Teaching handout of basic knowledge for thermal po

Teaching handouts of basic general knowledge for arc welding students

(I) knowledge points

1. Be familiar with relevant welding engineering terms and understand the basic knowledge of common welding materials

2. Preliminarily acquire the basic process knowledge of welding through training

3. Master the basic concepts of welding production process, understand the practical knowledge of welding technology, and lay a foundation for future courses

4. Understand the safety technical knowledge of welding and achieve safety training

(II) ability training points

by welding simple workpieces, cultivate students' welding process analysis ability and hands-on operation ability, and lay a solid foundation for engaging in production technology work in the future

(III) quality training points

1. Through training, students can establish a scientific attitude of integrating economic views, quality views and theory with practice

2. Educate students in ideological style, make them abide by discipline in production and labor, and take good care of state property

II. Key points of the outline, learning difficulties and solutions

(I) key points of the outline

1. The basic wrong interface of welding may damage the equipment; Concept, type, structure, performance, characteristics and application method of manual arc welding machine

2. Composition of welding arc and solution pool

3. Composition and function of welding rod, type, brand, meaning and application of commonly used structural welding rod

4. Wiring method of manual arc welding machine

5. Current regulation of manual arc welding, arc striking and extinguishing, strip transportation and flat surfacing welding methods

6. Common forms of welded joints, grooves and spatial positions of welding

7. Safety technology of manual arc welding

(II) learning difficulties

1, composition of welding arc and composition of solution pool

2. Selection of welding specifications; (such as welding current, welding speed, arc length, electrode angle)

3. Common welding defects and their causes

(III) solutions to difficulties

1. Explain some basic concepts carefully and emphatically

2. Explain the situations that are not easy to observe and pay attention by drawing some schematic diagrams

3. Organically combine theory and practice through practical operation

III. teaching plan

main content of unit teaching form objective plan time notes

1 classroom teaching the significance, application and classification of welding understand 10 minutes examples

2 classroom teaching manual arc welding familiar with and master 60 minutes drawing simple demonstration

3 classroom teaching the joint form of weld, Spatial position and groove understanding 15 minute drawing

4 classroom teaching common welding defects and their causes understanding 15 minute drawing

5 classroom teaching safety technology of arc welding understanding 10 minute examples

6 operation demonstration current regulation of manual arc welding, arc striking, arc extinguishing, strip transportation Welding methods such as flat welding and surfacing are familiar with and master the actual operation for 20 minutes

7 students' operation is the same as the same as that of the same day examination

design instructions

1. First, teach the basic concept, application and classification of welding, so that students can understand what welding is, the classification method and specific form of welding. It is pointed out that manual arc welding is the most widely used welding method at present, and it is also the basis of other kinds of welding methods

2. Focus on the characteristics of manual arc welding, equipment and tools, composition and classification of welding rods, wiring methods of welding machines, arc ignition, strip transportation and strip transportation methods

3. Theoretically understand some basic knowledge of manual arc welding, and also need to master how to choose common welding specifications such as electrode diameter, welding current, arc voltage, electrode angle and welding speed

4. Make students know the basic knowledge of weld through drawing. (such as joint form, spatial position, groove and defects)

5. Safety is the first priority in what work to do. Through teaching safety technology, students can understand that if they do not comply with the safety operation procedures, they may cause electric shock, burns, fire, explosion, poisoning and other accidents

6. The above five units are the basic theoretical knowledge taught in the classroom. The actual operation starts from unit 6. Before the operation, some precautions during the operation should be explained clearly, such as safety, saving the use of welding rods, weldments, organizational discipline, etc., and the demonstration operation can be carried out later. During the demonstration operation, students should pay attention to observing how the instructor selects the welding specification during welding. (for example, welding current and such psychology have been bothering him for "three degrees", etc.)

7. When students operate, they should first imitate the welding action of the instructor, and use their brains to find out their own shortcomings in welding and correct them next time

IV. material preparation (in groups)

1. Equipment: 1 set of BX welding machine

2. Tools: one welding tongs, two masks, and one planer hammer

3. Material: E4303 type Ф 3.2 welding electrode 2kg, two pieces of low carbon steel plate, specification 180 × one hundred and twenty × 10。

4. Teaching aids: standard teaching materials, chalk, wall charts, etc

v. teaching process

unit manual arc welding (theoretical part)

Introduction: manual arc welding is the basis of other welding methods, and we need to carry out practical operation in our three-day internship, so it is the focus of this teaching program. The schedule is about 2 hours (mainly classroom teaching)

unit 1. Significance, application and classification of welding

welding is a processing method that connects two pieces of metal by heating or pressurizing, or heating and pressurizing, with or without filler metal

welding is an indispensable advanced manufacturing technology in modern industrial production. With the development of science and technology, welding technology has attracted more and more attention from all walks of life and is widely used in institutions, metallurgy, electric power, boilers and pressure vessels. Production departments of construction, bridges, ships, automobiles, electronics, aerospace, military industry and military equipment

there are many classification methods of welding. If the metal is in different states during the welding process, the welding methods can be divided into three categories: fusion welding, pressure welding and brazing, and each category includes many welding methods

fusion welding is a welding method that heats the weldment joint to the melting state without pressure during the welding process. Such as gas welding, manual arc welding, etc

pressure welding is a method of applying pressure (heated or unheated) to the weldment to complete the welding during the welding process. Such as resistance welding, friction welding, etc

brazing is a method of connecting Weldments by using the materials belonging to the shear strength testing equipment of the gold bolt tray that are lower than the melting point of the base metal as brazing filler metal in the welding process, heating the weldments and brazing filler metals to a temperature higher than but lower than the melting point of the base metal, wetting the base metal with liquid brazing filler metal, filling the joint gap and diffusing with the base metal. Such as soft soldering (heating temperature below 450 degrees? Tin soldering) hard soldering (heating and then remote auxiliary temperature above 450 degrees? Brazing)

among them, manual arc welding is the most widely used at present, and it is also the basis of other kinds of welding methods

unit 2. Manual arc welding

(I) characteristics of arc welding

manual arc welding is an electric arc welding method that uses manually operated electrodes for welding, which is referred to as manual arc welding for short. Its features:

1, simple equipment

2. Flexible and convenient operation

3. Capable of all position welding, suitable for welding a variety of materials

4. The disadvantage is low production efficiency and high labor intensity

what is arc? The strong and lasting discharge phenomenon in the gas medium between the two electrodes is called arc. When the arc discharges, high temperature is generated on the one hand, and strong light is generated at the same time. Manual arc welding is to use the high temperature generated by the arc to melt the welding rod and weldment, so that the two separated metals are fused together, so as to obtain a solid joint

manual arc welding uses welding rod and weldment as two electrodes, and the weld metal is called weldment or base metal. During welding, the weldment is partially melted due to the high temperature and blowing force of the arc. An oval pit filled with liquid metal is formed on the welded metal, which is called a molten pool. With the movement of the welding rod, the weld pool is formed after cooling and solidification. A layer of slag shell covering the weld surface is called slag. The distance from the melting end of the electrode to the surface of the molten pool is called the arc length. The distance from the surface of the weldment to the bottom of the weld pool is called the penetration depth. (end)