How to strengthen the technology of torsion spring

Heat treatment can be used to strengthen the technology of torsion spring
1) Protective atmosphere heat treatment. In our country, the heat treatment of torsion springs, oil-quenched and tempered steel wires and toughened steel with a wire less than 15mm use protective atmosphere heat treatment. Protective atmosphere heat treatment can eliminate surface decarburization and oxidation, and improve the surface of the material quality.
2) Induction heating or protective atmosphere induction heating heat treatment. This process is generally carried out on the wire before the spiral torsion spring is formed. Some torsion spring factories combine the heat treatment of the wire material and the production of torsion springs to reduce costs. Induction heating treatment has more advantages. Good strengthening effect and fast induction heating speed can help refine crystal grains and reduce surface decarburization, which can give full play to and improve the strength and toughness of the material.
3) Surface nitriding heat treatment technology. In recent years, high-stress valve torsion springs or other high-stress clutch torsion springs have also adopted surface nitriding technology to achieve reliable fatigue life. Now the more advanced technology is low-temperature gas nitriding technology , The general nitriding temperature is (450~470)℃, and the gas nitriding time is (5~20)h.

Spring_How to protect the spring surface

Protection method of spring surface:
The surface of the spring can generally be treated, such as blackening, phosphating, electroplating, spraying, etc. In recent years, Dacromet’s protective layer has appeared with excellent corrosion resistance, which is 7~10 of the corrosion resistance of traditional electroplating layers. Double, there is no hydrogen embrittlement of electroplating process. And strong adhesion, especially suitable for surface protection of elastic materials.
The surface of the product treated by Dacromet is silvery white. The main characteristics and use of the surface treatment are corrosion resistance. Oxidation treatment, common spring protection is generally kept in the air for 3 months, and electroplating is used to protect 3 in the general air medium with higher protection. Month-2 years. Phosphating treatment has higher anti-embroidery ability than oxidation treatment, and can withstand high temperatures of 400℃. It is generally used for the protection of important parts such as artillery and gun parts, or as the pre-treatment of other protective layers. Non-metallic protective layer, paint, spray , Electrophoretic paint and other anti-corrosion capabilities, a wide range of applications, and strong anti-corrosion capabilities. At present, the special anti-rust oil protection used for the pretreatment of automobile surfaces is often used for refrigerator compressor springs without hydrogen embrittlement, simple process, environmental protection and pollution-free produce.

