Anchor for heavy loads

Abstract: Anchor having two fluke parts (5, 6) each with a sharp tip (7, 8) and each with a substantially triangular cross section the basis of which is a common flat plate (2), said anchor having a double shank (18, 19) the two arms (18, 19) of which extend from the interconnected front ends (20, 21) towards the top ridges (22, 23) of the respective fluke parts with connecting points (15, 16) between one third and two thirds of each ridge as well as between two thirds and the rear end respectively of said ridges (22, 23), each arm having a rear part (24, 25) parallel to the vertical plane of symmetry and front parts (26, 27) at a mutual sharp angle.

Description: Description of the prior art . The present invention relates to an anchor with a double shank and a fluke with two fluke parts each with a forwardly pointed tip on either side of the central plane of symmetry of fluke and shank, which two fluke parts form an integral unit at the said central plane with their front edges tapering towards the respective tips and from each tip extend rearwardly with a cross section between bottom and top which is substantially triangular with the apex of each triangular cross section on a ridge line which extends parallel to the said central plane from tip to the rear end at a sharp angle with the bottom which bottom and top of the fluke parts form a box-like structure, whereas the shank has two arms which at a predetermined sharp angle extend towards the fluke from a common point of connection of the shank arms towards said ridges respectively, each shank part having a pivotable point of connection with the said ridge and a spaced apart other point of connection. An anchor of this type is known from US-A-4,781,142. Said known anchor has a fluke with two fluke parts each of which in a transverse plane do have a substantially triangular cross section which is open at the bottom. Said fluke parts are internally provided with reinforcing ribs which extend up to the underside plane. Accordingly the lower edges of said reinforcing ribs are exposed at the underside and form an open cell structure, which under normal circumstances will not hamper the penetration of the fluke into the soil but can give additional resistance upon withdrawal of the anchor. Said reinforcing ribs have to be very strong to give strength to the fluke parts because of their open structure. Said known anchor has only a single shank which has a pivotable point of connection in its rear half of the fluke and an adjustable point of connection close to the rear end of the fluke. Said shank is placed in the central plane of symmetry but if the anchor yaws or roles due to being subjected to unequally distributed loads, such shank and its points of connection are heavely loaded. Said heavy loads have to be taken up by the structure of the flukes or fluke parts. Anchors can be subjected to very heavy loads from almost any direction. When they are lowered upon the sea bottom in particular when they are dropped sudden loads can occur when they hit the bottom or obstacles. Upon reaching said bottom they ara not oriented in the proper position nor in the proper direction for becoming dug in the soil and deliver anchoring forces. Very often they have to be turned over during being dragged over the soil of the bottom, can meet obstacles, stones rock and the like and when they have reached the proper position to start digging in the fluke parts often meet unequal resistances. If there is only a single shank the two fluke parts of the above-mentioned prior art anchor will generate heaving bending forces there where the two fluke parts merge into each other which is at and adjacent to the said central plane of symmetry. This makes it necessary to provide reinforcing ribs in different directions. The substantially triangular cross section of the fluke parts have the advantage that once properly being dug into the soil the laterally inclined top faces enlarge the area of the soil above the anchor against which the anchor finds support. The construction of said known anchor is however extremely complicated due to the presence of the reinforcing ribs and does not have the possibility to add additional weight. It is observed that from EP-A-0,049,544 an anchor is known having a double shank. Said double shank is connected, if so desired, adjustable with a fluke formed by a single flat plate. The two shank arms have connecting points with said fluke plate which are spaced apart and lie at equal distances from the central plane of symmetry and extend towards each other from the fluke towards a single point of connection in a manner such that they form between them a sharp angle. When said anchor is dug into the soil the flat top surface of the fluke does not enlarge the mass of soil against which the fluke finds support. However if the shank arms are