Metal spring anti-rust technology

In daily life, we often see that although stainless steel does not rust, stains often appear on the surface. Stainless steel hardware springs are a bit more difficult than ordinary stainless steel, so some tips should be used to deal with them. Then other stainless steel products also have the same principle.
   Generally, the washing method is based on the surface condition, and we also need to pay attention to some specific matters.
   For example, when washing, please be careful not to scratch the surface. Avoid using bleaching ingredients, detergents containing abrasives, steel balls (brush roller balls), abrasive tools, etc., in order to remove the detergent, after washing, rinse the surface with clean water.
Labels and stickers, use warm water, weak detergent to scrub; dust and easy to remove scales, use soap, weak detergent or warm water to wash; binder components, use alcohol or organic solutions; surface pollution caused by rust, use Nitric acid (10%) or abrasive detergent for washing-Use special detergents to cause excessive rainbow patterns, caused by detergent or oil, use warm water detergent when washing.
Fat, oil, lubricating oil pollution, wipe dry with a soft cloth or paper, and then use neutral detergent or ammonia solution or special detergent to wash; fingerprints, use alcohol or organic solvents (ether, benzene), wipe with a soft cloth Wash with water after drying; rinse with water immediately after bleaching and acid attachment, soak in ammonia or neutral carbonated soda aqueous solution, and then wash with neutral detergent or warm water.
Welding discoloration by heat, wash with 10% nitric acid or hydrofluoric acid solution, then neutralize with ammonia water and carbonated soda light solution, and then wash the stainless steel spring with water–specially used for washing medicine; organic carbide is attached and soaked in hot neutral detergent or The ammonia solution is then washed with a weakly abrasive detergent, and so on.
  Using these methods to clean stainless steel products can try to ensure that the damage on the surface of the stainless steel is minimized, so that the stainless steel products look more comfortable and more comfortable to use.

Surface treatment technology and precautions of mold spring

Existing molds are the main process equipment for industrial production. The development of modern industrial products and the improvement of technical levels depend largely on the development level of the mold industry. In recent years, the increase in automation has led to the rapid development of foreign molds. And many The manufacturing industry is in a similar situation. Although China is a big country in mold production, it is not a strong country in mold manufacturing. For springs that match the mold, this detail is also the key to achieving quality. The pros and cons of its surface treatment process directly affect the use of the entire mold Performance. To this end, the editor of Huicong Surface Treatment Network has collected and sorted out the information, and I will share it with you briefly here.
  Colorful paint finish
  The surface of the spring is identified by various paint layers, such as yellow paint for light and small loads; blue paint for light loads; red paint for medium loads; coffee paint for extremely heavy loads;
   Performance analysis: A good paint layer to match the surface treatment of the spring can be described as two birds with one stone. The color is used to identify various technical parameters, which is convenient for industrial production and operation, and the anti-corrosion performance of the spring surface can be better guaranteed.
At present, the main manufacturers that successfully use the above methods are mostly abroad, especially in Japan. In China, only a small number of manufacturers have effectively visited. At present, there are mainly some fixed technical requirements, such as the use of imported materials to reach foreign levels, but the whole However, there is obviously a gap in the effect of spring surface treatment.
   Generally, manual painting is used in China, and the appearance will appear sagging, leaking, poor combination, and poor rust resistance. The limitations of its own process cause a large number of products to be stripped and reworked.
Electrophoretic paint is used abroad. In a water-soluble paint tank, the workpiece is used as a cathode, and a certain voltage and time are applied to form a uniform thickness of paint on all surfaces of the spring, which can then be cleaned and dried. Clean and bright, no particles, no bottoming phenomenon, good binding force, not easy to fall off, good hardness of 3-4H, if the British LVH company polyurethane cathodic electrophoretic paint is used, its softness is quite good. The operating environment does not have a strong solvent smell, and the air There is little pollution, and the wastewater treatment and discharge process is simple, just adjust the resin of the PH sedimentation electrophoretic paint, and then discharge the clear water.
  The paint used for the spring paint layer
  A. Asphalt paint Asphalt paint has good water resistance, moisture resistance, and corrosion resistance, especially excellent acid resistance and good alkali resistance. However, adhesion, mechanical strength, and decoration are poor.
b. Phenolic paint Phenolic paint is divided into two types: primer and top coat. Phenolic primer has strong adhesion and good anti-rust performance, but the mechanical strength and gloss of the paint film are poor. The phenolic top coat paint film is hard, good gloss, but resistant The climate is poor, and the paint film is easy to turn yellow.
c. Alkyd paint Alkyd paint film is tough, strong adhesion, good mechanical properties, excellent gloss, good durability and certain oil resistance and insulation properties. The disadvantage is that the surface dries quickly and the hand sticks for a long time , Easy to wrinkle, intolerant to water and alkali.
d. Epoxy paint Epoxy paint has strong adhesion, high hardness, good toughness, flex resistance, impact resistance, hard but not brittle, and has excellent resistance to water, acid, alkali and many organic solvents. Especially alkali resistance is more prominent. Its disadvantage is that the surface chalks fast and the solvent selectivity is large. Water-soluble epoxy paint is used for electrophoretic coating.
In general, the paint layer can be used alone or as a colorant after phosphating. Sometimes, some springs are also sprayed with different colors of paint to distinguish them in order to be classified according to the load. Which type and brand to choose The paint should be determined according to the working environment. If necessary, it should be indicated in the spring pattern.
  Spring surface finishing treatment
   In recent years, the surface of the spring has been polished (refined) by the spring designer.

