Injection nozzle, injection device, and injection molding machine

Abstract

To provide an injection nozzle capable of accurately controlling a resin temperature.SOLUTION: An injection nozzle (25) is attached to a tip end of a heating cylinder (19), and has an in-nozzle channel (28) formed therein. In the present disclosure, the injection nozzle (25) is pressed against the heating cylinder (19) by a nozzle pressing member (31) fixed to an end surface at the tip end of the heating cylinder (19), to be attached. Then, concerning the injection nozzle (25), a sensor hole (38) is opened in an outer peripheral surface (33) that contacts the nozzle pressing member (31), to allow temperature measuring means (36) to be inserted.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an injection nozzle provided in an injection molding machine, an injection device equipped with the injection nozzle, and an injection molding machine. [Background technology]

[0002] The injection nozzle is provided at the tip of the heating cylinder, and its tip touches the mold to inject molten resin. As described in Patent Document 1, for example, a shut-off nozzle may be configured from an injection nozzle and a needle valve provided at an angle to the injection nozzle. The shut-off nozzle can open and close an internal nozzle flow path formed within the injection nozzle by moving the needle valve back and forth. The shut-off nozzle can prevent resin leakage, or so-called dripping, when the tip of the injection nozzle is separated from the mold. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 1-176533 Summary of the Invention [Problem to be solved by the invention]

[0004] The heating cylinder is divided into multiple zones in the longitudinal direction, and multiple heaters are provided corresponding to each zone. The heating cylinder also has multiple holes drilled from the outer surface, each equipped with a temperature sensor so that the resin temperature can be measured. Therefore, the temperature can be controlled so that the resin reaches the desired temperature in each zone.

[0005] The injection nozzle is also equipped with a heater and a temperature sensor. However, the temperature sensor is located relatively close to the tip of the injection nozzle. Therefore, although it is possible to control the temperature at the injection nozzle, the control is limited to the tip. On the other hand, since the rear end of the injection nozzle is attached to a heating cylinder, controlling the temperature of the heating cylinder should also appropriately control the temperature of the injection nozzle. However, in reality, there is a problem of temperature drop near the rear end of the injection nozzle. This reduces the fluidity of the resin, causing pressure loss during injection and potentially resulting in voids in the molded product. This problem is particularly likely to occur with shut-off nozzles, where it is difficult to install a heater near the rear end of the injection nozzle.

[0006] The present disclosure provides an injection nozzle capable of controlling resin temperature with high precision, an injection device equipped with such an injection nozzle, and an injection molding machine.

[0007] Other objects and novel features will become apparent from the description of this specification and the accompanying drawings. [Means for solving the problem]

[0008] The injection nozzle is attached to the tip of the heating cylinder, and an internal nozzle flow path is formed inside. In the present disclosure, the injection nozzle is attached by being pressed against the heating cylinder by a nozzle pressing member fixed to the end face of the tip of the heating cylinder. Then, a sensor hole is formed on the outer peripheral surface of the injection nozzle that contacts the nozzle pressing member. The nozzle holder has through holes. Open it, The rotational position relative to the heating cylinder is adjusted so that the sensor hole and the through-hole are aligned, and the nozzle is fixed with a nozzle pressing member. Insert a temperature measuring means. [Effects of the Invention]

[0009] The present disclosure allows for accurate control of resin temperature at the injection nozzle. [Brief explanation of the drawings]

[0010] [Figure 1]1 is a front view showing an injection molding machine according to an embodiment of the present invention; [Figure 2] 1 is a front cross-sectional view showing a shut-off nozzle and a part of an injection device according to the present embodiment. FIG. [Figure 3] FIG. 1 is a front cross-sectional view showing a conventional injection nozzle and part of an injection device. [Figure 4] FIG. 10 is a front cross-sectional view showing a part of an injection nozzle and an injection device according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Specific embodiments will be described in detail below with reference to the drawings. However, the present invention is not limited to the following embodiments. For clarity of explanation, the following description and drawings have been simplified as appropriate. In each drawing, the same elements are given the same reference numerals, and duplicate explanations are omitted as necessary. Furthermore, hatching has been omitted in some areas to avoid cluttering the drawings.

