MULTI-LAYER HATCH COVER SUPPORT PAD

Abstract

The invention provides a multi-layer hatch cover support pad for supporting a hatch cover on a coaming structure of a ship. The multi-layer hatch cover support pad comprises an outer wear surface for sliding against a mating surface provided on the hatch cover or the coaming structure, a wear layer comprising first and second opposite sides, the first side defining the outer wear surface, the wear layer comprising a first plastic material, and, a base layer comprising third and fourth opposite sides, the third side being joined to the second side. The base layer comprises a second polymer material which is less abrasion resistant than the first plastic material. By making the base layer, which in practice makes up the main part of the multi-layer hatch cover support pad, out of the second polymer material, the cost of the multi-layer hatch cover support pad is decreased. The multi-layer hatch cover support pad may further comprise an internal wear indicator body for indicating wear of the wear layer and/or an identification unit for identifying the multi-layer hatch cover support pad. A method of producing the multi-layer hatch cover support pad, as well as a use of the multi-layer hatch cover support pad, is also provided.

Claims

14. A multi-layer hatch cover support pad for supporting a hatch cover on a coaming structure of a ship, said multi-layer hatch cover support pad comprising an outer wear surface for sliding against a mating surface provided on said hatch cover or said coaming structure, a wear layer comprising first and second opposite sides, said first side defining said outer wear surface, said wear layer comprising a first plastic material, and, a base layer comprising third and fourth opposite sides, said third side being joined to said second side, said base layer comprising a second polymer material, said second polymer material being less abrasion resistant than said first plastic material, said second side being joined, through moulding, to said third side.

15. The multi-layer hatch cover support pad according to claim 14, the abrasion resistance of said first plastic material and said second polymer material being determined by measuring loss of material from geometrically identical bodies of said first plastic material and said second polymer material slid equal distances against said mating surface when subjected to equal contact forces.

16. The multi-layer hatch cover support pad according to claim 14, said multi-layer hatch cover support pad being moulded.

17. The multi-layer hatch cover support pad according to claim 14, said multi-layer hatch cover support pad further comprising a deformable bottom layer comprising fifth and sixth opposite sides, said fifth side being attached to said fourth side, said deformable bottom layer comprising a material having lower compressive strength than said second polymer material.

18. The multi-layer hatch cover support pad according to claim 14, said base layer on said third side comprising attachment structures for enhancing the strength of the joining of said wear layer to said base layer.

19. The multi-layer hatch cover support pad according to claim 14 further comprising at least one wear indicator body, said wear indicator body being made from a material different from said first plastic material , said wear indicator body being included, such as by moulding, in said wear layer at a first distance from said wear surface.

20. The multi-layer hatch cover support pad according to claim 14 further comprising an identification unit comprising identification information for uniquely identifying said multi-layer hatch cover support pad.

21. The multi-layer hatch cover support pad according to claim 20, said identification unit being provided within the multi-layer hatch cover support pad, preferably at a second distance from said wear surface.

22. The multi-layer hatch covers support pad according to claim 21, said identification unit being configured for wireless reading of said identification information, by for example comprising a RFID tag.

23. The multi-layer hatch cover support pad according to claim 20, said identification unit being provided on an exterior surface of the multi-layer hatch cover support pad, said identification unit preferably comprising a barcode.

24. The multi-layer hatch cover support pad according to claim 14, said second polymer material comprising a plastic material.

25. A method of producing a multi-layer hatch cover support pad for supporting a hatch cover on a coaming structure of a ship according to claim 14, the method comprising the steps of: moulding a second polymer material, such as a plastic material, into a base layer having opposite third and fourth sides, moulding a first plastic material onto said third side to form a wear layer having first and second opposite sides, said first side defining a wear surface and said second side being joined, through moulding, to said third side, said second polymer material, in solid form, being less abrasion resistant than said first plastic material in solid form.

26. Use of a multi-layer hatch cover support pad according to claim 14 for supporting a hatch cover on a coaming structure of a ship.

27. The multi-layer hatch cover support pad according to claim 15, said multi-layer hatch cover support pad being moulded.

