Ultrasonic carton sealer

Abstract

Ultrasonic sealing apparatus, including at least one anvil and at least one transducer opposed to the anvil to transmit ultrasonic energy to a workpiece clamped between them, is disclosed. The anvil and sealing horn each are reciprocated between an open position allowing a carton to pass and a closed position for sealing a closure. A biasing element is connected between the anvil or the horn and its drive to define the sealing pressure developed between the anvil and the horn. The biasing force can be adjusted without stopping the machine, by using an externally applied pneumatic force. The anvil has a backing element, a facing member, a body, and a resilient pad separating the body from the facing member. The backing element has a curved front surface facing the transducer. The back surface of the anvil pad is curved similarly to and bears against the curved front surface of the backing element. A fastener is provided for selectively fixing the anvil pad and the backing element together or allowing the anvil pad to shift along the curved surface of the backing element for aligning the anvil with respect to the transducer. The apparatus may also include cooling fluid passages within the facing member and extending through the anvil body and the resilient pad for carrying fluid from the source of cooling fluid through the facing member of the anvil. A method for aligning the anvils and transducers of a ultrasonic sealing apparatus as described above is also disclosed.