The characteristics of push spring steel pickling process

1. Push-type spring steel pickling process characteristics
Push-type spring steel pickling is also called push-pull pickling, which is semi-continuous pickling. The pickling process is that each strip is bitten in sequence by a pinch roller.
Without welding, push forward until coiling. The coils of spring steel strip pass intermittently through the pickling unit to remove oxygen on the surface of the spring steel strip.
For iron sheet, push pickling has the following characteristics:
(1) There are many varieties of pickled spring steel, such as carbon steel, silicon steel, alloy steel, etc.;
(2) Strong adaptability. For example, the thickness of the pickling spring steel strip of the continuous unit generally does not exceed 6.Smm, while in the push pickling unit
Up to 9. Smm, even 12mm;
(3) Multiple narrow strips can be pickled at the same time;
(4) The cost of equipment is low, and expensive welding machines, tension leveling machines and huge cart-type loopers are eliminated.
Therefore, push-pull pickling is favored by some small and medium enterprises.
2. Process flow of typical push spring steel pickling unit
Push-type pickling unit process: raw material feeding trolley_steel coil preparation station (five-roll straightening machine_cutting head and all angles)
. Uncoiling-+Yinke guide plate pressure roller_centering side guide roller_five-roll straightening machine_pickling tank_rinsing tank-+drying machine_freeliving
Set_cross-cutting shear_centering three-roller tension device, guide plate, coiler with pressure roller, and unloading trolley.
3. Process index of new type push spring steel hydrochloric acid pickling unit
At present, the production capacity of the new push-type hydrochloric acid pickling unit can reach 100×104 t/a, and the unit speed can reach
200m/min, the belt threading speed reaches 120m/min, the pickling steel strip thickness is 0.8-19mm, and the pickling time is less than 24s,
In addition, a four-roll leveling machine is installed at the outlet section of the unit to improve the straightness of the pickled spring steel strip.

