JP2014240178A - Apparatus and method for insert injection molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus and a method for insert injection molding which suppress positional changes of an insert material during molding while reducing trace holes due to holding pins.SOLUTION: Insert holding parts 41 and 51 capable of holding an insert material 90 are provided in a forming die 1, and urging forces of urging means 43 and 53 of urging the holding pins 42 and 52 toward the insert material 90 in the insert holding parts 41 and 51 are set so that, while the holding pins 42 and 52 do not move under the injection pressure of an injection molding machine, and the holding pins 42 and 52 move during dwell pressure application.

Description

  The present invention relates to an injection molding apparatus including a mold.

  The insert injection molding method is a method of obtaining a molded product by injecting a fluid resin material into a cavity in which different members (so-called insert materials) are previously arranged. In a molding apparatus for insert injection molding, a pin for holding an insert material in a cavity is generally provided on a molding die (see, for example, Patent Document 1). The holding pin is generally pressed toward the insert material by a biasing means such as a spring. By this pressing force, the position of the insert material is fixed in the cavity.

  By the way, in this type of injection molding apparatus, if the pressing force of the holding pin against the insert material is excessive, the holding pin remains in contact with the insert even when the cavity is filled with the resin material. For this reason, in the obtained molded product, the trace hole of a holding pin remains, and there exists a possibility that the designability of a molded product may be impaired.

  On the other hand, if the pressing force of the holding pin against the insert material is too small, the holding pin separates from the insert material due to the fluid pressure of the resin material in the middle of the resin material being injected and filled into the cavity. In this case, the position of the insert material changes due to the fluid pressure of the resin material, and it may be difficult to obtain a molded product in which the insert material is arranged at a desired position.

JP-A-8-267504

  The present invention has been made in view of the above circumstances, and provides an insert injection molding apparatus and an insert injection molding method capable of suppressing a change in position of an insert material during molding while reducing trace holes due to holding pins. For the purpose.

An insert injection molding apparatus of the present invention that solves the above-mentioned problems comprises a molding die for defining a cavity for injection molding, and an injection molding machine for injecting a fluid resin material into the cavity. An insert injection molding apparatus that performs injection molding with the insert material arranged in
The mold includes a general mold part that defines at least a part of the cavity, a holding pin that can be advanced and retracted into the cavity, and a biasing unit that biases the holding pin toward the cavity. An insert holding portion capable of holding the insert material within,
The holding pin is capable of changing a position between a forward position where the holding pin is in contact with the insert material and a backward position where the holding pin is retracted to the outside of the cavity.
The holding pin includes a pressure receiving surface that is exposed in the cavity at the advanced position and intersects the forward-retracting direction of the holding pin;
The biasing means biases the holding pin toward the advance position,
The urging force of the urging means is a device in which the holding pin does not move due to the injection pressure of the injection molding machine and the holding pin moves at the time of holding pressure.

  In order to make the urging force of the urging means have the above magnitude, the insert injection molding apparatus of the present invention preferably includes the following (1).

(1) The biasing force of the biasing means is
Less than a value obtained by multiplying the internal pressure of the cavity at the time of the pressure holding by the projected area of the pressure receiving surface of the holding pin in the receding direction, and
It is not less than a value obtained by multiplying the internal pressure of the cavity at the time of injection by the projected area of the pressure receiving surface of the holding pin in the receding direction.

The insert injection molding method of the present invention for solving the above problems is an injection molding method using the above-described insert injection molding device of the present invention,
An injection step of injecting a fluid resin material into the cavity of the mold, and a pressure holding step of making the internal pressure of the cavity exceed the internal pressure of the cavity in the injection step after the injection step. ,
In this method, the urging force of the urging means in the insert holding part is equal to or greater than the force acting on the pressure receiving surface in the injection step and less than the force acting on the pressure receiving surface in the pressure holding step.

  According to the insert injection molding apparatus of the present invention, when the resin material is injected, the holding pin holds the insert material by the urging force of the urging means, and at the time of holding pressure, at least a part of the holding pin is retracted outside the cavity to insert material. Get away from. For this reason, according to the insert injection molding apparatus of this invention, the trace hole of a holding pin is hard to be formed. That is, according to the insert injection molding apparatus of the present invention, trace holes can be reduced.

