Abstract:
A lathe includes a machine support, a working table positioned on the machine support, a rotating driver, a moving device, and a feeding device. The rotating driver rotates the work table. The moving device includes at least one cross beam, at least one first driving mechanism, and at least one second driving mechanism. The cross beam is movably positioned on the machine support above the working table. The feeding device is movably positioned on the at least one cross beam, and includes a feeding driving mechanism and a cutter. The first driving mechanism drives the cross beam to move along a first direction, and the second driving mechanism drives the feeding device to move along a second direction at about ninety degrees from the first direction. The feeding mechanism drives the cutter to move backwards and forwards along a third direction perpendicular to the first and second direction.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims all benefits accruing under 35 U.S.C. §119 from China Patent Application No. 201210252845.0, filed on Jul. 20, 2012, in the China Intellectual Property Office, the disclosure of which is incorporated herein by reference. The application is also related to co-pending applications entitled, “MACHINE TOOL WITH UNINTERRUPTED CUTTING” Ser. No. 13/705,843; “FEEDING DEVICE AND MACHINE TOOL USING THE SAME” Ser. No. 13/705,788; “METHOD FOR MACHINING CURVED SURFACE USING LATHE” Ser. No. 13/705,777; “LATHE FOR MACHINING CURVED SURFACES” Ser. No. 13/705,713; “FEEDING DEVICE AND MACHINE TOOL USING THE SAME” Ser. No. 13/705,611; “LATHE WITH TWO CROSS BEAMS” Ser. No. 13/705,585; “LATHE CONTROL SYSTEM” Ser. No. 13/705,545; “WORKPIECE HAVING NON-ROTATARY SURFACE MACHINED BY LATHE” Ser. No. 13/705,478. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure generally relates to lathes, and particularly, to a lathe which can machine a curved surface. 
     2. Description of the Related Art 
     In the related manufacturing field, a milling cutter with different cutting edges is used for machining curved surfaces. Some tracks are formed on the milled surface of the workpiece because of intermitted contact and interrupted milling by the milling cutter. A polish step needs to be added for a better appearance. When a lathe is used for machining curved surfaces, only a two dimensional curved surface with rotary feature can be machined because the movement of a cutter of the lathe is limited. 
     Therefore, there is room for improvement within the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The components in the drawings are not necessarily drawn to scale, the emphasis instead placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is an isometric view of an embodiment of a lathe having a feeding device and a work table. 
         FIG. 2  is a partial, isometric view of the lathe of  FIG. 1 . 
         FIG. 3  shows an exploded and isometric view of the lathe of  FIG. 2   
         FIG. 4  shows an isometric view of the feeding device and the work table of the lathe of  FIG. 1 . 
         FIG. 5  is an exploded, isometric view of the feeding device of  FIG. 1 . 
         FIG. 6  is similar to  FIG. 5 , but viewed from another aspect. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 and 2  show an embodiment of a lathe  100 . The lathe  100  includes a machine support  10 , a work table  20 , a moving device  30 , a feeding device  40 , and a controller (not shown). The work table  20  holds a workpiece in place and is supported by the machine support  10 . The moving device  30  is movably positioned on the machine support  10  above the work table  20 . The feeding device  40  is slidably mounted on the moving device  30 . The controller is electrically connected with the work table  20 , the moving device  30 , and the feeding device  40  for controlling the lathe  100 . Under the control of the controller, the moving device  30  can be driven to move with the feeding device  40 , such that the feeding device  40  can be driven to move along the X, the Y, and the Z axes. 
     The machine support  10  includes a base  11  and a pair of support bodies  13  positioned substantially parallel on the base  11 . A pair of first sliding rails  131  are positioned substantially parallel on a surface of each support body  13  away from the base  11 , and arranged apart from each other. In the illustrated embodiment, the first sliding rails  131  extend substantially parallel to the X-axis (a first direction). A receiving groove  133  is formed on each support body  13  between the two first sliding rails  131 . 
     Referring also to  FIG. 2 , the work table  20  is substantially cylindrical, and rotatably positioned on the base  11  between the two support bodies  13  via the rotating driver  21 . The rotating driver  21  drives the work table  20  and a workpiece placed on the work table  20  to rotate. In the illustrated embodiment, the rotating driver  21  is a direct drive motor. 
