Injection molding machine

Abstract

In an injection molding machine of one embodiment, a lid portion having a through-hole into which a root portion of a screw is fitted is fitted to a rear end of a cylinder, a sink is formed in a center portion of a front surface of the lid portion that abuts against a rear end surface of the cylinder, and a U-shaped gasket is provided in the sink in such a manner that an inner peripheral surface thereof abuts against an outer peripheral surface of the root portion of the screw and a concave surface thereof faces the rear end surface of the cylinder.

Description

Technical Field

[0001] This invention relates to injection molding machines. Background Technology

[0002] As disclosed in Patent Document 1, an injection molding machine is known in which a thermosetting liquid resin as a raw material is injected into a cylinder, injected into a mold through a screw, and heated inside the mold to cure the resin.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2023-151749 Summary of the Invention

[0004] When the inventors were developing an injection molding machine that used liquid thermosetting resins as raw materials as described above, they encountered a variety of problems. For example, a sealing ring is provided on the outer circumferential surface of the screw root to seal the screw root and the cylinder body. This sealing ring has a structural risk that liquid resin may leak from the rear end of the cylinder body due to the screw's forward and backward movement within the cylinder. Furthermore, the leaked liquid resin may solidify due to factors such as rising temperatures, requiring considerable effort to remove. Other issues and new features become clear from the description in this specification and the accompanying drawings.

[0005] In one embodiment of the injection molding machine, a cover with a through hole for inserting the root of a screw is fitted at the rear end of the cylinder. A groove is formed at the center of the front surface of the cover that abuts against the rear end face of the cylinder. A U-shaped gasket is provided in the groove such that its inner circumferential surface abuts against the outer circumferential surface of the root of the screw, and its concave side faces the rear end face of the cylinder.

[0006] In one embodiment of the injection molding machine, a discharge port for the liquid resin, extending from the inner circumferential surface to the outer circumferential surface, is formed at the rear end of the cylinder. The injection molding machine further includes: a suction pump connected to the discharge port for suctioning the liquid resin; a torque sensor for detecting the torque of the screw; and a controller for driving the suction pump when the torque detected by the torque sensor exceeds a predetermined threshold.

[0007] According to one embodiment, an injection molding machine capable of suppressing leakage of liquid resin from the rear end of the cylinder can be provided. The above and other objects, features and advantages of this disclosure will be more fully understood from the detailed description and accompanying drawings given below. Attached Figure Description

[0008] Figure 1 This is a schematic cross-sectional view showing the configuration of the injection molding machine according to the first embodiment. Figure 2This is a schematic cross-sectional view showing the configuration of the injection molding machine according to the first embodiment. Figure 3 This is a schematic cross-sectional view showing the configuration of the injection molding machine according to the first embodiment. Figure 4 This is a schematic cross-sectional view showing the configuration of the rear end of the cylinder 11 of the comparative example injection molding machine. Figure 5 This is a schematic cross-sectional view showing in more detail the configuration of the rear end of the cylinder 11 of the injection molding machine according to the first embodiment. Figure 6 This is a YZ planar schematic diagram showing the structure of the cover 15 in more detail. Figure 7 This is a schematic cross-sectional view showing in more detail the configuration of the rear end of the cylinder 11 of the injection molding machine, a modified example of the first embodiment. Figure 8 This is a schematic cross-sectional view showing the configuration of the injection molding machine according to the second embodiment. Figure 9 This is a chart illustrating an example of the relationship between the number of days elapsed and the screw torque. Detailed Implementation

[0009] The following is a reference to the appendix. Figure 1 The specific embodiments will be described in detail below. However, the description is not limited to the embodiments described below. In addition, for the sake of clarity, the following description and drawings have been appropriately simplified.

[0010] (First Implementation) <Composition of an Injection Molding Machine> First, refer to Figures 1 to 3 The structure of the injection molding machine according to the first embodiment will be explained. Figures 1 to 3 This is a schematic cross-sectional view showing the configuration of the injection molding machine according to the first embodiment. also, Figures 1 to 3 The right-handed XYZ orthogonal coordinate system shown is a convenient method for illustrating the positional relationships of constituent elements. Typically, the positive Z-axis points vertically upwards, and the XY plane is horizontal; this is common across the attached diagrams.

