Patent Publication Number: US-10766118-B2

Title: Edge processing device for molded powder compact and edge processing method for molded powder compact

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a National Stage of International Application No. PCT/JP2016/078559, filed Sep. 28, 2016, claiming priority based on Japanese Patent Application No. 2015-210262, filed Oct. 26, 2015. 
     TECHNICAL FIELD 
     The present invention relates to an edge processing device and an edge processing method, for chamfering and burring corner portions of a molded powder compact. 
     BACKGROUND ART 
     A product that is obtained by carrying out a predetermined treatment to a molded powder compact manufactured by compressing magnetic powder is commonly known. Examples of such a product include magnetic cores (metal powder cores and ferrite cores) included in coiled components such as inductors, transformers, and chokes. Such magnetic cores are produced in such a manner that a molded powder compact is manufactured by compressing ferrite or metal magnetic powder, and then the molded powder compact is annealed and sintered by carrying out a heat treatment. 
     Further, a drum-shaped molded powder compact in which a shaft is provided between a pair of flanges is known as molded powder compact. A drum-type magnetic core (drum core) obtained by heat treating the drum-shaped molded powder compact, along with a coil wound around the shaft, constitutes a coiled component described above. Such a molded powder compact is manufactured by carrying out machine processing to cut a molded powder compact having a simple shape such as a circular cylinder or a rectangular solid (cf. Patent Document 1). In recent years, however, various attempts have been made in order to reduce processing by near-net-shape forming. 
       FIG. 9  shows a cross-section of a mold that is used for near-net-shape forming of a molded powder compact. With this, a molded powder compact  1  having a shaft  13  between a pair of flanges  11 ,  12  as shown in  FIG. 1  is provided. The mold includes a pair of punches  91  that face each other in a pressure direction (an up-down direction in  FIG. 9 ), and tubular dies  92  that are disposed on both side of the punches. Each of the punches  91  is provided with a flange forming portion  93  and a shaft forming portion  94 . Tip end portions  94   a  of the shaft forming portion  94  are formed flat so as to ensure their thickness. This also applies to tip end portions of the flange forming portion  93 . This is because there is a concern, for example, for damages due to poor strength when the tip end portions are pointed. 
     However, when the molded powder compact  1  is manufactured using the mold described above, corner portions  13 A- 13 D of the shaft  13  have an angular shape as shown in  FIG. 1 , and therefore it is necessary to carry out chamfering in order not to damage a coil when winding. Further, even if chamfering is not necessary, there is a case in which it is necessary to remove burrs occurring at the corner portions  13 A- 13 D. In particular, magnetic powder made from a soft and highly malleable metal such as pure iron and magnetic powder with fine grain diameter easily get into gaps between the punches and the dies to produce burrs. In view of the above circumstances, it is necessary to carry out treatments, such as chamfering and burring (hereinafter referred to as edge processing), to corner portions of a molded powder compact. 
     PRIOR ART DOCUMENTS 
     Patent Documents 
     Patent Document 1: JP-A-H06-260357 
     Patent Document 2: JP-A-2007-90482 
     Patent Document 3: JP-A-2005-212026 
     Patent Document 4: JP-A-2010-214554 
     Patent Document 5: JP-A-2006-247768 
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
     Patent Document 1 describes a technique for cutting a square-shaped winding core portion into a circular shape by rotating a chip core between a pair of grindstones. As described above, this is a technique relating to cutting work for forming the winding core portion into a circular shape, and does not relate to edge processing to corner portions of a molded powder compact. 
     Patent Documents 2-4 describe a technique for burring using a tool such as a roller and a rotating brush. However, as the molded powder compact is generally lightweight, and easily pushed out to a downstream side due to a contact with a rotating tool, there is a case in which edge processing may not be carried out appropriately without appropriate contact time being provided. Nevertheless, if the molded powder compact is held too tightly in order to prevent undesirably being pushed out, the molded powder compact may involve cracking. 
     Patent Document 5 describes a technique for processing end surfaces of a glass substrate using a plurality of grindstones disposed on both sides of a conveying belt in the width direction. However, this technique neither relate to edge processing to corner portions of a molded powder compact, nor suggest solution for the above stated problem. 
     The present invention is made in view of the above circumstances, and an object of the present invention is to provide a device and a method for carrying out edge processing to corner portions of a molded powder compact. 
     Means for Solving the Problems 
     The present invention provides an edge processing device for a molded powder compact, the device comprising conveying means that convey a molded powder compact along a predetermined conveying path, a first rotating tool disposed on one side in an intersecting direction intersecting with a conveying direction, and a second rotating tool disposed on the other side in the intersecting direction, and rotating in a direction identical to a direction the first rotating tool rotates, wherein the first rotating tool is configured so as to be able to be brought into contact from an upstream side with a first corner portion between one side surface of a processing target portion of the molded powder compact and a rear surface of the processing target portion, the second rotating tool is configured so as to be able to be brought into contact from a downstream side with a second corner portion between the other side surface of the processing target portion and a front surface of the processing target portion, and the second rotating tool faces the first rotating tool with the conveying path therebetween, and is positionally displaced to the downstream side with respect to the first rotating tool. 
