JPH11114775A - Thermal displacement amount calculating device for machine tool, and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal displacement amount calculating device capable of calculating the accurate thermal displacement amount corresponding to characteristics of individual machine tools as necessary without deteriorating work efficiency of the machine tool. SOLUTION: When precision machining is required (YES in S3), the thermal displacement amount of a machine tool is measured (S5) for each measuring timing (YES in S4), and a correction value is calculated (S7). The accurate thermal displacement amount corresponding to characteristics of individual machine tools and the using environment can be calculated by changing (S9) respective parameters to be used in the thermal displacement amount calculating processing (S1). Moreover, when precision machining is not required (NO in S3), the thermal displacement amount is calculated by numeric calculation by the thermal displacement amount calculating processing (S1), S4 to S9 are not performed. In this case, the thermal displacement amount can be easily calculated without deteriorating work efficiency of the machine tool.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a machine tool thermal displacement calculating apparatus which is mounted on a machine tool and calculates the amount of thermal displacement generated by the machine tool, and a storage medium for realizing the apparatus.

[0002]

2. Description of the Related Art Conventionally, processing means for cutting or drilling a work or assembling parts on a substrate, and driving means for changing the relative position between the processing means and a workpiece such as a work or a substrate. There is a machine tool having: Generally, in a machine tool that performs machining such as cutting, a holding mechanism for holding a tool such as a drill or a tap, a spindle drive mechanism for rotating and driving the tool held by the tool, and a feed of the tool in the X-axis direction -Axis feed mechanism for feeding the tool, Y-axis feed mechanism for feeding the tool in the Y-axis direction, Z-axis feed mechanism for feeding the tool in the Z-axis direction, a control device for controlling these feed mechanisms, etc. It has.

As an example, there is a machine tool 10 shown in FIGS. As shown in FIG. 15, the machine tool 10 includes a table 14 for placing a workpiece W (see FIG. 1) inside a splash guard 12 for preventing scattering of cutting chips, such as a drill or a tap. An ATC magazine 16 for tool change, a machine tool main body (hereinafter also simply referred to as a main body) 20, and the like are arranged. In addition, the splash guard 12 is provided with an operation panel 22, a work exchange port 24 for entering and exiting the work W and maintenance, an inspection hatch 26 mainly for maintenance, and the like.

As shown in FIG. 16, a main body 20 has a main shaft 2 for holding a tool T (FIG. 1) such as a drill or a tap.
8, a spindle motor 30 for rotating and driving the spindle 28, and a nut portion 3 containing a large number of steel balls and fixed to the spindle side.
2, a ball screw mechanism 36 including a ball screw 34 inserted into the nut portion 32, a Z-axis motor 38 for rotating and driving the ball screw 34, a guide rail 40 disposed parallel to the ball screw 34, the guide rail 40 and the main shaft 28.
It has a slide 42 and the like connecting the side.

In the main body 20, a Z-axis feed mechanism for feeding in the Z-axis direction is constituted by the ball screw mechanism 36 and the Z-axis motor 38. The ball screw 34 is rotated by the Z-axis motor 38 to rotate the main shaft 28. The movement in the Z-axis direction is performed. In addition, the table 14 shown in FIG. 15 can be moved in the X-axis and Y-axis directions, and the relative movement of the workpiece W and the tool T in the X, Y, and Z-axis directions can be made together with the movement of the main shaft 28 in the Z-axis direction. The position can be changed.

[0006] In such a machine tool, for example, frictional heat is generated by driving the ball screw mechanism 36, and the ball screw 34 may be extended. Also, other mechanisms generate heat. Such heat generation causes a thermal displacement in the machine tool. When this thermal displacement occurs in, for example, the Z-axis direction, an error occurs in the depth of the groove formed in the workpiece W, the height of the step, and the like. If the tolerance is sufficiently larger than the amount of thermal displacement, the processing error due to such thermal displacement does not cause much problem, but if not, the thermal displacement needs to be corrected. Therefore, a thermal displacement calculating device for calculating the thermal displacement of the machine tool is provided, and in controlling the driving means according to a predetermined machining program, the driving means is controlled while performing a correction according to the thermal displacement. (For example, JP-A-62-88548).

[0007]

However, in the conventional machine tool thermal displacement calculating apparatus, the thermal displacement is calculated while the machine tool is being driven, so that a system for executing the processing is used. Had to be constantly running. For this reason, the load involved in the calculation process was large. Therefore, the applicant of the present application has noticed that when the temperature is increased by continuing to drive the machine tool, the amount of heat generation and the amount of heat radiation eventually become balanced (the amount of thermal displacement at this time is referred to as the amount of saturated thermal displacement). Then, it was proposed to calculate the amount of thermal displacement as follows. That is, during the operation of the machine tool, the thermal displacement is calculated based on the saturated thermal displacement and the driving time of the machine tool, and when the thermal displacement becomes substantially equal to the saturated thermal displacement, the thermal displacement is thereafter calculated. Is substituted for the value of the saturated thermal displacement (Japanese Patent Application No. 8-298866).
issue). In this case, given the exact saturated thermal displacement,
The amount of thermal displacement at each time can be accurately calculated, and the load involved in the calculation process can be reduced.

[0008] Further, the applicant of the present invention, when given the value of the saturated thermal displacement (for example, L), the thermal displacement l when the machine tool is driven for t time, l = L · ｛1 -Exp (-γt)｝, or after driving the machine tool until the thermal displacement reaches the saturated thermal displacement L, and then calculating the thermal displacement 1 when the time t has elapsed after stopping the driving. , L = L · exp (−γt) (where γ is a constant specific to the machine tool).

However, the amount of thermal displacement actually generated in a machine tool changes according to the characteristics of each machine tool and the use environment. Further, the characteristics of the machine tool may change with time. For this reason, if the parameters such as L and γ are fixed uniformly and the thermal displacement of the machine tool is calculated, it is not possible to calculate an accurate thermal displacement reflecting the characteristics and the like of each machine tool. It was difficult to handle the processing.

Further, the applicant of the present application detects that the processing means has relatively moved to a predetermined position with respect to the workpiece by, for example, a contact-type sensor or the like, and determines the amount of thermal displacement based on the driving amount of the driving means at that time. It is also proposed to measure. In this case, since the thermal displacement amount is calculated based on the actually measured value,
The characteristics of each machine tool and the like are favorably reflected in the amount of thermal displacement. However, in this case, actual processing cannot be performed unless the processing of the workpiece by the processing means is interrupted once. Therefore, if the amount of thermal displacement is obtained only by actual measurement for machining that does not require much accuracy, the work efficiency of the machine tool is unnecessarily reduced.

Therefore, the present invention provides a machine tool capable of calculating an accurate amount of thermal displacement corresponding to the characteristics and the like of each machine tool as needed without unnecessarily reducing the working efficiency of the machine tool. It was made for the purpose of providing a thermal displacement calculating device.

[0012]

Means for Solving the Problems and Effects of the Invention In order to achieve the above object, the invention according to claim 1 comprises a processing means for processing a workpiece, and the processing means and the workpiece. A machine tool having a drive means for changing the relative position of the machine tool, the machine tool thermal displacement calculating apparatus for calculating the machine tool thermal displacement, wherein the drive state for detecting the machine tool drive state Detecting means, displacement amount calculating means for calculating the thermal displacement amount of the machine tool based on the driving state detected by the driving state detecting means, displacement amount measuring means for actually measuring the thermal displacement amount of the machine tool, Determining means for determining whether or not the actual measurement of the thermal displacement by the displacement measuring means is necessary; and when the determining means determines that the actual measurement is unnecessary, the displacement calculating means calculates the thermal displacement of the machine tool as the thermal displacement. Select the amount of thermal displacement, and When the cross-sectional unit determines that requires the actual, comprising selection means for selecting a thermal displacement amount of the displacement amount measured means has measured the thermal displacement amount of the machine tool, and
When the determination means determines that the actual measurement is unnecessary, the displacement amount actual measurement means does not perform the actual measurement.

