Injection molding apparatus and injection molding method

Abstract

To manufacture easily a resin molded product having good characteristics.SOLUTION: In an injection molding apparatus having a cylinder 11, a screw S deployed in the cylinder 11, and a drive unit 17 for controlling rotation, advancement, and retreat of the screw S, the cylinder 11 has a supply port 13h located upstream and supplied with a resin material, and a split cylinder part 11B located downstream from the supply port 13h, the split cylinder part 11B is selected from a plurality of split cylinder parts having a filler supply port 15h and provided with holes at different positions or different sizes. By preparing the plurality of split cylinder parts 11B in this way, a degree of freedom in setting a size and position of the filler supply port 15h is increased, and an appropriate filler supply port can be selected according to the resin material, a filler material, and a combination thereof. Thereby, for example, a resin molded product having good characteristics such as good dispersibility of the filler can be produced.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention can be suitably used in an injection molding apparatus and an injection molding method. [Background technology]

[0002] In recent years, resin composite materials using fillers (such as carbon fibers) have been attracting attention. In particular, studies have been conducted on improving the mechanical strength of molded articles by producing them using resins containing fillers.

[0003] Such a molded article using a composite material can be obtained by kneading a resin and a filler using an injection molding device and then injecting the mixture into a mold.

[0004] For example, Patent Document 1 discloses an injection molding technique using a molding material containing carbon fiber resin pellets and glass fiber resin pellets. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2018-167409 Summary of the Invention [Problem to be solved by the invention]

[0006] The present inventors have been engaged in research and development of filler-containing resins using injection molding machines and extruders, and have been making intensive studies into improving the reinforcing effect of resins by adding fillers.

[0007] Such a molded body made of a filler-containing resin can be formed by using an injection molding device. The injection molding device has a cylinder and a screw rotatably arranged in the cylinder. For example, resin pellets supplied from a hopper into the cylinder are melted in the cylinder and sent forward by the screw, and then a filler is added, the molten resin and the filler are kneaded, and a predetermined amount of the mixture is injected into a mold from the injection molding device to form a molded body of a desired shape.

[0008] Here, in order to improve the mechanical strength of the molded body, it is necessary for the filler to be uniformly dispersed in the resin, but when the filler is added after the resin pellets are melted, the filler is added midway through the cylinder. Furthermore, injection molding machines often use a long cylindrical cylinder that is molded as an integral unit, and the position and size of the supply port for adding the filler that is provided at the time of design cannot be easily changed.

[0009] For example, in order to extend the kneading time, it may be desirable to add the filler further upstream in the cylinder, and it would be desirable to develop an injection molding device that can easily meet such requirements.

[0010] Other objects and novel features will become apparent from the description of this specification and the accompanying drawings. [Means for solving the problem]

[0011] The injection molding apparatus disclosed in the present application has a cylinder, a screw disposed within the cylinder, and a drive unit that controls the rotation, forward movement, and backward movement of the screw, wherein the cylinder has a first hole located upstream through which a resin material is supplied, and a split cylinder portion located downstream of the first hole, the split cylinder portion having a second hole, and the split cylinder portion being selected from a plurality of split cylinder portions having holes in different positions or of different sizes.

[0012] The injection molding method disclosed in the present application includes the steps of: (a) preparing an injection molding apparatus having a cylinder and a screw disposed in the cylinder, and a mold connected to the tip of the injection molding apparatus; (b) supplying a resin material into the cylinder from a first hole provided upstream of the cylinder, melting the resin material and forming a molten resin; (c) supplying an additive from a second hole provided downstream of the first hole of the cylinder, and kneading the molten resin with the additive to form a molten resin containing the additive; and (d) kneading the molten resin with the additive from the tip of the screw. (e) measuring the additive-containing molten resin at the tip of the screw by retracting the screw so that the end of the screw is retracted by a first stroke from a first position to a second position; and (f) injecting the additive-containing molten resin into the mold by advancing the screw, wherein the cylinder in step (a) has a split cylinder portion including the second hole, and step (a) includes a step of selecting a split cylinder portion including the second hole from a plurality of split cylinder portions having holes in different positions or of different sizes. Effect of the Invention

[0013] The injection molding apparatus disclosed in the present application makes it possible to manufacture resin molded articles with excellent characteristics.

