AE sensor mounting structure

Abstract

This provides an alternative mounting structure for AE sensors to the embedded type. [Solution] The AE sensor 32 is attached to the heating cylinder 14 via an attachment 50. In addition, the tip of the waveguide rod 31 is placed against the outer surface of the heating cylinder 14. The attachment 50 is fixed to the heating cylinder 14 in a manner that it is held in place by a band heater 13. There is no need to drill a hole in the heating cylinder 14 for inserting the waveguide rod 31. Therefore, the AE sensor 32 can be easily attached to and removed from existing injection devices.

Description

Technical Field

[0001] The present invention relates to an attachment structure of an AE sensor when measuring an AE wave emitted by an injection device with the AE sensor. AE means Acoustic Emission.

Background Art

[0002] [Definition of Injection Device] The injection device is a part of an injection molding device. The injection molding device consists of a bed, an injection device placed on this bed, and a mold clamping device. The mold clamping device clamps the mold. The injection device includes a heating cylinder and a screw, plasticizes a resin material (hereinafter also referred to as resin) introduced from a dropping port at the rear of the heating cylinder, and injects the molten resin into the mold by the forward movement of the screw.

[0003] The quality of a molded product obtained by the injection device is strongly affected by the plasticized state of the resin material. If the plasticized state of the resin material can be known, it will be beneficial for setting the conditions of the injection device.

[0004] Since the heating cylinder is a strong metal cylinder, it is impossible to visually observe the resin material from the outside. By providing a viewing window in the heating cylinder, visual observation is possible. However, the viewing window may affect the flow of the resin material and has the disadvantage of increasing installation costs. Therefore, various visualization technologies have been proposed as alternatives to the viewing window (see, for example, Patent Document 1 (Figure 2)).

[0005] Patent Document 1 will be described based on the following figure. Figure 6 is a front view of a conventional injection device. The injection device 100 includes a heating cylinder 101, a screw 102 rotatably and axially movably housed in the heating cylinder 101, a screw rotation mechanism 103 for rotating the screw 102, and a screw movement mechanism 104 for advancing the screw 102. In addition, as shown in the enlarged section of the figure, an AE sensor 105 is provided embedded in the heating cylinder 101.

[0006] The AE wave detected by the AE sensor 105 is sent to the molding machine controller 106 and used for control by the molding machine controller 106.

[0007] However, it is necessary to drill a hole 107 in the heating cylinder 101, and the processing cost for drilling the hole 107 is high. Furthermore, if an AE sensor 105 were to be newly installed on an existing injection molding machine 100, it would be necessary to remove the heating cylinder 101 from the injection molding machine 100, drill a hole 107 in the removed heating cylinder 101, and then reattach the heating cylinder 101 to the injection molding machine 100. Therefore, it is not easy to install an AE sensor 105 on an existing injection molding machine 100.

[0008] Therefore, the mounting structure for embedded AE sensors has many problems. Thus, an alternative mounting structure for AE sensors is needed. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Patent No. 5388996 [Overview of the project] [Problems that the invention aims to solve]

[0010] The object of this invention is to provide an AE sensor mounting structure that can replace the embedded type. [Means for solving the problem]

[0011] The invention according to claim 1 is a mounting structure for an AE sensor when measuring AE waves emitted by an injection device with the AE sensor, The AE sensor is equipped with a waveguide, The injection device comprises a heating cylinder containing a screw and a band heater wrapped around the heating cylinder. The band heater comprises a heater element that generates heat when an electric current is applied, an electrical insulating material covering the heater element, a metal cover that covers at least the outer surface of the electrical insulating material and has a ring-shaped section with a portion cut out, and a connector that connects one end of the metal cover to the other end. The AE sensor is attached to the heating cylinder via an attachment, The attachment consists of a seat that curves along the outer surface of the heating cylinder and a cylindrical body that extends from the seat away from the heating cylinder and houses the waveguide rod. The attachment is fixed to the heating cylinder by placing the seat against the outer surface of the heating cylinder and having the cylindrical body protrude from between one end and the other end of the metal cover, and the waveguide rod is inserted into the cylindrical body and the tip of the waveguide rod is placed against the outer surface of the heating cylinder.

