Abstract:
A tool magazine of an automatic tool changer applicable to a machine tool, comprises a magazine body and a plurality of tool holders each being slidably attached to the magazine body and holding a tool head. The tool magazine is characterized by that the tool magazine includes a tool-delivering mechanism for delivering the tool holder that holds the tool to a predetermined position away from the magazine body and disengaging the tool from the tool holder.

Description:
BACKGROUND OF THE INVENTION 
   1. Technical Field 
   The present invention relates to an automatic tool changer of a machine tool, and more particularly, to a tool magazine of an automatic tool changer applied to a machine tool. 
   2. Description of Related Art 
   An ATC (Automatic Tool Changer) is typically provided to a machine tool to significantly improve the efficiency of the machine tool by saving time in moving, switching, installing and storing tools as well as adjusting and calibrating the machine tool. That is to say, the reliability as well velocity of an ATC can directly affect the efficiency of a machine tool it serves and thus are usually taken as the major index for design, selection and evaluation of an ATC. 
   The conventional ATC generally has a tool magazine for storing tools and an automatic tool-changing arm simultaneously holding and exchanging a tool to be replaced as well as another tool to be assembled to a machine tool. Traditionally, for providing accessibility to the automatic tool-changing arm, the tool magazine is arranged beside the machine tool. However, the tool magazine attached to a lateral of the machine tool can lead to machine vibration due to asymmetric balance of the entire machine tool and therefore brings an additional need of a balance weight. Besides, the traditional tool magazine is limited in its volume and capacity otherwise it can not be properly arranged beside the machine tool. 
   Hence, a need exists for providing an automatic tool changer with a tool magazine that does not cause asymmetric balance of an entire machine tool and is free from limitations in its volume as well as capacity. 
   SUMMARY OF THE INVENTION 
   In view of the aforementioned need, the present invention provides a tool magazine for an automatic tool changer that comprises improved tool holders and an extendable tool delivering device. 
   One objective of the present invention is to provide a tool magazine for an automatic tool changer that serves to deliver a tool to an automatic tool-changing arm of the automatic tool changer so that the tool magazine can overcome the limitation of the tool-changing arm and be settled behind a machine tool, thereby preventing asymmetric balance of the entire machine tool. 
   Another objective of the present invention is to provide a tool magazine for an automatic tool changer that is settled behind a machine tool, and is free to extend and is possible to provide an enhanced capacity according to practical needs. 
   Another objective of the present invention is to provide a tool magazine for an automatic tool changer that holds tools more stably and discharges the tools therefrom more smoothly so as to efficiently enhance the efficiency of the automatic tool changer. 
   Still another objective of the present invention is to provide a tool magazine for an automatic tool changer that has a compact design that frees the cylinder from interruption of air tubes and allows the cylinder to move smoothly. 
   To achieve these and other objectives of the present invention, the disclosed tool magazine comprises a magazine body and a plurality of tool holders each being slidably attached to the magazine body and holding a tool head. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: 
       FIG. 1  is a perspective view of a tool holder of the present invention and a tool head assembled; 
       FIG. 2  is an exploded view of the tool holder and the tool head of  FIG. 1 ; 
       FIG. 3  is a cross-sectional view of the tool holder, showing the tool head retained thereon; 
       FIG. 4  is another cross-sectional view of the tool holder, showing the tool head disassembled therefrom; 
       FIG. 5  is an oblique top elevation of a tool magazine of the present invention; 
       FIG. 6  is an oblique bottom elevation of the tool magazine of the present invention; 
       FIG. 7  is an exploded view of the tool magazine of the present invention; and 
       FIG. 8  is a schematic drawing showing the tool magazine, in cooperation with an automatic tool-changing arm, serving to a machine tool for changing tools. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Please refer to  FIGS. 1 to 3  for a preferred embodiment of a tool holder  10  of the present invention assembled with a tool head  70 . Therein, the tool holder  10  comprises a housing  11 , a tool seat  13  providing at a lower end of the housing  11 , and a movable shaft  15  axially passing through the housing  11  and the tool seat  13 . 
   The housing  11  is substantially formed as a hollow column with a groove  111  provided thereon for being engaged with a rail  21  of a magazine body  20 . An accommodating space is axially formed in the housing  11  and has an upper portion thereof defined as a first shaft-receiving portion  112  fittingly accommodating the movable shaft  15  and a lower portion thereof defined as an expanded seat-receiving portion  113  opened to the lower end of the housing for accommodating the tool seat  13 . Besides, a guiding pin hole  114  is formed on the housing  11  corresponding to the first shaft-receiving portion  112  and diverging from an axis of the housing  11  so that the guiding pin hole  114  has a part thereof communicated with the first shaft-receiving portion  112 . 