[0014] According to the injection molding method disclosed in the present application, a resin molded article with excellent properties can be produced. [Brief description of the drawings]

[0015] [Figure 1] 1 is a diagram showing a configuration of a manufacturing apparatus (manufacturing system) for a filler-containing resin molded body according to a first embodiment. [Diagram 2] FIG. 1 is a diagram showing an injection molding device and an injection molding process. [Diagram 3] FIG. 2 is a diagram showing a configuration of a screw drive unit. [Figure 4] 11A to 11C are diagrams illustrating another injection molding process. [Diagram 5] 11A to 11C are diagrams illustrating another injection molding process. [Figure 6] FIG. 11 is a cross-sectional view showing a connection configuration of split cylinder portions in Application Example 1 of Embodiment 2. [Figure 7] FIG. 11 is a cross-sectional view showing the position of a supply port of a divided cylinder portion in Application Example 2 of Embodiment 2. [Figure 8] 13 is a perspective view showing the vicinity of the supply port of the divided cylinder part of Application Example 3 of Embodiment 2. FIG. [Figure 9] 13 is a perspective view showing the vicinity of the supply port of the divided cylinder part of Application Example 4 of Embodiment 2. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, the embodiment will be described in detail with reference to examples and drawings. In all the drawings for explaining the embodiment, the same reference numerals are used to designate members having the same functions, and the repeated description thereof will be omitted.

[0017] (Embodiment 1) 1 is a diagram showing the configuration of a manufacturing apparatus (manufacturing system) for a filler-containing resin molded body according to the present embodiment. This apparatus includes an injection molding apparatus 1 and a press machine 5. Here, a process of directly mixing filler-free resin pellets (resin material) with a filler to form a molded body (molded body) will be described as an example. Note that powdered resin may be used as the raw material instead of pellets.

[0018] The injection molding apparatus 1 melts the supplied raw material resin pellets RP, then adds filler F, and mixes and kneads the mixture to form a filler-containing molten resin (MRF). The injection molding apparatus 1 has a cylinder 11 whose temperature is controlled by a temperature adjustment means (not shown), a single-shaft screw S arranged inside the cylinder 11, and a screw drive unit 17 connected to the screw S. A discharge nozzle 19 is provided at the tip (downstream end) of the cylinder 11.

[0019] The cylinder 11 has a supply port 13h for resin pellets RP disposed upstream of the cylinder 11 and a supply port 15h for the filler F. The supply port 13h is connected to a hopper (supply device, charging device) 13 for the resin pellets RP, and the supply port 15h is connected to a supply device 15 for the filler F. The cylinder 11 is, for example, a member extending in the X direction (axial direction) and has a cylindrical space in which a screw S is disposed. Here, the cylinder 11 is described as being cylindrical, but the outer shape may be rectangular as long as it has a space in which the screw S is disposed.

[0020] Here, the vicinity of the supply port 15h of the cylinder 11 is a replaceable split cylinder portion (intermediate cylinder portion, split block portion) 11B. That is, the cylinder 11 is composed of a front stage portion (11A), a split cylinder portion 11B, and a rear stage portion (11C). And four types of split cylinder portions 11B are prepared. Specifically, (1) a split cylinder portion (FIG. 1(A)) in which a supply port 15h having a first hole diameter r1 is provided at the central portion of the split cylinder portion (a portion including the center of the length in the X direction), (2) a split cylinder portion (FIG. 1(B), r2 < r1) in which a supply port 15h having a second hole diameter r2 is provided at the central portion of the split cylinder portion (a portion including the center of the length in the X direction), (3) a split cylinder portion (FIG. 1(C)) in which a supply port 15h having the second hole diameter r2 is provided at the upstream portion of the split cylinder portion (a portion between the center of the length in the X direction and the upstream end portion), (4) a split cylinder portion (FIG. 1(D)) in which a supply port 15h having the second hole diameter r2 is provided at the downstream portion of the split cylinder portion (a portion between the center of the length in the X direction and the downstream end portion) are prepared. And here, (1) the split cylinder portion (FIG. 1(A)) in which a supply port 15h having a first hole diameter r1 is provided at the central portion of the split cylinder portion (a portion including the center of the length in the X direction) is selected and incorporated into the cylinder 11.

