Frictionally welded thermoplastic articles having improved strength
AssigneeHoneywell International Inc.
InventorsVal A. Kagan, Chul S. Lee
Life of this patent
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Abstract
A frictionally welded, filled thermoplastic article is strengthened by restricting lateral flow of molten material out of the gap between the workpieces, so that a molten pool of substantial depth is maintained from the beginning of melting to the onset of solidification. The restriction to lateral flow of material is provided by dams (projections) of essentially rectangular cross-section at each lateral edge of one of the workpieces, while the other workpiece has a substantially flat mating surface.
Claims20
A frictionally welded thermoplastic article, comprising:
- a. a first thermoplastic workpiece and a second thermoplastic workpiece, each of said first and second thermoplastic workpieces having a mating surface;
- b. said mating surface of said first thermoplastic workpiece and said mating surface of said second thermoplastic workpiece being joined in a melt down region;
- and
- said mating surface of said first workpiece having been comprised, prior to welding, of a restriction to lateral flow of the melt from between the workpieces, and said mating surface of said second workpiece being substantially flat.
A vibration welded thermoplastic article, comprising:
- a. a first thermoplastic workpiece and a second thermoplastic workpiece, each of said first and thermoplastic workpieces having a mating surface;
- b. said mating surface of said first thermoplastic workpiece and said mating surface of said second thermoplastic workpiece being joined in a melt down region;
- c. said mating surface of said first workpiece having been comprised, prior to welding, of a restriction to lateral flow of the melt from between the workpieces, and said mating surface of said second workpiece being substantially flat;
- d. wherein the restriction to lateral flow of the melt from between the workpieces is a substantially rectangular projection along each lateral edge of the first workpiece;
- e. wherein the thickness of each of said projections is between about 5% and about 35% of the thickness of the first workpiece;
- and
- f. the height of each of said projections, relative to the lowest point on the initial mating surface is at least about 25% of the dimension of the melt down region.
A vibration welded thermoplastic article, comprising:
- a. a first thermoplastic workpiece and a second thermoplastic workpiece, each of said first and thermoplastic workpieces having a mating surface;
- b. said mating surface of said first thermoplastic workpiece and said mating surface of said second thermoplastic workpiece being joined in a melt down region;
- c. said mating surface of said first workpiece having been comprised, prior to welding, of a restriction to lateral flow of the melt from between the workpieces, and said mating surface of said second workpiece being substantially flat;
- d. wherein the restriction to lateral flow of the melt from between the workpieces is a substantially rectangular projection along each lateral edge of the first workpiece;
- e. wherein the thickness of each of said projections is between about 5% and about 35% of the thickness of the first workpiece;
- and
- f. prior to welding, the cross-sectional area of the space defined by a line between the upper edges of the rectangular projections and the material surfaces between them is at least about 15% of the product of the thickness of the first workpiece and the dimension of the melt down region.
A method of frictional welding a first thermoplastic workpiece to a second thermoplastic workpiece, comprising the steps of:
- a. pressing the first and second workpieces together under a compressive clamping pressure;
- b. moving the first workpiece relative to the second workpiece in a plane parallel to their interface sufficient to frictionally heat the interface;
- c. melting the interfacial surfaces of the first and second workpieces creating a melt down region;
- d. providing a means to restricting the lateral flow of molten material out of the gap between said interfacial surfaces;
- and
- e. retaining a molten pool of substantial depth between the workpieces from the beginning of melting to the onset of solidification.
Dependencies are inferred from the claim text.