Bevel gears are used extensively in a wide variety of industries and mechanical operations due to the most important advantage they offer: smooth and low-noise power transmission between non-parallel shafts at almost any angle or speed. However, due to the mathematical complexity of their design, manufacturing these gears is not an easy process.
TS16949 certified bevel gears manufacturing starts production from a forging, bar stock, or any other formed product such as a casting, depending on the strength requirements of the finished bevel gear. A forged blank is used when a superior strength to weight ratio, as well as better impact and fatigue resistance is necessary.
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The forging, casting or bar stock is machined into a blank. Threads and splines maybe added on to the blank if the design so requires, and other machining processes such as turning, milling, drilling and tapping etc. are carried out prior to teeth cutting.
Next, the bevel gear teeth are cut into the blank. There are two main manufacturing methods to cut bevel gear teeth, and the tooth length and depth forms vary depending on the process adopted. The system uses the single indexing or face milling procedure, where every gap is milled separately, and the gear then rotated by the width of that tooth space. Bevel gears produced via this method have a tapered tooth depth and tooth thickness, and the curvature along the face width is that of a circular arc. This results in a gear, where the ends of the teeth curve slightly inward, allowing for greater tolerance of minor errors in shaft alignment as compared to straight cut teeth.
uses the face hobbing process or the palloid manufacturing process, where the gear rotates constantly during the milling process. This continuous indexing method produces bevel gears with a constant tooth depth and tapered slot width and tooth thickness. The face width of the tooth is curved like an extended epicycloid. Bevel gears with involute tooth length can only be produced via the face hobbing method.
Depending on the end use of the bevel gear, either method may be used to cut teeth.
Next, the gear is subjected to heat treatment – usually case carburizing and hardening, resulting in a surface hardness of 60-63 Rc. The pinion is normally up to 3 Rc harder than the gear to equalize wear and tear. Nitriding, flame hardening and induction hardening are rarely used in bevel gear heat treatment, to avoid significant tooth distortion.
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The required finish machining operations are then carried out, such as turning outer and inner diameters, grinding and other special machining procedures.
The last important procedure involves the hard cutting of the bevel gear. The gear is finished first, and the pinion teeth are modified for optimum tooth contact along the profile and length of the tooth, by changing the curvature radius of the cutting blade. Once the tooth contact requirements are optimized, the gear is mounted for final inspection, including dimension checks, magnaflux or other specific inspections.
Bevel gear manufacturing services provide high precision crafting to maximize the functionality in powertrain / power transmission applications. Learn more about the different types of bevel gear supplier services we can offer you.