Abstract:
The invention relates to scrapers for link chains of in particular double center scraper chain conveyors, comprising a one-part scraper body with a head web connecting two lateral scraper wings and at least one insertion pocket for insertion of a horizontal chain link of the link chain and securing scraper by means of a detachable scraper-securing element. In order to improve the entrainment of scrapers connected to the horizontal chain links and to be able to use the scrapers even with novel link chains, grooves extend in insides of scraper wings and outsides of an intermediate web over the height of limb beds up to head web and form receivers for entrainment projections on the outer surfaces of limbs of horizontal chain links. The invention also relates to scraper-securing element.

Description:
This application claims priority from International Application PCT/EP2006/002735 filed on Mar. 24, 2006 which is hereby incorporated by reference herein in its entirety and which forms a part of the specification of this application. In addition, copending International Application PCT/EP2006/002734 filed on Mar. 24, 2006 is hereby incorporated by reference herein in its entirety and also forms a part of the specification of this application. 
     The invention relates to scrapers for link chains of scraper chain conveyors, in particular double center scraper chain conveyors, comprising a one-part scraper body with a head web connecting two lateral scraper wings and at least one insertion pocket between the scraper wings for insertion of a horizontal chain link of the link chain and securing the scraper on an inserted horizontal chain link by means of a detachable scraper-securing element which can be connected to the head web, wherein the insides facing one another of the scraper wings are provided below the head web with a groove, the head web has on both front sides bearing zones for the fronts of vertical chain links of the link chain and on its underside on both sides of the bearing zones a limb bed for limbs of the horizontal chain links of the link chain. The invention also relates to the scraper-securing element provided for these scrapers. 
     BACKGROUND OF THE INVENTION 
     A generic scraper is known from DE 102 25 341 C1. The known scraper can be fixed to link chains whose horizontal and vertical chain links in each case comprise oval ring eyelet members with round chain fronts. Fixing of the scraper on the horizontal chain links of these link chains is performed by means of a securing strap which runs in one piece between both insides of the scraper wings and clamps the horizontal chain links from below against the underside of the head web. The securing of the strap on the head web against detachment is performed by means of dowel pins which can be inserted into through bores, which dowel pins penetrate through the pins which are formed on the upper side of the strap and engage with corresponding locking recesses in the head web. 
     DE 197 01 579 A1 discloses a link chain whose front sections have straight front zones and whose vertical chain links have a wire cross-section which is constant around the full circumference and is provided on the outer periphery with a flat section. A link chain formed in this manner can also be used in high-performance scraper chain conveyors and the chain links are subject to less wear than those of a standard scraper chain with vertical and horizontal round wire chain links. The scrapers known from DE 197 01 579 A1 have, for connection to this link chain, a head web on whose underside a pin projects onto which a horizontal web chain link having a transverse web can be pushed and can be fixed by means of separate locking rails. In one particular configuration of scraper and horizontal chain link, the passages in the transverse webs can also be formed substantially T-shaped. This configuration enables a positive-locking closure of pin and transverse web, wherein the chain links can be mounted at the pins only in a defined swivel position. The scrapers provided in DE 197 01 579 A1 require special horizontal web chain links with transverse web and are also not suitable for withstanding the large forces which occur with a high-performance conveyor. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, provided is a scraper for link chains of scraper chain conveyors and a scraper-securing element therefor. 
     A scraper for link chains of scraper chain conveyors, in particular double center scraper chain conveyors, scraper comprising a scraper body having a head web connecting two lateral scraper wings and at least one insertion pocket between scraper wings, pocking being shaped to receive an associated horizontal chain link of an associated link chain and securing scraper relative to associated horizontal chain link by means of a detachable scraper-securing element which is connectable to head web, wings including insides facing one another and inside being below head web, insides each including a groove, head web having front sides that include a bearing zone for the fronts of an associated vertical chain links of the associated link chain and on its underside and head we further including a limb bed on both sides of bearing zones for limbs of horizontal chain links and limb beds having a limb bed height, grooves extend over at least a portion of limb bed height up to head web and forming receivers for associated entrainment projections on the outer faces of the associated limbs of the associated horizontal chain links. 
     An object of the invention is to create a scraper in particular for a link chain with special chain links which has a sufficiently long lifetime and is reliably entrained even in the case of large width and thus high potential conveying power and with low wear by the horizontal chain links of a link chain. 
