Patent Abstract:
A burring device is provided which can efficiently perform continuous burring. The burring device has a work holder which has a burring hole and which holds a work object, a pusher rod which rotatably supports the base end of a metal core which has a processing part on the tip end thereof, and a guide rod which is positioned to the front of the extended axis of the pusher rod and which has a guide surface on the tip end thereof which guides the tip end of the metal core towards the burring hole of the holder.

Full Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a burring device, and more particularly to a burring device suitable for processing of tubular walls. 
   2. Description of the Related Art 
   Examples of burring devices for tubular surfaces include those which push a metal core ball out through a lower hole formed in the tube, thereby deforming outward the circumferential edge of the lower hole (Refer to Japanese Patent Application Laid-open No. S59-33036 (FIG. 2 and FIG. 3) and Japanese Patent Application Laid-open No. H8-197151 (FIG. 3 and FIG. 7) for example). 
   Incidentally, with the burring devices of Japanese Patent Application Laid-open No. S59-33036 (FIG. 2 and FIG. 3) and Japanese Patent Application Laid-open No. H8-197151 (FIG. 3 and FIG. 7), the circumferential edge of the lower hole is deformed by the ball by being pushed out through the lower hole from inside the tube to perform the burring process, but when the next burring process is to be performed, the ball must be returned to the original position, and considerable effort is needed to perform a continuous burring operation. 
   SUMMARY OF THE INVENTION 
   With the foregoing in view, an object of the present invention is to provide a burring device which can efficiently and continuously perform a burring process. 
   In order to accomplish the aforementioned object, the burring device of a first embodiment comprises: a work holder has a burring hole and holds a work object; a pusher rod which rotatably supports a base end of a metal core which has a processing part on a tip end thereof; and a guide rod, which is positioned in front of the extended axis of the pusher rod, has a guide surface on the tip end thereof which guides the tip end of the metal core towards the burring hole of the holder; wherein a lower hole of the work object is aligned with the burring hole in the holder; the tip end of the guide rod is made to correspond to the lower hole of the work object; the pusher rod is moved forward; the metal core is made to contact a guide surface of the guide rod; and the pusher rod is moved forward; and thereby the tip end of the metal core is pressed into the lower hole of the work object and the circumferential edge of the lower hole is bent over. 
   Furthermore, the burring device of a second embodiment of the invention according to the first embodiment includes the guide surface of the guide rod formed into an arc. 
   Furthermore, the burring device of a third embodiment of the invention according to the first embodiment includes the processing part of the metal core formed with an arc cross section in the rotational direction, and the processing part is connected to the pusher rod via an arm. 
   Furthermore, the burring device of a fourth embodiment of the invention according to the third embodiment includes the processing part of the metal core having a spherical shape. 
   Furthermore, the burring device of a fifth embodiment of the invention according to the first embodiment includes a punch for the lower hole positioned to the outside of the extended axis of the burring hole of the work holder, and a lower hole die formed on the circumferential surface of the guide rod. 
   Furthermore, the burring device of a sixth embodiment the invention according to the first embodiment includes a coining punch hole formed concentrically with the burring hole of the work holder, positioned to the outside of the burring hole, and having a larger curvature radius than the curvature radius of the burring hole, and a coining punch positioned to the outside of the extended axis of the burring hole. 
   According to the first embodiment of the invention, a metal core is rotatably connected to the tip end of a pusher rod, so that after the burring process is complete and the pusher rod is pulled out of the work holder, the metal core will simultaneously be pulled out from the burr processing part, and therefore a series of burring processes can be continuously performed. 
   Furthermore, according to the invention of the aforementioned second embodiment, in addition to the above affect, the guide surface is formed in an arc, so the metal core will be smoothly guided, which can help to conserve the power of the actuator which moves the guide rod. 
   Furthermore, according to the invention of the aforementioned third embodiment, in addition to the above effect, the processing of the lower hole circumferential edge in the longitudinal direction of the tube can be smoothly performed and a product with good quality can be obtained. 
   Furthermore, according to the invention of the aforementioned fourth embodiment,  in addition to the above affect, a round protruding part can be obtained. 
   Furthermore, according to the invention of the aforementioned fifth embodiment,  in addition to the above affect, the burring process can be performed after a lower hole is made without moving the tube, so the operation of the burring process can be performed more efficiently. 
   Furthermore, according to the invention of the aforementioned sixth embodiment,  in addition to the above affect, the height and thickness of the tip end of the protruding part can be made consistent, and a better product with higher quality can be obtained. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view schematically showing the burring device of the present invention; 
       FIG. 2  is a cross-section view of the burring device of  FIG. 1  showing the condition where a lower hole is formed in the tube circumferential wall; 
       FIG. 3  is a cross-section view of the burring device of  FIG. 1  showing the condition prior to performing the burring process on the lower hole formed in the tube circumferential wall; 
       FIG. 4  is a cross-section view of the burring device of  FIG. 1  showing the condition during the burring process of the lower hole formed in the tube circumferential wall; 
       FIG. 5  is a cross-section view of the burring device of  FIG. 1  showing the condition when the burring process of the lower hole formed in the tube circumferential wall is complete; and 
       FIG. 6  is a perspective view showing various configurations of the metal core processing part of the burring device of the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The aforementioned burring device of the present invention will be described below in detail while referring to the drawings. 
   Note,  FIG. 1  is a perspective view schematically showing a tube circumferential wall burring device as the burring device of the present invention,  FIG. 2  is a schematic cross section view showing the condition where a lower hole is formed in the tube circumferential wall, and  FIG. 3  through  FIG. 5  are schematic cross section views showing the procedures of the burring process. 