[0012] The present embodiment will be described. <Injection molding machine> 1, an injection molding machine 1 according to this embodiment includes a toggle-type mold clamping unit 2 and an injection unit 3. The injection unit 3 according to this embodiment is provided with a shut-off nozzle 5 according to this embodiment, which will be described in detail later.

[0013] <Mold clamping device> The mold clamping unit 2 includes a fixed platen 7 fixed to a bed B, a movable platen 8 slidably provided on the bed B, and a mold clamping housing 9. The fixed platen 7 and the mold clamping housing 9 are connected by a plurality of tie bars 11, 11, ..., and the movable platen 8 is slidably provided between the fixed platen 7 and the mold clamping housing 9. A mold clamping mechanism, which is a toggle mechanism 13 in this embodiment, is provided between the mold clamping housing 9 and the movable platen 8. A fixed-side mold 15 and a movable-side mold 16 are provided on the fixed platen 7 and the movable platen 8, respectively. Therefore, when the toggle mechanism 13 is driven, the molds 15 and 16 are opened and closed.

[0014] <Injection device> The injection device 3 includes a heating cylinder 19, a screw 20 provided in the heating cylinder 19, and a screw drive device 22. The heating cylinder 19 is supported by the screw drive device 22, and the screw 20 is driven in the rotational direction and the axial direction by the screw drive device 22. The heating cylinder 19 is provided with a hopper 23 and a shut-off nozzle 5 according to the present embodiment, which will be described next. Resin is supplied from the hopper 23, the heating cylinder 19 is heated, and the screw 20 is rotated by the screw drive device 22, whereby the resin is melted and metered. When the screw 20 is driven in the axial direction by the screw drive device 22, the resin can be injected into the molds 15, 16.

[0015] <Shut-off nozzle according to this embodiment> As shown in FIG. 2, the shut-off nozzle 5 according to this embodiment includes an injection nozzle 25 and a needle valve 26. The injection nozzle 25 according to this embodiment has several features that are different from those of conventional injection nozzles, and these features will be described in detail below. However, some features are similar to those of conventional shut-off nozzles. Specifically, an internal nozzle flow path 28 through which resin flows is formed inside the injection nozzle 25. A needle hole 29 is formed from the outer periphery of the injection nozzle 25 and reaches the internal nozzle flow path 28. The needle valve 26 is inserted into the needle hole 29 and is driven by a drive mechanism (not shown). Therefore, moving the needle valve 26 back and forth opens and closes the internal nozzle flow path 28.

[0016] In this way, in the shut-off nozzle 5 according to this embodiment, the needle valve 26 is externally connected to the injection nozzle 25. fromBecause an inserted type is employed, there are few structures that would interfere with providing a heater around injection nozzle 25. The heater will be explained later, but it can be appropriately disposed around injection nozzle 25, etc. In other words, although shut-off nozzle 5 according to this embodiment is equipped with a shut-off valve, it is a type that places few restrictions on providing a heater.

[0017] <Injection nozzle> The injection nozzle 25 according to this embodiment is characterized by the method of attachment to the heating cylinder 19, which is achieved by a nozzle retaining member 31, as shown in FIG. 2. The injection nozzle 25 has a distinctive structure formed on its upstream side, i.e., its rear end, so that it can be attached by the nozzle retaining member 31. Specifically, it has an enlarged flange 32, and the outer circumferential surface 33 of this flange 32 is a smooth cylindrical surface. In other words, the outer circumferential surface 33 is not formed with a male thread. The nozzle retaining member 31 has a step 35, and the flange 32 is housed in this step 35. The nozzle retaining member 31 is fastened to the heating cylinder 19 by a plurality of bolts 30, 30, ..., thereby pressing the injection nozzle 25 against the heating cylinder 19.