     These and further objects are achieved according to the invention in that the grooves in the insides of the scraper wings extend over the height of the limb beds up to the head web and form receivers for entrainment projections on the outer faces of the limbs of the horizontal chain links. The scrapers according to the invention are particularly suitable for a link chain which the applicant has developed together with the scrapers and which is the subject matter of a parallel application with the same filing date. In this link chain, entrainment projections which can cooperate with the receivers formed by the grooves on the scrapers by positive fit are formed on the outer surfaces of the limbs of the horizontal chain links in order, as a result, to move the scrapers evenly and well-supported in the conveying direction preferably in a pushing manner. In one embodiment, the grooves in the scraper wings extend on both sides of the limb beds up to the head web such that particularly reliable, even and also low-wear entrainment of the scrapers is achieved in the running direction of the link chain due to the engagement of the entrainment projections with the grooves in the scraper. 
     According to one aspect of the invention, the grooves in the insides extend up to the underside of the scraper wings. This not only enables precise placing and insertion of the horizontal chain links, but rather the grooves can, as is explained further below, also fix and hold a scraper-securing element by positive fit in the direction of movement. 
     The invention can in principle also be used in the case of scrapers for single center scraper chain conveyors in which only two grooves are formed in the insides of the scraper wings and a scraper-securing element extends between these two grooves in the insides of the scraper wings. However, the preferred configuration of the scrapers has an intermediate web located at the head web between both scraper wings, which intermediate web in each case delimits an insertion pocket at one side with its outsides which face the insides and also has in each case a groove in the outside, which groove extends over the height of the limb beds up to the head web and forms a receiver for an entrainment projection on the outer surface of the limbs of the horizontal chain links. A corresponding scraper then has two insertion pockets lying next to one another for horizontal chain links of the link chain strands lying next to one another of a double center chain. Each horizontal chain link inserted into an insertion pocket then engages with its entrainment projections at one side of the chain bed with a groove on the inside of one of the scraper wings and on the other side of the chain bed with a groove in the outside of the intermediate web. 
     According to another aspect of the invention, a scraper-securing element could then be provided which furthermore extends exclusively between both grooves in the insides and, as a one-part scraper-securing element, simultaneously secures both inserted horizontal chain links on the scraper against falling out. Nevertheless, this configuration provides that the grooves also reach in the outsides up to the underside of the central web, wherein the underside of the central web is then formed substantially flush with the undersides of the scraper wings in order to improve the bearing of the scrapers on the conveyor base of a conveyor. Two insertion pockets are therefore present, into which in each case a horizontal chain link with an associated scraper-securing element can be inserted and secured against falling out. 
     According to yet another aspect of the invention, the limb beds are formed for insertion of horizontal chain links which have straight front zones on the front sections and recesses provided with entrainment projections in the outer surfaces of the limbs connecting the front sections to one another. Moreover, the bearing zones are preferably formed at the head web of the scraper for supporting of vertical chain links of a link chain, whose wire cross-section is constant around the full circumference and is provided on the outside with a flat section and on the inside with a circular camber, wherein bevels are formed at the transition of the flat section to the circular arc. It is particularly advantageous for receiving of the horizontal chain links of a corresponding scraper link chain if the limb beds comprise surfaces which run out flat towards the insides of the scraper wings and/or the outsides of the intermediate web, on which surfaces the substantially rectangular horizontal chain links can then be particularly well supported. 
     In accordance with a further aspect of the invention, the fixing of the scraper-securing element on the scraper is by means of a fixing screw and a nut which cooperates therewith. To this end, it is advantageous if a screw passage for the shaft of the fixing screw and/or a recess for insertion of a nut which cooperates with the fixing screw is/are formed in the head web between both bearing zones. It is also advantageous if an introduction inclination for a detachment tool opens into each recess in order to be able to detach a potentially rusted-tight nut from the shaft of the fixing screw even after many hours of operation. In this case, the detachment or tightening of the nut can be performed from above and thus with easy access at all times in the upper trunk of a scraper chain conveyor, wherein possibly for mounting the scraper wings must only be pushed on from above onto the scraper-securing elements and the fixing screws and the screws must be tightened. 
     In accordance with yet a further aspect of the invention, it is advantageous for the cooperation of the scraper with the vertical chain links if the bearing zones preferably embodied as circular arc-shaped cambers also extend over the front sides of a projection protruding downward at the head web between the limb beds and/or are exclusively formed as recesses on the front sides. The preferably flattened outsides of the vertical chain links can then bear on this projection over a relatively large surface area, as a result of which a relatively large bearing face is achieved between the vertical chain links and the front sides of the scrapers and simultaneously a good angling capacity of the vertical chain links in the vertical direction is enabled. This vertical angling capacity is particularly necessary if the link chain with the connected scrapers runs around on a driven chain wheel. The projection is expediently provided centrally with the screw passage. 
