Compound is backing down welding ,welding electrodes and heat welding are used in the welding to the welding method, welding and capping fill up welding method using the welding process. The wall thickness is mainly used in welding large pipes. The decade of the 20th century 90 large wall thickness of pipe is widely used in domestic and international oil, gas and water industry in the long-distance pipelines, water pipelines in the industry, the pressure above the normal diameter of 1m, the wall thickness of 10 ~ 60mm, in northern China cold regions oil and gas pipeline wall thickness of 10 ~ 24mm. Compared with the traditional upward welding, welding heat input to the next low penetration shallow weld thin steel tube wall thickness increases with the number of layers also increased rapidly weld, welding time and labor intensity become larger , simply difficult to play under its welding to the welding speed and high efficiency. Manual arc welding of steel pipe(Stainless Steel Electrode) when the level of different thickness and the channel number in Table 2. The backing welding, thermal welding with the next to the welding, welding and capping fill up the welding of the compound with the next two to welding technology can play the advantages of welding methods to achieve quality and efficient results. Under the semi-automatic gas shielded welding technology to the pipeline construction is not used before, a large wall thickness under the pipe to use more complex welding
Technologies. If an industrial park works with a steel water pipeline specifications for φ400mm × 14mm, material is Q235-A. Weld backing during welding, heat welding cellulosic electrodes J425G, fill welding and capping the ordinary J422 (E4303) electrode, the weld bead layer welded by a single click to the desired level was reduced to 7 to8 4 to 5 layers, welding time can be shortened 30min, greatly improving production efficiency.
Microsoft Access is a relational structure using the database management system, and it has a general database management system functions, and thus has easy to use features, making it the most appropriate database entry software.Compared to other large-scale database management systems, including Microsoft SQL Server, Oracle, Sybase, Informix, etc., Microsoft Access provides an affordable solution.It is not only in price much cheaper than other systems, and the "small but complete", you think of all the functions it has, therefore very suitable for the development of small database applications. In the Access database contains database objects 7, respectively, "table", "query", "form", "Report," "page", "macro", "module", the following will introduce the 7 database objectsAccess database in the role.
The data table is a collection of specific topics, such as "products" table contains all the product records and the properties of each product description.In addition to browsing table data, in the Access table "set juice view", you can either create an entire table from scratch, you can also add, delete or custom fields already in the table.
Enquiries can follow different ways to view, change, and analyze data.The basis for the SQL query command, which is used to query data in relational database manipulation language.Through which to combine several tables, and according to specific criteria to identify relevant data.
Form in the Access database is a database object, mainly used to input or display data in the database.Access provides a function of the form, the use of a convenient window operation interface design, so not familiar with Access, users can easily get started.
Each form is a user interface, which contains graphic objects called controls, forms and records can be established between the source connection.Controls include text boxes, check boxes, command buttons.According to different data types, you can use the appropriate controls for user input.The establishment of a form built by Access Form Wizard or manually to complete.
Print format statements is an effective way to display the data.On the report because the user can control the size and appearance of everything, so it can be displayed in accordance with the required information to view.
Page is active on the Internet Web pages.Use the page very similar to the use of a form, you can view, enter, edit and delete data in the database, even in the Internet or Intranet can also update or view data.
Macro is used to automatically perform an action or set of actions of the collection.Such as opening windows or print the report off the macro command.Macros can perform common tasks for you automatically.Macro is a series of macro structure, can also be a macro group.
Module is essentially a statement, statements, and a collection of processes, they are as - a named unit stored together on the Microsoft Visual Basic code organization.Module is the process of Visual Basic statements and stored as a unit set.Module can be divided into two basic types: class module with the standard module.
Second, the overall design concept
2.1 Characteristics of knowledge-based classification of welding 
Materials, shapes or parts connected parts or machine parts in the way of a mechanical connection, physical and chemical connections and metallurgical connection (welding) categories.These connections forming technology in machinery manufacturing, construction, vehicles, petrochemical, nuclear, aerospace and a variety of advanced science and technology play an active role.
