Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1999-07-15
2001-12-11
Sells, James (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S304600, C156S309900, C156S499000
Reexamination Certificate
active
06328842
ABSTRACT:
The present invention relates to a machine for welding hollow plastic articles.
It relates more specifically to a machine for producing at least one assembly using the hot-plate technique.
The manufacture of articles of complex shape often make use of techniques for assembling smaller elementary articles which it is easier to accomplish in a less sophisticated and smaller apparatus than would be required for manufacturing the complete article.
The use of plastics has, because of their excellent forming and machining properties, allowed the design and production of components and finished articles of the most varied and most complex shapes, very often exceeding by far the versatility of metals and natural materials. As the complexity of the articles manufactured from these plastics has increased, it has, however, nevertheless proved necessary to operate by assembling smaller and less complex components or articles so as to facilitate the manufacturing process and to reduce the cost thereof. Moreover, increasingly the need arises to be able to integrate, more easily than using the conventional methods, ancillary elements inside the articles.
These considerations apply particularly to the field of hollow articles which have to meet complex shape and size requirements, such as those articles used in the most diverse of fields and applications requiring high technical performance. Among such articles, may especially be found tubes and pipes of complex shape which have to fit into confined spaces, as well as bottles and containers which have to be housed in spaces having the most diverse and complex contours.
Plastics are often used for the manufacture of such hollow articles. When their external surface is highly sophisticated, techniques have sometimes been used which involve the assembly of several elements which are simpler to manufacture. In the case of plastics, one favourite technique allows complex hollow articles to be obtained by welding smaller and simpler articles.
Welding hollow plastic articles requires the local melting of the material at the location of the weld lips followed by the pressing of the articles to be welded together until the material of the lips returns to the solid state due to the effect of the cooling. The heat influx required to melt the plastic on the surface of the lips is provided by various processes which include generating heat by, in particular, ultrasound, friction, infra-red radiation or conduction from a heated tool.
One conduction technique has been well developed, namely the technique of welding using a heating tool applied to the weld lips, this technique being called hot-plate welding.
British Patent 1,601,468 describes a process and an apparatus for welding, by means of a hot-plate, rectangular parallelepipedal half-boxes, made of various plastics, which have one face missing so as to obtain a closed box.
The technique is suitable for the production of easily deformable boxes whose thickness is small compared with the other dimensions of the article. The half-boxes to be welded together are each fastened inside a mould and the walls are applied against the internal surface of the mould so as to make the two half-boxes come into perfect correspondence and to present strictly parallel lips during welding.
However, the use of shaping moulds greatly complicates the welding machines because they require bulky machines, the articles to be welded have to be manipulated many times and the articles have to be maintained at the required temperature for long periods. It follows that bulkier and trickier machines have to be used, which machines generally prove to be much more expensive and less reliable than simple welding machines not having means for shaping the articles to be welded together.
The object of the invention is to provide a machine for welding hollow plastic articles which does not have the drawbacks of the known machines. In particular, it relates to machines which are more economical, smaller in size and simpler, which have a shorter cycle time and which allow accessories to be inserted into the assemblies more easily.
For this purpose, the invention relates to a machine for welding hollow plastic articles for the production of at least one assembly using the hot-plate technique, comprising a plate and means for heating this plate (“hot” plate), means for holding and positioning the articles to be welded face to face so as to be able to bring the weld lips together, which weld lips correspond to the surface of each article, means for moving the hot plate between the weld lips and means for pressing the articles against the hot plate, in which it also comprises a plate whose temperature does not allow the plastic with which it may be brought into contact to melt (“cold” plate).
The term “welding” should be understood to mean the operation of joining at least two articles together, which operation comprises a melting step carried out on at least one portion of the surface of each article, a step of bringing the articles into contact with each other and a final step of cooling until the molten material has returned to the solid state, for the purpose of obtaining a composite-article assembly which behaves from a mechanical standpoint as a single article.
The articles to be welded together may be of the same or different nature.
In particular, the articles to be welded together may be made of pure products, chemical compositions, composite materials, alloys or natural substances, these being by themselves or as a mixture.
All types of plastic may be suitable. Very suitable plastics belong to the category of thermoplastics.
Synthetic thermoplastics are preferred. Any type of thermoplastic polymer or copolymer with a melting point below the decomposition temperature is suitable. Synthetic thermoplastics with a melting range spread over at least 10° Celsius are most particularly suitable. Examples of such materials include those which exhibit polydispersity in their molecular mass. In particular, polyolefins, thermoplastic polyesters, polyketones, polyamides and their copolymers may be used. A blend of polymers or of copolymers may also be used, as may a blend of polymeric materials with inorganic, organic and/or natural fillers such as, for example, but non-limitingly, carbon, salts and other inorganic derivatives, glass fibres, natural fibres or polymer fibres. It is also possible to use multilayer structures consisting of layers comprising at least one of the polymers or copolymers described above.
The welding operation may be carried out in the machine according to the invention by adding an additional new material to that of the articles to be welded together. In the case of thermoplastics, it is preferred to use, as new material, a material contained in at least one of the articles to be welded together.
The welding operation may also be carried out without the addition of new material, simply by material interpenetration at the welded surfaces.
The welding machine according to the invention is most particularly well suited to welding without the addition of new material.
The welding machine according to the invention produces assemblies of hollow plastic articles. The term “hollow articles” should be understood to mean any article whose surface presents at least one empty or concave part. In particular, the machine according to the invention is well suited to welding hollow articles which are in the form of plastic shells which are welded together edge to edge.
More than two plastic articles may be welded using the machine according to the invention. Preferably, two articles are welded together.
The machine according to the invention makes it possible to produce at least one plastic assembly simultaneously.
The hot-plate technique employed by the machine according to the invention is based on the principle of the local melting of parts of the surfaces to be welded together, by contact with a heated tool called a plate or “hot” plate. This will be made of a heat-resistant material whose surface roughness is very low so as to maxi
Coninck Hubert
De Beeck Joel Op
Gilliard Pierre
Van Meulebeke Guy
Van Schaftingen Jules-Joseph
Schneller Marina V.
Sells James
Solvay S.A.
Venable
LandOfFree
Machine for welding hollow articles and process for welding... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Machine for welding hollow articles and process for welding..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Machine for welding hollow articles and process for welding... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2587586