Industrial applications of spring safety valves

Industrial applications of spring safety valves:

With the rapid development of industrialization, the company’s own business philosophy has also undergone significant changes. In the past, people always said that companies are pursuing economic benefits, but now, with the mandatory implementation of the national safety production policy, they are also seeking Under the premise of maximizing benefits, the concept of “safe production” has begun to penetrate into the hearts of business owners. Therefore, new types of safety equipment that continue to appear have been promoted and used in the workshops and production chains of various types of chemical plants. Among them, the spring type The safety valve is favored by factories for its high safety and stability. So what is the reason for it to attract attention?

The spring-loaded safety valve refers to the sealing parts such as the valve flap or plunger relying on the elastic pressure of the spring. Once the pressure of the pressure vessel is abnormal, the high pressure generated will overcome the spring pressure of the safety valve, so the locking device is opened and formed A pressure relief channel is used to release the high pressure to avoid harmful accidents. As we all know, many chemical companies need high temperature and high pressure for chemical reactions in production. If these media are not well controlled, then once a safety accident occurs , The harm caused is not only the production loss of the enterprise, but also the life safety of the operators. In order to ensure foolproof, the state stipulates that high-pressure production enterprises must install spring-type safety valves to eliminate production hazards.

Of course, the powerful safety performance of high-pressure safety valves is inseparable from their sophisticated production processes. Generally speaking, safety valve manufacturers will make them according to the applicable medium when selecting materials. Cast iron, aluminum alloy, cast steel and stainless steel materials are The best material for the safety valve. In addition, the housing of the safety valve must not have cracks and small holes during the processing process. Do not underestimate this point. The fatal danger is caused by small negligence. Finally, the most important thing is to For testing work, the safety valve that has just been produced must pass a complete set of tests before it can enter the market. The test is to be responsible for consumers and for industrial safety production.

After several generations of development, the application range of safety valves has become wider and wider, and more safety equipment that meets the needs has entered the market. And more and more companies have established their own brands, precisely because the future industrial production must also take into account safety With benefits, the prospect of safety equipment is broad and the market is broad!

Application and failure analysis of spring safety valve

The spring safety valve is a device set up for the exhaust pipe being blocked due to misoperation or uncleaned. The spring safety valve is a device that limits the pressure cooker to exhaust within the safe pressure range and ensures safe use. The structure and performance of the spring are the valve’s The essential.

According to the ratio of the maximum opening height of the valve flap to the diameter of the safety valve flow path, the spring safety valve can be divided into two types: spring micro-open closed high-pressure safety valve and spring full-open safety valve.

A. Spring micro-open closed high pressure safety valve

The opening height of the micro-lift safety valve is less than 1/4 of the diameter of the flow channel, usually 1/40 to 1/20 of the diameter of the flow channel. The action process of the micro-lift safety valve is proportional action and is mainly used in liquid applications. , Sometimes also used in gas occasions with small emissions.

B. Spring full lift safety valve

The opening height of the full-lift safety valve is greater than or equal to 1/4 of the diameter of the flow channel. The discharge area of ​​the full-lift safety valve is the smallest cross-sectional area of ​​the valve seat throat. Its action process is a two-stage action type, which must be aided by one The lift mechanism can be fully opened, and the full lift safety valve is mainly used for gas medium occasions.

C. Open type safety valve

The opening height is between the micro-open type and the full-open type. It can be made into a two-stage action or a proportional action type.

Common failures and elimination methods of spring-type safety valves

(1) The disc does not return to its seat after discharge. This is mainly caused by the spring bending the valve stem, the incorrect installation position of the disc or the jam. It should be reassembled.

(2) Leakage. Under the normal working pressure of the equipment, the leakage between the valve disc and the valve seat sealing surface exceeds the allowable degree. The reasons are: there is dirt between the valve disc and the valve seat sealing surface. A lifting wrench can be used Open the valve several times to flush away the dirt; the sealing surface is damaged. According to the degree of damage, it should be repaired by grinding or grinding after turning; the valve stem is bent, tilted or the lever and fulcrum are deflected, so that the valve core and the valve disc Dislocation. Should be reassembled or replaced; spring elasticity is reduced or loses elasticity. Measures should be taken to replace the spring and readjust the opening pressure.

(3) It does not open when the specified pressure is reached. The cause of this situation is that the constant pressure is inaccurate. The compression of the spring or the position of the weight should be readjusted; the disc and the valve seat are stuck. The safety valve should be manually operated on a regular basis Vent or water discharge test; the lever of the lever-type safety valve is stuck or the heavy hammer is moved. The position of the heavy hammer should be readjusted and the lever can move freely.