Various functions of springs in the electromechanical industry

The application of springs in modern industrial society is very extensive, especially in electromechanical, and there are many applications, mainly in the following types.
1. Supporting springs mainly for automobiles, motorcycles, diesel engines and gasoline engines.
Such springs include valve springs, suspension springs, damping springs, clutch springs, etc., and they are used in large quantities, accounting for about 50% of the spring production. At the same time, the technical level is also high. It can be said that the technical level of these springs is representative. They are mainly developed in the direction of high fatigue life and high resistance to relaxation, thereby reducing quality.
2. Large springs and leaf springs based on railway rolling stock, trucks and construction machinery.
These springs are mainly formed by hot coils, which is an important aspect of spring manufacturing. With the development of high-speed railways and the upgrading of vehicle damping systems, the technology of hot-formed springs as vehicle suspensions has been greatly improved. This type of spring is mainly developed in the direction of high strength and high precision to stabilize product quality.
3. Electronic and electrical springs based on instruments and meters, typical products such as motor brush springs, switch springs, video cameras and camera springs, as well as computer accessories springs, instrumentation accessories springs, etc.
In this type of springs, leaf springs and heterosexual springs account for a larger proportion, and different products have different materials and technical requirements. This type of spring is mainly developing in the direction of both high strength and miniaturization.
4. Hardware springs based on daily-use machinery and electrical appliances, such as mattresses, sofas, door hinges, toys, lighters, etc.
The demand for this kind of spring is large, but the technical content is not high, which improves the development opportunities for small spring enterprises. This kind of spring is mainly developed in the direction of miniaturization.
5) Special springs mainly to meet special needs.
This kind of springs, such as cradle springs for textile machinery, require high relaxation resistance; springs for ladle water slides require high heat resistance; suspension springs for mine vibrating screens require not only high fatigue performance, but also High corrosion resistance is required, so rubber-metal composite springs are used: In order to meet the comfort of the vehicle, air springs are used.
The suspension springs and valve springs with heterogeneous cross-sections currently appearing are more reasonable than round cross-section springs in terms of lightweight, space saving, improved comfort and improved spring stress distribution. However, such spring materials are expensive and the spring manufacturing process is complex. The cost of the spring is higher than that of the round section spring. Therefore, there is no sign of the replacement of the round cross-section spring with the heterosexual cross-section spring.

Innovative design of spring chuck

If used for a long time, if the spring chuck wears more than a certain limit, the workpiece will not be firmly clamped, which directly affects the machining accuracy and production efficiency. At this time, the spring chuck is scrapped, which virtually increases the manufacturing cost of the fixture, resulting in a huge economy loss. To improve the wear resistance of the chuck, it is necessary to increase the hardness of the chuck. If the hardness of the chuck is too high, the elasticity of the chuck is weakened and the spring flap is easy to break. For this problem, an insert spring chuck is designed.
Improvement of spring chuck
It is composed of two parts, one is the chuck body, and the other is the clamping block, and the two are connected by screws. The chuck body has six spring flaps, and the clamping and unclamping actions are completed by the elastic deformation of the spring flaps when working. The material of the chuck body is 65M n, and the quenching hardness is 40~45 HRC to ensure the elasticity of the chuck; The block is installed on the claw of the chuck and directly contacts the workpiece. The block is an easy-to-wear part. The material of the block can be GCr15 with a quenching hardness of 60-62 HRC to increase wear resistance. The following problems have occurred in the use of insert spring chucks:
(1) Since the chuck manufacturing error is prone to eccentricity, the wall thickness difference of the ferrule after turning will be out of tolerance.
(2) After the clamping block is arbitrarily installed in the chuck, the roundness of the clamping block is not good. If the ferrule is clamped with such a clamping block, the wall thickness difference of the processed ferrule will also be out of tolerance. It must be overcome when manufacturing.
For the conical surface of the fine turning chuck, threaded tires are used to ensure the machining accuracy of the chuck body. After finishing each surface of the chuck and drilling the equally divided holes, turn the conical surface again. When turning the conical surface, use the threaded surface as the positioning reference. Design a threaded tire, which can ensure the machining accuracy when turning the conical surface. The processing principle is as shown in the figure below. First, screw the chuck onto the threaded tire, then install the threaded tire on the spindle of the machine tool, and finally use the small tool holder on the pallet to cut.
Grinding the tapered surface of the chuck: When grinding the tapered surface of the chuck, threaded tires are also used to ensure the grinding accuracy. The cone surface is an important positioning surface in the clamping process of the chuck. The accuracy of the cone surface is good or bad, which directly affects the accuracy of the entire chuck.
To design a set of threaded tire clamping chucks for grinding, the threaded surface is still selected as the positioning reference. The grinding principle is as shown in the figure below. After grinding, the conical surface can reach a coaxiality of 0.1mm with respect to the threaded surface.
Grinding the inner diameter of the collet chuck: The inner diameter of the chuck is ground to ensure the accuracy of the grinding process. The inner diameter of the chuck is also a positioning surface. The inner diameter of the chuck is used to clamp the clamp, and the clamp is used to clamp the workpiece, so the accuracy of the inner diameter is also direct Affect the accuracy of the workpiece, which requires that the inner diameter and the conical surface must be coaxial. We design a special grinding inner diameter mold clamping chuck. This tire is positioned on a conical surface. The grinding principle is shown in the figure below. 02mm。 After grinding, the inner diameter of the chuck is generally up to 0.02mm with respect to the concentricity of the conical surface. The head of the chuck is cut into six petals, and then tempered to enlarge
Using this solution to manufacture the spring chuck can greatly reduce the manufacturing cost and the difficulty of processing, reduce unnecessary waste of materials, improve production efficiency, and bring huge economic benefits.

