Ultrasonic welding and welding horn having indenter

Patent metadata

Field	Value
Publication number	US-11141925-B2
Application number	US-201916669802-A
Country	US
Kind code	B2
Filing date	Oct 31, 2019
Priority date	Oct 31, 2019
Publication date	Oct 12, 2021
Grant date	Oct 12, 2021

Abstract

A method of joining includes disposing a second workpiece adjacent to a first workpiece. The method further includes identifying a determined hardness parameter of at least one of the first and second workpieces at a welding position. The determined hardness parameter is determined by at least one of estimation, calculation, and measurement. The method includes selecting a weld schedule based on the determined hardness parameter and welding the first and second workpieces together using the selected weld schedule. A welding horn includes a shank and a tip having an end face, the tip being disposed at an end of the shank and configured to contact a workpiece and to transmit energy to the workpiece. Knurls are disposed on the end face, each knurl having a distal end. A curved indenter extends from the end face beyond the distal ends of the knurls.

First claim

What is claimed is:

1. A method of joining, the method comprising:
providing a first workpiece;
providing a welding horn comprising:
a shank defining an end shank radius at an end of the shank;
a tip having an end face, the tip being disposed at an end of the shank and configured to contact the first workpiece and to transmit energy to the first workpiece, the end face being curved and defining a tip radius of curvature;
a plurality of knurls disposed on the end face, each knurl having a distal end; and
a curved indenter extending from the end face beyond the distal ends of the knurls, the curved indenter defining an indenter radius of curvature, the tip radius of curvature being greater than the indenter radius of curvature and the tip radius of curvature being at least four times the end shank radius

disposing a second workpiece adjacent to the first workpiece;
identifying a determined hardness parameter of at least one of the first and second workpieces at a welding position, the determined hardness parameter being determined by at least one of estimation, calculation, and measurement;
selecting a weld schedule based on the determined hardness parameter; and
ultrasonically welding, using the welding horn, the first and second workpieces together using the selected weld schedule.

2. The method of claim 1 , wherein the first and second workpieces are each formed of a polymeric composite material.

3. The method of claim 2 , wherein the polymeric composite material comprises a thermoplastic polymer matrix and a plurality of reinforcing chopped fibers disposed within the thermoplastic polymer matrix.

4. The method of claim 3 , wherein the polymeric composite material is a carbon-reinforced nylon having a plurality of chopped carbon fibers disposed within the nylon, the plurality of chopped carbon fibers having an average fiber length no greater than 50 millimeters and an average diameter no greater than one micrometer.

5. The method of claim 1 , wherein the step of identifying the determined hardness parameter includes pressing the curved indenter into a surface of the first workpiece with a predetermined force and determining a depth of a displacement of the curved indenter after pressing the curved indenter into the surface of the first workpiece.

6. The method of claim 5 , wherein the selected weld schedule includes a predetermined horn amplitude.

7. The method of claim 6 , the selected weld schedule further including at least one of the following: a predetermined total welding time, an initial horn trigger force, a total distance of displacement of the welding horn into the first workpiece, a total amount of energy applied to the first workpiece through the welding horn, a velocity of moving the welding horn into the first workpiece, a maximum amount of force applied to the first workpiece by the welding horn, and an amount of melted material of the first workpiece after an initial application of energy from the welding horn prior to moving the welding horn into the first workpiece.

8. The method of claim 2 , wherein the step of identifying the determined hardness parameter includes pressing a tool into a surface of one of the first and second workpieces with a predetermined force and a predetermined amplitude and determining a power applied through the tool upon pressing the tool into the surface with the predetermined force and the predetermined amplitude.

9. The method of claim 1 , the welding position being a first welding position, the determined hardness parameter being a first determined hardness parameter, and the selected weld schedule being a first selected weld schedule, the method further comprising identifying a plurality of additional determined hardness parameters of at least one of the first and second workpieces at a plurality of additional welding positions, selecting a weld schedule for each of the plurality of additional welding positions based on the plurality of additional determined hardness parameters to identify a plurality of additional selected weld schedules, each additional selected weld schedule correlating with an additional welding position of the plurality of additional welding positions, and welding the first and second workpieces together at each of the additional welding positions using the plurality of additional selected weld schedules.

10. A welding horn for ultrasonic welding a plurality of workpieces together, the welding horn comprising:
a shank defining an end shank radius at an end of the shank;
a tip having an end face, the tip being disposed at an end of the shank and configured to contact a first workpiece of the plurality of workpieces and to transmit energy to the first workpiece, the end face being curved and defining a tip radius of curvature;
a plurality of knurls disposed on the end face, each knurl having a distal end; and
a curved indenter extending from the end face beyond the distal ends of the knurls, the curved indenter defining an indenter radius of curvature, the tip radius of curvature being greater than the indenter radius of curvature and the tip radius of curvature being at least four times the end shank radius.

11. The welding horn of claim 10 , the shank defining an end shank diameter at the end of the shank, the indenter radius of curvature being less than the end shank diameter.

12. A welding horn for ultrasonic welding a plurality of workpieces together, the welding horn comprising:
a shank defining an end shank radius at an end of the shank and an end shank diameter at the end of the shank;
a tip having an end face, the tip being disposed at the end of the shank and configured to contact a first workpiece of the plurality of workpieces and to transmit energy to the first workpiece, the end face being curved and defining a tip radius of curvature;
a plurality of knurls disposed on the end face, each knurl having a distal end; and
a curved indenter extending from the end face beyond the distal ends of the knurls, the curved indenter defining an indenter radius of curvature, the tip radius of curvature being greater than the indenter radius of curvature and the tip radius of curvature being at least four times the end shank radius, the indenter radius of curvature being less than the end shank diameter, the end shank diameter being no greater than four times the indenter radius of curvature, and the indenter extending no more than 2.0 mm beyond the distal ends of the knurls.

13. The welding horn of claim 12 , the plurality of knurls defining a knurl pitch between each adjacent knurl that is not interrupted by the indenter, each knurl being defined by a knurl angle extending from a knurl base to an outwardly extending knurl edge, the knurl angle being in range of 40 to 60 degrees, and a ratio of the knurl pitch to the end shank diameter being at least 0.045 and no greater than 0.065.

Assignees

• Gm Global Tech Operations Llc

Inventors

• Wang Pei-Chung
• Blaski Bradley J
• Nagesh Athreya

Classifications

• B29C66/7212

  characterised by the composition of the fibres · CPC title

• B29C66/45

  Joining of substantially the whole surface of the articles (methods or apparatus for laminating B32B37/00) · CPC title

• B29C66/73921

  characterised by the materials of both parts being thermoplastics · CPC title

• B29C65/08 Primary

  using ultrasonic vibrations {(non-plastics element to plastics elements B29C65/645)} · CPC title

• B29C66/721

  Fibre-reinforced materials (B29C66/729 takes precedence) · CPC title