(4) The pressure continues to rise after exhaust. This is mainly because the selected safety valve has a small displacement and the safety discharge volume of the equipment, and a suitable safety valve should be selected again; the center line of the valve stem is not correct or the spring is rusted, so that the valve disc cannot be opened. The valve stem should be reassembled or the spring should be replaced if the height should be; if the exhaust pipe is not enough, an exhaust pipe that meets the safe discharge area should be adopted.

(5) The valve flap frequently jumps or vibrates. The main reason is that the spring stiffness is too large. Springs with appropriate stiffness should be used; the adjustment ring is improperly adjusted, so that the return pressure is too high. The position of the adjustment ring should be readjusted; the discharge pipe resistance is too large , Resulting in excessive discharge back pressure. The resistance of the discharge pipeline should be reduced.

(6) The opening is less than the specified pressure. The main reason is that the constant pressure is inaccurate; the spring is aging and the elastic force is reduced. The adjustment screw should be properly tightened or the spring should be replaced.

Introduction to the development potential of special-shaped spring application market

Development potential of special-shaped spring application market:

With the continuous development of my country’s economy, various production fields in my country have also been continuously improved! As an extremely small component, the special-shaped spring is widely used and has great potential in the development of my country’s component market!

A. Special-shaped springs provide springs for the transportation market, including supporting and maintenance parts for automobiles, motorcycles, diesel engines and railways. This is the most important and most promising market for the special-shaped spring industry. The rapid development of the automotive industry is right The spring industry has had an obvious pulling effect and has become the largest customer in the spring industry. With the deepening of the railway system reform, the gradual opening of the market and the implementation of high-speed railway planning, the vehicle shock absorption system is facing upgrading, and the railway line needs to install new types of reduction Vibration and noise reduction components will bring huge business opportunities to the spring industry.

B. In recent years, the domestic market has a strong demand for daily hardware products, which has driven the growth of supporting special-shaped springs. The daily necessities industry and the hardware industry such as lighters, toys, locks, door hinges, fitness equipment, mattresses, sofas, etc. In terms of springs, the demand is the largest, tens of billions of pieces.

C, the demand for special-shaped springs in industrial and mining products. This market covers other industrial sectors except the transportation industry, from textile machinery cradle springs to chemical springs, power station switches, support springs, bulldozer springs, etc.

It is precisely because of the wide range of special-shaped springs that China is paying more and more attention to its development! With its years of production experience, Dongguan Spring Factory has continuously improved the special-shaped springs through production materials and technological innovation, striving to meet the growing number of special-shaped springs market!

With the development of industry, the application of special-shaped springs as basic parts has become more and more extensive, and the requirements for the spatial shape and forming accuracy of special-shaped springs are also continuously improved. To deal with this change, it is suitable for CNC machining of special-shaped springs with complex shapes. Coiling spring equipment is playing an increasingly important role in the production and manufacturing of special-shaped springs. However, due to various conditions, there is a big gap between China and industrially developed countries in the manufacture of special-shaped spring coiling equipment.

It is mainly occupied by imported products. Therefore, the development of advanced special-shaped spring spring coiling equipment with independent intellectual property rights is particularly urgent and necessary to comprehensively improve the level of China’s spring manufacturing industry. On the other hand, as a common product, people The research on its advanced manufacturing methods is often ignored, resulting in relatively weak research on the CNC coiling of special-shaped springs. In fact, due to the characteristics of the special-shaped spring winding and the particularity of the working mode of the winding equipment, the CNC spring equipment is in use The process has defects such as low degree of automation, strong dependence on experience, and inconvenient operation. Therefore, in-depth study of the spring manufacturing process has important theoretical significance and application value.

Special-shaped spring is a kind of spring. It shoulders a kind of tension and pressure. Like ordinary springs, it has its own characteristics and special uses than ordinary springs. One of the heterosexual springs is a miniature compression spring. The effect is very subtle, mainly a compression function, which plays a very important role in the machine. Corresponding to the compression spring is the extension spring. The spring is originally made of special metal materials and special craftsmanship. It is made of a device that can be contracted, so the function of the tension spring also has a great effect on mechanical equipment, mainly to resist external pressure, and use the unique stretching function of the spring to help the machine resist these pressures. Springs may not have been touched in daily life.

