WO2009017303A1

WO2009017303A1 - The injection mold apparatus and method for making bobbin having core

Info

Publication number: WO2009017303A1
Application number: PCT/KR2008/003151
Authority: WO
Inventors: Jong-Won Park
Original assignee: Jong-Won Park
Priority date: 2007-07-30
Filing date: 2008-06-05
Publication date: 2009-02-05
Also published as: KR100812974B1

Abstract

Disclosed are a mold for fabricating a core-integrated bobbin and a method of fabricating such a bobbin using the mold. The core-integrated bobbin fabricating mold includes a movable mold 100 and a stationary mold 200. The movable mold 100 includes: at least one lower cavity 110 forming a space spaced from a mold center CL2, a core Co being mounted in the space 110 in such a manner that the core is spaced from the inner wall of the space; at least one first actuation pin 121 with a top end being actuated through a bottom wall 111 of a corresponding lower cavity 110, the top end of the first actuation pin supporting the bottom side of the core Co before molten resin is introduced into the mold, and the top end of the first actuation pin being retracted after the molten resin is introduced into the mold, thereby releasing the supporting of the bottom side of the core Co; at least one second actuation pin 122 for removing a molded bobbin B; and at least one third actuation pin 123 for cleaning out a sprue Sp and a runner Rn after the molding is completed. The stationary mold 200 includes: at least one upper cavity forming a space spaced from a mold center CLl, the core Co being mounted in the space in such a manner that the core is spaced from the inner wall of the space; at least one actuation pin 200 with a lower end actuated through the top of the upper cavity 210, the lower end of the actuation pin 220 supporting the top side of the core Co before the molten resin is introduced into the mold, and the lower end of the actuation pin 220 being retracted after the molten resin is introduced into the mold, thereby releasing the supporting of the top side of the core Co.

Description

THE INJECTION MOLD APPARATUS AND METHOD FOR MAKING BOBBIN HAVING CORE

Technical Field

[1] The present invention relates to a mold for fabricating a core-integrated bobbin, in which the core-integrated bobbin is fabricated by inserting a core into a mold for injection molding, and then actuating various actuating pins by spring action, resin pressure, injection pressure, hydraulic pressure, and pneumatic pressure, so that an insulation layer with an even thickness is injection-molded in the entirety of the outer circumferential surface of the core, whereby the surface of the core is not exposed to the outside. The present invention also relates to a method of fabricating a bobbin using the above-mentioned mold. Background Art

[2] In general, various coils form an electric field when electric current is made to flow through a conductive electric wire (e.g., a copper wire or the like) wound around a bobbin having a cylindrical core, or conduct predetermined functions together with a circuit component or the like connected to the coils, respectively, when they are soldered to various circuit boards.

[3] FIG. 1 is a perspective view showing a conventional bobbin for a coil, and FIG. 2 is a perspective view showing an outer appearance of a conventional bobbin formed by injection-molded separate caps.

[4] As shown in the drawings, a conventional bobbin Bl formerly used for coils is provided with an insulation layer I in a state in which a core Nl is installed inside the bobbin Bl. An insulation material, such as a thin film, is wound around the outer circumferential surface of the core Nl many times so as to insulate the core Nl. Alternatively, a material, such as urethane, is sprayed and cured on an area corresponding to one half of the outer circumferential surface of the core, and then the same material is sprayed on the remaining surface, thereby coating the entirety of the outer circumferential surface (FIG. 1).

[5] However, the above-mentioned spray coating method is usually performed through a manual operation, which requires long working time, and thus is ineffective. As a result, another method has been considered. Molded caps Ml and M2 for wrapping the upper and lower parts of the core Nl are formed through injection molding, and fitted on the core Nl from the top and bottom sides of the core Nl, respectively, so that the surface of the core Nl is not exposed, and then an electric wire Na for a coil is wound around the outer circumferential surface formed with an insulation layer, thereby fabricating a coil suitable for an intended purpose.

