Patent Publication Number: US-2023162912-A1

Title: Apparatus and method for manufacturing reactor

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from Japanese patent application No. 2021-189255, filed on Nov. 22, 2021, the disclosure of which is incorporated herein in its entirety by reference. 
     BACKGROUND 
     The present disclosure relates to an apparatus and a method for manufacturing a reactor. 
     Japanese Unexamined Patent Application Publication No. 2013-149841 discloses a method for manufacturing a reactor including a primary molding step and a secondary molding step. According to the technique described in Japanese Unexamined Patent Application Publication No. 2013-149841, a common mold can be used for both primary and secondary molding. 
     SUMMARY 
     In the secondary molding step, when a resin preferentially enters an outer peripheral side of the core, the core cannot be supported against a resin pressure, and therefore, there is a problem that a high stress is generated in the core, and thus the core is cracked. 
     The present disclosure has been made in order to solve such a problem, and an object of the present disclosure is to provide an apparatus and a method for manufacturing a reactor capable of preventing a core from being cracked due to a resin pressure during molding. 
     In an example aspect of the present disclosure, an apparatus for manufacturing a reactor provided with a core includes: a mold including a cavity for housing the core. 
     The mold includes a core support pin brought into contact with the core and configured to support the core against a resin pressure during molding, 
     resin flow paths during molding include an inner flow path passing through inside the core and an outer flow path passing through outside the core, and 
     the core support pin is disposed at a position where a width of the inner flow path is greater than a width of the outer flow path. 
     In another example aspect of the present disclosure, a method for manufacturing a reactor provided with a core includes: 
     molding a molded article by using a mold including a cavity for housing the core. 
     The mold includes a core support pin brought into contact with the core for supporting the core against a resin pressure during molding, 
     resin flow paths in the molding of the molded article include an inner flow path passing through inside the core and an outer flow path passing through outside the core, and 
     the core support pin is disposed at a position where a width of the inner flow path is greater than a width of the outer flow path. 
     According to the present disclosure, it is possible to provide an apparatus and a method for manufacturing a reactor capable of preventing a core from being cracked due to a resin pressure during molding. 
     The above and other objects, features and advantages of the present disclosure will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not to be considered as limiting the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a schematic top view showing an overview of a mold according to related art; 
         FIG.  2    is a schematic top view showing a configuration of a core; 
         FIG.  3    shows a dimensional relationship between an inner flow path and an outer flow path of the mold according to the related art; 
         FIG.  4    shows three modes of cracks of the core in the manufacturing apparatus according to the related art; 
         FIG.  5    is a schematic top view showing a mold of a manufacturing apparatus according to a first embodiment; 
         FIG.  6    shows a dimensional relationship between an inner flow path and an outer flow path of the mold according to the first embodiment; 
         FIG.  7    shows a preferable dimensional relationship between flow paths of the mold according to the first embodiment; 
         FIG.  8    shows a preferable dimensional relationship between flow paths of the mold according to the first embodiment; and 
         FIG.  9    shows a preferable dimensional relationship between flow paths of the mold according to the first embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     (Study Leading to Embodiment) 
     First, the contents of the study conducted by the inventor of the present application will be described.  FIG.  1    is a schematic top view showing an overview of a mold  200  of a related manufacturing apparatus. The related manufacturing apparatus is an apparatus for manufacturing a reactor provided with a core. Note that the related manufacturing apparatus may further include an apparatus for opening and closing the mold  200  (not shown), a resin injection apparatus (not shown), etc. A core  10  and a coil mold  20  molded with a resin are inserted into the mold  200 . A reference sign R 1  indicates the resin included in the coil mold  20 . Next, a resin is injected around the core  10  and the coil mold  20  to perform insert molding. A hole h, which is an insertion hole for a bolt or the like, is formed during a molding process.  FIG.  1    shows an internal state of the mold  200  during insert molding. 
       FIG.  1    shows a three-dimensional orthogonal coordinate system of XYZ for clarity of explanation. Note that a Z direction is a vertical direction. Therefore, the Z direction is a height direction. The resin is injected, for example, in a negative direction of a Z-axis. 
     The mold  200  includes a cavity for housing the core  10 . For example, a pair of E-shaped cores  10  are inserted into the cavity. The core  10  may be a sintered product obtained by sintering a compact. 
       FIG.  2    is a schematic top view showing a configuration of the core  10 . The core  10  includes a base core  11 , a middle leg core  12 , and outer leg cores  13   a  and  13   b . Hereinafter, when the outer leg cores  13   a  and  13   b  are not distinguished from each other, they may be referred to simply as the outer leg cores  13 . The middle leg core  12  and the outer leg core  13  project from the base core  11  in the same direction. In  FIG.  2   , an X direction indicates a direction in which the base core  11  is extended, and a Y direction indicates a direction in which the middle leg core  12  and the outer leg core  13  are extended. The coil mold  20  molded with a resin is assembled to the middle leg core  12 . 
