The ripper is hung on the tail of the bulldozer or the grader. The bulldozer or grader can press the ripper of the ripper into the working surface during the process of travel, and carry out the loosening operation, cracking the frozen soil, rock formation or hard. Road surface. The ripper has poor working conditions, and its loose teeth and tooth sleeves are subjected to a large pulling force during the operation.
There is a problem
During the operation of loose soil in a certain type of bulldozer, the ripper gear sleeve is cracked. The cracking part is on the back side of the bottom of the toothed sleeve. After the tooth sleeve is cracked, the maintenance personnel use the welding method to reinforce and still fail to curb the crack propagation. As a result, the ripper is not available.
2. Cause analysis
The bulldozer ripper has a large gap between the loose tooth and the tooth sleeve, so that the loose tooth tooth bar swings in the tooth sleeve, and the swing angle is β. When the ripper is loosened, the rack and the tooth sleeve are in contact with the area 1 and the area 2, respectively. When the ripper is in working condition, its base is far from the contact area 2, according to the principle of moment balance, the load of the area 2 is large, and the area 2 has only 5mm contact surface, which can be regarded as line contact, which has obvious Stress concentration problem.
In order to solve the problem that the region 2 is prone to cracking, we analyze its stress. There are two kinds of stress calculation methods, one is calculated by the Hertz contact formula, and the other is simulated by finite element software. We observe that the crack of the tooth sleeve is long, indicating that the damage of the toothed sleeve is mainly the deep stress. The shape of the crack is not suitable for calculating the contact stress using the Hertz contact formula, and can only be simulated by finite element software.
In the simulation analysis, the ripper is used in the large depth of the working condition, and the stone suddenly hits the operation. For this purpose, the impact coefficient is 2, and the stress distribution of the toothed sleeve is simulated and analyzed under this condition. It can be seen from the analysis results that the local stress near the contact area 2 of the toothed sleeve reaches 1063.7 MPa, which is higher than the upper limit of the strength of the material. The analysis result is consistent with the actual cracking position, indicating that the finite element software simulation analysis basically conforms to the actual working conditions.
