As a representative of advanced productivity in machinery manufacturing, CNC machining has played a huge role in the automotive, aerospace, aerospace and mold industries after more than 10 years of introduction and development. CNC programming is an important aspect that affects the quality and efficiency of CNC machining, especially in high-speed and precision machining. In the machinery industry, because the level of CNC programmers is different, it is necessary to establish certain specifications so that everyone can avoid low-level errors and repetitive problems.
First, the NC machining programming process The general process of NC machining programming includes: determining the programming basis, establishing the process model, defining the machining operation, generating the tool path trajectory, machining path simulation, post-processing, numerical control machining program simulation, CNC machining program proofreading, Distribute on-site machining and CNC machining program finalization. The specific preparation process is as shown.
1. Determining programming According to CNC programming, including 3D model, engineering drawings and parts manufacturing instructions (CNC process specification), the following information can be obtained through NC programming: part information, CNC machining process plan, CNC machine type, clamping positioning method , tools, processes and work steps, machining program numbers and product processing status.
2. Establishing the process model The design of the process model is based on the 3D model of the part and the engineering drawings, including: trimming the 3D model of the part, establishing the process reference surface, establishing the process positioning hole, pressing plate and position design, and the margin of the machining surface. Processing and so on.
3. Define the machining operation to generate the tool position trajectory to define the machining operation and generate the tool position trajectory. The main contents include: defining the programming coordinate system, taking into account factors such as the material properties of the machine, the cutting characteristics of the tool, the cutting characteristics of the machine tool and the material condition that the parts need to be removed. According to the process requirements, the machining method (including various cutting strategies, etc.), process parameters (including margin, feed rate, spindle speed and span of the machining path), and auxiliary attributes (including the tool point, safety surface and CNC machine tool attributes, etc., finally generate the tool path.
4. Machining trajectory simulation verification The main content of the machining trajectory simulation verification includes: checking whether the definition of the tool, machine tool, workpiece and fixture is complete, and whether the size is accurate; checking the machining operation, defining whether the size of the part that should be achieved in each operation is correct; checking the definition of the machining operation Whether the processing methods (such as roughing strategy, tool offset machining and cavity machining) are correct and reasonable; check whether there is overcut or undercut between the CNC machine table, the machined parts, the tool and the fixture during the machining process. Or collision interference and other issues; check whether the process parameters are reasonable.
5. Post-processing Post-processing can be an independent process, or it can be integrated with the tool location generation process. According to the function of the processing software, the appropriate processing method is selected, and the following requirements are required for post-processing: To generate a specific CNC system-specific machining program, select its specific post-processing software; post-processing software development or customization, combined with specific control system and machine motion structure type; post-processing software to ensure tool position processing information Full conversion, and meet the requirements of the control system syntax; post-processing, automatically add the necessary annotations to the processing program.
6. Numerical control machining program simulation verification On the basis of programming software or combined with the function of numerical control simulation software (Vericut), verify all aspects involved in the numerical control machining program as much as possible to ensure the correctness of the final machining program, and correspondingly The NC machining program simulation verification is recorded. The simulation verification mainly includes the following contents: checking whether the annotation information is correct in the machining program; checking whether the selection of the machining mode is correct in the numerical control machining program; checking whether the tool size information is correct in the machining program; checking each process in the numerical control machining program Whether the part size information should be correct; check whether the tool compensation information is correct in the NC machining program; check whether there are overcutting, undercutting or collision interference in the CNC machining program; check the spindle speed and advance in the CNC machining program. Whether the speed is matched with the current CNC machine tool, etc.
