A method for thermal distortion prediction and compensation for a numerical control machine tool

Abstract

The application provides a thermal deformation prediction and compensation method for a numerical control machine tool, and relates to the technical field of numerical control machine tools.The compensation method comprises the following steps: collecting temperature data of a plurality of temperature-sensitive points of the machine tool; detecting the thermal characteristics of the machine tool to obtain thermal errors of linear shafts, thermal errors of rotary shafts and thermal errors of main shafts; based on the temperature data and the thermal errors, a multivariate regression analysis method is used to establish a thermal error prediction mathematical model; a thermal error compensation distribution method is established by using a multibody theory to convert the thermal errors into position errors of the linear shafts; the position errors are transmitted to a numerical control system of the machine tool, and the original position parameters of each linear shaft in the numerical control system are adjusted to realize the position offset of the linear shafts of the machine tool, so that the real-time compensation of the thermal errors is realized, a brand-new train of thought and implementation mode are provided for the thermal compensation research, and the requirements for the thermal error compensation of high-end numerical control machine tools can be met.

Description

Technical Field

[0001] This invention belongs to the field of CNC machine tool technology, and more specifically, relates to a method for predicting and compensating for thermal deformation of CNC machine tools. Background Technology

[0002] With the widespread application of high-speed and high-precision machine tools, the factors affecting the machining accuracy of high-end CNC machine tools are receiving increasing attention. Generally speaking, the main influencing factors can be divided into the following categories: machine tool geometric error, thermal error, system control error, force error, and CAM toolpath error. Among them, machine tool thermal error mainly refers to the thermal deformation generated by the machine tool during operation, such as the deformation of the main structure of the machine tool caused by changes in ambient temperature, the thermal deformation generated by the spindle during high-speed rotation, and the thermal expansion generated by the guide rail and lead screw during operation. The impact of machine tool thermal error on the machining accuracy of parts accounts for about 40%-70% of the total machining error of the machine tool. Therefore, controlling or compensating for the thermal error generated by the machine tool is very important for ensuring the machining accuracy of machine tool parts. At present, existing technical solutions have not systematically studied the thermal errors generated by the linear axes, rotary axes, and spindles of CNC machine tools, especially five-axis linkage machine tools, and have not studied the thermal error prediction algorithm and compensation method of the whole CNC machine tool. It is not easy to realize the compensation of the thermal error generated by CNC machine tools, and it is not easy to commercialize the thermal error compensation function of CNC machine tools. Summary of the Invention

[0003] The purpose of this invention is to provide a systematic method for predicting and compensating thermal deformation of CNC machine tools, addressing the shortcomings of existing technologies. This method solves the problem that existing technical solutions mentioned in the background do not systematically study the thermal errors generated by the linear axes, rotary axes, and spindles of CNC machine tools, especially five-axis linkage machine tools, and do not study the thermal error prediction algorithm and compensation method of the entire CNC machine tool, making it difficult to compensate for the thermal errors generated by CNC machine tools.

[0004] To achieve the above objectives, the present invention provides a method for predicting and compensating for thermal deformation of CNC machine tools, the compensation method comprising:

[0005] Collect temperature data from multiple temperature-sensitive points on the machine tool and temperature data from the machine tool's surrounding environment;

[0006] The thermal characteristics of the machine tool are tested to obtain the thermal errors of the linear axis, the rotary axis, and the spindle.

[0007] A mathematical model for predicting thermal errors is established based on temperature data and thermal errors using multiple regression analysis.

[0008] A thermal error compensation and allocation method is established using multibody theory to convert thermal errors into position errors of the linear axis;

[0009] The position error is transmitted to the CNC system of the machine tool, and the position parameters of the origin of each linear axis in the CNC system are adjusted to realize the position offset of the linear axis of the machine tool, so as to achieve real-time compensation for thermal error.

[0010] Preferably, the temperature data collected from multiple temperature-sensitive points of the machine tool includes:

[0011] Temperature sensors are installed at each temperature-sensitive point, and the temperature signals from the sensors are transmitted to the CNC system of the machine tool to achieve real-time monitoring of temperature data.

