Method for manufacturing resin molded body

Abstract

Provided is a resin molded body manufacturing method that increases variation in product shape of a resin molded body, and prevents electric conductor deformation and mold breakage.　This resin molded body manufacturing method comprises: a mold preparation step for preparing a movable-side mold and a fixed-side mold; a positioning step for positioning an electric conductor in the fixed-side mold; a closing step for closing the molds and accommodating the electric conductor in the molds; an injection step for injecting a liquefied resin into the molds; a curing step for curing the resin inside the molds and fixing a part of the electric conductor to the resin; and an opening step for separating the movable-side mold from the fixed-side mold. In the mold preparation step, a mold having a groove that accommodates at least a portion of the electric conductor is prepared. The groove has a groove bottom wall having a bottom wall surface with which the electric conductor is brought into surface contact, and a pair of groove lateral walls having tapered surfaces that are inclined from the groove bottom wall so as to expand toward a groove opening provided in a position opposite the groove bottom wall. The height of the pair of groove lateral walls is half the distance between adjacent electric conductors.

Description

[Technical Field]

[0001] The present invention relates to a method for producing a resin molded article. [Background technology]

[0002] When manufacturing a resin molded product having a metal terminal therein, resin is injected into the mold with the metal terminal placed therein. During this process, the metal terminal may be deformed due to the force of the resin flow within the mold. To prevent the metal terminal from being swept horizontally and deformed by the force of the resin flow within the mold, it is known to provide the mold with a structure that engages with the side of the metal terminal downstream of the resin flow direction. For example, a protrusion located between multiple metal terminals may be used as the structure for engaging the side of the metal terminal. In injection molding of thermoplastic resins, such a structure can generally only be provided on the fixed mold where the metal terminal is installed, which places constraints on the design of the product shape of the resin molded product. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-163303 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-190596 Summary of the Invention [Problem to be solved by the invention]

[0004] The mounting portion for the metal terminal provided on the fixed mold (usually the lower mold) has a surface that comes into close contact with the metal terminal in order to form an exposed surface on the metal terminal that will be used to join the metal terminal to the circuit board by wire bonding, etc. Specifically, the mounting portion is a groove into which the metal terminal fits, and the fixed mold has protrusions located between the metal terminals, which serve to lock the side of the metal terminal downstream in the resin flow direction and prevent deformation of the metal terminal in the horizontal direction.

[0005] A structure (e.g., a protrusion) for engaging the side surface of a metal terminal is generally provided on a fixed mold. If a protrusion for engaging the side surface of a metal terminal is provided on a movable mold (upper mold), the movable mold approaches the fixed mold so that the groove forming the exposed surface covers the metal terminal, which is an insert part set in the fixed mold (lower mold), and the protrusion is inserted between the metal terminals. In this case, dimensional changes or misalignment of the metal terminal of the insert part may cause the protrusion on the movable mold to come into contact with the metal terminal, resulting in molding defects such as deformation of the metal terminal or the formation of foreign matter (burrs, cracks, etc.), and damage to the mold. For this reason, a structure for engaging the side surface of a metal terminal is usually provided in parallel on a fixed mold, which limits the variety of product shapes of resin molded products.

[0006] Patent Document 1 describes a technique for positioning the arrangement direction and thickness direction of each lead terminal within a recess in a second mold by clamping a lead frame from above and below between a first mold and a second mold. With the technique described in Patent Document 1, the mounting base is molded while positioning the lead terminals within the recess so as not to shift laterally. However, because the lead terminals are positioned within the recess while in contact with the wall surface of the recess in the second mold, there is a risk of deformation of the lead terminals or damage to the mold.

[0007] Patent Document 2 describes a technique in which a recess into which a metal terminal can be fitted is formed in an upper mold that constitutes a resin molding die, and a pin that contacts the back surface of the metal terminal is formed in a lower mold, and the metal terminal is sandwiched between the recess and the pin. However, with the technique described in Patent Document 2, when the metal terminal is fitted into the recess of the upper mold, the upper mold comes into contact with the metal terminal, which may cause deformation of the metal terminal or damage to the mold.

