A NOZZLE AND A METHOD FOR FEEDING THERMOSETTING PLASTIC

Abstract: A nozzle for feeding a mixture of thermosetting plastic and hardener from a mixing chamber, to which feed lines for supply of thermosettable plastic as well as the hardener are connected. The mixing chamber communicates with at least two beam channels (14) having a diameter (b) of 0.5-1.5 mm, which converge in an angle ( alpha ) of 70-140 DEG towards a point outside the nozzle. By feeding a mixture of thermosetting plastic and hardener via the nozzle, the mixture has a viscosity of between 150 and 75.000 cpois, and that the mixture is extruded from the nozzle with a pressure of 75 to 100 bar.

Description: Title A nozzle and a method for feeding thermosetting plastic TECHNICAL FIELD The present invention refers to a nozzle for feeding a mixture of thermosetting plastic and hardener from a mixing chamber, to which feed lines for supply of ther osettable plastic as well as hardener are connected. The invention also refers to a method for feeding the mixture. BACKGROUND OF THE INVENTION Thermosetting plastics, for instance polyester, urethan and epoxy can be mixed in fluid state and are fed out by means of a spray-gun, which is equipped with a nozzle providing a defined spray image. In this way, the plastic can be app¬ lied, e.g. in a mould for casting plastic products. Generally, solvent agents are needed as gelling agent in the plastic, to allow it to receive correct viscosity for spray¬ ing through the nozzle. This known technic involves drawbacks, as one generally has to calculate with a certain amount of spillage, when plastic due to an uncontrollable spray image wrongly lands in the mould or next to it. This spillage results in consuming an unnecessary large amount of plastic and also solvent agents. For environmental reason such a spillage should be mini- mized. Furthermore, it becomes difficult to maintain an even and high production quality, if one does not have control over the amount of plastic fed out per unit area. CONFIRMATION COPY The amount of the spillage will not be reduced, if the spray-gun, when spraying according to prior art, is moved closer to the surface to be covered with the thermosetting plastic, as drops of thermosetting plastic hitting a surface with a grate force, tend to brake into smaller drops, which rebound back towards the spray-gun. THE TECHNICAL PROBLEM An object of the present invention is therefore to provide a nozzle of a type described initially, which makes it possible to hold the spray-gun closer to the surface to be covered without risk for back-spray, and which provides a stable and well-defined spray image with distinct edges. THE SOLUTION For this object the nozzle according to the invention is characterized in that the mixing chamber communicates with at least two beam channels having a diameter of 0.5-1.5 mm, which converge in an angle of 70-140° towards a point outside the nozzle. The method according to the invention is charac¬ terized in that the mixture of plastic and the hardener has a viscosity between 150 and 75.000 cpois, and that the mixture is extruded from the nozzle with a pressure of 75 to 100 bar. Through the present design of the nozzle small plastic drops having uniform size are produced, which move with low speed towards the surface to be covered. In this way a surprisingly well-defined spray image is obtained, without risk for back spray. DESCRIPTION OF THE DRAWINGS The invention will be described with reference to an embodi¬ ment, which is shown on the enclosed drawings, wherein: Fig. l shows a section along line I-I in Fig. 2 through a nozzle according to the invention, Fig. 2 is a bottom view of the nozzle, and Fig. 3 shows the nozzle schematically in pers- pective under use. DESCRIPTION OF EMBODIMENT The nozzle in Fig. 1-3 iε made of a metallic cylinder 10 with mounting flange 11 formed through turning. The end of the cylinder closest to the flange exhibits a concentric turned space 12. The opposite end of the cylinder is pro¬ vided with two towards each other inclining plane surfaces 13, sloping towards the longitudinal axis of the cylinder, with a mutual divergent angle. The angle between said plane surfaces can be between 70° and 140°. A beam channel 14 is bored in each plane surface 13, sub¬ stantially perpendicular to each plane surface. The two channels 14 are consequently drilled with such a mutual angle α that they converge towards a point outside the nozzle. The angle α between both beam channels is between 70° and 140° and channels extend into the space 12. Each channel 14 has a diameter b of 0.5-1.5 mm and the distance a between the downstream mouth of the beam channels is 2-5 mm. The nozzle is used mounted on the outlet from a mixing chamber on the spray-gun, which mixing chamber is fed with plastic and hardener via separate feed channels. Mixture of plastic and hardener should have a viscosity between 150 and 75.000 cpois and feed pressure is suitably between 75 and 100 bar. The nozzle with this equipment can be used, e.g. in combina¬ tion with the nozzles for feeding cut reinforcement fibres, to spray composite laminate directly in a mould, for exam¬ ple, by means of an industrial robot. The nozzle can also be used without addition of fibres, to cover a surface with a layer of thermosetting plastic, for example a floor area. The spray image has a narrow elliptical form with distinct edges. The invention is not limited to the above described embodi¬ ment, but variants may occur within the scope of the at¬ tached claimε. For instance the nozzle may be equipped with more than two spray channels. By using more spray channels the spray image can be affected.

Claims: CLAIMS 1. A nozzle for feeding a mixture of thermosetting plastic and hardener from a mixing chamber, to which feed lines for supply of thermosettable plastic as well as the hardener are connected, characterised in, that the mixing chamber communicates with at least two beam channels (14) having a diameter (b) of 0.5-1.5 mm, which converge in an angle (a) of 70-140° towards a point outside the nozzle. 2. A nozzle according to claim 1, characterised in, that the distance (a) between the downstream outlets of the beam channels (14) is 2-5 mm. 3. A nozzle according to claim 1, characterised in, that each beam channel (14) extends towards and discharges substantially perpendicular to a plan surface (13) . 4. A nozzle according to claim 1, characterised in, that the surfaces (13) are shaped with mutual divergent angle of 70°-140° towards each other inclining plan. 5. Method for feeding a mixture of thermosetting plastic and hardener via a nozzle that includes a mixing chamber, to which feed lines for supply of thermosettable plastic aε well as hardener are connected, and which chamber communi¬ cates with at least two beam channels (14) having a diameter (b) of 0.5-1.5 mm, which converge in an angle (α) of 70-140° to a point outside the nozzle, characterised in, that the mixture of plastic and hardener has a viscosity of between 150 and 75,000 cpois, and that the mixture is ex¬ truded from the nozzle with a pressure of 75 to 100 bar.

Inventors: SAND KJELL, SAND, KJELL
Applicants: APLICATOR SYSTEM AB, SAND KJELL, SAND, KJELL
Application year: 1996
Main classification: B05B7
IPC codes: B05B7