  Further, since the cavity is already filled with the resin material at the time of holding pressure, even if the holding pin is separated from the insert material at this stage, the position of the insert material does not change, or the position change amount of the insert material is small. That is, according to the insert injection molding apparatus of the present invention, it is possible to suppress a change in the position of the insert material during molding.

  According to the insert injection molding method of the present invention, the above-described insert molding device of the present invention can provide a molded product in which trace holes are reduced and the position change of the insert material is suppressed.

It is explanatory drawing which represents typically the insert injection molding apparatus of Example 1. FIG. It is sectional drawing which represents typically a mode that the shaping | molding die in the insert injection molding apparatus of Example 1 was cut | disconnected in the AA position in FIG. It is explanatory drawing which represents typically the insert injection molding apparatus of Example 1 in an injection process. It is explanatory drawing which represents typically the insert injection molding apparatus of Example 1 in a pressure-holding process. It is explanatory drawing which represents typically the relationship between the holding pin of a shaping | molding die in the insert injection molding apparatus of Example 1, and insert material. It is explanatory drawing which represents typically the relationship between the holding pin of a shaping | molding die in the insert injection molding apparatus of Example 2, and insert material. It is a perspective view which represents typically the holding pin of the shaping | molding die in the insert injection molding apparatus of Example 2. FIG. FIG. 8 is a side view schematically showing the holding pin shown in FIG. 7 as viewed from the position B in FIG. 7. It is explanatory drawing which represents typically the projection area in the retraction direction of the pressure receiving surface of a holding pin shown in FIG.

  Hereinafter, as necessary, the insert injection molding apparatus of the present invention is abbreviated as the molding apparatus of the present invention, and the insert injection molding method of the present invention is abbreviated as the molding method of the present invention.

  The molding die has a part (general mold part) for defining at least a part of the cavity and a part (insert holding part) for holding the insert material in the cavity. The general mold portion may be formed by partitioning the entire cavity. Alternatively, a part of the cavity may be partitioned by a part other than the general mold part. For example, a part of the cavity may be defined by a part of the holding pin.

  The insert holding part includes a holding pin and a biasing means. There may be at least one holding pin and one urging means. For example, the holding pins may be plural or only one. In order to hold the insert material at a desired position with high reliability, the number of holding pins is preferably 2 or more. Further, it is preferable to provide one urging means for each holding pin, but two or more holding pins may be urged by one urging means. The urging means is not particularly limited as long as it can urge the holding pin toward the insert material, and its drive mechanism, material and shape are not particularly limited, but is preferably made of a spring such as a coil spring or a leaf spring.

  The material and shape of the insert material are not particularly limited, but the molding apparatus and the molding method of the present invention can be particularly preferably applied, for example, when the insert material is completely embedded in the molded product. In such a case, generally, if the biasing force of the biasing means is set to be small so as to reduce the trace holes in the molded product, it becomes difficult to hold the insert material firmly. However, according to the molding apparatus and molding method of the present invention, trace holes can be reduced as described above.

  The holding pin can change its position between a position where it abuts against the insert material (advance position) and a position where the holding pin retracts outside the cavity (retreat position). In the advanced position, the holding pin may simply contact the insert material, but is preferably pressed against the insert material. This is to hold the insert material with high reliability. In the retracted position, the entire holding pin may be arranged outside the cavity, or a part of the holding pin may remain inside the cavity. Alternatively, a part of the cavity in the pressure holding process may be partitioned by a part of the holding pin.

  The forward-backward direction of the holding pin in the insert holding part may be a linear direction or a curved direction. Further, the holding pin may be advanced and retracted in the linear direction and the curved direction. That is, the holding pin may move linearly during forward movement and backward movement, may move in a curved line, or may move in a linear and curved line. Examples of the linear movement method include slide movement. Examples of the curvilinear moving method include sliding, swinging, and turning.

