Mold for molding and method for producing molded article

Abstract

This mold (1) for molding, which is used to obtain an electronic control device (100), has a cavity (8) for molding the electronic control device (100), a first wall surface part (42) bordering the cavity (8) and facing a bottom part (2) of the cavity (8), and a second wall surface part (41) bordering the cavity (8) and extending toward the bottom part (2) relative to the first wall surface part (42). The second wall surface part (41) is water-repellent, and the first wall surface part (42) is more hydrophilic than the second wall surface part (41).

Description

Molding die and method for manufacturing molded product

[0001] The present invention relates to a molding die used for obtaining a molded product and a method for manufacturing a molded product obtained using this molding die.

[0002] In recent years, in vehicles such as automobiles, an electronic control unit for controlling the operating state of an electric motor or the operating state of vehicle-mounted components has come to be used. In such an electronic control unit, in order to protect a circuit board or electronic components, etc., it is common to adopt a configuration in which the periphery of the circuit board or electronic components is covered with resin.

[0003] In such a situation, Patent Document 1 discloses, in a conventional example, a method for manufacturing an electronic circuit block in which, with a part of a substrate inserted into a resin receiving container, resin is poured into the resin receiving container from an upper opening, and the resin is injected so that the liquid level of the resin reaches a position for sealing an electronic component mounted on the substrate, and after the resin is solidified or cured, the electronic circuit block is removed from the resin receiving container.

[0004] Japanese Patent Application Laid-Open No. 2001-210960

[0005] However, in Patent Document 1, when a liquid material is supplied into the cavity, the liquid material rises along the wall portion facing the cavity due to the surface tension of the supplied liquid material and then cures, resulting in a problem of generating burrs protruding outside the molded product during mold release or the like.

[0006] An object of the present invention is to provide a molding die and a method for manufacturing a molded product capable of suppressing the generation of burrs protruding outside the molded product.

[0007] To achieve the above object, the present invention is a molding die used for obtaining a molded product, having a cavity for molding the molded product, a first wall surface portion facing the cavity and facing the bottom of the cavity, and a second wall surface portion facing the cavity and continuous with the first wall surface portion on the bottom side, the second wall surface portion having water repellency, and the first wall surface portion having higher hydrophilicity than the second wall surface portion as one aspect.

[0008] According to one aspect of the present invention, a molding die used to obtain a molded product comprises a cavity for molding the molded product, a first wall portion facing the cavity and facing the bottom of the cavity, and a second wall portion facing the cavity and connected to the bottom side of the first wall portion, wherein the second wall portion is water-repellent and the first wall portion is more hydrophilic than the second wall portion, thereby suppressing the generation of burrs protruding outward from the molded product.

[0009] Figure 1 is a side view of a molding die according to the first embodiment of the present invention. Figure 2 is a plan view of a molding die according to the first embodiment of the present invention. Figure 3 is a cross-sectional view taken along line A-A in Figure 2. Figure 4 is an enlarged cross-sectional view of a part of the molding die according to the first embodiment of the present invention. Figure 5 is a cross-sectional view of a molded product formed by the molding die according to the first embodiment of the present invention. Figure 6 is a cross-sectional view of a part of a molded product formed by the molding die according to the first embodiment of the present invention. Figure 7 is an enlarged cross-sectional view of a part of a molding die according to the second embodiment of the present invention. Figure 8 is a cross-sectional view of a part of a molded product formed by the molding die according to the second embodiment of the present invention.

[0010] Hereinafter, the molding die in the embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the drawings, the x, y, and z axes form a three-axis orthogonal coordinate system, with the positive direction of the y axis being the forward direction, the negative direction of the y axis being the backward direction, the positive direction of the x axis being the right direction, the negative direction of the x axis being the left direction, the positive direction of the z axis being the upward direction, and the negative direction of the z axis being the downward direction.

[0011] (First Embodiment) <Configuration of the Molding Mold> The configuration of the molding mold 1 according to the first embodiment of the present invention will be described in detail with reference to Figures 1 to 4.