According to the present invention, the displacement calculating means calculates the thermal displacement of the machine tool based on the driving state detected by the driving state detecting means. The determining means determines whether or not the actual measurement of the thermal displacement of the machine tool is necessary. When the determining means determines that the actual measurement is necessary, the measuring means actually measures the thermal displacement of the machine tool.

For this reason, unless the displacement amount calculating means calculates the thermal displacement of the machine tool and the actual measurement by the displacement measuring means is not performed, the thermal displacement can be easily calculated without stopping the machine tool. it can. Further, if the thermal displacement of the machine tool is actually measured by the displacement measuring device, an accurate thermal displacement corresponding to the characteristics of each machine tool, the use environment, and the like can be actually measured.

Therefore, the selecting means of the present invention obtains the thermal displacement of the machine tool as follows based on the judgment by the judging means. That is, when the determining means determines that the actual measurement is unnecessary, the thermal displacement calculated by the displacement calculating means is selected as the thermal displacement of the machine tool. Moreover, at this time, the displacement actual measurement means does not perform the actual measurement. In this case, the amount of thermal displacement of the machine tool can be easily calculated without lowering the work efficiency. The selecting means selects the thermal displacement measured by the displacement measuring means as the thermal displacement of the machine tool when the determining means determines that the actual measurement is necessary.
In this case, it is possible to calculate an accurate thermal displacement amount corresponding to the characteristics of each machine tool, the use environment, and the like. Therefore, according to the present invention, it is possible to calculate an accurate thermal displacement amount corresponding to the characteristics of each machine tool as needed without unnecessarily reducing the work efficiency of the machine tool. In the present invention, when it is determined that the actual measurement is necessary, the actual measurement is performed every time the thermal displacement is calculated. So, in this case,
The amount of thermal displacement of the machine tool can be calculated more accurately.

According to a second aspect of the present invention, there is provided a machine tool having processing means for processing a workpiece, and driving means for changing a relative position between the processing means and the workpiece. A machine tool thermal displacement amount calculating device for calculating a machine tool thermal displacement amount, wherein the drive state detecting means for detecting a drive state of the machine tool, and the drive state detected by the drive state detection means, A displacement amount calculating means for calculating a thermal displacement amount of the machine tool, a displacement amount measuring means for actually measuring the thermal displacement amount of the machine tool, a thermal displacement amount actually measured by the displacement amount measuring means, and the displacement amount calculating means. Comparing the calculated thermal displacement with the correction value calculating means for calculating a correction value for the thermal displacement calculated by the displacement calculating means, and judging whether the actual measurement of the thermal displacement by the displacement measuring means is necessary. Determining means for determining When it is determined that actual measurement is unnecessary, the thermal displacement calculated by the displacement calculator is selected as the thermal displacement of the machine tool, and when the determiner determines that the actual measurement is necessary, the thermal displacement of the machine tool is determined. Selecting means for selecting a value obtained by correcting the thermal displacement calculated by the displacement calculating means by the correction value as the amount, when the determining means determines that the actual measurement is unnecessary, The means does not perform the actual measurement, and the correction value calculating means does not calculate the correction value.

According to the present invention, the displacement calculating means calculates the thermal displacement of the machine tool based on the driving state detected by the driving state detecting means. The determining means determines whether or not the actual measurement of the thermal displacement of the machine tool is necessary. When the determining means determines that the actual measurement is necessary, the measuring means actually measures the thermal displacement of the machine tool. Furthermore, at this time,
The correction value calculating means compares the thermal displacement measured by the displacement measuring means with the thermal displacement calculated by the displacement calculating means, and calculates a correction value for the thermal displacement calculated by the displacement calculating means.

Therefore, unless the actual amount of displacement of the machine tool is calculated by the displacement amount calculating means and the actual measurement is not performed by the actual displacement amount measuring means, the amount of thermal displacement can be easily calculated without stopping the machine tool. it can. When the thermal displacement of the machine tool is actually measured by the displacement measuring device and the correction value is calculated by the correction value calculating device, the correction by the correction value is added to the thermal displacement calculated by the thermal displacement calculating device. Thus, it is possible to calculate an accurate amount of thermal displacement corresponding to the characteristics of each machine tool, the use environment, and the like.

Therefore, the selecting means of the present invention obtains the thermal displacement of the machine tool as follows based on the judgment by the judging means. That is, when the determining means determines that the actual measurement is unnecessary, the thermal displacement calculated by the displacement calculating means is selected as the thermal displacement of the machine tool. Moreover, at this time, the displacement actual measuring means does not perform the actual measurement, and the correction value calculating means does not calculate the correction value. In this case, the amount of thermal displacement of the machine tool can be easily calculated without lowering the work efficiency. When the determining means determines that the actual measurement is necessary, the selecting means selects, as the thermal displacement of the machine tool, a value obtained by correcting the thermal displacement calculated by the displacement calculating means with the correction value. In this case, it is possible to calculate an accurate thermal displacement amount corresponding to the characteristics of each machine tool, the use environment, and the like.

Therefore, according to the present invention, an accurate amount of thermal displacement corresponding to the characteristics of each machine tool can be calculated as needed without unnecessarily reducing the work efficiency of the machine tool. Further, in the present invention, instead of using the actually measured thermal displacement amount as it is, a correction value is calculated from the actually measured thermal displacement amount, and the thermal displacement amount calculated by the displacement amount calculating means using the corrected value is calculated. Has been corrected. Therefore, it is not necessary to actually measure the thermal displacement amount each time the thermal displacement amount is calculated.
Therefore, even when the actual measurement is required, it is possible to calculate the accurate amount of thermal displacement according to the characteristics of each machine tool and the like while securing the work efficiency of the machine tool in a favorable manner.

The third aspect of the present invention is the first or second aspect.
In addition to the configuration described above, the apparatus further comprises a precision machining determining means for determining whether a machining program for controlling the machine tool is compatible with precision machining, based on a result of the precision machining determining means, The determination means determines that the actual measurement is necessary when the machining program corresponds to precision machining, and determines that the actual measurement is unnecessary when the machining program does not correspond to precision machining.

In the present invention, the precision machining determining means determines whether or not the machining program corresponds to precision machining. Then, based on the result of the determination by the precision machining determination means, the determination means determines that the actual measurement is necessary when the machining program corresponds to precision machining, and does not require the actual measurement when the machining program does not correspond to precision machining. Judge. That is, the determination means according to claim 1 or 2 reads the operation state of the operation panel or the like to determine whether or not the actual measurement is necessary, but the total driving time of the machine tool has reached a predetermined time and a change with time has occurred. Various forms are conceivable, such as those that determine that the actual measurement is necessary when there is a possibility. In the present invention, the necessity of the actual measurement is determined according to whether the machining program is compatible with precision machining. I do. Therefore, the necessity of the actual measurement can be determined very appropriately and automatically.

Therefore, in the present invention, in addition to the effects of the first and second aspects of the present invention, the balance between the calculation accuracy of the thermal displacement of the machine tool and the work efficiency of the machine tool is extremely appropriately adjusted according to the machining program. In addition, there is an effect that the setting can be automatically performed. In addition, as described above, when the thermal displacement measured by the displacement measuring device is selected as the thermal displacement of the machine tool, the thermal displacement is calculated with more importance on the calculation accuracy. When the value corrected by the described correction value is selected as the thermal displacement of the machine tool, the thermal displacement can be calculated with more emphasis on the working efficiency of the machine tool. Therefore, when the precision machining determination means determines that the precision program is compatible with precision machining, it determines whether the machining program is compatible with ultra-precision machining that requires extremely high precision or with precision precision machining. In the case of (1), the thermal displacement measured by the displacement actual measuring means according to claim 1 may be selected as the thermal displacement of the machine tool in the latter case, and the value corrected by the correction value according to claim 2 may be selected. . In this case, there is an effect that the balance between the calculation accuracy of the thermal displacement of the machine tool and the work efficiency of the machine tool can be set more appropriately and automatically according to the machining program.

