EP0594226A2

EP0594226A2 - Marine container roof structure with heat insulation

Info

Publication number: EP0594226A2
Application number: EP93121120A
Authority: EP
Inventors: Hiroshi Hirose; Michinobu Uchikoshi
Original assignee: Nippon Fruehauf Co Ltd
Current assignee: Nippon Fruehauf Co Ltd
Priority date: 1989-09-14
Filing date: 1990-09-13
Publication date: 1994-04-27
Also published as: DE69010602T2; DE69010602D1; EP0594226A3; EP0419138B1; EP0419138A1; KR910006115A; MY106457A

Abstract

A heat-insulated marine container has an elongate hexahedral shape and includes a roof, a floor confronting the roof, and corner members positioned at four corners of each of the roof and the floor. The marine container has a roof structure which comprises a roof and an inner lining panel which are bonded to the opposite surfaces of a heat insulation sandwiched therebetween. The roof and the inner lining panel have a plurality of stress-absorbing corrugations which extend inwardly into the heat insulation material. The corrugations extend transversely of the marine container, and may have various cross-sectional shapes.

Description

The present invention relates to a marine container roof structure with a heat insulation, and more particularly to a marine container roof structure with a heat insulation, which structure is protected from damage during usage.
Containers are in the form of simple transportation boxes whose outside surfaces are covered with metal panels, and widely used in many transport applications such as ship, railroad, and automobile transport systems.
Among various containers are large-size marine containers used mainly for sea transport. One known marine container disclosed in U.S. Patent No. 3,206,902 comprises a floor, a roof, and side walls each comprising a heat-insulated structural body which is composed of a heat insulation sandwiched between two metal panels. The roof structure of a marine container with a heat insulation will be described below with reference to the accompanying drawings.
Fig. 11 of the accompanying drawings shows in fragmentary cross section a roof of a marine container which is in the form of a long rectangular parallelepiped (see Fig. 10) or a hexahedral shape, the view being taken along a longitudinal plane extending from the roof to the confronting floor of the container. As shown in Fig. 11, the roof of the marine container has a flat roof panel 2 and a flat inner lining panel 3 which are disposed upwardly and downwardly of transverse beams 1 spaced at intervals in the longitudinal direction of the container. The space between the roof panel 2 and the inner lining panel 3 is filled with a heat insulation 4. The container also includes side panels 11 extending downwardly from the side edges of the roof.
The marine container, with cargo stored therein, is loaded from ground onto a ship or unloaded from a ship onto ground, by a container crane.
As shown in Figs. 10 and 11, the marine container has corner members 5 on its corners which will be hooked for loading and unloading. More specifically, as shown in Fig. 10, fastening hooks 7 of a spreader 6 of a container crane are held in engagement with the respective corner members 5, and the marine container is lifted or lowered by the container crane through the spreader 6. When the marine container is suspended by the container crane, the container is largely flexed by a vertical interval 6 at its centre due to the weight of the cargo stored in the container as illustrated in Fig. 12. Therefore, the roof panel 2 of the marine container is subjected to a compressive load while the container is being suspended. Since the marine container is repeatedly used over a long period of time, thereof panel 2 undergoes repeated compressive loads when the container is loaded and unloaded, and hence will have localized metal fatigue regions or localized deformed regions. The localized metal fatigue regions produce cracks in the roof panel 2, or the localized deformed regions force the roof panel 2 to be peeled off the heat insulation 4 or rupture the heat insulation 4. The cracks in the roof panel 2 allow rainwater to enter into the container roof, and the peeling or rupture of the heat insulation 4 reduces the heat insulation capability thereof.
In view of the aforesaid problems of the conventional heat-insulated marine container roof structure, it is an object of the present invention to provide a marine container roof structure with a heat insulation, which structure is capable of absorbing localized load irregularities or deviations which are caused in the roof when the container is loaded or unloaded.
According to the present invention, there is provided a roof structure for a heat-insulated marine container having an elongate hexahedral shape and including a roof, a floor confronting the roof, and corner members positioned at four corners of each of the roof and the floor, the roof structure comprising a heat insulation, a roof panel attached to a face of the heat insulation, an inner lining panel attached to a back of the heat insulation, and a plurality of stress-absorbing corrugations disposed on at least the roof panel. The stress-absorbing corrugations may be disposed on both the roof panel and the inner lining panel. The corrugations comprise grooves concaved inwardly into the roof. The corrugations may have a triangular cross section, a semicircular cross section, or a trapezoidal cross section.
The corrugations may extend transversely of the marine container. The corrugations may be spaced at pitches which are smaller in a region of the roof where produced stresses are larger.
The above and other objects, features and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings, in which:

Fig. 1 is a plan view of a marine container roof structure according to a first embodiment of the present invention;
Fig. 2 is an enlarged cross-sectional view taken along line II - II of Fig. l;
Fig. 3 is an enlarged cross-sectional view taken along line III - III of Fig. l;
Figs. 4(a) and 4(b) are plan views of a marine container roof structure according to a second embodiment of the present invention;
Fig. 5 is an enlarged cross-sectional view taken along line v - V of Fig. 4(a);
Fig. 6 is a fragmentary perspective view of a marine container roof structure according to a third embodiment;
Fig. 7 is a perspective view of a marine container with a roof structure according to a fourth embodiment of the present invention;
Fig. 8 is an enlarged cross-sectional view taken along line XI - XI of Fig. 7;
Fig. 9 is an enlarged cross-sectional view taken along line XII - XII of Fig. 7;
Fig. 10 is a perspective view of a marine container and spreader for suspending the marine container;
Fig. 11 is a fragmentary vertical cross-sectional view of a conventional marine container; and
Fig. 12 is a side elevational view showing the manner in which a roof panel of a marine container is flexed when the container is suspended.

Figs. 1 through 3 show a marine container roof structure according to a first embodiment of the present invention. As shown in Fig. 2, the roof of a marine container is of a laminated construction comprising a roof panel 2, an inner lining panel 3, and a heat insulation 4 sandwiched between the roof panel 2 and the inner lining panel 3. The roof panel 2 is bonded to the upper surface of the heat insulation 4 and the inner lining panel 3 is bonded to the lower surface of the heat insulation 4. The roof panel 2 has transverse grooves 8 concaving inwardly into the roof and spaced at constant intervals in the longitudinal direction of the roof, as shown in greater detail in Fig. 2. As shown in Fig. 1, each of the transverse grooves 8 terminates short of the lateral edges of the roof panel 2, leaving an attachment margin to which an upper side frame 9 (Fig. 3) of the marine container is fastened.
According to a second embodiment of the present invention, each groove 8 extends the fully transverse width of the marine container as shown in Fig. 4(a), or each groove 8 is interrupted in the transverse direction of the marine container as shown in Fig. 4(b).
In the first embodiment shown in Fig. 1, since the transverse grooves 8 do not extend fully to the lateral edges of the roof panel 2, each lateral edge of the roof panel 2 can easily be fastened to the upper edge of the upper side frame 9 by rivets 10 as shown in Fig. 3. In the second embodiment shown in Figs. 4(a) and 4(b), however, each transverse groove 8 extends fully to the lateral edges of the roof panel 2. Therefore, as shown in Fig. 5, the roof panel 2 is fastened to the upper edge of the upper side frame 9 by rivets 10 fixed to those portions of the lateral edges of the roof panel 2 which are free of the transverse ridges 8. In Fig. 5, each lateral edge 2' of the roof panel 2 is bent downwardly around and over the side edge of the upper side frame 9, thereby preventing rainwater and seawater from entering the marine container from between the roof panel 2 and the upper side frame 9.
While the roof panel 2 has transverse corrugations or grooves 8 in the above arrangement, the inner lining panel 3 also has similar grooves.
The interval δ (Fig. 12) by which the marine container is flexed when it is suspended is maximum at the centre of the marine container. Therefore, the transverse grooves 8 may be positioned at spaced intervals or pitches that are progressively greater in longitudinal directions from the centre of the container toward the front and rear ends thereof.
Since the transverse grooves 8 are provided on at least the roof panel 2 at longitudinally spaced intervals, irregular compressive loads applied to the roof which are produced when the marine container is suspended can be absorbed by the transverse grooves 8. The transverse grooves 8 are also effective to absorb thermal strains in the roof. Therefore, any damage to the roof of the marine container due to compressive load irregularities and thermal strains can be reduced, and the service life of the marine container is extended.
Fig. 6 shows a modification of the marine container roof structure according to a third embodiment. As shown in Fig. 6, a roof panel 2 has two pairs of transverse grooves 80' respectively at lateral sides thereof and a single transverse groove 80' at the centre. An inner lining panel 3 also has similar transverse grooves 80'. These transverse grooves 80' in the roof panel 2 and the inner lining panel 3 are also effective in stiffening the upper and lower surfaces of the roof and hence increasing the service life of the marine container.