7. CNC machining program proofreading The proofreading of the NC program is completely different from the proofreading of the process documents. The program format is a coordinate point. If the program content is proofed line by line, it takes a lot of time and it is unrealistic. Proofreading of the program is mainly considered from the following aspects. 1 model. The model is the basic element to ensure the correctness of the program. It is necessary to proofread the correctness of the model, and whether all the data of the analysis model are consistent with the elements of the process file. 2 coordinate system. Check that the programmed machining coordinate system direction matches the requirements of the process documentation, whether it is easy to operate, whether the coordinate system selection is reasonable, and whether it is convenient to control the size. 3 processing strategy. The programs generated by different processing strategies are absolutely different, the program size is also different, and the rationality of the analysis processing strategy is mainly to control the tool path of the program and control the processing quality and efficiency. 4 tools. Tool materials, specifications and forms are determined according to the material of the part and the machining location of the part. Different tools directly affect the machining efficiency and processing quality. 5 infeed point and retract point. The infeed point and the retract point are the main factors that cause the knife to be scratched and stabbed, and are also an important aspect that affects the surface quality. 6 program format. Different CNC systems have different format requirements for the program. Generally, the processing program that meets the requirements of different control systems can be generated by editing the post-processing program. The proofreading of the program format is mainly at the beginning and the end of the program, and does not affect the processing quality of the program.
The NC program must be complete, correct, uniform and coordinated to ensure that the operator can use the program correctly and process the qualified product. The NC machining program should ensure the rationality, safety and stability of the entire process.
8. CNC program on-site trial processing and machining program shaping For some parts with complex process, difficult processing, high dimensional accuracy or large batch size, it is necessary to organize CNC programmers, workshop process supervisors, operators and inspectors to conduct on-site trials. The machining situation is tracked and recorded to instantly correct unreasonable clamping positioning methods and cutting parameters. For some single-piece parts, in the case of good manufacturability and low dimensional accuracy, try-cut machining should be avoided as much as possible. Instead, the problem should be found and corrected in the CNC machining simulation to improve programming efficiency and reduce production costs. For mass-produced parts, the NC machining program should be finalized and managed in a unified manner after the first batch is produced.
Second, the NC program and manufacturing outline (FO) management 1. The NC program is named for easy access, easy to identify, call and manage, the first NC program file must be properly named. CNC machine tools have different coding ratios, and generally only recognize numbers and letters. Different CNC systems recognize different program formats. Therefore, the form of the NC program naming is generally: name + suffix.
(1) The name composition is generally: product code _ processing type + process number _ program version. The “product code†is the reference number of the referenced part: “machining type†is whether it is milling (M) or car (L): “operation number†is the process number in the process file: “program version†The new version (NEW) can be managed by 001, 002, etc. after the version change.
(2) Suffix composition: generally txt, mpf, etc.
(3) Numerical control program naming example: A product code is D25?1155?12? 00, there are three processes that require CNC machining, of which process 15 is a CNC milling process, the first NC program is programmed, and its corresponding NC program The name of the file in the library is as shown.
(4) The naming of the NC program is in accordance with the requirements of the control system, and is easy to identify, call and manage.
2. Tool naming When programming the machining process, it is necessary to define various tool types, tool materials and geometric parameters of the tool itself. Before the cutting parameter database is established, it can only be manually input, so the efficiency is low, and the completion is only a simple repetitive work. The resulting program is not intuitive to the operator and requires a high level of craftsmanship. Through the experience summary in the actual processing, the processing database can be established by the corresponding CAM software (NX software), which can be directly called from the library in later operations. To create a library, you should first define the tool number. For easy identification, you can use the following method in the NX tool library.
(1) End mill: LX+D+ diameter + L+ tool extension length + La + tool edge length + Z + edge number + R + bottom tooth radius. For example, LXD25L50La25Z3R1.5_L7 means: the diameter of the end mill is 25mm, the working length is required to be minimum 50mm, the blade length is required to be minimum 25mm, the number of blades is 3, and the bottom angle is R1.5mm; L7 is processing 7075 imported aluminum.
(2) Drill bit: ZT+D+ diameter + tool extension length + La + tool blade length + Z + blade number + J + drill angle. For example, ZTD6.5L30La20Z2J120 means: the diameter of the drill is 6.5mm, the working length is required to be minimum 30mm, the blade length is required to be minimum 20mm, the number of blades is 2, and the drill angle is 120°.
In the case of the rear, the tool information is required to be output together, which prevents the operator from running the program without missing the tool number or the tool length. Its main purpose is to establish a unified standard for NC programming and program simulation, and also facilitate the uniform distribution and proofreading of tools.