According to a fourth aspect of the present invention, in addition to the configuration of any of the first to third aspects, when the displacement measuring means moves relative to a predetermined position with respect to the workpiece, Processing means detecting means for detecting the processing means; processing means moving means for controlling the driving means to relatively move the processing means to a position detected by the processing means detecting means; By means of transportation
The driving amount of the driving means required to relatively move the processing means to a position detected by the processing means detecting means, and the driving amount required when no thermal displacement occurs in the machine tool And the actual amount of the thermal displacement is measured based on the comparison result.

In the displacement measuring device according to the present invention, the processing means is relatively moved by the processing means moving means to a position detected by the processing means detecting means, and then the driving means required for the relative movement is driven. The amount is compared with the drive amount required when no thermal displacement is generated in the machine tool, and the thermal displacement amount of the machine tool is actually measured based on the comparison result. For this reason, the accurate thermal displacement of the machine tool can be automatically and easily measured. Further, in the present invention, the processing means detecting means can be a simple one such as a contact type sensor, and the processing means moving means can use the same structure as the driving means. Therefore, in the present invention, in addition to the effect of the invention according to any one of claims 1 to 3, it is possible to reduce the manufacturing cost by simplifying the configuration of the apparatus, and to calculate the parameters more accurately and easily. There is an effect that it can be done.

According to a fifth aspect of the present invention, there is provided a processing means for processing a workpiece, a driving means for changing a relative position between the processing means and the workpiece, and a heat generated by driving the driving means. A displacement amount measuring means for measuring a displacement amount, the storage medium being used for a machine tool having a computer program for calculating a thermal displacement amount of the machine tool, the drive state of the machine tool being , A displacement amount calculation process for calculating a thermal displacement amount of the machine tool based on the drive state detected in the drive state detection process, and Displacement amount actual measurement process for actually measuring the displacement amount, a determination process for determining whether the actual measurement of the thermal displacement amount by the displacement amount actual measurement process is necessary, and when it is determined that the actual measurement is unnecessary in the determination process,
The thermal displacement calculated by the displacement calculating process is selected as the thermal displacement of the machine tool, and when it is determined that the actual measurement is necessary in the determining process, the displacement is determined as the thermal displacement of the machine tool. A selection process for selecting the thermal displacement amount actually measured in the actual amount measurement process, and a computer program for executing the same.When the determination process determines that the actual measurement is unnecessary, the displacement amount actual measurement process is performed. It is characterized in that it is set not to be performed.

Since the storage medium of the present invention is configured as described above, if a control means such as a computer connected to the machine tool executes a computer program stored in the present invention, the present invention will be described. It is possible to execute a drive state detection process, a displacement amount calculation process, a displacement amount actual measurement process, a judgment process, and a selection process corresponding to the drive state detection unit, the displacement amount calculation unit, the displacement amount actual measurement unit, the determination unit, and the selection unit. it can. Therefore, if the control means executes the computer program stored in the present invention, the same effect as the first aspect of the present invention is produced. Further, if a requirement limited to the invention according to claim 3 or 4 is added to the program of each process stored in the present invention, when the program is executed,
The same effects as the first and third aspects or the first and fourth aspects of the invention are obtained.

According to a sixth aspect of the present invention, there is provided processing means for processing a workpiece, driving means for changing a relative position between the processing means and the workpiece, and heat generated by driving the driving means. A displacement amount measuring means for measuring a displacement amount, the storage medium being used for a machine tool having a computer program for calculating a thermal displacement amount of the machine tool, the drive state of the machine tool being , A displacement amount calculation process for calculating a thermal displacement amount of the machine tool based on the drive state detected in the drive state detection process, and The displacement amount actual measurement process for actually measuring the displacement amount, the thermal displacement amount actually measured in the displacement amount actual measurement process, and the thermal displacement amount calculated in the displacement amount calculation process are compared. Thermal displacement calculated A correction value calculation process for calculating a correction value for, a determination process for determining whether or not the actual measurement of the thermal displacement amount is required by the displacement amount measurement process, and when it is determined that the actual measurement is unnecessary in the determination process, The thermal displacement calculated by the displacement calculating process is selected as the thermal displacement of the machine tool, and when it is determined that the actual measurement is necessary in the determining process, the thermal displacement of the machine tool is determined as the thermal displacement of the machine tool. A selection process for selecting a value obtained by correcting the thermal displacement amount calculated in the amount calculation process by the correction value, and a computer program for executing the selection process, and when the determination process determines that the actual measurement is unnecessary. Is set so that the actual displacement amount measurement processing and the correction value calculation processing are not performed.

Since the storage medium of the present invention is constructed as described above, if a control means such as a computer connected to the machine tool executes a computer program stored in the present invention, the storage medium according to the present invention is described in claim 2. Driving state detecting means, displacement amount calculating means, displacement amount measuring means, correction value calculating means, determining means, determining means, and driving state detecting processing, displacement amount calculating processing, displacement amount actual measuring processing, correction value calculating processing, determining means A process and a selection process can be executed. Therefore, if the control means executes the computer program stored in the present invention, the same effect as the second aspect of the present invention is produced. Further, if a requirement limited to the invention described in claim 3 or 4 is added to the program of each process stored in the present invention, when the program is executed, the program is executed in claim 2 and 3 or claim 2 and The same effect as the invention described in the fourth aspect is obtained.

[0030]

Embodiments of the present invention will now be described in detail with reference to the drawings.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The mechanical configuration of a machine tool according to this embodiment is as follows.
1 except that the following detector 49 was provided.
5 and FIG. 16, the description of the mechanical configuration of the machine tool 10 will be omitted by using them.

FIG. 1 is a schematic diagram showing the structure of the detector 49. As shown in FIG. 1, the detector 49 is fixed to one corner of the table 14 and generates a contact signal when the tool T held on the main shaft 28 contacts. Further, the detector 49 is configured so that the position on the Z axis can be changed so that measurement can be performed at an optimum position according to the workpiece W.
When the position is changed, data relating to the position on the Z axis stored in the CPU 72 or the like described later is updated.

FIG. 2 shows a machine tool 10 as a first embodiment.
FIG. 2 is a block diagram illustrating a configuration of a control system. As shown in FIG. 2, the control system is a main shaft control system 50 for controlling the rotation of the main shaft 28, a Z-axis control system 60 for controlling the Z-axis position of the main shaft 28, and the center of this control system. The microcomputer unit 70, the operation panel 22, the detector 49, the X-axis control system (not shown) for controlling the X-axis position of the table 14 and the table 1
4 includes a Y-axis control system (not shown) for controlling the Y-axis position.

The spindle control system 50 includes a spindle motor 30 and a spindle servo amplifier 5 for supplying power to the spindle motor 30.
2, and an axis control circuit 54 for controlling the power supplied to the spindle servo amplifier 52. The axis control circuit 54 controls the operation of the spindle servo amplifier 52 in accordance with an instruction from the CPU 72 of the microcomputer unit 70. Z axis control system 60
Are a Z-axis motor 38, a Z-axis servo amplifier 62 for supplying power to the Z-axis motor 38, and a Z-axis servo amplifier 62.
An axis control circuit 64 for controlling the supply power of
The axis control circuit 64 controls the operation of the Z-axis servo amplifier 62 according to an instruction from the CPU 72 of the microcomputer unit 70. Further, an X-axis control system and a Y-axis control system (not shown) have substantially the same configuration as the main axis control system 50 and the Z-axis control system 60.

The microcomputer unit 70 is composed of a one-chip type CPU 72, a RAM 74, a clock 76, etc., having a built-in ROM and an input / output port for storing a control program and the like, and is configured as a well-known microcomputer. The microcomputer unit 70 (strictly, the CPU 72) controls the spindle control system 50, the Z-axis control system 60, and the like in accordance with a machining program corresponding to the machining to be performed on the workpiece W, and performs a predetermined machining on the workpiece W. is there. Further, the microcomputer unit 70 is connected to the operation panel 22 and the detector 49, and the microcomputer unit 70 is connected to the operation panel 22 or the detector 4.
9 to control the display of images and characters on the liquid crystal display of the operation panel 22 by sending a signal to the operation panel 22, control the blinking of LEDs, and the like.