  The holding pin has a pressing portion and a pressure receiving surface. When the holding pin is disposed at the forward movement position, the pressing portion of the holding pin comes into contact with the insert material. The pressure receiving surface is a surface that is exposed in the cavity when the holding pin is disposed at the forward movement position. That is, the pressure receiving surface does not contact the insert material at the advanced position. The pressing part may be planar, linear or dot-shaped. The pressing part and the pressure receiving surface may be continuous or may be divided. Moreover, when a press part is planar, the press part and the pressure receiving surface may face the different direction, and may face the same direction.

  The molding method of the present invention includes an injection process and a pressure holding process. The injection process is a process of injecting a resin material into the cavity. The pressure holding process is a process of further increasing the cavity internal pressure after the injection process. By the pressure holding step, for example, even when the fluidity of the resin material is low, the resin material can be spread over the entire cavity. Alternatively, it is possible to fill the cavity with a resin material with high density. The cavity internal pressure in the pressure holding process exceeds the cavity internal pressure in the injection process. In other words, the pressure holding step only needs to pressurize and hold the resin material filled in the cavity with a pressure exceeding the injection pressure.

  The pressure receiving surface intersects with the forward-backward direction of the holding pin. In other words, the pressure receiving surface is not parallel to the forward-backward direction of the holding pin. For this reason, the pressure receiving surface is exposed to the resin material inside the cavity and receives the fluid pressure of the resin material. Then, the holding pin moves forward or backward depending on the magnitude of the fluid pressure (that is, the cavity internal pressure) received by the pressure receiving surface. Therefore, the movement of the holding pin is related to the size of the pressure receiving surface that can receive the cavity internal pressure. Specifically, it is the projected area of the pressure receiving surface in the backward direction of the holding pin. It should be noted that the pressure receiving surface itself moves backward as the holding pin moves backward. Therefore, the projected area can be rephrased as the projected area of the pressure receiving surface in the receding direction of the pressure receiving surface itself.

  It is preferable that the pressing portion has a planar shape and is flush with a mold surface (referred to as a general mold surface) of the general mold portion adjacent to the holding pin at the retracted position. For example, when the entire holding pin is disposed outside the cavity at the retracted position, the pressing portion is disposed outside the cavity from the general mold surface. In this case, a convex shape (so-called sagging shape) is generated on the surface of the molded product by a level difference between the pressing portion and the general mold surface. In some cases, it is necessary to cut and remove the convex portion, which increases the man-hour required for molding and increases the molding cost. On the other hand, if the pressing portion has a planar shape, a part of the cavity is defined at the retracted position, and the pressing portion and the general mold surface are flush with each other at the retracted position, the occurrence of the convex shape can be suppressed. When the pressing portion and the pressure receiving surface are smoothly continuous, it is preferable that both the pressing portion and the pressure receiving surface are flush with the general mold surface.

  Hereinafter, the insert injection molding apparatus and the insert injection molding method of the present invention will be described with specific examples.

Example 1
An explanatory view schematically showing the molding apparatus of Example 1 is shown in FIG. FIG. 2 is a cross-sectional view schematically showing a state where the molding die in the molding apparatus of Example 1 is cut at the position AA in FIG. An explanatory view schematically showing the molding apparatus of Example 1 in the injection step is shown in FIG. FIG. 4 is an explanatory view schematically showing a molding die of the molding apparatus of Example 1 in the pressure holding step. FIG. 5 is an explanatory view schematically showing the relationship between the holding pins of the mold and the insert material in the molding apparatus of Example 1.

  As shown in FIG. 1, a molding apparatus 100 according to an embodiment includes a molding die 1 and an injection molding machine 2. The injection molding machine 2 includes a molding machine body 20, a feeder 25, a motor 26, and control means 27.

  As shown in FIG. 2, the molding die 1 is divided into a fixed die 11 and a movable die 15. The fixed mold 11 and the movable mold 15 have substantially the same shape. The fixed die 11 has a nested structure divided into an inner die 11a and an outer die 11b. Similarly, the movable die 15 has a nested structure divided into an inner die 15a and an outer die 15b.

