Assembly technology has the characteristics of automation, digitization, and integration. It is a key technology. The editor found German assembly technology to let gold fans experience the essence of the technology!
Assembly technical requirements
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 part to be riveted 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 centerline will be uniform. 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.
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 should coincide, and their offset should not exceed the design requirements. If not specified in the design, 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 side must be tightened to ensure smooth meshing.
3.4. The sag of the non-working side of the chain should meet the design requirements. If the design does not specify it, it should be adjusted by 1% to 2% of the center distance between the two sprockets.
4. Assembly of belts and pulleys
4.1. The position of the symmetrical center plane of the pulley grooves in the same circuit is: when the center distance is less than 1.2m, it is not greater than 0.3% of the pulley center distance; when it is greater than or equal to 1.2m, it is not greater than 0.5% of the pulley center distance.
4.2. The tension of each transmission belt should meet the requirements of the Foton "Gushen 2" system inspection card.
5. Assembly of hydraulic system
5.1. The pipelines of the hydraulic system must be derusted and cleaned before assembly. Pay attention to dust and rust prevention during assembly and storage.
5.2. Various 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 pipelines must be arranged neatly and facilitate the adjustment and maintenance of the hydraulic system.
5.4. The hydraulic oil injected into the hydraulic system should meet the design and process requirements.
5.5. Hydraulic pipelines and components must not leak oil after assembly. In order to prevent leakage, sealing fillers and sealants are allowed to be used during assembly, but they should be prevented from entering the system.
5.6. The hydraulic control system and steering system should be flexible and free of stagnation.
5.7. After the hydraulic system is installed, the operation test should be carried out in accordance with relevant standards.
5.8. Other requirements related to hydraulic systems and hydraulic components should comply with the provisions of GB/T3766.
6. Assembly of electrical system
6.1. Electrical components should be tested and inspected before assembly. Those that fail to meet the standards cannot be assembled.
6.2. The numbers and signals displayed by instruments and indicators should be clear and accurate, and the switches should work reliably.
6.3. Wiring and connections should be carried out strictly in accordance with the requirements of the electrical assembly drawing.
6.4. The insulation layer of all wires must be intact, and 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 must be no desoldering or weak soldering. Solder joints should be smooth and even.
7. Balance
7.1. The threshing drum, continuously variable speed and pulleys with a speed exceeding 400r/min and a weight greater than 5kg should be subjected to static balance or dynamic balance tests, and the balance accuracy should not be lower than G6.3 level.
7.2. The following methods can be used to correct the unbalanced mass of rotating parts.
7.2.1. Use repair welding, threaded connection, etc. to add mass (counterweight).
7.2.2. Use drill pins to remove mass (deduplication).
7.2.3. Change the number and position of the balance weights.
7.3. When calibrating by adding mass, it must be fixed firmly to prevent it from loosening or flying out during the work.
7.4 When correcting by removing mass, be careful not to affect the stiffness, strength and appearance of the part.
7.5 For the combined rotary body, after the overall balance, parts are not allowed to be moved or replaced at will.
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 control mechanism should ensure light and flexible operation and appropriate tightness.
All control parts that require automatic return should be able to automatically return to their original position after the control force is removed.
10. Final assembly
10.1 During final assembly, the random accessories should also be trial-assembled and the design requirements should be ensured.
10.2 The ground clearance of the rigid header should be consistent, and the difference is allowed to be no more than 15mm.
10.3 The traveling brake device and parking brake device should ensure reliable parking of the harvester.
10.4 The engine should start smoothly and smoothly, and stall completely and reliably; it should be able to start smoothly when the ambient temperature is not lower than -50°C.
10.5 All machine signs should be pasted to designated locations according to design requirements and must not be deflected or uneven.
10.6 Before leaving the factory, the test machine should ensure that the main machine has an operation record of more than 2 hours.
