The internal hole surface processing method is more, commonly used drilling, reaming, reaming, boring, grinding hole, pull hole, grinding hole, honing hole, rolling hole and so on. First, drilling The use of a drill to drill a hole in a solid part of the workpiece is called drilling. Drilling is rough machining. The attainable dimensional tolerance grade is IT13~IT11, and the surface roughness is Ra50~12.5μm. Due to the long twist drill diameter, small diameter and poor rigidity of the drill core, and the effect of the chisel edge, the drilling process has the following characteristics: 1. The drill bit is easily deflected. Due to the influence of the chisel edge, centering is inaccurate, and the drill bit is easily deflected when cutting in; the rigidity and guiding action of the drill bit are poor, and the drill bit is easily bent during cutting. When drilling in the drill press, as shown in Fig. 7-2a, the axis of the hole is easily displaced and not straight, but there is no significant change in the hole diameter; when drilling in the lathe, as shown in Fig. 7-2b, the hole diameter is easily caused. The change, but the axis of the hole is still straight. Therefore, the end face should be machined before drilling and pre-drilled with a drill or center drill, as shown in Figure 7-3, to center the drill. When drilling small holes and deep holes, in order to avoid the misalignment and misalignment of the holes, drill holes should be drilled as much as possible. 2. The aperture is easily enlarged. When drilling, the radial force of the two cutting edges of the drill bit will cause the aperture to expand; the incision and lead of the horizontal lathe when drilling are also important reasons for the aperture expansion; in addition, the radial runout of the drill bit also causes the aperture enlargement. 3. Pore ​​surface quality is poor. Drilling chips are wider, they are forced to spiral in the hole, and when they flow out, they rub against the hole wall to scratch the machined surface. 4. The axial force is large when drilling. This is mainly caused by the chisel edge of the drill. Tests have shown that 50% of axial force and 15% of torque at the time of drilling are generated by the chisel edge. Therefore, when the drilling diameter d>30mm, drilling is generally performed twice. Drill (0.5~0.7)d for the first time and drill to the required hole diameter the second time. Since the chisel edge does not participate in the cutting for the second time, a larger amount of feed can be used, so that the surface quality and productivity of the hole are improved. Second, reaming Reaming is the use of reamers for further processing of drilled holes to increase the aperture and improve accuracy and reduce surface roughness values. The dimensional tolerance grades available for reaming are IT11~IT10, and the surface roughness is Ra12.5~6.3μm. It belongs to the semi-finishing method of the hole and is often pre-machined before reaming, and can also be used as a hole with low precision. The final processing. The hole expansion method is shown in Figure 7-4. The hole allowance (Dd) can be read by the table. The form of reamer varies with diameter. The diameter of Φ10~Φ32 is a taper reamer drill, as shown in Figure 7-5a. Diameter Φ25 ~ Φ80 for the sleeve reamer drill, as shown in Figure 7-5b. The structure of reamer drill has the following characteristics compared with twist drill: 1. Rigidity is better. Due to the small amount of reaming knife and less chips, the flutes of the reamer are shallow and narrow, and the diameter of the core is large, which increases the rigidity of the working part of the reamer. 2. Good guidance. The reamer has 3 to 4 teeth, the number of edges around the tool increases, and the guiding effect is relatively enhanced. 3. Chip conditions are better. The reamer drill does not have a chisel edge to participate in the cutting. The cutting is brisk, a larger feed rate can be used, and the productivity is higher. Because the swarf is less, the swarf is smooth and it is not easy to scratch the processed surface. Therefore, compared with the drilling, the reaming hole has higher machining accuracy, lower surface roughness, and can correct the axial error of the drilling to a certain extent. In addition, the machine for hole expansion is the same as the drill hole. Third, reaming Reaming is a finishing method for holes based on semi-finishing (reaming or semi-finishing). Reaming hole size tolerances up to IT9 ~ IT6, surface roughness values ​​up to Ra3.2 ~ 0.2μm. Reaming methods are organic and hand hinges. The reaming on the machine is called the machine hinge, as shown in Figure 7-6; the reaming by hand is called the hand hinge, as shown in Figure 7-7. Reamers are generally classified into machine reamers and hand reamers. As shown in Figure 7-8. Machine reamers can be divided into shank (diameter 1 ~ 20mm for the straight shank, diameter 10 ~ 32mm for the taper shank, as shown in Figure 7-8a, b, c) and sleeve type (diameter 25 ~ 80mm, such as Figure 7-8f). Hand reamers can be divided into integral (as shown in Figure 7-8d) and adjustable (as shown in Figure 7-8e) two. Reaming can be used not only to machine a cylindrical hole, but also to use a taper reamer to machine a conical hole (as shown in Figure 7-8g, h). 