[0012] Preferably, the thermal characteristic detection of the machine tool, obtaining the thermal error of the linear axis, the thermal error of the rotary axis, and the thermal error of the spindle, includes:

[0013] To obtain the thermal positioning error in the thermal error of the linear axis, the machine tool has three linear axes: the X-axis, Y-axis, and Z-axis. The thermal positioning error detection is set to three items.

[0014] To obtain the coordinate thermal drift error in the thermal error of the rotary axis, the machine tool has two rotary axes, namely the A-axis and the C-axis, and the coordinate thermal drift error is set to six items;

[0015] To obtain the thermal errors of the spindle, we need to calculate the thermal expansion error, coordinate thermal drift error, and axis angle deformation error. The machine tool has one spindle, which is the milling spindle. We set the thermal expansion error as one item, the coordinate thermal drift error as two items, and the axis angle deformation error as two items.

[0016] Preferably, the method of establishing a mathematical model for predicting thermal errors based on temperature data and thermal errors using multiple regression analysis includes:

[0017] Temperature data of temperature-sensitive points corresponding to the linear axis, the rotary axis, and the spindle, as well as the machine tool body, the ambient temperature, and the linear axis running position are set as independent variables. Various thermal errors of the linear axis, the rotary axis, and the spindle are set as dependent variables. A mathematical model of thermal error for the linear axis, the rotary axis, and the spindle is established using multiple regression analysis.

[0018] Preferably, the method for establishing thermal error compensation allocation using multibody theory to convert thermal error into position error of a linear axis includes:

[0019] The various thermal errors of the linear axis, the various thermal errors of the rotary axis, and the various thermal errors of the spindle are converted into position errors of the linear axis.

[0020] Preferably, the step of transmitting the position error to the CNC system of the machine tool and adjusting the origin position parameters of each linear axis in the CNC system to achieve the position offset of the linear axes of the machine tool, so as to realize real-time compensation for thermal error, includes:

[0021] The software development process involves writing the thermal error prediction mathematical model and thermal error compensation allocation method into the thermal error compensation allocator in the form of a program algorithm, calculating the thermal error compensation values ​​allocated to the X-axis, Y-axis and Z-axis, and then transmitting the thermal error compensation values ​​to the machine tool CNC system.

[0022] Preferably, a thermal characteristic testing device is used to detect the thermal error of the linear axis, the thermal error of the rotary axis, and the thermal error of the spindle of the machine tool. This testing device includes:

[0023] The first detection module includes an optical measuring instrument, which is installed on the machine tool. The first detection module is used to detect the thermal positioning error in the thermal error of the linear axis.

[0024] The second detection module includes multiple first detection probes and a sphere. The sphere is disposed on the rotating shaft, and the multiple first detection probes are disposed on the machine tool and on the periphery of the sphere. The second detection module is used to detect the coordinate thermal drift error in the thermal error of the rotating shaft.

[0025] The third detection module includes multiple second detection probes, which are disposed on the machine tool and on the periphery and end sides of the spindle. The third detection module is used to detect thermal elongation error, coordinate thermal drift error and axis angle deformation error in the thermal error of the spindle.

[0026] Preferably, the optical measuring instrument is a laser interferometer.

[0027] Preferably, the sphere is an alloy steel sphere, the first detection probe is an eddy current sensor, the number of the first detection probes is three, and the second detection module further includes:

[0028] A first link, the first link being connected to the machine tool;

[0029] A first housing is connected to the end of the first connecting rod. The first housing has an opening at a position away from the first connecting rod. Three first detection probes are disposed through the first housing. The three first detection probes are perpendicular to each other. The axes of the three first detection probes and the axis of the first connecting rod can intersect at a point.

[0030] The second link is connected to the rotation axis, and the ball is connected to the end of the second link.

