3.the boring hole
A boring is a method of augmenting a pre-formed hole with a cutting tool. The boring can be performed either on a trampoline or on a lathe.
1) boring hole method
There are three different ways of processing the boring hole.
a. The workpiece rotates and the tool makes the feed motion. The boringhole on the lathe mostly belong to this type of boring. The characteristic of the process is that the axis of the hole after machining is consistent with the axis of rotation of the workpiece. The roundness of the hole mainly depends on the rotation precision of the machine tool spindle. The axial geometry error of the hole mainly depends on the tool feed direction relative to the workpiece rotation axis. Positional accuracy. This type of boring is suitable for machining holes that have coaxiality with the outer surface.
b. The tool rotates and the workpiece makes the feed motion. The spindle of the boring machine drives the boring tool to rotate, and the worktable drives the workpiece for the feed motion.
c. The tool rotates and feeds the movement. This type of boring is used for the boring. The sling elongation of the ram is changed. The deformation of the ram is also changed. The hole near the headstock is large, away from the headstock. The aperture is small and forms a tapered hole. In addition, the elongation of the mast is increased, and the bending deformation of the main shaft due to its own weight is also increased, and the axis of the machined hole will be correspondingly curved. This method of boring is only suitable for processing shorter holes.
2) King Kong boring
Compared with the general boring, the diamond has the characteristics of small amount of back-feeding knife, small feed rate and high cutting speed. It can obtain high processing precision (IT7~IT6) and very smooth surface (Ra is 0.4~). 0.05). King Kong boring was originally processed with a diamond file and is now commonly processed with carbide, CBN and synthetic diamond tools. Mainly used for processing non-ferrous metal workpieces, but also for processing cast iron and steel parts.
The cutting amount commonly used by King Kong boring is: 0.2~0.6mm, the final boring is 0.1mm; the feed is 0.01~0.14mm/r; the cutting speed is 100~250m/min when processing cast iron, processing It is 150~300m/min for steel and 300~2000m/min for non-ferrous metals.
In order to ensure that the diamond processing can achieve high machining accuracy and surface quality, the machine tool (Golden boring machine) must have high geometric precision and rigidity. The machine tool spindle supports commonly used precision angular contact ball bearings or static pressure sliding bearings, high-speed rotating parts. It must be precisely balanced; in addition, the movement of the feed mechanism must be very stable, ensuring that the table can perform a smooth low-speed feed movement.
King Kong boring has good processing quality and high production efficiency. It is widely used in the final processing of precision holes in a large number of mass production, such as engine cylinder bore, piston pin hole, spindle hole on machine headstock. However, it should be noted that when processing ferrous metal products with diamonds, only the boring tools made of cemented carbide and CBN can be used, and the boring tool made of diamond cannot be used because the carbon atoms in the diamond have a high affinity with the iron group elements. , tool life is low.
3) boring tool
The tool can be divided into a single-edged file and a double-edged tool.
4) Process characteristics and application range of the boring tool
Compared with the drilling-expansion-hinge process, the aperture size is not limited by the size of the tool, and the pupil has a strong error correction capability, which can correct the deviation error of the original hole axis by multiple passes, and can The bore and the positioning surface maintain a high positional accuracy.
Compared with the outer circle of the car, the boring bar system has poor rigidity and large deformation, the heat dissipation and chip removal conditions are not good, the thermal deformation of the workpiece and the tool is relatively large, and the machining quality and production efficiency of the boring hole are not as high as the outer circle. .
From the above analysis, the boring tool has a wide processing range and can process holes of various sizes and different precision grades. For holes and holes with large apertures, high dimensional and positional accuracy, the boring tool is almost the only processing. method. The machining accuracy of the boring is IT9 to IT7, and the surface roughness Ra is . The boring can be carried out on machine tools such as boring machines, lathes, boring machines, etc. It has the advantages of maneuverability and flexibility, and is widely used in production. In large-scale mass production, in order to improve the efficiency of the boring tool, a mold is often used.