Injection molding mold

Abstract

To provide an injection molding die capable of smoothly molding a molded product having an undercut part.SOLUTION: Provided is an injection molding die 100 for molding a bumper 1, which is a molded product having a movable die 10 and a fixed die 50 that are closely spaced from each other and an undercut part 4 having a recess 3. The injection molding die comprises a rotary core 20 that is rotatably provided in the movable die 10 and has an operating surface 48 and a molding surface 31 for molding the undercut part 4, and an operating part 60 that is provided in the fixed die 50 and has an engaging surface 63 that engages the operating surface 48 when the movable die 10 is separated and rotates the rotary core 20 to separate the molding surface 31 from the undercut part 3 of the bumper 1.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an injection mold. [Background technology]

[0002] Patent document 1 discloses that when injection molding a resin molded product having a concave or hole-shaped undercut on the molding surface, an injection molding die is used that includes a rotating top, a main body that contains the rotating top, and a spring member that is positioned between the main body and the rotating top and that rotates the rotating top.

[0003] In this injection mold, the rotating top has a first cutout portion on part of its outer circumferential surface where a protrusion corresponding to the shape of the undercut is formed, and the spring member is arranged to rotationally bias the rotating top in a direction in which the protrusion comes out of the undercut. According to this injection mold, the rotating top is always rotationally biased by the spring member in a direction in which the protrusion comes out of the undercut, so that the protrusion can be removed from the undercut simply by releasing the mold clamping and removing the upper mold. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2016-36988 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in a structure in which the rotating top is rotated solely by the rotational biasing force of a spring member, such as the above-mentioned injection molding die, there is a risk that the rotating top will malfunction when strong frictional forces are generated on the sliding surface on the outer periphery of the rotating top.

[0006] The present invention has been made in view of the above circumstances, and has an object to provide an injection molding die capable of smoothly molding a molded product having an undercut portion. [Means for solving the problem]

[0007] In order to achieve the above object, the injection molding die of the present invention comprises: An injection molding die for molding a molded product having an undercut portion provided with at least one of a recess and a protrusion, comprising: a pair of dies spaced apart from each other and adapted to be disposed close to each other; a rotary core rotatably provided in one of the dies and having an operating surface and a molding surface for molding the undercut portion; an operating portion provided in the other mold, the operating portion having an engagement surface that engages with the operating surface when the molds are separated from each other to rotate the rotary core and separate the molding surface from the undercut portion of the molded product; Equipped with.

[0008] With this injection mold, when the pair of molds are separated to demold the molded product, the operating surface of the rotating core of one mold engages with the engaging surface of the operating part of the other mold to rotate the rotating core and move the molding surface of the rotating core away from the undercut portion. Therefore, compared to a structure in which the rotating core is rotated by the rotational biasing force of a spring member to move the molding surface away from the undercut portion when the molded product is demolded, the rotating core can be rotated smoothly to smoothly mold a molded product having an undercut portion. Effect of the Invention

[0009] According to the injection mold of the present invention, it is possible to provide an injection mold that is capable of smoothly molding a molded product having an undercut portion. [Brief description of the drawings]

[0010] [Figure 1] 1A and 1B are diagrams showing a bumper molded by the injection molding die according to the present embodiment, in which (a) is a front view and (b) is a cross-sectional view taken along the line AA in (a). [Diagram 2] 1(b) is a perspective view showing an undercut portion as viewed from the rear side; FIG. [Diagram 3] 1 is a schematic cross-sectional view and an enlarged view of a main portion of a movable mold and a fixed mold that constitute an injection molding die according to the present embodiment. FIG. [Figure 4] FIG. 2 is a diagram showing the movement of a rotating core and an operating part when molding a bumper, (a) to (d) being enlarged views of main parts of a die for injection molding. [Diagram 5] FIG. 2 is a diagram showing a process for forming a bumper, where (a) to (c) are schematic cross-sectional views of a movable mold and a fixed mold, respectively. [Figure 6] 1 is a schematic cross-sectional view of a movable die and a fixed die of an injection molding die according to Reference Example 1. FIG. [Figure 7] FIG. 11 is a schematic cross-sectional view of a movable die and a fixed die of an injection molding die according to Reference Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 shows a bumper molded by the injection molding die according to the present embodiment, where (a) is a front view and (b) is a cross-sectional view taken along line AA in (a). Fig. 2 shows a fixing portion of the bumper, where (a) is an enlarged view of portion B in Fig. 1(b) and (b) is a perspective view of the undercut portion as viewed from the rear side.