Mechanical connection refers to screws, bolts and rivets and other fasteners to connect the two separate sections or parts or components into a complex part of the process.Physical and chemical connection is glue or solder through capillary action, molecular diffusion and chemical reaction between the role of the surface connected to two separate joint process can not be removed, usually a pointer welding, sealing and bonding three categories.Metallurgical connection is welded by heat or pressure (or both) to separate the two metal atoms to the surface of the lattice distance, and the formation of metallic bonds to obtain joint process can not be removed.
Metallurgical connection (welding) is currently the most widely material connection method.It has the following advantages: savings in materials, reduce the structural weight; joint sealing, and can withstand high pressure; processing and assembly process is simple, can shorten the processing cycle; easy to implement mechanization and automation of production and improve productivity and product quality.However, welding is a process of uneven heating and cooling, welding parts welding stress and deformation will have, therefore, must take certain measures to prevent the process.
Metallurgical metal connections (welding) classified as follows:
Artifacts described in this article in the joints after welding is not survived is called the integrity of welding defects, mainly cracks, incomplete penetration, slag, weld appearance of pores and defects.These defects will reduce the weld cross section, reduce the carrying capacity; stress concentration, causing cracks and reduce the fatigue strength, easy to cause component rupture which led to brittle fracture.
2.3 Selection of methods of Welding
Forming method of welding should be considered the choice of materials, welding, weldment thickness, weld length, production volume, quality and other factors, combined with the characteristics of various welding methods and applications to determine.The basic principle is: the premise of guaranteeing quality of products, the preferred methods commonly used in welding; production volume is large, consider increasing productivity and reducing costs.
2.3 The choice of welding parameters
Welding parameters including welding joint type, thickness, wire diameter, welding current, arc voltage, wire feed speed, welding speed.Choice of different methods of welding process parameters are different.
2.4 The establishment of the corresponding module 
According to the most common welding production process, to the design of the database system is divided into three main modules, namely, welding defects and cause analysis module, the choice of modules forming method of welding, welding process parameter selection module.As shown below.
Third, the establishment of a database
3.1 Create Database 
Database is the basis for data processing, which not only holds all static data, but also for dynamic data processing has brought great convenience.A well-designed database, not only makes access to useful information, but also gives database administrators to manage the data extremely easy and fast.Therefore, the database creating a database to be an important step in treatment. Access offers a variety of database templates The templates cover a wide range widely.First create a blank database and then create a table by using the designer.Access data table is stored in a way most relevant information, table data is stored in a classified manner.Parameters of the welding process data in a table in the form of multi-display and large data, type a number, so the data table is created is the first step.
Fourth, Design Summary
Welding technology is an important part of the welding process, welding quality and welding parts manufacturing cost, quality has a significant impact.That is why one of the purposes of this design is that designers can easily and quickly query parameters of the welding process, shorten the design cycle process, the process side by developing fast.Welding method of the system are classified by its process design parameters required to classify, organize and then combined as a whole, on this basis, the faster users can find the data required for the design, can easily referencea lot of welding knowledge and related data.Design eliminates the need to use it while turning a troubled side.
This design allows us to welding technology welding technology, especially designed for a variety of process data with a more comprehensive understanding of and familiarity with, the consolidation of the knowledge learned in practical applications there is a certain increase.The importance of teamwork is what I get in this important design knowledge, a good design requires many people to collaboration and cooperation, a person is difficult to accomplish great things alone, team staff should keep in mind for each design.Another big achievement is learned outside the profession did not involve a database of knowledge, such as Access, Visual Basic applications are expanding our knowledge, the use of computers can help us to better and faster to complete the design for computer technologyThe study should also be one way forward.This design also allows us to deeply understand the application of computers in the field of welding expanding the scope, making the welding broke many of the traditional restrictions on the design and manufacturing technology, a bright future.Welding technology and the close integration of computer technology represents the future direction of the field.
As our knowledge and experience of its lack of reserves, but only started early in the design study.So many features not able to understand and learn, and many programming languages do not use well, resulting in the system design is relatively simple, can only implement some basic functionality.In addition, we also lack practical work experience, so for die design in the end the actual production of data also need to check what some vague, the process of establishing a database there must be imperfections.Even so, I believe we have done is very promising, through its major improvements, such as increasing the number of powerful modules to achieve a more complex queries.Can also increase the existing database, the contents of the welding process to cover broader data to meet the broader needs.