Jinan Tianshan Seiko Bearing Co., Ltd. With the rapid development of the machinery industry, the application of slewing bearings is more and more extensive. The yaw bearing is a new type of slewing bearing product newly developed by our company. It requires the finished product to have zero clearance or negative clearance. The rotary damping torque of the bearing is strictly regulated, and the precision of the finished product is very high. According to the requirements of the main machine, the bearing surface must be treated with anti-corrosion treatment. How to solve the above problems is the main subject of research.

First, the anti-corrosion treatment of the outer surface For the anti-corrosion requirements of yaw bearings, we use the arc spray long-term anti-corrosion process. It uses a special arc spraying equipment to melt, atomize and spray the corrosion-resistant metal (pure aluminum or zinc) onto the surface of the workpiece to form a metal arc spray coating layer, and then seal it with a highly permeable corrosion-resistant coating to form an arc spray coating. Anti-corrosion composite coating. Its technical characteristics are: 1 long life of anti-corrosion, up to 20 years; 2 high adhesion of coating; 3 good quality coating. The process route: semi-finished product preparation of the inner and outer rings of the bearing → pre-cleaning → pre-protection of the workpiece → sand blasting → arc spraying → sealing treatment, which are described below.

1. Preparation of semi-finished products for inner and outer rings of bearings

In order to ensure the high appearance quality of the yaw bearing, the anti-corrosion spraying process is arranged after all the machining, and the bearing parts after the spraying are directly put into the warehouse after the assembly is completed, so as to ensure that the anti-corrosion layer is not scratched.

2, pre-cleaning

Degreasing treatment with organic solvents, oil stains may appear on the surface of the semi-finished bearing after machining. In order to ensure the quality of the spray, the cleaning process must be arranged before spraying.

3, workpiece pre-protection

Protection of the workpiece's arc raceways, threaded holes and surfaces that are not to be sprayed by special surface pre-protective tooling prior to blasting and spraying.

4, sandblasting

The surface of the inner and outer rings of the bearing is roughened to increase the contact surface between the coating and the workpiece, so that the surface of the workpiece is more activated and the bonding strength of the coating is improved.

5) Arc spraying

Arc spraying (pure aluminum or zinc) equipment mainly includes DC power supply, spray gun, air compressor and air filter, etc. It mainly controls parameters such as arc voltage, current, wire feeding speed, compressed air pressure and spraying distance.

Closed treatment

Since the coated coating has pores, it must be closed to increase corrosion resistance.

The main exposed surface of the yaw bearing after spraying and assembly has a gear surface, a mounting thread surface and a circular raceway surface. The first two are coated with anti-rust oil after assembly, the latter one is coated with lubricating grease during assembly, the inner packaging of the finished product is closed with a plastic film, and the outer layer is wrapped with a plastic braid to meet the anti-rust requirements.

Second, the damping torque

1. Formation mechanism

There are two sources of damping torque after yaw bearing assembly: one is the frictional resistance of the raceway part, and the other is the frictional resistance of the sealing strip and the sealing surface. The latter is generally constant under the same processing conditions, so the magnitude of the damping torque after yaw bearing assembly depends mainly on the former.

The frictional resistance torque generated by the raceway portion during rotation mainly depends on the size of the bearing clearance. If the gap is large, the resistance is small, and if the gap is small, the resistance is correspondingly increased. The yaw bearing requires zero clearance or negative clearance, and the amount of negative clearance is determined by the friction damping torque after assembly. Therefore, the friction damping torque after assembly basically depends on the assembly clearance value of the yaw bearing, and the formation of this value depends mainly on the size of the finished car before the quenching of the raceway, the quenching of the raceway surface, and the quenching of the raceway. The grinding size and the size of the rolling elements are matched in four steps.

2, process measures

For the above steps, the following methods are used to control the assembly clearance of the bearing.

1. The turning before quenching of the raceway surface adopts CH57207×5/12H high-precision full CNC vertical lathe to perform arc-tracking turning forming. The precision can reach above IT6, and the size, precision and cross-section shape of the raceway surface are guaranteed. .

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