Abstract:
The invention relates to a sack cutting means ( 10 ) for offshore emptying of content from a package, comprising a means ( 11 ) for cutting up the package, means ( 21 ) for separating the package from its content and means ( 20 ) for removing the emptied package from the cutting means, said means ( 21 ) for separating the content at least from the package comprising means ( 13 ) for ripping the package open, one or more transporting means and a rotating drum ( 21 ) provided with openings through which the content separated from the package is allowed to leave the drum ( 18 ). Further, the sack cutting screw ( 11 ) is separated from the drum ( 18 ) and that below both the sack cutting screw ( 11 ) and the drum ( 17 ), a means ( 20 ) for collecting and transporting away the content of the sacks is arranged, said means being configured in such way that the content of the package is removed at one end, while the waste package is removed at the other end of said sack cutting means ( 10 ).

Description:
THE TECHNICAL FIELD 
       [0001]    The present invention relates to means for cutting sacks in order to empty a more or less powder shaped content into a container means, such as for example a bag or the like. More specifically, the invention relates to a means for emptying the content out of a package at an offshore location, comprising a means for cutting up the package, means for separating the content in the sacks from the sacks and means for removing the emptied packages. The means for separating the content at least from the package comprises a means for cutting up the package, one or more transporting screws and a rotating drum provided with openings, through which the separated content of the packages is allowed to escape out of the drum. 
       BACKGROUND FOR THE INVENTION 
       [0002]    During drilling of offshore wells a drill liquid is required. Such drill liquid may be water based or oil based. The drill liquid consists of a mixture of a number of different chemicals and compounds, and several of these ingredients represent a risk for the human being. The chemicals are commonly supplied in sacks of 25-30 kg and the content of the sacks is fed into a mixer and mixed into a circulating drill fluid. The drill fluid has to be tailor made to the specific requirements at any time, the need for different mixtures often being changed. On this basis it is thus required that the mixing of the drill liquid is executed on the platform as an integral part of the drilling operation. 
         [0003]    The problem to be solved is thus how to cut up the sacks and empty these in order to mix the content of the sacks into the circulating drill liquid in a most efficient manner. Such mixing should, amongst other due to the health hazards, but also from an economical point of view, be automatic and without representing a health risk for the operator. 
         [0004]    A large number of different machines, performing such operations, are already available on the market. 
         [0005]    U.S. Pat. No. 4,930,968 describes a sack cutting machine comprising a unit for cutting up the sack so that the powder inside may be released, a first transporting screw for transport of the powder and the sack; a drum for separating the powder from the sack, the first transport screw being concentrically arranged in the drum; a feeding screw arranged below the drum and in open communication with the drum for transport of the powder to a separate location and a means for collecting ripped, empty sacks, arranged at the opposite side of the drum and said first feeding screw, seen with respect to the feeding opening for filled sacks. According to this solution an intact sack with its powder content is fed into the machine at the end of the sack cutting means, whereupon the sack by means of the first transporting screw is moved in a direction towards a stopper whereby the sack is cut and the content released, whereupon the direction of rotation is reversed. 
         [0006]    EP 1 123 868 describes a sack cutting machine in the form of a feeding screw, arranged in a tray, provided with fixed knives for cutting the sack, and a drum arranged at one end of the feeding screw, the content being separated from the sack in said drum. At the opposite end an opening directing towards a tray for collection of empty sacks is arranged. 
       SUMMARY OF THE INVENTION 
       [0007]    An object of the invention is to provide a solution suitable for being placed on an offshore platform, such solution also must be reliable and eliminating, or at least substantially reducing, the health risks for the operator. 
         [0008]    A second object is to provide a machine securing correct quality of the drill liquid in an efficient and cost optimal way. 
         [0009]    A still further object is to provide a machine which quickly may adjust or change the content or mixture of the drill liquid. 
         [0010]    The objects are achieved by means of a solution as further defined by the characterized part of the independent claim. 
         [0011]    According to the invention, the drum is suspended and floats freely without being supported by shafts and bearings, the drum being suspended by at least one belt extending around the drum, said belt also running over at least one in respect to the drum, separated, rotating driving shaft. 
         [0012]    According to one embodiment, said at least one belt is a chain belt running over a correspondingly configured wheel on said at least one driving shaft. 
         [0013]    The chain belt may for example be a sphere or ball string running over a correspondingly configured wheel on said at least one driving shaft. 
         [0014]    According to a further embodiment the drum may be provided with corresponding tracks extending around the periphery of the drum and co-functioning with said belt in order to cause said rotation of the drum. In connection with the drum, a guiding means may be provided, securing that the drum is kept in proper position during rotation. 
