Resin intrusion prevention structure into heater, injection device, and injection molding machine

Abstract

To provide a structure for preventing resin intrusion into a heater in a shut-off nozzle.SOLUTION: A shut-off nozzle (5) includes: a nozzle body (25) having an injection flow path (33); and a shut-off valve (26) configured to open and block the injection flow path (33). The nozzle body (25) has a sliding portion for driving the shut-off valve, and a sliding exposed portion (39) is formed therein. A structure (6) for prevention of resin intrusion into heaters is provided in the vicinity of the sliding exposed portion (39), and is configured to prevent the resin leaking from the sliding exposed portion (39) from intruding into a heater (38) provided in the shut-off nozzle (5).SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a structure for preventing resin from entering a heater in a shut-off nozzle, and to an injection device and an injection molding machine equipped with the structure. [Background technology]

[0002] A shut-off nozzle installed in the injection device of an injection molding machine is designed to prevent dripping by opening and closing the injection flow path through the injection nozzle where resin flows. There are various types of shut-off nozzles, such as the type described in Patent Document 1. This type of shut-off nozzle consists of a nozzle body and a needle valve installed at an angle to the nozzle body. The nozzle body has an oblique hole, i.e., a needle hole, that extends from its outer periphery to the injection flow path within the nozzle body. A needle valve is inserted into this needle hole so that it can move back and forth. When the needle valve is advanced, the injection flow path is closed, and when it is retracted, the injection flow path is opened. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 3-274125 Summary of the Invention [Problem to be solved by the invention]

[0004] Because the needle valve slides against the needle hole, a small amount of resin may leak from this sliding point. Although the amount of resin leaking from the sliding point is small, the amount of leakage increases over long periods of operation. The leaked resin may flow into the heater installed in the nozzle body. Because the nozzle body is used while inserted into the mold platen, it is not possible to visually check from the outside whether the leaked resin has reached the heater. If the resin reaches the heater, it may cause the heater to malfunction or make it impossible to remove the heater.

[0005] The present disclosure provides a structure for preventing resin from entering the heater in the shut-off nozzle.

[0006] Other objects and novel features will become apparent from the description of this specification and the accompanying drawings. [Means for solving the problem]

[0007] The shut-off nozzle includes a nozzle body having an axial injection flow path through which resin flows, and a shut-off valve that opens and closes the injection flow path. The nozzle body has a sliding exposed portion that is exposed on the outer circumferential surface of the nozzle body and is a sliding portion between the nozzle body and a drive member that drives the shut-off valve. The present disclosure provides a resin intrusion prevention structure for a heater that is provided near the sliding exposed portion and that prevents resin leaking from the sliding exposed portion from infiltrating into a heater provided in the shut-off nozzle. The resin penetration prevention structure is a heater cover that covers the heater. [Effects of the Invention]

[0008] The present disclosure can prevent resin leaking from the sliding exposed portion of the shut-off nozzle from reaching the heater. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a front view showing an injection molding machine according to an embodiment of the present invention; [Figure 2] FIG. 2 is a front cross-sectional view showing a shut-off nozzle and a part of an injection device according to the present embodiment. [Figure 3] 1 is a perspective view showing a resin intrusion prevention structure for a heater according to an embodiment of the present invention; [Figure 4] 4 is a flowchart showing a method for determining the timing of cleaning or replacing the shut-off nozzle according to the present embodiment. [Figure 5A] FIG. 10 is a perspective view showing a resin penetration prevention structure for a heater according to a second embodiment. [Figure 5B] 10 is a front cross-sectional view showing a resin intrusion prevention structure for a heater according to a third embodiment and a part of a shut-off nozzle. FIG. [Figure 5C] FIG. 10 is a side cross-sectional view showing a resin intrusion prevention structure into a heater according to a fourth embodiment and a part of a shut-off nozzle. [Figure 5D] FIG. 10 is a front cross-sectional view showing a part of an injection device, a shut-off nozzle according to another embodiment, and a structure for inhibiting resin from entering a heater according to a fifth embodiment, which is provided on the shut-off nozzle. DETAILED DESCRIPTION OF THE INVENTION

[0010] 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.

[0011] The present embodiment will be described. <Injection molding machine> As shown in FIG. 1, the injection molding machine 1 according to this embodiment is a vertical injection molding machine. The shut-off nozzle 5 and the structure 6 for preventing resin from entering the heater according to this embodiment, which will be described later, are provided, but these can also be employed in horizontal injection molding machines. In other words, the present invention can be implemented with any type of injection molding machine, and the same effects can be achieved with any type of injection molding machine. Below, this embodiment will be described using a vertical injection molding machine.

