JP2000317772A - Control method for machine tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten cycle time by executing subsequent processes when the completion of the movement of a feed rod is confirmed, without confirming an arrival to a command rotating speed of a man spindle in a first positioning process where the rotation speed of the main spindle is commanded. SOLUTION: A main spindle to which a tool is mounted is started to rotate, a feed rod is driven to position the tool toward dividing direction in the two directions perpendicular with the cutting direction. After the completion of the movement of the feed rod is confirmed at the time of positioning (step 18), processes after a first positioning process are executed (step 19), in a given subsequent process, the arrival time of the speed of the main spindle is confirmed (step 20, 24 and 28) by means of a speed arrival information confirmation command (step 14, 15 and 16). When the arrival of speed for the main spindle is confirmed at this time, subsequent work processes are executed (step 17).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of controlling a machine tool for processing a workpiece by rotating a main spindle on which a tool is mounted according to an NC program and moving the spindle in a three-dimensional direction orthogonal to the spindle.

[0002]

2. Description of the Related Art Conventionally, there is a method of processing a workpiece by controlling a machine tool according to an NC program 50 shown in FIG.
The machine tool controlled by the NC program 50 is a general horizontal machining center that holds a tool in a horizontal direction. The left and right direction is the X direction, the up and down direction is the Y direction, and the front and rear directions are the cutting direction of the tool. Let the direction be the Z direction.

In this control method, a spindle with a tool mounted at the tip is set to a block N according to the NC program shown in FIG.
(X, Y, Z) = (100, 20)
(0,0) to the indexing position in the X and Y directions, and at the same time, start rotation at a rotation speed of 10000 min ^{- 1} and then have a slight gap with the workpiece specified by the block N020 (X, 0). Y, Z) = (100, 200,
50), it is rapidly moved in the Z direction to the machining start position, and then (X, Y, Z) = (1) commanded in block N030.
1000 mm / min to the position of (00, 200, 70)
The workpiece W is drilled by cutting at a speed of .times., And then (X, Y, Z) = (10)
(0, 200, 50).

Although it is possible to simultaneously position X, Y, and Z axes in N010 of the NC block 50, the shape of the processing surface of the workpiece is not always flat, so that the tool and the workpiece need not be flat. Positioning to the processing start position is performed in block 0 of the NC program 50 to prevent interference.
In general, the description is divided into two blocks, such as 10 and N020.

[0005]

Since the feed speed and the rotation speed of the tool specified by the NC program are determined in consideration of the material and machining accuracy of the workpiece and the tool, the rotation speed of the main spindle is controlled by the NC. Machining is performed under conditions different from those assumed to start machining before reaching the rotation speed commanded by the data block of the program, so that machining accuracy is degraded. In the worst case, if the machining is started before the rotation speed of the spindle reaches the command value, tool breakage may be caused. Therefore, conventionally, after confirming that the spindle has reached the commanded rotation speed, rapid feed to the machining start position is performed, and then machining is started.

In the conventional control method, in order to shorten the cycle time, in block N010 of the NC program 50, movement to the machining position and start of the spindle are commanded in one block, and positioning and start of the spindle are started simultaneously. However, in the conventional control method, the block N010
The next block N020 is not executed unless both the completion of the feed movement of the X and Y axes to the target position instructed by the command and the attainment of the speed of the main spindle to the rotation speed instructed by the block N010 are confirmed. . Therefore, even when the feed movement of the X and Y axes is completed earlier than the rotation of the spindle, it is necessary to wait until the rotation speed of the spindle reaches the command value.

In other words, in such a case, X, Y,
As can be seen from the diagram showing the relationship between each feed axis speed of Z and the rotation speed of the main shaft with respect to time, the feed movement in the X and Y directions commanded in block N010 also causes the main shaft to move to the commanded rotation speed in block N010. Even if the rotation is completed earlier than reaching the speed, the rotation speed of the spindle is the command value 1
Without waiting for the time t1 until reaching 0000 min ⁻¹ , it is impossible to proceed to the next block N012,
There is a problem that a useless waiting time is generated by t1 and the cycle time is extended.

[0008]

According to a first aspect of the present invention, there is provided a method for controlling a machine tool, comprising the steps of: starting the main spindle on which a tool is mounted; A first positioning step of positioning the feed shaft toward an indexing position aligned with the machining position of the workpiece in the cutting direction; A second positioning step of positioning the tool in the cutting direction toward the machining start position without confirming the arrival of the tool, and after the completion of the second positioning step has been confirmed, the rotation of the spindle to the commanded rotation speed is confirmed. After confirming that the speed has been reached,
And a processing step of processing and feeding the tool in the cutting direction.

