Bushing bearing is a cylindrical mechanical part sleeved on a rotating shaft and is an integral part of a sliding bearing. Generally speaking, the Bushing bearing and the bearing seat adopt an interference fit, while the Bushing bearing adopts a clearance fit.

Concept

Bushing bearing is on the propeller shaft or stern shaft. The bearing is a component that fixes and reduces the load friction coefficient during the mechanical transmission process.

The sleeve and bearing are the same in that both bear the load of the shaft.

The difference between the two is that the Bushing bearing is an integral structure, and the relative movement between the shaft and the Bushing bearing is relative when rotating; while the bearing is split, the relative movement of the inner and outer rings of the bearing is relative when rotating. But in essence, the sleeve is actually a type of sliding bearing.

The bearing bush is equivalent to the outer ring of a sliding bearing. The bushing is integral and moves relative to the shaft, while the bearing bush is divided into pieces and the relative shaft is rotated.

In the LEGO Mindstorms series and BioTrans RoSys series robot components, the sleeve refers to the silver-grey LEGO standard shaft holder, which is divided into two types: full sleeve and 1/2 sleeve.

2. Maintenance

Common causes of failure

During long-term operation of the Bushing bearing, the surface of the shaft journal is subject to the pressing force of the expansion sleeve and the compound mechanical force, which will cause its permanent deformation and the diameter may be reduced by 0.1mm ~ 0.3mm. As a result, the mechanical expansion and contraction force can’t reach the required contraction force, and there is a fitting gap between the Bushing bearing and the main shaft, which causes the wear of the Bushing bearing.

Latest fix

Due to the greater value of parts, traditional repair methods are more expensive. With the development of advanced technologies such as foreign polymer composites, some repair methods that are fast and low in cost are favored. This method has also been introduced in China. The more mature materials are Fu Shilan 2211F. The material has comprehensive mechanical properties, excellent adhesion and temperature and corrosion resistance unmatched by traditional methods. The maximum compressive strength can reach 1200kg / cm2. The adhesion (overlapping shear test) is 225 on a smooth steel surface. kg / cm2. Therefore, it can be used to repair the wear of large Bushing bearings. And the equipment does not need to be dismantled in a large area, which saves a lot of manpower and material resources for the enterprise.

3. brass bushing bearing process analysis

Part technology analysis

(1) Part material: 45# steel. Good machinability.

(2) Component surface: outer surface (Φ50, 35, 33), inner surface (Φ31.5, 20.5), hole, end surface, inner and outer step surface, inner and outer retraction sipe, inner and outer Chamfer.

(3) Analysis of main surface: Φ20.5 inner hole is not only the supporting surface for supporting other parts, but also the main reference plane of this part; Φ50 outer circle and its stepped surface are also used to support other parts.

(4) Main technical conditions: The coaxiality of the outer circle of Φ50 and the inner hole of Φ20.5 is controlled in the range of 0.03mm; the perpendicularity of the step surface and the inner hole of Φ20.5 is controlled in the dimensional tolerance of the inner hole of Φ44 in mm; Roughness Ra0.8μm; heat treatment hardness HRC50 ～ 55.

Part manufacturing process design

(1) Blank selection: According to the material of the part is 45 steel, the production type is medium batch production, the diameter of the part has a large difference, the part has a thin wall, low rigidity and easy deformation, and the processing precision is high. The part needs to be quenched. In terms of factors, choose between bar stock and die forging: die forging.

(2) Benchmark analysis: The main positioning benchmark should be Φ20.5 inner hole center

(3) Installation scheme: when processing the big end and the inner hole, the three-jaw chuck can be directly used for clamping; the rough end can be used with the large end of the reverse jaw clamp, and the semi-finish and finishing small end should be equipped with a mandrel. , Axial clamping workpiece with Φ20.5 hole positioning. When processing the hole, you can use the indexing head to install, lift the spindle by 90º, and use the direct indexing method to ensure the 3 × Φ6 even position on the circumference of the part. For the four screw vias on the big end, a special fixture is used for installation: the large end face and the Φ20.5 hole are used as the main positioning reference, the hole is prevented from turning, and the workpiece is clamped axially.

(4) Part surface processing method: Φ20.5 inner hole, precision grinding is used to achieve the accuracy and roughness requirements; the outer circle and its step surface are processed by grinding; the remaining turning surfaces are processed by semi-finishing to meet the processing requirements; Mill on.

(5) Heat treatment arrangement: Because the surface of the die forging has crust, it will accelerate tool wear and passivation. In order to improve the cutting processability, the blank is annealed after the forging to soften the crust; the final treatment of the part is quenching. The wall thickness of the parts is small and easily deformed. In addition, the high precision of the part processing is required. In order to control the quenching deformation as much as possible, the quenching and tempering treatment is arranged after the rough machining for pretreatment.

4. Sleeve Inspection Details

1. Appearance quality The surface of the sample should be free of air bubbles, burrs, and deformation, with uniform material and no irritating odor.

2.Size

(1) The relevant dimensions tested with vernier calipers shall comply with the relevant technical and drawing requirements.

(2) After the Bushing bearing and the rotating shaft are matched, the rotor is vertically downward, and the bronze bushing bearing will not slide freely under the action of its own weight.

3. Heat and aging resistance test

(1) After the sample is subjected to a ball pressure test at 125 ° C / 1h, the indentation shall be ≤ 2mm, and no deformation shall be observed visually.

(2) After putting the sample in the oven at 120 ° C / 96 hours, visually inspect the Bushing bearing for no embrittlement or deformation.

4, fire resistance test

The flame retardant grade is VW-1. If it is burned with alcohol lamp for 15S, it should be extinguished within 15S.

5.Packing and marking

(1) The packaging shall be firm, reliable and safe to ensure that the product is not damaged during transportation.

(2) The supplier code and name, product name, product quantity, material code, quality inspection mark, production date, etc. should be indicated on the package. The marks should be clear and accurate, and there should be no mixing.

(3) In order to increase the traceability of the product, it is required to mark the production batch number in a prominent place on the outer packaging. The delivery lot number shall be indicated on the original certificate of the inspection certificate or inspection (experiment) of the product.

6. Content of harmful substances (RoHS directive)

If used for RoHS directive models, the materials should meet RoHS directive requirements.