JP2012148455A - Injection molding device and injection molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate strength poverty of a weld line part, jetting and floating of glass fibers when injection-molding resin.SOLUTION: In a cavity C formed between a stationary mold 16 and a movable mold 32, the resin 34 is injected from two gates 22A, 22B. When injecting the resin 34, by forward and backward movement of a slide core 38 in the inside of a molding hole 36 forming the cavity C, the cavity C is kept at a constant volume until after elapse of a fixed time from start of the injection. After the fixed time elapses and the resin 34 in the cavity C merges and closely contacts with each other, the slide core 38 is gradually moved backward until completion of the injection to gradually expand the volume of the cavity C. The forward and backward movement of the slide core 38 is performed by a slide core forward and backward movement mechanism 80. With this, a weld line in a product 120 is prevented from being generated and strength poverty is eliminated. Further, jetting and floating of glass fibers when using material containing glass fibers are eliminated.

Description

  The present invention relates to an injection molding apparatus and an injection molding method using a mold for molding a resin product, and more specifically to control of a cavity volume at the time of resin injection into a mold.

  Currently, many resin products are manufactured by injection molding. In general injection molding, resin melted by an injection apparatus is injected and filled at high pressure in a closed mold, and after cooling and solidifying in the mold, a product is taken out. FIG. 11 (A) shows an example of the structure of a conventional general injection molding apparatus, FIG. 11 (B) shows the state at the time of product release, and FIG. 11 (C) shows. Is an external perspective view of the product. As shown in FIGS. 11A and 11B, the injection molding apparatus 300 has a structure in which a mold can be divided into a fixed mold 304 and a movable mold 316, and the fixed mold 304 has a fixed side mounting plate 302. The movable mold 316 is supported on the movable side mounting plate 312 via the leg portion 314. The fixed-side mounting plate 302 is provided with a sprue bush 306 serving as a passage for resin 330 injected from a nozzle of an injection device (not shown). The runner 308 connected to the sprue bush 306 is connected to the fixed die 304. And gates 310A and 310B are provided.

  The movable mold 316 is formed with a cavity C through which molten resin 330 is injected through the gates 310A and 310B. A space 318 is formed by the leg portion 314 between the movable mold 316 and the movable side mounting plate 312, and the space 318 can be moved back and forth between the movable mold 316 and the movable side mounting plate 312. A slide base 322 is disposed. The slide base 322 is urged toward the movable mounting plate 312 by a spring 320 provided between one main surface 322A and the movable mold 316. Furthermore, one end of projecting pins 326A and 326B that penetrate the movable mold 316 and reach the cavity C is fixed to the main surface 322A. As shown in FIG. 11B, the slide base 322 pushes the main surface 322B side by the tip 328A of the protruding rod 328 that penetrates the through hole 312A provided in the movable side mounting plate 312 in the mold open state. Then, the product 340 is extruded and released. In the injection molding apparatus 300, as shown in FIG. 11A, after the fixed mold 304 and the movable mold 316 are closed, the molten resin 330 is injected, cooled, and solidified. Release product 340 and runner as shown in B).

  FIGS. 12A-1 to 12A-4 schematically show the filling state of the resin 330 in the cavity C by the injection molding apparatus 300. FIG. As shown in FIG. 12 (A-1), the resin 330 enters from the two-point gate, and as shown in FIGS. 12 (A-2) and (A-3), the resin 330 gradually approaches the center and the tip portion Bonding is started from 332, and finally the entire resin 330 is fused as shown in FIG. At this time, in the cavity C, when the resin 330 advances to the center of the cavity C, the surface of the resin 330 is exposed to air to form a thin solidified layer, which is bonded, and FIG. ) And FIG. 11C, a weld line 342 having a substantially V-shaped groove appears on the surface of the product 340.

  The weld line is one of the disadvantages of injection molded products, and appears when a gate uses two or more molds as in the injection molding apparatus 300, but even if there is only one gate, Appears if the product has holes or bosses. For example, as shown in FIG. 13 (C), when forming a product 360 having a boss portion 362, FIGS. 13 (A-1) to (A-3) and FIGS. As shown in B-3), the cavity C has a shape including a forming hole 352 for forming the boss portion 362, and the resin 330 is formed in a state where the boss hole forming core 354 is disposed in the forming hole 352. Fill. In such a shape of the cavity C, the resin 330 is formed as shown by an arrow F13 in FIGS. 13 (A-1) to (A-3) and FIGS. 13 (B-1) to (B-3). After being filled and split into two at the annular portion of the molding hole 352, the weld line 364 appears at the boss portion 362 of the product 360 to join from the tip portion 332.

  In addition to the bosses described above, the weld line also appears in product holes. However, these holes and bosses are used for product installation and the like. There is an inconvenience that the strength is insufficient. In particular, when glass-filled materials are used, the glass fiber is aligned in one direction at the part where the resin that flows from the left and right is fused, so the strength of the weld line of glass-reinforced plastic is halved. Resulting in. Furthermore, since a layer made only of glass fibers is formed at the tip portion of the flowing resin, the resin is not actually fused at the portion where the materials merge, which may cause a further lack of strength. There is.

  In order to eliminate the insufficient strength of the weld line part, conventionally, a process such as embedding a metal screw in a boss part or a hole part is performed. In the case of multi-point gates, the weld line is located in the center of the product and is prone to fatal defects. Therefore, in order to avoid this, the gate arrangement must be considered, the quantity should be limited, or the thickness should be formed. To improve the strength.

  In addition to the occurrence of the above-described weld line, the resin product manufactured by the conventional general injection molding described above has a disadvantage that shrinkage and voids are generated at the stage of cooling and solidification. As means for preventing the occurrence of sink marks and voids, there is a molding method using the injection molding apparatus proposed by the present applicant in Japanese Patent Application No. 2009-110173. This molding method is referred to herein as an IMP (in-mold pressing) method and will be described below. Japanese Patent Application No. 2009-

  In addition to the occurrence of the weld line described above, the resin product manufactured by the conventional injection molding described above also has a disadvantage that shrinkage and voids are generated at the stage of cooling and solidification. In order to prevent the occurrence of sink marks and voids, there is a molding method using an injection molding apparatus proposed by the present applicant in Japanese Patent Application No. 2009-110173 (Patent Document 1). This molding method is referred to herein as an IMP (in-mold pressing) method and will be described below. The injection molding apparatus of the Japanese Patent Application No. 2009-110173 was developed to improve inconveniences (such as resin leakage and insufficient filling) of conventional injection compression molding in which resin is injected with the parting of the mold open. FIG. 14 shows the outline of the apparatus configuration and the IMP method. The mold part of the injection molding apparatus 400 shown in FIG. 14A includes a fixed mold 404 fixed to the fixed side mounting plate 402, a movable mold 412 supported by the movable side mounting plate 410, and the movable mold 412. A slide core 420 slidable in the formed molding hole 418 and provided with a pressure sensor 424, a leg 414 fixed to the movable side mounting plate 410, and the leg 414 and the movable mold 412. It is constituted by a spacer 416 or the like disposed between them. The movable side mounting plate 410 can be stroked toward the fixed side mounting plate 402 by a clamping mechanism (not shown) such as a direct pressure type or a toggle type.

