Patent Publication Number: US-6901621-B2

Title: Scaling bar

Description:
This patent application claims priority of co-pending U.S. Provisional patent application No. 60/399,252 filed on Jul. 19, 2002 

   FIELD OF THE INVENTION 
   The invention is in the field of scaling bars for use by miners and other workmen to pry loose rocks or other materials from the side wall or roof of a tunnel, mine shafts, or the like. 
   BACKGROUND OF THE INVENTION 
   In galleries of subterranean mines, it often occurs that overhanging loose rocks appear on wall surfaces, for example after the dynamiting of a mine shafts. It is essential to regularly remove these unstable rocks, as a safety precaution against injuries to mine workers. 
   It is known to use scaling bars for this purpose. Such scaling bars are elongated rigid tools comprising a penetrating pick tip at one end thereof, for insertion between unstable rocks. An elbowed section of the rigid tool forms a lever, for enabling a mine worker to dislodge these rocks with reduced physical effort. More particularly, these scaling tools have a cam element adjacent the pick end, to provide extra leverage. However, these known scaling tools are still relatively inefficient. 
   Moreover, scaling bars can be made of a hollow aluminum tube having scaling picks inserts. Such scaling bars, having generally eight feet or more in length can easily be bent out of shape, under the influence of bending strains induced in the aluminum tube while in use. 
   SUMMARY OF THE INVENTION 
   The present invention relates to a scaling bar for prying overhanging rocks from rocky wall structures. The scaling bar comprises an elongated tubular shaft and a first pick member attached to one end thereof, and, optionally, a second pick member attached to a second end thereof. At least one of the two pick members comprises an end portion closely fitted into engagement with the tubular shaft, a tip portion defining a substantially sharp leading edge for easier penetration in the rocky structure, and a cam element. The cam element comprises a first and a second leverage bulges, whereby by displacing the shaft, a lever is formed for dislodging unstable overhanging rocks with minimized physical effort from the workman. The second inner leverage bulge provides greater leverage to the tip portion than the first leverage bulge, but the size of the first leverage bulge is smaller, and can hence engage narrower clefts than the second leverage bulge. In use, a workman axially inserts the pick member of the scaling bar in a cleft adjacent to an unstable overhanging rock, and applies a transverse load by prying the unstable rock using the leverage provided by the first leverage bulge, hence widening the cleft. Subsequently, if necessary, the pick member is further axially driven into the cleft, and the workman again applies a transverse load to pry the rock away again using the leverage provided by the second leverage bulge. This procedure can be repeated so as to sink further into the rock bed, until the rock has been dislodged from its bed. 
   The present invention also relates to a scaling bar, comprising an elongated shaft having opposite first end and second end, a pick member attached to said first end of said elongated shaft, said pick member comprising an outer tip portion and an inner cam member, said cam member comprising a first and a second axially offset leverage bulge, said first leverage bulge being smaller in size than said second leverage bulge; wherein said first leverage bulge is located intermediate said tip portion and said second leverage bulge. 
   Said tip portion of said pick member could be either V-shaped or beveled, hence defining a substantially sharp leading edge; or could be elbowed relative to a lengthwise axis defined by said elongated shaft. A second pick member could also be attached to said second end of said elongated shaft. 
   Preferably, said second pick member comprises an inner end portion anchored to said shaft, an outer V-shaped portion defining a substantially sharp leading edge, and an intermediate arcuate leverage portion integrally mounted to said inner end portion and outer V-shaped tip portion of said second pick member. 
   A flexible core cable could be added, fixedly interconnecting said first and second pick members, said core cable stretched therebetween for attenuating bending moments of force induced in said shaft while said scaling bar is being handled. 
   The present invention also relates to a scaling bar, for use in prying overhanging unstable rocks off a rocky wall structure, comprising an elongated shaft, having opposite first end and second end, a pick member attached to said first end of said elongated shaft, said pick member comprising an outer tip portion defining a substantially sharp leading edge for easing axial driving of said pick member in the rocky wall structure, and an inner cam member, said cam member comprising a first leverage means and a second leverage means, said first leverage means providing greater leverage to said tip portion than said second leverage means. 
   Reinforcement means could then fixedly interconnect first pick member and second pick members, for attenuating bending moments of force induced in said shaft while said scaling bar is being handled. 
