CNC machine tool machining is the process of using cutting tools to cut certain materials into a desired shape or size. These manufacturing processes often referred to as subtractive processes, remove excess material to convert the workpiece or blank to the correct size and shape specified in the drawing or model.
Part surface quality is an important evaluation factor in machine tool machining quality. Part surface micro-geometry and machine tooling after the surface of the metal material properties of the change is the performance of the surface quality after machine tooling. Machine tool machining of the parts due to various aspects of the impact, can not present a completely smooth surface, there will inevitably be different degrees of cold hardening, cracks, rough corrugations, and other defects.
The parameter setting of the CNC machine tool before work is very important, and the correct development of the control program is one of the main conditions to ensure the quality of precision mechanical parts processing. For the digital program control stage system, the preparation of the control program is carried out by the automatic programming system, and its quality level depends largely on the price of preparing the control program.
The main factors affecting the quality of machine tool processing are as follows.
1. Original error
The original error is compared to a variety of factors affecting the quality of machine tool machining is more common in a kind of impact. The reasons for its appearance are due to uneven distribution of cutting force error, processing errors caused by deformation and thermal deformation caused by processing errors, and so on. The essence of reducing the original error of machine tool processing is to artificially reduce or eliminate new errors. Can be analyzed, statistics and generalization, master the characteristics of the original error and the law, from the fundamental reduction of the original error.
2. Cutting force distribution of uneven error solution
Cutting force is determined by the machine tool and processing parameters, and processing parameters are calculated through advanced CNC programming. After establishing the mathematical model, the problem can be found and processed in time. In addition, excessive amplitude during the machining process of the machine tool can affect the final machining accuracy. By observing the rated parameters of the model, the final adjustment plan can be scientifically derived to control the noise and vibration during machining within an acceptable range, thus affecting the CNC machining process to the maximum extent.
3. Machine operator technical operation errors
As CNC machine tools become more and more complex in function, the level of programming and operation varies greatly. Combining superior human skills with computer information technology allows for maximum utilization of the machine. To do this, machine operators must be familiar with equipment performance. If operators do not know enough about the performance of the equipment, the resulting operational errors lead to conditions such as wear and tear in the quality of the parts machined by the machine. Therefore, training machine operators' skills in machining production need to be strengthened.
4. The characteristics of the workpiece material
In the process of processing plastic materials, the tool will squeeze the metal, resulting in plastic deformation of the metal, the tearing effect of the tool will also increase the surface roughness. During the machining of brittle materials, the chip effect tends to cause surface pitting, making it difficult to ensure surface roughness. In this case, it is necessary to choose the cutting method according to different material characteristics to reduce surface roughness.
5. Dimensional tolerance
Dimensional tolerance is the amount of dimensional variation allowed. It is equal to the larger limit size minus the difference between the smaller limit size, or the difference between the upper deviation and the lower deviation. Precision CNC machine tool accuracy inspection can be divided into geometric accuracy inspection and shape accuracy inspection. Work accuracy refers to the index control machine tool in dynamic conditions when processing the workpiece reflecting the accuracy of the machine tool. And geometric accuracy refers to the index control machine tool in the non-working mutual position accuracy and the main parts of the shape accuracy and position accuracy.
