Numerical control machine tool system for precision injection mold processing

Abstract

The present invention relates to the technical field of numerical control machine tool systems, and relates to a numerical control machine tool system for precision injection mold processing. The numerical control machine tool system for precision injection mold processing comprises a CAM system and a detection module, a measurement module, an execution module, an analysis module and a parameter optimization module that are communicationally connected to the CAM system. The CAM system provides a programmed contour of a three-dimensional model of an S-shaped test piece; the execution module performs machining on the basis of the programmed contour; the measurement module measures a machined contour of the S-shaped test piece and records same; the detection module detects the degree of wear and the temperature of a tool during machining; the analysis module uses a multivariate regression model to perform analysis on the basis of an error between the machined contour and the programmed contour and the detection result of the detection module and determines the weight of an error factor; and the parameter optimization module adjusts execution parameters of the execution module in real time on the basis of the multivariate regression model. By means of various modules, the tool is monitored in real time and the tool path is optimized, thereby improving the precision and quality of a numerical control machine tool in mold processing, and at the same time improving the quality of products produced by a mold.

Description

A numerical control machine tool system for precision injection mold processing TECHNICAL FIELD

[0001] The present application belongs to the technical field of numerical control machine tool systems, and particularly relates to a numerical control machine tool system for precision injection mold processing. BACKGROUND

[0002] At present, building block toys on the market, such as plastic particle building block toys, are generally connected through the interference fit between two parts. The connection tightness is realized through the part tolerance. This connection method puts high requirements on mold precision manufacturing and injection molding production, resulting in high production cost of building block parts, poor part consistency, different building strength, and ultimately poor user experience.

[0003] In order to improve the machining precision of the mold during the manufacturing process, the existing numerical control machine tool usually generates an ideal machining path and shape through the CAM system, which is calculated based on the design model and requirements. Moreover, the CAM system can automatically generate the machining path and tool trajectory of the numerical control machine tool according to the three-dimensional model data of the workpiece, and the simulated machining path and programmed contour in the CAM system. The smaller the error between the machining contour and the programmed contour in the actual machining process indicates the machining precision. Thus, the precision of the mold on the model during the machining process can be ensured, and high-precision mold manufacturing can be completed by controlling the error in the machining process.

[0004] However, in the actual machining process, the machining contour is affected by various factors, and the main factors causing errors are static errors and dynamic errors. Static errors can be directly detected by instruments such as laser interferometers, ball bar instruments, and R-test instruments. The dynamic error is detected by the S-shaped test piece widely used in the industry to detect the dynamic error of the machine tool. The dynamic error is controlled to control the mold precision during the final machining process. However, due to the complex causes and components of dynamic error, including thermal error, system control error, etc., the machine tool thermal error accounts for about 40%-70% of the total machining error of the machine tool. Therefore, in the process of high-precision mold manufacturing, the error range of the mold cannot be accurately controlled. SUMMARY

[0005] To solve the above problems in the prior art, the present application provides a numerical control machine tool system for precision injection mold processing, which solves the problem that the existing numerical control machine tool cannot accurately control the error range of the mold due to the influence of dynamic error during the manufacturing of high-precision molds.

[0006] The purpose of the application can be realized by the technical scheme: a numerical control machine tool system for precision injection mold processing, comprising a CAM system and a detection module, a measurement module, an execution module, an analysis module and a parameter optimization module connected with the CAM system, the CAM system provides the programming profile of the S-shaped test piece three-dimensional model, the execution module processes according to the programming profile, the measurement module measures the processing profile of the S-shaped test piece and records, the detection module detects the wear degree and temperature of the tool in the processing process, the analysis module adopts a multiple regression model to analyze and determine the error weight according to the error between the processing profile and the programming profile and the detection result of the detection module, and the parameter optimization module adjusts the execution parameters of the execution module in real time according to the multiple regression model.

[0007] As a preferred technical scheme of the application, the detection module comprises a visual detection unit and an infrared detection unit, the visual detection unit monitors the tool wear in real time, and the infrared detection unit detects the temperature in the machine tool in real time.

[0008] As a preferred technical scheme of the application, it further comprises a compensation module, which adjusts the length parameter of the tool in the programming profile in real time according to the error weight of the analysis module and the detection result of the detection module.

[0009] As a preferred technical scheme of the application, the error between the processing profile and the programming profile in the multiple regression model is used as the dependent variable, and the wear degree of the tool and the temperature of the tool in the processing process are used as the independent variables.

[0010] As a preferred technical scheme of the application, the measurement items of the measurement module include S-shaped edge strip thickness error, S-shaped edge strip indentation, convex edge, local defects of vibration lines and S-shaped edge strip profile error.