Explanation of strengthening treatment of hardware compression spring

Explanation of strengthening treatment of hardware compression spring:
   compression spring strengthening
  Round springs, due to their spiral geometry, are harder to strengthen than flat surface leaf springs. In addition, it is necessary to strictly evaluate the strengthening effect of the circular spring cross section, so as to fully understand the resistance of the circular spring to fatigue fracture.
  The round springs are individually sent to the shot blasting chamber via a continuous conveyor chain system. A set of parallel roller tables are installed in the shot blasting chamber. While strengthening, the roller table keeps rolling, driving the circular spring to rotate while moving forward. This way of rotation allows the high-speed pill flow to pass between the rings of the circular spring and hit the metal surface of the inner ring, where the stress of the circular spring is most concentrated.
  For applications with high productivity requirements, you can choose an enhanced equipment that can spray two round springs at the same time. The latest research and development result is based on the original shot blasting equipment, combined with multiple nozzles, used for more targeted and concentrated shot peening for the specific area of ​​the round spring (stress concentration to please).
   leaf spring reinforcement
  A continuous pass-through shot blasting equipment can be used to strengthen the leaf springs one by one individually, exposing the geometric concave surface of the leaf spring to the high-speed shot flow. A typical model includes a throwing head for projecting the top of the leaf spring, and a throwing head is installed on the side to spray the left and right sides of the leaf spring at the same time.
   The passing speed of this standard leaf spring strengthening equipment is 10 feet per minute. If a higher production speed is required, the number of polishing heads can be increased and the motor frequency can be adjusted. Under working conditions, leaf springs are repeatedly affected by unidirectional bending stress, so they are sometimes stressed by stress. In the strengthening process, it is simulated that the leaf spring will be subjected to “stress strengthening” in the future use process, so that it will be shot peened while applying a “static stress” in the direction of bearing the load. After strengthening, release the applied static stress. Experiments prove that stress strengthening can further extend the service life of leaf springs than conventional strengthening.
   suspension spring strengthening
   Thanks to the high-stress and lightweight design, the weight of suspension springs has been greatly reduced in recent years. It is very common for new models to have suspension springs with a stress of >1000Mpa. The service of the spring under such high stress has exceeded the limit that the material can withstand, so it must be supplemented by other strengthening methods (such as shot/shot peening).
The main engine manufacturer adopts very strict test standards for automobile suspension springs. The longest test period is as long as 70 days (10 weeks). It should be a suspension spring that works under high stress conditions. Once the surface is subjected to stress corrosion That is, corrosion fatigue failure occurs. If the broken spring port punctures the tire, it may cause major safety and personal accidents.
Shot/shot peening is the most effective strengthening method for suspension springs. After proper shot peening, the fatigue life of high-stress springs can be increased by more than 5 times. At present, most suspension springs are shot/shot blasted with steel wire cut blasting. Shot peening (different pellet diameters) is commonly used. The strength and depth of the spring surface compressive stress are important indicators to measure the effect of shot peening. The surface stress of good shot peening is at least above -600Mpa, and it can reach -800Mpa at a distance of 50um from the surface. The surface pressure stress of a stress shot peening spring can reach above -800Mpa, and it can reach -1200Mpa at a distance of 50um from the surface.
   At present, well-known spring manufacturers at home and abroad, such as Liaoyang Kesuo, etc., generally use a continuous pass-through type roll cage reinforcement equipment, and the workpiece is transported through a suspended conveyor chain. Each part must be in three shot blasting positions, and three shot blasting strengthening cycles are performed according to the set time. After the strengthening is completed, the throwing head stops, the discharge door is opened, the strengthened workpiece is automatically lifted out, the new workpiece enters, and the new cycle starts. The equipment’s capacity can reach 500 pieces/hour.

Hardness test method of metal stamping parts

In order to obtain high surface hardness and wear resistance, many metal stamping die and metal stamping die accessories must undergo surface heat treatment, such as surface nitriding. For such a mold, people are very concerned about its surface hardness and hardened layer depth.
   When testing the hardness of stamping die steel that has undergone surface heat treatment, there is a wrong approach worthy of correction. This is the improper use of the Leeb hardness tester in this situation. This is determined by the principle of the Leeb hardness tester. The three commonly used hardness testers of cloth, Luo, and Wei all adopt the static test principle, in which a hard indenter is slowly pressed into the surface of the sample, and then the depth or size of the indentation is tested to determine the hardness value. The Leeb hardness tester uses the principle of dynamic testing.
   It is to impact a sphere of specified mass on the surface of the sample at a specified speed, and test the difference between its initial speed and the rebound speed to determine the hardness value of the sample. To understand this, just look at how thick the standard hardness block of the Leeb hardness tester is. Obviously, the measured hardness value is neither the hardness of the nitride layer nor the hardness of the base material, but the result of the interaction of the two. Because the thickness of the surface layer of the stamping part is different, different results will inevitably be obtained.
  The main material of stamping parts molds is tool steel (including tool steel and high-speed steel), and sometimes hard alloy stamping parts molds are usually required to have high hardness and wear resistance, and heat treatment is essential.

Under what circumstances is it good to use a compression spring

Under what circumstances should a compression spring be used?
   (1) The design load cannot be achieved with round section materials.
   (2) Replace the round section compound spring.
   (3) When the spring with round material cannot reach the required deformation.
   (4) Where the spring installation space is small.
   (5) Where strict spring characteristics are required.
   Pressure spring design principles
  1. The selection of the allowable stress [τ] of the spring material should be based on ensuring the fatigue life of the spring. The dynamic life of springs is generally divided into three categories:
   Class I: The number of alternating loads is 106;
   Class Ⅱ: The number of alternating loads is 10~105;
   Class III: The number of times of bearing the alternating load is less than 10?;
  2. The material width-to-thickness ratio (a/b) should not be too large, and the winding of the spring should not be too small.
  3. When designing non-rectangular shaped cross-section springs, it is necessary to derive and draw curves or calculation formulas in different rotation ratios, different width to thickness ratios, deformation correction coefficients (τ) and shear stress correction coefficients (β).
  4. According to the given conditions and constraints, choose a design method that is simple to calculate and select reasonable parameters.

