working principle of 1.

the cooling water bag is placed in the cuboid nitrate salt bath melt. during the quenching process of workpieces such as taps and round dies, the evaporation of tap water added to the water bag is used to take away the heat absorbed by the nitrate salt bath melt, so as to keep the temperature in the bath stable and achieve the purpose of continuous operation.

 

2. defects

This water bag is a cooler commonly used by tool factories in China from 1970 s to 1980 s. Its main disadvantages are as follows:

1. poor cooling effect

when the nitrate furnace works continuously, the heat taken away by the vaporization of the water in the bag is far less than the heat released by the quenching of the workpiece. in a short time, the temperature in the nitrate tank rises above 190 ℃, cause the workpiece quenching quality is not stable, can not be normal production.

2. Long startup time. Power waste is severe

when the nitrate furnace is out of use. 1/2~1/3 of the water is still in the water bag. If the nitrate furnace is melted again, it is bound to evaporate the water in the bag before the nitrate can melt. Generally, it takes 3~4 hours.

3. workers have high labor intensity

when the cooling performance of nitrate salt melt is reduced, the quenching hardness of the workpiece is insufficient or the hardness is uneven, the whole tank nitrate salt needs to be replaced, the water bag weighs 40kg, and the nitrate salt aging sediment adheres to the water bag, making it very difficult to take out.

ideas for 3. improvement

1. the workpiece is quenched into a nitrate salt tank, and the heat released increases the temperature of nitrate salt melt, which can accommodate 400kg of nitrate salt. generally, the production capacity of hand taps is 100 kg/h. It is assumed that the temperature after quenching is t = 0.92X 10 71.9 without cooling system, where X is the normal use temperature of nitrate salt melt, I .e. X-160 ~ 180 ℃.

2. according to the heat balance principle of QAc absorption 1 q phosphate salt discharge, the rising temperature difference t = 11. 7 & times is calculated; (860-X)/m water. m7K refers to the mass of water introduced. Here set the normal water temperature 18 ℃. The table is the correspondence between the two.

verification of 4. effect

from the table, the change of static water temperature is greater than that of flowing water. on the premise of ensuring that the temperature of nitrate salt melt is stable at 160~180 ℃, 200~400 kg/h of tap water is required to meet the temperature stability, and the effluent temperature is 38~58 ℃, so as to ensure the quality of the workpiece quenching.

uses flowing water to cool nitrate molten solution, uses water valve to control the flow rate, and uses 3/4in(lin = 0.0254 m) galvanized pipe to make cooling system. after production practice, the effect is good, which not only prolongs the service life of nitrate, it also ensures the stability of quenching quality.