  As shown in FIG. 14B, in the IMP method, the resin 430 is injected with the fixed mold 404 and the movable mold 412 closed at high pressure, and then the spacer 416 is moved in the stroke direction of the movable mold 412 by a drive mechanism (not shown). Pull out in a direction perpendicular to Then, the slide core 420 is slid in the molding hole 418 through the movable side mounting plate 410 and the slide base 422 by the space generated by the drawing, and the volume of the cavity C is compressed (re-clamping). In addition, it is configured to suppress the occurrence of sink marks and voids.

Japanese Patent Application No. 2009-110173

  However, the background art as described above has the following disadvantages. First, in the molding using the general injection molding apparatus 300 described above, metal screws are embedded in the hole or boss of the product or the gate position is changed in order to eliminate the insufficient strength of the weld line. There is a disadvantage that the molding process and the gate structure become complicated. In addition to the generation of weld lines, jetting occurs as shown in FIGS. 12 (B-1) to (B-4) depending on the resin material, mold structure, product shape, molding conditions, and the like. In many cases, canceling jetting can be dealt with by changing the gate position, and if the gate position is also limited, it can be dealt with under molding conditions. There is an inconvenience.

On the other hand, in the IMP method using the injection molding apparatus 400 shown in FIG. 14, since the parting can be injected at a high pressure using a mold clamping mechanism, the product shape that can be molded and compressed has a degree of freedom and is thick. Although there are advantages such as being able to process products and products with uneven thickness parts with high precision and voice dress,
(1) Since it is necessary to place spacers on the side of the mold, the mold structure becomes complicated, leading to a decrease in durability and an increase in cost.
(2) The mold clamping pressure needs to be reduced or zero to pull out the spacer, and the parting cannot always be clamped at a high pressure and parting burr may occur.
(3) Because the slide core is moved using the clamping pressure, it is difficult to perform the movement and control dedicated to the slide core.
(4) There is an inconvenience that the lack of strength in the weld line and the elimination of jetting are not considered.

  The present invention pays attention to the above points, and when injecting resin into a mold and molding, the lack of strength of the weld line part and jetting are eliminated, and a material containing glass fiber is used. Even so, an object of the present invention is to provide an injection molding apparatus and an injection molding method capable of eliminating glass fiber floating. Another object of the present invention is to provide an injection molding apparatus and an injection molding method capable of eliminating the void generation as well as the lack of strength of the weld line portion, jetting and glass fiber floating.

  The injection molding apparatus of the present invention forms a cavity into which molten resin is injected and filled when the movable mold supported by the movable mounting plate and the end face of the fixed mold supported by the stationary mounting plate are brought into contact with each other. A mold to be molded, an injection mechanism for injecting and filling molten resin into the cavity, and opening and closing the mold by causing the movable side mounting plate to stroke with respect to the fixed side mounting plate, and injection of the molten resin by the injection mechanism At the time of filling, a mold clamping mechanism for clamping the parting of the mold with a high-pressure mold, and an extension formed in the stroke direction on the movable mold, opening at an end surface facing the fixed mold, and applying the fixed mold to the end surface One or more molding holes forming at least a part of the cavity when contacted, a slide core partly accommodated in the molding hole and capable of moving forward and backward along the molding hole, and the gold Closed mold In this state, the slide core is driven so as to be able to advance and retreat along the molding hole, and a slide core advance / retreat mechanism that changes the volume of the molding hole, and the slide core according to the injection state of the molten resin into the cavity A control means for driving the advance / retreat mechanism, and a release means for extruding the product after injection molding from the cavity, and the control means has passed a predetermined time from the start of injection of the molten resin into the cavity. Until the injection hole is maintained until the injection hole is completed after a predetermined time elapses, and the slide core advance / retreat mechanism is controlled so that the volume of the formation hole gradually expands. Features.

  One of the main forms is that the molten resin injected into the cavity is merged at one or more locations in the cavity, and the control means is configured so that the volume of the molding hole is increased after the merged molten resin is in close contact. The slide core advancing / retreating mechanism is driven in a direction in which the slide core is expanded. In another embodiment, the cavity has a shape corresponding to a product having a boss or a recess, or the molten resin is injected into the cavity from the injection mechanism through a plurality of gate ports. The injection molding apparatus according to claim 1 or 2.

  In still another embodiment, the slide core advance / retreat mechanism is formed between the movable side mounting plate and the movable mold, and a leg portion that forms a space for the slide core to advance and retreat, and the leg portion. The slide base disposed in the space, one of the main surfaces is attached to the rear end of the slide core, and the movable side mounting plate penetrates in the advancing and retracting direction, and one end is the other main surface of the slide base One or more moving pins that can contact the moving pin, and a moving pin driving means that is disposed on the other end side of the moving pin and drives the moving pin in the forward / backward direction.

  In still another embodiment, the releasing means includes a protruding rod that pushes the slide core forward through the slide base, and a protruding rod driving means that drives the protruding rod in the forward / backward direction. Features. In still another embodiment, the control means stops the expansion of the volume of the molding hole and then advances the slide core to compress the volume of the molding hole.

  An injection molding method of the present invention is an injection molding method in which molten resin is injected and filled into a cavity formed on a dividing surface of a movable mold and a fixed mold, and is cooled and solidified, and a molding hole for forming at least a part of the cavity In addition, a part of the slide core is provided so as to be able to advance and retreat in the stroke direction of the movable mold, and the slide core is advanced in a mold clamping state, and the molding hole is reduced to a predetermined volume and maintained. A step of starting injection of molten resin into the cavity and a predetermined time after the injection of molten resin starts, the slide core is gradually retracted to continuously expand the volume of the molding hole. A step of stopping volume expansion of the molding hole, a step of starting cooling of the molten resin injected and filled in the cavity, and a step of opening the mold after releasing the cooled and solidified product , Characterized in that it comprises a.

