KR102675793B1 - Apparatus and method for compensating spindle of machine tool - Google Patents

Abstract

The present invention is based on the change in the amount of thermal displacement at the current position and current time through repeated measurement of the error between the data stored in the position data storage unit and the temperature data storage unit and the transport coordinates input through the input unit according to the measurement cycle of the timer. By deriving a calculation formula according to the kinematic error relationship and performing compensation by calculating compensation values according to the derived calculation formula, not only the linear deformation of the machine tool at the current time and location but also the non-linear deformation of the machine tool is taken into consideration. This relates to a spindle correction device and correction method for machine tools that can improve the processing precision of machine tools, maximize reliability and stability, and increase consumer satisfaction by improving productivity and quality.

Description

Spindle compensating device and method for compensating spindle of machine tool {Apparatus and method for compensating spindle of machine tool}

The present invention relates to a spindle correction device and correction method for a machine tool. More specifically, the present invention relates to a spindle correction device and a correction method for a machine tool, and more specifically, to compensate for non-linear deformation by reflecting the current position of the spindle and the current thermal displacement amount of the structure of the machine tool and the spindle. This relates to a spindle compensation device and compensation method for machine tools that can improve processing precision.

In general, machine tools refer to machines used to process metal/non-metal workpieces into desired shapes and dimensions using appropriate tools using various cutting or non-cutting processing methods.

Various types of machine tools, including turning centers, vertical/horizontal machining centers, door machining centers, Swiss turns, electric discharge machines, horizontal NC boring machines, and CNC lathes, are widely used in various industrial fields to suit the purpose of the work.

In general, various types of machine tools currently in use are equipped with an operating panel to which numerical control (NC) or computerized numerical control (CNC) technology is applied. This operating panel is equipped with various function switches or buttons and a monitor.

In addition, a machine tool includes a table on which the workpiece material is seated and transported for processing the workpiece, a pallet to prepare the workpiece before processing, a spindle on which the tool or workpiece is combined and rotated, a tailstock to support the workpiece, etc. during processing, and an anti-vibration tool. Equipped with etc.

In general, in machine tools, tables, tool rests, spindles, tailstocks, dust rests, etc. are equipped with transfer units that transfer along a transfer axis to perform various machining.

Additionally, machine tools generally use multiple tools for various processing, and a tool magazine or turret is used as a tool storage location to store and store multiple tools.

These machine tools use multiple tools for various processing, and a tool magazine is used as a tool storage location to store and store multiple tools.

In addition, machine tools are generally equipped with an automatic tool changer (ATC) for withdrawing or storing a specific tool from a tool magazine according to a command from a numerical control unit in order to improve the productivity of the machine tool.

Additionally, machine tools are generally equipped with an automatic pallet changer (APC) to minimize non-processing time. The automatic pallet changer (APC) automatically exchanges pallets between the workpiece machining area and the workpiece installation area. A workpiece can be mounted on a pallet.

In general, machine tools generate thermal displacement due to temperature changes in structures such as the spindle, bed, column, and saddle due to internal heat generated during processing and external environmental factors. This thermal displacement causes linear behavior, resulting in position error. occurs.

In addition, thermal displacement causes non-linear thermal behavior due to an imbalance between top and bottom or left and right temperatures and is accompanied by angular error.

In other words, if the temperature of the main axis and structure of the machine tool rises uniformly throughout, the accuracy of the main axis compensation of the machine tool can be increased through linear behavior, but the difference in heat capacity of the machine tool structures such as the bed, column, and saddle may increase. Due to the difference in time constant, temperature gradients occur between the top and bottom, left and right, and inside and outside of each structure, resulting in nonlinear behavior such as bending or twisting.

However, although non-linear behavior can occur in any direction depending on temperature distribution, the spindle compensation device and compensation method of conventional machine tools measures the displacement of each axis only at one point and reflects the angular error due to non-linear behavior. There was a problem that correction could not be performed precisely.

In addition, the spindle compensation device and compensation method of a conventional machine tool is judged through measurement only at a single point rather than the entire machining area, so even in the case of non-linear behavior, is it local deformation of the tip of the tool or the body or body of the spindle head? There was a problem in that processing precision was reduced as accurate correction could not be performed as it was impossible to distinguish whether it was a non-linear deformation such as bending or twisting of the column.

Moreover, the spindle compensation device and compensation method of the conventional machine tool corrects without considering the correlation between non-linear deformation and linear deformation due to thermal displacement at a specific point in time and at a specific location, thereby significantly reducing accuracy and reliability, and the final There was a problem that the processing quality deteriorated.

