Plastic and nonmetallic article shaping or treating: processes – Direct application of fluid pressure differential to... – Producing multilayer work or article
Patent
1996-12-20
1998-12-29
Vargot, Mathieu D.
Plastic and nonmetallic article shaping or treating: processes
Direct application of fluid pressure differential to...
Producing multilayer work or article
114357, 264225, 264254, 264255, 264257, 264258, B36B 524
Patent
active
058536507
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to a method of manufacturing boat hulls, in a female mould, i.e. a mould whose inner side is made to determine the shape of the hull. The hull is manufactured by applying material, for example glass fibre reinforced plastic, to the inner side of the female mould, the mould surface, and let the material harden to form a shell that is comprised by the load carrying structure of the hull. This shell may be a single shell or the outer shell of a sandwich construction.
STATE OF THE ART
According to customary technique, a boat hull can be manufactured by applying the material that will form said structural shell directly on the mould surface of the female mould. This can be made, for example, by spraying chopped glass fibres mixed with liquid plastic resin on the release agent treated mould surface in a layer that is varying in thickness depending on the strength requirements set up for different parts of the hull. Another way is by using hand lay-up technique which means that plastic resin impregnated fibre reinforcement material in the form of mats or weaves is applied in the mould In several layers. Air voids and excessive resin is taken away by the use of a roller.
After the material has been applied In the mould, it is allowed to cure and the rigid structural shell is formed. The outer surface of the shell will thus be determined by the shape of the mould. To achieve a smoother surface In a desired colour, normally a surface layer, for example gelcoat, is sprayed on the mould surface before the reinforcement provided resin is applied. The gelcoat layer and the reinforced plastic form together the rigid structural shell.
A hull made in this manner has a good structural strength. The hard structural shell is however sensitive to wear and crushing loads. It is customary that the hull can be protected from this sort of loads by attaching a sheet of rubber material on the bottom surface of a finished hull. If a proper material is used, a very effective protection can be obtained. The fatal pressure that a point shaped object like the tip of a stone may create on the naked surface of the hull, is by the rubber sheet distributed to a larger area of the hull and by that becomes harmless. By using a sufficient thickness of the rubber sheet and a highly elastic and wear resistant material, the risk for crushing and wear damages is decreased significantly. However, a boat that is supplied with such a rubber sheet attached to the hull has the following disadvantages: sheet and the hull remaining from the glueing operation of the sheet might later cause debonding. irregularities in the hull surface. These cause losses in speed and reduction of the service range. In addition these irregularities provide points of action for e g rocks etc. to catch and then tear the sheet off. consuming and costly. surface of the boat which reduces the performance of the boat. an effective material should not be too elastic.
DESCRIPTION OF THE INVENTION
The object of the invention is to provide an improved method to manufacture plastic boats having a rigid shell in a female mould without having the disadvantages above. Specially for landing crafts the following requirements are called for: disembark troops. In addition the boats must be able to easily come off the shores. in order to make the boats seaworthy and to withstand rough handling. have unnecessary hydrodynamic resistance which will reduce the speed and service range.
According to the invention there is proposed that at least one outer protective layer of a material that is softer and more elastic than the material of the structural shell, such as a highly elastic and wear resistant plastic or rubber material, is integrated into the rigid shell when the hull is manufactured. This is accomplished by Introducing the elastic protective layer to the prospective hull already at the initial phase of the manufacturing process, i.e. before the rigid structural layer within is applied, by first applying the elastic layer in the female mould and
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H.ang.kanson Petter
Lonno Anders
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