Parts are descaled. On the machined surface of the parts, there should be no defects such as scratches, abrasions, etc. that damage the surface of the parts. The unmarked shape tolerance shall meet the requirements of GB1184-80, and the unmarked length dimension allowable deviation is ±0.5mm. The casting tolerance zone is symmetrical to the basic dimensional configuration of the blank casting. Assembly of rolling bearings is allowed to use oil heating for hot charging, and the temperature of the oil should not exceed 100 °C. Sealing packing or sealant is permitted when assembling hydraulic systems, but should be prevented from entering the system. Parts and components that enter the assembly must have the certificate of the inspection department before they can be assembled. Parts must be cleaned and cleaned before assembly, free from burrs, flash, oxide scale, rust, chips, oil, colorants and dust.
Before assembly, the main fit dimensions of parts and components, especially the interference fit dimensions and related accuracy, should be reviewed. During the assembly process, the parts are not allowed to be knocked, bumped, scratched and rusted. When tightening screws, bolts and nuts, it is strictly forbidden to strike or use unsuitable screwdrivers and wrenches. After tightening, the screw slots, nuts and screws, and the heads of the bolts shall not be damaged. Fasteners with specified tightening torque must be tightened with a torque wrench and tightened according to the specified tightening torque. The excess adhesive that flows out should be removed after bonding. The outer ring of the bearing and the semi-circular hole of the open bearing seat and the bearing cover are not allowed to be stuck; the outer ring of the bearing and the semi-circular hole of the open bearing seat and the bearing cover should be in good contact. It should be in uniform contact with the bearing cap within a range of 90° symmetrical to the center line at 120° of the center line. When checking with a feeler gauge within the above range, a 0.03mm feeler gauge shall not be inserted into 1/3 of the width of the outer ring.
After the bearing outer ring is assembled, it should be in even contact with the end face of the bearing cap at the positioning end. After the rolling bearing is installed, it should be flexible and stable to rotate by hand. The joint surfaces of the upper and lower bearing shells should be closely attached and cannot be checked with a 0.05mm feeler gauge. When fixing the bearing bush with the locating pin, drill the hinge and distribute the pin under the condition that the mouth face and end face of the bush are flush with the opening and closing face and end face of the relevant bearing hole. The pins must not be loosened after being driven in. When the surface of the alloy bearing lining is yellow, it is not allowed to be used, and no nucleation is allowed within the specified contact angle. The nucleation area outside the contact angle shall not be greater than 10% of the total area of the non-contact area. The reference end face of the gear (worm gear) and the shaft shoulder (or the end face of the locating sleeve) should fit together, and the 0.05mm feeler gauge should be used for inspection. And the verticality requirements of the gear reference end face and the axis should be guaranteed.
Strictly check and remove the sharp corners, burrs and foreign objects left in the processing of parts before assembly. Make sure that the seals are not scratched when they are installed. The casting surface is not allowed to have cold space, cracks, shrinkage cavities and penetrating defects and serious incomplete defects. The castings should be cleaned without burrs and flashes, and the pouring risers on the non-processed surface should be cleaned and flush with the surface of the castings. The cast characters and signs on the non-machined surface of the castings shall be clearly identifiable, and the positions and fonts shall meet the requirements of the drawings. Castings should be clear of pouring risers, flying spurs, etc. The residual amount of the pouring riser on the non-machined surface should be leveled and polished to meet the surface quality requirements. The molding sand, core sand and core bone on the casting should be cleaned. The casting has inclined parts, and its dimensional tolerance zone should be symmetrically arranged along the inclined plane.
The right and wrong type and the casting deviation of the boss should be corrected to achieve a smooth transition and ensure the appearance quality. The non-machined surfaces of machine product castings need to be shot peened or roller treated to meet the requirements of cleanliness Sa2 1/2 level.
The surface of the casting should be flat, and the gate, burr, sticky sand, etc. should be cleaned. Castings are not allowed to have casting defects such as cold partitions, cracks, holes, etc. that are detrimental to the use. All steel surfaces that need to be painted must be removed from rust, scale, grease, dust, mud, salt and dirt before painting.