They are toy springs. This kind of springs are widely used in toys, such as toy pistols, toy cars and toy cats and dogs. Toys are currently sold very well in the market, especially Nowadays, parents attach great importance to children, and many parents attach great importance to the development of children’s intelligence, so they develop children’s intelligence on toys. Nowadays, there are many kinds of toys, and they are very popular with consumers, especially children. I like novel toys, and they do have great benefits for intellectual development. But as the author, I want to mention a very important thing about the application of special-shaped springs in toys, which is the safety of springs, because springs are very effective. It is subtle, but its safety factor is not very high.It will cause a certain degree of damage to children during the rebound, especially if the spring hurts the eyes, it will cause a lifetime of regret.

Performance and application of compression spring

Springs are generally of equal pitch. The shapes of compression springs are: cylindrical, conical, convex and concave, and a small amount of non-circular shapes. There is a certain gap between the coils of the compression spring. The spring shrinks and deforms under external load and stores deformation energy.

Compression Springs provide resistance to external load pressure. Compression springs are generally coiled and solid

fixed wire diameter. The compression spring uses multiple open coils to provide resistance to the external load (such as gravity pressing the wheel or the body pressing on the mattress).

That is, they push back to resist external pressure.

Compression spring is suitable for medical breathing equipment, medical mobile equipment, hand tools, home care equipment, shock absorption, engine valve spring.

What are the characteristics of coil springs

Due to the structural characteristics of the cylindrical spiral spring, within the elastic deformation range of the material, the relationship between the spring load “P” and the deformation amount “F” is not completely linear. As the deformation increases, the helix angle also increases. , The deviation of load and deformation from linearity is also large, but in general, the relationship between load and deformation is basically linear within the working deformation range of the spring, and the deviation from linearity is generally 1% to 3%.

The metal protective layer of the spring

There are many types of metal protective layers for springs. As far as springs are concerned, gold plating is generally used to obtain the metal protective layer. The plating protective layer can not only protect against corrosion, but also improve the appearance of the spring. Some electroplated metals can also improve the spring Work performance, such as improving surface hardness, increasing wear resistance, improving thermal stability, preventing ray corrosion, etc. However, if it is purely for spring corrosion, generally electrogalvanized layer and electroplated cadmium layer should be used.

Zinc is relatively stable in dry air, hardly changes, and is not easy to change color. In humid air, a white film of zinc oxide or carbon zinc carbonate is formed. This dense film can prevent further corrosion. Therefore, plating The zinc layer is used as the anti-corrosion protective layer of the spring under general atmospheric conditions. Any spring that is in contact with sulfuric acid, hydrochloric acid, caustic soda and other solutions, and works in humid air with an atmosphere of sulfur trioxide, etc., should not be coated with zinc. Generally speaking. After the galvanized layer is passivated, passivation can improve the protective performance of the coating and increase the appearance of the surface.

In oceanic or high-temperature atmospheres, springs in contact with seawater, and springs used in hot water at 70°C, cadmium is relatively stable and has strong corrosion resistance. Cadmium coatings are brighter, more beautiful, softer, and more plastic than zinc coatings. Zinc is good, and the coating has low hydrogen embrittlement. It is most suitable for springs as a protective layer. However, cadmium is rare, expensive, and cadmium salt is highly toxic, which is very harmful to the environment. Therefore, it is restricted in use. Therefore, most of them are only used in aviation, The springs used in the navigation and electronics industries use cadmium plating as a protective layer.

In order to improve the corrosion resistance of the cadmium coating, passivation treatment can be performed after plating. The thickness of the zinc and cadmium coating determines the level of protection. The thickness should generally be selected according to the working environment during use. The hardness of the zinc coating is recommended to be Select within the range of 6~24μm; the thickness of the cadmium plating layer is recommended to be selected within the range of 6~12μm.

The zinc and cadmium plating of the spring is carried out in the cyanide electrolyte. During the electroplating process, in addition to the zinc or cadmium plating, a part of the reduced hydrogen penetrates into the crystal lattice of the plating layer and the base metal, causing The internal stress makes the coating and spring on the spring brittle, also called hydrogen embrittlement. Because the strength of the spring material is high, and the deformation of the spring is large when it is formed, it is particularly sensitive to hydrogen embrittlement, if it is not removed in time , Often cause the spring to break. In order to eliminate some of the defects generated in the electroplating process, improve the physical and chemical properties of the spring, extend the service life of the spring, and improve the corrosion resistance of the coating, post-plating treatment, that is, hydrogen removal treatment, must be carried out. Hydrogen treatment is carried out immediately or within a few hours after electroplating. The electroplated spring is heated at a temperature of 200 to 215 °C for 1 to 2 hours (or more than 2 hours, if the time is too long, it is easy to cause chromium brittleness), The purpose of hydrogen removal can be achieved.

