KR101297036B1 - Phosphate coating method by utilizing ultrasonic vibration for return spring - Google Patents

Abstract

The return spring inserted into the reclining device, which is a mechanism for adjusting the angle of the backrest of the automobile seat, is a spiral leaf spring that provides a restoring force by winding a thin metal plate. Since the spring flat iron 11 can be in contact with each other, lubrication and abrasion resistance are additionally required, and the surface finish of the return spring is important.
The present invention forms a phosphate film using a zinc-based phosphate and a phosphate solution on the surface of the return spring to form a coating layer for corrosion resistance and rust resistance, and by coating a metal salt on the surface to form a lubricating film, ultrasonic vibration The present invention proposes a method of forming a firm and lubricious film by forming a more dense and rigid film by reacting with and preventing the return spring from rusting and abrasion resistance of the surface of the return spring.

Description

Phosphate coating method by utilizing ultrasonic vibration for return spring}

The present invention relates to a method for surface treatment of metals, and more particularly, to a method for forming a phosphate coating on the surface of a return spring used as an accessory of a reclining apparatus that is a backrest mechanism of an automobile seat.

The return spring is a spiral leaf spring, usually called a spring, which is embedded in a reclining device, which is the back of a car seat, which serves to fold back and recover the back. Is designed to produce torque.

The return spring for automobile seats is made of carbon steel and forms a film on the surface for corrosion resistance and rust resistance.The return spring embedded in the reclining device is a form in which a thin metal plate is wound in a spiral shape and the metal plate and the metal plate are in contact with each other. Since the wear and tear can cause unpleasant sounds and the like upon contact, the lubricity and abrasion resistance of the metal surface of the return spring are required.

The surface treatment after the spring is manufactured using tin, zinc plating, chromium or nickel plating, phosphate coating, film formation such as chromate, nitrate and molybdenum salt, electrolytic polishing, general painting and epoxy painting. In order to satisfy the requirements as a return spring and to consider economical and environmental pollution, it can form corrosion resistance, abrasion resistance and lubricity by forming phosphate coating film and alkali metal salt on return spring.

Ultrasound is a sound wave whose frequency exceeds 20 Hz to 20,000 Hz, which is an audible frequency, and is transmitted as a medium using gas, liquid, and solid. Ultrasonic waves of 20 kHz to 2000 kHz are used for dispersibility enhancement and chemical reaction active fields, and ultrasonic waves of 2000 kHz or more are used for medical purposes.

The chemical activity produced by the application of ultrasound to the compound is due to cavitation in the liquid medium by repeated compression and expansion by the negative pressure of the ultrasound.

Cavitation occurs when ultrasonic waves are irradiated into the liquid phase. The ultrasonic waves vibrate to explode and expand the solution while rapidly evolving a portion of the solution to form bubbles in the solution and then explode and disappear. The size of the bubble is a micro-scale, the generation, explosion, and extinction of a myriad of micro-bubbles repeatedly, the inside of the bubble is formed at the temperature of thousands of degrees and the extreme conditions of more than 1000 atm and the inside of the bubble and the outside of the bubble Dispersion and activity of chemical substances, thermal decomposition of organic substances, and oxidation of radicals are performed.

Therefore, the proper use of ultrasonic waves can effectively disperse the reactants to achieve homogenization of the reactants and speed up the reaction.

 In order to impart the lubricity required for the return spring, when the return spring is immersed in the reaction tank and the soap layer formation reaction is induced in the bath, a soap component is applied to the surface of the return spring to give lubricity. Soap is a metal salt of saturated or unsaturated fatty acid. Soap used for general life is water-soluble alkali metal salt, and other metal salts which are not water-soluble are called metal soap and various industrial products such as paint additives, desiccants, and plastic stabilizers. It is used as.

