Ultrasonic welding of dissimilar sheet materials

Patent metadata

Field	Value
Publication number	US-11027498-B2
Application number	US-201815991367-A
Country	US
Kind code	B2
Filing date	May 29, 2018
Priority date	Jun 16, 2016
Publication date	Jun 8, 2021
Grant date	Jun 8, 2021

Abstract

A ultrasonic welding method of joining dissimilar-material workpieces, such as sheet materials, and the joined components formed thereby. The method includes applying ultrasonic energy to a thermoplastic piece to fill a hole of a dissimilar piece to form a weld point that is made up with polymer from the thermoplastic piece. In general, the geometry of the thermoplastic piece is not altered during the process. The dissimilar piece generally has a higher melting temperate and can be metal, thermoset polymers, or other thermoplastic material. The welded pieces can be arranged in a lap, laminate, or double lap configuration. In some embodiments, the hole of the dissimilar sheet material includes undercut features that improve the mechanical interlock between the dissimilar pieces. In some embodiments, the weld point has a mushroom cap to improve mechanical interlock.

First claim

We claim:

1. A method, of forming a welded component of dissimilar-material pieces by ultrasonic welding, comprising,
placing a first thermoplastic piece atop a top surface of a higher melting temperate (HMT) piece, wherein the top surface of the HMT piece comprises a first set of holes each having an opening in the top surface, to cover the first set of holes in the HMT piece, and wherein the HMT piece further comprises a second set of holes, each having an opening at a bottom surface of the HMT piece;
placing a second thermoplastic piece adjacent the bottom surface of the HMT piece, covering the second set of holes in the HMT piece, sandwiching the HMT piece with the first thermoplastic piece;
applying ultrasonic energy to the thermoplastic piece above the first set of holes of the HMT piece using an ultrasonic horn to melt material of the first thermoplastic piece so that material melted fills the first set of holes of the HMT piece to create a weld point joining the first thermoplastic piece and the HMT piece to form the welded component; and
applying ultrasonic energy to the second thermoplastic piece below the second set of holes of the HMT piece, so that material of the second thermoplastic piece melts and flows into the second set of holes.

2. The method of claim 1 , wherein the first set of holes and the second set of holes has at least one undercut feature and some of the material melted from the first and second thermoplastic pieces fills the undercut feature.

3. The method of claim 2 , wherein the at least one undercut feature comprises a step, internal threads, or a combination thereof.

4. The method of claim 1 , wherein the method is performed to form a double lap joint to join the first and second thermoplastic pieces and HMT piece of the welded component, wherein:
the ultrasonic horn is a first ultrasonic horn; and
applying the ultrasonic energy to the second thermoplastic piece is performed using a second ultrasonic horn having a larger diameter than the first ultrasonic horn.

5. A method, of forming a welded component of dissimilar-material pieces by ultrasonic welding, comprising,
placing a thermoplastic piece atop a first higher melting temperate (HMT) piece, wherein the HMT piece comprises a first set of holes, to cover the first set of holes in the first HMT piece;
stacking a second HMT piece comprising a second set of holes with the first HMT piece and aligning the first set of holes with the second set of holes; and
applying ultrasonic energy to the thermoplastic piece above the first and second set of holes of the first and second HMT pieces to fill all of the holes with material melted from the thermoplastic piece to join the first and second HMT pieces to the thermoplastic piece to create a weld point joining the thermoplastic piece and the first and second HMT pieces to form the welded component.

6. The method of claim 1 , wherein the second set of holes are through holes and the melted material of the first thermoplastic piece fills the through holes of the HMT piece to create the weld point joining the first thermoplastic piece and the HMT piece to form the welded component.

7. The method of claim 1 , wherein the second set of holes are blind holes and the melted material of the first thermoplastic piece fills the blind holes of the HMT piece to create the weld point joining the first thermoplastic piece and the HMT piece to form the welded component.

8. The method of claim 7 , wherein the blind hole comprises at least one undercut feature includes a step, an internal thread, or a combination thereof and the melted material of the thermoplastic piece fills the undercut feature(s) of the blind hole of the HMT piece to create the weld point joining the thermoplastic piece and the HMT piece to form the welded component.

9. A method, for joining dissimilar-material workpieces, comprising:
positioning a higher melting temperature (HMT) piece adjacent an anvil-cutting apparatus;
moving a cutter of the apparatus into a hole of the HMT piece;
extending a cutting insert of the cutter and rotating the cutting insert to form a void in a side wall of the hole;
retracting the cutting insert;
retracting the cutter from the hole;
positioning a thermoplastic piece atop the HMT piece; and
applying ultrasonic energy to the thermoplastic piece causing material of the thermoplastic piece to melt and move into the hole until the material melted contacts a top of the cutter of the anvil-cutter apparatus, thereby filling the hole and the void formed.

10. The method of claim 9 , wherein:
the anvil-cutter apparatus has a slot in which the cutter is slidably positioned;
the slot is wider than the hole of the HMT piece;
retracting the cutter includes retracting the cutter into a body of the cutter-anvil arrangement so that a top surface of the cutter is lower than an adjacent top surface of the body, so that a lower surface of the HMT piece exposed can act as an under-piece feature for receiving material melted from the thermoplastic piece; and
applying ultrasonic energy to melt the thermoplastic piece to fill a space between sides of the slot, atop the top surface of the cutter, and beneath the under-piece feature formed by the exposed surface of the HMT piece.

Assignees

• Gm Global Tech Operations Llc

Inventors

• Li Yongqiang
• Hu Shixin
• Shriver Daniel
• Wang Kaifeng
• Banu Mihaela
• Arinez Jorge F

Classifications

• B29C65/4895

  Solvent bonding, i.e. the surfaces of the parts to be joined being treated with solvents, swelling or softening agents, without adhesives · CPC title

• B29C65/562

  using extra joining elements, i.e. which are not integral with the parts to be joined (using plastic snap elements B29C65/58; using plastic rivets B29C65/601) · CPC title

• B23K20/22

  taking account of the properties of the materials to be welded · CPC title

• B29C66/939

  characterised by specific speed values or ranges · CPC title

• B29C65/02

  by heating, with or without pressure · CPC title