The common processing methods of deep hole drilling are as follows
① The cooling water hole and heating hole of small and medium-sized mold are usually processed on vertical drilling machine and radial drilling machine by common drill or lengthened drill. During processing, it is necessary to timely discharge and cool the chips, with small feed rate to prevent hole deflection.
② The holes of medium and large moulds are generally processed on radial drilling machine, boring machine and deep l drilling machine. The more advanced method is that they can be processed together with other holes on the machining center machine tool.
③ Long low precision holes can also be drilled from both ends after marking.
④ The holes with high requirements for verticality shall be guided by certain technological measures, such as the use of drilling jigs.
When drilling deep holes, attention shall also be paid to:
a. When the drilling depth is 3 times of the diameter, it is necessary to lift the drill bit for chip removal, and then every time a certain depth is entered, the drill bit shall exit for chip removal, so as to prevent the drill bit from breaking due to chip blocking.
b. When the depth of some deep holes exceeds the total length of the bit or is deeper, lengthening rod bit or connecting rod bit can be used for drilling. These two kinds of bits can be purchased or self-made.
c. For some special deep holes, such as the processing of some through holes, special equipment is generally used or carried out on the machine tool. At this time, special lengthening rod drill bit is required. This kind of bit needs to be developed on its own according to the specific conditions of the workpiece. In general, deep hole machining process, it is impossible to process all the hole depths with a single cutting. It is necessary to feed several times to solve the problems of chip removal, cooling, etc. and the machining accuracy is low. Gun drill can solve these problems, so deep holes with diameter less than 20 mm, such as cooling water holes, can be processed by gun drill. WeChat official account: hcsteel gun drill. The working part of gun drill is made of high-speed steel or hard alloy and seamless steel pipe by butt welding. During operation, the workpiece rotates the drill bit to feed, and at the same time, the high-pressure cutting fluid is injected from the tail of the drill pipe. After the cutting area is cooled, the cuttings are washed out along the drill pipe groove.
The characteristics of gun drilling hole are as follows:
① The ratio of length to diameter of the hole can reach 100:1 or greater;
② High production efficiency, only one process can obtain high quality holes;
③ In a long period of continuous machining, the change of hole size is very small (within 0.02-0.05mm);
④ When the hardness of workpiece material is up to 45hrc, it can still be processed;
⑤ The quality of the hole is very good, usually no further processing is needed;
⑥ Do not need skilled operation technology;
⑦ The tool durability is 10-15 times higher than that of twist drill, and it can process hundreds to several dry workpieces every time;
⑧ The position accuracy of the hole is the same as that of the adjustment.
About the author