WO2008145819A1

WO2008145819A1 - Flexible support for the hatch cover of a vessel

Info

Publication number: WO2008145819A1
Application number: PCT/FI2008/050308
Authority: WO
Inventors: Pentti Tiensuu; Antti Niemi
Original assignee: Teknikum Oy
Priority date: 2007-05-28
Filing date: 2008-05-28
Publication date: 2008-12-04
Also published as: CN101314398A; FI20075380A0

Abstract

Flexible support for the hatch cover of a vessel and a method in the manufacture of the same. The support (12) comprises several parallel superimposed plate layers (18), which are fastened to each other by means of rubber layers (23). The support also comprises a plastic surface plate (19) fastened on top of said plate layers (18) by means of a rubber layer (24); and a plastic bottom plate (21) fastened underneath said plate layers (18) by means of a rubber layer (25). In one embodiment, the support also comprises a bottom plate (20) positioned between the lowermost plate layer (18) and said plastic bottom plate (21) and fastened to said lowermost plate layer (18) and said plastic bottom plate (21) by means of rubber layers (25, 27). In one embodiment the plastic bottom plate (21) or the plastic surface plate (19), or both of them are made of glass fiber reinforced polyamide.

Description

FLEXIBLE SUPPORT FOR THE HATCH COVER OF A VESSEL

Field of the invention

The invention relates to a flexible support for the hatch cover of a vessel. The invention also relates to a method in the manufacture of a flexible support for the hatch cover of a vessel.

Background of the invention

According to prior art, hatch covers that cover and close the cargo hold are applied in vessels intended for diverse cargo. Hatch covers can be for example swinging or sliding covers or covers that can be lifted up. Hatch covers are often equipped with sealings that seal the gap between the hatch cover and the coaming, so that the ambient conditions would not have an impact on the cargo hold.

In vessels carrying freight containers, the freight containers are also loaded^' on top of the hatch covers, and therefore the structure of the hatch covers must be sufficiently durable to carry the weight of the freight containers, and they must also distribute the forces produced by the freight containers on the frame of the vessel, for example via the coaming. The sealings of the hatch cover do not receive said load but elements, such as bearings, supports or pads are positioned between the hatch cover and the coaming, said ele- ments transmitting the forces and allowing the mutual movement of the hatch cover and the coaming, as well as transformations, such as bending of the hatch cover. Forces are directed both to the vessel and to the hatch cover that produce transformations and movement of the hatch cover in relation to the coaming, the deck of the vessel or frame construction of the vessel.

Publication FI-82426-B discloses a bearing supporting the hatch cover, in which a plastic element glides against a steel surface and if necessary, the position of the plastic element can change by means of an intermediate layer made of rubber, if transformations occur in the hatch cover. The plastic ele- ment may be attached to a steel element. Publication FI-110179-B discloses a support integrated in the sealing and composed of at least rubber and metal. The support is flexible and it allows horizontal movement of the cover. Publication US-5464287-A discloses a bearing in which a self-lubricating woven layer is positioned between gliding surfaces, said layer being positioned on top of a PTFE layer. Publication US-4363283-A also discloses a bearing consisting of two parts, said bearing containing parts to be attached to the hatch cover and to the coaming, said parts gliding against each other. Similar bearing is also disclosed in publication DE-3732889-C1. Publication DE-19805765-A1 discloses a bearing comprising an element made of stainless steel, having a PTFR coating on its glide surface. The counter element is also made for example of PTFE, and it is attached to its base by means of a flexible, vulcanized rubber layer. Steel plates are embedded in the rubber layer, which reinforce and stiffen the structure. The bearing allows both the gliding and non-gliding movement of the hatch cover so that only the rubber layer of the bearing yields sideways.

When hatch covers become larger in size and loads grow, the movement of the hatch covers in relation to the coaming increases, wherein it is necessary to increase the size of the bearings based on gliding. At the same time the positioning of the bearings becomes more difficult because of the increasing size. Glide surfaces are subject to wearing and damages and in addition to this, the effect of the ambient conditions, especially in seas causes erosion and corrosion of materials, especially steel. The use of corrosion-resistant and wear-proof materials increases the manufacturing costs and thus also the maintenance costs of the bearings.

A prior art flexible support of a hatch cover is illustrated in Fig. 1 , which shows a transverse cross-section of said support, and in Fig. 2, which shows the longitudinal cross-section of said support. The support is made of rubber material and the different parts are fastened to each other by means of vulcanization. The structure of the support is flexible horizontally, especially sideways, wherein the support adapts to the movements of the hatch cover as shown by broken lines, and gliding with respect to the hatch cover positioned against the upper surface 9 of the support does not occur.

