Material overview of compression spring

Material of compression spring:
Instrument wire for parts beginning with number C: in accordance with ASTM a228 or AMS 5112. When the temperature exceeds 121 degrees Celsius (250 degrees Fahrenheit), the use of musical instrument wire springs is not recommended
Stainless steel wire for parts beginning with number C: 302 stainless steel, conforming to ASTM a313 or AMS 5688, spring tempered (physical and chemical properties only). Springs made of stainless steel are not recommended when temperatures exceed 260 degrees Celsius (500 degrees Fahrenheit)
Musical instrument wire for parts with numbers beginning with D: in accordance with DIN 17223 or JIS g4314 swp-nb
Or AMS 5112, it is not recommended to use the spring made of metal string of musical instrument
Stainless steel wire for parts with numbers beginning with D: 301, 302 or 304 stainless steel, in accordance with DIN 17224 or JIS g4314, Sus 302 / 304 or AMS 5688, spring tempered (physical and chemical properties only). Springs made of stainless steel are not recommended when temperatures exceed 260 ° C (500 ° f)
Type 302 stainless steel is slightly magnetic. There may be a little residual nickel on the surface of stainless steel. This is a normal phenomenon and will not affect the function of the parts
Wire diameter refers to the diameter before forming
Unless stainless steel is specified, musical instrument wire shall be used in general. When inquiring and ordering, the letter “m” or “s” shall be used to indicate stainless steel and musical instrument wire respectively

Manufacturing process of special shaped spring

Special shaped spring is made of steel wire. It has various shapes and can be customized according to market demand
A linear spring forming special-shaped spring device, in which there are three or more forming tools arranged radially around the center line of the main shaft for wire guiding, which are pushed in the direction perpendicular to or basically perpendicular to the center line of the main shaft and towards the extension direction of the central line of the main shaft, And the forming tool strikes the wire which is sent in from the top part of the spindle

The equipment is characterized in that it also includes: a first driving device for turning the rotary table, and the corresponding tracks for moving forward and backward of the sliding components equipped with forming tools are fixed on the rotary table, and these sliding components can move forward and backward along the extension direction of the central line of the main shaft perpendicular or substantially perpendicular to the central line of the main shaft, and a number of second driving devices.

 

The second driving device is arranged radially outside the rotary table around the center line of the main shaft to make the required sliding component move forward and backward towards the extension line of the central line of the spindle; the special-shaped spring is a third driving device for feeding the wire rod from the top part of the spindle; and, The first driving device and the second driving device are controlled to be synchronized with the third driving device. The main shaft can rotate around the center line of the main shaft and can be converted between the two situations. One is that the main shaft is fixed by a connecting member and cannot rotate; the other is that the main shaft is connected with the rotary table through another connecting member, Make it rotate with the turntable

Basic factors affecting the service life of dies

The basic factors affecting the service life of dies are as follows
Die structure design, die material, cold and hot processing technology, heat treatment, grinding, adjustment and operation of machine tool, properties and state of processed materials, lubrication conditions and service environment of dies are the eight basic factors affecting the service life of dies

1. Structural design
Unreasonable structural design is often an important factor for the early failure and heat treatment deformation and cracking of the die. In the structural design of the die, sharp fillet and excessive cross-section change should be avoided as far as possible. The stress concentration caused by sharp fillet can be as high as 10 times of the average calculated stress, For example, the inner square head bolt was upset by cold upsetting die in the original design, and the service life was 500 pieces, which broke at the stress concentration part of punch fillet transition; later, the design was improved to increase the radius of fillet transition part from R = 0.127mm to 0.381-0.5mm, and the service life was increased to 12000-27000 pieces, In order to prevent heat treatment deformation and cracking, the cross-section size should be uniform, the shape should be symmetrical and simple, the blind hole should be opened as far as possible, the process hole could be opened if necessary, and the mold with complex shape and easy deformation and cracking could be changed into combined type

2. Die material and heat treatment
The influence of die material on die life is reflected in three aspects: whether the die material is selected correctly, whether the material is good and whether it is used reasonably. When selecting material, the requirements of die performance must be taken into consideration. For cold stamping die, the strength, toughness and wear resistance of steel should be mainly considered. The strength and toughness, as well as toughness and wear resistance, often go up and down When cracking, it is necessary to select materials with lower strength but better toughness, or formulate reasonable heat treatment process to improve the toughness of steel, or select high-grade alloy steel with both high strength and high toughness according to the actual situation, Reasonable surface treatment is used to improve the wear resistance of the die. The strength, wear resistance and corrosion resistance of the plastic die steel at the plastic forming temperature should be taken into account, and the processability and specularity should also be considered

