| 摘要 |
PURPOSE:To obtain an electrode having cylinders supplied with the desired true roundness at the ends of openings by a construction wherein three cylinders close to each other are formed en bloc and a uniform ring channel is provided at the base of the central cylinder, while a ring channel wider and deeper on the side far from the central cylinder is provided at the base of the cylinder located on either side. CONSTITUTION:Three cylinders 19a-19c are formed en bloc in such a way that their height is, for instance, 0.5 or more time greater than their inside diameter. A forming mold is used to provide press-forming and then a mandrel is used to form a taper 24 of which the inside diameter toward the opening at the bases of the cylinders 19a-19c is enlarged. In addition, a forming die is employed to form ring channels 25a-25c along the outside periphery of the bases. In so doing, the flow of metal is generated according to the thickness of the base and the opening of the base of the cylinder can form an electron lens having the desired true roundness. |
