Patent Publication Number: US-9422138-B2

Title: Arrangement for damping oscillation of loading member in crane

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to an arrangement for damping oscillation of a loading member in a crane comprising a trolley, a hoisting mechanism provided in the trolley, hoisting ropes suspended from the hoisting mechanism, a loading member fastened to the hoisting ropes, the arrangement for damping oscillation of a loading member comprising a vertical guide projection arranged in an upper part of the loading member, and damping members arranged in the trolley and including a guide part receiving the guide projection of the loading member. 
     Acceleration and deceleration of a crane are mainly responsible for oscillations of a loading member of the crane. This oscillation may be minimized by driving the crane at a constant speed or sufficiently slowly. Research abounds for damping or eliminating oscillations of a loading member of a crane and a load fastened thereto by using various computer programs or speed control methods, e.g. in U.S. Pat. No. 5,219,420. In some cases, particularly in container cranes, oscillation has been suppressed by means of auxiliary ropes and auxiliary drums, cf. for instance U.S. Pat. Nos. 5,769,250 and 7,287,740 as well as DE Patent 1207578. In many applications also pneumatic or hydraulic dampers are used, cf. for instance GB Patent 1542821. However, when using process cranes in connection with heavy loads, such as vacuum hoists including loading members suspended therefrom, the cranes have to be driven at high speeds required by the course of the process. When the commodity to be moved is then e.g. paper or a corresponding product, it is at high risk of being damaged if the liquids used in the crane leak to the product being moved. 
     U.S. Pat. No. 5,165,556, in turn, describes a device for damping oscillation of a loading member, comprising downward-pointing brackets attached to the bottom of a trolley. A load is lifted in place between these brackets, and the load is retained rigidly in place while driving the crane, whereby oscillation of the loading member and the load attached thereto is prevented. Such damping systems are expensive, and they require a lot of material and space. The damping of this type has a further disadvantage in that when the loading member is lifted at a high speed between the brackets, a gap formed by the brackets for the loading member has to be wide, which may lead to post-oscillations between the brackets. When the loading member has then been supported rigidly between the brackets, accelerations of the trolley directly influence the load attached to the hoisting member. This may lead to malfunction or increased risk of collision, particularly when handling large paper rolls, for instance, when the rolls are kept in place by means of a vacuum hoist. 
     From JP 08268682 A and KR 20010057393 A, centering of a loading member to a trolley of a crane by means of conical surfaces is known. Therein, a conical loading member centering piece is mounted immovably in the trolley. In the first-mentioned publication, the conical surface of the loading member simultaneously serves as a damper. 
     DE 10105261 A1 also discloses centering and interlocking means between a loading member and a trolley as well as vertical damping means provided in the trolley for damping a centering event. 
     In SU 502830 A1, a load is lifted into a tube downwardly extending from a trolley, wherein the load is supported laterally in the tube by means of suspended wheels provided at ends of lever arms. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to eliminate the disadvantages of the above-described prior art and to provide an advantageous solution to the problem. This object is achieved by an arrangement according to the invention, which is mainly characterized in that the damping means are arranged in a separate support frame which, in a hoisting direction of the loading member, is guidable into its place in a dock arranged underneath the trolley and which is lowerable off the dock, onto the loading member, the guide part is a floating guide tube structure, the damping members comprising a plurality of side damping modules connected between a side wall of the guide tube structure and the support frame, around the guide tube structure, for substantially damping horizontal movement of the guide tube structure, and a joint which is arranged in an upper part of the support frame and from which the guide tube structure is suspended. 
     Compared with previous solutions, the solution according to the invention takes little space and it may be installed between hoisting ropes located about one meter apart from one another. The arrangement may be applied in connection with various loading members since its guide projection is mounted at the centre of the loading member. The arrangement may be implemented by a simple welded structure wherein the number of various fastening members may be minimized. The structure is modular, enabling its components to be changed as necessary and required. The loading member may be lifted at a high speed to the guide tube structure. The elasticity of the damping arrangement reduces stresses of the trolley and makes loads safer to hoist and transport. The support frame is easy to detach from the dock and lower onto the loading member for service, for instance. Consequently, no service plane as such has to be provided in the trolley for the damping arrangement, either. 
