FR2683746A1 - METHOD AND INSTALLATION FOR MAKING A SURFACE COATING ON ARTICLES BASED ON SYNTHETIC RESINS OR SIMILAR MATERIALS. - Google Patents

Abstract

Method and installation for carrying out a surface coating on articles (1) based on synthetic resin or similar insulating material, of the type according to which the objects to be treated (1) are arranged on supports (2) in the form of hanging swings to a conveyor (3) connected to the mass, allowing them to travel along the successive treatment zones. It is characterized in that: - the articles (1) are held vertically on the swings (2), ensuring their movement in the different treatment zones by means of supports (8) which are good conductors of electricity, ensuring contact. continuous with the surface of the object (1) to be coated; - the projection of the coating product is carried out by means of a nozzle (6) forming a cloud of particles in the form of a paraboloid, the passage of the objects (1) being carried out such that it passes through the cloud of particles at the level of the base of the paraboloid that they define.

Description

METHOD AND INSTALLATION FOR REALIZING A COATING

  SURFACE ON ARTICLES BASED ON SYNTHETIC RESINS

OR SIMILAR MATERIALS.

  In many technical sectors, more and more parts are used made from synthetic resins, the oldest and best known of them being that known under the name of "Bakelite". Among the many applications of such materials, it should be noted more particularly the realization of the handles, handles and other items of kitchen utensils, which is the consequence of the fact that such materials are by nature insulating In the following the

  description, the invention will be described for such applications, but it is

  obvious that the invention could also be applied to any other

  type of part for which similar problems arise.

  To date, to perform a surface finishing treatment for the handles or handles of cooking utensils, and more particularly the coloring of these elements, various techniques are used In all cases, the surface of the surface is cleaned beforehand. produced, then a staining operation obtained either by dipping or by spraying with pneumatic guns. While these techniques make it possible to continuously treat the products and lead to articles having a good quality, on the other hand, they cause a great deal of

  consumption of coloring matter.

  Of all the surface coating processes proposed to date, the one known under the term "electrostatic coating" can be considered as the most efficient, in particular as regards the production rates and the yield of dyestuff used. The method currently used for coating metallic objects consists, generally, in such installations, the objects to be treated are placed on supports in the form of "swings" attached to a conveyor connected to ground, this which makes it possible to route the products along the successive treatment zones, essentially comprising a zone for cleaning the surface, a coating zone proper essentially comprising an electrostatic projection apparatus, such as for example of the type described in FR-A. A-2 137 357, followed by a heat treatment zone

  to ensure the "baking" of the coating paint.

  If such a technique is particularly suitable for coating good conductor materials (metal), on the other hand, in the case of objects made in non-conductive materials, such as synthetic resin (Bakelite), their implementation involves prior to coating the surface of the objects with a conductive coating, which

  complicates manufacturing cycles and significantly increases costs.

  It has been found, and this is the subject of the present invention, a method and an installation for its implementation which makes it possible to produce, in a simple and effective manner, a surface coating of articles based on of synthetic resin (or equivalent insulating material), said surface coating being obtained by means of an electrostatic spray installation. In a general manner, the method according to the invention consists in producing, continuously, on an electrostatic projection type installation, a surface coating on articles made of insulating material, based on synthetic resin in particular, of the type according to the invention. which objects to be treated are arranged on supports in the form of swings attached to a conveyor connected to the ground, allowing them to travel along successive treatment areas essentially comprising a surface cleaning area, a coating area itself essentially comprising an electrostatic spraying apparatus and a heat treatment zone making it possible to "cook" the coating, and it is characterized in that: the articles are held vertically on the swings ensuring their displacement in the different treatment zones; intermediates, good conductors of electricity, ensuring contact t continuous with the surface of the object to be coated; the projection of the coating product is carried out by means of a nozzle forming a particle cloud in the form of a paraboloid, the passage of the objects to be coated being made so that they pass through the cloud of

  particles at the base of the paraboloid that they define.

  According to a preferred embodiment of the method according to the invention, each swing supporting the objects to be coated is in the form of a rack having a pole-shaped amount that can be hooked to the conveyor system, and the along which are arranged, at regular intervals, sleepers equipped with organs for holding the objects vertically individually. Such elements making it possible to ensure the individual retention of the objects to be coated, may be in the form of metal pads that can be inserted inside a corresponding internal chamber provided at the base of each object when the latter allows it (for example inside the end of a handle), or possibly in the form of clamps ensuring continuous contact with the surface of the object In the latter case, said clamps are designed to support against non-visible areas during use and after

final assembly of objects.

  The invention and the advantages it brings will however be better understood thanks to the embodiment given hereinafter by way of indication, but not limitation, and which is illustrated by the attached diagrams in which: FIG. 1 is a view schematic showing the assembly of a coating installation designed for the implementation of the method according to the invention; Figure 2 is a detail view in perspective showing the manner in which the coating of the object (sleeve) is carried out in accordance with the method according to the invention; FIG. 3 is a diagrammatic view, also in perspective, showing the manner in which the holding of an object (handle) is ensured on the swing so as to ensure its transport in the different

treatment areas.