   The present invention also relates to a portable prying tool for use by miners on mineshaft walls, said prying tool including:
         a handle;   a driving head, attached to said handle, said driving head for engagement through small wall cavities on the mineshaft walls;   first cam means, co-operating with said handle for providing fine-grade leverage force to increase the penetration depth of said driving head into the wall cavities of the mineshaft walls; and   second cam means, co-operating with said handle and with said first cam means for providing coarse-grade leverage force to further increase penetration depth of said driving head into the wall cavities of the mineshaft walls, beyond that enabled by said first cam means.       

   A second driving head could be added, integral to said handle at a location spacedly opposite the first mentioned driving head. 
   Preferably, third cam means is added, co-operating with said handle for providing fine-grade leverage force to increase the penetration depth of said second driving head into the wall cavities of the mineshaft walls, and fourth cam means is added, co-operating with said handle and with said third cam means for providing coarse-grade leverage force to further increase penetration depth of said second driving head into the wall cavities of the mineshaft walls, beyond that enabled by said third cam means. 
   Said first mentioned driving head and said second driving head could be coaxially mounted, with a flexible tensioning member being added, fixedly spacedly interconnecting said second driving head and the first mentioned driving head. 
   Said tensioning member could either extend coaxially to said first mentioned driving head and to said second driving head, or alternately, could define a lengthwise axis being axially offset relative to said first mentioned driving head and to said second driving head but parallel thereto. 

   
     DESCRIPTION OF THE DRAWINGS 
     In the annexed drawings: 
       FIG. 1  is a perspective view of a scaling bar according to prior art; 
       FIG. 2  is an enlarged top plan view of the scaling bar of  FIG. 1 , shown partly broken for clarity of the view; 
       FIG. 3  is a view similar to  FIG. 2 , but with the bar tilted a quarter of a turn; 
       FIG. 4  is a view similar to  FIG. 3 , but showing a sectional view of one end portion of the bar; 
       FIG. 5  is a perspective view of a scaling bar according to a first embodiment of the invention; 
       FIG. 6  is a top plan view at an enlarged scale of the scaling bar of  FIG. 5 , shown partly broken for clarity of the view; 
       FIG. 7  is a view similar to  FIG. 6 , but with the bar tilted a quarter of a turn; 
       FIG. 8  is a view similar to  FIG. 7 , but showing a structural integrity enhancing cable mount; 
       FIG. 9  is a perspective view of a scaling bar according to a second embodiment of the invention; 
       FIG. 10  is an enlarged top plan view of the scaling bar of  FIG. 9 , broken at its mid portion to fit the sheet window; 
       FIG. 11  is a view similar to  FIG. 10 , but with the bar tilted a quarter of a turn; and 
       FIG. 12  is a view similar to  FIG. 11 , but showing one end portion of the bar in sectional view, and further showing an alternate structural integrity enhancing cable mount. 
   

   DETAILED DESCRIPTION OF THE EMBODIMENTS 
     FIGS. 1  to  4  show a scaling bar  1  according to prior art. Scaling bar  1  comprises two pick ends  3  and  4  installed on opposite ends of a shaft  2 . Pick end  3  is V-shaped and defines a leading edge  3 ′. Pick end  4  comprises a V-shaped tip portion  4   a  defining a leading edge  4 ′, an elbow  4   b,  and a straight end portion  4   c.    
   With further reference to  FIG. 5 , a scaling bar  10  is illustrated according to a first embodiment of the present invention. Scaling bar  10  is used for dislodging hazardous loose rocks clung on to wall structures of mine shafts, which, if not removed, can unexpectedly fall on miners or other workmen, hence causing serious bodily injuries. 
   Scaling bar  10  comprises an elongated shaft  12  having a pick member  14  firmly attached coaxially to one end thereof, and a pick member  20  fixedly attached coaxially to the other end thereof. 
   Shaft  12  can be for example an aluminum hollow tube having a circular or polygonal (e.g. quadrangular) cross-section, and can have varying lengths. The length of shaft  12  could vary for example between 8 to 14 feet. Opposite pick members  14  and  20  should be made from a much stronger material relative to shaft tube  12 , for example from heavycast iron alloy. 