    
    
     
       LIST OF FIGURES 
       The invention is now be described in closer detail by means of its preferred embodiments and with reference to the accompanying drawings, in which: 
         FIG. 1  is a side view showing a crane and an arrangement according to the invention when the crane starts moving or accelerates to the right; 
         FIG. 2  is a side view showing a crane and the arrangement according to the invention when the crane further moves to the right but starts to decelerate or stop; 
         FIG. 3  shows the arrangement according to  FIGS. 1 and 2  on a larger scale; 
         FIG. 4  shows the arrangement according to  FIG. 3  but with a support frame of damping members being lowered onto a loading member; 
         FIG. 5  shows a dock and a support frame as seen from below; 
         FIG. 6  shows another embodiment of a dock and a support frame as seen from below; 
         FIG. 7  shows damping members in closer detail; 
         FIG. 8  is a perspective view showing an implementation of a guide projection of a loading member and a guide part receiving the same; 
         FIG. 9  is a perspective view showing another implementation of a guide projection of a loading member and a guide part receiving the same; 
         FIG. 10  shows an alternative support joint of a guide tube structure; 
         FIG. 11  shows another alternative support joint of a guide tube structure; 
         FIG. 12  shows yet another alternative support joint of a guide tube structure; 
         FIG. 13  shows an implementation of a side damping module; 
         FIG. 14  shows another implementation of a side damping module; and 
         FIG. 15  shows an alternative for fastening a dock to a trolley. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     First referring to  FIGS. 1 and 2 , a crane  1  is shown which is provided with an arrangement according to the invention for damping oscillation of a loading member  5 . The crane  1  comprises a trolley  2 , a hoisting mechanism  3  arranged in the trolley  2 , hoisting ropes  4  suspended from the hoisting mechanism  3 , and the loading member  5  fastened to the hoisting ropes  4 . Resting on its wheels  7 , the trolley  2  moves along end supports  6  of the crane  1 . The end supports  6  are connected to ends  6   b  of the crane  1 , the ends  6   b  in turn moving along load-bearing structures  8  of a site of the crane  1 . A load attached to the loading member  5  is designated by reference number  9 . The loading member  5  shown herein is typically a vacuum hoist. 
     Referring further to the rest of the figures of the drawings, the arrangement for damping oscillation of the loading member  5  and, depending on the load of the loading member  5 , also of the load  9  fastened thereto, comprises a vertical guide projection  10 ;  110  arranged in an upper part of the loading member  5  and damping members (to be described next) arranged in the trolley  2  and including as one part a guide part  11 ;  110  for receiving the guide projection  10 ;  100  of the loading member  5 . 
     One essential feature of the invention is that the damping means are arranged in a separate support frame  12  guidable in a hoisting direction of the hoisting member  5  into its place in a dock  13  arranged underneath the trolley  2  and lowerable off the dock  13 , onto the loading member  5 . 
     It is also essential that the guide part  11 ;  110  is a floating guide tube structure  11 ;  110 , whereby the damping members comprise a plurality of side damping modules  14  connected between a side wall of the guide tube structure  11 ;  110  and the support frame  12 , around the guide tube structure  11 ;  110  for substantially damping horizontal movement of the guide tube structure  11 ;  110 , and a support joint  15 ;  150 ;  350 ;  450  which is arranged in an upper part of the support frame  12  and which is advantageously damped and from which the guide tube structure  11 ;  110  is suspended. 
     A horizontal position of at least one of the support frame  12  and the dock  13  is adjustable so as to enable the guide projection  10 ;  110  and the guide tube structure  11 ;  110  to be brought into the same vertical line. 
     Preferably, the dock  13  is fastened to a support framework  36  provided between two transverse load beams  16  of the trolley  2 , wherein the position of the dock  13  is adjustable in the longitudinal and transverse direction of the trolley  2 . 
     Alternatively, according to  FIG. 15 , the dock  13  is fastened to one transverse load beam  16  of the trolley  2 , wherein the position of the dock  13  is adjustable also in those directions. Also the support frame  12  may in the dock  13  be adjustable in the longitudinal direction of the trolley  2  along rails (not shown) appropriately arranged in the dock  13 , for instance. 
     The dock  13  is provided with vertical slide bars  17  and the support frame  12  is provided with slide blocks  18  in co-operation therewith for lowering the support frame  12  from the dock  13  and for guiding it back in to the dock  13 . Consequently, the support frame  12  is at its lower part further provided with bottom stoppers  19  abutting against the lower part of the dock  13  for restricting the upward movement thereof, and interlocking devices  20  clamping an upper part of the dock  13  for fastening the support frame  12  to the dock  13 . 
