Abstract:
A wire guide assembly of the present invention is provided with a working fluid inlet port through which a working fluid flows info the wire guide assembly and a nozzle with a working fluid outlet port which is attached to the wire guide assembly at least during machining and through which the working fluid is allowed to flow out from the wire guide assembly. The working fluid is prevented from flowing out from the wire guide assembly while the interior of the wire guide assembly is being cleaned, thereby enabling cleaning with a high-pressure flow of the working fluid produced in the wire guide assembly.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Field of the Invention 
         [0002]    The present invention relates to a wire guide assembly, and more particularly, to a wire guide assembly that uses a closed nozzle at the time of cleaning. 
         [0003]    Description of the Related Art 
         [0004]    When a wire electrode is fed out, wire residue is produced as it rubs against ail electrode pin or a wire guide. If the wire residue is accumulated in a wire guide assembly, it may hinder wire connection and reduce reliability. Moreover, if the wire residue adheres to the wire guide, the traveling direction of the wire is inclined, so that the machining accuracy is reduced or breakage is induced. Therefore, it is necessary to disassemble and clean the wire guide assembly periodically. However, it requires a large number of man-hours to assemble and clean the wire guide assembly that has a complicated shape. Furthermore, adjustment work such as vertical feed must be tried again, so that the machining accuracy may be reduced by an operational error or the like. Accordingly, the interior is expected to be cleaned without disassembling the wire guide assembly. 
         [0005]    In a technique disclosed in Japanese Patent Application Laid-Open No. 2010-69541, for example, as a prior art technique related to cleaning of various parts of a wire electrical discharge machine, a wire guide assembly is provided inside with a flow passage through which a working fluid is passed. An outlet port is disposed downstream of an electrode pin that easily generates wire residue and upstream of a die guide that is liable to accumulation of the wire residue so that the wire residue generated in the position of the electrode pin can be discharged without being accumulated in the position of the die guide. 
         [0006]    Moreover, in a technique for a wire feed pipe disclosed in Japanese Examined Patent Publication Ho. 2009-166240, a compression gas for wire feed is caused to flow back into the pipe by being fed out with the distal end of the pipe closed. According to this proposed method, wire residue or the like in the pipe is removed in this way. 
         [0007]    In the technique disclosed in Japanese Patent-Application Laid-Open No. 2010-69541, however, it is difficult to remove once adhered wire residue due to a low fluid pressure, although the wire residue can be prevented from being accumulated. Moreover, in order to introduce the technique disclosed in Japanese Patent Application Laid-Open No. 2010-69541, the flow passage roast be newly provided in the wire guide assembly, thus requiring a change in the design of the wire guide assembly. 
         [0008]    In the technique disclosed in Japanese Examined Patent Publication No. 2009-166240, in contrast, the mechanism for wire feed is used directly, so that there is an advantage that the design change, is unnecessary. In consideration of the application of this technique to cleaning of the interior of a wire guide assembly, however, the interior of the wire guide assembly is narrower and more complicated than that of the wire feed pipe, and in addition, contains movable parts. Moreover, the diameter of a die guide hole is so small that it is difficult to apply this technique, which uses a low-viscosity gas for these structural reasons, to the cleaning of the interior the wire guide assembly. 
       SUMMARY OF THE INVENTION 
       [0009]    Accordingly, the object of the present invention is to provide a wire guide assembly capable of cleaning wire residue or the like accumulated in narrow and complicated structural areas without changing its design. 
         [0010]    According to the present invention, a working fluid is poured with a working fluid outlet port of a wire guide assembly closed by a closed nozzle without an opening, thereby producing a high-pressure fluid flow for cleaning in the assembly. According to this method, a passage for the fluid for machining is used, so that it is unnecessary to change the design of the wire guide assembly. Also, since the high-pressure fluid flow is produced by using the working fluid that is more viscous than a gas, wire residue or the like accumulated in even narrow arid complicated structural areas can be cleaned. Moreover, even those spots which cannot be easily reached by the working fluid flow can be cleaned by moving movable parts such as an electrode pin during the cleaning. Furthermore, by providing the side surface of a die guide with a flow passage that connects the inside and outside of the die guide, the working fluid is allowed to easily flow into the die guide, so that finer portions can be cleaned. 
         [0011]    A wire guide assembly according to the present invention, which is provided with a wire passage through which a wire electrode passes, comprises a working fluid inlet port through which a working fluid flows into the wire guide assembly and a nozzle with a working fluid outlet port which is attached to the wire guide assembly at least during machining and through which the working fluid is allowed to flow out from the wire guide assembly, and is characterized in that the working fluid is prevented from flowing out from the wire guide assembly while the interior of the wire guide assembly is being cleaned, thereby enabling cleaning with a high-pressure flow of the working fluid produced in the wire guide assembly. 
         [0012]    The wire guide assembly according to the present invention is characterized in that the nozzle is replaced with a closed nozzle without any opening which opens to the outside while the interior of the wire guide assembly is being cleaned, thereby preventing the working fluid from flowing out from the wire guide assembly. 