28. The multi-layer hatch cover support pad according to claim 15, said multi-layer hatch cover support pad further comprising a deformable bottom layer comprising fifth and sixth opposite sides, said fifth side being attached to said fourth side, said deformable bottom layer comprising a material having lower compressive strength than said second polymer material.

29. The multi-layer hatch cover support pad according to claim 16, said multi-layer hatch cover support pad further comprising a deformable bottom layer comprising fifth and sixth opposite sides, said fifth side being attached to said fourth side, said deformable bottom layer comprising a material having lower compressive strength than said second polymer material.

30. The multi-layer hatch cover support pad according to claim 15, said base layer on said third side comprising attachment structures for enhancing the strength of the joining of said wear layer to said base layer.

31. The multi-layer hatch cover support pad according to claim 16, said base layer on said third side comprising attachment structures for enhancing the strength of the joining of said wear layer to said base layer.

32. The multi-layer hatch cover support pad according to claim 17, said base layer on said third side comprising attachment structures for enhancing the strength of the joining of said wear layer to said base layer.

33. The multi-layer hatch cover support pad according to claim 15 further comprising at least one wear indicator body, said wear indicator body being made from a material different from said first plastic material, said wear indicator body being included, such as by moulding, in said wear layer at a first distance from said wear surface.

Description

[0082] The invention and its many advantages will be described in more detail below with reference to the accompanying schematic drawings, which for the purpose of illustration show some non-limiting embodiments, in which:

[0083] FIG. 1 shows, in perspective view, a conventional cargo ship with hatch covers and containers stacked on top of the hatch covers, the hatch covers being supported by conventional hatch cover support pads,

[0084] FIG. 2 shows, in perspective view, a conventional hatch cover support assembly comprising a hatch cover support pad holder for holding two conventional hatch cover support pads.

[0085] FIG. 3A shows a first cross section of a first embodiment of a hatch cover support pad according to the first aspect of the present invention,

[0086] FIG. 3B shows a second cross section of the first embodiment of the hatch cover support pad according to the first aspect of the present invention,

[0087] FIG. 3C shows a third cross section of the first embodiment of the hatch cover support pad according to the first aspect of the present invention, the third cross section corresponding to the appearance of the hatch cover support pad once the wear layer has been worn down to expose the wear indicators.

[0088] FIG. 4 shows a first cross section of a second embodiment of the hatch cover support pad according to the first aspect of the present invention, the second embodiment additionally comprising a deformable bottom layer and an interface layer,

[0089] FIG. 5A shows a first cross section of a third embodiment of the hatch cover support pad according to the first aspect of the present invention, the third embodiment additionally comprising an identification chip,

[0090] FIG. 5B shows, in perspective view, a fourth embodiment of the hatch cover support pad according to the first aspect of the present invention, the fourth embodiment additionally comprising a barcode on its exterior, and

[0091] FIG. 6 shows, in perspective view, a locking screw for securing a hatch cover support pad in a hatch cover support pad holder.

[0092] In the below description, one or more signs added to a reference number indicates that the element referred to has the same or similar function as the element designated the non-modified reference number, however, differing in structure.

[0093] In the below description, where suitable for discussing a plurality of identical elements, a subscript Arabic numeral added to a reference number indicates that the element referred to is a further one of the element designated the non-subscripted reference number.

[0094] When further embodiments of the invention are shown in the figures, the elements which are new, in relation to earlier shown embodiments, have new reference numbers, while elements previously shown are referenced as stated above. Elements which are identical in the different embodiments have been given the same reference numerals and no further explanations of these elements will be given.

[0095] FIG. 1 shows, in perspective view, a conventional cargo ship 2 comprising a hull 4 having a deck 6. In the deck are formed hatch openings through which the ship's cargo holds may be accessed. The hatch openings are closed by hatch covers, one of which is designated the reference numeral 8 which are placed on the coaming structures, one of which is designated the reference numeral 10, which border the hatch openings in the hull 4. Containers, one of which is designated the reference numeral 12 are loaded in the cargo holds below the hatch covers (not shown) and also stacked on top of the hatch covers. The containers 12 are fastened to the hatch covers and lashed together as is known in the art of cargo shipping.

