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Assembly technical requirements

 

1. Basic requirements

 

1.1 It must be assembled in accordance with the design, process requirements and this regulation and related standards.

 

1.2 The assembly environment must be clean. The assembly environment temperature, humidity, dust resistance, lighting and shock resistance of high-precision products must comply with relevant regulations.

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

1.4 The parts must be cleaned and cleaned before assembly. There should be no burrs, flashes, oxide scales, rust, chips, sand, dust and oil, etc., and should meet the corresponding cleanliness requirements.

1.5 The parts shall not be bumped, scratched and corroded during the assembly process.

1.6 Parts with wet paint shall 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. Special measures should be taken when special parts must be operated on the machine. A protective cover should be used to cover the stepped parts. The operator must wear flat shoes to prevent damage to paint films, batteries and non-metallic materials. It is strictly forbidden to step on the lower strength parts.

 

2. Requirements for the connection method

2.1 Screw and bolt connection

2.1.1

When tightening screws, bolts and nuts, it is strictly forbidden to strike or use inappropriate screwdrivers and wrenches. After tightening, the screw grooves, nuts, screws and bolt heads must not be damaged.

2.1.2

Fasteners with specified tightening torque requirements should be tightened with torque wrench according to the specified tightening torque. For bolts with no specified tightening torque, the tightening torque can refer to the provisions in Appendix I.

2.1.3

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

2.1.4

When using double nuts, the thin nuts should be installed first and then the thick nuts should be installed.

2.1.5

After the screws, bolts and nuts are tightened, the screws and bolts should generally expose 1-2 pitches of the nuts.

2.1.6

After screws, bolts and nuts are tightened, their bearing surfaces should be in close contact with the parts being fastened.

 

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 taper pin with the screw tail is installed in the relevant part, the big end should sink into the hole.

2.2.2

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

2.2.3

 

The important tapered pin should be painted and inspected with the hole when assembling, and its 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 even contact, and there should be no gap between the mating surfaces.

2.3.2

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

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 should not be concentrated in one place; the length of the exposed part should be 10% to 15% of the length of the inclined plane.

 

2.4 Riveting

2.4.1

The material and size of riveting must meet the design requirements. The processing of rivet holes shall comply with relevant standards.

2.4.2

During riveting, the surface of the riveted part shall not be damaged, nor shall the surface of the riveted part be deformed.

2.4.3

Unless there are special requirements, there should be no looseness after riveting. The head of the rivet must be in close contact with the riveted part, and it 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, after assembly, about one-half of the cavity should generally be filled with grease that meets the requirements.

2.5.3

When assembling by press-in method, use special pressing tools or pad with rods or sleeves on the interference fit ring, and do not transmit pressure or impact force through the rolling elements and cage.

2.5.4

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

2.5.5

After the bearing outer ring is assembled, the contact between the locating end bearing cap and the washer or outer ring should be uniform.

2.5.6

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

2.5.7

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

2.5.8

For bearings with an eccentric sleeve, 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

The axial clearance of single row tapered roller bearings, thrust angular contact bearings, and two-way thrust ball bearings should comply with the drawings and process requirements during assembly.

2.5.11

 

The outer ring of the bearing should be in good contact with the semi-circular hole of the open bearing seat and the bearing cover. 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; and the bearing cover should be symmetrical to the center line. Uniform contact within 90°. Within the above range, when checking with a 0.03mm feeler gauge, one third of the width of the outer ring shall not be inserted.

2.5.12

 

When assembling radial bearings with adjustable radial clearance 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 an axial clearance.

 

 C=α△tl+0.15

L——Center distance between two axles (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 gap (mm) that should remain after the shaft is thermally expanded.

 

3. Assembly of sprocket chain

3.1 The cooperation between the sprocket and the shaft must meet the design requirements.

3.2 The geometric center planes of the gear teeth of the driving sprocket and the driven sprocket shall coincide, and the offset shall not exceed the design requirements. If the design is not specified, it should generally be less than or equal to two thousandths of the center distance between the two wheels.