         [0015]    Such guiding means may comprise rotating wheels which runs in contact against the outer surface of the drum, at the upper part and possibly also at the lower part of the drum. At last four rotatably arranged wheels may for example be used at the upper end, and possibly also with wheels arranged at the lower end of the drum. In stead of, or in addition, guiding means may be in the form of at least one rail shaped guide having a curved support surface corresponding to the outer shape of the drum. One or more guides may also lie in contact with the lower external surface of the drum. 
         [0016]    In order to prevent axial displacement of the drum, the drum may lie on contact with one or more stopping surfaces or means. 
         [0017]    With a solution according to the present invention a solution is provided being so compact that the footprint is reduced as much as possible, so that the unit is well suited for being installed on an offshore platform. 
     
    
     
       SHORT DESCRIPTION OF THE DRAWINGS 
         [0018]    In the following an embodiment of the invention shall be described in closer detail, referring to the drawings, where: 
           [0019]      FIG. 1  shows schematically a side view of an embodiment of the invention; 
           [0020]      FIG. 2  shows a vertical section through the sack cutting means, seen along the line A-A in  FIG. 1 ; 
           [0021]      FIG. 3  shows a vertical section through the sack cutting means, seen along the line B-B in  FIG. 1 ; and 
           [0022]      FIG. 4  shows a vertical section through the sack cutting means, seen along the line C-C in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]      FIG. 1  shows schematically a side view of a preferred embodiment of a sack cutting means  10  according to the invention. The sack cutting means  10  comprises four main elements. These are the cutting means  11 , a separation means  21 , a transporting means  38  and a compressing means  20 . 
         [0024]    The cutting means  1  consists of a housing or casing  25  with a rotatable cutting screw  22 . The screw is in the form of a central shaft  12  and a helical blade body  13  twisting along the central shaft  12 . The blade body  11  is rigidly fixed to the central shaft  12 . The screw means  11  is powered by a driving unit  14 , such as an electro motor and preferably a gear. At least one end of the screwing means  11  is supported in the housing  15 . The housing  15  may preferably surround the screw  13 , so that a tray  16  is formed at least at the lower side of the housing. The tray  16  is along its bottom part provided with openings  26  allowing the content of the sacks to escape, so that said content is allowed fall out of the tray  16 . The perforated grating in the tray  16  may preferably be suspended on rubber rails or similar dampening means, allowing a degree of vibration of the tray if required, without transferring possible vibrations to the remaining parts of the machine. Such vibration secures that the content from the sacks is transported out of the tray. A means (nor shown) for transferring the content from the sacks for example to a mixing container is arranged below the perforated tray. Such means for transportation may be of any suitable type, well known to the person skilled in the art. 
         [0025]    At the end of the housing  15  where the screw  13  is connected to the powering unit  14 , the upper part of the housing is provided with an inlet opening  27 . The inlet opening  27  may preferably be provided with a preferably dustproof lid, the lid being connected to a switch so that the screw is not allowed to rotate when the lid is not in a closed position. In such way dust and powder is prevented from escaping uncontrolled from the unit and the possibility of causing injury to the operator is eliminated. 
         [0026]    At the opposite end of the housing  15  the separating means  21  is arranged. The separating means  21  comprises a house or a casing comprising a cylindrical, rotatably arranged grating or drum  17 , separating the remaining part of the powder and the packaging. The separating means is orientated in such way with respect to the cutting screw  22  that the cutting screw  22  is partly projecting into the rotatably arranged grating  17 . The grating  17  is provided with openings so that the powder or the fine graded material is fed into the grating by the cutting screw  22 , is allowed to fall out through said openings  18 , while the ripped sack (not shown) is transported axially out through the rotating drum in any suitable way. The rotatable drum  17  is made of grating or of a perforated plate and is suspended by one or more belts or chains  28  which is suspended on a rotatably shaft  29 , connected to a power unit (not shown), such as an electro motor or the like, and preferably a gear. In order to prevent sideways displacement of the drum  17 , the drum  17  is kept in place by means of a plurality of guiding wheels  30 . Four guiding wheels  30  may for example be used, arranged in pairs in spaced relation from each other at the upper side of the drum  17 . Guiding wheels may optionally also be arranged at the lower side of the drum  17 . The drum  17  may optionally also be supported against axial movement or displacement by a contact surface or the like (not shown) at each end of the drum  17 . Internally in the drum  17  blades  23  are arranged forcing the package around and at the same time moving the package in axial direction out of the drum  17 . 
