Gears are mechanical parts that rely on the meshing of teeth to transmit torque. By cooperating with other toothed mechanical parts, the rotation speed and torque 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. The following is a brief description of the principle of gear manufacturing process by Yixin Precision Metal and Plastic Ltd.:
Forging-normalizing-roughing each part, leaving allowance-finishing each part-hobbing-chamfering-inserting keyway-deburring-shaving-heat treatment, tooth surface quenching-grinding-quilting-inspection
Second, the gear process principle
(1) Hobbing process 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. A chain is used to connect the hob main shaft with an operating table, and the hob is axially fed to produce full teeth.
(2) The gear shaping process uses a gear-shaped gear shaping cutter or a 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, and at the same time, the gear shaper and the workpiece interact with each other at a certain speed ratio by the machine tool chain to form an expansion, so that the tooth shape of the gear is accurately enveloped.
(3) There are two kinds of tooth planing techniques: profiling and generating. The profiling method is to use a profiling tool that enlarges the profile to cut out the profile by controlling the point 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.
Three, gear cutting equipment
(1) When manufacturing gears on a numerical control gear hobbing machine, according to the workpiece drawing parameters, fixture dimensions, hob parameters and process requirements, circular arc interpolation method shall be used to manufacture drum-shaped straight teeth and helical teeth gears with circular arcs symmetrical to the workpiece tooth width.
(2) In order to reduce the investment and reduce the number of numerical control shafts as appropriate under the condition that the mechanical part transformation meets the actual use requirements, the original mechanical gear hobbing machine is less changed.
(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) according to the process requirements to calculate the new control instruction execution.
(5) Due to the high manufacturing 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.
Four, gear cutting oil
(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 and degreasing method.
(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. Using special gear cutting oil can avoid the problem of rust, but degreasing should be done as soon as possible.
(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.
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Source of this article:https://www.ymp.com.hk/