JP2019217707A - Case with insert nut and method of manufacturing the same - Google Patents

Abstract

To provide a case with an insert nut and a method of manufacturing the case, which can prevent poor positioning of the nut during insert molding and prevent poor quality of the case.SOLUTION: A case 1 with an insert nut according to the present invention, is insert molded in a state where a resin holder member 6 integrated with a nut 2 as a nut assembly 7 is pressed into a recess 83 of a molding die 8 through each projection 61. As described above, since the holder member 6 is configured to be press-fittable into the recess 83, the nut 2 is appropriately held in the recess 83 by press-fitting of the holder member 6 into the recess 83 regardless of a manufacturing error of the nut 2. In this state, a resin can be charged into the molding die 8. Thereby, when insert molding the nut 2, an occurrence of a positioning failure of the nut 2 is suppressed, and poor quality of the case 1 can be prevented.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a case with an insert nut, which is applied to, for example, an electronic control device used for an automobile and is formed by insert-molding a nut into a resin case, and a method of manufacturing the case.

  BACKGROUND ART As a conventional electronic control device using a case with an insert nut, the one described in the following patent document is known.

  As shown in FIG. 8, the electronic control device 100 has a boss portion in which a metal nut 102 is insert-molded at each corner of a resin case 101 formed in a rectangular tube shape with one end opened. 103. The circuit board 105 is fixedly fastened to the case 101 together with the cover 106 closing the opening of the case 101 with a plurality of screws 104 screwed to the nuts 102 embedded in the bosses 103.

  Here, in the case 101 described above, each boss portion 103 into which the nut 102 is inserted is formed in a so-called bag shape having a rectangular tube shape with a bottom. For this reason, when manufacturing the case 101, as shown in FIG. 9, the nut 102 is fitted into a concave portion 112 a provided in a stepped shape at the bottom of the lower mold 112, with respect to the forming mold 110 including the upper mold 111 and the lower mold 112. After the positioning, the nut 102 is insert-molded into the boss 103 by filling the inside of the mold 110 with a resin material.

JP 2012-001105 A

  However, in the case 101 of the related art, it is necessary to set the inner diameter R0 of the concave portion 112a in accordance with the maximum tolerance of the outer diameter D0 of the nut 102 for manufacturing. For this reason, when the outer diameter D0 of the nut 102 is formed relatively small within the tolerance range, the nut 102 moves from the recess 112a due to the pressure of the resin to be filled or the vibration of the molding die 110 during the insert molding. There is a risk that the case 101 may fall off, resulting in poor quality of the case 101.

  The present invention has been devised in view of such technical problems, and a case with an insert nut and a method of manufacturing the case with an insert nut capable of suppressing poor nut positioning during insert molding and preventing poor case quality. It is intended to provide.

  The present invention is a case with an insert nut in which the nut is buried in a bottomed cylindrical boss by being filled with a resin while a metal nut is held in a concave portion of a molding die, In one embodiment, the nut is provided integrally with a resin holder member having a plurality of protrusions that can be pressed into the inner surface of the recess, and is embedded in the opening end of the boss through the holder member. Have been.

  Further, as another aspect of the case with the insert nut, each of the protrusions is surrounded by the resin that goes from the opening side of the recess to the bottom side through the space between the protrusions in the boss. desirable.

  As described above, since each of the protrusions is surrounded by the resin that wraps around from the opening side of the recess to the bottom through the space between the protrusions, the holder member in the boss portion is prevented from coming off and from rotating. Thus, the nut can be firmly held on the boss via the holder member.

  As still another mode of the case with the insert nut, each of the protrusions extends in a direction in which the holder member is inserted into the recess, and a contact surface of each of the protrusions that contacts an inner surface of the recess is It is preferable that the projection is formed in an arc shape having a curvature smaller than the curvature of the inner surface of the recess, and each of the protrusions is held in the recess in a state of being in line contact with the inner surface of the recess.

  In this way, by configuring each projection to be in line contact with the recess of the molding die, the work of press-fitting the holder member into the recess can be easily performed, which can contribute to an improvement in productivity of the case.

