Double Girder Overhead (EOT) Crane Manufacturing Process: Højpræcision og avancerede teknikker

This article will introduce the double girder eot crane manufacturing process of Henan Kuangshan Crane in detail. The dobbeltdrager traverskran is widely used in various indoor and outdoor industrial and mining enterprises, including steel and chemical industries, railway transportation, ports, terminals, and logistics centers. The quality of bridge crane manufacturing process directly determines its performance and effectiveness in actual use, and even affects its safety.

This article simplifies the double girder eot crane manufacturing process into five parts:

• Manufacturing of the main girder.
• Manufacturing of the end beams.
• Assembly of the bridge structure: including the assembly of the main girder and end beams, installation of the tracks, assembly of the walkways and railings, installation of the traveling mechanism, and installation of wiring conduits, among others.
• Manufacturing and assembly of the trolley: including the fabrication of the trolley frame and the assembly of the trolley’s traveling and hoisting mechanisms.
• Electrical assembly in eot crane manufacturing process.

Manufacturing of the Main Girder

The main girder of the overhead crane is a box-type beam structure, as shown in the diagram below. It consists of upper and lower cover plates, web plates, large and small stiffening plates, and process-reinforced angle steel, forming a symmetrical box beam structure. The general process includes material preparation, assembly welding, and correction.

Preparation before Manufacturing

• Design the drawings according to the requirements of the contract and technical agreement, providing the production, procurement, and quality inspection departments with construction drawings and lists of materials and configurations, including technical requirements.
• Deliver materials to the construction site according to specifications, material grades, and quantities. The incoming materials must undergo acceptance and quality inspection (including necessary physical and chemical tests to determine chemical composition).

Steel Treatment

For the main girder of the double girder eot crane, custom steel coils are uncoiled using an uncoiling machine, flattened with a leveling machine, and then shot-blasted to remove rust. Steel plate pretreatment equipment can be used to remove rust and apply paint to the steel beforehand, or the rust removal can be done after the main girder is completed using a shot-blasting machine.

The leveling machine at Henan Kuangshan Crane utilizes a multi-roller working principle, where the sheet material undergoes repeated deformation between the upper and lower leveling rollers to eliminate stress and achieve leveling. By using this machine for leveling, the flatness of the sheet material is significantly improved, thereby enhancing the quality of the workpiece.

Our company’s shot blasting machine is a roller conveyor type, which includes procedures such as loading, shot blasting, painting, and drying. This shot stream is projected onto the surface of the steel, providing a three-dimensional, all-around cleaning process. This quickly removes rust, welding slag, oxide scale, and other contaminants from the steel surface, resulting in a clean surface with a certain level of roughness. This process enhances the adhesion of the paint to the steel surface, improves the steel’s fatigue strength and corrosion resistance, improves the inherent quality of the steel, and extends its service life.

Material Preparation and Cutting of Web Plate, Upper and Lower Cover Plates, and Stiffening Plates

• The web plate is cut using a CNC plasma cutting machine, ensuring the camber, length, and height of the web plate. After the material cools, the camber of the cut plate is checked and recorded (with at least five points measured on each piece). The plates are then paired, marked, and passed on to the next process.
• The upper and lower cover plates are cut using either a CNC plasma cutting machine or a semi-automatic cutting machine. The cover plates should be matched with the corresponding web plate, ensuring that the seams of the cover plates and the web plate are staggered by no less than 200mm. Appropriate markings are made, and after quality approval, they are passed on to the next process.
• The dimensions of the stiffening plates must meet the required specifications.

Compared to flame cutting and other metal fabrication processes, plasma CNC cutting machines offer higher cutting quality. The edges of the cut metal are free from slag residue, and the heat-affected zone is smaller. Plasma cutting is significantly faster than laser cutting and flame cutting, which greatly improves production efficiency.

Assembly and Welding of Box-Type Beam

• The upper cover plate is welded to the large and small stiffening plates, ensuring that the stiffening plates are perpendicular to the cover plate.
• Welding of the web plate with the upper cover plate and stiffening plate. When tack-welding the two web plates, welding should start from the center and proceed simultaneously towards both ends on both sides.
• Before assembling the lower cover plate, ensure that the main girder is not twisted. If it is, it must be corrected at this stage.
• Welding and repairing the ends of the main girder. Any gaps exceeding tolerance should be closed tightly. If they cannot be closed tightly, manual welding should be used to fill the gaps. Additionally, any wave-like deformations on the surface of the main girder should be corrected.
• Welding the four main seams of the main girder. Place both ends of the main girder on the welding platform and use an automatic gantry submerged arc welding machine to weld from both sides simultaneously.