     According to this device, when the first rotating tool processes the first corner portion, the second rotating tool also processes the second corner portion, and therefore a force by which the first rotating tool pushes the molded powder compact out toward the downstream side and a force by which the second rotating tool pushes the molded powder compact out toward the upstream side act at the same time. In addition, the first corner portion and the second corner portion are disposed substantially diagonally regarding the processing target portion, these forces act in a balanced manner. Therefore, the molded powder compact may not be pushed undesirably toward the downstream side due to the first rotating tool being in contact, and contact time in which the first rotating tool is in contact with the corner portion may be ensured. As a result, it is possible to appropriately carry out edge processing to the corner portion of the molded powder compact. 
     On the other hand, in a configuration in which the second rotating tool is positionally displaced to the upstream side with respect to the first rotating tool, or in which the second rotating tool is not positionally displaced with respect to first rotating tool to the downstream side or to the upstream side, it is difficult to cause the first corner portion and the second corner portion to exert the push-put force and the push-back force at the same time. In this case, when the first rotating tool processes the first corner portion, the molded powder compact can be easily pushed toward the downstream side due to contact with the first rotating tool, and if this reduces the contact time in which the first rotating tool is in contact with the first corner portion, edge processing to the first corner portion may not be appropriately carried out. 
     In the edge processing device, it is preferable to further comprise a third rotating tool disposed on the other side in the intersecting direction, and rotating in a direction opposite from the direction the first rotating tool rotates, and a fourth rotating tool disposed on the one side in the intersecting direction, and rotating in a direction identical to the direction the third rotating tool rotates, wherein the third rotating tool is configured so as to be able to be brought into contact from the upstream side with a third corner portion between the other side surface of the processing target portion and the rear surface of the processing target portion, the fourth rotating tool is configured so as to be able to be brought into contact from the downstream side with a fourth corner portion between the one side surface of the processing target portion and the front surface of the processing target portion, and the fourth rotating tool faces the third rotating tool with the conveying path therebetween, and is positionally displaced to the downstream side with respect to the third rotating tool. 
     In this case, when the third rotating tool processes the third corner portion, the fourth rotating tool also processes the fourth corner portion, and therefore a force by which the third rotating tool pushes the molded powder compact out toward the downstream side and a force by which the fourth rotating tool pushes the molded powder compact out toward the upstream side act at the same time. In addition, the third corner portion and the fourth corner portion are disposed substantially diagonally regarding the processing target portion, these forces act in a balanced manner. Thus, in the same manner as described above, contact time in which the third rotating tool is in contact with the corner portion of the molded powder compact may be ensured, and it is possible to appropriately carry out edge processing to the four corner portions. 
     For each of the first and the second rotating tool, a rotating brush may be used that rotates about a rotating shaft extending along a direction intersecting with both of the conveying direction and the intersecting direction. Similarly, for each of the third and the fourth rotating tool, a rotating brush may be used that rotates about a rotating shaft extending along a direction intersecting with both of the conveying direction and the intersecting direction. 
     In the edge processing device, it is preferable that each of the first and the second rotating tool is configured to be displaceable in a direction intersecting with both of the conveying direction and the intersecting direction. With this, the rotating tool may reach ends of the processing target portion to provide superior finishing. From the same reason, it is preferable that the third and the fourth rotating tools are configured displaceably in the direction intersecting both with the conveying direction and the intersecting direction. 
     In the edge processing device, it is preferable that the conveying means is provided with a restricting surface that faces, from the upstream side, a portion of the molded powder compact excluding the processing target portion. With this, along with improved effect by the positional relation among the rotating tools described above, edge processing can be appropriately carried out to the corner portions of the molded powder compact. 
     In the edge processing device, it is preferable that above the conveying means, a guiding surface for guiding a top surface of the molded powder compact is provided. With this, it is possible to prevent the molded powder compact from being lifted while being conveyed, and along with improved effect by the positional relation among the rotating tools described above, edge processing can be appropriately carried out to the corner portions of the molded powder compact. 
     In the edge processing device, it is preferable that a restricting surface is provided, the restricting surface facing, from the intersecting direction, a portion of the molded powder compact excluding the processing target portion. With this, along with improved effect by the positional relation among the rotating tools described above, edge processing can be appropriately carried out to the corner portions of the molded powder compact. 
