外文翻译自动焊接操作系统精品.docx

1、外文翻译自动焊接操作系统精品An automated welding operation planning systemfor block assembly in shipbuildingKyu-Kab Cho*, Jung-Guy Sun, Jung-Soo OhAbstractThe block assembly process is one of the most important manufacturing processes for shipbuilding. Since block is composed of several steel plates and steel sec

2、tions with predetermined shapes according to ship design, the welding operation planning to construct a block is a critical activity for shipbuilding, but this activity has traditionally been experience based. Thus, it is required to develop an automated welding operation planning system to assemble

3、 blocks. This paper describes the development of an automated welding operation planning system for block assembly in shipbuilding. Based on the information about parts, topological relationship between parts and assembly sequences for block, the developed system performs the determination of weldin

4、g postures, welding methods, welding equipment and welding materials. The developed system implemented successfully for real blocks constructed in shipyard.Keywords: Block assembly; Expert system; Operation planning; Welding process1. IntroductionShipbuilding is traditionally a labor-intensive assem

5、bly industry that employs the welding process as a basic production technology. In shipbuilding, there are several types of manufacturing process planning for cutting and bending, assembly, out- fitting, and erection. Among these process planning activities, the assembly process planning is by far t

6、he most important, since the construction process for a hull block comprises approximately 4850% of the total shipbuilding process 1,2. The main operation for block assembly is the welding operation. The welding operation planning problems in block assembly are very difficult to solve because all bl

7、ocks are different in size, type, and constituting sub-assemblies that depend on the types of ships. Also, since this activity has traditionally been experienced-based, welding operation planning in shipbuilding has been performed manually. Thus, it is very important to develop an automated weldingo

8、peration planning system for shipbuilding. There is relatively very little literature available on automated welding operation planning systems for shipbuilding 3,4. This paper deals with the development of an automated welding operation planning system for block assembly in shipbuilding. The rule-b

9、ased expert system for welding operations has been developed using Smart Elements as an expert system tool. The developed system is demonstrated and verified by using actual blocks in the shipyard.2. Development of an automated welding operation planning system2.1. System frameworkThe automated weld

10、ing operation planning system developed in this paper consists of four modules: welding postures module, welding methods module, welding equipment module, and welding materials module. The framework of this system is shown in Fig. 1.2.2. Determination of welding posturesThis module determines the po

11、sture of the welding operator. Welding posture is reasoned by considering connection types and positional direction between two connected parts, direction information of assembly base part, existence of turnover, and assembly level.Connection types are classified into butt type (B) and fillet type (

12、T), as shown in Fig. 2. The four types of welding postures, down posture (D), overhead posture (O), horizontal posture (H), and vertical posture (V), are considered in this paper, as shown in Fig. 2 5,6. The most stable and easiest welding posture is the down welding posture, and the most difficult

13、one is the overhead welding posture. The welding operator determines an efficient welding posture according to the working conditions.For relationship of connection between two parts that are welded, one part is considered as the base and the other is connected to the base. The part that is consider

14、ed as a base is represented as PartFrom and the other that is connected to the base is represented as PartTo. The levels of block assembly to assemble steel plates and sections into the final block are classified into subassembly (SA) level, unit block assembly (UBA) level, and final block assembly

15、(FBA) level.Subassembly levels may be divided into small subassembly (SSA) levels and intermediate subassembly (ISA) levels according to the size and weight of the subassembly as shown in Fig. 3.For determining welding postures, the block assembly levels are classified into two groups. The first gro

16、up is the small subassembly level; the second group consists of the intermediate subassembly, the unit block assembly, and the final block assembly levels. The reason for this grouping is that there is no turnover process in the small subassemblylevel, but the assembly levels belonging to the second

17、 group may have turnover processes. Turnover processes cause the change of welding postures that are determined before the turnover process.2.2.1. Determining welding postures in the first group levelThe following are examples of rules to determine the welding posture for a small subassembly level.