[0031] Preferably, the second detection probe is an eddy current sensor, and the third detection module further includes:

[0032] The second housing is connected to the machine tool. The spindle is disposed inside the second housing. The sidewall of the second housing is located in the base plane of the machine tool in the X and Z directions, and two second detection probes are disposed through it from top to bottom. The sidewall of the second housing is located in the base plane of the machine tool in the Y and Z directions, and two second detection probes are disposed through it from top to bottom. One second detection probe is disposed through it at the bottom end of the second housing.

[0033] This invention provides a method for predicting and compensating thermal deformation in CNC machine tools. Its advantages lie in the following: This compensation method, through the entire process of acquiring machine tool temperature data, detecting thermal errors, establishing a mathematical model for thermal error prediction, and establishing a thermal error compensation allocation method, converts the thermal errors of the linear axis, rotary axis, and spindle into positional errors of the linear axis, which are then transmitted to the CNC system of the machine tool. Through adjustments made by the CNC system, the position of the linear axis of the machine tool is offset, thereby achieving real-time thermal error compensation. This provides a novel approach and implementation method for thermal compensation research and can meet the requirements for thermal error compensation in high-end CNC machine tools.

[0034] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0035] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the invention.

[0036] Figure 1 A flowchart of a method for predicting and compensating thermal deformation of a CNC machine tool according to an embodiment of the present invention is shown.

[0037] Figure 2 A roadmap for a method of predicting and compensating thermal deformation in CNC machine tools according to an embodiment of the present invention is shown.

[0038] Figure 3 A schematic diagram of the various temperature-sensitive points at the machine tool location is shown in a method for predicting and compensating thermal deformation of a CNC machine tool according to an embodiment of the present invention.

[0039] Figure 4 A schematic diagram of a second detection module for a method of predicting and compensating thermal deformation of a CNC machine tool according to an embodiment of the present invention is shown.

[0040] Figure 5 A schematic diagram of the thermal error of a rotating axis in the X and Y directions is shown in an embodiment of the present invention for a method of predicting and compensating thermal deformation of a CNC machine tool.

[0041] Figure 6 A schematic diagram of the thermal error of the rotating axis in the Z direction is shown in a method for predicting and compensating thermal deformation of CNC machine tools according to an embodiment of the present invention.

[0042] Figure 7 A front view schematic diagram of a third detection module for a method of predicting and compensating thermal deformation of CNC machine tools according to an embodiment of the present invention is shown.

[0043] Figure 8 A side view schematic diagram of the third detection module of a method for predicting and compensating thermal deformation of CNC machine tools according to an embodiment of the present invention is shown.

[0044] Figure 9 A block diagram is shown illustrating a method for predicting and compensating thermal deformation in CNC machine tools according to an embodiment of the present invention, which uses multibody theory to establish thermal error compensation allocation.

[0045] Explanation of reference numerals in the attached figures:

[0046] 1. First detection module; 2. Second detection module; 21. First detection probe; 22. Sphere; 23. First connecting rod; 24. First housing; 25. Second connecting rod; 3. Third detection module; 31. Second detection probe; 32. Second housing; 4. Machine tool. Detailed Implementation

[0047] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0048] This invention provides a thermal characteristic testing device for CNC machine tools, used to detect the thermal errors of the linear axes, rotary axes, and spindles of the machine tool. The testing device includes:

[0049] The first detection module 1 includes an optical measuring instrument, which is mounted on the machine tool 4. The first detection module 1 is used to detect the thermal positioning error in the thermal error of the linear axis.

[0050] The second detection module 2 includes multiple first detection probes 21 and a ball 22. The ball 22 is mounted on the rotating shaft, and the multiple first detection probes 21 are mounted on the machine tool 4 and are located around the ball 22. The second detection module is used to detect the coordinate thermal drift error in the thermal error of the rotating shaft.

[0051] The third detection module 3 includes multiple second detection probes 31, which are mounted on the machine tool 4 and located on the periphery and end sides of the spindle. The third detection module 3 is used to detect thermal elongation error, coordinate thermal drift error, and axis angle deformation error in the thermal error of the spindle.

