JP2004261934A - Machine tool control method and machine tool - Google Patents

Abstract

An object of the present invention is to stabilize thermal displacement of a spindle without performing a warm-up operation longer than necessary, and to improve machining efficiency and machining accuracy of a machine tool.
A blade edge position of a tool T mounted on a spindle 15 is detected during a warm-up operation of a spindle 15, and a change in the detected blade edge position of the tool T falls within a preset allowable range. Then, the warm-up operation of the main shaft 15 is ended.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a machine tool control method and a machine tool capable of performing an appropriate warm-up operation of a spindle without wasting time.
[0002]
[Prior art]
2. Description of the Related Art In a spindle device of a machine tool, it is known that a spindle motor for rotating the spindle or a bearing portion of the spindle generates heat by rotation of the spindle, and the heat causes thermal displacement of the spindle. This thermal displacement is particularly remarkable when the temperature of the spindle changes greatly, such as when the spindle is started or when the rotation is started.
[0003]
Such thermal displacement causes a change in the position of the cutting edge of the tool held on the main shaft, and thus adversely affects machining accuracy.
[0004]
Therefore, before starting machining at the time of starting or after changing tools, a warm-up operation in which the spindle is rotated for a time determined based on experience is performed. Alternatively, a method of detecting the position of the tool edge and starting machining is generally employed. Further, the lubricating fluid temperature control device for cooling the spindle is controlled so that the temperature of the spindle when the tool length or the position of the tool edge is detected is substantially equal to the temperature of the spindle at the start of machining by the tool. Alternatively, a method of controlling a machine tool in which the influence of the thermal displacement of the spindle is reduced by making the thermal displacement of the spindle at the time of detection of the tool edge position and at the start of machining substantially equal to each other has been adopted (for example, Patent Document 1). 1).
[0005]
[Patent Document 1]
JP-A-8-267342
[Problems to be solved by the invention]
During the warm-up operation as described above or during the temperature adjustment to make the temperature of the spindle substantially equal between the detection of the tool length or the position of the tool edge and the start of the machining, machining cannot be performed, while tool change and tool change are not performed. It is necessary to stop the rotation of the spindle to detect the length or measure the shape of the workpiece.Each time, the warm-up operation and temperature adjustment must be performed. It was a factor to lower it.
[0007]
As a method for solving this, as described in JP-A-11-11021 and JP-A-11-99448, a cooling liquid used for cooling the spindle based on processing conditions for the next processing. There is a precision machining method that controls the circulation and temperature thereof, stabilizes the thermal displacement of the spindle in a shorter time, and measures the tool length or starts machining at a preset timing.
[0008]
However, the above method only predicts the timing at which the thermal displacement of the spindle will be stable, and does not confirm whether the thermal displacement of the spindle is actually stable. However, it was difficult to sufficiently remove the influence of the steel on the processing accuracy. On the other hand, in order to ensure that the thermal displacement of the spindle is stabilized, the timing for starting the processing must be set late, and there is a tendency that a useless time not directly contributing to the processing becomes long.
[0009]
Therefore, an object of the present invention is to solve the above-mentioned problems in the prior art, to stabilize the thermal displacement of the spindle, and to improve machining efficiency and machining accuracy of a machine tool without performing a warm-up operation longer than necessary. It is an object of the present invention to provide a machine tool control method and a machine tool that can perform the control.
[0010]
[Means for Solving the Problems]
In view of the above-mentioned object, the present invention measures and calculates the cutting edge position of a tool mounted on a spindle while rotating a spindle based on machining conditions, and starts machining after the cutting edge position of the tool is stabilized. ing.
[0011]
That is, the present invention is a method for controlling a machine tool that processes a workpiece by relatively moving a tool and a workpiece, and rotates a spindle on which the tool is mounted under predetermined rotation conditions to perform a warm-up operation of the spindle. Starting the step, measuring the position of the cutting edge of the tool mounted on the spindle during the warm-up operation of the spindle, and the amount or rate of change in the position of the cutting edge of the tool measured during the warm-up operation of the spindle. Ending the warm-up operation of the spindle when the temperature falls within a preset range.