     As already explained further above, it is advantageous if the scrapers have scraper-securing elements which can be inserted from below into the insertion pockets and have at their upper side limb beds for the limbs of the horizontal chain links and have at their transverse sides a projection which can be introduced into the grooves. The projection on the transverse sides of the scraper-securing element then secures this by positive locking in the grooves in the insides of the scraper wings or the outsides of the preferably present intermediate web, as a result of which the grooves are given a dual function, namely to bring about, on the one hand, a positive-locking closure between horizontal chain links and scrapers and, on the other hand, a positive-locking closure in the direction of travel of the link chain between the scraper-securing elements and the scrapers. Moreover, the projection can comprise a vertical web with a trapezoidal cross-section which correspondingly cooperates with grooves in the insides and outsides on the scraper which likewise have a trapezoidal cross-section and extend from a groove base to the surfaces of the insides or outsides on the scraper. 
     According to another aspect of the invention, the scraper-securing elements are provided in their base surface with a receiving recess for the screw head of a fixing screw. It is particularly expedient if the receiving recess forms a positive-locking anti-twist device for the screw head since then exclusively a mounting tool for the nut which can be screwed onto the shaft of the fixing screw must be placed from above without the fixing screw having to be fixed by a locknut. In order to tighten the nut, it is then sufficient to prevent a rotation of the scraper. The receiving recess can in particular be formed as a transverse slot which e.g. receives the screw head of a hammerhead screw as a fixing screw in a rotationally fixed manner. 
     According to yet even another aspect of the invention, the width of the scraper-securing means can correspond to the minimum distance of the bearing zones for the vertical chain links on the front zones of the head web. Furthermore, the scraper-securing element can preferably be provided centrally between both entrainment projections with a raised portion on the sides of which limb beds for the limbs of the horizontal chain links are formed. The raised portion and/or the projection can be provided laterally with rounded portions for cooperation with the limbs of the chain links of the link chain, wherein the rounded portions then can run out flat towards the outside or inside. The raised portion and/or the projection can, in the case of the horizontal chain links according to the invention, enclose in inner eyelets of these chain links and lie on top of one another there in the mounting status of scrapers, horizontal chain link and scraper-securing element. 
     The invention also relates to a scraper-securing element for securing a scraper on horizontal chain links of a link chain of a double center scraper chain conveyor which are inserted into insertion pockets on the scraper, wherein the base of the scraper-securing element is provided on its transverse sides with projections for engagement with grooves in the inside of the scraper wings and the outside of an intermediate web on the head web of a scraper. 
     These and other objects, aspects, features and advantages of the invention will become apparent to those skilled in the art upon a reading of the Detailed Description of the invention set forth below taken together with the drawings which will be described in the next section. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention may take physical form in certain parts and arrangement of parts, a preferred embodiment of which will be described in detail and illustrated in the accompanying drawings which form a part hereof and wherein: 
         FIG. 1  shows a top view, partially sectioned, of a scraper connected to a link strand of a double center chain; 
         FIG. 2  shows a sectional view along II-II in  FIG. 1 ; 
         FIG. 3  shows a longitudinal section, partially broken up, through both insertion pockets with inserted and secured horizontal chain links, partially broken up; 
         FIG. 4  shows, in an exploded side view, an insertion pocket, two chain links and a scraper-securing element prior to mounting; 
         FIG. 5  a view of the underside of a half of a scraper according to the invention; 
         FIG. 6  shows a longitudinal section through a scraper according to the invention, partially broken up; 
         FIG. 7  shows a view along VII-VII in  FIG. 6  of a groove in the inside of the scraper wings; and 
         FIG. 8  shows a chain strand of a link chain in which the scrapers according to the invention are preferably used. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings wherein the showings are for the purpose of illustrating preferred and alternative embodiments of the invention only and not for the purpose of limiting same, the scraper generally designated in the figures by  10  is formed for a relatively wide underground high-performance scraper chain conveyor in which a link chain  50  embodied as a double center chain rotates with two link chain strands  51  formed identically to one another for conveying the extraction material, in particular coal. In this case, scrapers  10  according to the invention are in each case connected at a distance from one another to horizontal chain links  52  which have chain fronts  53  with a straight front side  54  as is already easily apparent from  FIG. 1 . 