     In the described examples, the support frame  12  and the dock  13 , when viewed from above, are rectangular structures, so when arranged one within the other, they may be located such that their sides are parallel, as in  FIG. 5 , or such that the corners of the support frame  12  reside at the centre of the sides of the dock  13 , as in  FIG. 6 . The solution according to  FIG. 5  saves space but in the solution according to  FIG. 6  the side damping modules  14  may be easier to arrange. The support frame  12  and the dock  13  are herein described as an open “lattice structure”, but closed or partly closed box structures are also possible. 
     Referring to  FIGS. 3, 7, and 8  in particular, the guide projection  10  comprises an end projection  21  whose lower end is fastened to the loading member  5 , between two hoisting ropes  4 , a tapering projection guide surface  22  protruding upwards from an upper end of the end projection  21 , and a guide pin  23  which extends upwards from this projection guide surface  22  and whose diameter is considerably smaller than the diameter of the end projection  21 . Similarly, the guide tube structure  11  comprises an end tube  24  guide projection  10  for receiving the end projection  21 , whereby a downwards expanding guide hem  25  extends from a lower edge of the end tube  24  and whereby an upper end of the end tube  24  is provided with an upwards tapering inner guide surface  26  and an upper tube  27  which extends upwards from the inner guide surface  26  and receives the guide pin  23  and into which the guide pin  23  of the guide projection  10  fits with a loose fitting. 
     Most preferably, the end projection  21  and the guide pin  23  of the guide projection  10  as well as the end tube  24  and the upper tube  27  of the guide tube structure  11  are cylindrical while the projection guide surface  22 , the guide hem  25  and the inner guide surface  27  are conical. 
     Alternatively, according to  FIG. 9 , an end projection  210  and a guide pin  230  of a guide projection  100  as well as an end tube  240  and an upper tube  270  of a guide tube structure  110  may have an angular, preferably square, cross-section, while a projection guide surface  220 , a guide hem  250  and an inner guide surface  260  are angular cones. 
     In the structure shown in  FIG. 7 , the support joint  15  connected to the upper tube  27  of the guide tube structure  11  is arranged in a damping chamber  28  provided in the upper part of the support frame  12 , the support joint  15  comprising a support structure  29 , such as a plate-sleeve structure shown in the figure, arranged around the upper tube  27  of the guide tube structure  11 , and vertical damping elements  30  which are made of an appropriate elastic yet sufficiently robust material capable of carrying the entire guide tube structure  11  floatingly and which are arranged in the damping chamber  28 , above and under the support structure  29 . In order to ensure that the guide tube structure  11  and the support structure  29  stay in the position designed therefor, an upper end of the upper tube  27  may be provided with a through hole  31  capable of receiving a suitable retainer pin (not shown). 
       FIG. 10  shows a simpler support joint  150  comprising a ball joint  151  fastened to the upper end of the upper tube  27  of the guide tube structure  11 . The ball joint  151  is supported against the support frame  12  by means of interlocking plates  152  and  153  provided above and below it. The interlocking plates  152  and  153  are provided with incisions  154  and  155  for the ball joint  150 . In order to provide the guide tube structure  11  with vertical elasticity, a vertical damping material  157  is applied between the support frame  12 , the lower interlocking plate  152  and fastening bolts  156  thereof. 
       FIG. 11  shows another support joint solution comprising a gyroscopic swing  350  including its damping members  351  arranged in an upper end of the guide tube structure  11 . 
       FIG. 12  shows yet another support joint solution wherein a support plate  451  is mounted in the support frame  12 , the support joint comprising helical springs  450  arranged between this support plate  451  and the upper end of the guide tube structure  11 . 
     As shown by  FIGS. 7, 13, and 14  in particular, the side damping modules  14  comprise a tubular body  33  and at least one elastic element  34 ,  134  or  234  and  235  mounted therein. 
     In  FIG. 7 , the elastic element  34  is shown as a schematic view, in  FIG. 13  the elastic element comprises a helical spring  134  (or more if necessary), and in  FIG. 14  cup springs  234  and a rubber damper  235 . When necessary, these elastic elements may be prestressed. 
     The described side damping modules  14  may be provided in one or two layers, each layer comprising 3 to 5 such modules. The drawings describe a “single-layer” solution. 
     The above description of the invention is only intended to illustrate the basic idea of the invention. A person skilled in the art may thus vary its details within the scope of the accompanying claims.