  One of the main forms is that the molten resin injected into the cavity merges at one or more locations in the cavity and expands the volume of the molding hole. It starts after it adheres. In another embodiment, after the cooling start step, the slide core is advanced to compress the volume of the forming hole, and after the compression step, the cooled and solidified product is opened and separated. It is characterized by molding. The above and other objects, features and advantages of the present invention will become apparent from the following detailed description and the accompanying drawings.

  According to the present invention, when the resin injected into the cavity formed between the fixed mold and the movable mold is molded, the slide core is slidable in the molding hole that forms at least a part of the cavity. The molding hole is maintained at a predetermined constant volume until a predetermined time elapses from the start of injection, and the slide core is gradually retracted until the injection is completed after the certain time elapses to reduce the volume of the molding hole. Since the expansion is performed continuously, insufficient weld strength and jetting at the weld line portion can be eliminated, and even when a material containing glass fiber is used, there is an effect that glass fiber floating can be prevented. Moreover, the property which glass fiber orientates radially from a gate port is eased, the intensity | strength from all directions is stabilized, and it leads to suppression of a warp. Furthermore, if necessary, after the slide core is retracted and stopped, the slide core is advanced to compress the volume of the molding hole, thereby eliminating the lack of weld line strength, jetting, and glass fiber floating. Thus, it is possible to eliminate the generation of voids.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows Example 1 of this invention, (A) is a figure which shows the whole structure of an injection molding apparatus, (B) is an external appearance perspective view which shows the product shape shape | molded by a present Example. It is a figure which shows the effect | action of the said Example 1. FIG. It is a flowchart which shows the shaping | molding process by the injection molding apparatus of the said Example 1. FIG. FIG. 3 is a schematic diagram showing a flow of molten resin in the cavity in the molding process of Example 1. It is a figure which shows Example 2 of this invention, (A) is a figure which shows the principal part of an injection molding apparatus, (B) is an external appearance perspective view which shows the product shape shape | molded by a present Example. It is a figure which shows the effect | action of the said Example 2. It is a figure which shows the flow of the molten resin in the cavity in the shaping | molding process of the said Example 2, (A-1)-(A-3) are top views, (B-1)-(B-3) are the said ( It is sectional drawing which cut | disconnected A-1)-(A-3) along the # A- # A line and looked at the arrow direction. It is a figure which shows the whole structure and effect | action of the injection molding apparatus of Example 3 of this invention. It is a flowchart which shows the shaping | molding process by the injection molding apparatus of the said Example 3. It is a figure which shows the other Example of this invention. It is a figure which shows background art, (A) and (B) is a figure which shows the structure and operation | movement of an injection molding apparatus, (C) is an external appearance perspective view which shows a product shape. It is a schematic diagram showing the flow of the molten resin in the cavity in the molding process according to the background art, (A-1) ~ (A-4) shows the case where a weld line occurs, (B-1) ~ (B- 4) shows the case where jetting occurs. It is a figure which shows the example of application of the said background art, (A-1)-(A-3) is a top view which shows the flow of the molten resin in the cavity in a formation process, (B-1)-(B-3) Is an end view of the above-described (A-1) to (A-3) cut along line # B- # B and viewed in the direction of the arrow, and (C) is an external perspective view showing the product shape. It is a figure which shows the structure and effect | action of an injection molding apparatus for implement | achieving the IMP method of background art.

  Hereinafter, the form for implementing this invention is demonstrated in detail based on an Example.

  First, Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1A is a diagram showing the overall configuration of the injection molding apparatus of this embodiment, and FIG. 1B is an external perspective view showing the shape of a product molded by this embodiment. FIG. 2 is a diagram illustrating the operation of the present embodiment, FIG. 3 is a flowchart illustrating the molding process according to the present embodiment, and FIG. 4 is a schematic diagram illustrating the flow of the molten resin in the cavity in the molding process of the present embodiment. is there. The present embodiment is applied to the above-described general injection molding to eliminate insufficient weld line strength and jetting. When a material containing glass fiber is used, glass fiber is used. The structure is also capable of eliminating floating. In the following description, the injection molding method according to this embodiment is referred to as an IMM method (in-mold moving method) as necessary.

  As shown in FIG. 1A, the injection molding apparatus 10 of this embodiment includes a mold 12 including a fixed mold 16 and a movable mold 32, a mold clamping mechanism 70, a control device 76, and a slide core advance / retreat mechanism 80. And an injection device 110 and mold release means. First, the mold 12 will be described. On the fixed side of the mold 12, the fixed mold 16 is attached to the fixed-side mounting plate 14, and the sprue bush 18 passes through the fixed-side mounting plate 14. The fixed mold 16 is provided with runners 20A and 20B and gates 22A and 22B connected to the sprue bush 18. The sprue bush 18 is connected to a nozzle 118 of an injection device 110 described later in order to supply the molten resin 34. The fixed side mounting plate 14 is supported by a fixed plate 60. In addition, the fixed mold 16 is provided with cooling holes (not shown) through which a coolant flows, as necessary, along a surface corresponding to a movable molding hole 36 described later.

  On the other hand, the movable side of the mold 12 has a movable side mounting plate 26, a movable mold 32 whose front end face is opposed to the fixed mold 16, and a leg portion 28 that supports the movable mold 32. By arranging the leg portion 28 between the movable side mounting plate 26 and the movable mold 32, a space 30 in which a slide core 38 described later can be advanced and retracted is formed. The movable mold 32 is formed with a molding hole 36 that extends in the stroke direction of the movable mold 32, and the molding hole 36 causes the front end surface of the movable mold 32 to abut against the fixed mold 16. The cavity C is formed. The molding hole 36 accommodates a part of a slide core 38 that can advance and retreat along the molding hole 36. A rear end surface 38B of the slide core 38 is exposed in the space 30, and is fixed to a slide base 40 including a first plate 40A and a second plate 40B. The movable mounting plate 26 is provided with through holes 26A and 26B. A moving pin 86 of a slide core advance / retreat mechanism 80, which will be described later, passes through the through hole 26A, and a moving pin 88 passes through the through hole 26B. is doing.