[0008] The present invention has been made in consideration of the above circumstances, and aims to provide a method for manufacturing a resin molded body that can increase the variety of product shapes of the resin molded body while preventing deformation of the electrical conductor and damage to the mold. [Means for solving the problem]

[0009] In order to solve the above problems, the manufacturing method of the resin molded article according to the present invention is a manufacturing method of the resin molded article in which an electrical conductor is placed in a mold and resin is injected, and includes a mold preparation step of preparing a movable mold and a fixed mold as the mold, a positioning step of positioning a part of the electrical conductor in the fixed mold, a closing step of closing the mold by bringing the movable mold into contact with the fixed mold and accommodating the electrical conductor in the mold, an injection step of injecting liquefied resin into the mold, and a step of hardening the resin in the mold to encapsulate the electrical conductor. The method comprises a curing step of fixing a portion of the electrical conductor to the resin, and an opening step of separating the movable mold from the fixed mold, wherein in the mold preparation step, a mold having a groove for accommodating at least a portion of the electrical conductor is prepared, the groove having a groove bottom wall having a bottom wall surface with which the electrical conductor comes into surface contact, and a pair of groove side walls having tapered surfaces that are inclined so as to widen from the groove bottom wall toward a groove opening provided at a position opposite the groove bottom wall, and the height of the pair of groove side walls is half the distance between adjacent electrical conductors. [Effects of the Invention]

[0010] According to the method for manufacturing a resin molded product of the present invention, it is possible to increase the variety of product shapes of the resin molded product while preventing deformation of the electrical conductor and damage to the mold. Further features related to the present invention will become apparent from the description of this specification and the accompanying drawings. In addition, problems, configurations, and effects other than those described above will become apparent from the description of the following embodiments. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is an overall view of a resin molded body manufactured by a manufacturing method according to the present invention. [Figure 2] Cross section AA of Figure 1. [Figure 3] 1A to 1C are diagrams illustrating steps of a manufacturing method according to a first embodiment of the present invention. [Figure 4] FIG. 4 is an enlarged cross-sectional view illustrating one step of the manufacturing method shown in FIG. 3. [Figure 5] FIG. 4 is an enlarged cross-sectional view illustrating one step of the manufacturing method shown in FIG. 3. [Figure 6] 4A to 4C are diagrams illustrating the migration prevention effect achieved by the manufacturing method shown in FIGS. [Figure 7] FIG. 6 is an enlarged cross-sectional view illustrating a mold used in a manufacturing method according to a second embodiment of the present invention. [Figure 8] FIG. 10 is an enlarged cross-sectional view illustrating a mold used in a manufacturing method according to a third embodiment of the present invention. [Figure 9] FIG. 10 is an enlarged cross-sectional view illustrating a mold used in a manufacturing method according to a fourth embodiment of the present invention. [Figure 10] FIG. 11 is an enlarged cross-sectional view illustrating a mold used in a manufacturing method according to a fifth embodiment of the present invention. [Figure 11] FIG. 10 is an enlarged cross-sectional view illustrating one step of a manufacturing method according to the prior art. [Figure 12] 12 is an enlarged cross-sectional view illustrating a step different from the step shown in FIG. 11. [Figure 13] FIG. 10 is an enlarged cross-sectional view illustrating one step of another manufacturing method according to the prior art. [Figure 14] FIG. 14 is an enlarged cross-sectional view illustrating a step different from the step shown in FIG. 13. [Figure 15] 1A and 1B are diagrams illustrating migration in a manufacturing method according to the prior art. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, a method for manufacturing a resin molded article according to an embodiment of the present invention will be described in detail with reference to the drawings.

[0013] First, an airflow sensor (resin molded product) 1 manufactured by a manufacturing method according to an embodiment of the present invention will be described with reference to Figures 1 and 2. Figure 1 is an overall view of the airflow sensor 1 manufactured by the manufacturing method according to the present invention. Figure 2 is a cross-sectional view taken along line AA in Figure 1.

[0014] 1, the air flow sensor 1 includes a resin main body 1a, a metal terminal (electrical conductor) 2 that is an insert part, and a substrate 17 that is electrically connected to the metal terminal 2. One end of the metal terminal 2 is electrically connected to an external control device (not shown) or the like. One end of the metal terminal 2 is located in a connector portion 6 of the resin main body 1a.

