Pain Points & Technical Challenges
Before tightening an engine main-bearing cap, the cap must be seated on the cylinder-block locating pins with a preload of 1,500 ?50 N. Seal friction and stick-slip in a conventional hydraulic preload cylinder cause actual force fluctuations of ?200 N. This introduces additional torque variation during tightening and raises the risk of main-bearing bore roundness being out of tolerance to 4.6%.
When press-fitting side plates on new-energy battery modules, adhesive thickness must be controlled between 0.15 and 0.25 mm. Because of hydraulic-fluid compressibility, a hydraulic system cannot maintain a rigid final position. Rebound during a 10-second hold can open the adhesive layer to 0.35 mm, exceeding the specified thermal-adhesive gap.
Yiruiju Customized Technical Solutions
A dual-servo-electric-cylinder master/slave system is used. The master cylinder performs closed-loop force control for preload, while the slave follows position to keep both sides synchronized. High-speed cross-coupling control holds force deviation between the two sides within ?30 N and synchronization error below 0.02 mm. Main-bearing bore roundness yield after tightening improves from 95.4% to 99.7%.
At the end of pressing, Position Hold with Active Damping is enabled. The servo drive instantaneously raises velocity-loop bandwidth to 150 Hz and applies reverse torque to cancel elastic rebound. A 0.5 ?m-resolution linear scale provides micron-level creep compensation, limiting adhesive-thickness drift to no more than 0.005 mm during a 10-second hold.
Error-proofing interlocks exchange cylinder position, force, and robot-grip signals over Profinet IRT. Cycle time remains stable at 12 seconds per part?22% faster than the hydraulic solution?while eliminating hydraulic-oil contamination of high-voltage connector busbars.