Inside the support there are horizontal steel plates 1 extending in parallel and functioning as reinforcements, The upper part of the support comprises a surface plate 2 made of steel, which is thicker than the steel plates 1. On top of the surface plate 2 there is a protective plate 3 made of stainless steel that extends parallel to the other plates. The lower part of the support comprises a bottom plate 4 made of steel that is thicker than the steel plates 1 , parallel to the other plates and extends beyond the other plates at both ends of the support. In the lateral direction the widths of the plates correspond to each other substantially. The number of the steel plates 1 and the dimensions of the support depend on the load intended to be carried by the support as well as on that how much the support is allowed to yield in the lateral direction.

The steel plates 1 , the surface plate 2, the protective plate 3 and the bottom plate 4 are separated from each other by means of rubber layers 5, 6, 7 and 8. The plates are protected from all sides inside the rubber layer, wherein the ambient conditions are not capable of affecting them. The protective plate 3 and the bottom plate 4 have been covered with a surface layer 9 made of rubber and a bottom layer 10 made of rubber.

The ends of the bottom plate 4 contain holes 11 for fastening members, wherein it is possible to fasten the support to the hatch cover, or alternatively to the coaming or other corresponding structure by means of a screw. For the fastening the bottom plate 4 must be sufficiently strong, as it is imperative that the support remains in its place during use and endures different kinds of impacts. The rubber surface layer 9 of the support may become damaged during use or for other reasons. The rubber bottom layer 10 may become damaged due to irregularities in the surface of the fastening surface. The purpose of the protective plate 3 is to protect the structure and prevent such breakage which would let for example sea water inside the structure. According to prior art, the protective plate 3 is made of stainless steel. The protective plate 3 may also be omitted entirely.

In prior art there are some problems relating to materials. The surface plates rust if the upper surface of the support is damaged and no protective plates are used. On the other hand, the price of stainless steel is considerably higher than the price of more common carbon steels, even three- or fourfold, which affects the price of the support significantly. Thus, it is not advisable to change the material into stainless steel. The weight of large supports in- creases because of the large amount of steel, wherein it is more difficult to handle them. For the sake of the durability of the supports and their reinforcement, the steel structures must be reinforced, which increases the weight. The use of common rusting steel grades only exposes the damaged bearings to rusting, which causes disturbances in the operation and it is difficult to observe damages inside the bearing or rust propagating in the boundary between the rubber layer and steel.

Summary of the invention

It is an aim of the present invention to eliminate the drawbacks presented above.

The flexible support for a hatch cover of a vessel according to the invention is presented in claim 1. The method in the manufacture of a flexible support for a hatch cover of a vessel according to the invention is presented in claim 16.

One objective is a flexible support for a hatch cover, in which plastic material, especially synthetic polymer is used for protection against corrosion and mechanical damages. As a result of the use of the plastic material a rustproof structure is attained, which at the same time protects the support for example against mechanical impacts and is less expensive than stainless steel.

Another objective is a support containing plastic material as a reinforcement in addition to steel, wherein it is possible to make the steel structures lighter.

Yet another objective is a support in which the parts of the support used for fastening may also be protected against corrosion and mechanical damages better than in prior art, and at the same time the structure is well suited for fastening because of its sufficient rigidity. As a result of the use of the plastic material, irregularities on the fastening surfaces do not cause damages which would result in rusting. By means of the combined use of plastic material and steel the parts of the support used for fastening can be better protected. At the same time the structure remains strong, as steel is not necessarily omitted entirely.

According to an embodiment, one objective is a support whose part used for fastening is made of plastic, but said part extends as a continuous element to the frame part of the support, thus making the structure strong. Another objective is a support whose plate layers are surrounded and covered with a layer of rubber which is flexible, ductile and reversible.

Brief description of the drawings

In the following description, the invention will be illustrated with reference to the appended drawings.

Fig. 1 shows a transverse section of a prior art support.

Fig. 2 shows a longitudinal section of the support according to Fig. 1.

Fig. 3 shows a side view of a support according to an embodiment of the invention.

Fig. 4 shows a top view of the support according to Fig. 3.

Fig. 5 shows a transverse section of the support according to Fig. 3.

Fig. 6 shows a longitudinal section of the support according to Fig. 3.