sufficiently deep dug in their inclined outer faces will help in somewhat increasing the lateral area of support although they mainly are present in a portion of the soil which has been disturbed by the anchor upon being dug in. Although a shank has two arms connected at spaced apart locations with the fluke all bending forces have to be taken up by the plate which forms the fluke and in particular at the points of connection between fluke arms and plate. Object of the invention . Purpose of the invention is to provide an anchor which is simple of construction, nevertheless extremely strong, allowes excellent penetration of fluke and shank and optimal distribution of load transfer between shank and fluke as well as generating a broad load bearing mass above the anchor when dug in. Short description of the invention . According to the invention this purpose is achieved in that the bottom of the box-like structure of the fluke is formed by one flat plate, that the triangular cross sections of the two fluke parts extend from the outer side edges of the respective fluke parts towards a common vertical strip between bottom and top at the said central plane, that the ridges over their entire length are provided with a strip in planes parallel to the central plane, which strips have openings for transfer pins to connect the shank arms with the said strips, that each arm of the shank has a rear part which curves downwardly towards said points of connection with the said strips and which lies in a plane parallel to the central plane, which rear parts have a first point of connection by means of said pin between one third and two thirds of each ridge strip away from the tip and a second point between two thirds and the rear end of said ridge strip, which shank parts are interconnected by a flat plate at the transition between rear part and front part, which plate lies in the plane which is substantially parallel to the plane of the bottom, which front parts are the only parts which extend towards each other. Accordingly the fluke is formed by a closed box which at the top ridges of the two fluke parts does have a strip at the top of each ridge upon which the lower and major parts of the shank arms are attached which parts extend in parallel planes of which each plane coincides with the plane through the tip the of each fluke part and the said strip. Tension forces which act at the common point of connection of the shank arms are transferred into forces acting in the parallel shank arm parts whilst transverse force components are taken up by the transverse plate between the two shank arms. Due to this the force distribution is transversed in the best way possible towards the two fluke parts whilst at the same time soil which has to pass the gap between the shank parts is properly guided. It is observed that from EP-A-0,220,758 an anchor is known the fluke of which is formed by a single fluke in box-like structure with reinforcements and a slightly curved bottom plate which fluke has upon its upper surface a connecting box to which the arms of a double shank are connected which arms from said connecting box converge towards the common point of connection to which the haulser has to be attached. In this known anchor load distribution is less favourable. The combination of features of the anchor according to the invention allows for optimal transfer of loads which occur in the entire construction, allows for optimal penetration into the soil. Said combination of features cannot be obtained with the above discussed prior art anchors because if a double shank would be combined with the anchor having two fluke parts, said fluke would still be of open structure whereas if a shank with two shank arms would be connected to a box-like structure having a flat top plate then high-tension forces and accordingly sheering forces cannot be avoided at the connection area of the shank parts with said top plate. The invention now will be further described with reference to the drawing which in a perspective view shows one embodiment of the anchor according to the present invention. Detailed description of the invention . The drawing shows an anchor having a fluke 3 with two fluke parts 5, 6. Said fluke parts are interconnected at the central plane schematically indicated with the interrupted line 9. The fluke has a bottom plate 2 which is completely flat, has top plates 5, 5' and 6, 6' respectively which top plates at each fluke part in a transverse direction form with the bottom plate 2 a substantially triangular cross section cut off at the central plane 9 where the top walls 5 and 6 respectively merge into each other. A vertical rib can be provided there interconnecing bottom plate and top plates. Said two fluke parts 5, 6, 5', 6' and 2 form an integral unit and each have a forwardly tapering tip one tip 7 being defined by the tapering