   [Document 1] Steel phosphate coating technology. Lee Woon Kwan: Korean Journal of Surface Engineering, Vol. 13, No. 4. 1980. pp. 228-243

[Document 2] Principle of phosphate coating agent during metal surface treatment process. Kim Jong Gun: The Korean Institute of Surface Engineering. Metal Surface Treatment, Vol. 3, No. 1, 1970. Pp. 22--23

[Document 2] Process concept of phosphate coating agent. Jong Gun Kim. Korean Institute of Surface Engineering. Metal Surface Treatment, Vol. 5, No. 3, 1972. Pp. 86--88

Document 4 Summary of Surface Technology. Korea Surface Treatment Technology Information Center (on-line)

Document 5: Publication 90-000302. Date of Publication 1990. 01.25. Method of forming chemically treated phosphate film on steel surface

       Reference 6 Registration 10-0212400. Registration date 1999.05.10. Phosphate treatment method and treatment liquid on metal surface

       [Reference 7] J. Korean Eng. Chem. Vol 20, No3, Jun 2009, 322-328

Reference 7 Registration 10-0475774. 2005. 03. 02. Method and device for removing air bubbles on substrate surface using ultrasonic waves

The return spring, which is a part of the reclining device provided in the car seat, requires corrosion resistance, rust resistance, lubrication, and abrasion resistance. To meet this purpose, a compact, solid and rapid zinc phosphate film is formed using ultrasonic vibration energy. The problem to be solved is to find a high quality coating treatment method of the surface of the return spring to form high quality rust prevention, corrosion resistance and abrasion resistance, and to form a dense metal soap layer to lubricate the surface of the return spring.

It consists of a washing step, a phosphate film forming step and a lubricating film forming step, and the corrosion resistance to the surface of the spring flat iron 11 of the return spring 10 by promoting the reaction using ultrasonic vibration in the phosphate film forming and lubricating film forming step Phosphate coating and lubricating film are formed to have rust resistance, abrasion resistance and lubricity.

As a cleaning step for cleaning the return spring 10,

Degreasing the return spring (10) at a concentration of 5 to 10 g / l of sodium hydroxide and a temperature of 65 to 75 ° C. in a reaction bath, followed by washing with degreasing and washing with a concentration of 20 to 25% by weight of hydrochloric acid and a temperature of 20 ° C. 3 to 5 minutes of immersion in pickling and washing after pickling, and the concentration of calcium hydroxide 1.5 ~ 2.0g / L, the temperature is immersed in 20 ℃ 3 to 5 minutes, and neutralizing,

Forming a phosphate coating film,

Zinc-based phosphate was added to a reaction bath containing a phosphate solution, and titrated to 25-27 points of acidity and 3.0-4.0 points of free acid, and concentration of 0.5-1.0 g / l as an oxidizing agent in the mixture of zinc-based phosphate and phosphate solution. Phosphorus chlorine is further mixed, the ultrasonic frequency is 40 kHz to 100 kHz, the output is 100 to 200 W based on 60 liters of the mixed liquid, and the temperature is immersed in the return spring 10 at 80 to 90 ° C. Forming a phosphate coating,

As a step of forming a lubricating film,

Washing the return spring formed with phosphate-coated film, adding sodium nitrite having a concentration of 3.0 to 3.5 g / l, maintaining the mixture at 20 ° C. for 3 to 5 minutes, and neutralizing the stearic acid with a concentration of 80 to 85 g / l in the ultrasonic reactor 40. The mixture is immersed and mixed with an excess concentration of 120 to 130 g / l acetate and 100 to 110 g / l ethanol, and the frequency of the ultrasonic wave is 40 kHz to 100 kHz and the output is 100 to 200 W based on 60 liters of the mixed liquid. Maintaining it at 75 degreeC and including the step of forming the lubricating film of a metal soap component in the surface of the return spring in which the phosphate film was formed is a means of solving the subject.

Phosphate film and metal soap layer formed by the general process has a problem that the surface is rough and the hardness is poor, and the lubrication property is not maintained for a long time.By forming the phosphate film and the lubricating layer using the vibration energy of ultrasonic waves, each reaction time It is possible to form a high-quality phosphate film and a lubricating layer which is dense, solid and durable while reducing the weight.

1 is an enlarged view of a return spring of a reclining apparatus of a seat;
Figure 2 is a process chart for the formation of phosphate film of the return spring using ultrasonic vibration.
Figure 3 is a plan view of the ultrasonic reactor.
(b) is an operating state of the ultrasonic reactor.

1 is an enlarged view of a reclining apparatus 20 for an automobile seat in which a return spring 10 coated with a phosphate coating film and a lubricating film is mounted according to the present invention.