  The outer mold 11b of the fixed mold 11 has a substantially box shape, and the inner mold 11a is accommodated in the outer mold 11b. The inner mold 11a includes a general mold part 40 and an insert holding part 41. The insert holding part 41 has a holding pin 42 and an urging means 43, and the holding pin 42 is movable relative to the general mold part 40 and the outer mold 11b. Specifically, the general mold part 40 is formed with a pin holding part 11c. The pin holding part 11 c has a concave shape corresponding to the outer shape of the insert holding part 41. More specifically, the pin holding portion 11 c has a through hole shape substantially complementary to a part of the pin body 44 and the outer shape of the spring seat portion 45 in the insert holding portion 41 described later. Similarly with respect to the movable die 15, the outer die 15b has a substantially box shape, and the inner die 15a is accommodated in the outer die 15b. The inner mold 15 a is composed of a general mold part 50 and an insert holding part 51. The general mold part 50 and the insert holding part 51 have substantially the same shape as the general mold part 40 and the insert holding part 41.

  A driving means (not shown) is attached to the movable die 15. For this reason, the movable mold 15 can advance and retreat with respect to the fixed mold 11. In the molding apparatus 100 of the first embodiment, the movable mold 15 can advance and retreat in a direction parallel to the mold split direction (opening / closing direction in FIG. 2). Since the fixed mold 11 is fixed, its position does not change, but the movable mold 15 changes its position, so that the movable mold 15 and the fixed mold 11 change in position (separate). The inner mold 11a constituting the fixed mold 11 is fixed to the outer mold 11b of the fixed mold 11, and the inner mold 15a constituting the movable mold 15 is also fixed to the outer mold 15b of the movable mold 15. . Therefore, the outer mold 15b and the inner mold 15a in the movable mold 15 advance and retreat integrally. Further, the holding pin 42 of the insert holding part 41 accommodated in the outer mold 11 b of the fixed mold 11 can change its position with respect to the outer mold 11 b and the general mold part 40. Similarly, the position of the holding pin 52 of the insert holding portion 51 accommodated in the outer die 15 b of the movable die 15 can be changed with respect to the outer die 15 b and the general die portion 50.

  The insert holding part 41 includes a holding pin 42 and a biasing means 43. The insert holding part 51 also includes a holding pin 52 and a biasing means 53. The urging means 43 and 53 are each composed of a coil spring. The holding pin 42 includes a pin body 44 and a spring seat 45. The holding pin 52 also includes a pin body 54 and a spring seat 55. The pin bodies 44 and 54 each have a substantially quadrangular prism shape. Each of the spring seats 45 and 55 has a substantially box shape that is slightly larger than the pin bodies 44 and 54, and is integrated with one end of the corresponding pin bodies 44 and 54 in the longitudinal direction. The spring seat portions 45 and 55 are provided with substantially cylindrical recesses. The recesses of the spring seats 45 and 55 open to the opposite side of the pin body 44 or 54. The urging means 43 or 53 is accommodated in the recesses of the spring seats 45 and 55. Therefore, the holding pin 42 has a two-stage substantially quadrangular prism shape as a whole. The same applies to the holding pin 52. For reference, the shape of the holding pins 42 and 52 is not limited to this, and may be, for example, a cylindrical shape. Furthermore, the holding pins 42 and 52 may have the same shape or different shapes. The insert holding portions 41 and 51 are respectively inserted into the pin holding portions 11c or 15c with the urging means 43 and 53 while the longitudinal direction of the holding pins 42 and 52 is directed in the forward / backward direction (opening / closing direction in FIG. 2). Yes. At this time, the urging means 43 is interposed between the holding pin 42 and the outer mold 11b. The urging means 53 is interposed between the holding pin 52 and the outer mold 15b.