     Link chain  51  without mounted scrapers is shown in a top view in  FIG. 8  to which reference is made first. In each case two horizontal chain links  52  formed identically to one another with front parts  53  having straight front sides  54  are connected to one another by means of a vertical chain link  60 , which vertical chain link  60  has a constant cross-sectional profile  61  around the full circumference. Cross-sectional profile  61  of vertical chain links  60  is, around the full circumference, provided on its outside with a flat section  62  and embodied on its inside facing an inner opening with a circular arc-shaped camber  63 . Flat section  62  of cross-sectional profile  61  forms a transition in each case via bevels  64  into circular arc-shaped camber  63  and vertical chain links  60  which are generally relatively small engage with inner openings  55  of horizontal chain links  52 . All horizontal chain links  52  have limbs  56  which connect front sections  53  embodied in a rectangular shape on the front side to one another, and limbs  56  are provided on their outside with a recess  57  in which, centrally between both front sections  53 , an entrainment projection  58  protruding into recess  57  is formed with a trapezoidal cross-sectional profile which serves for improved scraper connection by positive-locking entrainment of the scrapers. Link chain  51  with approximately rectangular horizontal chain links  52  and flat vertical chain links  60  is particularly suitable for high-performance scraper chain conveyors since, on the one hand, horizontal chain links  52 , during rotation around a chain wheel, are only subject to low surface pressures with the pockets of the chain wheel and, on the other hand, the articulated play between vertical chain links  60  and horizontal chain links  52  is also improved in particular by bevels  64 , as a result of which the overall wear characteristics of link chain  51  are minimized. The scraper chain shown in  FIG. 8  forms the subject matter of a separate application with the same filing date, to which disclosure reference is made for completion of the present disclosure. 
     The structure of scrapers  10  embodied for connection to horizontal chain links  52  will now be explained with additional reference to  FIG. 2 to 7 . Each scraper  10  has at its lateral ends two scraper wings  1  which are integrally connected to one another by means of a head web  2 . Scraper  10  according to the invention preferably comprises a cast part and front sides  3  of scraper wings  1 , which reach down to underside  8  of scraper  10 , have convex recesses  4  in order to improve the conveying capacity of scrapers  1  according to the invention in operational use. The connection of scrapers  10  to horizontal chain links  52  of double center chain  50  is performed into insertion pockets  5  below head web  2 . Both insertion pockets  5  lying next to one another are herein divided from one another by means of a solid, in cross-section trapezoidal intermediate web  6  whose underside  7  ends flush with underside  8  of scraper wings  1 , as is particularly apparent from  FIG. 6 . In order to reduce the weight of scrapers  10 , both scraper wings  1  are provided with cavities  9  open to underside  8 , which cavities  9  are already preferably provided during original shaping of scraper  10 . Each scraper wing  1  has, below head web  2 , an inside  11  which forms one of both lateral delimitations for insertion pockets  5 . The other lateral delimitation of each insertion pocket  5  is formed by respective outsides  12  of central web  6 . Insides and outsides  11 ,  12  diverge slightly, as a result of which the width of insertion pockets  5  increases towards underside  7  or  8 . For positive-locking anchoring of horizontal chain links  52  having entrainment projections  58  in insertion pockets  5 , grooves  13  and  14  are formed both in insides  11  of scraper wings  1  and in outsides  12  of central web  6 , grooves  13  and  14  protruding upwards substantially from underside  8  of scraper  10  to underside  2 ′ of head web  2 . Grooves  13  provided according to the invention in insides  11  and grooves  14  in the outsides of intermediate web  6  are particularly apparent from  FIGS. 1 ,  4 ,  5  and  7 . Since grooves  13  and  14  run over the entire height of insertion pockets  5 , they extend both across a region in which a scraper-securing element  40  is received in each insertion pocket  5  as well as across the region directly below underside  2 ′ of head web  2  in which limb beds  15  for limbs  56  of horizontal chain links  52  are formed.  FIGS. 3 and 4  show herein the status after and before mounting of horizontal chain link  52  and of scraper-securing element  40  in insertion pockets  5 .  FIG. 3  illustrates that entrainment projections  58  on horizontal limbs  56  extend to groove base  13 ′ or  14 ′ of respective grooves  13 ,  14  such that the scrapers are therefore fixed in a positive-locking manner in the direction of movement of the link chain on horizontal chain links  52 .  FIG. 1  shows the positive-locking engagement of entrainment projections  58  with grooves  13  and  14 .  FIGS. 3 and 4  furthermore illustrate that, between limb beds  15  of each insertion pocket  5 , a conical projection  17  protruding downward across web head  2  is formed, which projection  17  has laterally trough-shaped recesses  18  as a part of limb beds  15 . The front side of the projection which coincides with front side  19  of head web  2  is provided with trough-shaped bearing zones  20  for chain fronts  65  of vertical chain links  60 . Therein, in each case, a bearing zone  20  simultaneously forms a division for both limb beds  15  of an insertion pocket  5  lying next to one another. The relatively flat progression, which is semicircularly cambered across the height of scrapers  10 , of the surface of bearing zones  20  on which the fronts of vertical chain links  60  flattened on the outside bear is particularly clearly apparent from  FIGS. 2 and 5 . 