When the rider pulls the return handle 21 to recover the backrest forward from the seat 30, the backrest is restored forward by the restoring force of the return spring 10 of the reclining apparatus 20.

When the rider pulls the return handle 21 to lean the back back from the seat 30, the reclining apparatus 20 is released and the back back is leaned back. At this time, the return spring 10 is compressed to decrease the diameter and the return spring. The spring flat irons 11 of 10 come into contact with each other and rub, and an unpleasant friction sound is generated.

In order to reduce the friction noise, the lubricity and abrasion resistance of the surface of the spring flat 11 of the return spring 10 are required. Therefore, a phosphate coating film of zinc phosphate type having excellent abrasion resistance can be formed by providing corrosion resistance and polishing. Metal soap, a metal salt, is placed on the surface in order to make it castle.

Ultrasound is a sound wave whose frequency exceeds 20 Hz to 20,000 Hz, which is an audible frequency, and is transmitted as a medium using gas, liquid, and solid. Ultrasonic waves of 20 kHz to 2000 kHz are used for dispersibility enhancement and chemical reaction active fields, and ultrasonic waves of 2000 kHz or more are used for medical purposes.

The chemical activity produced by the application of ultrasound to the compound is due to cavitation in the liquid medium by repeated compression and expansion by the negative pressure of the ultrasound.

Cavitation occurs when ultrasonic waves are irradiated into the liquid phase. The ultrasonic waves vibrate to explode and expand the solution while rapidly evolving a portion of the solution to form bubbles in the solution and then explode and disappear. The size of the bubble is micro scale, and numerous micro bubbles are repeatedly generated, exploded, and extinguished. At this time, the inside of the bubble is formed at a temperature of thousands of degrees and an extreme condition of more than 1000 atm. Dispersion and activity of chemical substances, thermal decomposition of organic substances, and oxidation of radicals are performed.

Therefore, the proper use of ultrasonic waves can effectively disperse the reactants to achieve homogenization of the reactants and speed up the reaction.

Phosphate coating is one of the most used metal surface treatment methods in the industry as a surface treatment method to improve the physical and chemical properties by treating the surface of iron.

When phosphate (H3PO4) meets an alkaline solution, phosphate is produced. Phosphate is a tribasic acid and has three types of phosphates:

The primary phosphate is water soluble in any alkali metal salt, and the second and third phosphate salts are insoluble except the alkali metal and ammonium salts, so these properties are used to form a phosphate coating.

When phosphate is immersed in a phosphate solution, it dissociates itself at a certain concentration and temperature. The dissociation degree varies depending on the type of metal salt and is also affected by temperature. Forming a chemical conversion film to change the surface properties of the object to be surface-treated with a metal salt having a temperature setting.

The present invention uses a zinc-based, manganese-based and iron phosphate as a metal salt to form a phosphate film on the surface of the iron product, and on the formed phosphate film to form a metal soap layer as a lubricating film using ultrasonic vibration energy in the film It can promote the formation reaction and make the density of phosphate coating layer and metal soap layer more firm and even.

This reaction is an equilibrium when there is no object to be coated on the surface. When the object of iron (Fe) is immersed in this liquid, dissociated phosphoric acid (H3PO4) is dissolved in iron as in the following equation ④. The surface is eroded, eluted with Fe (H2PO4) 2, and hydrogen gas is generated.

④ When the concentration of Fe (H2PO4) 2 in the solution rises and the limit is reached, Fe (H2PO4) 2 dissociates, resulting in poorly soluble ferric phosphate (FeHPO4), which reduces free phosphoric acid (H3PO4). It is extinguished and extracted in the form of the second phosphate (Zn 2 HPO 4) and the third phosphate (Zn 3 (PO 4)) to form a phosphate coating on the surface of the iron object.

The material of the phosphate coating film is a salt of zinc divalent metal, which is the first phosphate, to make a first phosphate solution like phosphoric acid to immerse the return spring, which is carbon steel, and react for 10 minutes at 85˚C without applying ultrasonic vibration. When the surface of the return spring is corroded by the chemical reactions shown in ①, ②, ③, and ④, the second and third phosphates are formed on the surface of the spring flat iron 11.