Improper heat treatment is an important factor leading to early failure of dies and moulds. The influence of heat treatment on die life is mainly reflected in two aspects: unreasonable technical requirements for heat treatment and poor quality of heat treatment. Statistical data show that about 70% of dies fail early due to improper material selection and heat treatment. This problem is discussed separately in sections 4 and 5

3. Hot and cold processing technology
The influence of forging and machining on die life is often ignored. Incorrect forging and machining often become the key to early failure of dies. Taking Cr12MoV steel as an example, this steel is one of the most commonly used cold working die steels in China. It belongs to high carbon and high chromium ledeburite steel, which contains a lot of primary and secondary carbides and has a large segregation, It is important to improve the distribution of carbide in Cr12MoV steel. Table 1 shows the effect of carbide grade on mechanical properties of Cr12MoV steel

It is difficult to eliminate the eutectic network carbide by heat treatment, so it must be refined and homogenized by forging. In the national standard, the grade of network carbide is wide. In actual use, it needs to be re forged to meet the requirement of no more than grade 2 carbide. Therefore, it is necessary to upsetting and drawing steel billet from different directions, It should be forged according to “two light and one heavy” method. That is, when the billet is heated to 1100 ~ 1150 ℃, it should be struck gently to prevent forging crack; when the temperature is 1000 ~ 1100 ℃, it should be hammered again to ensure that the carbide is broken; when the plasticity of steel is lower than 1000 ℃, it is necessary to strike again to prevent internal crack, and to ensure that the direction of the carbide formed is perpendicular to the working face of the die, The final forging temperature is 850 ~ 900 ℃ and the forging ratio is generally controlled at 2 ~ 2.5. The crypto needle martensite, fine dispersed carbides and a small amount of retained austenite can be obtained by quenching with residual heat after forging and tempering at low temperature. The service life of the die can be greatly improved

Incorrect machining may lead to early failure of dies in the following three aspects:
① Improper cutting, forming sharp fillet or too small fillet radius, often causes stress concentration and makes die early failure;
② The surface finish is not enough and there are not allowed tool marks, which often lead to the failure of die due to early fatigue failure;
③ The decarburization layer formed by rolling and forging was not removed completely and evenly by machining, which resulted in the formation of soft spots and excessive residual stress after heat treatment, which led to the early failure of the die

Structure of spring safety valve

The spring safety valve consists of valve disc and valve seat. The valve disc is connected with the valve stem, and the total displacement of the valve stem must meet the requirements of the valve
From closing to full opening, the setting pressure of safety valve is mainly adjusted by changing spring pressure by adjusting bolt.
The upper part of the valve is equipped with a lever mechanism, which is used to lift the valve stem manually during the working test.
The valve body is equipped with upper and lower adjusting rings. Adjusting the lower adjusting ring can make the valve obtain a complete take-off action
The adjusting ring is used to adjust the recoil pressure. The return pressure enables the valve to obtain a complete take-off, and the upper ring is used to adjust
Recoil pressure. If the re seat pressure is too low, the valve will remain open for a long time, and if the re seat pressure is too high, the valve will continue to jump and
Closing causes chatter, causing valve damage and reducing valve discharge. The best position of the upper adjusting ring should be able to
Valve reaches full stroke.

Price analysis of wire spring

Wire spring machine is a necessary production tool in the spring industry, so people in the spring industry are very concerned! As a spring machine sales nearly 7 years, for the understanding of spring machine price, make a small explanation for the people in need
First of all, fractional control spring machine, CNC universal machine and mechanical spring machine
The smallest CNC spring presses are generally 8-type machines, domestic ones are about 60000-80000, Taiwan brands are about 120000-160000, 2mm spring presses are about 100000 yuan, Taiwan machines are about 150000.3mm spring presses are about 120000-150000, Taiwan machines are more than 200000 yuan. 5mm spring presses are about 250000-350000 yuan, Taiwan machines are about 400000, 8mm spring presses, The price is about 550000-750000. The price of 20 mm spring press is more than 1.5 million
The price of CNC universal machine and 2mm machine is about 110000-150000 for domestic cam spring machine, about 190000-210000 for non cam non rotating line, about 350000-390000 for Taiwan machine, about 170000-200000 for Taiwan machine. For 4mm computer spring machine, the price of domestic cam spring machine is about 180000-220000, and that of Taiwan machine is 550000-650000
Mechanical spring machine, cheap, troublesome operation, production accuracy is not enough, has been gradually diluted by the market, here no longer mentioned
This is just some of my understanding of the market under the current situation. Perhaps, the prices vary in different periods of time, different models and manufacturers, which are not completely accurate. Please refer to the actual transaction price for reference only

