Round springs, due to their spiral geometry, are more difficult to strengthen than flat surface leaf springs. In addition, the strengthening effect of the cross section of the round spring must be strictly evaluated to fully understand the fatigue fracture resistance of the round spring. Resistance size.
The round springs are individually sent to the shot blasting room through a continuous conveyor chain system. A set of parallel roller tables are installed in the shot blasting room. While strengthening, the roller tables keep rolling, driving the round springs to rotate while moving forward. The passing method allows the high-speed pill flow to pass between the various rings of the circular spring and hit the metal surface of the inner ring, where the stress of the circular spring is most concentrated.
For applications with high productivity requirements, you can choose a strengthening equipment that can spray two round springs at the same time. The latest research and development result is to combine multiple nozzles on the basis of the original shot blasting equipment to target specific areas of the round spring (Stress concentration to please) More targeted shot peening with concentrated firepower.
Leaf spring strengthening can use a continuous-through shot blasting equipment to strengthen the leaf springs one by one, so that the geometric concave surface of the leaf spring is exposed to the high-speed blast flow. A typical model includes a blasting head for the projection plate On the top of the spring, install a polishing head on the side, and spray the left and right sides of the leaf spring at the same time.
The passing speed of this standard leaf spring strengthening equipment is 10 feet per minute. If a higher production speed is required, the number of throwing heads can be increased and the motor frequency can be adjusted. Under working conditions, the leaf spring will be repeatedly subjected to unidirectional bending stress Therefore, it is sometimes stressed by stress. In the strengthening process, it is simulated that the leaf spring will be subjected to “stress strengthening” in the future use process, so that it will apply a “static stress” in the direction of the load. After the strengthening is completed, the applied static stress is released. Experiments have shown that stress strengthening can further extend the service life of the leaf spring than conventional strengthening.
Suspension springs are strengthened, thanks to the high-stress lightweight design. In recent years, the weight of suspension springs has been greatly reduced. It is very common for the stress of suspension springs of new models to exceed 1000Mpa. The springs have been used under such high stress and have exceeded the limit that the material can withstand. So it must be supplemented by other strengthening methods (such as shot/shot peening).
The main engine manufacturer adopts very strict test standards for automobile suspension springs. The longest test period is as long as 70 days (10 weeks). It should be a suspension spring that works under high stress conditions. Once the surface is subjected to stress corrosion That is, corrosion fatigue failure occurs.If the broken spring port punctures the tire, it may cause major safety and personal accidents.
Shot/shot peening is the most effective strengthening method for suspension springs. After proper shot peening, the fatigue life of high-stress springs can be increased by more than 5 times. At present, most of the suspension springs are shot/shot blasting using steel wire cut blasting, and the process is many times Shot peening (different shot diameters) is commonly used. The spring surface compressive stress strength and depth are important indicators to measure the shot peening effect. A good shot peening surface stress is at least -600Mpa, and the distance 50um from the surface can reach -800Mpa. The surface pressure stress of the pill spring can reach -800Mpa or more, and it can reach -1200Mpa at a distance of 50um from the surface
At present, well-known spring manufacturers at home and abroad generally use a continuous pass-through anti-roll frame strengthening equipment, and the workpiece is conveyed through a suspended conveyor chain. Each part must be in three shot blasting positions, according to the set time Three shot blasting strengthening treatment cycles. After the strengthening is completed, the throwing head stops, the discharge door opens, the strengthened workpieces are automatically lifted out, new workpieces enter, and a new cycle starts. The equipment’s capacity can reach 500 pieces/hour.