Method and apparatus for heating plastics by means of laser beams

• US 20050098260A1
• Filed: 10/06/2004
• Published: 05/12/2005
• Est. Priority Date: 10/21/2003
• Status: Active Grant

• Current Assignee: Leister Technologies AG
• Original Assignee: Leister Process Technologies
• Inventors: Chen, Jie Wei
• Granted Patent: US 7,223,315 B2
• Time in Patent Office: Days
• US Class Current: 156/272.8
• CPC Class Codes: B23K 26/0604 by a combination of beams
• CPC Class Codes: B23K 26/0608 in the same heat affected zone [HAZ] B23K26/0613, B23K26/0619 take precedence
• CPC Class Codes: B23K 26/067 Dividing the beam into multiple beams, e.g. multifocusing
• CPC Class Codes: B23K 26/244 Overlap seam welding
• CPC Class Codes: B29C 65/00 Joining or sealing of preformed parts , e.g. welding of plastics materials; Apparatus therefor general aspects of processes or apparatus for joining preformed parts B29C66/00; using porous material formed by internal pressure generated therein for joining preformed parts B29C44/1228, B29C44/326
• CPC Class Codes: B29C 65/1635 at least passing through one of the parts to be joined, i.e. laser transmission welding
• CPC Class Codes: B29C 65/1638 focusing the laser beam on the interface
• CPC Class Codes: B29C 65/1654 scanning at least one of the parts to be joined
• CPC Class Codes: B29C 65/1658 scanning once, e.g. contour laser welding
• CPC Class Codes: B29C 65/1664 making use of several radiators
• CPC Class Codes: B29C 65/1687 making use of light guides
• CPC Class Codes: B29C 66/0242 Heating, or preheating, e.g. drying B29C66/3464 takes precedence
• CPC Class Codes: B29C 66/1122 Single lap to lap joints, i.e. overlap joints B29C66/45, B29C66/472, B29C66/52272 take precedence
• CPC Class Codes: B29C 66/21 said joint lines being formed by a single dot or dash or by several dots or dashes, i.e. spot joining or spot welding
• CPC Class Codes: B29C 66/221 being in the form of a sinusoidal wave B29C66/2272 takes precedence
• CPC Class Codes: B29C 66/223 being in the form of a triangle wave or of a sawtooth wave, e.g. zigzagged
• CPC Class Codes: B29C 66/232 said joint lines being multiple and parallel, i.e. the joint being formed by several parallel joint lines
• CPC Class Codes: B29C 66/43 Joining a relatively small portion of the surface of said articles B29C66/45 takes precedence
• CPC Class Codes: B29C 66/80 General aspects of machine operations or constructions and parts thereof
• CPC Class Codes: B29C 66/8122 characterised by the composition of the material constituting the pressing elements, e.g. constituting the welding jaws or clamps
• CPC Class Codes: B29C 66/81267 : Transparent to electromagnetic radiation, e.g. to visible light
• CPC Class Codes: B29C 66/83441 : Ball types
• CPC Class Codes: B29C 66/836 : Moving relative to and tangentially to the parts to be joined, e.g. transversely to the displacement of the parts to be joined, e.g. using a X-Y table B29C66/65 takes precedence
• CPC Class Codes: B29C 66/8362 : Rollers, cylinders or drums moving relative to and tangentially to the parts to be joined
• CPC Class Codes: B29C 66/91411 : of the parts to be joined, e.g. the joining process taking the temperature of the parts to be joined into account
• CPC Class Codes: B29C 66/9161 : by controlling or regulating the heat or the thermal flux, i.e. the heat flux
• CPC Class Codes: B29C 66/9192 : in explicit relation to another variable, e.g. temperature diagrams
• CPC Class Codes: B29K 2313/00 : Use of textile products or fabrics as reinforcement B29K2105/06 takes precedence
• CPC Class Codes: B29K 2909/08 : Glass
• CPC Class Codes: B29K 2995/0027 : for light outside the visible spectrum

Abstract

Method and apparatus for heating plastic by laser beams with the aid of a number of laser points on the focal plane, the laser points being produced by an optical arrangement with the aid of a multiple wedge plate. The arrangement can be integrated in a processing head.

Claims

1. A method for welding plastic comprising the steps of:

providing a laser beam source for producing a laser beam;

locating a lens downstream of the last beam source for collimating the laser beam;

splitting the collimated laser beam into a plurality of beams by means of a multiple wedged plate comprising a plurality of wedges which correspond to a desired number of laser points to be produced, wherein the wedges are offset from horizontal at a desired angle; and

locating a converging lens downstream of the multiple wedged plate, wherein the plurality of beams are fed through the converging lens and continue to be collimated thereby to produce a plurality of laser points on a focal plane of plastic to be welded.

2. The method according to claim 1, further comprising providing a movable transparent ball downstream of the converging lens wherein the plurality of laser beams are coupled and guided over the focal plane during movement of the ball.

3. The method according to claim 1, including controlling laser beam intensity by varying the size of the wedges.

4. The method according to claim 1 or 2, including providing a movable deflecting element in the path of the plurality of laser beams between the multiple wedge plate and the converging lens and moving the deflecting element transversely in the path to produce a zigzag on the focal plane.

5. The method according to claim 4, wherein the deflecting element comprises two wedges formed on either side of an axis at a desired angle from horizontal.

6. An apparatus for welding plastic comprises:

means for producing a laser beam;

lens means downstream of the means for producing for collimating the laser beam;

means for splitting the collimated laser beam into a plurality of beams comprising comprising a plurality of wedges which corresponds to a desired number of laser points to be produced, wherein the wedges are offset from horizontal at a desired angle; and

converging lens means downstream of the splitting means for producing a plurality of laser points on a focal plane of plastic to be welded.

7. The apparatus as claimed in claim 6, further comprising a transparent ball which is transparent to the laser beam is arranged downstream of the converging lens means and is mounted rotatably in a processing head.

8. The apparatus as claimed in claim 6, wherein the means for splitting comprises a multiple wedge plate comprising a double wedge plate, and located between the double wedge plate and the converging lens are two deflecting wedges that run with contact edges parallel to contact edges between the double wedge plate, and further including means for moving the two deflecting wedges to and fro transverse to the laser beam.