Advantages of leaf spring

The suspension spring plays a role in the suspension system of the car, which is responsible for bearing the weight and load of the vehicle, absorbing and eliminating the vibration caused by the fluctuation of the road surface, so as to increase the comfort of the vehicle when driving
There are many different types of springs in automobiles according to the different suspension devices. Most of the modern vehicles are leaf springs. The sheet spring is composed of 4 to 15 pieces of elastic long cylinders with a thickness of 6-12 mm, which are overlapped and fixed by steel plate clamps, so that the spring sheets are not easy to break when bending. The spring is installed on the frame by the lifting lug at the two ends, Depending on the elasticity of the plates and the friction between the plates, the damping effect is achieved
The advantages of leaf spring: simple structure and low cost. However, the sheet suspension spring is easy to shake the body, and it is poor in handling and comfort. Therefore, it is mostly used in the rear suspension of medium and large trucks

Production technology of spring steel

Research direction
The strength level of traditional spring steel is difficult to meet the requirements of modern industrial development. As we all know, the mechanical properties of spring steel depend on the heat treatment process under the premise of material quality assurance, and the heat treatment process should also be determined according to the materials used. An important way of high strength spring steel is to give full play to the role of alloy elements to achieve the best alloying effect

(1) Heat treatment
Spring steel requires higher strength and fatigue limit. It is usually used in the state of quenching and tempering at medium temperature to obtain higher elastic limit. Heat treatment technology has a crucial impact on the internal quality of spring. Therefore, further research is needed to further improve the fatigue life of spring, In order to further strengthen the surface strength, increase the compressive stress and improve the fatigue life of the valve spring, the valve spring should be further nitrided, low temperature liquid carbonitriding or sulfur nitriding treatment, and then shot peening strengthening. Nitrogen infiltration not only eliminates the adverse effects of decarburization, In addition, the residual compressive stress is increased, and the high temperature strength of the valve spring after nitriding and liquid carbonitriding is improved.

 

The deformation amount at 150 ℃ is 0.2% (the specified value is 0.5%), and the deformation amount at 250 ℃ is 0.56%, which improves the thermal stability and anti relaxation stability of the valve spring. However, the time of nitriding and liquid carbonitriding should be strictly controlled, otherwise the network sulfide and network nitride will be formed, On the contrary, it will reduce its fatigue strength

(2) Alloying
Carbon is the main strengthening element in steel, and its influence on spring steel is often more than that of other alloy elements. According to the application requirements, spring steel material should be medium and high carbon alloy steel. In order to overcome the problem of reducing toughness and plasticity after increasing the strength of spring steel, there is also a trend to reduce carbon content

The main function of alloy elements in spring steel is to improve mechanical properties, process properties and give some special properties (such as high temperature resistance, corrosion resistance)
In many spring steels, silicon is the main alloy element, which has the greatest influence on the elastic reduction resistance. This is mainly due to the strong solid solution strengthening effect of silicon. At the same time, silicon can inhibit the nucleation and growth of cementite during tempering, change the quantity, size and morphology of carbide precipitated during tempering, and improve the tempering stability of steel, It will promote the decarburization and graphitization tendency of steel during rolling and heat treatment, and make smelting difficult and easy to form inclusions. Therefore, the use of spring steel with high silicon content should be cautious

Because chromium can significantly improve the hardenability of steel, prevent the graphitization tendency of Si Cr steel during spheroidizing annealing and reduce decarburization layer, it is a common alloy element in spring steel. The spring steel 50CrV with chromium as the main strengthening element is widely used
Molybdenum can improve the hardenability of steel, prevent temper brittleness and improve fatigue property. There are not many spring steels added molybdenum in the existing standards, and the addition amount is generally less than 0.4%

