At the roadbed construction site of the expressway expansion project, Master Chen was driving the XCMG TY160 bulldozer to level the roadbed earthwork. Under the scorching sun in the afternoon, the bulldozer suddenly had a bucket dropping phenomenon - the just-pushed earthwork slipped along the edge of the bucket before being transported to the designated area. He operated the control lever repeatedly and found that the lifting speed of the bucket was sometimes fast and sometimes slow, and the pointer of the hydraulic system pressure gauge jumped violently.
After an emergency shutdown, the construction site maintenance team used a portable detector to check and found that the fit clearance between the tilt cylinder barrel and the piston had reached 0.25mm (standard value ≤ 0.1mm). After disassembly, longitudinal scratches were visible on the inner wall of the cylinder barrel, and there was a 0.8mm wide crack near the top. Checking the equipment log, it can be seen that this bulldozer has been working continuously in clay containing gravel, advancing the roadbed by 150 meters per day on average. Moreover, after the heavy rain last week, the water on the construction site was not drained, and the oil cylinder has been working in a semi-submerged state for a long time, and pitting corrosion has appeared on the outer wall of the cylinder barrel. What's more, the original parts warehouse is 800 kilometers away from the construction site, and it will take at least 5 days to arrive. However, the subgrade project is at the acceptance node, and the delay will face liquidated damages.
Solution:
KICAN Team's Online Customized Solution
After receiving the online help from the construction site project department, the KICAN team launched the "drawing + data" dual-drive scheme design process. Through encrypted transmission, the 3D model of the oil cylinder of XCMG TY160, the flow parameters of the hydraulic system, as well as the 3D scan of the cylinder barrel crack and the operation load data of the past month provided by the construction site were obtained.
The technical team used finite element analysis software to simulate the stress state of the cylinder barrel under clay extrusion, gravel impact and water erosion environment, and formulated a targeted plan: using 40CrNiMoA alloy structural steel with excellent corrosion resistance, after quenching and tempering, the hardness reaches HB260-290, which is 40% higher than the original material in corrosion resistance; the inner wall adopts nano-ceramic coating technology with a thickness of 50μm, and the friction coefficient drops to 0.08, which is much lower than 0.15 of the chrome plating layer; in order to cope with the impact load of subgrade operation, the yield strength of the cylinder barrel is increased from 800MPa to 950MPa, and an annular reinforcing rib is added at the top where cracks are prone to occur.
The plan communicated with the construction site in real-time through the cloud collaboration platform, and the engineers answered 6 questions online about coating wear resistance and installation tolerance. The flexible production line was used in the production link, and key processes such as deep hole boring and coating spraying were live-streamed through 5G. After the finished cylinder barrel was inspected by the coordinate measuring instrument, it was delivered to the construction site within 48 hours by means of cold chain logistics + special vehicle escort.
"It's unexpected that it can be so reliable without engineers being present!" The project manager of the construction site sighed when accepting the new cylinder barrel. The maintenance personnel completed the replacement in only 2 hours according to the AR installation guide provided by KICAN, which was half the time specified in the original manual. After starting the equipment, the pressure fluctuation of the hydraulic system was controlled within ±2%, and the response speed of the bucket action was increased by 12%.
The data after 10 days of continuous operation showed that the operating temperature of the oil cylinder was stable at 48℃, 10℃ lower than before; the wear amount of the nano-ceramic coating was only 0.003mm, far lower than the expected value. Master Chen's most intuitive feeling is: "I used to have to rev the throttle hard to push hard soil, but now I can drive the bucket by pushing the joystick lightly, saving nearly 20 liters of oil a day."
In terms of project progress, the timely arrival of the customized cylinder barrel allowed the subgrade project to be accepted as scheduled, avoiding liquidated damages of 50,000 yuan per day. Cost accounting shows that the comprehensive cost of the online customization plan is 18% lower than that of the original parts, and the design life of the new cylinder barrel is 8,000 hours, which is 1.5 times that of the original parts. The project department has signed a long-term cooperation agreement with KICAN to promote the online customization model to the maintenance of other equipment.