The RAM 74 is a work area for the CPU 72 as is well known.
A pitch error correction table having the configuration shown in FIG. 3 is provided above. This pitch error correction table is a table for correcting a driving error of the ball screw mechanism 36, for example.

Ball screw mechanism 36 responsible for Z-axis movement
Is the amount of rotation of the ball screw 34 and the amount of movement of the nut 32 due to a manufacturing error (ie, the amount of movement of the main shaft 28 in the Z-axis direction).
It is necessary to correct the error since it cannot be avoided. Therefore, an appropriate number of correction points are set (if the length of the ball screw 34 is 500 mm and correction is performed every 20 mm, the number of correction points is 25). An error between the calculated value and the actually measured value is obtained, and a rotation amount (pitch) of the ball screw 34 corresponding to the error is written in a pitch error correction table, and the ball screw 34 is rotated forward or backward by the pitch for each correction point. By doing so, the Z-axis position of the main shaft 28 is accurately adjusted. X axis and Y
The same is true for the axis.

The clock 76 is a so-called electronic clock.
The date can be calculated and the data can be sent to the CPU 72. It should be noted that the CPU 72 has a predetermined period, for example, 1 /
A built-in counter for incrementing the count value every 1000 seconds is provided, and by using the counter, an elapsed time such as a required time from the start to the end of a certain processing can be measured.

When the machine tool 10 is driven, thermal displacement occurs in the Z-axis direction due to expansion of the ball screw 34 and the like. Thus, the CPU 72 executes the following processing in order to execute the machining program while correcting the thermal displacement. FIG. 4 is a flowchart illustrating a main routine of a process executed by CPU 72. In addition,
The CPU 72 executes this process as an interrupt process at a predetermined timing after the power is turned on, and calculates a thermal displacement amount generated by executing a machining program or the like.

As shown in FIG. 4, when the CPU 72 starts the process, first, in S1 (S represents a step: the same applies hereinafter), the CPU 72 calculates a thermal displacement amount based on the driving state of the machine tool 10. A displacement amount calculation process is executed, and S3, S4
It moves sequentially to. In S3, it is determined whether or not it is necessary to perform the precision processing on the workpiece W, and in S4, it is determined whether or not it is the actual measurement timing described below. If there is no need to perform precision machining (S3: NO), and if precision machining is necessary (S3: YES), and it is not the actual measurement timing (S4: NO), the process returns to S1 and the amount of thermal displacement is returned. Continue the calculation of. In addition, it is necessary to perform precision processing (S
3: YES), and when it is the actual measurement timing (S4: YES), the process proceeds to S5 to S9 described below,
After actually measuring the amount of thermal displacement and changing various parameters used in S1, the process proceeds to S1.

In S3, the necessity of the precision machining is determined by. A special code is provided in a machining program executed by the machine tool 10, and when the code is detected, it is determined that precision machining is performed. When the command (cutting, positioning, etc.) corresponding to the NC data of the processing program is a predetermined command (for example, cutting), it is determined that precision processing is performed.
Define whether or not to perform precision machining for each program. Various forms, such as making a determination based on the operation state of the operation panel 22, are possible. The actual measurement timing in S4 is. A predetermined time has elapsed since the last actual measurement. Spindle 2
8 has moved a predetermined distance,. The measurement movement command is read as NC data of the machining program. Operation panel 2
2 was operated according to a predetermined procedure.

Here, the process of calculating the amount of thermal displacement in S1 will be described. FIG. 5 is a flowchart illustrating the details of the thermal displacement amount calculation processing in S1. In this routine, first, S1
At 1, processing is performed for assuming that the moving distance during power-off is 0. As will be described later, when the amount of thermal displacement has been calculated in the past and its influence still remains, it is necessary to calculate the amount of thermal displacement of the machine tool 10 in consideration of the effect. Further, such a thermal displacement amount is generated by the machine tool 10 during a break time in a factory or the like.
May remain even after the power is turned off.
Therefore, in S11, the moving distance of the main shaft 28 in the Z-axis direction while the power is turned off is set to 0.

In S12, it is determined based on the output of the clock 76 whether a predetermined sampling time (interval a) has been reached. If it is not the sampling time (S12: NO), the process stands by, and if it is the sampling time (S12: YES), the process proceeds to S13. In S13, the driving state of the machine tool 10 is detected from the execution state of the machining program and the like, and the movement distance of the main shaft 28 in the Z-axis direction during the sampling time is calculated based on the detected driving state. Then, the process proceeds to S14, and the maximum displacement L as the saturated thermal displacement is calculated as follows.

When the temperature rises by continuing to drive the machine tool 10, the heat generation and the heat radiation eventually balance. The thermal displacement at this time is the maximum displacement L. When the machine tool 10 is continuously driven in a constant state, the maximum displacement L
Has a correspondence shown in FIG. 6 with respect to the average moving distance of the spindle 28 per unit time. As shown in FIG. 6, the maximum displacement L increases as the average moving distance increases.
This correspondence is represented by a line graph in which the slope becomes gentler when the average moving distance is equal to or more than a predetermined value. This is because when the main shaft 28 moves at a high speed, the heat radiation increases due to the air cooling effect, and the thermal displacement is suppressed. In S14, the moving distance calculated in S13 is converted into an average moving distance per unit time (here, mm / min),
The corresponding maximum displacement L is calculated with reference to the map of FIG. The map in FIG. 6 may be stored in the CPU 72 in the form of a mathematical expression or a data table.

At S15, the thermal displacement 1 during the sampling time is calculated as follows. As illustrated in FIG. 7, when the maximum displacement is _L1a , the machine tool 10
The thermal displacement l during driving is asymptote ₁ to the straight line l = L1a.
Draw 02. Furthermore, after the thermal displacement amount l has reached the maximum displacement amount L _1a (time point t = 8hour 7), the machine tool 10
Is stopped, the thermal displacement l draws an asymptote 104 with respect to the straight line l = 0. Here, asymptote 102 is a _{l = L 1a · {1-} exp (-γt)} ...... (1), asymptote 104 is a _{l = L 1a · exp (-γt} ) ...... (2) , Respectively. Here, γ is a constant unique to the machine tool 10, and the units of t and l are respectively hour and μm.
It is. Therefore, from this equation, the thermal displacement l _1a a minute after the start of driving of the machine tool 10 is given by l _1a = L _1a · {1-exp (−γ · a / 60)}. Also, the thermal displacement l after a minute after the machine tool 10 stops
_-1a is expressed as follows: l _-1a = L _1a · exp (−γ · a / 60) In S15, the thermal displacement 1 during the sampling time is calculated mainly using Expression (1). Further, the following S16
Then, after adding the thermal displacement amount 1 within the holding time described later to calculate the total thermal displacement amount as follows, the above-described S3 (FIG. 4)
Move to.

In this embodiment, when the thermal displacement 1 is calculated based on the moving distance during the sampling time (S13 to S13).
S15) It is considered that the thermal displacement l subsequently decreases according to the equation (2). That is, as exemplified by the curve 201 in FIG. 8A, the value l _1a-1 of the thermal displacement amount l _{1a at} the time 1a calculated based on the moving distance from the time 0 to the time 1a is as described above. _L1a-1 = L1a ₁ {1-exp (-γ ・ a / 60)}. Here, _L1a is the maximum displacement calculated at the sampling time of time 1a. Then, the value l _1a-2 of the thermal displacement l _{1a at} the time 2a is calculated from the equation (2) as follows: l _1a-2 = l _1a-1 · exp (−γ · a / 60) Thermal displacement l _{1a at} time 4a
The values l _1a-3 and l _1a-4 are as follows: l _1a-3 = l _1a-1 · exp (−γ · 2a / 60) l _1a-4 = l _1a-1 · exp (−γ · 3a / 60) ). Similarly, if the maximum displacement L _2a is calculated based on the movement distance from time 1a to time 2a,
The corresponding thermal displacement l _2a is shown by curve 202 in FIG.
And the values l _2a-1 , l _2a-2 , and l _{2a-3 at} the times 2a, 3a, and 4a are respectively: l _2a-1 = L _2a · ｛1-exp (−γ · A / 60)｝ l _2a-2 = l _2a-1 · exp (-γ · a / 60) l _2a-3 = l _2a-1 · exp (-γ · 2a / 60) In S16, the total thermal displacement is calculated by adding the values of the thermal displacements l _1a , l _2a ,... Calculated at this time at that time. For example, time 1a, 2
Based on the movement distances between the sampling times of a, 3a, 4a, 5a,..., curves 201, 20 in FIG.
Assuming that the thermal displacement 1 illustrated in 2, 203, 204, 205,... Has been calculated, the total thermal displacement calculated in S16 changes as illustrated by the curve 200 in FIG.

