Analysis of turning shaft workpiece

In the process of turning axis workpieces in numerical control machining, there will be problems such as the accuracy and surface roughness can not meet the requirements. Analyze according to the specific process of turning.

1、 The reason and solution of dimension precision not meeting the requirement
1. Due to the operator's carelessness in NC machining, errors occur when measuring children, or the dial is wrong and used improperly
Therefore, it is very important to be careful and use the dial correctly when measuring. As far as the middle carriage handle dial is concerned, the dials of various types of lathes are different. Each small scale can be calculated by the following formula:
Turning tool movement interval=carriage lead screw interval/total number of scale divisions (mm)
If you know the scale value of each grid in the future, you should pay attention to the gap between the lead screw and the nut when using. Sometimes the turning tool will move even though the dial is rolling. The turning tool will not move until the gap is turned. Therefore, when using, if the scale is turned too many times, it is not allowed to turn it back only a few times, but to turn it back and then align the scale from the beginning.

2. The measuring tool itself has errors or is not placed correctly during operation
Before using the measuring tools, they must be carefully checked and adjusted, and they must be placed correctly.
3. Because of the change of temperature, the workpiece size changes
During cutting, the chip deforms, and each molecule of the chip moves with each other, while they collide and generate a lot of heat when moving. In addition, because of the conflict between the chip and the front of the turning tool, the conflict between the rear of the turning tool and the surface of the workpiece also generates heat, which directly affects the tool and the workpiece. Of course, high heat Z is chip (about 75%), followed by turning tool (about 20%) and workpiece (about 4%, and 1% in air). When the workpiece is heated, its diameter increases (about 0.01~0.05 mm, and the change of cast iron is larger than that of steel), and after cooling, its diameter shortens, forming waste products. Therefore, it cannot be measured when the workpiece temperature is very high. If the side measurement is necessary, pour enough cutting fluid during turning to prevent the workpiece temperature from increasing; Secondly, use the method of separating rough and fine turning.

4. Blank surplus is not enough
The bending of the blank itself has not been straightened, and the deviation of the base hole is formed.