Detailed description of the invention

Figs 3 and 4 show a support 12 comprising an elongated frame part 13 having a rectangular horizontal, longitudinal and transverse section and shape, and whose corners are rounded, if necessary. The height, length and width of the support 12 vary and are determined on the basis of the load that has to be carried by the bearing, wherein the surface pressure determines the surface area of the upper surface 13a of the support and that how much the support must yield sideways without gliding occurring in the upper surface 13a. The heaviest load of the support in the vertical direction is approximately 2500 kN. The lateral displacement required from the support may be as wide as 100 mm and the flexibility of the support depends on the rubber material in use and the number of plate layers therein. The length of the support varies between 200 to 800 mm, the width varies between 55 to 200 mm and the height between 40 to 120 mm. The lower surfaces 14b and 15b of the fastening parts 14 and 15 function as extensions for the even lower surface 13b of the support 12. The lower surface 13b is fastened either to the hatch cover, wherein the upper surface 13a is directed downward, or the lower surface 13b is fastened to the coaming or a corresponding structure in a position shown in Fig. 3, wherein the upper surface 13a is directed upward. Two screws made of acid-proof material are typically used for the fastening, the size of the screws varying between M16 to M24.

According to an embodiment, the height (thickness) of the fastening parts 14 and 15 is approximately 1/4 or 1/5 of the entire height of the support. The fastening parts 14 and 15 extend sufficiently far from the end surfaces 13e and 13f of the frame part in the longitudinal direction so that fastening holes 16 and 17 for the fastening screw can be provided therein. The fastening holes 16 and 17 extend perpendicularly through the fastening parts 14 and 15. The head of the screw is positioned on the upper surfaces 14a and 15a, which contain a groove for the head of the screw. In the presented embodiment the fastening parts 14 and 15 have the shape of a semi-circle, or they contain two different wide roundings. The width of the fastening parts 14 and 15 corresponds substantially to the perpendicular distance of the sides 13c and 13d of the frame part from each other. According to some embodiments the length of the frame part 13 is 2 to 4 times the width of the frame part 13.

The support 12 is made of rubber and its structure is horizontally flexible, wherein the support 12 adapts to the movements of the hatch cover as shown by the broken lines, and gliding does not occur between the upper surface 13a and the surface (hatch cover or coaming) positioned against the same. Rubber is fastened to the plates by means of vulcanization, said plates being integrated inside the rubber and thus protected by means of the rubber against the effects of the ambient conditions. Preferably, the rubber layer surrounds the support 12 seamlessly from all sides, wherein the different plate layers are both coated and surrounded by the rubber layer, whose thickness in different parts of the support vary.

According to Figs 5 and 6, there are reinforcing steel plates 18 inside the support 12, said plates extending horizontally in parallel. The steel material is preferably S235. The upper part of the support 12 comprises a surface plate 19 made of plastic, which is thicker than the steel plates 18. The lower part of the support 12 comprises a bottom plate 20 made of steel, which is thicker than the plates 18, parallel to the other plates and extends beyond the other plates to the fastening parts 14 and 15 at both ends of the support 12. The steel material is preferably S235. Both fastening holes 16 and 17 extend through the bottom plate 20. Underneath the bottom plate 20 there is a bottom plate 21 made of plastic, which is thicker than the plates 18, parallel to the other plates and extends beyond the other plates to the fastening parts 14 and 15 at both ends of the support 12. Both fastening holes 16 and 17 extend through the bottom plate 20. The fastening holes 16 and 17 are positioned on the longitudinal central line X of the support 12.

In the embodiment presented in the example, the plastic surface plate 19 and the plastic bottom plate 21 are equally thick and thicker than the steel bottom plate 20.

According to an example of the invention, the plastic surface plate 19 is covered by a 22 mm thick rubber layer 22 , the thickness of the plates 18 is 2 mm and they are separated from each other and the bottom plate 20 by a 5 mm thick rubber layer 23, which, however, is slightly thicker at the location of the upper surfaces 14a and 15a. Between the upper plate 18 and the plastic surface plate 19 there is a 2 mm thick rubber layer 24. Between the lowermost plate 18 and the bottom plate 20 there is a 5 mm thick rubber layer 27, which, however, is slightly thicker at the location of the upper surfaces 14a and 15a. Between the bottom plate 20 and the plastic bottom plate 21 there is a 1 mm thick rubber layer 25. The plastic bottom plate 21 is covered by a 2 mm thick rubber layer 26, which at the same time is the surface positioned against the fastening surface. On the side surfaces 13c and 13d and on the end surfaces 13e and 13f the thickness of the rubber layer varies, being for example 4 to 12 mm.