   As illustrated in  FIG. 7 , pick member  14  comprises the following integral elements : a straight inner portion  16 , an elbowed outer tip portion  17  and an inner cam member  15  integrally projecting outwardly radially from inner portion  16 . Straight portion  16  is aligned coaxially with shaft  12 , and can for example have an hexagonal cross-section. Elbowed tip portion  17  extends from the outer end of straight portion  16 ; the elbow angle of elbowed tip portion  17  is acute, for example ranging between 30° to 45° Tip portion  17  is V-shaped, hence defining a substantially sharp leading edge  17 ′ for better insertion in clefts present into rocky wall structures. Moreover, cam member  15  is provided on pick member  14 , cam member  15  integrally projecting radially outwardly from inner portion  16 . Cam member  15  is used as leverage means for prying away loose rocks from wall structures of mine shafts. Cam member  15  comprises two leverage bulges  15   a  and  15   b  which are separated by a recess  15   c.  The size of bulge  15   b,  located on the outer end of straight portion  16  adjacent to tip portion  17 , should be significantly smaller than that of bulge  15   a,  which is located on the inner end of straight portion  16  opposite tip portion  17 . For example, outer bulge  15   b  could increase by 50% the diameter of straight portion  16 , and inner bulge  15   a  by 100%. Other relative sizes of bulges  15   a  and  15   b  are not excluded from the scope of the invention. Bulges  15   a  and  15   b  have a substantially semi-circular cross-section. Cam element  15  may comprise two opposite planar faces  15 ′,  15 ″ parallel to the central axis of elongated shaft  12 , as illustrated in FIG.  6 . 
   As illustrated in  FIG. 7 , the geometry of the two opposite pick members  16  and  23  is very similar. Both pick members  16  and  23  comprise similar straight portions  16  and  22  respectively, and similar cam members  15  and  21  respectively. However, tip portion  23  of pick member  20  differs from tip portion  17  of pick member  14 . Tip portion  23  is a non-elbowed coaxial beveled extension of straight portion  22 . A beveled face  23 ″ is defined on tip portion  23 , and is sloped downwardly opposite cam member  23 . Beveled tip portion  23  thus defines a substantially sharp leading edge  23 ′, and thereby allowing an easier through insertion of pick member  20  in clefts present in mine shaft walls. 
   In one embodiment, as illustrated in  FIG. 8 , straight portions  16  and  22  of pick members  14  and  20  respectively are inserted within the inner periphery of tubular shaft  12  and suitably firmly attached thereto, by means of rivets, screws and bolts, welding, press fitting, or other suitable means known in the art. 
   In  FIG. 9 , there is shown an alternate embodiment of the scaling bar of the invention, which will be further referred to as scaling bar  110 . Scaling bar  110  comprises an elongated shaft  112  similar to shaft  12  of scaling bar  10 , and two pick members  114  and  120  firmly attached to opposite ends of shaft  112 . 
   As illustrated in  FIGS. 11 and 12 , pick member  114  comprises an inner end portion  116 , an intermediate elbowed arcuate portion  115 , and an outer tip portion  117  coextensive to one another. Leverage portion  115  is meant to abut on the wall structure (side wall or roof) of a mine shaft or the like as leverage means for prying away loose rocks clinging thereon and allowing these rocks to fall down in a controlled way not hazardous to coworkers. Tip portion  117  is V-shaped, hence defining a leading edge  117 ′ for easier insertion in clefts on a wall structure of a mine shaft. 
   In one embodiment, as shown in  FIG. 12 , end portion  116  of pick member  114  comprises an inner straight portion  116   a  and an arcuately elbowed intermediate portion  116   b.  Straight portion  116   a  is closely fitted into engagement through a tube mouth  112   a  and into the inner peripheral wall of tubular shaft  112 , and is firmly secured thereto with screws, rivets, or other suitable means known in the art. 
   Pick member  120  has a very similar geometry to that of pick member  20 . It comprises a cam member  121  identical to cam member  21 , and a straight portion  122  identical to straight portion  22 . However, it comprises a V-shaped (double-bevel) tip portion, hence defining a substantially sharp leading edge  123 ′ aligned coaxially with shaft  112 . 
   In alternate embodiments, as displayed in  FIGS. 8 and 12 , provision has been made for a core cable  100 ,  200  respectively reinforcing tubular shafts  12 ,  112  respectively, and joining pick members  14  and  20 ,  114  and  120  together respectively. As illustrated in  FIG. 8 , core cable  100  having opposite threaded end portions  100   a,    100   b,  is installed on tubular shaft  12  in axially offset fashion parallel thereto, in a diametrically opposite fashion relative to cam member  15 . More specifically, core cable end portions  100   a,    100   b  are each inserted through threaded channel  26  located in a supporting member  25 , the latter being integrally mounted on both pick members  14  and  20  radially outwardly thereof. Core cable  100  is suitably secured therewith by means of nuts screwed onto its threaded end portions  100   a,    100   b.  Alternatively, as illustrated in  FIG. 12 , core cable  100  can be installed coaxially with and within the inner walls of tubular shaft  112 . The opposite threaded end portions  200   a  of core cable  200  engage a threaded socket  202  recessed into the end portion of pick members  114  and  120  located within the inside of tubular shaft  112 . 
