The technical requirements of the bench drill spindle sleeve are mainly divided into two parts, namely, the design principle of the external shape and size and the technical requirements for the selection of part materials.
The material selection of the spindle sleeve of the drilling machine and the design of the external shape and size The function of the spindle sleeve of the drilling machine is to transmit the rotary motion of the processing parts and drive the spindle, that is, the cutter, to move up and down. Considering the above reasons and characteristics, the following two aspects will be designed and introduced respectively according to the material selection of the spindle sleeve and the size design of the external shape.
1. Material Selection of Spindle Sleeve of Drilling Machine
Considering the nature and working characteristics of the spindle sleeve, the analysis is as follows: as one of the main parts of the drilling machine, the spindle sleeve must ensure its durability, and the main failure form of the spindle sleeve is fatigue failure, so the selected materials should have good strength, toughness and wear resistance. Therefore, good carbon structural steel is often selected, such as steel grades 35, 45 and 50. The material of spindle sleeve (i.e. 45 # steel) is selected reasonably, which can meet the normal processing and production requirements. Therefore, the material of the spindle sleeve of the drilling machine is determined to be No. 45 steel.
2. External shape and dimension of spindle sleeve of drilling machine
The design and principle According to the practice, the failure form of sleeve parts under alternating stress is completely different from that under static stress. Its main features are:
⑴ When parts are damaged, the value of alternating stress is far less than the static strength limit of materials, or even lower than the yield point.
⑵ The parts are fragile fracture when they are damaged. Even for materials with good plasticity, there is no obvious plastic deformation when they are broken. Therefore, the fracture is not easy to detect in advance, which shows the danger of such damage.
⑶ The fracture surface is damaged in two areas, smooth area and rough area. In the smooth area, it is sometimes possible to see an arc curve with microcrack as the starting point (crack source) gradually expanding.
The experiments show that the endurance limit of materials is not only related to the type of materials, stress forms and cycle characteristics, but also affected by the shape, overall dimensions of parts and the indicated processing quality. Therefore, I design reasonable dimensions according to the above conditions to meet the strength requirements, and must also meet the reliable positioning and fastening of parts on the spindle sleeve, and facilitate processing, manufacturing, disassembly and adjustment.