Usually, zinc, manganese and iron phosphates are used as the coating material of phosphate coating film. However, when phosphate coating is made using manganese phosphate, a thick film with a thickness of 10 to 20um is formed. However, if the phosphate film is formed using zinc phosphate, the thickness of the film is thin, but the metal soap component, which is a metal salt, can be additionally formed on the formed phosphate film to improve the lubricity of the surface. In this case, zinc base phosphate coating is used as the undercoat, and fatty acid, tin acetic acid and alcohol capable of forming a tin metal soap layer, which is one of metal salts, are immersed and applied.

The process of forming the phosphate-encapsulating film and lubricating film of the return spring consists of three steps: washing step, phosphating film-forming step, and lubricating film forming step. It is washed with an ultrasonic cleaner and DI water and neutralized with calcium hydroxide.In the phosphate film forming step, a zinc phosphate is added to the phosphate solution of the reaction tank and an oxidizing agent to remove hydrogen gas generated as a result of the reaction. It is added together to form a phosphate coating film, in which a bath type ultrasonic reaction tank is formed and reacted to increase the reaction rate and improve the quality of the film resulting from the reactants.

In the phosphate film formation reaction, hydrogen bubbles are generated on the surface of the return spring as a result of the chemical reaction according to the equation ④, but these bubbles slow the reaction rate but are easily separated from the surface of the return spring by the vibration of ultrasonic waves. As the accelerator is added to the reactor together, it binds and disappears faster, resulting in a much faster rate of phosphate film formation on the surface of the return spring.

After the phosphate coating is formed, it is washed with distilled water and neutralized with sodium nitrite to complete.

Finally, in the lubrication film forming step, a dense and durable tin metal soap layer is prepared by adding stearic acid, tin acetate, and alcohol, which can generate metal salts, and by vibrating with low power ultrasonic waves to promote the formation of a tin metal soap layer, which is a metal salt. It is formed on this phosphate coating layer.

Table 1 below is a process sequence for forming a zinc-based phosphate coating film on the return spring 10. Each reaction is carried out in each reaction bath. Alkaline washing with sodium hydroxide and washing with water, acidic washing with hydrochloric acid and ultrasonic washing with pure water and neutralizing with alkali calcium hydroxide.

A phosphate mixture is prepared to form a phosphate film on the surface of the spring flat iron (11). Zinc-based phosphate is added to the phosphate solution, and the acidity is 25 to 27 points and dissociation acid is 3.5 to 4.0 points. The return spring 10, which is an object to be formed, is immersed in a low-power ultrasonic reaction tank of 100 to 200 W based on 60 liters of the reaction tank, and the phosphate film is formed when the temperature is reacted at about 85 ° C. for 1 to 2 minutes.

In general, the most important factors affecting the quality of the film in the formation of phosphate coating are the concentration of acidity and dissociation acidity.

The acidity represents the total acid content in the phosphate solution in which phosphate is added.Measurement method is to neutralize when 10cc of solution is taken and titrated with 0.1N sodium hydroxide using PP as the indicator. The amount of sodium hydroxide at that point (ml)

Dissociative acidity is the amount of free acidity in the phosphate solution to which phosphate is added.The amount of sodium hydroxide at the time of neutralization when 10 cc of solution is taken and titrated with 0.1 N sodium hydroxide using bromine phenol blue (BPB) as an indicator (ml ) Is that.

The quality of the phosphate film is affected by two parameters: acidity and free acidity.In the case of free acidity, when the concentration is high, the reaction time, that is, the time required for the chemical conversion of the surface of the spring flat iron 11, becomes long and the corrosion resistance may decrease. In addition, even when the concentration is low, corrosion resistance can be reduced.

When the acidity is low, that is, when the phosphate mixture is diluted excessively, a large amount of sediment is generated, and the loss is large. When the acidity is high, the reaction time is long, the corrosion resistance is decreased, and the surface state is rough and dark. .