  A spring (not shown) may be provided between the slide base 40 and the movable mold 32 as necessary, so that the slide base 40 is always urged toward the movable side mounting plate 26. When the slide base 40 is stroked in the direction of arrow F1a by a slide core advance / retreat mechanism 80 described later, the slide core 38 moves in the molding hole 36 to compress the volume of the cavity C, and the slide base 40 moves in the direction of arrow F1b. If it is made retractable, the volume of the cavity C can be expanded. Furthermore, another through-hole 26C is formed in the substantially central portion of the movable side mounting plate 26, and a protruding rod 46 driven by a hydraulic cylinder 50 provided on the back side of the moving plate 66 described later passes therethrough. It is possible. Then, by driving the hydraulic cylinder 50, the slide core 38 is advanced by pushing the slide base 40 at the tip 46A of the protruding rod 46, and the product molded in the cavity C is extruded and released. That is, the slide core 38 adjusts the volume of the cavity C and, together with the slide base 40, the protruding rod 46, and the hydraulic cylinder 50, constitutes a product release means. The hydraulic cylinder 50 is connected to a control device 76 described later.

  Next, the mold clamping mechanism 70 will be described. The mold clamping mechanism 70 opens and closes the mold 12 by causing the movable side mounting plate 26 to stroke with respect to the fixed side mounting plate 14, and at the time of injection filling of the molten resin 34 by the injection mechanism 110 described later. Twelve partings are clamped by high pressure. In this embodiment, a toggle type mold clamping mechanism is employed as the mold clamping mechanism 70. In the toggle type mold clamping mechanism, a moving plate 66 is disposed between a pair of fixed plates 60 and 62, and the moving plate 66 includes a plurality of guide rods provided between the pair of fixed plates 60 and 62. 64, the stroke is made in the direction of arrows F1a and F1b. The moving plate 66 is connected to the rod 73 of the hydraulic motor 74 through a cam mechanism including a plurality of links 72A to 72F. The rod 73 passes through the fixed plate 62. The fixed-side mounting plate 14 on which the fixed mold 16 is supported is fixed to the fixed plate 60, and the movable-side mounting plate 26 that supports the movable mold 32 is connected to the movable plate via a slide core advance / retreat mechanism 80 described later. 66.

  Next, the slide core advance / retreat mechanism 80 will be described. The slide core advance / retreat mechanism 80 changes the volume of the molding hole 36 by driving the slide core 38 so as to advance and retreat along the molding hole 36 with the mold 12 closed. It comprises a portion 28, a slide base 40, a fixed base 82, moving pins 86 and 88, a spacer 90, a servo motor 98, and the like. Among these, as described above, the leg portion 28 is disposed between the movable side mounting plate 26 and the movable mold 32, and both ends thereof are fixed to the movable side mounting plate 26 and the movable mold 32, respectively. A space 30 in which 38 is advanced and retracted is formed, and the slide base 40 is also as described above. As shown in FIG. 1A, the fixed base 80 has a substantially U-shaped cross section composed of an upper surface 82A and a side surface 82B, and an edge of the side surface 82B is fixed to the moving plate 66. The movable side mounting plate 26 is fixed to. On the upper surface 82A, through holes 84A to 84C are formed at positions corresponding to the through holes 26A to 26C of the movable mounting plate 26, and the moving pin 86 can pass through the through holes 26A and 84A. The moving pin 88 can pass through the through holes 26B and 84B, and the rod 46 can pass through the through holes 26C and 84C.

  The distal ends 86A and 88A of the moving pins 86 and 88 can contact the back side of the slide base 40, and rollers 86B and 88B are provided on the rear ends of the moving pins 86 and 88, respectively. Yes. Further, inside the fixed base 82, it can slide along the main surface of the movable plate 66 in a direction substantially perpendicular to the stroke direction of the movable side mounting plate 26 (directions of arrows F1a and F1b in FIG. 1). A spacer 90 is disposed. The spacer 90 has a shape in which thick portions 92 and thin portions 94 are alternately formed with slopes 96A and 96B sandwiched therebetween, and the surfaces of the thick portions 92 and the thin portions 94 are formed on the movable plate 66. It is almost parallel to the main surface. The spacer 90 is connected to, for example, a servo motor 98 via a shaft 100 and is driven by the servo motor 98. The servo motor 98 is connected to the control device 76 described above. The servo motor 98 is driven by the controller 76 and the spacer 90 is slid, so that the rollers 86B and 88B are in contact with the thick portion 92, the inclined surfaces 96A and 96B, or the thin portion 94 of the spacer 90. It is possible to adjust the retreating amount (or advancement amount) of the moving pins 86 and 88, and consequently the retreating amount (or advancement amount) of the slide core 38. In this embodiment, the servo motor 98 is used from the viewpoint of ease of control, but various other known driving means may be used.

  Next, the control device 76 will be described. The control device 76 controls the driving of the hydraulic motor 74 of the mold clamping mechanism 70 and the hydraulic cylinder 50 of the protruding rod 46, and the slide core advance / retreat mechanism 80 of the slide core advance / retreat mechanism 80 according to the state of injection of molten resin into the cavity C. The drive of the servo motor 98 is also controlled. Specifically, from the start of injection of the resin 34 into the cavity C until the predetermined time elapses, the volume of the molding hole 36 is kept constant in a reduced state, and the injection is performed after the predetermined time elapses. Until the completion, the drive of the servo motor 98 is controlled so that the volume of the forming hole 36 gradually expands. In this embodiment, since a two-point gate structure in which the resin 34 is injected into the cavity C from the two gates 22A and 22B is adopted, the control means 76 has the resin 34 merged in the cavity C completely adhered. Until the cavity volume is reduced, the slide core 38 is controlled to be gradually retracted so that the volume of the cavity C is expanded after the resin 34 is joined and adhered.

  Next, the injection device 110 will be described. The injection device 110 melts the molding material input from the hopper 114 by the cylinder 112, and the sprue 18A, runners 20A and 20B from the nozzle 118 at the tip of the cylinder 112 to the cavity C of the mold 12 by the injection mechanism 116. The molten resin 34 is injected and filled through the gates 22A and 22B, and its structure is known.

  Next, the operation of this embodiment will be described with reference to FIGS. First, by driving the hydraulic motor 74 of the mold clamping mechanism 70, the movable side mold plate 26 is moved in the direction indicated by the arrow F1a in FIG. 1 to mold the mold 12 (step S10 in FIG. 3). Next, when the servo motor 98 of the slide core advance / retreat mechanism 80 is driven, the spacer 90 is pushed in the direction of the arrow F2a shown in FIG. 2A, that is, the rollers 86B and 88B of the moving pins 86 and 88 are moved to the spacer 90. The slide core 38 is moved forward in the molding hole 36 (step S12), and the resin from the injection device 110 is maintained in a predetermined initial set volume. 34 injection is started (step S14). The state at this time is shown in FIG.