[0096] As the cargo ship 2 sails it will pitch and roll due to the seaway. This causes flexing of the hull 4 with the result that the coaming structure 10 moves in relation to the hatch cover 8. For the cargo ship 2 shown in fig. 1 this movement is conventionally accommodated by supporting the hatch cover 8 using a steel mating surface 14 provided on the coaming structure 10 and by providing a hatch cover support pad 16 in a hatch cover support pad holder 18 which is fastened to the hatch cover 8. As the hull 4 flexes the hatch cover support pad 16 slides back and forth over the steel mating surface 14 while transferring the weight of the hatch cover 8 with the containers 12 to the coaming structure 10.

[0097] FIG. 2 shows, in perspective view, a conventional hatch cover support assembly in its entirety designated the reference numeral 20. The hatch cover support assembly 20 comprises a hatch cover support pad holder 22 provided with two pad receiving cavities, one of which is designated the reference numeral 24. Holes, one of which is designated the reference numeral 26, are provided in the walls of the hatch cover support pad holder 22 between the exterior of the hatch cover support pad holder 22 and the interior of the pad receiving cavities 24 for receiving a rod-shaped locking pin 28. In the pad receiving cavity 24 is first placed an elastic support piece 30 followed by a metal shim plate 32 before a conventional plastic hatch cover support pad 40 is installed. The conventional plastic hatch cover support pad 40 comprises a through-going hole or bore 42, which, when the plastic hatch covers support pad 40 is installed in the pad receiving cavity 24, lines up with the hole 26 in the hatch cover support pad holder 22 for receiving the locking pin 28 for retaining the plastic hatch cover support pad 40. The conventional plastic hatch cover support pad 40 further comprises on its wear surface, i.e. the upper surface of the conventional plastic hatch cover support pad 40, first and second sets of three wear indicating grooves 44 and 46, each of the three grooves having different depths to facilitate measuring the wear on the conventional plastic hatch cover support pad 40.

[0098] As stated above the conventional plastic hatch cover support pad 40 is expensive as the plastic material used is expensive due to the high demands on abrasion resistance for the plastic material used. Further it is difficult to detect wear using the set of grooves 44 and 46 because as plastic material is worn off the wear surface, the worn off material may accumulate in the grooves,

[0099] FIG. 3A shows a first cross section of a first embodiment of a multi-layer hatch cover support pad SO according to the first aspect of the present invention. The multi-layer hatch cover support pad 50 may be used instead of the conventional plastic hatch cover support pad 40 in the conventional hatch cover support assembly 20.

[0100] The multi-layer hatch cover support pad 50 comprises two layers, a wear layer 52 having a first side defining a wear surface 54 for sliding over the steel mating surface 14 and an opposite second side 56, and a base layer 58 having third and fourth sides 60 and 62 for supporting the wear layer 52. The wear layer 52 is made from a first plastic material, in this case a self-lubricating, highly abrasion resistant and low friction plastic material while the base layer is made from a second polymer material which is less abrasion resistant than the first plastic material and which is more economical than the first plastic material. Thus the multi-layer hatch cover support pad 50 is more economical as it uses less of the expensive first plastic material than the conventional plastic hatch cover support pad 40.

[0101] The third side 60 of the base layer 58 is joined to second side 56 of the wear layer 52 while the opposite fourth side 62 in use contacts the metal shim plate 32.

[0102] The multi-layer hatch cover support pad 50 may, as shown in FIGS. 3A and 3B comprise blind holes, one of which is designated the reference numeral 64, open to the fourth side 62 and being provided in the base layer 58 for reducing the weight of the multi-layer hatch cover support pad 50.

[0103] The multi-layer hatch cover support pad 50 further comprises the through-going hole 42 of the conventional plastic hatch cover support pad 20.