The robotic fully automatic welding workstation for the internal seams of the double girder overhead crane’s main girder enables the automatic welding of two long seams. After the material is manually loaded and roughly aligned horizontally and vertically, the L-arm hydraulic flipping machine rotates the workpiece by ±90°, allowing the robot to automatically locate and weld the seams. This significantly improves the quality of the welds and enhances the efficiency of welding the crane’s structural components, particularly in the welding of internal seams.

The multi-head design of the fully automatic gantry submerged arc welding machine allows for the simultaneous welding of multiple seams, greatly improving work efficiency and saving time and labor costs. The weld quality is high, with strong and well-sealed seams.

Repair and Inspection of the Main Beam

Place the two main beams of the same crane on the inspection platform to check the camber, waviness, local plate warping, and height differences. If any of these do not meet the required standards, corrections can be made using flame straightening or weight pressing methods.

Manufacturing of the End Beams

The end beam consists of a symmetrical box beam structure made up of upper and lower cover plates, web plates, reinforcing plates, diaphragms, bent plates, tie plates, and footplates. The middle joint is connected to form the entire end beam using angle steel and steel plates fastened with bolts.

The general process includes material preparation, assembly and welding of the end beam, and inspection.

Material Preparation

• The web plate is cut using a CNC plasma cutting machine.
• Preparation of reinforcing plates.
• Diaphragms are cut using a shearing machine.
• Bent plates are cut using a semi-automatic cutting machine or CNC flame cutting machine.
• Preparation of cover plates.
• Preparation of middle joint connecting parts.
• Preparation and cutting of other components.

End Beam Assembly and Welding

• Assembly of the π-shaped beam.
• Assembly of the bent plates.
• Welding the internal structure of the end beam, including diaphragms, reinforcing plates, and connecting angle steel.
• Assembly of the lower cover plate.
• Welding of the longitudinal seams of the end beam.
• Drilling and reaming of joint holes.
• Assembly of the joint bolts.

Henan Kuangshan Crane’s new robotic welding workstation for end beams offers high precision, ensuring that the position, shape, depth, and width of each weld are consistent. This eliminates errors and inconsistencies that can occur with manual operations. The automated welding technology significantly increases welding speed and efficiency, enhances workplace safety, saves materials and energy, and allows for more precise control of the welding process, reducing material waste.

End Beam Inspection

After the team completes its self-inspection, the end beam is handed over to the quality inspection department for further examination.

Assembly of the Crane Bridge Structure

• Assembly of the main girder and end beams: After assembling the main girder and end beams and confirming that the dimensions of both main girders meet the technical requirements, remove the excess material from the web plate. Lift the end beams and assemble them with the main girders. Once the dimensions are properly adjusted, fix the end beams to the main girders. Tack weld the connection points between the end beams and main girders, starting with the upper cover plate, followed by the weld between the main girder web plate and the end beam connection plate, and finally the lower cover plate.
• Track assembly: Before assembling the tracks, recheck the camber values.
• Assembly and welding of the walkway and tread plate
• Correction and final inspection: The bridge structure should undergo a self-inspection according to technical requirements. If any discrepancies are found, corrections and repairs should be made. Once approved, submit the structure for a special inspection by the quality control department.
• Assembly of the wheel sets
• Assembly of the crane drive mechanism
• Installation of the transmission side railing
• Installation of the trolley cable trough
• Installation of the operator’s cabin suspension channel steel
• Installation of cable and wire conduits
  Installation of protective covers: Securely install the pre-fabricated protective covers.

Manufacturing of the Trolley

• Fabrication and welding of the trolley frame
• Inspection of the trolley frame: Place the trolley frame on a platform to check for twisting and unevenness. Corrections can be made using flame straightening and weight pressing methods.
• Assembly of the trolley drive mechanism: Before installation, verify the overall alignment of the trolley frame. Install the trolley’s running wheel sets and drive system, and adjust them to meet the required specifications.
• Assembly of the trolley hoisting mechanism

Electrical Assembly in Eot Crane Manufacturing Process

Henan Kuangshan Crane possesses over 2,000 sets of precision processing and testing equipment, enabling the independent and high-standard completion of more than 20 processes in the crane manufacturing process. Our company has a comprehensive quality assurance system, strict management protocols, strong production capabilities, and advanced testing methods. For over two decades, Henan Kuangshan Crane has been dedicated to producing high quality products with precision and passion, ensuring that every user can use them with confidence and peace of mind.

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