Repair of four-column hydraulic press

⒈Equipment failure

The four-column hydraulic press is mainly used for the processes of pressing, pressing and correcting plastic materials. The equipment operates continuously for 12 hours in two shifts. The fault is that the slider of the hydraulic press cannot move up and down with the piston of the master cylinder.

⒉Cause of issue

The lower part of the piston rod of the master cylinder is broken.

The installation position of the mold is not correct, which violates the equipment safety operation regulations, and is used for profiling exceeding the maximum eccentricity. The four-column sliding sleeve has been worn for many years, causing the gap to increase, and the piston rod is stressed in the horizontal direction when an eccentric load, and the piston rod and the slider are rigidly connected. The structure design of the piston rod head is a bit unreasonable. The diameter difference between the two sections is large. The piston rod and the lower end of the slider are connected by threads, while the connection between the piston rod and the slider of other manufacturers is a split snap ring at the lower end.

Flanges and bolts fasten the piston rod and the upper-end surface of the slider into one body. The equipment is old and aging, maintenance is not timely, and fatigue use.

⒊Repair plan

A section of rod connector is inserted at the disconnection of the master cylinder piston rod. One end of the rod connector is made into a disc with the same diameter as the piston rod, and a uniformly distributed bolt counterbore is made to connect to the master cylinder piston rod with several high-strength hexagon socket bolts. The bearing boss at the end corresponds to the repair point of the piston rod head, and the other end is still made of the same shaft section with the slider hole and the screw section of the fastening double nut as the broken rod section.

During the pressing process of the four-column hydraulic press, the rod takes over the connecting bolts, and the tension on the bolts caused by the weight of the slider and the die and the frictional resistance is relatively small during the return stroke. The stroke of the main cylinder of the hydraulic press has not changed, and the piston rod has been extended by 100mm due to the rod connection, which reduces the opening height of the hydraulic press, but does not affect the use of the mold.

⒋Repair process and effect

⑴Repair process

Remove the piston of the main cylinder of the four-column hydraulic press, flatten the fracture of the piston rod of the main cylinder, and machine a stop that matches the rod connector, and then process evenly distributed M30 threaded holes. Make a pole takeover according to Figure 2. Use M30 high-strength hexagon socket bolts to fasten the rod connector and the piston rod together. Lift the main cylinder and the upper crossbeam vertically and put them on the four columns. Screw the upper and lower column lock nuts on the column. The lower lock nuts should be fully tightened, and the upper lock nuts should leave a little gap for adjustment accuracy. When used. Install and refuel the liquid-filled barrel to make the master cylinder move several times in its full stroke to remove the air in the cylinder and pipeline. After the main cylinder piston descends to contact with the upper plane of the slider, it is fixed with a double nut (Figure 3). After the sliding block and the piston of the master cylinder are tightly connected, adjust according to the specified accuracy, and tighten the column lock nut as much as possible. Carry out a load test. Set up a warning sign on the eye-catching position on the side of the slider, stating "Do not exceed the maximum eccentricity, and it is strictly prohibited to exceed the maximum stroke of the slider."

⑵Repair effect

After the repair, the opening height of the hydraulic press is reduced from 1200mm to 1100mm, but it can still meet the requirements of process equipment. This repair method is simple and easy to implement, and it takes less than a week to solve urgent production needs. There was no abnormality in production and use, and no problems were found in the regular inspection of the equipment.