     The present invention provides an edge processing method for a molded powder compact, the method comprising a conveying step for conveying a molded powder compact along a predetermined conveying path, a first processing step for processing a first corner portion by bringing a first rotating tool into contact from an upstream side with the first corner portion between one side surface of a processing target portion of the molded powder compact and a rear surface of the processing target portion, and a second processing step for processing a second corner portion by bringing a second rotating tool into contact from a downstream side with the second corner portion between the other side surface of the processing target portion and a front surface of the processing target portion, wherein the second rotating tool is positionally displaced to the downstream side with respect to the first rotating tool, and the second corner portion is processed by the second rotating tool when the first corner portion is processed by the first rotating tool. 
     According to this method, when the first corner portion is processed by the first rotating tool, the second corner portion is also processed by the second rotating tool, and therefore a force by which the first rotating tool pushes the molded powder compact out toward the downstream side and a force by which the second rotating tool pushes the molded powder compact out toward the upstream side act at the same time. In addition, the first corner portion and the second corner portion are disposed substantially diagonally regarding the processing target portion, these forces act in a balanced manner. Therefore, the molded powder compact may not be pushed undesirably toward the downstream side due to the first rotating tool being in contact, and contact time in which the first rotating tool is in contact with the corner portion may be ensured. As a result, it is possible to appropriately carry out edge processing to the corner portion of the molded powder compact. 
     In the edge processing method, it is preferable to further comprise a third processing step for processing a third corner portion by bringing a third rotating tool into contact from the upstream side with the third corner portion between the other side surface of the processing target portion and the rear surface of the processing target portion, and a fourth processing step for processing a fourth corner portion by bringing a fourth rotating tool into contact from the downstream side with the fourth corner portion between the one side surface of the processing target portion and the front surface of the processing target portion, wherein the fourth rotating tool is positionally displaced to the downstream side with respect to the third rotating tool, and the fourth corner portion is processed by the fourth rotating tool when the third corner portion is processed by the third rotating tool. 
     In this case, when the third corner portion is processed by the third rotating tool, the fourth corner portion is also processed by the fourth rotating tool, and therefore a force by which the third rotating tool pushes the molded powder compact out toward the downstream side and a force by which the fourth rotating tool pushes the molded powder compact out toward the upstream side act at the same time. In addition, the third corner portion and the fourth corner portion are disposed substantially diagonally regarding the processing target portion, these forces act in a balanced manner. Thus, in the same manner as described above, contact time in which the third rotating tool is in contact with the corner portion of the molded powder compact may be ensured, and it is possible to appropriately carry out edge processing to the four corner portions. 
     In the edge processing method, it is preferable to process the first and the second corner portion while the first and the second rotating tool are displaced in an extending direction of the processing target portion. With this, the rotating tool may reach ends of the processing target portion to provide superior finishing. From the same reason, it is preferable to process the third and the fourth corner portion while the third and the fourth rotating tool are displaced in an extending direction of the processing target portion. 
     In the edge processing method, it is preferable to restrict movement of the molded powder compact to the upstream side when being conveyed, by bringing a restricting surface into contact from the upstream side with a portion of the molded powder compact excluding the processing target portion. With this, along with improved effect by the positional relation among the rotating tools described above, edge processing can be appropriately carried out to the corner portions of the molded powder compact. 
     In the edge processing method, it is preferable to restrict movement in an intersecting direction or rotation of the molded powder compact when being conveyed, by bringing a restricting surface into contact from the intersecting direction with a portion of the molded powder compact excluding the processing target portion, the intersecting direction intersecting with a conveying direction. With this, along with improved effect by the positional relation among the rotating tools described above, edge processing can be appropriately carried out to the corner portions of the molded powder compact. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows one example of a molded powder compact in (a) a perspective view and (b) a cross-sectional view. 
         FIG. 2  is a front view schematically illustrating one example of an edge processing device. 
         FIG. 3  is a plan view illustrating conveying means and a rotating tool. 
         FIG. 4  is a sectional view taken along an arrow X-X in  FIG. 3 . 
         FIG. 5  is a sectional view taken along an arrow Y-Y in  FIG. 3 . 
         FIG. 6  is a perspective view illustrating another example of the molded powder compact. 
         FIG. 7  shows one example of a molded powder compact in (a) a perspective view and (b) a cross-sectional view. 
         FIG. 8  is a perspective view illustrating another example of the molded powder compact. 
         FIG. 9  is a sectional view illustrating one example of a mold for molding the molded powder compact. 
     
    
    
     MODE FOR CARRYING OUT THE INVENTION 
     An embodiment of the present invention will be explained with reference to the drawings. 
