Abstract:
A motor mount assembly for a milling tool, in particular a clamshell lathe, wherein the motor mount assembly has a housing that is secured to a stationary ring of the lathe and a drive gear rotatably journaled in the housing and in operative contact with gearing on a rotatable ring of the lathe that carries a cutting tool. The drive gear is operatively axially supported internally by both the drive shaft of the motor as well as by a portion of the motor mount assembly housing in order to provide a durable, long wearing motor mount assembly.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a motor mount assembly for a milling tool, in particular a clamshell lathe, wherein the motor mount assembly has a housing that is secured to a stationary ring of the lathe and a drive gear rotatably journaled in the housing and in operative contact with gearing on a rotatable ring of the lathe that carries a cutting tool. The drive gear is operatively axially supported internally by both the drive shaft of the motor as well as by a portion of the motor mount assembly housing in order to provide a durable, long wearing motor mount assembly. 
     BACKGROUND OF THE INVENTION 
     Clamshell lathes are known in the art and can be utilized typically in industrial settings to mill a portion of a generally cylindrical pipe or tube. Non-limiting examples of clamshell lathes are disclosed in U.S. Pat. Nos. 4,739,685; 4,939,964; and 5,549,024. Clamshell lathes in some embodiments are designed as annular devices formed from semi-cylindrical halves connected together around a pipe to be milled. A stationary ring of the clamshell lathe is temporarily fixed to the pipe. A rotatable ring is operatively connected to the stationary ring and is rotatable for example by an air, hydraulic, or electrically-operated motor operatively connected to the rotatable ring. In some embodiments, the motor has a motor mount assembly having a housing that is connected to the stationary ring. The motor mount assembly has a drive gear that engages gearing located on the rotatable ring. A tool slide can be mounted on the rotatable ring and is adapted to hold a cutting tool for milling the pipe. The tool slide can include a feed mechanism that advances the tool slide and thus the cutting tool preferably in a radial direction toward the pipe in incremental steps upon a predetermined revolution of the ring gear. 
     The motor mount assemblies used in the prior art to connect the motor to the lathe are typically connected to the outside diameter of the stationary ring. Such motor mount assemblies have been designed having a plurality of structural arrangements. Some arrangements of motor mount assemblies utilize a drive gear journaled for rotation in the housing that is connected to a drive shaft of the drive motor. 
     Examples of motor mount assemblies are set forth in the following patents. 
     U.S. Design Pat. D466,132 relates to an ornamental design for a drive motor mount for a clamshell lathe. 
     U.S. Pat. No. 4,762,038 relates to a pipe machining apparatus having a tool carrier rotatable about a frame mounted externally of a pipe, with the frame being formed of two semi-annular sections which are releasably held together by connection devices including co-acting pin and latch structures. 
     U.S. Pat. No. 4,823,655 relates to a multi-speed drive system for a portable lathe, wherein two or more input drive gears are utilized to drive a cutting tool holder ring. Each of the input drive gears has a different pitch diameter so that it will reportedly impart different drive speeds/torque characteristics to the cutting tool holder ring. A main drive gear is interposed between each of the input drive gears and a ring gear attached to the cutting tool holder. The input drive gears are each engaged with the main drive gear and a drive motor is connected to the desired input drive gear. 
     U.S. Pat. No. 4,939,964 relates to a portable machining lathe having a stationary member interconnected with a gear housing which covers a rotating gear member. A circular race member is connected to the gear member and held in place by means of a plurality of roller bearings. A tool module having a tool bit machines the work piece and automatically advances longitudinally along the work piece by means of an advance mechanism. 
     U.S. Pat. No. 5,054,342 relates to a pipe machining apparatus that includes a tool carrier with a frame attachable to a pipe for rotatably mounting the tool carrier. The tool carrier is circumferentially rotatable about the pipe and carries a tool for performing cutting or machining operations on the pipe. A plurality of rotatable bearings are provided between the frame and the tool carrier, and the bearings are reportedly individually adjustable in a radial direction to compensate for wear of the bearings during use of the apparatus. 
     U.S. Pat. No. 5,549,024 relates to a clamshell machining lathe for cutting and finishing pipes in industrial settings comprising a split-ring assembly, including a clamping ring that is positioned about the pipe, and journaled to the clamping ring is a rotatable gear ring that supports a tool block carrying a cutting tool. 