         [0027]    Below that part of the sack cutter  10  a compressing means  20  is arranged. Said compressing means  20  comprises a housing  24  containing a rotatable screw  32  rotating in a duct ending at an outlet. This end may be connected to a collecting means, such as a bag for receipt of emptied packages as such emptied sacks are forced out of a transfer pipe  24  and into the collecting means by means of the rotating screw  32 . The rotating screw  32  is powered by a driving unit (not shown), such as an electro motor. The outlet  24  is arranged below the sack cutting means and the screw  34  is configured in such way that the emptied sack moves from right towards left in the Figure. An emptied sack exits the drum  21  at the free end and is then fed or falling down through an opening  40  down onto the screw  34 , moving the emptied sack back under the drum and out through the opening  24  at the opposite end of the screw  14 . 
         [0028]    The content in the sacks, which often is in the form of powder, is transported out of the unit  10  through the exit pipe  31 , arranged at the end of the unit  10  and communicating with the screw  38 . 
         [0029]    As shown in  FIG. 1  the sack cutting means  10  is supported by a plurality of legs  39 . 
         [0030]      FIG. 2  shows a vertical section through the screw cutting means  11 , seen along the line A-A in  FIG. 1 . As shown in  FIG. 1 , a feeding table  35  provided with a cover comprising a dust proof lid  36  is arranged in conjunction with the opening  27 . Further, the entire sack cutting means  10  may be completely enclosed in its own housing  37 , so that the entire unit is enclosed, thus avoiding emission of dust to the environment. Further, along the bottom of the entire sack cutting unit  30  along its entire length a transport means  38  is arranged for transport of the content of the sacks out of the sack cutting means  10 . Said transport means  38  may for example be in the form of a screw or the like, preferably rotating in such direction that the content of the sacks is transported out of the machine. The transport means  38  is arranged at the bottom of a tray shaped channel, the channel being in open communication with a tray  16  above through openings communication with the sack cutting screw  22  and the perforated drum  21 . It should be appreciated, however, that in certain cases it may be desirable to provide the sack cutting means with a reservoir comprising a feed in stead of a transport screw. 
         [0031]      FIG. 3  shows a vertical section through the part of the sack cutting means  10  where the drum  17  is arranged, while  FIG. 4  shows a vertical section seen along the line C-C in  FIG. 1 . As shown in  FIG. 4 , an open channel  40  leads the emptied sack down into the compressing unit  20 . As indicated in  FIG. 4  the compression unit is sideways displaced with respect to the drum  17  and the axis of the cutting blades  13 . 
         [0032]    The functioning of the sack cutting means according to the invention shall in the following be described in further details. 
         [0033]    The sack with its content, for example in the form of a powder or a fine, uniformly graded material, is fed into the sack cutting means  10  through the opening  27 . The cutting screw  22  starts and rotates in a direction so that the sack is screwed towards the rotating grating  17 . On its way towards the grating  17 , the sack is cut open by means of the cutting screw  11 , which also transports the opened sack in direction towards the rotating grating  17 , while the main part of the content of the sack falls down through the openings  26 . According to the invention, the sack is cut into pieces by the helically shaped blades  13  on the screw  11 , the blade edges cutting through the sack material. The blades may be provided with knives, securing proper cutting of the sacks. The sack is fed into one end of the rotating grating  17 , where the sack is turned around by means of internally arranged blades  23  inside the grating  17 . The blades  23  move also the emptied sacks further through the grating  17  and out of the grating  17  at the opposite end. The emptied sack falls down into the compression unit  20  which comprises a compression screw  34 . The screw catches the emptied sack and compresses the emptied sack into a collecting means. Such collecting means may for example be a bag or the like. 
         [0034]    Even if the cutting screw  11  with its cylindrical core  12  is shown, it should be appreciated that the core  12  of the cutting screw  11  may be conical, having a decreasing diameter in direction towards the drum  17 , whereby the sack is compressed more and more and/or cut open more and more in direction towards the drum  17 . Further, it should be noted that knives securing proper cutting of the sacks may be used, securing improved opening of the sack, so that the remaining content in the sack more easily may escape out of the sack prior to the sack being fed towards the drum  17 . In order to improve the cutting and emptying effect the light openings at the opening between the cutting screw  11  and the drum  17  may also be made as small as possible. 
         [0035]    According to the present invention the gradient between the blades of the sack cutting screw may be increased, for example so that the gradient may be reduced, i.e. the distance between the blades being smallest where the sack firstly hits the screw and larger towards the drum  17 . This will contribute to stretching of the sack and hence to improved emptying. 
         [0036]    Further, it should be appreciated that the grating, used in the bottom of the respective trays, preferably may be replaceable. 
         [0037]    In order to secure that dust does no escape uncontrolled, a fan may be arranged inside the unit, thereby establishing a vacuum inside the housing.