  Further, as still another aspect of the case with the insert nut, the amount of protrusion of each of the protrusions in the press-fitting direction with respect to the recess gradually increases from the end on the side of press-fitting to the recess toward the end on the opposite side. It is desirable to do.

  In this way, by configuring the amount of protrusion of each protrusion to gradually increase from the end on the press-fit side to the end on the opposite side in the press-fit direction of the holder member, the end on the press-fit side of each protrusion is formed. Are formed in a tapered shape. By this tapered portion, the insertability of each projection into the recess is improved, and the productivity of the case is further improved.

  Furthermore, by configuring the amount of protrusion of each protrusion to gradually increase from the end on the press-fit side to the end on the opposite side in the press-fit direction of the holder member, the inner surface of the concave portion when the holder member is press-fitted is formed. It is possible to reduce the length (area) of each protruding portion that slides. Thereby, the sliding resistance of each projection at the time of press-fitting the holder member is reduced, and the work of press-fitting the holder member can be more easily performed.

  Further, as still another aspect of the case with the insert nut, the holder member has a nut receiving portion for receiving the nut, and the nut is press-fitted into the nut receiving portion, so that the holder member and It is desirable that they are integrally formed.

  As described above, by press-fitting the nut into the nut accommodating portion of the holder member and integrating the nut and the holder member, the nut and the holder member can be firmly connected with a simple structure.

  Further, as still another mode of the case with the insert nut, it is preferable that the nut is integrally formed with the holder member by being insert-molded integrally with the holder member.

  In this way, by integrating the nut and the holder member by insert-molding the nut when manufacturing the holder member, the molding of the holder member and the coupling between the nut and the holder member can be performed simultaneously, This can contribute to an improvement in the productivity of the case.

  Further, as still another aspect of the case with the insert nut, one of an outer surface of the nut and an inner surface of the nut housing portion has an engagement protrusion, and the other can engage with the engagement protrusion. It is desirable to have an engagement recess.

  As described above, by engaging the nut and the holder member with the engagement structure of the engagement projection and the engagement concave portion, the nut can be prevented from coming off from the holder member and can be prevented from rotating.

  Further, from another viewpoint, the present invention provides an insert in which the nut is buried in a bottomed cylindrical boss portion by filling a resin in a state where a metal nut is held in a concave portion of a molding die. In a method of manufacturing a case with a nut, in one embodiment, at least a part of the nut is held by a resin holder member having a plurality of protrusions protruding on an outer peripheral side, and the nut and the holder A first step of integrating the members, and a second step of, after the first step, press-fitting the distal end surfaces of the respective protrusions of the holder member integrated with the nut into the inner surfaces of the recesses of the molding die. And a third step of, after the second step, filling the inside of the mold with a resin while the nut is held in the concave portion via the holder member.

  According to the present invention, instead of disposing the nut directly in the concave portion of the mold, a resin holder member provided integrally with the nut is pressed into the concave portion of the mold via a plurality of protrusions. The nut is insert molded. As described above, since at least the holder member is configured to be press-fittable into the concave portion, the resin can be filled in a state where the nut is appropriately held in the concave portion via the holder member regardless of a manufacturing error of the nut. . Accordingly, in the insert molding of the nut during the manufacture of the case, the occurrence of the defective positioning of the nut is suppressed, and the defective quality of the case can be prevented.