[0011] like Figures 1 to 3 As shown, the injection molding machine 10 of this embodiment includes an injection unit 1, a fixed mold D1, and a movable mold D2. Here, the injection unit 1 includes a cylinder 11, a screw 12, a static mixer 13, a cooler 14, and a cover 15.

[0012] Figure 1 This indicates the state of liquid resin 82 being injected into the cavity C of the mold (fixed mold D1 and movable mold D2) in the injection molding machine. Figure 2This indicates that the liquid resin 82 has been injected into the mold cavity C in the injection molding machine. Figure 3 This indicates the appearance of resin molded part 83 being removed from the mold in the injection molding machine.

[0013] First, let's describe injection molding machine 1. like Figures 1 to 3 As shown, the cylinder body 11 is a cylindrical component extending along the X-axis. The front end of the cylinder body 11 (the end on the negative X-axis side) gradually tapers towards the front end, forming a nozzle shape. In the example shown, the frontmost end of the cylinder body 11 is inserted into a through hole provided on the fixed mold D1.

[0014] The screw 12 extends along the X-axis and is rotatably and retractably housed within the cylinder 11. For example... Figures 1 to 3 As shown, the root (end on the positive X-axis side) 12a of the screw 12 is connected to a metering motor M1 that rotates the screw 12 and an injection motor M2 that moves the screw 12 axially (X-axis direction) for injecting liquid resin 82.

[0015] More in detail, such as Figures 1 to 3 As shown, a pulley P11 is inserted into and fixed at the root 12a of the screw 12 that protrudes from the cylinder 11. The pulley P12, which is fixed to the rotating shaft of the metering motor M1, is connected to the pulley P11, which is fixed to the screw 12, via the belt B1. Therefore, if the metering motor M1 rotates, the screw 12 will also rotate. Alternatively, a power transmission mechanism such as gears can be used instead of belt B1.

[0016] On the other hand, such as Figures 1 to 3 As shown, the root 12a of the screw 12 is rotatably fixed to the connecting plate CP, which has the YZ plane as its main surface, at a position on the root side compared to the pulley P11. A nut NT that engages with the ball screw BS is fixed to the upper part of the connecting plate CP. A pulley P21 is fixed to the end of the ball screw BS in the positive X-axis direction, which extends along the X-axis.

[0017] A pulley P22 fixed to the rotating shaft of the injection motor M2 is connected via belt B2 to a pulley P21 fixed to the ball screw BS. Therefore, the ball screw BS rotates due to the rotation of the injection motor M2. When the ball screw BS rotates, the screw 12 and the connecting plate CP with the nut NT fixed to it move together in the negative X-axis direction, and liquid resin 82 is injected from the nozzle at the front end of the cylinder 11 into the molds (fixed mold D1 and movable mold D2). Conversely, if the ball screw BS rotates in the opposite direction, the screw 12 retracts in the positive X-axis direction.

[0018] Alternatively, a power transmission mechanism such as gears can be used instead of belt B2. Furthermore, the rotational and retracting movements of screw 12 are controlled, for example, by a controller (not shown). Moreover, the mechanism for moving screw 12 forward and backward is not limited to a ball screw; other direct-acting mechanisms can also be used.

[0019] Static mixer 13 is used to mix as Figures 1 to 3 The cylindrical component shown is a mixture of the main agent (first liquid) 81a and the curing agent (second liquid) 81b of the raw materials of the liquid resin 82 in a specified ratio. The static mixer 13 does not require power. The main agent 81a and the curing agent 81b, which are injected into the static mixer 13 at a specified pressure, pass through the static mixer 13 and are thus uniformly mixed.

[0020] like Figures 1 to 3 As shown, the static mixer 13 is located on the upper side of the positive X-axis end of the cylinder body 11. The main agent 81a and the curing agent 81b, after being mixed by passing through the static mixer 13, are supplied to the cylinder body 11 as liquid resin 82.

