Abstract:
A rotary clamping device for use in clamping and holding a metal casting tree during cutting of the metal casting tree includes a cylinder having a piston rod for actuating a plurality of clamping jaws. In one embodiment, a conically shaped cam engages exteriorly disposed clamping jaws for urging the jaws in a clamping direction. In another embodiment, an exteriorly located cam urges the jaws in a clamping direction. The number of jaws employed may vary with the shape of the metal casting tree to be gripped.

Description:
FIELD OF THE INVENTION 
     This invention related to clamps and more particularly to rotary clamps used to hold metal casting trees during a cutting operation. 
     BACKGROUND OF THE INVENTION 
     In metal casting operations, several identical articles are simultaneously cast as a cluster or tree. The various articles must be cut from the tree or cluster. In some conventional practices, the cast articles are cut from the tree by a power driven, manually manipulated saw. This type of operation is dangerous and sometimes results in injury to the operator. 
     SUMMARY OF THE INVENTION 
     It is an object of this invention to provide an improved rotary clamping device for gripping and holding metal casting trees during a cutting operation regardless of the shape or configuration of the sprue or other part to be gripped. 
     Another object of this invention is to provide an improved rotary clamping device of elongate configuration for reaching and gripping internally located sprues of metal castings to be cut. 
     Another object of this invention is to provide a rotary clamping device having recessed clamping jaws for effectively clamping sprues or other parts of metal casting to be cut. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWINGS 
     FIG. 1 is a side elevation of one embodiment of my novel rotary clamping device illustrated in clamping relation with a metal casting depicted in dotted line configuration and with parts thereof broken away for clarity; 
     FIG. 2 is an exploded, fragmentary perspective view of a portion of the clamping device illustrated in FIG. 1 with certain parts thereof broken for clarity; 
     FIGS. 3-6 are diagrammatic end elevational views illustrating different numbers and arrangements of the clamping jaws for gripping sprues or other parts of metal castings having different shapes; 
     FIG. 7 is a side elevational view of a different embodiment of the rotary clamping device with certain parts thereof broken away for clarity; 
     FIGS. 8-10 are end elevational views of the clamping jaws and camming ring illustrating how differently shaped sprues are effectively gripped, FIG. 8 being depicted in broken exploded condition for clarity. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIGS. 1-6, it will be seen that one embodiment of the novel clamping device, designated generally by the reference numeral  10 , is thereshown. The clamping device  10  is a rotary clamping device and is intended to be used in conjunction with the apparatus for holding and cutting metal casting trees disclosed in my co-pending application entitled Apparatus For Clamping and Precisely Cutting Metal Castings, filed Nov. 2, 1998, Ser. No. 09/184,150. The rotary clamping device  10  is rotatable about its longitudinal axis to position the metal casting ICT in the optimum condition for cutting. It will be noted that the sprue of the metal casting ICT is gripped and held by the rotary clamping device  10 . 
     The rotary clamping device  10  includes a cylinder  11  having a rear plate  13  and a front plate  12  which co-operates with the cylinder to define a chamber  14 . A piston  15  is positioned in the chamber and is movable axially therein in response to hydraulic fluid introduced into the chamber. One end of an elongate piston rod  16  is secured to the piston and projects axially through the plate  12  as best seen in FIG.  1 . In this regard, the plate  12  is provided with an opening  17  through which the piston rod  16  projects and a suitable O-ring seal sealingly engages the piston rod  16 . 
     A plate  18  is secured to the plate  12  and has one end of an elongate tube  19  welded thereto. It will be noted that the plate  18  has an opening therein through which the piston rod  16  projects. 
     The piston rod  16  has a collar  20  secured thereto intermediate the ends thereof but located adjacent the rear end portion of the piston rod. The tube  19  serves as a guide tube and the collar  20  is movable in the tube along with the piston  16 . The collar  20  serves to stabilize the movement of the piston rod during movement thereof in the tube  19 . 