The thermal displacement 1 calculated at each time is
As described above, the value decreases with the lapse of time.
It is possible to neglect the influence of the thermal displacement 1 over a predetermined time (for example, 120 minutes) after calculation on the total thermal displacement. Therefore, the CPU 72 stores the predetermined time in the ROM as the holding time, and calculates the total thermal displacement by performing the above addition only on the thermal displacement 1 calculated within the holding time. Therefore, the number of thermal displacements l that must be added in the process of S16 is 120
/ A + 1 is suppressed to a natural number or less, and the load related to the calculation process can be reduced. Therefore, it is possible to simplify the software configuration and the like related to the processing and improve the processing speed.

Further, the CPU 72 associates the thermal displacement 1 calculated at each time with the calculated time at the RAM.
74, and the stored contents are stored in the power supply O.
It is also held between the FFs by a backup power supply (not shown). For this reason, the power is once turned off and turned on again.
In step S11, the moving distance during power-off is regarded as 0 (therefore, the thermal displacement 1 is also 0) in step S11, and in step S16,
Then, the total thermal displacement can be calculated by adding the influence of the thermal displacement 1 calculated during the previous power-on period, which has not passed the holding time since the calculation, and calculating the total thermal displacement. .

Returning to FIG. 4, if it is necessary to perform precision machining on the workpiece W (S3: YES), and if it is the actual measurement timing (S4: YES), the flow proceeds to S5 to perform the next displacement amount actual measurement processing. Execute In the displacement amount measurement processing of S5,
The Z-axis control system 60, the X-axis control system, and the Y-axis control system are driven to bring the tool T held on the main shaft 28 into contact with the detector 49. The CPU 72 receives the contact signal from the detector 49 and determines the Z-axis control system 6 required to confirm the contact.
A drive amount of 0 is calculated and compared with the above-mentioned calculated drive amount required when no thermal displacement occurs in the machine tool 10. Then, the amount of thermal displacement (Z-axis direction) of the machine tool 10 is calculated (actually measured) based on the comparison result.

After the actual measurement of the amount of thermal displacement, a correction value calculation process in S7 is executed. In this process, the total thermal displacement calculated in S1 (hereinafter referred to as a calculated value) is compared with the thermal displacement measured in S5 (hereinafter referred to as an actually measured value) to calculate a correction value for the calculated value. I do. In S9, based on the correction value calculated in S7, various parameters (including mathematical formulas) used in S1 are changed and stored in a predetermined area of the RAM 74 (parameter change processing).

Here, the processing in S7 and S9 includes a mode in which the difference between the calculated value and the actually measured value is used as a correction value, and a mode in which the ratio between the two is used as a correction value. A desired form can be selected by setting the panel 22. In FIGS. 9A and 9B, the change in the calculated value of the thermal displacement l when no correction based on the actually measured value is performed is represented by a solid line, and the time t0 (measured timing)
The measured value detected by is indicated by ■.

When utilizing the difference between the calculated value and the actually measured value,
As illustrated in FIG. 9A, a difference Δl obtained by subtracting the calculated value from the actually measured value is calculated as a correction value (S7), and the above Δl is added to the equations (1) and (2) used in S15, respectively. (S9). By executing the processing of S5 to S9 and shifting to S1 again, the total thermal displacement calculated in the processing of S1 can be corrected as shown by the dotted line in FIG.

When using the ratio between the calculated value and the actually measured value,
As illustrated in FIG. 9B, the measured value l2 and the calculated value l1
Is calculated as the correction value (S7).
In Equations (1) and (2) used in Equation 5,
The processing of multiplying by l1 is performed (S9). By executing the processing of S5 to S9 and shifting to S1 again, the total thermal displacement calculated in the processing of S1 can be corrected as shown by the dotted line in FIG. 9B.

The case where the difference between the calculated value and the actually measured value is used as a correction value and the case where the ratio between the two is used have the following advantages.
Allows a desired form to be selected. As described below, it is advantageous to use the difference when the absolute value of the calculated value and the measured value is small, and to use the ratio when the absolute value of both is large. Therefore, when the absolute value of the calculated value or the actual measurement value is small, a mode in which the difference between the two is used as the correction value is automatically selected, and when the absolute value is large, a mode in which the ratio of the two is used as the correction value is automatically selected. May be configured. Furthermore, other forms that are not differences or ratios may be employed.

If the absolute values of the calculated value and the actually measured value are extremely small, a slight measurement error will be reflected in the value of the ratio between the two. For this reason, when the ratio between the calculated value and the actually measured value is calculated as a correction value, and the value is multiplied or divided by the total thermal displacement calculated in S1, the total thermal displacement that is large in S1 except at time t0 is calculated. When the displacement amount is calculated, there is a possibility that a measurement error or the like is multiplied or divided by the calculated value and largely reflected. On the other hand, if the difference between the calculated value and the actually measured value is used as the correction value as shown in FIG. 9A, the same amount is always obtained regardless of the absolute value of the total thermal displacement calculated in S1. Corrections can be made. Therefore, in this case, even when the absolute value of the calculated value serving as the basis for calculating the correction value and the actual measurement value is extremely small, it is possible to calculate the accurate amount of thermal displacement.

When the absolute value of the calculated value and the measured value is extremely large, the absolute value of the difference between the two tends to be large. For this reason, when the difference between the calculated value and the actually measured value is used as a correction value, it is difficult to use the same correction value when a small total thermal displacement is calculated in S1 at a time other than the time t0. . For example, the corrected thermal displacement may be negative. On the other hand, if the ratio between the calculated value and the actually measured value is used as a correction value as shown in FIG. 9B, when a small total thermal displacement is calculated in S1, a small correction corresponding thereto is performed. It can be carried out. Therefore, in this case, even when the absolute value of the calculated value serving as the basis for calculating the correction value and the measured value is extremely large, the accurate thermal displacement amount can be calculated.

As described above, in the microcomputer section 70 of the present embodiment, when it is necessary to perform precision machining on the work W (S3: YES), the microcomputer 70 performs the measurement at each measurement timing (S4: YE).
In S), the thermal displacement of the machine tool 10 is actually measured (S5), and a correction value is calculated (S7). Then, by changing various parameters based on the correction value (S9), the total thermal displacement calculated in the thermal displacement calculating process (S1) can be corrected. In this case, it is possible to calculate an accurate thermal displacement amount corresponding to the characteristics of each machine tool 10 and the use environment.

When it is not necessary to perform precision machining (S3: NO), the thermal displacement is calculated by numerical calculation in the thermal displacement calculating process (S1), and the actual measurement (S5) and the correction value are calculated (S5). S7) and the parameter change (S9) are not performed. In this case, the amount of thermal displacement of the machine tool 10 can be easily calculated without lowering the work efficiency. Therefore, in this embodiment, the individual machine tools 10 can be used without unnecessarily reducing the work efficiency of the machine tools 10.
An accurate amount of thermal displacement corresponding to the characteristics of the above can be calculated as required.

Further, in the present embodiment, a correction value is calculated from the actually measured thermal displacement amount instead of using the actually measured thermal displacement amount as it is, and the total thermal displacement amount calculated in S1 is corrected. Corrected using the values. For this reason, if the above-mentioned thermal displacement amount is measured at a predetermined actual measurement timing (for example, every 30 minutes) while the machine tool 10 is being driven, then a sufficiently accurate thermal displacement can be obtained using the correction value calculated from the actual measurement value. The amount can be calculated. That is, when the thermal displacement is actually measured by using the detector 49 as in the present embodiment, the machining of the work W must be temporarily interrupted at the time of the actual measurement. You only need to do it at the right time. Therefore, even when the above-described actual measurement is required, it is possible to calculate the accurate amount of thermal displacement according to the characteristics of the individual machine tools 10 and the like while securing the work efficiency of the machine tool 10 well. .