[0021] In addition, liquid resin 82 is a thermosetting liquid resin, such as silicone resin. Figures 1 to 3 The liquid resin 82 shown is a two-component mixture of main agent 81a and curing agent 81b, but liquid resin 82 can also be a single-component mixture. In the case of liquid resin 82 being a single-component mixture, static mixer 13 is not required.

[0022] Cooler 14 cools cylinder 11 in a manner that prevents the thermosetting liquid resin 82 from curing within cylinder 11. There are no particular limitations, but... Figures 1 to 3 The cooler 14 shown is, for example, a water-cooled jacket in which cooling water flows internally, and is provided to extend along the long side (X-axis direction) of the cylinder 11 in such a way that it covers the outer peripheral surface of the cylinder 11.

[0023] Figures 1 to 3 In the example shown, the cooler 14 is located on the front end side (negative X-axis direction side) compared to the static mixer 13. The cooler 14 is controlled, for example, by a controller (not shown), to maintain the cylinder 11 at a specified temperature below. As an example, when the liquid resin 82 is silicone resin, the cylinder 11 is maintained at a temperature below 25°C.

[0024] In the injection molding machine 10 of this embodiment, the liquid resin 82 supplied from the static mixer 13 is cooled by the cooler 14 inside the cylinder 11, while being mixed by the rotating screw 12.

[0025] like Figures 1 to 3 As shown, the cover portion 15 has a through hole for the root portion 12a of the screw 12 to be inserted, and fits into the rear end of the cylinder body 11. In the injection molding machine 10 of this embodiment, the cover portion 15 is provided in order to suppress the leakage of liquid resin 82 from the rear end of the cylinder body 11. The detailed structure of the cover 15 will then be explained.

[0026] The fixed mold D1 is a mold fixed to the front end of the injection molding machine 1. On the other hand, the movable mold D2 is a mold driven by a drive source (not shown) and capable of sliding in the X-axis direction. First, the movable mold D2 moves in the positive X-axis direction and comes into contact with the fixed mold D1. Thus, as... Figure 1 As shown, a resin molded article 83 (see reference) is formed between the fixed mold D1 and the movable mold D2. Figure 3 The shape of the cavity C corresponds to the shape of the movable mold D2. The forward and backward movements of such a movable mold D2 are controlled, for example, by a controller not shown.

[0027] Next, as Figure 2 As shown, the screw 12 is moved forward in the negative X-axis direction, filling the interior of the mold (fixed mold D1 and movable mold D2), that is, the cavity C, with liquid resin 82. The liquid resin 82 is heated and cured in the cavity C, forming the resin molded article 83. Then, as Figure 3 As shown, the screw 12 retracts in the positive X-axis direction while metering liquid resin 82, and moves the movable mold D2 in the negative X-axis direction, thereby removing the resin molded article 83 by demolding it from the fixed mold D1.

[0028] <Composition of a comparative injection molding machine> Here, refer to Figure 4 This describes the configuration of the injection molding machine used in the comparative example. Figure 4 This is a schematic cross-sectional view showing the configuration of the rear end of the cylinder 11 of the comparative example injection molding machine. like Figure 4 As shown, in the comparative injection molding machine, no [feature / equipment] is provided at the rear end of the cylinder 11. Figures 1 to 3 The cover 15 shown.

[0029] On the other hand, such as Figure 4 As shown, in the comparative example injection molding machine, an annular groove 12c is formed on the outer peripheral surface of the root 12a of the screw 12, and a sealing ring SR is embedded in the annular groove 12c. The sealing ring SR seals the root 12a of the screw 12 with the rear end of the cylinder 11.

[0030] However, for example Figure 4 As shown, when the screw 12 retracts, causing the liquid resin 82 to flow from the gap between the root 12a of the screw 12 and the cylinder 11 in the positive X-axis direction, the liquid resin 82 will pass over the sealing ring SR and leak out from the rear end of the cylinder 11.

[0031] <Detailed Composition of Cover 15> Next, refer to Figure 5 as well as Figure 6 This explains the detailed structure of the cover 15. Figure 5 This is a schematic cross-sectional view showing in more detail the configuration of the rear end portion of the cylinder 11 of the injection molding machine according to the first embodiment. Figure 5 Is with Figure 4 The corresponding diagram. Figure 6 This is a YZ planar schematic diagram showing the structure of the cover 15 in more detail.