[0012]
Further, the present invention provides a machine tool for processing the workpiece by relatively moving a tool and a workpiece, wherein a spindle warm-up operation for rotating the spindle mounted with the tool under predetermined rotation conditions to perform a warm-up operation of the spindle. Control means, tool edge position measurement calculating means for measuring, calculating and storing the edge position of the tool mounted on the spindle at predetermined time intervals, and the edge position of the tool determined during the warm-up operation of the spindle And a determining means for determining whether to terminate the warm-up operation of the spindle based on a change amount or a change rate of the main shaft.
[0013]
During the warm-up operation of the spindle, the position of the cutting edge of the tool is detected, and by confirming that the change in the position of the tool edge is within a predetermined allowable range, the thermal displacement of the spindle during the warm-up operation is actually reduced. It is stable and it can be determined that the warm-up operation is no longer necessary. Therefore, the machining can be performed after the thermal displacement of the spindle is reliably stabilized, so that it is possible to reduce a change in the position of the tool edge due to the thermal displacement of the spindle during the machining. In addition, since the tool edge position is detected during the warm-up operation, it is not necessary to perform useless warm-up operation, and the warm-up operation time can be reduced.
[0014]
If a non-contact type measuring means is used for detecting the position of the tool edge, the position of the tool edge can be detected without stopping the rotation of the main shaft while the main shaft is being rotated. Therefore, by stopping the spindle, the temperature of the spindle decreases, and the thermal displacement of the spindle at the time of detection can be prevented from fluctuating from the thermal displacement of the rotating spindle. Thermal displacement can be detected.
[0015]
Furthermore, if a non-contact sensor, preferably an optical measuring means having a band-like measuring area, is used, it is possible to detect a change in the position of the tool edge without moving the position of the main shaft.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0017]
First, an overall configuration of an NC machine tool 11 according to the present invention will be described with reference to FIG. The machine tool main body of the NC machine tool 11 includes a spindle 15 rotatably supported by a spindle head 13 and a table 17 on which a work (not shown) is mounted and fixed. based on, X-axis feed motor _M X, Y axis feed motor _M Y, the Z-axis feed motor _{M Z,} X-axis and a spindle head 13 and the spindle 15 and the table 17, the three orthogonal axial direction of the Y-axis and Z-axis It is configured to be able to move relatively.
[0018]
In the NC machine tool 11 of FIG. 1, X-axis feed motor _M X, by moving the spindle head 13 by the Y-axis feed motor _{M Y} and Z-axis feed motor _{M Z} X-axis direction, the Y-axis direction and the Z-axis direction , although by relatively moving the main spindle 15 and the table 17 supported on the spindle head 13 in three orthogonal directions, to move the table 17 in the X-axis direction by the X axis feed motor M _X, Y axis feed motor M _Y and spindle head 13 by the Z-axis feed motor M _Z such as to move in the Y-axis direction and the Z-axis direction, it is also possible to adopt other configurations. Here, the X axis and the Y axis indicate two orthogonal axis directions in a plane perpendicular to the rotation axis of the main shaft 15, and the Z axis indicates an axis direction parallel to the rotation axis of the main shaft 15.
[0019]
Then, the tool T mounted on the tip of the spindle 15 is cut into the workpiece while rotating, and the tool T and the workpiece are relatively moved in the X-axis, Y-axis, and Z-axis directions by relatively moving the spindle 15 and the table 17. Then, the work is processed into a desired shape.
[0020]
NC device 19 stores a variety of programs such as a machining program, analyzes a program stored, generates sequential movement command according to a program, X-axis feed motor M _X in accordance with the movement _command, Y axis feed motor M _Y, drives the Z-axis feed motor _{M Z.}
[0021]
The machine body of the NC machine tool 11 is provided with position reading means 21 for reading the coordinate values of the X-axis, Y-axis, and Z-axis feed axes at an arbitrary moment. The relative position of the spindle head 13 with respect to the table 17 is sequentially fed back to the NC device 19. In the embodiment of FIG. 1, a digital scale is used as the position reading means 21, but an encoder attached to the X-axis feed motor M _X , the Y-axis feed motor M _Y , or the Z-axis feed motor M _Z may be used as appropriate. It is also possible to use the device described above.