     A molded powder compact  1  illustrated in  FIG. 1  is in a drum shape in which a shaft  13  having a substantially square-shaped cross-section is provided between a pair of flanges  11 ,  12 . Providing heat treatment to this produces a drum-type magnetic core having the shaft  13  as a winding portion. However, if a magnetic core is manufactured in this state, a coil may be damaged at corner portions of the shaft  13  when winding. In this embodiment, therefore, chamfering as edge processing is carried out to the corner portions of the shaft  13  taking the shaft  13  of the molded powder compact  1  as a processing target portion. Specifically, using an edge processing device illustrated in  FIGS. 2-5 , each of angular corner portions  13 A- 13 D are cut into curved corner portions  13 A- 13 D as illustrated in  FIG. 7 . 
     The edge processing device includes: a conveying belt  2  that conveys the molded powder compact  1  along a predetermined conveying path (one example of conveying means); a rotating brush  31  as a first rotating tool disposed on one side in an intersecting direction intersecting with a conveying direction CD (a downward side in  FIG. 3 , in this embodiment); and a rotating brush  32  as a second rotating tool disposed on the other side in the intersecting direction (an upward side in  FIG. 3 , in this embodiment). In this embodiment, the edge processing device further includes a rotating brush  33  as a third rotating tool disposed on the other side in the intersecting direction, and a rotating brush  34  as a fourth rotating tool disposed on the one side in the intersecting direction. While shown only partially in  FIG. 3 , bristles  39  of the rotating brushes are provided along an entire circumference. 
     The conveying belt  2  is configured by an endless toothed belt combined with a pair of pulleys  21 , and driven at a predetermined speed by an unillustrated driving device coupled to the pulleys  21 . The molded powder compact  1  placed on the conveying belt  2  is conveyed along the predetermined conveying path, and then carried toward the conveying direction CD. In the following, a rearward side of the conveying direction CD (a right side in  FIG. 3 ) is often referred to an upstream side, and a forward side of the conveying direction CD (a left side in  FIG. 3 ) is often referred to a downstream side. In this embodiment, the intersecting direction intersecting with the conveying direction CD corresponds to an across-the-width direction of the conveying belt  2  (the up-down direction in  FIG. 3 ). 
     As illustrated in  FIG. 2 , there is, on the upstream side of the conveying belt  2 , a supply device  41  for supplying the molded powder compact  1  to the conveying belt  2 . On the downstream side of the conveying belt  2 , there is a collection case  61  for collecting the molded powder compact  1  after processing. Under the conveying belt  2 , there is a container  62  for receiving processing scraps occurred in the edge processing. Above the conveying belt  2 , as illustrated in  FIGS. 4 and 5 , there is a guiding surface  46  for guiding over a top surface of the molded powder compact  1 . The guiding surface  46  extends along the conveying direction CD, and configured by a bottom surface of a top panel  45  disposed above the conveying belt  2 . 
     The supply device  41  includes a sensor  42  that senses molded powder compacts  1  sequentially or non-sequentially carried from an oscillating feeder  63 , a rotating table  43  that separates the molded powder compacts  1  carried from the oscillating feeder  63  on an individual basis, and an arm  44  that picks the molded powder compacts  1  on the rotating table  43  and places the molded powder compacts  1  on the conveying belt  2 . The molded powder compacts  1  are aligned to take the same posture before being placed on the rotating table  43 , and the molded powder compacts  1  are placed on the conveying belt  2  in a certain posture illustrated in  FIGS. 3-5 . The conveying belt  2  conveys the molded powder compacts  1  in a state in which shafts  13  are upright. 
     As illustrated in  FIGS. 4 and 5 , the guiding surface  46  faces top surfaces of the molded powder compacts  1 , and prevents the molded powder compact  1  from being lifted while being conveyed. The guiding surface  46  is disposed at height at which it is slightly in contact with the top surfaces of the molded powder compact  1 , or at height at which it is positioned with a fine gap from the top surfaces of the molded powder compact  1 . According to such a configuration, as the molded powder compact  1  may not be tightly held from top and bottom, there is only a small possibility that cracking occurs in the molded powder compact  1  (especially, in the flanges  11 ,  12 ). On the other hand, the molded powder compact  1  in contact with the rotating brushes can be easily pushed out toward the conveying direction CD, and therefore a configuration described below is useful. 
     A plan view in  FIG. 3  shows the conveying belt  2  and the rotating brushes  31 - 34  that can be used by this device. The rotating brushes  31 - 34  rotate respectively about rotating shafts  31   a - 34   a , and driven by a motor  35  as a driving device (cf.  FIG. 2 ). The rotating shafts  31   a - 34   a  are directed in an up-down direction that intersects with both of the conveying direction CD and the intersecting direction, and extend along an extending direction of the shaft  13  as the processing target portion. The rotating brush  32  rotates in a direction LD which is the same direction as the rotating brush  31  rotates. The rotating direction LD is a counterclockwise direction in  FIG. 3 . Further, the rotating brush  33  rotates in a rotating direction RD which is an opposite direction from the direction the rotating brush  31  rotates. The rotating direction RD is a clockwise direction in  FIG. 3 . The rotating brush  34  rotates in the direction RD which is the same direction as the rotating brush  33  rotates. 