[0011] As a preferred technical scheme of the application, the measurement module obtains the three-dimensional data points of the workpiece by laser scanning the S-shaped test piece to convert into a three-dimensional profile.

[0012] As a preferred technical scheme of the application, the execution parameters of the execution module include the positioning parameters of the linear shaft of the machine tool and the coordinate parameters of the rotating shaft.

[0013] As a preferred technical scheme of the application, it further comprises an interpolation module, which adjusts the execution parameters of the linear shaft of the machine tool in the execution module according to the measurement result of the measurement module and the error weight of the analysis module.

[0014] As a preferred technical scheme of the application, the CAM system, the detection module, the measurement module, the execution module, the analysis module, the interpolation module and the parameter optimization module are connected through Modbus protocol respectively.

[0015] The beneficial effects of the present application are: the CAM system provides the programming profile of the S-shaped test piece, the execution module processes according to the programming profile and obtains the processing profile through the measurement module, the detection module detects the wear degree and temperature of the tool during processing, the analysis module analyzes the error between the processing profile and the programming profile and the detection results of the detection module by using a multiple regression model and determines the weight of the error factors, and the parameter optimization module adjusts the execution parameters in the execution module in real time according to the weight of each factor, through the cooperation of each module, the tool is monitored in real time and the tool path is optimized, thereby improving the precision and quality of the numerical control machine tool in mold processing, further improving the quality of the products produced through the mold, and solving the problem that the existing numerical control machine tool cannot accurately control the error range of the mold due to the influence of dynamic error during the manufacture of high-precision molds. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to facilitate the understanding of those skilled in the art, the present application will be further described below in conjunction with the drawings.

[0017] Fig. 1 is a schematic diagram of the numerical control machine tool system of the present application. DETAILED DESCRIPTION

[0018] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined application purpose, the specific embodiments, structures, features and effects according to the present application are described in detail as follows in conjunction with the drawings and preferred embodiments.

[0019] Before the high-precision mold is made, the numerical control machine tool first makes an S-shaped test piece to obtain the dynamic error of the machine tool, and then adjusts the execution parameters of the machine tool in real time according to the dynamic error, and ensures the machining precision of the numerical control machine tool through the precision of the S-shaped test piece that appears during machining, so as to ensure that the machining error range of the mold can be accurately controlled when the high-precision mold is machined subsequently. Because the detection of the S-shaped test piece has been included in the ISO10791-7 standard, in order to ensure that the machining error range of the high-precision mold can be accurately controlled during the manufacturing process, please refer to Figure 1, the embodiment provides a numerical control machine tool system for precise injection mold machining, which comprises a CAM system and a detection module, a measurement module, an execution module, an analysis module and a parameter optimization module in communication connection with the CAM system, and the data interfaces between the above-mentioned modules transmit parameters, results and information, so as to realize data sharing and process control between the modules. Through connection, an organic whole is formed between each module, which can realize data sharing, transmission and processing, the CAM system provides the programming contour of the S-shaped test piece three-dimensional model, and then the execution module processes according to the programming contour. In the processing process, the measurement module measures and records the processing contour of the S-shaped test piece, and the detection module detects the wear degree and temperature of the tool during processing at the same time. The measurement module and the detection module will transmit the obtained data to the analysis module in real time, the analysis module adopts a multiple regression model to analyze the error between the processing contour and the programming contour and the detection results of the detection module and determines the error weight, and then the parameter optimization module adjusts the execution parameters of the execution module in real time according to the multiple regression model in the analysis module, so as to complete the processing of the S-shaped test piece, and the machining error of the machine tool during processing can be compensated in real time, thereby reducing the influence of dynamic error on the machining process.

[0020] During the machining process, the wear of the tool and the error between the processing contour and the programming contour are the main factors causing the machining error, and the wear of the tool is mainly affected by the thermal error of the machine tool. Because the tool will generate high temperature during the continuous cutting process during machining, the temperature will further accelerate the wear degree of the tool, and the temperature will also cause the thermal expansion and contraction of the machine tool, thereby causing errors. Through the analysis module, the wear and temperature of the tool are analyzed to determine which one has a greater influence on the machining precision of the whole, so that the parameter optimization module is adjusted to improve the machining precision of the numerical control machine tool.

[0021] And the existing numerical control machine tool in the process of making mold, ensure the consistency of programming profile and machining profile is essential. Because the consistency of programming profile and machining profile means the degree of conformity between the actual processing result and the design intention. If the two are highly consistent, it means that the machining precision is high, and the product quality is good; on the contrary, if there is a large deviation, it may lead to substandard product quality, and even cause waste. Therefore, the error between the two is used as the correction standard to improve the machining precision in the machining process.

