Before you start programming, you must analyze the design drawings and technical requirements in detail to get the best machining solution.
First, the original data required for the development of CNC machining process lines
1. Parts design drawings, technical materials, and assembly drawings of the products.
Most of the common structures on parts are obtained by forging (or casting) and machining, so they are called process structures. Knowing the common process structure on a part is the basis for learning a part drawing.
For the current economic CNC lathes in China, the ordinary three-phase asynchronous motor is generally used to realize stepless speed change through the frequency converter. If there is...
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Numerical control (English name: Numerical Control abbreviation: NC) technology refers to the use of digital instructions composed of numbers, characters and symbols to realize the motion control of one or more mechanical devices. CNC is generally controlled by a general-purpose or special-purpose computer for digital program control. Therefore, CNC is also called Computer Numerical Control (CNC), which is called CNC in foreign countries. The concept of NC is rarely used.
It controls the mechanical quantities such as position, angle, speed, etc. and the amount of switching related to the flow of mechanical energy. The generation of numerical control relies on the emergence of data carriers and binary form data operations. In 1908, a perforated sheet metal interchangeable data carrier was introduced; at the end of the 19th century, a control system with paper as a data carrier and an auxiliary function was invented; in 1938, Shannon conducted rapid data calculation and transmission at the Massachusetts Institute of Technology. It laid the foundation for modern computers, including computer numerical control systems. CNC technology is developed in close cooperation with machine tool control. In 1952, the first CNC machine tool came out, becoming an epoch-making event in the history of the world machinery industry, promoting the development of automation.
Nowadays, CNC technology is also called CNC Numerical Control Technology (CNC), and it is currently a computer-based digital program control technology. This technique uses a computer to execute a sequential logic control function for the motion track of the device and the peripherals in accordance with a previously stored control program. Since the computer is used to replace the numerical control device which is originally composed of hardware logic circuit, the realization of various control functions such as storage, processing, calculation, logic judgment of the input operation instruction can be completed by computer software, and the generated micro-instruction transmission is processed. Drive the motor or hydraulic actuator to drive the device.
CNC technology is a technology that uses digital information to control mechanical motion and work processes. CNC equipment is a mechatronic product formed by the penetration of new technologies represented by numerical control technology into traditional manufacturing industries and emerging manufacturing industries, so-called digital equipment. Such as CNC machine tools. Its technology involves many fields: (1) mechanical manufacturing technology; (2) information processing, processing, transmission technology; (3) automatic control technology; (4) servo drive technology; (5) sensor technology; (6) software technology Wait.
CNC technology and equipment are the enabling technologies and the most basic equipment for the development of emerging high-tech industries and cutting-edge industries. National defense industries such as information industry, bio-industry, aviation, and aerospace have widely adopted numerical control technology to improve manufacturing capacity and level, and to improve their adaptability and competitiveness to the market. Industrial developed countries also listed numerical control technology and numerical control equipment as the national strategic materials, not only vigorously developing their own numerical control technology and its industry, but also implementing a blockade and restriction policy on China in terms of "high-precision" numerical control key technologies and equipment. Therefore, vigorously developing advanced manufacturing technology with CNC technology as the core has become an important way for the developed countries in the world to accelerate economic development and improve their overall national strength and national status.
Under the condition of stiffness, the roughing process takes a larger cutting depth to reduce the number of passes and increase the productivity of the workpiece; the finishing generally takes a smaller depth of cut to obtain a higher surface quality. Influencing the final machining accuracy and machining efficiency of the workpiece, in addition to the reasons of the CNC machine itself, it should also be based on reasonable machining route setting, tool selection and correct installation, reasonable selection of cutting amount, programming skills and rapid control of dimensional accuracy. Aspects are considered comprehensively.
First, programming skills
CNC programming is the most basic work of CNC machining. The pros and cons of workpiece machining program directly affect the final machining accuracy and machining efficiency of the machine tool. It can be started from clever use of intrinsic programs, reduction of cumulative errors in CNC systems, and flexible use of main programs and subroutines.
1, flexible use of the main program and subroutines
In the process of complex mold processing, it is generally processed in the form of multiple molds. If there are several identical shapes on the mold, the relationship between the main program and the subprogram should be used flexibly, and the subroutine should be called repeatedly in the main program until the machining is completed. Not only can the consistency of the processing dimensions be ensured, but also the processing efficiency can be improved.
2. Reduce the cumulative error of the CNC system
In general, the incremental programming is used to program the workpiece. It is the previous one to process the reference. In this way, continuous execution of multi-segment programs will inevitably produce a certain cumulative error. Therefore, in the programming, try to use absolute mode to program, so that each block is a workpiece. The origin is the reference, which can reduce the cumulative error of the CNC system and ensure the machining accuracy.
Machining accuracy is mainly used to produce product grades. Machining accuracy and machining tolerance are terms used to evaluate the geometric parameters of the machined surface. However, the actual parameters obtained by any processing method are not absolutely accurate. From the function of the parts, as long as the machining error is within the tolerance range required by the part drawing, it is considered that the machining accuracy is guaranteed.
Machining accuracy refers to the actual geometric parameters (size, shape and position) after machining the part. You want to learn UG programming to receive learning materials. The group 496610960 can help you to match the ideal geometric parameters. The difference between them is called the machining error. The size of the machining error reflects the level of machining accuracy. The larger the error, the lower the machining accuracy, and the smaller the error, the higher the machining accuracy. Here is a brief introduction to the methods to improve the machining accuracy of the workpiece:
First, adjust the process system
(1) Trial cutting adjustment by trial cutting - measuring size - adjusting the tool's cutting amount - cutting cutting - retrying, and so on until the desired size is reached. This method has low production efficiency and is mainly used for single-piece small batch production.
(2) The adjustment method obtains the required size by adjusting the relative positions of the machine tool, the jig, the workpiece and the tool in advance. This method has high productivity and is mainly used for mass production.
Second, reduce machine tool error
(1) The rotation accuracy of the bearing should be improved:
1 use high precision rolling bearings;
2 using high-precision multi-oil dynamic pressure bearing;
3 using high precision hydrostatic bearings
(2) Improve the accuracy of the accessories with the bearing:
1 Improve the processing precision of the box support hole and the spindle journal;
2 Improve the machining accuracy of the surface matched with the bearing;
3 Measure and adjust the radial runout range of the corresponding parts to compensate or cancel the error.
(3) Appropriate preloading of rolling bearings:
1 can eliminate the gap;
2 increase the bearing stiffness;
3 Homogenize rolling element error.
(4) Make the spindle rotation accuracy not reflected on the workpiece
Third, reduce the transmission chain transmission error
(1) The number of transmission parts is small, the transmission chain is short, and the transmission precision is high;
(2) Adopting the speed reduction transmission is an important principle to ensure the transmission accuracy, and the closer to the end of the transmission pair, the smaller the transmission ratio should be;
(3) The accuracy of the end piece should be higher than other transmission parts.
Fourth, reduce tool wear
(1) Re-grinding must be performed before the tool size wear reaches th