1 is an exploded perspective view of an electronic control device to which a case with an insert nut according to the present invention is applied. It is a perspective view of the case with an insert nut shown in FIG. FIG. 3 is a sectional view taken along line AA of FIG. 2. FIG. 4 is a sectional view taken along line BB of FIG. 3. (A) is an exploded perspective view of a nut and a holder member, and (b) is a perspective view of a nut assembly showing a state in which the nut and the holder member are integrated. (A) is a longitudinal sectional view showing a relationship between a molding die and a nut assembly, and (b) is a sectional view taken along line CC in FIG. 2A and 2B show a manufacturing process of the electronic control device shown in FIG. 1, wherein FIG. 1A is a cross-sectional view showing a process of inserting a nut assembly into a molding die (lower die), and FIG. FIG. 3C is a perspective view showing a state in which the case in which the nut is insert-molded is taken out of the mold, and FIG. 4D is a sectional view of the case showing a step of bending the connector terminal held by the connector portion of the case. FIG. 3E is an exploded perspective view showing a process of inserting a connector terminal into a through hole of a circuit board to electrically connect the connector terminal, and FIG. 4F is a perspective view showing a process of fixing the circuit board to a case. It is a longitudinal section perspective view of an electronic control unit using a conventional case with an insert nut. FIG. 9 is a longitudinal sectional view showing an internal state of a molding die when insert-molding the nut shown in FIG. 8.

  Hereinafter, embodiments of a case with an insert nut and a method for manufacturing the case according to the present invention will be described in detail with reference to the drawings. In the present embodiment, a case in which the case with an insert nut according to the present invention and the method of manufacturing the same are applied to an electronic control device used in an automobile will be described as an example.

(Construction of case with insert nut)
A specific configuration of the electronic control device according to the present embodiment will be described in detail with reference to FIGS.

  As shown in FIG. 1, the electronic control device according to the present embodiment has a resin-made insert nut in which a metal nut 2 is embedded in a boss portion 17 and is integrally formed into a bottomed rectangular tube having one opening. A case (hereinafter abbreviated as “case”) 1, a circuit board 3 housed in the case 1 and fixed to the case 1 with a plurality of screws 4 screwed to a nut 2, and an opening of the case 1 15 for closing the cover 15.

  As a means for fixing the cover (not shown) to the case 1, the cover 1 may be fixed to the case 1 by, for example, welding (vibration welding), or may be fixed to the case 1 by a screw 4 as in the related art. . In other words, the cover fixing means (not shown) can be freely changed as appropriate according to the specifications of the electronic control unit.

  As shown in FIG. 2, the case 1 is integrally formed of a predetermined resin material, and includes a rectangular bottom wall 10 and four side walls that stand upright at the edges of each side of the bottom wall 10. And first to fourth side walls 11 to 14, and an upper portion is formed with an opening. The first side wall 11 is provided with two connector portions 16 for electrical connection to electronic components (not shown) mounted on the circuit board 3 in parallel along the width direction of the first side wall 11. .

  Each of the connector portions 16 is formed in a bottomed rectangular tube shape having the first side wall 11 as a bottom wall, and is provided with a terminal holding portion 161 (see FIG. 7D) provided integrally with the first side wall 11. A male connector is formed by inserting and holding a plurality of connector terminals 5 bent substantially in an L shape. That is, one end of each connector terminal 5 is inserted into the terminal holding portion 161, faces the opening 162 of the connector portion 16, and is connected to a female connector (not shown) connected to the connector portion 16. On the other hand, the other end of each connector terminal 5 is bent upward by 90 °, and is connected to the circuit board 3 covered from the opening 15 side of the case 1.

  In the case 1, bosses 17, which are four board mounting portions for mounting the circuit board 3, are provided upright near each corner of the bottom wall 10. As shown in FIGS. 2 and 3, each boss portion 17 is formed in a substantially cylindrical shape with a bottom that opens upward, and a nut 2 that is a metal insert nut is embedded in the open end. ing. These bosses 17 are formed integrally with the case 1 in a manufacturing process of the case 1 to be described later, with the nut 2 being inserted.

  Here, as described later, the nut 2 is integrally connected to the resin-made holder member 6, is embedded in each boss 17 together with the holder member 6, and is inserted into each boss 17 through the holder member 6. Fixed to. That is, the nut 2 has a cylindrical shape with a bottom, and a so-called bag-like female screw portion 20 that opens upward is formed along the axial direction inside, and an upper end that is the open end side of the outside. The side is exposed to the outside, and the lower end side is housed and held in the holder member 6. As shown in FIGS. 3 and 5, the outer surface of the nut 2 is a region that is accommodated in the holder member 6 and is substantially radially outwardly provided at a substantially intermediate portion in the axial direction. The collision portion 21 is formed in an annular shape that is continuous in the circumferential direction. Further, as shown in FIG. 5A, the engaging projection 21 is formed with an engaging recess 22 which is recessed in a step shape in the circumferential direction and is notched in a groove shape along the axial direction.