Republic of Korea Patent Publication No. 10-2011-0026024 Republic of Korea Patent Publication No. 10-2015-0073727

The present invention is to solve the above problems, and the purpose of the present invention is to repeatedly measure the error between the data stored in the position data storage unit and the temperature data storage unit and the transport coordinates input through the input unit according to the measurement cycle of the timer. Through this, a calculation formula is derived according to the kinematic error relationship according to the change in the amount of thermal displacement at the current position and current time, and the compensation value is calculated according to the derived calculation formula to perform compensation, thereby determining the A machine tool that can improve the processing precision of the machine tool, maximize reliability and stability, and increase consumer satisfaction by improving productivity and quality by compensating the main axis of the machine tool by considering not only linear deformation but also non-linear deformation. To provide a spindle correction device and correction method.

In order to achieve the purpose of the present invention, the spindle correction device for a machine tool according to the present invention includes a spindle on which a tool is installed; A table on which the workpiece is placed; One or more fixtures installed on the upper surface of the table; a position measuring unit mounted on the main axis and measuring the center position of the jig; a temperature measuring unit installed on the bed, column, saddle, spindle, and table to measure temperature in real time; a numerical control unit that stores data measured through the position measurement unit and the temperature measurement unit and inputs transfer coordinates of the main axis; and a correction amount control unit that corrects non-linear deformation by reflecting the current position of the spindle, the structure of the machine tool, and the current amount of thermal displacement of the spindle.

In addition, in another preferred embodiment of the spindle compensation device for a machine tool according to the present invention, the numerical control unit of the spindle compensation device for a machine tool includes an input unit for inputting transfer coordinates of the spindle while the position measuring unit is coupled to the spindle; a location data storage unit that stores location data measured by the location measurement unit; a temperature data storage unit that stores temperature data measured by the temperature measurement unit; and a timer for setting measurement cycles of the position measuring unit and the temperature measuring unit.

In addition, in another preferred embodiment of the spindle compensation device for a machine tool according to the present invention, the correction amount control unit of the spindle compensation device for a machine tool includes a basic data storage unit that stores the length and maximum correction amount of each jig; Depending on the measurement cycle of the timer, the error between the data stored in the position data storage unit and the temperature data storage unit and the transfer coordinates input through the input unit is repeatedly measured to determine the change in the amount of thermal displacement at the current location and current time. a calculation unit that calculates the kinematic error relationship; a correction value calculation unit that calculates a correction value according to the error relationship derived by the calculation unit; a comparison unit that compares the correction value of the correction value calculation unit with the maximum correction amount stored in the basic data storage unit; and a correction unit that corrects an error in the main axis by the correction value when, as a result of the comparison of the comparison unit, the correction value is less than or equal to the maximum correction amount.

In addition, in another preferred embodiment of the spindle compensation device for a machine tool according to the present invention, the calculation unit of the correction amount control unit of the spindle compensation device for a machine tool calculates the angle error and position error due to the change in the amount of thermal displacement at the current position and a specific time. The mathematical expression for the relationship can be derived by regression analysis or least squares.

In addition, in another preferred embodiment of the spindle compensating device for a machine tool according to the present invention, the spindle compensating device for a machine tool has three jigs of different lengths on the upper surface of the table when the machine tool is formed in three axes. More than one can be installed.

In addition, in another preferred embodiment of the spindle compensating device for a machine tool according to the present invention, when the machine tool of the spindle compensating device for a machine tool is formed in 5 axes, one jig having a bending portion is provided on the upper surface of the table. It can be installed more than once.

In order to achieve another object of the present invention, the spindle correction method of a machine tool according to the present invention includes a setup step of installing one or more fixtures on the upper surface of a table and mounting a position measuring unit on the spindle; storing basic data in a basic data storage; Setting the measurement cycle of the timer; Inputting transfer coordinates through an input unit; Measuring the center position of each fixture multiple times according to a measurement cycle and storing the position data in a position data storage unit; When processing a workpiece, measuring the temperature of the current structure multiple times according to the measurement cycle and storing the temperature data in a temperature data storage unit; The amount of thermal displacement at the current position and current time is determined through repeated measurement of the error between the plurality of data stored in the position data storage unit and the temperature data storage unit and the transport coordinates input through the input unit according to the measurement cycle of the timer. Calculating a kinematic error relationship according to change; calculating a correction value through the error relationship derived in the calculating step; Comparing the correction value with a maximum correction amount stored in the basic data storage; and if the correction value is less than or equal to the maximum correction amount as a result of comparison, correcting the error of the main axis by the correction value.

In addition, in another preferred embodiment of the spindle correction method of a machine tool according to the present invention, the calculating step is based on the relationship between the angle error and the position error due to the change in the amount of thermal displacement at the current position. The mathematical equation can be derived by regression analysis or least squares.

The spindle correction device and correction method for a machine tool according to the present invention are based on the measurement cycle of the timer by repeatedly measuring the error between the data stored in the position data storage unit and the temperature data storage unit and the transfer coordinates input through the input unit. By deriving a calculation formula according to the kinematic error relationship according to the change in the amount of thermal displacement at the current time and performing correction by calculating a correction value according to the derived calculation formula, not only the linear deformation of the machine tool at the current time and position is performed. In addition, the machining precision of the machine tool can be improved by compensating the main axis of the machine tool by considering non-linear deformation.