3.3 When the chain meshes with the sprocket, the working edge must be tightened and the meshing should be stable.

3.4 The sag of the non-working side of the chain should meet the design requirements. If the design is not specified, it should be adjusted according to 1% to 2% of the center distance of the two sprockets.

 

4. Assembly of belt and pulley

4.1 The position degree of the symmetrical center plane of the pulley groove of the same circuit is: when the center distance is less than 1.2m, it is not greater than 0.3% of the center distance of the pulley; when it is greater than or equal to 1.2m, it is not greater than 0.5% of the center distance of the pulley.

4.2 The tension of each transmission belt should meet the requirements of the Futian "Gushen 2" system inspection card.

 

5. Assembly of hydraulic system

5.1 The piping of the hydraulic system must be derusted and cleaned before assembly, and attention should be paid to dust and rust during assembly and storage.

5.2 All kinds of pipes shall not have dents, wrinkles, flattening, cracks, etc. The bends of the pipes shall be smooth and shall not be twisted.

5.3 The arrangement of pipelines should be neat, and should facilitate adjustment and maintenance of the hydraulic system.

5.4 The hydraulic oil injected into the hydraulic system shall meet the design and process requirements.

5.5 Hydraulic pipelines and components shall not leak oil after assembly. In order to prevent leakage, sealing packing and sealant are allowed to be used during assembly, but should be prevented from entering the system.

5.6 The hydraulic control system and steering system should be flexible and free from sticking.

5.7 After the hydraulic system is installed, the operation test shall be carried out according to the relevant standards.

5.8 Other requirements for hydraulic systems and hydraulic components shall comply with the provisions of GB/T3766.

 

6. Assembly of electrical system

6.1 Electrical components should be tested and inspected before assembly, and those that are not qualified cannot be assembled.

6.2 The numbers and signals displayed by instruments and indicators should be clear and accurate, and the switches work reliably.

6.3 Wiring and connections should be made in strict accordance with the requirements of the electrical assembly drawings.

6.4 The insulation layer of all wires must be intact, the thin copper wire at the stripping end of the wire must be tightened, and tinned if necessary.

6.5 The solder joints must be firm, and there shall be no de-soldering or virtual soldering. Solder joints should be smooth and uniform.

 

7. Balance

7.1 The threshing drum, stepless speed change and pulleys with rotating speed exceeding 400r/min and weight greater than 5kg should be subjected to static balance or dynamic balance test, and the balance accuracy should not be lower than grade G6.3.

 

7.2 The unbalanced mass of the rotating parts can be corrected by the following methods.

7.2.1

Use repair welding, threaded connection, etc. to add mass (counterweight).

7.2.2

Remove mass (deweight) with a drill pin.

7.2.3

Change the number and position of the balance blocks.

7.3 When calibrating by adding mass, it must be fixed firmly to prevent it from loosening or flying out during the working process.

7.4 When calibrating by removing the mass, be careful not to affect the rigidity, strength and appearance of the part.

7.5 For the combined rotary body, after the overall balance, it is not allowed to move or exchange parts arbitrarily.

 

8. Each adjustment mechanism should ensure easy operation, flexible and reliable adjustment.

The adjustment range of each component should be able to reach the specified limit position.

 

9. Each operating mechanism should ensure that the operation is light and flexible, and the tightness is moderate.

All control elements requiring automatic return shall be able to return to their original positions automatically after the control force is removed.

 

10. Final assembly

10.1 During the final assembly, the random accessories should also be tested and the design requirements should be guaranteed.

10.2 The ground clearance of the rigid header should be the same, and the difference is allowed to be no more than 15mm.

10.3 The traveling braking device and the parking braking device shall ensure that the harvester stops reliably.

10.4 The engine should be started smoothly and smoothly, and the flameout should be completely reliable; when the ambient temperature is not lower than -50°C, it should be able to start smoothly.

10.5 All the signs of the whole machine should be pasted to the designated parts according to the design requirements, and should not be skewed or uneven.

10.6 Before leaving the factory, the test machine should ensure that the main engine has a running record of more than 2 hours.