         [0013]    The wire guide assembly according to the present invention is characterized in that the working fluid outlet port is closed while the interior of the wire guide assembly is being cleaned, thereby preventing the working fluid from flowing out from the wire guide assembly. 
         [0014]    The wire guide assembly according to the present invention is characterized in that the nozzle is covered by a closed nozzle without any opening which opens to the outside while the interior or the wire guide assembly is being cleaned, thereby preventing the working fluid from flowing out from the wire guide assembly. 
         [0015]    The wire guide assembly according to the present invention is characterized in that the wire passage is provided in a die guide, which comprises a passage through which the working fluid having flowed into the wire guide assembly through the working fluid inlet port is caused to flow into the wire passage. 
         [0016]    The wire guide assembly according to the present invention is characterized by comprising an electrode pin in the wire passage and a movable mechanism for moving the electrode pin and in that the working fluid in the wire passage and the wire guide assembly is stirred by driving the movable mechanism during the cleaning of the interior of the wire guide assembly. 
         [0017]    The wire guide assembly according to the present invention is characterized in that the closed nozzle is attached and detached by a robot. 
         [0018]    According to the present invention, there can be provided a wire guide assembly capable of cleaning wire residue or the like accumulated in narrow and complicated structural areas without changing its design. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    The above and other objects and features of the present invention will be obvious from the ensuing description of embodiments with reference to the accompanying drawings, in which; 
           [0020]      FIG. 1  is a schematic configuration diagram of a lower wire guide assembly (in a normal state) according to one embodiment of the present invention; 
           [0021]      FIG. 2  is a schematic configuration diagram of the lower wire guide assembly (at the time of cleaning) according to the one embodiment of the present invention; 
           [0022]      FIG. 3  is a schematic configuration diagram of an upper wire guide assembly (in the normal state) according to the one embodiment of the present invention; 
           [0023]      FIG. 4  is a schematic configuration diagram of the upper wire guide assembly (at the time of cleaning) according to the one embodiment of the present invention; and 
           [0024]      FIG. 5  is a schematic configuration diagram of a wire electrical discharge machine provided with the wire guide assembly according to the one embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0025]    One embodiment of the present invention will now be described with reference to the accompanying drawings. 
         [0026]      FIG. 1  is a schematic configuration diagram of a lower wire guide assembly according to the one embodiment of the present invention in a normal state. A lower wire guide assembly  1   a  and an upper wire guide assembly  1   b  (described later) are vertically arranged with a workpiece (not shown) therebetween and serve to rectilinearly guide a wire electrode  2 . The lower wire guide assembly  1   a  of the present embodiment is constructed so that a die guide  4   a  is assembled to a nozzle  3   a.  A die hole  5   a  through which the wire electrode  2  is passed is provided at one end of the die guide  4   a,  while a sub-guide  6   a  with a sub-die hole  7   a  for guiding the traveling direction of the wire electrode  2  is secured to an opposite end portion of the die hole  5   a.  The wire electrode  2  is passed through a nozzle hole  8   a  in the nozzle  3   a,  the die hole  5   a,  and the sub-die hole  7   a  as it is guided. 
         [0027]    The lower wire guide assembly la of the present embodiment comprises the nozzle  3   a  and the die guide  4   a,  and a working fluid introduced into the lower wire guide assembly  1   a  through a working fluid inlet port  9   a  is discharged from the nozzle hole  8   a.  The diameters of the die hole  5   a  and the sub-die hole  7   a  are so small that the working fluid can hardly flow out through these holes. 
         [0028]      FIG. 2  is a schematic configuration diagram of a lower wire guide assembly  1   a  at the time of cleaning. In cleaning the lower wire guide assembly  1   a,  the nozzle  3   a  is replaced with a closed nozzle  13   a  without an opening after the wire electrode  2  is removed. If the working fluid is introduced into the lower wire guide assembly  1   a  through the working fluid inlet port  9   a  in this state, the closed nozzle  13   a  is filled with the working fluid. Since there is no outlet port through which the working fluid in the lower wire guide assembly  1   a  is discharged to the outside, the fluid pressure in the lower wire guide assembly  1   a  increases. The working fluid filling the closed nozzle  13   a  with the fluid pressure thus increased circulates in the closed nozzle, thereby cleaning wire residue or the like. 
         [0029]    There is also a method in which the opening (nozzle hole  8 , etc.) of the nozzle  3   a  is stopped to close the outlet port through which the working fluid is discharged, in addition to the above-described method in which, the nozzle  3   a  is removed and replaced with one such as the closed nozzle  13   a  without any opening that opens to the outside. Moreover, there is also another method in which the opening (nozzle hole  8 , etc.) is closed by covering the entire nozzle  3   a  by the closed nozzle  13   a  without, removing the nozzle  3   a.    
