# US 9,873,225 B2 · Energy director joint design for ultrasonic welding of thermoplastics > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,873,225 B2 - Document ID: US9873225B2 - Status: Granted - Kind: B2 - Application number: 14/500,416 - Filed: 2014-09-29 - Published: 2015-05-14 - Granted: 2018-01-23 - Earliest claimed: 2013-11-12 - Assignees: Dukane IAS, LLC - Applicants: Dukane Corporation - Inventors: Leo Klinstein; Paul Golko; Miranda Bair Marcus - Web page: https://patentgrep.com/patent/US9873225B2 ## CPC - B29C 65/08: using ultrasonic vibrations {(non-plastics element to plastics elements B29C65/645)} - B29C 66/112: {Single lapped joints} - B29C 66/114: {Single butt joints} - B29C 66/30223: {said melt initiators being rib-like} - B29C 66/542: {joining hollow covers or hollow bottoms to open ends of container bodies} - B29C 66/73921: {characterised by the materials of both parts being thermoplastics} - B29C 66/8322: {Joining or pressing tools reciprocating along one axis} - B29C 66/92615: {the gap being non-constant over time} - B29C 66/92921: {in specific relation to time, e.g. pressure-time diagrams} - B29C 66/951: {by measuring or controlling the vibration frequency and/or the vibration amplitude of vibrating joining tools, e.g. of ultrasonic welding tools} - B29C 66/1222: {comprising at least a lapped joint-segment} - B29C 66/1224: {comprising at least a butt joint-segment} - B29C 66/24221: {being circular (B29C66/51 takes precedence)} - B29C 66/24244: {forming a rectangle} - B29C 66/71: {characterised by the composition of the plastics material of the parts to be joined (welding bar compositions B29C65/125)} - B29C 66/8246: {Servomechanisms, e.g. servomotors} - B29K 2101/12: Thermoplastic materials - B29K 2105/253: {Preform} - B29K 2105/256: {Sheets, plates, blanks or films} - B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00) - B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS ## Abstract An ultrasonic welding system and method for joining first and second thermoplastic parts includes least one energy director formed on at least one surface of the first thermoplastic part, with the energy director projecting from the surface of the first thermoplastic part toward an opposed surface of the second thermoplastic part. The distal end portion of the energy director has a curved or flat surface that initially engages the opposed surface of the second thermoplastic part when the first and second parts are brought into engagement with each other. The first and second thermoplastic parts are ultrasonically welded by pressing the parts together while vibrating at least the first part in a direction parallel to the direction of projection of the energy director. The energy director may include a pair of substantially flat side walls joined to opposite ends of the curved or flat end surface. ## Claims ### Claim 1 An ultrasonic welding method for joining first and second thermoplastic parts, said method comprising forming at least one energy director as an integral part of at least one surface of said first thermoplastic part, said energy director projecting from said surface of said first thermoplastic part toward an opposed surface of said second thermoplastic part, the end portion of said energy director having a convex curved surface so that the central portion of said convex curved surface initially engages said opposed surface when said first and second thermoplastic parts are brought into engagement with each other, and ultrasonically welding said first and second thermoplastic parts by pressing said first and second thermoplastic parts together using a servo-driven ultrasonic press while vibrating at least said first part in a direction parallel to the direction of projection of said energy director to melt said energy director and the adjacent surface of said first thermoplastic part on which said energy director is formed, wherein a longitudinal section taken through said energy director, in a direction normal to the surface to be engaged by said director, has a curved profile at the distal end of said director, said curved profile having a radius of curvature of at least 0.20 mm at the distal end of said energy director, and advancing said parts toward each other after an initial programmed delay interval following the start of said vibrating using the servo-driven ultrasonic press to change forces or speed rapidly during the ultrasonically welding after the programmed delay interval to promote initial melting of the energy director and thereafter a uniform and consistent welt joint with an optimum weld strength. ### Claim 2 (depends on 1) The ultrasonic welding method of claim 1 in which a longitudinal section taken through said energy director, in a direction normal to the surface to be engaged by said director, has a curved profile at the distal end of said director. ### Claim 3 (depends on 2) The ultrasonic welding method of claim 2 in which said curved profile is a section of a circle. ### Claim 4 (depends on 3) The ultrasonic welding method of claim 3 in which the center of said circle is substantially coincident with the surface of said first thermoplastic part from which said energy director protrudes. ### Claim 