Hydrogen removal is generally carried out in an oven. The effect of hydrogen removal is related to temperature, time, and residence time after electroplating. Generally speaking, high temperature, long heating time, short pause time after plating, and its hydrogen removal effect is good. The spring hydrogen removal temperature can be selected higher.

Metal protective layer, in addition to the above-mentioned zinc plating and cadmium plating, there are also copper plating, chromium plating, nickel plating, tin plating, silver plating, zinc titanium alloy plating, etc.The spring designer can choose the plating layer according to the spring working occasion.

What are the characteristics of the spring industry

China’s spring (excluding leaf springs, the same below) industry is composed of two parts: spring production enterprises and spring production-related enterprises. The former mainly produces springs, and the latter is spring material manufacturing and spring production equipment serving spring production. (Including testing equipment) mainly manufactured.

The two use spring products as a link to form a community with the same interests, participate in industry organizations, and participate in industry activities. As a general-purpose basic component, springs are large in quantity and wide in scope. The application field involves almost all areas of the national economy. Due to the use environment, occasions, and functions Because of the inherent characteristics of the spring itself, the investment in the production of springs is not large, and the entry technology threshold is not high, so many people are attracted to join this industry. There are more than 1,000 enterprises, all over the country.

There are more than 1,000 companies in the spring industry, most of which are small companies. Compared with other industries, the average number of assets and employees of each unit is lower than most other industries. There are about 30,000 employees in the entire industry and sales of 3 billion. Around RMB (excluding leaf springs). Looking at the status quo of the industry, it has the following characteristics:

1. The nature of the enterprise is mainly private enterprise, small enterprises account for the vast majority of the industry, and most enterprises employ less than 100 employees.

2. Enterprises are spread all over the country, but they have obvious geographical characteristics, which are directly proportional to the economic development level of various regions in the country. The eastern region is the region with the most spring enterprises, and Zhejiang has the largest number of enterprises.

3. There is a great disparity in individual differences between enterprises. The technical equipment level and product quality of advanced enterprises are close to the advanced foreign levels, but most of the enterprises are backward in equipment and the product quality level is not high.

4. The industry is generally a labor-intensive industry, and manual operation occupies a major position in the production process of many companies.

5. The level of corporate management is relatively backward, and most private companies implement family management.

6. ​​Fierce competition among enterprises is mainly manifested in price competition, rather than competition in product development and technical quality.

7. The products are mainly processed from drawings, and they rarely participate in the synchronous development of OEMs.

What is the relationship between the extension of the tension spring and the tension

Studying the elongation of the spring: the elongation of the spring is related to the weight of the object hanging by the spring dynamometer, and the length of the spring is related to the hanging object. A spring dynamometer is used to hang a heavy object and a spring does not hang a heavy object. The length is different, and it is in a free state without hanging heavy objects.
The spring will stretch after being hung on an object. The relationship between the length of a spring (cm) and the weight of the hung object (kg) is as follows:

(1) Because the data in the table mainly relates to the length of the spring and the weight of the hanging object, it reflects the relationship between the mass of the hanging object and the length of the spring. The mass of the hanging object is the independent variable; the length of the spring Is the dependent variable;

(2) It can be seen from the table that when the mass of the object is 2kg, the length of the extension spring is 13cm;

(3) According to the data in the table, the length of the spring increases with the weight of the hanging object;

(4) According to the data in the table, when x=0, y=12, and every additional kilogram of weight increases the length by 0.5cm, so y=0.5x+12;

(5) If the mass of the object x=2.5, substituting into the functional analytical formula, it can be solved when x=2.5, y=12+0.5×2.5=13.75cm.

From the above analysis, the spring elongation has a linear relationship with the weight of the object suspended by the spring dynamometer.

Classification of springs and their manufacturing information

Springs can be divided into extension springs, compression springs, torsion springs and bending springs; according to their shapes, they can be divided into disc springs, ring springs, leaf springs, spiral springs, truncated cone scroll springs and torsion bar springs. Common cylindrical springs are due to It is simple to manufacture, and can be made into various types according to the load condition, and the structure is simple, so it is the most widely used.

Generally speaking, the manufacturing materials of springs should have high elastic limit, fatigue limit, impact toughness and good heat treatment performance. Commonly used are carbon spring steel, alloy spring steel, stainless spring steel, copper alloy, nickel alloy and rubber. The manufacturing methods of springs include cold-rolling and hot-rolling methods. Cold-rolling methods are generally used for spring wire diameters less than 8 mm, and hot-rolling methods are used for spring wire diameters greater than 8 mm. Some springs need to be forced or shot blasted after they are made. Treatment can improve the bearing capacity of the spring.