In addition, the spindle compensation device and compensation method for machine tools according to the present invention have the effect of maximizing the reliability and stability of machine tools by improving processing precision.

Moreover, the spindle compensation device and compensation method for machine tools according to the present invention has the effect of improving processing quality by improving processing precision, thereby improving consumer satisfaction and reducing processing costs by minimizing waste of workpieces.

In addition, the spindle correction device and correction method for machine tools according to the present invention have the effect of saving resources by preventing workpiece waste and increasing productivity by reducing non-processing time of machine tools by improving processing precision.

Figure 1 shows a conceptual diagram of a spindle compensation device for a machine tool with three axes according to an embodiment of the present invention.
Figure 2 shows a conceptual diagram of a spindle compensation device for a machine tool with 5 axes according to an embodiment of the present invention.
Figure 3 shows some details of Figure 1.
Figure 4 shows some details of Figure 2.
Figure 5 is a graph for explaining the process of setting the measurement cycle of the timer of the spindle compensation device of a machine tool according to an embodiment of the present invention.
Figure 6 is a block diagram showing the configuration of a spindle compensation device for a machine tool according to an embodiment of the present invention.
Figure 7 shows a procedure diagram of a spindle correction method for a machine tool according to an embodiment of the present invention.
Figure 8 is a graph of the change in YZ perpendicularity according to temperature change according to the spindle correction device and correction method of the machine tool according to the present invention.
Figure 9 is a graph of the change in kinematic error measurement value for long-term temperature changes according to the spindle compensation device and compensation method of the machine tool according to the present invention.

Hereinafter, the prefabricated pillow according to an embodiment of the present invention will be described in detail with reference to the drawings. The embodiments introduced below are provided as examples so that the idea of the present invention can be sufficiently conveyed to those skilled in the art. Accordingly, the present invention is not limited to the embodiments described below and may be embodied in other forms. Also, in the drawings, the size and thickness of the device may be exaggerated for convenience. Like reference numerals refer to like elements throughout the specification.

The advantages and features of the present invention and methods for achieving them will become clear by referring to the embodiments described in detail below along with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and will be implemented in various different forms. These embodiments only serve to ensure that the disclosure of the present invention is complete and that common knowledge in the technical field to which the present invention pertains is provided. It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification. The sizes and relative sizes of layers and regions in the drawings may be exaggerated for clarity of explanation.

The terminology used herein is for describing embodiments and is therefore not intended to limit the invention. As used herein, singular forms also include plural forms, unless specifically stated otherwise in the context. As used in the specification, “comprise” and/or “comprising” refers to the presence of one or more other components, steps, operations and/or elements. or does not rule out addition.

Figure 1 shows a conceptual diagram of a spindle correction device for a machine tool with 3 axes according to an embodiment of the present invention, and Figure 2 is a conceptual diagram of a spindle correction device for a machine tool with 5 axes according to an embodiment of the present invention. , FIG. 3 shows a partial detailed view of FIG. 1, and FIG. 4 shows a partial detailed view of FIG. 2. Figure 5 is a graph for explaining the process of setting the measurement cycle of the timer of the spindle compensation device of a machine tool according to an embodiment of the present invention, and Figure 6 is a graph of the spindle compensation device of a machine tool according to an embodiment of the present invention. It is a block diagram showing the configuration, and Figure 7 shows a procedure diagram of the spindle correction method of a machine tool according to an embodiment of the present invention. Figure 8 is a graph of the change in YZ perpendicularity according to temperature change according to the spindle correction device and correction method of the machine tool according to the present invention, and Figure 9 is a graph of the change in YZ perpendicularity according to the spindle correction device and correction method of the machine tool according to the present invention. This is a graph of the change in kinematic error measurement value in response to temperature change.

Referring to FIGS. 1 to 6, a spindle compensation device 1 for a machine tool according to an embodiment of the present invention will be described. As shown in Figures 1 to 6, the spindle correction device 1 for a machine tool according to an embodiment of the present invention includes a spindle 10, a table 20, a jig 30, a position measuring unit 40, It includes a temperature measurement unit 50, a numerical control unit 60, and a correction amount control unit 70.

In general, machine tools include a bed (2) installed on the ground, a column (3) installed on a part of the bed (2), and saddles (4) that are movable along the column (3) or fixed to the column (3). ) includes.

A tool is installed on the main axis 10. As shown in the drawing, this main shaft 10 can be installed on the saddle 4 to be movable up and down on the spindle body.

The bed (2), column (3), saddle (4), spindle body, etc. are all elements that make up the structure of the machine tool and have different heat capacities.

The table 20 is installed on the bed 2 to enable linear transfer and/or rotation. The workpiece is seated on the upper surface of the table 20.