5 (depends on 3) The ultrasonic welding method of claim 3 in which the center of said circle is spaced away from the surface of said first thermoplastic part from which said energy director protrudes, in a direction opposite the direction of projection of said energy director. ### Claim 6 (depends on 3) The ultrasonic welding method of claim 3 in which the center of said circle is spaced away from the surface of said first thermoplastic part from which said energy director protrudes, in the same direction as the direction of projection of said energy director, and which includes a pair of substantially flat side walls joined to opposite ends of said curved profile, said substantially flat side walls diverging from each other as they extend away from said curved profile toward the surface of said first thermoplastic part to be joined to said second thermoplastic part. ### Claim 7 (depends on 2) The ultrasonic welding method of claim 2 in which the maximum width of said curved profile is at least half of the maximum width of said longitudinal section taken through said energy director. ### Claim 8 (depends on 2) The ultrasonic welding method of claim 2 in which said curved profile has the radius of curvature of at least 0.20 mm at the distal end of said energy director. ### Claim 9 (depends on 1) The ultrasonic welding method of claim 1 in which said energy director is formed in a mold in which the cavity that forms said energy director is formed by ball end milling. ### Claim 10 An ultrasonic welding method for joining a film or fabric to a rigid thermoplastic part, said method comprising forming at least one energy director as an integral part of at least one surface of said rigid thermoplastic part, said energy director projecting from said surface of said rigid thermoplastic part toward an opposed surface of said film or fabric, the end portion of said energy director having a convex curved surface so that the central portion of said convex curved surface initially engages said film or fabric when said film or fabric is brought into engagement with said rigid thermoplastic part, wherein a longitudinal section taken through said energy director, in a direction normal to the surface to be engaged by said director, has a curved profile at the distal end of said director, said curved profile having a radius of curvature of at least 0.20 mm at the distal end of said energy director, and ultrasonically welding said film or fabric to said rigid thermoplastic part by pressing said film or fabric and said rigid thermoplastic part together using a servo-driven ultrasonic press while vibrating at least said rigid thermoplastic part or said film or fabric in a direction parallel to the direction of projection of said energy director to melt said energy director and the adjacent surface of said rigid thermoplastic part on which said energy director is formed, and advancing said parts toward each other after an initial programmed delay interval following the start of said vibrating using the servo-driven ultrasonic press to change forces or speed rapidly during the ultrasonically welding after the programmed delay interval to promote initial melting of said energy director and thereafter a uniform and consistent welt joint with an optimum weld strength. ### Claim 11 (depends on 10) The method of claim 10 in which said film or fabric is supported on a rigid surface made of a material that will not adhere to said rigid thermoplastic part. ### Claim 12 An ultrasonic welding method for joining first and second thermoplastic parts, said method comprising forming at least one energy director as an integral part of at least one surface of said first thermoplastic part, said energy director projecting from said surface of said first thermoplastic part toward an opposed surface of said second thermoplastic part, the end portion of said energy director having a trapezoidal surface so that the central portion of said trapezoidal surface initially engages said opposed surface when said first and second thermoplastic parts are brought into engagement with each other, and ultrasonically welding said first and second thermoplastic parts by pressing said first and second thermoplastic parts together using a servo-driven ultrasonic press while vibrating at least said first part in a direction parallel to the direction of projection of said energy director to melt said energy director and the adjacent surface of said first thermoplastic part on which said energy director is formed, wherein said energy director has a non-pointed profile at a distal end of said energy director, and advancing said parts toward each other after an initial programmed delay interval following the start of said vibrating using the servo-driven ultrasonic press to change forces or speed rapidly during the ultrasonically welding after the programmed delay interval to promote initial melting of the energy director and thereafter a uniform and consistent welt joint with an optimum weld strength. ### Claim 13 (depends on 1) The ultrasonic welding method of claim 1 in which said trapezoidal energy director has truncated corners separated by a flat central end surface on said energy director.