[0052] Specifically, the thermal characteristic detection device is used to detect thermal positioning error in the thermal error of linear shafts, coordinate thermal drift error in the thermal error of rotary shafts, and thermal elongation error, coordinate thermal drift error, and axis angle deformation error in the thermal error of spindles.

[0053] Preferably, the optical measuring instrument is a laser interferometer.

[0054] Specifically, the thermal positioning error in the thermal error of the linear axis is detected by a laser interferometer.

[0055] like Figures 4-6 As shown, preferably, the sphere 22 is an alloy steel sphere, the first detection probe 21 is an eddy current sensor, and the number of first detection probes 21 is three. The second detection module 2 also includes:

[0056] The first link 23 is connected to the machine tool 4;

[0057] The first housing 24 is connected to the end of the first connecting rod 23. The first housing 24 has an opening at a position away from the first connecting rod 23. Three first detection probes are disposed through the first housing. The three first detection probes 21 are perpendicular to each other. The axes of the three first detection probes 21 can intersect the axis of the first connecting rod 23 at a point.

[0058] The second link 25 is connected to the rotating shaft, and the ball 22 is connected to the end of the second link 25.

[0059] Specifically, the alloy steel ball is a high-precision alloy steel ball, the three first detection probes 21 are perpendicular to each other, the axes of the three first detection probes 21 can intersect the axis of the first connecting rod 23 at a point, and the three first detection probes 21 form an orthogonal arrangement in space. By the angle of the three first detection probes 21 and the relative position relationship of the ball 22, the coordinate thermal drift error of the rotation axis is detected.

[0060] like Figure 7 and Figure 8As shown, preferably, the second detection probe 31 is an eddy current sensor, and the third detection module 3 further includes:

[0061] The second housing 32 is connected to the machine tool 4. The spindle is set inside the second housing 32. The sidewalls of the second housing 32 are located in the base plane of the machine tool 4 in the X and Z directions, and two second detection probes 31 are installed through it from top to bottom. The sidewalls of the second housing 32 are located in the base plane of the machine tool 4 in the Y and Z directions, and two second detection probes 31 are installed through it from top to bottom. One second detection probe 31 is installed through it at the bottom end of the second housing 32.

[0062] Specifically, five second detection probes 31 are used to detect thermal elongation error, coordinate thermal drift error, and axis angle deformation error in the thermal error of the spindle.

[0063] like Figure 1 and Figure 2 As shown, this invention provides a method for predicting and compensating for thermal deformation in CNC machine tools, utilizing a thermal characteristic detection device for CNC machine tools. The compensation method includes:

[0064] Collect temperature data from multiple temperature-sensitive points on the machine tool and temperature data from the machine tool's surrounding environment;

[0065] The thermal characteristics of the machine tool are tested to obtain the thermal errors of the linear axis, the rotary axis, and the spindle.

[0066] A mathematical model for predicting thermal errors is established based on temperature data and thermal errors using multiple regression analysis.

[0067] A thermal error compensation and allocation method is established using multibody theory to convert thermal errors into position errors of the linear axis;

[0068] The position error is transmitted to the CNC system of the machine tool, and the position parameters of the origin of each linear axis in the CNC system are adjusted to realize the position offset of the linear axis of the machine tool, so as to achieve real-time compensation for thermal error.

[0069] Specifically, to address the problem that existing thermal error compensation technologies are not readily available for compensating for thermal errors generated by the rotary axes of machine tools, and thus fail to meet the requirements for thermal error compensation in high-end CNC machine tools, this invention provides a thermal deformation compensation method for CNC machine tools. Both the linear and rotary axes are servo axes of the machine tool. The locations of temperature-sensitive points in this compensation method include, but are not limited to, the servo motor mounting base, lead screw nut, bearing housing, front and rear bearings of the electric spindle, spindle housing, rotary axis motor mounting base, and bed base of the machine tool. Furthermore, the surrounding environment of the machine tool can also be designated as temperature-sensitive points. This compensation method, when utilizing a thermal characteristic detection device, involves the entire process of acquiring machine tool temperature data, detecting thermal errors, establishing a mathematical model for predicting thermal errors, and establishing a thermal error compensation allocation method. This process converts the thermal errors of the machine tool's linear axis, rotary axis, and spindle into positional errors of the linear axis, which are then transmitted to the machine tool's CNC system. Through adjustments made by the CNC system, the position of the machine tool's linear axis is offset, thereby achieving real-time thermal error compensation. This provides a novel approach and implementation method for thermal compensation research and can meet the requirements for thermal error compensation in high-end CNC machine tools.