[0104] To increase the strength of the adhesion between the wear layer 52 and the base layer 58 the third side 60 of the base layer 58 comprises mushroom shaped engagement units, one of which is designated the reference numeral 66, each of which comprises a stem 68 extending from the third side 60 and being terminated in an engaging head 70 extending beyond the diameter of the stem 68 to define an undercut 72. The engaging head 70 with the undercut 72 serve to anchor the wear layer 52 to the base layer 58 as part of the first plastic material of the wear layer 52, during moulding of the wear layer 52 to the base layer 58, becomes trapped by the undercut 72 beneath the engaging head 70. Figure 3A also shows alternative engagement units 66 and 66.

[0105] The multi-layer hatch cover support pad 50 may, as shown in figs. 3A and 3B, comprise the first and second sets of three wear indicating grooves 44 and 46, however the wear indicating grooves 44 and 46 are not essential to the multi-layer hatch cover support pad 50.

[0106] As described above it may be difficult to properly detect the wear of the wear surface 54 using the sets of three grooves 44 and 46.

[0107] Therefore the hatch cover support pad 50 further, or instead, comprises a plurality of internal wear indicator bodies, one of which is designated the reference numeral 80. The wear indicator body 80 comprises a body of a material which is different from the first plastic material, such as having a colour or texture which is different from the colour or texture of the wear layer 52. As the wear indicator body is placed within the multi-layer hatch cover support pad 50 a first distance, such as 3-5 mm, from the wear surface 54 of an unworn multi-layer hatch cover support pad 50, wear on the wear surface 54 will eventually result in the wear indicator body becoming visible as can be seen in FIG. 3C. This clearly indicates that the multi-layer hatch cover support pad 50 is worn out and needs to be replaced.

[0108] In contrast to the sets of three grooves 44 and 46 the wear indicator body 80 is less likely to be fouled by the worn off plastic material.

[0109] As shown in figure 3A the wear indicator body 80 may preferably be attached to the mushroom shaped engagement units 66, however the wear indicators 80 may alternatively be integral with the base layer 58 and extend from the third side 60. In particular the wear indicator body 80 may be formed integral with the mushroom shaped engagement units 66, as a body extending from the mushroom shaped engagement units 66.

[0110] FIG. 3B shows a second cross section of the first embodiment of the multi-layer hatch cover support pad 50 according to the first aspect of the present invention,

[0111] FIG. 3C shows a third cross section of the first embodiment of the multi-layer hatch cover support pad 50 according to the first aspect of the present invention, the third cross section corresponding to the appearance of the multi-layer hatch cover support pad once the wear layer 52 has been worn down enough, typically 3-5 mm and depending on the first distance, to expose the wear indicator body 80. Preferably, as shown in FIG. 3C, several wear indicator bodies 80 are positioned In a cross formation with one wear indicator body 80 at each end of the multi-layer hatch cover support pad 50 and one wear indicator body 80 on each side of the longitudinal axis of the multi-layer hatch cover support pad 50.

[0112] Additional wear indicators 80 may be added to the multi-layer hatch cover support pad 50 in order to determine wear in other locations of the wear layer 52 and the wear surface 54. Further, wear indicator bodies 80 being positioned or adapted at different first distances to the wear surface 54 of an unworn multi-layer hatch cover support pad 50, may be used resulting in that different wear indicator bodies 80 become visible sequentially or gradually as the wear layer 52 is worn off, thereby indicating how much of the wear layer 52 has been worn off.

[0113] The wear indicator body 80 may also be used in the conventional plastic hatch cover support pad 40.

[0114] In operation the multi-layer hatch cover support pad 50 is used with the hatch cover support assembly 20 by being placed in the pad receiving cavity 24 of the hatch cover support pad holder 22. The height of the multi-layer hatch cover support pad 50 is adjusted by placing one or more metal shim plates 32 in the pad receiving cavity 24 below the multi-layer hatch cover support pad 50. Further an elastic support piece 30 may also be placed in the pad receiving cavity 24.