In the above embodiment, the main shaft 28 is used as the machining means, and the ball screw mechanism 36 and the Z-axis control system 60, X
The axis control system, the Y-axis control system are the driving means and the processing means moving means, the detector 49 is the processing means detecting means, and the CPU 72 is the driving state detecting means, the displacement calculating means, A CPU corresponds to a displacement actual measurement unit, a correction value calculation unit, a judgment unit, a precision machining judgment unit, and a selection unit.
Of the processing of S72, S13 corresponds to the driving state detection means, and S14
S16 to displacement amount calculation means, S5 to displacement amount measurement means, S7 to correction value calculation means, judgment processing in S3 and S4 to judgment means, of which S3 to precision machining judgment means, and S3 to S4 The distribution of the processing is processing corresponding to the selection means.

Next, FIGS. 10 and 11 show the C of the first embodiment.
15 is a flowchart illustrating another form of the main routine executed by the PU 72. This process is started when the machine tool 10 is driven. First, in S31, one NC data instruction is read. That is, the machining program is composed of a combination of a large number of NC data representing commands such as cutting and positioning, and reads the NC data by one instruction from the beginning each time the process proceeds to S31. The machining program handled in this routine also includes, as NC data, a measurement movement command for instructing the detector 49 to actually measure a thermal displacement amount. The ROM of the CPU 72 stores a data table as exemplified in Table 1, and stores the number of pointers and the set number of times in association with each other.

[0062]

[Table 1]

Here, the number of pointers indicates the number of times the actual measurement of the thermal displacement was actually performed, and the set number indicates the number of times the measurement movement command was read. That is, when processing described later is executed based on the data table in Table 1, the first actual measurement is performed when the first measurement movement command is read, and the second measurement is performed when the third measurement movement command is read. Perform an actual measurement.

After reading one NC data command in S31, the flow shifts to S33, and it is determined whether or not the command is the above-described measurement movement command. If it is not a measurement movement command (S3
3: NO), the NC data is executed in S35, and the routine goes to S31. By repeating this process,
Processing according to the processing program can be performed on the work W. If a measurement movement command has been read in S31 (S33: YES), the flow shifts to S37 to determine whether or not precision machining is necessary, as in S3 described above. If there is no need for precision machining (S37: NO), the flow shifts to S39, where the same amount of displacement calculation processing as in S1 is executed, and S3 is executed.
Move to 1.

In S37, precision processing is required (YE
When it is determined as S), the process proceeds to S41, and it is determined whether or not a value of a later-described operation stop timer (hereinafter, also simply referred to as a timer) is equal to or longer than a preset monitoring stop time. If the timer value is longer than the monitoring stop time (S4
1: YES), after resetting the counter for counting the number of times of the measurement movement command, the pointer, and the timer to 0 (S43), if the value of the timer is less than the monitoring stop time (S41: NO), each is left as it is. Move to S45.

Here, the CPU 72 starts the operation stop timer from 0 while the machine tool 10 is stopped. Table 1
Is set so as to reduce the number of times the actual measurement is performed in response to the measurement movement command as the work of the machine tool 10 proceeds, but when the stop time of the machine tool 10 is longer than the stop monitoring time (S41: YES), the amount of thermal displacement changes significantly during stoppage. Therefore, in such a case, S43
Resets the counter, pointer, and timer, and again performs actual measurement faithful to the measurement movement command.

In S45, the value of the counter is incremented by one, and in S47, it is determined whether or not the value of the counter is 1. When the counter is 1 (S47: YE
S), the process proceeds to S49, performs the same displacement amount measurement processing as in S5, and proceeds to S31. When the thermal displacement is measured in S49, the measured value is referred to in S35 for executing the machining program while correcting the thermal displacement. That is, when S49 is executed, the thermal displacement actually measured in S49 is used as it is instead of the total thermal displacement calculated in S39.

On the other hand, if the value of the counter is not 1 (S
47: NO), the value of the counter is compared with the set number of times corresponding to the pointer to determine whether or not actual measurement is necessary (S5).
1) If necessary (YES), proceed to S49; if unnecessary (NO), proceed to S31. Here, the processing of S51 will be described in detail with reference to FIG. As shown in FIG. 11, when shifting from S47 to S51, first, the set number indicated by the pointer is read from the data table of Table 1 in S53. In subsequent S54, it is determined whether or not the value of the counter is equal to the set number of times. When the counter is equal to the set number of times (S54: YES), the value of the pointer is incremented by one (S57), and the process proceeds to the displacement amount actual measurement process of S49.
When the value of the counter is less than the set number of times (S5
4: NO), when the thermal displacement amount actually measured in the previous S49 (previous displacement amount) is equal to or larger than a preset monitoring displacement amount (S55: YES), or the counter value is periodically monitored. If it is equal to the number of times (S56: YES), the process similarly proceeds to S49. In cases other than the above, S3
Move to 1.

That is, when the previously measured thermal displacement is equal to or greater than the monitored displacement (for example, 0.020 mm), it is desirable to measure the thermal displacement immediately after the measurement movement command is issued. The number of regular monitoring (for example, 1000 times) is a numerical value set in advance for periodically measuring the thermal displacement amount. Therefore, in the process of S51 (that is, S53 to S57), when the value of the counter matches the set number of times or the number of regular monitoring in Table 1, and when the previously measured thermal displacement amount is equal to or more than the monitored displacement amount. Makes the actual measurement of the thermal displacement amount in S49, and otherwise judges that the actual measurement is unnecessary.

Even when this routine is executed by the CPU 72 of the microcomputer unit 70, if it is necessary to perform precision machining on the work W, similarly to the processing of FIG. 4 (S37: YE
S), the thermal displacement of the machine tool 10 can be actually measured (S49). Therefore, in this case, it is possible to calculate an accurate thermal displacement amount corresponding to the characteristics of the individual machine tools 10 and the use environment. If it is not necessary to perform precision machining (S37: NO), the thermal displacement is calculated by numerical calculation in the thermal displacement calculation process (S39), and the actual measurement (S4
9) is not performed. Therefore, in this case, the thermal displacement amount of the machine tool 10 can be easily calculated without lowering the work efficiency.

Accordingly, even when this routine is executed by the CPU 72, an accurate amount of thermal displacement corresponding to the characteristics of each machine tool 10 can be obtained as needed without unnecessarily reducing the work efficiency of the machine tool 10. Can be calculated. In this routine, the actually measured thermal displacement is used as it is when executing the machining program. That is, in this routine, the above-described actual measurement is performed each time the amount of thermal displacement is calculated during precision machining. Therefore, the amount of thermal displacement of the machine tool 10 can be calculated more accurately, and the processing accuracy of the work W can be further improved.

The main routine is an embodiment corresponding to claim 1 and its dependent claims.
39 corresponds to the displacement amount calculating means, S41 to S49 correspond to the displacement amount measuring means, the judgment processing in S37 corresponds to the judgment means and precision machining judgment means, and the distribution of the processing in S37 corresponds to the selection means.

In the main routine, the processing for executing the processing program to perform the processing on the work W (S31 to S31)
S35) and processing for calculating the amount of thermal displacement of the machine tool 10 (S35)
37 to S51) are a series of processes, but both may be configured by separate routines. In this case, regardless of whether the measurement movement command is issued,. When a predetermined time has elapsed since the last measurement, When the main shaft 28 moves a predetermined distance,. When the operation panel 22 is operated according to a predetermined procedure, the processing of S37 to S51 is executed, and the amount of thermal displacement can be calculated. Therefore, the present invention can be applied to a machining program that does not include a measurement movement command as NC data.