  According to the invention, to achieve a surface coating on articles based on insulating materials, such as for example handles, sleeves used in the production of kitchen utensils, an installation of the type illustrated in FIG. 1 is used. and which, in general, allows a continuous coating to be carried out on the surface of the articles. In such an installation, the objects (1) are arranged on supports in the form of swings, designated by the general reference (2) and an embodiment of which according to the invention is illustrated in FIG. 2, and which are attached to a conveyor (3) connected to the mass making it possible to route them along the successive treatment zones essentially comprising a cleaning zone of surface (4), a coating zone proper designated by the general reference (5) and which essentially comprises an electrostatic projection apparatus (6), and a heat treatment area (7)

  to ensure the "cooking" of the coating.

  According to the invention, the articles (1) are held vertically on swings (2) ensuring their displacement in the different treatment areas, and this via supports (8), good conductors of electricity, ensuring a continuous contact with the surface of the object (1) to be coated The projection of the coating product is carried out by means of a nozzle (6) forming a cloud of particles in the form of

2683746

  paraboloid (9), the passage of the objects to be coated being made so that it passes through said cloud of particles at the base of the

paraboloid that they define.

  As an indication, it is possible to achieve a uniform coating on the surface of elements made of "Bakelite", such as handles (Figure 2) or handles (Figure 3) used for the production of kitchen utensils working in the following conditions: the projection nozzle (6) of the electro-aerodynamic type comprising a rotary bowl (10) rotating at a speed of 30 to 35,000 revolutions / minute, having a skirt air pressure of approximately 200 grams, the objects traveling between 30 and 35 cms from the end of the nozzle (6), that is to say, substantially at the paraboloid-shaped particle cloud created by said nozzle (5), the dyestuff used being

  a polyurethane type paint.

  According to a preferred embodiment of the method according to the invention for increasing productivity, the swing (2) supporting the objects (1) to be coated is, as illustrated in Figure 2, in the form of a rack comprising a pole-shaped upright (10) capable of being hooked to the conveyor system (3) and along which are arranged, at regular intervals, crosspieces (llallb, llc) equipped with members (8) making it possible to maintain the objects (1) vertically and individually Such holding elements (8) will be designed according to the shape of the different objects to be coated For example, they will be in the form of pads (8) as shown in FIG. FIG. 2, which can be inserted inside an internal chamber provided at the base of the object when the latter allows it, especially when it is a handle (1) (FIG. in the form of a clamp (8) (Figure 3) to support the object vertically facing the protective nozzle (6) and which leans against areas not

  visible during use and after final assembly of objects.

  For the implementation of the method according to the invention, it can be envisaged to use either a projection nozzle (5) fixedly mounted facing a scrolling zone objects or, when it is desired to treat a large number of objects distributed over several levels as shown in Figure 2, by mounting the nozzle (6) vertically movable on an upright (11), and in synchronism with scrolling objects in the eyes

of said nozzle.

  Such a simple, efficient method makes it possible to continuously process small parts with significantly improved productivity compared with previous solutions using a projection of

  sticky material by means of pneumatic systems.

  If the invention has been described for an installation having only one electrostatic projection assembly, it could be envisaged to make installations comprising several projection assemblies, arranged either side by side or on both sides of the zone. scrolling of objects, especially in the case where the latter have

very complex shapes.

  Of course, the invention is not limited to the embodiment described above, but it covers all variants

realized in the same spirit.

Claims (2)

  1 / Method and installation for producing a surface coating on articles (1) based on synthetic resin or similar insulating material, of the type according to which the objects to be treated (1) are arranged on supports (2) in the form of swings hung on a conveyor (3) connected to the mass, making it possible to route them along the successive treatment zones essentially comprising a surface cleaning zone (4), a so-called coating zone (5) essentially comprising an apparatus electrostatic spraying device (6), and a heat treatment zone (7) for firing the coating, characterized in that: the articles (1) are held vertically on the swings (2), ensuring their displacement in the different treatment areas via supports (8) good conductors of electricity, ensuring continuous contact with the surface of the object (1) to be coated; the projection of the coating product is carried out by means of a nozzle (6) forming a paraboloid-shaped cloud of particles, the passage of the objects (1) being carried out so that it passes through the cloud of   particles at the base of the paraboloid that they define.   2 / A method and installation according to claim 1, characterized in that each swing supporting the objects to be coated is in the form of a rack comprising a pillar-shaped upright (10) capable of being hooked to the conveyor system (3). ), and along which are arranged at regular intervals, sleepers (11a, llbllc) equipped with members (8) for holding the objects (1) individually and vertically.