   In both configuration of  FIGS. 8 and 12 , core cable  100 ,  200  strongly pulls and maintains together pick members  14  and  20  and pick members  114  and  120  respectively, so as to substantially relieve structurally weaker but much lighter tubular body  112  from bending moment of forces. Core cables  100 ,  200  are particularly useful for scaling bars in the high end of operational lengths, for example from 12 to 14 feet in length. 
   Scaling bar  10  or  110  is generally used to dislodge loose overhanging rocks that often appear on wall surfaces after the dynamiting of mine shafts. The following description will depict the usage of pick member  14  of scaling bar  10  exclusively, for clarity purposes; pick member  20  of scaling bar  10  and pick member  120  of scaling bar  110  are meant to be used in a similar fashion. Bulge  15   a  and  15   b  of cam member  15  provide leverage for the tip portion  17 , hence rendering the dislodging of the loose rock less physically demanding on the workman maneuvering scaling bar  10 . Bulge  15   b  being bigger than bulge  15   a,  the former provides greater leverage than the latter. In practice, tip portion  17  followed by bulge  15   a  are first axially inserted in a cleft too narrow for bulge  15   b  to be inserted therein as well. Transverse lever pressure is then applied on the shaft to try to pry the loose rock out of its bed and widen the cleft. If necessary, the pick member can then be further axially driven into the cleft, allowing for bulge  15   b  to penetrate therein as well. Transverse lever pressure is then applied on the shaft once again to pry the loose rock further out of it bed. This procedure can be repeated at different locations around the loose rock to fully pry it away from the wall surface, allowing it to cling off the wall of the mine shaft and to fall on the ground. 
   It has been found that unexpectedly high performance was achieved with elbowed tip portions  17 ,  117 , due to the specific elbow shape, compared to conventional crow bar having an elongated handle. 
   Returning to the prior art scaling bar  1 , illustrated in  FIGS. 1 through 4 , elbow  4   b  located onto pick end  4  provides leverage to the tip portion  4   c.  However, such leverage means have been found to be quite inefficient. The double-bulged cam member  15 ,  21 ,  121  located on the pick members of the scaling bars of the present invention have also unexpectedly been found to provide much more efficient leverage means to the adjacent tip portion. 
   The different shapes of pick members described hereinabove provide miners or other workmen a plurality of different tools for prying away loose rocks embedded in a wall structure. Each scaling bar  10 ,  110  being provided with two opposite pick members, the workman can, by tilting the scaling bar one half turn, alternate between both pick members while scaling a mine shaft wall structure. In one embodiment, pick members are releasably mounted to the tubular body  12 ,  112 , allowing for them to be interchangeable, adding a modular capacity to the scaling bar of the invention which enhances the versatility of the tool  10 ,  110 . 
   In an embodiment of the invention not shown in the appended figures, the scaling bar could include only one end pick member, this pick member being shaped similarly to pick member  14 ,  20  or  120 , and hence comprising a double-bulged camel-back-like cam element. 
   In use, shaft  12  or  112  may withstand a great deal of transverse bending moments of force. In the embodiments illustrated in both  FIGS. 8 and 12  wherein a core cable  100  is installed on shaft  12  or  112 , core cables  100 ,  200  attenuate bending loads resulting from lever prying rocks off hard wall structures. Indeed, core cables  100 ,  200  being strongly stretched between the two pick members, if bending loads are induced in the shaft, the shaft will spring back to its original conformation under the bias of the stretched cable  100 ,  200 . Cables  100 ,  200  should be made from a material much stronger than tube  12 ,  112 , but also flexible, contrary to the end pick members, for example metallic flexible cable. 
   In an alternate embodiment, a metallic rod (not shown) can be used instead of a core cable to help preventing excessive warping due to bending loads. 
   Note that various other configurations of scaling bars could come within the scope of the current invention. FIG.  5  and  FIG. 8  represent two distinct embodiments of the scaling bar. However, any one of the above described pick members can be assembled with any other of the pick members on a tubular shaft, yielding a variety of different scaling bars. For each or these scaling bars, provision can be made for an external flexible core cable  100 , or an internal flexible cable  200 , which may be located inside or radially outside the tubular shaft, as described hereinabove.