[6] However, the above-mentioned method, in which each of molds Ml and M2 is molded, and the molds Ml and M2 are fitted on the core Nl so as to wrap the core Nl, inevitably has problems in that manufacturing costs are increased since the mold caps Ml and M2 should be separately molded, whereby many steps should be performed, including fitting the mold caps Ml and M2 on the core Nl, and setting the mold caps Ml and M2 through a manual operation, and the defect rate is increased due to the increase of the number of the steps and components needed. Disclosure of Invention Technical Problem

[7] Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art, and the present invention is to provide a mold for fabricating a core-integrated bobbin, in which the core-integrated bobbin is capable of being fabricated by inserting a core into a mold for injection molding, and then making an insulation layer with an even thickness injection-molded on the entirety of the outer circumferential surface of the core, so that the surface of the core is not exposed to the outside, and to provide a method of fabricating such a bobbin using the above- mentioned mold. Technical Solution

[8] The above-mentioned object of the present invention can be achieved by a molding method including the steps of: inserting a plurality of cores into a mold at predetermined positions, respectively; introducing molten synthetic resin for use in injection molding into the mold in a state in which the cores are continuously retained at their original positions; and then finishing the molding, so that an insulation layer with a uniform thickness can be formed around the outer circumferential surface of each of a plurality of cores, and the molded bobbins can be automatically removed from the injection mold.

Advantageous Effects

[9] According to the inventive core-integrated bobbin fabricating mold and method, there is an advantage in that, by setting molding conditions in such a manner that after the movable mold is most remotely spaced from the stationary mold, plural cores are inserted into the stationary mold, and then continuously retained at their original mounting positions while molten resin is being injected, it is possible to produce uniform bobbins.

[10] In addition, according to the inventive core-integrated bobbin fabricating mold and method, there is an advantage in that, by arranging at least one first actuation pin, a second actuation pin, and a third actuation pin of the movable mold, and an actuation pin of the stationary mold to cooperate with each other, and in particular, the actuation pins are actuated by at least three of spring action, injection pressure, hydraulic pressure, and pneumatic pressure, the fabrication steps can be variously modified.

[11] Moreover, according to the present invention, it is possible to simultaneously mold as many bobbins as possible and to reduce the defect rate, whereby it is possible to substantially reduce costs for manufacturing bobbins which are superior in an insulation property. Brief Description of the Drawings

[12] The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

[13] FIG. 1 is a perspective view showing a conventional bobbin for coils;

[14] FIG. 2 is a perspective view showing an outer appearance of a conventional bobbin formed by injection-molding separate caps;

[15] FIG. 3 is a top plan view showing a movable mold of the inventive core-integrated bobbin fabricating mold;

[16] FIG. 4 is a partial enlarged view showing respective lower cavities shown in FIG. 3;

[17] FIG. 5 is a stationary mold of the inventive core-integrated bobbin fabricating mold;

[18] FIG. 6 is a sectional view of the inventive mold taken along the direction A-A in

FIG. 3 before molten resin is introduced into the mold;

[19] FIG. 7 is a sectional view of the inventive mold taken along the direction B-B in FIG.

3 before molten resin is introduced into the mold;

[20] FIG. 8 is a sectional view of the inventive mold taken along the direction A-A in

FIG. 3 after molten resin is introduced into the mold; and

[21] FIG. 9 is a sectional view of the inventive mold taken along the direction B-B in FIG.

3 after molten resin is introduced into the mold. Mode for the Invention

[22] Hereinafter, preferred embodiments of the inventive mold for fabricating a core- integrated bobbin, and a method fabricating such a bobbin will be described with reference to the accompanying drawings.

