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2024

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01

What if the gear runs out of order?

Source:

Time:2024-01-12 15:48


Gear due to the structure type, material and heat treatment, operating environment and conditions of different factors, the form of failure is also different, common gear failure has the following types of forms.

(1) Tooth surface wear

Insufficient lubricating oil or unclean oil will cause abrasive wear on the tooth surface, change the tooth profile, increase the backlash, and cause tooth breakage due to excessive thinning of the gear. Under normal circumstances, only when the lubricating oil is mixed with abrasive particles, it will cause tooth surface abrasive wear during operation.

(2) Tooth surface bonding and abrasion

For the transmission of heavy-duty and high-speed gears, the temperature of the tooth surface working area is very high. Once the lubrication condition is poor, the oil film between the tooth surfaces will disappear, and the metal of one tooth surface will be welded on the other tooth surface meshing with it. A scratch-like gluing perpendicular to the pitch line is formed on the tooth surface. When the new gear is put into use without running-in, this phenomenon often occurs in a certain part, causing the gear to scratch.

(3) tooth surface contact fatigue

In the actual meshing process, the gear has both relative rolling and relative sliding, and the friction force of relative sliding is opposite to the direction on both sides of the node, resulting in pulsating load. The effect of load and pulsation force causes pulsating cyclic shear stress in the deep surface layer of the gear. When this shear stress exceeds the fatigue limit of the gear material, fatigue cracks will occur on the contact surface. With the expansion of the cracks, the tooth surface will peel off small pieces of metal and form small pits on the tooth surface, which is called pitting. When the "pitting" is expanded into a piece, the metal block on the tooth surface is peeled off. In addition, the material is not uniform or local scratches, but also easy to contact fatigue on a tooth first, resulting in peeling.

(4) Bending fatigue and broken teeth

In the process of operation to bear the load of the gear teeth, like the cantilever beam, the root of the bending stress of the pulse cycle is very large, when this periodic stress exceeds the fatigue limit of the gear material, will produce cracks in the root, and gradually expand, when the remaining part can not bear the transmission load will occur when the tooth breakage phenomenon. Gear due to the work of serious impact, eccentric load and uneven material may also cause broken teeth. Broken teeth and pitting are the main forms of gear failure.

Gear faults can also be divided into local faults and distributed faults. Local faults are concentrated on one or several teeth, while distributed faults are reflected in each gear tooth.