Patent Publication Number: US-6712431-B1

Title: Cutting arrangement

Description:
FIELD OF THE INVENTION 
     This invention relates to a cutting arrangement for a machine. 
     SUMMARY OF THE INVENTION 
     According to the invention a cutting arrangement includes a pick holder having a bore containing a sleeve within which a shank of a pick is located, with the pick and the sleeve each having heads, the head of the sleeve having an outer abutting surface and an inner abutting surface, the outer abutting surface abuts an abutting surface of the head of the pick and the inner abutting surface abuts an abutting surface of the pick holder, with the abutting surface of the head of the pick having a convex formation which abuts a concave formation on the outer abutting surface of the sleeve. 
     Preferably the inner abutting surface on the sleeve has a convex formation and the abutting surface of the pick holder has a concave formation, with the convex and concave formations abutting one another. 
     The abutting surface of the head of the pick and the outer abutting surface of the head of the sleeve may include planar surfaces which abut one another. 
     The inner abutting surface of the head of the sleeve and the abutting surface of the pick holder may include planar surfaces which abut one another. 
     The shank of the pick and the bore of the sleeve may include retaining formations for retaining the sleeve and the shank within the pick holder if the head of the pick is severed from the shank. The retaining formations may be step formations. 
     The shank is preferably rotatable within the sleeve and the sleeve is preferably rotatable within the bore of the pick holder. Thus the sleeve is not an interference fit within the bore of the pick holder, but is a sliding fit within the bore of the pick holder. 
     The sleeve preferably has a tail which abuts a step in the bore of the pick holder, the tail having an inwardly curved formation which abuts an outwardly curved formation on the step. 
     The pick is preferably retained within the pick holder by a clip releasably secured to the pick. 
     According to another aspect of the invention a cutting arrangement includes a pick holder having a bore containing a sleeve within which a shank of a pick is located, with the pick and the sleeve each having heads, the head of the sleeve having an outer abutting surface and an inner abutting surface, the outer abutting surface abuts an abutting surface of the head of the pick, and the inner abutting surface abuts an abutting surface of the pick holder, with the inner abutting surface of the head of the sleeve having an outwardly curved formation and the abutting surface of the pick holder having an inwardly curved formation, with the inwardly and outwardly curved formations abutting one another. 
     According to another aspect of the invention a cutting arrangement includes a pick and a pick holder, the pick having a head with a shank extending therefrom, the head having an abutting surface which abuts an abutting surface of the pick holder, the abutting surface of the head having a convex formation which abuts a concave formation on the abutting surface of the pick holder. 
     The abutting surfaces of the pick and the pick holder may include planar surfaces which abut one another. 
     The shank of the pick and the bore of the pick holder may include retaining formations for retaining the shank within the bore if the head is severed from the shank. The retaining formations may be step formations. 
     According to another aspect of the invention a cutting arrangement includes a pick holder having a bore containing a sleeve within which the shank of a pick is located, with the shank of the pick and the bore of the sleeve having retaining formations for retaining the sleeve and the shank within the pick holder if the head of the pick is severed from the shank. 
     According to another aspect of the invention a sleeve includes an outer abutting surface for abutting a head of a pick, and an inner abutting surface for abutting a pick holder, the outer abutting surface having an inwardly curved formation for abutting an outwardly curved formation on the head of the pick. 
     The inner abutting surface may have an outwardly curved formation for abutting an inwardly curved formation on the pick holder. 
     The sleeve preferably has a tail which abuts a step in the bore of the pick holder, the tail having an inwardly curved formation for abutting an outwardly curved formation on the step. 
     According to another aspect of the invention a sleeve includes an outer abutting surface for abutting a head of a pick, and an inner abutting surface for abutting a pick holder, the inner abutting surface having an outwardly curved formation for abutting an inwardly curved formation on the pick holder. 
     According to another aspect of the invention a pick holder includes an abutting surface with a inwardly curved formation for abutting an outwardly curved formation on a sleeve or a pick. 
     The pick holder preferably has a step in its bore for abutting a tail of the sleeve, the step having an outwardly curved formation for abutting an inwardly curved formation on the tail. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional side view of a cutting arrangement according to the invention; 
     FIG. 2 is an exploded perspective view of the cutting arrangement; 
     FIG. 3 is an enlarged view of part of the pick showing its curved surfaces; 
     FIG. 4 is an enlarged view of part of the sleeve showing its curved surfaces; 
     FIG. 5 is an enlarged view of the pick holder showing its curved surfaces; 
     FIG. 6 is an exploded perspective view of a pick and a pick holder according to another embodiment of the invention; 
     FIG. 7 is a side view of FIG. 6 with the pick holder in cross-section; 
     FIG. 8 is a cross-sectional side view of the pick holder showing the location of the pick in the pick holder; 
     FIG. 9 is an enlarged view of part of FIG. 8; 
     FIG. 10 is a cross-sectional side view of a cutting arrangement according to a further embodiment of the invention; 
     FIG. 11 is an exploded perspective view of the cutting arrangement of FIG. 10; 
     FIG. 12 is a similar view to FIG. 4, but in addition showing the curved surfaces on the tail of the sleeve; 
     FIG. 13 is a similar view to FIG. 5, but in addition showing the curved surfaces on the step of the pick holder; 
     FIG. 14 is a similar view to FIG. 1, but in addition showing the curved surfaces on the tail of the sleeve and on the step of the pick holder; 
     FIG. 15 is a cross-sectional side view of a sleeve according to the invention for use as an adaptor for a prior art pick; and 
     FIG. 16 is a cross-sectional side view of the prior art pick located within the sleeve of FIG.  15 . 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     A cutting arrangement  10  for a continuous mining machine (not shown) includes a pick holder  12  having a bore  14  containing a sleeve  16  within which a shank  18  of a pick  20  is located. The pick  20  and the sleeve  16  have heads  22  and  24  respectively. 
