Linear shaft of numerical control machine tool

Abstract

The invention discloses a numerical control machine tool linear shaft which comprises a rolling guide rail assembly. The linear motor driving unit comprises a brushless direct current motor and a stator and a rotor which are matched with the brushless direct current motor, and provides driving force for linear motion for the rolling guide rail assembly; the intelligent temperature control module comprises a temperature sensor, a cooling device and a control unit, the temperature sensor is used for monitoring the temperature change of a sliding block in the rolling guide rail assembly in real time, and the control unit receives a feedback signal of the temperature sensor and controls the cooling device to work; and the position adjusting module comprises a high-precision sensor, a controller and an executing mechanism. The working temperature of the linear shaft can be monitored and adjusted in real time, the influence of temperature change on precision is effectively reduced, and high precision and stability of the linear shaft in long-time working are ensured; and meanwhile, position errors can be detected and compensated in real time, the limitation of a linear shaft of a traditional numerical control machine tool on position precision is broken through, and higher machining precision and surface quality are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of numerically controlled machine tools, and in particular to a linear axis of a numerically controlled machine tool. Background Art

[0002] As a key component in modern mechanical manufacturing technology, the performance of CNC machine tool linear axis directly affects the accuracy, efficiency and stability of CNC machine tools. However, there are still some significant shortcomings in the actual application of CNC machine tool linear axis.

[0003] The linear axis of CNC machine tools will generate heat during operation, causing the temperature to rise. Changes in temperature will cause changes in the thermal expansion coefficient of the material, thereby affecting the dimensional accuracy and shape accuracy of the linear axis. In addition, temperature changes will also affect the viscosity of the grease, which in turn affects the lubrication effect and friction resistance, and ultimately affects the transmission accuracy and stability of the linear axis. The linear axis of CNC machine tools usually uses ball screw transmission. This transmission method has a large friction resistance, which not only reduces the transmission efficiency, but also accelerates the wear of the guide rails and screws. Wear will cause the guide rail gap to increase, affecting the positioning accuracy and stability. At the same time, the debris generated by wear may also pollute the working environment and affect the overall performance of the CNC machine tool. In addition, due to factors such as mechanical assembly errors, sensor accuracy limitations, and imperfect control systems, the position accuracy of the linear axis still has a certain error. This error will affect the processing accuracy and surface quality of CNC machine tools.

[0004] Therefore, the present invention proposes a linear axis for a numerically controlled machine tool to solve the problems existing in the prior art. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a linear axis for a numerically controlled machine tool.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] The present invention provides a linear axis for a numerically controlled machine tool, comprising:

[0008] The rolling guide rail assembly is composed of a ball screw, a ball, a ball bracket, a linear guide rail, a slider, a slide seat, an external platform and a moving platform. The external platform is used as a carrier to install the ball screw, the ball, the ball bracket, the linear guide rail, the slider and the slide seat inside. The moving platform is connected to the slider and the slide seat to move linearly. The external platform is made of high-strength alloy and has a hollow middle part.

[0009] The linear motor drive unit includes a brushless DC motor and a stator and a mover matched therewith, and provides a driving force for linear motion for the rolling guide assembly;

[0010] An intelligent temperature control module, comprising a temperature sensor, a cooling device and a control unit, wherein the temperature sensor is used to monitor the temperature change of the slider in the rolling guide assembly in real time, and the control unit receives a feedback signal from the temperature sensor and controls the operation of the cooling device;

[0011] A position adjustment module, comprising a high-precision sensor, a controller and an actuator, wherein the high-precision sensor is arranged on a moving platform of the rolling guide assembly to monitor position information in real time, the controller calculates the position error according to the real-time position feedback signal provided by the high-precision position sensor, and automatically adjusts the output of the actuator based on the position error component, and the actuator adjusts the position of the controlled object according to the signal of the controller;

[0012] The lubrication system includes grease, a lubrication pump and a lubrication pipeline. The grease is regularly injected into the raceway of the ball screw through the lubrication pump to reduce friction and wear and extend the service life of the guide rail.