Production technology of spring steel

Spring steel is a kind of steel specially used for manufacturing springs and elastic elements due to its elasticity in quenched and tempered state. The elasticity of steel depends on its elastic deformation capacity, that is, within the specified range, the elastic deformation capacity enables it to withstand a certain load, and there is no permanent deformation after the load is removed
Spring steel should have excellent comprehensive properties, such as mechanical properties (especially elastic limit, strength limit, yield ratio), elastic reduction performance (i.e. anti elastic degradation performance, also known as anti relaxation performance), fatigue performance, hardenability, physical and chemical properties (heat resistance, low temperature resistance, oxidation resistance, corrosion resistance, etc.) to meet the above performance requirements, Spring steel has excellent metallurgical quality (high purity and uniformity), good surface quality (strict control of surface defects and decarburization), accurate shape and size
1. Classification
(1) Carbon spring steel
The carbon content of carbon spring steel is generally in the range of 0.62% – 0.90%. According to its manganese content, it can be divided into general manganese content (0.50% – 0.80%), such as 65, 70, 85 and higher manganese content (0.90-1.20%)
(2) Alloy spring steel
Alloy spring steel is a kind of steel which can improve the mechanical properties, hardenability and other properties of the steel by adding one or several alloy elements on the basis of carbon steel to meet the requirements of manufacturing various gas springs
The basic composition series of alloy spring steel include silicon manganese spring steel, silicon chromium spring steel, chromium manganese spring steel, chromium vanadium spring steel, tungsten chromium vanadium spring steel, etc. on the basis of these series, some brands have added molybdenum, vanadium or boron alloy elements in order to improve their performance in some aspects
According to the working conditions of spring, it can be divided into static load bearing spring steel, impact load bearing spring steel, high (low) temperature resistant spring steel and corrosion-resistant spring steel
2. Production process
Generally, spring steel can be produced in electric furnace, open hearth furnace or oxygen converter; high quality spring steel with good quality or special performance can be refined by electroslag furnace or vacuum furnace. The specified content range of main elements such as carbon, manganese and silicon in spring steel is narrow, so chemical composition must be strictly controlled during smelting. When silicon content is high, it is easy to form bubbles and other defects, Therefore, the raw materials for smelting must be dry, gas and inclusions should be removed as far as possible, and the molten steel should be avoided from overheating
It is necessary to pay special attention to decarburization and surface quality in the rolling process of spring steel. When the surface decarburization is serious, the fatigue limit of steel will be significantly reduced. For high silicon spring steel such as 70si3mna, attention should be paid to avoid graphitization. Therefore, the stop rolling temperature should not be too low (≥ 850 ℃) during hot working, so as to avoid staying too long in the temperature range (650-800 ℃) where graphitization is easy to form
After the spring is made, shot peening can produce residual compressive stress on the surface layer of the spring to offset part of the working stress on the surface layer and inhibit the formation of surface cracks, which can significantly improve the fatigue limit of the spring