     The base core  11  includes a connection part  111   a  for connecting the middle leg core  12  to the outer leg core  13   a , and a connection part  111   b  for connecting the middle leg core  12  to the outer leg core  13   b . Hereinafter, when the connection parts  111   a  and  111   b  are not distinguished from each other, they may be simply referred to as the connection parts  111 . 
     Widths of the outer leg cores  13   a  and  13   b  (e.g., the length thereof in the X direction) are smaller than a width of the middle leg core  12 . In a reactor of a smaller size, the outer leg core  13  may become thinner, and thus the outer leg core  13  may be broken during molding. 
     Returning to  FIG.  1   , the description will be continued. The resin flow paths during molding include inner flow paths  31   a  and  31   b  passing through the inside of the core  10 , an outer flow path  32  passing through the outside of the core  10 , a flow path  33  passing through the inside of the coil mold  20 , and a flow path  34  passing between the two cores  10 . Hereinafter, when the inner flow paths  31   a  and  31   b  are not distinguished from each other, they may be referred to simply as the inner flow paths  31 . When the inner flow paths  31 , the outer flow path  32 , the flow path  33 , and the flow path  34  are not distinguished from each other, they may be simply referred to as the flow paths  30 . In the related mold  200 , a resin is preferentially injected into the outer flow path  32 . Therefore, there is a problem that the core  10  is pressurized from the outside to the inside as indicated by the arrow, and the core  10  is broken. 
       FIG.  3    is a schematic view showing a dimensional relationship between the outer flow path  32  and the inner flow path  31   a  in the mold  200 . In the related mold  200 , a width W 1  of the outer flow path  32  in the X-direction is greater than a width W 2  of the inner flow path  31   a  in the X-direction. In such a case, the outer leg core  13   a  of the core  10  is pressurized in the direction indicated by the rightward arrow. Similarly, a width of the outer flow path  32  in the Y direction is greater than a width of the inner flow path  31   a  in the Y direction. Accordingly, the base core  11  of the core  10  is pressurized in the direction indicated by the downward arrow. Since the mold  200  does not include a mechanism for supporting the core  10  against the resin pressure, there is a possibility that a high stress may be generated in the core  10 , and thus the core may be cracked. 
     In order to prevent the core  10  from being cracked, the inventor studied the relationship between the size of each flow path  30  and the cracking modes of the core  10 .  FIG.  4    is a schematic view showing three cracking modes of the core  10 . A mode  1  occurs when the outer flow path  32  is filled with a resin first. In the mode  1 , the outer leg core  13  is pressurized in the X direction as indicated by the arrow, and a high stress is generated in a part X 1 . A possible cause of the mode  1  may be because there is no support mechanism inside the outer leg core  13 . 
     A mode  2  occurs also when the outer flow path  32  is filled with a resin first. In the mode  2 , the base core  11  is pressurized in the Y direction as indicated by the arrow, and a high stress is generated in a part X 2 . A possible cause of the mode  2  may be because there is no support mechanism inside the base core  11 . 
     A mode  3  occurs when the core  10  is filled with a resin first from an upper side of the core  10 . In the mode  3 , the core  10  is pressurized downward as indicated by the arrow, and a high stress is generated in a part X 3 . A possible cause of the mode  3  may be because there is no support mechanism on a lower side of the core  10  (e.g., on the negative direction side of the Z-axis). 
     The inventor of the present application arrived at the present disclosure according to the embodiment based on the above study. Hereinafter, the present disclosure will be described through an embodiment of the disclosure, but the disclosure according to the claims is not limited to the following embodiment. Further, not all of the configurations described in the embodiment are essential as means for solving the problem. 
     First Embodiment 
     A manufacturing apparatus according to a first embodiment will be described below with reference to the drawings.  FIG.  5    is a schematic top view showing an overview of a mold  100  of the manufacturing apparatus according to the first embodiment. In the following description, differences of the mold  100  of the manufacturing apparatus according to the first embodiment from the mold  200  of the related manufacturing apparatus will be mainly described. 
     The mold  100  includes core support pins  110   a ,  110   b ,  110   c ,  110   d ,  110   e ,  110   f , and  110   g . Hereinafter, when the core support pins  110   a ,  110   b ,  110   c ,  110   d ,  110   e ,  110   f , and  110   g  are not distinguished from each other, they may be referred to simply as the core support pins  110 . Since a resin does not flow into parts of the mold  100  that are in contact with the core support pins  110 , windows corresponding to the core support pins  110  are formed in a molded article. 
