Ⅰ. Lifting motor of electric hoist
1. The type, basic parameters, performance and size of the motor should conform to the design of the product and the use requirements of the main engine.
2. The enclosure protection level of the motor should not be lower than P44 (except for the wind cover).
3. The locked-rotor torque, maximum torque and locked-rotor current of the motor under the rated voltage should meet the regulations.
4. The lead wire of the motor should have a phase sequence mark. There should be a grounding screw at the junction box of the electric hoist motor, and a grounding sign should be set near the grounding screw. This sign should be clear throughout the service life of the motor.
5. The fastening bolts of the motor should have anti-loosening measures.
6. The braking of the motor should be stable and reliable, and the static braking torque should meet the design requirements.
Ⅱ. Lifting hook of electric hoist
1. The appropriate lifting hook should be selected according to the rated lifting capacity of the electric wire rope hoist, the working level of the mechanism and the strength level of the hook.
2. The mechanical properties of the lifting hook should comply with the provisions of GB/T10051.1 "Lifting Hook Part 1: Mechanical Properties, Lifting Weight, Stress and Materials".
3. The rated lifting capacity should be marked on the eye-catching place of the hook group, and the hook opening locking device should be installed. The electric hoist for lifting molten metal should not be equipped with a locking device.
4. The use of forged hooks for electric hoists should comply with the provisions of GB/T10051.2 "Lifting Hooks Part 2: Technical Conditions for Forged Hooks". There should be no cracks, white spots and other defects that affect the safety of use. Welding repairs are not allowed for defects on the hook.
5. The lifting hook should be inspected before and during use. The forged hook inspection should comply with the provisions of GB/T 10051.3 "Lifting Hook Part 3: Forged Hook Use Inspection".
Ⅲ. Wire rope of electric hoist
1. The steel wire rope should meet the requirements of GB/T20118 "General Purpose Steel Wire Rope", and the wire contact type steel wire rope is preferred, and the nominal tensile strength is not less than 1570MPa. When the electric hoist lifts molten metal, the high-temperature-resistant steel wire rope with a metal core or a metal strand core whose performance is not lower than that specified in GB8918 "Important Purpose Steel Wire Rope" should be used.
2. When the hook is lowered to the lowest limit position, the remaining safety circle of the wire rope on the drum (except the number of circles for fixing the end of the rope) should be kept at least 2 circles. Under this safety circle, the rope end fixing device should not be deformed to cause loosening when it bears 2.5 times the maximum working static tension of the wire rope.
3. The use and maintenance of the electric hoist wire rope should comply with the provisions of GB/T 29086 "Safe Use and Maintenance of Wire Rope".
4. The end of the wire rope should be fixed reliably. When wedge joints are used, more than 200mm should be left after the fixed end of the wire rope passes through the wedge, and the steel wire at the end of the remaining rope head should not be loosely forked, and the loose forked part should be tied tightly with soft iron wire, the tightening length is more than 4 times the diameter of the wire rope. When the rope clamp is used for fixing, the rope clamp should be selected according to the nominal diameter of the wire rope, and the place where the wire rope is clamped should be smooth, flat and free of burrs.
5. The wire rope fixing parts should be inspected regularly to check the deformation, wear, cracks and sliding of the detachable wedge joints or rope clamps, as well as the broken wires and corrosion inside the device and the rope end, to ensure the fastening reliability of the rope end fixing. If there is obvious broken wire or corrosion in the vicinity of the rope end fixing device or in the rope end fixing device, the wire rope can be shortened and reinstalled on the rope end fixing device, and the length of the wire rope should be sufficient for the drum when the hook is at the lower limit. The number of turns (2 turns) required for upper winding.
Ⅳ. The pulley of the electric hoist
Electric hoists for lifting molten metal should not use cast iron pulleys.
Ⅴ. Rope guide for electric hoist
1. The electric hoist should be equipped with a rope guide or take other measures to prevent chaos.
2. When the rope guide is used, it should be able to ensure that when the hook is lowered and the wire rope has no other external force, the wire rope can still be discharged freely from the rope outlet of the rope guide. When the rated load is lifted and lowered, and the deflection angle of the wire rope to the vertical plane of the axis of the drum is ±3°, it can still work normally.
3. When the rope guide is used in conjunction with the lifting limiter, it should be able to ensure a reliable limit function.
4. The rope guide is a consumable part, it should be checked and maintained regularly, and it should be replaced in time if it is found to be worn.