Main Characteristics Of Deep Hole Drilling Machine
Jan 12, 2019


Profile of deep hole processing: Deep hole drilling (ratio of hole depth to hole diameter > 5) occupies a very important position in the field of mechanical processing, accounting for more than 40% of the hole processing volume. With the progress of science and technology, the emergence of new high-strength, high-hardness and high-value hard-to-machine deep-hole parts, and the continuous improvement of processing depth, accuracy and efficiency of workpieces, make deep-hole processing become the key process and processing difficulties in mechanical processing. Traditional processing methods are due to the stiffness of the process system, cutting discharge and cooling and lubrication problems. It is more and more difficult to satisfy or even fail to meet the requirements of precision, efficiency and material in deep hole processing. Therefore, deep hole drilling needs the support of a specific drilling technology.


Deep hole drilling can adopt a variety of machine tool installation methods: workpiece rotation, tool feed movement; workpiece fixed, tool rotation and feed movement; workpiece rotation, tool reverse rotation and feed movement. The specific way to adopt depends on the characteristics of the workpiece and the situation of the hole processed.


Usually there are two kinds of deep hole drilling tools: gun drill and BTA single pipe drill.


The main characteristics of CNC deep hole drilling are as follows:

Extremely high material removal rate; under normal processing conditions, drilling deep holes run through at one time without tool withdrawal; excellent hole size accuracy, straightness, surface roughness can be obtained, and various forms of deep holes can be processed, such as cross holes, blind holes, oblique holes, etc. High consistency of processing quality. When drilling deep holes, the whole drilling process has very high requirements for cutting tools, machine tools and related equipment.


Deep hole processing is in a closed or semi-closed state, so the cutting condition of the tool can not be observed directly. At present, we can only judge whether the cutting process is normal by listening to the sound, looking at the cutting, observing the machine load, pressure gauge, touch vibration and other appearance phenomena.

Cutting heat is not easy to spread. In general, 80% of the cutting heat is taken away by chips in the process of cutting, while only 40% in deep hole drilling. Tools account for a large proportion of the cutting heat. They are diffused late and easily overheated. The cutting edge temperature can reach 600 degrees. CNC deep hole drills must adopt compulsory and effective cooling method.


Chips are not easily discharged. Because of the depth of the hole and the long cutting path, it is prone to blockage, which causes the bit to collapse. Therefore, the length and shape of chips should be controlled and compulsory chip removal should be carried out.


The rigidity of NC deep hole drilling system is poor. Due to the limitation of the size of the hole, the length of the hole is relatively large, the drill pipe is thin and long, the rigidity is poor, the vibration is easy to occur, and the drilling hole is easy to deviate, so the support guidance is very important. This is more prominent in gun drilling machine tools.


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