  As shown in FIGS. 3 and 4, the holder member 6 is formed integrally with a predetermined resin material, and has a bottomed cylindrical holder body 60 that accommodates the nut 2 therein, A plurality of (three in this embodiment) protrusions 61 protruding radially on the outer peripheral side. In the present embodiment, since the number of the protrusions 61 is set to three, good stability in the recess 83 of the molding die 8 (lower die 82) described later is obtained, and the protrusion is inserted into the recess 83. There is an advantage that the contact area at this time is relatively small and good insertability can be obtained. The number of the protrusions 61 is not limited to the configuration disclosed in the present embodiment, and can be arbitrarily changed according to the specifications of the case 1 such as the fastening torque of the nut 2.

  Further, in the present embodiment, the holder member 6 is formed separately from the nut 2, and is press-fitted into the nut 2 (see FIG. 5A), thereby being integrated with the nut 2 as a nut assembly 7. 5 (see FIG. 5B), and buried in the boss portion 17 (insert molding). The holder member 6 may be integrally formed as a nut assembly 7 by insert-molding the nut 2 when the holder member 6 is formed. As described above, by molding the nut 2 and the holder member 6 integrally with the molding of the holder member 6, the molding of the holder member 6 and the coupling between the nut 2 and the holder member 6 can be performed simultaneously, and the case 1 Can improve productivity.

  A nut accommodating portion 62 that opens upward is formed inside the holder main body 60 along the axial direction. An engagement recess 63 that can engage with the engagement protrusion 21 of the nut 2 is formed in an annular shape along the circumferential direction on the inner side surface of the nut housing portion 62. In other words, the holder member 6 has its engaging concave portion 63 engaged with the engaging protrusion 21 of the nut 2, whereby the axial relative movement with respect to the nut 2 is restricted, and the nut 2 can be prevented from coming off. . Note that the engagement protrusion 21 of the nut 2 and the engagement recess 63 of the holder member 6 may be configured such that the unevenness is reversed. That is, the engagement recess 63 which becomes concave may be provided on the nut 2 side, and the engagement protrusion 21 which becomes convex may be provided on the holder member 6 side.

  As shown in FIG. 5A, an engagement protrusion 64 that can be engaged with the engagement recess 22 of the nut 2 is linearly formed in the engagement recess 63 of the holder member 6 along the axial direction. Is formed. That is, the relative movement of the holder member 6 in the circumferential direction with respect to the nut 2 is restricted by the engagement of the engagement protrusion 64 with the engagement recess 22 of the nut 2, and the rotation of the nut 2 can be prevented. . In addition, the engagement concave portion 22 of the nut 2 and the engagement protrusion 64 of the holder member 6 may be configured such that the unevenness is reversed. That is, the engagement protrusion 64 that is convex may be provided on the nut 2 side, and the engagement recess 22 that is concave may be provided on the holder member 6 side.

  As shown in FIGS. 3 and 4, each of the protrusions 61 is formed in a substantially semicircular cross section with a rounded tip end, and is arranged at substantially equal intervals in the circumferential direction. In other words, each of the protrusions 61 radially protrudes outward in the radial direction of the holder main body 60, has a substantially arc-shaped outer surface, and extends over substantially the entire axial direction of the holder main body 60. It is configured as Further, the outer diameter D2 (see FIG. 6) of the distal end portion 610 of each projection 61 is set to be substantially the same as the outer diameter D3 of each boss 17, and when the holder member 6 is embedded in each boss 17, The distal end 610 of the projection 61 is exposed on the outer peripheral surface of each boss 17. (See FIGS. 2 to 4). Further, each of the protrusions 61 is set to have a curvature smaller than the curvature of the inner surface of a concave portion 83 of the molding die 8 (lower die 82) described later. , So-called line contact with the inner side surface of the concave portion 83.

