Abstract:
This invention relates to a connector, particularly to a shackle suitable for use in connecting two links of a chain or a chain to an anchor, more particularly to a connector comprising a first portion and a second portion, at least one first connector arm on the first portion and at least one second connector arm on the second portion, wherein both the first and second connector arms have multiple bearing surfaces, preferably six, and are able to engage one another when the connector is coupled by means of the bearing surfaces. The connector of the present invention has the advantage of having a break load of 1.3[0.0274 d 2 (44−0.08 d) kN, wherein d is the nominal diameter, and preferably a thickness of 1.3 d.

Description:
FIELD OF INVENTION 
     The present invention relates to a connector, particularly to a joining link or shackle suitable for use in connecting chains or a chain and an anchor. 
     BACKGROUND OF INVENTION 
     Anchor chains for marine use can be connected using known designs of shackles. Shackles usually comprises at least two portions, each of which will usually connect with a respective link on separate chains or with a link on a chain and an anchor, before the two shackle portions are connected together to join the chains or the chain to the anchor. The shackle should preferably be capable of withstanding the same forces as the chain links, but this is often a difficult compromise for the multipart shackle and frequent inspections are needed to assess the condition of the shackles, which is costly and inconvenient. 
     There are many different styles of shackles, swivels and connecting links. The two main types of connecting links (chain or anchor) in use are Kenter style links or “Baldt” style links. The difference between the two is in the design of the way the links open and close. The Kenter link consists of two opposite halves that slide together. The Baldt link has a C-shaped body and uses two caps to connect the open end of the C together. 
     U.S. Pat. No. 5,983,620 to Amoss discloses a “Kenter” type detachable connecting link without button shoulders that shows no apparent loss of strength compared to one with button shoulders. Versatility, however, is increased, enabling one link to fit several chain sizes, instead of just one. Preferably the button is aligned with the link cross section. 
     French Patent 2 581 150 to Caron discloses two identical half-links with a male end and a female end. The two half-links form, by mutual interlocking, a link locked by a locking component. Each male end comprises a bearing surface composed of several staged elementary bearing surfaces. The invention applies to chains for boats and oil platforms. 
     WO 2007/068472 to Feuerstein discloses a connector, particularly to a shackle suitable for use in connecting two links of a chain, more particularly to a connector comprising a first portion and a second portion, at least one first connector arm on the first portion and at least one second connector arm on the second portion, wherein both the first and second connector arms have at least one bearing surface and are able to engage one another when the connector is coupled by means of the bearing surfaces. 
     However, none of the prior art connectors meet the new offshore standards established in 2009 by DNV-OS-E302. There are many classification societies such as ABS (American Bureau of Shipping), Lloyds, BV (Bureau Veritas), DNV (Det Norske Veritas), etc. that examine links and supervise the testing before certifying its use for a vessel or mooring setup under their classification. According to the new DNV standard, the breaking load (kN) of a grade R5 connector is 0.0320 d 2 (44−0.08 d) (wherein d is the chain nominal diameter). Therefore, for example, the breaking load for a 76 mm shackle should be about 7009 kN under the new DNV standard. However, typical 76 mm shackles, regardless of the configuration have a break load of 6001 kN, which is well below the new DNV standards. Accordingly, there remains a need for a shackle that can meet the new DNV standards. 
     SUMMARY OF INVENTION 
     Accordingly, it is an object of the invention to provide a connector that meets the new DNV standards. 
     It is another object of the invention to provide a connector comprising a first portion and second portion, at least one connector arm (first connector arm) on the first portion and at least one connector arm (second connector arm) on the second portion, wherein the first and second connector arms are able to engage one another when the connector is coupled, each connector arm having at least one bearing surface, preferably a plurality of bearing surfaces, which engage one another in the coupled connector and which transmit force between the first and second portions. In a preferred embodiment at least six bearing surfaces are provided on each arm. 
     It is another object of the invention to provide a connector wherein the break load is at least 1.3[0.0274 d 2 (44−0.08 d) kN, wherein d is the nominal diameter, which is 30% higher than the prior art. 
     It is another object of the invention to provide a connector with a break load of at least 1.3[0.0274 d 2 (44−0.08 d) kN and a thickness of 1.30 d. In other words, it is an object to provide a connector that can meet current DNV standards while maintaining a thickness of no more than 1.30 d. 