Although not shown in the drawing, the main shaft 10 and the table 20 are moved by the transfer unit. Although not necessarily limited to this, the rotation shaft transfer unit is formed of a motor or a servo motor (SERVO MOTOR), and the driving is controlled by a numerical control unit 60, a correction amount control unit 70, or a PLC, which will be described later.

One or more fixtures 30 are installed on the upper surface of the table 20. Although not necessarily limited to this, the jig 30 is formed as a datum ball.

As shown in Figures 1 and 3, when the machine tool is formed in three axes (X-axis, Y-axis, Z-axis), the jig 30 of different lengths is attached to the upper surface of the table 20. 3 or more are installed. Preferably, when the machine tool is formed in three axes, four jigs 30 of different lengths are installed at random positions on the upper surface of the table 20. Accordingly, six error components can be extracted. When a machine tool is formed as a 3-axis equipment, each axis (X-axis, Y-axis, Z-axis) has one position error and one direction error. Accordingly, the kinematic error of the 3-axis equipment is defined as a total of 6 error components and consists of 3 position error components and 3 direction error components, and these 6 error components are divided into the jig 30 of different lengths. It can be derived by repeated measurements.

Position error refers to how far the origin of each coordinate axis (X-axis, Y-axis, Z-axis) is from the ideal coordinate axis in each coordinate axis direction, and angular error refers to the degree to which each axis of the machine tool is not parallel or perpendicular to each other. do.

As shown in Figures 2 and 4, when the machine tool is formed with 5 axes (X-axis, Y-axis, Z-axis, C-axis, A-axis), the jig 30 with the bent portion 31 is attached to the table. One or more are installed on the upper surface. Preferably, when the machine tool is formed in 5 axes, one jig 30 having a bent portion 31 on the upper surface of the table 20 is installed. In the case of 5-axis equipment, since the table 20 can rotate along the C-axis, measurements can be made at multiple points in space using the rotary table 20, reducing 10 or 11 kinematic errors with just one fixture 30. components can be derived. At this time, the 10 error components consist of 4 position errors and 6 direction errors.

The position measuring unit 40 is mounted on the main axis 10 when correcting the main axis of the machine tool, and measures the center position of each jig 30 installed on the upper surface of the table 20. At this time, the position measurement unit 40 measures multiple times according to the measurement cycle stored in the timer 64 of the numerical control unit 60, which will be described later, and transmits the measured position data to the numerical control unit 60. Although not necessarily limited to this, the position measuring unit 40 may be formed as a touch probe to quickly measure the center position of the fixture and transmit it to the numerical control unit 60.

A plurality of temperature measuring units 50 are installed on the inside or outside of the bed 2, column 3, saddle 4, spindle 10, and/or table 20 and measure the structure of the machine tool in real time. Measure the temperature. At this time, the temperature measuring unit 50 measures multiple times according to the measurement cycle stored in the timer 64 of the numerical control unit 60, which will be described later, and transmits the measured temperature data to the numerical control unit 60. Although not necessarily limited to this, the temperature measuring unit 40 may be formed as a temperature sensor to quickly measure the temperature at a specific point and time of each structure of the machine tool and transmit this to the numerical control unit 60. .

The numerical control unit 60 stores the position data and temperature data measured through the position measurement unit 40 and the temperature measurement unit 50, and inputs the transfer coordinates of the main axis 10. In addition, the numerical control unit 100 includes a numerical control (NC) or computerized numerical control (CNC) and has various numerical control programs built in. That is, the numerical control unit 50 has a built-in drive program for the linear axis drive unit and the rotary shaft drive unit, a tool operation program, etc., and the corresponding program is automatically loaded and operated according to the operation of the numerical control unit. This numerical control unit 60 communicates with the manipulation unit 80, the display unit 90, the correction amount control unit 70, and the PLC using a predetermined protocol.

The correction amount control unit 70 corrects the non-linear deformation by reflecting the current position of the main axis 10 and the current thermal displacement amount of the structure of the machine tool and the main axis 10.

Therefore, the spindle compensation device for a machine tool according to the present invention determines the current position and By deriving a calculation formula according to the kinematic error relationship according to the change in the amount of thermal displacement at the current point in time, and performing correction by calculating a correction value according to the derived calculation formula, not only the linear deformation of the machine tool at the current time and position, but also the The machining precision of the machine tool can be improved by compensating the main axis of the machine tool, taking into account nonlinear deformation.

In addition, as shown in FIGS. 1 to 2 and 6, the spindle compensation device 1 for a machine tool according to another embodiment of the present invention may further include a manipulation unit 80 and a display unit 90.

The operating unit 80 is installed in the form of a switch or touch button on an operating panel, etc., and performs a spindle correction function during operation of the machine tool.

That is, the operator sets up the jig and the position measurement unit using the operation unit 80, repeatedly measures the kinematic error at the current time and current position with the position measurement unit and the temperature measurement unit, and determines the kinematic error relationship according to the change in thermal displacement. By deriving a calculation formula according to , you can arbitrarily select a function that performs correction by calculating a correction value according to the derived calculation formula. If the spindle compensation function of the machine tool is not selected on the control panel 80, the spindle compensation function of the machine tool will not operate.

