disc spring 16 which is an urging | biasing means is arrange | positioned to the front side and the pressurization chamber 17 is arrange | positioned to the rear side, you may make it reverse. As the biasing means, a coil spring or the like can be used in addition to the disc spring. The fluid supplied to the pressurizing chamber is not limited to oil, and other fluids such as air and gas may be used. The fluid supply path to the pressurizing chamber is not limited to the draw bar, and is provided on the main shaft. Also good.
The damping member is not limited to the damping collar of the above-described form, and can be changed by using a metal other than steel or combining a plurality of metals. Also, a plurality of hollow portions are provided in a concentric circle around the draw bar so that the draw bar penetrates, and a damping member such as a sphere can be moved back and forth in the axial direction of the main shaft. It is also possible to provide a biasing means and a pressurizing chamber to control the position of the damping member.

  1 .... Spindle device 2 .... Spindle 3 .... Motor 4 .... Bearing 5 .... Drawbar 6, ... Pressing mechanism 7, 16, ... Belleville spring 12, ... Hollow part 13, ... Control Vibration mechanism, 14 ... Fixed collar, 15 ... Damping collar, 17 ... Pressure chamber, 18 ... Pressure oil supply path, 19 ... Seal member, 20 ... Control valve, 21 ... Hydraulic unit, 22 ..Control device, 23 ..Input device, 24 ..Calculation device, 25 ..Storage device, 26 ..NC device

Claims (3)

A spindle device for a machine tool, comprising: a spindle that is attachable and detachable and rotatably supported via a bearing in a housing; a motor that rotates the spindle; and a control device that controls the motor. ,
A damping member provided in the main shaft and movable back and forth in the direction of the rotation axis of the main shaft;
Vibration analysis means for analyzing the vibration form of the spindle based on machining conditions including the rotation speed of the spindle and the dimensions of the tool, and bearing characteristics including support rigidity and damping coefficient of the bearing;
A spindle device for a machine tool, comprising: moving means for moving the damping member to a predetermined position in the direction of the rotation axis based on an analysis result of the vibration analysis means.   The apparatus further comprises vibration detecting means for detecting vibration generated in the main shaft during processing, the vibration analyzing means analyzes vibration during processing detected by the vibration detecting means, and the moving means is the vibration analyzing means. The spindle device of the machine tool according to claim 1, wherein the vibration damping member is moved to a position different from the predetermined position based on the analysis result.   The vibration damping member is accommodated in a hollow portion formed in the main shaft so as to be movable back and forth, and the moving means is provided in the hollow portion and biases the vibration damping member forward or backward. An urging unit, a pressurizing chamber formed on the opposite side of the urging unit with the damping member interposed therebetween, and a fluid pressure adjusting mechanism capable of adjusting a fluid pressure to the pressurizing chamber. The spindle device for a machine tool according to claim 1, wherein the spindle device is included.

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