As an important component in the industrial system, springs are used in a large amount and have a wide variety of types. Therefore, the production of springs is primitive hand-made and gradually moves towards automation. Ninety years ago, the spring industry had very few professional springs. With the increasing size of the spring market, professional spring equipment companies have gradually entered our country.

The coil spring is a torsion spring, a spring that accepts torsion deformation, and the working part is also tightly wound into a spiral shape. The end structure of the torsion spring is processed into a torsion arm of various shapes, rather than a hook. Torsion springs are often used for balance in machinery Widely used in industrial production such as institutions, automobiles, machine tools, and electrical appliances.

Tension spring is a helical spring that accepts axial tension. Tension springs are generally made of round cross-section materials. When not under load, the coils of the tension spring are generally tight and there is no gap.

Compression springs are helical springs that receive pressure. Most of the materials used are circular in cross-section, and springs made of rectangular and multi-stranded steel coils are generally equal-pitch compression springs. The shapes are: cylindrical, conical, medium Convex and concave shapes and a small amount of non-circular shapes, etc., there is a certain gap between the coils of the compression spring, and when subjected to an external load, the spring shrinks and deforms and stores the deformation energy. What is a torsion spring? A torsion spring uses the principle of leverage. , By twisting or rotating the elastic material with soft material and greater toughness, it has great mechanical energy.

Hardware springs are classified according to the nature of the force

What are the classification of hardware springs according to the nature of the force:

According to the nature of the force, hardware springs can be divided into tensile hardware springs, compression hardware springs, torsion hardware springs and bending hardware springs; according to their shapes, they can be divided into disc-shaped hardware springs, annular hardware springs, plate hardware springs, spiral hardware springs, and cut-off hardware springs. Cone scroll hardware spring and torsion bar hardware spring, etc.

Ordinary cylindrical hardware springs are the most widely used because they are simple to manufacture and can be made into various types according to the load conditions, with simple structure.

Generally speaking, the manufacturing materials of hardware springs should have high elastic limit, fatigue limit, impact toughness and good heat treatment performance. Commonly used are carbon hardware spring steel, alloy hardware spring steel, stainless hardware spring steel and copper alloy, Nickel alloy and rubber, etc.

The manufacturing methods of hardware springs are cold-rolled and hot-rolled. Hardware spring wires with a diameter of less than 8 mm are generally cold-rolled, and those with a diameter greater than 8 mm are hot-rolled. Some hardware springs need to be forced or sprayed after they are made. Pill treatment can improve the load capacity of the hardware spring.

Compression hardware springs are helical hardware springs that accept downward pressure. Most of the materials used are circular in cross-section, and hardware springs made of rectangular and multi-stranded steel coils are generally equal-pitch compression hardware springs. The shapes are: cylindrical, Conical, convex and concave shapes, and a small amount of non-circular shapes.

There is a certain gap between the ring and the ring of the compression hardware spring. When subjected to an external load, the hardware spring shrinks and deforms and stores the deformation energy. What is a torsion hardware spring? The torsion hardware spring uses the principle of lever, through the softness and toughness of the material The distortion or rotation of the elastic material gives it great mechanical energy.

Tension hardware springs are spiral hardware springs that accept axial tension. Tension hardware springs are generally made of round cross-section materials. When not under load, the coils of the tension hardware springs are generally tight and there is no gap.

What are the principles of spring selection

What are the principles of spring selection:

The principle of spring selection is: first to meet the functional requirements, then strength requirements, and finally to consider economics.

Carbon spring steel is a widely used and the largest amount of steel in spring steel. Steel contains 0.60% to 0.90% carbon and 0.3% to 1.20% manganese, no longer add other alloy elements, the cost of use is relatively low.

Carbon spring wire by proper processing or heat treatment, can obtain a high tensile strength, adequate toughness and good fatigue life.

However, the clamofability of carbon wire is low, anti-relaxation and corrosion resistance is poor, the temperature coefficient of elastic modulus is larger (up to 300 x 10-6/ degrees C), suitable for the manufacture of small cross-section, low operating temperature (120 degrees C) of the spring.

Metal spring steel generally contains 0.45% to 0.70% carbon and a certain amount of Si, Mn, Cr, V, W and B alloy elements. The addition of alloyelements improves the anti-relaxation properties of spring steel, improves the toughness of the steel, while significantly improving the quenchability and use temperature of the steel, and is suitable for the manufacture of larger cross-sections and the use of springs at higher temperatures.