Ultrasonic reactor for forming the phosphate film is possible in many forms, but the form used in the present invention is a bath (bath) type in which a plurality of ultrasonic vibrators 50 are provided at the bottom of the reactor, the high-frequency oscillator 60 in FIG. In operation, 2 * 5 = 10 ultrasonic vibrators 50 provided at the lower portion of the ultrasonic reactor 40 vibrate, and ultrasonic vibrations generated at the lower end of the ultrasonic reactor 40 propagate upwards. At the interface 45, which is a surface where air is in contact with each other, the light is reflected according to the difference in refractive index between the liquid and the gas, and then is reflected back to the downward direction, whereby the distance between the bottom surface of the ultrasonic reactor and the surface of the phosphate reaction solution is used. When standing at an integer multiple of one-half the wavelength of the ultrasonic wave, standing waves are generated, which makes it possible to transmit ultrasonic waves more uniformly. In this case, the pulsation phenomenon, which is a nonuniform ultrasonic vibration in the reaction solution, may occur due to interference with the reflected sound waves, and the quality of the phosphate coating may be deteriorated. 40) Constantly manage the distance from the bottom of the lower part to an integer multiple of 1/2 of the ultrasonic wavelength.

The frequency used in the phosphate film forming reactor used in the present invention is 40 kHz. The speed of sound waves in the solution is a multiple of the rate of air in the water, but it is 1500 m / sec in sea water and this also depends on the temperature of the solution. The approximation of the wavelength length using the propagation speed is as follows.

1500 m / sec = 40,000 Hz * Wavelength

-> Wavelength = 1500/40000 = 0.0375m ~ 3.75cm

In other words, when the 40kHz ultrasonic wave propagates in the seawater, the wavelength is about 3.75cm

The specific gravity of the phosphate solution is about 1.9, which is higher than the average specific gravity of 1.025 in seawater, resulting in longer wavelengths than 3.75 cm.

Even if the specific gravity and density of the medium increases, the frequency of propagation is constant, but the speed of sound waves increases.Assuming the propagation speed of sound waves in phosphate solution is 1600m / sec, the wavelength is about 4cm. The interfacial height 61 of the phosphate solution of the phosphate reactor is determined as the distance. In the present invention, the interface height 61 after the phosphate solution and the phosphate is added and the oxidant is added to 40 cm, which is an integer multiple of 2 cm,

In the immersion process, the interface height (61) of the total solution in which tin acetate and ethanol were added to stearic acid is about 0.85 at 70 degrees of stearic acid, and 0.79 at 20 degrees of ethanol, so the speed of sound waves in these mixtures is 1500m. When the approximate value is obtained assuming a propagation speed of 1400 m / sec lower than / sec, the length of the wavelength in the mixture is about 3.5 cm, and the interface height 61 of the mixture in the ultrasonic reactor 40 is an integer multiple of 3.5 cm. It is cm.

When ultrasonic vibration is applied to the reaction solution by using the ultrasonic vibrator 50, the temperature of the solution increases. In the phosphate formation reaction of the present invention, the temperature is controlled based on 85 degrees, but the temperature is increased by ultrasonic vibration. The temperature controller used in the reactor requires a feedback type temperature control device that directly measures the temperature of the solution and controls the temperature, and a water jacket that can circulate the coolant in the reactor shell in case the temperature rises too high. A reactor equipped with 80 is used.

When the vibration of the ultrasonic wave is transmitted to promote the phosphate formation reaction and the metal soap layer formation reaction, if the vibration is too strong, the film is not formed due to excessive vibration of the surface of the return spring 10. Therefore, the output of the ultrasonic oscillator is weakened and uniform in the solution. In the present invention, the vibration is to be transmitted to 100 ~ 200W for the reaction liquid of 60 liters, but this output needs to be adjusted according to the shape of the reaction vessel or the arrangement position of the ultrasonic vibrator, so the ultrasonic output is experimentally Decide

In the formula (4) described in the background art, hydrogen gas (H2) is generated as a reaction result, and the hydrogen gas remains in the form of small bubbles on the surface of the return spring 10, delaying the phosphate film formation reaction and making the film state uneven. Since it can be roughened, sodium nitrate (NaNO2) or sodium chlorate (NaClO3) is added as an oxidizing agent to remove hydrogen gas, which shortens the film formation time and forms a higher quality film. As a result, hydrogen bubbles generated on the surface of the return spring are easily released into the reaction solution, and are combined with the oxidizing agent in the solution to extinguish.

In the present invention, in the formation of the phosphate film, sodium chloride chlorine is added at a concentration of 0.5 to 1.0 g / l as an oxidizing agent to promote the film forming reaction.

