1. Drilling concept
The inner hole surface is one of the main surfaces on the part. According to the different functions of the part in the mechanical product, the inner hole of different structure has different precision and surface quality requirements. According to the different connection relationship between the hole and other parts, it can be divided into matching hole and non-matching hole; according to its geometric characteristics, it can be divided into through hole, blind hole, stepped hole, tapered hole, etc.; according to its geometric shape Can be divided into round holes, non-round holes, and so on. Since the hole machining is the processing of the inner surface of the part, it is difficult to observe and control the machining process, and the processing difficulty is much larger than that of the open surface such as the outer circular surface. The processing of the hole mainly has the following characteristics:
(1) Hole machining tools are mostly fixed-size tools, such as drills, reamers, etc., the shape and size changes caused by tool wear will directly affect the accuracy of the hole being machined.
(2) Due to the size of the hole to be machined, the cutting speed is difficult to increase, affecting the processing productivity and the quality of the machined surface.
(3) The structure of the cutter is limited by the diameter and length of the hole size, and the rigidity is poor.
(4) When the hole is machined, the tool is generally operated in a semi-closed space, and the chip removal is difficult; the coolant is difficult to enter the processing area, and the heat dissipation condition is not good. Drilling is the method of machining a hole in a solid material with a drill bit. In the drilling machine. Drilling, the workpiece is fixed, the drill bit rotates (the spindle motion is called the main motion), and the axial direction moves downward (called the feed motion). Due to the flaws in the structure of the drill bit and the poor guiding property, the machining quality is affected, and the drilling is rough machining.