Precautions when using the spring hanger

The design of the spring hanger currently mostly adopts a hot zero hoisting scheme, that is, when the pipeline is in a hot state, the load of the spring hanger is equal to the working load assigned to the hanger point.
During the work of the spring hanger, there is a certain load change; the supporting point with large thermal displacement requires multiple springs in series, and the number of series is limited. Therefore, the spring hanger will not be able to meet the needs for strictly controlled load changes and large thermal displacements. But it has the advantage of simple structure, so it is still widely used. During the installation and use of the spring hanger, the following aspects should be paid attention to.
(1) According to the installation load provided by the user, the manufacturer uses the upper and lower positioning blocks to fix the indicator plate of the spring hanger at the position corresponding to the installation load, so that the spring hanger is temporarily in a rigid state.
(2) When the pipeline starts to run, first check whether the positioning block is closed and removed, and then check whether the indicator board is jammed during the displacement process from the installation load to the working load.
(3) After the pipeline is put into normal operation, check whether the displacement of the spring hanger under working load is consistent with the design. After the pipeline stops running, check whether the indicator board is reset to the position where the load is installed.
(4) After the pipeline is cleaned and water pressure tested, remove the upper and lower positioning blocks before putting the pipeline into use.
In the spring hanger, the load of the hanger is vertically directly balanced with the spring force, and the spring force is the product of the spring stiffness and the compression value. When the fulcrum point produces a vertical thermal displacement, the spring compression value also changes, and the load of the support frame also changes. If a suitable spring can be selected, the load change of the support frame will be limited to a certain allowable range. Inside, there will be no large change in load or no effort like a rigid hanger.

Disc spring technology summary

Disc springs are disc springs that bear axial load. They are divided into two types: no bearing surface and with bearing surface. It can be used singly, but also can be combined, stacked or combined into a disc spring set. Withstand static load or variable load.
The reasonable choice of disc spring can reduce the space size to the most economical level, and maximize the use of energy and space.
1. The surface of the disc spring is not allowed to have defects such as burrs, cracks, and scars that are harmful to use.
2. Disc spring characteristics
Short stroke and heavy load.
The space required is small. Easy to use in combination. Easy maintenance and replacement.
Economical and safe.
3. Material requirements:
The standard material CK67 is used for thickness less than 1.25mm in accordance with DIN2093. It can also be applied to the thickness of mm under extraordinary circumstances if the customer needs.
The most advanced spring material, 50CrV4, can ensure that the spring is very good at a working temperature of 15℃ and 150℃. Suitable for disc springs below 6 mm thickness.
4. The surface anti-corrosion treatment of the disc spring is generally treated by oxidation, and other anti-corrosion treatments (such as phosphating, electroplating, etc.) can also be used.
5. Friction coefficient and shock absorption
1. Constant instant hits will shorten the life of the spring.
2. When the spring is overloaded or the pressure is loosened rapidly, the spring will be hysterical and scratch the spring.
3. Show the calculated elastic force. The travel table takes 25X12.2X0.9mm reed as an example. The comparison of 4 parallel stacks in 4 groups and 2 parallel stacks in 4 groups shows the increase in friction. , The more pieces are stacked in parallel, the greater the friction.
6. Application industry:
Used in the fields of machinery and equipment industry, petroleum industry, automobile industry, and aerospace industry
Design considerations: When the disc spring is used in series combination, there must be an inner guide post or an outer ring, and the inner palm or outer ring must be heat treated to HRC52 degrees before grinding and polishing.

