Injection device

Abstract

To provide an injection device that can suppress operating costs without the risk of the powdery resin material being discharged to the outside. 【Solution means】An injection device (20) in which the resin material stored in the hopper (28) is dropped into the heating cylinder (27) via the hopper holding member (50) and the dropping port bush (40), wherein the dropping port bush (40) is provided with a first gas passage (42) that extends upward and guides the gas generated from the resin material in the heating cylinder (27), and the hopper holding member (50) is provided with a second gas passage (57) that is connected to the first gas passage (42) and guides the gas, and a gas outlet that discharges the gas to the outside. Since natural exhaust is performed instead of forced exhaust, the exhaust becomes gentle and it is difficult for the powder to be discharged to the outside. Since it is natural exhaust, no electric energy or the like is required.

Description

Technical Field

[0001] The present invention relates to an injection device for kneading and injecting a resin material in a heating cylinder.

Background Art

[0002] A solid resin material is kneaded and melted by a screw in a heating cylinder of an injection device. In this process, although slightly, gas may be generated from the resin material. This gas is injected into the mold together with the melted resin material. The obtained resin material contains a trace amount of gas.

[0003] For general-purpose resin products, the inclusion of a trace amount of gas is acceptable. However, for certain resin products, a purity above a certain level is required, and a reduction in gas inclusion is demanded. One of the technologies to meet that requirement is known, for example, as disclosed in Patent Document 1.

[0004] Patent Document 1 will be described based on the following figure. FIG. 6 is a diagram for explaining the basic structure of a conventional injection device. As shown in FIG. 6, an injection device 100 including a barrel 101, a hopper 102, a hopper base 103 supporting the hopper 102, a screw 104, a barrel support base 105 supporting the barrel 101, and a barrel clamp 106 for holding down the barrel 101 is provided with the following elements in Patent Document 1.

[0005] That is, it includes a nitrogen gas supply source 111 for supplying nitrogen gas to a dropping port 107 below the hopper 102, a first exhaust passage 112 extending upward from the tail of the barrel support base 105, a first vacuum generator 113 provided in the first exhaust passage 112, a second exhaust passage 114 extending upward from the barrel clamp 106, and a second vacuum generator 115 provided in the second exhaust passage 114.

[0006] When the resin material 116 is kneaded and plasticized by the screw 104, the gas generated is forcibly discharged to the atmosphere (i.e., to the outside) by the first and second vacuum generators 113 and 115 via the first and second exhaust passages 112 and 114. As a result, in the technology of Patent Document 1, Ta the resin product maintains a purity above a certain level.

[0007] However, the technology of Patent Document 1 has the following problems. When the resin material 116 is in powder form, a part of the resin material 116 is sucked by the first and second vacuum generators 113 and 115 and discharged to the outside. Therefore, the yield represented by (weight of resin product / weight of resin material) deteriorates. When the yield deteriorates, the effective utilization rate of the resin material 116 decreases, which is not preferable.

[0008] In addition to the equipment that uses compressed air (Patent Document 1, paragraph 0052), which is usually installed in the factory, as a driving source, a vacuum pump that uses an electric motor as a driving source is adopted for the first and second vacuum generators 113 and 115. When the driving source is compressed air, energy (such as electric energy) for compressing the air is required. In the case of a vacuum pump, electric energy is required. As a result, the operating cost increases.

[0009] There is a need for an injection device that can produce a resin product with the required purity without the worry of the powdery resin material being discharged to the outside and can suppress the operating cost.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0011] An object of the present invention is to provide an injection device that can prevent a powdery resin material from being discharged to the outside and can suppress operating costs.

Means for Solving the Problems

[0012] The invention according to claim 1 includes a heating cylinder, a screw rotatably and axially movably accommodated in the heating cylinder, an injection table supporting the heating cylinder, a drop port bush attached to the injection table, a hopper holding member disposed on the drop port bush, and a hopper disposed on the hopper holding member, An injection device in which a resin material stored in the hopper is dropped into the heating cylinder through the hopper holding member and the drop port bush, The drop port bush is provided with a first gas passage that extends upward and guides gas generated from the resin material in the heating cylinder, The hopper holding member is provided with a second gas passage that connects to the first gas passage and guides the gas, and a gas outlet that discharges the gas to the outside 1. A vacuum pump is not connected to the gas outlet. characterized by this.