[0013] As a preferred technical solution of the present invention, the ball is installed in a ball bracket, and a nut and a preload spring are provided on the ball bracket.

[0014] As a preferred technical solution of the present invention, an elastic element is arranged between the stator and the mover of the linear motor drive unit, and the stiffness or preload force of the elastic element is changed by adjusting the screw.

[0015] As a preferred technical solution of the present invention, the control unit of the intelligent temperature control module is built with a PID control algorithm, which calculates the temperature error according to the real-time temperature feedback signal provided by the temperature sensor, and automatically adjusts the working state of the cooling device based on the proportional (P), integral (I) and differential (D) components of the temperature error to achieve precise temperature control; wherein the control signal output formula of the PID control algorithm is:

[0016]

[0017] In formula (1), u(t) represents the control signal, which is used for the power of the cooling device; e(t) represents the temperature error; Kp, Ki, and Kd are the proportional coefficient, integral coefficient, and differential coefficient, respectively.

[0018] As a preferred technical solution of the present invention, the actuator of the position adjustment module is equipped with a position compensation algorithm, which calculates the position error according to the real-time position feedback signal provided by the high-precision sensor and automatically adjusts the output of the actuator to compensate for the position error; wherein, the implementation method of the position compensation algorithm includes the following steps:

[0019] a) Obtaining actual position information fed back by high-precision sensors;

[0020] b) Calculate the position error between the actual position and the target position. The position error calculation formula is:

[0021] e(t)=Xtarget-Xactual(t) (2)

[0022] In formula (2), e(t) is the position error at time t, Xtarget is the target position, and Xactual(t) is the actual position at time t;

[0023] c) According to the position error, the compensation amount is calculated through the preset compensation strategy or model. The compensation amount calculation formula is:

[0024] Δx(t)=f(e(t),parameters) (3)

[0025] In formula (3), Δx(t) is the compensation amount at time t, and f is a function that calculates the compensation amount based on the position error and algorithm parameters;

[0026] d) Convert the compensation amount into a control signal recognizable by the actuator and output it to the actuator to adjust the position of the linear axis to achieve position compensation.

[0027] As a preferred technical solution of the present invention, the high-precision sensor is any one or more combinations of a laser ranging sensor, a grating scale, a magnetic scale or an encoder, and the actuator is a linear moving platform driven by a servo motor.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention can monitor and adjust the working temperature of the linear axis in real time, effectively reducing the influence of temperature changes on the accuracy, and ensuring the high accuracy and stability of the linear axis during long-term operation; at the same time, it can detect and compensate for position errors in real time, breaking through the limitations of the position accuracy of the linear axis of traditional CNC machine tools, and achieving higher processing accuracy and surface quality; at the same time, through lubrication and cooling, it ensures good lubrication and heat dissipation of the linear axis during operation, avoids the decrease in accuracy and increased wear caused by overheating and poor lubrication, and improves the reliability and durability of the linear axis. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0031] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0032] Figure 2is a schematic diagram of the intelligent temperature control module of the present invention;

[0033] Figure 3 is a schematic diagram of a position adjustment module of the present invention;

[0034] In the figure: 1. Rolling guide assembly; 2. Linear motor drive unit; 3. Intelligent temperature control module; 4. Position adjustment module; 5. Lubrication system. DETAILED DESCRIPTION

[0035] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0036] Example 1

[0037] like Figure 1-3 As shown, the present invention provides a linear axis of a numerically controlled machine tool, comprising:

[0038] The rolling guide assembly 1 is composed of a ball screw, a ball, a ball bracket, a linear guide, a slider, a slide seat, an outer platform and a moving platform. The outer platform is used as a carrier to install the ball screw, the ball, the ball bracket, the linear guide, the slider and the slide seat inside. The moving platform is connected to the slider and the slide seat to move linearly. The outer platform is made of high-strength alloy and has a hollow middle portion.

