Repair Technology for Bearing Position Wear of Cold Shearing Machine

Repair Technology for Bearing Position Wear of Cold Shearing Machine

Introduction of Cold Shearing Machine

Cold shearing machine is the main equipment for finishing section in bar production line. Its function is to cut the finished rolled piece to a fixed scale. Its structure (see Figure 1) consists of: cutting edge, crankshaft, pulley, electric motor, brake and clutch. The flywheel is mounted on the main shaft, and the motor drives the flywheel to run through the belt. During the shearing action, the clutch connects the main shaft to the flywheel, so that the reducer drives the eccentric wheel to run, and the shearing frame equipped with cutting edges completes the shearing action downwards.

Reasons for Wear of Cold Shear Shaft

In a bar workshop of an iron and steel enterprise, the cold shearing machine suffers from wear problems. The wear location is the mating surface between pulley and spindle. The diameter of the spindle is 180mm and the wear width is 110mm. The damage location is local deep wear, the maximum wear is about 5mm, and the bearing type is SKF2236EC.

Generally, there are many reasons for wear of shaft type. All kinds of defects during manufacture and bad problems in different stages of assembly, maintenance and use during use may cause wear of bearing position. Apart from these problems, the principal reason is that the metal properties used to fabricate shafts are determined by their high hardness, but poor concessionality (which cannot be restored after deformation), poor impact resistance and poor fatigue resistance, which easily lead to adhesive wear, abrasive wear, fatigue wear, fretting wear, etc. Most of the shaft wear problems are not easy to detect. Only when high temperature, large runout, abnormal noise and other conditions occur, most of the shafts have been worn seriously, resulting in machine shutdown.

Repair Process of Cold Shear Shaft

The traditional method to deal with this kind of bearing position wear problem is to transport the shaft to the machine repair plant after disassembly for repair welding and bushing insertion, etc. However, the process of repair welding machine itself is easy to cause local thermal stress on the shaft surface and cause hidden danger of shaft breakage. Moreover, the process of repair welding machine needs a lot of manpower and time to dismantle, transport and install the equipment. The repair time is long and the comprehensive repair cost is high. The cold shearing machine is shut down by accident and must restore the operation of equipment quickly and effectively. Therefore, traditional repair technology is obviously not suitable for this repair of bearing position wear.

Polymer composites can select different repair processes according to the parameters such as rotational speed of equipment, bearing type and service requirements. After observing the field conditions, it is found that a large area of datum surface still exists. Only partial damaged parts can be filled and repaired by materials. Components of the Fossil Blue process can be used to repair the relationship (see Figure 2), which has the characteristics of short repair time, high repair accuracy, low repair cost, no secondary damage to the equipment and easy operation.

Implementation Process of Site Plan

1. Surface treatment: First, bake the worn position to remove the grease which penetrates into the metal micropore;

2. Grinding: Use sandpaper to grind the worn area and clean it with alcohol or acetone.

3. Harmonizing Material: Harmonizing Fossil Blue Proportionally ® 2211F material and stir evenly until there is no color difference.

4. Coating material: Use 2211F material to fill out the wear position and slightly exceed the wear amount.

5. The inner race of the bearing is assembled directly after being dried with mould release agent, and the bearing can be started up after material curing is completed.

Through years of application experience in industrial field, after unexpected sudden shutdown caused by wear of driving parts in enterprises, the technology can make corresponding repair plans according to the operating conditions and design parameters of different equipment and the forming characteristics of polymer composites. It can solve the problem of wear on the transmission part of equipment in the first time, and meet the operation conditions of most equipment to the maximum extent by using the limited basic conditions in the field, thus greatly improving the repair efficiency and accuracy.

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