1. It may be the fault of the elevator's anti-pinch system.

according to the national standard for elevators, "automatic doors driven by power should have anti-pinch devices." At present, the anti-pinch device is mainly realized by safety touch panel and light curtain. Some elevators are equipped with one type, while others are equipped with both light curtain and touch panel. When passengers get in and out of the car, the elevator door cannot be closed by blocking the safety touch panel or light curtain. Even if the safety touch panel or light curtain is blocked suddenly during the door closing process, the elevator door will stop and open itself. Under normal circumstances, the elevators controlled by centralized selection, parallel connection and cascade group will be closed for standby when there is no operation instruction. In the process of closing the door, especially when the door is about to be completely closed, the anti-pinch system (light curtain or safety touch plate connection) has poor contact and other faults, and the elevator control system will think that the passenger is blocking the light curtain or touch plate, and the door will bounce back. After a few seconds, the door will automatically close and then bounce back, which will affect the normal use. The solution is to check the light curtain and safety touch panel and eliminate the fault.

2. It may be that there is garbage in the hall door or the sill of the car door and the slide way of the upper sill

The national standard of elevator stipulates that "the force of the power-driven automatic door to stop closing the door should not be greater than 1.51 Newton, and this force should not be measured within 1/3 of the beginning of the closing stroke." The elevator door moves in the slideway of the sill and the upper sill. During the closing process, if there is garbage (such as dust, cloth, cigarette butts, pebbles, etc.) in the sill or the upper sill, the slideway will be blocked and the normal closing of the elevator door will be prevented. If the driving force of the door machine exceeds 1.51 Newton, the elevator door will bounce back (the garbage in the upper sill and the upper sill is not within the working range of the light curtain and the safety contact plate). Close the door again, then bounce off. The solution is to clean up the garbage in the slideway and ensure the slideway clean and smooth.