     U.S. Pat. No. 6,427,567 relates to a motor mount for attaching a drive motor to a clamshell lathe including a gear box whose angular disposition reportedly can be adjusted relative to a drive gear housing affixed to the periphery of the clamshell lathe. This reportedly facilitates the positioning of the clamshell lathe on a workpiece with reduced chance of interference of the drive motor with neighboring obstructions. 
     SUMMARY OF THE INVENTION 
     In view of the above, it would be desirable to provide a clamshell lathe with a motor mount assembly that can be quickly and easily connected to both the clamshell lathe as well as a drive motor. 
     One object of the invention is to provide a motor mount assembly with a desirable construction that is durable and has a long wearing drive gear. 
     Another object of the invention is to provide a motor mount assembly with a drive gear that is internally supported at both ends in relation to a central rotational axis in order to minimize lateral movement of the drive gear. 
     Yet another object of the invention is to provide a compact, space saving motor mount assembly having a drive gear comprising a bore or aperture located at the end of the gear comprising gear teeth, wherein a bearing is located in the aperture, the bearing having an aperture that receives a projection present on an inner surface of the cover the housing, whereby the drive gear is rotatably supported by the housing. 
     Still another object of the invention is to provide a motor mount assembly with a pair of bearings, wherein one bearing is rotatably connected to the drive shaft of the motor and the second bearing is rotatably connected to an internal portion of the drive gear, whereby both bearings are in contact with a portion of the housing, namely a rim of the body of the housing as well as an end cover of the housing. 
     A further object of the present invention is to provide the motor mount assembly housing with a bearing seat having a rim that prevents lateral movement of one of the bearings towards the drive gear. 
     Still another object of the present invention is to provide a motor mount assembly that places minimal stress on a drive shaft of a motor connected thereto, thereby extending the life of the motor by preventing damage to the drive shaft. 
     Yet another object of the present invention is to provide a motor mount assembly having sealed bearings which are thus shielded from debris that results from the milling operation performed utilizing the clamshell lathe to which the motor mount assembly is attached. 
     In one aspect of the present invention, a motor mount assembly for a clamshell lathe is disclosed, comprising a drive gear adapted to be connected to a drive shaft of a drive motor and having a rotational axis, a head portion comprising a plurality of gear teeth arranged circumferentially around the rotational axis and adapted for driving gear teeth on a rotatable ring of the clamshell lathe, and a shaft portion connected to the head portion, the head portion having a bore in an end face of the head portion, the shaft portion including a second bore located in an end face of the shaft portion and adapted to receive the drive shaft of the drive motor; and a housing adapted to be connected to a stationary ring of the clamshell lathe, wherein a portion of the drive gear is located in and is operatively rotatable within the housing, the housing having a drive shaft aperture adapted to receive a portion of the drive shaft of the drive motor, and a drive gear aperture that exposes a portion of the gear teeth of the drive gear. 
     In another aspect of the present invention, a motor mount assembly for a clamshell lathe is disclosed, comprising a drive gear adapted to be connected to a drive shaft of a drive motor and having gear teeth adapted for driving gear teeth on a rotatable ring of the lathe; and a housing adapted to be connected to a stationary ring of the lathe, the housing having a drive shaft aperture adapted to receive the drive shaft of the motor, a drive gear aperture that exposes a portion of the gear teeth of the drive gear, and a projection having a portion internally located in a bore of the drive gear that operatively supports the drive gear, and wherein the drive gear is rotatable about the projection. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be better understood and other features and advantages will become apparent by reading the detailed description of the invention, taken together with the drawings, wherein: 
         FIG. 1  is an exploded perspective view of one embodiment of a motor mount assembly of the present invention; 
         FIG. 2  is a perspective view of one embodiment of the drive gear of the present invention, particularly illustrating an aperture for a drive shaft of a motor for driving the motor assembly as well as an aperture in which a bearing is mountable; 
         FIG. 2A  is a side elevational view of the drive gear illustrated in  FIG. 2 ; 
         FIG. 2B  is a front elevational view of the bearing illustrated in  FIG. 2 ; 
         FIG. 3  is a side elevational view of one embodiment of the motor mount assembly of the present invention connected to a motor; and 
         FIG. 4  is a perspective view of one embodiment of the present invention illustrating the motor mount assembly operatively connected to a clamshell lathe. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     One embodiment of a motor mount assembly  10  for a clamshell lathe is illustrated in  FIG. 1 . The assembly is adapted to be fastened, for example utilizing bolts  12 , or otherwise operatively connected to a stationary ring  72  of a clamshell lathe  70 , see  FIG. 4  for example. A drive motor  60  is operatively connected to a housing  20  of the assembly  10  for driving a drive gear  30  that is used to rotate a rotatable ring  74  of the clamshell lathe  70 , see  FIGS. 3 and 4 . 