     According to a preferred embodiment, the first portion has at least one further connector arm, hereinafter referred to as the “third connector arm”, and the second portion also has at least one further connector arm, hereinafter referred to as the “fourth connector arm”, wherein each connector arm comprises at least one shoulder, i.e., a first, second, third and fourth shoulder, respectively, and each shoulder has at least one bearing surface, i.e., a first, second, third and fourth bearing surface, respectively. The first and third connector arms provided on the first portion have at least six first bearing surfaces located on at least six respective first shoulders on the first connector arm and at least six third bearing surfaces located on at least six respective third shoulders on the third connector arm. The second and fourth connector arms provided on the second portion have at least six second bearing surfaces and at least six fourth bearing surfaces located on the at least six respective second and fourth shoulders. The first and second bearing surfaces and the third and fourth bearing surfaces are able to engage one another, so that force is transmitted between the two connector portions by the respective shoulders engaging one another in the coupled connector. 
     In another preferred embodiment, each of the connector arms typically has six shoulders and six bearing surfaces, wherein each bearing surface is provided on one corresponding shoulder. 
     In another preferred embodiment, one connector arm of a mating pair, e.g., first and second connector arms and third and fourth connector arms, respectively, has a different structure than the other connector arm of the mating pair. For example, one connector arm of the mating pair can have a head, and the other can have a socket in which the head at least partially engages. Each head and socket comprises at least one bearing surface. Where two connector arms are provided on each connector portion, one can have a head, and the other a socket, so as to engage with the socket and head respectively on the other connector portion, preferably head or socket on the first portion correspond to head or socket on the second portion, so that basically both portions of the connector have engaging members of equivalent geometry. 
     In another preferred embodiment, the bearing surfaces are provided on shoulders extending at least partially laterally outward from the head, and extending at least partially laterally inward from the socket. The shoulders on each mating pair of connector arms can have complementary shapes, so that the heads fill the sockets and leave little space for movement when the connector is coupled. 
     In another preferred embodiment, the bearing surfaces are typically aligned parallel to the longitudinal axis, i.e., the shoulders are “stacked” along the longitudinal axis of the connector. The first and third bearing surfaces are typically opposed to the second and fourth bearing surface, so that each first and third bearing surface faces one end of the coupled connector, and each second and fourth bearing surface of the coupled connector faces the opposite end of the connector. In the coupled connector, the bearing surfaces on the first portion and the second portion can then be trapped behind one another. Also, when the connector is coupled, at least two bearing surfaces on the connector arms of a mating pair of connector arms are engaged against one another in a flat plane that is perpendicular to the longitudinal axis of the connector. This arrangement can transmit force more efficiently, and reduces the tendency towards movement in the coupled connector. 
     The provision of at least six separate bearing surfaces on respective shoulders increases the total bearing surface area available to transmit force between the two connector portions, and reduces the pressure applied to each separate surface, thereby reducing fatigue damage of the components. 
     In another preferred embodiment, the at least six separate bearing surfaces are aligned along the longitudinal axis of the connector. This can avoid increases in cross sectional area of the connector necessary to bear the axial loads. 
     In a further preferred embodiment, the two portions are generally U-shaped, with a connector arm on each side of the U. Typically, the two arms on each connector portion can be a different length from one another, so that when the connector is coupled, the mating portions are not in the same plane on the connector but are axially offset with respect to one another. 
     In a further preferred embodiment, the two portions are connected by means of a connector pin. In another embodiment, the connector pin is optionally driven laterally through each of the portions of the coupled connector to secure them together. Driving the pin through the mating portions can be facilitated by axially offsetting the mating portions. 
     In a further preferred embodiment, the two portions are braced in the coupled connector by a spacer. 
     There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described further hereinafter. 
     In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. 
     As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may be readily utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that equivalent constructions insofar as they do not depart from the spirit and scope of the present invention, are included in the present invention. 
     For a better understanding of the invention, its operating advantages and the aims attained by its uses, references should be had to the accompanying drawings and descriptive matter which illustrate preferred embodiments of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1   a  is a perspective view of the connector of the present invention shown in disassembled form; 
         FIG. 1   b  is a close-up side view of the head and socket from  FIG. 1   a;    
         FIG. 2  is a side sectional view of the connector of  FIG. 1 ; 
         FIG. 3  is a sectional view of the connector of  FIG. 1 , viewed from arrow A in  FIG. 2 ; 
         FIG. 4  is a side sectional view of another embodiment of the connector of the present invention; and 
         FIG. 5  is a sectional view of the connector of  FIG. 4 , viewed from arrow A in  FIG. 4 . 