[0022]
Further, the NC machine tool 11 includes a tool edge position detecting device 23 provided at a position on the table 17 which does not hinder processing, and a control device 25 for controlling the warm-up operation via the NC device 19.
[0023]
As shown in FIG. 2, the control device 25 includes a spindle warm-up operation control unit 29, a tool edge position measurement calculation unit 31, and a spindle warm-up operation determination unit 39. The tool edge position measurement calculation means 31 includes a measurement control means 33, a tool edge position calculation means 35, a storage means 37, and a measurement time interval determination means 41.
[0024]
The spindle warm-up operation control means 29 receives a rotation command of the spindle 15 from the NC device 19, and returns warm-up operation ON / OFF commands. The measurement control means 33 of the tool edge position measurement calculation means 31 issues a measurement command to the NC device 19 at each measurement timing, and sends the tool T to the tool edge position calculation means 35 based on the detection value of the tool edge position detection device 23. A command is issued to calculate the position of the cutting edge. The storage means 37 stores the tool edge position calculated and obtained. The measurement time interval determination means 41 calculates a tendency of the displacement of the spindle with respect to the elapsed time of the warm-up operation from the stored tool edge position, and determines an appropriate measurement time interval of the tool edge position during the warm-up operation from the calculation result. , To the measurement control means 33. When the tool edge position data obtained by the tool edge position measurement calculating means 31 is transmitted to the spindle warm-up operation determining means 39 in this way, the spindle warm-up operation determining means 39 calculates the amount of change or the rate of change of the blade edge position and calculates the value. Is within the allowable range, and sends a signal to the spindle warm-up operation control means 29 as to whether or not to end the warm-up operation.
[0025]
In the NC machine tool 11, when measuring the position of the cutting edge of the tool T, such as during a warm-up operation, the spindle 15 and the table 17 are relatively moved, and the tool T mounted on the spindle 15 by the tool edge position detecting device 23. Of the cutting edge position is detected. Specifically, since the blade edge detection position of the tool edge position detection device 23 is a predetermined position with respect to the table 17, if the positions of the spindle head 13 and the table 17 are detected, the spindle head 13 and Using the fact that the distance from the detection position of the tool edge position detection device 23 is known, the edge position of the tool T with respect to the spindle head 13 is calculated.
[0026]
The controller 25 detects the cutting edge position of the tool T by the tool cutting edge position detecting device 23 while rotating the main shaft 15 during the warm-up operation, and the fluctuation of the cutting edge position of the tool T, that is, the thermal displacement of the main shaft 15 is reduced. After confirming the stability, it is determined that the warm-up operation has been completed. Therefore, the NC machine tool 11 of the present invention requires only a minimum time for the warm-up operation, while reliably stabilizing the thermal displacement of the spindle 15 after the end of the warm-up operation, and The possibility that the position of the cutting edge fluctuates due to the thermal displacement of the main shaft 15 can be minimized.
[0027]
The method of detecting the position of the cutting edge of the tool T can detect the position of the cutting edge by stopping the main shaft 15 and quickly bringing the tool cutting edge into contact with the reference position of the contact sensor. However, if the spindle 15 is stopped when detecting the cutting edge position of the tool T, the temperature of the spindle 15 decreases, and the thermal displacement of the spindle 15 at the time of detection changes from the thermal displacement of the rotating spindle 15. Therefore, it is preferable that the detection of the cutting edge position of the tool T is performed without stopping the rotation of the main shaft 15. In this case, a non-contact type tool edge position detecting device 23 is used. For this reason, in the embodiment shown in FIG. 1, an optical tool edge position detecting device 23 is used. However, as the non-contact type tool edge position detecting device 23, for example, a non-contact type sensor such as a capacitance type or an eddy current type may be used.