[0015] As shown in FIGS. 1 and 2, the metal terminal 2 is electrically connected at its other end to the substrate 17 via an aluminum wire 4. The metal terminal 2 has an exposed surface 3 at its other end that is not covered by the resin body 1a. The exposed surface 3 is a portion of the metal terminal 2 that is exposed to the outside from the resin body 1a. An aluminum wire 4 is welded (wire bonded) to the exposed surface 3 to electrically connect the metal terminal 2 to the substrate 17. To form the exposed surface 3 at the other end of the metal terminal 2, a mold 15 (described below) used to manufacture the airflow sensor 1 is provided with a groove 7. A gate 5 is also formed in the airflow sensor 1, and resin is injected into the mold 15 from the gate 5 as shown by resin flow 8 in FIG. 2.

[0016] Here, a method for manufacturing a resin molded body according to conventional technology will be described. Fig. 11 is an enlarged cross-sectional view illustrating one step of the manufacturing method according to conventional technology. Fig. 12 is an enlarged cross-sectional view illustrating a step different from the step shown in Fig. 11. Figs. 11 and 12 illustrate a case where a groove 10c for installing a metal terminal 2 is provided in a fixed mold 10.

[0017] As shown in FIG. 11 , a mold 15 has a fixed mold 10 (also referred to as a lower mold) and a movable mold 9 (also referred to as an upper mold). Conventionally, a groove 10c into which a metal terminal 2 fits is formed in the fixed mold (also referred to as a lower mold) 10, and the metal terminal 2 is placed in the groove 10c and injection molded to form an air flow sensor 1. The fixed mold 10 has a protrusion shape 10b between adjacent grooves 10c, i.e., between the metal terminals 2. Because the metal terminal 2 is placed in the fixed mold 10 and injection molded in this manner, it has been common for the exposed surface 3 of the metal terminal 2 to be formed by the fixed mold 10.

[0018] As shown in FIG. 12, protrusions 10b are positioned between the metal terminals 2, and when the mold 15 is closed, the metal terminals 2 are restrained in the vertical direction by the fixing pins 9p and the grooves 10c. Therefore, even if resin is injected into the mold 15 and a resin flow 8 occurs within the mold 15, the metal terminals 2 are swept away by the resin flow 8, suppressing horizontal deformation of the metal terminals 2. Furthermore, the depth of the grooves 10c is formed shallower than the thickness of the metal terminals 2. As a result, the surfaces of the metal terminals 2 other than the exposed surface 3 (including part of the side surface 2a) are covered with resin. As a result, the metal terminals 2 are fixed to the resin body 1a, and deformation of the metal terminals 2 is prevented when the aluminum wire 4 is welded to the exposed surface 3 of the metal terminals 2 after molding.

[0019] Conventionally, from the viewpoint of mold protection, it has been difficult to provide a groove 10c for fitting the metal terminal 2 in the movable mold (upper mold) 9. Fig. 13 is an enlarged cross-sectional view illustrating one step of another manufacturing method according to conventional technology. Fig. 14 is an enlarged cross-sectional view illustrating a step different from the step shown in Fig. 13. Figs. 13 and 14 illustrate a case where a groove 9d for installing the metal terminal 2 is provided in the movable mold 9.

[0020] 14, when the movable mold 9 is brought close to the fixed mold 10 and the mold 15 is closed, the protrusions 9f formed between the grooves 9d are inserted between the metal terminals 2. Furthermore, with the mold 15 closed, the metal terminals 2 are restrained in the vertical direction by the fixing pins 10d and the grooves 9d. If the metal terminals 2 are displaced from their fixed positions 19 relative to the grooves 9d due to factors such as dimensional changes or deformation of the metal terminals 2, the protrusions 9f of the movable mold 9 and the metal terminals 2 may collide, causing damage to both.

[0021] To avoid damage to the metal terminal 2 and the mold 15, the groove for fitting the metal terminal 2 is generally provided in the fixed mold 10, and conventionally, the exposed surface 3 of the metal terminal 2 has generally been formed by the fixed mold 10. For this reason, it is necessary to select a shape for the product shape of the airflow sensor 1 such that the exposed surface 3 of the metal terminal 2 is formed by the fixed mold 10, which places restrictions on expanding the variety of product shapes of the airflow sensor 1.

[0022] First Embodiment A method for manufacturing a resin molded product according to the first embodiment will be described. In this embodiment, a case where the groove 7 is formed in the movable mold 9 will be described, but the groove 7 may also be formed in the fixed mold 10. In the manufacturing method according to this embodiment, a metal terminal (electrical conductor) 2 is placed in a mold 15, and resin is injected to mold the air flow sensor 1.