[23] The inventive mold for fabricating a core-integrated bobbin includes a movable mold and a stationary mold, wherein the movable mold includes at least one lower cavity forming at least one space spaced from the center of the movable mold, a core being mounted in the space in such a manner as to be spaced from the inner wall of the space; at least one first actuation pin with a top end actuated through a bottom of the lower cavity, the top end of the first actuation pin supporting the bottom side of the core before molten resin is introduced into the mold, and the top end of the first actuation pin being retracted after the molten resin is introduced into the mold, thereby releasing the supporting of the bottom side of the core; at least one second actuation pin for removing a completely molded bobbin; and at least one third actuation pin for cleaning out a sprue and a runner after the molding is completed, and wherein the stationary mold includes: at least one upper cavity forming at least one space spaced from the center of the stationary mold, the core being mounted in the space in such a manner that the core is spaced from the inner wall of the space; and at least one actuation pin with a lower end actuated through the top of the upper cavity, the lower end of the actuation pin supporting the top side of the core before the molten resin is introduced into the mold, and the lower end of the actuation pin being retracted after the molten resin is introduced into the mold, thereby releasing the supporting of the top side of the core.

[24] The inventive method for fabricating a core-integrated bobbin by using the above- mentioned mold includes the steps of: mounting the core in the lower cavity; moving the movable mold toward the stationary mold; introducing molten resin into the space formed by the upper cavity in the stationary mold and the lower cavity in the movable mold; moving the actuation pin of the stationary mold and the first actuation pin of the movable mold, so that the first actuation pin and the actuation pin project from the bottom of the lower cavity and the top of the upper cavity, respectively, thereby supporting the core; returning the actuation pin of the stationary mold and the first actuation pin of the movable mold to their original positions; and actuating the second and third actuation pins of the movable mold, thereby removing a molded bobbin.

[25] Now, each of the above-mentioned components will be described.

[26] The movable mold of the inventive core-integrated bobbin fabricating mold is a component that is moved in relation to the stationary mold, thereby being opened or closed, so that a bobbin, which is injection-molded as molten resin is introduced into and cooled in the mold, can be automatically removed. The lower core mounted at the center of the movable mold is formed with at least one lower cavity, and at least one first actuation pin and a second actuation pin are provided to extend through the bottom of the lower cavity. In addition, a third actuation pin is provided at the center of the lower cavity to extend through the bottom of the lower cavity.

[27] The first actuation pin of the movable mold does not project upward from the bottom of the cavity when the movable mold is opened. However, if the movable mold is moved toward the stationary mold and closed, and then molten resin is introduced into the mold after the first actuation pin is actuated and projects upward from the bottom of the lower cavity, thereby supporting the bottom side of the core. As a result, after the molten resin is cooled so that the bobbin is molded, the resin uniformly wraps the outer circumferential surface of the core. After the bobbin is molded, a pin mark with a predetermined depth is formed only at an area where the first action pin is positioned. An electric wire wound around the outer circumferential surface of the bobbin will not directly come into contact with the internally positioned core, thereby being insulated from the core. The first actuation pin is returned to its original position by a spring before a process for molding another bobbin is performed, and retained in the state in which the first actuation pin does not project upward from the bottom of the lower cavity.

[28] After the movable mold in the opened state is moved toward the stationary mold, thereby being closed, the second actuation pin of the movable mold does not project upward from the bottom of the lower cavity while the molten is being introduced into the mold. After the molten resin is cooled so that a bobbin is molded, the second actuation pin projects upward from the bottom of the lower cavity in cooperation with the first actuation pin, thereby pushing the bottom side of the core upward. As a result, the molded resin at a pin gate area is cut and the molded bobbin is automatically removed. The second actuation pin is returned to its original position by a spring, after its operation is completed.

[29] In addition, the third actuation pin of the movable mold is continuously maintained at a position below the bottom of the lower cavity at the center of the lower cavity while the molten is being introduced into the mold after the movable mold in the opened state is moved toward the stationary mold, thereby being closed. After the molten resin is cooled so that a bobbin is molded and then automatically removed in cooperation with the first actuation pin, the third actuation pin is lifted so that the sprue and the runner are automatically cleaned out. After completing the operation, the third actuation pin is returned to its original position by a spring.