1. Reaming method Reaming margin is very small, if the margin is too large, the high cutting temperature will expand the diameter of the reamer and cause the aperture to expand, which will increase the number of chips and scratch the surface of the hole. If the margin is too small, it will leave the original Hole marks affect the surface roughness. The general rough hinge allowance is 0.15~0.25mm, and the precision hinge allowance is 0.05~0.15mm. Reaming should use low cutting speed to avoid build-up and induced vibrations. As shown in Fig. 7-9a, when reaming on the lathe, if the axis of the reamer mounted in the tailstock sleeve is offset from the axis of rotation of the workpiece, the aperture will be enlarged. As shown in Fig. 7-9b, when the reaming hole is drilled on the drill press, if the axis of the reamer is offset from the axis of the original hole, the shape error of the hole will be caused. Machine reamer and machine tool commonly used floating connection to prevent reaming aperture expansion or hole shape error. The floating chuck used for the floating connection between the reamer and the machine spindle is shown in Figure 7-10. The taper shank 1 of the floating chuck is installed in the taper hole of the machine tool, and the reamer taper shank is installed in the taper sleeve 2. The blocking pin 3 is used to receive the axial force, and the pin 4 can transmit the torque. Due to the large gap between the tail and the large hole, the pin 4 and the small hole of the taper sleeve 2, the reamer is in a floating state. 2. Reaming process features (1) The accuracy and surface roughness of the reaming hole mainly do not depend on the accuracy of the machine tool, but depend on the accuracy of the reamer, the installation method of the reamer, the machining allowance, the cutting amount, and the cutting fluid. For example, under the same conditions, the accuracy and surface roughness obtained by reaming holes on a drill press and reaming on a lathe are basically the same. (2) The reamer is a sizing finishing tool. The reaming hole is easier to ensure dimensional accuracy and shape accuracy than the fine bore hole, and the productivity is also high, especially for small holes and elongated holes. However, due to the small reaming allowance, the reamer is often floating, so the axis misalignment of the original hole cannot be corrected, and the accuracy of the position of the hole and other surfaces needs to be ensured by the previous process or the subsequent process. (3) The reaming hole has poor adaptability. A certain diameter reamer can only machine one hole of diameter and dimensional tolerance grades. To increase the hole tolerance class, the reamer needs to be ground. Reamed aperture is generally less than Φ80mm, commonly used in Φ40mm or less. For the stepped holes and blind holes, the reaming process is poor. Fourth, bore hole, car hole Boring is the use of boring tools to drill, cast or forge holes for further processing. It can be done on a lathe, boring machine or milling machine. Boring is one of the commonly used hole processing methods and can be classified into rough, semi-finished, and fine boring. The rough size tolerance grade is IT13~IT12, the surface roughness value is Ra12.5~6.3μm; the semi-finite flaw size tolerance grade is IT10~IT9, the surface roughness value is Ra6.3~3.2μm; The dimensional tolerance grade is IT8~IT7 and the surface roughness value is Ra1.6~0.8μm. 1. Lathe hole The lathe hole is shown in Figure 7-11. If the car does not have a hole or a hole with a right-angled step (Fig. 7-11b), the turning tool can do longitudinal feed movement. When the hole is cut to the end of the hole, the turning tool changes to the horizontal feed movement and then the inner end face is machined. In this way, the inner end face can be well connected with the hole wall. Turn the inner hole groove (Fig. 7-11d), insert the turning tool into the hole, do horizontal infeed first, cut to the required depth and then do the longitudinal feed movement. The hole on the lathe is the rotation of the workpiece and the movement of the turning tool. The size of the hole can be controlled by the depth of cut and the number of passes of the turning tool, and the operation is convenient. The lathe hole is used to process the holes of the disc cover and the small bracket parts. 
=4~10m/min, precision hinge =1.5~5m/min. The feeding amount of the machine hinge can be 3~4 times higher than that when drilling, generally 0.5~1.5mm/r. In order to dissipate heat and to remove swarf, reduce friction, dampen vibration, and reduce surface roughness, suitable cutting fluid should be used for reaming. Reaming steel commonly used emulsion, reaming cast iron pieces available kerosene. 