[0012] The molding die 1 is integrally formed from a flexible and breakable sheet-like member such as a synthetic resin material, and has a bottom portion 2, a right side wall portion 3, a left side wall portion 4, an inclined wall portion 5, a front wall portion 6, a rear wall portion 7, a cavity 8, an opening 9, a protrusion 10, a row of recesses 31, an overhang 32, a second wall portion 41, and a first wall portion 42. The bottom portion 2, the right side wall portion 3, the left side wall portion 4, the inclined wall portion 5, the front wall portion 6, and the rear wall portion 7 constitute the cavity 8.

[0013] The bottom portion 2 has its longitudinal direction in the front-to-back direction and its short direction in the left-to-right direction. The bottom portion 2 connects the lower end of the right side wall portion 3, the lower end of the inclined wall portion 5, the lower end of the front wall portion 6, and the lower end of the rear wall portion 7. The bottom portion 2 constitutes the bottom of the cavity 8, which closes the lower end side of the cavity 8.

[0014] The right side wall section 3 connects the front end of the bottom section 2, the right end of the front wall section 6, and the right end of the rear wall section 7.

[0015] The left side wall section 4 connects the upper end of the inclined wall section 5, the left end of the front wall section 6, and the left end of the rear wall section 7.

[0016] The inclined wall section 5 connects the left end of the bottom section 2, the lower end of the left side wall section 4, the left end of the front wall section 6, and the left end of the rear wall section 7. The inclined wall section 5 slopes downward from the lower end of the left side wall section 4 towards the right side wall section 3.

[0017] The front wall section 6 connects the front end of the right wall section 3, the front end of the left wall section 4, and the front end of the bottom section 2.

[0018] The rear wall section 7 connects the rear end of the right wall section 3, the rear end of the left wall section 4, and the rear end of the bottom section 2.

[0019] Cavity 8 is a space enclosed by the bottom portion 2, the right side wall portion 3, the left side wall portion 4, the inclined wall portion 5, the front wall portion 6, and the rear wall portion 7. Cavity 8 is used to mold the electronic control device 100, which will be described later, as a molded product.

[0020] The opening 9 connects the upper side of the cavity 8 to the outside.

[0021] The protrusion 10 extends to the right from the upper end of the right side wall 3, increasing the thickness of the right side wall 3. The protrusion 10 is provided from the viewpoint of improving the strength of the right side wall 3 and improving the grip of the worker.

[0022] The row of recesses 31 is formed continuously from the lower end of the right side wall portion 3, through the upper end of the right side wall portion 3, to the right end of the protrusion 10. The row of recesses 31 is formed in pairs with a gap between them in the front and back. Note that the row of recesses 31 is not limited to being formed in pairs; one or three or more may be formed.

[0023] The protruding portion 32 is bent inward from the upper ends of the right side wall portion 3, the left side wall portion 4, the front wall portion 6, and the rear wall portion 7 at an angle of approximately 90 degrees relative to each of the right side wall portion 3, the left side wall portion 4, the front wall portion 6, and the rear wall portion 7, and protrudes into the cavity 8. The protruding portion 32 is provided along the opening 9.

[0024] The second wall portion 41 covers the inner surfaces of the bottom portion 2, right side wall portion 3, left side wall portion 4, inclined wall portion 5, front wall portion 6, and rear wall portion 7 on the cavity 8 side, and also faces the cavity 8. The second wall portion 41 is connected to the first wall portion 42 on the bottom portion 2 side. The second wall portion 41 is formed to be water-repellent by applying a water-repellent treatment, such as applying a water-repellent coating agent to the inner surfaces of the bottom portion 2, right side wall portion 3, left side wall portion 4, inclined wall portion 5, front wall portion 6, and rear wall portion 7 on the cavity 8 side. The water-repellent coating agent contains, for example, a silicone resin or a fluororesin. Note that in Figure 3, the description of the second wall portion 41 is omitted for convenience of explanation.

[0025] The first wall portion 42 covers the inner surface of the protruding portion 32 on the cavity 8 side and faces the cavity 8. The first wall portion 42 has higher hydrophilicity than the second wall portion 41. The first wall portion 42 is formed by applying a hydrophilic treatment, such as applying a hydrophilic coating agent to the inner surface of the protruding portion 32 on the cavity 8 side. The hydrophilic coating agent contains, for example, a zinc ion salt such as zinc acetate and polyacrylamide. Note that in Figure 3, the description of the first wall portion 42 is omitted for the sake of explanation.