[0012] 1(a) and 1(b), the injection molding die according to this embodiment is, for example, a die for molding a vehicle bumper 1. The bumper 1 is molded from resin by injection molding.

[0013] 2(a) and 2(b), the bumper 1 has an undercut portion 4 with a recess 3 at a fixing portion 2 to the vehicle body. For example, when the bumper 1 is attached to the vehicle body, a locking claw (not shown) provided on the vehicle body is locked into the recess 3 at the undercut portion 4.

[0014] Next, an injection molding die according to this embodiment used for molding the above-mentioned bumper 1 will be described. FIG. 3 is a schematic cross-sectional view and an enlarged view of a main portion of a movable mold and a fixed mold that constitute the injection molding die according to this embodiment.

[0015] As shown in Fig. 3, the injection molding die 100 includes a movable die 10 and a fixed die 50, and is incorporated into an injection molding machine (not shown). The movable die 10 is attached to a movable platen 11 of the injection molding machine, and the fixed die 50 is attached to a fixed platen 51 of the injection molding machine. The movable die 10 is moved toward and away from the fixed die 50 by a clamping unit (not shown) of the injection molding machine. The movable die 10 and the fixed die 50 have molding surfaces 12, 52 formed on the surfaces facing each other.

[0016] In the injection molding machine, with the movable die 10 approaching the fixed die 50 and clamped, molten resin is injected into an injection space formed by the molding surfaces 12, 52 of the movable die 10 and the fixed die 50. After the resin hardens, the movable die 10 is separated from the fixed die 50 to open the die, and the bumper 1, which is a resin molded product, is removed.

[0017] The movable die 10 includes a rotating core 20. The rotating core 20 is accommodated in an accommodating recess 40 formed in the movable die 10, and is supported rotatably about a rotating shaft 21.

[0018] The rotating core 20 has sliding surfaces 22, 23 formed in an arc shape. These sliding surfaces 22, 23 slide against sliding concave surfaces 42, 43 formed in the accommodating recess 40 as the rotating core 20 rotates about the rotation shaft 21.

[0019] The rotating core 20 also has pressure-receiving surfaces 24, 25. When the rotating core 20 rotates in one rotation direction RA, these pressure-receiving surfaces 24, 25 come into contact with rotation restriction surfaces 44, 45 formed in the accommodating recess 40, and restrict the rotation of the rotating core 20 in the one rotation direction RA.

[0020] Furthermore, the rotating core 20 has pressure receiving surfaces 26, 27. When the rotating core 20 rotates in the other rotation direction RB, these pressure receiving surfaces 26, 27 come into contact with rotation restricting surfaces 46, 47 formed in the accommodating recess 40, and restrict the rotation of the rotating core 20 in the other rotation direction RB.

[0021] The rotating core 20 has a molding surface 31 formed on the pressure-receiving surface 24. This molding surface 31 is a molding surface that molds the undercut portion 4, and has a protrusion 32 formed at a position corresponding to the recess 3. In addition, a part of the outer circumferential side of the pressure-receiving surface 26 of the rotating core 20 is made to be a contact surface 33.

[0022] Furthermore, the rotating core 20 has an operating surface 48. This operating surface 48 is parallel to the moving direction of the movable die 10 when the pressure receiving surfaces 26, 27 of the rotating core 20 abut against the rotation restricting surfaces 46, 47 of the accommodating recess 40 and the rotation of the rotating core 20 in the other rotation direction RB is restricted. Moreover, the operating surface 45 is inclined in a direction away from the rotation axis 21 toward the fixed die 50 with respect to the moving direction of the movable die 10 when the pressure receiving surfaces 24, 25 of the rotating core 20 abut against the rotation restricting surfaces 44, 45 of the accommodating recess 40 and the rotation of the rotating core 20 in one rotation direction RA is restricted.