[0023] Fig. 3 is a diagram illustrating steps of a manufacturing method according to a first embodiment of the present invention. Fig. 4 is an enlarged cross-sectional view illustrating a step of the manufacturing method shown in Fig. 3. Fig. 5 is an enlarged cross-sectional view illustrating a step of the manufacturing method shown in Fig. 3. Fig. 6 is a diagram illustrating the migration prevention effect of the manufacturing method shown in Fig. 3.

[0024] As shown in FIG. 3, the method for manufacturing the air flow sensor 1 according to the first embodiment includes a mold preparation step S1, a positioning step S2, a closing step S3, an injection step S4, a curing step S5, and an opening step S6.

[0025] The mold preparation step S1 is a step of preparing a movable mold 9 and a fixed mold 10 as the mold 15. As shown in FIGS. 4 and 5, the movable mold 9 of the mold 15 has a groove 7 that accommodates at least a portion of the metal terminal 2 when the mold 15 is closed. The groove 7 has a groove bottom wall 7g having a bottom wall surface 9g with which the metal terminal 2 comes into surface contact, and a pair of groove side walls 7b, 7b having tapered surfaces 9b that incline so as to widen from the groove bottom wall 7g toward a groove opening 7a provided at a position opposite the groove bottom wall 7g. One end of the pair of groove side walls 7b, 7b is connected to the groove bottom wall 7g. The bottom wall surface 9g and the pair of tapered surfaces 9b, 9b are formed facing the interior of the groove 7. The groove 7 has a groove opening 7a at a position opposite the bottom wall surface 9g.

[0026] By tilting the pair of groove sidewalls 7b, 7b, resin can be filled into the space between the side surface 2a of the metal terminal 2 and the tapered surface 9b in the injection step S4 described below. Filling the side surface 2a of the metal terminal 2 with resin increases the amount of resin covering the metal terminal 2 after molding, improving the fixing strength of the metal terminal 2. As shown in FIG. 6, covering the side surface 2a of the metal terminal 2 with resin prevents water droplets 150 from adhering to the side surface 2a of the metal terminal 2, thereby increasing the distance to a short circuit due to migration. Therefore, compared to the conventional manufacturing method shown in FIG. 15, the risk of migration caused by water droplets 150 adhering between the metal terminals 2 can be reduced. Furthermore, since the metal terminal 2 is more firmly fixed, the substrate 17 and the metal terminal 2 can be more reliably welded with the aluminum wire 4.

[0027] In the movable mold 9, a top wall surface 9c is formed between adjacent grooves 7. The top wall surface 9c is a part of the top wall 7c, and the top wall 7c connects the other ends of the groove side walls 7b, 7b of adjacent grooves 7. The top wall surface 9c faces the same direction as the bottom wall surface 9g. The top wall surface 9c may be formed to be convexly curved toward the fixed mold 10, or may be formed flat. The top wall 7c is positioned offset from the groove bottom wall 7g in the arrangement direction of the metal terminals 2. In this way, the movable mold 9 in this embodiment is provided with a repeated arrangement of the groove bottom wall 7g, groove side wall 7b, top wall 7c, groove side wall 7b, and groove bottom wall 7g.

[0028] Since the bases 20 of the pair of groove side walls 7b, 7b lock the corners of the metal terminal 2 on the exposed surface 3 side, the metal terminal 2 can be restrained in the horizontal direction relative to the direction of the resin flow 8.

[0029] In this embodiment, height 17b of a pair of groove side walls 7b, 7b is half of distance 17a between adjacent metal terminals 2. The higher height 17b of groove side walls 7b, the greater the effect of preventing deformation of metal terminal 2 due to collision with movable mold 9. However, from the viewpoint of suppressing a decrease in strength of movable mold 9, height 17b of groove side walls 7b is preferably half of distance 17a between metal terminals 2. The inventors have found that height 17b of groove side walls 7b of mold 15 is preferably up to about 70% of the width of distance 17a between metal terminals 2, and if groove side walls 7b have a height exceeding 70% of distance 17a between metal terminals 2, there is a risk of mold 15 being damaged.