     Centrally between both bearing zones  20  which lie opposite one another, each insertion pocket  5  is assigned a screw passage  21  passing perpendicularly through head web  2  which, due to projection  17 , reaches relatively far into insertion pocket  5 . On upper side  2 ″ of web head  2 , each screw passage  21  opens into a recess  22  which serves to receive a fixing nut  41 , as  FIGS. 1 and 2  in particular show. Herein, an introduction inclination  23  for a detachment tool opens into each recess  22  in order to detach a potentially rusted-tight nut  41  from shaft  43 ′ of a fixing screw  43  which fixes scraper-securing element  40  and horizontal chain link  52  in insertion pocket  5 . Fixing screw  43  is embodied as a cap screw, in particular a hammerhead screw, whose head  44  engages in a positive-locking manner with a transverse slot  45  on underside  46  of base  47  of scraper-securing element  40  in a rotationally fixed manner, while shaft  43 ′ of fixing screw  43  passes through a bore in scraper-securing element  40  and through screw passage  21  in head web  2 , in order then to be able to screw fixing nut  41  onto shaft  43 ′. 
     As is in turn particularly apparent from  FIGS. 3 and 4 , base  47  of scraper-securing element  40  has, at its upper side, a raised section  48  and, at its transverse sides, in each case a projection  49 . Both projections  49  are substantially adapted in terms of cross-section and width to entrainment projections  58  of horizontal chain links  52  and to the groove geometry of grooves  13 ,  14  so that, in the mounted state, projections  49  can likewise enclose on the transverse sides of scraper-securing element  40  into grooves  13  and  14  on both sides of insertion pockets  5  in order to support inserted horizontal chain link  52  downward over its entire width and prevent tilting movements between horizontal chain link  52  and scraper  10 . Raised section  48  cooperates, in the mounted state of scraper  2 , chain link  52  and scraper-securing element  40 , with projection  17  on the underside of head web  2  and both engage with inner openings  55  of horizontal chain links  52 , as  FIGS. 2 and 3  in particular illustrate. At the same time, limb beds  30  whose geometry is substantially adjusted to the geometry of limb beds  15  on the underside of head web  2  are formed on the upper side of scraper-securing elements  40  together with trough-shaped recesses on both sides of raised section  48 . All limb beds  15  and  30  run out in each case flat to grooves  13 ,  14  or to projections  49  in order to achieve a good interaction and a large-area bearing with limbs  56  of horizontal chain links  52 . 
     The mounting of scrapers  20  on horizontal chain links  52  of the double center chain is particularly facilitated by the positive-locking fixing of screw heads  44  of fixing screws  43  since a tool for tightening or detaching nuts  41  must be put in place exclusively from above without the fixing screw having to be fixed by a locknut from the underside. Mounting can in particular also be performed with an electrical screwdriver. 
     Numerous modifications which should fall within the scope of protection of the attached claims are apparent to the person skilled in the art from the above description. An exemplary embodiment is not represented in which only one scraper-securing element is used to secure both horizontal chain links in the insertion pockets. In the case of such an exemplary embodiment, the central web would only reach to the lower height of the limb beds. An exemplary embodiment is also not shown of the use of a scraper having only one insertion pocket on a single center chain. 
     Further, while considerable emphasis has been placed on the preferred embodiments of the invention illustrated and described herein, it will be appreciated that other embodiments, and equivalences thereof, can be made and that many changes can be made in the preferred embodiments without departing from the principles of the invention. Furthermore, the embodiments described above can be combined to form yet other embodiments of the invention of this application. These combinations include, but are not limited to, combining a tank with an inner vessel arrangement. Accordingly, it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.