1. Basic requirements

1.1 Assembly must be carried out in accordance with the design, process requirements, these regulations and relevant standards.

1.2 The assembly environment must be clean. The assembly environment temperature, humidity, dustproof amount, lighting and shockproof of high-precision products must comply with relevant regulations.

1.3 All parts (including outsourced and outsourced parts) must have inspection certificates before they can be assembled.

1.4 Parts must be cleaned and cleaned before assembly. There must be no burrs, flash, scale, rust, chips, sand, dust, oil, etc., and should meet the corresponding cleanliness requirements.

1.5 Parts must not be bumped, scratched or rusted during assembly.

1.6 Parts with wet paint must not be assembled.

1.7 For relatively moving parts, lubricating oil (grease) should be added between the contact surfaces during assembly.

1.8 The relative position of each component should be accurate after assembly.

1.9 In principle, it is not allowed to step on the machine during assembly. When special parts must be operated on the machine, special measures should be taken. A protective cover should be used to cover the stepped parts. The operator must wear flat shoes to prevent damage to the paint film, battery and non-metallic, etc. It is strictly forbidden to step on the lower strength parts.

2. Requirements for connection methods

2.1 Screw and bolt connection

2.1.1. When tightening screws, bolts and nuts, it is strictly prohibited to hit or use inappropriate screwdrivers and wrenches. The screw slots, nuts, screws and bolt heads must not be damaged after tightening.

2.1.2. Fasteners with specified tightening torque requirements should be tightened with a torque wrench according to the specified tightening torque.

2.1.3. When the same part is fastened with multiple screws or bolts, each screw (bolt) must be tightened clockwise, staggered, and symmetrically. If there is a positioning pin, start from the screw or bolt close to the positioning pin.

2.1.4. When using double nuts, install the thin nut first and then the thick nut.

2.1.5. After tightening the screws, bolts and nuts, the screws and bolts should generally expose 1 to 2 pitches of the nut.

2.1.6. After screws, bolts and nuts are tightened, their supporting surfaces should fit closely with the fastened parts.

2.2 Pin connection

2.2.1. The end face of the positioning pin should generally be slightly higher than the surface of the part. After the tapered pin with a screw tail is installed into the relevant part, its big end should sink into the hole.

2.2.2. After the cotter pin is installed into the relevant parts, its tail should be separated by 60°~90°.

2.2.3. When assembling important conical pins, they should be color-checked with the holes. Their contact length should not be less than 60% of the working length, and should be distributed on both sides of the joint surface.

2.3 Key connection

2.3.1. The two sides of the keyway of the flat key and the fixed key should be in uniform contact, and there should be no gap between their mating surfaces.

2.3.2. After the clearance fit key (or spline) is assembled, there must be no uneven tightness when the relatively moving parts move along the axial direction.

2.2.3. After the hook key and wedge key are assembled, the contact area should not be less than 70% of the working area, and the non-contact parts must not be concentrated in one place; the length of the exposed part should be 10% to 15% of the length of the slope.

2.4 Riveting

2.4.1. The materials and specifications of riveting must meet the design requirements. The processing of rivet holes should comply with relevant standards.

2.4.2. During riveting, the surface of the riveted parts must not be damaged or deformed.

2.4.3. Unless there are special requirements, generally no loosening should occur after riveting. The head of the rivet must be in close contact with the riveted part and should be smooth and round.

2.5 Assembly of rolling bearings

2.5.1. Bearings must be clean before assembly.

2.5.2. For grease-lubricated bearings, approximately one-half of the cavity should generally be filled with grease that meets the regulations after assembly.

2.5.3. When assembling by the press-in method, special presses should be used or rods or sleeves should be placed on the interference fit rings. Pressure or impact force should not be transmitted through the rolling elements and cages.

2.5.4. The end face of the inner ring of the bearing should generally be close to the shaft shoulder. It should not be larger than 0.05mm for tapered roller bearings and radial thrust bearings, and should not be larger than 0.1mm for other bearings.

2.5.5. After the bearing outer ring is assembled, the contact between the positioning end bearing cap and the washer or outer ring should be even.

2.5.6. When assembling a detachable bearing, it must be installed according to the inner and outer rings and alignment marks. It must not be installed upside down or mixed with the inner and outer rings of other bearings.

2.5.7. Bearings with adjustable heads should be assembled with the numbered end facing outward for easy identification.

2.5.8. For bearings with eccentric sleeves, the tightening direction of the eccentric sleeve should be consistent with the rotation direction of the shaft during assembly.

2.5.9. After the rolling bearing is installed, the rotation of the relative moving parts should be flexible and light, and there should be no jamming.

2.5.10. When assembling single-row tapered roller bearings, thrust angular contact bearings and two-way thrust ball bearings, the axial clearance should comply with the drawings and process requirements.

2.5.11. The outer ring of the bearing should be in good contact with the open bearing seat and the semicircular hole of the bearing cap. When inspected by the coloring method, it should be in uniform contact with the bearing seat within a range of 120° symmetrical to the center line; Symmetrical contact within 90° of the center line. Within the above range, when checking with a 0.03mm feeler gauge, one-third of the width of the outer ring must not be inserted.

2.5.12. When radial bearings with adjustable radial clearance are installed on both sides of the shaft, and the axial displacement is limited by the end caps at both ends, only one end of the bearing must be close to the end cap, and the other end must have axial clearance. gap

  C=α△tL+0.15

L——center distance between two axes (mm);

α——The material linear expansion coefficient of the shaft;

△t——The difference between the maximum working temperature of the shaft and the ambient temperature (℃);

0.15——The remaining gap (mm) after the thermal expansion of the shaft.