The continuous rainy days for a week turned the water conservancy project site into a quagmire. When Master Wang was driving the Komatsu D65 bulldozer for river dredging, the bucket suddenly had a problem of slow lifting. He tried to increase the throttle to work forcibly, but heard a "click" abnormal sound from the oil cylinder, and then the bucket completely lost power. The shutdown inspection found that the surface of the boom cylinder barrel had irregular depressions, and there was a penetrating crack near the piston rod seal, and hydraulic oil mixed with mud and water gushed out from the crack.
After disassembly, it was found that there were many unfused casting pores in the inner wall of the cylinder barrel. These hidden defects gradually rusted and expanded in the long-term high-humidity environment. In addition, the stones mixed in the sludge continuously hit the outer wall of the cylinder barrel, eventually leading to the failure of the cylinder barrel strength. After checking the equipment files, the site supervisor found that this bulldozer had been working continuously in similar muddy conditions for more than 1200 hours, far exceeding the maintenance cycle recommended by the original factory.
Solution:
KICAN Team's Customized Solution
After receiving the rescue request, the KICAN team rushed to the scene with a portable spectrometer. The test showed that the carbon content of the original cylinder barrel material exceeded 12%, resulting in insufficient toughness, which was a quality defect in the manufacturing process. Combined with the hydraulic system parameters of Komatsu D65 and the muddy working conditions of water conservancy projects, the team formulated a targeted plan: using low-carbon alloy structural steel 20CrMnTi to forge the cylinder barrel, and the surface hardness reaches HRC58-62 through carburizing treatment, while the core maintains good toughness; the inner wall adopts mirror polishing technology (Ra ≤ 0.08 μm) to reduce the flow resistance of hydraulic oil; a polyurethane wear-resistant coating is added to the outer wall of the cylinder barrel, with a thickness of 3mm, which can effectively resist stone impact.
In the production process, vacuum casting technology is used to eliminate internal pores, and the finished product must pass the -40℃ low-temperature impact test and 1 million reciprocating fatigue tests. During installation, the technicians equipped the oil cylinder with a two-stage dust ring to prevent mud and water from invading, and adjusted the layout angle of the hydraulic pipeline to avoid additional bending stress on the cylinder barrel.
User Feedback and Machinery Usage Experience
"This cylinder is simply made for the quagmire!" Master Wang said excitedly after working continuously for three days. In the past, the mud on the surface of the oil cylinder had to be cleaned once an hour, but now the mud and water on the coating will slide off automatically, and only a simple wipe is needed every day. What surprised him even more was that the lifting speed of the bucket was 15% faster than before, and even when working in deep silt, there would be no stuck phenomenon.
Statistics from the project leader show that after the new cylinder barrel is installed, the daily average workload of the bulldozer has increased from 180 cubic meters to 240 cubic meters, and the equipment failure rate has dropped to zero. Although the initial investment of the customized cylinder barrel is 20% higher than that of the standard parts, it saves two maintenance shutdowns per month (each affecting 8 hours of operation). Based on the operation income of 300 yuan per hour, the cost can be recovered in two months.
When the rainstorm came again, Master Wang specially tested the performance of the equipment: pushing soil continuously for two hours in the area with 30 cm of water, the temperature of the hydraulic system was stable at 55℃, far lower than the original 70℃. "I used to have to stop work on rainy days, but now this D65 is like wearing a raincoat, and it's okay no matter how you use it." This bulldozer, which used to break down frequently, has now become the "main force in flood control" of the project department, completing the river dredging task 15 days in advance.