     Referring also to  FIG. 3 , the moving device  30  is slidably mounted on the pair of support bodies  13  above the work table  20 . The moving device  30  includes two cross beams  31 , four sliding bases  33 , four first driving mechanisms  35 , and two second driving mechanisms  37 . The two cross beams  31  are positioned spaced apart on the support bodies  13  for high stability. Opposite ends of each cross beam  31  are slidably positioned on the support bodies  13  via a pair of sliding bases  33 , respectively. The extending direction of the cross beam  31  is substantially parallel to the Y-axis (a second direction). A pair of second sliding rails  311  is positioned on a side surface of each cross beam  31  and extending substantially parallel to the Y-axis. Two side surfaces having the second sliding rails  311  of the cross beams  31  are positioned face to face. Two sliding bases  33  are installed on the opposite ends of the corresponding cross beam  31  to slidably connect with the first sliding rails  131 . The sliding base  33  includes a first sliding block  331  slidably engaging with the first sliding rails  131 . Each first driving mechanism  35  is mounted on a surface of one sliding base  33  away from the cross beam  31  and received in one receiving groove  133 . 
     The first driving mechanisms  35  are configured to drive the cross beams  31  to move along the first sliding rails  131 . Each of the first driving mechanisms  35  includes a first forcer  351  and a first stator  353 . The first forcer  351  is fixedly mounted on the sliding base  31  facing the receiving groove  133 . Two first stators  353  are fixedly received in each of the receiving grooves  133 . One second driving mechanism  37  is mounted on each of the cross beams  31  between two second sliding rails  311  to drive the feeding device  40  to move along the second sliding rails  311 . Each of the second driving mechanisms  37  includes a second forcer  371  and a second stator  373 . Each of the second forcers  371  are fixedly mounted on each of the opposite surfaces of the feeding device  40  facing the cross beams  31 . Both of the second stators  373  are installed on each of the cross beams  31  between two second sliding rails  311 . The first driving mechanisms  35  and the second driving mechanism  37  are electrically connected to the controller. In the illustrated embodiment, the first driving mechanisms  35  and the second driving mechanism  37  are linear motors. In other embodiments, the first driving mechanisms  35  and the second driving mechanism  37  are other drivers, such as hydraulic cylinders or rams. The number of the first driving mechanisms  35 , the second driving mechanism  37 , and the cross beam  31  can be designed according to their applications. 
       FIGS. 3 to 5  shows that the feeding device  40  is slidably positioned between the two cross beams  31 . The feeding device  40  includes a sliding saddle  41 , a mounting seat  43 , a tool holder  45 , a feeding mechanism  47 , and a cutter  49 . The sliding saddle  41  is movably assembled with the cross beams  31 . The mounting seat  43  is slidably connected to the sliding saddle  41  away from the cross beam  31 . The feeding mechanisms  47  are mounted and received in the mounting seat  43  to electrically connect with the controller. The tool holder  45  is slidably positioned on the mounting seat  43 , and has a reciprocating motion substantially parallel to the Z-axis (the Z-axis direction, a second direction) relative to the mounting seat  43 . 
     The sliding saddle  41  is slidably positioned between the two cross beams  31 . Two second sliding blocks  411  are separately positioned on opposite surfaces of the sliding saddle  41  away from the tool holder  45 , and substantially parallel to the Y-axis towards the cross beam  31 . The second sliding blocks  411  are slidably engaged with the correspondingly second sliding rails  311 . Each of the second forcers  371  is positioned between the two second sliding blocks  411 . 
     The mounting seat  43  includes a frame  431  and two mounting boards  433 . The frame  431  includes a first side wall  4311  and a second side wall  4313 . The first side wall  4311  and the second side wall  4313  are positioned substantially parallel to each other and cooperatively define a receiving space  4315 . The first side wall  4311  is slidably connected with the sliding saddle  41 . Two guiding portions  4317  protrude from an inner surface of the first side wall  4311  facing toward the second side wall  4315  and extend substantially parallel to the Z-axis. A through groove  4318  is defined in the second side wall  4313  and extends along a direction substantially parallel to the Z-axis corresponding to the guiding portions  4317 . Two guiding portions  4319  protrude from an outer surface of the second side wall  4313  at two sides of the through groove  4318 . In the illustrated embodiment, the guiding portions  4319  are sliding rails, the frame  431  is integrally formed. Two mounting boards  433  are respectively installed on two opening sides of the frame  431 . Each mounting board  433  is connected substantially perpendicularly to the first wall  4311  and the second side wall  4313  to close the two opening sides of the frame  431 . 
     The tool holder  45  slidably connects with the mounting seat  43 . The tool holder  45  is substantially “T” shaped, and includes a main body  451  and a sliding board  453  protruding substantially perpendicularly from the main body  451 . The main body  451  is a bar of material tapering in at both ends, and positioned outside of the mounting seat  43 . Two distanced holding portions  4511  are positioned on a bottom of the main body  451  away from the sliding board  453 . Four first direct portions  4513  (see  FIG. 5 ) are positioned on a surface of the main body  451  adjacent to the sliding board  453 . The four first direct portions  4513  are divided into two groups, each group having two first direct portions  4513  slidably engaging with one guiding portion  4319 . The sliding board  453  is located between the two groups of the first direct portions  4513 . The sliding board  453  passes through the through groove  4318  and is slidably attached to the two guiding portions  4317 , dividing the receiving space  4315  into two parts. A second direct portion  4531  is formed on an end of the sliding board  453  away from the main body  451 , and received in the guiding portion  4317 . In the illustrated embodiments, the first direct portions  4513  are sliding blocks, and the second direct portion  4531  is a sliding rail. 