[0070] Specifically, this compensation method can be applied not only to five-axis machine tools, but also to two-axis CNC lathes, three-axis vertical machining centers, and machine tool products with various structural layouts.

[0071] like Figure 3 As shown, preferably, the temperature data collected from multiple temperature-sensitive points of the machine tool includes:

[0072] Temperature sensors are installed at each temperature-sensitive point, and the temperature signals from the sensors are transmitted to the CNC system of the machine tool to achieve real-time monitoring of temperature data.

[0073] Specifically, the temperature sensor is a resistive temperature sensor. The resistive temperature sensor can convert the resistance value into an analog voltage through a temperature transmitter, convert it into a digital signal through an A / D converter, and transmit it to the CNC system of the machine tool through an industrial bus to realize real-time monitoring of temperature data.

[0074] Preferably, the thermal characteristic detection of the machine tool, obtaining the thermal error of the linear axis, the thermal error of the rotary axis, and the thermal error of the spindle, includes:

[0075] To obtain the thermal positioning error in the thermal error of the linear axis, the machine tool has three linear axes: the X-axis, Y-axis, and Z-axis. The thermal positioning error detection is set to three items.

[0076] To obtain the coordinate thermal drift error in the thermal error of the rotary axis, the machine tool has two rotary axes, namely the A-axis and the C-axis, and the coordinate thermal drift error is set to six items;

[0077] To obtain the thermal errors of the spindle, we need to calculate the thermal expansion error, coordinate thermal drift error, and axis angle deformation error. The machine tool has one spindle, which is the milling spindle. We set the thermal expansion error as one item, the coordinate thermal drift error as two items, and the axis angle deformation error as two items.

[0078] Specifically, the thermal positioning error detection is set to three terms, expressed as a function E. xp (x, T) x E yp (y,T y E zp (z,T z ).

[0079] Specifically, the coordinate thermal drift error is set to six terms, expressed as a function E. xa (T a E ya (T a E za (T a E xc (T c E yc (T c E zc (T c ).

[0080] Specifically, thermal elongation error is set as one item, coordinate thermal drift error as two items, and axis angle deformation error as two items, expressed as a function E. xs (T s E ys (T s E zs (T s ), θ sx (T s ), θ sy (T s ).

[0081] Preferably, the method of establishing a mathematical model for predicting thermal errors based on temperature data and thermal errors using multiple regression analysis includes:

[0082] Temperature data of temperature-sensitive points corresponding to the linear axis, the rotary axis, and the spindle, as well as the machine tool body, the ambient temperature, and the linear axis running position are set as independent variables. Various thermal errors of the linear axis, the rotary axis, and the spindle are set as dependent variables. A mathematical model of thermal error for the linear axis, the rotary axis, and the spindle is established using multiple regression analysis.

[0083] Specifically, a mathematical model for the thermal error of the linear axis is established, including:

[0084] The first detection module 1 is used to perform multiple reciprocating thermal positioning error detections on a certain linear axis of the X-axis, Y-axis and Z-axis of the machine tool, and the temperature data of the temperature sensitive point corresponding to the linear axis is recorded.

[0085] Taking the X-axis of a machine tool as an example, let's take the coordinates x of the nth thermal positioning error acquisition point. np The independent variable is the corresponding thermal positioning error value e. np Let p be the dependent variable, where p = 1, 2, 3...m, and m is the number of data collection points on the linear axis. A polynomial interpolation algorithm is used to establish the data at temperature T. xn The thermal positioning error function E of this measurement under the given conditions xp (x, T) xn ).