[0030] The inclination angle 18 of the pair of groove side walls 7b, 7b is preferably 25° to 45° with respect to the vertical direction of the movable mold 9 (FIG. 4). The smaller the inclination angle 18 of the pair of groove side walls 7b, 7b, the greater the effect of locking the metal terminal 2. However, to prevent the viscous resin material from being left unfilled, it is preferable that the inclination angle 18 be greater than 25°. Furthermore, if the inclination angle 18 is greater than 45°, when the metal terminal 2 comes into contact with the tapered surface 9b as the mold 15 closes, the force pushing the metal terminal 2 vertically becomes dominant over the force moving the metal terminal 2 horizontally. Therefore, the tapered surface 9b is less effective in guiding the metal terminal 2 to the fixed position 19. Therefore, it is preferable that the inclination angle 18 be less than 45°.

[0031] Furthermore, height 17b of the pair of groove side walls 7b, 7b is preferably half the thickness 17c of metal terminal 2. This reduces the area over which resin injected from gate 5 into mold 15 directly collides with side surface 2a of metal terminal 2, and reduces horizontal stress on metal terminal 2, thereby preventing deformation of metal terminal 2 due to resin flow 8.

[0032] As shown in Figures 4 and 5, in the mold preparation step, a mold 15 is prepared that has a flow changer 10a at a position on the fixed mold 10 that faces the bottom wall surface 9g of the movable mold 9. The flow changer 10a has a collision surface 10n that collides with the liquefied resin injected in the injection step S4. The collision surface 10n at least partially changes the direction of the resin flow 8 toward the coating surface 3a of the metal terminal 2. Therefore, when the resin flow 8 occurs with the mold 15 closed, the resin flow 8 and the bottom wall surface 9g restrict vertical movement of the metal terminal 2.

[0033] In this way, the fixed mold 10 does not have a fixing pin 10d (FIGS. 13 and 14) that prevents deformation of the metal terminal 2 in a direction perpendicular to the direction of the resin flow 8. This makes it possible to sandwich the metal terminal 2 between the fixing pin 10d and the bottom wall surface 9g of the movable mold 9, which forms the exposed surface 3 of the metal terminal 2, thereby reducing the risk of damaging the metal terminal 2.

[0034] As shown in Fig. 4, the positioning step S2 is a step of positioning a portion of the metal terminal 2 in the fixed mold 10. The metal terminal 2 is fixed at one end and the other end to the fixed mold 10. For example, one end of the metal terminal 2 (the connector portion 6 side) may be fixed to the fixed mold 10 by a slide piece. The other end of the metal terminal 2 (the exposed surface 3 side) may be fixed to the fixed mold 10 by inserting the other end into a pin.

[0035] The closing step S3 is a step of closing the mold 15 by bringing the movable mold 9 into contact with the fixed mold 10, and accommodating the metal terminal 2 in the mold 15. In the closing step S3, when the metal terminal 2 comes into contact with the bottom wall surface 9g that forms the exposed surface 3, if the metal terminal 2 is not in a fixed position 19 relative to the groove 7, the metal terminal 2 comes into contact with the tapered surface 9b, and the metal terminal 2 can be guided along the tapered surface 9b to the bottom wall surface 9g without being sandwiched by the mold 15.

[0036] 5, the injection step S4 is a step of injecting liquefied resin into the mold 15. In this embodiment, the resin injected into the mold 15 may be not only a thermoplastic resin but also a thermosetting resin.

[0037] The curing step S5 is a step of curing the resin in the mold 15 and fixing a part of the metal terminal 2 to the resin. When the thermoplastic resin is injected into the mold 15 in the injection step, the resin is cured by cooling.

[0038] The opening step S6 is a step of separating the movable mold 9 from the fixed mold 10.

[0039] According to the manufacturing method of this embodiment, the groove 7 that accommodates a portion of the metal terminal 2 is formed in the movable mold 9. Therefore, even if misalignment, dimensional change, or deformation of the metal terminal 2 occurs in the positioning step S2, these can be flexibly absorbed and the metal terminal 2 can be guided to the groove bottom wall 7g via the tapered surface 9b. Therefore, in the closing step S3, damage, deformation, and foreign matter to the mold 15 and the metal terminal 2 that may occur when the metal terminal 2 and the movable mold 9 collide can be prevented, and a structure for locking the metal terminal 2 can be provided without the limitations of the fixed mold 10 and the movable mold 9.

