Monthly Archive December 3, 2020

Key points of improving CNC machining quality

  1. Reasonable machining tool with CNC

The smooth knife for processing steel and copper should be used strictly, and the allowance of the smooth knife should be reasonable, so that the smoothness of the workpiece and the service life of the tool will be better.

  1. Before CNC machining, use the calibration table to check whether the tool swing is within the allowable tolerance range. Before machining, the tool head and lock nozzle should be blown clean with air gun or cleaned with cloth before installing the tool. Too dirty will have a certain impact on the accuracy and quality of the workpiece.
  2. When clamping, pay attention to see whether the name and model of CNC machining workpiece and program list are the same, whether the material size is matched, whether the clamping height is high enough, and use caliper to check.
  3. The CNC machining program sheet should be consistent with the reference angle direction marked on the mold, and then check whether it is aligned with the upper 3D drawing, especially for the workpiece with water transportation, it is necessary to see whether the 3D drawing is consistent with the water transportation of the workpiece. If there is any ambiguity, it is necessary to timely feed back to the programmer or find the fitter to check the 2D drawing to see whether the 2D and 3D datum angles are consistent.
  4. The program list of CNC machining documents should be normalized, including die number, name, program name, processing content, tool size, feed amount, especially the safe length of tool clamping, the reserved allowance of each program, and the smooth knife. The place where the R-plane should be connected with the plane should be indicated on the program sheet. The operator should increase 0.02-0.05mm during machining, and the Gong should be cut several times When you stop to see if it is connected smoothly, touch it with your hand to see if it rises, and if it doesn’t, lower the Gong again.
  5. Before processing, it is necessary to understand the contents of the CNC processing program sheet. There must be 2D or 3D drawings on the program list, and the hexagonal data of “x length, y width, Z height” should be marked,

If there is a plane, it should be marked with “Z” value. The operator can easily check whether the data is correct after processing. If there is tolerance, the tolerance data should be indicated.

  1. The processing speed of machine tool should be strictly controlled by the operator. The rotation speed of F-speed and s-spindle should be adjusted reasonably. When F-speed is fast, it should be accelerated relative to s-spindle, and the feed speed should be adjusted in different areas. After processing, check the quality of the machine before it can be off the machine, to achieve a perfect processing.

Speed control of CNC machining

CNC machining is developing towards high speed and high efficiency. This includes the speed control of CNC machining. If we want to make full use of the effective working stroke, we must make the moving parts accelerate to the high speed stroke in a very short time, and stop in the high speed stroke instantaneously. This is why CNC machining speed control.

According to the open control idea, we put forward a method of automatic acceleration and deceleration control for the motion of CNC machine tool according to any curve. This method pushes the automatic acceleration and deceleration control from the traditional fixed mode to the new flexible mode, and explores a new way to effectively improve the dynamic performance of CNC machine tools.

  1. Flexible acceleration and deceleration control

In CNC machining, the specific automatic speed control function is usually realized by the system program directly. In this way, it is necessary to change the acceleration and deceleration characteristics of the system or to control the addition and subtraction to modify the NC program, so ordinary users can not make the CNC machine tool have the best acceleration and deceleration performance according to their own will. Therefore, the flexible acceleration and deceleration control method is based on the principle of database. The acceleration and deceleration control is divided into acceleration and deceleration description and implementation, and the acceleration and deceleration description is separated from the system program. In the software of numerical control system, a general control channel is designed which has nothing to do with the contents of acceleration and deceleration database, which can complete acceleration and deceleration calculation and trajectory control independently.

  1. Flexible automatic acceleration control

The acceleration curve, analytic curve and non analytical curve are set and stored in the acceleration and deceleration curve library as templates in the form of data table.

  1. Flexible automatic deceleration control

As for acceleration control, it is stored in the acceleration and deceleration curve Library in the form of data table. Reasonable automatic acceleration and deceleration control is an important link to ensure the dynamic performance of CNC machine tools. Due to the lack of flexibility, the traditional automatic acceleration and deceleration control based on fixed curve is not easy to ensure that the acceleration and deceleration process is compatible with the performance of the machine tool, so it is difficult to achieve the best dynamic characteristics of the machine tool