[0086] E xp (x, T) xn ) = A m (T xn )·x m +A m-1 (T xn )·x m-1 +…+A1(T xn )·x+A0(T xn )

[0087] And the polynomial coefficient function A under the conditions of this measurement can be obtained. m (T x A) m-1 (T x ...A1(T x ), A0(T x At temperature T xn Value A under the condition mn A m-1n ...A 1n A on .

[0088] Where T x It is a one-dimensional temperature matrix containing the element t i t j , representing the temperature value of the corresponding temperature sensor, i, j = 1, 2, ..., T xn This is a matrix of measured temperature values ​​from the nth measurement. Let T be the temperature value. xn A is the independent variable. mn Using multiple linear regression as the dependent variable, the coefficient function A of the m-th order polynomial can be solved. m (T x ).

[0089] Am (T x )=a0+∑b i t i +∑c ij t i t j

[0090] Where a0, b i c ij is the regression coefficient.

[0091] Therefore, the thermal positioning error prediction function E of the linear axis can be obtained. xp (x, T) x ).

[0092] E xp (x, T) x ) = A m (T x )·x m +A m-1 (T x )·x m-1 +…+A1(T x )·x+A0(T x )

[0093] Specifically, a mathematical model for the thermal error of the rotating shaft is established, including:

[0094] The thermal error of the rotating shaft is mainly located at a point on the axis of the rotating shaft. In the reference coordinate system, due to the thermal deformation of the machine tool, spatial thermal drift occurs in the X, Y and Z directions. The coordinate thermal drift function is solved by multiple linear regression.

[0095] E ψω (T ω ) = r ψ0 +∑r ψi Δt ωi +∑r ψij Δt ωi Δt ωj +...

[0096] The letter ψ represents the spatial orthogonality error direction, which can be replaced by x, y, and z; the letter ω represents the name of the rotation axis, such as the A and C axes; where r ψ0 r ψi r ψij For regression coefficients, Δt ωi、 Δt ωj Temperature matrix T ω The elements in the table represent the temperature change values ​​of the corresponding temperature sensors, i, j = 1, 2, ...

[0097] Taking the A-axis of a machine tool rotating around the X-axis as an example, the three-dimensional spatial thermal drift is expressed in functional form as Exa (T a E ya (T a E za (T a ).

[0098] Specifically, a mathematical model for spindle thermal error is established, including:

[0099] Thermal error detection of the spindle is performed under three operating conditions: low speed, medium speed, and high speed. The temperature of the corresponding temperature-sensitive point is collected at timed intervals starting from the cold state.

[0100] Taking a milling spindle as an example, it includes five thermal errors: thermal expansion error of the spindle (one item) and coordinate thermal drift error of the spindle (two items), expressed as a function E. σs (T s The letter σ represents the direction of thermal error and can be replaced by x, y, and z; the axial angle deformation error of the spindle consists of two terms, expressed as a function. letter This represents the direction of inclination and can be replaced by x or y.

[0101] The thermal elongation error and the coordinate thermal drift error of the principal shaft can be expressed by the following formula using multiple linear regression:

[0102] E σs (T s ) = s σ0 +∑s σi Δt si +∑s σij Δt si Δt sj +…

[0103] The spindle's axial angle deformation error can be expressed by the following formula:

[0104]

[0105] Where s σ0 s σi s σij , For regression coefficients, Δt si Δt sj Temperature matrix T s The elements in the table represent the temperature change values ​​of the corresponding temperature sensors, i,j = 1, 2, ...

[0106] Preferably, the method for establishing thermal error compensation allocation using multibody theory to convert thermal error into position error of a linear axis includes:

[0107] The various thermal errors of the linear axis, the various thermal errors of the rotary axis, and the various thermal errors of the spindle are converted into position errors of the linear axis.

