In the process of turning shaft workpiece, the precision and surface roughness can not meet the requirements. According to the specific process of turning, the analysis is carried out.
I. Reasons why the dimensional accuracy fails to meet the requirements and solutions
1. Due to rough (careless) operator, the measurement errors, or dial the wrong and improper use, therefore, when measuring, be careful, it is very important to the proper use of dial, on the dragging plate handle dial, various types of lathe dial is not the same, each a small lattice dial can use the following formula: scale turn one tool moving distance = dragging plate screw distance/dial a total number scribed line (mm) know each scale value later, when use notice because there are clearance between screw and nut, although sometimes dial rotation, but turning tool may not move, such as gap to after turning tool didn't move. Therefore, in use, if the scale has been turned too far, it is never allowed to reverse only a few squares, but to reverse a turn, and then re-align the scale.
2. There are errors in the measuring tool itself or the measuring tool is not put right in use. Before using the measuring tool, it should be carefully checked and adjusted and put right in use.
3. Due to the change of temperature, the workpiece size changes in the cutting process, the chip deformation, chip molecules move among each other, and they move friction and generate a lot of heat. In addition, due to the chip and the front of the lathe tool friction, friction behind the lathe tool and the workpiece surface also produce heat, the heat will directly affect the tool and the workpiece up. Of course, the highest amount of heat is chip (about 75%), followed by turning tool (about 20%) and workpiece (about 4%, and 1% in the air). When the workpiece is heated, the diameter increases (about 0.01 ~ 0.05 mm, the change of cast iron is greater than that of steel), and the diameter shrinks after cooling, resulting in waste products. Therefore, it cannot be measured when the workpiece temperature is very high. If the side must be measured, enough cutting fluid is poured during the turning so that the workpiece temperature does not rise; Next, use the method that the coarse fine car separates.
4. The blank residual is not enough, which is caused by the bending of the blank itself and the deviation of the center hole.