As an important force in automated production,
the assembly production process of industrial robots
still requires a large amount of manual labor.
This highlights the importance of assembly work.
Next, let us together
experience the essence of assembly from the assembly process of robots…
1. Basic Requirements
• Assembly must be carried out according to design, process requirements, and relevant standards.
• The assembly environment must be clean. The temperature, humidity, dust prevention, and lighting conditions for assembling high-precision products must meet relevant regulations.
• All components (including purchased and outsourced parts) must have inspection certificates before assembly.
• Parts must be cleaned and washed before assembly, free from burrs, flash, oxidation, rust, chips, sand, dust, and oil, and must meet corresponding cleanliness requirements.
• During assembly, parts must not be bumped, scratched, or corroded.
• Parts with wet paint must not be assembled.
• For parts with relative motion, lubricating oil (grease) should be applied to the contact surfaces during assembly.
• The relative positions of assembled parts must be accurate.
• Generally, stepping on the machine during assembly is not allowed. If special parts must be operated on the machine, special measures should be taken, such as covering the stepped area with protective covers, and operators must wear flat-soled shoes to prevent damage to the paint film. Stepping on battery and non-metal parts with lower strength is strictly prohibited.
2. Requirements for Connection Methods
2.1 Screw and Bolt Connections
• When tightening screws, bolts, and nuts, striking or using inappropriate tools is prohibited. After tightening, the screw slots, nuts, screws, and bolt heads must not be damaged.
• Fasteners with specified tightening torque requirements should be tightened using a torque wrench according to the specified torque. For bolts without specified tightening torque, the torque can refer to the provisions in Appendix 1.
• When fastening the same part with multiple screws or bolts, each screw (bolt) should be tightened in a clockwise, staggered, and symmetrical manner. If there are positioning pins, start with the screw or bolt closest to the positioning pin.
• When using double nuts, the thin nut should be installed first, followed by the thick nut.
• After tightening screws, bolts, and nuts, the screws and bolts should generally protrude 1-2 threads from the nut.
• After tightening screws, bolts, and nuts, the supporting surface should be in contact with the fastened part.
2.2 Pin Connections
• The end face of positioning pins should generally be slightly higher than the surface of the part. After inserting a tapered pin with a screw tail into the relevant part, its large end should be sunk into the hole.
• After inserting a cotter pin into the relevant part, its tail should be separated by 60° to 90°.
• Important tapered pins should be checked for color with the hole during assembly, and the contact length should not be less than 60% of the working length, distributed on both sides of the joint surface.
2.3 Key Connections
• The flat key and fixed key should have uniform contact on both sides of the keyway, and there should be no gaps between the mating surfaces.
• For keys (or splines) with clearance fit, there should be no uneven tightness when the relative moving parts move axially.
• After assembly, the contact area of hook keys and wedge keys should not be less than 70% of the working area, and the non-contact parts should not be concentrated in one place; the exposed length should be 10%-15% of the inclined surface length.
2.4 Riveting
• The materials and specifications for riveting must meet design requirements. The processing of rivet holes should comply with relevant standards.
• During riveting, the surface of the riveted part must not be damaged, nor should it be deformed.
• Unless there are special requirements, there should generally be no looseness after riveting, and the head of the rivet must be in close contact with the riveted part and should be smooth and rounded.
2.5 Assembly of Rolling Bearings
• Bearings must be clean before assembly.
• For grease-lubricated bearings, about half of the cavity should generally be filled with the specified grease after assembly.
• When using the press-fit method for assembly, special pressing tools should be used, or a rod or sleeve should be placed on the interference fit ring. Pressure or impact force must not be transmitted through rolling elements and cages.
• The end face of the inner ring of the bearing should generally be in close contact with the shaft shoulder. For tapered roller bearings and thrust bearings, it should not exceed 0.05mm, and for other bearings, it should not exceed 0.1mm.
• After the outer ring of the bearing is assembled, the contact between the positioning end bearing cover and the washer or outer ring should be uniform.
• When assembling removable bearings, they must be installed according to the inner and outer ring and alignment marks, and must not be installed incorrectly or mixed with other bearings.
• For adjustable head bearings, the numbered end should be facing outward for identification during assembly.
• For bearings with eccentric sleeves, the tightening direction of the eccentric sleeve should be consistent with the rotation direction of the shaft during assembly.
• After the rolling bearings are installed, the rotation of the relative moving parts should be flexible and light, with no jamming phenomenon.
• For single-row tapered roller bearings, thrust angular contact bearings, and bi-directional thrust ball bearings, the axial clearance during assembly should meet the drawing and process requirements.
• The outer ring of the bearing should have good contact with the open bearing seat and the semicircular hole of the bearing cover. When checked with color, it should have uniform contact within a 120° range symmetrical to the centerline with the bearing seat; and uniform contact within a 90° range symmetrical to the centerline with the bearing cover. Within the above range, when checked with a 0.03mm feeler gauge, it should not be able to fit into one-third of the width of the outer ring.