Therefore, according to the first aspect of the present invention, in the first positioning step in which the rotation speed of the spindle is commanded, the completion of the movement of the feed shaft is confirmed without confirming that the spindle reaches the commanded rotation speed. Then, the second positioning step is executed, and when both the completion of the movement of the feed shaft and the reaching of the spindle speed are confirmed in the second positioning step, the machining step is executed.

According to a second aspect of the present invention, in the method for controlling a machine tool according to the first aspect, an instruction for confirming that the speed of the spindle has reached the speed is provided in an arbitrary step before the machining step. A confirmation instruction step, a reference step of referring to speed attainment information stored in a memory of the numerical controller by the confirmation instruction, and, if the speed arrival is confirmed within a predetermined time in this reference, the tool is cut into the notch. A processing step of processing and feeding in the direction, and an abnormal processing step of executing an abnormal processing when the arrival at the speed is not confirmed even after a predetermined time elapses in the reference, are further included.

Therefore, according to the second aspect of the present invention, the reference step of referring to the speed attainment information stored in the memory of the numerical control device is executed by the confirmation instruction step, and the speed attainment within a predetermined time is performed by this reference step. Is confirmed, the machining step is executed, and if the arrival at the speed is not confirmed even after the elapse of the predetermined time, the abnormal processing step is executed.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a side view of a machine tool controlled by the control method according to the present invention. In this figure, 1
Reference numeral 0 denotes a bed of the machine tool 9, and a column 11 is provided at a rear portion of the bed 10. The column 11 is located on the bed 10 in a left-right direction of the machine tool 9 (a direction perpendicular to the plane of FIG. 1). A pair of Xs extending and fixed in the direction
The shaft guide rail 12 is movably guided in the X direction.

An X-axis ball screw (not shown) rotated by an X-axis servo motor 18 having an encoder 19 is mounted on the bed 10 on the side of the column 11 so as to be rotatable around an axis parallel to the guide rail 12. The nut screwed to the ball screw is mounted on the lower surface of the column 11.
With such a configuration, the column 11 is guided by the pair of X-axis guide rails 12 via the X-axis ball screws and nuts by the rotation drive of the X-axis servo motor 18 and moves in the X direction.

On the other hand, a pair of Y-axis guide rails 22 are fixed to the front surface of the column 11 so as to extend in the Y direction which is the vertical direction of the machine tool 9 (the vertical direction in FIG. 1). Saddle 21 is moved by Y-axis guide rail 22
It is guided so as to be movable in the direction. In addition, a Y-axis servo motor 2 having an encoder 29 is provided above the column 11.
A Y-axis ball screw 23 rotated by 8 is rotatably supported about an axis parallel to the Y-axis guide rail 22, and the Y-axis ball screw 23 is screwed with a nut 24 attached to a spindle head 31. . With such a configuration, the saddle 2
Numeral 1 is guided by a pair of Y-axis guide rails 22 via a Y-axis ball screw 23 and a nut 24 by the rotational drive of a Y-axis servo motor 28 and moves in the Y direction.

A through hole is formed in the center of the saddle 21, and a spindle head 31 is inserted into the through hole. The spindle head 31 connects the spindle 25 to the front and rear direction of the machine tool 9 (in FIG. (Horizontal direction) so as to be rotatable around an axis extending in the Z direction. The spindle 25 is attached to the rear of the spindle head 31 and is driven to rotate by a spindle motor 48 having an encoder 49. A tool T such as a drill, an end mill, and a grindstone is removably mounted at the tip of the spindle 25.
The attachment and detachment of the tool T to and from the tool magazine are automatically performed by an automatic tool changer (not shown).

A pair of Z-axis guide rails 32 are fixed to the inner surface of the column 11 so as to extend in the Z direction, and the spindle head 31 is guided by the Z-axis guide rails 32 so as to be movable in the Z direction. I have. Also, at the back of column 11,
A Z-axis ball screw 33 rotated by a Z-axis servo motor 38 having an encoder 39 is rotatably supported around an axis parallel to the Z-axis guide rail 32. The Z-axis ball screw 33 is mounted on the spindle head 31. Nut 34 is screwed. With such a configuration, the spindle head 31 is driven by the rotation of the Z-axis servomotor 38 so that the Z-axis ball screw 33,
It is guided by a pair of Z-axis guide rails 32 via nuts 34 and moves in the Z direction.