     The head  24  of the sleeve  16  has an outer surface  26  which abuts a surface  28  of the head  22  of the pick  20 . Part of these abutting surfaces  26  and  28  have a concave formation  26 . 1  and a convex formation  28 . 1  which abut one another. In addition the abutting surfaces  26  and  28  have planar surfaces  27  and  29  which abut one another (see FIGS.  3  and  4 ). 
     Likewise an inner surface  30  of the head  24  of the sleeve  16  and an outer surface  32  of the pick holder  12  have a convex formation  30 . 1  and a concave formation  32 . 1  which abut one another. In addition to the abutting convex and concave formations, the inner surface  30  has a planar surface  33  which abuts a planar surface  35  on the pick holder  12  (see FIGS.  4  and  5 ). 
     FIGS. 3 to  5  show the convex and concave formations and their radiuses of curvature. 
     The thickness of the sleeve  16 , indicated by reference numeral  34 , is 7 mm, and the thinnest part of the pick holder  12  surrounding the sleeve  16 , indicated by reference numeral  36 , is 22 mm. 
     The sleeve  16  is a sliding fit within the bore  14  of the pick holder  12 . Likewise the shank  18  of the pick is a sliding fit within the sleeve  16 . Thus the sleeve  16  can rotate relative to the pick holder  12 , and the pick  20  can rotate relative to the sleeve  16 . 
     Referring now to FIGS. 6 to  9  a cutting arrangement for a mining machine (not shown) includes a pick  110 . 1  which has a head  112 . 1  and a shank  114 . 1  extending from the head  112 . 1 . The head  112 . 1  has an abutting surface  116 . 1  which abuts a abutting surface  118 . 1  of a pick holder  120 . 1 . the abutting surface  116 . 1  of the head  112 . 1  has a circumferentially extending convex formation  122 . 1 . The convex formation  122 . 1  abuts a circumferentially extending complimentary concave formation  124 . 1  on the abutting surface  118 . 1  of the pick holder. 
     The abutting surface  116 . 1  of the head  112 . 1  also has a circumferentially extending planar surface  126 . 1  which abuts a circumferentially extending planar surface  128 . 1  on the abutting surface  118 . 1  of the pick holder. 
     The convex formation  122 . 1  has a radius of curvature  128 . 2  with its centre  130 . 1  located inwardly of the head  112 . 1 . the concave foundation  124 . 1  has a radius of curvature which is substantially the same as the radius of curvature  128 . 2 . 
     The pick  112 . 1  is rotatable within the pick holder  120 . 1 . 
     Referring now to FIGS. 10 and 11, a cutting arrangement  10 . 2  for a continuous mining machine (not shown) is the same as that shown in FIGS. 1 to  3  except that the shank  18  has 45° step formation  28 . 3  at which its diameter decreases. The sleeve  16  has a bore  31  which has a corresponding step formation at which the diameter of the bore  31  decreases. 
     A clip  32 . 2  retains the pick  20  within the pick holder  12 . If the head  22  of the pick, which head includes the convex formation  28 . 1 , is severed from the shank  18 , the step formations on the shank and the bore  31  retain the sleeve  16  and the shank  18  within the pick holder  12  thereby preventing the loss of the sleeve  16 . The clip  32 . 2  is removably located on the pick  20 . 
     The step formation  28 . 3  is inclined at 45° and reduces the diameter of the shank by 2 mm. 
     Referring now to FIGS. 12 to  14 , a sleeve  16 . 2  has a tail  38  which abuts a step  40  in the bore of the pick holder  12 . 2 . The tail  38  has a concave formation  42  with a radius of curvature of 3.1 mm which abuts a convex formation  44  on the step  40 . The convex formation  44  has a radius of curvature of 3.0 mm. 
     Referring now to FIGS. 15 and 16, a sleeve  16 . 3  is the same as sleeve  16 . 2  except that it does not have a convex formation on its abutting surface  26 . The whole of the abutting surface  26  is planar. In addition, the bore of the sleeve  16 . 3  has a groove  46  for a clip  48  of a prior art pick  50 . The prior art pick  50  has a planar surface  52  which abuts the planar surface  26  of the sleeve  16 . 3 . Thus the sleeve  16 . 3  can be used as an adaptor in the pick holder  12 . 2  for a prior art pick  50 . 
     The applicant believes that the life of a cutting arrangement according to the invention will be increased over the prior art arrangements. The reason for this is that the abutting convex and concave formations result in an increased contact area or load bearing area. The increased contact area between the abutting convex and concave formations decreases the pressure on the abutting surfaces and acts as a bearing between the abutting surfaces. The applicant also believes that the convex and concave formations will improve the rotatability of the pick within the sleeve or pick holder, and improve the rotatability of the sleeve within the bore of the pick holder because of the reduced pressure. Furthermore, the applicant believes that the convex and concave formations improve the seal between the abutting surfaces, thereby at least reducing the penetration of particulate material between the abutting surfaces. Since the sleeve is a sliding fit, and not an interference fit within the pick holder, the sleeve can easily be removed from the pick holder if it is desired to replace the sleeve. 
     It will be appreciated that many modifications or improvements of the invention are possible without departing from the spirit or scope of the invention. Although the invention has been described with reference to convex formations and concave formations, these formations can broadly be described as outwardly curved formations and inwardly curved formations respectively.