[0039] The linear motor drive unit 2 includes a brushless DC motor and a stator and a mover matched therewith, and provides a driving force for linear motion for the rolling guide assembly 1;

[0040] The intelligent temperature control module 3 includes a temperature sensor, a cooling device and a control unit. The temperature sensor is used to monitor the temperature change of the slider in the rolling guide assembly 1 in real time. The control unit receives the feedback signal of the temperature sensor and controls the operation of the cooling device.

[0041] The position adjustment module includes a high-precision sensor, a controller and an actuator. The high-precision sensor is arranged on the moving platform of the rolling guide assembly 1 to monitor the position information in real time. The controller calculates the position error according to the real-time position feedback signal provided by the high-precision position sensor, and automatically adjusts the output of the actuator based on the position error component. The actuator adjusts the position of the controlled object according to the signal of the controller.

[0042] The lubrication system 5 includes lubricating grease, a lubricating pump and a lubricating pipeline. The lubricating grease is regularly injected into the raceway of the ball screw through the lubricating pump to reduce friction and wear and extend the service life of the guide rail.

[0043] Furthermore, the ball is installed in the ball bracket, and a nut and a preload spring are provided on the ball bracket. The preload spring is located between the nut and the ball. When the nut is rotated to compress the ball, the preload spring will be compressed, thereby generating a continuous preload force. This preload force helps to ensure that the ball maintains gapless rolling in the raceway of the ball screw.

[0044] Furthermore, an elastic element is arranged between the stator and the mover of the linear motor drive unit 2 to provide buffering and shock absorption so as to reduce the gap change caused by factors such as vibration, impact or temperature change. The stiffness or preload of the elastic element is changed by adjusting the screw, thereby achieving fine-tuning of the gap between the stator and the mover to adapt to different working conditions and ensure the stability and accuracy of the brushless DC motor.

[0045] Furthermore, the control unit of the intelligent temperature control module 3 is built with a PID control algorithm, which calculates the temperature error (i.e., the difference between the actual temperature and the target temperature) according to the real-time temperature feedback signal provided by the temperature sensor, and automatically adjusts the working state of the cooling device based on the proportional (P), integral (I) and differential (D) components of the temperature error to achieve precise temperature control; wherein, the control signal output formula of the PID control algorithm is:

[0046]

[0047] In formula (1), u(t) represents the control signal, which is used for the power of the cooling device; e(t) represents the temperature error; Kp, Ki, and Kd are the proportional coefficient, integral coefficient, and differential coefficient, respectively.

[0048] The PID control algorithm also includes an adaptive adjustment mechanism, which is used to dynamically adjust the proportional coefficient, integral coefficient and differential coefficient according to the changing trend of the temperature error and the response characteristics of the system during system operation to optimize the control effect and stability.

[0049] Furthermore, the actuator of the position adjustment module 4 is equipped with a position compensation algorithm, which calculates the position error (i.e., the difference between the actual position and the target position) according to the real-time position feedback signal provided by the high-precision sensor, and automatically adjusts the output of the actuator to compensate for the position error, thereby improving the positioning accuracy of the linear axis; wherein, the implementation method of the position compensation algorithm includes the following steps:

[0050] a) Obtaining actual position information fed back by high-precision sensors;

[0051] b) Calculate the position error between the actual position and the target position. The position error calculation formula is:

[0052] e(t)=Xtarget-Xactual(t) (2)

[0053] In formula (2), e(t) is the position error at time t, Xtarget is the target position, and Xactual(t) is the actual position at time t;

[0054] c) According to the position error, the compensation amount is calculated through the preset compensation strategy or model. The compensation amount calculation formula is:

[0055] Δx(t)=f(e(t),parameters) (3)

[0056] In formula (3), Δx(t) is the compensation amount at time t, and f is a function that calculates the compensation amount based on the position error and algorithm parameters;

[0057] d) Convert the compensation amount into a control signal recognizable by the actuator and output it to the actuator to adjust the position of the linear axis to achieve position compensation.

[0058] The position compensation algorithm also includes a dynamic adjustment mechanism, which is used to dynamically adjust the compensation strategy or parameters in the model according to the changing trend of the position error and the response characteristics of the system during system operation to optimize the compensation effect and positioning accuracy.