In this way, through a simple operation of the control panel, a calculation formula according to the kinematic error relationship according to the change in thermal displacement is derived, and the compensation value is calculated and corrected according to the derived calculation formula, so that processing precision can be arbitrarily selected according to the processing that is required. By reducing processing time, productivity can be improved and processing precision can be increased to maximize reliability and safety.

The display unit 90 displays correction values, comparison values, position data, temperature data, etc. by the numerical control unit 60 and the correction value control unit 70. Accordingly, the operator can visually monitor the precision of the machine tool at a specific time and location during processing in real time and check the correction value in real time.

In addition, the display unit 90 displays an alarm when the correction value calculated by the correction value calculation unit 73 as a result of the judgment of the comparison unit 47, which will be described later, exceeds the maximum correction value stored in the basic data storage unit 71. By notifying the operator of machine tool abnormalities, maintenance of the machine tool can be facilitated and damage to the workpiece can be minimized. At this time, the alarm may be displayed in the form of a monitor, warning sound, or warning light.

Although not necessarily limited to this, the display unit 90 may be composed of an LCD, LED, PDP monitor, etc.

As shown in FIG. 6, the numerical control unit 60 of the spindle compensation device 1 of a machine tool according to an embodiment of the present invention includes an input unit 61, a position data storage unit 62, and a temperature data storage unit 63. ), and a timer 64.

The input unit 61 functions to input the transfer coordinates of the main axis 10 while the position measuring unit 40 is coupled to the main axis 10. That is, the input unit 10 inputs transfer coordinates, which are command coordinates, and the input transfer coordinates are transmitted to the PLC and the numerical control unit 60 to drive the transfer unit to drive the main axis 10 along the X, Y, and Z axes. .

The position data storage unit 62 stores center position data including errors of one or more fixtures 30 installed on the upper surface of the table 20 by the position measurement unit 40.

The temperature data storage unit 63 stores data at a specific point in time of a plurality of temperature measuring units 50 installed on the bed 2, column 3, saddle 4, main shaft 10, and/or table 20. Save temperature data.

The timer 64 is set to the measurement cycle of the position measurement unit 62 and the temperature measurement unit 63. That is, as shown in FIG. 5, the center position of the jig 30 and the temperature of the structure of the machine tool are repeatedly measured by the position measuring unit 62 and the temperature measuring unit 63 at a specific time, and the measurements are stored and updated. do. The measurement cycle of the timer 64 can be automatically set to the optimal measurement cycle according to repeated measurements, or can be manually specified by the operator through operation of the PLC or the operation panel of the numerical control unit 60.

The spindle compensation device for machine tools according to the present invention can maximize the reliability and stability of machine tools by improving processing precision.

As shown in Figure 6, the correction amount control unit 70 of the spindle compensation device 1 of a machine tool according to an embodiment of the present invention includes a basic data storage unit 71, a calculation unit 72, and a correction value calculation unit ( 73), a comparison unit 74, and a correction unit 75.

The basic data storage unit 71 stores the length of each jig 30 installed on the upper surface of the table 20 and the maximum correction amount at a specific time.

The calculation unit 72 calculates the position data and the current point in time about the center position of the jig 30 stored in the position data storage unit 62 and the temperature data storage unit 63 at the current position according to the measurement cycle of the timer 64. Between the temperature data of each structure such as the bed (2), column (3), saddle (4), main shaft (10), and/or table (20) of the machine tool and the transfer coordinates input through the input unit (61) Through repeated measurement of the error, the kinematic error relationship according to the current position and the change in thermal displacement at the current point is obtained. Although not necessarily limited to this, the calculation unit 72 derives a mathematical equation for the relationship between the angle error and the position error due to the change in the amount of thermal displacement at the current position and a specific time using regression analysis or the least squares method.

The correction value calculation unit 73 calculates the correction value according to the error relationship derived by the calculation unit 72, that is, a calculation formula (mathematical formula) derived by regression analysis or the least squares method.

The comparison unit 74 compares the correction value of the correction value calculation unit 73 with the maximum correction amount stored in the basic data storage unit 71.

As a result of the comparison of the comparator 74, the correction unit 75 corrects the error of the main axis 10 by the correction value when the correction value is less than or equal to the maximum correction amount (correction value ≤ maximum correction amount), and the correction value is the maximum correction amount. If it is greater than the correction amount (correction value > maximum correction amount), an alarm is generated by the display unit 90.

The spindle correction device for a machine tool according to the present invention calculates the correction value of the spindle based on the relationship between thermal displacement and kinematic error according to the current position and current time, and performs correction by comparing this correction value with the maximum correction value. Accordingly, the stability and reliability of machine tools can be maximized, processing quality can be improved by improving processing precision, improving consumer satisfaction, and processing costs can be reduced by minimizing waste of workpieces.