Energy-saving heat treatment of extension springs and application effects of heat treatment technology

Energy-saving heat treatment of extension springs and application effects of heat treatment technology:
  1. Energy-saving heat treatment for extension springs
  Scientific production and energy management are the most potential factors for the effective use of energy. The establishment of a professional heat treatment plant to ensure full-load production and give full play to equipment capabilities is the choice of scientific management. In terms of heat treatment energy structure, priority is given to primary energy; waste heat and waste heat are fully utilized; processes with low energy consumption and short cycles are used instead of processes with long cycles and high energy consumption.
   2. Less non-oxidizing heat treatment
By using protective atmosphere heating instead of oxidizing atmosphere heating to controllable atmosphere heating with precise control of carbon potential and nitrogen potential, the performance of parts after heat treatment is improved, heat treatment defects such as decarburization, cracks, etc. are greatly reduced, and the finishing allowance after heat treatment is reduced , Improve material utilization and machining efficiency. Vacuum heating gas quenching, vacuum or low-pressure carburizing, nitriding, nitrocarburizing and boronizing can significantly improve quality, reduce distortion and increase life.
  3. Application effect of heat treatment technology of extension spring
  (1) Expanded the scope of application of GCr15 steel
   Generally, the effective wall thickness of the ferrule during quenching of GCr15 steel M is less than 12mm, but the effective wall thickness of the ferrule can be expanded to about 28mm due to the strong cooling ability of nitrate salt during BL quenching.
  (2) Stable hardness and good uniformity
Because BL transformation is a slow process, generally GCr15 steel needs 4h, GCr18Mo steel needs 5h, the ferrule is isothermal in nitrate salt for a long time, and the surface core structure changes almost simultaneously, so the hardness is stable and the uniformity is good. Generally, GCr15 steel BL The hardness after quenching is 59~61HRC, and the uniformity is ≤1HRC. Unlike the larger ferrule wall thickness during quenching, problems such as low hardness, soft spots and poor uniformity will occur.
  (3) Reduce quenching and grinding cracks
In the production of railway and rolling mill springs, due to the large size and heavy weight of the ferrule, the M structure is brittle during oil quenching. In order to obtain high hardness after quenching, strong cooling measures are often taken, resulting in quenching micro-cracks; while BL quenching, due to The toughness of the BL structure is much better than that of the M structure. At the same time, a compressive stress of -400~-500MPa is formed on the surface, which greatly reduces the tendency of quenching cracks; during grinding, the surface compressive stress offsets part of the grinding stress and makes the overall stress level Drop, greatly reducing the grinding cracks.

The whole process of laser heat treatment of precision spring

1. The deformation of the processed part is extremely small. Due to the high laser power density, the interaction time with the part is very short (10-2-10 seconds), so the thermal deformation zone and the overall change of the part are very small. Therefore, it is suitable for high-precision parts processing as the final processing procedure of materials and parts;
  2. No need to use additional materials, only change the structure of the surface of the material to be treated. The modified layer after treatment has enough thickness, and the depth can be adjusted as needed, generally up to 0.1-0.8mm;
  3. The treatment layer and the substrate have high bonding strength. The laser surface treatment of the modified layer and the substrate material is a dense metallurgical bond, and the surface of the treatment layer is a dense metallurgical structure with high hardness and wear resistance;
  4. Good processing flexibility and wide application range. The flexible light guide system can freely guide the laser to the processing part, so that deep holes, inner holes, blind holes and grooves can be conveniently processed, and selective local processing can be performed.
  to sum up:
Laser heat treatment is a method of using high-power density laser beams for surface treatment of metals. It can achieve phase change hardening (also called surface quenching, surface amorphization, surface remelting and quenching), surface alloying and other surfaces. Modification treatment produces changes in surface composition, structure and performance that cannot be achieved by quenching with its large surface. After laser treatment, the surface hardness of cast iron can reach above 60 degrees HRC, and the surface hardness of medium-carbon and high-carbon carbon steel can reach above HRC70 degrees, thereby improving wear resistance, fatigue resistance, corrosion resistance, oxidation resistance, etc. Its service life. Compared with other traditional heat treatment such as high frequency quenching, carburizing, nitriding, laser heat treatment technology has the above characteristics.

