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The application of shot peening in torsion beam 


1. Why torsion beam needs shot peening?

Leaf spring and torsion beam are commonly used shock-absorbing buffers on the vehicle chassis.Compared with leaf spring, torsion beam as tubular buffers can effectively reduce the weight of components, improve the strength, stiffness and fatigue property. However, there are stamping defects in the manufacturing process because the component is a hydroforming component. On the rough road, the deformation area of stamping is subjected to bending stress continuously, and there is stress concentration in stamping v-edge and the stamping transition region of pipe ends, which is the first region of crack fracture. Meanwhile, there is weld stress at the back of the torsion beam, which is also a reason for torsion beam fracture failure.

With the rapid development of domestic automobile industry in recent years, the requirements for lightweight, fatigue life and comfort of automobile components have been improved. Shot peening technology has been gradually introduced into the torsion beam of the middle and high-end automobile chassis. The fatigue life is increased by more than 50%, even up to 200% through shot peening on the failure locations. Shot peening has become the most economic process to improve the fatigue life of torsion beam.


2.Failure locations of torsion beam

Failure locations of torsion beam:

a)Both ends of V-shaped region——Stamping——Bending stress

b) The stamping transition region of pipe ends——Stamping——Bending stress

c) Welding seam——Welding seam——Welding residual stress 

a.jpg                                                   a)                                                               b)                                             c)


3. Commonly used shot peening process for torsion beam

3.1 Shot blasting on the external wall of torsion beam——Both ends of V-shaped region

a)Shot blasting intensity≥0.3mmA

b)Coverage(30x magnifier method):98%

c)Recommend shot: CW32(0.8mm)/HV640 /G3

d)Shot blasting location:Whole external wall


3.2 Shot blasting on the external wall of torsion beam——the stamping transition region of pipe ends

a) Shot blasting intensity near the end≥0.24mmA

    Shot blasting intensity near the inside≥0.14mmA

b) Coverage(30x magnifier method after spliting):98%

c) Recommend shot: CW32(0.8mm)/HV640 /G3

d) Shot blasting location: the stamping transition region of pipe ends


3.3 Shot peening on the welding seam of torsion beam——Welding seam

a) Shot blasting intensity≥0.3mmA

b) Coverage(30x magnifier method): 98% (Cover the region of 10 mm at both ends of the weld seam)

c) Recommend shot: CW32(0.8mm)/HV640 /G3

d) Shot blasting location: the whole weld seam



a.jpg
                              3.1                                                      3.2                                                                             3.3


4. Shot peening/ blasting machine for torsion beam

4.1 Shot blasting on the external wall of torsion beam——Both ends of V-shaped region

Recommended equipment: 2RT500-H32/2/15

                                             2-work position turning table shot blasting machine

a.jpg     

4.2 Shot peening on the welding seam of torsion beam——Welding seam

Recommended equipment: 2RT2P-H32/2/15

                                             4-work position turning table shot blasting machine

a.jpg     

4.3 Shot blasting on the external wall of torsion beam——the stamping transition region of pipe ends

Recommended equipment: 2RT2P-G80II/4/R

                                             4-work position turning table shot peening machin


a.jpg