A fixed or rotary indexing type table 15 is provided on the bed 10 in front of the column 11, and a workpiece W is fixed to the table 15 by a clamp mechanism (not shown). With the above-described configuration, the spindle 25 is rotationally driven by the spindle motor 48, and the spindle head 31 is moved along the X-axis guide rail 12 by the driving of the X-axis servomotor 18.
The tool T can be positioned at a desired machining position of the workpiece W by being driven in the Y direction by driving the Y-axis servo motor 28, and then advanced in the Z direction by driving the Z-axis servo motor 38. And a tool T such as a drill
Drilling is performed at the processing location.

When the tool T is an end mill, the workpiece W is controlled by simultaneously controlling two or three axes of the spindle head 31 in X, Y and Z directions orthogonal to each other at a contact position between the tool T and the workpiece W.
Can be subjected to a contouring process. If necessary, a plurality of workpieces may be mounted on the table 15. In the vicinity of the machine tool 9 configured as described above, a numerical controller 50 having a built-in computer and a sequence controller 60 not shown in FIG. 1 are arranged. The numerical controller 50 and the sequence controller 60 control the operation of the machine tool 9.

As shown in FIG. 2, the numerical controller 50 includes:
It is mainly composed of a CPU 51 and a memory 52.
The CPU 51 sends X,
Drive units 17, 27, 3 for controlling the Y and Z axes and the spindle
7, 47 are connected, and these drive units 17,
27, 37, and 47 have servo motors 18, 2 respectively.
8, 38 and 48 are connected. The memory 52 has a CP
An NC program area 52a for storing, by number, an NC program for the spindle 25 executed by the U51, a variable area 52b for storing state information such as speed attainment of the spindle 25 as a variable, and a time when the CPU 51 refers to the state information. And a timer area 52c to be stored.

The CPU 51 reads and analyzes the NC program stored in the NC program area 52a of the memory 52, calculates a large number of interpolation points up to a target position specified in each data block of the NC program, and calculates The interpolated points are input to the drive units 17, 27, 37, 47 at predetermined minute time intervals via the interface 54.
To each servo motor 1
8, 28, 38, and 48 are driven to rotate, and the main shaft 25 is moved in X-, Y-, and Z-directions, which are orthogonal three-dimensional directions, and the workpiece W is processed.

Servo motors 18, 28, 38 of each control axis
Are input via the interface 54 from the encoders 19, 29, and 39 attached to
The CPU 51 constantly monitors the position feedback signal, and confirms the completion of the feed movement when the deviation from the target position commanded in each data block of the NC program becomes zero.

The rotation speed of the spindle motor 48 is detected by an encoder 49 attached to the spindle motor 48 of the spindle 25, and the rotation speed of the spindle motor 48 reaches the rotation speed commanded by each data block of the NC program. When this is detected, a speed reaching signal is transmitted from the spindle drive unit 49. This speed reaching signal is input to the CPU 51 via the interface 54, and 1 is stored in the speed reaching information SB of the spindle 25 stored in the area 52c in the memory 52. When the speed reaching signal is not input, 0 is set in the speed reaching information SB.
Is stored. Therefore, the CPU 51 refers to the speed reaching information SB, and confirms that 1 is stored in SB, thereby confirming that the spindle 25 has reached the speed.

CPU 51 via interface 55
The input / output device 53 has push buttons and switches (not shown). Various commands input from the push buttons and switches are input to the input / output device 53 via the interface 55.
The information is transmitted to the PU 51 and various processes are executed. The sequence controller 60 connected to the CPU 51 via the interface 56 performs various auxiliary function commands specified in the NC program, for example, a spindle rotation start / stop command,
Receiving coolant ON / OFF command and tool change command,
The sequence control according to this command is executed.

Next, a method of controlling the machine tool 9 by the numerical controller 50 having the above configuration will be described with reference to FIGS. To start the control of the machine tool 9, the operator operates a push button and a switch group (not shown) of the input / output device 53 to instruct the CPU 51 to execute the NC program via the interface 55. CPU that received this
51 is the N stored in the area 52a of the memory 52
Among the C programs, the NC programs of the numbers designated by the push buttons and switches not shown in the input / output device 53 are read and processed.