  Then, as shown in FIG. 4B, when a certain period of time has elapsed until the resin merged from the tip 34A of the resin 34 injected into the cavity C comes into close contact (step S16), the slide core advance / retreat mechanism 80 By driving, the spacer 90 is gradually retracted in the direction indicated by the arrow F2b in FIG. 2B in synchronization with the injection molding pressure. When the spacer 90 is retracted in the direction of the arrow F2b, the rollers 86B and 88B that have been in contact with the thick portion 92 can move on the inclined surfaces 96A and 96B toward the thin portion 94. The core 38 starts to retract in the direction of the arrow F1b along the molding hole 36 (step S18, FIGS. 4B and 4C)). As shown in FIG. 4D, when the cavity C is expanded to a predetermined volume, the backward movement of the slide core 38 is stopped (step S20), and then the injection of the resin 34 is stopped (step S22).

  Thereafter, cooling is performed (step S24). When cooling is completed, the hydraulic motor 74 of the mold clamping mechanism 70 is driven to open the mold (step S26), and as shown in FIG. By protruding the protruding rod 46 by driving the hydraulic cylinder 50, the product 120 is released from the slide core 38 through the slide base 40 (step S28). Thereafter, if molding is continued (Yes in Step S30), the process returns to Step S10, and Steps S12 to S28 are repeated. If molding is not performed (No in Step S30), the process ends. As shown in FIG. 1 (B), the product 120 obtained by the above steps is welded in a thin state, so that the injection pressure at the time of joining is high, the joining strength is also increased, and the subsequent slide By moving the core 38, it is possible to create a situation where the weld line 124 is absent (including a situation where there is almost no weld line 124), and it is possible to eliminate the insufficient strength of the weld line portion. Moreover, even if it is a case where the material containing glass fiber is used, there exists an effect that glass fiber floating can be prevented. Furthermore, the property that the glass fiber is oriented radially from the gate port is relaxed, the strength from all directions is stabilized, and the warpage is suppressed. In the case of resin injection molding, particularly when a glass fiber-containing material is used, the material flowing out from the gate port spreads radially, and the polymer and glass fibers of the resin are arranged radially. As a result, the strength of the product in the direction away from the gate opening is very strong, and conversely, in the direction of 90 degrees from that direction, the strength is extremely insufficient. According to the IMM method of the present embodiment described above, the orientation occurs at the stage of making the thin product, but when the slide core 38 is moved backward to widen the product, the flow direction of the resin 34 changes by 90 degrees. Therefore, products with random orientation can be produced. For this reason, there is no unevenness in the strength of the product 120, and a stable strength can be obtained in all directions. In addition, since there is no orientation, it is also effective for the problem of warping of the product 120.

As described above, according to the first embodiment, when the resin 34 injected into the cavity C formed between the fixed mold 16 and the movable mold 32 is molded, the resin 34 is formed inside the molding hole 36 that forms the cavity C. Due to the advance / retreat of the slide core 38, the cavity C is maintained at a constant volume from the start of the injection of the resin 34 until a lapse of a certain time, and the slide core 38 is gradually retracted after the lapse of a certain time until the completion of the injection. The volume of was gradually expanded. For this reason, the following effects are acquired.
(1) Even if the weld line 124 of the product 120 is turned off, even if it exists, it can be made to be a very few lines, so the lack of strength of the weld line portion can be solved.
(2) Since the cavity C is expanded to the shape of the actual product 120 from the shape where jetting does not occur at the time of injection, the product 120 having an excellent appearance with no jetting can be created.
(3) In the IMM method of the present embodiment, since the volume of the cavity C is gradually expanded, a strong injection pressure is first applied to the resin 34, and the cavity C is moved to the shape of the product 120 while maintaining the pressure. In order to expand, even if a material containing glass fiber is used as the resin 34, a product excellent in appearance with little glass fiber floating can be obtained. In addition, the property that the glass fibers are oriented radially from the gate ports 122A and 122B is relaxed, the strength is stabilized from all directions, and warpage is suppressed.
(4) Normally, when the resin 34 containing glass fiber is used, when jetting occurs, the weld line is generated in the entire product 120, but according to the IMM method of this embodiment, Since jetting does not occur at all, the strength can be improved.

  Next, Embodiment 2 of the present invention will be described with reference to FIGS. In addition, the same code | symbol shall be used for the component which is the same as that of Example 1 mentioned above, or respond | corresponds (it is the same also about a following example). The first embodiment described above is an example of a mold configuration in which a two-point gate structure is adopted and the resin joins in the cavity. However, in this embodiment, the gate is one place and the resin is placed in the cavity. This is an example using a mold having a shape to merge. FIG. 5 (A) is a diagram showing the main part of the injection molding apparatus of this embodiment, and FIG. 5 (B) is an external perspective view showing the product shape molded by this embodiment. FIG. 6 is a diagram illustrating the operation of the present embodiment. FIG. 7 is a view showing the flow of the molten resin in the cavity in the molding step of this example, (A-1) to (A-3) are plan views, and (B-1) to (B-3) FIG. 4 is a cross-sectional view taken along line # A- # A and viewed in the direction of the arrows (A-1) to (A-3).

  Also in the injection molding apparatus 200 of the present embodiment, the mold 202 is divided into a fixed mold 204 and a movable mold 206. The fixed mold 204 has a one-point gate structure in which only a runner 20B and a gate 22B connected to the sprue bush 18 are formed. On the other hand, on the movable mold 206 side, a cavity C corresponding to the main body 222 of the product 220 shown in FIG. 5B and a molding hole corresponding to the boss 224 of the product 220 and constituting a part of the cavity C are shown. 208 and a through-hole 209 through which the protruding rod 214 penetrates are formed. A part of the substantially cylindrical slide core 210 is accommodated in the molding hole 208. The slide core 210 is for increasing or decreasing the volume of the molding hole 208. One end 210A side is accommodated in the molding hole 208, and the other end 210B is fixed to the first plate 40A of the slide base 40. The fixed portion is covered with the second plate 40B.