According to another example of the invention the rubber layer 22 is missing, wherein the plastic surface layer 19 at the same time functions as a glide surface, against which the hatch or the coaming may move, if necessary. According to a third example of the invention, the rubber layer 26 is missing, possibly together with the rubber layer 22, wherein the plastic bottom plate 21 is positioned directly and in a stationary manner against its mounting. The cross-section of the plastic surface plate 19 or the plastic bottom plate 21 , preferably the cross-section of both of them in the transverse direction of the support 12 corresponds to the shape of a truncated cone so that the wide upper surface of the plastic surface plate 21 is on the side of the upper surface 13a of the support, or the wide lower surface of the plastic bottom plate 21 is on the side of the lower surface 13b of the support, and they are also wider than the plates 18. Thus, the plastic bottom plate 19 or the plastic bottom plate 21 extend laterally beyond the plates 18, thereby protecting the plates 18 and being the first to receive the impacts hitting the sides or corners of the support, for example the corner between the upper surface 13a and the side surface 13c.

The plastic bottom plate 21 protects the support 12 as well as the bottom plate 20 from below. The plastic bottom plate 21 prevents the effect of damages from extending to the bottom plate 20, and thus sea water is not capable of rusting the bottom plate 20. Damages may occur for example as a result of the fastening or due to irregularities in the mounting. The plastic bottom plate 21 and the bottom plate 20 extend to the fastening parts 14 and 15, wherein it is possible to make the fastening parts 14 and 15 sufficiently firm for fastening purposes, thus making the entire structure rigid so that the support yields substantially only in the area where the plates 18 are located.

The shape of the support reverts to the shape shown in the figures when the forces effecting in the lateral direction are terminated. The lower surface 13b remains against its mounting and the support 12 does not change its shape unnecessarily.

An embodiment of the invention does not have a bottom plate of steel 20 and the plastic bottom plate 21 , in turn, is thicker. The rubber layers 25 and 27 are thus attached together. The material at the location of the fastening holes 16 and 17 is thus entirely rustproof, wherein corrosion is not capable of propagating between rubber and steel, even though there were a damage in the rubber layer at the location of the fastening holes 16 and 17. However, the thick plastic bottom plate 21 guarantees a rigid, durable structure and ensures that the fastening parts 14 and 15 are kept fastened to the support, because the plastic bottom plate 21 extends as a uniform element to the frame part 13 and is fastened to the structures of the frame part 13 by means of vulcanization.

The plates are attached to the structure of the support 12 and to the rubber material by means of vulcanization, wherein at least all the steel parts, and in the presented example all the plastic parts as well are surrounded by rubber, wherein good protection is attained.

Hereinabove, an embodiment of the support has been presented. In other embodiments the thickness of the bottom plate 20 and the plastic bottom plate 21 varies between 10 to 15 mm, the thickness of the plates 18 varies between 1 to 3 mm, and their number between 3 to 15, and the thickness of the plastic surface plate 19 varies between 6 to 8 mm. The thicknesses of the rubber layers 23 between the plates 18 vary between 3 to 5 mm, which is the case in other rubber layers as well.

The plates 18, the surface plate 19, the bottom plate 20 and the bottom plate 21 are separated from each other by means of rubber layers 23, 24, 25 and 27. Especially the plates 18 are protected from all sides inside the rubber layer, wherein the ambient conditions are not capable of affecting them. The surface plate 19 and the bottom plate 21 have been covered with a surface layer 22 made of rubber and a bottom layer 26 made of rubber. In the frame part 13 the plates are also surrounded by rubber, wherein the ends of the frame part 13 comprise a rubber layer 31 , and there are also rubber layers 28 and 29 on the sides of the frame part 13. The plates of the fastening parts, especially the bottom plate 20, are also surrounded by rubber, wherein there is a rubber layer 31 at the ends of the fastening parts 14 and 15.

The plastic surface plate 19 and the plastic bottom plate 21 , preferably both of them, are made of plastic, i.e. polymer, according to one embodiment glass fibre reinforced polyamide, preferably PA6+ 30 GF.

The invention is not restricted solely to the embodiments presented above. In the above-presented description, the invention has been illustrated by means of some examples, but the invention can also be applied within the scope of the appended claims.