Phosphating treatment of spring

Phosphating treatment of spring
Phosphating is a process to prevent the spring from corrosion during transportation and use. The phosphated spring has corrosion resistance in air, animal and vegetable mineral oil, toluene and other organic solvents. The spring is suitable for zinc phosphate treatment and can avoid hydrogen embrittlement. The phosphating film is thicker than the oxide film, Generally, it is 5 ~ 10 microns. Generally, phosphating has better corrosion resistance than oxidation. Especially, phosphating treatment is suitable for the front process of spring upper protective frame
(1) Spring phosphating process cold and hot water
(1) Removing oil and rust — removing copper — cleaning — phosphating — cleaning — passivation — saponification — soaking film to replace oil — storage
Phosphating process:
Remove oil, rust and oxide scale by shot peening or sand blasting. Used for quenching and tempering springs
2. It can be washed with gasoline and can be phosphated (washed twice or three times) after drying. It is mainly used for fine spring
3. Chemical deoiling naoh100 ~ 150g / L, 20 ~ 70% na2co2 heated to 100 ℃
4. Degreasing and rust removal of barrel is used for stretching spring
This process can be omitted when there is no copper in water and 250 ~ 300 g / L chromic acid and 80 ~ 100 g / L ammonium sulfate
Acid removal by washing with tap water
Manganese iron phosphate tetraphosphate 30 ~ 35 g / L, zinc nitrate 55 ~ 75 g / L, temperature 70 ~ 80 ℃ for 10 ~ 15 minutes, total acidity 48 ~ 60, free acid 2.5 ~ 6.7, sulfate radical ≤ 0.5
5. Washing with tap water
Hexapassivation potassium dichromate (k2cr2o2) 80 ~ 100g / L, 90 ~ 100 ° C
7. Washing with tap water
8. Wash with hot water 90 ~ 100 ℃ for 1 ~ 2 minutes
9. Saponification of 10-20 g / L industrial soap or triethyl oleic acid soap at 50-70 ℃ for 1-2 minutes
10. Change the oil after soaking in water
11. Warehousing
(2) Operation procedures and precautions of spring phosphorus process
(I) before going to work every day, the surface condition of the spring to be phosphated shall be strictly checked, and it is required to be clean and bright. No oil, dirt, rust, copper coating, etc. are allowed
(II) turn on the phosphating tank, passivation tank, hot water tank and heating power supply of saponification tank to ensure that the phosphating bath liquid is 70 ~ 80 ℃, the passivation tank is 90 ~ 100 ℃, the hot water tank is 90 ~ 100 ℃, and the saponification tank is 50 ~ 70 ℃
(III) the material frame used before phosphating is fully sprayed and then loaded with spring. Polyester cotton gloves that must be cleaned or put on the frame shall not have large area or line contact between springs
(IV) the phosphating process requirements should be strictly followed during phosphating, and the temperature should be kept for 10 ~ 15 minutes
(V) after phosphating, the spring should be washed with tap water
(VI) the spring should be kept in the passivation tank for about 1 ~ 2 minutes. After passivation, the spring should be sprayed with tap water
(VII) put the spring into the hot water tank for cleaning for 1-2 minutes, and then put it into the saponification tank for 1-2 minutes, and then send the spring to the coating place or the oil coated part
(VIII) after work, turn off the power supply and clean the workshop carefully
(IX) add manganese iron phosphate and zinc nitrate to the phosphating tank at the ratio of 1:2, the waste potassium dichromate in the passivation tank should be treated in a centralized way, and the saponification tank should be often supplemented with soap or triethyloleic acid soap
(x) if passivation is not required, operation procedure VI can be omitted
(XI) before phosphating, the interval between sand blasting, shot blasting and phosphating should not exceed 4 hours. After cleaning, the spring must be put into the clean material frame
(3) Phosphating quality inspection method
(I) immersion method
3% sodium chloride, temperature 15 ~ 25 ℃, immersion for 2 hours without rust is qualified
(II) drip method
Copper sulfate CuSO 20.5n 40 mg, sodium chloride 10% 20 mg, sulfuric acid 0.1N 0.8 mg
The longer the yellowing time is, the better the quality is. The one without discoloration within 3 minutes is qualified
(III) drip method II
Copper sulfate CuSO4, sh2066 g / L, sodium chloride 32.5 g / L, hydrochloric acid HCl 1:101.2 g / L, drip for more than 3 minutes without yellowing are qualified http://www.888th.com.cn
(IV) immersion method
Copper sulfate 5% solution, immersion for 1 minute, the workpiece surface does not appear yellow is qualified
While inspecting the phosphating quality of the workpiece, the total acidity, free acid and acid radical parameters of the phosphating bath solution must be tested regularly to ensure the daily phosphating quality of the workpiece

What are the failure modes of general springs

What are the failure modes of general springs
Spring is one of the important basic parts in mechanical products. There are many kinds of them, such as spiral spring, plate spring, disc spring, ring spring, plane (truncated cone) volute spring, etc. according to the bearing characteristics, it can be divided into compression, stretching and torsion springs. There are also ways to divide springs according to forming mode and material. The stress of spring mainly includes bending stress, torsion stress, tension and compression stress and composite stress. The main failure modes of spring are fracture, deformation, relaxation and wear.

The main analysis is fracture and deformation (relaxation). Failure mode classification of spring: spring is one of the important basic parts in mechanical products. There are many kinds of them, such as spiral spring, plate spring, disc spring, ring spring, plane (truncated cone) volute spring, etc. according to the bearing characteristics, it can be divided into compression, stretching and torsion springs. There are also ways to divide springs according to forming mode and material.
The stress of spring mainly includes bending stress, torsion stress, tension and compression stress and composite stress.
The main failure modes of spring are fracture, deformation, relaxation and wear. The main analysis is fracture and deformation (relaxation).