  In this embodiment, another slide base 42 is arranged between the slide base 40 and the moving plate 66. The slide base 42 is composed of a first plate 42A and a second plate 42B, and can move forward and backward in the direction of arrow F5 independently of the slide base 40. Through holes 44A and 44B are formed in the slide base 42, the boss hole forming core 212 passes through one of the through holes 44A, and an end portion 212B is fixed to the moving plate 66. . The moving pin 216 is inserted through the other through hole 44B. The moving pin 216 also penetrates the moving plate 66, one end 216 </ b> A can contact the slide base 40, and the other end is connected to the hydraulic motor 218. The hydraulic motor 218 is connected to the control device 76, and the control device 76 controls the advance and retreat of the moving pin 216. In this embodiment, the hydraulic motor 218 is used as the driving means for the moving pin 216. However, a mechanism using the spacer 90 and the servo motor 98 may be used as in the first embodiment. Further, one end portion 214B of the protruding rod 214 is fixed to the first plate 42A of the slide base 42, and the fixed portion is covered with the second plate 42B. The protruding rod 214 is set to a length such that the tip 214A of the protruding rod 214 is flush with the body portion of the cavity C when the slide base 42 is seated on the moving plate 66. When the hydraulic cylinder 50 is driven, the protruding rod 46 advances, and when the slide base 42 is pushed out by the tip 46A of the protruding rod 46, the protruding rod 214 advances accordingly, and the product 200 molded in the cavity C is made of gold. Extrude from the mold 202 and release.

  Next, the operation of this embodiment will be described with reference to FIGS. First, by driving a mold clamping mechanism (not shown) (for example, a mold clamping mechanism 70 similar to that of the first embodiment), the movable side mold plate 206 is moved in the direction indicated by an arrow F6a in FIG. . In this clamped state, the tip 212A of the boss hole forming core 212 is in contact with the end surface of the fixed mold 204. Next, by driving the hydraulic motor 218, the moving pin 216 is advanced, the slide base 40 and the slide core 210 are advanced, the volume of the molding hole 208 is reduced to a predetermined initial setting volume, and the state is maintained. Thus, the injection of the resin 34 into the cavity C from an injection device (not shown) is started. The state at this time is shown in FIG. 6 (A) and FIGS. 7 (A-1) and (B-1).

  The resin 34 injected into the cavity C proceeds as shown by an arrow F7 in FIG. 7, but when it reaches the boss hole forming core 212, it is divided into two hands, and the tip 34A joins from two directions. Then, after waiting for the elapse of a certain time until the resin 34 that has joined from the tip end 34A comes into close contact, the hydraulic motor 218 is driven to retract the moving pin 216 in the direction of arrow F6b in FIG. Then, the slide core 210 starts to retreat in the direction of the arrow F6b along the molding hole 208 by the injection pressure of the resin 34 (FIGS. 7A-2 and 7B-2). Then, as shown in FIGS. 7A-3 and B-3, when the molding hole 208 is expanded to a predetermined volume, the retraction of the slide core 210 is stopped, and then the injection of the resin 34 is stopped. .

  Thereafter, cooling is performed. When the cooling is completed, the mold is opened by a mold clamping mechanism, and the protruding rod 46 of the mold release means is protruded by driving the hydraulic cylinder 50 as shown in FIG. 40 and 42 advance in the direction of arrow F6a, and the product 220 is extruded and released by the tip 210A of the slide core 210 and the tip 216A of the protruding rod 216. Thereafter, the above-described operation is repeated as necessary to perform molding. As shown in FIG. 5 (B), the product 220 obtained by the above process has a weld line 228 of the boss portion 224 or is very shallow even if it exists, and solves the lack of strength of the weld line portion. It becomes possible. As in the present embodiment, if the structure allows the resin to merge within the cavity C even if there is only one gate, as in the first embodiment described above, insufficient weld line strength, jetting, and glass fiber floating. Can be eliminated.

  Next, Embodiment 3 of the present invention will be described with reference to FIGS. The above-described Examples 1 and 2 mainly perform only the IMM method for the purpose of eliminating the strength deficiency of the weld line portion, jetting, and glass fiber floating, but this example is based on the IMM method. This is an example in which the voids of the product can be eliminated by combining the IMP method described above. FIG. 8 is a diagram showing the overall configuration and operation of the injection molding apparatus of this embodiment, and FIG. 9 is a flowchart showing the molding process according to this embodiment. As shown in FIG. 8, the injection molding apparatus used in the present embodiment has the same configuration as the injection molding apparatus 10 of the first embodiment described above. Further, as shown in FIG. 9, the processes from mold clamping (step S10, FIG. 8A) to the stop of injection (step S22) are the same as in the first embodiment.

  In this embodiment, after the injection is stopped as shown in FIG. 8B, cooling of the mold 12 is started by a cooling mechanism (not shown) (step S50 in FIG. 9), and then the servo motor 98 is driven by the controller 76. 8C, by sliding the spacer 90 in the direction of the arrow F2b, the rollers 86B and 88B of the moving pins 86 and 88 ride on the thick portion 92 of the spacer 90, and the moving pins 86 and 88 are the same. It advances in the direction shown by the arrow F8a in the figure and starts compression (step S52). Then, the slide core 38 moves forward in the direction of the arrow F8a through the slide base 40 by the moving pins 86 and 88, and the cavity C is compressed, so that the void 130 as shown in FIG. 8B can be eliminated. Thereafter, when cooling is completed (step S54), the mold is opened as shown in FIG. 8D (step S26), and the product 120 is projected and released (step S28). Steps S26 to S30 are the same as those in the first embodiment.

The following effects can be obtained by combining the IMM method and the IMP method as in the third embodiment.
(1) When only the IMP method is performed, the void 130 can be eliminated, but it is known that stress easily accumulates inside the product 120. This stress appears in the form of cracks inside the product when it is released during cooling, but this crack originates from hot water wrinkles (in a sense, a weld line) existing inside the product. On the other hand, in this example, by combining the IMP method and the IMM method of Example 1, it is possible to prevent the unbalance of the strength lurking inside the product as much as possible and obtain uniform and excellent strength stability. . For example, when the strength of a product with no weld line at one gate is 100, the strength of only two gates can be obtained by normal molding, whereas according to the combination of the IMM method and the IMP method of this embodiment, A test result of strength 75 is obtained at two gates.