  The other ends of the pin bodies 44 and 54 in the longitudinal direction (ends opposite to the spring seats 45 and 55) constitute curved surfaces 46 and 56 having curved surfaces. The curved surface 46 is flush with the inner surface of the general mold portion 40 (that is, the general mold surface 40a) when the pin body 44 of the holding pin 42 is disposed in the retracted position in the pressure holding process described later. Similarly, with respect to the holding pin 52, when the pin body 54 is disposed at the retracted position, the curved surface 56 is flush with the general mold surface 50a. Here, the insert material 90 in Example 1 is substantially cylindrical, and the shape of the injection-molded product to be insert-molded is also substantially cylindrical. The curvature of the curved surfaces 46 and 56 in the pin bodies 44 and 54 is different from the curvature of the surface (cross section) of the insert material 90. Therefore, the curved surfaces 46 and 56 and the surface shape of the insert member 90 do not coincide with each other, and both are in line contact or point contact. That is, in the molding apparatus 100 according to the first embodiment, the pressing portions of the holding pins 42 and 52 (that is, the portion that comes into contact with the insert member 90) remain in the form of dots or lines. The substantially entire surfaces of the curved surfaces 46 and 56 constitute a pressure receiving surface.

  The urging means 43 and 53 comprising coil springs compress and accumulate the urging force. The holding pins 42 and 52 are urged toward the inside of the mold 1 (that is, inside the cavity 10c) by the corresponding urging means 43 and 53, respectively. In the molding apparatus 100 according to the first embodiment, the insert holding portions 41 and 51 of the molding die 1 are arranged one by one at positions facing the fixed die 11 and the movable die 15 respectively.

  The mold 1 is attached to the molding machine body 20 of the injection molding machine 2. The molding machine body 20 includes a cylinder 21 and a plunger 22 and a heater (not shown) inside. The plunger 22 has a screw shape and is disposed inside the cylinder 21. An internal space 20 a is formed between the plunger 22 and the cylinder 21. A feeder 25 is disposed at the rear end of the cylinder 21. The resin material thrown into the feeder 25 is supplied to the internal space 20a in the cylinder 21 and heated by a heater (not shown) to melt or soften to become a fluid. A motor 26 is connected to the plunger 22. The plunger 22 advances and retreats while rotating with respect to the cylinder 21 by the driving force of the motor 26. When the plunger 22 moves forward, a fluid resin material is injected into the cavity 10 c of the mold 1. The magnitude (distance and speed) by which the plunger 22 advances and retreats is appropriately controlled by the control means 27.

  Hereinafter, the molding method of Example 1 will be described.

(Injection process)
As shown in FIG. 3, in the injection process, the movable mold 15 is advanced toward the fixed mold 11, and the insert material 90 is sandwiched and held by the two insert holding portions 41 and 51. The holding pins 42 and 52 of the insert holding portion 41 are urged to advance positions that abut against the insert material 90 (in pressure contact in the first embodiment) by the urging means 43 and 53, respectively. For this reason, after the insert material 90 is temporarily fixed (not shown) to the fixed mold 11, the movable mold 15 is advanced toward the fixed mold 11, and the mold 1 is clamped, so that the insert material 90 is naturally 2. It is sandwiched between the two insert holding portions 41 and 51. At this time, the cavity 10 c is partitioned and formed in the mold 1. Specifically, the inner surface of the general mold surface 50 in the movable mold 15, the inner surface of the general mold surface 40 in the fixed mold 11, and the pressure receiving surface of the holding pin 52 in the movable mold 15 (that is, the curved surface 56, hereinafter referred to as the pressure receiving surface 56). The cavity 10 c is partitioned by the side surface 57 of the holding pin 52 that continues to the pressure receiving surface 56, the pressure receiving surface 46 of the holding pin 42 in the fixed mold 11, and the side surface 47 of the holding pin 42 that continues to the pressure receiving surface 46.

  Then, the plunger 22 of the molding machine body 20 is advanced to inject the fluid resin material 80 into the cavity 10c. The urging force of the urging means 43 and 53 is such that the holding pins 42 and 52 are not moved by the injection pressure at this time. Specifically, the urging force of the urging means 43 and 53 is set to be larger than the force acting on the pressure receiving surfaces 46 and 56 of the holding pins 42 and 52 by the internal pressure of the cavity 10c in the injection process.