  In addition, as shown in FIGS. 4 and 5, the present embodiment exemplifies a mode in which the distal end side has the semi-circular cross-section with a rounded tip, but is not limited to this mode. It is not done. In other words, the specific aspect of each projection 61 is not limited to the above-described aspect, but may be, for example, formed in a triangular cross-section, such as the insertability of the holder member 6 into the molding die 8 (lower die 82) described later. It can be changed as needed.

  As shown in FIGS. 3 and 5, the holder member 6 has an opening side of a nut accommodating portion 62 which is a press-fit side end of the holder member 6 with respect to a concave portion 83 of a molding die 8 (lower die 82) described later. The thickness (the amount of protrusion of the protrusion 61) gradually increases from the end on the opening side of the nut housing 62 toward the bottom of the nut housing 62, which is the opposite end. The tapered portion 65 having a substantially conical shape and inclined as described above is provided continuously from the holder main body 60 side to the respective projecting portions 61 side. That is, the press-fitting of the holder member 6 into the concave portion 83 of the molding die 8 (lower die 82) described later is guided (guided) by the tapered portion 65. The tapered portion 65 also functions as a so-called draft, which is used for forming the holder member 6, and can also contribute to improving the formability of the holder member 6.

  On the other hand, as shown in FIG. 3, each boss 17 is formed with an opening at the upper end, and has a nut exposed portion 171 that exposes the end of the nut 2 on the female screw portion 20 side to the outside, and a lower portion from the nut exposed portion 171. And a holder accommodating portion 172 that accommodates and holds the holder member 6. That is, in each of the bosses 17, the holder member 172 accommodated in the holder accommodating portion 172 is formed with the nut exposing portion 171 by forming the holder accommodating portion 172 in a stepped manner with respect to the nut exposing portion 171. Through the step portion 173 formed between the boss portions 17, the dropout from each boss portion 17 is regulated.

  The nut exposure part 171 is set to an inner diameter corresponding to the outer diameter of the nut 2 and holds the nut 2 so as to surround the entire outer peripheral surface of the upper end of the nut 2. As shown in FIGS. 3 and 4, the holder accommodating portion 172 is provided with a main body accommodating portion 174 accommodating the holder main body 60 of the holder member 6, and the holder accommodating portion 174 is recessed radially outside the main body accommodating portion 174. And a plurality of (three in the present embodiment) projection accommodating portions 175 formed in a substantially groove shape capable of accommodating each of the projection portions 61. The main body accommodating portion 174 is set to have an inner diameter larger than the inner diameter of the nut exposed portion 171, and is formed in a stepped manner with respect to the nut exposed portion 171, and corresponds to the outer diameter of the holder main body 60 along the axial direction. Have a constant inner diameter. Each of the protrusion accommodating portions 175 has a substantially semicircular cross section, and is notched along the axial direction at a position corresponding to each of the protrusions 61 of the holder member 6. Surround the entire outer surface except for. That is, the relative rotation of the holder member 6 in the holder accommodating portion 172 is regulated by holding the circumferential end of each of the projecting portions 61 by each of the projection accommodating portions 175.

  As shown in FIG. 1, the circuit board 3 is formed in a rectangular shape with a non-conductive resin material typified by a glass epoxy resin, and a conductor pattern (not shown) is provided on each of the front and back surfaces. A plurality of through holes 31 through which the other end of each connector terminal 5 is inserted are formed in the circuit board 3, and each connector terminal inserted through each of the through holes 31 is connected to the terminal via a solder (not shown). And is electrically connected to the conductor pattern (not shown). Further, in the vicinity of each corner of the circuit board 3 and at a position corresponding to each boss 17 of the case 1, a circular mounting hole 32 through which the screw 4 is inserted to fix the circuit board 3 to the case 1 is provided. It is formed through.

