| 摘要 |
PROBLEM TO BE SOLVED: To improve a seal finishing by preventing bubbles from remaining on a sealed surface in heat-sealing a wrapping material. SOLUTION: A seal belt 12 is traveled synchronously with feeding of the wrapping material, and sealing heat is applied while contact-bonding a seam S of the wrapping material with a heater block in slide contact with an inner peripheral face of the belt 12. Since a heating surface of the heater block is formed to broaden along a traveling direction of the wrapping material in its sealing section, during a process that the material is sealed, a sealed region M which is heat-welded gradually increases to the maximum width W. Since air existing between the seams S is expelled to both sides of the sealed region M during such a sealing process, no bubbles remain in a sealed face after sealing is completed. |
