Starting from the guide strip layout of gun drill, the factors affecting the straightness of machined hole are analyzed. Because the gun drill processing is carried out in a closed environment, the processing process is very unstable, and the deviation of the gun drill directly affects the straightness of the processed hole, and even causes the workpiece to be scrapped. Through the stress analysis of the gun drill guide bar in the machining process, the stability in the machining process is calculated, the Pro / E three-dimensional model is established and analyzed by ANSYS, the layout parameters of the gun drill guide bar with the highest stability in the machining process are obtained, the drilling test is carried out and good results are obtained. This paper has practical significance for improving the straightness of deep hole with small diameter and large aspect ratio.
Through the analysis of the original machining process of the inner hole of thin-walled slender parts, the causes of bending deformation are found out, and a new process scheme of machining the inner hole with gun drill before carburizing and electric spark grinder instead of internal grinder after carburizing and quenching is put forward, which ensures that the straightness error of the inner hole is within φ According to the requirement within 0.001 mm, the qualified rate of products is greatly improved by trial processing three batches of workpieces, which proves that this method is feasible
Three edge integral cemented carbide gun drill bit is characterized by:
The drill core is thicker and stronger than that of two edge drill, which compensates for the weakness of poor toughness of cemented carbide;
The front end of the tool tip forms a special shape, which can be automatically centered during cutting, so there is no need to process the central hole;
Due to more cutting edges, the feed per revolution increases (up to 20m / min when cutting aluminum), and high-speed cutting can be carried out (up to 1000m / min when cutting aluminum), which can greatly shorten the processing time;
High machining accuracy, dimensional accuracy up to H9, position accuracy of ± 0.011mm and roughness Rz of 20-25 μ m；
Long service life: processing alloy steel, cast iron and aluminum alloy can be 20m and 80m respectively;
It is easy to regrind without special grinding machine. This drill is suitable for machining holes of the following materials with hole depth of 3D ~ 4D: low alloy, titanium alloy, austenitic manganese steel, hard bronze, high hardness cast iron and silicon aluminum alloy. When processing austenitic manganese steel and titanium alloy, the cutting speed can reach 40m / min and 130m / min for aluminum alloy.
This kind of drill requires good rigidity of the machine tool, especially the precision of the spindle bearing of the machine tool and the rotation precision of the drill clamp must be high. Therefore, it is generally used in CNC machine tools or machining centers. Bilz company, Hertel company, Guehring company and ilix company of Germany first launched this kind of drill bit, and then linggaojing Machine Co., Ltd. of Japan also launched products. Bilz's specification is F4 ~ 20mm, Hertel's TF bit is F3 ~ 20mm, Guehring's GS200's specification is F3 ~ 20mm (divided into left and right rotation directions), and ilix's specification is F2 ~ 16mm.