(Production method of case with insert nut)
Before describing a method of manufacturing the case 1 (manufacturing process), a molding die 8 used for manufacturing the case 1 will be described with reference to FIG.

  As shown in FIG. 6 (a), the molding die 8 used for molding the case 1 is provided with a concave portion 83 forming a cavity C forming each boss portion 17, and has a lower die 82 that opens upward and a lower die 82 that opens upward. And an upper mold 81 that covers the opening of the mold 82 and closes the cavity C. The recess 83 is recessed in the bottom wall of the recess 83 and receives the tip end (opening end) of the nut 2 and the nut receiving portion 831 is recessed in the side wall of the recess 83, and substantially the entire holder member 6 is formed. And a holder receiving portion 832 for receiving.

  The nut receiving portion 831 has a substantially circular cross section corresponding to the outer shape of the distal end portion of the nut 2, and is formed in a concave shape at the center position of the bottom wall of the concave portion 83. Further, the nut receiving portion 831 is set to an inner diameter R1 slightly larger than the maximum tolerance of the outer diameter D1 of the nut 2 so that the tip of the nut 2 can be fitted regardless of a manufacturing error of the nut 2. I have.

  As shown in FIGS. 6A and 6B, the holder receiving portion 832 has a circular cross section passing through the apex (tip portion 610) of each protrusion 61 of the holder member 6. It is formed concentrically. Further, the holder receiving portion 832 is set to an inner diameter R2 slightly smaller than the minimum tolerance of the outer diameter D2 of the apex (tip portion 610) of each projection 61, and regardless of the manufacturing error of the holder member 6, The apex (tip 610) of each projection 61 is press-fittable. Here, the holder member 6 press-fitted into the concave portion 83 (holder receiving portion 832) is positioned between the inner surface of the peripheral wall of the holder receiving portion 832 and the outer surface of the holder main body 60 between the circumferential directions of the respective projecting portions 61. , A gap S is formed. Thereby, at the time of molding the case 1, the resin filled from the opening side of the concave portion 83 goes around to the bottom wall side of the concave portion 83 through the gap S, so that the step portion 173 of each boss portion 17 is formed. become.

  As shown in the enlarged view of FIG. 6A, the opening edge of the holder receiving portion 832 has an arc shape (R shape) in which the inner diameter R2 of the concave portion 83 gradually decreases toward the bottom wall side of the concave portion 83. ) Is formed. Thus, when the holder member 6 is press-fitted into the concave portion 83, each projection 61 is guided (guided) by the tapered portion 65, so that the holder member 6 can be easily press-fitted into the concave portion 83. In particular, in the present embodiment, the press-fitting operation of the holder member 6 into the concave portion 83 is further facilitated in combination with the tapered portion 65 provided on the holder member 6 side.

  Hereinafter, a method for manufacturing the case 1 according to the present embodiment will be described in detail with reference to FIGS.

  First, as shown in FIG. 5, the bottom side of the nut 2 is pressed into the nut accommodating portion 62 of the holder member 6, and the engaging projection 21 and the engaging concave portion 22 of the nut 2 are engaged with the engaging concave portion 63 of the holder member 6. The nut 2 and the holder member 6 are integrated with each other by engaging with the engagement protrusion 64 to form the nut assembly 7. Thereafter, as shown in FIG. 7A, the nut assembly 7 is pressed into the concave portion 83 of the lower die 82 of the forming die 8. That is, the holder member 6 of the nut assembly 7 is press-fitted into the holder receiving portion 832 of the concave portion 83 via each of the protrusions 61, and the distal end portion of the nut 2 of the nut assembly 7 is inserted into the nut receiving portion of the concave portion 83. 831. Thereafter, as shown in FIG. 7B, the upper die 81 is fitted to the lower die 82 to close the molding die 8, and the cavity C is filled with the resin P. Then, the resin P filled from the opening side of the concave portion 83 passes through the gap S (see FIG. 6B) formed between the inner side surface of the holder receiving portion 832 and the holder main body 60 of the holder member 6. The case 1 is formed in a state in which the nut assembly 7 is embedded in each boss 17 by forming a step 173 around the bottom wall side of the 83.