[0028]
Further, the tool edge position detecting device 23 may be an optical sensor using one light beam, but as shown in FIG. 1, a strip-shaped detection region extending along a plane including the rotation axis of the tool T. Are preferred. Due to this feature, even when the spindle 15 supported by the spindle head 13 arranged at a predetermined position causes thermal displacement and the position of the cutting edge of the tool T held by the spindle 15 changes, the cutting edge of the tool T There is an effect that a change in position can be detected.
[0029]
Next, a control method of the warm-up operation in the NC machine tool shown in FIG. 1 will be described with reference to FIG.
[0030]
In the NC machine tool 11, when the spindle 15 is shifted from the stopped state to the rotating state, for example, when the NC machine tool 11 is started or when the tool T is changed, the spindle 15 is moved before starting the machining. Perform warm-up operation. For this purpose, the control device 25 drives the X-axis feed motor M _X , the Y-axis feed motor M _Y , and the Z-axis feed motor M _Z via the NC device 19 so that the spindle head 13 and the spindle supported by the spindle head 13 are driven. The tool 15 and the table 17 are moved to a predetermined relative position, and the cutting edge of the tool T mounted on the main shaft 15 is arranged in the detection area of the tool cutting edge position detecting device 23. Then, in a state where the spindle head 13 and the table 17 are arranged at this relative position, the spindle 15 is rotated at a rotation speed of a machining condition set in machining using the tool, which is commanded by the NC device 19, and The warm-up operation control means 29 starts the warm-up operation of the main shaft 15 (step S1).
[0031]
Next, the measurement control means 33 detects the cutting edge position of the tool T mounted on the spindle 15 by the tool cutting edge position detecting device 23 during the warm-up operation, and the tool cutting edge position calculating means 35 detects the cutting edge position based on the detected value. The position of the cutting edge of the tool T is calculated (step S2). The calculated cutting edge position of the tool T is stored in the storage means 37 (step S3). Further, after a predetermined time interval, the position of the cutting edge of the tool T is calculated again in the same manner as in step S2 (step S4), and the calculated cutting edge position of the tool T is stored in the storage means 37 (step S4). S5). Step S5 can be omitted.
[0032]
Next, the spindle warm-up operation determining means 39 calculates the change amount of the cutting edge position of the tool T from the currently measured cutting edge position of the tool T and the cutting edge position of the tool T in the previous calculation stored in the storage means 37. It is determined (step S6), and the obtained change amount of the cutting edge position of the tool T is compared with a preset allowable value of the change amount (step S7).
[0033]
When the amount of change in the position of the cutting edge of the tool T is equal to or greater than the allowable value, that is, when the amount of change in the position of the cutting edge of the tool T exceeds the allowable range, it is determined that the thermal displacement of the spindle 15 is not stable, and 4, the calculation of the cutting edge position of the tool T is continued (NO in step S7). On the other hand, when the amount of change in the position of the cutting edge of the tool T is equal to or less than a preset allowable value, that is, when the amount of change in the position of the cutting edge of the tool T falls within a preset allowable range, the thermal displacement of the main shaft 15 is reduced. Judge as stable. When the thermal displacement of the spindle is stabilized, there is no longer any need for the warm-up operation, so the spindle warm-up operation judging means 39 judges that the warm-up operation may be ended, A command to end the machine operation is issued, and the NC device 19 starts machining (YES in step S7). A change rate may be used instead of the change amount of the tool edge position.
[0034]
As described above, since the position of the cutting edge of the tool T mounted on the main shaft 15 is detected during the warm-up operation, it can be confirmed that the thermal displacement of the main shaft 15 is actually stable, and the thermal displacement of the main shaft 15 is stable. Since it is possible to detect the moment when the operation is performed, it is possible to avoid performing unnecessary warm-up operation. If an appropriate measurement time interval determined by the measurement time interval determination means 41 is used, the warm-up operation time can be minimized.