[30] The stationary mold of the inventive core-integrated bobbin fabricating mold is a component which is closed or opened by the movable mold moved in relation to the stationary mold, so that a bobbin, which is injection-molded as molten resin is introduced into the mold and cooled, can be automatically removed. The upper core mounted at the center of the stationary mold is formed with at least one upper cavity, and at least one actuation pin extending through the top of the upper cavity is provided in the stationary mold.

[31] The actuation pin of the stationary mold is actuated in such a manner that its bottom end extends through the top of the upper cavity. Before molten resin is introduced into the mold, the actuation pin supports the top side of the core, and is retracted (lifted) by the resin pressure and the injection pressure while the molten resin is being introduced into the mold, thereby releasing the supporting of the top side of the core. The actuation pin is returned to its original position after completing the operation.

[32] According to a characteristic feature of the present invention, the first actuation pin, the second actuation pin and the third actuation pin of the movable mold, and the actuation pin of the stationary mold, are arranged to cooperate with each other. Beyond actuating the first actuation pin by applying resin pressure and injection pressure, and returning the first actuation pin by a spring, it is also possible to apply hydraulic pressure or pneumatic pressure to the first actuation pin, the second actuation pin and the third actuation pin of the movable mold, and to the actuation pin of the stationary mold, so that the actuation pins can be slid, and to employ springs so as to return the actuation pins to their original positions. Now, a description will be made as to how injection pressure is applied so as to actuate the actuation pins.

[33] In the inventive core-integrated bobbin fabricating method, the step of mounting a core in each lower cavity of the movable mold is a step performed in preparation for integrally fabricating a core within the bobbin through insert injection molding. The step of moving the movable mold toward the stationary mold forms one or more spaces, each of which is formed of cavities in a set of molds as the molds are engaged with each other. In this manner, one or more spaces are obtained, into which molten resin is introduced. The molten resin is sequentially introduced into the spaces formed by the upper cavities in the stationary mold and the lower cavities in the movable mold, respectively.

[34] According to the inventive core-integrated bobbin fabricating method, in the step of moving the actuation pin of the stationary mold and the first actuation pin of the movable mold, the core is evenly spaced from the inner circumferential surface of a space formed by a pair of top and bottom cavities, whereby it is assured that the core is not exposed to the outer circumferential surface of a bobbin while the bobbin is being injection-molded, so that an insulation layer can be securely formed.

[35] In addition, according to the inventive core-integrated bobbin fabricating method, a plurality of bobbin products, sprues, and runners are automatically cleaned out as the step of returning the actuation pin of the stationary mold and the first actuation pin of the movable mold, and the step of actuating the second and third actuation pins of the movable mold, are performed.

[36] Hereinbelow, embodiments of the inventive core-integrated bobbin fabricating mold and method will be described with reference to accompanying drawings.

[37] FIG. 3 is a top plan view showing a movable mold in the inventive core-integrated bobbin fabricating mold, and FIG. 4 is a partial enlarged view showing respective lower cavities shown in FIG. 3.

[38] As shown in the drawings, the movable mold 100 of the inventive mold for fabricating a core-integrated bobbin includes a lower core Uc provided at the center of a lower disc plate Up which is stacked on and fixed to the top of a bottom fixing plate Uf through at least one bottom leg B R , wherein the lower core Uc includes: at least one lower cavity 110 spaced from the center CL2 of the movable mold and forming at least one space, a core Co being mounted in the space in such a manner that the core is spaced from the inner wall of the space; at least one first actuation pin 121, with a top end actuated through the bottom 111 of the lower cavity 110, the top end supporting the bottom side of the core Co before molten resin is introduced into the mold, and the top end of the first actuation pin 121 being retracted after the molten resin is introduced into the mold, thereby releasing the supporting of the bottom side of the core Co; at least one second actuation pin 122 for extracting a completely molded bobbin B; and at least one third actuation pin 123 for cleaning out a sprue Sp and a runner Rn after the molding is completed.

[39] The undescribed symbol Pg indicates a guide pin.

[40] FIG. 5 is a top plan view showing a stationary mold of the inventive core-integrated bobbin fabricating mold.

