NL8502453A - Producing mould to mfr. fibre reinforced plastic ships hull - by building mould wall from foam plastic blocks in rectangular container, machining cavity contour, and opt. lining cavity wall - Google Patents

Abstract

The method is for producing a mould for the mfr. of a buoyant body, e.g. a ship or boat, from setting material, e.g. fibre-reinforced plastics, where the contour of the mould cavity corresponds with that of the outer hull surface. It comprises filling a container with side and end walls and a bottom with settable foam material and forming the cavity in it. The filling is pref. built-up from blocks of already set foam leaving a space which is smaller than the required cavity, this cavity then being produced by a rotary cutting operation or with a heated cutting blade. The cavity wall may be lined with a material compatible with the plastic used to form the hull.

Description

NO3318

A method of manufacturing a mold intended for manufacturing a buoyancy body such as a ship.

The applicant mentions as inventor: Ir. Jozef Wilhelmus Theresia Werneke 5 in Schelluinen.

The invention relates to a method for manufacturing a mold intended for manufacturing a buoyancy body, such as a ship, from a hardenable material, such as a fiber-reinforced plastic, which mold must have a mold cavity corresponding to with the outer shape of the buoyant body, such as the outer shape of a ship's hull.

Such a method is known in the manufacture of a mold cavity or mold in which the hull of a ship composed of plastic can be manufactured. For the production of such a mold, steel plates are used, which are bent and welded together to obtain a shape which essentially corresponds to the shape of the hull of the ship to be subsequently manufactured from plastic. These steel plates, which determine the mold cavity, are fixed outwards on 20 supports resp. provided with stiffeners for the strength of the mold cavity as a designer. The entire mold is divisible and usually consists of two parts, each defining about half of the mold and releasably connected at the bottom by a support beam, which is vertically movable enough to promote loosening of the molded parts and on which the keel of the hull to be manufactured can rest. In the contiguous position, these two parts and the support beam form the mold cavity. After the manufacture of a body in the mold cavity from, for example, fiber-reinforced synthetic resin, the manufactured body is lifted slightly by means of the support beam and at least one of the halves of the mold is moved away sideways, so that the obtained body is displaced from the mold can be removed.

The manufacture of the known mold from steel plate with associated supports and facilities for its displacement is extremely expensive and only usable for a single type of ship. In fact, a ship's hull is first manufactured from steel, which is not reinforced with rafters on the inside, but with supports on the outside.

In this known mold, several ships of the same type can then be manufactured; however, deviations or type changes are excluded. A new mold is required for this.

The object of the invention is now to provide a method with which 8502 453 2 / * it is possible in a simple and inexpensive manner to manufacture a mold, which can be used several times, is considerably lighter in construction and which is at least partly suitable or suitable can be made for the manufacture of buoyancy bodies, such as ships of other shapes.

According to the invention, this object is achieved in that a filling of hardenable foam material is placed in a container with longitudinal and transverse walls and a bottom and the mold cavity is arranged in that material. According to the invention, the container, which can take the form of a very large open box, is filled with foam, depending on the dimensions of the body to be manufactured. In it, the mold cavity is made by some suitable operation, such as a rotary machining operation or a device operating with a heated cutting blade. Other possibilities are also conceivable.

This container can be relatively light, because it initially only has to bear the weight of the foam material, which foam material can be, for example, polystyrene foam or polyurethane foam. This foam can be placed in the container by spraying the components therein and foaming it until a sufficiently large filling is obtained, after which the desired mold cavity is cut therein. This foam filling can of course also be applied by other techniques.

Preferably, the filling is made up of blocks of already hardened foam material, leaving a cavity smaller than the mold cavity. Such blocks can easily be stacked and joined together, for example by gluing or by mechanical means, such as a tongue and groove, after which only the excess material needs to be removed from the foam blocks. The container for the mold cavity defining foam material need not be strong and can easily be increased or decreased in size. If one wants to manufacture a body of different dimensions or other shape and the contours of a part of the mold cavity already manufactured are no longer usable, the foam is removed from older, new foam is applied, for example in the form of new blocks and added the new shape in the filling. In this way great flexibility is obtained.

