CNC machining and CNC system

Beijing Fanaco Electromechanical Co., Ltd. (100085) CNC is the basic technology of advanced manufacturing technology. CNC machining has shown great advantages in modern production.

For modern manufacturing, CNC machines are ideal for parts that are complex, precise and small in size. Or ordinary ordinary machine tools simply cannot meet this requirement. Even the profiling machine and the combined machine tool can't solve the contradiction between high precision and small batch. Therefore, CNC machining is very suitable for parts processing technology in the manufacturing industries of aviation, aerospace, electric power, transportation and electronics.

One of the main problems facing parts processing is the contradiction between the precision, diversity and small batch size of the product. This requires flexibility from machine tools to CNC. The CNC system has great flexibility due to software control.

The outstanding advantages of modern CNC machine tools are high-precision machining and diversified machining, which can completely replace other machining methods. Since the CNC machine tool is automatically processed according to a predetermined program, the machining process does not require manual intervention, and the machining accuracy can be corrected and compensated by software, so that the machining accuracy of the parts can be improved and the quality of the product can be stabilized. This is especially true for multi-variety, low-volume parts.

In addition, the use of CNC machine tools can increase productivity, generally can increase production efficiency by 2 to 3 times, for the processing accuracy of some complex parts, the productivity can be increased by 10 times or even higher. Some CNC machine tools have multiple processes and automatic tool changers, so they can be used in one machine, which not only improves production efficiency, but also saves plant area.

The 0 series CNC system is a kind of CNC system with high precision and full function. It has good flexibility and is ideal for machining mechanical parts.

What are the main indicators for measuring the superiority and inferiority of CNC systems? Reliability The most important of these indicators is reliability. The reliability indicators generally use the mean time between failures (MTBF units are hours). Some companies use failure rate (Failurerate unit is time/month). The trouble-free time of CNC machine tools is generally 500h, which requires the trouble-free time of the CNC system to be greater than it. Now the fault-free time of the domestic CNC system can reach 500010000h, even more ambiguous, and abroad is more than 10 000h. The failure rate of FANUC's FS-01 system is 0.008 mechanical workers (time/month. The equivalent of 90-degree fault-free time depends on whether the numerical control system's command value range meets the needs of the machine. These command value ranges include: minimum Input increment, minimum command increment, maximum programming size, maximum fast-moving speed, feed rate range, etc. The resolution of the CNC machine tool and the speed of the fast motion and the range of the machining speed range represent the basic requirements of the machine tool, and also the numerical control system. Basic indicators. These indicators are related to the grade of the CNC system. The resolution indicates the interpolation capability of the system, and when considering the entire command range, it is also related to the indicators of the servo device.

The function is mainly to meet the requirements of the machine tool. The general CNC system has two functions, basic functions and selection functions. The former is a function of the numerical control system, and the latter is a function that is provided when the user selects, and each additional option adds a certain price. Therefore, in order to improve the economics of CNC machine tools, the functions of the CNC system must be carefully selected according to the needs. The function of the CNC system is related to the type of CNC system. For example, the functions of CNC lathes and CNC milling machines are different. Therefore, different system functions should be selected for different types of machine tools. When selecting a function, it must be determined according to the purpose of the CNC machine. The system functions of different grades are also different. One-sidedly thinking that the more functions, the better the idea is wrong. In China's processing workshops, the general use of CNC machine tools is more specialized. Therefore, it is not necessary to select a system with many functions, which will increase the price of the purchase.

What is the basic program of the CNC system? The general CNC system has three basic interpolation functions, namely positioning (G00), linear interpolation (G01), and circular interpolation (G02, G03). These three kinds of imputed programs are called basic programs (see "Functions of CNC System").

The program gives an example description.

10.0; its path is like.

G01 shows that the program is (1 arc axis with rapid movement. This command is generally used for automatic tool change (ATC). Therefore, a need to take A to cancel tool radius compensation and tool length compensation when executing this command.

The return point is that the G29 that is used to make the CNC machine tool and the CNC system is automatically returned from the point. It indicates the process by which the specified axis is positioned to the specified position through the intermediate point. Usually used after G28 or G30 (return to point 2). G29 operates as in (4) and (5); (4) the specified axis, positioned to the intermediate point defined by G28 or G30 (K point to point B); from the intermediate point to the specified point positioning point to C Point); move to the middle, the specified point at a rapid speed.

() The mechanical origin specified by the machine tool builder.

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 a point is called a return point. The process of returning points by manual operation is called "manual return point."

The process of automatically returning to zero according to the specified G code is called "automatic return point".

The quick process of returning points. Set a deceleration encoder near the point of the coordinate axis - the 倌 I I return point is commanded by G28, and in the block of G28, the intermediate point coordinate value of the command axis is stored. The command operation of the G28 block is as follows: 1 Move the axis of the command to the intermediate point (point A to point B). 2 Position from the intermediate point to the point (point B to point i). 3 If it is not the machine lock state, the return light will be on. In the point-to-point slender screw threading tool, the tool is installed in the tailstock sleeve by the taper shank. The guide sleeve 2 is mounted on the clip body 1, and the guide sleeve 3 is fitted with the die 3, and the position of the cap 4 is adjusted according to the length of the medium on the workpiece. When working, do not tighten the tailstock, shake the handwheel to contact with the workpiece, the workpiece rotates slowly, the guide sleeve moves along the open track, and the vehicle is reversed after cutting.