The force acting on the pressure receiving surface 46 of the holding pin 42 in the injection process can be calculated by (internal pressure of the cavity 10c during injection) × (projected area of the pressure receiving surface 46 in the backward direction of the holding pin 42). The same applies to the holding pin 52. The force acting on the holding pins 42 and 52 increases as the projected area of the pressure receiving surfaces 46 and 56 increases. In the molding apparatus 100 of the first embodiment, the advancing / retreating direction of the holding pins 42 and 52 is the same as the opening / closing direction of the fixed mold 11 and the movable mold 15. Therefore, in the molding apparatus 100 of the first embodiment, the projected areas of the pressure receiving surfaces 46 and 56 in the backward direction are the projected areas of the pressure receiving surfaces 46 and 56 viewed from the front side or the rear side in the opening / closing direction in FIG. By the way, in the molding apparatus 100 of Example 1, the holding pins 42 and 52 are in line contact or point contact with the surface of the insert member 90 as shown in FIG. Therefore, almost the entire curved surfaces 46, 56 of the holding pins 42, 52 constitute pressure receiving surfaces 46, 56 that receive injection pressure (that is, internal pressure acting on the cavity 10c). For this reason, in the molding apparatus 100 of Example 1, it can be said that the cross-sectional area orthogonal to the advancing and retracting directions of the holding pins 42 and 52 is the projected area of the pressure receiving surfaces 46 and 56 in the retracting direction. Here, the projected areas of the pressure receiving surfaces 46 and 56 in Example 1 were 35 mm ² , respectively, and when the urging forces of the urging means 43 and 53 were 5 N, the holding pins 42 and 52 were retreated. However, when the urging force was 50 N, the retracting of the holding pins 42 and 52 was not recognized. In this way, by appropriately selecting the urging force of the urging means 43 and 53, the backward movement of the holding pin 35 is prevented, and the resin material is placed inside the cavity 10c while the insert material 90 is held between the holding pins 42 and 52. Can be filled.
If the urging forces of the urging means 43 and 53 are equal to or greater than the force acting on the pressure receiving surfaces 46 and 56 described above, the holding pins 42 and 52 are unlikely to move backward. Further, when the urging force of the urging means 43 and 53 is set larger than the force acting on the pressure receiving surfaces 46 and 56 described above, the backward movement of the holding pins 42 and 52 at this time can be further suppressed.

(Pressure holding process)
In the pressure holding process, the plunger 22 is further advanced after the injection process. Then, the internal pressure of the cavity 10c is set to exceed the internal pressure of the cavity 10c during the injection process. The force acting on the pressure receiving surface 46 of the holding pin 42 in the pressure holding step can be calculated by (internal pressure of the cavity 10c during pressure holding) × (projected area of the pressure receiving surface 46 in the backward direction of the holding pin 42). The same applies to the pressure receiving surface 56 of the holding pin 52.

  Specifically, at this time, the internal pressure of the cavity 10c is 50 MPa. Therefore, as shown in FIG. 4, the holding pins 42 and 52 move toward the retracted positions by the internal pressure of the cavity 10 c acting on the pressure receiving surfaces 46 and 56 at this time, respectively. In the above-described injection process, the cavity 10c is substantially filled with the resin material 80. Therefore, in the pressure holding step, the insert material 90 is already surrounded by the resin material 80 and is held by the resin material 80. Therefore, even if the holding pressure due to the internal pressure of the cavity 10c acts in the pressure holding process, the position of the insert material 90 is unlikely to change. For this reason, in the pressure holding step, only the holding pins 42 and 52 move to the retracted position in a state where the insert material 90 is substantially fixed. Therefore, according to the molding apparatus 100 and the molding method of the first embodiment, it is possible to obtain an injection molded product in which the insert material 90 is embedded while the insert material 90 is disposed at a desired position.

  Further, in the pressure holding process, the holding pins 42 and 52 move toward the retracted position and are separated from the surface of the insert material 90, and accordingly, the resin material 80 is filled in the region where the holding pins 42 and 52 existed. Therefore, no trace holes of the holding pins 42 and 52 remain on the surface of the molded product.

  In the retracted position, the pressure receiving surfaces 46 and 56 (pressing surfaces) are arranged flush with the inner surfaces 40a and 50a of the general mold portions 40 and 50, respectively. For this reason, the surface of the obtained molded product is smooth and does not require a post-process such as a cutting process.