[0013] The invention according to claim 2 is the injection device according to claim 1, The second gas passage of the hopper holding member consists of a vertical passage that connects to the first gas passage and extends upward, and a horizontal passage that extends horizontally from the upper end of the vertical passage, The gas outlet is provided at the outlet of this horizontal passage, and the gas is discharged horizontally from this gas outlet.

[0014] The invention according to claim 3 is the injection device according to claim 1 or claim 2, A filter for capturing powder discharged along with the gas is provided at the gas outlet.

[0015] The invention according to claim 4 is the injection device according to claim 1, The drop port bush is made of a corrosion-resistant material having corrosion resistance to the gas.

[0016] The invention according to claim 5 is an injection device according to claim 1, Before wherein the dropping port bush 3. The bottom surface extends to the outer peripheral surface of the heating cylinder, and the lower part of the drop port bush is not inserted into the heating cylinder. is characterized in that.

Effect of the Invention

[0017] In the invention according to claim 1, a first gas passage is provided in the dropping port bush, a second gas passage is provided in the hopper holding member, and gas is discharged to the outside through the first gas passage and the second gas passage. For this discharge, a vacuum pump or the like is not used. That is, in the present invention, the gas is discharged by a so-called natural exhaust method. Since a vacuum pump or the like is not used, electrical energy is not required and the operating cost can be compressed.

[0018] Compared with the forced exhaust method, the natural exhaust method is a gentle exhaust method. With such an exhaust method, the powdery resin material is not discharged to the outside, or even if there is any, it is in a very small amount. Therefore, according to the present invention, there is provided an injection device in which there is no fear of the powdery resin material being discharged to the outside and the operating cost can be suppressed.

[0019] In the invention according to claim 2, the second gas passage is composed of a vertical passage extending upward together with the first gas passage and a horizontal passage extending horizontally from the upper end of the vertical passage. Although the second gas passage is provided in the hopper holding member, since the second passage is a simple passage composed of a vertical passage and a horizontal passage, the processing cost of the hopper holding member can be reduced.

[0020] In the invention according to claim 3, a filter for capturing powder discharged along with the gas is provided at the gas outlet of the horizontal passage. In the present invention, in principle, powder is not discharged to the outside, but there is a possibility that a very small amount of powder may be discharged. Even in this case, by providing a filter, the powder is not discharged to the outside, which is preferable.

[0021] In the invention according to claim 4, the drop port bush is made of a corrosion-resistant material. When the resin material is polyvinyl chloride, a small amount of chlorine-based gas is generated. Chlorine-based gas is corrosive. If the drop port bush is made of a corrosion-resistant material, polyvinyl chloride can be added to the resin material. As a result, the types of resin materials that can be processed can be increased.

[0022] In the invention according to claim 5 Is, fall the lower port bush 5. The bottom surface extends to the outer peripheral surface of the heating cylinder, and the lower part of the drop port bush is not inserted into the heating cylinder. 。 6. A cylindrical space calculated by (the wall thickness of the heating cylinder × the bottom area of the drop port bush) is secured in the heating cylinder. 7. The resin material falling from the drop port spreads in a frustum of a cone shape, but a sub - space with a triangular cross - section remains at the corner of the space. Due to the existence of this sub - space, the opening of the first gas passage is maintained, and the gas smoothly enters the first gas passage.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0024] Embodiments of the present invention will be described below with reference to the accompanying drawings. Note that the drawings are to be viewed in the direction of the reference numerals.

Examples

[0025] [Injection Molding Apparatus] As shown in Fig. 1, the injection molding apparatus 10 mainly includes a mold clamping device 11, an injection device 20, and a bed 12 that supports the mold clamping device 11 and the injection device 20. The mold clamping device 11 is a device for clamping the mold 13, and only a part (fixed platen 14) is shown for the sake of drawing.

[0026] [Injection Device] The injection device 20 is a moving table 22 supported by a rail 21 laid on the bed 12 and is supported so as to be horizontally movable. For example, the nozzle 24 is reciprocated between a position where it touches the mold 13 and a position sufficiently separated from the mold 13 (the position in the figure) by an injection device moving cylinder 23 passed between the moving table 22 and the fixed platen 14. The injection device moving cylinder 23 can employ a hydraulic cylinder or an electric cylinder.