[0035]
【The invention's effect】
As described above, according to the present invention, it is possible to confirm that the thermal displacement of the spindle has been stabilized by detecting the change in the position of the tool tip mounted on the spindle during the warm-up operation, so that the thermal displacement of the spindle during machining can be confirmed. The influence can be reduced, and the processing accuracy can be improved. In addition, since the moment when the thermal displacement of the spindle is stabilized can be detected, the time required for the warm-up operation can be minimized, and the processing efficiency can be improved.
[Brief description of the drawings]
FIG. 1 is a configuration diagram and a block diagram of a main part of a machine tool according to the present invention.
FIG. 2 is a block diagram showing an embodiment of the control device shown in FIG.
FIG. 3 is a flowchart showing a control method of a warm-up operation in the machine tool shown in FIG. 1;
[Explanation of symbols]
11 ... NC machine tool 15 ... Spindle 23 ... Tool edge position detection device 25 ... Control device 29 ... Spindle warm-up operation control means 31 ... Tool edge position measurement / calculation means 33 ... Measurement control means 35 ... Tool edge position calculation means 37 ... Storage Means 39: Spindle warm-up operation determining means T: Tool

Claims (8)

A method of controlling a machine tool that processes a workpiece by relatively moving a tool and a workpiece,
Starting the warm-up operation of the spindle by rotating the spindle equipped with the tool under predetermined rotation conditions,
Measuring the position of the cutting edge of the tool mounted on the spindle during the warm-up operation of the spindle,
Ending the warm-up operation of the spindle when the change amount or the change rate of the cutting edge position of the tool measured during the warm-up operation of the spindle is within a preset range;
A method for controlling a machine tool, comprising: Measuring the position of the cutting edge of the tool mounted on the main spindle during the warm-up operation of the main spindle, measuring the position of the cutting edge of the tool mounted on the main spindle at a predetermined time interval during the warm-up operation of the main spindle. 2. The method according to claim 1, further comprising the step of storing. The step of ending the warm-up operation of the spindle when the change amount or the change rate of the cutting edge position of the tool measured during the warm-up operation of the spindle falls within a preset range includes the warm-up operation of the spindle. 3. The machine tool according to claim 1, further comprising: calculating a change amount or a change rate of the tool edge position from a value measured and stored therein, and ending the warm-up operation of the spindle from the calculation result. 4. Control method. Calculating a change tendency of the displacement of the spindle with respect to the elapsed warm-up operation time from the stored tool edge position, and determining a measurement time interval of the tool edge position of the tool during the warm-up operation of the spindle from the calculation result. The method for controlling a machine tool according to claim 2. The machine tool control method according to claim 1, wherein the predetermined rotation condition of the spindle in the step of starting the warm-up operation of the spindle is a rotation speed used for machining or a predetermined rotation speed. In a machine tool that processes the work by relatively moving a tool and a work,
A spindle warm-up operation control means for rotating the spindle equipped with the tool under predetermined rotation conditions and performing a warm-up operation of the spindle;
Tool edge position measurement calculating means for measuring, calculating and storing the edge position of the tool mounted on the spindle at predetermined time intervals,
Determining means for determining whether to end the warm-up operation of the spindle, based on a change amount or a change rate of the cutting edge position of the tool determined during the warm-up operation of the spindle;
A machine tool comprising: The tool edge position measurement calculating means calculates the change tendency of the displacement of the spindle with respect to the elapsed time of the warm-up operation from the stored tool edge position, and measures the edge position of the tool during the warm-up operation of the spindle from the calculation result. 7. The machine tool according to claim 6, comprising means for determining a time interval. The tool edge position measurement calculating means is a measuring means for detecting the edge position by bringing the tool edge into contact with a detection unit of the sensor, or a light emitting unit that emits at least one light beam or a band-shaped light beam and the light beam The machine tool according to claim 6, wherein a light receiving unit that receives light is arranged to face the light receiving unit, and any one of a measuring unit that detects a position of the cutting edge based on a light receiving state when the tool cutting edge blocks the light beam is used.

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