Abstract:
The frame of a machine tool forms a closed force loop design that surrounds a workzone containing the spindle head. The X, Y, and Z-axis drive systems are all mounted outside of the machine to shield them from contamination and debris generating during the machining process, and for ease of maintenance without having to enter the machine or remove workzone covers to access them. The X and Y-axis drives are mounted on stationary parts of the machine, eliminating the need for flexible cables to power and control these drives and reducing the mass of the moving elements of the machine.

Description:
FIELD OF THE INVENTION 
     A machine tool has drive motors, drive elements and linear feedback for the X, Y, and Z-axis drives positioned so that they are on the exterior or perimeter of the machine for maintenance and repair purposes, and to keep these elements outside of the workzone. 
     BACKGROUND OF THE INVENTION 
     Machining operations performed by a machine tool result in a large amount of coolant and machining debris to be thrown around by the working tool. Drive motors and ways for the X, Y, and Z axis of the machine that are located in the workzone are protected from contamination by sealed workzone covers. When maintenance or replacement of the drive motors or ways is required, personnel have to enter the wet and dirty workzone and remove the workzone covers, breaking the seals. When maintenance is completed, the workzone covers have to be replaced and resealed. It would be desirable for the X, Y, and Z axis drive motors and ways to be located on the exterior or perimeter of the machine so that they could be maintained and serviced without requiring the operator to enter the machine itself or the workzone and remove workzone covers in order to have access to these elements. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         FIG. 1  is a perspective view of a machine tool according to the invention. 
         FIG. 2  is a simplified view of the machine tool of  FIG. 1  showing the X, Y, and Z elements of the machine tool. 
         FIG. 3  is a sectional view taken along lines  3 - 3  of  FIG. 1  showing the Y-axis column and other elements of the machine tool. 
         FIG. 4  is a perspective view partly broken to show the X-axis frame members, the back of the pallet receiver and the X-axis drive. 
     
    
    