     The rotating brushes  31 - 34  are disposed between the conveying belt  2  and the top panel  45  in the up-down direction, and their circumferential portions extend above the conveying belt  2 . As in  FIG. 3 , the rotating brush  31  and the rotating brush  32  face each other with the conveying belt  2  therebetween, and an interval between their circumferential portions is set to be smaller than a width W of the shaft  13 . As a result, the rotating brushes  31 ,  32  are brought into contact horizontally with the shaft  13  of the molded powder compact  1  that passes between the rotating brushes  31 ,  32 . The rotating brushes  33 ,  34  are configured in the same manner. 
     The rotating brush  31  is configured to able to be brought into contact, from the upstream side, with the corner portion  13 A (corresponds to a first corner portion) between one side surface of the shaft  13  as the processing target portion (a lower side in  FIG. 3 ) and a rear surface of the shaft  13 . The bristles  39  of the rotating brush  31  extend above the conveying belt  2  from one side of the intersecting direction, and grind the corner portion  13 A while moving to the downstream side. Further, the rotating brush  32  is configured to able to be brought into contact, from the downstream side, with the corner portion  13 B (corresponds to a second corner portion) between the other side surface of the shaft  13  (an upper side in  FIG. 3 ) and a front surface of the shaft  13 . The bristles  39  of the rotating brush  32  extend above the conveying belt  2  from the other side of the intersecting direction, and grind the corner portion  13 B while moving to the upstream side. 
     With this device, the rotating brush  32  faces the rotating brush  31  with the conveying path (that is, the conveying belt  2 ) therebetween, and is positionally displaced to the downstream side with respect to the rotating brush  31 , so that while the rotating brush  31  processes (chamfer in this embodiment) the corner portion  13 A, the rotating brush  32  processes (chamfer in this embodiment) the corner portion  13 B. A positional displacement amount D 1  is a distance between the rotating shafts  31   a ,  32   a  in the conveying direction CD, and set to be an amount allowing time duration for processing the corner portion  13 A and the corner portion  13 B at the same time. Further, as the rotating brushes  31 ,  32  face each other, the positional displacement amount D 1  is set to be an amount that does not exceed a diameter of the rotating brushes  31 ,  32 . 
     The positional displacement amount D 1  is not particularly limited as long as the above described effects are exerted, and is set, for example, to be 10% to 300% of a length L of the shaft  13 , and, more narrowly, 50% to 200% of the length L. The length L is measured as a distance between the corner portion  13 A and the corner portion  13 B in the conveying direction CD. In one specific example, it is possible to chamfer a molded powder compact having 4 mm of the length L and a different molded powder compact having 3 mm of the length L in an appropriate manner, using a device in which the positional displacement amount D 1  (and a positional displacement amount D 2  described later) is set to 3 mm. 
     Therefore, an edge processing method using this device includes: a conveying step for conveying the molded powder compact  1  along the predetermined conveying path; a first processing step for processing the corner portion  13 A by bringing the rotating brush  31  into contact with the corner portion  13 A from the upstream side; and a second processing step for processing the corner portion  13 B by bringing the rotating brush  32  into contact with the corner portion  13 B from the downstream side. Further, the rotating brush  32  is positionally displaced to the downstream side with respect to the rotating brush  31 , and the corner portion  13 B is processed by the rotating brush  32  when the corner portion  13 A is processed by the rotating brush  31 . 
     By the rotating brushes  31 ,  32  disposed in this manner processing the corner portions  13 A,  13 B, when the corner portion  13 A and the corner portion  13 B are processed, a force with which the rotating brush  31  pushes the molded powder compact  1  to the downstream side is exerted at the same time as a force with which the rotating brush  32  pushes the molded powder compact  1  to the upstream side. Furthermore, as the corner portion  13 A and the corner portion  13 B are positioned substantially diagonally in a cross-section of the shaft  13  as the processing target portion, these forces act in a balanced manner. Therefore, the molded powder compact  1  may not be pushed undesirably toward the downstream side due to the rotating brush  31  being in contact, and contact time in which the rotating brush  31  is in contact with the corner portion  13 A may be ensured. Moreover, it is possible to prevent contact with the rotating brush  32  from pushing the molded powder compact  1  back to the upstream side. 
