CNC machining and CNC system
Cnc Machining shows great advantages in modern production.
For modern manufacturing, Cnc Machine tools are very suitable for parts with complex shapes, precision and small batches. However, ordinary ordinary machine tools cannot meet this requirement at all. Even profiling machine tools and modular machine tools cannot solve the contradiction between high precision and small batches. Therefore, CNC machining is very suitable for parts processing technology in aviation, aerospace, electric power, transportation and electronics industries.
One of the main problems facing parts processing is the contradiction between product precision, variety and small batch size. This requires flexibility from machine tools to CNC. The CNC numerical control system has great flexibility due to its software control.
The outstanding advantage of modern CNC machine tools is that they can carry out high-precision processing and diversified processing, which can completely replace other processing methods. Because the CNC machine tool is automatically processed according to a predetermined program, the processing process does not require manual intervention, and the processing accuracy can also be corrected and compensated by software, so the processing accuracy of the parts can be improved and the quality of the product can be stabilized. This is especially true for parts with many varieties and small batches.
In addition, the use of CNC machine tools can increase productivity. Generally, it can increase production efficiency by 2 to 3 times. For the processing accuracy of some complex parts, productivity can be increased by several times or even higher. Some CNC machine tools have multiple processes and automatic tool changers, so they can achieve multiple functions in one machine, which not only improves production efficiency, but also saves plant area.
0 series numerical control system is a kind of precision, full-function numerical control system. It has good flexibility and is very suitable for the processing of mechanical parts.
What are the main indicators to measure the quality of the CNC system? The most important of these indicators of reliability is reliability. The indicator of reliability generally adopts the mean time between failures (MTBF unit is hour). Some companies use failure rate (Failurerate unit is times/platform). The failure-free time of CNC machine tools is generally 500h, which requires the failure-free time of the CNC system to be longer than it. At present, the failure-free time of the domestic CNC system can reach 500010000h, or even more, and it is more than 10 000h in foreign countries. FANUC’s FS-0 system has a failure rate of 0.008 mechanical workers (times/platform. The equivalent of a non-failure time of 90. The function first depends on whether the command value range of the CNC system meets the needs of the machine tool. These command value ranges include: * Small input increment, minimum instruction increment, maximum programming size, maximum rapid traverse speed, feed rate range, etc. The resolution and rapid motion speed of CNC machine tools and the index of processing speed range represent the basic requirements of the machine tool. It is also the basic index of the numerical control system. These indexes are related to the grade of the numerical control system. The resolution indicates the interpolation capability of the system, and when considering the entire instruction range, it is also related to the index of the servo device.
The function is mainly to meet the requirements of machine tools. The general numerical control system has two functions, basic function and selection function. The former is a function of the CNC system, and the latter is a function provided when the user chooses. Each additional option will increase a certain price. Therefore, in order to improve the economy of CNC machine tools, the functions of the CNC system must be carefully selected according to needs. The function of the CNC system is related to the category of the CNC system. For example, the functions of a CNC lathe and a CNC milling machine are different. Therefore, different system functions should be selected for different types of machine tools. When selecting the function, it must be determined according to the purpose of the CNC machine tool, and the system functions of different grades are also different. It is wrong to think one-sidedly that the more functions the better. In my country’s processing workshops, general CNC machine tools are more specialized. Therefore, it is not necessary to choose a system with many functions, which will increase the purchase price.
What is the basic program of a numerical control system? General numerical control systems have three basic interpolation functions, namely positioning (G00), linear interpolation (G01), and circular interpolation (G02, G03). These three interpolation programs are called basic programs (please refer to “Functions of CNC System”).
‘S procedures give examples to illustrate.
10.0; its path is like.
The program of G01 example is (circle of ①<diameter like.
The axis moves at rapid speed. This command is generally used for automatic tool change (ATC). Therefore, when a executes this command, it is necessary to cancel A to cancel the tool radius compensation and tool length compensation.
Return point is to make the connection between CNC machine tool and CNC system. G29 is the command to automatically return from the point. It shows the process of positioning the specified axis to the specified position through the intermediate point. Usually used after G28 or G30 (return to point 2). G29 operations are as in (4) and (5); (4) the designated axis is positioned to the intermediate point defined by G28 or G30 (point K to point B); from the intermediate point to the designated point, the positioning point is towards C Point); move to the middle, designated point at a fast speed.
(:20010827) The mechanical origin specified by the machine tool manufacturer.
Deceleration switch manual return point The so-called “point” is a fixed point along the coordinate axis, which can be based on the machine coordinate origin.
The process of locating to a point is called returning to the point. The process of returning to the point by manual operation is called “manual returning to the point”.
The process of automatically returning to the zero point according to the specified G code is called “automatic return point”.
The fast process of returning to the point. Set a deceleration encoder near the point of the coordinate axis-the turning point I return point is commanded by G28. In the block of G28, the coordinate value of the intermediate point of the command axis is stored. The command operation of the G28 block is as follows: ① Move the commanded axis to the intermediate point for positioning (point A to point B). ②Locate from the intermediate point to the point (point B to point i). ③If the machine is not locked, the return light is on. At the point of the slender screw thread tool, Jiangsu Rugao Mining Machinery Factory, this tool is installed into the tailstock sleeve by the taper handle, as shown in the figure. A guide sleeve 2 is installed on the clamping body 1, and a die 3 is installed in the guide sleeve, and the position of the splice cap 4 is adjusted according to the length of the medium pattern on the workpiece. Do not tighten the tailstock when working, shake the handwheel to contact the workpiece, the workpiece rotates slowly, the guide sleeve moves along the open track, and the car is reversed after cutting.