At 5 a.m., the mining operation site was still immersed in cold fog. Master Li was driving the five-year-old Shantui SD22 bulldozer for stripping operations. When the bucket hit the concrete block embedded in the rock formation for the third time, the hydraulic system suddenly let out a shrill hiss, and the vehicle body trembled violently before stopping askew on the slope. He jumped out of the car to check and found a three-centimeter-long crack near the earring of the bucket cylinder barrel, and hydraulic oil was accumulating into a bright yellow puddle on the frozen ground along the crack. The on-board recorder showed that the heavy rain the previous night had loosened the rock formation. This hidden concrete block was a residue from the blasting three years ago. The instantaneous impact force exceeded the bearing limit of the cylinder barrel. In addition, long-term high-intensity operations in a dusty environment had already fatigued the cylinder barrel material, greatly reducing its strength, and finally, a rupture occurred under this strong impact.
Solution:
KICAN Team's Customized Solution
After receiving the emergency repair request, engineers from the KICAN team arrived at the site with testing equipment in the afternoon of the same day. Ultrasonic flaw detection revealed that there were multiple fine casting defects inside the original cylinder barrel, which was also an important reason for its premature aging. Based on the original parameters of the Shantui SD22 and the actual operating conditions of this equipment, the team worked out a customized plan overnight: using 42CrMo alloy steel to forge the cylinder barrel, which is 30% higher in tensile strength than the original material; adding a 0.05mm chromium plating layer on the inner wall to improve wear resistance and corrosion resistance; in view of the large impact load in the mine, increasing the wall thickness of the cylinder barrel from 12mm to 14mm, and optimizing the radian of the transition fillet of the earring to reduce stress concentration.
In the production process, CNC machining centers were used throughout to ensure dimensional accuracy, and the finished products were put out of the factory only after 24-hour high-pressure testing (with a pressure of 31.5MPa). During installation, technicians used a laser aligner to calibrate the coaxiality of the cylinder barrel and the earring，ensuring that the error did not exceed 0.02mm, completely avoiding the problem of eccentric load.
"After replacing the new cylinder barrel, the bulldozer is like a new one!" Master Li feedback after using it for a week. In the past, when pushing hard soil, I always had to carefully control the throttle for fear of failure again. Now even if I hit the rock block at full speed, the car body only vibrates slightly. The team leader did the math: although the purchase cost of the customized cylinder barrel is 15% higher than that of the original parts, the expected service life can be extended to 1.8 times of the original. In addition, the daily loss of 5,000 yuan due to shutdown caused by faults is reduced, and the price difference can be recovered in half a year.
The data after the equipment has been in operation for one month shows that the oil temperature of the hydraulic system is 4-6℃ lower than before, which means that the new cylinder barrel has smaller fluid resistance; the bucket lifting speed has increased by 8%, and the operation efficiency has been significantly improved. Master Li's most intuitive feeling is: "The joystick has become lighter, and after pushing the same material for a day, my arms don't ache." This Shantui SD22 has now become the main force in mining operations, and the stability brought by the KICAN customized cylinder barrel has advanced the entire construction progress by 10 days.