In the known method of manufacturing a hull of fiber-reinforced synthetic resin, layers of synthetic resin impregnated cloth are subsequently applied to the wall of the mold cavity, which function as a reinforcement and in this way the strength of the hull wall of 8502 453 is built up. 3 the ship to be manufactured, while the rafters of the ship are connected in a comparable manner to the inner surface of the obtained plastic hull using lost cores. The fact that during the manufacture of such a hull it acquires its own strength and thus load-bearing capacity, progressively with the structure 5 and the hardening of the synthetic resin, plays no role whatsoever within the known mold consisting of steel, because it is without a doubt capable of increase the weight of the resulting forces, the more so because the majority is nevertheless carried by the bottom or central support beam.

In the context of the present invention, however, the gradual build-up of self-strength plays an important role in the manufacture of the hull from fiber-reinforced plastic. After all, the mold consisting of container and plastic foam does not now have to bear the weight of the hull, but only the low weight of the first layers as long as they have not yet hardened. With the increase in the number of layers, the weight increases, but also the strength, so that the actual load on the wall of the mold cavity remains small. This is all the more so because the forming wall itself will also provide design support for the further layers and parts to be applied.

The plastic foam from which the mold is made can be any suitable type of foam. The invention is therefore not limited to the use of polystyrene foam or polyurethane foam. A certain strength is desired and can be supplemented by reinforcement or coating of the surface. The foam can have a composition which results in a density of between 10 and 40 kilograms per m3, preferably 18 to 30 kilograms per m3. Other values are however conceivable. The mold according to the invention can thus be manufactured from inexpensive material, which greatly reduces the costs of manufacturing, for example, a ship.

According to the invention, it is preferable if the wall of the mold cavity obtained is coated with a layer which is neutral with respect to the material from which the body is manufactured in the mold cavity.

Such a coating can have several functions. For example, after machining it may be necessary to smooth the surface of the mold cavity using the coating.

Protection against impact and thus damage to the wall of the mold cavity is also a task of the coating. It must therefore have a greater hardness or firmness. When moving parts of the mold, stability is needed and the covering can then be 85 02 45 3 ·? * 4 ensure that during transport, for example with hoisting devices, no damage occurs to the mold cavity surface.

A smooth wall of the mold cavity promotes unloading and limits the need to apply fabrics that promote unloading.

It is of great importance that the materials used in the manufacture of a body in the mold cavity, such as a ship's hull, do not come into conflict with the foam material.

For example, if polystyrene foam is used and the hull to be manufactured in the mold cavity is made of glass-fiber reinforced polyester, the styrene contained therein will adversely affect the polystyrene foam and damage the shape. The coating must therefore provide a barrier, i.e. care must be taken to ensure that the mold cavity and the material to be incorporated therein are chemically compatible with each other and are therefore neutral with respect to each other.

This coating can be formed by an epoxy resin, a polyurethane resin, plaster with urethane lacquer, a wax layer and many others. The determining factor here is the nature of the surface obtained after processing, the nature of the foam and the materials used for the manufacture of a body in the mold cavity. For example, if it is formed by polystyrene foam and an epoxy resin is used in the manufacture of the body, then the coating is not necessary to obtain a chemical neutrality. However, if polyester is used, as already mentioned, this is necessary.

Instead of polystyrene foam or polyurethane foam, other foams are also conceivable, such as polyvinyl chloride foam, phenolic resin foam, polyether foam or polyethylene foam, provided that they are sufficiently rigid after the surface has been reinforced.

Various methods can be used to produce the mold cavity in the foam filling by means of a suitable processing device. Thus, first of all, grooves can be provided therein, which correspond in shape and location to the rafters according to the rafter plan of the body to be manufactured, after which the material is removed between the successive grooves. This can be done, for example, with the aid of molds derived from the rafter plan and with the aid of which the successive grooves are made, either with hand-operated tools from a work platform or with the aid of remote-controlled tools.