[0012] The invention according to claim 2 is a mounting structure for the AE sensor described in claim 1, The waveguide is characterized by being made of a material with a higher thermal conductivity than the heating cylinder. [Effects of the Invention]

[0013] In the invention according to claim 1, the AE sensor is attached to the heating cylinder via an attachment. In addition, the tip of the waveguide is placed against the outer surface of the heating cylinder. The attachment is fixed to the heating cylinder in a manner that it is held in place by a band heater. There is no need to provide a hole in the heating cylinder for inserting the waveguide rod. Therefore, the AE sensor can be easily attached to and removed from existing and newly installed injection equipment. Since the attachment does not need to be secured to the heating cylinder with screws or other fasteners, there is no need to add any special processing to the heating cylinder, such as forming internal threads. Therefore, the present invention provides an AE sensor mounting structure that can replace the embedded type.

[0014] In the invention according to claim 2, the waveguide rod is made of a material having a higher thermal conductivity than the heating cylinder. Many materials having a high thermal conductivity have a large elastic modulus. Therefore, according to the present invention, it becomes easy to study the material of the waveguide rod.

Brief Description of the Drawings

[0015] [Figure 1] It is a diagram showing a basic configuration of an injection device according to the present invention. [Figure 2] It is a cross-sectional view taken along line 2-2 of FIG. 1. [Figure 3] It is an exploded view of a band heater and an attachment. [Figure 4] It is a view taken in the direction of arrow 4-4 of FIG. 3. [Figure 5] It is a graph showing the AE wave detection performance according to the present invention. [Figure 6] It is a front view of a conventional injection device.

Embodiments for Carrying Out the Invention

[0016] Embodiments of the present invention will be described below based on the attached drawings.

[0017] [Injection Device] As shown in FIG. 1, an injection device 10 includes a dropping port 11 for charging resin, a nozzle 12 for injecting plasticized resin, a heating cylinder 14 around which a band heater 13 is wound, a screw 15 rotatably and axially movably housed in the heating cylinder 14, a screw rotation mechanism 16 for rotating the screw 15, a screw movement mechanism 17 for advancing the screw 15, and an operation panel 18 as basic components.

[0018] [Operation Panel] The operation panel 18 controls the temperature of the heating cylinder 14, the rotation speed of the screw rotation mechanism 16, and the movement of the screw movement mechanism 17. For this purpose, the operation panel 18 includes a display 19 capable of making various settings and incorporates a control unit.

[0019] Multiple band heaters 13 are wrapped around the outer circumference of the heating cylinder 14, and the power supply to each band heater 13 is controlled by the zone control unit 21 so that the temperature information from the temperature sensor 22 matches the set temperature.

[0020] [Operation of the control panel] The resin falls into the heating cylinder 14 from the drop-off port 11. The fallen resin is guided by the spiral of the screw 15 and moves to the nozzle 12. During this movement, the heat from the heating cylinder 14 and the shearing heat generated by the screw 15 cause the resin to change from a solid to a molten state. The molten resin accumulates near the nozzle 12. The reaction force of the accumulated resin causes the screw 15 to retract. When the retraction distance reaches a predetermined value, plasticization is completed. The product of the retraction distance and the inner cross-section of the heating cylinder 14 becomes the metered value (plasticization metering process). After weighing, the screw 15 is advanced to inject the plasticizing resin into the mold (injection process). The control panel executes the above series of steps.

[0021] [Analysis support device for the molten state of resin] An analysis support device 30 for the molten state of the resin is attached to such an injection device 10. The resin molten state analysis support device 30 plays a role in supporting the work of analyzing the molten state of the resin.

[0022] The resin melting state analysis support device 30 consists of a plurality of waveguide rods 31 provided at intervals in the heating cylinder 14 along the axis of the screw 15, an AE sensor 32 provided at the ends of these waveguide rods 31 (the ends furthest from the heating cylinder 14) for detecting AE waves emitted by the resin, a calculation unit 33 that performs predetermined processing on the AE waveform detected by the AE sensor 32, and a display unit 34 that displays the processed AE waveform in the form of a graph or the like.