  In the first embodiment, each of the movable die 15 and the fixed die 11 is provided with one insert holding portion 41, 51, and each insert holding portion 41, 51 is advanced and retracted in substantially the same direction as the mold splitting direction. However, the number, arrangement, and advancing / retreating direction of the insert holding portions 41 and 51 are not limited to this. The number, arrangement, and advancing / retracting direction of the insert holding portions 41, 51 may be appropriately set according to the shape of the mold 1, the position of the gate, the resin flow direction, etc. so that the insert material 90 can be held at a desired position. good. Also, the number of urging means can be set as appropriate according to the specifications of the insert holding portions 41 and 51.

(Example 2)
FIG. 6 is an explanatory view schematically showing the relationship between the holding pins of the mold and the insert material in the molding apparatus of Example 2. FIG. 7 is a perspective view schematically showing a holding pin of a mold in the molding apparatus of Example 2, and FIG. 8 is a side view schematically showing the holding pin viewed from the direction of arrow B in FIG. Show. Furthermore, in the molding apparatus of Example 2, FIG. 9 is an explanatory view schematically showing a projected area in the backward direction of the pressure receiving surface of the holding pin.

  The molding apparatus of the second embodiment is substantially the same as the molding apparatus 100 of the first embodiment except for the shape of the holding pins 42 and 52 (more specifically, the pin bodies 44 and 54). The molding method of Example 2 is substantially the same as the molding method of Example 1.

  As shown in FIGS. 7 and 8, in the second embodiment, the pin body 44 of the holding pin 42 includes a planar pressing portion (that is, the pressing surface 46) and a plurality of pressure receiving surfaces (44a, 44b and 44c). Have. Since the same applies to the pin body 54 of the holding pin 52 (not shown), the description will focus on the holding pin 42 in the second embodiment.

  The pressing surface 46 has a long curved surface shape corresponding to the surface shape of the insert material 90. As shown in FIG. 9, the pressing surface 46 has its own longitudinal direction directed to the longitudinal direction of the insert material 90. By doing so, the insert material 90 can be stably held by the pressing surface 46. The pressure receiving surfaces 44a to 44c each have a planar shape. The pressure receiving surface 44 a is a tapered surface provided on the front side in the longitudinal direction of the pressing surface 46. The pressure receiving surface 44b is a flat surface provided on both front sides of the pressing surface 46 in the short direction. The pressure receiving surface 44 c is a flat surface disposed on the front side in the backward direction of the holding pin 42 with respect to the pressing surface 46. The pressure receiving surface 44c, the pressure receiving surfaces 44a and 44b, and the pressing surface 46 are arranged in steps. The pressure receiving surfaces 44c and 44b are substantially orthogonal to the backward direction. In the molding apparatus of Example 2, the projected area in the receding direction of the pressure receiving surface refers to the sum of the projected areas of the pressure receiving surfaces 44a, 44b, and 44c. As shown in FIG. 6, the pressing surface 46 comes into surface contact with the surface of the insert member 90 when the holding pin 42 is disposed at the advanced position.

  According to the molding apparatus of the second embodiment, the pressing surface 46 is in surface contact with the surface of the insert material 90, so that the insert material 90 can be held more reliably by the insert holding portion 41, and the insert material 90 can be placed in a more desired position. Can be placed.

  Further, since the pressure receiving surface 44a having a tapered surface and having a relatively large area is provided in the vicinity of the pressing surface 46, a relatively large force is applied between the insert member 90 and the pressing surface 46 when the holding pin 42 is retracted. Can act. That is, by providing such a pressure receiving surface 44a, even if the insert material 90 and the pressing surface 46 are in close contact with each other, the pressure receiving surface 44a can be used to open both of them, thereby improving the backward movement performance of the holding pin 42. Is possible.