3 to 5, the current position of the calculation unit 73 of the correction value control unit 70 of the spindle compensation device 1 of a machine tool according to an embodiment of the present invention and the change in the amount of thermal displacement at the current time. The principle of obtaining the kinematic error relationship according to is explained.

As shown in Figure 3, when the machine tool is a 3-axis equipment, three or more jigs 30 of different lengths are installed on the table 20.

The center position of each jig 30 is input through the input unit 61, and the position measuring unit 40 is mounted on the main axis 10 to measure the position of the jig 30. The center position data of the jig 30 measured by the position measurement unit 40 is stored in the position data storage unit 62 in real time.

Msr: Measured value of center position of fixture including error

Cmd: Transfer coordinate value entered through the input unit

x': X-axis measurement value, y': Y-axis measurement value, z': Z-axis measurement value

Mx: Commanded X-axis coordinate, My: Commanded Y-axis coordinate, Mz: Commanded Z-axis coordinate

Calculate the XY-axis error matrix and YZ-axis error matrix as follows.

ε _yx : XY-axis error matrix

ε _zy : YZ-axis error matrix

δ _x : Position error in the X-axis direction

δ _y : Position error in the Y-axis direction

δ _z : Position error in Z-axis direction

α _yx : YZ angle error

β _zy : XZ angle error

γ _yx : XY angle error

Equation (1)

Equation (2)

Δ (difference between measured value and command value): Msr-Cmd

Six error components at a specific point in time are calculated through regression analysis using equations (1) and (2) above. In other words, ΔX, ΔY, ΔZ, X, Y, and Z are all known values, and the six error components at a specific point in time can be obtained through regression analysis.

Equation (1)

Equation (1) is derived through regression analysis of the relationship between the temperature data at the current n locations and the three angle errors and three position error components according to each measurement time using equations (1) and (2). can do.

In this way, when the machine tool is a 3-axis equipment, the calculation unit 72 calculates equation (1), and the correction value calculation unit 73 calculates the correction value based on equation (1).

As shown in Figure 4, when the machine tool is a 5-axis equipment, one jig 30 equipped with a bending portion 31 is installed on the upper surface of the rotatable table 20.

The center position of the jig 30 is input through the input unit 61, and the position measuring unit 40 is mounted on the main axis 10 to measure the position of the jig 30. The center position data of the jig 30 measured by the position measurement unit 40 is stored in the position data storage unit 62 in real time.

Msr: Measured value of center position of fixture including error

Cmd: Transfer coordinate value entered through the input unit

x': X-axis measurement value, y': Y-axis measurement value, z': Z-axis measurement value

Mx: Commanded X-axis coordinate, My: Commanded Y-axis coordinate, Mz: Commanded Z-axis coordinate,

M _A : Commanded A-axis coordinate, Mc: Commanded C-axis coordinate

Calculate the XY-axis error matrix, YZ-axis error matrix, AC-axis error matrix, and AX-axis error matrix as follows.

ε _yx : XY-axis error matrix

ε _zy : YZ-axis error matrix

ε _CA : AC axis error matrix

ε _AX : AX-axis error matrix

δ _x : Position error in the X-axis direction

δ _y : Position error in the Y-axis direction

δ _z : Position error in Z-axis direction

_δXCA : AC X-axis direction position error

δ _YCA : AC Y-axis direction position error

δ _YAX : AX Y direction position error

δ _ZAX : AX Z direction position error

α _yx : YZ angle error

β _zy : XZ angle error

β _CA : AC angle error

β _AX : AX angle error

γ _yx : XY angle error

Equation (3)

Equation (4)

Δ (difference between measured value and command value): Msr-Cmd

Using error values obtained from multiple measurement locations, 10 error components at a specific time can be calculated through regression analysis using equations (3) and (4) above.

Equation (2)

Equation (2) is derived through regression analysis of the relationship between the temperature data at the current n locations and the three angle errors and three position error components according to each measurement time using equations (3) and (4). can do. Even if the machine tool is a 3-axis or 5-axis machine, it compensates for errors in the position of the tool tip by transferring the X, Y, and Z axes, which are all linear axes. It can be solved with a compensation formula, and calculating the minimum corrections in this way can improve the productivity of machine tools by minimizing the time required to calculate compensation values.

In this way, when the machine tool is a 3-axis equipment, the calculation unit 72 calculates equation (2), and the correction value calculation unit 73 calculates the correction value based on equation (1).

Therefore, a calculation formula is derived according to the kinematic error relationship according to the change in the amount of thermal displacement at the current position and current time, and the compensation value is calculated according to the derived calculation formula to perform correction, thereby performing correction. The machining precision of the machine tool can be improved by compensating the main axis of the machine tool by considering not only linear deformation but also non-linear deformation.

In other words, as shown in FIGS. 8 and 9, the angle change according to temperature is improved and the precision of the machine tool can be maximized by consistently converging to the correction value even if the error measurement value according to temperature is different.