         FIG. 6  is a graph of a break load test for the connector of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to  FIGS. 1-3 , a first preferred embodiment of a connector  100  has a first portion  102  and a second portion  104 . The two portions  102 ,  104  are substantially similar. The coupled connector  100  has a longitudinal X axis, which also applies to both the first and second portion  102 ,  104 , when the connector  100  is coupled. 
     The first connector portion  102  is generally U-shaped and has a first arm  106  with a socket  108  and a third arm  110  having a head  112 . The socket  108  and the head  112  as engaging members are disposed at the open end of the first connector portion  102  extending away from the closed end of the U-shaped portion. The socket  108  has preferably six shoulders  108   s  protruding radially into the socket  108  and extending around the inner circumference of the socket  108 . The head  112  on the third connector arm  110  has preferably six radially outwardly protruding shoulders  112   s  extending circumferentially around three sides of the head  112 . The side of the head  112  that is closest to the X axis has no shoulder. All of the shoulders  112   s ,  108   s  are aligned in a plane parallel to the X axis. 
     The second connector portion  104  is also generally U-shaped and has a fourth arm  114  with a socket  116 , and a second arm  118  having a head  120 . Again, the head  120  and the socket  116  are disposed at the open end of the connector portion  104  extending away from the closed end of the U-shaped portion. The socket  116  has preferably six inwardly protruding shoulders  116   s  extending around the circumference of the socket  116 . 
     The head  120  on the second connector arm  118  has six outwardly protruding shoulders  120   s  extending circumferentially around three sides of the head  120 . The side of the head  120  that is closest to the X axis has no shoulder. All of the shoulders  116   s ,  120   s  are aligned in a plane parallel to the X axis. 
     The shoulders  108   s  and  116   s  on the sockets  108 ,  116  have the same basic structure, as the shoulders  112   s  and  120   s  on the heads  112 ,  120 . Therefore, in the interests of brevity and simplicity, only the details of the head  120  and the socket  108  will be described in detail, with reference to  FIG. 1   b.    
     Each head shoulder  120   s  is generally triangular in cross section, and has a bearing surface  120   b  facing the closed end of the second connector portion  104 , and a support face that is generally facing the open end of the second connector portion  104 . Each bearing surface  120   b  is flat and is disposed in a single plane that is generally perpendicular to the X axis. The bearing surfaces  120   b  are disposed in a single plane that is generally parallel to the X axis. The support surface tapers from the radially outermost edge of the bearing surface  120   b  back into the base of the head  120 . 
     Each socket shoulder  108   s  is also generally triangular in cross section, and has a bearing surface  108   b  facing the closed end of the first connector portion  102 , and a support face that is generally facing the open end of the first connector portion  102 . Each bearing surface  108   b  is flat and is disposed in a single plane that is generally perpendicular to the X axis. The bearing surfaces  108   b  are disposed in a single plane that is generally parallel to the X axis. The support surface tapers from the radially outermost edge of the bearing surface  108   b  back into the root of the socket  108 . 
     It will be noted that each bearing surface  108   b ,  120   b  faces the closed end of the first and second connector portions,  102 ,  104 , respectively, whether disposed on a socket  108 ,  116 , or a head  112 ,  120 , and whether disposed on the first or second connector portion  102 ,  104 , respectively. Therefore, when the first and second connector portions  102 ,  104 , respectively, are facing one another before being coupled together, the bearing surfaces  108   b ,  120   b  to be engaged with one another are facing in opposite directions towards the closed ends of their respective connector portions  102 ,  104 . 
     A spacer  122  is provided in order to brace the arms apart in the coupled connector  100 . The spacer  122  has a flat outer surface on each side, with a step  124  that engages in a corresponding recess on the inner surface of the arms  106 ,  114 , so that the spacer  122  can fit between the arms in only one configuration. In this configuration, a bore  126  that extends through the spacer  122  lines up with bores through the arms  106  and  114 , to allow the passage of a fixing pin  128  through the bore  126  to secure the first and second connector portions,  102 ,  104 , respectively, and the spacer  122  together in a particular configuration. The fixing pin  128  and the bore  126  each have tapered sides, so that when the fixing pin  128  is hammered into the bore  126 , it lodges in position, fixing the connector  100  together. The fixing pin  128  can be sealed within the bore  126 , by melting or hammering a lead plug within the opening of the bore once the fixing pin  128  is in position. 
