| 摘要 |
PURPOSE:To prevent a glass disk from causing breakage by disposing a glass wool material large in size than the inner diameter of a glass disk, which is attached to the front face of a die as a front face lubricant, between the glass disk and a hot billet. CONSTITUTION:In addition to a glass disk 1 used as a front face lubricant in hot extrusion, a glass wool material 5 larger in size than the inner diameter of a die 2 is disposed between the glass disk 1 and a hot billet 3. When the billet 3 approaches in this state, a part of the material 5 with which the billet 5 comes into contact is first molten into a fluid state and begins to flow toward the front face of the billet 3. Next, when an extrusion is started after upsetting, the material 5 situated at the front end of the billet 3 is taken into the die 2 together with the billet 3 in a state of lying on the front end of the billet 3. Then the glass disk 1 begins to act as a front face lubricant, and is protected by the glass wool material 5 up to the time just before starting the extrusion and is prevented from causing breakage, etc. |