[0012] 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 is provided with a shut-off nozzle 5 according to this embodiment, and the shut-off nozzle 5 is provided with a resin intrusion prevention structure 6 for preventing resin from entering the heater according to this embodiment. A camera 7 is provided near the shut-off nozzle 5. The injection molding machine 1 is provided with a control device 4, and the mold clamping unit 2, injection unit 3, shut-off nozzle 5, camera 7, etc. are connected to and controlled by the control device 4.

[0013] <Mold clamping device> The mold clamping unit 2 includes a housing 8, a fixed platen 9 fixed to the housing 8, an upper movable platen 11 provided above the fixed platen 9, and a lower movable platen 12 provided below the fixed platen 9. The upper movable platen 11 and the lower movable platen 12 are connected by a plurality of, for example, three tie bars 13, 13, ..., and the fixed platen 9 is penetrated by the tie bars 13, 13, .... A mold clamping mechanism, that is, a toggle mechanism 15 in this embodiment, is provided between the lower movable platen 12 and the fixed platen 9. A lower mold 16 and an upper mold 17 are provided on the fixed platen 9 and the upper movable platen 11, respectively. Therefore, when the toggle mechanism 15 is driven, the molds 16 and 17 are opened and closed.

[0014] <Injection device> The injection unit 3 is supported by the upper movable platen 11 and moves up and down integrally with the upper movable platen 11 when the upper movable platen 11 moves up and down due to mold opening and closing. However, the support structure is not shown in FIG. 1 . The injection unit 3 includes a heating cylinder 18 and a screw 19 provided within the heating cylinder 18. The screw 19 is driven in the rotational and axial directions by a screw drive device (not shown in FIG. 1 ). The heating cylinder 18 is provided with heaters 21, 21, and a shut-off nozzle 5 according to this embodiment, which will be described next, is attached to its tip. When the heating cylinder 18 is heated and resin is supplied to rotate the screw 19, the resin melts and is metered. When the screw 19 is driven in the axial direction, the resin can be injected into the molds 16, 17.

[0015] <Shut-off nozzle according to this embodiment> 2, the shut-off nozzle 5 according to this embodiment is composed of a nozzle body 25, a needle valve 26 which is a shut-off valve, and needle valve drive means 28 which drives the needle valve 26. The nozzle body 25 is attached to the heating cylinder 18 via an adapter 30. The needle valve drive means 28 is supported by a bracket 31 which is fixed to the heating cylinder 18.

[0016] The nozzle body 25 has a flow path through which the resin flows, i.e., an injection flow path 33, formed therein. The injection flow path 33 is formed at the axis of the nozzle body 25. In other words, the injection flow path 33 is formed in the axial direction inside the nozzle body 25. The nozzle body 25 has an oblique hole, i.e., a needle hole 35, formed from its outer peripheral surface to the injection flow path 33. A needle valve 26 is inserted into this needle hole 35 so as to be able to move back and forth.

[0017] The needle valve 26 moves forward and backward by the needle valve drive means 28. When the needle valve 26 moves forward, its head 36 closes the injection flow path 33. In other words, the shut-off nozzle 5 is closed and resin does not flow. On the other hand, when the needle valve 26 moves backward, the head 36 moves backward from the injection flow path 33. In other words, the injection flow path 33 is opened and resin can flow. In this way, the head 36 of the needle valve 26, which is a shut-off valve, serves as the valve body, and the needle valve 26 itself can be said to be a drive member that drives the head 36, which is the valve body.

[0018] The nozzle body 25 is provided with heaters 38, 38, which control the resin in the injection flow path 33 to a desired temperature.

[0019] The needle valve 26 slides relative to the nozzle body 25. That is, the needle hole 35 in the nozzle body 25 is a sliding portion. The portion of this sliding portion that is exposed to the outside is referred to in this specification as the sliding exposed portion 39. Although the gap at the sliding portion is small, some of the resin flowing through the injection flow path 33 may pass through this gap and leak to the outside from the sliding exposed portion 39. Leakage is particularly likely to occur along with the needle valve 26 when it is driven forward or backward. In this embodiment, a resin intrusion prevention structure 6 into the heater according to this embodiment is provided to prevent resin leaking from the sliding exposed portion 39 from infiltrating into the heaters 38, 38. In FIG. 2, the resin intrusion prevention structure 6 into the heater is indicated by a two-dot chain line.

