Another method is to use a pipe wrench to clamp the valve stem, and with external signal pressure, rotate the valve stem forward and backward to allow the valve core to pass through the jam. If not, i

Another method is to use a pipe wrench to clamp the valve stem, and with external signal pressure, rotate the valve stem forward and backward to allow the valve core to pass through the jam. If not, increase the air source pressure, increase the driving power, and move it up and down several times to solve the problem. If it still doesn't work, it needs to be disassembled. There is also leakage, which is divided into:

1. Leakage within the valve, and the length of the valve stem is inappropriate. When opening the valve with air, the valve stem is too long and the upward (or downward) distance of the valve stem is not enough, resulting in a gap between the valve core and the valve seat, which cannot fully contact, resulting in lax closing and internal leakage. Similarly, the valve stem of the air shut-off valve is too short, resulting in a gap between the valve core and the valve seat, which cannot fully contact, resulting in lax closing and internal leakage.

Solution: The regulating valve stem should be shortened (or extended) to make the regulating valve length appropriate so that it will no longer leak internally.

2. Packing leakage. After the packing is loaded into the stuffing box, axial pressure is applied to it through the gland. Due to the plasticity of the filler, it generates radial force and is in close contact with the valve stem, but this contact is not very uniform. Some parts are in loose contact, some parts are in tight contact, and some parts are even not in contact. During the use of the regulating valve, there is relative movement between the valve stem and the packing. This movement is called axial movement. During use, with the influence of high temperature, high pressure and highly permeable fluid media, the regulating valve stuffing box is also the site where leaks occur more often. The main cause of filler leakage is interface leakage, and leakage may also occur for textile fillers (pressure medium leaks outward along the tiny gaps between filler fibers). Interface leakage between the valve stem and the packing is caused by the gradual attenuation of the contact pressure of the packing, the aging of the packing itself, etc. At this time, the pressure medium will leak outward along the contact gap between the packing and the valve stem.

Solution: In order to facilitate the loading of the packing, chamfer the top of the stuffing box, and place a metal protection ring with a small gap that is resistant to erosion at the bottom of the stuffing box (the contact surface with the packing cannot be sloped) , to prevent the filler from being pushed out by the medium pressure. The metal surfaces of all parts of the stuffing box that are in contact with the packing must be finely machined to improve surface finish and reduce packing wear. Flexible graphite is selected as the filler because it has good air tightness, low friction, little change after long-term use, little burning loss due to wear, easy maintenance, and no change in friction after the gland bolts are re-tightened, and has good pressure resistance and heat resistance. It has good performance and is not corroded by the internal medium. The metal in contact with the inside of the valve stem and stuffing box does not suffer from pitting or corrosion. In this way, the seal of the valve stem stuffing box is effectively protected and the reliability and long-term sealing of the packing are ensured.

3. The valve core and valve seat are deformed and leaking. The main reason for core and valve seat leakage is that casting or forging defects during the production process of the regulating valve can lead to enhanced corrosion. The passage of corrosive media and the erosion of fluid media can also cause leakage of the regulating valve. Corrosion mainly exists in the form of erosion or cavitation. When corrosive media passes through the regulating valve, it will cause erosion and impact on the materials of the valve core and valve seat, causing the valve core and valve seat to become oval or other shapes. As time goes by, the valve core and valve seat will not be damaged. Matching, there is a gap, leakage will occur if the seal is not tight.

Solution: The key is to control the selection and quality of the materials of the valve core and valve seat. Choose corrosion-resistant materials and resolutely eliminate products with defects such as pitting and trachoma. If the deformation of the valve core and valve seat is not too serious, they can be ground with fine sandpaper to eliminate traces and improve the sealing smoothness to improve the sealing performance. If the damage is serious, the valve should be replaced with a new one.

The other is oscillation. The reason for the oscillation is insufficient spring stiffness of the regulating valve. The output signal of the regulating valve is unstable and rapid changes can easily cause the regulating valve to oscillate. It is also said that the frequency of the valve selection is the same as the system frequency or the pipe or base vibrates violently, causing the regulating valve to vibrate accordingly. If the valve is improperly selected, there will be sharp changes in flow resistance, flow rate, and pressure when the regulating valve operates at a small opening. When the valve stiffness is exceeded, the stability will become worse, and oscillation will occur in severe cases.

Solution: Since there are many reasons for oscillation, specific problems must be analyzed in detail. For slight vibrations, stiffness can be increased to eliminate them. If a large stiffness spring is selected, use a piston actuator structure instead.

If the pipeline and base vibrate violently, add supports to eliminate vibration interference; if the frequency of the valve selection is the same as the system frequency, replace the valve with a different structure; if the oscillation is caused by working at a small opening, the selection is inappropriate and the flow capacity C value should be large. It is necessary to reselect a model with a smaller flow capacity C value or use split-range control or a master-sub valve to overcome the small opening of the regulating valve.