[0059] Furthermore, the high-precision sensor is any one or more combinations of laser ranging sensors, grating scales, magnetic scales or encoders, which are used to provide high-precision, high-resolution position feedback signals, and the actuator is a linear moving platform driven by a servo motor.

[0060] Specific:

[0061] 1. Start: After the power is turned on, the linear axis of the CNC machine tool enters the standby state. Start the linear axis through the control panel and perform initialization settings. The initialization process includes checking the connection status of each module (such as intelligent temperature control module 3, position adjustment module 4, etc.), calibrating sensors and actuators, etc.

[0062] 2. Temperature control: The temperature sensor monitors the temperature changes of the slider part in the rolling guide assembly in real time, and sends the temperature data to the control unit. After the control unit receives the feedback signal from the temperature sensor, the built-in PID control algorithm is calculated based on the difference between the current temperature and the target temperature (i.e., the temperature error). According to the calculation results of the PID control algorithm, the control unit automatically adjusts the working state of the cooling device. The cooling device is a cooling fan with circulating coolant. For example, when the temperature error is large, the control unit may increase the speed of the cooling fan or increase the flow rate of the coolant to quickly reduce the temperature; when the temperature error is small, the speed of the cooling fan may be reduced or the flow rate of the coolant may be reduced to keep the temperature stable. Through continuous feedback and adjustment, the intelligent temperature control module 3 can achieve precise control of the temperature of the slider in the rolling guide assembly 1, ensuring that the linear axis operates in a stable temperature environment.

[0063] 3. Position adjustment and compensation: High-precision sensors (such as laser ranging sensors, grating rulers, etc.) monitor the position information of the mobile platform in real time and send the position data to the controller. After receiving the feedback signal from the high-precision sensor, the controller calculates the position error between the target position and the actual position according to the preset trajectory or instruction. According to the size and direction of the position error, the controller calculates the compensation amount through a preset compensation strategy or model. The size and direction of the compensation amount depend on the size of the position error and the response characteristics of the system. The controller converts the compensation amount into a control signal recognizable by the actuator and outputs it to the actuator. The actuator is a linear moving platform driven by a servo motor, and its output can be adjusted according to the control signal to achieve compensation for the position error. Through continuous feedback and adjustment, the position adjustment module 4 can achieve precise control of the position of the mobile platform and ensure that the linear axis moves in a straight line according to the preset trajectory or instruction.

[0064] 4. Linear motion control: According to the preset trajectory or instructions, the linear motor drive unit 2 provides the driving force for linear motion for the rolling guide assembly. After receiving the instructions from the controller, the linear motor drive unit 2 adjusts the output current and frequency of the brushless DC motor according to the requirements of the instructions, thereby controlling the mobile platform to move linearly along the linear guide. During the movement, the controller monitors the position information of the mobile platform in real time through a high-precision sensor, and adjusts and controls it as needed. At the same time, the intelligent temperature control module 3 also continuously monitors the temperature changes of the slider in the rolling guide assembly, and adjusts and controls it as needed. Through the synergistic effect of linear motion control and temperature control, the linear axis of the CNC machine tool can achieve high-precision and high-stability linear motion control.

[0065] 5. Linear axis lubrication: Lubrication system 5 regularly injects grease into the ball screw raceway through the lubrication pump to reduce friction and wear. The lubrication cycle and lubrication amount can be adjusted according to actual conditions. Regularly check the wear and connection status of each component. And for severely worn components (such as balls, ball brackets, etc.), they should be replaced in time.

[0066] The present invention can monitor and adjust the working temperature of the linear axis in real time, effectively reducing the influence of temperature changes on the accuracy, and ensuring the high accuracy and stability of the linear axis during long-term operation; at the same time, it can detect and compensate for position errors in real time, breaking through the limitations of the position accuracy of the linear axis of traditional CNC machine tools, and achieving higher processing accuracy and surface quality; at the same time, through lubrication and cooling, it ensures good lubrication and heat dissipation of the linear axis during operation, avoids the decrease in accuracy and increased wear caused by overheating and poor lubrication, and improves the reliability and durability of the linear axis.