   The burring device  1  shown in  FIG. 1  is comprised of a work holder  10 , a metal core pusher rod  20 , and a guide rod  30  on a base  2 , and is also equipped with a punching means  40 . 
   The work holder  10  is constructed of two separate holder parts  11 ,  12 . Furthermore, the mating surfaces of both of the holder parts  11 ,  12  have grooves  13   a ,  13   b  respectively, which extend in the horizontal direction to both ends and form a semicircular arc vertical cross section in the longitudinal direction, and small curvature radius grooves  14   a ,  14   b  and large curvature radius grooves  15   a ,  15   b  are formed to be connected together extending vertically up to the top surface forming a semicircular arc horizontal cross section at the middle region of the grooves  13   a ,  13   b . 
   Furthermore, the first holder part  11  is mounted to the base  2  and the second holder part  12  is connected to a piston rod  16   a  of a cylinder  16  which is mounted to the base  2 . Therefore, the second holder part  12  will be moved toward the first holder part  11 , and will be brought into contact with the holder  11 , by the cylinder  16 . 
   Therefore, when both holder parts  11 ,  12  are aligned together, tube insertion hole  13 , burring hole  14 , and coining punch hole  15  are formed between these holder parts  11 ,  12 . 
   Metal core pusher rod  20  is positioned on the extended axis of the aforementioned tube insertion hole  13 , and the base end is connected to the tip end of a piston rod  21   a  of a cylinder  21  which is mounted on the base  2 . Furthermore, the tip end of this metal core pusher rod  20  is equipped with a metal core  22 . This metal core  22  has a spherical part  22   a  as a processing part on the tip end, and a curved arm  22   b  protrudes from the back surface of this spherical part  22   a . Furthermore, the back end of the arm  22   b  is inserted into a slide region  23  formed at the tip end of the metal core pusher rod  20 , and is swingingly supported on the core shaft pusher rod  20  by a pin  24 . 
   The guide rod  30  is positioned on the extended axis of the aforementioned tube insertion hole  13 , and the base end is connected to a piston rod  31   a  of a cylinder  31  which is mounted to the base  2 . This guide rod  30  has a curved arc guide surface  32  formed on the back side facing upward. Furthermore, the center part of the top surface of this guide rod  30  is formed with a lower hole die part  33 . 
   Punching means  40  is equipped on tube  50  with a lower hole punch  41  for forming a lower hole  51  and a coining punch  42  which presses on the protruding part  52  which was formed by the burring process. 
   With the burring device  1  constructed in this manner, first the tube  50  which is the work object is held in the groove  13   a  of the first holder part  11 , and the second holder part  12  is brought into contact with the first holder part  11 , thereby retaining tube  50  in the tube insertion hole  13  which is formed. 
   Guide rod  30  is inserted from one end of the tube  50  in this condition, and the lower hole die part  33  of the guide rod  30  is positioned below the burring hole  14  of the holder  10 . Next, the lower hole punch  41  of the punching means  40  is lowered, and a lower hole  51  is formed in the tube  50  as showing in  FIG. 2 . 
   Next, the guide rod  30  is slightly retracted as showing in  FIG. 3 , and the guide surface  32  of this guide rod  30  is positioned beneath the lower hole  51  and the metal core pusher rod  20  is inserted into the tube  50  and the spherical part  22   a  of the metal core  22  is brought into contact with the guide surface  32  of the guide rod  30 . 
   Also, the metal core pusher rod  20  is further inserted. Therefore, the spherical part  22   a  of the metal core  22  is guided to the guide surface  32  of the guide rod  30  as shown in  FIG. 4 , is pushed into the lower hole  51  of the tube  50 , and the circumferential edge of the lower hole  51  is deformed outward. 
   Next, the metal core pusher rod  20  is further inserted. Then, the spherical part  22   a  of the metal core  22  deforms the circumferential edge of the lower hole  51  along the shape of the burring hole  14  of the holder  10  as shown in  FIG. 5 . In this case, the end surface of the protruding part  52  that is formed is made to have a consistent height and thickness by the coining punch  42 , thus completing the burring process. 
   Therefore, when the burring process is complete, the metal core pusher rod  20 , the guide rod  30  and the coining punch  42  are returned to their respective original conditions, and the holder part  12  of the holder  10  is separated from the holder part  11  and tube  50  is removed from the holder  10 . 
   An embodiment of the burring device of the present convention was described above, but the present invention is not restricted to the above-mentioned embodiments, and various alternates and changes are of course possible within the range of the technical concept of the invention shown in the patent claims. 
   For instance, in the aforementioned embodiment, a lower hole punch  41  was provided and lower hole  51  was formed in the tube  50  while being held in the work holder  10 , but the lower hole punch  41  is not necessary if the lower hole  51  is formed in a different location. 
   Furthermore, in the aforementioned embodiment, a coining punch  42  was provided, and thereby the height and thickness of the end of the extended part  52  of the tube  50  was made to be consistent, but this coining punch  42  is not absolutely necessary. 
   Furthermore, in the aforementioned embodiment, the guide surface  32  of the guide rod  30  was formed in an arc, but a simple sloped surface or a plurality of connected sloped surfaces are acceptable. Furthermore, in the aforementioned embodiment, the processing part  22   a  of the core shaft  22  had a spherical shape, but as shown in  FIG. 6 , a processing part with an elliptical shape (a), multi-surface shapes (b)–(e), or a combination of curved and flat surfaces (f) may be used.

Technology Classification (CPC): 1