The Background and Significance of NC Machining Technology

1. Background of NC machining technology:

Numerical control technology originated from the needs of aviation industry. In the late 1940s, an American helicopter company proposed this scheme.

The original idea of CNC machine tools, 1952, MIT developed a three-coordinate CNC milling machine. In the mid-1950s, this CNC milling machine has been used to process aircraft parts. In 1960s, numerical control system and programming became more and more mature and perfect. CNC machine tools have been used in various industrial sectors, but the aerospace industry has always been the biggest user of CNC machine tools. Some large aviation factories are equipped with hundreds of CNC machine tools, among which cutting machine tools are the main ones. NC machining parts include the integral wall plate, beam, skin, partition frame, propeller, mold cavity of aero-engine casing, shaft, disk and blade, and special cavity surface of liquid rocket engine combustion chamber, etc. In the early development of CNC machine tools, continuous trajectory control is the main method.

Continuous trajectory control, also known as contour control, requires the tool to move relative to the part according to the specified trajectory. In the future, we will vigorously develop point control CNC machine tools. Point control means that the tool moves from one point to another, as long as it can reach the target accurately in the end, regardless of the moving route.

2. The significance and characteristics of NC machining technology:

From the very beginning, CNC machine tools selected aircraft parts with complex contours as processing objects, which solved the key problems that were difficult to be solved by ordinary processing methods.

The biggest feature of NC machining is to control the machine tool with perforated belt (or magnetic tape) for automatic machining. Because aircraft, rockets and engine parts have different characteristics: aircraft and rockets are zero, the parts are large in size and complex in shape; The engine is zero, the component size is small and the precision is high. Therefore, the CNC machine tools selected by aircraft, rocket manufacturing departments and engine manufacturing departments are different. In aircraft and rocket manufacturing, large CNC milling machines with continuous control are mainly used, while in engine manufacturing, there are both continuous control CNC machine tools and some control CNC machine tools (such as CNC drilling machines, CNC boring machines and machining centers). ) all of them are used.

Process concentration

CNC machine tools are generally equipped with a tool holder and a tool magazine that can automatically change tools. The tool changing process is automatically controlled by the program, so the process is relatively concentrated. Centralized processes bring huge economic benefits;

(1) Reduce the floor space of the machine tool and save the workshop.

⑵ Reducing or not having intermediate links (such as intermediate inspection and temporary handling of semi-finished products) saves time and effort.

automation

When CNC machine tools are processed, there is no need to manually control tools, and the degree of automation is high. The benefits are obvious.

(1) has low requirements for operators:

An ordinary machine tool senior worker can't be trained in a short time, while an unprogrammed CNC lathe worker needs very short training time (for example, a CNC lathe worker needs a week, and a simple machining program can be written). Moreover, the parts processed by CNC workers on CNC machine tools are more accurate and time-saving than those processed by ordinary workers on traditional machine tools. ⑵ Reduce the labor intensity of workers: CNC workers are excluded from the processing process most of the time, which is very labor-saving.

⑶ Stable product quality: The processing automation of CNC machine tools avoids the fatigue, carelessness and human estimation error of workers on ordinary machine tools, and improves the consistency of products.

(4) High machining efficiency: CNC machine tools automatically change tools to make the machining process compact and improve labor productivity.

High flexibility

Traditional universal machine tools are flexible, but inefficient. Although the traditional special plane has high efficiency, it has poor adaptability to parts, high rigidity and poor flexibility, and it is difficult to adapt to frequent product modifications brought about by fierce competition in the market economy. As long as the program is changed, new parts can be processed on CNC machine tools, and the operation can be automated, flexible and efficient, so CNC machine tools can adapt to market competition well.

Strong ability

Machine tools can accurately process all kinds of contours, but some contours cannot be processed on ordinary machine tools. CNC machine tools are especially suitable for the following occasions:

1, parts that are not allowed to be scrapped.

2. New product development.

3. Processing of parts is urgently needed.

Numerical control technology has a far-reaching impact on the realization of automatic control operation.