Longitudinal sealing mechanism

Abstract

A longitudinal sealing mechanism is adapted to seal an overlapped portion of a packaging material formed into a tubular shape with the overlapped portion extending along a conveying direction of the packaging material. The longitudinal sealing mechanism includes a contact section, a heating section and a receiving member. The contact section comes into contact with the overlapped portion of the packaging material. The heating section heats the contact section to perform longitudinal sealing of the overlapped portion to form a longitudinal seal portion. The receiving member abuts against the contact section with the overlapped portion of the packaging material being disposed therebetween. The contact section, the heating section, and the receiving member are arranged such that an amount of heat per unit time applied to the packaging material from the contact section decreases in a direction toward both sides of the longitudinal seal portion.

1 . A longitudinal sealing mechanism adapted to seal an overlapped portion of a packaging material formed into a tubular shape with the overlapped portion extending along a conveying direction of the packaging material, the longitudinal sealing mechanism comprising:
 a contact section configured and arranged to come into contact with the overlapped portion of the packaging material;   a heating section configured and arranged to heat the contact section to perform longitudinal sealing of the overlapped portion to form a longitudinal seal portion; and   a receiving member configured and arranged to abut against the contact section with the overlapped portion of the packaging material being disposed therebetween while the longitudinal sealing of the overlapped portion;   the contact section, the heating section, and the receiving member being configured and arranged such that an amount of heat per unit time applied to the packaging material from the contact section decreases in a direction toward both sides of the longitudinal seal portion in a direction perpendicular to the conveying direction of the packaging material.   
     
     
         2 . The longitudinal sealing mechanism according to  claim 1 , wherein
 the heating section and the receiving member each have a width substantially equal to a width of the longitudinal seal portion formed on the packaging material, and   the contact section has a width larger than the width of the longitudinal seal portion.   
     
     
         3 . The longitudinal sealing mechanism according to  claim 1 , wherein
 the receiving member has a width substantially equal to a width of the longitudinal seal portion.   
     
     
         4 . The longitudinal sealing mechanism according to  claim 1 , wherein
 the receiving member has a convex contact surface configured and arranged to face the overlapped portion of the packaging material so that both sides of the receiving member in a width direction are spaced apart from the contact section.   
     
     
         5 . The longitudinal sealing mechanism according to  claim 1 , wherein
 the contact section has a convex surface configured and arranged to face the overlapped portion of the packaging material so that the packaging material is spaced apart from the contact section at an area on an outer side of a contact portion of the contact section that contacts the longitudinal seal portion.   
     
     
         6 . The longitudinal sealing mechanism according to  claim 1 , wherein
 the heating section has a generally T-shape cross sectional shape in a plane perpendicular to the conveying direction of the packaging material with a side corresponding to a horizontal line of the T-shape being disposed adjacently to the contact section.   
     
     
         7 . The longitudinal sealing mechanism according to  claim 1 , wherein
 the contact section has a rotational belt structure that rotates around the heating section.   
     
     
         8 . The longitudinal sealing mechanism according to  claim 1 , wherein
 the contact section is integrally formed with the heating section to form a heater block member.