Regarding the use of CNC cutting machines, for most users, once they feel a fault, the most intuitive performance is that the cut parts have dimensional deviations. Of course, the size deviation is only the result of the failure of the CNC cutting machine. The real cause may have many aspects, such as mechanical failure, software failure, operating error, environmental factors, etc. This article analyzes the size deviation of the CNC cutting machine to make it faster, Find out the cause of the failure more accurately and deal with it.
The so-called numerical control cutting refers to the workpiece instruction (or program) used to control the machine tool or equipment, which is a new control method given in the digital form. When this instruction is provided to the control device of the CNC automatic cutting machine, the cutting machine can automatically cut according to the given program. Numerical control cutting is composed of two parts: the numerical control system and mechanical structure. Compared with traditional manual and semi-automatic cutting, CNC cutting can effectively control and improve cutting quality and cutting efficiency through the cutting technology, cutting process, and automatic control technology provided by the CNC system that is the controller.
Advantages of CNC cutting: CNC cutting has higher cutting efficiency and more complex nesting programming. If the optimized nesting programming software is not used or is not used well, the steel waste will be more serious, resulting in faster cutting and more cutting. The more waste. The numerical control system is the controller, which is the heart of the numerical control cutting machine. If the numerical control system is not used well, or the numerical control system does not have the necessary cutting technology and cutting experience, it will lead to cutting quality problems, thereby reducing cutting efficiency and causing waste of steel. It also lost the advanced nature of CNC cutting automation, high efficiency, high quality, and high utilization rate.
In the process of using the CNC cutting machine, the size of the cut workpiece often appears to be inaccurate. There are many reasons for this, and the main reasons are summarized as follows:
1. Graphics size error
In the process of drawing or nesting, there may be negligence caused by the error of the graphic size. At this time, the cause can be found by checking the size.
2. Programming software error
If the programming software has defects or has no cumulative error correction function, it will cause errors in the generated CNC code. For example, the generated code size data is wrong or the compensation direction is wrong; or the code has accumulated errors, which causes no problems with small-scale sizes. When there are many line segments, there are large errors, resulting in a misalignment of the entry and exit points, which will also cause the entire board to cover the Deviation of workpiece spacing during material loading. It is easy to check program problems. As long as the NC code is converted to CAD graphics for measurement, the compensation direction can be seen through simulation.
3. The accuracy of the cutting machine
The precision of the cutting machine includes mechanical precision and electronic precision. The mechanical accuracy is mainly affected by the straightness, parallelism, levelness of the guide rail, and the transmission accuracy of gears or steel belts. The levelness of the cutting platform also affects the accuracy of the workpiece. The electronic accuracy is affected by the numerical control system software and motion control card, pulse equivalent, servo and servo drive, etc. In particular, if the pulse equivalent is not adjusted accurately, it will cause problems such as out-of-round cutting and uneven size of large parts. It is also very simple to check the accuracy of the cutting machine, as long as the cutting needle is installed on the cutting gun, and the program of the cutting machine to correct the error is run to check the marking.
4. Cutting nozzle quality and cutting compensation amount
The quality of the cutting nozzle will affect the surface quality of the workpiece and the flatness of the cutting side. The slit compensation must be consistent with the actual cutting slit width. The way to reduce this kind of error is to choose a cutting nozzle with qualified quality. The cutting nozzle specifications should also be suitable for the thickness and material of the plate to be cut. You can first try cutting and adjusting the scrap until the width of the slit is uniform and the section is flat without slag. Cut a rectangle to a fixed length without compensation, and finally measure it, and makeup as much as the slit width is smaller.
5. Deformation during cutting
Deformation mainly includes thermal deformation and deformation caused by gravity. Using a reasonable lead position and cutting direction during programming can reduce deformation. Some cooling devices can be added as needed, and a reasonable structure cutting platform can be used.
6. Errors caused by edge
If co-edge is used, the compensation amount, the actual slit width, and the spacing of the workpiece co-edge must be consistent. If they are inconsistent, the size of the workpiece will be larger and smaller.
7. The cutting machine runs randomly
Voltage fluctuations, loose data lines, poor contact between the system and servo control lines, loss of servo feedback signals, and unstable servo drive circuits may cause the cutting machine to run randomly.
The principle of judging the phenomenon of the random running of the cutting machine: one is that irregular running can eliminate the problem of the CNC program; the other is to check whether there is a problem with the program through simulation. If the program is okay, check the system software (including axis The built-in software of the card).
To sum up, the error can be divided into the error before cutting and the error after cutting. For a certain program, the error before cutting can be checked by scribing, and the error after cutting needs to be optimized by a reasonable cutting process to reduce the error.