Process for welding hollow articles

• US 6,372,079 B1
• Filed: 07/16/1999
• Issued: 04/16/2002
• Est. Priority Date: 07/22/1998
• Status: Expired due to Fees

• Current Assignee: Solvay Polyolefins Europe-Belgium (Societe Anonyme)
• Original Assignee: Solvay SA (Solvac SA)
• Inventors: De Beeck, Joel Op, Van Meulebeke, Guy, Coninck, Hubert, Van Schaftingen, Jules-Joseph, Gilliard, Pierre
• Primary Examiner(s): Aftergut, Jeff H.
• Assistant Examiner(s): Kilkenny, Todd J.
• Application Number:
  US09/354,172
• Time in Patent Office: 1,005 Days
• Field of Search: 156/304.2, 156/304.6, 156/304.5, 156/499, 156/292
• US Class Current: 156/304.2
• CPC Class Codes: B29C 65/203 being several single mirrors, e.g. not mounted on the same tool
• CPC Class Codes: B29C 65/2061 by sliding
• CPC Class Codes: B29C 65/245 the heat transfer being achieved contactless, e.g. by radiation B29C65/32 takes precedence
• CPC Class Codes: B29C 65/26 Hot fluid
• CPC Class Codes: B29C 65/28 Flame or combustible material
• CPC Class Codes: B29C 65/30 Electrical means B29C65/38 takes precedence
• CPC Class Codes: B29C 65/32 Induction
• CPC Class Codes: B29C 65/7802 Positioning the parts to be joined, e.g. aligning, indexing or centring
• CPC Class Codes: B29C 65/7847 using vacuum to hold at least one of the parts to be joined vacuum work holders in general B25B11/005
• CPC Class Codes: B29C 65/7858 characterised by the feeding movement of the parts to be joined
• CPC Class Codes: B29C 66/0222 without removal of material, e.g. cleaning by air blowing or using brushes
• CPC Class Codes: B29C 66/0242 Heating, or preheating, e.g. drying B29C66/3464 takes precedence
• CPC Class Codes: B29C 66/1312 Single flange to flange joints, the parts to be joined being rigid the parts to be joined being flexible B29C66/133
• CPC Class Codes: B29C 66/54 Joining several hollow-preforms, e.g. half-shells, to form hollow articles, e.g. for making balls, containers; Joining several hollow-preforms, e.g. half-cylinders, to form tubular articles
• CPC Class Codes: B29C 66/71 characterised by the composition of the plastics material of the parts to be joined welding bar compositions B29C65/125
• CPC Class Codes: B29C 66/723 being multi-layered B29C66/7292, B29C66/72941 take precedence
• CPC Class Codes: B29C 66/80 General aspects of machine operations or constructions and parts thereof
• CPC Class Codes: B29C 66/81265 Surface properties, e.g. surface roughness or rugosity
• CPC Class Codes: B29C 66/8242 Pneumatic or hydraulic drives using fluid pressure directly acting on the parts to be joined B29C66/8266
• CPC Class Codes: B29C 66/83221 cooperating reciprocating tools, each tool reciprocating along one axis
• CPC Class Codes: B29C 67/0048 : Local deformation of formed objects
• CPC Class Codes: B29K 2023/00 : Use of polyalkenes or derivatives thereof as moulding material
• CPC Class Codes: B29K 2061/00 : Use of condensation polymers of aldehydes or ketones or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2067/00 : Use of polyesters or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2077/00 : Use of PA, i.e. polyamides, e.g. polyesteramides or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2105/06 : containing reinforcements, fillers or inserts
• CPC Class Codes: B29K 2105/16 : Fillers
• CPC Class Codes: B29L 2009/00 : Layered products
• CPC Class Codes: B29L 2031/7172 : Fuel tanks, jerry cans

Abstract

Machine for welding hollow articles and process for welding these articles, for example half-shells of a plastic fuel tank, using the technique of hot-plate welding, in which the mirror is in the form of separate elements which can be moved independently. Particular processes in which the articles to be welded together are preshaped by pressing against cold-plate elements, which might not be plane, by stretching or compressing the side walls of the articles or by pressing against the walls of a mould. Process applied to the manufacturer of injection-moulded/welded fuel tanks. Use of the machine for manufacturing such tanks.

Claims

1. Process for welding together edge to edge hollow plastic articles in the form of plastic shells for the manufacture of a fuel tank in a welding cycle in which:

a) at the start of a cycle, at least two articles to be welded together are positioned so as to present parts of a surface of each hollow article which will be heated and brought into contact with a corresponding surface of another article and defining weld lips face to face;

b) articles are shaped in four steps as follows in order to achieve a better correspondence of the weld lips;

1) at least two cold plate elements, a temperature of which is below that required to cause local melting of the plastic of the lips in contact with the plate elements, are moved separately and brought between the weld lips of each article which are placed opposite each other;

2) the articles are pressed against the cold-plate elements with a pressure and for a time which are necessary for deforming a profile of the weld lips and to better adjust their correspondence;

3) the articles are moved away from the cold-plate elements, and

4) the cold-plate elements are withdrawn;

c) 3 to 8 separate hot plate elements are moved separately and brought between the weld lips of each article which are placed opposite each other, a temperature of the plate elements being sufficient to be able to melt, by contact, the plastic to be welded,

d) the articles are pressed against two faces of the hot-plate elements for a time at least sufficient to start to melt the articles on a surface of the lips in contact with the hot-plates;

e) the articles are moved away from the plate elements;

f) the plate elements are withdrawn;

g) the articles are pressed against each other so as to bring the heated lips into contact for a time necessary for welding and for returning a molten material to a solid phase and

h) the assembly thus obtained is removed.

2. Process according to claim 1, characterized in that the cold-plate elements and the hot-plate elements are separate regions of the same plate elements.

3. Process according to claim 1, wherein the hollow plastic articles are formed by injection molding.

4. Process according to claim 2, wherein the hollow plastic articles are formed by injection molding.

5. Process for welding hollow plastic articles in a welding cycle in which:

a) at the start of a cycle, at least two articles to be welded together are positioned so as to present face to face parts of a surface of each hollow article which will be heated and brought into contact with a corresponding surface of another article and defining weld lips;

b) articles are shaped in four steps as follows, in order to achieve a better correspondence of the weld lips;

1) at least two cold-plate elements, the temperature of which is below that required to cause local melting of the plastic of the weld lips in contact with the cold plate elements, are moved separately and brought between the weld lips of each article which are placed opposite each other,

2) the articles are pressed against the cold-plate elements with a pressure and for a time which are necessary for deforming the profile of the weld lips and to better adjust their correspondence;

3) the articles are moved away from the cold-plate elements, and

4) the cold-plate elements are withdrawn;

c) at least two hot-plate elements are moved separately and brought between the weld lips of each article which are placed opposite each other, a temperature of the two hot plate elements being sufficient to melt, by contact, the plastic to be welded;

d) the articles are moved away from the hot-plate elements;

e) the hot-plate elements are withdrawn;

f) the articles are pressed against each other so as to bring the heated lips into contact for the time necessary for welding and for returning the molten material to the solid phase; and

g) an assembly thus obtained is removed.

6. Process according to claim 5, characterized in that the cold-plate elements and the hot-plate elements are separate regions of the same plate elements.