[0018] Because the injection nozzle 25 is attached to the heating cylinder 19 in this manner, the injection nozzle 25 can be adjusted to a desired rotational position and fixed to the heating cylinder 19. Because the rotational position can be adjusted, a temperature measurement means, i.e., a rear-end temperature sensor 36, can be provided at the rear end of the injection nozzle 25. That is, a sensor hole 38 is bored in the injection nozzle 25 at a predetermined depth from the outer peripheral surface 33 of the flange portion 32. A through-hole 39 is also bored in the nozzle presser member 31. The rotational position is adjusted so that the through-hole 39 and the sensor hole 38 are aligned, and the injection nozzle 25 is attached to the heating cylinder 19, and the rear-end temperature sensor 36 is inserted.

[0019] The rear end temperature sensor 36 is designed to measure the temperature of the rear end of the injection nozzle 25, but it actually measures the temperature of the resin flowing inside the nozzle flow path 28. The cross-sectional area of ​​the nozzle flow path 28 changes at several points in the flow direction, and as indicated by the reference numeral 40, the rear end temperature sensor 36 is located near the point where the rate of decrease in the cross-sectional area of ​​the flow path is greatest. In other words, it is designed to measure the resin temperature at the point indicated by the reference numeral 40. When the resin flows, the temperature is more likely to rise at points where the cross-sectional area of ​​the flow path decreases significantly than at other points. Being able to measure the temperature near the reference numeral 40 makes it possible to control the resin temperature with high precision.

[0020] One of the features of the injection nozzle 25 according to this embodiment is that it is formed from a single member. In other words, it is not assembled from multiple members. Therefore, the internal nozzle flow path 28 is smoothly formed, preventing the flow of resin from being disturbed. Another feature of the injection nozzle 25 according to this embodiment is that the nose portion 41 is longer than that of conventional injection nozzles. Specifically, the ratio L / D of the length L of the nose portion 41 to the diameter D of the nose portion 41 is 4.0 or greater. This is also a structure for regulating the flow of resin in the internal nozzle flow path 28. As such, the injection nozzle 25 according to this embodiment has a structure that allows the resin to flow smoothly, so pressure loss during injection is small. Therefore, the occurrence of voids can be prevented.

[0021] First and second nose temperature sensors 43, 44 are embedded in the nose 41 of the injection nozzle 25. These sensors enable measurement of the resin temperature near the tip and in the center of the injection nozzle 25.

[0022] <Heater> The injection device 3 according to this embodiment is provided with heaters 45, 46, ... as follows: First, a heating cylinder heater 45 is provided on the outer peripheral surface of the heating cylinder 19. Although only one heating cylinder heater 45 is shown in Fig. 2, a plurality of heating cylinder heaters 45 are provided along the length of the heating cylinder 19.

[0023] Next, a nozzle holder heater 46 is provided on the outer peripheral surface of the nozzle holder member 31. The nozzle holder heater 46 is independent of the heating cylinder heater 45 and heats only the nozzle holder member 31. The rear end of the injection nozzle 25 is heated by heat conduction from the nozzle holder member 31, but because they are separate components, the temperature of the rear end of the injection nozzle 25 tends to be low. In other words, the area near the rear end of the injection nozzle 25 is prone to heat dissipation, and it is likely that the resin temperature will drop, its viscosity will increase, and pressure loss will occur during injection. However, in this embodiment, as described above, the rear end temperature sensor 36 can directly measure the temperature of the rear end of the injection nozzle 25, and the nozzle holder heater 46 can heat the nozzle holder member 31 independently of the heating cylinder 19. Therefore, the temperature of the rear end of the injection nozzle 25 can be accurately controlled to the desired temperature.

[0024] The nose 41 of the injection nozzle 25 is provided with first to third nose heaters 47, 48, 49. The injection nozzle 25 according to the embodiment is thus provided with a plurality of temperature sensors 36, 43, 44 as well as a plurality of heaters 46, 47, ..., and therefore is able to accurately control the resin temperature in the nozzle flow path 28. This makes it less likely that a decrease in fluidity caused by a drop in resin temperature and the accompanying loss of resin pressure will occur. In other words, it is possible to suppress the occurrence of voids.