[0023] The fixed die 50 is provided with an operating part 60. The operating part 60 is formed in a block shape, and is attached by being fitted into a fixed recess 70 formed in the fixed die 50. A part of the operating part 60 protrudes toward the movable die 10. The operating part 60 has a pressing surface 61. A protruding piece 62 is formed at the tip of the operating part 60, and an engaging surface 63 is formed on the protruding piece 62. The engaging surface 63 is gradually inclined toward the pressing surface 61 side in the protruding direction of the protruding piece 62.

[0024] Next, the molding of the molded product, that is, the bumper 1, using the above-mentioned injection molding die 100 will be described. Fig. 4 is a diagram showing the movement of the rotating core and the operating part when molding a bumper, (a) to (d) are enlarged views of the main part of the injection mold, and Fig. 5 is a diagram showing the process of molding a bumper, (a) to (c) are schematic cross-sectional views of the movable mold and the fixed mold, respectively.

[0025] The mold clamping unit moves the movable mold 10 in a direction approaching the fixed mold 50. Then, as shown in Fig. 4(a), the pressing surface 61 formed on the operating part 60 of the fixed mold 50 comes into contact with the contact surface 33 formed on the rotating core 20 of the movable mold 10.

[0026] When the movable die 10 is brought even closer to the fixed die 50 and the movable die 10 and the fixed die 50 are clamped together, the contact surface 33 of the rotating core 20 is pressed by the pressing surface 61 of the operating portion 60, and as shown in Fig. 4(b) , the rotating core 20 is rotated in one rotation direction RA, and the pressure-receiving surfaces 24, 25 of the rotating core 20 are brought into contact with the rotation restricting surfaces 44, 45 of the accommodation recess 40. As a result, the rotation of the rotating core 20 is restricted, and an injection space Su for molding the undercut portion 4 is formed between the molding surface 31 formed on the pressure-receiving surface 24 and the rotation restricting surface 44.

[0027] 5(a), the injection space formed by clamping the movable die 10 and the fixed die 50 is filled with resin and cured to form the bumper 1. At this time, as shown in FIG. 4(c), the injection space Su between the molding surface 31 of the pressure-receiving surface 24 and the rotation restriction surface 44 is also filled with resin, and the undercut portion 4 of the bumper 1 is formed.

[0028] After the resin has hardened, the mold clamping unit moves the movable mold 10 in a direction away from the fixed mold 50. Then, as shown in Fig. 4(d), the engagement surface 63 formed on the operating portion 60 of the fixed mold 50 moves while engaging with the operating surface 48 formed on the rotating core 20 of the movable mold 10. As a result, the rotating core 20 rotates in the other rotation direction RB, and the molding surface 31 formed on the pressure-receiving surface 24 moves away from the molded undercut portion 4. In addition, the pressure-receiving surfaces 26, 27 of the rotating core 20 come into contact with the rotation-restricting surfaces 46, 47 of the installation recess 40, restricting the rotation, and the rotating core 20 is returned to the initial position.

[0029] Then, when the movable mold 10 is separated from the fixed mold 50 in the mold open state as shown in FIG. 5(b), the molded bumper 1 is pushed out by an ejection pin (not shown) provided on the movable platen 11 and removed from the mold as shown in FIG. 5(c).

[0030] Here, a reference example will be described. Fig. 6 is a schematic cross-sectional view of a movable die and a fixed die of an injection molding die according to Reference Example 1. Fig. 7 is a schematic cross-sectional view of a movable die and a fixed die of an injection molding die according to Reference Example 2.