Now, a case where the spindle head 31 processes a plurality of machining points of the workpiece W on the table 15 in accordance with the NC program 10 shown in FIG. 4 will be described with reference to a flowchart shown in FIG. First, the NC program 1 is sent to the CPU 51 by a not-shown push button and switch group of the input / output device 53.
When the execution of 0 is instructed, the block number N of the NC program is reset to zero (step 11), and the block number N is incremented by one (step 12). next,
The CPU 51 reads the block N010 in the first positioning step, which is the first block of the NC program 10 (step 13). This block N010 contains WHILE, G1
Since neither 85 nor G186 is described, the determinations in steps 14, 15 and 16 are all NO, and the process proceeds to step 17, where normal movement processing is performed.

In step 17, the description of the block N 010 in the first positioning step is analyzed to calculate interpolation points, and the interpolation points are output to the respective drive units 17, 27, 37, and 47 via the interface 54, and The X-axis servo motor 18 and the Y-axis servo motor 28 are rotationally driven to rapidly move the tool T held at 25 to the index position (X100, Y200, Z0) specified by the absolute value coordinates in the block N010. The main shaft motor 48 is driven to rotate at a rotation speed of 10,000 min ^-1 . Note that the coordinates of each axis in the NC program 10 are coordinates in a workpiece coordinate system having a reference point of the workpiece W as an origin.

Subsequently, from the feedback signals from the encoders 19 and 29 of the X-axis servo motor 18 and the Y-axis servo motor 28, until the completion of the movement of the feed axis in the first positioning step instructed in block N010 is confirmed. If the movement is continued and the completion of the movement is confirmed, the determination in step 18 becomes YES, and the process proceeds to step 19 even if the arrival of the speed of the spindle 25 is not confirmed. In step 19, it is determined whether the current block is the end of the program. If YES, the process ends, but if NO, the process returns to step 12.

In step 12, N is incremented by one, and the CPU 51 reads the block N020 of the second positioning step, which is the second block. In block N020, WHILE, G185, and G18 are provided as in block N010.
Since there is no description of No. 6, the determinations in Steps 14, 15 and 16 are all NO, and the process proceeds to Step 17, where normal movement processing is performed.

In step 17, the description of the block N020 in the second positioning process is analyzed to calculate and output the interpolation point, and the tool T held on the spindle 25 is moved to the block N020.
Point (X100, Y200, Z)
Fast forward to 50). This movement is performed based on the feedback signal from the encoder 39 of the Z-axis servo motor 38 based on the block N.
The movement is continued until the completion of the movement commanded in 020 is confirmed. When the completion of the movement in the second positioning step is confirmed, the determination in step 18 becomes YES and the process proceeds to step 19.

In step 19, it is determined whether or not the current block is the end of the program. If the result is YES, the program ends, but if the result is NO, the process returns to step 12. In step 12, N is incremented by one, and the CPU 51 reads the third block. Since a WHILE statement is described in this block, the determination in step 14 is YES, and the process proceeds to step 20. In step 20, it is determined whether SB = 0, which is the condition of the WHILE statement, is satisfied. This determination is made by referring to the contents of the variable SB representing the information on the speed attainment of the spindle in the variable area 52b in the memory 52,
This variable SB becomes SB = 0 when the speed has not been reached, and SB = 1 when the speed has been reached.

If SB = 0, that is, if the speed has not been reached, the determination in step 20 is YES and the process proceeds to step 21. In step 21, it is determined whether the timer 1 stored in the timer area 52c in the memory 52 has counted up. If NO, the process returns to step 20 and SB = 0 is determined again. If SB = 1, that is, if the arrival of the speed is not confirmed during the timer 1, the determination in step 21 is Y
The process proceeds to step 22 as ES, where abnormal processing such as stop of spindle rotation and return to the original position is performed, and the process ends. In addition,
Since the value of the timer 1 is stored in the memory 52 as a parameter, the value can be arbitrarily changed in accordance with various conditions such as the performance of the spindle motor 48.
It is preferable to set the start time to about the command rotation speed.

The determination in step 20 is NO (SB = 1)
When it is confirmed that the speed has been reached, the process proceeds to step 23, where N
Is incremented by one and the program passes through the block in which ENDWHILE is described, and returns to step 12. In step 12, N is incremented by one, and in step 13, the CPU 51 reads out the block N030 of the processing step which is the fifth block. WHIL in block N030
Since there is no description of any of E, G185, and G186, the determinations in steps 14, 15, and 16 are all NO, and the process proceeds to step 17, where normal movement processing is performed.

