Method for filling with metallic sodium
Provided is a method for filling a stem-side hollow area of an engine valve with metallic sodium. The method includes injecting melted metallic sodium into a cylinder having a larger diameter than an inner diameter of the hollow area of the engine valve, forming a solidified metallic sodium rod having a substantially uniform structure in the cylinder, inserting the metallic sodium into the hollow area of the engine valve through a nozzle having a small diameter, and sealing the engine valve.
1. A method for filling a hollow area of a hollow engine valve with metallic sodium, the method comprising:
injecting melted metallic sodium into a cylinder having a larger diameter than an inner diameter of the hollow area of the engine valve under a directional solidification condition, at a speed faster than a speed at which a droplet solidifies, and in a form in which no discontinuity occurs;
forming a solidified metallic sodium rod having a substantially uniform structure in the cylinder;
inserting metallic sodium into the hollow area of the engine valve through a nozzle shaped die while keeping the uniform structure of the metallic sodium rod;
cutting the inserted metallic sodium; and
sealing the engine valve.
2. The method for filling with metallic sodium according to claim 1 , wherein the melted metallic sodium is injected into the cylinder with a boundary of the metallic sodium in the cylinder kept in a semi-solidified condition.
3. The method for filling with metallic sodium according to claim 1 , wherein the melted metallic sodium is injected into the cylinder by dripping.
4. The method for filling with metallic sodium according to of claim 1 , wherein an inner diameter of the cylinder is within a range of 20 mm to 50 mm, a temperature of the metallic sodium is within a range of 180° C. to 250° C., and an injection speed is within a range of 150 g/min to 300 g/min.
5. A method for purifying metallic sodium including organic solvent and filling a hollow area of a hollow engine valve with purified metallic sodium, the method comprising:
placing metallic sodium in a melting tank which is sealed;
heating the melting tank under reduced pressure to vaporize and remove the organic solvent coating the metallic sodium;
injecting the metallic sodium in a melting state into a cylinder having a larger diameter than an inner diameter of the hollow area of the engine valve under a directional solidification condition, at a speed faster than a speed at which a droplet solidifies, and in a form in which no discontinuity occurs;
forming a solidified metallic sodium rod having a substantially uniform structure in the cylinder;
inserting metallic sodium into the hollow area of the engine valve through a nozzle shaped die while keeping the uniform structure of the metallic sodium rod;
cutting the inserted metallic sodium; and
sealing the engine valve.
6. The method for filling with metallic sodium according to claim 2 , wherein the melted metallic sodium is injected into the cylinder by dripping.
7. The method for filling with metallic sodium according to claim 2 , wherein an inner diameter of the cylinder is within a range of 20 mm to 50 mm, a temperature of the metallic sodium is within a range of 180° C. to 250° C., and an injection speed is within a range of 150 g/min to 300 g/min.
8. The method for filling with metallic sodium according to claim 3 , wherein an inner diameter of the cylinder is within a range of 20 mm to 50 mm, a temperature of the metallic sodium is within a range of 180° C. to 250° C., and an injection speed is within a range of 150 g/min to 300 g/min.
9. The method for filling with metallic sodium according to claim 4 , wherein the inner diameter of the cylinder is within a range of 20 mm to 40 mm.
10. The method for filling with metallic sodium according to claim 7 , wherein the inner diameter of the cylinder is within a range of 20 mm to 40 mm.
11. The method for filling with metallic sodium according to claim 8 , wherein the inner diameter of the cylinder is within a range of 20 mm to 40 mm.