The characteristics of CNC machine tools in processing
1. High precision
(1) The machine tool structure of CNC machine tools has high rigidity and thermal stability, and measures to reduce errors have been taken. With the error, it can also be compensated by the numerical control device, so the numerical control machine tool has higher machining accuracy.
(2) The transmission system of the CNC machine tool adopts a ball screw without clearance, a rolling guide rail, a gear mechanism with zero clearance, etc., which greatly improves the transmission rigidity, transmission accuracy and repeatability of the machine tool. The advanced CNC machine tool adopts linear motor technology, so that the mechanical transmission error of the machine tool is zero.
(3) The error compensation function of the numerical control system eliminates the system error.
(4) The CNC machine tool is automatic processing, eliminating human error, improving the consistency of the processing size of the same batch of parts, and the processing quality is stable. One installation can carry out continuous processing of multiple processes, reducing installation errors.
2. Can process parts with complex shapes
Using the CNC machine tool with more than two axes linked together, it can process the rotating body, cam, and various complex space curved surfaces whose busbar is a curve, and can complete the processing that is difficult for ordinary machine tools. For example, the marine propeller is a complex part with a space curved body, which can only be processed by an end milling cutter and a five-axis linkage horizontal CNC machine tool.
3. High productivity
(1) Save auxiliary time
CNC machine tools are equipped with automatic tool changing mechanisms such as index tool rests and tool magazines. The manipulator can automatically load and unload tools and workpieces, which greatly saves auxiliary time. No inspection is required in the production process, saving inspection time. When the machining part is changed, in addition to re-clamping the workpiece and changing the tool, only the program needs to be changed, which saves the preparation and adjustment time. Compared with ordinary machine tools, the productivity of CNC machine tools can be increased by 2 to 3 times, and the productivity of machining centers can be increased by ten to dozens of times.
(2) Increase the feed rate
CNC machine tools can effectively save manoeuvring time, fast movement shortens the time of idle travel, and the range of feed is large. Can effectively select a reasonable amount of cutting.
(3) High-speed cutting
During CNC machining, small-diameter tools, small depth of cut, small width of cut, and rapid multiple passes are used to improve cutting efficiency.
The cutting force of high-speed machining is greatly reduced, and the required spindle torque is correspondingly reduced.
The deformation of the workpiece is also small. High-speed cutting not only improves productivity, but also helps to improve machining accuracy and reduce surface roughness.
The adaptability and economic characteristics of CNC machine tools
1. Strong adaptability
CNC machine tools can adapt to the processing of workpieces of different varieties, specifications and sizes. When changing parts to be machined, it is only necessary to clamp the workpiece with a universal fixture, change the tool, and change the machining program, and the machining can be performed immediately. The computer numerical control system can use the system control software to flexibly increase or change the functions of the numerical control system, and can meet the needs of production development.
2. Facilitates the development of more advanced manufacturing systems
CNC machine tools are the basic equipment for machining automation. Flexible machining cells (FMC), flexible manufacturing systems (FMS) and computer integrated manufacturing systems (CIMS) are all based on CNC machine tools. One or more CNC machine tools, together with other auxiliary equipment (such as transport trolleys, robots, changeable workbenches, three-dimensional warehouses, etc.) constitute an automated production system. The numerical control system has a communication interface, which is easy to communicate between computers and realize computer management and control of the production process.
3. The economy of CNC machine tools
The cost of CNC machine tools is higher than that of ordinary machine tools, and the processing cost is relatively high. Therefore, not all parts are suitable for processing on CNC machine tools, and it has a certain range of processing applications. Whether it is suitable for CNC machine tool processing should be determined according to the production type, structure size and complexity of the product.
The general-purpose machine tool is suitable for single-piece and small-batch production, and the processing structure is not too complicated.
Special machine tools are suitable for the processing of large quantities of workpieces.
CNC machine tools are suitable for batch processing of complex workpieces.
Characteristics of CNC machine tools in management and use
CNC machine tools are expensive to manufacture, and are key equipment for key products and key processes in an enterprise. Once the machine fails, the impact and loss will be great. As a mechatronics equipment, CNC machine tools have their own characteristics.
The technical level of management, operation, maintenance and programming personnel is relatively high. The use effect of CNC machine tools depends to a large extent on the user’s technical level, the formulation of CNC machining technology and the correctness of CNC programming. Therefore, the use technology of CNC machine tools is not a problem of general equipment use, but a technical application project of talents, management, and equipment systems. The users of CNC machine tools must have rich process knowledge, and at the same time have strong operational capabilities in the application of CNC technology, so as to ensure that the CNC machine tools have a high integrity rate and operating rate.
The types of CNC programming
NC programming is divided into two categories: manual programming and automatic programming.
1. Manual programming
(1) Determining the technological process According to the part drawing, the process analysis is carried out, and the technological parameters such as the technological route, working step sequence, cutting amount and so on of the part processing are determined. Determine the tools and the number of tools to use.
( 2 ) Calculate the machining track and size
(3) Write a program list and verify it
(4) Input the content of the program list The content of the numerical control program list is input into the numerical control device through the input device.
(5) Verification and trial cutting of the NC program Start the NC device, make the NC machine tool run dry, and check the correctness of the program trajectory. Use wood or plastic products instead of the workpiece for trial cutting to check the correctness of the cutting amount.
(6) Trial cutting of the first piece
2. Automatic programming
The process of compiling CNC machining programs with the help of a computer is called automatic programming.
For parts with complex geometries, manual programming is labor-intensive and error-prone.
Programming and calculation of space surface parts is very cumbersome, and manual work is not competent. In automatic programming, the data calculation of node coordinates, the generation of tool paths, the programming and output of programs are all done automatically by the computer.
Post time: May-23-2022