[0021] For example, the divided cylinder section 11B of (1) has a larger diameter of the supply port 15h than the divided cylinder section 11B of (3), and the supply port 15h is arranged further upstream, so that the supply amount of the filler F (e.g., carbon fiber) can be secured, and the length of the screw S that the filler F comes into contact with after being supplied into the molten resin can be secured. Therefore, the kneading property of the molten resin and the filler F can be improved.

[0022] In this way, by preparing multiple split cylinders, the freedom in setting the size and position of the filler supply port is increased, and an appropriate filler supply port can be selected depending on the resin material, filler material, and combination of these.

[0023] As described above, the cylinder of an injection molding machine is often molded as a single unit, and the supply port provided at the time of design cannot be easily changed, but according to the present embodiment, the filler supply port can be easily changed. This makes it possible to manufacture a resin molded product with good properties, such as good filler dispersion.

[0024] It should be noted that there are many different combinations of hole diameters and positions of the supply ports provided in the divided cylinder portions, and they are not limited to those described above.

[0025] The split cylinder portion is provided in the middle of the cylinder, that is, between the front stage portion (11A) and the rear stage portion (11C), and the front stage portion (11A), the split cylinder portion (11B), and the rear stage portion (11C) are different in length, and the split cylinder portion (11B) is shorter than the front stage portion (11A) (its length in the X direction is smaller) and shorter than the rear stage portion (11C). Note that a split cylinder may be provided at the connection portion with the discharge nozzle 19, and in this case, the portion excluding this portion can be regarded as the front stage portion (11A). In addition, when the outer diameter (maximum outer diameter) of the screw S is D, the front stage portion (11A) is, for example, 8D to 18D, the split cylinder portion is, for example, 3D to 8D, and the rear stage portion (11C) is, for example, 10D to 20D.

[0026] The press machine 5 has, for example, a first mold SL and a second mold SR, and a filler-containing molten resin MRF is injected (injected, discharged) into the gap between them and solidified into a shape corresponding to the mold, thereby forming a molded body.

[0027] FIG. 2 is a diagram showing an injection molding apparatus and an injection molding process. As shown in FIG. 2, a screw S is inserted and built into a cylinder 11 so that it can be rotated (freely rotated) by a drive unit 17 and can move forward and backward.

[0028] There is no limitation on the shape of the screw S, but in FIG. 2, the screw S is mainly composed of a full-flight type screw provided with a helical protrusion (thread). The screw S has a plurality of screw parts (screw pieces). Specifically, the screw S has a plurality of screw parts with different groove depths (protrusion heights). For example, the screw S1 on the upstream side (hopper 13 side) has a screw part S1a and a screw part S1b whose groove is shallower than the screw part S1a. The screw S2 on the downstream side (discharge nozzle 19 side) has a screw part S2a and a screw part S2b whose groove is shallower than the screw part S2a. The screw S1 on the upstream side is arranged from the supply port 13h to the supply port 15h, and the screw S2 on the downstream side is arranged from the supply port 15h to the upstream side. Such a screw configuration is sometimes called a two-stage type. Here, a part (piece) with a pointed shape toward the tip is arranged at the tip of the screw S.

[0029] In the screw section S1a corresponding to the supply section (13h) of the resin pellets RP, it is preferable to use a screw section with deep grooves to ensure volume, and in the screw section S1b through which the molten resin passes, it is preferable to use a screw section with shallow grooves to improve the kneading ability of the resin and to prevent the molten resin from leaking out (venting up) from the supply port 15h.

[0030] In addition, in the screw section S2a corresponding to the supply section (15h) of the filler F, it is preferable to make the groove deep and create a starvation state, and in the screw section S2b through which the kneaded product of the molten resin and the filler F passes, it is preferable to use a screw section with a shallow groove in order to improve the kneading property of the resin.

