US 5,893,959 AGranted

Workpiece of plastic and production process for such a workpiece

AssigneeMarquardt GmbH

InventorVitus Muellich

Life of this patent

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Abstract

The invention relates to a workpiece, in particular a housing (6) for an electrical switch, and to a process for its production. The workpiece is composed of at least two workpiece parts (7, 8) of plastic, preferably a thermo-plastic, welded together by laser beams (11) along a joining zone (10), the two workpiece parts (7, 8) having a transmission coefficient and an absorption coefficient for the spectrum of the laser beams (11) which are different from one another, at least in subregions. The one, first workpiece part (8) is made to be at least partially transmitting for the laser beams (11) in the region from a first coupling-in zone (12), in which the laser beams (11) impinge on the first workpiece part (8), up to the joining zone (10), whereby part of the laser beams (11) can penetrate through the first workpiece part (8) and can penetrate into the second workpiece part (7) at a second coupling-in zone (13). The second workpiece part (7) is made to be at least partially absorbent for the laser beams (11) in the region of the joining zone (10) at the second coupling-in zone (13).

Claims36

Dependent claims

In an article of manufacture, including

first and second plastic parts being in a face-to-face relationship and being welded together by a laser beam along a joining zone;
said first and second plastic parts having, for a laser beam spectrum, transmission coefficients different from one another and absorption coefficients different from one another;
said first plastic part having a first coupling-in zone designed as a location of impingement of the laser beam;
said first plastic part being transparent for the laser beam from said first coupling-in zone to said joining zone, whereby at least one part of the laser beam can pass through said first plastic part and can penetrate into said second plastic part at a second coupling-in zone thereof;
said second plastic part being absorbent for the laser beam in a region of said joining zone at said second coupling-in zone;
the improvement wherein said transmission coefficient of said first plastic part and said absorption coefficient of said second plastic part are set by additives to the plastic material of said first and second plastic parts such that said first plastic part is at least partially transparent for the spectrum of the laser beam in a region from said first coupling-in zone to said joining zone and said second plastic part is at least partially absorbent for the spectrum of the laser beam in a region of said second coupling-in zone;
and further wherein a reflectivity of said first and second plastic parts is substantially identical for visible light rays throughout the first and second plastic parts, and said first and second plastic parts are substantially opaque to visible light.

4 more elements

A process for welding together a first and a second plastic part by a laser beam to form an article of manufacture, wherein at least a portion of said first plastic part is transparent to the laser beam and at least a portion of said second plastic part absorbs the laser beam;

said process comprising the following steps:
(a) including an additive, affecting a transparency to the laser beam, in the material of said first plastic part in a first proportion such that a region of said first plastic part is at least partially transparent to the laser beam;
(b) including an additive, affecting a transparency to the laser beam, in the material of said second plastic part in a second proportion such that a region of said second plastic part is at least partially absorbent to the laser beam;
said first proportion being different from said second proportion;
(c) setting reflectivities for said first and second plastic parts such that said reflectivities are substantially identical to visible light rays throughout the first and second plastic parts, and said first and second plastic parts are substantially opaque to visible light;
(d) positioning said first and said second plastic parts in a path of a laser beam such that a surface portion of said first plastic part faces a surface portion of said second plastic part to form a joining zone and that said first plastic part is upstream of said second plastic part as viewed in a direction of propagation of the laser beam;
(e) directing the laser beam to impinge on a first coupling-in zone of said first plastic part, to pass through said region of said first plastic part from said first coupling-in zone to said joining zone, to impinge on a second coupling-in zone of said second plastic part at said joining zone and to pass into said region of said second plastic part from said second coupling-in zone, whereby said second plastic part is heated at said second coupling-in zone, causing said first and said second plastic parts to assume a molten state in said joining zone;
and
(f) cooling said joining zone to effect a solidifying thereof.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/702,434Filed 24 Sep 1996
Priority: DE 44 11 25131 Mar 1994
Granted: 13 Apr 1999
Term ends: Not estimatedThe source records don’t support an estimate.

Classification52 codes

B29C 66/81267
Optical properties, e.g. transparency, reflectivity: transparent to electromagnetic radiation, e.g. to visible light
B29C 65/1635
Characterised by the way of heating the interface: at least passing through one of the parts to be joined, i.e. laser transmission welding
B29C 65/1654
Characterised by the way of heating the interface: scanning at least one of the parts to be joined
B29C 65/1677
Laser beams: making use of an absorber or impact modifier