[0022] In order to better detect the wear degree of the tool and the temperature in the machine tool, and at the same time reduce the machining error caused by the detection error, in an embodiment, the detection module includes a visual detection unit and an infrared detection unit. The visual detection unit monitors the tool wear in real time, and the infrared detection unit detects the temperature in the machine tool in real time. The wear degree of the tool and the temperature in the machine tool are detected in real time by the visual detection unit and the infrared detection unit respectively, so as to reduce the detection error caused by the detection module itself, and to avoid affecting the machining precision.

[0023] When the parameter optimization module adjusts the execution parameters of the execution module, if the tool wear weight is large at this time, in order to reduce the machining error caused by tool wear, in an embodiment, a compensation module is further included. The compensation module adjusts the length parameter of the tool in the programming profile in real time according to the error weight of the analysis module and the detection result of the detection module. When the error caused by tool wear has exceeded the error range of machining, the tool length in the programming profile is adjusted by the compensation module, so as to correct the position of the tool in the subsequent machining profile, and reduce the machining error caused by tool wear.

[0024] In order to make the analysis module can output the best parameter combination, so as to realize the accurate control of numerical control machine tool machining, in an embodiment, the error between the machining profile and the programming profile in the multiple regression model is used as the dependent variable, and the wear degree of the tool and the temperature of the tool in the machining process are used as the independent variables. The above two variables are substituted into the regression model, the model is fitted, that is, the weight of each error factor is determined. Through the determined weight value, unknown data can be predicted, so as to predict the error result that may be produced under different error factor combinations, so as to optimize the output of the best parameter combination. Thus, the machining precision is improved.

[0025] In order to better obtain the dynamic error of the machine tool by processing the S-shaped test piece, and reduce the dynamic error of the machine tool by adjusting the parameters of the execution module in real time, in an embodiment, the measurement items of the measurement module include the S-shaped edge strip thickness error, the S-shaped edge strip indentation, the local defects of the convex edge and the vibration pattern, and the S-shaped edge strip profile error, because the S-shaped test piece is a special processing part similar to an S-shaped part, which has a complex shape composed of two curved planes, and can be used to detect the dynamic error of the five-axis machine tool on different coordinate axes. When the S-shaped test piece is processed on the machine tool workbench, due to its special shape and large curvature change, the errors of each axis can be displayed and recorded during the processing, and can be corrected by dynamic compensation software. Therefore, by detecting the S-shaped edge strip thickness error, the S-shaped edge strip indentation, the local defects of the convex edge and the vibration pattern, and the S-shaped edge strip profile error, the errors of each axis of the machine tool in the actual processing process can be obtained, thereby improving the overall processing precision.

[0026] In order to avoid the influence of the error caused by the detection result on the adjusted parameter value during the detection process of the S-shaped test piece, in an embodiment, the measurement module obtains the three-dimensional data points of the workpiece by laser scanning the S-shaped test piece to convert into a three-dimensional profile, acquires the three-dimensional data points of the workpiece profile by laser scanning, and simulates the three-dimensional machining profile of the workpiece according to the three-dimensional data points; thereby completing the comparison between the machining profile and the programmed profile, obtaining the error between the two profiles, and adjusting the execution parameters of the execution module.

[0027] Meanwhile, the laser scanning selects a phase scanner to acquire the point cloud data of the workpiece surface by using a continuous wave laser and a phase measurement technology. The continuous wave laser emitted by the laser will be reflected back after hitting the workpiece surface, and by comparing the phase difference between the reflected laser wave and the reference laser wave, the distance and angle information of the workpiece surface point to the laser emitter can be calculated, thereby constructing a three-dimensional model of the workpiece. The measurement and analysis unit preferably carries GeomagicQualify software to calculate the difference value between the machining profile and the programmed profile.

[0028] In order to better adjust the parameters in the execution module to improve the processing precision, in an embodiment, the execution parameters of the execution module include the positioning parameters of the linear axes of the machine tool and the coordinate parameters of the rotary axes, wherein the linear axes, the rotary axes and the main shaft of the machine tool are three important components of the machine tool.

[0029] Linear axes: Linear axes are the axes that move linearly on a machine tool, usually including X-axis, Y-axis, and Z-axis. They move through linear guides or slides to achieve linear movement of the workpiece. Linear axes often face thermal error problems, mainly due to the heat generated by the machine tool during operation, which causes the linear axes to expand to some extent, affecting the machining precision. Rotary axes: Rotary axes are the axes that rotate on a machine tool, including A-axis, B-axis, C-axis, etc. Different rotary axes can achieve rotation of the workpiece in different directions, allowing the machine tool to perform multi-angle and multi-directional machining. Rotary axes also face thermal error problems, but they usually have less impact than linear axes. Spindle: Spindle is one of the most important components of a machine tool, which can achieve rotary machining of the workpiece. Spindle is usually ground or carefully machined to meet precision requirements. The rotational speed and precision of the spindle have a very important influence on the quality and efficiency of machining. The spindle also generates heat during high-speed operation, but the thermal error of the spindle is much smaller than that of linear and rotary axes.