It is also caused by valve positioner failure, which is further divided into

1. Ordinary positioners work on the principle of mechanical force balance, that is, nozzle baffle technology. The main problems are as follows: Fault type:

1) Because it works on the mechanical force balance principle, it has many movable parts and is easily affected by temperature and vibration, causing fluctuations in the regulating valve;

2 ) uses nozzle baffle technology. Since the nozzle hole is very small, it is easily blocked by dust or unclean air source, causing the positioner to not work properly;

3) Using the balance principle of force, the elasticity of the spring The coefficient changes in harsh conditions, causing nonlinearity of the control valve and resulting in a decrease in control quality.

2. The intelligent locator is composed of a microprocessor (CPU), A/D, D/A converter and other components. Its working principle is completely different from that of ordinary locators. The comparison between the given value and the actual value is purely an electric signal and no longer a force balance. The disadvantages of force balancing of conventional positioners can therefore be overcome. But when used in emergency parking lots, such as emergency shut-off valves, emergency vent valves, etc. These valves are required to remain stationary in a certain position and only need to operate reliably when an emergency occurs. Staying in a certain position for a long time can easily cause the electrical converter to lose control and cause a dangerous situation of small signal failure. In addition, because the position sensing potentiometer used for valves works on-site, the resistance value is prone to change, causing dangerous situations such as small signal inactivity and large signal fully open. Therefore, to ensure the reliability and availability of smart locators, they must be tested frequently.

By analyzing the causes of control valve failures and taking appropriate treatment and improvement measures, the utilization rate of the control valve will be greatly improved, the instrument failure rate will be reduced, and the production efficiency and economic benefits of the process and energy will be improved. The reduction of consumption plays an important role in effectively improving the quality of the regulating system, thereby ensuring long-term operation of the production device.

After a period of time, I have been able to work freely. Now I am full of confidence in my future work. I believe that I will do something great.

The above is my summary of the internship during this period. I hope the teacher will criticize and correct me.

Workshop assembly line production internship experience (2)

I feel very honored to have the opportunity to intern in the factory this time. Although it only lasted for a week, during this period, I gained a perceptual understanding of some common theoretical things and felt that I benefited a lot.

The following is some summary and experience during my internship. I hope it can be used as a reference when carrying out my own work and communicating with customers in the future.

1. Overall scale level of the factory

Yatai (Dongguan) Wood Industry is located in Dalang Town, Dongguan, covering an area of ??24,600 square meters and more than 600 employees. With a manufacturing history of more than ten years, it has developed into a professional wood products expert and is well-known in the developed manufacturing area of ??Dongguan.

When you walk into the factory, you will see a clean and tidy environment and well-ordered work procedures. Although it is a domestic manufacturer, when you go to the workshop and see those advanced assembly lines and those skilled technical levels, you will completely feel the modern management. As a manufacturer of wooden products, some problems such as the flying of sawdust, the noise of machines, and the smell of glue and paint are inevitable, but the factory has minimized these as much as possible. Walking in the workshop, the serious problems faced by most wooden manufacturers do not seem to be a big problem in our factory. On the contrary, it is the management and efficiency that attract most visitors.

The factory has its own schedule and will strictly abide by it. Even during the lunch break, each worker will keep his or her own area in order. This kind of conscious organization is one of the reasons why the factory can stay clean.

When it comes to dining, the factory also has its own characteristics. That is, everyone from senior managers to ordinary workers eat the same meals without any specialization.

2. Learning process

The following points are the main knowledge I learned during my internship in the factory and some insights I gained based on my work needs.

(1) Selection of wood

The most commonly used wood in factories is mahogany (African rosewood), maple (USA), and walnut. Most of them are imported from abroad, which is why our company's quotation is higher than the price of the same domestic manufacturer - it is "you get what you pay for".

MDF board is also one of the commonly used materials. Many of our products can also be veneered with MDF to achieve the effect of imitating solid wood. It can be recommended for some customers who want to save costs.

These conventional woods have a certain amount of stock in the warehouse, and other woods are also in stock. However, it is generally recommended to use conventional woods as much as possible (unless the quantity of products ordered by the customer is large enough for the factory to purchase additional wood) Expensive wood), which will be helpful for the factory's processing technology, production cycle, growth cost, etc.

(2) Processing

The machines used in the factory are relatively advanced and generally operate automatically, such as CNC machines, universal circular saw machines, vertical axis machines, etc. . Therefore, as long as the operation is done properly and the personnel arrangement is reasonable, it can generally produce high efficiency (generally speaking, skilled labor is required).