[0115] FIG. 4 shows a first cross section of a second embodiment of the multi-layer hatch cover support pad 50 according to the first aspect of the present invention, the second embodiment in addition to the first embodiment, comprising a deformable layer bottom 90 and a steel interface layer 100. The deformable bottom layer 90 is attached to the base layer 58 by moulding and, as it is made of a material with less compressive strength than the second polymer material, ensures that the multi-layer hatch cover support pad 50 will be levelled evenly against the mating surface 14 in case the multi-layer hatch cover support pad 50 is not evenly pressed against the mating surface 14 due to unevenness in the coaming structure 10 or the hatch cover 8.

[0116] The steel interface layer 100 serves the purpose of ensuring an equal transfer of weight from the hatch cover onto the elastic layer 90 despite the presence of the blind holes 64 on the second side 62 of the base layer 58.

[0117] When the hatch cover support pad 50 is used with the hatch cover support pad holder 22 there is no need for the elastic support piece 30, however one or more metal shim plates 32 may still be needed to ensure the correct height of the hatch cover support pad 50.

[0118] Although shown in fig. 4, the steel interface layer 100 is not essential and may be dispensed with, resulting in a multi-layer hatch cover support pad comprising only the deformable bottom layer 90, the base layer 58 and the wear layer 52. In this case preferably the base layer 58 does not comprise the blind holes 64 but is rather instead formed as a massive piece. Alternatively the material of the deformable bottom layer 90 may occupy also the blind holes 64. In either case the whole multi-layer hatch cover support pad 50 becomes a single massive piece.

[0119] FIG. 5A shows a first cross section of a third embodiment of the multi-layer hatch cover support pad 50 according to the first aspect of the present invention, the third embodiment, in addition to the first embodiment, comprising an identification chip 110 representing an identification unit. The identification chip 110 is as shown in FIG. 5A moulded into the wear layer 52 at a second distance from the wear surface 54 such as a position below the upper ends of the wear indicators 80, i.e. further away from the wear surface 54 of the non-worn multi-layer hatch cover support pad 50 than the wear indicator body 80. However, the identification chip 110 may alternatively be moulded into the base layer 58 or be positioned at the interface between the wear layer 52 and the base layer 58.

[0120] The identification chip 110 comprises a RFID chip comprising a memory storing a unique identification code for the multi-layer hatch cover support pad 50 and an antenna for sending the unique identification code to a reader. The RFID chip may comprise a battery for powering the RFID chip and sending the unique identification code, or alternatively the RFID chip may comprise an antenna for receiving power from the reader.

[0121] The purpose of the identification chip 110 is to allow an operator of the cargo ship 2 to properly identify the multi-layer hatch cover support pad 50 so that the wear of each multi-layer hatch cover support pad 50, as determined using the set of three grooves 44 and 46 or using the wear indicators 80, can be correctly allocated to that specific multi-layer hatch cover support pad 50 out of the typically hundreds of multi-layer hatch cover support pads 50 that may be used on the cargo ship 2. This provides for securely keeping track of the wear of each and every hatch cover support pad 50 on the cargo ship 2 so that the multi-layer hatch cover support pad 50 may be exchanged when worn out and for allowing the identification of any structural anomalies of the hatch cover 8 or coaming structure 10 that may lead to un-equal wear of the multi-layer hatch cover support pads 50.

[0122] The position of the identification chip 110 shown in FIG. 5A, i.e. at a the second distance which is further away from the wear surface 54 of the non-worn multi-layer hatch cover support pad 50 than the wear indicator body 80, however still within the wear layer 52, has the advantage that the identification chip 110 may be used to indicate wear of the wear layer 52. As an unworn multi-layer hatch cover support pad 50 is exposed to wear the thickness of the first plastic material between the identification chip 110 and the wear surface 54 decreases, however the multi-layer hatch cover support pad 50 can still be identified with the reader. Once the wear layer 52 has been worn off, so much that the identification chip 110 is exposed, the friction and pressure between the multi-layer hatch cover support pad 50 and the mating surface 14 will destroy or render inoperable the identification chip 110, thus resulting in that the multi-layer hatch cover support pad 50 can no longer be identified with the reader which clearly indicates that the hatch cover support pad 50 must be exchanged.