Next, a second embodiment of the present invention will be described. FIG. 12 is a block diagram illustrating a configuration of a control system of the machine tool 10 according to the second embodiment. Note that the machine tool 1 of the present embodiment
The mechanical configuration of the control system 0 is the same as that of the first embodiment, and the configuration of the control system differs in the following points. That is, as shown in FIG. 12, the microcomputer unit 70 includes an interface (I / F) 78 in addition to the above-described configuration, and is connected to the personal computer 80 via the interface 78. The personal computer 80 includes a one-chip type CPU 82 having a ROM for storing a control program and the like, an input / output port, and the like.
It comprises an M84, a clock 86, an interface (I / F) 88 connected to the microcomputer unit 70, and the like, and is configured as a known microcomputer. Further, a keyboard 91 and a CRT 92 are also connected to the personal computer 80.

In this control system, the microcomputer unit 70 controls the machine tool 10 based on a machining program, and the microcomputer unit 70 sends the PC 80 a necessary distance for calculating the total thermal displacement such as the moving distance of the spindle 28. Data, detector 4
The measured thermal displacement amount and the like are transmitted via 9. Further, the personal computer 80 calculates the thermal displacement amount (total thermal displacement amount) of the machine tool 10 by the following processing, and transmits the calculated total thermal displacement amount to the microcomputer unit 70. Then, the microcomputer unit 70 executes the machining program while performing correction based on the transmitted total thermal displacement amount.

The personal computer 80 (strictly speaking, the CPU 82)
Almost the same processing as that of FIG. 4 described above is executed.
The thermal displacement amount calculation process 1 and the displacement actual measurement process S5 are executed not by controlling the Z-axis control system 60 and the like but by transmitting and receiving the data and the drive command of the main shaft 28 and the like to and from the microcomputer unit 70. I do. For example, the thermal displacement calculation process in S1 is as shown in FIG. Note that this thermal displacement amount calculation processing is almost the same as the thermal displacement amount calculation processing shown in FIG. 5, and therefore only different parts will be described.

In S13a executed instead of S13,
The CPU 82 does not calculate the moving distance by itself, but reads the moving distance transmitted from the microcomputer unit 70. Also,
In S16a executed in place of S16, after calculating the total thermal displacement in the same manner as in S16, the total thermal displacement is transmitted to the microcomputer unit 70. Other processes are the same as those in the first embodiment, and the detailed description is omitted by using the reference numerals used in FIG. 5 as they are. The personal computer 80 also executes the displacement measurement process in S5 by the same transmission and reception.

In the present embodiment thus configured, the first
Functions and effects substantially similar to those of the embodiment are obtained. Also, in the present embodiment, the same processing as in FIG. 10 can be executed.
In this case, the processes in S31 to S35 are processes performed only by the microcomputer unit 70. Note that, also in the present embodiment, the CPU 82
The amount of thermal displacement 1 calculated at each time is stored in the table of the RAM 84 in association with the time at which it was calculated, but the stored content does not necessarily need to be backed up. This is because if the power of the personal computer 80 is kept on even if the power of the machine tool 10 is turned off, the stored contents will not be lost. Further, in this embodiment, if the machine tool 10 connected via the interface 88 is changed, the total amount of thermal displacement for a plurality of machine tools 10 can be calculated by one personal computer 80.

As described above, the present invention has been described with reference to the embodiments. However, the present invention is not limited to the above embodiments, and can be implemented in various forms without departing from the gist of the present invention. . For example, in the above embodiment, the spindle 28
Of the machine tool 10 in the Z-axis direction is calculated from the Z-axis moving distance.
Thermal displacement occurs in 8 itself. Therefore, the rotation amount of the spindle motor 30 is calculated as a moving distance, and Z is calculated from the moving distance.
The axial thermal displacement may be calculated. In addition, the aforementioned total thermal displacement calculated by the processing of FIG. 5 or FIG.
The thermal displacement in the Z-axis direction of the entire machine tool 10 may be calculated by adding the thermal displacement calculated from the rotation of the main shaft 28. In this case, the amount of thermal displacement in the Z-axis direction can be calculated more accurately. Further, the present invention may be applied to a mechanism for moving the work W.

Further, the amount of thermal displacement of the machine tool 10 is affected by various conditions such as the moving distance of the main shaft 28 and the driving time. For example, when the air temperature is relatively low in the morning or the like, the temperature rise of the machine tool 10 becomes gentle, and the error between the calculated total thermal displacement and the actual thermal displacement may not be negligible. Therefore, for example, S16 in FIG. 5 may be changed as shown in FIG. 14 so that various adjustments can be made.

That is, in S61, the total thermal displacement is calculated as in S16. In subsequent S62, the CPU 72
It is determined whether it is necessary to adjust the total thermal displacement calculated in S61. This necessity determination is made by. The adjustment value is input via the operation panel 22,. There is an adjustment value set corresponding to the time. The determination is made based on whether or not a condition such as the necessity of using the adjustment value corresponding to the environmental temperature is satisfied. If the condition is satisfied, adjustment is necessary (S62: YE
In step S63, the adjustment value is adjusted by adding or subtracting the adjustment value to or from the total thermal displacement amount. On the other hand, no adjustment is required (S62: N
If it is O), the process proceeds to S3 (FIG. 4) or S31 (FIG. 10) while maintaining the total thermal displacement calculated in S61.

In this case, for example, if the adjustment value is determined in accordance with the time, according to the time period of the day (morning, noon, night, etc.),
An error between the calculated total thermal displacement and the actual thermal displacement can be automatically and better eliminated. Therefore, an accurate total thermal displacement amount can always be calculated regardless of the time. If the adjustment value is determined according to the environmental temperature of the machine tool 10, the calculated total thermal displacement and the actual thermal displacement are calculated according to the temperature at the place where the machine tool 10 is installed, that is, the environmental temperature. Can be automatically and better eliminated. Therefore, it is possible to always calculate the accurate total thermal displacement regardless of the environmental temperature. Note that S1 in FIG.
5, a similar effect is obtained even if S15 or S16a in FIG. 13 is changed in this way.

In each of the above embodiments, the tool T is brought into contact with the detector 49 to detect that the main shaft 28 has moved to a predetermined position, and based on the drive amount of the Z-axis control system 60 at that time, the heat is detected. Although the displacement amount is actually measured, various other configurations can be employed as the displacement amount measuring means.
For example, the main shaft 28 may be brought into direct contact with the detector 49 without using the tool T, or the main shaft 28 may be photographed from the side, and the thermal displacement may be measured by image processing or the like. However, if the configuration using the detector 49 of the above embodiment is adopted, the detector 4
The machine tool 10 has a simple configuration in which the
The accurate value of the thermal displacement amount can be automatically and easily measured. Therefore, the configuration of the apparatus can be simplified, the manufacturing cost can be reduced, and the parameters can be calculated more accurately and easily.

Further, various forms of the thermal displacement calculation processing are conceivable. For example, the thermal displacement may be calculated by a process not using the maximum displacement L. In addition, various processes for determining the necessity of actual measurement can be considered in addition to the above. For example, the operation state of the operation panel 22 may be read and determined, and the actual measurement may be necessary when the total drive time of the machine tool 10 has reached a predetermined time and a temporal change may have occurred. Good. However, in each of the above embodiments, the machining program and N
The necessity of the actual measurement is determined depending on whether the C data or the like corresponds to precision processing. Therefore, the necessity of the actual measurement can be determined very appropriately and automatically. Therefore, there is an effect that the balance between the calculation accuracy of the thermal displacement amount of the machine tool 10 and the work efficiency can be set very appropriately and automatically according to a machining program or the like.

As described above, when the thermal displacement is calculated by the processing of FIG. 10, the calculation of the thermal displacement with more importance on the calculation accuracy is performed, and when the thermal displacement is calculated by the processing of FIG. The calculation of the thermal displacement amount with more emphasis on the working efficiency of the machine 10 can be performed. Therefore, S3
When it is determined that precision processing is necessary (YES) in the processing of step 7, it is determined whether ultra-high precision processing with extremely high precision is necessary or normal precision processing is sufficient. In the former case, the processing proceeds to S41 and subsequent steps. In the case of, S is performed via S4 to S9 in FIG.
39 (if S4 is negative, the process immediately proceeds to S39). In this case, the balance between the calculation accuracy of the thermal displacement amount and the work efficiency can be set more appropriately and automatically according to the machining program or the like.