  The pressing surface 46 has a curved surface corresponding to the surface of the insert material 90. That is, in the molding apparatus of Example 2, the curvature of the pressing surface 46 and the curvature of the general mold surface (not shown, 40 in FIG. 2) are different. For this reason, the pressing surface 46 is not completely flush with the general mold surface 40 in the retracted position. However, if the holding pin 42 is arranged so that the end portion of the pressing surface 46 is close to the general mold surface 40 in the retracted position, the pressing surface 46 is smoothly continuous with the general mold surface 40. Only a fine convex shape remains as a trace of the pressing surface 46. Further, since the pressure receiving surfaces 44a and 44b are located in the vicinity of the pressing surface 46, similarly, if the end portions of the pressure receiving surfaces 44a and 44b are close to the general mold surface 40 in the retracted position, molding is performed. The traces of the pressure receiving surfaces 44a and 44b remaining on the surface of the product remain small. The pressure receiving surface 44c is disposed on the front side in the backward direction from the pressing surface 46. However, by reducing the step between the pressing surface 46 and the pressure receiving surface 44c, the pressure receiving surface 44c has an effect on the appearance of the molded product. Can be reduced. Therefore, also in the molding apparatus of Example 2, the trace of the holding pin 42 does not significantly affect the design of the molded product.

  As shown in FIG. 9, in the second embodiment, the pressure receiving surfaces 44 a to 44 c do not overlap with the retracting direction of the holding pin 42, but depending on the case, a part of each pressure receiving surface may be the retracting direction of the holding pin 42. It may overlap. If the pressure receiving surface is exposed in the cavity at the forward movement position and intersects with the forward / backward direction of the holding pin, the force due to the internal pressure of the cavity also acts on the pressure receiving surface in this case. In this case, the projected area of the pressure receiving surface indicates the sum of the projected areas of the intersecting pressure receiving surfaces.

  In the second embodiment, the arrangement of the pressure receiving surfaces 44a and 44b with respect to the longitudinal direction of the pressing surface 46 is asymmetrical. However, the pressure receiving surfaces 44a and 44b may be arranged symmetrically. For example, the pressure receiving surface may uniformly surround the entire circumference of the pressing surface 46.

(Other)
The present invention is not limited to the embodiments described above and shown in the drawings, and can be implemented with appropriate modifications within the scope not departing from the gist.

DESCRIPTION OF SYMBOLS 100: Insert injection molding apparatus 1: Mold 40, 50: General mold part 10c: Cavity 2: Injection molding machine 41, 51: Insert holding part 42, 52: Holding pin 46, 56, 44a-44c: Pressure receiving surface 46: Press surface 43, 53: Biasing means 80: Resin material 90: Insert material

Claims (3)

An insert injection comprising: a molding die for defining a cavity for injection molding; and an injection molding machine for injecting a fluid resin material into the cavity, and performing injection molding in a state where an insert material is disposed in the cavity. A molding device,
The mold includes a general mold part that defines at least a part of the cavity, a holding pin that can be advanced and retracted into the cavity, and a biasing unit that biases the holding pin toward the cavity. An insert holding portion capable of holding the insert material within,
The holding pin is capable of changing a position between a forward position where the holding pin is in contact with the insert material and a backward position where the holding pin is retracted to the outside of the cavity.
The holding pin is provided with a pressure receiving surface that is exposed in the cavity at the advance position and intersects with the advance-retreat direction of the hold pin, and the urging means urges the hold pin toward the advance position. And
The urging force of the urging means is an insert injection molding apparatus in which the holding pin does not move due to the injection pressure of the injection molding machine and the holding pin moves at the time of holding pressure. The biasing force of the biasing means is
Less than a value obtained by multiplying the internal pressure of the cavity at the time of the pressure holding by the projected area of the pressure receiving surface of the holding pin in the receding direction, and
2. The insert injection molding apparatus according to claim 1, wherein the insert injection molding apparatus is equal to or greater than a value obtained by multiplying an internal pressure of the cavity at the time of injection by a projected area in the retreat direction of the pressure receiving surface of the holding pin. An injection step of injecting a fluid resin material into the cavity of the mold, and a pressure holding step of making the internal pressure of the cavity exceed the internal pressure of the cavity in the injection step after the injection step. ,
The urging force of the urging means in the insert holding part is equal to or greater than a force acting on the pressure receiving surface in the injection step and less than a force acting on the pressure receiving surface in the pressure holding step. Alternatively, an insert injection molding method using the insert injection molding apparatus according to claim 2.

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