[0032] like Figure 5 as well as Figure 6 As shown, the cover portion 15 has a flange portion 15a, a main body portion 15b, and a recess 15c. The flange portion 15a is a portion that protrudes outward in the radial direction from the rear end side (the positive X-axis direction side). The main body portion 15b is embedded in a recess formed in the rear end portion of the cylinder body 11.

[0033] A recess 15c is formed in the center (corner on the inner circumferential side) of the front surface of the main body 15b, which abuts against the rear end face of the cylinder 11. A U-shaped gasket UP1 is provided in the recess 15c. Here, the U-shaped gasket UP1 is, for example, a sealing member made of resin (including synthetic rubber).

[0034] U-shaped pad UP1 has the following characteristics: Figure 5 The cross-section shown is U-shaped and as... Figure 6 The shape shown is ring-shaped when viewed from above in the YZ plane. Furthermore, as... Figure 5 As shown, the inner circumferential surface of the U-shaped gasket UP1 abuts against the outer circumferential surface of the root 12a of the screw 12, and the concave side of the U-shaped gasket UP1 is opposite to the rear end face of the cylinder 11.

[0035] Alternatively, a plate-shaped spring component may be provided on the concave side of the U-shaped pad UP1 to allow the concave portion of the U-shaped pad UP1 to expand in the radial direction. in addition, Figure 6 This is a top view, but for ease of understanding, the U-shaped pad UP1 is represented by shading.

[0036] Here, as Figure 5 As shown, when the screw 12 retracts, causing the liquid resin 82 to flow from the gap between the root 12a of the screw 12 and the cylinder 11 in the positive X-axis direction, the concave portion of the U-shaped gasket UP1 in the radial direction ( Figure 5 It extends along the Z-axis direction. Therefore, by blocking the liquid resin 82 with the U-shaped gasket UP1, leakage of liquid resin 82 from the rear end of the cylinder 11 can be suppressed.

[0037] As described above, in the injection molding machine 10 of this embodiment, a cover portion 15 with a through hole for inserting the root portion 12a of the screw 12 is fitted at the rear end of the cylinder body 11. A recess 15c is formed at the center of the front surface of the cover portion 15 that abuts against the rear end face of the cylinder body 11. Furthermore, a U-shaped gasket UP1 is provided in the recess 15c such that its inner circumferential surface abuts against the outer circumferential surface of the root portion 12a of the screw 12, and its concave side faces the rear end face of the cylinder body 11.

[0038] With this configuration, the injection molding machine 10 of this embodiment can suppress the leakage of liquid resin 82 from the rear end of the cylinder 11. Furthermore, the injection molding machine 10 of this embodiment can also be used with... Figure 4 The comparative example shown also has an annular groove 12c and a sealing ring SR.

[0039] <Modified Injection Molding Machine> Next, refer to Figure 7 The configuration of the injection molding machine of the modified example of the first embodiment will be explained. Figure 7 This is a schematic cross-sectional view showing in more detail the configuration of the rear end of the cylinder 11 of the injection molding machine, a modified example of the first embodiment. Figure 7 Is with Figure 5 The corresponding diagram.

[0040] like Figure 7 As shown, in the modified injection molding machine 10, an annular groove 15d is formed on the inner circumferential surface of the cover portion 15, and a U-shaped gasket UP2 is also provided in the annular groove 15d. That is, in the modified injection molding machine 10, the cover portion 15, in addition to having a U-shaped gasket (first U-shaped gasket) UP1 provided in the sink 15c, also has a U-shaped gasket (second U-shaped gasket) UP2 provided in the annular groove 15d.

[0041] The U-shaped gasket UP2 is configured such that its inner circumferential surface abuts against the outer circumferential surface of the root 12a of the screw 12, and the concave side of the U-shaped gasket UP2 faces the rear end face of the cylinder body 11. Thus, in the cover portion 15, not only is the U-shaped gasket UP1 provided in the recess 15c, but the U-shaped gasket UP2 is also provided in the annular groove 15d, thereby further suppressing the leakage of liquid resin 82 from the rear end of the cylinder body 11.

