Application analysis of machining technology of CNC turning and milling center

Application analysis of machining technology of CNC turning and milling center

1 Introduction to turning and milling machine

Turning and milling is a multi-functional machine tool that can complete rotation and milling operations at the same time, and the turning and milling machine usually has two main components: a spindle and a cutter tower. The spindle is used to provide rotary power and can be used to grip the workpiece and perform turning operations. The cutter tower is used for clamping tools, including milling cutters, drills, etc., to carry out milling, boring and drilling operations, machining efficiency and tooling adjustment flexibility are guaranteed, mainly used in modern manufacturing. With the development of The Times, automation technology, intelligent technology and information technology are widely used in various fields, CNC milling technology as the most important manufacturing technology in CNC automation technology, in the application process can not only improve the quality of product processing, but also ensure the mechanical processing production treatment effect. However, it is more susceptible to external factors in the actual operation process, and should continue to improve the processing technology in the future, and do a good job in site management.

2 CNC turning and milling classification

2.1 Axial turn-milling

The axial turn-milling processing range is large, can complete the outer circular surface processing, can also complete the inner hole surface processing, because the axial turn-milling tool and the workpiece rotation axis are in a parallel state, but the process also has a short plate, that is, the tool longitudinal and stroke will be limited, and this is mainly affected by the milling tool diameter than the radial size of the spindle box. If this situation occurs in the processing process, the processing process should be changed in time, if the axial turning mill continues to be used, it will not only affect the quality of parts, can not meet the production requirements, but also may cause some equipment damage.

2.2 Orthogonal turn-milling

Orthogonal turn milling means that the rotation axis of the turning tool is perpendicular to the rotation axis of the workpiece, and the cutting track of the turning mill is a space curve, its shape is more complex, and the instantaneous cutting depth and cutting thickness will change with the change of the tool axis and the rotation direction. For turning milling, some parts of the processing process is very complicated, and will be applied to a variety of processes, different process parameters will be different, in order to fully ensure the quality of production, we should first straighten out the parameter relationship, and reasonable combination of various process parameters. If the orthogonal turn-milling function is fully used in the production process, the machining quality of turn-milling surface can be effectively improved.

3 Application analysis of CNC turning center milling processing technology

3.1 Analysis of machining elements of CNC turn-milling center milling

Before the CNC turning and milling work, it is necessary to analyze various factors in this regard, because the CNC programming module is more complex, the overall application effect also needs to show technical and flexible, so it is necessary to consider the machine tool factor, workpiece factor, tool and fixture factor, etc., as follows:

First, machine tool factor analysis. In this respect, machine power, machine coolant and machine tool maintenance are based on the testing to determine the quality of the milling machine itself, such as hardness, power, etc., if these indicators do not reach the standard, it is not possible to ensure product quality in the actual product processing process. In terms of coolant, first of all, it is necessary to scientifically select coolant according to the actual needs, and then pay attention to the flow of the cooling medium. If the coolant is not applied in production, the operator should do a good job in the daily maintenance of the milling cutter to avoid the phenomenon of stuttering in practical application;

Second, the workpiece factor analysis. When applying the CNC programming process, the workpiece factors should be comprehensively considered, including the workpiece assembly state, repeated positioning, especially positioning, which must be fully ensured that it has accuracy, otherwise the product is very prone to defects. In addition, the cutting tools and materials should be reasonably distributed to ensure that the workpiece size, blank size, surface quality and other aspects meet the production needs;

Three, tool and fixture factor analysis. First of all, the diameter of the milling cutter should be determined, and then the forward Angle blade should be selected as far as possible, because this blade can not onl‘’y reduce power consumption, but also improve the smoothness of the plane, and then select the tool, to the production requirements of the product as an indicator, to ensure the production accuracy of the product for the purpose of scientific selection of the tool shape, material, and finally determine the main Angle.

3.2 Preparation work for CNC milling

China's machine tool industry is extremely strict, not only requires the production quality of various parts, but also has strict requirements for the operation specifications of the milling machine, in the process of CNC milling, it is necessary to avoid human intervention as far as possible, and do a good job of preparation. First of all, we need to clean the workbench and fixture, although CNC milling is mainly based on mechanical equipment, there are still many operators on the site to assist production, in order to ensure the life and health of personnel and safety, but also to reduce equipment failure, the site must do a good job of cleaning. Because the milling machine will produce metal fragments when running, the fragments are very sharp, if not cleaned in time it is easy to cut the operator, and the longer the metal fragments stay in the workbench, the more it will affect the accuracy of the product, timely cleaning can effectively avoid such situations. In addition to cleaning the workbench, the fixture is also the key cleaning object, the jaws, base, clamp and other places are easy to stick to small iron filings, if not treated in time, it will inevitably reduce the production accuracy when used again. If these fixtures appear convex phenomenon, the working state of the fixture itself will continue to reduce, and even lead to the scrapping and rework of some products, which will bring economic losses to manufacturing enterprises, but also affect the processing progress. Secondly, it is necessary to check the blank parts, which can directly affect the machining accuracy of the machine tool. During the inspection, the main work content is whether there is damage to the parts, and if the parts are found damaged, they should be replaced immediately.