[0020] <Structure to prevent resin from penetrating into the heater> A resin penetration prevention structure 6 for a heater according to a first embodiment of the present invention is shown in Fig. 3. The resin penetration prevention structure 6 for a heater is formed from a metal plate and includes a pair of walls, namely, first and second resin outflow prevention walls 41 and 42, which surround the sliding exposed portion 39 from both sides, and a third resin outflow prevention wall 43 which connects the first and second resin outflow prevention walls 41 and 42. The first to third resin outflow prevention walls 41, 42, and 43 surround the sliding exposed portion 39 from three sides, and their ends are in close contact with the outer circumferential surface of the nozzle body 25.

[0021] The first and second resin outflow prevention walls 41, 42 are provided with outwardly bent fixing portions 46, 47, respectively. The heater resin intrusion inhibiting structure 6 according to the first embodiment is fixed to the nozzle body 25 by a dedicated metal fixing band 48. That is, although not shown in the figure, the fixing band 48 has male screws attached to both ends, and these male screws are connected to the fixing portions 46, 47 and fixed by nuts 49, 49. The third resin outflow prevention wall 43 has a cutout 50 of a predetermined width and length formed in its center, and the needle valve 26 is inserted into this cutout 50.

[0022] As described above, the ends of the first to third resin outflow prevention walls 41, 42, and 43 are in close contact with the outer circumferential surface of the nozzle body 25. Therefore, even if the resin 52 leaks from the sliding exposed portion 39, the resin 52 is blocked by the first to third resin outflow prevention walls 41, 42, and 43. In other words, the resin 52 is prevented from entering the heater 38. This protects the heater 38.

[0023] When the structure 6 for preventing resin from entering the heater is operated for a long time, the amount of resin 52 leaking from the sliding exposed portion 39 increases. In this embodiment, a camera 7 (see FIGS. 1 and 2) is configured to monitor the structure 6 for preventing resin from entering the heater.

[0024] <Method of determining when to clean or replace the shut-off nozzle according to this embodiment> A method for determining when to clean or replace the shut-off nozzle according to this embodiment will be described. The control device 4 (see FIG. 1) executes the process shown in FIG. 4 each time a molding cycle is completed. First, step S01 is executed to use the camera 7 to photograph the structure 6 for preventing resin from entering the heater according to this embodiment. The amount of resin accumulated in the structure 6 for preventing resin from entering the heater is then estimated from the photographed image. There are various methods for estimating the amount of resin, but for example, the control device 4 (FIG. 1) compares an image taken when there was no resin leakage with the current image to find areas where the brightness has changed. The amount of resin is estimated based on the size of the changed areas.

[0025] The control device 4 executes step S02. That is, it determines whether the amount of resin accumulated in the resin intrusion prevention structure 6 to the heater exceeds an allowable value. The allowable value is set in the control device 4, and the amount of resin is compared with this allowable value. If the amount of resin does not exceed the allowable amount, the process proceeds to step S03. On the other hand, if the amount of resin exceeds the allowable amount, the process proceeds to step S04.

[0026] In step S03, the control device 4 checks the number of shots. The number of shots is the cumulative number of injections performed in the injection device 3, and is the cumulative number of molding cycles. If the number of shots does not exceed the allowable number of shots preset in the control device 4, the process is completed. On the other hand, if the number of shots exceeds the allowable number of shots, the process proceeds to step S06. The control device 4 outputs an alarm to prompt the operator to clean the shut-off nozzle 5 and the structure 6 that prevents resin from entering the heater. After the alarm is output, the process is completed. The operator cleans the shut-off nozzle 5 and the structure 6 that prevents resin from entering the heater. After cleaning, the operator resets the number of shots recorded in the control device 4 to zero.

[0027] If it is determined in step S02 that the resin amount exceeds the allowable value, the process proceeds to step S04 as described above. The control device 4 checks whether the number of shots has reached the minimum number of shots. The minimum number of shots is preset in the control device 4. If the number of shots has reached the minimum number of shots in step S04, the process proceeds to step S06. On the other hand, if the number of shots has not reached the minimum number of shots, the control device 4 executes step S05 and outputs an alarm to prompt the operator to consider replacing the shut-off nozzle 5. This is because wear of the shut-off nozzle 5 is suspected. The operator determines whether the shut-off nozzle 5 should be replaced. After the alarm is output, the process proceeds to step S06. The process in step S06 is as already described, and once the operator has performed cleaning, the number of shots recorded in the control device 4 is reset to zero as described above. The process is then completed.