Referring to FIG. 7, a method for correcting the spindle of a machine tool according to an embodiment of the present invention will be described. As shown in FIG. 7, the spindle correction method according to an embodiment of the present invention includes a setup step (S1), a basic data storage step (S2), a timer measurement cycle setting step (S3), a transfer coordinate input step (S4), It includes a position measurement and storage step (S5), a temperature measurement and storage step (S6), an error relationship calculation step (S7), a correction value calculation step (S8), a comparison step (S9), and a correction step (S10). Additionally, according to an embodiment of the present invention, a display step (S11) may be further included after the correction step (S10).

In order to perform the spindle correction method of the machine tool according to the present invention while the machine tool is in operation, one or more fixtures 30 are installed on the upper surface of the table 20, and the position measuring unit 40 is installed on the spindle 10. Install it. At this time, when the machine tool is a 3-axis equipment as shown in FIGS. 1 and 3, three or more jigs 30 of different lengths are installed at random intervals on the upper surface of the table 20, and as shown in FIGS. 2 and 4 and Similarly, when the machine tool is a 5-axis equipment, one jig 30 having a bent portion 31 is installed on the rotatable table 20.

After the setup step (S1), data on the length of each fixture and basic data on the maximum correction amount are stored in the basic data storage unit 71.

After the basic data storage step (S2), the measurement cycle of the timer 64 is set. The measurement cycle of the timer 64 can be manually set by the user through an operation panel, etc. In addition, the existing correction value and the measurement cycle of the timer are input according to repeated measurements, and the PLC calculates the optimal measurement cycle according to the size of the correction value and the operating status of the machine tool and automatically sets the measurement cycle. .

After the timer measurement cycle setting step (S3), the transfer coordinates of the main axis 10, that is, the command coordinates, are input through the input unit 61. At this time, if the table 20 has a plurality of fixtures 30 installed on the upper surface, the command coordinates are input multiple times, and in the case of a rotary table, the command coordinates are input as many times as measured. In addition, input coordinates, or command coordinates, can be automatically entered through a PLC, etc.

After the transfer coordinate input step (S4), the center position of each jig 30 or the center position of the jig at the current position of one jig 30 changes according to the rotation of the rotary table 20 using the timer 64. Measurements are made multiple times through the position measuring unit 40 according to the measurement cycle, and the position data is stored in the position data storage unit 62.

After the position measurement and storage step (S5), the temperature of the current structure is measured multiple times through a plurality of temperature measurement units 50 installed in each structure according to the measurement cycle of the timer 64, and the temperature data storage unit 63 Save the temperature data in .

After the temperature measurement and storage step (S6), the center position of the fixture including a plurality of error values stored in the position data storage unit 62 and the temperature data storage unit 63 according to the measurement cycle of the timer 64. The kinematic error relationship according to the change in the amount of thermal displacement at the current position and current time is calculated through repeated measurement of the error between the position data, the temperature data of the workpiece structure at the current time, and the transfer coordinates input through the input unit.

In the step of calculating the error relationship (S7), a mathematical equation for the relationship between the angle error and the position error due to the change in thermal displacement at the current position is derived by regression analysis or the least squares method. This derivation method is the same as the method described above and will be omitted hereinafter.

After the error relationship calculation step (S7), the correction value is calculated through the error relationship derived in the error relationship calculation step, that is, equation (1) for 3-axis equipment and equation (2) for 5-axis equipment. Calculate .

After the correction value calculation step (S8), the correction value is compared with the maximum correction amount stored in the basic data storage unit 71.

After the comparison step (S9), if the correction value as a result of comparison is less than or equal to the maximum correction amount, the error of the main axis is corrected by the correction value, and if the correction value as a result of comparison is greater than the maximum correction amount, an alarm is generated through the display unit 90. do.

Therefore, the main axis correction method of a machine tool according to the present invention is to determine the current position and By deriving a calculation formula according to the kinematic error relationship according to the change in the amount of thermal displacement at the current point in time, and performing correction by calculating a correction value according to the derived calculation formula, not only the linear deformation of the machine tool at the current time and position, but also the The machining precision of the machine tool can be improved by compensating the main axis of the machine tool, taking into account nonlinear deformation.

In addition, the main axis correction method of a machine tool according to the present invention calculates the correction value of the main axis based on the relationship between the amount of thermal displacement and kinematic error according to the current position and current time, and compensates by comparing this correction value with the maximum correction value. By performing this, the stability and reliability of machine tools can be maximized, processing quality can be improved by improving processing precision, thus improving consumer satisfaction, and processing costs can be reduced by minimizing workpiece waste.

Although the detailed description of the present invention described above has been described with reference to preferred embodiments of the present invention, those skilled in the art or those skilled in the art will understand the present invention as described in the patent claims to be described later. It will be understood that various modifications and changes can be made to the present invention without departing from the spirit and technical scope. Therefore, the technical scope of the present invention should not be limited to what is described in the detailed description of the specification, but should be defined by the scope of the claims.