[0108] Specifically, after establishing mathematical models for various thermal errors, during the actual machining process of the machine tool, it is necessary to calculate the position change components of the linear axis, rotary axis, and spindle caused by various thermal errors. A thermal error compensation and distribution method is established using multibody theory to convert various thermal errors into position errors of the linear axis. The sum of the position errors caused by various thermal errors of the same linear axis is the thermal error compensation value of the machine tool at that moment.

[0109] like Figure 9 As shown, taking a five-axis machining center containing three linear axes (X-axis, Y-axis, Z-axis), two rotary axes (A-axis, C-axis), and one spindle as an example, the thermal error compensation allocation algorithm includes:

[0110] The thermal error compensation values ​​assigned to the X-axis include the linear axis thermal error E. xp (x, T) x The X-axis coordinate offset of the machining point in the machine tool coordinate system caused by the thermal deformation of the rotating shaft and the X-axis coordinate offset of the machining point in the machine tool coordinate system caused by the thermal deformation of the spindle.

[0111] The thermal error compensation value assigned to the Y-axis includes the linear axis thermal error E. yp (y, T) y The Y-axis coordinate offset of the machining point in the machine tool coordinate system caused by the thermal deformation of the rotating shaft and the Y-axis coordinate offset of the machining point in the machine tool coordinate system caused by the thermal deformation of the spindle.

[0112] The thermal error compensation value assigned to the Z-axis includes the linear axis thermal error E. zp (z,T z The Z-axis coordinate offset of the machining point in the machine tool coordinate system caused by the thermal deformation of the rotating shaft and the Z-axis coordinate offset of the machining point in the machine tool coordinate system caused by the thermal deformation of the spindle.

[0113] Preferably, the step of transmitting the position error to the CNC system of the machine tool and adjusting the origin position parameters of each linear axis in the CNC system to achieve the position offset of the linear axes of the machine tool, so as to realize real-time compensation for thermal error, includes:

[0114] The software development process involves writing the thermal error prediction mathematical model and thermal error compensation allocation method into the thermal error compensation allocator in the form of a program algorithm, calculating the thermal error compensation values ​​allocated to the X-axis, Y-axis and Z-axis, and then transmitting the thermal error compensation values ​​to the machine tool CNC system.

[0115] Specifically, the thermal error compensation value is transmitted from the thermal error compensation distributor to the machine tool's CNC system PLC via the industrial bus, and then to the CNC. By adjusting the origin position parameters of each linear axis in the CNC system, the position offset of the machine tool's linear axes is achieved, thereby realizing real-time compensation of thermal errors.

[0116] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for predicting and compensating thermal deformation in CNC machine tools, characterized in that, The compensation method includes: Collect temperature data from multiple temperature-sensitive points on the machine tool and temperature data from the machine tool's surrounding environment; The thermal characteristics of the machine tool are tested to obtain the thermal errors of the linear axis, the rotary axis, and the spindle. This includes obtaining the thermal positioning error in the thermal error of the linear axis, the coordinate thermal drift error in the thermal error of the rotary axis, and the thermal elongation error, coordinate thermal drift error, and axis angle deformation error in the thermal error of the spindle. Based on temperature data and thermal errors, a mathematical model for predicting thermal errors is established using multiple regression analysis. This includes setting the temperature data of the temperature-sensitive points corresponding to the linear axis, the rotary axis, and the spindle as independent variables, and setting the thermal errors of the linear axis, the rotary axis, and the spindle as dependent variables. The mathematical models for the thermal errors of the linear axis, the rotary axis, and the spindle are then established using multiple regression analysis. A thermal error compensation allocation method is established using multibody theory, which converts thermal errors into positional errors of the linear axis. This includes converting various thermal errors of the linear axis, the rotary axis, and the spindle into positional errors of the linear axis. The thermal error compensation value allocated to the linear axis includes the thermal error of the linear axis, the coordinate offset of the machining point in the linear axis direction in the machine tool coordinate system caused by the thermal deformation of the rotary axis, and the coordinate offset of the machining point in the linear axis direction in the machine tool coordinate system caused by the thermal deformation of the spindle. The position error is transmitted to the CNC system of the machine tool, and the position parameters of the origin of each linear axis in the CNC system are adjusted to realize the position offset of the linear axis of the machine tool, so as to achieve real-time compensation for thermal error.