[41] As shown in the drawing, the stationary mold 200 of the inventive core-integrated bobbin fabricating mold includes an upper core Uc at the center of an upper disc plate stacked on and fixed to the bottom of an upper fixing plate Uf, wherein the upper core Uc includes at least one upper cavity 210 spaced from the center CLl of the stationary mold and forming a space, a core Co being mounted in the space in such a manner that the core is spaced from the inner wall of the space; and at least one actuation pin 200 with a lower end actuated through the top of the upper cavity 210, the lower end of the actuation pin 220 supporting the top side of the core Co before molten resin is introduced into the mold, and the lower end of the actuation pin 220 being retracted to release the supporting the top side of the core Co after the molten resin is introduced into the mold.

[42] The undescribed symbol h indicates a guide pin resting slot.

[43] FIG. 6 is a sectional view of the inventive mold taken in the direction A-A in FIG. 3 before molten resin is introduced into the mold, and FIG. 7 is a sectional view of the inventive mold taken in the direction B-B in FIG. 3 before molten resin is introduced into the mold. In addition, FIG. 8 is a sectional view of the inventive mold taken in the direction A-A in FIG. 3 after molten is introduced mold, and FIG. 9 is a sectional view of the inventive mold taken in the direction B-B in FIG. 3 after molten resin is introduced into the mold.

[44] The inventive core-integrated bobbin fabricating method using the above-mentioned core-integrated bobbin fabricating mold includes the steps of: mounting the core Co at the center of the lower cavity 110 by inserting the core Co (SlO); moving the movable mold 100 toward the stationary mold 200 so that that the movable mold is closed (S20); introducing molten resin into the space, which is formed by an upper cavity 210 in the stationary mold 200 and a lower cavity 110 in the movable mold 100, so that molding is implemented (S30); moving the at least one actuation pin 220 of the stationary mold 200 and the at least one first actuation pin 121, so that the first actuation pin 121 and the actuation pin 220 project from the bottom 111 of the lower cavity 110 and the top 211 of the upper cavity 210, respectively, thereby supporting the core Co to be evenly spaced from the inner circumferential surface of the cavity 210 (S40); returning the actuation pin 220 in the stationary mold 200 and the first actuation pin 121 in the movable mold 100 to their original positions, so that no pin mark is produced on the outer surface of a molded bobbin (S50); and actuating the second actuation pin 122 in the movable mold 100, thereby automatically removing a molded bobbin B, and actuating the third actuation pin 123, thereby automatically cleaning out a sprue and a runner (S 60).

[45] As shown in the drawings, before the resin is introduced, the first actuation pin 121 of the movable runner part 100 of the inventive mold 100 is retained without projecting upward from the bottom 111 of the lower cavity 110 (see FIGs. 6 and 7), and as the molten resin is introduced into the mold, the first actuation pin 121 and the actuation pin 220 are moved toward the core Co to be adjacent to each other through the bottom 111 of the lower cavity 110 and the top 211 of the upper cavity 210. Consequently, a predetermined space is continuously maintained between the inner circumferential surface of the space formed by the lower and bottom cavities and the core Co (see FIGs. 8 and 9), whereby, when the molten resin is introduced, an insulation layer is retained without exposing the core Co from the outer circumferential surface of the bobbin B.

[46] In addition, after the molten resin is cooled so that the molding is completed, the movable mold is moved, and the second actuation pin 122 is actuated, thereby removing the molded bobbin B, and the third actuation pin 123 is actuated, thereby cleaning out the sprue Sp and the runner Rn. Industrial Applicability

[47] Although preferred embodiments of the present invention have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. Therefore, the present invention is not limited to the embodiments described above.