However, it is also possible for the mold cavity to be manufactured in the cured foam material using a numerically controlled 40 machine which provides positioning control signals 8502 45 3 5 V λ in three perpendicular directions, which signals are derived from the shape of the body to be manufactured in the mold cavity, such as, for example, a model of the hull of a ship.

This numerical control can be used for manufacturing the grooves and for later removal of the remaining parts, but it can also be used such that the processing device advances through the foam mass according to the three perpendicular directions in the main directions signals. Preferably, a gantry crane is used, which carries a working platform adjustable in vertical direction, from which the manually controlled or numerically controlled processing of the foam can take place. This gantry crane with work platform is movable over the jig in the longitudinal direction thereof and each work platform is movable transversely of the longitudinal direction and movable in height direction. This portal crane is known per se in the manufacture of a ship's hull in a steel mold for applying the resin-impregnated cloth to the wall of the mold cavity. According to the invention, the same device can now also be used for making the mold cavity.

In the method according to the invention, for the production of the mold cavity, use can be made of the CAD / CAM techniques known for the production of hulls.

The invention also relates to the device for applying the method according to the invention and this device is characterized in that the container consists at least of parts which define vertical supporting surfaces and which have supporting members remote from the mold cavity, which parts are divisible at least along a plane parallel to the central part plane of the mold cavity.

While the known system required a heavy mold, according to the invention a light construction consisting of walls, which must support the foam filling laterally, and which can thus consist of plates or of a trellis, suffices to the rear. must be supported away from the mold cavity and which are on the floor or have an associated own bottom. The divisibility, known from the steel mold, is also applicable here, but in a simpler manner, because it is easier to share the supporting surfaces in the longitudinal or transverse direction, and thus also more easily to add or omit pieces, for example if one wants to overlay with a foam filling. to manufacture another mold cavity.

The invention will now be explained differently with reference to the drawings.

8502 45 3 6

Fig. 1 is a perspective view of a container for making a mold cavity therein.

Fig. 2 is a section through the container of FIG. 1 filled with foam blocks.

FIG. 3 shows a possibility for manufacturing the mold cavity.

Fig. 4 is a perspective view of the molded plastic foam cavity with the container omitted for clarity.

Fig. 5 shows the application of a coating.

FIG. 6 is a sectional view of a fully manufactured mold.

Fig. 7 schematically shows the method of manufacturing a ship's hull in the mold of FIG. 6.

Fig. 8 shows the molded hull of a ship in a further phase.

FIG. 9 serves to explain the unloading of the manufactured hull.

Fig. 1 shows an empty container 1 with outside of it a stack 2 of foamed plastic blocks which have been manufactured in advance. The one shown in FIG. 1, the holder or supporting mold shown has longitudinal walls 3 and 20 transverse walls 4, respectively, which walls can consist of parts, as indicated by the dividing lines 5, and which can be further attached to floor supports 6 and have vertical supporting backs 7.

Fig. 2 shows the in FIG. 1, a cross-section of a holder or support mold shown therein, containing a stack of not yet processed foam blocks, such as 8, 9, 10 and 25 11, of different dimensions, placed on either side of a support beam 12 known per se. by means of glue 13 or by a tongue and groove. The inner surface formed by the blocks leaves a cavity 14 which is smaller than the foam cavity to be manufactured later in the foam, which is indicated by a broken line 26.

Fig. 3 shows that a gantry crane 15 is mounted above the mold, which is movable on rails 16, 17 in the longitudinal direction of the mold. Movable in transverse direction relative to said longitudinal direction, a work platform 18 is attached to the gantry, namely at the lower end of a vertically adjustable column 19. Thus, the work platform 18 can be moved in the longitudinal direction, in the transverse direction and in the vertical direction. A device 20 is attached to the work platform with a machining machining device 21. This can now remove the excess foam material, either by working along 40 vertical planes and cutting grooves according to successive clamping lines, or through the mold cavity point by point. depending on a numerical control.

Fig. 4 shows that in this way a mold can be obtained with the mold cavity and built up from large sections or pieces, which are located within the supporting mold, which in FIG. 4 is omitted for clarity. Each in FIG. 4 shown may consist of blocks omitted for clarity.