     The core support pins  110  are in contact with the core  10  and support the core  10  against the resin pressure during molding. The core support pins  110   a ,  110   b ,  110   c , and  110   d  support the outer leg core  13  against the resin pressure indicated by the arrows in the ±X direction during molding. The core support pins  110   e ,  110   f , and  110   g  support the base core  11  against the resin pressure indicated by the arrows in the ±Y direction during molding. The downward arrow indicates that the resin pressure is received from both of the two inner flow paths  31 . The core support pins  110   e  and  110   f  support the connection part  111  included in the base core  11 . 
     The core support pins  110   a ,  110   b ,  110   c ,  110   d ,  110   e , and  110   f  are located at positions where the widths of the inner flow paths  31  are greater than that of the outer flow path  32 . Some of the core support pins  110  (e.g., the core support pin  110   e ) may be disposed at other positions. 
       FIG.  6    is a schematic view showing a dimensional relationship between the outer flow path  32  and the inner flow path  31   a  in the mold  100 . The outer flow path  32  includes a flow path outside the outer leg core  13   a . The inner flow path  31   a  includes a flow path in a gap between the coil mold  20  and the outer leg core  13   a.    
     In the mold  100 , the width W 2  of the inner flow path  31   a  in the X direction is greater than the width W 1  of the outer flow path  32  in the X direction. In other words, a width of the above-mentioned gap is greater than the width of the flow path outside the outer leg core  13   a . In such a case, the outer leg core  13   a  of the core  10  is pressurized in the direction indicated by the leftward arrow. The core support pin  110   a  supports the outer leg core  13   a  against the pressure in the direction of the leftward arrow to prevent deformation of the outer leg core  13   a.    
     Similarly, the width of the inner flow path  31   a  in the Y direction is greater than the width of the outer flow path  32  in the Y direction. Accordingly, the base core  11  of the core  10  is pressurized in the direction indicated by the upward arrow. The core support pin  110   f  supports the base core  11  against the pressure in the direction of the upward arrow to prevent the deformation of the base core  11 . 
     The mold  100  is designed in such a way that the widths of the inner flow paths  31  become greater than the width of the outer flow path  32 , so that the core  10  can be prevented from being deformed inward and broken. The core  10  is supported from the outside by the core support pins  110 , and thus the mold  100  can prevent the core  10  from being deformed outward and broken. Therefore, the manufacturing apparatus according to the first embodiment can prevent the core  10  from being broken by the resin pressure during molding. 
     Next, a preferred dimensional relationship of the flow paths  30  will be described with reference to  FIGS.  7  to  9   .  FIGS.  7  to  9    shows preferable dimensional relationships between the flow paths  30 . In  FIGS.  7  to  9   , the core support pins  110  are not shown. A reference sign A in  FIG.  7    indicates the width of the inner flow path  31  in the X direction. A reference sign B in  FIG.  7    indicates a width B in the X direction of the outer flow path  32 . A reference sign C in  FIG.  8    indicates the width of the inner flow path  31  in the Y direction. A reference sign D in  FIG.  8    indicates the width of the outer flow path  32  in the Y direction. A reference sign H in  FIG.  9    indicates the width of the above-mentioned flow path  34 . The inventor has found that cracking of the above-described modes  1  to  3  can be prevented by satisfying the following first to third dimensional relationships. 
     Referring to  FIG.  7   , the first dimensional relationship is that A&gt;B and 0.5≤B≤2 (in mm) hold. In relation to the above-described mode  1 , the width of the inner flow path  31  in the X direction is set to be greater than the width of the outer flow path  32  in the X direction. The width of the outer flow path  32  in the X direction can be selected within a range from 0.5 mm to 2 mm. 
     Referring to  FIG.  8   , the second dimensional relationship is that C&gt;D and 0.5≤D≤2 (in mm) hold. In relation to the above-described mode  2 , the width of the inner flow path  31  in the Y direction must be set to be larger than the width of the outer flow path  32  in the Y direction. Furthermore, in relation to the above-described mode  3 , it is necessary to set the width of the outer flow path  32  in the Y direction appropriately. 
     Referring to  FIG.  9   , the third dimensional relationship is that 0.4≤H≤2 (in mm) holds, and at least one of the outer leg cores  13   a  or the outer leg cores  13   b  are in contact with each other. In relation to the above-described modes  2  and  3 , the width of the flow path  34  must be selected within a range from 0.4 mm to 2 mm. 
     In the manufacturing apparatus according to the first embodiment, since the size of the inner flow path is larger than that of the outer flow path, a resin is first injected into the inside of the core  10 , and the core subjected to the resin pressure is supported by the pins provided in the mold. Therefore, the manufacturing apparatus according to the first embodiment can prevent the core  10  from being broken by reducing the deformation of the core and reducing the stress inside the core. 
     Note that the present disclosure is not limited to the above-described embodiment, and may be suitably modified without departing from the spirit. 
     From the disclosure thus described, it will be obvious that the embodiments of the disclosure may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the disclosure, and all such modifications as would be obvious to one skilled in the art are intended for inclusion within the scope of the following claims.