[0026] The mold 1 having the above configuration is a container-shaped member into which potting resin material 200a is injected from the opening 9 into the cavity 8 and which can accommodate the potting resin material 200a inside the cavity 8, and is used when manufacturing an electronic control device 100.

[0027] <Method for Manufacturing an Electronic Control Device> A method for manufacturing an electronic control device 100 using a molding die 1 according to the first embodiment of the present invention will be described in detail with reference to Figures 1 to 6.

[0028] Here, the molded electronic control device 100 is a control device such as an ECU (Electronic Control Unit) that controls the operating state of a drive source such as an internal combustion engine or electric motor of a vehicle such as an automobile, and has a configuration in which a part of the device body C is protected by a potting resin body 200. Specifically, the device body C includes, as an example, a circuit board 101 having a conductive part (not shown), various electronic components 102a, 102b, 102c and 102d such as a CPU (Central Processing Unit), memory and capacitors mounted on the circuit board 101, and a connector 103 in which a pin terminal 103a that electrically connects the conductive part of the circuit board 101 to an external connection device (not shown) is surrounded by a mating part 103b. Furthermore, the circuit board 101, electronic components 102a, 102b, 102c, 102d, and a portion of the pin terminals 103a of the device body C are protected by a potting resin body 200.

[0029] First, the device body C is positioned in a predetermined location within the cavity 8 of the molding mold 1. Then, molten potting resin material 200a is supplied from the opening 9 into the gaps between the device body C and each of the bottom 2, right side wall 3, left side wall 4, inclined wall 5, front wall 6, and rear wall 7, and filled by gravity. At this time, the molten potting resin material 200a is filled into the cavity 8 to a position where it contacts the first wall surface 42. As a result, the entire circuit board 101, electronic components 102a, 102b, 102c, and 102d are immersed in the potting resin material 200a, and a part of the connector 103 on the circuit board 101 side is also immersed in the potting resin material 200a.

[0030] Next, after a predetermined time has elapsed under predetermined environmental conditions, the potting resin material 200a filled in the gaps between the main body of the device C and each of the bottom 2, right side wall 3, left side wall 4, inclined wall 5, front wall 6, and rear wall 7 hardens, and as shown in Figure 5, the main body of the device C and the potting resin body 200 become one, resulting in an electronic control device 100 in which the main body of the device C is protected by the potting resin body 200.

[0031] When the molten potting resin 200a is supplied into the cavity 8, the second wall portion 41 wets and spreads the potting resin 200a as it fills the cavity 8, and the surface tension of the potting resin 200a causes it to rise in direction A in Figure 4. As the potting resin 200a rises in direction A and reaches the first wall portion 42, the first wall portion 42, which is more hydrophilic than the second wall portion 41, pulls the potting resin 200a inward in direction B in Figure 4. The potting resin 200a pulled in direction B is held in place at the tip of the first wall portion 42 in direction B due to the surface tension of the potting resin 200a. As a result, an edge portion E1 (see Figure 6) is formed at the tip in direction B, which is the direction of flow of the potting resin 200a.

[0032] Next, for example, an external force is applied to the right side wall 3 such that a tensile force acting in the front-rear direction and a tensile force acting in the left-right direction are applied, and the row of recesses 31 is pulled in the front-rear direction, concentrating stress in the row of recesses 31. As a result, the right side wall 3 breaks starting from the row of recesses 31, and the molding die 1 is split, so the electronic control device 100 can be removed from the molding die 1. At this time, the shape of the potting resin body 200 is molded to match the shape of the cavity 8 of the molding die 1.

[0033] In the electronic control unit 100 manufactured as described above, the first wall portion 42 controls the direction of burr generation, allowing burrs to form on the inner edge portion E1 on the connector 103 side of the potting resin body 200. Furthermore, by suppressing the formation of burrs that protrude outward from the potting resin body 200, the process of removing burrs from the electronic control unit 100 can be eliminated. Moreover, by controlling the direction of burr generation with the first wall portion 42, the burrs formed on the edge portion E1 are less likely to become thin and needle-shaped.

