Abstract:
A method for making a stone article includes the steps of providing a block of material having substantially square top and bottom surfaces, impacting the top and bottom surfaces with a non-square blade so as to split off-excess material from the top and bottom surfaces and provide said surfaces with a shape substantially matching the non-square blade cutting a cylindrical cut into said top surface, drilling a hole into the bottom surface, and applying a force into the hole whereby a stone portion within the cylindrical cut is removed from the block of material. A stone polishing apparatus is also provided.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This application is a continuation-in-part of co-pending application Ser. No. 60/423,629 filed Nov. 1, 2002. 

   BACKGROUND OF THE INVENTION 
   The invention relates to stone cutting and polishing and, more particularly, to methods for cutting stone to produce useful articles such as planters, vases and the like, and to methods and an apparatus for polishing certain surfaces of same. 
   Stone planters and vases are decorative articles for which there is a demand. Such articles are frequently made from stone, especially granite. 
   Starting granite raw material for such articles is typically in the form of a square or a substantially rectangular block of granite. In the course of providing a planter or vase from such an article, a rounded outer appearance and a hollow center section are typically desired. Conventional methods for providing such structures are time consuming. Furthermore, following conventional methods, the central portion removed from the block to form the planter or vase is typically destroyed and/or wasted. 
   It is clear that the need remains for improved methods for providing articles such as planters and vases from substantially square or rectangular blocks of stone, especially granite. It is therefore the primary object of the present invention to provide such methods. 
   It is a further object of the present invention to provide such a method wherein far less starting material is wasted. 
   It is still another object of the present invention to provide a method and apparatus for polishing the outside surface of cylindrical or accurate outer-shaped stone articles to enhance the appearance of same. 
   SUMMARY OF THE INVENTION 
   In accordance with the present invention, the foregoing objects and advantages have been readily attained. 
   According to the invention, methods are provided for providing an rounded outer surface on a substantially rectangular or square block of stone such as granite, for removing a substantially cylindrical central portion from the block of granite, for removing a smaller substantially cylindrical portion from the originally removed cylindrical portion so as to provide yet another useful article such as a planter or vase, and for polishing the cylindrical outer surfaces of central portions removed in the course of these methods. 
   These methods and apparatus advantageously provide for simpler and faster provision of the original planter or vase to be provided from the starting material, and also provide for the fabrication of useful and desirable articles from the central portions removed such that very little starting material is wasted, particularly as compared to conventional processes. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A detailed description of preferred embodiments of the present invention follows, with reference to the attached drawings, wherein: 
       FIG. 1  illustrates an initial step of the present invention wherein corners are removed from a square block of material; 
       FIG. 2  illustrates the resulting product of the step illustrated in  FIG. 1 ; 
       FIG. 3  illustrates a block of material with the corners having been removed and having a core drilled into one side and a hole drilled into the other side; 
       FIG. 4  illustrates removal of the central core from the block of material of  FIG. 3 ; 
       FIG. 4A  is a side view illustrating a further aspect of the step of removing the core from the block; 
       FIG. 5  illustrates further treatment of the core material removed in  FIG. 4 ; and 
       FIG. 6  illustrates an apparatus for polishing outer cylindrical surfaces of a stone object in accordance with the present invention. 
   

   DETAILED DESCRIPTION 
   The invention relates to stone cutting methods and, more particularly, to a method for treating a block of granite so as to form rounded outer surfaces on the block, and so as to remove a substantially cylindrical-shaped central portion from the block, so as to provide a planter or vase or other useful articles as desired. 
   Furthermore, the invention is drawn to methods for polishing the outer cylindrical surface of the central portion so removed, and/or for removing a smaller central portion from the originally removed central portion so as to provide a further planter, vase or the like, and this method can be repeated until the removed central portion is too small to be of any use. In this manner, and advantageously, a plurality of useful articles are provided from a single block of granite, each of which is appealing to consumers, far less material is wasted, and the resulting products are provided in a simpler, less time-consuming and more cost-effective manner. 
     FIG. 1  shows a block of granite  10  in substantially rectangular form having a top surface  12 , a bottom surface  14  and sides  16 . A typical size for such a block of granite to be used in accordance with the present invention would be between about 5 and about 14 inches in height and between about 2 and about 12 inches in width. Of course, other size blocks of granite can be used as starting material as well. 
   In many applications, the first step is to provide rounded top and bottom surfaces, and conventionally this is done through various manual procedures and is very time consuming. 
   In accordance with the present invention, it has been found that a rounded top  12  and rounded bottom  14  can be provided by impacting or pressuring surfaces  12 ,  14  with a blade having the desired shape, typically a round cross section to provide a rounded top, and it has been found advantageously that impacting surface  12  with a blade  18  such as is shown in  FIG. 1  advantageously serves to split away corners of the block as desired. 