Further, in each of the above embodiments, a program for executing the processing of FIG. 4, FIG. 5, FIG. 10, FIG. 11, FIG.
M, but it goes without saying that these programs may be stored in a storage medium such as a floppy disk or CD-ROM. In this case, an arbitrary control means such as a general computer can execute the above processing.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration of a detector of a machine tool according to an embodiment.

FIG. 2 is a block diagram illustrating a configuration of a control system of the machine tool according to the first embodiment.

FIG. 3 is an explanatory diagram illustrating a configuration of a pitch error correction table of the machine tool.

FIG. 4 is a flowchart illustrating a main routine of a process executed by a CPU of the machine tool.

FIG. 5 is a flowchart illustrating a thermal displacement amount calculation process in the process.

FIG. 6 is an explanatory diagram showing a configuration of a map used for calculating a maximum displacement amount.

FIG. 7 is an explanatory diagram exemplifying a temporal change of a thermal displacement amount corresponding to a maximum displacement amount.

FIG. 8 is an explanatory diagram illustrating a process of calculating a total thermal displacement amount from a thermal displacement amount.

FIG. 9 is an explanatory diagram exemplifying correction of a thermal displacement amount based on an actually measured value.

FIG. 10 is a flowchart showing another form of the main routine.

FIG. 11 is a flowchart showing a part of the processing in detail.

FIG. 12 is a block diagram illustrating a configuration of a control system of a machine tool according to a second embodiment.

FIG. 13 is a flowchart illustrating a thermal displacement amount calculation process executed by a personal computer connected to the machine tool.

FIG. 14 is a flowchart illustrating still another form of the thermal displacement amount calculation process.

FIG. 15 is an explanatory diagram illustrating a configuration of a machine tool according to an embodiment and a conventional example.

FIG. 16 is an explanatory diagram illustrating a configuration of a machine tool according to an embodiment and a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Machine tool 14 ... Table 16 ... ATC magazine 20 ... Main body 28 ... Spindle 30 ... Spindle motor 36 ... Ball screw mechanism 38 ... Z-axis motor 49 ... Detector 60 ... Z-axis control system 70 ... Microcomputer part 72, 82 ... CPU 7
4, 84 RAM 76, 86 Clock 80 PC

Claims (6)

[Claims] 1. A machine tool having machining means for machining a workpiece and driving means for changing a relative position between the machining means and the workpiece, wherein a thermal displacement amount of the machine tool is provided. A drive state detection means for detecting a drive state of the machine tool, and a thermal displacement amount of the machine tool based on the drive state detected by the drive state detection means. Calculating means for calculating the amount of thermal displacement of the machine tool; measuring means for measuring the amount of thermal displacement of the machine tool; determining means for determining whether it is necessary to measure the amount of thermal displacement by the means for measuring the amount of thermal displacement; When it is determined that the actual measurement is unnecessary, the thermal displacement calculated by the displacement calculator is selected as the thermal displacement of the machine tool, and when the determiner determines that the actual measurement is necessary, Above displacement as thermal displacement Selecting means for selecting a thermal displacement amount actually measured by the measuring means, wherein the displacement measuring means does not perform the actual measurement when the determining means determines that the actual measurement is unnecessary. Thermal displacement calculator. 2. A machine tool having machining means for machining a workpiece and driving means for changing a relative position between the machining means and the workpiece, wherein a thermal displacement amount of the machine tool is provided. A drive state detection means for detecting a drive state of the machine tool, and a thermal displacement amount of the machine tool based on the drive state detected by the drive state detection means. A displacement amount calculating means for calculating the thermal displacement amount of the machine tool, a thermal displacement amount actually measured by the displacement amount measuring means, and a thermal displacement amount calculated by the displacement amount calculating means. A correction value calculating unit that calculates a correction value for the thermal displacement amount calculated by the displacement amount calculating unit; a determining unit that determines whether the thermal displacement amount is actually measured by the displacement amount measuring unit; The judgment means judges that the above actual measurement is unnecessary Then, the thermal displacement calculated by the displacement calculating means is selected as the thermal displacement of the machine tool, and when the determination means determines that the actual measurement is necessary, the thermal displacement of the machine tool is determined as the thermal displacement of the machine tool. Selecting means for selecting a value obtained by correcting the thermal displacement amount calculated by the amount calculating means with the correction value. The apparatus for calculating a thermal displacement of a machine tool, wherein the correction value is not calculated and the correction value is not calculated by the correction value calculating means. 3. A precision machining judging means for judging whether or not a machining program for controlling the machine tool corresponds to precision machining, further comprising a precision machining judging means based on a judgment result of the precision machining judging means. 3. The apparatus according to claim 1, wherein the means determines that the actual measurement is necessary when the machining program corresponds to precision machining, and determines that the actual measurement is unnecessary when the machining program does not correspond to precision machining. An apparatus for calculating a thermal displacement of a machine tool according to any one of the preceding claims. 4. The apparatus according to claim 1, wherein the displacement amount measuring means controls the driving means when the processing means relatively moves to a predetermined position with respect to the workpiece. And a processing means moving means for relatively moving the processing means to a position detected by the processing means detection means. The processing means moving means relatively moves the processing means to a position detected by the processing means detection means. The driving amount of the driving means required to cause the driving is compared with the driving amount required when no thermal displacement occurs in the machine tool, and the thermal displacement amount is measured based on the comparison result. The apparatus for calculating a thermal displacement of a machine tool according to any one of claims 1 to 3, wherein: 5. A processing means for processing a workpiece, a driving means for changing a relative position between the processing means and the workpiece, and a displacement for measuring a thermal displacement generated by driving the driving means. And a computer-readable storage medium storing a computer program for calculating a thermal displacement amount of the machine tool, wherein the drive state detection detects a drive state of the machine tool. Processing, based on the driving state detected in the driving state detection processing,
A displacement amount calculation process for calculating the thermal displacement amount of the machine tool; a displacement amount measurement process for actually measuring the thermal displacement amount via the displacement amount measurement means; and an actual measurement of the thermal displacement amount by the displacement amount measurement process. A judgment process for judging the necessity, and when it is judged that the actual measurement is unnecessary in the judgment process, the heat displacement amount calculated in the displacement amount calculation process is selected as the heat displacement amount of the machine tool; When it is determined in the determination process that the actual measurement is required, a selection process of selecting the thermal displacement amount actually measured in the displacement actual measurement process as the thermal displacement amount of the machine tool is stored. In addition, when it is determined that the actual measurement is unnecessary in the above determination processing,
A storage medium set so as not to perform the actual displacement amount measurement processing. 6. A processing means for processing a workpiece, a driving means for changing a relative position between the processing means and the workpiece, and a displacement for measuring a thermal displacement generated by driving the driving means. And a computer-readable storage medium storing a computer program for calculating a thermal displacement amount of the machine tool, wherein the drive state detection detects a drive state of the machine tool. Processing, based on the driving state detected in the driving state detection processing,
A displacement calculating process for calculating the thermal displacement of the machine tool; a displacement measuring process for measuring the thermal displacement via the displacement measuring device; and a thermal displacement actually measured in the displacement measuring process. And a correction value calculation process of comparing the thermal displacement amount calculated in the displacement amount calculation process to calculate a correction value for the thermal displacement amount calculated in the displacement amount calculation process; A determination process for determining whether or not the actual measurement of the thermal displacement amount is necessary, and when it is determined in the determination process that the actual measurement is unnecessary, the thermal displacement amount of the machine tool is calculated in the displacement amount calculating process. When the thermal displacement is selected and the actual measurement is determined to be necessary in the determination process, the thermal displacement calculated in the displacement calculating process is corrected by the correction value as the thermal displacement of the machine tool. Execute the selection process to select the selected value and Stores the computer program to, when the actually measured is determined to be unnecessary in the determination process,
A storage medium set so as not to perform the displacement actual measurement processing and the correction value calculation processing.