Deep hole processing flow and characteristics
Deep hole, slender hole processing method: center hole - drilling - reaming - reaming
Deep hole processing refers to a hole having a hole depth to diameter ratio L/d ≥ 5. Modern processing of deep holes is mainly processed by special equipment and special auxiliary tooling. It is characterized by high efficiency, good quality and low labor intensity. However, some small and medium-sized processing enterprises and individual processing households generally do not have the above-mentioned equipment, so they can only be adapted to local conditions. Because of the simpleness and simplicity, on the ordinary machine tools, the simple and long holes are processed by simple tooling. Machining an elongated hole with a dimensional accuracy of φ12H 7 and a cylindricity of 115 mm. Because the hole wall is thin, the hole is drilled directly with the other chamfer 0.545φ11. 8mm or φ11. 9mm. The heat generated by one cutting is large. There is not enough time to eliminate the machining error caused by thermal deformation and the machining error caused by the residual stress remaining on the surface of the hole wall after drilling. The roughness of the hole wall produced by one drilling is also large, and it is not suitable for direct reaming. Hole processing. Therefore, in order to reduce the influence of thermal deformation and residual stress on the finishing, multiple reaming and full casting of the cooling liquid should be adopted to reduce the machining error left by the roughing to improve the subsequent processing accuracy. Figure 2 shows the processing route of the hole.
●The characteristics of deep hole processing
1. When deep hole machining, the axis of the hole is easy to be skewed, and the drill bit is easy to deflect during drilling.
2. The shank is generally thin and long, with low strength and poor rigidity. It is easy to produce “knife” and vibration, which causes defects such as taper and ripple on the surface of the hole.
3. When drilling or reaming, the chips are difficult to discharge, and the cutting fluid is not easily injected into the cutting zone.
4. It is difficult to see the processing situation during processing, and it is difficult to control the processing quality.
It is not difficult to see that the key technology of deep hole machining is to rationally select the geometric angle of the tool and solve the problem of cooling and chip removal. The measures adopted are as follows:
(1) For deep holes with high precision and low surface roughness, roughing and finishing should be carried out in stages.
(2) The requirements for the tool structure are: first, there is sufficient strength and rigidity, second, the chip removal should be smooth, and third, the cutting night should be injected into the cutting zone in time.
(3) For guiding and auxiliary support, there should be a guiding part for the thin and long shank, and an auxiliary support should be added to prevent the knife and vibration from being generated.
(4) The cutting fluid is conveyed by pressure to strengthen the tool to cool and discharge the chips.