[0025] <Conventional shut-off nozzle> For comparison with the shut-off nozzle 5 according to this embodiment, a conventional injection nozzle 60 shown in FIG. 3 will be described. The injection nozzle 60 is composed of an injection nozzle main body 61 and a nozzle tip 62. The injection nozzle main body 61 has a male thread 64 formed at its upstream rear end. The heating cylinder 19 has a female thread 66 formed at its tip, and the male thread 64 is threadedly engaged with this female thread 66 to attach the injection nozzle main body 61. The injection nozzle main body 61 has a female thread 67 formed at its tip, and the nozzle tip 62 has a male thread 68 formed at its rear end. The nozzle tip 62 is attached to the injection nozzle main body 61 by threading the male thread 68 into the female thread 67.

[0026] First and second intra-nozzle flow paths 70, 71 are formed in the nozzle tip 62 and the injection nozzle main body 61, respectively, and these are continuous. In order to heat the resin flowing through the first and second intra-nozzle flow paths 70, 71, first and second nozzle heaters 74, 75 and first and second temperature sensors 77, 78 are provided in the nose 73 of the injection nozzle 60. A heating cylinder heater 45 is provided in the heating cylinder 19, which heats the heating cylinder 19 and indirectly heats the rear end of the injection nozzle 60.

[0027] The conventional injection nozzle 60 does not have a temperature sensor at its rear end. Therefore, the resin temperature near the rear end cannot be measured, and the temperature cannot be controlled accurately. Furthermore, the rear end of the injection nozzle 60 is heated by heat conduction from the heating cylinder 19. However, because the injection nozzle main body 61 and the heating cylinder 19 are made of separate components, the temperature of the injection nozzle main body 61 is unlikely to rise. Therefore, the resin temperature in the second nozzle flow passage 71 is likely to drop. Furthermore, because the conventional injection nozzle 60 is made of two components, the injection nozzle main body 61 and the nozzle tip 62, a joint 80 is formed between the first and second nozzle flow passages 70, 71. The joint 80 disrupts the resin flow and causes pressure loss during injection. As already explained, the injection nozzle 25 of the shut-off nozzle 5 (see FIG. 2) according to this embodiment solves these problems.

[0028] <Injection nozzle according to the second embodiment> This embodiment can be modified in various ways. For example, it can be applied to an injection nozzle without a shutoff valve. FIG. 4 shows an injection device 3A according to a second embodiment, equipped with an injection nozzle 25A according to the second embodiment. Components similar to those in the first embodiment are designated by the same reference numerals and will not be described again. The injection nozzle 25A according to the second embodiment also has a rear end temperature sensor 36 at its rear end, which measures the resin temperature at a location in the nozzle internal flow path 28 where the rate of change in the flow path cross-sectional area is high, as indicated by reference numeral 40. The nozzle presser member 31 is also provided with a nozzle presser member heater 46. These features enable appropriate temperature control. Furthermore, because the injection nozzle 25A is formed from a single member, the resin flows smoothly through the nozzle internal flow path 28, eliminating pressure loss.

[0029] In this embodiment, only one heater, i.e., nose heater 47A, and one temperature sensor, i.e., nose temperature sensor 43A, are provided in nose 41. However, the resin temperature in nose 41 can be controlled to be approximately uniform.

[0030] The invention made by the inventor has been specifically described above based on the embodiments, but it goes without saying that the present invention is not limited to the above-described embodiments and various modifications are possible without departing from the spirit of the invention. The multiple examples described above can also be implemented in appropriate combinations. [Explanation of symbols]

[0031] 1 Injection molding machine 2 Mold clamping device 3 Injection unit 5 Shut-off nozzle 7 Fixed plate 8 Movable plate 9. Clamping housing 11. Tie bar 13 Toggle mechanism 15 Fixed side mold 16 Movable mold 19 Heating cylinder 20 Screw 22 Screw drive device 23 Hopper 25 Injection nozzle 26 Needle valve 28 Nozzle internal flow path 29 Needle hole 30 Bolt 31 nozzle holding member 32 flange portion 33 Outer surface 35 Stepped portion 36 Rear end temperature sensor 38 Sensor hole 39 Through hole 41 Nose portion 43, 44 No. 1 and No. 2 nose temperature sensors 45 Heater for heating cylinder 46 Heater for nozzle holding member 47, 48, 49 No. 1 to No. 3 nose heaters

