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JB/T 7688.5-2012 PDF in English


JB/T 7688.5-2012 (JB/T7688.5-2012, JBT 7688.5-2012, JBT7688.5-2012)
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Standards related to: JB/T 7688.5-2012

JB/T 7688.5-2012: PDF in English (JBT 7688.5-2012)

JB/T 7688.5-2012
JB
MECHANICAL INDUSTRY STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
ICS 53.020.20
J 80
Filing No.:
Replacing JB/T 7688.15-1999
Specifications for metallurgy cranes - Part 5: Ladle cranes
ISSUED ON: MAY 24, 2012
IMPLEMENTED ON: NOVEMBER 01, 2012
Issued by: Ministry of Industry and Information Technology of PRC
Table of Contents
Foreword ... 3 
1 Scope ... 6 
2 Normative references ... 6 
3 Terms and definitions ... 7 
4 Technical requirements ... 7 
4.1 Basic requirements ... 7 
4.2 Environmental conditions ... 7 
4.3 Lifting capacity ... 7 
4.4 Main components ... 8 
4.5 Safety ... 9 
5 Test method ... 11 
5.1 Visual inspection ... 11 
5.2 Static load test ... 12 
5.3 Static stiffness test ... 12 
5.4 Rated load test ... 12 
5.5 Dynamic load test ... 12 
5.6 Safety brake test ... 12 
5.7 Electric braking deceleration test of hoisting mechanism ... 13 
5.8 Noise test ... 13 
5.9 Vertical and horizontal deflection detection of bridge and trolley wheels ... 13 
6 Inspection rules ... 13 
7 Labeling, packaging, transportation, storage ... 13 
Specifications for metallurgy cranes - Part 5: Ladle cranes
1 Scope
This Part of JB/T 7688 stipulates the technical requirements, test methods, inspection
rules of ladle cranes (hereinafter referred to as cranes).
This Part applies to cranes for lifting molten metal.
2 Normative references
The following documents are essential to the application of this document. For the dated
documents, only the versions with the dates indicated are applicable to this document;
for the undated documents, only the latest version (including all the amendments) is
applicable to this standard.
GB/T 1591-2008 High strength low alloy structural steels
GB/T 2970-2004 Thicker steel plates - Method for ultrasonic inspection
GB/T 3811-2008 Design rules for cranes
GB/T 5973 Cuneiform connector for use with steel wire ropes
GB/T 5976-2006 Wire rope grips
GB/T 6974.1 Cranes - Vocabulary - Part 1: General
GB/T 6974.5 Cranes - Vocabulary - Part 5: Bridge and gantry cranes
GB 8918 Steel wire ropes for important purposes
GB/T 10051.1 ~ 10051.15-2010 Lifting hooks
GB 12602 Lifting appliances - Safety devices against overloading
GB/T 19418-2003 Arc-welded joints in steel - Guidance on quality levels for
Imperfections
GB/T 20303.5 Cranes - Cabins - Part 5: Overhead travelling and portal bridge cranes
JB/T 6061 Non-destructive testing - Magnetic particle testing of welds
JB/T 6406 Electro-hydraulic drum brakes
JB/T 7020 Electro-hydraulic disc brakes
JB/T 7688.1-2008 Specifications for metallurgy cranes - Part 1: General
requirements
JB/T 9008 (all parts) Electric wire rope hoists
3 Terms and definitions
The terms and definitions, which are defined in GB/T 6974.1 and GB/T 6974.5, apply
to this document.
4 Technical requirements
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.
4.4.1.2 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.
4.4.1.3 If the main hook adopts the laminated hook, it shall meet the requirements of
GB/T 10051.13 ~ 10051.15-2010.
4.4.1.4 The forged hook used on the crane shall comply with the provisions of GB/T
10051.1 ~ 10051.12-2010.
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.
......
 
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.