3.3 CNC milling process analysis

CNC milling and manual milling are mechanical manufacturing processes, and CNC is programmed by computer to achieve automatic control of the processing process, there are big differences between the two, for CNC milling process, whether the preparation process is reasonable will determine the success or failure of CNC milling technology. In this process should do the following aspects of work:

One, dimensioning. When designing and programming, the advantages of CNC technology should be flexibly applied to clarify the dimensions and positions of all points, lines and surfaces of the products, and do a good job of marking at the same time;

Second, analyze the elements. As a programmer, they should first clarify the various influencing elements of the process, understand the parameter relationship, and ensure the rationality of programming. In the process of product design, the designer should check the drawings in detail, and if any problem is found, it should be timely reflected with the superior leadership, and timely adjusted after getting feedback.

Three, precise positioning. In view of the relatively concentrated processing procedures in the CNC milling process, it is particularly important to use the positioning work under the same benchmark, and it is necessary to ensure the accuracy of each positioning, otherwise it will inevitably cause adverse effects on subsequent processing operations;

Fourth, uniform type and size.

CNC milling machine operation should maintain continuity, avoid frequent interruption of operations, in addition, the quality of the tool should be fully guaranteed, determine the tool and installation after the completion of daily care work, reduce the number of replacement, at the same time, through a variety of ways to shorten the process time. In order to achieve the above purpose, first of all should unify the form and size, so that a large number of times can be achieved, but it should be noted that some parts in the production of parts have special requirements for the shape, such as to reflect the geometric symmetry of the shape, at this time you can complete this operation through the CNC mirror function, reduce the trouble of CNC milling programming.

3.4 CNC milling machining parts clamping and positioning analysis

Before the formal production, the CNC milling machine should place the workpiece on the corresponding fixture or machine tool, and then do a good job of fixing the work, so as not to shift the workpiece due to vibration during the processing. In order to improve the effect, the operator should have the ability to operate the equipment flexibly, so that a clamp, if a clamp is not successful, the operator needs to manually adjust, but the manual operation is difficult to ensure accuracy, and the operation speed is slow, and has a certain risk, so the actual production activities will try to avoid this situation.

3.5 Determine CNC milling machine tool selection and cutting amount

Whether it is the cutting tool or the cutting amount, if the selection is unreasonable, it will affect the machining effect of the machine tool. In addition, the tool selection during transportation operations will also affect the processing accuracy, so when selecting the tool, it is necessary to start from the processing Angle, especially for the CNC milling machine, the tool used must have the advantages of high precision, high strength, high rigidity, high durability, easy installation and easy adjustment. When in the processing environment, the specific requirements of the workpiece processing is the only standard for tool selection, in general, the selection of the tool will be combined with the workpiece geometric parameters. However, if it is a closed keyway, this way will be difficult to play a role, at this time to the keyway milling cutter, if the product is required to be refined, it should be based on four-sided blades. When determining the cutting parameters, it should first be clear which influencing factors are mainly included in this aspect, such as cutting amount, cutting speed and spindle speed, etc., if you want to determine the milling machine, you should also consider its application life, the service life is divided into two kinds, one is the minimum economic life, the other is the maximum working life. Many machinery manufacturing enterprises will take economic benefits as the main consideration when receiving orders, but if the production task is too urgent, it is necessary to take the best cutting power as the primary condition.

3.6 Select CNC milling tool and feed method

In order to fully improve the machining quality of CNC milling operations, the tool path must not be ignored. Tool path can often directly affect the process effect, in the selection of tool path, machine tool parts processing accuracy, external roughness matching degree are the influencing factors, at this time only to shorten the tool running path, reduce the empty edge in the tool path, in order to ensure the processing effect. If two adjacent tool paths are connected with the ramp, the arc radius should be increased to avoid direct crossing, and the tool can automatically track the next processing route. If the cutter path is the same, it is necessary to take measures in the arc radius to keep it in motion, which can not only ensure that the CNC milling machine tool position trajectory is smooth, but also reduce the resistance during tool operation and avoid tool wear. The arc transition process has a good application effect in this respect, because it can effectively complete the workpiece tangent operation and comprehensively improve the quality of CNC milling. The selection range of the cutting method is small, usually in the longitudinal and spiral two ways to choose, the longitudinal feeding method is more damaging to the tool, because its milling cutter, mold cutting force is larger than the spiral way. Therefore, the actual production activities in the spiral mode selection probability is large, in the application of the feeding method, it is necessary to scientifically set the cutting amount, reasonable set screw diameter, while regulating the operation process, so as to avoid damage to the tool due to illegal operations or unreasonable operation.

