JB/T 7688.5-2012Specifications for metallurgical cranes - Part 5: Ladle cranes (English PDF)

4.1 Basic requirements

Except for the following requirements, other technical requirements shall comply with the provisions of Chapter 3 of JB/T 7688.1-2008.

4.2 Environmental conditions

The minimum working environment temperature of the crane is -10 °C; the maximum is not more than 60 °C.

4.3 Lifting capacity

4.3.1 The lifting capacity of the crane shall reach the following rated lifting capacity:

a) For a crane equipped with an inseparable rigging, its rated lifting capacity is the sum of the mass of the molten metal container (such as a ladle) and the mass of the molten metal;

b) For a crane equipped with a separable rigging gear, its rated lifting capacity is the sum of the mass of the separable rigging, the mass of the molten metal container (such as a steel ladle), the mass of the molten metal.

4.3.2 The rigging of the crane adopts the following two structural types:

a) Inseparable rigging I: The steel wire rope of the main hoisting mechanism directly hangs the spreader beam, which has two laminated hooks. For ladle cranes in steelmaking plants, when lifting heavy tanks of molten iron, molten steel or liquid slag, use a ladle crane with a fixed gantry hook. installed on the crane, are installed on the spreader beam, reliable measures against radiation heat shall be taken.

4.4 Main components

4.4.1.2 Welded forks

4.4.1.2.1 The stress direction of the welded fork shall be consistent with the rolled fiber direction of the steel plate, meanwhile the mechanical properties of the steel plate shall not be lower than the Q345B steel in Table 1 of GB/T 1591-2008.

4.4.1.2.2 When the main stress-bearing fillet welds of the welded fork are subjected to magnetic particle testing, according to the provisions of JB/T 6061, cracks are not allowed; other welding quality shall meet the provisions of C (medium) in GB/T 19418-2003, meanwhile perform annealing treatment before machining, to eliminate welding stress.

4.4.2 Steel wire rope

4.4.2.1 It shall use the steel wire ropes with metal wire rope core or metal wire strand core, which comply with GB 8918.

4.4.2.2 When the end of the wire rope is fixed with wire rope clamps, the quantity and fixing method shall comply with the provisions in Appendix A of GB/T 5976-2006.

4.4.2.3 When the end of the steel wire rope is fixed with wedged joints, the wedged joints shall comply with the provisions of GB/T 5973.

4.4.3 Cab

When the crane is controlled by the driver's cab, it shall adopt a closed driver's cab, which shall comply with the relevant provisions in GB/T 20303.5.

4.5 Safety

4.5.1 Two sets of brakes, that meet the requirements of JB/T 6406 or JB/T 7020 AND can work independently, shall be installed on the drive shaft of each set of main hoisting mechanism transmission chain. The safety factor of each set of brakes shall comply with the requirements of 6.1.1.3.1.3c) in GB/T 3811-2008.

4.5.2 The transmission chain of the main hoisting mechanism (except electric hoist) shall meet one of the following conditions:

a) The main hoisting mechanism is equipped with two sets of drive devices, which are rigidly connected to the output shaft;

b) The main hoisting mechanism is equipped with two sets of driving devices. When there is no rigid connection on the output shaft OR when the main hoisting mechanism is equipped with a set of drive devices, a safety brake shall be installed on the wire rope drum;

Note: Two sets of driving devices refer to two sets of electric motors, two sets of reduction systems, one or more sets of reel devices, four sets of brakes.

c) For cranes with a rated lifting capacity not greater than 16 t, when designing the hoisting mechanism, its working level shall be at least 2 levels higher than that required by the actual operating conditions, meanwhile the minimum working level shall not be lower than level M5.

4.5.3 For the main hoisting mechanism, which uses two sets of driving devices, when one of the motors or one set of electric control devices fails, the other drive device shall be able to complete a working cycle, at the rated lifting capacity.

4.5.4 The wire rope of the main hoisting mechanism shall meet the following conditions:

a) Four wire rope winding systems shall be adopted for double lifting points;

b) A single lifting point adopts at least two wire rope winding systems;

c) The safety factor shall comply with the relevant provisions in GB/T 3811. For cranes with a rated lifting capacity not greater than 16 t, the safety factor shall not be less than 5.6.

4.5.5 In the wire rope winding system of the main hoisting mechanism, a balanced pulley shall not be used.

4.5.6 The main hoisting mechanism shall be equipped with different forms of dual secondary protection devices, at the limit position of the lift, AND can control different circuit breakers. When the pick-up device rises to the limit position specified in the design, the first protection device shall be able to cut off the lifting power source of the lifting mechanism, the second protection device shall be able to cut off the power source of the next higher level; if necessary, an interlocking protection device for the lower limit position shall be installed.

4.5.7 The main and auxiliary hoisting mechanisms shall be equipped with lifting weight limiters, that meet the requirements of GB 12602.

4.5.8 The main hoisting mechanism shall be equipped with overspeed protection; the overspeed setting value is 1.2 ~ 1.3 times of the maximum working speed (the maximum working speed refers to the maximum stable running speed, that can be […]

5.2 Static load test

It is carried out, according to the provisions of 4.2 in JB/T 7688.1-2008.

5.3 Static stiffness test

It is carried out, according to the provisions of 4.3 in JB/T 7688.1-2008.

5.4 Rated load test

It is carried out, according to the provisions of 4.4 in JB/T 7688.1-2008.

5.5 Dynamic load test

It is carried out, according to the provisions of 4.5 in JB/T 7688.1-2008.

5.6 Safety brake test

5.6.1 General

During the type test of the crane, the safety brake shall be subjected to function test and capability test.

5.6.2 No-load function test

5.6.2.1 Simulated overspeed braking test: Start the hoisting mechanism, to simulate an overspeed failure (such as reducing the setting value); the system alarms; the hoisting system stops. Then the working brake shall be applied before the safety brake, meanwhile there is no mechanical damage.

5.6.2.2 Braking test for simulated broken shaft: Start the hoisting mechanism, to simulate a broken shaft failure (such as stopping the encoder signal on one side). The hoisting system shuts down. Then the working brake shall be applied before the safety brake, without mechanical damage.

5.6.3 Rated load braking capacity test

Under the condition of rated load, the main hoisting mechanism stops working; the working brake and the safety brake are applied successively. When the working brake is manually opened, the load does not slide down. […]