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Procedia Engineering 24 (2011) 783 – 787
2011 International Conference on Advances in Engineering
The Research on Optimal Design of Large Metallurgical Crane
Xianwen Wua, Bo Chena , Dan Zhanga, Jian Lib,a*
d
Sichuan Engineering Technical College,DeYang618000,China
China Second Heavy Industrial Group Corporation,DeYang618000,China
a
Abstract
According to the application, structure and technical requirements of 320/50t-22m large quenching crane, the general structure and hoisting mechanism of crane were optimized, the main technical parameters of crane were calculated. The key issues in the design were discussed. The references on the future design and calculation of similar cranes were provided. The paper has some application value.
? 2011 Published by Elsevier Ltd. Open access under CC BY-NC-ND license. Selection and/or peer-review under responsibility of ICAE2011.
Keywords:Metallurgical Crane, Optimization, General structure, Hoisting mechanism.
a) Introduction
Metallurgical crane is a kind of lifting equipment. It is always used in these departments, for example, casting sector, forging departments, quenching sector, metallurgy sector. With the development of power generation equipment, petroleum, chemicals, heavy machinery and higher quality requirements of users for large forgings, both of heat treatment technology and equipment are needed a corresponding increase. In addition, the size of quenching crane used for lifting heavy forgings is also increased. Because the weight of quenching crane is large, and the manufacture of quenching crane is more complex, it has high technical difficulties in the design. Thus, the size of 320/50t quenching crane is very large in China. The optimization of general structure and hoisting mechanism of the crane will be discussed as follows[1].
b) Key technical features of crane
According to the working principle of metallurgical crane and design requirements, design handbooks for crane were consulted, key technical features of crane were gotten as follows.
* Corresponding author. Tel.: 13678389985 E-mail address: wuxianwen01@163.com
1877-7058 ? 2011 Published by Elsevier Ltd. Open access under CC BY-NC-ND license. doi:10.1016/j.proeng.2011.11.2737
Xianwen Wu et al. / Procedia Engineering 24 (2011) 783 – 787 784
? Lifting capacity
Main hook: 320[t]; Auxiliary hook: 50[t]. ? Span Lk=22[m].
? ) Lifting height
Main hook: 23[m]；Auxiliary hook:24[m]. ? Rated working speed
Key Lifting Mechanism of main hook:16 [ m/min]； Key Lifting Mechanism of auxiliary hook:19.6 [m/min]；
Trolley travelling speed:26 [m/min]；Crane travelling speed:41 [m/min]. ? Limit position
Distance between the center of main hook and the rail surface of crane: 2000[m]. Distance between the center of auxiliary hook and the rail surface of crane: 1000[m].
c) Design standard and principle
In view of applying working condition and working requirements of metallurgical crane, hoisting capacity, price and speed must be considered. So the standards GB3811-83 specification for crane design, the standards GB6067-85 specification for crane safety and the standards JB5898-91 specification for metallurgical crane must be abided during design process [2]. There are some considered factors, such as surface treatment of steel structure, electrical system protection and operation mode. Electrical control mode is implemented through frequency converter. The calculation of crane bridge, the calculation of choice model proof of the whole crane layout scheme and the whole design calculation can be realized by the ways of the conditioned place calculation or the analysis of analogy method. The mechanical method to calculate the internal force of dangerous section is used in the structure. Design a cross-section and check strength, rigidity by allowable stress method or limit state method in order to optimize the overall design of the crane [3].
d) General structure of the crane
320/50t bridge crane is a quenching crane which combines with large scale work-piece to do for the hardening treatment, at the same time, and it can be used as hoisting equipment for large parts. This crane consists mainly of a trolley, the bridge frame, the travelling mechanism of the larger traveler, the overload safety protection device, the driver cab,the maintenance chamber, the trolley power chamber, the drying- oil lubricating device, the electrical system. The structure of crane is as shown in Fig.1.
①-Trolley Power Supply ②-Maintenance room ③-Driver room ④-Trolley ⑤Bridge ⑥ -Gantry Fig.1 Main components of metallurgical crane
?
Trolley
Xianwen Wu et al. / Procedia Engineering 24 (2011) 783 – 787 785
A trolley consists mainly of a trolley frame, master-slave hoisting mechanism, wheeling mechanism, and 320/50t subassembly of hanger which is shown in Fig.2. Every main beam and end beam of trolley frame are both for box-section beam structure. Trolley frame for assembled structures has sufficient strength and rigidity, on the other hand, it must be certain that their connections are safe and reliable. Trolley frame deformation when it acted by load should be without influence in their normal work.
①-320t Hook group ②-50t Hook group ③-trolley travelling mechanism ④-Main lifting mechanism
⑤-Trolley frame ⑥-Auxiliary lifting mechanism
Fig.2 Car of metallurgical crane
Master hoisting mechanism
Four ordinary motors separately drive four drums via gear reducer and realize mechanical synchronous for four drums by combining high-speed synchronous shaft with the two-motor synchronous system. Slave hoisting mechanism
A motor drives twin-drum via gear reducer. The winding system is linked to winding drum groups, fixed pulley groups and mobile pulley groups through the rope.
Four groups of disk brakes are used by master hoisting mechanism, but two-part hydraulic thruster brake is used by slave hoisting mechanism. The winding drum is made by steel plate with rolling-welding
Xianwen Wu et al. / Procedia Engineering 24 (2011) 783 – 787 786
procedure. The rolled wheel flange pulley is used. The motor of medium hard tooth surface with double input and double output is utilized. Wheeling mechanism of trolley
The centralized driving method of trolley’s wheeling mechanism is 1/4 duty. Motors drive two wheels via vertical gear reducer which is fixed on the trolley [4].
The motor is linked to the gear reducer through full tooth couplings. The connection between gear reducer and wheel is realized by cross-axle universal shaft couplings. Angle-closure bearing box is used by wheel groups. Double-flange cylindrical tread type is used by wheels. The type of hydraulic thruster brake is block. The type of vertical gear reducer is QJ and has middle hard gear-face. ?
Safety protection
Master-slave hoisting mechanism has position limitation protection switch and over-speed protection switch. The overload restrictor is set under the balancing arm of master-slave hoisting mechanism, and a suggestive alarm can send out when the rating load is 90%. In addition, hoisting mechanism can only decrease when the rating load is 105%.
One rotary encoder is each installed on the low speed axial of two gear reducers to detect synchronization of low speed axial. The practical production shows that the synchronization error of low speed axial of two gear reducers is more than 5% on the start, the motor is immediately made to stop running.
e) Design calculation of key Lifting Mechanism of crane
? Calculation of maximum static pulling force of wire rope
Q
S ? (1)
2myy1
Q1 -Weight of hoisting load ( Q1 ??320[t] ); Q2 -Deadweight of spreader( Q2 ??30[t] ); m - multiplying power of pulley block ( m ?12 ); Q ??Q1 ??Q2 ;
y2 - Efficiency of guide pulley ( y2 ??0.98 ); y1 - Efficiency of pulley block ( y1 ??0.95 );
The result of S is 15.66[t].
? Selection of wire rope
The maximal broken pulling force must be satisfied the following conditions through Eq.2.
Smax
??n S
(2)
The type of wire rope is 44ZAA6×36SW+IWR1670ZS which the broken pulling force of this wire rope is 117.2[t]. The actual safety coefficient of wire rope is 7.5 [5].
? Calculation of drum length
Effective length of drum can be calculated through Eq.3. (3) A. n)
L0 ??(0
?D??t
H - Maximal lifting height ( H ??23.5[m] );
m - Multiplying power of single group pulley block ( m ??6 );
Hm