Although the factory can produce most wooden products, in the future communication process with customers, while trying to meet customer requirements, we must also try to consider the factory's perspective. For example, you can recommend to customers some samples that have the same appearance, but simple methods and clear structures. This can not only reduce costs for the factory, but also improve efficiency.

(3) Painting processing

After the white body processing is completed, it should be transferred to the painting workshop as soon as possible, otherwise the wood will deform. The process of spray painting is: coloring (giving the product a base color) - primer - topcoat. The process from spraying primer to topcoat also requires a frosting process.

Primer can be divided into NC paint and PU paint. The primer often used in factories is NC paint, because the cost of PU paint is higher than that of NC, and the environment required for spraying PU paint is also relatively high, and a dust-free room is required. Customers are generally recommended to use NC paint.

The painting processing time is generally about two days. However, although it does not take long, the factory will arrange every link in place to complete an order. Therefore, when confirming an order with a customer, be sure to confirm every requirement completely. Some customers have not decided on the paint after finishing the white body. If they are left aside, not only will the product be easily deformed, but it will also affect the progress of the order and bring unnecessary trouble to the factory.

Experience of workshop assembly line production internship (3)

1. Internship purpose

Production internship is an important practical teaching link that combines teaching with production practice. During the production internship process, the school also aims to cultivate students' abilities and methods to observe and solve problems and learn from actual production practices. Cultivate our spirit of unity and cooperation and firmly establish our group consciousness, that is, individual wisdom can only play its maximum role when integrated into the collective.

Through this production internship, I learned the technical management knowledge of electrical equipment operation, the manufacturing process knowledge of electrical equipment and practical knowledge that cannot be learned in school. While learning from the workers, we cultivated our fine style of hard work and simplicity. In production practice, we realized that strict observance of disciplines, unified organization and coordination are the needs of modern large-scale production, and are also necessary for our contemporary college students, thus further improving our organizational concepts.

Through production internships, it plays an important role in consolidating and deepening the theoretical knowledge we have learned, cultivating our ability to work independently and strengthening our labor perspective.

2. Internship tasks

1. Have a more comprehensive and comprehensive understanding of the company’s production process and production technology; have a more in-depth and detailed understanding of the company’s production equipment, processes, products, etc. Knowledge; understand the knowledge and operation process of the company's organizational management, corporate culture, product development and sales, etc.

2. In internship positions that are relatively professional, strive to closely integrate the theoretical knowledge learned with practical work, and be able to apply it flexibly, so that one's professional knowledge, professional skills and engineering practice abilities are all improved. A comprehensive improvement.

3. Accumulate a certain amount of work experience and social experience, have significant improvements in professional ethics, professional quality, labor concepts, work ability, etc., and gradually master the role transformation from students to employees, preparing for graduation Lay a good foundation for future employment and improve employment competitiveness.

3. Basic requirements for internship:

1. Students must abide by various rules and regulations of the company and corresponding labor disciplines in the internship company, and are not allowed to ask for leave without reason or leave their positions without permission. If you need to take leave or change the internship company under special circumstances, you must obtain the consent of the internship company and the instructor.

2. Students must strictly abide by the job operating procedures and safety management system during the internship period to strictly prevent work liability accidents and personal safety accidents.

3. You must abide by the law and model the social ethics of citizens, and are not allowed to engage in activities that are not allowed by laws and regulations, factory rules, and school rules.

4. Work hard, actively complete the tasks assigned by the internship unit, learn with an open mind, proactively and sincerely seek advice from master workers, engineering technicians and business managers, and study hard.

5. You should communicate more with the instructor and get timely guidance from the instructor.

IV. Internship content

(1) Safety education 1. Purpose of safety education learning: 2. Occurrence of accidents and their prevention: 1. Factors in accidents: human factors—— Factors of unsafe behavior - unsafe factors 2. Factors considered to cause accidents 1). Management factors; 2) Violations: a. Wrong operation b. Illegal operation c. Reckless behavior 3) Poor safety responsibility (quality) . 3. Main safety precautions when entering the factory 1. Fire and explosion protection 2. Dust and poison protection 3. Prevent burns and scalds 4. Prevent electric shock 5. Prevent mechanical injuries 6. Prevent falling from heights 7. Prevent vehicle injuries 8. Prevent injuries from lifting machinery 9 .Prevent objects from being hit. 10. Drinking is not allowed before class. 4. Instructions for working inside the equipment: 1. Work inside various storage tanks, tankers, towers and other equipment as well as basements, shafts, pits, sewers or other closed places is considered work inside the equipment. 2. There is no communication between the equipment and the outside world. Connected pipes, holes, etc. should be effectively isolated from the outside world. 3. Before entering the equipment for work, the equipment must be cleaned and replaced. 4. Measures should be taken to maintain good air in the equipment. 5. Within 30 minutes before operation, the equipment must be cleaned and replaced. The gas in the equipment should be sampled and analyzed, and the sampling should be representative. 6. When working in equipment that cannot meet the cleaning and replacement requirements, corresponding protective measures must be taken. 7. Because the lighting is good when working in the container, the lighting electricity consumption should be less than or equal to 36v explosion-proof lamps 8. For multiple types of work and multi-level cross-working operations, measures should be taken to avoid injuries to each other, and safety ladders or safety platforms should be set up. When necessary, guardians should use safety ropes to tie the workers to the construction 9. Inside the equipment The operation must be supervised by a dedicated person, and there should be rescue measures and effective protection methods. 10. The construction unit is responsible for handling the "Safe Operation Certificate in Equipment". The person in charge or technician of the project should fill in the operation certificate, and the maintenance operation unit should fill it out. various contents.