edges 10 and 11 and the other 8 being defined by the tapering edges 12, 13. The inner edges 11 and 12 meet each other at the said central plane. The bottom plate 2 and the top plates 5, 5', 6, 6' form a box-like structure which can be closed at the rear side or even can be open, can be filled with a heavy mass such as concrete. The top plates 5, 5' and 6, 6' respectively form ridges 22 and 23 respectively at which in the embodiment shown vertical plates 22' and 23' are welded. The anchor shown has a shank generally indicated with 14 having two shank arms 18 and 19 each having a rear part 24 or 25 respectively and a front part 26 or 27 respectively. Said front parts meet each other at 20 and 21 and are interconnected there and have an opening for the attachment of a chain or the like. The rear parts 24, 25 extend parallel to each other and parallel to the central plane of symmetry. They have each a pivotable point of connection such as 15 and an adjustable point of connection such as 16. The point of connection 15 lies between one third and two thirds of the length of ridge 22 and the adjustable point of connection between two thirds and the end of ridge 22, seen from the tip 7 or 8 respectively rearwardly. Said position is the best position for transferring load into the ridge part of the box-like structures. Between said parallel rear parts 24 and 25 stiffening ribs can be present but preferably a stiffening plate 34 is provided at the transition 28 and 29 respectively between the rear parts 24 and 25 and the front parts 26 and 27 respectively. Said plate 34 may have cutting teeth. Since lines 28 and 29 are parallel to each other and so are the lines where the front ends meet at 20 and 21 all descriptive lines of the front parts 26 and 27 are parallel to each other. Accordingly the opening between the shank arms offers no resistance to the soil which in the drawing from right to left has two parts through the space between the shank arms. Once the anchor is penetrated its bottom plate 2 extends at a sharp angle with the horizontal and this means that the shank 14 as a whole is tilted to the right due to which the outer faces of the front parts 26 and 27 will add a contributional resistance against withdrawal of the anchor to the resistance generated by the fluke parts.

Claims: Anchor with a double shank (14, 18, 19) and a fluke (3) with two fluke parts (5, 6) each with a forwardly pointed tip (7, 8) on either side of the central plane (9) of symmetry of fluke and shank (14), which two fluke parts (5, 6) form an integral unit at the said central plane with their front edges (10, 11, 12, 13) tapering towards the respective tips (7, 8) and from each tip (7, 8) extend rearwardly with a cross section between bottom and top which is substantially triangular with the apex of each triangular cross section on a ridge line which extends parallel to the said central plane from tip (7, 8) to the rear end at a sharp angle (α) with the bottom (2) which bottom and top of the fluke parts (5, 6) form a box-like structure, characterized in that the shank (14) has two arms which at a predetermined sharp angle extend towards the fluke from a common point of connection of the shank arms towards said ridges respectively, each shank part having a pivotable point of connection with the said ridge and a spaced apart other point of connection, in that the bottom of the box-like structure of the fluke is formed by one flat plate, that the triangular cross sections of the two fluke parts extend from the outer side edges (10, 13) of the respective fluke parts (5', 6') towards a common vertical strip between bottom and top at the said central plane, that the ridges over their entire length are provided with a strip (22', 23') in planes parallel to the central plane which strips have openings for transfer pins to connect the shank arms (24, 25) with the said strips (22', 23'), that each arm (18, 19) of the shank has a rear part (24, 25) which curves downwardly towards said points (15, 16) of connection with the said strips (22', 23') and which lies in a plane parallel to the central plane (9), which rear parts have a first point of connection by means of said pin (15) between one third and two thirds of each ridge strip (22', 23') away from the tip (7, 8) and a second point between two thirds and the rear end of said ridge strip (22', 23'), which shank parts are interconnected by a flat plate (34) at the transition between rear part (24, 25) and front part (26, 27), which plate (34) lies in the plane which is substantially parallel to the plane (2) of the bottom, which front parts are the only parts which extend towards each other.

Inventors: ALHAYARI SAMY, GRAMET JEAN-CLAUDE, ALHAYARI, SAMY, GRAMET, JEAN-CLAUDE
Applicants: SINGLE BUOY MOORINGS, SINGLE BUOY MOORINGS INC.
Application year: 1992
Main classification: B63B21
IPC codes: B63B21