[0027] The injection device 20 includes an injection table 26 supported by the moving table 22, a heating cylinder 27 supported by this injection table 26, a hopper 28 for supplying a resin material to this heating cylinder 27, a screw 29 rotatably and axially movably housed in the heating cylinder 27, a screw moving cylinder 31 attached to the injection table 26, a moving plate 33 supported by the piston rod 32 of this screw moving cylinder 31, and a screw rotation mechanism 34 supported by this moving plate 33 and rotating the screw 29.

[0028] The screw moving cylinder 31 can employ a hydraulic cylinder or an electric cylinder. The screw rotation mechanism 34 can employ an electric motor or a hydraulic motor.

[0029] The injection device 20 further includes the following elements. That is, it includes a dropping port bush 40 attached to the injection table 26 and a hopper holding member 50 disposed on this dropping port bush 40. The hopper 28 is disposed on this hopper holding member 50.

[0030] [Plasticization and Metering Process] Plasticization and metering process: While rotating the screw 29 in a predetermined direction by the screw rotation mechanism 34, a resin material is supplied from the hopper 28 to the heating cylinder 27. The resin material moves inside the heating cylinder 27 along the spiral groove of the screw 29 to the vicinity of the nozzle 24. During this movement, the resin material is plasticized while being kneaded, and the plasticized resin material accumulates at the front part of the heating cylinder 27. Due to the reaction force of the accumulated resin material, the screw 29 retreats (moves away from the nozzle 24). When the screw 29 retreats to a predetermined position, the rotation of the screw 29 is stopped. Thus, plasticization and metering are performed.

[0031] [Injection process] Injection process: With the nozzle 24 touching the mold 13, the screw 29 is advanced by the screw movement cylinder 31. Due to this advancement, the resin material is injected into the mold 13 through the nozzle 24.

[0032] [Resin material] The resin material is not particularly limited, but a resin material that generates gas during the plasticization and metering process can be processed by the injection device 20 of the present invention. Examples of resins that generate gas include polyvinyl chloride (PVC), polyphenylene sulfide (PPS), polycarbonate (PC), polyether ether ketone (PEEK), acrylonitrile - butadiene - styrene resin (ABS), and polymethacrylic (PMMA).

[0033] [Drop - opening bush] Based on FIGS. 2(a) to (c), the structure of the drop - opening bush 40 will be described in detail. Note that FIG. 2(a) is a plan view of the drop - opening bush 40, FIG. 2(b) is a cross - sectional view thereof, and FIG. 2(c) is a bottom view thereof.

[0034] As shown in FIG. 2(a), the drop - opening bush 40 has a drop - opening 41 for dropping the resin material at the center, and has a plurality of (eight in this example) first gas passages 42 surrounding the drop - opening 41. As shown in FIG. 2(b), the drop - opening bush 40 has a flange 43. As shown in Fig. 2(c), a plurality of first gas passages 42 can be seen surrounding the dropping port 41.

[0035] [Material of the dropping port bush] The material of the dropping port bush 40 can be ordinary carbon steel, mechanical structure steel, or cast iron. However, when the resin material to be handled contains polyvinyl chloride, it is recommended to use a corrosion-resistant material such as stainless steel that has corrosion resistance to chlorine-based gases.

[0036] [Machining of the dropping port bush] As shown in Figs. 2(a) to 2(c), the dropping port bush 40 has a very simple shape. In particular, it does not have fine threaded parts (also called taps). Therefore, the machining of the dropping port bush 40 is easy.

[0037] [Hopper holding member] Based on Figs. 3(a) to 3(c), the structure of the hopper holding member 50 will be described in detail. Note that Fig. 3(a) is a plan view of the hopper holding member 50, Fig. 3(b) is a cross-sectional view thereof, and Fig. 3(c) is a bottom view thereof.

[0038] As shown in Fig. 3(a), the hopper holding member 50 is a square thick plate, has a through hole 51 with the same diameter as the dropping port (Fig. 2(a), reference numeral 41) at the center, has a bar 52 crossing this through hole 51, and has threaded parts 53 and bolt holes 54 at the four corners respectively.

[0039] By assembling the bars 52 in a grid pattern, it is possible to prevent objects larger than the mesh of this grid (including the hands of the operator) from falling from the hopper (Fig. 1, reference numeral 28) side into the dropping port. The hopper holding member having a falling object prevention mechanism is a general-purpose product, and by machining this general-purpose product, the hopper holding member 50 can be easily obtained.