(2) By performing the construction method of the present embodiment with, for example, the injection molding apparatus 200 shown in the second embodiment, it is possible to arbitrarily set the weld line strength deficiency, the jetting elimination site, and the compression site. It becomes possible to correspond to the product shape.
(3) Compared to the IMP method of the background art, it is not necessary to arrange a spacer on the side surface of the mold, so the mold structure is simplified, and the effect of improving durability and reducing costs can be obtained.
(4) Compared to the IMP method of the background art, it is not necessary to pull out the spacer arranged on the side of the mold, so there is no need to reduce the mold clamping pressure or zero, and the parting is always clamped with high pressure Generation of burrs can be prevented.
(5) Since the injected resin 34 can be compressed, there is an effect that the degree of freedom of the product shape is increased, and it is possible to deal with a thin product or an uneven product including a thin part.
(6) In the IMP method of the background art, compression using a mold clamping pressure is applied, whereas in the combination method of this embodiment, the slide core compression mechanism 80 for the IMM method is used as the mold clamping mechanism 70. Since it is an externally attached mechanism, it is possible to perform a dedicated operation and control for volume compression and expansion of the cavity C (or the molding hole 36).

  Next, Embodiment 4 of the present invention will be described with reference to FIG. The present embodiment is an example showing another configuration of the slide core advance / retreat mechanism, and the other components are basically the same as those of the first embodiment described above. In the slide core advance / retreat mechanism 250 shown in FIG. 10A, the fixed base 80 is fixed to a plate 252 provided on the moving plate 66, and a thin hydraulic cylinder 254 is provided on the plate 252. ing. The thin hydraulic cylinder 254 is connected to the control device 76. The rear ends of the moving pins 86 and 88 for moving the slide core 38 forward and backward are connected to the thin hydraulic cylinder 254, and the volume of the cavity C is adjusted by the thin hydraulic cylinder 254. In this embodiment, after mold clamping, the movable pins 86 and 88 are advanced by the thin hydraulic cylinder 254 to keep the cavity volume in a certain reduced state, and the injected resin 34 is completely adhered in the cavity C. After waiting, the moving pins 86 and 88 are gradually retracted to expand the cavity volume, thereby obtaining the same effect as in the first embodiment. If necessary, the cavity C may be compressed by the slide core 38 to eliminate voids after completion of injection, as in the third embodiment.

  Next, Embodiment 5 of the present invention will be described with reference to FIGS. 10 (B) and 10 (C). The present embodiment is also an example showing another configuration of the slide core advance / retreat mechanism, and the other components are the same as those of the first embodiment described above. FIG. 10B is a diagram showing the overall configuration of the injection molding apparatus of the present embodiment, and FIG. 10C is a plan view of the slide base as viewed from the moving plate 66 side. In the slide core advance / retreat mechanism 260 of the present embodiment, a large-diameter screw member 264 is rotatably supported on the plate 262 fixed on the moving plate 66. On the other hand, a large-diameter nut 266 is rotatably attached to the back surface of the slide core 40. A gear portion 268 is formed on the outer peripheral surface of the nut 266. A motor 272 is provided on the front side of the slide base 40. An output shaft of the motor 272 passes through the slide base 40, and a gear 274 and a gear portion 268 are provided at the tip of the output shaft. A belt 270 is hung on the belt. Accordingly, when the nut 266 is rotated by the drive of the motor 272 via the gear 274, the belt 270, and the gear portion 268, the screw member 264 that meshes with the nut 266 is fixed to the plate 262. It will advance and retreat. The motor 272 is connected to the control device 76 together with the hydraulic motor 74.

  In this embodiment, after clamping the mold, the slide base 40 is advanced by driving the motor 272 to keep the cavity volume in a certain reduced state, and waits for the injected resin 34 to be completely adhered in the cavity C. Then, the slide base 40 and the moving pins 86 and 88 are gradually retracted by driving the motor 272 to expand the cavity volume. Similarly to the third embodiment, if necessary, the cavity C may be compressed by the slide core 38 after the injection is completed to eliminate voids. The effect of the present embodiment is the same as that of the first embodiment described above.

In addition, this invention is not limited to the Example mentioned above, A various change can be added in the range which does not deviate from the summary of this invention. For example, the following are also included.
(1) In the first embodiment, the portion of the fixed mold 16 that faces the molding hole 36 of the movable mold 32 is flat, but a corresponding molding irregularity can be formed according to the shape of the product. The same applies to the other embodiments.
(2) The slide core advance / retreat mechanism 80 using the spacer 90 and the servo motor 98 shown in the first embodiment, the slide core advance / retreat mechanism 250 of the fourth embodiment, and the slide core advance / retreat mechanism 260 of the fifth embodiment are examples. The design can be changed as appropriate within a range that exhibits the same effect. For example, as in the example shown in FIG. 10D, three protruding pins 280A to 280C that pass through the movable side mold plate 26 and can be driven by the hydraulic cylinders 282A to 282C are provided, and any of these protruding pins 280A to 280C is provided. These may be used as means for pushing out the slide core. In the first embodiment, the slide base 40 is composed of the first plate 40A and the second plate 40B. However, this is also an example, and the slide core can be changed by increasing or decreasing the number of plates constituting the slide base 40. The amount of movement may be adjusted.

(3) In the above embodiment, the case where the number of gates is one or two is given as an example. However, this is also an example, and the present invention can be applied to a configuration having three or more gates.
(4) In the second embodiment, the case where the product 220 having the boss portion 224 is molded is taken as an example. However, this is also an example. The present invention can be applied to all mold structures in which the two merge.
(5) The present invention is suitable, for example, when a glass-filled resin is used, but is not limited thereto, and can be applied to injection molding using various known molding materials.

  According to the present invention, by moving the slide core back and forth inside a forming hole that forms at least a part of the cavity formed between the fixed mold and the movable mold, the molding is performed until a certain time has elapsed from the start of injection. The hole was maintained in a certain reduced state, and the slide core was gradually retracted until the injection was completed after a lapse of a certain time, and the volume of the forming hole was continuously expanded. For this reason, it is applicable as an injection molding apparatus and method in which the strength of the weld line portion is insufficient and the elimination of jetting is required. In particular, glass fiber floating can be prevented, the property that glass fibers are oriented radially from the gate opening, and the strength from all directions can be stabilized to suppress warping. It is suitable for the case. In addition, if necessary, the volume of the forming hole can be compressed by the slide core after completion of the injection to prevent the generation of voids, which is suitable for forming thick products and uneven products.