After the formation of the phosphate film, the return spring 10 is washed with distilled water and neutralized with sodium nitrite, and then a metal salt, ie, a metal soap, is applied to the surface of the return spring 10 in order to lubricate the surface of the return spring. In order to form a mixture of fatty acids stearic acid, tin acetate and ethanol in the concentration of 80 ~ 85g / ℓ, 120 ~ 130g / ℓ, 100 ~ 110g / ℓ, respectively, in the ultrasonic reactor 40 and then about 2 ~ at 70 ℃ When ultrasonic vibration is applied for 3 minutes, a solid tin metal soap is formed on the phosphate film on the surface of the return spring 10 and the lubricating property is formed.

After the phosphate coating and the lubricant treatment of the return spring 10 are completed, the temperature is 75 to 80 ° C. and finally dried for about 30 minutes with a hot air blower to form the phosphate coating on the surface of the return spring 10 and the lubricating film. Complete the forming work.

REFERENCE SIGNS LIST 10 Return spring 11 Spring flat iron 20 Reclining device 21 Return handle 30 Sheet 40 Ultrasonic reactor 45 Interface 50 Ultrasonic oscillator 60 High frequency oscillator 61 Interface height 65 Standing wave 70 Temperature controller 80 Water jacket 85 : Basket

Claims (4)

In the method for surface treatment of the return spring 10, which is inserted into the reclining device 20 of the automobile seat 30 and made of carbon steel,

Washing step; and, phosphate film forming step; and, lubricating film forming step; and drying step; but sequentially made, in the phosphate film forming step and lubricating film forming step, the return spring by promoting the reaction by using ultrasonic vibration A method of forming a phosphate coating film of a return spring using ultrasonic vibration, comprising forming a phosphate coating film and a lubricating film on the surface of the spring flat iron (11) to have corrosion resistance, rust resistance, abrasion resistance, and lubricity.
The method of claim 1,
As a cleaning step for cleaning the return spring 10,
Degreasing the return spring 10 at a concentration of 5-10 g / l and a temperature of 65-75 ° C. in a reaction bath; And
After degreasing, washing with water and concentration of hydrochloric acid 20-25 wt%, temperature immersed at 20 ° C. for 3-5 minutes, and pickling; and
After washing with water and washing with water, the concentration of calcium hydroxide was 1.5 to 2.0 g / l, and the temperature was neutralized by immersion at 20 ° C. for 3 to 5 minutes;
Formation method of the phosphate-ized film of the return spring using ultrasonic vibration, comprising.
3. The method according to claim 1 or 2,

After cleaning the return spring (10) to form a phosphate film in the ultrasonic reactor 40,
Adding zinc-based phosphate to the reaction bath containing the phosphate solution and titrating the acidity to 25-27 points and the free acidity to 3.0-4.0 points; and
To the mixed solution of the zinc-based phosphate and the phosphate solution, sodium chlorate having a concentration of 0.5 to 1.0 g / l is further mixed as an oxidizing agent,
Forming a phosphate film on the surface of the spring flat iron 11 by immersing the return spring 10 at a frequency of 40 kHz to 100 kHz and an output of 100 to 200 W based on 60 liters of mixed liquid and a temperature of 80 to 90 ° C .; To
Formation method of the phosphate-ized film of the return spring using ultrasonic vibration, comprising.
3. The method according to claim 1 or 3,

As a step of forming a lubricating film,
Washing the return spring formed with a phosphate film and neutralizing the solution by adding sodium nitrite having a concentration of 3.0 to 3.5 g / l and maintaining the solution at 20 ° C. for 3 to 5 minutes; and
Stearic acid with a concentration of 80-85 g / l, acetate with a concentration of 120-130 g / l, and ethanol with a concentration of 100-110 g / l are immersed in the ultrasonic reactor 40, and the frequency of the ultrasonic wave is 40 kHz to 100 kHz, and the output is a mixed solution. 100 to 200W based on 60 liters and the temperature of the mixed solution is maintained at 65 ~ 75 ℃, forming a lubricating film of the metal soap component on the surface of the return spring is formed with a phosphate film;
Formation method of the phosphate-ized film of the return spring using ultrasonic vibration, comprising.

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