A marine container roof structure according to a fourth embodiment of the present invention will be described below with reference to Figs. 7 through 9.
As shown in Fig. 7, a roof panel 2 bonded to the upper surface of a heat insulation 4 has a plurality of transverse grooves 12 concaved inwardly into the roof and spaced at intervals in the longitudinal direction of the roof panel 2. The transverse grooves 12 extend the full transverse width of the roof panel 2. Alternatively, the transverse grooves 12 may terminate short of lateral edges of the roof panel 2, leaving attachment margins which are fastened to upper side frames 9. Each of the transverse grooves 12 is shown being continuous, but may be interrupted in the transverse direction of the roof panel 2.
As described above, the transverse grooves 12 extend fully to the lateral edges of the roof panel 12, as shown in Fig. 7. To attach the roof panel 12 to the upper side frames 9, the lateral sides of the roof panel 12 are first pressed to flat shape, and then the flat lateral sides are fastened to the upper side frames 9. As shown in Fig. 8. each of the lateral edges of the roof panel 2 is bent downwardly over and around a flange 9a of the upper side frame 9, thereby preventing rainwater and seawater from entering the marine container from between the roof panel 2 and the upper side frame 9.
While the roof panel 2 has transverse grooves 12 in the above arrangement, an inner lining panel 3 bonded to the lower surface of the heat insulation 4 may also have similar transverse grooves 12, as shown in Fig. 9, which appear as grooves that are upwardly concave when viewed from within the container.
The roof structure with the transverse grooves 12 will be described below in greater detail. The transverse grooves 12 are pressed into triangular cross section at predetermined intervals or pitches as shown in Fig. 9. To attach the roof panel 2 to the upper side frames 9, the lateral sides of the roof panel 2 are pressed into flat attachment margins, which are then bent over and fastened to the flanges 9a of the upper side frames 9. As shown in Fig. 9, the heat-insulated roof structure also includes a plurality of transverse beams 1 positioned between the roof panel 2 and the inner lining panel 3 and spaced at intervals (e.g. about 600 mm) in the longitudinal direction of the marine container. The transverse grooves 12 in the roof panel 2 and the inner lining panel 3 are positioned off the beams 1.
Compressive loads which are produced in the roof when the marine container is suspended are absorbed by the transverse grooves 12, so that the roof panel 2 or the inner lining panel 3 is prevented from being buckled.
The interval δ (Fig. 12) by which the marine container is flexed when it is suspended is maximum at the centre of the marine container. Therefore, the transverse grooves 12 may be positioned at spaced intervals or pitches that are progressively greater in longitudinal directions from the centre of the container toward the front and rear ends thereof.
Because the transverse grooves 12 are provided on at least the roof panel 2 at longitudinally spaced intervals, irregular compressive loads applied to the roof which are produced when the marine container is suspended can be absorbed by the transverse grooves 12. Consequently, the roof panel 2 or the inner lining panel 3 is prevented from being locally buckled.
The grooves 12 in the roof panel 2 increase the surface area with which the roof panel 2 is bonded to the heat insulation 4. Therefore, the roof panel 2 and the heat insulation 4 are strongly bonded to each other and prevented from being peeled off each other.

Claims

A roof structure for a heat-insulated marine container having an elongate hexahedral shape and including a roof (2), a floor confronting the roof, and corner members (5) positioned at four corners of each of the roof and the floor, the roof structure comprising a heat insulation (4), a roof panel (2) attached to a face of the heat insulation, an inner lining panel (3) attached to a back of the heat insulation, and a plurality of stress-absorbing corrugations (80') disposed on at least the roof panel; characterised in that the stress-absorbing corrugations are outwardly facing grooves (8,80') which extend transversely of the container, and are disposed on both the roof panel and the inner lining panel.
A roof structure according to claim 1, wherein the grooves (8,80') have a triangular cross section.
A roof structure according to claim 1, wherein the grooves (8,80') have a semicircular cross section.
A roof structure according to claim 1, wherein the grooves (8,80') have a trapezoidal cross section.
A roof structure according to any one of the preceding claims, wherein the grooves are spaced at pitches which are smaller in a region of the roof where produced stresses are larger.