Ultrasonic welding of dissimilar sheet materials

Patent metadata

Field	Value
Publication number	US-2018272618-A1
Application number	US-201815991367-A
Country	US
Kind code	A1
Filing date	May 29, 2018
Priority date	Jun 16, 2016
Publication date	Sep 27, 2018
Grant date	—

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 thermoplastic piece atop a higher melting temperate (HMT) piece, wherein the HMT piece comprises at least one hole, to cover the hole in the HMT piece; and applying ultrasonic energy to the thermoplastic piece above the hole of the HMT piece using an ultrasonic horn to melt material of the thermoplastic piece so that material melted fills the hole of the HMT piece to create a weld point joining the thermoplastic piece and the HMT piece to form the welded component.

2 . The method of claim 1 , wherein the at least one hole has at least one undercut feature and some of the material melted 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:
said hole is one of a plurality of holes of the HMT piece; and the placing and the applying are performed to fill each hole with the material of the thermoplastic piece melted.

5 . The method of claim 1 , further comprising, prior to applying ultrasonic energy, placing the HMT piece on an anvil having a generally flat top surface, wherein a bottom of the weld point being formed is kept flat by the generally flat top surface of the anvil as the melted thermoplastic material fills the hole.

6 . The method of claim 1 , further comprising:
placing the HMT piece on an anvil prior to applying ultrasonic energy; wherein:
the anvil has a top surface and a concavity in the top surface;
the concavity is wider than the hole of the HMT piece, forming an under-piece feature when the HMT piece is placed on the anvil; and
when the material of the thermoplastic piece is melted by the ultrasonic energy, the melted material fills the hole and the concavity of the anvil, including beneath the under-piece feature, forming a convex bottom portion of the weld point overlapping a bottom surface of the HMT piece.

7 . The method of claim 1 , wherein:
the thermoplastic piece is a first thermoplastic piece; the at least one hole of the HMT piece is a first set of holes, each having an opening at a top surface of the HMT piece; the first thermoplastic piece is placed adjacent the top surface of the HMT piece; the HMT piece further comprises a second set of holes, each having an opening at a bottom surface of the HMT piece; and the method further comprises:
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; and
applying ultrasonic energy to the second thermoplastic piece above 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.

8 . The method of claim 1 , wherein the method is performed to form a double lap joint to join the thermoplastic and HMT pieces 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.

9 . The method of claim 1 , wherein:
the HMT piece is a first HMT piece; the at least one hole of the first HMT piece is a first set of holes; and the method further comprising butting the first HMT piece with a second HMT piece having a second set of holes before placing the thermoplastic piece on top of the holes of the first and second HMT pieces and applying the ultrasonic energy to fill all of the holes of the first and second sets with the material from the thermoplastic piece to form the butt joint joining the first and second HMT pieces to the thermoplastic piece.

10 . The method of claim 1 , wherein:
the HMT piece is a first HMT piece; and the at least one hole of the first HMT piece is the first set of holes and the method further comprises 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 before applying ultrasonic energy to the thermoplastic piece above the 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.

11 . The method of claim 1 , wherein the at least one hole is a through hole and the melted material of the thermoplastic piece fills the through hole of the HMT piece to create the weld point joining the thermoplastic piece and the HMT piece to form the welded component.

12 . The method of claim 1 , wherein the at least one hole is a blind hole and the melted material of the thermoplastic piece fills 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.

13 . The method of claim 12 , 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.

14 . 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 arrangement, thereby filling the hole and the void formed.

15 . The method of claim 14 , wherein:
the anvil-cutter arrangement 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

• B29K2705/00

  Use of metals, their alloys or their compounds, for preformed parts, e.g. for inserts · CPC title

• B29C66/949

  characterised by specific time values or ranges · CPC title

• B29C66/929

  characterized by specific pressure, force, mechanical power or displacement values or ranges · CPC title

• B29C66/43

  Joining a relatively small portion of the surface of said articles (B29C66/45 takes precedence) · CPC title

• B29C65/607

  the integral rivets being hollow · CPC title