3. The content of the NC machining process requires that in the manufacturing outline (FO), it is necessary to put forward some requirements for the content of the NC machining process to prevent the manufacturing outline (FO) from being inconsistent with the NC program, resulting in the scrapping of the parts.
The specific requirements are as follows: (1) Clearly mark the clamping positioning surface of the blank or part and the workpiece coordinate origin and coordinate system, and ensure that the coordinate origin and coordinate system are consistent with the machining program; (2) clearly indicate the pressing plate pressing parts Or the position of the blank and the limit height of the top surface of the platen bolt; (3) Briefly describe the necessary specifications of the required tool and the parts of the part to be machined; (4) The numerical control program to accurately represent the machined part Name; (5) to accurately express the tooling for processing the part.
III. Conclusion CNC technology, as an advanced manufacturing technology for many years, has a high technical content and involves many aspects, especially the rapid and efficient CNC machining programming, the application of high-speed cutting, the standardization and standardization of NC programming. Index number: 122 In the operation of CNC lathe, to reach the level of senior workers and technicians, we must solve several difficult problems, including the following four aspects: 1 profiling; 2 trapezoidal thread processing; 3 non-circular curve Processing; 4 assembly processing. Take SIEMENS 802S as an example to solve them separately.
1. Profiling processing As shown in the handle parts, the main structural features are the forming surface and the concave shape of the contour. The sharp knife can be used, and the contour processing is used. The route is as shown in the figure, and the cutting is performed from large to small layer to the end. carry out.
Here are two programming methods: G91 incremental subroutine loop cutting method and G158 coordinate shift command program loop cutting method.
1. G91 incremental subroutine cycle cutting method (1) processing analysis. Since each path is the same as the contour, a cyclic cutting method is used. After the outline is shifted outward by a certain distance, the absolute coordinate X of each point increases. Although it is difficult to calculate and determine the coordinates because of the point, the relative position between the points is fixed, and the coordinate increment does not change. That is, the relative coordinates are not changed, so only the relative coordinates can be used in programming. As long as the starting point of the cycle is close to the workpiece, layered profiling can be achieved.
In the operation of CNC lathe, to reach the level of senior workers and technicians, we will certainly encounter a series of difficult problems. This paper selects several aspects and analyzes and solves with examples, hoping to improve the skills of CNC car.
Several difficult points in the processing of advanced CNC machining â–¡ Gong Linrong, the professional secondary school of Shuyang County, Hunan Province, and the incremental coordinates and processing route of each point? The efficiency of CNC machining technology is largely related to the company's own technology management model. The standardization and standardization of NC machining program embodies the application level of CNC machining technology to a certain extent. It regulates the diversification of NC program by standardization and improves the quality of tool path. For example, the positioning reference is specified in the process documentation. Tool reference, coordinate system, tool parameters and cutting parameters; program programming can be standardized from 2D contour machining, 3D surface machining, fixed cycle, tool compensation and tool path machining strategy; On the basis of experience, the establishment of standardized and standardized NC program templates can greatly improve the programming quality and product processing efficiency. For the successful product processing technology and CNC machining experience of the enterprise, it can be saved in the form of template, which is beneficial to the reuse of resources and also as a resource for technical exchange. Therefore, the effective CNC machining process and the use of CNC programming templates and corresponding specifications can greatly reduce quality accidents, reduce costs and improve processing efficiency.
(Finish)
Seamless steel pipe is a tubular section or hollow cylinder, usually but not necessarily of circular cross-section, used mainly to convey substances which can flow - liquids and gases (fluids), slurries, powders and masses of small solids.Steel Pipe & Tubing seem similar at first blush and in fact they share many characteristics but they also have some important differences.
Steel Tubing is a hollow steel shape intended for structural purposes and made from carbon, stainless, or galvanized steel.
Pipe is a hollow structure that is intended to carry material such as liquids, gasses, or even solids. Its wall thickness is described by its Schedule and it is often broken down by type using the method of manufacturing it, either ERW or Seamless.
Seamless Steel Pipe, A106 Seamless Pipe, Carbon Steel Seamless Pipe, A53 Seamless Pipe, Mild Steel Pipe
Shandong Guanzhou Iron and Steel Group Co., Ltd , https://www.cnshansteel.com