[0040] By screwing the bolt 36 shown in Fig. 1 into the threaded part 53, the hopper 28 can be fixed to the hopper holding member 50. Also, by passing a bolt 55 with a hexagonal hole through the bolt hole 54, the hopper holding member 50 can be fixed to the injection table 26 shown in FIG. 1.

[0041] In FIG. 1, the dropping port bush 40 is fitted so as to drop into the injection table 26, the hopper holding member 50 is overlapped thereon, and the hopper holding member 50 is fixed to the injection table 26 with a bolt with a hexagonal hole (reference numeral 55 in FIG. 3(a)). The dropping port bush 40 is only placed on the injection table 26 by the flange 43. The dropping port bush 40 is prevented from coming off upward by the hopper holding member 50. Therefore, as described above, the structure of the dropping port bush 40 is simplified.

[0042] As shown in FIG. 3(b), the hopper holding member 50 has a second gas passage 57. The second gas passage 57 is composed of a vertical passage 58 that extends upward while being connected to the upper end of the first gas passage (reference numeral 42 in FIG. 2(b)), and a horizontal passage 59 that extends horizontally from the upper end of the vertical passage 58.

[0043] As shown in FIG. 3(c), the vertical passage 58 is an annular groove. If it is an annular groove, even if the dropping port bush 40 shown in FIG. 2(a) rotates, the first gas passage 42 will always be connected to the vertical passage 58 shown in FIG. 3(a). As shown in FIG. 3(a), a plurality of (four in this example) horizontal passages 59 are connected to the annular groove-shaped vertical passage 58.

[0044] As shown in FIG. 3(b), a female thread portion 62 may be provided at the gas outlet 61 of the horizontal passage 59, and a cylindrical filter 63 may be attached to the female thread portion 62.

[0045] Whether or not to attach the filter 63 is arbitrary, but the following criteria are recommended. Attach the filter 63 when the resin material to be handled is powder. Do not attach the filter 63 when the resin material to be handled is not powder. In this case, the female thread portion 62 may be omitted.

[0046] [Powder and beads] The particle size of the powder is 200 μm to 300 μm. The resin material called beads has a particle size of several millimeters. When the powder or beads are subjected to wind pressure, a wind pressure proportional to the cross-sectional area (square of the radius) acts. On the other hand, the mass (self-weight) of the powder or beads is proportional to the cube of the radius. Due to the balance between this mass and the wind pressure, the beads are less likely to fly, and the powder is more likely to fly. Therefore, in the case of beads, the filter 63 is not necessary, and in the case of powder, it is recommended to attach the filter 63.

[0047] [Material of Hopper Holding Member] The material of the hopper holding member 50 is preferably a corrosion-resistant material such as stainless steel having corrosion resistance to chlorine-based gases.

[0048] However, as described with reference to FIGS. 3(a) to 3(c), since the structure of the hopper holding member 50 is slightly complicated, ordinary carbon steel, machine structural steel, or cast iron can also be used. Since carbon steel and the like are inexpensive, they can be appropriately replaced with new ones. Therefore, whether to use expensive stainless steel or inexpensive carbon steel or the like for the material of the hopper holding member 50 can be arbitrarily selected in consideration of cost-effectiveness.

[0049] The operation of the injection device 20 having the above configuration will be described based on FIG. 4. In FIG. 4, the resin material stored in the hopper 28 falls into the heating cylinder 27 through the through hole 51 and the dropping port 41. The resin material is kneaded and plasticized by the screw 29. Gas may be generated in this process.

[0050] Based on the natural laws that a fluid containing gas flows where it is easy to flow, the fluid flows toward the outlet, and a gas lighter than air rises in the atmosphere, the gas acts. The gas outlet (reference numeral 61 in FIG. 3(b)) of the present invention hits the outlet toward which the fluid flows.

[0051] That is, the gas generated in the heating cylinder 27 heads toward the first gas passage 42 as indicated by the arrow G1. The gas passes through the first gas passage 42 and the second gas passage 57 and is discharged outside as indicated by the arrow G2.

[0052] The amount of gas in the heating cylinder 27 is reduced by the amount discharged. As a result, the amount of gas contained in the resin product remains within the allowable range, and the quality of the resin product is maintained.