     When the connector  100  is to be coupled, the first and second connector portions  102 ,  104 , respectively, of the connector  100  are arranged side-by-side with their open ends facing one another, as shown in  FIG. 1   a , so that the head  120  on the second connector arm  118  is lined up with the socket  108  on the first connector arm  106 , and the head  112  on the third connector arm  110  is lined up with the socket  116  on the fourth connector arm  114 . The fixing pin  128  is removed from the bore  126 , and the heads  112 ,  120  are inserted into the sockets  108 ,  116  by moving the two portions  102 ,  104  sideways towards one another, so that the bearing surfaces  108   b ,  120   b ,  112   b  and the support surfaces on the heads  112 ,  120  and the sockets  108 ,  116  interlock with one another. The spacer  122  can then optionally be slid into the space between the arms  106 ,  114 , so that the steps  124  on the spacer  122  engage in the corresponding recesses on the arms  106 ,  114 , whereby the bore  126  through the spacer  122  is aligned with the bores through the arms  106 ,  114 . The fixing pin  128  is then hammered into the bore  126  and sealed as described above. 
     In this configuration, the bearing surfaces  120   b  on the head  120  on the second connector arm  118  are locked behind the bearing surfaces  108   b  on the socket  108  on the first connector arm  106 . Likewise, the bearing surfaces  112   b  on the head  112  on the third connector arm  110  are locked behind the bearing surfaces on the socket  116  on the fourth connector arm  114 . When the coupled connector  100  is in tension, the force is transmitted between the first and second portions  102 ,  104  by the bearing surfaces  108   b ,  120   b ,  112   b  that are locked against one another. The support surfaces on each component support the bearing surfaces  108   b ,  120   b ,  112   b  against deformation. 
     The bearing surfaces  108   b ,  120   b ,  112   b  are aligned with one another in the same plane that is parallel to the main X axis of the connector  100 . The axial load borne by the bearing surfaces  108   b ,  120   b ,  112   b  is spread between the six shoulders  108   s ,  120   s ,  112   s ,  116   s  on each arm  106 ,  118 ,  110 ,  114  of each connector portion  102 ,  116 , thereby reducing the force borne by any specific shoulder  108   s ,  120   s ,  112   s ,  116   s.    
     The angle of taper of the support surface, and the extent to which the bearing surfaces  112   b ,  120   b  protrudes radially from the base of the heads  112 ,  120  is variable between different embodiments. Increasing the radial extent of the bearing surfaces  112   b ,  120   b  increases the surface area through which force is transmitted, which is beneficial, because it reduces the pressure applied on each shoulder  112   s ,  120   s.    
     As seen in  FIG. 3 , the connector has a thickness D and a nominal diameter d. According to a preferred embodiment, D=1.3 d. 
       FIGS. 4 and 5  show a second embodiment  200 , in which the first and second portions  202 ,  204  are different from one another, but are attached in the same way as described above. Whereas the connector  100  is most useful for connecting two links of chain that are of similar size, the second embodiment  200  shown in  FIGS. 4 and 5  is designed for connecting different size/weights of chain or a chain to an anchor. Thus, the first portion  202  of the second embodiment  200  has an arm  206  with a head  208 , having shoulders  208   s , as previously described, and an arm  210  having a socket  212  with internal shoulders  212   s  as previously described. The second portion  204  has an arm  214  with a head  216  and shoulders  216   s , and a further arm  218  with a socket  220  and internal shoulders  220   s , as previously described. A bore  222  runs through the first and second portion  202 ,  204 , respectively. The closed end of the first portion  202  is relatively narrow, and is designed for use with lightweight chain. The closed end of the second portion  204  has a heavier gauge, and is designed for use with heavyweight chain or anchor. The components of the second embodiment  200  function in the same way as those described for the connector  100 . 
     Example 
     A break load test was conducted on a 76 mm/3″ connector, wherein D=1.30 d, as shown in  FIGS. 1-3 .  FIG. 6  is a graph showing the break load test results. Although only a 16% improvement was expected, the break load test surprisingly yielded a break load of 8009.3 kN. In other words, the connector  100  of the present invention yielded a break load that was surprisingly 33% better than the connectors of the prior art. Moreover, the break load test also showed that the connector  100  failed in the crown area, rather than at the locking mechanism. Traditionally, such connectors fail at the locking mechanism. In this test, however, the locking mechanism remained intact and in fact, even after the connector of the present invention failed, the locking mechanism remained intact and was easily disassembled. 
     Having now described a few embodiments of the invention, it should be apparent to those skilled in the art that the foregoing is merely illustrative and not limiting, having been presented by way of example only. Numerous modifications and other embodiments are within the scope of the invention and any equivalent thereto. It can be appreciated that variations to the present invention would be readily apparent to those skilled in the art, and the present invention is intended to include those alternatives. 
     Further, since numerous modifications will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to as falling within the scope of the invention.