[0034] According to the molding die 1 of this embodiment, the mold has a cavity 8 for molding the electronic control device 100, a first wall portion 42 facing the cavity 8 and facing the bottom portion 2 of the cavity 8, and a second wall portion 41 facing the cavity 8 and connected to the bottom portion 2 side relative to the first wall portion 42. The second wall portion 41 is water-repellent, and the hydrophilic portion is more hydrophilic than the second wall portion 41, so that burrs can be prevented from forming on the outside of the electronic control device 100.

[0035] In this embodiment, a second wall portion 41 and a first wall portion 42 are provided, but the invention is not limited to this. The bottom portion 2, the right side wall portion 3, the left side wall portion 4, the inclined wall portion 5, the front wall portion 6, and the rear wall portion 7 may be formed from a water-repellent material, while the protruding portion 32 may be formed from a hydrophilic material.

[0036] Furthermore, in this embodiment, the protruding portion 32 is made to protrude into the cavity 8 from the upper ends of the right side wall portion 3, the left side wall portion 4, the front wall portion 6, and the rear wall portion 7. However, the invention is not limited to this, and depending on the vertical length of the electronic control device 100, the protruding portion 32 may be made to protrude into the cavity 8 from below the upper ends of the right side wall portion 3, the left side wall portion 4, the front wall portion 6, and the rear wall portion 7.

[0037] Furthermore, although the electronic control device 100 was molded using the molding mold 1 in this embodiment, the invention is not limited to this, and molded products other than the electronic control device 100 can be molded using the molding mold 1.

[0038] (Embodiment 2) <Configuration of the molding die> The configuration of the molding die 51 according to the second embodiment of the present invention will be described in detail with reference to Figure 7.

[0039] In Figure 7, parts that have the same configuration as those in Figure 4 are denoted by the same reference numerals, and their descriptions are omitted. Also, in the configuration of the molding die 51 according to this embodiment, parts that have the same configuration as those in the molding die 1 are denoted by the same reference numerals, and their illustration and description are omitted.

[0040] The molding die 51 is integrally formed from a flexible and breakable sheet-like material such as synthetic resin, and has a bottom portion 2, a right side wall portion 3, a left side wall portion 4, an inclined wall portion 5, a front wall portion 6, a rear wall portion 7, a cavity 8, an opening 9, a protrusion 10, a row of recesses 31, an overhang 33, a second wall portion 43, a first wall portion 44, and a curved wall portion 45.

[0041] The protruding portion 33 extends into the cavity 8 from the upper ends of the right side wall portion 3, the left side wall portion 4, the front wall portion 6, and the rear wall portion 7, and is inclined toward the inside of the cavity 8, away from the bottom portion 2. The protruding portion 33 is inclined toward each of the right side wall portion 3, the left side wall portion 4, the front wall portion 6, and the rear wall portion 7.

[0042] The second wall surface portion 43 covers the inner surfaces of a part of the curved wall portion 45, the bottom portion 2, the right side wall portion 3, the left side wall portion 4, the inclined wall portion 5, the front wall portion 6, and the rear wall portion 7 on the cavity 8 side and faces the cavity 8. The second wall surface portion 43 is formed to have water repellency by performing a water repellent treatment such as applying a water repellent coating agent to the inner surfaces of a part of the curved wall portion 45, the bottom portion 2, the right side wall portion 3, the left side wall portion 4, the inclined wall portion 5, the front wall portion 6, and the rear wall portion 7 on the cavity 8 side.

[0043] The first wall surface portion 44 covers the inner surfaces of a part of the curved wall portion 45 and the protruding portion 32 on the cavity 8 side and faces the cavity 8. The first wall surface portion 44 is inclined with respect to the second wall surface portion 43 and is inclined in a direction away from the bottom portion 2 toward the inside of the cavity 8. The first wall surface portion 44 has higher hydrophilicity than the second wall surface portion 43. The first wall surface portion 44 is formed by performing a hydrophilic treatment such as applying a hydrophilic coating agent to the inner surfaces of a part of the curved wall portion 45 and the protruding portion 32 on the cavity 8 side.

