Introduce you to several methods for cleaning the resid […]
Introduce you to several methods for cleaning the residual oil on the surface of fasteners. These methods are mainly for the residual oil of the cooling oil attached to the surface of the fastener during cold heading or cutting, and the residual oil on the surface of the fastener after quenching in the heat treatment oil. Clean.
1. Alkaline water cleaning method
Simple alkaline water cleaning is a direct heating or indirect heating cleaning tank, and the cleaning solution is 3% to 10% N2CO3 or NaOH aqueous solution. The main disadvantage of the alkaline water cleaning method is that the cleaning effect is not very good, especially the blind holes and grooves of the fasteners are prone to stains and residues. The wastewater generated from alkaline water cleaning must be neutralized, and waste oil must be recycled, and it can be discharged only when it meets the relevant environmental protection requirements.
Two, metal cleaning agent cleaning method
In order to overcome the shortcomings of the alkaline water cleaning method and improve the cleaning effect, a special metal cleaning agent can be used at present. The cleaning agent is diluted into a 1%~3% solution in water at 40~70℃, and the fasteners are soaked in the solution 15 ~20min, then rinse with hot water, and then use a dehydrator for dehydration treatment. Can be used in the washing machine. The disadvantages of the metal cleaner cleaning method are that it is expensive, has an unpleasant smell, has a certain corrosive effect on fasteners, and waste water pollutes the environment. Therefore, it is necessary to treat the waste water and recycle the waste oil.
3. Organic solvent cleaning method
Use organic solvents such as trichloroethane and trichloroethylene to clean with good cleaning effect. When the quenched fasteners are cleaned by soaking or spraying under normal pressure, the volatilization and splashing of organic solvents pollute the environment. For this reason, a complete set of devices for the closed decompression solvent vacuum cleaning method is used, and the air is exhausted by a vacuum pump. The fasteners are in contact with high-density solvent vapor without air to further improve the cleaning effect, and the solvent and oil are recovered by vacuum distillation. . The solvent content in the recovered oil is reduced from 20% to below 4%, which is lower than the 50ppm of the environmental sanitation regulations for trichloroethylene.
4. Burning degreasing method
Cold heading or machined fasteners need to be cleaned of oil on the surface before entering the heat treatment process. For this reason, the fastener can be heated to 350~400℃ in the degreasing furnace to vaporize or burn the oil, so as to achieve the purpose of degreasing the fastener or the effect of dephosphorization on the surface. The combustion degreasing method is only suitable for cleaning before heat treatment. It can also clean light, low viscosity and low boiling point oils such as cooling oil and anti-rust liquid. After the heavy quenching oil with high viscosity and high boiling point burns, there will be a large amount of residue and carbon black attached to the surface of the fastener, which cannot achieve the purpose of cleaning.
For fasteners that require a high degree of surface cleanliness, such as aviation bolts, automobile engine connecting rod bolts, etc., vacuum or ultrasonic cleaning technologies are currently used to replace the commonly used chlorinated hydrocarbon substances that have a destructive effect on the atmospheric ozone layer as a solvent cleaning method. , It can realize effective environmental cleaning.