[0030] Therefore, when adjusting the parameters in the execution module, the positioning parameters of the linear axes of the machine tool and the coordinate parameters of the rotary axes are adjusted to reduce the errors generated during machining, so that the machined parts can be within the error range.

[0031] Since the temperature inside the machine tool has the greatest impact on the linear axes, and is also the parameter that affects the machining precision the most, in order to further reduce the machining errors caused by the linear axes, in an embodiment, an interpolation module is also included, which adjusts the execution parameters of the linear axes of the machine tool in the execution module according to the measurement results of the measurement module and the error weights analyzed by the analysis module. When the numerical control system calculates the position, speed, and acceleration of each axis for each time step based on the input tool trajectory and machining path, and controls the servo system to move accurately according to the specified path, the interpolation module adjusts the execution parameters of the linear axes of the machine tool in the execution module according to the error weights analyzed by the analysis module, further reducing the errors caused by the linear axes being affected by temperature.

[0032] Since data connection is needed between the modules, and in order to reduce the influence on machining precision caused by the delay, network fluctuation and other factors during data transmission, in an embodiment, the CAM system, the detection module, the measurement module, the execution module, the analysis module, the compensation module, the interpolation module and the parameter optimization module are connected through Modbus protocol. Modbus protocol has simple structure, is easy to implement and understand. It uses standard CRC check to ensure the reliability of communication, and Modbus protocol supports multiple physical media and communication modes, including serial port, Ethernet and the like, and can communicate between different platforms and devices. Meanwhile, Modbus protocol supports master-slave mode and multipoint communication, and can realize communication and cooperative work between multiple devices. Meanwhile, it also supports batch read and write operation of multiple registers, and improves the communication efficiency. Therefore, data transmission through Modbus protocol can avoid machining error caused by data transmission.

[0033] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed as above with reference to the preferred embodiment, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes, without departing from the technical solution of the present application. Any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present application still falls within the scope of the technical solution of the present application.

Claims

1. A precision injection mold machining numerical control machine tool system, characterized by: The CAM system, the detection module, the measurement module, the execution module, the analysis module and the parameter optimization module are connected in communication, the CAM system provides the programmed profile of the three-dimensional model of the S-shaped test piece, the execution module processes according to the programmed profile, the measurement module measures and records the processing profile of the S-shaped test piece, the detection module detects the wear degree and temperature of the tool in the processing process, the analysis module analyzes and determines the weight of the error factors according to the error between the processing profile and the programmed profile and the detection result of the detection module by using the multiple regression model, and the parameter optimization module adjusts the execution parameters of the execution module in real time according to the multiple regression model. The error between the processing profile and the programmed profile in the multiple regression model is used as the dependent variable, and the wear degree of the tool and the temperature of the tool in the processing process are used as the independent variables. The measurement items of the measurement module include the local defects of the S-shaped edge strip thickness error, the S-shaped edge strip indentation, the convex rib and the vibration mark, and the S-shaped edge strip profile error.

2. The CNC machine tool system for precision injection mold machining according to claim 1, characterized in that: The detection module includes a visual detection unit and an infrared detection unit, the visual detection unit monitors the tool wear in real time, and the infrared detection unit detects the temperature in the machine tool in real time.

3. The precision injection mold machining CNC machine system of claim 2, wherein: The compensation module adjusts the length parameter of the tool in the programmed profile in real time according to the error weight of the analysis module and the detection result of the detection module.

4. The CNC machine tool system for precision injection mold machining of claim 1, wherein: The measurement module obtains the three-dimensional data points of the workpiece by laser scanning the S-shaped test piece and converts them into a three-dimensional profile.

5. The CNC machine tool system for precision injection mold machining of claim 1, wherein: The execution parameters of the execution module include the positioning parameters of the linear shaft of the machine tool and the coordinate parameters of the rotating shaft.

6. The precision injection mold machining CNC machine tool system of claim 5, wherein: The interpolation module adjusts the execution parameters of the linear shaft of the machine tool in the execution module according to the measurement result of the measurement module and the error weight analyzed by the analysis module.

7. The CNC machine tool system for precision injection mold machining of claim 1, wherein: The CAM system, the detection module, the measurement module, the execution module, the analysis module, the interpolation module and the parameter optimization module are connected by Modbus protocol.

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