[0044] Since the first wall surface portion 44 covers the inner surface of a part of the curved wall portion 45 on the cavity 8 side and the second wall surface portion 43 covers the inner surface of a part of the curved wall portion 45 on the cavity 8 side, the end portion 44a of the first wall surface portion 44 on the second wall surface portion 43 side and the end portion 43a of the second wall surface portion 43 on the first wall surface portion 44 side are curved so as to protrude outward with respect to the cavity 8.

[0045] The curved wall portion 45 is formed at the boundary between the protruding portion 32 of the right side wall portion 3, the left side wall portion 4, the front wall portion 6, and the rear wall portion 7 and the portion below the protruding portion 32, and is curved so as to protrude outward with respect to the cavity 8. The surface of the curved wall portion 45 on the cavity 8 side is covered by the first wall surface portion 44 and the second wall surface portion 43.

[0046] The molding die 51 having the above configuration is a container-shaped member into which the potting resin material 200a is injected from the opening 9 into the cavity 8 and the potting resin material 200a can be accommodated inside the cavity 8, and is used when manufacturing the electronic control device 100.

[0047] <Method of manufacturing an electronic control device>A method of manufacturing an electronic control device 100 using a molding die 51 according to a second embodiment of the present invention will be described in detail with reference to FIGS. 7 and 8.

[0048] When supplying the molten potting resin material 200a into the cavity 8, the second wall surface portion 43 wets and spreads the potting resin material 200a as the potting resin material 200a is filled into the cavity 8, and raises the potting resin material 200a in the A direction in FIG. 7 due to the surface tension of the potting resin material 200a. Then, when the potting resin material 200a raised in the A direction reaches the first wall surface portion 44 along the second wall surface portion 43 curved by the curved wall portion 45, the first wall surface portion 44 having higher hydrophilicity than the second wall surface portion 43 pulls the potting resin material 200a in the B direction inside the cavity 8 in FIG. 7. The potting resin material 200a pulled in the B direction stays at the tip portion in the B direction of the first wall surface portion 44 due to the surface tension of the potting resin material 200a along the first wall surface portion 44 curved by the curved wall portion 45. As a result, an edge portion E2 is formed at the tip portion in the B direction, which is the advancing direction of the flow of the potting resin material 200a.

[0049] In addition, since the manufacturing method other than the above in the method of manufacturing the electronic control device 100 using the molding die 51 according to the present embodiment is the same as the method of manufacturing the electronic control device 100 using the molding die 1, the description thereof is omitted.

[0050] In the electronic control device 100 manufactured as described above, the first wall portion 44 controls the direction of burr generation, allowing burrs to be formed on the connector 103 side inside the potting resin body 200. Furthermore, by suppressing the formation of burrs protruding outward from the potting resin body 200, the process of removing burrs from the electronic control device 100 can be eliminated. In addition, by controlling the direction of burr generation with the first wall portion 44, the burrs formed on the edge portion E2 are less likely to become thin and needle-shaped. Moreover, by inclining the first wall portion 44 with respect to the second wall portion 43 and inclining it toward the inside of the cavity 8 away from the bottom portion 2, the edge portion on the outside of the upper end of the potting resin body 200 can be eliminated, thereby suppressing cracking or chipping of the edge portion of the potting resin body 200. Furthermore, by providing a curved wall portion 45 and curving the first wall portion 44 and the second wall portion 43 so that they protrude outward relative to the cavity 8, the opposing portion 201 facing the curved wall portion 45 can be curved via the first wall portion 44 and the second wall portion 43 of the potting resin body 200, thereby suppressing cracking or chipping of the opposing portion 201.

[0051] According to the molding die 51 of this embodiment, the first wall portion 44 is inclined with respect to the second wall portion 43 and is inclined toward the inside of the cavity 8 away from the bottom portion 2. In addition to the effects of the first embodiment described above, this eliminates sharp edges on the outside of the upper end of the potting resin body 200, thereby preventing the edges of the potting resin body 200 from cracking or chipping.

[0052] Furthermore, according to the molding die 51 of this embodiment, at least one of the end portion 44a of the first wall portion 44 on the second wall portion 43 side and the end portion 43a of the second wall portion 43 on the first wall portion 44 side is curved so as to protrude outward with respect to the cavity 8, thereby preventing the opposing portion 201 from cracking or chipping.