     Motor mount housing  20  has a main body portion having a generally cylindrical shape that houses the drive gear  30 , wherein an axis  14 , generally a rotational axis of the drive gear  30  and drive shaft  62  of the drive motor, see  FIG. 3 , extends through the housing  20 , see  FIG. 1 . Housing  20  has a first end  22  that includes an aperture  23  through which the drive shaft  62  of the motor  60  is adapted to extend. The housing  20  is provided with a base  24  having one or more flanges  25  that preferably include at least one aperture through which bolt  12  can be extended in order to allow the motor mount assembly  10  to be secured to the stationary ring  72  of the clamshell lathe  20 , such as shown in  FIG. 4 . In one embodiment, the bottom surface of base  24  is substantially planar, such as shown in  FIG. 1 . In one embodiment, base  24  can be provided with one or more keys or key slots which cooperate with the corresponding opposite features on the stationary ring  72  in order to provide accurate alignment of the motor mount assembly  10  on the stationary ring  72  of clamshell lathe  70 . 
     The housing  20  has a second end  26 , generally opposite first end  22  along the axis  14 , to which end cover  40  is connected. The end cover  40  allows access to the inside of the housing  20 , provides protection to the components located within the housing  20 , and provides support to the drive gear  30 , as well as the drive shaft  62 , as further explained herein. A suitable fastener, such as button socket head cap screws  42  can be used to secure the cover  40  to the second end  26  of housing  20 . 
     In one embodiment, the housing inner surface  21  is provided with an annular seat  27  for a bearing  50 , preferably a roller bearing through which a portion of the motor drive shaft extends. The seat  27  is preferably formed comprising a rim  28  that prevents lateral movement of the bearing  50  along the axis  14  towards the second end  26  of the housing  20  and drive gear  30 . Rim  28  is thus a feature, in a preferred embodiment an annular ring, that has a portion, preferably diameter, smaller than the maximum diameter of bearing  50 , thereby maintaining the bearing  50  in the housing chamber located towards the first end  22  of housing  20 . The outer diameter of bearing  50  is preferably journaled in bearing seat  27  and one side of the bearing  50  preferably contacts seat rim  28 . 
     Housing  20  also includes a window or opening  29  near the second end  26 , see especially  FIG. 3 , which allows the drive gear  30  to be connected to or meshed with the gearing  76  on the rotating ring  74  of the clamshell lathe  70 . The periphery of the opening  29  preferably abuts the rotating ring cover in order to prevent debris such as chips or shavings that result from the milling operation performed on a workpiece with the clamshell lathe from entering the motor mount assembly  10 . 
     One embodiment of drive gear  30  is illustrated in  FIGS. 2 ,  2 A and  2 B. Drive gear head portion  31  has a plurality of teeth  32  connectable with the gearing located on the rotating ring of the clamshell lathe. Drive gear head portion  31  also includes a first bore  34  in which drive gear bearing  52  is journaled. 
     The depth of bore  34  is preferably sufficient to fit the width of bearing  52 . In one embodiment, bearing  52  is located within drive gear  30 , such that the front face of the drive gear  30  is flush with the face of bearing  52 , i.e., the bearing does not project outwardly from the front face of the bore of drive gear  30 . The depth of the bore  34  can vary and generally ranges from about 40% to about 60% and preferably from about 35% to about 55% of the width of gear teeth  32  measured along the axis  14 . Drive gear  30  also has a shaft portion  33  provided with a second bore  36  for receiving an appropriate drive shaft of the drive motor. Second bore  36  preferably includes a key slot  37 , see  FIG. 2B , that mates with a key present on a drive shaft of the motor. The shaft portion  33  is preferably provided with a set screw aperture  38  that can receive a set screw that fixedly connects the drive shaft  62  and drive gear  30 . Therefore, it can be understood that the drive motor is adapted to rotate the rotatable ring of the stationary ring through the gear assembly provided by connecting the drive shaft of the motor to drive gear  30 . The diameter of bore  36  in relation to central axis  14  can vary such that the drive shaft to the motor is able to operatively rotate the drive gear  30 . 