     The rotating brush  33  is configured so as to be able to be brought into contact, from the upstream side, with the corner portion  13 C (corresponds to a third corner portion) between the other side surface of the shaft  13  as the processing target portion and the rear surface of the shaft  13 . Similarly to the rotating brush  31  described above, the rotating brush  33  grinds the corner portion  13 C in the process of moving to the downstream side above the conveying belt  2 . Further, the rotating brush  34  is configured so as to be able to be brought into contact, from the downstream side, with the corner portion  13 D (corresponds to a fourth corner portion) between the one side surface of the shaft  13  and the front surface of the shaft  13 . Similarly to the rotating brush  32  described above, the rotating brush  34  grinds the corner portion  13 D in the process of moving to the upstream side above the conveying belt  2 . 
     The rotating brush  34  faces the rotating brush  33  with the conveying path (that is, the conveying belt  2 ) therebetween, and is positionally displaced to the downstream side with respect to the rotating brush  33 , so that while the rotating brush  33  processes (chamfer in this embodiment) the corner portion  13 C, the rotating brush  34  processes (chamfer in this embodiment) the corner portion  13 D. A positional displacement amount D 2  is a distance between the rotating shafts  33   a ,  34   a  in the conveying direction CD, and set to be an amount allowing time duration for processing the corner portion  13 C and the corner portion  13 D at the same time. The positional displacement amount D 2  can be as large as the positional displacement amount D 1 . 
     Therefore, the edge processing method using this device includes, after the first and the second processing step described above: a third processing step for processing the corner portion  13 C by bringing the rotating brush  33  into contact with the corner portion  13 C from the upstream side; and a fourth processing step for processing the corner portion  13 D by bringing the rotating brush  34  into contact with the corner portion  13 D from the downstream side. Further, the rotating brush  34  is positionally displaced to the downstream side with respect to the rotating brush  33 , and the corner portion  13 D is processed by the rotating brush  34  when the corner portion  13 C is processed by the rotating brush  33 . 
     By the rotating brushes  33 ,  34  disposed in this manner processing the corner portions  13 C,  13 D, a force with which the rotating brush  33  pushes the molded powder compact  1  to the downstream side is exerted at the same time as a force with which the rotating brush  34  pushes the molded powder compact  1  to the upstream side. Furthermore, as the corner portion  13 C and the corner portion  13 D are positioned substantially diagonally in a cross-section of the shaft  13  as the processing target portion, these forces act in a balanced manner. Therefore, the molded powder compact  1  may not be pushed undesirably toward the downstream side due to the rotating brush  33  being in contact, and contact time in which the rotating brush  33  is in contact with the corner portion  13 C may be ensured. Moreover, it is possible to prevent contact with the rotating brush  34  from pushing the molded powder compact  1  back to the upstream side. 
     As described above, according to this embodiment, it is possible to carry out chamfering as the edge processing appropriately to the corner portions  13 A- 13 D of the shaft  13  of the molded powder compact  1 . With the molded powder compact  1  after the processing, as shown in an enlarged view on a left side of  FIG. 3  as well as in  FIG. 7 , the corner portions  13 A- 13 D of the shaft  13  are in a rounded shape. Therefore, with a magnetic core obtained by carrying out heat treatment to the molded powder compact  1 , a coil may not be damaged while winding. 
     The rotating brushes  31 - 34  in this embodiment are configured such that the bristles  39  extend radially from a disc-shaped base portion  38  as shown in  FIG. 3 , and the bristles  39  are curved so as to project in the rotating direction (the rotating direction LD or the rotating direction RD). Therefore, the brushes may easily move in the rotating direction in a state in which the brushes are in contact with the corner portions of the shaft  13 , and thus it is advantageous to carry out edge processing. The bristles  39  are made of a resin containing abrasive grains such as alumina, and have a superior abrasive capability to the molded powder compact  1 , yet a concern for over-grinding of the corner portions is smaller as compared to metallic brushes. As examples of such rotating brushes, Radial bristle Marguerite disks available from Sumitomo 3M Ltd may be used. Examples of the rotating tool to be used are not limited to this, and may include a rolling brush having bristles made of nylon  6  or nylon containing abrasive grains, and a cotton yarn buffing wheel. 
     A thickness of the rotating brushes  31 - 34  (a thickness of the bristles  39 ) is preferably smaller than a height H of the shaft  13  (cf.  FIG. 4 ) so that the bristles  39  may easily enter between the pair of flanges  11 ,  12 . For example, the thickness of the rotating brushes is set to be smaller than the height H by about 0.5 mm to 1 mm. In this case, however, processing to ends of the shaft  13  may not be sufficient. Therefore, in this embodiment, the corner portions  13 A,  13 B are processed while the rotating brushes  31 ,  32  are displaced in the up-down direction, which is the extending direction of the shaft  13 . This also applies to the rotating brushes  33 ,  34 . 