         [0030]      FIG. 3  is a schematic configuration diagram of the upper wire guide assembly in the normal state, and  FIG. 4  is a schematic configuration diagram of the upper wire guide assembly at the time of cleaning. The upper wire guide assembly lb of the present embodiment is the same as the above-described lower wire guide assembly la with respect to the flow of the working fluid and the cleaning operation, as well as in configuration, and differs from the latter only in that a jet nozzle  14  with a jet nozzle hole  15  is installed outside a die guide  4   b.  The jet nozzle  14  is used to guide the wire electrode  2  to the lower wire guide assembly la by downwardly jetting the working fluid from the jet nozzle hole  15  at the time of connection of the wire electrode  2 , for example. 
         [0031]    In  FIGS. 1 to 4 , the side surfaces of the die guides  4   a  and  4   b  are provided with flow passages  10   a.  and  10   b,  respectively, which connect the interior of the die guides  4   a  and  4   b  and the outside. Conventionally, the working fluid introduced into nozzles  3   a  and  3   b  is expected to pass through die holes  5   a  and  5   b  with small openings in order to get into the die guides  4   a  and  4   b,  so that a sufficient amount of the working fluid cannot enter the die guides  4   a  and  4   b.  Nevertheless, the flow passages  10   a  and  10   b  that connect the inside and outside of the die guides  4   a  and  4   b  enable a sufficient amount of the working fluid to get into the die guides  4   a  and  4   b  through the flow passages  10   a  and  10   b,  thereby cleaning the interior of the die guides  4   a  and  4   b.    
         [0032]    Moreover, in  FIGS. 1 to 4 , electrode pins  11   a  and  11   b  in the wire passages of the die guides  4   a  and  4   b  are mounted on the shafts of air cylinders  12   a  and  12   b  so that the electrode pins  11   a  and  11   b  can move in conjunction with the movements of the shafts of the air cylinders  12   a  and  12   b.  For example, the working fluid flows into the die guide  4   a  through the flow passage  10   a  in the side surface of the die guide  4   a  while the interior of the lower wire guide assembly  1   a  is being cleaned in the state of  FIG. 2 . The electrode pin  11   a  moves as the air cylinder  12   a  is moved, whereby the working fluid in the die guide  4   a  and the lower wire guide assembly  1   a  is stirred. By doing this, the cleaning effect is improved, so that even those fine portions and the like which cannot be easily reached by the working fluid can be cleaned. 
         [0033]      FIG. 5  is a schematic configuration diagram of a wire electrical discharge machine mounted with the wire guide assembly of the present embodiment shown in  FIGS. 1 to 4 . A wire electrical discharge machine  30  comprises a cleaning necessity determination unit  31 , cutting operation unit  32 , tension sensor  33 , pump  34 , air cylinder  12 , wire connection unit  36 , and machining power supply  37 . An operation for cleaning a wire guide assembly  1  (comprising the lower and upper wire guide assemblies  1   a  and  1   b ) will now be described with reference to  FIG. 5 . 
         [0034]    The wire electrical discharge machine  30  determines the necessity of cleaning of the wire guide assembly  1  by means of the cleaning necessity determination unit  31 . If the cleaning is determined to be necessary by the cleaning necessity determination unit  31 , a controller  40  commands various parts of the wire electrical discharge machine  30  to interrupt machining and sends a command to the cutting operation unit  32  to cut the wire electrode  2 . When the wire electrode  2  is cut, a tension value output from the tension sensor  33  attached to the wire electrode  2  is reduced. If the tension value fails below a predetermined threshold, the controller  40  determines that the cutting of the wire electrode  2  is completed and sends a command to a robot operation unit  50  to replace the nozzles  3   a  and  3   b  with closed nozzles  13   a  and  13   b,  respectively. 
         [0035]    On receiving the command, the robot operation unit  50  removes the nozzles  3   a  and  3   b  and replaces them with the closed nozzles  13   a  and  13   b.  Thereafter, the controller  40  sends a command to the pump  34  of the wire electrical discharge machine  30  to jet the working fluid. As this is done, a command can foe sent to the air cylinders  12   a  and  12   b  fitted with the electrode pins  11   a  and  11   b  to operate them. After the jetting of the working fluid is stopped after the passage of a predetermined cleaning time, the controller  40  sends a command to the robot operation unit  50  to replace the closed nozzles  13   a  and  13   b  with the nozzles  3   a  and  3   b,  respectively. The robot operation unit  50  removes the closed nozzles  13   a  and  13   b  and replaces them with the nozzles  3   a  and  3   b.    
         [0036]    Thereafter, the controller  40  sends a command to the wire connection unit  36  of the wire electrical discharge machine  30  to connect the wire electrode  2 . If the tension value of the tension sensor  33  attached to the wire electrode  2  exceeds a threshold, the controller  40  determines that the connection of the wire electrode  2  is completed and sends a command to the machining power supply  37  to resume feed machining. 
         [0037]    By the operations described above, a series of cleaning operations can be automatically performed. The robot operation unit  50  may also be used to stop the opening (nozzle holes  8 , etc.) of the nozzles  3   a  and  3   b  or cover the entire nozzle  3   a  by the closed nozzle  13   a  without removing the nozzle  3   a,  in the above-described manner. 
         [0038]    While an embodiment, of the present invention has been described herein, the invention is not limited to the above-described embodiment and may be suitably modified and embodied in various forms.