1. Parts clamping
(1) Selection of positioning reference
When machining in a machining center, the positioning of parts should still follow the six-point positioning principle. At the same time, special attention should also be given to the following points:
1) When performing multi-station machining, the selection of the positioning reference should consider the ability to complete as much processing as possible, even if the positioning method can be processed on each surface. For example, for a box part, a combined positioning method with one side and two pins is used as much as possible.
2) When the positioning reference of the part is difficult to coincide with the design reference, the assembly drawing shall be carefully analyzed to specify the design function of the design reference of the part. Through the calculation of the dimensional chain, the dimensional and positional accuracy between the positioning reference and the design reference shall be strictly specified to ensure that Precision.
3) The programming origin and the part positioning reference may not coincide, but there must be a certain geometric relationship between the two. The choice of programming origin is mainly considered for ease of programming and measurement. For example, the parts in Fig. 5.7 are machined with Φ80H7 and 4-Φ25H7 holes on the machining center, where the 4-ф25H7 is based on the ф80H7 hole and the programming origin should be selected on the centerline of the ф80H7 hole. When the part positioning reference is A, B on both sides, the positioning reference and programming origin do not coincide, but the same can guarantee the processing accuracy.
(2) Selection of fixtures
At the machining center, the task of the fixture is not only to clamp parts, but also to use the positioning reference as a reference to determine the machining origin of the part. Therefore, the positioning reference must be accurate and reliable.
(3) Clamping of Parts
When considering the clamping scheme, it should be ensured that the clamping is reliable and the clamping deformation should be minimized.
2, the choice of tools
The basic requirements for machining tools in machining centers are:
1) Good cutting performance: Can withstand high-speed cutting and strong cutting and stable performance;
2) Higher accuracy: The accuracy of the tool refers to the shape accuracy of the tool and the positional accuracy of the tool and the chucking device;
3) Equipped with a complete tool system: to meet the requirements of multi-knife continuous processing.