18、The connection types of welding joints between two parts used in this rule are: Butt type (0) and T type (1).(1) IF (Part Level=Small Assembly)(Connection Type=1)(Direction of Assembly Base=Connection Direction)(PartFrom=not Assembly Base Part)(PartTo=not Assembly Base Part)THEN (Welding Posture=H)(

19、2) IF (Part Level=Small Assembly)(Connection Type=1)(Direction of Assembly Base Part=not Connection Direction)(PartFrom=not Assembly Base Part)(PartTo=not Assembly Base Part)THEN (Welding Posture=V)An example of a small subassembly is shown in Fig. 4. In this case, there are ve parts, and the assemb

20、ly base parts are A and B. The relationships between the parts are listed in Table 1 and the results of the determination of welding postures for this example are shown in Table 2.2.2.2. Determining welding postures in the second group levelsIn the second group levels, information for determining we

21、lding postures is the same as for the small subassembly level. Welding postures are determined between the assembly base part and other parts that are connected to the assembly base part in a similar way to the small subassembly. Other welding postures are determined between parts that are not an as

22、sembly base part. If turnover processes exist, the direction of the assembly base part is changed at an angle of 180 and the welding posture is also changed. An example of the rules for the second group levels are as follows:(1) IF (Part Levelnot Small Assembly)(Connection Type is 0)(Direction of As

23、sembly Base PartConnection Direction)(PartFromnot Assembly Base Part)(PartTonot Assembly Base Part)THEN (Welding PostureH)(2) IF (Part Levelnot Small Assembly)(Connection Type0)(Direction of Assembly Base Partnot Connection Direction)(PartFromnot Assembly Base Part)(PartTonot Assembly Base Part)THEN

24、 (Welding PostureV)2.3. Determination of welding methodsThis module determines the welding methods based on welding postures by rule-based reasoning. Welding methods used in this paper are summarized in Table 3, according to the connection types of welding joints and welding processes 7.In general,

25、there are several welding techniques such as braze welding, forge welding, gas welding, resistance welding, induction welding, arc welding, and special welding. Considering the features of shipbuilding, the welding process used in the shipyard is the arc welding process. Arc welding is a process in

26、which coalescence is obtained by heat produced from an electric arc between the work and an electrode 8.Arc welding is classified into several types, according to the welding mechanisms such as shield metal arc welding (SMAW), flux cored arc welding (FCAW), submerged arc welding (SAW), and electroga

27、s arc welding (EGW). SMAW is one of the oldest, simplest, and most versatile joining processes. Currently, about 50% of most industrial and maintenance welding is performed by this process, but this process is used approximately less than 5% at most large shipyards. In FCAW, an electrode that is tub

28、ular in shape is used, and if necessary, the welding area is shielded by carbon dioxide. In SAW, the weld arc is shielded by granular flux, consisting of lime, silica, manganese oxide, calcium fluoride, and other materials. The flux is fed into the weld zone by gravity flow through a nozzle. EGW is

29、used primarily for welding the edges of sections vertically in one pass, with the pieces placed edge to edge (butt type) 9. To build the knowledge base for the determination of welding methods, knowledge is aquired from welding handbooks and experts. Input information of this module is geometrical i

30、nformation that is provided from CAD system and the welding posture determined by welding posture determination module. The knowledge is represented by rules. The examples of the rule for the determination of welding methods are as follows:(1) IF (Connection Type=0)(Groove=none)(Welding Posture=O)(6

31、Thickness50)THEN (Welding Method=SMAW-MANUAL BUTT)(2) IF (Connection Type=1)(Leg Length4.5mm)(Welding Posture=O, H, V)THEN (Welding Method=FCAW-FILLET)2.4. Determination of welding equipmentThis module selects the appropriate welding equipment by rule-based reasoning based on information about weldi

32、ng postures and welding methods. Table 4 shows the relationship between welding methods and welding equipment. After determining welding methods, welding equipment is automatically selected by using the information contained in Table 4.2.5. Determination of welding materialsThis module determines the most proper welding materials by rule-based reasoning, based on information about welding postures, methods, and equipment. In general, steels used for block assembly are mild steels and high tensile steels. Mild