Claims

[1] A mold for fabricating a core-integrated bobbin comprising a movable mold 100 and a stationary mold 200, wherein the movable mold 100 comprises: at least one lower cavity 110 forming a space spaced from a mold center CL2, a core Co being mounted in the space 110 in such a manner that the core is spaced from the inner wall of the space; at least one first actuation pin 121 with a top end being actuated through a bottom wall 111 of a corresponding lower cavity 110, the top end of the first actuation pin supporting the bottom side of the core Co before molten resin is introduced into the mold, and the top end of the first actuation pin being retracted after the molten resin is introduced into the mold, thereby releasing the supporting of the bottom side of the core Co; at least one second actuation pin 122 for removing a molded bobbin B; and at least one third actuation pin 123 for cleaning out a sprue Sp and a runner Rn after the molding is completed, and wherein the stationary mold 200 comprises: at least one upper cavity forming a space spaced from a mold center CLl, the core Co being mounted in the space in such a manner as to be spaced from the inner wall of the space; at least one actuation pin 200 with a lower end actuated through the top of the upper cavity 210, the lower end of the actuation pin 220 supporting the top side of the core Co before the molten resin is introduced into the mold, and the lower end of the actuation pin 220 being retracted after the molten resin is introduced into the mold, thereby releasing the supporting of the top side of the core Co.

[2] The mold as claimed in claim 1, wherein the first actuation pin 121, the second actuation pin 122, the third actuation pin 123, and the actuation pin 220 are actuated by any of injection pressure, hydraulic pressure, and pneumatic pressure.

[3] The mold as claimed in claim 2, wherein after having been actuated, the first actuation pin 121, the second actuation pin 122, the third actuation pin 123, and the actuation pin 220 are returned to their original positions by springs, respectively.

[4] A method of fabricating a core integrated bobbin by using a core-integrated bobbin fabricating mold comprising a movable mold 100 and a stationary mold 200, wherein the movable mold 100 comprises: at least one lower cavity 110 forming a space spaced from a mold center CL2, a core Co being mounted in the space 110 in such a manner that the core is spaced from the inner wall of the space; at least one first actuation pin 121 with a top end being actuated through a bottom wall 111 of a corresponding lower cavity 110, the top end of the first actuation pin supporting the bottom side of the core Co before molten resin is introduced into the mold, and the top end of the first actuation pin being retracted after the molten resin is introduced into the mold, thereby releasing the supporting of the bottom side of the core Co; at least one second actuation pin 122 for removing a molded bobbin B; and at least one third actuation pin 123 for cleaning out a sprue Sp and a runner Rn after the molding is completed, and wherein the stationary mold 200 comprises: at least one upper cavity forming a space spaced from a mold center CLl, the core Co being mounted in the space in such a manner as to be spaced from the inner wall of the space; at least one actuation pin 200 with a lower end actuated through the top of the upper cavity 210, the lower end of the actuation pin 220 supporting the top side of the core Co before the molten resin is introduced into the mold, and the lower end of the actuation pin 220 being retracted after the molten resin is introduced into the mold, thereby releasing the supporting of the top side of the core Co., the method comprising the steps of: mounting the core Co in the lower cavity 110 (SlO); moving the movable mold 100 toward the stationary mold 200 (S20); introducing molten resin into the space formed by the upper cavity 210 in the stationary mold 200 and the lower cavity 110 in the movable mold 100 (S30); moving the actuation pin 220 of the stationary mold 200 and the first actuation pin 121 of the movable mold 100, so that the first actuation pin 121 and the actuation pin 220 project from the bottom 111 of the lower cavity 110 and the top 211 of the upper cavity 210, respectively, thereby supporting the core Co (S40); returning the actuation pin 220 of the stationary mold 200 and the first actuation pin 121 of the movable mold 100 to their original positions (S50); and actuating the second actuation pin 122 of the movable mold 100, thereby removing a molded bobbin B (S 60).

[5] The method as claimed in claim 4, wherein the first actuation pin 121, the second actuation pin 122, the third actuation pin 123, and the actuation pin 220 are actuated by any of injection pressure, hydraulic pressure, and pneumatic pressure.

[6] The method as claimed in claim 5, wherein after having been actuated, the first actuation pin 121, the second actuation pin 122, the third actuation pin 123, and the actuation pin 220 are returned to their original positions by springs, respectively.