Packaging machine

Abstract

A packaging machine, includes a pair of sealing jaws that sandwiches and seals a sealed portion of a tubular film. The packaging machine is provided with a first rotating shaft for supporting one sealing jaw, a second rotating shaft for supporting the other sealing jaw, a rotary encoder, and an entrapment determination part. When the first rotating shaft and the second rotating shaft approach or move away, the rotary encoder measures the movement amount of the first rotating shaft in relation to the second rotating shaft in an approaching direction or a moving away direction. The entrapment determination part determines whether or not articles are present in the sealed portion based on the movement amount.

1 . A packaging machine in which a pair of sealing members is configured to sandwich and seal a sealed portion of a film, the packaging machine comprising:
 a first support part configured to support one of the sealing members;   a second support part configured to support the other of the sealing members;   a movement amount detector configured to measure the relative movement amount of the first support part in relation to the second support part in an approaching direction or a moving away direction, when the first support part and the second support part approach or move away; and   an entrapment determination part configured to determine whether or not articles are present in the sealed portion based on the relative movement amount.   
     
     
         2 . The packaging machine according to  claim 1 , wherein
 the pair of sealing members are configured to be rotated in a circular orbit, whereby the sealing members sandwich and laterally seal the film along a direction intersecting a first direction, the film being conveyed in the first direction and formed into a tubular shape.   
     
     
         3 . The packaging machine according to  claim 2 , wherein
 the first and second support parts are rotating shafts for rotating the sealing members.   
     
     
         4 . The packaging machine according to  claim 2 , further comprising:
 a fluid-pressure-utilizing pressing mechanism configured to constantly press the first support part toward the second support part so that the film is to be pressed between the sealing members when the film is sandwiched between the pair of sealing members.   
     
     
         5 . The packaging machine according to  claim 1 , wherein
 each of the first and second support parts is configured to support the sealing member at a first-end side and a second-end side in the longitudinal direction of a surface with which the sealing members sandwich the film;   the movement amount detector is configured to measure, as the relative movement amount, a first relative movement amount of the first support part in relation to the second support part at the first-end side, and a second relative movement amount of the first support part in relation to the second support part at the second-end side; and   the entrapment determination part is configured to determine whether or not articles are present in the sealed portion based on the first relative movement amount and the second relative movement amount.   
     
     
         6 . The packaging machine according to  claim 1 , wherein
 the entrapment determination part is configured to determine whether or not articles are present in the sealed portion based on statistics of the relative movement amount measured during a predetermined time period by the movement amount detector.   
     
     
         7 . The packaging machine according to  claim 6 , wherein
 the entrapment determination part is configured to determine whether or not articles are present in the sealed portion based on an average value of the relative movement amount measured during the predetermined time period by the movement amount detector.   
     
     
         8 . The packaging machine according to  claim 1 , wherein
 the pair of sealing members are configured to be rotated in a circular orbit, whereby the sealing members sandwich and laterally seal the film along a direction intersecting a first direction sequentially from the forward side in the first direction, the film being conveyed in the first direction and formed into a tubular shape; and   the entrapment determination part is configured to determine whether or not articles are present in the sealed portion, both in a first time period beginning at a start of a sealing action by the sealing members and ending at a first time point and in a second time period beginning at a second time point after the first time point and ending at a finish of the sealing action, within the single sealing action.   
     
     
         9 . The packaging machine according to  claim 1 , wherein
 the second support part is secured so as not to move in a direction toward or away from the first support part;   the first support part is capable of moving in a direction toward or away from the second support part; and   the movement amount detector is configured to measure the movement amount of the first support part in the direction toward or away from the second support part as the relative movement amount when the first support part moves toward or away from the second support part.