In step 17, the block N0 of the processing step
30 is analyzed and interpolation points are calculated and output, and the tool T held on the spindle 25 is changed to (X100, Y200, Z
70), the workpiece W is fed and moved at a speed of 1000 mm / min, and drilling is performed on the workpiece W. When the completion of the movement is confirmed from the feedback signal from the encoder 39 of the Z-axis servo motor 38, the determination in step 18 becomes YES, Step 19
Proceed to. In the step 19, the judgment is NO, and the process returns to the step 12.

In step 12, N is incremented by one, and the CPU 51 reads block N040. Since there is no description of any of WHILE, G185, and G186 in the block N040, the determinations in steps 14, 15, and 16 are all NO, and the process proceeds to step 17, where normal movement processing is performed. In step 17, the description of the block N040 is analyzed to calculate and output an interpolation point, and the tool T held on the spindle 25 is returned to the position (X100, Y200, Z50) before machining by rapid traverse.
When the completion of the movement is confirmed from the feedback signal from the encoder 39 of the shaft servomotor 38, the determination in step 18 is YE.
S, and the process proceeds to step S19.

The NC program 10 is executed as described above, and the workpiece W is machined by the tool T mounted on the main shaft 25. Further, according to the present invention, the WHILE statement is described before the block N030, which is a processing step, to check the speed attainment of the spindle 25. In addition, the following two types of G codes are used. It is also possible to describe and confirm the arrival of the speed.

First, as in the NC program 20 shown in FIG.
5 is described. In this case, the same processing as the above-described NC program 10 is executed up to the block N020 which is the second positioning step, and when the block N030 which is the processing step is read, the determination in step 15 of the flowchart of FIG. 3 becomes YES. Proceed to step 24. In step 24, the aforementioned NC program 10
Similarly to the above, the contents of the variable SB indicating the information of the speed arrival of the spindle in the variable area 52b in the memory 52 are referred to, and SB =
1, that is, reaching the command rotation speed of the main shaft 25 is determined.

When it is confirmed in step 24 that the speed has reached (SB = 1), the flow advances to step 17 where G in block N030 is set.
The movement process described after 185 is executed, and the workpiece W is processed. If it is not confirmed in step 25 that the speed of the spindle 25 has reached while the timer 2 times out, the process proceeds to step 22 and abnormal processing is executed. Since the value of the timer 2 is stored in the memory 52 as a parameter, it can be arbitrarily changed in accordance with various conditions. However, it is preferable to set the value to about the activation time up to the command rotation speed of the spindle motor 48. Is good.

Next, as shown in the NC program 30 shown in FIG. 6, the second step before the block N030 which is the machining step is performed.
G186 at the beginning of block N020, which is a positioning process
Is described. In this case, the same processing as that of the above-described NC program 10 is executed up to the block N010 which is the first positioning step, and when the block N020 which is the second positioning step is read, the determination in step 16 of the flowchart of FIG. If the result is YES, the process proceeds to a step S26, where a block N020 as a second positioning step
Is executed.

When the completion of the movement is confirmed from the feedback signal from the encoder 39 of the Z-axis servomotor 38 in the same manner as in the NC program 10 in the step 27, the determination in the step 27 becomes YES, and the process proceeds to the step 28. move on. In step 28, as in the above-described NC program 10, the contents of the variable SB representing the information on the speed attainment of the spindle in the variable area 52b in the memory 52 are referred to, and SB = 1
That is, it is determined that the spindle 25 has reached the command rotational speed. When it is confirmed in step 28 that the speed has reached (SB = 1), the processing in block N020 is terminated, and block N030, which is a machining process, is read out through steps 19 and 12, and the movement processing described in block N030 is executed. Then, the workpiece W is processed.

If it is determined in step 29 that the speed of the spindle 25 has not been reached while the timer 3 times out, the flow advances to step 22 to execute an abnormal process. Since the value of the timer 3 is stored as a parameter in the memory 52, it can be arbitrarily changed according to various conditions. However, it is preferable to set the value to about the activation time up to the command rotation speed of the spindle motor 48. Is good. Also, the timer 1 described above
The values of ~ 3 need not be the same, but can be different from each other.

According to the present embodiment, the relationship between the feed shaft speed of X, Y, and Z and the rotation speed of the main shaft with respect to time is shown in FIG.
It becomes as shown in. As shown in FIG.
In any of the cases of 0 to 30, the movement in the block N020 of the next second positioning step is executed even if it is not confirmed in the block N010 of the first positioning step that the rotation speed of the spindle 25 is commanded that the commanded rotation speed has been reached. Is done. Then, the rotation speed of the spindle 25 reaches the command rotation speed during the movement of the block N020 in the second positioning process,
This speed attainment is confirmed by one of WHILE, G185, and G186 after the movement of the block N020 in the second positioning process is completed and before the movement of the block N030 in the machining process is started, and the movement to the block N030 in the machining process is started. Transition.