Claims

1. A flexible support for the hatch cover of a vessel, the support (12) comprising: - several parallel superimposed plate layers (18) which are fastened to each other by means of rubber layers (23); characterized in that the support also comprises: a plastic surface plate (19), which is fastened on top of said plate layers (18) by means of a rubber layer (24); and - a plastic bottom plate (21 ), which is fastened underneath said plate layers (18) by means of a rubber layer (25).

2. The support according to claim 1 , characterized in that the support further comprises - a bottom plate (20) positioned between the lowermost layer (18) and said plastic bottom plate (21) and fastened to said lowermost plate layer (18) and said plastic bottom plate (21 ) by means of rubber layers (25, 27).

3. The support according to claim 1 , characterized in that the bottom plate (21) extends beyond the plate layers at both ends of the support, wherein at the ends of the bottom plate (21 ) there are fastening holes (16, 17) for fastening the support.

4. The support according to claim 2, characterized in that the bottom plates (20, 21 ) extend beyond the plate layers (18) at both ends of the support, wherein at the ends of the bottom plates (20, 21) there are fastening holes (16, 17) for fastening the support.

5. The support according to any of the claims 1 to 4, characterized in that the plastic surface plate (19) is covered with a rubber layer (22) or the plastic bottom plate (21) is covered with a rubber layer (26), or they are both covered with rubber layers (22, 26).

6. The support according to any of the claims 1 to 5, characterized in that the plate layers (18), the plastic surface plate (19) and the plastic bottom plate (21) are surrounded by a rubber layer (28, 29, 30, 31 ).

7. The support according to any of the claims 1 to 6, characterized in that the plastic bottom plate (21 ) or the plastic surface plate (19), or both of them extend wider than the plate layers (18) at both sides of the support.

8. The support according to any of the claim 7, characterized in that the plastic bottom plate (21 ) or the plastic surface plate (19), or both of them have a cross-section of a truncated cone and they are thicker than the plate layers (18).

9. The support according to any of the claims 1 to 8, characterized in that the plastic bottom plate (21 ) or the plastic surface plate (19), or both of them are made of glass fiber reinforced polyamide.

10. The support according to claim 2 or 4, characterized in that the bottom plate (20) positioned between the lowermost plate layer (18) and said plastic bottom plate (21 ) is made of steel material.

11. The support according to any of the claims 1 to 10, characterized in that said plate layers (18) are made of steel material.

12. The support according to any of the claims 1 to 11, characterized in that the plastic bottom plate (21 ) or the plastic surface plate (19), or both of them is/are thicker than said plate layers (18).

13. The support according to any of the claims 1 to 12, characterized in that the cross-section of the plastic surface plate (19) or the plastic bottom plate (21 ), or both of them in the transverse direction of the support (12) corresponds to the shape of a truncated cone and is wider than said plate layers.

14. The support according to claims 2 or 4, characterized in that the thickness of the bottom plate (20) and the plastic bottom plate (21 ) is between 10 to 15 mm and the thickness of said plate layers (18) is between 1 to 3 mm.

15. The support according to claim 2 or 4, characterized in that the bottom plate (20) and the plastic bottom plate (21 ) are thicker than said plate layers (18).

16. A method in the manufacture of a flexible support (12) for the hatch cover of a vessel, the method comprising: fastening to each other by means of vulcanization several parallel superimposed plate layer,s (18) which are fastened to each other by means of rubber layers (23); characterized in that the method also comprises: fastening by means of vulcanization a plastic surface plate (19) on top of said plate layers (14) by means of a rubber layer (24); and fastening by means of vulcanization a plastic bottom plate (21 ) underneath said plate layers (18) by means of a rubber layer

(25).

17. The method according to claim 16, characterized in that the method also comprises: - fastening by means of vulcanization the bottom plate (20) between the lowermost plate layer (18) and said plastic bottom plate (21 ) by means of rubber layers (25, 27).

18. The method according to claim 16 or 17, characterized in that said plas- tic bottom plate (21 ) extends beyond the plate layers (18) at both ends of the support, wherein at the ends of the bottom plate (21 ) there are fastening holes (16, 17) for fastening the support.

19. The method according to any of the claims 16 to 18, characterized in that the method also comprises: covering the plastic surface plate (19) with a rubber layer (22) or the plastic bottom plate (21) with a rubber layer (26), or covering both of them with rubber layers (22, 26).

20. The method according to any of the claims 16 to 19, characterized in that the method also comprises: surrounding the plate layers (18), the plastic surface plate (19) and the plastic bottom plate (21 ) by rubber layers (28, 29, 30, 31).