   In accordance with the present invention blade  18  can advantageously be a hardened carbide or steel pipe or other structure, preferably provided having a hardened and/or sharpened end. This advantageously pressure-splits the top corner edges off of top surface  12  to provide a block  20  ( FIG. 2 ) having a rounded top surface  22 . 
   In accordance with the invention, block  20  can then be flipped over and the same process performed on bottom surface  14  as desired. Alternatively, block  10  from  FIG. 1  can be treated on both top and bottom surfaces  12 ,  14  with two blades  18  so as to provide rounded top and bottom surfaces substantially simultaneously. 
   In accordance with a further aspect of the present invention, a method is provided for removing a substantially cylindrical center portion of the block of granite so as to provide an article suitable for use as a planter, vase and the like. 
     FIG. 3  shows a starting block of material  24  with the cylindrical centerpiece  26  marked in dashed lines. This cylindrical centerpiece  26  is to be removed from block  24  in accordance with the present invention. 
   Conventionally, centerpiece portion  26  would be removed through chiseling, grinding and other time-consuming processes which also would tend to destroy the actual portion being removed. In accordance with the present invention, portion  26  is removed by first cutting a cylindrical cut into top surface  28  of block  24  and to a desired depth within block  24 . This cut can be formed using a stone core drill or the like, and is advantageously made in the direction of the grain or rift of the block. The depth of the cut is preferably made to within about 0.5 and about 1.5 inches of bottom surface  30  of block  24 . A hole  32  is then drilled into bottom surface  30  of block  24  preferably having a diameter of between about 0.5 and about 1 inches, and preferably in the center of bottom surface  30  substantially as shown. This hole is preferably drilled to a depth of between about 0.5 and about 1.5 inches, and further preferably to approximately the same depth as a distance between the end of the cylindrical cut from face  28  and surface  30 . Hole  32  may be drilled prior to the cylindrical cut as well. 
   Block  24  is then advantageously supported, preferably around edges  34  of top surface  28 , and a shaft or other suitable member is positioned in hole  32  to which pressure or an impact are applied. This can be done with a hydraulic press and/or a large hammer or any other suitable device, and this impact or pressure advantageously serves to fracture off the bottom portion of central portion  26  from the remainder of block  24  and drives central portion  26  out of block  24 , against the grain of the material, so as to provide a final article having a hollowed central portion which is suitable for use as a planter, wine cooler, lamp, vase and the like. 
   It should be appreciated that this method provides the final article as illustrated in  FIG. 4  in a far less time consuming manner than conventionally can be accomplished. Furthermore, this method provides central portion  26  in a substantially cylindrical and intact form, and this material itself can be used to provide further articles. 
     FIG. 4A  illustrates a preferred embodiment of the pressure or impacting step which is utilized to remove the cylindrical portion  26  from block  24 . As shown in  FIG. 4A , shaft  25  which is to be used to impact the base of hole  32  is advantageously provided with a surrounding shock-absorbing member such as a spring  27 . When shaft  25  is positioned within hole  32 , spring  27  is compressed between a cuff  29  on shaft  25  and the bottom surface  30  of block  24 . This biasing or spring member advantageously serves to absorb much of the shock which typically occurs when cylindrical portion  26  fractures free of the remainder of block  24 . This is particularly desirable since, without spring  27 , block  24  can be violently moved upon fracturing out of central portion  26  which can result in undesirable chips or fractures of different edges of block  24 . Thus, in accordance with a preferred embodiment of the present invention, spring or other impact-absorbing means  27  is provided between affixed portion of shaft  25  and the surface of block  24  to absorb this shock as described above. 
   Turning to  FIG. 5 , central or centerpiece portion  26  itself can then be treated to provide a cylindrical cut  36 , and a hole  38  can be drilled from the bottom surface  39  of centerpiece portion  26 , and centerpiece portion  40  can thereby advantageously be removed following the same procedure as described above in connection with  FIGS. 3 and 4 . This procedure can be repeated as many times as are allowed by the decreasing size of the central portion removed from each successive piece of granite. In this manner, many articles can be prepared from the original piece of material, with far less waste. 
   It should be appreciated that the original article formed, as shown in  FIG. 4 , has a rough exterior surface with natural finish, which is desirable to consumers. It should also be appreciated that the products fabricated from removed cylindrical portions, or second, third, etc. generation products, have a substantially smooth cylindrical outside surface which can advantageously be flame finished, polished or sand blasted so as to provide them with a decorative and desirable finish. 
   Turning now to  FIG. 6 , an apparatus  50  in accordance with the present invention is illustrated. According to the invention, apparatus  50  has two main portions or assemblies. The first is the workpiece holding and moving assembly  52  which is advantageously adapted to hold a workpiece such as a cylindrical piece of granite  54  to be polished, and for moving workpiece  54  up and down as required, and also for rotating workpiece  54 . The second main assembly of apparatus  50  in accordance with the present invention is a polishing head assembly  56  which advantageously serves to rotate different bricks or diamond pads or other type of polishing media, typically having different coarseness or grit, against workpiece  54 . 