(2) A brief introduction to the characteristics of assembly line production: As the name suggests, the assembly line is the work of a group. Each employee must do his or her job seriously, because each process of the entire assembly line is closely related. The product produced by the entire assembly line may be scrap due to an error in a certain process.

(3) Learn and understand the structural types, structural types and functions of electronic devices.

(4) Learn and understand the production organization and management of the factory workshop, production processes, etc.

(5) During the internship, socialism and patriotism education, love of labor and discipline education, and safety education were carried out.

5. Internship Process

1. Safety Education At the beginning of the internship, the school organized us to go to the company to have professionals give us safety education, explaining the importance of safety issues and the The various dangers and potential dangers encountered during the internship, etc.

2. Workshop internship Our internship in the workshop is the main way of production internship. We conducted internships in the designated workshops according to the internship plan. Through observation, analysis and calculation, and consultation with workshop workers and technicians, we successfully completed the prescribed internship content.

3. The combination of theory and practice. In order to conduct a more in-depth workshop internship, during the internship process, we combined the book knowledge we learned with the internship requirements, and perfectly combined theory and practice. , and also motivates us to continue learning and research.

4. Internship Diary During the internship, we recorded our daily work, observation and research results, collected information and charts, and the content of the reports we listened to in the internship diary. Accept inspection and correction from teachers at any time.

5. Other activities While completing the content of our internship business, we often use on-site learning opportunities to carry out internship activities with the society, workers and engineering and technical personnel. In his spare time, he also organized ball games, shuttlecock playing, table tennis and other activities, and strengthened ideological and political education activities, etc.

6. Internship Insights Production internship is an important practical teaching link arranged by our college to cultivate high-quality engineering and technical talents. It is an important way to combine school teaching with production practice and connect theory with practice. . The purpose is to train and cultivate our professional knowledge and talent quality through internships, so as to lay a good foundation for us to work as soon as possible after graduation and become the backbone of the business.

Through production internships, we understand and master workshop management, production technology and process processes; the main tooling equipment used; technical data for product production; production organization and management, etc., and deepen our work on electronic devices Understanding of basic theories such as principles, design, and experiments. It enables us to understand and master the work and management of the factory floor. This will lay a good foundation for further learning professional courses and engaging in research and design in this area.

During this production internship, not only did we deepen our understanding of the knowledge we learned, but more importantly, we corrected our labor views and improved our ability to work independently.

In general, I am very enthusiastic about this course.

First, I have been interested in this kind of small production since I was a child. I didn’t know how to weld at that time, but I liked to disassemble and assemble things. But in this way, the thing was useless. Now the factory electronics internship class is about learning how to "put things back". Every time I complete a step, I am as happy as a child and have a sense of "achievement".

Second, electrical and electronic internship is characterized by students’ hands-on skills, mastering certain operating skills, and hands-on design, production, assembly and debugging. It organically combines basic skills training, basic process knowledge and innovation enlightenment to cultivate our practical ability and innovative spirit. As a college student in the information age, as a highly skilled talent cultivated by the country, it is not enough to just operate the mouse. Basic hands-on ability is the foundation and necessary condition for all work and creation.

After one month of study, I feel that I have gained something in the following aspects:

1. I have a preliminary systematic understanding of the theory of electronic technology. We learned the skills of testing ordinary components and circuit components, the design, production and process flow of printed circuit board diagrams, the working principles of hair dryers, flashlights, and nose hair machines and the functions of their components, etc. This knowledge is not only effective in the classroom, but also has great guiding significance for the future study of electronic technology courses. It has practical significance in daily life.

2. It is a great exercise for your hands-on ability.

Practice brings true knowledge. Throughout ancient and modern times, all inventions and creations have been tested in practice. Without sufficient hands-on ability, it is impossible to achieve success in future scientific research, especially experimental research. During the internship, I developed my hands-on skills and improved my ability to solve problems. For example, when assembling and testing flashlights, I found several short-circuited pads and repaired them.