[0042] Other components and Figure 5 The injection molding machine 10 of the first embodiment shown is similar, so the description is omitted. Alternatively, multiple annular grooves 15d can be formed on the inner circumferential surface of the cover 15, and U-shaped gaskets UP2 can be provided in each annular groove 15d.

[0043] (Second Implementation) Next, refer to Figure 8 The configuration of the injection molding machine according to the second embodiment will be explained. Figure 8 This is a schematic cross-sectional view showing the configuration of the injection molding machine according to the second embodiment. (e.g.) Figure 8 As shown, the injection molding machine of this embodiment is in Figures 1 to 3 Based on the injection molding machine 1, fixed mold D1, and movable mold D2 shown, it also has a control valve CV, a suction pump P, a discharge box DT, and a controller CNT.

[0044] like Figure 8 As shown, the suction pump P is connected to a discharge port formed at the rear end of the cylinder 11 via a control valve CV. More specifically, the discharge port is a hole provided in the lower side of the rear end of the cylinder 11, extending vertically from the inner circumferential surface to the outer circumferential surface, to discharge the liquid resin 82 retained in the gap between the root 12a of the screw 12 and the cylinder 11. In other words, the suction pump P draws in the liquid resin 82 retained in the gap between the root 12a of the screw 12 and the cylinder 11 and discharges it.

[0045] in addition, Figure 8 The metering motor M1 shown has a torque sensor (not shown) that detects the torque of the screw 12 connected to the metering motor M1. Figure 8 The controller CNT shown controls the control valve CV and the suction pump P based on the torque of the screw 12 detected by the torque sensor of the metering motor M1.

[0046] Here, Figure 9 This is a graph illustrating an example of the relationship between the number of days elapsed and the screw torque. For example, the viscosity of the liquid resin 82 remaining in the gap between the root 12a of the screw 12 and the cylinder 11 increases depending on the number of days elapsed (i.e., the passage of time) and environmental changes (especially rising temperatures). As a result, the torque of the screw 12 increases, for example, the mixing of the liquid resin 82 by the screw 12 becomes insufficient, and the output of resin molded products decreases.

[0047] The controller CNT measures the torque of the screw 12 as detected by the torque sensor on the metering motor M1. Figure 9 If the viscosity exceeds the specified threshold, the suction pump P is driven and the control valve CV is opened. The liquid resin 82 that has accumulated in the gap between the root 12a of the screw 12 and the cylinder 11 and whose viscosity has increased is discharged into the discharge box DT by the drive of the suction pump P.

[0048] As a result, the stagnant and viscous liquid resin 82 in the gap between the root 12a of the screw 12 and the cylinder 11 is replaced with fresh liquid resin 82, and the torque of the screw 12 returns to below the threshold. This results in the ability to suppress the decrease in resin-molded product output that occurs with the increase in the torque of the screw 12.

[0049] Furthermore, there are no specific limitations, but for example... Figure 8 As shown, when the screw 12 retracts and the movable mold D2 is demolded from the fixed mold D1 and the resin molded article 83 is removed, the liquid resin 82 is discharged.

[0050] Other components and Figures 1 to 3 The injection molding machine 10 of the first embodiment shown is similar, so the description is omitted. In addition, this embodiment can also be made similar to Figure 7 The first embodiment shown is a modified combination.

[0051] As described above, in the injection molding machine 10 of this embodiment, similarly to the first embodiment, a cover portion 15 with a through hole for inserting the root portion 12a of the screw 12 is fitted at the rear end of the cylinder body 11. A recess 15c is formed at the center of the front surface of the cover portion 15 that abuts against the rear end face of the cylinder body 11. Furthermore, a U-shaped gasket UP1 is provided in this recess 15c. With this configuration, the injection molding machine 10 of this embodiment can also suppress the leakage of liquid resin 82 from the rear end of the cylinder body 11.

