Ultrasonic Sealing Apparatus For Use In Bag Filling And Packaging Machine

Abstract

A horn and an anvil are moved toward and away from each other by axially reciprocating a driving rod and thereby reciprocatingly rotating a forked lever in a predetermined angle range. The horn and the anvil are moved toward and pressed against each other with a predetermined force with a bag mouth b held therebetween. A sensor detects the position of a second mounting block secured to the rear end of a sliding shaft of the anvil, thereby detecting the distance between respective pressing surfaces and of the horn and the anvil, i.e. the thickness m of a portion of the bag mouth held between the pressing surfaces and. When the thickness m is not less than a predetermined threshold value M, a vibrator is activated to perform sealing. When the thickness m is less than the threshold value M, no sealing is performed.

What is claimed is: 
     
         1 . An ultrasonic sealing apparatus for use in a bag filling and packaging machine in which a bag is held by being gripped at its laterally opposite side edges with a pair of laterally spaced grippers and the bag held in this way is moved along a predetermined path to sequentially undergo predetermined packaging processes, the ultrasonic sealing apparatus comprising:
 an ultrasonic sealing apparatus body having a horn and an anvil which are movable toward and away from each other, the ultrasonic sealing apparatus body being disposed at a predetermined sealing step position in the bag filling and packaging machine;   a sensor disposed at the sealing step position to detect whether or not a mouth of a bag moved to the sealing step position is in a predetermined sealing enable position between the horn and the anvil; and   a control unit controlling the ultrasonic sealing apparatus body on a basis of a signal from the sensor.   
     
     
         2 . The ultrasonic sealing apparatus of  claim 1 , wherein the sensor detects a distance between respective pressing surfaces of the horn and the anvil that press the bag when the horn and the anvil are pressed against each other with the mouth of the bag held therebetween, and the control unit judges that the mouth of the bag is in the sealing enable position when the distance detected by the sensor is not less than a threshold value, and controls the ultrasonic sealing apparatus body to apply ultrasonic vibration to the horn, whereas, when the distance detected by the sensor is less than the threshold value, the control unit judges that the mouth of the bag is not in the sealing enable position, and controls the ultrasonic sealing apparatus body not to apply ultrasonic vibration to the horn. 
     
     
         3 . The ultrasonic sealing apparatus of  claim 2 , wherein the horn and the anvil move in linkage with each other, and the sensor detects the distance between the pressing surfaces by detecting a position of one of the horn and the anvil. 
     
     
         4 . The ultrasonic sealing apparatus of  claim 3 , wherein the ultrasonic sealing apparatus body has:
 a box-shaped frame supporting the horn and the anvil; and   a driving mechanism for operating the horn and the anvil, the driving mechanism being disposed in the frame;   the sensor being disposed in the frame and configured to detect a position of a detecting member moving together with the anvil.   
     
     
         5 . The ultrasonic sealing apparatus of  claim 1 , wherein the sensor is provided at a position corresponding to a lower-limit position where an edge of the mouth of the bag lies when the mouth of the bag is at a lower limit of the sealing enable position, and the control unit judges, when the sensor detects presence of the bag at the lower-limit position, that the mouth of the bag is in the sealing enable position, and judges, when the sensor does not detect presence of the bag at the lower-limit position, that the mouth of the bag is not in the sealing enable position. 
     
     
         6 . The ultrasonic sealing apparatus of  claim 1 , wherein the anvil is secured, through an insulator, to an anvil support member advancing and retracting relative to the horn;
 the sensor being a detection sensor that is electrically connected to the horn and the anvil through respective wirings to detect electrical conduction between the horn and the anvil or a change in electric resistance occurring between the horn and the anvil when the horn and the anvil move to respective positions closest to each other;   wherein, when the detection sensor does not detect the electrical conduction or a change in the electric resistance, the control unit judges that the mouth of the bag is in the sealing enable position, and controls the ultrasonic sealing apparatus body to apply ultrasonic vibration to the horn, whereas, when the detection sensor detects the electrical conduction or a change in the electric resistance, the control unit judges that the mouth of the bag is not in the sealing enable position, and controls the ultrasonic sealing apparatus body not to apply ultrasonic vibration to the horn.   
     
     
         7 . The ultrasonic sealing apparatus of  claim 6 , further comprising:
 a disconnection detecting device detecting a disconnection in the wirings connecting the horn and the anvil to the detection sensor;   wherein, when the disconnection detecting device detects a disconnection in the wirings, the control unit judges that the mouth of the bag is not in the sealing enable position, and controls the ultrasonic sealing apparatus body not to apply ultrasonic vibration to the horn.   
     
     
         8 . The ultrasonic sealing apparatus of  claim 7 , wherein the detection sensor detects a change in electric resistance, and the disconnection detecting device has a resistor electrically connected between the horn and the anvil, the resistor constituting a closed circuit, together with the horn, the anvil, the detection sensor, and the wirings connecting the horn and the anvil to the detection sensor;
 wherein, when the detection sensor does not detect a change in the electric resistance, the control unit judges that the bag is in the sealing enable position, whereas, when the detection sensor detects a change in the electric resistance, the control unit judges that the bag is not in the sealing enable position.   
     
     
         9 . The ultrasonic sealing apparatus of  claim 6 , further comprising:
 a variable resistor connected between the detection sensor and one of the horn and the anvil.   
     
     
         9 . The ultrasonic sealing apparatus of  claim 7 , further comprising:
 a variable resistor connected between the detection sensor and one of the horn and the anvil.   
     
     
         9 . The ultrasonic sealing apparatus of  claim 8 , further comprising:
 a variable resistor connected between the detection sensor and one of the horn and the anvil.   
     
     
         10 . An intermittently rotating bag filling and packaging machine comprising:
 the ultrasonic sealing apparatus of  claim 1 .   
     
     
         11 . An intermittently rotating bag filling and packaging machine comprising:
 the ultrasonic sealing apparatus of  claim 6 .