1: Machine tool spindle compensation device, 2: Bed,
3: Column, 4: Birds,
10: spindle, 20: table,
30: jig, 31: bending part,
40: position measurement unit, 50: temperature measurement unit,
60: Numerical control unit, 61: Input unit,
62: location data storage unit, 63: temperature data storage unit,
64: Timer, 70: Correction amount control unit,
71: basic data storage unit, 72: calculation unit,
73: correction value calculation unit, 74: comparison unit,
75: correction unit, 80: control unit,
90: Display unit.

Claims (8)

Spindle on which the tool is installed;
A table on which the workpiece is placed;
One or more fixtures installed on the upper surface of the table;
a position measuring unit mounted on the main axis and measuring the center position of the jig;
A temperature measuring unit installed on the bed, column, saddle, spindle, and table to measure temperature in real time;
a numerical control unit that stores data measured through the position measurement unit and the temperature measurement unit and inputs transfer coordinates of the main axis; and
It includes a correction amount control unit that corrects the error of the main axis,
The numerical control unit,
an input unit that inputs transfer coordinates of the main axis while the position measuring unit is coupled to the main axis;
a location data storage unit that stores location data measured by the location measurement unit;
a temperature data storage unit that stores temperature data measured by the temperature measurement unit; and
It includes a timer that sets the measurement cycle of the position measuring unit and the temperature measuring unit,
The correction amount control unit reflects the current position of the main axis and the current thermal displacement amount of the structure of the machine tool and the main axis, not only linear deformation according to the position error of the structure of the machine tool, but also a time constant due to the difference in heat capacity of the structure of the machine tool. Due to differences in temperature gradients between the top and bottom, left and right, and inside and outside of the machine tool structure, non-linear deformation due to bending or twisting is reflected and corrected.
The correction amount control unit,
a basic data storage unit that stores the length and maximum correction amount of each fixture;
According to the measurement cycle of the timer, position data about the center position of the fixture stored in the position data storage unit at the current position, temperature data of the machine tool structure stored in the temperature data storage unit at the current point, and input through the input unit. A calculation unit that obtains a kinematic error relationship according to the change in thermal displacement at the current position and current time through repeated measurement of the error between transfer coordinates;
a correction value calculation unit that calculates a correction value according to the error relationship derived by the calculation unit;
a comparison unit that compares the correction value of the correction value calculation unit with the maximum correction amount stored in the basic data storage unit; and
As a result of the comparison of the comparison unit, if the correction value is less than or equal to the maximum correction amount, the error of the main axis is corrected by the correction value, and if the correction value is greater than the maximum correction amount, a correction unit that generates an alarm. do,
The main axis of the machine tool is characterized in that the calculation unit derives the equation for the relationship between the angle error and the position error due to the change in the amount of thermal displacement at the current position and a specific time through equation (2) below through regression analysis. Compensation device.
Equation (2)

delete delete delete According to paragraph 1,
A spindle compensation device for a machine tool, wherein when the machine tool is formed with three axes, three or more jigs of different lengths are installed on the upper surface of the table.
According to paragraph 1,
A spindle correction device for a machine tool, characterized in that when the machine tool is formed with five axes, one or more jigs having bends are installed on the upper surface of the table.
A setup step of installing one or more fixtures on the upper surface of the table and mounting the position measurement unit on the main axis;
storing basic data in a basic data storage;
Setting the measurement cycle of the timer;
Inputting transfer coordinates through an input unit;
Measuring the center position of each fixture multiple times according to a measurement cycle and storing the position data in a position data storage unit;
When processing a workpiece, measuring the temperature of the current structure multiple times according to the measurement cycle and storing the temperature data in a temperature data storage unit;
The amount of thermal displacement at the current position and current time is determined through repeated measurement of the error between the plurality of data stored in the position data storage unit and the temperature data storage unit and the transport coordinates input through the input unit according to the measurement cycle of the timer. Calculating a kinematic error relationship according to change;
calculating a correction value through the error relationship derived in the calculating step;
Comparing the correction value with a maximum correction amount stored in the basic data storage; and
Comprising: if the correction value is less than or equal to the maximum correction amount as a result of the comparison, correcting the error of the main axis by the correction value,
The step of calculating the kinematic error relationship according to the change in thermal displacement at the current position and current time reflects the current position of the main axis and the current thermal displacement of the structure and main axis of the machine tool and the position of the structure of the machine tool. Not only linear deformation due to error, but also non-linear deformation due to bending or twisting as temperature gradients occur between the top and bottom, left and right, and inside and outside of the machine tool structure due to the time constant difference due to the heat capacity difference of the machine tool structure. Calculate the kinematic error relationship by reflecting the
The calculating step involves deriving the equation for the relationship between the angle error and the position error due to the change in thermal displacement at the current position through equation (2) below through regression analysis. method.
Equation (2)

delete

Images