• When assembling radial clearance adjustable thrust bearings on both sides of the shaft, and the axial displacement is limited by end caps, only one end bearing should be in close contact with the end cap, while the other end must leave an axial clearance C=α△tl+0.15 (L: distance between the two shaft centers (mm), α: linear expansion coefficient of the shaft material, △t: difference between the maximum working temperature of the shaft and the ambient temperature (°C), 0.15: the remaining clearance after thermal expansion of the shaft (mm)).
3. Assembly of Sprockets and Chains
• The fit between the sprocket and the shaft must meet design requirements.
• The geometric center plane of the teeth of the driving sprocket and the driven sprocket should coincide, and the offset should not exceed design requirements. If not specified in the design, it should generally be less than or equal to 0.002 times the center distance of the two sprockets.
• When the chain engages with the sprocket, the working edge must be taut, ensuring smooth engagement.
• The sag of the non-working edge of the chain should meet design requirements. If not specified in the design, it should be adjusted to 1%-2% of the center distance of the two sprockets.
4. Assembly of Belts and Pulleys
• The position tolerance of the symmetrical center plane of the pulley grooves in the same loop should be: for center distances less than 1.2m, it should not exceed 0.3% of the pulley center distance; for center distances greater than or equal to 1.2m, it should not exceed 0.5% of the pulley center distance.
• The tension of each drive belt should meet the requirements of the Foton “Gushen 2” system inspection card.
5. Assembly of Hydraulic Systems
• The pipelines of the hydraulic system must be derusted and cleaned before assembly, and care should be taken to prevent dust and rust during assembly and storage.
• Various pipes must not have dents, wrinkles, flattening, or cracks, and the bends in the pipelines should be smooth, with no twisting.
• The arrangement of the pipelines should be neat and facilitate adjustments and maintenance of the hydraulic system.
• The hydraulic oil injected into the hydraulic system should meet design and process requirements.
• After assembly, there should be no oil leakage from the hydraulic pipelines and components. To prevent leakage, sealing materials and sealants may be used during assembly, but care should be taken to prevent them from entering the system.
• The hydraulic control system and steering system should be flexible and free of jamming.
• After the hydraulic system is assembled, it should undergo operational testing according to relevant standards.
• Other requirements for hydraulic systems and components should comply with GB/T3766 regulations.
6. Assembly of Electrical Systems
• Electrical components should be tested and inspected before assembly, and those that do not meet standards should not be assembled.
• The digital displays and signals of instruments and indicators should be clear and accurate, and switches should operate reliably.
• Wiring and connections should strictly follow the requirements of the electrical assembly diagrams.
• The insulation layer of all wires must be intact, and the fine copper wires at the stripped ends must be tightly twisted and tinned if necessary.
• Solder joints must be firm, with no desoldering or cold soldering phenomena. Solder joints should be smooth and uniform.
7. Balancing
7.1 The threshing drum, continuously variable transmission, and pulleys with speeds exceeding 400r/min and weights greater than 5kg should undergo static or dynamic balancing tests, with balancing accuracy not lower than G6.3 level.
7.2 The unbalanced mass of rotating components can be corrected using the following methods:
• Adding mass (counterweight) using methods such as welding or threaded connections.
• Removing mass (weight reduction) using drilling pins.
• Changing the number and position of balancing weights.
7.3 When correcting using the method of adding mass, it must be securely fixed to prevent loosening or flying out during operation.
7.4 When correcting using the method of removing mass, care must be taken not to affect the rigidity, strength, and appearance of the parts.
7.5 For combined rotating bodies, after overall balancing, parts must not be moved or swapped arbitrarily.
8. Adjustment Mechanisms
All adjustment mechanisms should ensure ease of operation, flexibility, and reliability. The adjustment range of each component should reach the specified limit positions.
9. Control Mechanisms
All control mechanisms should ensure ease of operation, flexibility, and appropriate tightness. All control elements that require automatic return should be able to return to their original position automatically after the operating force is removed.
10. Final Assembly
• During final assembly, random accessories should also be trial assembled to ensure they meet design requirements.
• The ground clearance of the rigid cutting platform should be consistent, with a permissible difference of no more than 15mm.
• The walking brake and parking brake devices should ensure reliable stopping of the harvester.
• The engine should start smoothly and steadily, and shut down completely and reliably; it should be able to start smoothly at ambient temperatures not lower than -50°C.
• All machine markings should be affixed to designated positions according to design requirements, without deviation or unevenness.
• The test machine should ensure that the main unit has more than 2 hours of operating records before leaving the factory.
END
Disclaimer: This article is a network reprint or adaptation, and the original author could not be found. Copyright belongs to the original author. If there are any copyright issues, please contact for deletion.
My Mechanical Network: www.mejxw.com
Free sharing of various mechanical design resources
Welcome everyone to join