   The tool seat  13  is also formed as a column and has a flange  131  to be coupled with an upper edge of the seat-receiving portion  113  of the housing  11 . Below the flange  131 , the tool seat  13  is formed with a contracted periphery  133  that embraces a second shaft-receiving portion  134  that has an relatively contracted upper section and a relatively extended lower section both communicating with the first shaft-receiving portion  112  of the housing  11 . The periphery  133  has a plurality of radially extended ball channels  135  corresponding to the extended lower section of the second shaft-receiving portion  134  wherein each of the ball channels  135  receives a ball  136 . As the ball channel  135  is formed as an outward tapered channel, along the ball  136  sliding along in ball channel  135 , it can slide inward to enter the second shaft-receiving portion  134  and it can slide outward to a limit position where it is retained by an opening of the channel  135 , wherein when the ball  136  is at the limit position, it partially jut out the opening. In other words, the ball  136  is moveable between jutting out and retracting from the periphery  133 . 
   The movable shaft  15  has an upper end and a lower end thereof radially expanded. The upper end is formed with a first guiding surface  151  which is a plane provided with a slanted guiding groove  152 . The lower end is formed with a ball receiving section  153  and a ball propping section  154 . The ball propping section  154  has a diameter matching a diameter of the extended lower section of the second shaft-receiving portion  134  while the ball receiving section  153  and the ball propping section  154  are connected with an arched surface  155 . 
   A guiding pin  17  is movably settled in the guiding pin hole  114  on the housing  11  and has a second guiding surface  171  whereon a slanted guiding ridge  172  matching the slanted guiding groove  152  on the first guiding surface  151  of the movable shaft  15  is formed. 
   Thereby, when the tool holder  10  are assembled, the upper end of the movable shaft  15  is received in the first shaft-receiving portion  112  and has its first guiding surface  151  corresponds to the guiding pin hole  114  while having its slanted guiding groove  152  with one end thereof engaged with the of the guiding pin  17 . The ball receiving section  153  at the lower end of the movable shaft  15  now has its upper end abuts the upper edge of the second shaft-receiving portion  134  of the tool seat  13 . At this time, the ball propping section  154  is positioned to align with the ball channels  135 . Since the diameter of the ball propping section  154  matches that of the second shaft-receiving portion  134 , the balls  136  are propped out from the ball channels  135  so that each said ball  136  has its partial surface jutting out the contracted periphery  133  of the tool seat  13 . Meanwhile, a tool head  70  has a circular flange formed therein retained by the flange  131  of the tool seat  13  and the surfaces of the balls  136 , thereby being fastened below the tool holder  10 . 
   Referring to  FIG. 4 , when the guiding pin  17  is pushed inward in the guiding pin hole  114  from he exterior of the housing  11 , the guiding ridge  172  slides inward and get engaged with the guiding groove  152  of the movable shaft  15 . Since the guiding ridge  172  and the guiding groove  152  are correspondingly slanted, the horizontal (radial) movement of the guiding pin  17  drives the vertical (axial) movement of the movable shaft  15  so as to lead the movable shaft  15  vertically move downward along the first shaft-receiving portion  112  and the second shaft-receiving portion  134 . Therefore, when the ball propping section  154  moves downward, the ball receiving section  153  comes to align with the ball channels  135 , so the balls  136  return into the ball channels  135  from the periphery  133  of the tool seat  13  and stop before the arched surface  155  below the ball receiving section  153 . Thus, the surfaces of the balls  136  leave the periphery  133  of the tool seat  13  so that the tool head  70  previously retained by the surfaces of the balls  136  can be separate from the tool holder  10  through the lower end if the second shaft-receiving portion  134 . 
   The disclosed tool holder  10  is beneficial by its capability of stably holding a tool. Also, the disclosed tool holder  10  can easily disengage a tool with simple yet effective mechanism. Therefore the disclosed tool holder  10  presents enhanced reliability and stability. 
   The tool magazine of the present invention further comprises a magazine body  20 , as shown in  FIGS. 5 and 6 . The magazine body  20  has a rail  21  for positioning the previously discussed tool holder  10 . The rail  21  is driven by a motor  22  so that the tool holders  10  hanged thereon can move along the rail  21  and be delivered to a tool-delivering position. In  FIGS. 6 and 7 , it can be seen more clearly that the magazine body  20  further has a tool-delivering mechanism that comprises a tool-delivering extension  25 , a sliding rail assembly  23 , an extending cylinder  27 , a tool-disengaging cylinder  28  and a telescopic gas pipe set. 
   The tool-delivering extension  25  comprises a movable rail segment  251  matching the rail  21  and forming an circular rail in the presence of the rail  32 . The movable rail segment  251  has a driven arm  252  extended therefrom toward a center of the magazine body  20 . 