     The feeding mechanism  47  is mounted in the mounting seat  43 , and includes two drivers  471 . The two drivers  471  are received in the receiving space  4315  and positioned on two sides of the sliding board  453 , respectively. In the illustrated embodiment, the drivers  471  are linear motors. Each driver  471  includes a forcer  4711  and a stator  4713 . Each forcer  4711  is fixed to a surface of each of the mounting boards  433 . The sliding board  453  is positioned between the two forcers  4711 . The forcers  4711  produce alternating magnetic fields when the forcers  4711  are supplied with an alternating electrical current. Two stators  4713  are respectively attached on the opposite surfaces of the sliding board  453 . Each stator  4713  is located between a forcer  4711  and the sliding board  453 . Interactions between magnetic fields produced by the stators  4713  and the alternating magnetic fields which are produced by the forcers  4711  drive the tool holder  45  in a reciprocating motion at a high speed along the direction of the Z-axis. In other embodiments, the number of drivers  471  can be designed according to application. For example, the two drivers  471  can replace a single driver with more power, or three or more drivers can be positioned to drive the tool holder  45  to maximize the available power, and simplify assembly of the drivers. 
     The cutter  49  is clamped between the two holding portions  4511  for machining curved surfaces of the workpiece. 
     In other embodiments, the mounting seat  43  may be attached on the sliding saddle  41  when the lathe  100  machines the workpiece of one type. In other words, the mounting seat  43  does not need to move along the Z-axis direction. A driving mechanism electrically connected with the controller may be positioned in the feeding device  40  to drive the mounting seat  43  to slide along the sliding saddle  41  in the Z-axis. The sliding saddle  41  may be omitted, and the mounting seat  43  can be directly slidably positioned on the cross beam  31 . 
     In other embodiments, the forcers  4711  may be directly installed on the frame  431 . The alternating magnetic fields produced by the forcers  4711  drive the stators  4713 , thereby causing the tool holder  45  to undergo a reciprocating motion at high speed along the guiding portions  4317 . 
     In assembly, the work table  20  is positioned between the two support bodies  13 . The cross beams  31  are installed on the two support bodies  13  via the sliding bases  33 . The first driving mechanism  35  and the second mechanism  37  are mounted on the moving device  30  and elastically connected with the controller. The sliding saddle  41  is also positioned on the cross beam  31 . The two stators  4713  are fixedly mounted on two surfaces of the sliding board  453 . The sliding board  453  passes through the through groove  4318  and slidably connects with the second direct portion  4531 . Each forcer  4711  is installed on one mounting board  433  and received in the mounting seat  43  together with the mounting board  433 . The cutter  49  is fixedly mounted between the two holding portions  4511 . Finally, the feeding device  40  is positioned on the sliding saddle  41  and electrically connected to the controller. 
     In use, the workpiece is placed on the work table  20 . The feeding device  40  moves and arrives at a position above the workpiece. The first driving mechanism  35  drives the moving device  30  to move along the first sliding rails  131  in the X-axis direction, the rotating driver  21  drives the workpiece to rotate, and the cutter  49  is driven to move back and forth at high speed in the Z-axis direction by the drivers  471  for machining the workpiece. The rotating speed of the rotating driver  21 , the speed and the range movement of the cutter  49  are programmed according to cutting required for each machining portion of the workpiece. A three dimensional curved surface will be machined because the cutting removal of the workpiece along the rotating direction in the Z-axis is different. The planar machining path of the cutter  49  is substantially spiral. The feeding device  40  and the work table  20  stop moving, and the moving device  30  returns to the initial position after completing the machining. The workpiece can then be unloaded from the work table  20 . 
     The feeding device  40  is capable of moving along X-axis and Y-axis via the moving device  30  and feeding with high speed in Z-axis for machining three dimensional curved surfaces. Compared with the conventional milling cutter machining, no other process needs to be performed on the workpiece used by the lathe  100  because the cutter  49  is continuously machining in three directions at one time. In addition, the work table  20  is directly driven to rotate by the rotating driver  21 , such that the work table  20  is capable of adjustments with great torsion. 
     While the present disclosure has been described with reference to particular embodiments, the description is illustrative of the disclosure and is not to be construed as limiting the disclosure. Therefore, various modifications can be made to the embodiments by those of ordinary skill in the art without departing from the true spirit and scope of the disclosure, as defined by the appended claims.