Ultrasonic welding method for sealing a thermoplastic cap to the neck of a thermoplastic container

• US 4,411,720 A
• Filed: 03/22/1982
• Issued: 10/25/1983
• Est. Priority Date: 03/22/1982
• Status: Expired due to Fees

• Current Assignee: Branson Ultrasonics Corporation (Emerson Electric Company)
• Original Assignee: Branson Ultrasonics Corporation (Emerson Electric Company)
• Inventors: Sager, Thomas B.
• Primary Examiner(s): WITYSHYN, MICHAEL G
• Application Number:
  US06/360,485
• Time in Patent Office: 582 Days
• Field of Search: 156/69, 156/73.1, 156/221, 156/580.1, 156/580.2, 264/23, 425/174.2, 228/110, 228/1 R, 53/471, 53/485, 53/489
• US Class Current: 156/69
• CPC Class Codes: B29C 65/08 using ultrasonic vibrations non-plastics element to plastics elements B29C65/645
• CPC Class Codes: B29C 66/114 Single butt joints
• CPC Class Codes: B29C 66/1222 comprising at least a lapped joint-segment
• CPC Class Codes: B29C 66/1224 comprising at least a butt joint-segment
• CPC Class Codes: B29C 66/131 Single flanged joints, i.e. one of the parts to be joined being rigid and flanged in the joint area
• CPC Class Codes: B29C 66/542 joining hollow covers or hollow bottoms to open ends of container bodies
• CPC Class Codes: B29C 66/7234 comprising a barrier layer
• CPC Class Codes: B29C 66/73921 characterised by the materials of both parts being thermoplastics
• CPC Class Codes: B29C 66/81431 comprising a single cavity, e.g. a groove
• CPC Class Codes: B29C 66/8322 Joining or pressing tools reciprocating along one axis
• CPC Class Codes: B29C 66/8414 of different diameter
• CPC Class Codes: B29C 66/847 Drilling standard machine type
• CPC Class Codes: B29C 66/9513 characterised by specific vibration frequency values or ranges
• CPC Class Codes: B29L 2031/565 for containers
• CPC Class Codes: B65B 51/225 by ultrasonic welding

Abstract

A method for sealing the neck of a thermoplastic container to a thermoplastic cap superposed upon the neck and the cap having a lateral edge extending beyond the periphery of the neck using an ultrasonic welding apparatus includes an ultrasonic resonator having a domical internal cavity in its output end for reshaping the lateral edge of the cap in order to form a peripheral bead along the interface between the cap and the neck of the container.

Claims

1. A method for ultrasonically welding the neck of a thermoplastic container to a thermoplastic cap, the latter having a flange superposed upon said neck and said flange having a lateral edge extending beyond the periphery of said neck, comprising the steps of:

providing an elongated ultrasonic resonator, dimensioned to be resonant as a half wavelength resonator when energized with ultrasonic energy of predetermined frequency at an input end and adapted to provide ultrasonic vibrations at an opposite output end, said resonator having a domical internal cavity with tapered wall extending from said output end of said resonator axially toward said input end, the maximum opening of said cavity being at least equal to the periphery of said neck;

causing said output end of said resonator while rendered resonant to be in forced engagement with said cap and container for effecting, responsive to the vibrations and the engagement force exerted by said resonator, thermoplastic material from the edge of said flange to be softened and displaced from said flange and to be trapped as a peripheral bead along the wall of said cavity, and

ceasing ultrasonic vibrations when said trapped softened material is disposed as a peripheral bead around the interface between said flange and said neck of the container to permit said bead to solidify and to thereby form a seal between said cap and said neck.

2. A method for ultrasonically welding the neck of a thermoplastic container to a thermoplastic cap superposed upon said neck and said cap having a lateral edge extending beyond the periphery of said neck, comprising the steps of:

providing an elongated ultrasonic resonator, dimensioned to be resonant as a half wavelength resonator when energized with ultrasonic energy of predetermined frequency at an input end and adapted to provide ultrasonic vibrations at an opposite output end, said resonator having a domical internal cavity with tapered wall extending from said output end of said resonator axially toward said input end, the maximum opening of said cavity being at least equal to the periphery of said neck;

causing said output end of said resonator while rendered resonant to be in forced engagement with said cap and container for effecting, responsive to the vibrations and the engagement force exerted by said resonator, thermoplastic material from the edge of said cap to be softened and displaced from said cap and to be trapped as a peripheral bead along the wall of said cavity, and

ceasing ultrasonic vibrations when said trapped softened material is disposed as a peripheral bead around the interface between said cap and said neck of the container to permit said bead to solidify and to thereby form a seal between said cap and said neck.