DESCRIPTION OF SYMBOLS 10: Injection molding apparatus 12: Mold 14: Fixed side template 16: Fixed type 18: Sprue bush 18A: Sprue 20A, 20B: Runner 22A, 22B: Gate 26: Movable side mounting plate 26A-26C: Through-hole 28: Leg part 30: Space 32: Movable type 34: Resin 34A: Front end part 36: Molding hole 38: Slide core 38A: Front end face 38B: Rear end face 40, 42: Slide base 40A, 42A: First plate 40B, 42B: First 2 plates 44A, 44B: through hole 46: protruding rod 46A: tip 50: hydraulic cylinder 60, 62: fixed plate 64: guide rod 66: moving plate 70: mold clamping mechanism 72A to 72F: link 73: rod 74: hydraulic motor 76: Control device 80: Core advance / retreat mechanism 82: Fixed base 82A: Upper surface 82B: Side surface 4A to 84C: Through hole 86, 88: Moving pin 86A, 88A: Tip 86B, 88B: Roller 90: Spacer 92: Thick part 94: Thin part 96A, 96B: Slope 98: Servo motor 100: Shaft 110: Injection device 112: cylinder 114: hopper 116: injection mechanism 118: nozzle 120: product 122A, 122B: gate port 124: weld line 130: void 200: injection molding device 202: mold 204: fixed mold 206: movable mold 208: molding hole 209: Through hole 210: Slide core 210A: Front end 210B: Rear end 212: Boss hole forming pin 212A: Front end 212B: Rear end 214: Protruding rod 214A: Front end 214B: Rear end 216: Protruding pin 216A: Front end 216B: Rear end 218: Hydraulic motor 220: Product 222: Body portion 224: Boss portion 2 4A: Boss hole 226: Gate port 228: Weld line 250: Core advance / retreat mechanism 252: Plate 254: Thin hydraulic cylinder 260: Core advance / retreat mechanism 262: Plate 264: Screw member 266: Nut 268: Gear portion 270: Belt 272: Motor 274: Gears 280A to 280C: Protruding rods 282A to 282C: Hydraulic cylinder 300: Injection molding device 302: Fixed side mounting plate 304: Fixed mold 306: Sprue bush 308: Runner 310A, 310B: Gate 312: Movable side mounting plate 312A: Through-hole 314: Leg 316: Movable mold 318: Space 320: Spring 322: Slide base 322A, 322B: Main surface 326A, 326B: Protruding pin 328: Protruding rod 328A: Tip 330: Resin 332: Tip 340: Product 342 : Eld lines 344A, 344B: Gate port 350: Mold 351: Main body 352: Molding hole 354: Boss hole forming core 360: Product 362: Boss part 362A: Boss hole 364: Weld line 400: Injection molding device 402: Fixed Side mounting plate 404: fixed die 406: sprue bush 408: nozzle 410: movable side mounting plate 412: movable die 414: leg 416: spacer 418: molding hole 420: slide core 422: slide base 424: pressure sensor 430: resin C: Cavity

Claims (10)

A movable mold supported by the movable mounting plate, and a mold in which a cavity into which molten resin is injected and filled is formed when the end surface of the fixed mold supported by the fixed mounting plate is brought into contact with the movable mold;
An injection mechanism for injecting and filling molten resin into the cavity;
A mold clamping mechanism that strokes the movable side mounting plate with respect to the fixed side mounting plate to open and close the mold, and at the time of injection filling of the molten resin by the injection mechanism, a mold clamping mechanism for high pressure clamping
One or more formed on the movable mold in the stroke direction, opening at an end face facing the fixed mold, and forming at least a part of the cavity when the fixed mold is brought into contact with the end face Molding holes,
A part of the molding hole is housed, and a slide core capable of moving back and forth along the molding hole;
With the mold closed, the slide core is driven so as to advance and retreat along the molding hole, and a slide core advance / retreat mechanism that changes the volume of the molding hole;
Control means for driving the slide core advance / retreat mechanism in accordance with the state of injection of the molten resin into the cavity;
Mold release means for extruding and releasing the product after injection molding from the cavity;
With
The control means includes
The volume of the molding hole is kept constant from the start of the injection of the molten resin into the cavity until a predetermined time elapses, and the volume of the molding hole gradually expands after the predetermined time elapses until the injection is completed. As described above, the injection molding apparatus controls the slide core advance / retreat mechanism. The molten resin injected into the cavity merges at one or more locations in the cavity,
2. The injection molding apparatus according to claim 1, wherein the control unit drives the slide core advancing / retreating mechanism in a direction in which the volume of the molding hole is expanded after the joined molten resin comes into close contact.   The injection molding apparatus according to claim 1 or 2, wherein the cavity has a shape corresponding to a product having a boss or a recess.   The injection molding apparatus according to claim 1 or 2, wherein molten resin is injected from the injection mechanism into the cavity through a plurality of gate ports. The slide core advance / retreat mechanism is
A leg that is disposed between the movable side mounting plate and the movable mold, and forms a space in which the slide core advances and retreats;
A slide base disposed in a space formed by the legs, one of the main surfaces being attached to the rear end of the slide core;
One or more moving pins penetrating the movable side mounting plate in the forward / backward direction and having one end abutting against the other main surface of the slide base;
A moving pin driving means disposed on the other end side of the moving pin, for driving the moving pin in the advancing and retracting direction;
The injection molding apparatus according to any one of claims 1 to 4, further comprising: The mold release means
A projecting rod that pushes the slide core forward through the slide base;
A protruding rod driving means for driving the protruding rod in the advancing and retracting direction;
The injection molding apparatus according to any one of claims 1 to 5, further comprising: The control means includes
The injection molding apparatus according to claim 1, wherein after the expansion of the volume of the molding hole is stopped, the slide core is advanced to compress the volume of the molding hole. An injection molding method in which a molten resin is injected and filled into a cavity formed on a dividing surface of a movable mold and a fixed mold, and then cooled and solidified. It is provided so as to be able to advance and retreat in the movable stroke direction,
A step of advancing the slide core in a mold-clamping state, and reducing and maintaining the molding hole to a predetermined volume;
Starting injection of molten resin into the cavity;
A step of gradually expanding the volume of the molding hole by gradually retracting the slide core after a predetermined time has elapsed since the injection of the molten resin started.
Stopping the volume expansion of the forming hole;
Starting cooling of the molten resin injected and filled into the cavity;
A process of opening and releasing the mold after cooling and solidifying,
An injection molding method comprising: The molten resin injected into the cavity merges at one or more locations in the cavity,
9. The injection molding method according to claim 8, wherein the step of expanding the volume of the molding hole is started after the molten resin joined in the cavity comes into close contact. A step of advancing the slide core to compress the volume of the forming hole after the cooling start step;
Including
The injection molding method according to claim 8 or 9, wherein after the compression step, the cooled and solidified product is opened and released.

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