     As illustrated in  FIG. 2 , this edge processing device is mounted on a working table  50 , and the conveying belt  2 , the top panel  45 , and an upper base member  56  are fixed to the working table  50  via supporting members  51 ,  52 . The top panel  45  is connected to the supporting member  52 , on the upstream side and the downstream side in the conveying direction, via a supporting member  64 , a connecting portion  65 , and the upper base member  56 . The top panel  45  is mounted so as to be able to move up and down with respect to the upper base member  56 . Further, in the illustrated example, in order to easily make the height of the top panel  45  equal on the upstream side and the downstream side in the conveying direction, a pulley  67  provided at an upper end of the connecting portion  65  on the upstream side and a pulley  67  provided at an upper end of the connecting portion  65  on the downstream side are connected with a belt  59 , a rotating operation of a positioning handle attached to the pulley  67  on the upstream side is transmitted to the pulley  67  on the downstream side to synchronize up and down movement of the top panel  45  on the upstream side and on the downstream side. Each of the rotating brushes  31 - 34  is connected to the motor  35  via a reducer  80 . Each of the rotating brushes  31 - 34  is supported by a supporting member  53  via a fixing member  58  that securely hold the reducer  80 , a positioning stage  68 , and a connecting member  57 . The supporting member  53  is combined with the upper base member  56  connected to the supporting member  52  so as to be able to displace in the up-down direction relative to the upper base member  56 . Between the upper base member  56  and the supporting member  53 , there is a cam  54  connected to an unillustrated driving device, and in conjunction with rotation of the cam  54 , the supporting member  53  moves up and down following an unillustrated guiding pin provided for the upper base member  56 . Along with this, the rotating brushes  31 - 34  also move up and down. Further, it is possible to adjust and determine initial positions of the rotating brushes  31 - 34  by the positioning stage  68 . 
     As described above, the rotating brushes  31 ,  32  are configured displaceably within a range defined by the cam  54 , in the up-down direction which is the direction intersecting both with the conveying direction CD and the intersecting direction. With this, edge processing may be carried out to ends of the shaft  13  as the processing target portion to provide superior finishing. Further, the rotating brushes  33 ,  34  are also configured displaceably in the up-down direction. A displacement amount of the rotating brushes  31 - 34  in the up-down direction (a margin of up-down movement of the supporting member  53 ) may be adjusted by changing a shape of the cam  54 . 
     In this embodiment, the rotating brushes  31 - 34  have, but not limited to, the same rotation speed. For example, if a force by which the rotating brushes  31 ,  33  push the molded powder compact  1  out toward the downstream side is large, and the molded powder compact  1  can slip on the conveying belt  2 , such a situation can be resolved by relatively increasing the rotation speed of the rotating brushes  32 ,  34  facing the rotating brushes  31 ,  33 . Alternatively, due to a different reason, the rotation speed of the rotating brushes  31 ,  33  may be relatively increased. 
     As illustrated in  FIGS. 3 and 4 , the conveying belt  2  is provided with a plurality of depressed portions  22  intermittently along the conveying direction CD, and each of the depressed portions  22  includes the molded powder compact  1 . A wall surface of the depressed portions  22  on the upstream side is provided as a restricting surface  23  that faces, from the upstream side, a flange  12  corresponding to a part that is not a processing target portion (the shaft  13 ) of the molded powder compact  1 . In this embodiment, movement of the molded powder compact  1  to the upstream side is restricted while being conveyed, by bringing the restricting surface  23  into contact with the flange  12  of the molded powder compact  1 . With this, along with improved effect by the positional relation among the rotating brushes described above, edge processing can be appropriately carried out to the corner portions of the shaft  13  of the molded powder compact  1 . Further, by bringing the restricting surface  23  into contact not with the shaft  13  but with the flange  12 , it is also possible not to prevent the rotating brushes from being brought into contact with to the shaft  13 . 
     In order to ensure workability when the molded powder compact  1  is placed on the conveying belt  2 , the depressed portions  22  are formed to be longer than the flange  12  in the conveying direction CD. For example, when a length of the flange  12  is 10 mm, a length of the depressed portions  22  may be set to be 14 mm. As described above, even in the configuration in which the molded powder compact  1  is placed within the depressed portions  22  is employed, a play is provided in the conveying direction CD between the wall surface of the depressed portions  22  and the molded powder compact  1 . Therefore, it is useful to employ the above configuration that prevents the molded powder compact  1  from being undesirably pushed out toward the downstream side. 
     Preferably, a depth of the depressed portions  22  is set to be equal to or smaller than a thickness of the flange  12 . For example, when the thickness of the flange  12  is 1 mm, the depth of the depressed portions  22  may be set to 0.6 mm. With this, as a top surface  12   a  of the flange  12  is positioned at the same height as or higher than a surface of the conveying belt  2 , the rotating brush may not be prevented from being brought into contact with a lower portion of the shaft  13 . 