2. The method for predicting and compensating thermal deformation in CNC machine tools according to claim 1, characterized in that, The temperature data collected from multiple temperature-sensitive points of the machine tool includes: Temperature sensors are installed at each temperature-sensitive point, and the temperature signals from the sensors are transmitted to the CNC system of the machine tool to achieve real-time monitoring of temperature data.

3. The method for predicting and compensating thermal deformation in CNC machine tools according to claim 2, characterized in that, The thermal characteristic detection of the machine tool, which obtains the thermal errors of the linear axis, rotary axis, and spindle, also includes: The machine tool has three linear axes: the X-axis, Y-axis, and Z-axis. The thermal positioning error detection is set to three items. The machine tool has two rotary axes, namely the A-axis and the C-axis, and the coordinate thermal drift error is set to six items; The machine tool has one spindle, which is the milling spindle. The thermal elongation error is set as one item, the coordinate thermal drift error is set as two items, and the axis angle deformation error is set as two items.

4. The method for predicting and compensating thermal deformation of CNC machine tools according to claim 1, characterized in that, The process of transmitting the position error to the CNC system of the machine tool and adjusting the origin position parameters of each linear axis in the CNC system to achieve the position offset of the linear axes of the machine tool and realize real-time compensation for thermal errors includes: The software development process involves writing the thermal error prediction mathematical model and thermal error compensation allocation method into the thermal error compensation allocator in the form of a program algorithm, calculating the thermal error compensation values ​​allocated to the X-axis, Y-axis and Z-axis, and then transmitting the thermal error compensation values ​​to the machine tool CNC system.

5. A method for predicting and compensating thermal deformation in CNC machine tools according to claim 3, characterized in that, A thermal characteristic testing device is used to detect the thermal errors of the linear axis, rotary axis, and spindle of a machine tool. This testing device includes: The first detection module includes an optical measuring instrument, which is installed on the machine tool. The first detection module is used to detect the thermal positioning error in the thermal error of the linear axis. The second detection module includes multiple first detection probes and a sphere. The sphere is disposed on the rotating shaft, and the multiple first detection probes are disposed on the machine tool and on the periphery of the sphere. The second detection module is used to detect the coordinate thermal drift error in the thermal error of the rotating shaft. The third detection module includes multiple second detection probes, which are disposed on the machine tool and on the periphery and end sides of the spindle. The third detection module is used to detect thermal elongation error, coordinate thermal drift error and axis angle deformation error in the thermal error of the spindle.

6. A method for predicting and compensating thermal deformation in CNC machine tools according to claim 5, characterized in that, The optical measuring instrument is a laser interferometer.

7. A method for predicting and compensating thermal deformation in CNC machine tools according to claim 5, characterized in that, The sphere is an alloy steel sphere, the first detection probe is an eddy current sensor, and there are three of the first detection probes. The second detection module also includes: A first link, the first link being connected to the machine tool; A first housing is connected to the end of the first connecting rod. The first housing has an opening at a position away from the first connecting rod. Three first detection probes are disposed through the first housing. The three first detection probes are perpendicular to each other. The axes of the three first detection probes and the axis of the first connecting rod can intersect at a point. The second link is connected to the rotation axis, and the ball is connected to the end of the second link.

8. A method for predicting and compensating thermal deformation in CNC machine tools according to claim 5, characterized in that, The second detection probe is an eddy current sensor, and the third detection module further includes: The second housing is connected to the machine tool. The spindle is disposed inside the second housing. The sidewall of the second housing is located in the base plane of the machine tool in the X and Z directions, and two second detection probes are disposed through it from top to bottom. The sidewall of the second housing is located in the base plane of the machine tool in the Y and Z directions, and two second detection probes are disposed through it from top to bottom. One second detection probe is disposed through it at the bottom end of the second housing.

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