The core was cleaned by dissolving vibration by Ding Yi, and the effects of different NaOH solution concentration, excitation force and core heating temperature on the cleaning efficiency of dissolving vibration were studied. When the core heating temperature is 300℃, the influence curve of different NaOH solution concentration and excitation force (characterized by the angle of the eccentric block of the vibration motor, the same below) on the efficiency of dissolving vibration cleaning.

From Figure 10, it can be seen that the falling sand rate of the core increases with the increase of the NaOH solution concentration; when the NaOH solution concentration is 2.5-7.5 wt.%, the falling sand rate of the core first increases with the increase of the exciting force When the included angle of the eccentric block is 3/18, the falling sand rate is high; when the cleaning fluid is water, no reaction of lye dissolving the core occurs, and the falling sand rate is almost o. At this time, the magnitude of the exciting force has no obvious influence on the falling sand rate of the core sample, which shows that the vibration can only dynamically promote the cleaning speed of the core sample.

In the dissolution vibration cleaning process, the NaOH solution can play a role in dissolving and softening the core sample during the process of soaking the core. The silica sand (mainly SiO2) in the core and NaOH can undergo an exothermic chemical reaction. The heat released by the reaction will promote the reaction of SiO2 and NaOH. The sodium silicate produced by the reaction is soluble in water. The application of external force in this process will accelerate the release of sodium silicate from the surface of the core sample and remove the sodium from the core sample. The surface of the core sample falls off, thereby accelerating the progress of the reaction. From the analysis of reaction thermodynamics, the greater the NaOH solution concentration, the faster the reaction rate, and the greater the reduction in core mass within a certain period of time.

In the dissolution vibration cleaning process, vibration can make the reactants of silica sand and sodium hydroxide solution fall off the surface of the core sample quickly, and speed up the cleaning efficiency of the core. During the vibration cleaning, the castings are thrown up and down to collide with the machine body. At the relative speed, the sand falling rate is good. At this time, the vibration motor collides with the casting once every revolution of the main shaft. The time interval between the two impacts and the vibration period of the vibration motor The same, the cleaning effect is good.

In the actual casting process, the heating temperature of different parts of the core is different, so it is necessary to study the influence of different heating temperature of the core on the efficiency of dissolving vibration cleaning.

As the heating temperature of the core increases from 250°C to 400°C, the cleaning efficiency of the core gradually increases. The reasons for the influence of the heating temperature of the core on the cleaning efficiency are as follows:

• (1) Higher heating temperature will cause the bonding bridge of the coated sand core sample and the adhesive film of the coated silica sand to burn more seriously, and the adhesive film will have cracks and other defects, thereby reducing the core residue Strength, so easy to clean;
• (2) The burning loss of the adhesive film is more serious. The more exposed silica sand, the larger the contact area between silica sand and NaOH solution, the more favorable it is for the chemical reaction between silica sand and NaOH solution, thereby improving the cleaning efficiency of the core. Therefore, the heating temperature of the core has a greater impact on its cleaning after casting.

Link to this article：Research on Efficient Cleaning Equipment and Technology of Resin Sand Core

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