Introduction of spring oxidation treatment

The oxidation treatment of the spring is also called bluing, blackening, and boiling black. After oxidation, protective magnetic iron oxide is formed on the surface of the spring. This oxide film is generally blue or black, and sometimes dark brown. Its color depends on the surface state of the spring, the chemical composition of the spring material and the oxidation treatment process.
Spring blackening process
In the heated solution of the spring, iron ions (ferrous compounds) are produced due to the alkali corrosion on the surface of the spring. The addition of oxidizing agent-sodium nitrite in the alkali can change the oxidation process and form a dense oxide film on the surface of the spring (4 Ferric oxide). This oxide film is mainly composed of magnetic iron oxide, and the generation time of the oxide film is 30-60 minutes. If the time is extended, the thickness of the oxide film cannot be increased.
The oxidation treatment cost is low, the process formula is relatively simple, the production efficiency is high, the oxide film has a certain degree of elasticity, and basically does not affect the characteristic curve of the spring, so the oxidation treatment is widely used as the anti-corrosion and anti-corrosion treatment of formed coil springs, spring washers and leaf springs Decorative measures.
The quality inspection of the spring after oxidation treatment includes visual inspection and corrosion resistance inspection.
The oxidation treatment methods include: salty oxidation method, alkali-free oxidation method and electrolytic oxidation method. The alkaline oxidation method is mostly used.
The alkaline oxidation method is to put the spring in a sodium hydroxide solution containing an oxidant at a temperature of about 140°C for a certain period of time. The oxidant and sodium hydroxide react with iron to generate sodium ferrite and sodium ferrite, and then react with each other. This produces magnetic iron oxide.
The thickness of the oxide film layer is about 0.6~2μm. Although the oxide film can improve the corrosion resistance of the spring, because the film is thin and has pores, its protection ability is poor, and it can only be used for springs that work in less corrosive media. The level of its anti-corrosion performance depends on the compactness of the oxide film and its thickness, which is also determined by factors such as the concentration of sodium hydroxide, the concentration of the oxidant, and the temperature of the solution.
In order to improve the corrosion resistance and lubricity of the oxide film, the treatment before and after the oxidation treatment should be strengthened. Before oxidation treatment, the rust, oxide scale, oil stain, heat-treated salt residue and surface contact layer on the spring surface must be thoroughly removed. After oxidation treatment, the spring is usually filled in soap solution or dichromate, then washed with running warm water, blow-dried or dried, and finally replaced with a water film to replace the anti-rust oil or mechanical oil with a certain temperature Carry out oil immersion treatment.
Oxidation treatment has eroded the surface grain boundaries of some hot-rolled spring materials, which will reduce the fatigue strength to a certain extent. Therefore, care should be taken when using oxidation treatment.
The traditional oxidation treatment requires heating. In recent years, some domestic manufacturing units have used normal temperature blackening agent, which overcomes the shortcomings of the traditional blackening process and saves a lot of energy.
The blackening agent is blue-green concentrated liquefaction, no impurities, no peculiar smell, non-flammable, non-explosive, non-corrosive, and safe transportation. The blackening agent is diluted with water, and the commonly used dilution ratio is about 1:5 when the spring is blackened.
The operation process of the blackening agent is relatively simple, and the process route is: degreasing, rinsing, acid cleaning, rinsing, blackening (2~5min at room temperature), rinsing, and water film replacement anti-rust oil. It should be noted that the oil on the spring work piece must be removed, cleaned, and then put into the room temperature agent for oxidation treatment.

