Ultrasonic sealing apparatus for use in bag filling and packaging machine

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 steps, 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, which detects 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;
• a control unit controlling the ultrasonic sealing apparatus body on a basis of a signal from the sensor;
• and
• an anvil support member,
• wherein the anvil is secured, through an insulator, to said 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 wiring to detect electrical conduction between the horn and the anvil or a change in electrical resistance occurring between the horn and the anvil when the horn and the anvil move relative to each other;
• wherein, when the detection sensor does not detect the electrical conduction or a change in the electrical 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 electrical 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,
• a disconnection detecting device detecting a disconnection in the wiring connecting the horn and the anvil to the detection sensor;
• wherein, when the disconnection detecting device detects a disconnection in the wiring, 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;
• the disconnection detecting device comprises a resistor,
• the detection sensor is connected to the horn via a first wiring and is connected to the anvil via a second wiring, and
• the resistor is electrically connected to the horn and the anvil via a third wiring,
• the resistor, the horn, the anvil, the detection sensor, and the wiring connecting the horn and the anvil to the detection sensor constituting a closed circuit, and
• wherein the disconnection detecting device further comprises a variable resistor provided on at least one of the first wiring and the second wiring.