Abstract:
There is provided a deep hole processing device for forming a hole by rotational movement of a main spindle to which a tool is attached of a portal machine toward a workpiece, having, a bush having a hole diameter for guiding rotational movement of the tool, and a bush holding unit provided on a cross rail capable of moving on columns of the portal machine for holding the bush with respect to a spindle head on which the main spindle is mounted at a predetermined distance, wherein a position of the bush relative to the workpiece and a pressure at which the bush is pressed against the workpiece may be controlled by movement of the cross rail.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims benefit of priority under 35 USC 119 from the Japanese Patent Application No. 2010-59386, filed on Mar. 16, 2010, the entire contents of which are incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     The present invention relates to a deep hole processing device like a machine tool for drilling. 
     2. Related Art 
     Deep hole processing is making a hole with a large ratio between depth and diameter. In deep hole processing, common processing systems include a gun drill system, a boring and trepanning association (BTA), system and an ejector system. 
     Deep hole processing tools are typically long and have relatively small diameters relative to their lengths. Therefore, it is difficult to perform of high accuracy processing due to bending and buckling of the tool and rotational deflection of the tool during attachment. 
     Therefore, conventionally, as illustrated in  FIG. 9A , a pilot hole  101  is provided in advance on a workpiece  158  using a short tool and a deep hole is processed using a long tool using the pilot hole as a guide. As illustrated in  FIG. 9B , a guide pad  119  provided on an outer periphery of a long tool  108  in a slightly projected manner is brought into contact with the pilot hole  101 . Then, as illustrated in  FIG. 9C , the processing is performed by a blade  118  provided on a tip end of the tool  108 . Alternatively, a bush guide is attached to the processing device and the hole processing is performed using the bush guide as the guide. An example of the conventional deep hole processing device is hereafter described in Japanese Patent Application Laid-Open No. S62-24203 
     However, when providing the above-described pilot hole, advance processing using the short tool is required, thereby resulting in low work efficiency. Also, when performing the processing using the bush guide, a mechanism to press the bush guide against the workpiece is required and it is problematically difficult to use a general-purpose machine. 
     SUMMARY OF THE INVENTION 
     The present invention is achieved in view of the above-described circumstances, and an object thereof is to provide a deep hole processing device capable of realizing deep hole processing of high accuracy using a general-purpose machine without necessity of processing a pilot hole. 
     According to the present invention, there is provided a deep hole processing device for forming a hole by rotational movement of a main spindle of a portal machine to which a tool is attached toward a workpiece, comprising, a bush having a hole diameter for guiding rotational movement of the tool, and a bush holding unit provided on a cross rail capable of moving on the columns of the portal machine for holding the bush with respect to a spindle head on which the main spindle is mounted at a predetermined distance, wherein a position of the bush relative to the workpiece and a pressure at which the bush is pressed against the workpiece may be controlled by movement of the cross rail. 
     According to the deep hole processing device of the present invention, time and effort to process the pilot hole is not necessary and high accuracy deep hole processing becomes possible using the general-purpose machine. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view of a schematic configuration of a general-purpose portal machine used in a deep hole processing device according to an embodiment of the present invention; 
         FIG. 2  is a front view of a configuration in the vicinity of a main spindle of the deep hole processing device according to the same embodiment; 
         FIG. 3  is a front view illustrating a configuration of a guide rail and a slider for supporting a discharge side hose in the deep hole processing device according to the same embodiment; 
         FIG. 4  is a front view illustrating a structure of a bush in the deep hole processing device according to the same embodiment; 
         FIG. 5  is a front view of a configuration of a variation of a bush holding unit in the deep hole processing device according to the same embodiment; 
         FIG. 6  is a front view of a configuration of a variation of the bush in the deep hole processing device according to the same embodiment; 
         FIGS. 7A to 7F  are illustrative diagrams of a procedure to perform deep hole processing using the deep hole processing device according to the same embodiment; 
         FIGS. 8A and 8B  are illustrative diagrams of an action of the bush in the deep hole processing device according to the same embodiment; and 
         FIGS. 9A to 9C  are illustrative diagrams of an example of a procedure of a conventional deep hole processing. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Hereafter, a deep hole processing device according to an embodiment of the present invention will be described with reference to the drawings. 
       FIG. 1  illustrates an overall schematic configuration of a deep hole processing device according to this embodiment in a state in which a bush and a bush holding unit are attached to a general-purpose portal machine. 
     A column  51  is provided so as to move on a bed  61  forward and backward in a direction perpendicular to a plane of paper. 
     A cross rail  52  is provided so as to vertically move on the column  51 . 
     A spindle head  1  is provided so as to horizontally move on the cross rail  52 . The spindle head  1  is provided with a ram  2  to be described later inside thereof, and a main spindle for rotating a tool is built in the ram  2 . A rotary joint  3  is connected to the main spindle. 