Claims

1. A heating cylinder for melting resin; a screw contained in the heating cylinder; an injection nozzle having an internal nozzle flow path formed therein; a nozzle pressing member fixed to an end surface of the tip of the heating cylinder to attach the injection nozzle to the tip of the heating cylinder, a sensor hole is formed in the outer peripheral surface of the injection nozzle that contacts the nozzle holding member, and a through hole is formed in the nozzle holding member, the injection nozzle is fixed by the nozzle pressing member after its rotational position relative to the heating cylinder is adjusted so that the sensor hole and the through-hole are aligned; The injection device, wherein a temperature measuring means is inserted into the sensor hole through the through hole.

2. 2. The injection device according to claim 1, wherein a heater for the nozzle holding member is provided on the outer periphery of the nozzle holding member.

3. 3. The injection device according to claim 1, wherein the temperature measuring means measures the resin temperature at a portion of the nozzle flow passage where the cross-sectional area of ​​the flow passage is reduced at the highest rate in the flow direction.

4. the injection nozzle is one component of a shut-off nozzle that is composed of the injection nozzle and a needle valve; a needle hole is formed in the injection nozzle from the outer circumferential surface to the nozzle internal flow path; 4. The injection device according to claim 1, wherein the needle hole is inserted into the needle hole so as to be able to move forward and backward, thereby opening and closing the flow path within the nozzle.

5. 5. The injection device according to claim 1, wherein the injection nozzle has a flange portion at an upstream end thereof, the flange portion having an expanded outer diameter, the flange portion being held down by the nozzle holding member, the outer peripheral surface of the flange portion being formed into a smooth cylindrical surface, and the sensor hole being opened in the outer peripheral surface of the flange portion.

6. 6. The injection device according to claim 1, wherein the injection nozzle is formed from a single member, and the nozzle flow path is formed seamlessly.

7. An injection molding machine comprising an injection unit and a mold clamping unit, The injection device includes a heating cylinder for melting the resin; a screw contained in the heating cylinder; an injection nozzle having an internal nozzle flow path formed therein; a nozzle pressing member fixed to an end surface of the tip of the heating cylinder to attach the injection nozzle to the tip of the heating cylinder, a sensor hole is formed in the outer peripheral surface of the injection nozzle that contacts the nozzle holding member, and a through hole is formed in the nozzle holding member, the injection nozzle is fixed by the nozzle pressing member after its rotational position relative to the heating cylinder is adjusted so that the sensor hole and the through-hole are aligned; An injection molding machine, wherein a temperature measuring means is inserted into the sensor hole through the through hole.

8. 8. The injection molding machine according to claim 7, wherein a heater for the nozzle presser member is provided on the outer periphery of the nozzle presser member.

9. 9. The injection molding machine according to claim 7, wherein the temperature measuring means measures the resin temperature at a portion of the nozzle in which the cross-sectional area of ​​the flow passage in the flow direction is reduced at the highest rate.

10. the injection nozzle is one component of a shut-off nozzle that is composed of the injection nozzle and a needle valve; a needle hole is formed in the injection nozzle from the outer circumferential surface to the nozzle internal flow path; 10. The injection molding machine according to claim 7, wherein the needle hole is inserted into the needle hole so as to be able to move back and forth, thereby opening and closing the flow path within the nozzle.

11. 11. The injection molding machine according to claim 7, wherein the injection nozzle has a flange portion formed at an upstream end thereof, the flange portion having an expanded outer diameter, the flange portion being held down by the nozzle holding member, the outer peripheral surface of the flange portion being formed into a smooth cylindrical surface, and the sensor hole being opened in the outer peripheral surface of the flange portion.

12. 12. The injection molding machine according to claim 7, wherein the injection nozzle is formed from a single member, and the nozzle internal flow path is formed seamlessly.

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