[0031] In addition, although a full-flight type screw (screw section) is used in Fig. 2, screws (screw sections) of other shapes may be used. For example, in the screw section S2b, a Dulmage type, Maddock type, pin type, static mixer type screw, etc. may be used to improve the kneading property.

[0032] As described above, the screw S is composed of multiple screw sections (screw pieces). Therefore, even if the length ratio of the screw sections S1a and S1b or the length ratio of the screw sections S2a and S2b is changed, it becomes necessary to adjust the filler supply port to an optimal position. Even in such a case, as described above, by preparing multiple divided cylinder sections 11B, the filler supply port can be easily adjusted.

[0033] FIG. 3 is a diagram showing the configuration of the screw drive unit. As shown in FIG. 3, the screw S is connected to a line drive mechanism 17L that moves the screw S forward or backward, and a rotation drive mechanism 17R that rotates the screw S. The line drive mechanism 17L and the rotation drive mechanism 17R are controlled by a control unit 17C of the screw. A load cell 17S between the line drive mechanism 17L and the screw S is a sensor that detects the load (back pressure) that the screw S receives in the axial direction. For example, the forward and backward movement of the screw S can be controlled based on a signal from the load cell 17S.

[0034] For example, as shown in FIG. 1, resin pellets RP supplied from a hopper 13 through a supply port 13h are melted in the cylinder 11 and transferred downstream while being stirred by the screw S. Then, filler F is supplied into the molten resin from a filler F supply port 15h, and the kneaded product of the molten resin and filler F is transferred to and stored at the tip of the cylinder 11. In this way, when the kneaded product of the molten resin and filler F stored at the tip of the cylinder 11 increases, a force pushing back (a retreating force) acts on the screw S. This force is called "back pressure" and corresponds to the output (signal) of the load cell described above.

[0035] The amount of the kneaded material stored can be known by such an increase in back pressure. For example, after a predetermined back pressure is reached, the screw S is retreated by a distance (first stroke) corresponding to one discharge amount (1S) (measurement process). That is, the screw S is retreated by the line drive mechanism (17L) to store (measure) a predetermined amount of the kneaded material at the tip of the cylinder 11, and then the screw S is advanced, so that a predetermined amount of the kneaded material can be discharged from the discharge nozzle (19) to the mold (press machine 5) (see FIG. 1). Note that, if the kneading time is extended to improve the kneadability, the amount of the kneaded material stored at the tip of the cylinder 11 increases and the back pressure becomes too large, so it is necessary to improve the kneadability before the predetermined back pressure (output of a predetermined load cell) is reached. Therefore, the position adjustment of the filler supply port as in this embodiment is very useful.

[0036] In the injection molding apparatus shown in FIG. 2, the supply port 15h has been described as a supply port for the filler F. However, there is no limitation on the use of the supply port 15h. For example, as shown in FIG. 4, the supply port 15h may be used to supply a gas (e.g., nitrogen (N 2 That is, the supply port 15h may be a supply port for a gas (for example, nitrogen (N 2)) supply device is connected. Also, as shown in FIG. 5, a vent hole 15v for releasing gas in the molten resin may be provided at the position of the supply port (15h). For example, a degassing device (pressure reducing device) is connected to the supply port 15h. FIG. 4 and FIG. 5 are diagrams showing other injection molding processes (treatment processes). The nitrogen injection process and degassing process as described above can prevent, for example, oxidation of the resin material. In these processes, it is necessary to improve the kneading property in order to homogenize the effects of each process.

[0037] In this way, the holes provided in the middle of the cylinder 11 can be used as supply ports or vent holes for additives (including gases). When such holes are provided, by providing the holes in the divided cylinder portion (middle cylinder) 11B, it is possible to optimally arrange the holes (supply ports and vent holes) at low cost in accordance with the processing between the first stage and the second stage.

[0038] (Embodiment 2) In this embodiment, various application examples of the above embodiment will be described.

