elevatorIt is an important equipment used in factories, and the down stroke limit switch is often damaged by collisions, causing great inconvenience to maintenance. The nut wears out rapidly and the electrical limit fails, so it needs to be modified.
1. Technical parameters and existing problems
1.1 The motor drives the worm gear reducer through the conical friction clutch, and the worm gear reducer drives the screw. The screw drives the sleeve with a nut to rise and lift the vehicle body.
1.2 Main parameters:
The motor model is Jo2-42-4, with a power of 5.5 kW and a speed of 1460 r/min. The transmission ratio of the worm gear reducer is i=27, and the modulus is m: 10 mm. The lifting screw Tr85 × 20 and the working height of the nut are 200 mm. The problems with the original equipment include:
(1) The lifting power of the equipment for the greenhouse truck is insufficient. The maximum lifting force of the equipment is 7 tons. Due to the weight of the shed car body being 25.4 tons, the ideal lifting capacity of the four elevators is 28 tons. However, in practice, it is difficult for the sleeves of the four elevators to fully contact the four corners of the car body, resulting in overloading of a single spiral elevator and severe nut wear. At the same time, it is necessary to avoid using a single elevator near full load; To improve the lifespan of nuts, the lifting force of a single unit should be increased.
(2) The use of a cone clutch is unreasonable. The cone friction clutch transmits torque by the friction between the contact surfaces. When the friction cone is overloaded, the relative sliding loss power of the friction cone protects the transmission parts from damage. In fact, it is difficult to control when the load is adjusted to 7 t, and it cannot be used in the motion chain with a certain transmission ratio, so it is difficult to meet the synchronous requirements of four screw elevators.
(3) Poor lubrication. The calcium based grease used for lubrication of this equipment can only be added once during assembly and cannot be added during equipment use.
(4) There are deficiencies in electrical control. The original control switch was modified from LW5, and the single action or linkage of the four lifting arms used one switch gear conversion, which resulted in inaccurate height positioning during operation. Whether the four lifting arms are of the same height or not depends entirely on visual observation and positioning. Due to differences in motor speed and damping performance, the lifting speed varies, causing unevenness in the four corners of the vehicle. Therefore, the operator needs to constantly observe and adjust the horizontal state of the four corners of the vehicle, which is very inconvenient.
(5) Insufficient electrical braking. The original elevator used DC energy consumption braking, and its braking performance decreased as the motor speed decreased. Due to the lack of other auxiliary braking measures, especially when carrying downward parking, the lifting weight is relatively large, and frequent collisions occur with the lower travel limit switch and electrical travel switch.
2. Improvement measures:
(1) Improve the lifting force of a single spiral elevator. We have re selected the drive motor, the lifting screw is T90 × 16, and the working height of the nut is 192 II] 111. After calculation and strength verification, the lifting force of a single screw elevator has reached 16 tons
(2) The coupling of this equipment needs to ensure both synchronous transmission speed and overload protection. Therefore, a nylon column pin coupling was selected, and the diameter of the column pin was calculated and experimentally verified. When the lifting force exceeds 15 tons, it will be cut off
(3) Due to the installation of the spiral elevator entirely in the pit, with the sleeve positioned 300mm above the ground, an oil injection hole is added at the top. Oil is added once per shift, with a volume of approximately 200-300 ml, to maintain good lubrication of the screw and reduce the friction coefficient.
(4) Improve electrical control.
(a) Select the appropriate control components. SA1 switch is a three position switch with elastic reset, SA2 is a two position switch without elasticity, and SB1 is an emergency stop self-locking switch. The 1 4CK travel switch is designed for simultaneous detection of 4 arms, and its installation position is at the top of the original 4 arms. When there is no vehicle body placed, the normally open contact is in a disconnected state. Only when the weight on it exceeds 3 tons (when the designed built-in spring travel is 20mm, a pressure of 3 tons is required), the normally open contact is pressed and in a standby state. When the 1~4CK travel switch is fully pressed, the vehicle body will rise. The 5-12CK travel switch is a limit switch with 4 arms.
(b) Increase the detection of contact between the lifting arm and the vehicle body, and achieve automatic compensation. During the lifting process, the lifting speed varies due to differences in motor speed and damping performance, resulting in uneven four corners of the vehicle body. To prevent this situation from happening, real-time detection is performed on each lifting arm in automatic control mode, so that the arm that comes into contact with the upper arm first waits for the arm that does not come into contact to come into contact during the lifting process (i.e., after the four corners of the vehicle are stable) before lifting simultaneously, to prevent accidents such as vehicle overturning.
(c) Add manual adjustment function. During use, it can be switched from automatic control mode to manual control mode, and the height of the four corners of the vehicle can be adjusted to meet the needs of temporary or repair faults on site.
(d) Improve braking performance. On the basis of DC energy consumption braking, combined with brake pad friction braking, improve the accuracy of stopping stability; The newly selected motor model is Y132M2-6, with a power of 5.5 kW and a speed of 960 r/rain. It has a B5 base, two output shafts at both ends, and a rear brake wheel to ensure the accuracy of the elevator start stop position and the safety of the vehicle body and elevator
Four SJA spiral elevators have been renovated to completely overcome the faults of rapid nut wear and electrical limit failure, ensuring smooth production and greatly reducing maintenance workload.