[0040] Furthermore, because the height 17b of the pair of groove side walls 7b, 7b is set to half the distance 17a between adjacent metal terminals 2, it is possible to prevent the strength of the movable mold 9 from becoming excessively high while obtaining a structure for locking the metal terminal 2 (the bases 20 of the pair of groove side walls 7b, 7b). Therefore, even if the metal terminal 2 comes into contact with the groove side wall 7b, deformation of the metal terminal 2 and damage to the mold 15 and the metal terminal 2 can be avoided. In this way, even if the groove 7 is provided in the movable mold 9, the mold 15 and the metal terminal 2 are not damaged. Therefore, it is possible to select the product shape of the air flow sensor 1 in which the orientation of the exposed surface 3 of the metal terminal 2 is formed by the movable mold 9, thereby expanding the variety of product shapes.

[0041] Second Embodiment Next, a second embodiment of the present invention will be described. Fig. 7 is an enlarged cross-sectional view illustrating a mold 15 used in a manufacturing method according to the second embodiment of the present invention.

[0042] In the manufacturing method according to the second embodiment, in the mold preparation step S1, a mold 15 is prepared in which a pair of groove side walls 7b, 7b have tapered surfaces, including a groove bottom tapered surface 11a located on the groove bottom wall 7g side and an opening tapered surface 11b that is continuous with the groove bottom tapered surface 11a and located on the groove opening 7a side. The angle between the side surface 2a of the metal terminal 2 and the opening tapered surface 11b perpendicular to the bottom wall surface 9g is 45 degrees or less. The angle between the side surface 2a of the metal terminal 2 and the groove bottom tapered surface 11a is smaller than the angle between the side surface 2a of the metal terminal 2 and the opening tapered surface 11b. Thus, the movable mold 9 has two tapered surfaces 11a, 11b with different angles as the tapered surfaces of the pair of groove side walls 7b, 7b. Note that the tapered surfaces of the pair of groove side walls 7b, 7b may be tapered surfaces with three or more different angles.

[0043] By making the opening-side tapered surface 11b at a larger angle than the groove bottom-side tapered surface 11a with respect to the side surface 2a of the metal terminal 2 that is perpendicular to the bottom wall surface 9g, the groove opening 7a becomes wider, making it easier to bring the metal terminal 2 into contact with the opening-side tapered surface 11b and to insert the metal terminal 2 into the groove 7. Also, by making the groove bottom-side tapered surface 11a at a smaller angle than the opening-side tapered surface 11b, a structure can be created that makes it easier to lock the metal terminal 2.

[0044] Third Embodiment Next, a third embodiment of the present invention will be described. Fig. 8 is an enlarged cross-sectional view illustrating a mold 15 used in a manufacturing method according to the third embodiment of the present invention.

[0045] In the manufacturing method according to the third embodiment, in the mold preparation step S1, a mold 15 is prepared in which portions 12 of a pair of groove side walls 7b, 7b located on the groove bottom wall 7g side are formed to have an R-shaped cross section. In this way, one end of the pair of groove side walls 7b, 7b is connected to the groove bottom wall 7g via the R-shaped portions 12.

[0046] Providing the R-shaped portion 12 that smoothly connects the groove side walls 7b, 7b and the groove bottom wall 7g improves the strength of the movable mold 9. Also, since the amount of resin that fills the side surface 2a of the metal terminal 2 can be increased, the fixing strength of the metal terminal 2 to the resin main body 1a can be improved.

[0047] <Fourth embodiment> Next, a fourth embodiment of the present invention will be described. Fig. 9 is an enlarged cross-sectional view illustrating a mold 15 used in a manufacturing method according to the fourth embodiment of the present invention. Fig. 9 illustrates a case in which the opening-side tapered surface 13a and the vertical surface 13b are provided on the fixed mold 10, but the opening-side tapered surface 13a and the vertical surface 13b may also be provided on the movable mold 9.

[0048] In the manufacturing method according to the fourth embodiment, in the die preparation step S1, a die 15 is prepared in which a pair of groove side walls 18b, 18b have, as tapered surfaces, opening-side tapered surfaces 13a located on the groove opening 7a side. Furthermore, the die 15 is prepared in which the pair of groove side walls 18b, 18b have vertical surfaces 13b located on the groove bottom wall 18g side, continuing from the opening-side tapered surfaces 13a. The vertical surfaces 13b are perpendicular to the bottom wall surface 10g and are formed facing the interior of the groove 7. In this way, the die 15 is structured so that the opening-side tapered surface 13a is located on the groove opening 7a side of the groove 7, where the metal terminal 2 is inserted, and the vertical surfaces 13b are continuous with the tapered surfaces 13a and extend to the bottom wall surface 10g.