   The sliding rail assembly  23  is composed of a guiding rail  231  fixedly attached below a lower surface of the magazine body  20  and a sliding rail  232  mounted around the guiding rail  231 . The sliding rail  232  has its front end fixedly connected with the driven arm  252  of the tool-delivering extension  25  so that when the sliding rail  232  performs an extension with respect to the guiding rail  231 , the tool-delivering extension  25  is supported by the sliding rail  232  to slide outward smoothly and makes the movable rail segment  251  attached thereon departed from the rail  32  of the magazine body  20 . 
   The extending cylinder  27  serves to provide a driving force to move the tool-delivering extension  25  and the sliding rail assembly  23 . The extending cylinder  27  is settled outside the sliding rail  232  and fixedly attached to the lower surface of the magazine body  20 . The extending cylinder  27  has a shaft end fixedly connected with the driven arm. The extending cylinder  27  may be a normal power cylinder, such as a hydraulic cylinder or an air cylinder. 
   The tool-disengaging cylinder  28  is fixedly attached outside the movable rail segment  251  of the tool-delivering extension  25  and has its driving shaft settled forward the interior of the movable rail segment  251  so as to correspond to the guiding pin hole  114  of one said tool holder  10 . The tool-disengaging cylinder  28  may be a normal air cylinder. 
   The telescopic gas pipe set includes an outer pipe  29  mounted outside the sliding rail  232  and fixedly fastened to the lower surface of the magazine body  20  and an inner pipe  291  fixedly connected to the driven arm  252  and communicated to the tool-disengaging cylinder  28 . Therein, the outer pipe  29  and the inner pipe  291  are relatively extendable in respond to the movement of the tool-delivering extension  25 . The telescopic gas pipe set is communicated to a high-pressure air source for providing the driving force to the tool-disengaging cylinder  28 . 
   Thereby, the tool-delivering mechanism normally forms a closed circular rail together with the rail  21  and the movable rail segment  251 . Each said tool holders  10  with its groove  111  engaged with the rail and is driven by the motor  22  to move along the rail. When tool change is required, a specific tool  70  is delivered to the tool-delivering position. Namely, when the specific tool  70  arrives the movable rail segment  251  of the tool-delivering extension  25 , the motor  22  stops so that the tool  70  is positioned in the movable rail segment  251 . At this time, the extending cylinder  27  is started and its shaft  271  drives the driven arm  252  of the tool-delivering extension  25  so that the driven arm  252  radially extends with respect to the magazine body  20 . Consequently, the tool-delivering extension  25  fixedly connected to the sliding rail  232  and the tool  70  thereon are moved outward synchronously, so as to draw the sliding rail  232  of the sliding rail assembly  23  to extend from the guiding rail  231 , thereby providing the tool-delivering extension  25  leaving the magazine body  20  with a reliable supporting force. In addition, since the inner pipe  291  of the telescopic gas pipe set is also fixedly connected with the tool-delivering extension  25 , it also performs extension with respect to the outer pipe  29 . 
   When the tool-delivering mechanism extends to a predetermined position, as shown in  FIG. 8 , where the tool-delivering extension  25  delivers the tool  70  to a position corresponding to an tool-changing arm  80 , a high-pressure air is sent to the tool-disengaging cylinder  28  though the outer pipe  29  and the extended inner pipe  291 . After the tool-disengaging cylinder  28  is started, it pushes the guiding pin  17  settled in the guiding pin hole  114  of the tool holder  10 , so that the guiding pin  17 , as previously described, drives the movable shaft  15  in the tool holder  10  to move downward and then the balls stop retaining the tool  70 , thereby freeing the tool  70  from the tool holder  10 . The dropped tool  70  is well retained and exchanged with another tool ( 70 ′) to be disassembled from the machine tool by the tool-changing arm  80  so as to accomplish required tool change. 
   The primary advantage of the tool-delivering mechanism is being free from the limitation of the position of the tool-changing arm so as to be installed behind he machine tool, thereby preventing the asymmetric balance of the entire machine tool. 
   Besides, the sliding rail assembly  23  provides the moving tool-delivering extension  25  with a reliable supporting force, so as to ensure a smooth and safe tool change. 
   Furthermore, the telescopic gas pipe set frees the tool-disengaging cylinder  28  from additional air pipe that may impede the tool delivery so as to optimize the tool-delivering mechanism of the present invention. 
   Although the particular embodiment of the invention has been described in detail for purposes of illustration, it will be understood by one of ordinary skill in the art that numerous variations will be possible to the disclosed embodiments without going outside the scope of the invention as disclosed in the claims.