In generally, the ordinary lathe workpiece are composed by the inner hole, cylindrical and plane.During the turning process, in order to ensure that the workpiece shape and position accuracy and surface roughness requirements, we should choose a reasonable way to clamp and turn right. When turning the thin-wall workpiece, the ordinary lathe should also avoid the deformation of the workpiece due to the clamping force. Here are the ways to ensure the coaxiality and perpendicularity.
1. Completing the turning process one time
In single piece small batch production, the whole or most of the surface of the workpiece can be finished by clamping once on the chuck or faceplate. This method has no positioning error, and higher accuracy can be obtained if the lathe is of higher precision. But when this method is used, it is necessary to change the tool holder frequently. It is difficult to grasp the size of the tool holder, and the cutting parameters need to be changed frequently.
2. The common lathe adopts the spindle as the positioning datum
When turning small and medium-sized shaft sleeves, pulleys, gears and other workpieces, the machined holes are generally used as the positioning criteria and the spindle positioning method is used for turning. There are two kinds of common mandrels.
(1) The mandrel of the dinner frame has two kinds of small taper mandrel and cylindrical mandrel. Small taper spindle taper C= (l: 1000) - (1: 5000), this is a simple centering mandrel manufacturing precision is high, but can not withstand axial positioning, small cutting force, loading and unloading is not easy. When the workpiece is clamped by the step mandrel, the gap between the cylindrical part of the mandrel and the workpiece bore is kept small, and the workpiece is pressed against the nut.
The utility model is characterized in that a plurality of workpieces can be clamped at once, and the workpiece is more convenient to load and unload by adopting an open gasket, but the centering accuracy is low, and the utility model can only be guaranteed about.02mm coaxial.
(2) The expanding mandrel and the expanding mandrel depend on the expansion force produced by the elastic deformation of the material to fix the workpiece. The taper angle of the expansion mandrel is preferably 30. The thinnest part of the wall is J - 6mm. In order to expand the force evenly, the groove can be made into three equal parts. Long term expansion mandrel can be made of spring steel. The expansion mandrel is easy to handle and has high centering precision, so it is widely used.
3. The outside of the lathe is used as the locating datum and the soft claw is adopted
When the outer circle is larger, the inner hole is smaller and the length is shorter, and the outer circle of the workpiece is used as the reference to guarantee the positional accuracy, the lathe is generally equipped with a soft gripper to clamp the workpiece.
The soft claws are made of steel which is not quenched. When the utility model is used, the soft claw is loaded into the chuck, and then the soft claw vehicle is formed into the required size of the arc. In order to eliminate clearance, a suitable cylinder (or ring) shall be placed in the claw (or claw) outside the claw. When the outer part of the workpiece is clamped with a soft claw (or called a positive claw), the locating cylinder shall be placed in the inside of the claw. When the soft jaw is used to clamp the workpiece (or anti claw), the locating ring shall be placed outside the claw. When the soft jaw is used to clamp the workpiece, because the soft claw is formed on the lathe itself, it can ensure the clamping precision; secondly, it is difficult to clamp the surface of the workpiece when the machined surface or the soft metal is clamped.
4The ordinary lathe uses a lifting set to clamp the workpiece
The car thin-walled workpiece, due to the difference in the cut workpiece, clamping force is easy to deform, to prevent or reduce deformation of thin-walled sleeve parts, often using open clamp work piece suit. Because the contact area of the opening sleeve and the workpiece is large, the clamping force is evenly distributed on the outer circle of the workpiece, so that the clamping deformation can be reduced, and the higher coaxiality can be achieved. When in use, the first paperback in the round slotted sleeve, and then clamped together in three jaw self centering chuck.
5 Ordinary lathe surface with clamping workpiece
For the large diameter, size precision and shape, position precision requirements of the thin wall disc workpiece, can be installed in the disc on the car cutting, using the end face pressing method, the workpiece is not easy to produce deformation.
6 The ordinary lathe clamps the workpiece with special clamp
According to the characteristics of the processing parts, the design and manufacture of special fixture, the workpiece into the clamp(with excircle positioning), with the locking nut to clamp the workpiece axial, can prevent workpiece deformation.