About heat treatment deformation of hardware spring

There are two main types of hardware spring heat treatment deformation: one is the change in size, and the other is the change in the shape of parts. The treatment methods are different, and the deformation methods of these two heat treatments will be released greatly.
Before the spring heat treatment. The rolled surface of steel is often the surface after the spring is made, so there should be no cracks, folds, scars, hair lines, bubbles, interlayers, and pressed oxide scales. Surface decarburization will significantly reduce the fatigue strength of the spring, so the depth of the decarburized layer should be inspected as required.
After heat treatment, there should be no cracks, corrosion pitting and severe quenching deformation when the spring watch is observed with the naked eye or a low-power magnifying glass. The hardness and its uniformity meet the requirements. In mass production, it is allowed to use a file to sample the hardness, but it must be noted that the position of the file mark should not affect the final accuracy of the spring. The metallographic structure should be troostite or a mixed organization of troostite and sorbite. After the leaf spring is assembled, the permanent deformation and static deflection test under working load are usually carried out.
In conventional heat treatment, the main reason for the shape change of parts is the thermal stress and phase transformation stress that occur during heat treatment heating and quenching. The heating speed is too fast, the parts are too large compared to the heating furnace, and the temperature of each part of the parts is different, which will cause thermal deformation. During heat preservation, the residual stress of processing will be released and deform, and the weight of the part will also cause deformation. When cooling, due to the different cooling rates of different parts of the part, thermal stress will be formed and the part will be deformed. Even if the cooling rate is the same, the cooling is always fast on the surface and slow at the heart. Therefore, the previously transformed surface plastically deforms the untransformed core. If there is segregation of alloy components in the material, or the surface is decarburized, the phase transformation stress will be more uneven and the parts will be more likely to deform. In addition, if the thickness of the parts is uneven, the cooling rate will be different.
The following methods can effectively reduce deformation: 1. Salt bath quenching; 2. High temperature oil quenching; 3. QSQ method; 4. Decompression quenching; 5. One tank three-stage quenching. Salt-bath quenching is similar to high-temperature oil quenching, both of which are quenched at the martensite transformation temperature to increase the uniformity of the martensite transformation. QSQ is double liquid quenching. Decompression quenching is to reduce the liquid surface pressure of the quenching medium, thereby extending the vapor film stage, the cooling rate of the high temperature zone is reduced, and the cooling rate of each part of the part is uniform. One-tank three-stage quenching structure is simple. First, the parts are cooled from the quenching temperature to a temperature slightly higher than the Ms point, then they are discharged from the furnace and maintained in the atmosphere to make the overall temperature of the parts uniform, and then oil-cooled to transform the martensite Evenly, the irregularity of deformation is greatly improved.
In the heat treatment of forgings, the way to reduce the deformation of the parts is to hang vertically as much as possible, the other is to place it vertically at the bottom of the furnace, and the third is to use two horizontal supports, the fulcrum position is at one-third and four of the full length Among them, the fourth is to lay flat on the heat-resistant steel tooling.
In the cooling process of parts, the type of quenching medium, cooling performance, hardenability, etc. are related to deformation. The change of cooling performance can be adjusted by changing the viscosity, temperature, surface pressure of the medium, using additives, and stirring. The higher the viscosity of the quenching oil and the higher the temperature, the smaller the elliptical deformation. In a static state, the deformation is small.

Spring shot peening

Shot peening is generally used in the processing of automobile spring steel plates. It is to reduce the plastic deformation of the processed material.
Shot peening is divided into general shot peening and stress shot peening. In general processing, the steel plate is in a free state, and high-speed steel shot is used to hit the inside of the steel plate to generate pre-compression stress on the surface. To reduce the tensile stress on the surface of the steel plate during work, increase Service life. Stress shot peening is to pre-bend the steel plate under a certain force, and then perform shot peening.
Shot peening is a cold working method that accelerates the pellets with a proper acceleration device and sprays them to the workpiece in a proper way.
Shot peening
Shot peening is used to plastically deform the surface layer and form a strained layer, in which the transformation ratio of the structure and residual stress occurs. Properly controlling these changes in the strain layer can improve the fatigue fracture resistance and stress corrosion cracking resistance of the parts.
Springs are one of the earliest parts in the production of shot peening, especially those compression coil springs, leaf springs and torsion bar springs that are subject to cyclic loads and are prone to fatigue damage. They must be shot peened.
Shot peening is arranged after spring forming and heat treatment. Using small metal balls or metal particles, sprayed on the surface of the spring countless times at a speed of tens of meters per second to produce many small pressure pits, which are uniformly bulging, covering the surface layer of the spring and on the surface layer It produces work hardening, and at the same time it can reduce or eliminate the harmful effects of spring surface defects (such as small cracks, uneven gaps and decarburized layers, etc.), thereby effectively improving the fatigue life of the spring.
Pay attention to the shot peening operation: ①Select the type and specification of the shot correctly, avoid using sharp-edged shots to damage the surface of the spring; ②Select a shot blasting machine reasonably, requiring high injection speed; ③The shot blasting time is required when the conditions are possible Properly longer, so that although the strength of the spring cannot continue to be improved, it can increase the coverage of shot peening and also increase the fatigue life.
The ratio between the area occupied by the bullet marks and the area required for shot peening on the specified parts of the surface of the shot peened part is called the surface coverage. The surface coverage is expressed as a percentage.