[0028] <Modification of this embodiment> This embodiment can be modified in various ways. FIG. 5A shows a heater resin intrusion prevention structure 6A according to a second embodiment. In this embodiment, the heater resin intrusion prevention structure 6A is composed of a main body 54 and a lid 55. The main body 54 has a slightly different shape from the heater resin intrusion prevention structure 6A according to the first embodiment, and the heights of the first to third resin outflow prevention walls 41A, 42A, and 43A are slightly higher. This allows for a relatively large amount of resin 52 to be stored. The main body 54 also includes a fourth resin outflow prevention wall 56 connecting the first and second resin outflow prevention walls 41A and 42A. The lid 55 completely closes the opening formed by the first to fourth resin outflow prevention walls 41A, 42A, 43A, and 56. In other words, the heater resin intrusion prevention structure 6A essentially completely covers the sliding exposed portion 39, and can also be considered a sliding exposed portion cover, preventing the resin 52 from scattering to the outside.

[0029] FIG. 5B shows a third embodiment of a heater resin penetration prevention structure 6B. This heater resin penetration prevention structure 6B is composed of a main body 58 that stores resin, a fixed portion 59 fixed to the nozzle body 25, and a spring 61 connecting the fixed portion 59 to the main body 58. The main body 58 slides downward as resin accumulates in the main body 58, and the spring 61 extends depending on the amount of resin. In this embodiment, a limit switch 62 is provided, which detects when the amount of resin accumulated in the main body 58 exceeds a certain amount. In other words, it is a detection mechanism that detects the weight of the resin. The limit switch 62 is connected to the control device 4, which can then determine whether the shut-off nozzle 5 and the heater resin penetration prevention structure 6 should be cleaned.

[0030] 5C shows a heater-resin-penetration-preventing structure 6C according to a fourth embodiment. This heater-resin-penetration-preventing structure 6C is a heater cover that covers heater 38. In this embodiment as well, heater-resin-penetration-preventing structure 6C prevents resin 52 leaking from sliding exposed portion 39 from penetrating heater 38.

[0031] 5D shows a shut-off nozzle 70 according to a different embodiment and a resin penetration inhibiting structure 6D for inhibiting resin from entering a heater according to a fifth embodiment, which is provided on the shut-off nozzle 70. The shut-off nozzle 70 also comprises a nozzle body 71, a needle valve 72, and needle valve drive means 73. However, unlike the shut-off nozzle 5 according to the first embodiment, the needle valve 72 is provided coaxially with the nozzle body 71.

[0032] The needle valve drive means 73 includes an air-driven cylinder structure 75 and a spring retainer 76 connected to the cylinder structure 75. The spring retainer 76 is connected to the rear end of the needle valve 72. When air is supplied to the cylinder structure 75, the spring retainer 76 is pushed, thereby driving the needle valve 72 forward. In other words, it closes the injection flow path 77 in the nozzle body 71. On the other hand, when the air supply to the cylinder structure 75 is stopped, the spring retainer 76 retracts. In other words, the needle valve 72 retracts and the injection flow path 77 opens.

[0033] In this shut-off nozzle 70, the sliding exposed portion 78 forms a gap around the spring receiver 76. The heater resin intrusion prevention structure 6D according to the fifth embodiment is a cover that covers the sliding exposed portion 78. Therefore, even if resin leaks from the sliding exposed portion 78, the resin will not leak from the heater resin intrusion prevention structure 6D, and the intrusion of resin into the heaters 38, 38 can be prevented.

[0034] The resin intrusion prevention structure 6 for the heater according to this embodiment can also be implemented in a shut-off nozzle in which the shut-off valve is a rotary valve. Even in a shut-off nozzle equipped with a rotary valve, there will be a sliding area between the drive member and the nozzle body when the rotary valve is driven, and the part of the sliding area exposed to the outside will be called an exposed sliding area. The resin intrusion prevention structure for the heater can be provided near such an exposed sliding area. This is because the heater provided in the nozzle body can be protected from resin intrusion.