As described above, according to the present embodiment, the spindle 2
5 without confirming that the rotation speed reaches the commanded rotation speed.
Since the processing of the data blocks subsequent to block N010, which is the first positioning step, including the rotation speed command of No. 5 is performed, and the speed of the spindle is reached before the block N030, which is the processing step, actual processing is performed. As described above, the time (t1) to wait for confirmation of the arrival of the spindle speed is not required, and the cycle time can be shortened accordingly. Although the present embodiment has described the drilling, the present invention can also be implemented in a milling or the like.

[0043]

As described above, according to the first aspect of the present invention, in the first positioning step in which the rotation speed of the spindle is commanded, the arrival of the feed shaft to the command rotation speed is not confirmed without confirming that the spindle reaches the commanded rotation speed. If the completion of the movement is confirmed, the subsequent steps are executed, so there is no time to wait for the spindle speed to reach,
Cycle time can be reduced. According to the second aspect of the present invention, the arrival of the spindle speed can be confirmed in any step between the first positioning step and the machining step, so that the degree of freedom in creating a program is improved and control with high versatility is possible. Become.
If the commanded rotation speed is not reached even after the lapse of the predetermined time, the process is regarded as abnormal and the subsequent steps are not executed, so that the abnormality can be reliably detected, and the machining is not started in the abnormal state. There is no deterioration of accuracy or tool breakage.

[Brief description of the drawings]

FIG. 1 is a side view of a machine tool provided with a spindle to be controlled by a numerical controller according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a schematic configuration of a numerical controller that controls the machine tool of FIG. 1;

FIG. 3 is a flowchart illustrating an outline of a control process executed by the numerical controller of FIG. 2;

FIG. 4 is a diagram showing an NC program 10 for confirming the arrival of the spindle speed by a WHILE statement.

FIG. 5 shows N for confirming the arrival of the spindle speed by G185.
FIG. 3 is a diagram showing a C program 20.

FIG. 6 shows N for confirming the arrival of the speed of the spindle by G186.
FIG. 3 is a diagram showing a C program 30.

FIG. 7 shows the NC programs 10, 20, and 3 of FIGS.
It is a figure which shows each feed axis speed of X, Y, Z at 0 and the relationship with respect to time of the rotational speed of a main shaft.

FIG. 8 is a diagram showing a conventional NC program 50.

9 shows X, Y, and Z in the NC program 50 of FIG.
FIG. 4 is a diagram showing a relationship between each feed shaft speed and the rotation speed of the main shaft with respect to time.

[Explanation of symbols]

18, 28, 38 X, Y, Z axis servo motors 19, 29, 39, 49 Encoder 25 Spindle 48 Spindle motor 50 Numerical control unit 51 CPU 52 Memory 52a NC program area 52b Variable area SB variable T Tool WHILE, G185, G186 Speed arrival information confirmation command

Claims (2)

[Claims] 1. A control method for controlling a machine tool to start machining of a workpiece after confirming that a spindle reaches a command rotation speed commanded by a data block of an NC program, wherein a tool is mounted. First, the main shaft is started to rotate and the feed shaft is driven to position the tool toward an indexing position aligned with a processing location of the workpiece in a cutting direction.
After the completion of the movement of the feed shaft is confirmed in the positioning step and the first positioning step, the tool is positioned in the cutting direction toward the machining start position without confirming that the spindle has reached the commanded rotational speed. After the completion of the second positioning step and the completion of the second positioning step, it is confirmed that the spindle has reached the commanded rotational speed. After the arrival of the speed has been confirmed, the tool is machined in the cutting direction. A method of controlling a machine tool, comprising: 2. The method of controlling a machine tool according to claim 1, further comprising: a confirmation command step of issuing a confirmation command for reaching the speed of the spindle in an arbitrary step before the machining step; A reference step of referring to speed attainment information stored in a memory; a machining step of machining and feeding the tool in the cutting direction if the speed attainment is confirmed within a predetermined time in the reference; A method for controlling a machine tool, further comprising an abnormality processing step of executing an abnormality processing when the arrival at the speed is not confirmed even after a lapse of time.