Application of self-propelled trolley lifting system in welding line
The Jiefang J6 truck welding production line was completed and put into operation in 2005. The transportation of the floor, side wall, rear wall and top cover to the main welding line is carried out by the self-propelled crane transport system. Take the car body lower assembly floor assembly as an example, and the system structure is shown in Figure 1. The lifting and lowering power of the spreader is provided by the electric hoist. Four movable lifting points are installed on the spreader, and the electric hoist lifting chain is connected to adjust the position of the four fixed lifting points to realize the leveling and lifting of the spreader. And the drop and the smoothness are guaranteed by the scissors fork balance mechanism. The motor in the assembly spreader system is used to control the spreader bracket opening and closing. The spreader adopts the distributed control, and the spreader comes with a PLC system to realize the distributed control of the main control cabinet, as shown in Figure 2. In the course of use, the self-propelled car transport line has been widely recognized in terms of function, control flexibility and reliability, but the combination of the electric hoist and the scissor fork balance mechanism gradually revealed the following problems: The self-propelled trolley is a monorail-mounted automatic conveying system. The self-propelled car consists of three parts: the front car (guide car), the medium car (load car) and the tail car. With walking motor, lifting motor, clamp motor, control box and multiple sensors, it can realize the functions of forward, backward, left and right turn, lifting and lowering of spreader and opening and closing of spreader. The overall structure is shown in Figure 3. The traveling motor and the current collector are installed on the guiding trolley, the control box is installed in the front part of the trolley, and the trolley motion control system is installed in the box, and the guiding trolley drives the entire self-propelled trolley system to walk on the track. The current collector is connected with the track slip line, and the power supply of the trolley is obtained from the track and the mobile bus is used to control the walking of the trolley, the lifting and lowering of the spreader, and the opening and closing of the clamp. The new spreader lifting system adopts a belt lifting mechanism, the lifting and lowering power is provided by the electric motor, the four-point hanging assembly spreader, and four points are distributed at the four corners of the spreader, and the assembly crane is well controlled. Balanced. The main drive motor that realizes the lifting function of the entire spreader directly drives the two belt winding wheels fixed on the shaft through the coupling, so that the belt is wound in the winding wheel, and then the belt is contracted and elongated in the vertical direction by the steering wheel. To achieve the function of rising and falling. The four belts are respectively connected with the spreader, and the lifting mechanism has a broken belt protection device, and the lifting position is controlled by an absolute value encoder. The system has speed detection and overspeed protection function; the lift over position switch is installed in the lifting spreader; and the positioning guide mechanism is installed at the motor frame base and the spreader frame to control the position of the spreader when it is raised in place, and at the same time ensure the self-propelled car The stability of the entire spreader relative to the drive motor frame during exercise. A maintenance lock wheel is provided in the system to facilitate the maintenance of the pulley and other maintenance operations. The clamp motor can open and close the spreader to realize the function of gripping the workpiece. Zinc Door Handle On Zinc Plate Wenzhou Shenghong Metal Products Co.,Ltd , https://www.shenghonglock.com
Self-propelled trolley crane transport line is a logistics transport system that highly reflects mechatronics technology. It combines the four essential technologies of mechanical, electrical, computer and automatic control. It is a combination of four logistics links: warehousing, transportation, loading and unloading, and process operation. The flexible production system, often referred to as the self-propelled car system. In the past ten years, with the improvement of the modernized large-scale assembly line operation level of China's automobile automatic production line, the self-propelled car system has developed rapidly. Compared with the traditional airborne chain conveyor equipment, it has the characteristics of low noise, strong flexibility, multiple functions, flexible layout, and safe and reliable work.
Production status 
figure 1 
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1) The failure rate of the scissors fork balancing mechanism is relatively high. Since the mechanism is composed of a plurality of scissor-fork structures and has a complicated structure, it has high requirements for manufacturing precision. In the field use, the matching precision between the scissors and the forks is insufficient, so that the shaft is broken due to excessive force, and the scissor structure needs to be frequently repaired.
2) Although the electric hoist lifting point has four points connected with the hoist, the distribution of the four points is limited, and the balance of the sling can not be well controlled; the structure of the scissor fork is complicated, the precision is difficult to guarantee, and the hoist is lifted and lowered. The stability is not good.
3) The poor balance between the lifting and lifting of the spreader leads to a large impact on the guiding track; at the same time, the noise generated by the scissor fork during the lifting and landing is very large, which has an impact on the working environment.
4) The lifting point connected to the electric hoist on the spreader is movable. Although the leveling of the spreader can be carried out, there will be a small amount of movement of the lifting point during use, which causes the spreader to tilt and affects normal production use.
5) The scissors fork itself has a large weight, which increases the lifting load of the electric hoist and improves the selection criteria of the electric hoist.
Belt lift spreader application
Based on the existing problems of the combination of the electric hoist and the scissors and fork slings, combined with the actual situation of the production workshop, after investigation and demonstration, it is decided to try to use the four-point lifting hoist on the car body lower assembly floor assembly hoisting automatic trolley conveying system. Instead of the combination of the electric hoist and the scissor fork, the lifting of the floor assembly from the lower line to the main welding line is achieved by a new lifting method. 
Figure 3 The overall structure of the self-propelled car