Detailed introduction of laser heat treatment of hardware spring

Laser heat treatment is a method of using high-power density laser beams for surface treatment of metals. It can achieve phase change hardening (also called surface quenching, surface amorphization, surface remelting and quenching), surface alloying and other surfaces. Modification treatment produces changes in surface composition, structure and performance that cannot be achieved by quenching with its large surface. After laser treatment, the surface hardness of cast iron can reach above 60 degrees HRC, and the surface hardness of medium-carbon and high-carbon carbon steel can reach above HRC70 degrees, thereby improving wear resistance, fatigue resistance, corrosion resistance, oxidation resistance, etc. Its service life. Compared with other traditional heat treatment such as high frequency quenching, carburizing, nitriding, laser heat treatment technology has the following characteristics:
  1. No need to use additional materials, only change the structure of the surface of the material to be treated. The modified layer after treatment has enough thickness, and the depth can be adjusted as needed, generally up to 0.1-0.8mm;
  2. The treatment layer and the substrate have high bonding strength. The laser surface treatment of the modified layer and the substrate material is a dense metallurgical bond, and the surface of the treatment layer is a dense metallurgical structure with high hardness and wear resistance;
  3. The deformation of the processed part is extremely small. Due to the high laser power density and the short interaction time with the part (10-2-10 seconds), the thermal deformation zone and overall change of the part are very small. Therefore, it is suitable for high-precision parts processing as the final processing procedure of materials and parts;
  4. Good processing flexibility and wide application range. The flexible light guide system can freely guide the laser to the processing part, so that deep holes, inner holes, blind holes and grooves can be conveniently processed, and selective local processing can be performed.

Several methods for strengthening the elasticity of hardware springs

1. Setting treatment:
   is also known as “settling treatment”. Compress the heat-treated compression spring to the height or compression height under the working limit load (the length of the tension spring stretched to the working limit load, the torsion spring is twisted to the working limit torsion angle), one or more brief compressions (tension Stretching, torsion) is a process method with the main purpose of stabilizing the spring geometry.
   2. Heating setting treatment:
   is also called “heating and standing treatment”. Standing treatment under conditions higher than the working temperature of the spring.
   Three, strong pressure treatment:
   Compress the compression spring to the surface of the spring material to produce beneficial residual stress that is opposite to the working stress, so as to achieve a process method to improve the spring load capacity and stabilize the geometric size. (The other is heating and pressure treatment, this type of spring is mainly used in thermostats and overload protectors)
   Four, strong pull processing:
   A process that stretches the tension spring to the surface of the spring material to generate beneficial residual stress that is opposite to the working stress, so as to improve the spring load capacity and stabilize its geometric dimensions.

Technical parameters and application range of compression spring

The pressure spring balanced manual loading and unloading crane tube has the characteristics of flexible operation, light weight, and convenient alignment; the structure adopts the pressure spring balance device, which does not occupy the trestle space, and can maintain balance at any position within the working range, easy manual operation, and reliable sealing It is an ideal operating equipment for the manual loading and unloading of light oil, heavy oil and other chemical liquids for trains and automobile tankers.
   Compression spring technical parameters:
  1、Nominal diameter DN50~DN100
  2, nominal pressure 1.6MPa
  3, horizontal rotation angle 0°~360°
  4, vertical pitch angle -15°~60°
  5. Sealing material: polyurethane rubber, fluorine rubber or silicon rubber
  6. ​​Applicable medium: light oil, heavy oil, lubricating oil and chemical liquid
   Compression spring complete supply range:
  1, crane tube body 2, sealing cover
   3. Liquid level alarm 4. Vapor recovery metal hose
   Other
The typical size parameters A, B, C, D, E, F of    crane tube are as shown in the table below, and they can also be designed and manufactured according to user requirements.
   type
  Dimension parameters (mm) ABCDEFQDY fire 005 type submerged loading and unloading crane pipe 37003800600~800
  Shun package 3700~4200 Flip package 5400~6000
  360850~950QDY steam 005 type submerged loading and unloading crane pipe 14002100600
  Shun 2200~2400 flip 3300~3500
  270660~770