2. Metallurgical cranes require cables, electric power and motors to meet the requirements of high temperature resistance, and the beam body has protective measures such as high temperature resistance.
If the general bridge crane has been used to lift molten metal, it should be replaced by a casting crane that meets the requirements of JB/T7688. 15- 1999 Technical Conditions for Metallurgical Cranes. In addition to meeting the laws, regulations and standards of general overhead cranes, the units that cannot replace the casting cranes due to factors such as workshop and foundation must also transform the original cranes and meet the following basic technical requirements:
1. Metallurgical cranes use special motors. When the temperature exceeds 40 degrees, the H-class insulated motor should be selected.
2. Two sets of independent brakes (double brakes) are installed.
3. The weight limiter must be installed.
4. Different types of double limiters (double limiters) (usually a combination of heavy hammer and rotary type) should be installed at the rising limit position to control different circuit breakers. For lifting with a lifting height greater than 20m, limiters shall be installed at the descending limit position as required.
5. Using SCR stator voltage regulation, eddy current braking, energy consumption braking, SCR power supply, DC device for speed regulation and other hoisting mechanisms that may cause overspeed due to speed regulation, as well as general bridge cranes over 20T used for lifting molten metal must have overspeed protection.
6. The hoisting mechanism should have the fault protection function of the forward and reverse contactors to prevent the motor from losing power when the brake is still energized, resulting in power loss and accidents.
7. The protection level of all electrical equipment shall meet the provisions of relevant standards.
8, long-term work in high temperature environment of hoisting machinery, its electronic control equipment need to take protective measures.
9. Choose wire rope suitable for high temperature occasions, and have enough safety factor.
10, cast iron pulley is necessary.
1 1. When the working level of the original crane is lower than A6 (excluding A6), it should be used with reduced load, and the load reduction range should be determined according to the actual working conditions, but the specified lifting weight after unloading should not exceed 80% of the original rated lifting weight.
All kinds of lifting machinery with rated lifting weight greater than 10T and electric hoist as lifting mechanism are not allowed to lift molten metal.
For all kinds of hoisting machinery with rated lifting weight less than or equal to 10T and electric hoist as lifting mechanism, the original cranes must be replaced or modified to meet the following basic technical advantages:
1, ordinary electric hoist shall not be used as lifting mechanism;
2, with support brake and safety brake.
3. There are different types of lifting double limiters (cranes with lifting height greater than 20m should also be equipped with descending limit position limiters).
4. It has a lifting limiter.
5. Electric hoist with high-temperature heat insulation protection function.
6. There is enough safety factor to improve molten metal, and the working level should reach M5 (including M5).
7. Choose the wire rope suitable for high temperature occasions, and the wire rope will gradually take shape with sufficient safety factor.
8, as far as possible, use remote control and other manipulation methods far away from the heat source, otherwise you must set up a safe passage for the operator.
Metallurgical Crane Metallurgical No.7 Middle School
Hopping is realized by longitudinal movement along the track direction of the factory building, lateral movement of the trolley and lifting movement of the hook. Suitable for metal smelting workshop, it is a special crane for lifting molten metal according to JB/T7688. 1-95 and JB/T7688. 15-95 standards.
Application of metallurgical crane
Generally applicable to the ambient temperature of-10℃ to +50℃, and the relative humidity at 40℃ is not more than 50. The radiation temperature of lifting molten metal to forging hook and plate hook shall not exceed 300℃. Working level: A7 and A8 are used in relatively busy metallurgical casting workshops.