   As shown in  FIG. 6 , assembly  52  may advantageously include a base portion  58 , and assembly  60  for providing vertical motion, and holding members  62  adapted to releasably hold workpiece  54  in a rotatable fashion. With these components, workpiece  54  can be mounted between elements  62  and vertically positioned through assembly  60 , while simultaneously being rotated around a vertical axis by rotation of elements  62 . To this end, a motor such as a 10 HP variable speed motor  64  can advantageously be communicated or operatively associated with element  62  to rotate same, and this motor may advantageously be mounted on a substantially horizontal brace  66  which may also advantageously serve to rotatably support one element  62  for holding workpiece  54  as discussed above. 
   A further horizontal member  68  is provided, substantially parallel to horizontal member  66 , and rotatably supports the other element  62  for holding workpiece  54 . Horizontal members  66 ,  68  are advantageously vertically slidably mounted relative to guide members  70 ,  72 , and are operatively associated with a threaded sleeve  74  which is preferably engaged with a threaded rod  76  which is driven by a motor  78  such as a 1½ HP motor, typically through a gear reducer such as a 60 XI gear reducer, for rotating threaded rod  76  within sleeve  74  so as to move horizontal support members  66 ,  68  vertically relative to support members  70 ,  72 . 
   It should be appreciated that motor  64  can advantageously be associated with elements  62  for driving same through a pulley assembly  80  as illustrated, or through any other suitable mechanism. 
   Furthermore, an air cylinder  82  may advantageously be provided for holding lower element  62  relative to workpiece  54  and allowing for opening of elements  62  relative to each other for placement and removal of workpiece  54  as desired. 
   Cylinder  82  in accordance with the present invention serves to apply pressure to hold workpiece  54  in place during rotation and vertical movement. 
   Assembly  56  advantageously includes a base or support member, in this case legs  84 , which support a horizontal frame member  86 . A polishing head  88  is provided, preferably in the form of a rotatable disc  90  rotatably mounted relative to surface  86  and having positioned thereon a plurality of sanding elements, typically bricks or diamond pads having different coarseness or grit. 
   In accordance with the present invention, it is preferred to provide five different bricks  92  or sanding elements, positioned around the periphery of disc  90 , for use in providing all phases of polishing as are desired. In this regard, a further motor  94  may advantageously be provided for driving rotation of disc  90  relative to surface  86  and thereby for positioning a desired sanding element or brick  92  relative to workpiece  54 . This motor may advantageously be a ½ HP motor preferably having a box/gear reducer adapted for providing the desired turning to each brick position. 
   A further air cylinder  96  is also preferably provided for driving polishing head  88  toward workpiece  54 , and may be provided in the form of a 2 inch air cylinder or the like. This serves advantageously to move bricks or sanding elements  92  in and out of contact with workpiece  54  and also to apply the pressure necessary for providing polishing of workpiece  54  as desired. 
   Assemblies  52  and  56  can advantageously be automated so that movement up and down, rotation speed or rpm of element  62  and workpiece  54  held thereby, and the duration, sequence and/or force applied using polishing head  88  are automated so that once a workpiece  54  is mounted between elements  62 , vertical motion and rotation of workpiece  54  and proper sequential operation of polishing head  88  are fully automated. This advantageously provides for uniform polishing of substantially cylindrical pieces of granite and the like, and further advantageously provides results which are duplicatable. 
   Still referring to  FIG. 6 , it may be desirable to position limit switches  98 , for example on vertical support  70 , for establishing upper and lower limits of movement of horizontal member  66 ,  68  relative to vertical support  70 ,  72 . These can advantageously be simple limit switches communicated with a control member for the system, or can be provided in other forms as well. 
   A apparatus  50  in accordance with the present invention advantageously provides for polishing of the outside cylindrical surface of a substantially cylindrical-shaped piece of stone such as centerpiece portions removed in accordance with the method of the present invention as illustrated in  FIGS. 1–5 . 
   It should be appreciated that the apparatus in accordance with the present invention advantageously provides for polishing of the outside cylindrical surface of stone articles such as granite, marble and the like, and this polishing has hence forth been done by hand in an extremely time-consuming manner. Thus, the apparatus of the present invention provides significant time savings and an excellent polished quality to the outside surface of the article treated thereby. 
   It should also be appreciated that although portions of the above detailed description are provided in terms of treating a block of granite, the method and apparatus of the present invention are likewise applicable to other types of stone such as marble and the like. 
   It is to be understood that the invention is not limited to the illustrations described and shown herein, which are deemed to be merely illustrative of the best modes of carrying out the invention, and which are susceptible of modification of form, size, arrangement of parts and details of operation. The invention rather is intended to encompass all such modifications which are within its spirit and scope.