Sinotruk jinan bridge box co., LTD., the workshop Kong Yuan passive spiral bevel gear plate using radial drilling machine, the use of common high speed steel drill bit for processing. As the company's production scale expands unceasingly, the original processing methods cannot satisfy the production rhythm, therefore, the workshop has introduced the advanced CNC machining center. Nc machine tool has the characteristics of high processing efficiency, product quality is stable, especially suitable for mass production.
The workshop in the processing of alloy grinding head for HOWO passive spiral bevel gear, with 16 phi the 17th hole, its material is SAE8822H. This product raw material hardness in HB165-190, due to certain ingredients of Ni element content, viscosity is bigger. According to the characteristics of the workpiece, selecting proper bit, optimization of cutting parameters, improve the machining efficiency become the urgent matter.
Bit selection of materials
According to the requirements of the material processing characteristics of drill bit has the following characteristics: the hardness of bit must be greater than the hardness of the workpiece processed; Due to the bit when machining under large torque and axial force, therefore must have enough strength and toughness; Due to the good toughness and processed materials requirements are sharp enough when cutting edge, so the cutting tool material must have enough ability to resist wear and tear, such ability reduce work hardening; Due to the chemical characteristics of the workpiece is higher, therefore requires cutting tool materials and titanium alloy affinity is poor, so as to avoid stroke diffusion caused by knife, the breaking of a rod phenomenon.
At present, are suitable for making the cutting tool material is extremely wide range, including tool steel, cemented carbide, superhard materials, etc.
At first, try using common high speed steel drill bit for coating test, common high speed steel drill bit price is low, when the coating technology, can obviously reduce the coefficient of friction of tool and the workpiece, enhance the knives' service life. But due to the high speed machine tool, use bit strength is not enough, cause bit broken in the processing, the effect is not ideal.
Cemented carbide is a newly developed a kind of cutting tool material, suitable for most coarse finishing materials, including steel, cast iron, special material and plastic. Therefore, decided to adopt the overall carbide drill.
Determine the parameters of drill grinding
1. The main auxiliary plane twist drill
Several main auxiliary plane as the base of twist drill, cutting plane, the profile and column section.
If you don't consider the supplementary motor, auger bit the main base of an arbitrary point on the cutting edge, due to the architecture characteristics of twist drill, drill master of each point on the cutting edge is base level changes.
The main cutting plane of an arbitrary point on the cutting edge, is a direction of cutting speed and cutting point of plane of the machined surface in that point. Vertical cutting plane and reference plane, and the main cutting edge on the cutting plane is not the same at every point. Main column section of an arbitrary point on the cutting edge is through the point and with the center line of the drill bit for the center line of the cylinder, different column section is different on the main cutting edge radius of the cylinder.
2. The selection of main geometrical parameters of twist drill bit
Twist drill bit selection of geometric parameters including the selection of drill vertex Angle, the drill cutting edge Angle before and after the choice of the Angle, spiral Angle of drill bit for bit life analysis, and the influence of relevant processing edge.
Width and drill bit apex Angle decided to chip the size of the anterior horn. When the drill bit diameter and feed must increase the apex Angle, narrow, iron filings, the unit on the cutting edge of load loss. Apex Angle has a great influence on the rake Angle, the corresponding increase apex Angle is helpful to improve the cutting condition linger-sometimes constantly place. Apex Angle influence the direction of the chip flow. According to relevant tool design data, combined with the processed products hardness is not high, but the characteristic of the large viscosity, selecting the bit apex Angle is 140 °.