A Brief Discussion on Machine Base Knowledge
The casting machine base should be suitable for the design process requirements of castings
The structure and shape of the machine base should be simple to ensure that the number of sand molds used in the casting process is as consistent and minimal as possible, in order to facilitate mold making, shaping, and cleaning.
The thickness of the machine base should be as uniform as possible to avoid looseness and cracks. If objective and performance requirements cannot be met, efforts should be made to ensure a smooth transition.
Try to avoid using thick solid sections as much as possible to prevent excessive metal accumulation and the formation of shrinkage, porosity, and cracks.
Reasonably use reinforcing bars. Strengthening ribs can improve the mechanical strength of castings, compensate for weak links, prevent cracking, and reduce metal accumulation. For example, the inner cavity of a medium-sized machine base often has circular reinforcing ribs, while the bottom of a small machine base often has plate-shaped reinforcing ribs between the outer circle.
The connection between the ribs and feet and the machine base wall should have an appropriate fillet radius.
The walls and ribs perpendicular to the casting parting surface should have an appropriate pitch for mold pulling and core removal.
Structural characteristics of welding machine base
The structure of the welding machine base cannot be forced to be exactly the same as the shape of the casting machine base, but should be suitable for the process requirements of the welding design.
The shape of the blank should be simple, and hot-rolled steel plates and profiles should be used as much as possible.
The length of the parts cut from the steel plate should be short, the contour should be simple, and consideration should be given to nesting to make the most of the steel plate.
The welding length should be shortened as much as possible, and the distribution of welds should be convenient for welding.
Due to the different material composition of welding rods compared to steel, in order to reduce the impact of welding seams on magnetic permeability, the welding seams should be arranged on the center line of the magnetic poles.
Requirements for the Convenience of Machine Base Processing
The selection of machining accuracy and roughness should be reasonable. Excessive precision and roughness will sharply increase processing costs.
The processing parts should be minimized as much as possible, and the cutting length should be minimized. Especially in areas with high precision and roughness, this should be the case.
Intermittent cutting should be avoided as much as possible for the parts of the car or boring. For example, when the inner cavity of the magnetic pole contact part on the DC motor base is circular, the protruding part should be continuous in the circumferential direction to avoid the need to reduce the cutting speed due to the impact of intermittent cutting. When the inner cavity is polygonal, only the machining method of planing or inserting can be used, and it is reasonable to design the contact part of the magnetic pole in a convex platform shape.
In order to simplify drilling and tapping, the diameter of the holes and the specifications of the bolt holes should be as uniform as possible. Under the condition of structural permission, try to use through holes as much as possible.
Small machine bases processed by combination machine tools or automated machine tools should minimize the number of inner diameter stages and use inner stops to reduce the workload of adjusting machine tools.
Requirements for assembly, maintenance, and installation
The contact end face between the machine base and the end cover should ensure good contact. For this reason, there should be a certain gap (2-5 millimeters) in the parts that do not require contact, and the machine base stopper must be angled.
The position of the foot hole should be convenient for inserting bolts from above and for wrench operation.
There should be two bolt holes on the foot of each side of the large motor for lifting the machine base during disassembly.
The two halves of the DC motor base should be separated slightly above the horizontal diameter, so that when disassembling the upper half, it is not necessary to remove the magnetic poles at the joint, which is convenient for maintenance and assembly.