[0039] (Application example 1) Fig. 6 is a cross-sectional view showing the connection structure of the split cylinder parts of this application example. The front stage part (11A) of the cylinder and the split cylinder part 11B are connected by, for example, nuts and bolts. For example, as shown in Fig. 6(A), a hole in the flange part of the front stage part (11A) of the cylinder is aligned with a hole in the flange part at one end of the split cylinder part 11B, a bolt is passed through, and they are fixed with a nut. Similarly, a hole in the flange part of the rear stage part (11C) of the cylinder is aligned with a hole in the flange part at the other end of the split cylinder part 11B, a bolt is passed through, and they are fixed with a nut.

[0040] Also, as shown in Fig. 6(B), a nested spigot structure may be provided at the connection between the front stage (11A) of the cylinder and the split cylinder section 11B. Specifically, a convex portion is provided at the end of the front stage (11A) of the cylinder, and a concave portion that fits the convex portion is provided on the split cylinder section 11B side. Also, as shown in Fig. 6(C), the side surfaces of the convex portion and the concave portion may be tapered and in contact with each other.

[0041] By providing such a spigot structure, it is possible to reduce connection distortion between the front stage part (11A) of the cylinder and the divided cylinder part 11B. In particular, in an injection molding machine, accurate metering is required, and therefore accurate connection with the central axes of the front stage part (11A) of the cylinder and the divided cylinder part 11B aligned is required. For example, the gap between the screw S and the cylinder 11 is, for example, about 1 mm to 0.1 mm, and slight connection distortion can cause a metering error. For this reason, by employing the above spigot structure, it is possible to reduce connection distortion and perform accurate metering and injection.

[0042] In the above-mentioned spigot structure, the upper surface of the protruding portion of the front stage (11A) or the rear stage (11C) and the bottom surface of the recessed portion of the divided cylinder portion 11B need only be in contact with each other, and these contact surfaces form a sealing surface. In this way, by adopting the spigot structure, the contact area of ​​the sealing surface can be reduced, and the surface pressure can be increased to prevent resin leakage.

[0043] (Application example 2) Fig. 7 is a cross-sectional view showing the position of the supply port of the split cylinder part of this application example. The position of the supply port 15h may be, for example, located directly above the split cylinder part 11B as described above (Fig. 7(A)), or may be located at an angle θ from directly above the split cylinder part 11B as shown in Fig. 7(B).

[0044] For example, in the case where the supply port 13h through which the resin pellets RP are supplied is disposed directly above (Z direction), the supply port 15h provided in the split cylinder part 11B may also be disposed directly above (Z direction), or the supply port 15h provided in the split cylinder part 11B may be disposed at a position shifted by an angle θ (e.g., 45°) from directly above (Z direction). In other words, the split cylinder part 11B can be incorporated into the cylinder so that the supply port 15h can be adjusted to a position at an angle of 0° or an angle θ (e.g., 45°) with respect to the supply port 13h.

[0045] (Application example 3) FIG. 8 is a perspective view showing the vicinity of the supply port of the split cylinder part of this application example. In this application example, a plurality of supply ports (15h) are provided in the split cylinder part, and some of them are covered with a plate (lid part). For example, as shown in FIG. 8(A), six supply ports 15ha to 15hf may be provided in the split cylinder part, and the necessary positions and number of supply ports (e.g., 15hb, 15he) may be selected, and the remaining supply ports (e.g., 15ha, 15hc, 15hd, 15hf) may be blocked with a metal plate (plate) 11P (FIG. 8(B)). The metal plate (plate) 11P may be fixed, for example, by screwing it to the side surface of the split cylinder part 11B.

[0046] (Application example 4) 9 is a perspective view showing the vicinity of the supply port of the divided cylinder part of this application example. In this application example, a horizontally long supply port 15hL is provided, and a part of it is covered with a plate (lid part). The horizontally long supply port 15hL is a hole whose length in the X direction is longer than its length in the Y direction.

[0047] For example, the horizontally long supply port 15hL shown in Fig. 9(A) is covered with a metal plate (plate) 11P having a hole 11Ph on the upstream side (Fig. 9(B)). Also, the horizontally long supply port 15hL shown in Fig. 9(A) is covered with a metal plate (plate) 11P having a hole 11Ph in the center of the split cylinder portion 11B (Fig. 9(C)). Also, the horizontally long supply port 15hL shown in Fig. 9(A) is covered with a metal plate (plate) 11P having a hole 11Ph on the downstream side of the split cylinder portion 11B (Fig. 9(D)).

