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Technological Principle of Manufacturing Gear by Metal Cutting

2019/8/10 9:50:36 click:

Gears are mechanical parts that rely on the meshing of teeth to transmit torque. By cooperating with other toothed mechanical parts, the rotation speed, torque and direction can be changed. The quality of gears directly affects the noise, smoothness and service life of equipment. Especially for gears with many teeth, large diameter, long tooth surface, high precision requirements and long period, strict technological guarantee is required in the manufacturing process. All links such as tooth blank, clamp, cutter, machine tool, cutting oil and technological environment must be well controlled.

What is the technological principle of gear manufacturing?

I. Technological Principle of Gear Cutting

(1) Hobbing is to manufacture gears according to the principle of generating method. It is a process of meshing and rolling of a pair of staggered helical gear pairs. Its helix angle is very large → worm → slotting and backhoe → hob connects the hob spindle with the operating table with a chain, and the cutter-workpiece → conjugate tooth surface; The axial feed of the hob forms an involute tooth profile and forms a linear tooth length (wire).

(2) Gear shaping is to use gear-shaped gear shaping cutter or rack-shaped comb cutter to cut teeth. When the gear shaper is used to cut teeth, the cutter reciprocates axially with the main shaft of the gear shaper. At the same time, the gear shaper and the workpiece rotate with each other according to a certain speed ratio by the machine tool chain, and the tooth shape of the gear is accurately enveloped.

(3) There are two methods of tooth planing: profiling and generating.  The profiling method is to use a profiling tool that enlarges the profile to cut the profile by controlling the tip trajectory of a single-edge planing tool.  The generating method of planer teeth is to use a pair of planers to plane the two sides of the gear teeth respectively, and the path of reciprocating movement of the planer blade represents the tooth surface of the imaginary crown wheel.

Second, gear cutting equipment selection

(1) To manufacture gears on a numerical control gear hobbing machine, arc interpolation method shall be used according to the workpiece drawing parameters, fixture size, hob parameters and process requirements, and the gear shall be symmetrical to the workpiece tooth width, drum-shaped straight teeth with arc and helical teeth.

(2) Under the condition of meeting the actual use requirements, the number of numerical control shafts shall be reduced as appropriate for the mechanical part transformation, and the original mechanical gear hobbing machine shall be changed less.

(3) The feed shaft is separately controlled by a motor through numerical control. The feed of numerical control machine tools shall meet the basic requirements of no clearance, low friction, high rigidity, etc.

(4) The real-time control module calculates the control instruction interpretation and execution according to the process requirements.

(5) Due to the high difficulty of gears, especially for workpieces made of superhard materials such as stainless steel and titanium alloy, special gear cutting oil should be selected to ensure the accuracy of gear workpieces.

Three, gear cutting oil selection

(1) Silicon steel is a relatively easy-to-cut material. Generally, for the purpose of cleaning gear workpieces, gear cutting oil with low viscosity will be selected on the premise of preventing burrs.

(2) When selecting cutting oil for carbon steel gear cutting, the better viscosity should be determined according to the technological difficulty.

(3) Galvanized steel will have chemical reaction with chlorine additives, so when selecting gear cutting oil, attention should be paid to the problem of possible white rust on gears.

(4) Stainless steel gear cutting generally uses gear cutting oil containing sulfur and chlorine compound additives to ensure extreme pressure performance while avoiding problems such as burrs and cracks on workpieces.

The above is the selection method of mechanical gear manufacturing equipment. Reasonable selection of equipment type, workpiece material and oil performance can effectively improve the process accuracy and efficiency.

Source of this article:https://ympcnc.com/