[0023] [AE sensor mounting structure] The mounting structure of the AE sensor 32 will be explained in detail based on Figures 2 to 4. Figure 2 is a cross-sectional view taken along line 2-2 in Figure 1, Figure 3 is an exploded view, and Figure 4 is a view taken along arrow 4-4 in Figure 3.

[0024] [AE sensor] As shown in Figure 3, the AE sensor 32 includes a waveguide rod 31. The waveguide rod 31 may be a separate component from the AE sensor 32. In this case, the end of the waveguide rod 31 is brought into close contact with the AE sensor 32.

[0025] [Wave guide rod] The waveguide rod 31 may be made of ordinary steel, but preferably it is a round bar made of a material with a higher thermal conductivity than the heating cylinder 14. Table 1 This will be shown.

[0026] [Table 1]

[0027] The heating element is made of steel. The thermal conductivity of steel is approximately 80 W / m·k, and its elastic modulus is 205 GPa. Tungsten and molybdenum have higher thermal conductivity and elastic modulus than steel. Therefore, they are evaluated as good and are suitable for use.

[0028] On the other hand, copper and aluminum are known to be metals with high thermal conductivity, but since their elastic moduli are lower than those of steel, they are not suitable for use. Although silicon carbide is a non-metallic ceramic, it has received a positive evaluation and is suitable for use.

[0029] When considering the material for the waveguide rod 31, the material can be efficiently selected by performing a first-order selection based on thermal conductivity and a second-order selection based on the elastic modulus. Therefore, it is recommended to first consider using a round rod made of a material with a higher thermal conductivity than the heating cylinder 14 for the waveguide rod 31.

[0030] [Band heater] The band heater 13 consists of a heater element 41 that generates heat when an electric current is applied, an electrical insulating material 42 that covers the heater element 41, a metal cover 43 that covers at least the outer surface of the electrical insulating material 42 and has a ring-shaped form with a part of the ring cut out (shape with a gap W), and a connector 44 that connects one end 43a and the other end 43b of the metal cover 43.

[0031] The heater element 41 is preferably made of nickel-chromium ribbon. Mica is preferred as the electrical insulating material 42. The metal cover 43 is preferably made of SUS304 strip.

[0032] [Connecting device] The connector 44 consists of a first curled portion 45 formed by curling around one end 43a of the metal cover 43, a second curled portion 46 formed by curling around the other end 43b of the metal cover 43, a bolt hole 47 formed through the first curled portion 45, a female threaded portion 48 formed in the second curled portion 46, and a bolt 49 that is inserted into the bolt hole 47 and screwed into the female threaded portion 48. By screwing in the bolt 49, the gap W can be reduced, and the smaller the gap W, the more firmly the band heater 13 is fixed to the heating cylinder 14.

[0033] The first curled portion 45 and the second curled portion 46 may be replaced with flanges formed by bending the ends of the metal cover 43 by 90°, and the bolts 49 may be replaced with clamps. Therefore, the connector 44 is not limited to the structure of the embodiment.

[0034] [attachment] The AE sensor 32 is attached to the heating cylinder 14 via the attachment 50. The attachment 50 consists of a seat 51 that curves along the outer surface of the heating cylinder 14, and a cylindrical body 52 that extends from the seat 51 away from the heating cylinder 14 and houses the waveguide rod 31. The seat 51 is provided with a central hole 53 whose diameter is sufficiently larger than the outer diameter of the waveguide rod 31.

[0035] As shown in Figure 4, the seat 51 is a strip of metal that is rectangular in plan view. The seat 51 may be a thin sheet of carbon steel, but it is preferably made of spring steel. In Figure 4, the attachment 50 is placed at the position indicated by the dashed line. Then, one end 43a and the other end 43b of the band heater 13 are placed over it. At this time, the cylindrical body 52 is positioned between the one end 43a and the other end 43b of the band heater 13.

[0036] The bolt 49 is passed through the bolt hole 47 and screwed into the female threaded portion 48. As it is screwed in, the gap W becomes smaller. As a result, the band heater 13 comes into close contact with the heating cylinder. Then, the seat 51 is pressed against the heating cylinder 14 by the band heater 13.

[0037] Specifically, as shown in Figure 2, the attachment 50 is fixed to the heating cylinder 14 in a manner that it is held in place by the band heater 13. The waveguide rod 31 is inserted into the cylindrical body 52 of the attachment 50, and its tip is pressed against the outer surface of the heating cylinder 14.