[0035] 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]

[0036] 1 Injection molding machine 2 Mold clamping device 3 Injection unit 4 Control unit 5 Shut-off nozzle 6 Resin penetration prevention structure to heater 7 Camera 8 Housing 9 Fixed plate 11 Upper movable plate 12 Lower movable plate 13 Tie bar 15 Toggle mechanism 16 Lower mold 17 Upper mold 18 Heating cylinder 19 Screw 21 Heater 25 nozzle body 26 needle valve 28 needle valve driving means 30 adapter 31 bracket 33 injection channel 35 Needle hole 36 Head 38 Heater 39 Exposed sliding part 41 First resin outflow prevention wall 42 Second resin outflow prevention wall 43 Third resin outflow prevention wall 46 Fixing part 47 Fixing part 48 Fixing band 49 Nut 50 Cutout 52 Resin 54 Main body 55 Lid 56 Fourth resin leakage prevention wall 58 Main body part 59 Fixed part 61 Spring 62 Limit switch 70 Shut-off nozzle 71 Nozzle body 72 needle valve 73 needle valve drive means 75 Cylinder structure 76 Spring support 77 Injection channel 78 Sliding exposed part

Claims

1. A shut-off nozzle comprising a nozzle body having an injection flow path for flowing a resin formed in an axial direction, and a shut-off valve for opening and closing the injection flow path, A resin intrusion prevention structure for a heater includes a heater cover that covers the heater provided in the shut-off nozzle near a sliding exposed portion that is exposed on the outer surface of the nozzle body among the sliding points between the drive member that drives the shut-off valve and the nozzle body, and prevents resin leaking from the sliding exposed portion from infiltrating into the heater.

2. 2. The structure for preventing resin from entering a heater according to claim 1, wherein the shutoff valve is a needle valve.

3. 3. The structure for inhibiting resin from entering a heater according to claim 2, wherein the needle valve is slidably provided in a needle hole that is opened so as to reach the injection flow path from the outer peripheral surface of the nozzle body, the drive member is the needle valve, and the sliding exposed portion is an opening portion of the needle hole.

4. a control device; A heating cylinder; a screw contained in the heating cylinder; a shut-off nozzle provided on the heating cylinder; a heater provided in the shut-off nozzle; a resin intrusion prevention structure provided in the shut-off nozzle to prevent the heater from entering the nozzle; the shut-off nozzle comprises a nozzle body having an injection flow path formed in an axial direction for flowing a resin, and a shut-off valve for opening and closing the injection flow path; The resin intrusion prevention structure for the heater comprises a heater cover that covers the heater near a sliding exposed portion that is exposed on the outer peripheral surface of the nozzle body among the sliding points between the drive member that drives the shutoff valve and the nozzle body, and prevents resin leaking from the sliding exposed portion from infiltrating into the heater, in an injection device.

5. 5. The injection device of claim 4, wherein the shut-off valve is a needle valve.

6. 6. The injection device according to claim 5, wherein the needle valve is slidably provided in a needle hole that is opened so as to reach the injection flow path from the outer peripheral surface of the nozzle body, the drive member is the needle valve, and the sliding exposed portion is an opening portion of the needle hole.

7. 6. The injection device according to claim 4, further comprising a camera disposed near the shut-off nozzle, and the control device is configured to monitor an amount of resin accumulated in the resin intrusion prevention structure toward the heater from an image captured by the camera.

8. 8. The injection device according to claim 7, wherein the control device outputs an alarm to notify cleaning when it determines that the amount of resin accumulated in the resin intrusion prevention structure toward the heater exceeds an allowable amount.

9. 8. The injection device according to claim 7, wherein the control device is configured to obtain a cumulative number of shots, which is a cumulative total of the number of shots performed in the injection device, and when an amount of resin accumulated in the resin intrusion prevention structure to the heater exceeds an allowable amount, if the cumulative number of shots exceeds an allowable number of shots, an alarm is output to prompt replacement of the shutoff valve.

10. an injection device that injects resin; a mold clamping device that clamps the mold; a control device; the injection device comprises a heating cylinder; a shut-off nozzle provided on the heating cylinder; a screw contained in the heating cylinder; a heater provided in the shut-off nozzle; a resin intrusion prevention structure provided in the shut-off nozzle to prevent the heater from entering the nozzle; the shut-off nozzle comprises a nozzle body having an injection flow path formed in an axial direction for flowing a resin, and a shut-off valve for opening and closing the injection flow path; The resin intrusion prevention structure for the heater comprises a heater cover that covers the heater near a sliding exposed portion that is exposed on the outer peripheral surface of the nozzle body among the sliding portions between the drive member that drives the shutoff valve and the nozzle body, and prevents resin leaking from the sliding exposed portion from invading the heater, an injection molding machine.

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