3.7 Optimization of CNC milling programming process

CNC milling engineering, CNC machine tools can often play a huge role, so in addition to making a reasonable choice, should also pay attention to programming work, and according to the needs of the industry to continuously optimize the CNC milling programming process, first of all, the use of standardized programming methods and specifications to ensure the consistency and efficiency of the programming process, Such as using uniform naming conventions, comments and documentation requirements, and following a conventional programming style; Secondly, using computer aided manufacturing (CAM) software or other programming tools, write automated programs to generate CNC milling process code, improve programming speed and accuracy; Then, adjust the tool path and trajectory planning, optimize the cutting path and feed speed to minimize cutting time, prevent collisions, and improve cutting efficiency and accuracy, using advanced path optimization algorithms and simulation tools to ensure the rationality and optimization of the cutting path and sequence; Finally, according to different workpiece and processing requirements, optimize the cutting parameters, such as cutting speed, feed speed, cutting depth, etc. Through experiments and tests, these parameters are verified and adjusted to achieve the best machining results.

4 Measures to improve the quality of CNC milling

4.1 Standardize CNC milling processing and operation flow

In order to fully improve the processing quality, we must standardize the CNC milling processing and operation process, in this process should try to introduce advanced technology, improve the technical level, optimize the entire operation process, which can be started from the following aspects:

First, carry out training for operators. In the training process, in addition to continuously improving their operation level, it is also necessary to sort out their operation process. If it is found that some operators do not strictly abide by the operation process in the actual production process, they should be dealt with according to the corresponding management system;

Second, the specification of the use of CNC milling machine, especially the processing, operation of these two parts, the specific specification process is made into a document, issued to each department, and then according to the document to develop a site management system, by each department manager or team leader is responsible for supervision;

Third, improve the rationalization of programming procedures. Under normal circumstances, CNC milling process in the machine tool performance, programming and practical applications will have some differences, in order to reduce the negative impact of such differences, manufacturing enterprises should do a good job of resource allocation work to avoid waste of resources. Before this, it is necessary to investigate the existing equipment, including the quantity, purchase years, current performance, whether there is fault or damage, and then rationally arrange the equipment according to the actual processing needs. If some devices are in the scrap stage, handle them in a timely manner to avoid wasting storage space or confusing the enterprise infrastructure.

4.2 Improve the machine tool software and hardware system

In CNC milling machine, the software system and hardware system can not only determine the ability of CNC machining equipment, but also directly reflect the digital management level of machinery manufacturing enterprises, as well as the software application ability, therefore, if the enterprise wants to strengthen the work efficiency, it is necessary to improve the software and hardware system of the machine tool, optimize the programming program, and protect the machine tool efficient and stable operation. Specific can be started from the following aspects:

First, optimize the control system: ensure that the control system of the machine tool has strong functions and stability, can support complex programming and processing operations, update and upgrade the firmware and software of the control system to improve performance, accuracy and stability; Second, strengthen cutting parameter management. Optimize the setting of cutting parameters and tubes

Management, including cutting speed, feed speed, cutting depth, etc., to ensure that the cutting parameters match the material characteristics and workpiece requirements to achieve more efficient and accurate machining;

Third, strengthen simulation and simulation functions. By enhancing the simulation and simulation capabilities of the machine tool software, the machining path can be simulated virtually and any potential conflicts or errors can be checked, which can reduce machine downtime and human error, improve production efficiency and quality;

Fourth, improve the machine tool software user interface, make it easier to operate, it is recommended to use a graphical interface;

It is equipped with high-precision sensors for real-time monitoring of the state of the machine tool, the position of the workpiece and the feedback of the cutting process.

4.3 Application of three-dimensional surface processing technology

Three-dimensional surface processing is a processing process of three-dimensional cutting on a surface, which is used to manufacture parts with complex surface shapes. The process steps are generally:

Design surface models: Use computer aided design software (CAD) to create or import surface models that need to be processed. This can be point cloud data from solid model scans, or it can be created through curve and surface modeling tools.

Second, plan the construction route. Use a computer to assist in the production of software(CAM) Generate the processing path of three-dimensional surface processing. According to the design model, the appropriate tool, process parameters and cutting path are selected.

Three, select the tool. According to the characteristics of the machining path and surface, the suitable tool is selected for milling. Ball head tools, spiral tools or special-shaped tools are usually used to adapt to the shape of the surface.

Four, set cutting parameters. Determine the cutting speed, feed speed, cutting depth and cutting direction and other cutting parameters, the selection of these parameters to consider the hardness of the material, the performance of the tool and the requirements of the workpiece.

Five, surface treatment and inspection. After finishing the three-dimensional surface processing, surface treatment may be required, such as polishing, spraying paint, etc., to achieve the desired surface quality.

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