Features of processing and assembly of composite products

The article deals with the problems of assembling cylindrical products, consisting of sector parts with dihedral angles. One of the main problems in the assembly of such parts is the accuracy of dihedral angles during processing. Using the example of assembling a product from 3-sector parts, it is shown that even with the exact equality of dihedral angles of 120 °, there is no unambiguous basing of these parts during assembly. Since spatial errors of dihedral angles occur during the processing of the planes of sector parts, it is practically impossible to achieve a tight fit of the planes during assembly. Possible options for assembling sectors with a total angle greater than and less than 360 ° are shown. In this case, a gap in the joint always appears between the planes of the dihedral angles. If the total angle exceeds 360 °, the assembly cannot be carried out at all, since it is impossible to ensure the fit of the planes of the dihedral angle. And if the total angle turns out to be less than 360 °, the assembly can be carried out, but at the same time, a noticeable twist angle or “propeller” of the assembled sectors appears, as well as the ambiguity of the assembly before and after processing. Using the methods of analytical geometry, it is proved that for the collection without a gap of 3 sectors, it is necessary and sufficient that the sum of all dihedral angles of the sectors be less than or equal to 360 °. Since it is impossible to ensure the exact equality of the sum of all dihedral angles of 360 °, a characteristic “propeller” is always formed during assembly. To obtain a gap-free connection, a new method for the selective assembly of sectors was proposed and a device scheme for controlling dihedral angles was developed. This method of selective assembly will allow you to select sectors in such a way that the angle of their “twist” in the assembled form is minimal. At the same time, when selecting sectors, it is possible to set the direction of “twisting” - clockwise or counterclockwise, depending on the direction of the cutting forces.