[0038] In this way, the AE sensor 32 is attached to the heating cylinder 14 via the attachment 50. There is no need to provide a hole in the heating cylinder 14 for inserting the waveguide rod 31. Therefore, the AE sensor 32 can be easily attached to existing and newly installed injection devices and easily removed. Since the attachment 50 does not need to be fastened to the heating cylinder 14 with screws or the like, there is no need to add any special processing to the heating cylinder 14, such as forming female threads.

[0039] The resin material is plasticized as it passes between the heating cylinder 14 and the screw 15. During the plasticization process, the solid resin material breaks down and melts. Large AE waves are generated when it breaks down. AE waves originating from the resin material are detected by the AE sensor 32 via the heating cylinder 14 and waveguide rod 31.

[0040] [Replacement of AE sensor, etc.] After a certain period of use, malfunctions may occur in the AE sensor 32 itself, or the waveguide rod 31 may deform and move away from the heating cylinder 14. When such a malfunction is found, remove the bolt 49, widen the gap W between one end 43a and the other end 43b of the band heater 13, remove the attachment 50, and pull the waveguide rod 31 out of the attachment 50. This allows us to inspect the AE sensor 32 and the waveguide rod 31.

[0041] Once the inspection is complete, the healthy AE sensor 32 and waveguide rod 31 can be attached to the heating cylinder 14 by following the reverse procedure. In other words, the setup can be returned to Figure 2. [Examples]

[0042] The AE wave detection using the embedded AE sensor 105 shown in Figure 6 will be used as a comparative example. The detection of AE waves by the AE sensor 32 via the attachment 50 shown in Figure 2 is presented as an example.

[0043] [Experimental conditions] Resin material: General-purpose polystyrene (GPPS) Heating cylinder temperature: 220℃ Screw rotation speed: 100 revolutions per minute The above conditions apply to both the examples and the comparative examples.

[0044] [Experimental Results] The experimental results are shown in Figure 5. In the comparative example, the AE wave at CH3 is high. Near CH6, the resin material is close to solid, so the AE wave is also high. In contrast, in the embodiment, CH3 had a low AE wave, while CH4, CH5, and CH6 had higher AE waves in that order. However, for CH1 to CH4, the examples did not differ significantly from the comparative examples. Therefore, it was confirmed that the structure of the present invention has detection performance comparable to that of conventional embedded types and is fully employable. [Industrial applicability]

[0045] The present invention is suitable for mounting an AE sensor in an injection molding device that injects molten resin. [Explanation of Symbols]

[0046] 10...Injection device, 13...Band heater, 14...Heating cylinder, 15...Screw, 31...Wave guide rod, 32...AE sensor, 41...Heater element, 42...Electrical insulating material, 43...Metal cover, 43a...One end, 43b...The other end, 44...Connector, 50...Attachment, 51...Base, 52...Cylindrical body.

Claims

1. A mounting structure for an AE sensor when measuring AE waves emitted by an injection device, The AE sensor is equipped with a waveguide rod. The injection device comprises a heating cylinder containing a screw and a band heater wrapped around the heating cylinder. The band heater comprises a heater element that generates heat when an electric current is applied, an electrical insulating material covering the heater element, a metal cover that covers at least the outer surface of the electrical insulating material and has a ring-shaped section with a portion cut out, and a connector that connects one end of the metal cover to the other end. The AE sensor is attached to the heating cylinder via an attachment, The attachment consists of a seat that curves along the outer surface of the heating cylinder and a cylindrical body that extends from the seat away from the heating cylinder and houses the waveguide rod. An AE sensor mounting structure characterized by the following: the base is placed against the outer surface of the heating cylinder, the attachment is fixed to the heating cylinder such that the cylinder protrudes from between one end and the other end of the metal cover, the waveguide rod is inserted into the cylinder, and the tip of the waveguide rod is placed against the outer surface of the heating cylinder.

2. The mounting structure for the AE sensor according to claim 1, The mounting structure for an AE sensor is characterized in that the waveguide rod is made of a material with a higher thermal conductivity than the heating cylinder.

Images