[0048] Moreover, the horizontally elongated supply port 15hL shown in FIG. 9(A) is covered with a metal plate 11P having a small diameter hole 11Ph provided on the downstream side of the divided cylinder portion 11B (FIG. 9(E)).

[0049] In addition, the horizontally elongated supply port 15hL shown in Figure 9(A) is covered with a metal plate (plate) 11P having a small diameter hole 11Ph on the downstream side of the split cylinder portion 11B and a large diameter hole 11Ph on the upstream side of the split cylinder portion 11B (Figure 9(F)).

[0050] In this manner, in this application example, the size and position of the supply port can be easily adjusted by changing the size and position of the hole provided in the metal plate (plate) 11P.

[0051] Although the supply port has been described above as an example, the size and position of the vent hole can also be easily adjusted by changing the size and position of the hole provided in the metal plate 11P.

[0052] The invention made by the inventor has been specifically described above based on the embodiment and examples. However, the present invention is not limited to the above embodiment or examples, and it goes without saying that various modifications can be made without departing from the gist of the invention. [Explanation of symbols]

[0053] 1 Injection molding equipment 5 Press machine 11 Cylinders 11A Front part 11B Split cylinder section 11C Rear section 11P Metal plate 11Ph Hole 13 Hopper 13h supply port 15 Feeding device 15h supply port 15ha~15hf Supply port 15hL Horizontal supply port 15v vent hole 17 Drive unit 17C Screw control section 17L Line Drive Mechanism 17R Rotational Drive Mechanism 17S Load Cell 19 Discharge nozzle F filler MRF Filler-containing molten resin RP Resin Pellets S screw S1 Screw S1a screw section S1b screw section S2 Screw S2a screw section S2b screw section SB lower mold SU upper mold

Claims

1. The present invention has a cylinder, a screw disposed in the cylinder, and a drive unit that controls the rotation, forward movement, and backward movement of the screw, the cylinder has a first hole located upstream and through which a resin material is supplied, and a divided cylinder portion located downstream of the first hole, An injection molding apparatus, wherein the split cylinder portion has a second hole which is a supply port for an additive to be added to the resin material, and the split cylinder portion can be selected from a plurality of split cylinder portions having holes in different positions or of different sizes.

2. The present invention has a cylinder, a screw disposed in the cylinder, and a drive unit that controls the rotation, forward movement, and backward movement of the screw, the cylinder has a first hole located upstream and through which a resin material is supplied, and a divided cylinder portion located downstream of the first hole, An injection molding apparatus, wherein the split cylinder portion has a second hole and is assembled to the cylinder so as to be adjustable to a first angular position or a second angular position relative to the first hole.

3. The present invention has a cylinder, a screw disposed in the cylinder, and a drive unit that controls the rotation, forward movement, and backward movement of the screw, the cylinder has a first hole located upstream and through which a resin material is supplied, and a divided cylinder portion located downstream of the first hole, An injection molding apparatus, wherein the split cylinder portion has a second hole and a lid portion covering a portion of the second hole, thereby making it possible to adjust the size and / or position of the hole that is not covered by the lid portion.

4. (a) preparing an injection molding device having a cylinder and a screw disposed in the cylinder, and a mold connected to a tip of the injection molding device; (b) supplying a resin material into the cylinder through a first hole provided upstream of the cylinder and melting the resin material to form a molten resin; (c) supplying an additive from a second hole provided downstream of the first hole of the cylinder and kneading the molten resin with the additive to form a molten resin containing the additive; (d) metering the additive-containing molten resin at the tip of the screw by retracting the screw such that the tip of the screw is retracted by a first stroke from a first position to a second position; (e) injecting the additive-containing molten resin into the mold by advancing the screw; The cylinder in the step (a) has a divided cylinder portion including the second hole, The (a) step includes a step of selecting a divided cylinder portion including the second hole from a plurality of divided cylinder portions having holes in different positions or of different sizes.

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