     The outer or front end of the piston rod  16  has a cam  21  secured thereto and projecting therefrom. The cam  21  includes a cylindrical portion  22  which engages the inner surface of the guide tube  19 . The cam also includes a frusto conical portion  23  which is integral with the cylindrical portion  22  and tapers forwardly therefrom. The piston rod  16  has a threaded forward end  24  which threadedly engages in a threaded recess in the cam  21  for securing the cam to the piston rod. It will be seen that the piston rod  16  and cam  21  are movable in an advanced direction, to the left as viewed in FIG. 1, and a retracted direction, to the right as viewed in FIG.  1 . 
     The clamping jaw assembly  25  is secured to the outer end portion of the guide tube  19  and includes a plurality of clamping jaws  25   a . Each clamping jaw  25   a  includes an elongate rectangular jaw body  26  having a recessed clamping face  27 . In the embodiment shown, each clamping jaw  25   a  is provided with a pair of clamping teeth  28  which project through openings  28   a  in the clamping jaw body. The clamping teeth  28  project inwardly beyond the clamping face  27  as best seen FIGS. 1 and 2. In the embodiments of FIGS. 1-4 and  6 , the teeth of each clamping jaw are arranged in a fore and aft spaced relation with respect to each other. 
     A cylindrical jaw mounting member  29  is mounted within the outer end of the guide tube  19  and projects therefrom. The cylindrical mounting member  29  has a plurality of pairs of ears  30  secured thereto and projecting therefrom as best in FIG.  2 . That portion of the jaw mounting member  29  to which the ears are secured is located forwardly of the guide tube  19 . The ears  30  are provided with openings or apertures  31  for accommodating pivot pins  33  which extend through openings  32  in the jaw members. In the embodiment illustrated in FIGS. 1 and 2, a pair of clamping jaws  25   a  are pivotally secured to the mounting member  29  in opposed relation with respect to each other. The jaws are pivoted in release and clamping directions. A spring  34  is provided for each jaw  25   a  and is interposed between jaw mounting member  29  and one of the jaws  25   a  to normally urge the jaw in an open or release direction. 
     Referring again to FIGS. 1 and 2, it will be seen that the rear end portion of each jaw  25   a  has a cam follower pin  26   a  press fitted in the jaw and projecting inwardly therefrom. These cam follower pins  26   a  pass through openings  19   a  in the guide tube  19  and are disposed in engaging relation with the frusto conical portion  23  of the cam  21 . It will be seen that when the piston and piston rod are moved in an advanced direction, the cam  21  will progressively cam the rear end portion of the jaws  25   a  outwardly which causes the front portion of the jaws to be progressively moved in a clamping direction. 
     It will be appreciated that the piston rod  16  will remain in the advanced condition when the clamping jaws  25   a  are clamping the sprue or other part of a casting tree. When the piston rod  16  is retracted, the flat springs  34  urge the jaws to the normally open position. It will again be noted that the springs  34  are interposed between the cylindrical mounting member  29  and the inner surface of the associated jaw  25   a.    
     A pair of conduits  35  and  36  are connected in communicating relation with the cylindrical chamber  14  for supplying hydraulic fluid thereto. These conduits  35 ,  36  are connected to a source of hydraulic fluid under pressure for selectively shifting the piston  15  axially of the chamber  14  in opposite directions. 
     The end plates  12  and  13  of the cylinder  11  are provided with bearing engaging elements  38  which engage in bearings  37  to permit rotation of the entire clamping device when the rod  39  is rotated. It is pointed out that the rod  39  is rigidly connected to the end plate  13  as best seen in FIG.  1 . 
     Referring now to FIG. 3, it will be seen that the rotary clamp device  10  is diagrammatically depicted with a jaw assembly  55  having four clamping jaws  56  for clamping a metal casting tree ICT. It will be noted that the jaws  56  are symmetrically arranged and are angularly disposed approximately 90° apart. Each jaw  56  is provided with a pair of teeth  58  which are arranged in fore and aft aligned relation. 