     In one embodiment as illustrated in  FIG. 2 , first bore  34  and second bore  36  are in communication with each other and, therefore, an aperture extends completely through drive gear  30  along axis  14 . However, it is to be understood that first bore  34  and second bore  36  may be separated if desired. The outer diameter of the shaft portion  33  is preferably less than the head portion  31  of the drive gear  30  in one embodiment. The outer diameter of the shaft portion  31  of drive gear  30  is less than the inner diameter of rim  28  in one embodiment. 
     As illustrated in  FIG. 1 , the end cover  40  of housing  20  includes a projection  44  on an inner surface thereof that operatively supports the drive gear  30 . Preferably, projection  44  is an annular ring or cylinder having an outer diameter that mates with the inner diameter of bearing  52 . Bearing  52  is operatively located within drive gear  30 , and drive gear  30  operatively rotates around projection  44  and is supported thereby. The axial support provided by the projection  44  for drive gear  30  prevents the head portion  31  of drive gear  30  from sagging or deformation and provides for longer life and less wear, for both drive gear  30  as well as drive shaft  62 . Also, less movement of the end of the drive gear  30  including the teeth  32  is realized. The height or length of projection  44  measured in relation to axis  14  is sufficient to provide the desired amount of support for drive gear  30  through bearing  52 . In a preferred embodiment, the maximum length of projection  44  measured parallel to axis  14  is about 50% to about 150% of the axial length of bearing  52 . The length of projection  44  measured parallel to axis  14  is preferably the same as the axial length of bearing  52  Also, it is important that projection  44  does not contact the drive shaft of the motor. 
     In view of the constructions described herein, it is illustrated that drive gear  30  is internally supported at both ends in relation to the central rotational axis  14 , thereby minimizing lateral movement of the drive gear  30  and drive shaft  62 . At the head portion  31  of the drive gear, the drive gear  30  is internally supported by projection  44  of end portion cover  40  through bearing  52 . The shaft portion  33  of drive gear  30  is internally supported by a drive shaft of the motor, with the drive shaft additionally being supported by housing  20  through bearing  50 . 
     The bearings provided in the present invention are compact and save space by providing the drive gear  30  with internal connection and support resulting in durability and extended life of the drive gear and drive shaft. The bearings utilized are preferably sealed so that the internal components thereof are shielded from debris that can result during the milling process utilizing the clamshell lathe. 
     The motor mount assembly of the present invention can be utilized in one embodiment as follows. A drive shaft  62  of the motor  60  that is utilized in connection with the motor mount assembly  10  is inserted through bearing  50  as well as through drive shaft aperture  23 . The motor is secured to housing  20  preferably utilizing one or more fasteners, see  FIG. 3  for example. Drive gear  30  is operatively connected to the end portion of the drive shaft  62  by inserting the drive shaft  62  in second bore  36  of drive gear  30 . A set screw is preferably provided in set screw aperture  38  and tightened against drive shaft  62  that fixedly connects drive gear  30  thereto. Thereafter, end cover  40  is fastened to housing  20  utilizing screws  42  whereby a portion of projection  44  and bearing  52  are located within the first bore  34  of drive gear  30 . Housing  20  is secured to the stationary ring of the clamshell lathe either prior to or after the motor and drive gear are interconnected. The teeth  32  of drive gear  30  are meshed with the gearing  76  on the rotatable ring  74  of the clamshell lathe  70 . Motor  60  can operate as desired in order to rotate the rotatable ring  74  of clamshell lathe  70  through motor mount assembly  10 . 
     While in accordance with the patent statutes the best mode and preferred embodiment have been set forth, the scope of the invention is not intended to be limited thereto, but only by the scope of the attached claims.