[0053] Note that since the flow of the arrow G1 is based on natural exhaust, it is very gentle. Therefore, unlike forced exhaust, powder is not vigorously discharged outside together with the gas, and even if there is any, it is in a very small amount. Because it is in a very small amount, the filter 63 is not essential. However, it is more preferable to provide the filter 63 to surely capture the very small amount of powder. To However, by providing the filter 63, a very small amount of powder can be surely captured, which is more preferable.

[0054] [Height dimension of the dropping port bush] Next, the height dimension of the dropping port bush 40 is considered. For the dropping port bush 40 shown in Fig. 5(a), the bottom surface extends to the inner peripheral surface 27a of the heating cylinder 27. Although gas venting is possible with this structure, there is a risk that the lower opening of the first gas passage 42 may be blocked by the resin material.

[0055] For the dropping port bush 40 shown in Fig. 5(b), the bottom surface extends to the outer peripheral surface 27b of the heating cylinder 27. As a result, a cylindrical space 65 (see Fig. 4) calculated by (the wall thickness of the heating cylinder × the bottom area of the dropping port bush) is secured in the heating cylinder 27. The resin material 64 dropping from the dropping port 41 spreads in a frustum of a cone shape, but a sub - space 66 with a triangular cross - section remains at the corner of the space 65. Due to the existence of this sub - space 66, the opening of the first gas passage 42 is maintained, and the gas smoothly enters the first gas passage 42. Therefore, Fig. 5(b) is recommended rather than Fig. 5(a).

[0056] In addition, the first gas passage 42 shown in Fig. 2(b) may be an inclined passage that extends obliquely upward in addition to extending vertically upward. The main point is that it should extend upward. Similarly, the vertical passage 58 shown in FIG. 3(b) may be an inclined diagonal passage in addition to extending vertically upward, as long as it extends upward. Also, the horizontal passage 59 shown in FIG. 3(b) may be inclined with respect to the horizontal in addition to extending horizontally, as long as it extends horizontally.

[0057] Also, the drop port bush 40 and the hopper holding member 50 may be integrated into a single part in addition to being separate parts. That is, the flange 43 shown in FIG. 2(b) may be enlarged, and the second gas passage 57 may be formed in the enlarged flange 43.

Industrial Applicability

[0058] The present invention is suitable for an injection device that injects a powdery resin material.

Explanation of Reference Numerals

[0059] 20... Injection device, 26... Injection table, 27... Heating cylinder, 28... Hopper, 29... Screw, 40... Drop port bush, 42... First gas passage, 50... Hopper holding member, 57... Second gas passage, 58... Vertical passage, 59... Horizontal passage, 61... Gas outlet, 63... Filter 15. 64... resin material .

Claims

1. An injection device comprising a heating cylinder, a screw rotatably and axially movably accommodated in the heating cylinder, an injection table supporting the heating cylinder, a dropping port bush attached to the injection table, a hopper holding member disposed on the dropping port bush, and a hopper disposed on the hopper holding member, wherein the resin material stored in the hopper is dropped into the heating cylinder through the hopper holding member and the dropping port bush, the dropping port bush is provided with a first gas passage extending upward to guide the gas generated from the resin material in the heating cylinder, the hopper holding member is provided with a second gas passage connected to the first gas passage to guide the gas and a gas outlet for discharging the gas to the outside, and a vacuum pump is not connected to the gas outlet. The injection device is characterized by this.

2. The injection device according to Claim 1, wherein the second gas passage of the hopper holding member consists of a vertical passage connected to the first gas passage and extending upward, and a horizontal passage extending horizontally from the upper end of the vertical passage, and the gas outlet is provided at the outlet of the horizontal passage, and the gas is discharged horizontally from the gas outlet. The injection device is characterized by this.

3. The injection device according to Claim 1 or Claim 2, wherein a filter for capturing the powder discharged along with the gas is provided at the gas outlet. The injection device is characterized by this.

4. The injection device according to Claim 1, wherein the dropping port bush is made of a corrosion-resistant material having corrosion resistance to the gas. The injection device is characterized by this.

5. The injection device according to Claim 1, wherein the bottom surface of the dropping port bush extends to the outer peripheral surface of the heating cylinder, and the lower part of the dropping port bush is not inserted into the heating cylinder. The injection device is characterized by this.

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