     A bush holding unit  11  to be described later is connected to a lower portion of the spindle head  1  so as to cover the rotary joint  3  and the ram. By the horizontal movement of the spindle head  1  on the cross rail  52 , the bush holding unit  11  may horizontally move to positions indicated by reference numerals  11 A and  11 B. 
     A workpiece  58  to which deep hole processing is performed is fixed on a surface plate  59  by a jig  60  and the like. 
     The cross rail  52  moves downward and stops when a bush  9  to be described later is brought into contact with the workpiece  58  and a predetermined pressure is applied thereto. Thereafter, the rotary joint  3  connected to the main spindle built in the ram  2  to be described later moves downward toward the workpiece  58  while rotating, thereby performing the processing. 
       FIG. 2  illustrates a principal configuration in the vicinity of the main spindle of the deep hole processing device according to this embodiment. 
     The spindle head  1  is provided as a part of the portal machine so as to be movable in a horizontal direction in the drawing as illustrated with reference to  FIG. 2 . 
     The ram  2  is arranged as a part of the portal machine so as to be able to be built in the spindle head  1  and is vertically movable relative to the spindle head  1 . Further, a main spindle  17  is mounted in the ram  2  and is vertically movable relative to the spindle head  1  similarly. 
     The rotary joint  3  is connected to the main spindle  17 , a rotary main spindle and a bearing for supporting the rotary main spindle not illustrated are provided in the rotary joint  3 , and the rotary main spindle and a tool  8  are coupled to each other. By vertical movement of the ram  2  with the built-in main spindle  17 , the rotary joint  3  may vertically move as indicated by reference numerals  3 A and  3 B. 
     Further, the rotary joint  3  has a function as a flow passage of cutting oil to the tool  8 . An oil supplying hose  4  is connected to the rotary joint  3  to supply the cutting oil. The tool  8  is a so-called ejector-type and is provided with a double tube structure with an outside outer tube and an inner tube inside thereof. The cutting oil supplied from the rotary joint  3  is transmitted between the outer tube and the inner tube to flow downward toward the workpiece. A tip end of the tool  8  cuts the workpiece and a chip is pushed upward in the inner tube together with the cutting oil. 
     A flexible tube  15  is further connected to the rotary joint  3  by a joint  6  and a discharge side hose  5  is further mounted thereon by a joint  7 . The chip and the cutting oil pushed in the inner tube of the tool  8  pass through the discharge side hose  5  through the rotary joint  3  to be discharged to outside. 
     The flexible tube  15  and the discharge side hose  5  pass through a hole  16  on a sliding plate  14  as illustrated in  FIG. 3  and are vertically movable following vertical movement of the tool  8  by vertical sliding of a discharge tube holding unit  21  on a guide rail  13 . The flexible tube  15  and the discharge side hose  5  may be attached to and detached from the rotary joint  3  as necessary. 
     Since the flexible tube  15  and the discharge side hose  5  are held by the sliding plate  14  provided with the discharge tube holding unit  21 , which vertically slides on the guide rail  13 , in this manner, it is possible to prevent a load and rotation moment generated by the flexible tube  15  and the discharge side hose  5  from being applied only to the rotary joint  3 . Almost entire load is directly held by the ram  2  through a rotation stopping plate  20 . 
     Meanwhile, it is not required that the sliding plate  14  necessarily has the hole  16 , and it may have a structure capable of supporting the flexible tube  15  and the discharge side hose  5 . It is also possible to use a discharge tube in place of the discharge side hose  5 . 
       FIG. 4  illustrates an example of a configuration of the bush  9 . The bush  9  is configured to guide the tool  8  during the processing and acts as replacement for a pilot hole as described later. 
     The bush  9  is mounted on the spindle head  1  by the bush holding unit  11  and vertically moves together with vertical movement of the spindle head  1 . 
     The bush  9  has an inner diameter  4  set to be identical to a drill diameter of the tool  8  or to be larger than the drill diameter within an allowable accuracy range, and is replaced according to the drill diameter of the tool  8  to be used to be attached to the bush holding unit  11 . 
     A pressure sensor  10  is mounted on a portion, which is brought into contact with the workpiece, on a tip end of the bush  9 . 
     The bush holding unit  11  illustrated in  FIG. 2 , which is configured to fasten the bush  9  to the spindle head  1  by some means such as a bolt, may be replaced with another bush holding unit as necessary on an attaching surface  12  of the spindle head  1 . 