  Subsequently, as shown in FIG. 7C, the case 1 in which the nut assembly 7 is insert-molded is taken out from a molding die (not shown), and then, as shown in FIG. The other end (the side facing the inside of the case 1) of each of the inserted connector terminals 5 is bent 90 ° toward the opening 15 side of the case 1. Thereafter, as shown in FIG. 7 (e), the circuit board 3 is inserted from the opening 15 side of the case 1, and the other end of each connector terminal 5 is inserted through each through hole 31 of the circuit board 3. Then, the circuit board 3 is placed on each boss 17 of the case 1. Then, each connector terminal 5 inserted into each through hole 31 of the circuit board 3 is soldered to electrically connect the connector terminal 5 to a conductor pattern (not shown), as shown in FIG. 7 (f). Then, the screw 4 is inserted into each mounting hole 32 of the circuit board 3 and screwed to the nut 2 embedded in each boss 17, whereby the circuit board 3 is fastened (fixed) to each boss 17. Then, the assembly of the electronic control device is completed.

(Operation and effect of the present embodiment)
Hereinafter, the operation and effect of the case 1 according to the present embodiment will be specifically described.

  In the case 101 of the related art, it is necessary to set the inner diameter R0 of the concave portion 112a in accordance with the maximum tolerance of the outer diameter D0 of the nut 102 in manufacturing. With this setting, when the outer diameter D0 of the nut 102 is formed relatively small within the tolerance range, as shown in FIG. The nut 102 may fall off from the concave portion 112a due to vibration or the like, which may lead to poor quality of the case 101.

  On the other hand, in the case 1 according to the present embodiment, the nut 2 is not directly disposed in the recess 83 of the molding die 8, but the resin holder member 6 integrated with the nut 2 as the nut assembly 7 is provided. Insert molding is performed while being pressed into the concave portion 83 of the molding die 8 via each projection 61. As described above, since at least the holder member 6 is configured to be press-fittable into the recess 83, the nut 2 is appropriately held in the recess 83 by press-fitting the holder member 6 into the recess 83 irrespective of a manufacturing error of the nut 2. In this state, the resin can be filled in the molding die 8. Thereby, at the time of insert molding of the nut 2, the occurrence of the positioning failure of the nut 2 is suppressed, and the quality failure of the case 1 can be prevented.

  Further, in the present embodiment, each protrusion 61 of the holder member 6 is formed between the inner surface of the concave portion 83 (holder receiving portion 832) and the outer surface of the holder main body 60 between the protrusions 61. It is surrounded by the resin that goes from the opening side of the concave portion 83 to the bottom wall side through the gap S. That is, the holder member 6 is prevented from falling out of the boss portion 17 by the step portion 173 formed of the resin that goes from the opening side of the concave portion 83 to the bottom wall side via the gap S. At the same time, the holder member 6 is held at the circumferential ends of the projections 61 by the resin that wraps from the opening side of the recess 83 to the bottom wall side via the gap S, so that the holder member 6 in the boss 17 is held. Is stopped. Thus, in the present embodiment, the nut 2 can be firmly held by the boss 17 via the holder member 6.

  In the present embodiment, the contact surface of each projection 61 that contacts the inner surface of the concave portion 83 (holder receiving portion 832) of the molding die 8 is smaller than the curvature of the inner surface of the concave portion 83 (holder receiving portion 832). It is formed in a circular arc shape having a curvature, and each projection 61 is configured to be able to make line contact with the inner side surface of the concave portion 83 (holder receiving portion 832). Therefore, the contact area (sliding resistance) of each projection 61 with the inner surface of the concave portion 83 (holder receiving portion 832) is reduced, and the press-fitting operation of the holder member 6 into the concave portion 83 can be easily performed. Can improve productivity.

