How to select the operation mode of a single-beam bridge crane based on the weight of the workpiece

1. Mode selection based on load characteristics

Light load/no load mode

Applicable scenario: lifting weight ≤ 30% of rated load (such as tools, small parts).

Mode characteristics:

High-speed operation: The speed of both the crane and the trolley can be increased to 1.2-1.5 times the rated speed, reducing non-production time.

Quick response: The lifting mechanism adopts a light-load quick gear to reduce waiting time.

Technical basis: When operating under light load, the motor has sufficient power margin, so increasing the speed will not cause overload, and can significantly enhance operational efficiency.

Case: When a certain automobile parts factory adopts the light-load mode for lifting light tooling on the assembly line, the single-shift operation time is shortened by 20%.

Overload mode

Applicable scenarios: lifting weight ≥ 80% of rated load (such as engines, large molds).

Mode characteristics:

Low-speed stable travel: The speed of both the crane and trolley is limited to 0.5-0.7 times the rated speed to reduce inertial impact.

Graded lifting: The lifting mechanism is controlled in two levels:

First gear (low speed gear): used to overcome static friction and avoid sudden lifting that may cause load swaying;

Second gear (high speed gear): Switch to this gear after the load is lifted off the ground to shorten the lifting time.

Technical basis: When operating under heavy loads, it is necessary to balance efficiency and safety. Running at low speeds can reduce braking distance (braking distance is proportional to the square of speed), preventing overload alarms or structural damage.

Case: When lifting a steel ladle at a steel plant, the braking distance was shortened from 8m to 3m after adopting the heavy-load mode, thus avoiding a steel spill accident.

II. Mode selection based on homework frequency

Intermittent operation mode

Applicable scenarios: Single lifting cycle > 5 minutes (such as equipment maintenance, warehouse stocking).

Mode characteristics:

Standby energy saving: In the non-working state, the motor automatically enters a sleep mode to reduce no-load energy consumption.

Soft start control: The frequency converter is used to gradually accelerate during each startup to prevent the impact of frequent start-stop operations on the power grid.

Technical basis: Under intermittent operation, the equipment operates for a low proportion of time, and priority should be given to reducing standby energy consumption (which accounts for 30%-40% of the total energy consumption of the equipment).

Case: After adopting an intermittent mode, the average daily electricity consumption of a single crane in a logistics center has decreased from 45 kWh to 32 kWh.

Continuous operation mode

Applicable scenarios: Single lifting cycle < 2 minutes (such as material handling in production lines, container loading and unloading at ports).

Mode characteristics:

Constant power control: The output power of the motor remains constant to avoid efficiency loss due to load fluctuations.

Multi-mechanism linkage: The large vehicle, small vehicle, and lifting mechanism move synchronously to reduce intermediate waiting time.

Technical basis: For continuous operation, it is necessary to maximize equipment utilization. Constant power control ensures that the motor always operates in the high-efficiency zone (efficiency ≥ 90%).

Case: After adopting a continuous production mode, the output per shift of a certain automobile factory's production line increased by 15%.