     BRIEF SUMMARY OF THE INVENTION 
     The X, Y, and Z-axis drive motors are all mounted on the exterior or perimeter of the machine to shield them from contamination and debris generating during the machining process, and to permit maintenance without having to enter the machine or remove workzone covers in order to have access to them. The X-axis drive is shielded from the workzone by an X-axis wall that is positioned between the X-axis drive and the workzone. The Y-axis drive motors and ways are mounted on the Y-axis column on the opposite side of the Y-axis column from the workzone. The Z-axis drive and ways are mounted on a saddle on the opposite side of the Y-axis column from the workzone. All of the X, Y, and Z-axis drive systems are removable from the machine from outside of the perimeter of the machine. The design and positioning of the X and Y-axis drives allows them to be mounted on a stationary part of the machine, eliminating the need for flexible cables to power and control these drives, and reduces the mass of the moving elements of the machine. 
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a machine tool generally designated by the reference numeral  10 . The machine tool is surrounded by standard guarding  12 , and an operator station  14  is positioned outside of the guarding. The machine tool receives a pallet  16  from the pallet support plate  15  of a pallet manipulator  18  that may be positioned on the side of the machine tool. The pallet will normally have a workpiece  17  clamped to it as shown in  FIG. 2 . In operation, the pallet  16  is transferred from the pallet manipulator  18  to a pallet receiver  19  positioned inside of the guarding. The machine then drives the pallet receiver  19  to the working zone of the machine tool in front of the working tool. 
       FIG. 2  shows the X, Y, and Z-axis elements of the machine tool. A pallet with a workpiece is positioned in front of a spindle or multi-axis head  21  that carries the working tool  22  and this establishes a workzone. The Y-axis column  24  is fixed and is bifurcated. As shown in  FIG. 2  and also in  FIG. 3 , the Y-axis column  24  carries a vertically movable saddle  25  that is mounted on vertical linear guides or ways  26 . A servomotor  27  is mounted on each side of the Y-axis column  24 , and each servomotor  27  is coupled to a drive screw  28 . The drive screws  28  engage drive nuts  29  on opposite sides of the saddle  25 , and the servomotors  27  are used to raise and lower the saddle to the desired vertical position. 
     Upper and lower Y-axis covers  30  and  31 , respectively, are mounted on the side of the Y-axis column  24  that is closest to the workzone. The covers close the opening  33  in the bifurcated column and prevent coolant and machining debris generated in the workzone from passing through the opening  33 . Although the covers  30  and  31  are shown as roll type covers, other cover arrangements such as telescoping or sliding panels as well known in the art may be used to cover the opening  33  above the Z-axis slide  32  and below the saddle  25 . The covers  30  and  31  adjust to accommodate the vertical position of the slide  32  and the saddle  25 . The covers  30  and  31  work together to form a Y-axis shield. The servomotors  27 , the drive screws  28 , the drive nuts  29 , and the Y-axis ways  26  are all located on the opposite side of the column  24  from the working tool  22  and are on the outside of the machine. As a result, the motors  27 , drive screws  28 , drive nuts  29 , and Y-axis ways  26  can all be removed from the machine without having to disturb seals or Y-axis covers. Because the drive elements for the saddle  25  are mounted on the column  24  which is stationary, the mass of the moving parts of the Y-axis drive for the machine is reduced. The term “outside of the machine” as used herein does not mean outside of the guarding  12  of the machine, but rather outside of or on the perimeter of the X, Y, and Z-axis elements of the machine. 
     The vertically movable saddle  25  carries a Z-axis slide  32  that is mounted on one or more Z-axis ways  39 . A Z-axis drive assembly comprises a servomotor  34  and a drive screw  35  that are mounted on the Z-axis saddle  25 . The Z-axis drive assembly may be selectively controlled to position the Z-axis slide  32  and the working tool  22  in the desired position along the Z-axis. The Z-axis drive motor  34  is placed on the opposite side of the Y-axis column  24  from the working tool  22  in the workzone. This allows the removal of the Z-axis slide  32  and the Z-axis drive motor  34  from the outside of the machine for maintenance purposes, and positions the Z-axis servomotor  34  and drive screw  35 , and the Z-axis ways  39  outside of the machine, and shielded by the Y-axis covers  30  and  31  from coolant and other debris that are scattered during a machining operation. 
     X-axis frame members  40  and  48  support an X-axis wall which extends along the back of the workzone. A plurality of X-axis rails  41  are mounted on the wall  45 . The pallet receiver  19  is mounted on the X-axis rails  41  for horizontal movement along the X-axis. The pallet receiver carries a vertically mounted pallet  16  on which a workpiece  17  may be mounted. One or more X-axis drive motors  44  shown in phantom are used to drive the pallet receiver back and forth along the X-axis rails. The X-axis frame member  40  is coupled to the Y-axis column by upper and lower tubular frame members  46  and  47 , respectively. 
       FIG. 3  shows certain elements of the machine in greater detail. The two Y-axis ways  26  that guide the vertical movement of the saddle  25  are positioned on the bifurcated column  24  on either side of the saddle. Two Y-axis flexible cable guides  52  are provided to carry electrical and hydraulic cables and the like from the stationary part of the Y-axis column to the movable saddle  25 . A Z-axis flexible cable guide  53  is provided to carry electrical and hydraulic cables from the saddle  25  to the Z-axis slide  32 .  FIG. 3  shows the X-axis rails  41  that extend from one side of the machine to the other to support the pallet receiver  19  and to position the workpiece in front of the working tool  22 . The pallet receiver  19  is centered in front of the Y-axis column  24 . 
       FIG. 4  is a perspective view of the back of the machine tool showing the X-axis frame members  40  and  48  that support the X-axis rails  41 . The X-axis drive motors  44  are mounted on an X-axis wall  45  that is supported by the X-axis frame members  40  and  48 . The X-axis wall  45  extends from one side of the machine to the other, and shields the X-axis drive motors  44  from coolant and other machining debris that are generated in the workzone. The output shafts of the drive motors are provided with pinion gears  49 . The pinion gears are engaged with an elongated rack  50  on the rear face of the pallet receiver  19 . The pallet receiver may be driven back-and-forth across the X-axis frame members by the X-axis drive motors  44 . In the embodiment shown, two X-axis drive motors are used, although other drive configurations are possible. 
     Because the X-axis drive motors  44  are positioned on the X-axis wall  45  on the outside of the machine tool, the X-axis drive motors do not have to be shielded from the workzone debris by workzone covers. Further, the X-axis drive motors  44  are removable from the outside of the machine without the requirement for maintenance personnel to enter the workzone or remove workzone covers in order to have access to these elements. Additionally, positioning the X-axis drive motors  44  on a stationary part of the machine reduces the mass of the moving X-axis elements of the machine. 
     Having thus described the invention, various alterations and modifications may be apparent to those skilled in the art, which modifications and alterations are intended to be within the scope of the invention as defined by the appended claims.