[0053] In this embodiment, a second wall portion 43 and a first wall portion 44 are provided, but the invention is not limited to this. The bottom portion 2, the right side wall portion 3, the left side wall portion 4, the inclined wall portion 5, the front wall portion 6, the rear wall portion 7, and a part of the curved wall portion 45 may be formed from a water-repellent material, while the protruding portion 33 and a part of the curved wall portion 45 may be formed from a hydrophilic material.

[0054] Furthermore, in this embodiment, the protruding portion 33 is projected into the cavity 8 from the upper ends of the right side wall portion 3, the left side wall portion 4, the front wall portion 6, and the rear wall portion 7. However, the invention is not limited to this configuration, and depending on the vertical length of the electronic control device 100, the protruding portion 33 may be projected into the cavity 8 from below the upper ends of the right side wall portion 3, the left side wall portion 4, the front wall portion 6, and the rear wall portion 7.

[0055] Furthermore, although a curved wall portion 45 is provided in this embodiment, the invention is not limited to this, and the first wall portion 44 may be configured to be inclined toward the inside of the cavity 8 toward the bottom portion 2 relative to the second wall portion 43 without providing a curved wall portion 45.

[0056] Furthermore, in this embodiment, the end 44a of the first wall portion 44 on the second wall portion 43 side and the end 43a of the second wall portion 43 on the first wall portion 44 side are curved so as to be convex outward with respect to the cavity 8. However, the embodiment is not limited to this configuration, and it is also possible to have a configuration in which only the end 44a of the first wall portion 44 on the second wall portion 43 side or only the end 43a of the second wall portion 43 on the first wall portion 44 side is curved so as to be convex outward with respect to the cavity 8.

[0057] Furthermore, although the electronic control device 100 was molded using the molding die 51 in this embodiment, the invention is not limited to this, and molded products other than the electronic control device 100 can be molded using the molding die 51.

[0058] The present invention is not limited to the above-described embodiments in terms of the type, shape, arrangement, number, etc. of the components, and it is of course possible to modify them as appropriate without departing from the spirit of the invention, such as by appropriately substituting the components with those that produce equivalent effects.

[0059] Specifically, in the first and second embodiments described above, the right side wall 3, left side wall 4, front wall 6, and rear wall 7 are each provided along the vertical direction. However, the invention is not limited to this, and at least one of the right side wall 3, left side wall 4, front wall 6, and rear wall 7 may be inclined at an angle with respect to the vertical direction.

[0060] As described above, the present invention can suppress the formation of burrs protruding from the outside of molded products, and due to its general-purpose and universal nature, it is expected to be widely applicable to molds for obtaining molded products such as electronic control devices and methods for manufacturing molded products.

[0061] 1...Molding mold 2...Bottom 3...Right side wall 4...Left side wall 5...Inclined wall 6...Front wall 7...Rear wall 8...Cavity 9...Opening 10...Convex part 31...Row of concave parts 32...Protruding part 33...Protruding part 41...Second wall part 42...First wall part 43...Second wall part 44...First wall part 45...Curved wall part 51...Molding mold 100...Electronic control unit 200...Potting resin body

Claims

1. A molding die used to obtain a molded product, comprising: a cavity for molding the molded product; a first wall portion facing the cavity and facing the bottom of the cavity; and a second wall portion facing the cavity and connected to the bottom side of the first wall portion, wherein the second wall portion is water-repellent, and the first wall portion is more hydrophilic than the second wall portion.

2. The molding die according to claim 1, characterized in that the first wall portion is inclined with respect to the second wall portion and is inclined toward the inside of the cavity toward away from the bottom portion.

3. The molding die according to claim 2, characterized in that at least one of the end of the first wall portion on the side of the second wall portion and the end of the second wall portion on the side of the first wall portion is curved so as to be convex outward with respect to the cavity.

4. A method for manufacturing a molded product obtained using a molding die, comprising: a first step of supplying a liquid material to a cavity facing a first wall portion facing the bottom of the cavity of the molding die and a second wall portion connected to the bottom side of the first wall portion, up to a position where it contacts the first wall portion; and a second step of curing the liquid material supplied to the cavity in the first step, wherein the second wall portion is water-repellent and the first wall portion is more hydrophilic than the second wall portion.

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