     Referring now to FIG. 4, it will be seen that the rotary clamping device is illustrated diagrammatically and is provided with a jaw assembly  65  having three symmetrically arranged jaws  66  for clamping the metal casting tree ICT. It will be noted that the jaws  66  are arranged approximately 120° apart. Each jaw  66  is provided with a pair of gripping teeth  68  which are arranged in fore and aft aligned relation. 
     Referring now to FIG. 5, it will be seen that the rotary clamping device is provided with a jaw assembly  75  having a pair of opposed jaws  76  for clamping and holding the metal casting tree ICT. In the embodiment of FIG. 5, each clamping jaw is provided with a pair of teeth  78  which are disposed in side-by-side spaced relation rather than the fore and aft relation of the embodiments of FIGS. 1-4. 
     Referring now to FIG. 6, it will be seen that the rotary clamping device is diagrammatically illustrated having a jaw assembly  85  which is comprised of three jaws  86 . The jaws  86  are not symmetrically arranged but serve to clamp a metal casting tree ICT. It will be noted that each jaw  86  is provided with a pair of clamping teeth  88  which are disposed in fore and aft relation. 
     From the foregoing description of the rotary clamping device  10  depicted in the embodiments FIGS. 1-6, it should be clear that the number of jaws and their particular arrangement may be selectively determined based on the configuration of the sprue or other part of the metal casting tree to be gripped. The gripping teeth may be arranged in fore and aft relation or may be disposed in side-by-side relation, again, depending on the shape of the sprue or part of the metal casting tree to be gripped. It will be appreciated that the number of jaws to be used is limited only by the space constraints of the size of the jaws and the mounting member  29 . The linear dimension of the clamping jaw device  10  is substantially greater than the conventional clamping jaw device. This long reach makes this clamping device especially adapted for gripping the interior part or sprue of a metal casting tree. 
     Referring now to FIGS. 7-10, it will be seen that a different embodiment of the rotary clamping device, designated generally by the reference numeral  100 , is thereshown. The rotary clamping device is similar in construction and operation to the rotary clamping device disclosed in U.S. Pat. No. 5,044,421 which is used in a cleaning rather than a cutting operation. The rotary clamp device  100  includes a clamp body  101  including a rear circular plate  102 , an intermediate circular plate  103  and a circular camming ring  104 . The clamp body also includes a rear cylindrical portion  105  and a front cylindrical body portion  106 . It will be seen that the rear body portion  105  is secured to the rear circular plate  102  and the intermediate circular plate  103 . The front cylindrical body portion  106  is secured to the intermediate circular plate  103  and the clamping ring  104 . 
     A pipe  107  is welded to an annular plate  108  which is secured by bolts  109  to the rear circular plate  102 . The pipe is connected to a wheel which permits the entire rotary clamp device  100  to be rotated about its longitudinal axis. 
     A piston  112  is positioned in the chamber  111  of the rear cylindrical body portion  105 . The piston  112  is moveable axially in the chamber  111  in response to fluid pressure. The piston  112  is provided with O-ring seals for engaging the interior surface of the cylindrical chamber  111  and one end of an elongate piston rod  114  is secured to the piston  112 . In this regard, the piston rod  114  has its rear end threaded as at  115  which projects through an opening in the piston rod and is secured thereto by nut  116 . It will be seen that when the piston  112  is moved axially of the chamber  111 , the piston rod  114  moves with the piston as a unit. 
     The piston rod  114  projects through the intermediate plate  103  which has O-ring seals  117  for providing a fluid type seal therebetween. A flange  118  having a reduced forward end is secured to the intermediate plate  103  by means of bolts  119 . An O-ring seal  120  is provided between the reduced end of the flange  118  and the piston rod  114 . 
     The outer end of the piston rod  114  is secured to a clamp assembly  121 . The clamp assembly  121  includes a clamp retainer plate  122  which is integral with the piston rod  114 . The clamp retainer plate  122  has diametrically disposed recesses  123  therein, each accommodating one end portion of an arcuate clamp jaw  124 . Each clamping jaw  124  is pivotally connected to the retainer plate  122  by a pivot  125  which permit the clamping jaws  124  to be moved in clamping and release directions. Each clamping jaw  124  is urged in a release direction by a spring  126  as best seen in FIG.  7 . 