[0123] FIG. 5B shows, in perspective view, a fourth embodiment of the multi-layer hatch cover support pad 50 according to the first aspect of the present invention , the fourth embodiment, in addition to the first embodiment, comprising a barcode 110, representing an identification unit, on its exterior. The barcode 110, which is simpler and more economical than the identification chip 110, serves the same purpose as the latter of identifying the multi-layer hatch cover support pad 50and therefore comprises an unique identification code. By reading the barcode with a suitable barcode scanner the multi-layer hatch cover support pad 50 may be properly identified and wear of the multi-layer hatch cover support pad 50, as determined using the set of grooves 44 and 46 or using the wear indicator body 80, can be correctly allocated to that specific multi-layer hatch cover support pad 50 and used as described above.

[0124] If desired the hatch cover support pad 50 may be provided with both an identification chip 110 within the hatch cover support pad 50 and a barcode 110 on the exterior of the hatch covers support pad 50.

[0125] Further the identification chip 110 and/or the barcode 110 may be used on the conventional plastic hatch cover support pad 40.

[0126] FIG. 6 shows, in perspective view, a locking screw 150 for securing the hatch cover support pad 40, 50, 50, 50 or 50 in the hatch cover support pad holder 22. The locking screw 150 comprises an elongated body 152 having a point 154 and an opposite head 158, the head 158 defining a tool receiving recess 160 comprising a torx screw drive for allowing the locking screw 150 to be tightened. The locking screw 150 further comprises, on its middle section between the point 154 and the head 158 a screw thread 162. The screw thread 162 is non-continuous as it is divided into screw thread segments 164 by a lengthwise groove 164, such as a flute, extending along and curving around the middle section of the elongated body 152.

[0127] In contrast to the locking pin 28 shown in FIG. 2 the locking screw 150 provides a more secure fastening as it is screwed into the hatch cover support pad 40, 50, 50, 50 or 50. Further, as the locking screw 150 is screwed into the hatch cover support pad 40, 50, 50, 50 or 50 material is cut from the inner walls of the through-going hole 42 as each screw thread segment 164 in the area of the groove 164 engages the inner wall. As the groove curves around the elongated body 152 it is ensured that each screw segment 164 cut material from the inner wall of the through-going hole 42.

[0128] The cut material then accumulates in the groove 164 and its presence in the grove 164 increases the force necessary to unscrew the locking screw 150, thereby increasing the security of the fastening of the hatch cover support pad 40, 50, 50, 50 and 50.

LIST OF PARTS WITH REFERENCE TO THE FIGURES

[0129] 2. Cargo ship

[0130] 4. Hull

[0131] 6. Deck

[0132] 8. cover

[0133] 10. Coaming structure

[0134] 12. Container

[0135] 14. Steel mating surface

[0136] 16. Hatch cover support pad

[0137] 16. Hatch cover support pad holder

[0138] 20. Conventional hatch cover support assembly

[0139] 22. Hatch cover support pad holder

[0140] 24. Pad receiving cavity

[0141] 26. Hole

[0142] 28. Locking pin

[0143] 30. Elastic support piece

[0144] 32. Metal shim plate

[0145] 40. Conventional plastic hatch cover support pad

[0146] 42. Through-going hole

[0147] 44. First set of three wear indicating grooves

[0148] 46. Second set of three wear indicating grooves

[0149] 50. Multi-layer hatch cover support pad

[0150] 58. Wear layer

[0151] 54. Wear surface

[0152] 56. Second side

[0153] 58. Base layer

[0154] 60. Third side

[0155] 62. Fourth side

[0156] 64. Blind hole

[0157] 64. Mushroom shaped engagement units

[0158] 68. Stem

[0159] 70. Engaging head

[0160] 72. Undercut

[0161] 80. Wear indicator body

[0162] 90. Deformable bottom layer

[0163] 100. Steel interface layer

[0164] 110. Identification chip

[0165] 150. Locking screw

[0166] 152. Elongated body

[0167] 154. Point

[0168] 158. Head

[0169] 160. Tool receiving recess

[0170] 162. Screw thread

[0171] 164. Screw thread segment

[0172] 164. Groove