A method that can effectively improve the life of gears: shot peening process

A method that can effectively improve the life of gears: The relevant description of the shot peening process is as follows for reference.

Shot peening process uses steel shots to hit at high speedgearThe bending part of the tooth root generates compressive stress on the surface, destroys the tensile stress inside the workpiece itself, improves the bending fatigue resistance of the gear tooth root, and can effectively increase the service life of the product.The following describes the principle and effect of shot peening, the process of shot peening and the influence of process parameters on the strengthening effect.

XNUMX. The principle and effect of shot peening

The shot peening process uses high-speed injection of steel shot particles to hit the surface of metal parts, causing elastoplastic deformation of the surface material of the workpiece and presenting a higher residual compressive stress.

Because the metal medium (steel shot or gold thread shot) impacts the surface of the part at high speed, it will cause the surface to produce plastic deformation. This deformation will extend to the surface layer of the material to generate a compressive stress under the surface layer, thereby offsetting the undesirable tension caused by the part manufacturing. stress.

The residual compressive stress delays the formation of fatigue fracture of the part, thereby prolonging the safe service life of the part.

As far as the gear is concerned, the maximum shear stress occurs at the fillet radius of the tooth root and the gear transition area, and the two tooth surfaces of the gear: the driving surface and the driven surface are both subject to increasing pressure during operation. load.

Therefore, the focus of gear strengthening lies in the strengthening of these parts: the driving surface, the driven surface, and the tooth root.From the perspective of strengthening requirements, it mainly includes two parameters: strength and coverage.

Of course, different gears have different requirements, which must be determined according to their final application environment.

3. Three processes of shot peening

The shot peening process has the following 3 methods: centrifugal force shot peening, compressed air shot peening, and hybrid (nozzle and blasting head), respectively as follows.

1. Compressed air shot peening

Compressed air shot peening must use multiple nozzles to align the specific parts of the tooth surface and tooth root, so that the blast flow is more concentrated, the target is more determined, and the effect of precise strengthening can be achieved.

2. Hybrid (nozzle and throwing head)

The advantage of hybrid shot peening is that it combines the high output of shot peening and the high accuracy and controllability of shot peening on a single device, but the application is relatively small.

3. Centrifugal shot blasting strengthening

In the centrifugal shot blasting process, the steel shot overflows from the hole on the impeller shaft to the blade under the action of centrifugal force, and then is thrown at a fixed angle by the high-speed rotating blade. The area covered by the shot blasting flow per unit time is larger than that of the nozzle spray. However, the application of shot blasting is limited by the small area of ​​the root of the gear to be processed, and multiple blasting heads are required to be fixed at different angles to achieve the required strengthening effect.

In terms of output, in mass production, centrifugal shot blasting is better than the other two methods.

XNUMX. The influence of process parameters on the strengthening effect

For direct pressure shot peening, variables such as nozzle, nozzle size, spray pressure, spray angle (involving nozzle movement, multiple nozzles) will affect the final strengthening effect.

For centrifugal shot blasting, process variables such as the throwing head, the spinning speed, the throwing speed, the throwing angle (involving the location of the throwing head, the movement of the directional sleeve, etc.) will affect the final strengthening effect.

Regardless of the kind of strengthening technology, the goal is to obtain a constant and repeatable strengthening strength. Therefore, it is necessary to understand which key variables in the process will affect the final strengthening result.

Other process parameters that affect the results of shot peening include: the flow rate of the steel shot, the size of the steel shot, and the consistency of the size.

The above description of the method to improve the gear life is for reference only. If you have any unclear points or related business, you can consult EP free of charge.