[0067] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A linear axis of a CNC machine tool, characterized in that: include: The rolling guide assembly (1) is composed of a ball screw, a ball, a ball bracket, a linear guide, a slider, a slide seat, an external platform and a moving platform. The external platform is used as a carrier to install the ball screw, the ball, the ball bracket, the linear guide, the slider and the slide seat. The moving platform is connected to the slider and the slide seat to move linearly. The external platform is made of a high-strength alloy and has a hollow middle portion. A linear motor drive unit (2), comprising a brushless DC motor and a stator and a mover matched therewith, and providing a driving force for linear motion for the rolling guide rail assembly (1); An intelligent temperature control module (3) comprising a temperature sensor, a cooling device and a control unit, wherein the temperature sensor is used to monitor the temperature change of the slider in the rolling guide assembly (1) in real time, and the control unit receives a feedback signal from the temperature sensor and controls the operation of the cooling device; A position adjustment module (4) comprises a high-precision sensor, a controller and an actuator, wherein the high-precision sensor is arranged on a moving platform of the rolling guide assembly (1) to monitor position information in real time, the controller calculates the position error according to the real-time position feedback signal provided by the high-precision position sensor, and automatically adjusts the output of the actuator based on the position error component, and the actuator adjusts the position of the controlled object according to the signal of the controller; The lubrication system (5) comprises lubrication grease, a lubrication pump and a lubrication pipeline. The lubrication grease is regularly injected into the raceway of the ball screw through the lubrication pump to reduce friction and wear and extend the service life of the guide rail.

2. A linear axis for a CNC machine tool according to claim 1, characterized in that: The ball is installed in the ball bracket, and the ball bracket is provided with a nut and a preload spring.

3. A linear axis for a CNC machine tool according to claim 1, characterized in that: An elastic element is arranged between the stator and the mover of the linear motor drive unit (2), and the stiffness or pre-tightening force of the elastic element is changed by adjusting the screw.

4. The linear axis of a CNC machine tool according to claim 1, characterized in that: The control unit of the intelligent temperature control module (3) is equipped with a PID control algorithm, which calculates the temperature error based on the real-time temperature feedback signal provided by the temperature sensor, and automatically adjusts the working state of the cooling device based on the proportional (P), integral (I) and differential (D) components of the temperature error to achieve accurate temperature control; wherein the control signal output formula of the PID control algorithm is: In formula (1), u(t) represents the control signal, which is used for the power of the cooling device; e(t) represents the temperature error; Kp, Ki, and Kd are the proportional coefficient, integral coefficient, and differential coefficient, respectively.

5. The linear axis of a CNC machine tool according to claim 1, characterized in that: The actuator of the position adjustment module (4) is equipped with a position compensation algorithm, which calculates the position error based on the real-time position feedback signal provided by the high-precision sensor and automatically adjusts the output of the actuator to achieve compensation for the position error; wherein the implementation method of the position compensation algorithm includes the following steps: a) Obtaining actual position information fed back by high-precision sensors; b) Calculate the position error between the actual position and the target position. The position error calculation formula is: e(t)=Xtarget-Xactual(t) (2) In formula (2), e(t) is the position error at time t, Xtarget is the target position, and Xactual(t) is the actual position at time t; c) According to the position error, the compensation amount is calculated through the preset compensation strategy or model. The compensation amount calculation formula is: Δx(t)=f(e(t),parameters) (3) In formula (3), Δx(t) is the compensation amount at time t, and f is a function that calculates the compensation amount based on the position error and algorithm parameters; d) Convert the compensation amount into a control signal recognizable by the actuator and output it to the actuator to adjust the position of the linear axis to achieve position compensation.

6. A linear axis for a CNC machine tool according to claim 5, characterized in that: The high-precision sensor is any one or more combinations of a laser distance measuring sensor, a grating scale, a magnetic scale or an encoder, and the actuator is a linear moving platform driven by a servo motor.

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