     In the embodiment shown, it will be seen that each clamping jaw  124  has an outer curved surface  124   a , substantially flat side surfaces  124   b  and a notch  124   c  formed in the front portion of the inner surface of the clamping jaw. The curved outer surface  124   a  actually defines a cam follower surface. 
     It will be noted that the rear end portion of each jaw  124  has a recess  127  therein for accommodating the spring  126 . It will further be noted that the cam ring  104  has an inner forwardly and inwardly tapered surface  128  which is generally of frustro conical configuration. The inner surface of the cam ring  104  has a pair of diametrically opposed notches  129  therein, each notch including a camming notch surface  130  and substantially flat side surfaces  131 . Each clamping jaw  124  is positioned in one of the notches  129  so that the outer cam follower surface  124  of the jaw is in engaging relation with the camming notch surface  130 . 
     The clamp retainer plate  122  has a centrally located recess  132  therein for accommodating a generally cylindrical seal  133 . An abutment bolt  134  is threaded into a threaded recess in the central portion of the clamp retainer plate and is provided with a bolt head  135  having an outer convex surface. 
     It will be seen that the pipe  107  which is welded to the annular plate  108  has a smaller pipe  136  positioned concentrically therein to define an annular passage  137  and a central passage  138  through which hydraulic fluid under pressure is supplied to the chamber  111  for shifting the piston  112  in advanced and retracted positions. 
     It will be seen that when the piston rod  114  is advanced, the clamping jaws  124  will be moved forwardly and urged in a clamping direction for progressively engaging the metal casting tree ICT. The sprue or other part of the metal casting tree will be gripped by the notched face of the jaws and held firmly during the cutting operation. The clamping jaws will be restrained against movement by the interaction of the jaws with the associated notches  129 . It is pointed out that during the cutting operation of the metal casting tree ICT, the jaws will be subjected to torque and side loading but are restrained against movement by the coaction of the arcuate jaws in the notches  129 . The notches  124   c  and the jaws  124  provide a highly efficient gripping surface for gripping the sprue or other part of the metal casting tree. 
     It will be appreciated that the cross-sectional configuration of the jaws  124  and the cross-sectional configuration of the notches  129  can have other shapes and are not limited to the configurations shown. For example, the notches may be arcuate or curved in cross-section and the jaws may also be arcuate and curved in cross-section. 
     Referring now to FIGS. 8,  9  and  10 , it will be seen that different shaped sprues or metal casting parts to be gripped are illustrated in gripped relation by the jaws  124 . In FIG. 8, a sprue or other part of the metal casting tree having a generally square or diamond shape configuration is shown being gripped at opposed corners. In FIG. 9, a sprue or other part of the metal casting having a triangular cross-sectional shape is gripped by the rotary clamping device. In FIG. 9, an apex of the triangular shaped sprue is gripped by a jaw while the other two apices are clamped against the inner surface  130  of the cam ring  104 . 
     In FIG. 10, a sprue or other part of the metal casting tree ICT having a circular cross-sectional configuration is illustrated in gripped relation by the jaws  124 . It is pointed out that the configuration of the notch  124   c  may also have other configurations than the V-shaped notch illustrated in the embodiments of FIGS. 7,  8  and  9 . Thus the notch  124   c  may be circular, square or the gripping face of the jaws  124  may be only slightly concave. The notch or concavity in the jaw face may have any number of configurations. 
     From the foregoing, it will be seen that the two embodiments of the rotary clamping devices are constructed to effectively grip variously configured sprues and other parts of metal casting trees to be gripped during a cutting operation. The rotary clamping devices positively hold the gripped metal casting tree against torque and side loading to assure effective and precise cutting of the casting tree. 
     Thus it will be seen that I have provided a rotary clamping device which is arranged and constructed for highly efficient action during a cutting operation of a metal casting tree.