[0031] 6, the injection molding die 100A according to Reference Example 1 has an inclined core 82 having a molding surface 81 for molding the undercut portion 4, a rod 83 connected to the inclined core 82, and a pusher plate 84 for pushing the rod 83 in to push the inclined core 82 out of the movable die 10. In this injection molding die 100A, when the die is opened, the pusher plate 84 pushes the rod 83 in to push the inclined core 82 out of the movable die 10 together with the bumper 1. As a result, the bumper 1 having the undercut portion 4 is demolded.

[0032] 7, the injection molding die 100B according to Reference Example 2 has a slide pin 92 having a molding surface 91 that molds the undercut portion 4, and a cylinder 93 that moves the slide pin 92 forward and backward. In this injection molding die 100B, when the bumper 1 is to be demolded, the slide pin 92 is retracted by the cylinder 93. As a result, the bumper 1 having the undercut portion 4 is demolded.

[0033] These injection molding dies 100A, 100B require a power source for moving the tilt core 82 and a cylinder 93 for moving the slide pin 92 forward and backward, in addition to a power source for opening and closing the movable die 10 and the fixed die 50. The operation time of the tilt core 82 and the slide pin 92 by these drive sources and cylinders 93 increases the cycle time of injection molding, lowering productivity. In addition, the provision of a mechanism for moving the tilt core 82 and a mechanism for moving the slide pin 92 forward and backward increases the number of parts, leading to increased costs, and furthermore, the provision of these mechanisms occupies space in the movable die 10, restricting the shape of the molded product.

[0034] In contrast, with the injection molding die 100 of this embodiment, when the movable die 10 is separated from the fixed die 50 to demold the molded product, that is, the bumper 1, the engagement surface 63 of the operating portion 60 of the fixed die 50 engages with the operating surface 48 of the rotating core 20 of the movable die 10, causing the rotating core 20 to rotate, and the molding surface 31 of the rotating core 20 to be separated from the undercut portion 4.

[0035] This eliminates the need for a separate power source for moving the inclined core 82 and the slide pin 92, and prevents an increase in costs due to an increase in the number of parts. In addition, because a mechanism for driving the inclined core 82 and the slide pin 92 is not required, the amount of space taken up in the mold can be reduced, and restrictions on the shape of the molded product can be reduced.

[0036] Furthermore, compared to a structure in which the rotating top is rotated by the rotational force of a spring member during demolding to move the molding surface away from the undercut portion, the rotating top can be rotated smoothly, allowing for smooth molding of a molded product having an undercut portion 4.

[0037] The undercut portion 4 formed by injection molding may have not only a recess but also a protrusion, or may have both a recess and a protrusion. When a protrusion is molded in the undercut portion 4, a recess is provided on the molding surface 31 of the rotating core 20, and when a recess and a protrusion are provided in the undercut portion 4, a protrusion and a recess are provided on the molding surface 31 of the rotating core 20.

[0038] In the above embodiment, the rotary core 20 is provided in the movable die 10 and the operating portion 60 is provided in the fixed die 50, but the rotary core 20 may be provided in the fixed die 50 and the operating portion 60 may be provided in the movable die 10.

[0039] In addition, in the above embodiment, the case of molding the bumper 1 has been illustrated, but the present invention is not limited to the bumper 1 and can be applied to the production of various resin molded products having undercut portions, such as dashboards. [Explanation of symbols]

[0040] 1 Bumper (molded product) 3. Recess 4 Undercut section 10 Movable mold (mold) 20 Rotating Core 31 Molding surface 48 Working Surface 50 Fixed mold (mold) 60 Operating Part 63 Engagement surface 100 Injection mold

Claims

[Claim 1] An injection molding die for molding a molded product having an undercut portion provided with at least one of a recess and a protrusion, comprising: a pair of dies spaced apart from each other and adapted to be disposed close to each other; a rotary core rotatably provided in one of the dies and having an operating surface and a molding surface for molding the undercut portion; a block-shaped operating part that is fitted into a fixed recess formed in the other mold, the operating part having an engagement surface that engages with the operating surface when the molds are separated from each other to rotate the rotary core and separate the molding surface from the undercut portion of the molded product; Equipped with Mold for injection molding.

Images