[0052] Furthermore, in the injection molding machine 10 of this embodiment, a discharge hole for liquid resin 82 extending from the inner circumferential surface to the outer circumferential surface is formed at the rear end of the cylinder 11. The injection molding machine 10 of this embodiment also includes a suction pump P connected to the discharge hole and drawing in the liquid resin 82, a torque sensor for detecting the torque of the screw 12, and a controller CNT. Here, the controller CNT drives the suction pump P when the torque detected by the torque sensor exceeds a predetermined threshold.

[0053] With this configuration, in the injection molding machine 10 of this embodiment, the stagnant and viscous liquid resin 82 in the gap between the root 12a of the screw 12 and the cylinder 11 is replaced with fresh liquid resin 82, and the torque of the screw 12 returns to below a threshold value. As a result, the reduction in the output of resin molded articles that accompanies the increase in the torque of the screw 12 can be suppressed.

[0054] Based on the above disclosure, it is obvious that the embodiments of this disclosure can be modified in various ways. These modifications should not be considered a departure from the spirit and scope of this disclosure, and all such modifications are, of course, included within the scope of the technical solution for those skilled in the art.

Claims

1. An injection molding machine, wherein, include: The cylinder body is used for injecting thermosetting liquid resin as raw material. A screw that can be retracted and accommodated within the cylinder body; as well as The mold is advanced by the screw, and the liquid resin inside the cylinder is injected into the mold. A cover is fitted at the rear end of the cylinder body, and the cover has a through hole for the root of the screw to be inserted. A groove is formed at the center of the front surface of the cover that abuts against the rear end face of the cylinder. In the settling groove, a U-shaped gasket is provided such that the inner circumferential surface abuts against the outer circumferential surface of the root of the screw, and the concave side faces the rear end face of the cylinder body.

2. The injection molding machine according to claim 1, wherein, The U-shaped pad is the first U-shaped pad. An annular groove is formed on the inner circumferential surface of the through hole in the cover. A second U-shaped gasket is provided in the annular groove such that the inner circumferential surface abuts against the outer circumferential surface of the root of the screw, and the concave side faces the rear end face of the cylinder.

3. The injection molding machine according to claim 1 or 2, wherein, The liquid resin is a silicone resin.

4. The injection molding machine according to claim 3, wherein, The liquid resin is a two-component liquid resin formed by mixing a second liquid containing a curing agent in a specified ratio with a first liquid containing a main agent.

5. An injection molding machine, wherein, include: The cylinder body is used for injecting thermosetting liquid resin as raw material. A screw that can be retracted and accommodated within the cylinder body; as well as The mold is advanced by the screw, and the liquid resin inside the cylinder is injected into the mold. A cover is fitted at the rear end of the cylinder body, and the cover has a through hole for the root of the screw to be inserted. A recessed groove is formed at the center of the front surface of the cover that abuts against the rear end face of the cylinder body, and a gasket is provided in the recessed groove. A discharge hole for the liquid resin is formed at the rear end of the cylinder, extending from the inner circumferential surface to the outer circumferential surface. The injection molding machine also includes: A suction pump, connected to the discharge port, is used to draw in the liquid resin. A torque sensor that detects the torque of the screw; and The controller drives the suction pump when the torque detected by the torque sensor exceeds a predetermined threshold.

6. The injection molding machine according to claim 5, wherein, The gasket is a U-shaped gasket, which is positioned in the sinker such that its inner circumferential surface abuts against the outer circumferential surface of the root of the screw and its concave side faces the rear end face of the cylinder.

7. The injection molding machine according to claim 6, wherein, The U-shaped pad is the first U-shaped pad. An annular groove is formed on the inner circumferential surface of the through hole in the cover. A second U-shaped gasket is provided in the annular groove such that the inner circumferential surface abuts against the outer circumferential surface of the root of the screw, and the concave side faces the rear end face of the cylinder.

8. The injection molding machine according to any one of claims 5 to 7, wherein, The liquid resin is a silicone resin.

9. The injection molding machine according to claim 8, wherein, The liquid resin is a two-component liquid resin formed by mixing a second liquid containing a curing agent in a specified ratio with a first liquid containing a main agent.

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