Fig. 4 also shows that for extension of the support jig one can easily add a section where, for example, the hull dimensions remain the same, which is the case with certain ship shapes. One can then make a longer body or, conversely, a shorter body.

However, it will also be clear that it takes little effort to apply a new mold cavity in a new filling of plastic foam.

Fig. 5 shows how a coating layer 22 can be applied with the same gantry crane 15 by spraying, rolling or brushing.

Eventually, the result shown in FIG. 6 molded cavity shown in cross-section with an inner wall 22, for example epoxy resin, or lining 22.

Fig. 7 shows how one can then again build the hull using the same portal crane 15 by applying either pre-impregnated cloth or resin and cloth to be applied to the resin according to a technique which is known per se and is also applied in the steel mold. If the hull has been built up in this way and, where necessary, provided with rafters and decks 23, 24 made of plastic elsewhere, then a hull has been obtained which has sufficient strength of its own to be released from the mold (Fig. 8).

Fig. 9 shows this in that one part of the mold has been displaced laterally. Preferably, the trunk is lifted slightly beforehand with the aid of the support beam 12. After sliding part of the mold sideways, as shown in Fig. 9, additional supports 25 can then be provided and finally the hull can be completely removed from the mold by displacement in transverse and longitudinal direction.

This can then be closed again to produce the next hull. Should this become a completely different hull, then the foam plastic filling is removed, which is possible by dividing it into sections, as shown in Fig. 4, after which a new filling with blocks is applied and another form is applied in the manner already described.

8502453 8

The method according to the invention lends itself to manufacturing molds with which both small and very large ships can be manufactured from plastic.

8502 453

Claims (14)

1. A method for manufacturing a mold intended for manufacturing a buoyancy body, such as a ship, from a hardenable material, such as a fiber-reinforced plastic, which mold must have a mold cavity corresponding to the outer shape of the buoyancy body, such as the outer shape of the hull of a ship, characterized in that a filling of hardenable foam material is placed in a container with longitudinal and transverse walls and a bottom and the mold cavity is arranged in that material. 2. A method according to claim 1, characterized in that the filling 15 is built up of blocks of already hardened foam material, leaving a cavity smaller than the mold cavity to be manufactured. Method according to claim 1 or 2, characterized in that the mold cavity is introduced into the foam material with the aid of a processing device. Method according to claim 3, characterized in that the machining is a rotary machining operation. 25 Method according to claim 3, characterized in that the processing takes place with a heated cutting blade. 6. Method according to one or more of the preceding claims, characterized in that the wall of the mold cavity obtained is coated with a layer which is neutral with regard to the material from which the buoyancy body is made in the mold cavity. Method according to one or more of the preceding claims, characterized in that the foam material is a polystyrene foam. 35 Method according to one or more of the preceding claims 1 to 6, characterized in that the foam material is a polyurethane foam. 85 0 2 4 5 3 «· -tf 9. Method according to one or more of the preceding claims, characterized in that the foam material has a composition such that its density is between 10 to 40 kilograms per m 2, preferably 18 to 30 kilograms per m 3. Method according to claim 6, characterized in that the coating consists of a layer of epoxy resin. Method according to claim 6, characterized in that the coating consists of polyurethane resin. 12. Method according to one or more of the preceding claims 1 to 5, characterized in that the mold cavity is arranged in the hardened foam material by firstly arranging grooves therein which correspond in shape and location to the rafters according to the truss plan of the body to be manufactured and then the material between the successive grooves is removed. Method according to one or more of the preceding claims 1 to 5 and claim 12 respectively, characterized in that the mold cavity is manufactured in the hardened foam material using a numerically controlled processing device to which positional control signals are given in three perpendicular to each other standing directions, which signals are derived from the shape of the body to be manufactured in the mold cavity, such as, for example, from a model of the hull of a ship. Device for applying the method according to one or more of the preceding claims, characterized in that the holder consists at least of 30 parts which define vertical support surfaces for the material determining in the cavity and which have support members remote from the mold cavity, which parts are divisible at least along a plane parallel to the central part plane of the mold cavity. 8502 45 3