  In the present embodiment, the amount of protrusion of each protrusion 61 is configured to gradually increase from the press-fit end to the opposite end in the press-fit direction of the holder member 6. In other words, the end of the protrusion 61 on the press-fit side is formed with a tapered portion 65 whose protrusion amount gradually decreases in the press-fit direction. By such a tapered portion 65, the insertability of each projection 61 into the concave portion 83 (holder receiving portion 832) of the molding die 8 is improved, and the productivity of the case 1 is further improved.

  In addition, by forming the protrusion amount of each of the protrusions 61 gradually from the end on the press-in side to the end on the opposite side in the press-in direction of the holder member 6, molding at the time of press-in of the holder member 6 is performed. It is possible to reduce the length (area) of each projection 61 that slides on the inner surface of the concave portion 83 (holder receiving portion 832) of the mold 8. Thereby, the sliding resistance of each projection 61 at the time of press-fitting the holder member 6 is reduced, and the work of press-fitting the holder member 6 can be performed more easily.

  In the present embodiment, the nut 2 and the holder member 6 are integrated by press-fitting the nut 2 into the nut receiving portion 62 of the holder member 6. Thus, the nut 2 and the holder member 6 can be firmly connected with a simple structure.

  In the present embodiment, in addition to press-fitting the nut 2 into the holder member 6, the nut 2 and the holder member 6 are engaged by engaging the engagement protrusion 21 of the nut 2 with the engagement recess 63 of the holder member 6. 6 are integrated. Thereby, relative movement of the nut 2 with respect to the holder member 6 in the axial direction, that is, falling off is restricted, and the nut 2 and the holder member 6 can be more firmly connected.

  In addition, in the present embodiment, the engagement protrusion 64 provided on the engagement recess 63 of the holder member 6 is engaged with the engagement recess 22 provided on the engagement protrusion 21 of the nut 2. The relative movement of the nut 2 relative to the nut 6 in the circumferential direction, that is, the relative rotation is restricted, so that the nut 2 and the holder member 6 can be more firmly connected.

  The present invention is not limited to the configuration exemplified in the above embodiment, and can be freely changed in accordance with the specification of the application object or the like without departing from the gist of the present invention.

1: Case (case with insert nut)
17 Boss part 2 Nut 21 Engagement protrusion 22 Engagement concave part 4 Screw 6 Holder member 61 Projection part 63 Engagement concave part 64 Engagement protrusion 8 Molding die 83 concave part

Claims (5)

A case with an insert nut, wherein the nut is buried in a bottomed tubular boss by being filled with resin while holding a metal nut in a concave portion of a molding die,
The nut is provided integrally with a resin holder member having a plurality of protrusions that can be press-fitted into the inner surface of the recess, and is embedded in the opening end of the boss via the holder member. A special case with insert nut.   The case with an insert nut according to claim 1, wherein each of the protrusions is surrounded by the resin that goes from the opening side to the bottom side of the recess through the space between the protrusions in the boss. . Each of the protrusions extends in a direction in which the holder member is inserted into the recess,
The contact surface of each of the protrusions that contacts the inner surface of the recess is formed in an arc shape having a curvature smaller than the curvature of the inner surface of the recess,
The case with an insert nut according to claim 1, wherein each of the protrusions is held in the recess in a state of being in line contact with an inner surface of the recess. The holder member has a nut storage portion that stores the nut,
The case with an insert nut according to any one of claims 1 to 3, wherein the nut is press-fitted into the nut accommodating portion to be integrally formed with the holder member. A method for manufacturing a case with an insert nut, wherein the nut is buried in a bottomed cylindrical boss by being filled with resin in a state where a metal nut is held in a concave portion of a molding die,
A first step of holding at least a part of the nut by a resin-made holder member having a plurality of protrusions protruding on an outer peripheral side, and integrating the nut and the holder member;
After the first step, a second step of press-fitting the distal end surface of each of the protrusions of the holder member integrated with the nut into the inner surface of the concave portion of the molding die;
A third step of filling the inside of the mold with a resin while the nut is held in the recess through the holder member after the second step;
A method for manufacturing a case with an insert nut, comprising:

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