     The bush holding unit  11  has a case-like structure to enclose the rotary joint  3 , the tool  8  and the ram  2  and has a longitudinal dimension so as not to prevent a maximum distance of the vertical movement of the rotary joint  3 .  FIG. 2  illustrates box shape of which cross section is square of the case-like structure as an example of the bush holding unit  11 . Meanwhile, the cross section of the bush holding unit  11  may be other than square. However, it is not required that the bush holding unit  11  necessarily has such case-like structure, and the shape is not limited and may be variously changed. For example, as illustrated in  FIG. 5 , the bush holding unit, which may press the bush  9  against the workpiece by fastening the bush  9  to the spindle head  1  with a predetermined distance therebetween, may be used. For example, although the bush  9  is fastened to the spindle head  1  by one member in  FIG. 5 , they may be fastened to each other by a plurality of members. Also, although one bar-like member is taken as an example in  FIG. 5 , a plurality of bar-like members may also be used. Also, the member is not limited to the bar-like member. 
     Also, the structure, an outer diameter and a shape of the bush  9  may be variously changed if the bush  9  has the inner diameter  4  identical to or slightly larger than the drill diameter of the tool  8 . 
     For example, as illustrated in  FIG. 6 , the bush  9  may have a structure composed of a plurality of parts such as two parts, which are a bush fixture  9 A and a bush  9 B. In this case, the bush  9 B is housed in the bush fixture  9 A and an inner diameter  4 ) of the bush  9 B is identical to or slightly larger than the drill diameter of the tool  8 . The bush fixture  9 A is attached to the bush holding unit  11 . By replacing the bush  9 B according to the drill diameter of the tool  8 , it becomes not necessary to replace the bush for the bush holding unit  11  and it becomes easy to use the tool  8  with different drill diameter. 
     A procedure to perform the hole processing using the deep-hole processing device according to this embodiment is described with reference to  FIGS. 7A to 7F . 
       FIG. 7A  illustrates the vicinity of the main spindle of the general-purpose portal machine at a stage at which the rotary joint  3  and the tool  8  are not attached. As described with reference to  FIG. 1 , the ram  2  is provided so as to be able to be built in the vertically movable spindle head  1 , and the main spindle  17  is mounted in the ram  2 . 
     As illustrated in  FIG. 7B , the rotary joint  3  to which the tool  8  is attached is attached to the main spindle  17  in the ram  2 . 
     As illustrated in  FIG. 7C , the bush holding unit  11  to which the bush  9  having the inner diameter identical to or slightly larger than the drill diameter of the tool  8  corresponding to a diameter of a hole to be processed is attached is attached to the attaching surface  12  of the spindle head  1 . 
     As illustrated in  FIG. 7D , the oil supplying hose  4  and the discharge side hose  5  are attached to the rotary joint  3 . 
     As illustrated in  FIG. 7E , the cross rail  52  is lowered, thereby moving the spindle head  1  downward to press the bush  9  against a machined surface of the workpiece  58 . At that time, when the pressure sensor  10  provided on the tip end of the bush  9  detects a pressure not smaller than a predetermined value, the movement of the cross rail  52  is stopped and pressing of the bush  9  against the workpiece  58  is stopped. 
     As illustrated in  FIG. 7F , by rotating the main spindle  17  of the spindle head  1  while supplying the cutting oil from the oil supplying hose  4 , the ram  2  is lowered in a direction indicated by an arrow to perform the hole processing. 
     The cutting oil supplied from the oil supplying hose  4  flows between the outer tube and the inner tube of the tool  8  to be supplied to the tip end of the tool  8 , and pushed upward in the tube together with the chip to be discharged to outside through the discharge side hose  5 . 
     As described with reference to  FIGS. 9A to 9C , it is conventionally required that the hole processing is performed by providing the pilot hole on the workpiece in advance, bringing a guide pad fitted to a part of an outer peripheral surface of the tool in a projected manner into contact with the pilot hole and using the portion as a guide. On the other hand, such pilot hole is not necessary according to the deep hole processing device of this embodiment. 
     As illustrated in  FIG. 8A , the bush  9  is pressed against the machined surface of the workpiece  58  without the pilot hole at a predetermined pressure as described with reference to  FIG. 7E . The processing is started in a state in which a guide pad  19  of the tool  8  is brought into contact with an inner peripheral surface of the bush  9 . According to this, the bush  9  acts as the pilot hole and the hole processing is started using the guide pad  19 , which is brought into contact with the bush  9 , as the guide. 
     As illustrated in  FIG. 8B , the tool  8  cuts the workpiece  58  as the ram  2  lowers. The guide pad  19  of the tool  8  passes through the bush  9  and is brought into contact with an inner wall of a processed hole, and the processing is further performed by using the same as the guide. 
     As described above, according to the deep hole processing device according to this embodiment, the processing of the pilot hole is not necessary and highly efficient processing of the deep hole of high accuracy becomes possible by using the general-purpose portal machine without a dedicated machine. 
     Meanwhile, an ejector drill is used as the tool  8  in this embodiment. However, the tool, which may be used, is not limited to this, and all the tools for processing by using the guide such as a BTA and a gun drill may be used. 
     The above-described embodiment is merely an example and this does not limit the present invention, and this may be variously changed within the technical scope of the present invention.