[0049] By providing an opening-side tapered surface 13a on the groove opening 7a side of the groove 7 and widening the groove opening 7a, it becomes easier to insert the metal terminal 2 into the groove 7. In addition, by providing a vertical surface 13b located on the groove bottom wall 18g side, it is possible to further improve the effect of preventing deformation of the metal terminal 2 in the horizontal direction due to the resin flow 8.

[0050] Fifth Embodiment Next, a fifth embodiment of the present invention will be described. Fig. 10 is an enlarged cross-sectional view illustrating a mold 15 used in a manufacturing method according to the fifth embodiment of the present invention.

[0051] In the manufacturing method according to the fifth embodiment, in the mold preparation step S1, a mold 15 having a curved top wall surface 9c of the top wall 7c is prepared as the mold 15. Specifically, the top wall surface 9c is formed to have an R-shape that is convex toward the fixed mold 10.

[0052] In this way, by making the top wall surface 9c of the movable mold 9 rounded, the strength of the movable mold 9 is improved. Sharp edges can be eliminated from the movable mold 9, and even if the top wall surface 9c comes into contact with the metal terminals 2 when the top wall 7c is inserted between the metal terminals 2, damage to the metal terminals 2 and the movable mold 9 can be suppressed. In addition, foreign matter on the metal terminals 2 due to dents, peeling plating, etc. can be reduced.

[0053] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various design modifications can be made without departing from the spirit of the present invention as defined in the claims. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations. [Explanation of symbols]

[0054] 1: resin molded body (air flow sensor), 2: metal terminal (electrical conductor), 7: groove, 7a: groove opening, 7b: pair of groove side walls, 7g: groove bottom wall, 9b: tapered surface, 9g: bottom wall surface, 10a: flow change portion, 11a: groove bottom tapered surface, 11b: opening side tapered surface, 12: R-shaped portion, 17a: distance between metal terminals, 17b: height of groove side wall, 17c: height of metal terminal, 9: movable side mold, 10: fixed side mold, 15: mold, S1: mold preparation process, S2: positioning process, S3: closing process, S4: injection process, S5: curing process, S6: opening process

Claims

1. A method for manufacturing a resin molded article by placing an electrical conductor in a mold and injecting resin, a mold preparation step of preparing a movable mold and a fixed mold as the mold; a positioning step of positioning a portion of the electrical conductor in the fixed mold; a closing step of closing the mold by bringing the movable mold into contact with the fixed mold, and accommodating the electrical conductor within the mold; an injection step of injecting liquefied resin into the mold; a curing step of curing the resin in the mold to fix a portion of the electrical conductor to the resin; an opening step of separating the movable mold from the fixed mold, A method for manufacturing a resin molded body, characterized in that in the mold preparation step, a mold having a groove that accommodates at least a portion of the electrical conductor is prepared as the mold, the groove having a groove bottom wall having a bottom wall surface with which the electrical conductor makes surface contact, and a pair of groove side walls having tapered surfaces that incline so as to widen from the groove bottom wall toward a groove opening provided at a position opposite the groove bottom wall, and the height of the pair of groove side walls is half the distance between adjacent electrical conductors.

2. 2. The method for manufacturing a resin molded body according to claim 1, wherein in the mold preparation step, a mold in which the height of the pair of groove side walls is half the thickness of the electrical conductor is prepared as the mold.

3. 2. A method for manufacturing a resin molded body as described in claim 1, characterized in that in the mold preparation process, the mold has a tapered surface having a groove bottom tapered surface located on the side of the groove bottom wall and an opening side tapered surface that is continuous with the groove bottom tapered surface and is located on the side of the groove opening, and the angle between the side of the electrical conductor perpendicular to the bottom wall surface and the opening side tapered surface is 45 degrees or less, and the angle between the side of the electrical conductor and the groove bottom side tapered surface is smaller than the angle between the side of the electrical conductor and the opening side tapered surface.

4. The method for manufacturing a resin molded body according to claim 1, characterized in that in the mold preparation process, a mold is prepared in which the portions of the pair of groove side walls located on the side of the groove bottom wall are formed with an R-shaped cross section.

5. The method for manufacturing a resin molded body described in claim 1, characterized in that in the mold preparation process, a mold is prepared as the mold, which is positioned opposite the bottom wall surface and has a flow change portion against which the liquefied resin injected in the injection process collides, at least partially changing the flow direction of the resin toward the electrical conductor.

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