CNC computer engraving and CNC milling and machining center comparison - Database & Sql Blog Articles

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1. Mechanical part The machine tool consists of two parts: the work table, the main shaft slide, etc. are moving parts; the bed, the base, the column, etc. are non-moving parts.
(1) CNC milling and CNC machining centers have high requirements on the non-moving parts and moving parts of CNC milling and CNC machining centers, so heavy cutting can be performed. However, because the moving parts are also huge, the machine flexibility is sacrificed, and it is not enough for small cutting and rapid feeding.
(2) The rigidity requirements of the non-moving part of the CNC engraving and milling machine must be as good as possible, and the rigidity of the moving part should be flexible, and should be designed to be as light as possible while maintaining a certain rigidity. . The CNC engraving machine thus designed can perform relatively fine finishing, and has high machining precision. For soft metal, high-speed machining can be performed, but heavy cutting is impossible due to poor rigidity of the moving portion. How to solve the contradiction between light weight and rigidity of the moving part from the mechanical structure, the key lies in the mechanical structure design, the following technical measures can be adopted:
1) With extra-wide columns and beams, the gantry structure is the preferred structure for high-speed cutting equipment because of its excellent symmetry and excellent rigidity. Compared with the traditional C-type bed structure, the gantry form has a higher rigidity and average force. The workpiece moves only in one axial direction, and each movement axis and relative inertia are low. The design is compact and precise, ensuring high rigidity. High precision and high dynamics. The beam of the machine tool can be tilted by 30 degrees, so that the center of gravity of the spindle saddle moves backwards, and the spacing of the rails of the beam is increased as much as possible, so that the stability and rigidity of the spindle can be greatly improved. Since the quality of the column is much larger than the quality of the moving parts such as the spindle, it provides a solid guarantee for the high-speed movement of the machine and the high-speed operation and load cutting of the spindle.
2) The base is cast in one piece of cast iron, using a mesh box structure with high and low ribs, or a hexagonal mesh structure directly connected to the honeycomb to ensure sufficient weight of the base to increase the stability of the machine. Such a high rigidity base The design ensures the rigid support of the fixed table and column and the moving parts such as the saddle and the spindle, which makes the dynamic machining of the machine have the best stability. The column is fully supported in the full stroke range, so that the deformation caused by the machining is minimized.
3) The difference between the moving part and the CNC milling is that the distance between the guide rail and the guide rail is widened to overcome the influence of bad torque.
4) Since the rigidity of the machine tool is mainly used to overcome the strong impact of the moving part on the non-moving part when moving at a high speed, the guide rail and the screw are required to be thicker, and the rigidity of the connecting portion is strengthened. Finally, in order to meet the dual requirements of high speed and load cutting, X/Y/Z three-axis adopts servo motor and high-precision elastic coupling to connect high-precision ball screw pair. All guide rails and lead screws adopt high-grade low friction coefficient. High-hardened and high-hardened products, which not only ensure the rigidity of the machine under heavy load, but also ensure the high-speed movement accuracy, ensuring low wear and precision retention of the machine tool in long-term continuous high-speed machining, saving users' maintenance. Maintenance costs.
5) For CNC milling and CNC machining centers, because the output of low speed and high torque is required, the reduction ratio of the main shaft gearbox is needed to increase the torque. Therefore, the low speed is unavoidable. The maximum speed of CNC milling and CNC machining centers is 6000r/ Min, it is unlikely that a tool with a small radius will be used. However, for the CNC engraving machine, the spindle usually works at 20,000 to 30000r/min, and the rotation accuracy is generally about 2μ. Otherwise, the broken knife phenomenon will be very serious, so it is necessary to use an electric spindle or a pneumatic spindle, that is, the motor and the spindle are integrated. The fixing plates of the main shaft are generally made of lightweight materials such as alloy aluminum. For high-speed cutting equipment, the built-in electric spindle is required, and a certain torque is required at low speed. There must be a water-cooling machine to keep the spindle working temperature constant. The spindle power should be above 7.5~8kW, and the speed should exceed 25000r/min.

2. CNC system CNC milling and CNC machining center require high speed for CNC system, spindle speed is about 0~6000r/min. The engraving and milling machine requires high-speed CNC system and excellent servo motor characteristics, and the spindle speed is about 3000~40000r/min. Directly supports G code generated by various CAD/CAM software such as MasterCAM. The CNC system has the following functions:
(1) Automatic tool setting function: automatic center finding, corner, depth, high precision, solve the problem of mold alignment;
(2) Automatic/manual machining: G commands that support the ISO standard;
(3) Incremental feed and feedrate override online adjustment function: This operation can accurately set the feed rate;
(4) User data input (MDI) function: The user can input the AG command online and execute it immediately;
(5) Single step mode: the user can set the machining task to be executed to the single step mode;
(6) High-speed smooth speed connection feature: adaptively determines the speed of the connection between the current command and the next instruction. It not only greatly improves the processing efficiency, but also improves the processing performance, and can eliminate the speed of the tooling marks left on the machined surface;
(7) 3D simulation display function: 3D machining results can be observed from various angles by simple operation;
(8) Simulation function: It can perform rapid simulation processing on the machining program, and it can be completed in a very short time. At the same time, it checks whether the machining program is wrong, whether the machining result is satisfactory, and can accurately calculate the time required for actual machining.

3. Programming software
(1) Diverse 2D design At present, many engraving softwares provide powerful graphic creation, editing, and typographic functions, precise drawing and art drawing functions, and powerful word processing functions. The artistic text arrangement effect with a variety of arbitrary curves, the font and size can be adjusted and edited arbitrarily; the powerful node editing function can quickly and randomly trim the local shape of the contour.
(2) Flexible 3D design The embossing engraving software provides a powerful and convenient way to generate 3D models from 2D graphics. The 2D curves are used to construct artistic reliefs and complex surfaces with strong artistic effects, and perfect for artistic relief and surface modeling. Combine to produce engraving products with complex shapes. It can also directly output 2D and 3D tool paths. The tool path provides functions such as roughing, semi-finishing, finishing and tool path simulation.
(3) Powerful CAD design
CAD/CAM mold design and manufacturing software is widely used and highly successful in the machining industry. It not only has the ability to accurately draw 2D and 3D graphics, but also produces powerful functions such as curved surfaces and solid models. The surface, solid model directly compiles the tool path, verifies the NC program by simulating the tool path, and inputs the powerful functions of the workpiece machining by the CNC input CNC engraving machine and CNC machine tool.
(4) Convenient data exchange function software can directly convert two or three-dimensional data. CNC engraving machine is the same as CNC machining center and CNC milling. Its machining basis is computer-aided design data, which is the key to engraving CAD function. At present, the advanced computer engraving software at home and abroad has different functions. From the software point of view, CNC milling, CNC machining center and CNC engraving machine can use standard CAD/CAM software, CAD/CAM software to carry out products first. The 3D graphic design, then design the CNC machining process according to the characteristics of the product, input the machining parameters, generate the tool path, and then generate the machining program and send it to the control system of the CNC machine for automatic machining. The CNC four-axis computer engraving machine is shown in Figure 1.


Figure 2 Machining Center