     As illustrated in  FIG. 5 , restricting surfaces  24  that face the flange  12  corresponding to a part that is not a processing target portion of the molded powder compact  1  are provided on the both side of the across-the-width direction of the conveying belt  2  corresponding to the intersecting direction (right-left direction in  FIG. 5 ). The restricting surfaces  24  are provided by side surfaces of guiding members  25  disposed adjacent to the conveying belt  2 . In this embodiment, movement in the intersecting direction and rotation of the molded powder compact  1  are restricted while being conveyed, by restricting surfaces  47  that will be later described. However, the restricting surfaces  24  may be used in place of or in addition to this configuration. Preferably, upper ends of the restricting surfaces  24  are positioned at the same height as or lower than the top surface  12   a  of the flange  12 , and with this, the rotating brush may not be prevented from being brought into contact with the lower portion of the shaft  13 . 
     Above the conveying belt  2 , there are provided the restricting surfaces  47  that face, from the intersecting direction, a flange  11  corresponding to a part that is not a processing target portion of the molded powder compact  1 . The restricting surfaces  47  are provided by side surfaces of guiding members  48  disposed adjacent to the top panel  45 . In this embodiment, movement in the intersecting direction or rotation of the molded powder compact  1  are restricted while being conveyed, by bringing the restricting surfaces  47  into contact with the flange  11  of the molded powder compact  1  from the intersecting direction. With this, along with improved effect by the positional relation among the rotating brushes described above, edge processing can be appropriately carried out to the corner portions of the shaft  13  of the molded powder compact  1 . Preferably, lower ends of the restricting surfaces  47  are positioned at the same height as or higher than a lower surface  11   a  of the flange  11 , and with this, the rotating brush may not be prevented from being brought into contact with an upper portion of the shaft  13 . 
     In this embodiment, the example in which chamfering is carried out to the corner portions of the shaft  13  of the molded powder compact  1 . However, burring as edge processing may be carried out in place of chamfering. Alternatively, it is possible to carry out chamfering and burring at the same time. 
     A molded powder compact as a target of edge processing may not be limited to the shape as shown in  FIG. 1 , and may take a different shape. For example, in a molded powder compact  7  illustrated in  FIG. 6 , a plate-like shaft  73  provided between a pair of flanges  71 ,  72  are taken as a processing target portion, and edge processing is carried out to corner portions of the shaft  73 . The flanges may include cutout. It should be noted that a molded powder compact to which edge processing is carried out is not limited to the shape in which flanges are provided on both side of a shaft, and may have a shape in which a flange only on one side of a shaft. 
     The present invention is not limited to the embodiment mentioned above, but can be improved and modified variously within the scope of the present invention. Therefore, for example, in a case in which a burr occurs only at a specific corner portion such as the first corner portion, it is possible to employ a configuration in which the third and the fourth rotating tools are not provided. 
     In the embodiment described above, the example in which the molded powder compact is conveyed while the shaft is upright is described. However, a molded powder compact may be conveyed while the shaft is laid down. Further, in the embodiment described above, the example in which the shaft of the molded powder compact is a processing target portion is described. However, apart other than the shaft may be taken as a processing target portion, or it is possible to process a molded powder compact without a shaft. 
     In the embodiment described above, the example is shown in which the intersecting direction that intersects with the conveying direction is, but not limited to, horizontal. For example, as shown in  FIG. 8 , in a configuration in which the extending direction of a processing target portion is directed horizontally as in a case in which a flat-plated molded powder compact  8  is conveyed in the conveying direction CD, and edge processing (e.g., burring) is carry out to corner portions  8 A- 8 D taking the molded powder compact  8  as a whole as a processing target portion, it is useful to employ a configuration in which the intersecting direction that intersects with the conveying direction may be directed vertically, and rotating brushes having a rotating shaft in a horizontal direction may be provided above and under the conveying path. 
     The configuration of the conveying belt may not be limited to the above embodiments. Further, in the embodiment described above, the example in which the conveying belt is used as the conveying means is described. However, as long as a molded powder compact may be conveyed along a predetermined conveying path, the conveying means may not be particularly limited, and a conveying chain or a different mechanism may be employed. 
     DESCRIPTION OF REFERENCE SIGNS 
     
         
           1  Molded powder compact 
           2  Conveying belt (one example of conveying means) 
           11  Flange 
           12  Flange 
           13  Shaft (one example of processing target portion) 
           13 A Corner portion (first corner portion) 
           13 B Corner portion (second corner portion) 
           13 C Corner portion (third corner portion) 
           13 D Corner portion (fourth corner portion) 
           22  Depressed portion 
           23  Restricting surface 
           31  Rotating brush (one example of first rotating tool) 
           32  Rotating brush (one example of second rotating tool) 
           33  Rotating brush (one example of third rotating tool) 
           34  Rotating brush (one example of fourth rotating tool) 
           41  Supply device 
           45  Top panel 
           46  Guiding surface