Melting apparatus for injection molding device and injection molded article using same

Abstract

The purpose of the present invention is to provide is a melting apparatus for an injection molding device. The melting apparatus melts a resin material (resin pellets) in a plunger-type injection molding device which has a vertical structure and which does not have a resin extrusion screw. This melting apparatus for an injection molding device comprises: a melting part that forms a rectangular parallelepiped-shaped housing structure and that has a plurality of melting holes which vertically penetrate the interior of the housing structure and which have an upper-end horizontal cross-sectional area smaller than that at the lower end of the melting holes; and a heater storage part that is disposed so as to face at least one of the outer side walls which run along the width of the melting part and to face a lower section thereof, the heater storage part having a heater.

Description

Melter for injection molding equipment and injection molded product using the same

[0001] The present invention relates to a melter for an injection molding apparatus that melts resin material (resin pellets) in a plunger-type injection molding apparatus that does not have a vertical structure resin extrusion screw.

[0002] Generally, resin injection molding machines are classified into two types: a screw type as shown in Patent Document 1 and a plunger type as shown in Patent Document 2. A screw-type injection molding machine is mainly composed of a cylinder and a screw. Resin pellets are fed from a hopper into the cylinder, and as the screw rotates, resin pellets are pressed and transported toward the injection nozzle. The pellets are heated and melted in the process, and the molten resin is then injected into a mold from the tip of the nozzle. However, due to factors such as the thermal conductivity of resin pellets, poor pellet melting efficiency during the pressing process, and the need to secure a large amount of pellets, injection molding machines tend to be large and complex in structure. Furthermore, the replacement of worn screws is also a significant burden.

[0003] On the other hand, plunger-type injection molding machines are mainly composed of a melter including a heater in the shape of a truncated cone (the remaining part when the head of a cone such as a truncated cone or a truncated pyramid is cut off along a plane parallel to the base) with many through holes, an injection plunger, a supply tube, etc. The injection plunger delivers the resin raw material to the melter for injection, which has the advantage of being a relatively simple structure and easy to make compact. Even with such plunger-type injection molding machines, large void spaces exist between the tip of the plunger and the melter, and between the tip of the plunger and the supply tube, preventing the resin raw material from efficiently flowing into the through holes of the melter and remaining in the void spaces, hindering the delivery of new resin raw material. There are also problems with mixing new resin with resin that has remained and deteriorated for a long time.

[0004] In order to solve this problem, the present inventors have developed an injection molding apparatus that can efficiently achieve the process of melting the pellet resin and the process of injecting the molten resin by simply pressing a collection of pellets with a plunger, as shown in Patent Document 3, etc., so that the pellets pass through a number of tapered holes in the melter, and have further achieved faster melting speeds and injection times, as shown in Patent Document 4, etc.

[0005] Japanese Patent Publication No. 6-246802 Japanese Patent Publication No. 36-9884 Japanese Patent No. 4880085 International Publication WO2014 / Patent No. 185514

[0006] However, even the injection molding devices described in Patent Documents 3 and 4 above still have room for improvement. Specifically, the resin material must melt as it passes through the multiple through-holes in the melter. The method of heating a truncated cone-shaped melter from the periphery with a heater has limitations in uniformly and quickly heating a large amount of resin material up to the through-holes near the center of the melter. This necessitates the development of a melter structure or selection of a material suitable for melting large amounts of resin material (demands for larger sizes and reduced cycle times). In particular, for resin materials that cannot melt at high temperatures, such as bioplastics, it is necessary to develop a structure or select a material that allows large amounts of resin to be injected while melting at low temperatures. Furthermore, for resin materials such as high-strength fibers, the melter must be highly resistant to wear.

[0007] In view of the above, the present invention has been created, and its object is to provide a melter for a plunger-type injection molding machine that does not have a vertical resin extrusion screw, is capable of uniformly and quickly inputting heat while consuming little power, and is capable of injection molding large volumes of resin material.

[0008] The present invention provides a melter for an injection molding device that melts a resin material (resin pellets) in a plunger-type injection molding device that does not have a vertical resin extrusion screw, and the melter has a rectangular parallelepiped housing structure, inside which a melting section has a plurality of melting holes that penetrate vertically and whose area does not increase from top to bottom, and a melting heater section that is arranged on one outer wall of the outer wall so as to input heat at least up to the lower part of one side of the outer wall of the width length of the melting section, and that houses a heating heater.

[0009] The melter for an injection molding apparatus of the present invention is a plunger-type melter with a vertical structure in which a resin material (resin pellets) is fed from above, transported while melted in the melter, and then injected from below. In particular, the melting section where the resin material is melted as it is transported downward has a rectangular parallelepiped housing structure, and a melter heater section that houses a heater for heating the melting section is disposed on one or both sides of the outer wall on the longer width side.

[0010] In conventional cylindrical melters with multiple through holes, heaters were attached to the outer periphery to heat the melter from the periphery, which resulted in large differences in heat conduction between the through holes near the periphery (equivalent to the melting holes of this invention) and those near the center, making uniform heating difficult and hindering upsizing. However, the melter for this injection molding device has a rectangular casing structure with a heater accommodating section attached to the outer wall with a large surface area, so the distance from each heater to each melting hole is short and there is little variation in each distance, resulting in good heat conduction and uniform heating, and a structure that makes it easy to upsize using a low-power heater.

[0011] Furthermore, it is preferable that the melter heater portions are disposed on both outer walls of the melting portion in the width direction thereof, thereby sandwiching the melting portion from the narrower width direction side.

[0012] By disposing the melter heater units on both sides of the long outer wall of the melting portion and sandwiching each melting portion from both sides, when a large melting unit is constructed by arranging multiple melters in parallel as described below, heat can be input from both sides of each melter at an equal distance near the internal melting hole, and the resin material can be melted uniformly and quickly even when unitized. Note that it is also possible to dispose additional melter heater units on one or both sides of the short outer wall of the melting portion and input heat from the periphery.

[0013] If the heater section for the melter is provided not only on the long outer wall but also on the short outer wall, the heat can be input to the melt hole more uniformly, which is particularly effective in the case of a thick melt portion.

[0014] In addition, it is preferable that the melter has a plurality of melting sections and the melter heater sections sandwiching the melting sections from the short width direction, the outer walls of which are arranged in parallel in the short width direction.

[0015] The melter for this injection molding machine is formed as a unit with multiple melting sections arranged in parallel (hereinafter simply referred to as a "unit type"), sandwiched between heater sections. As described above, each melting section has a rectangular parallelepiped housing structure. By arranging the melting sections in parallel facing each other, the number of melting sections arranged in parallel can be increased or decreased depending on the amount of resin material desired to be melted, advantageously facilitating changes and adaptations from small to large injection volumes. In this case, by sandwiching the melting sections between heater housing sections, heat from both heaters is conducted to the melting section, allowing the resin material in the melting hole to be sufficiently heated with a low-power heater. Since overheating is unlikely, the heater housing section and melting section can have a long life, advantageously reducing replacement costs. Furthermore, by arranging multiple melting sections in parallel, resin material does not infiltrate and accumulate between adjacent melting sections, specifically at the boundaries between the melting sections and the heater housing section. This prevents the resin material from accumulating at the boundary, making it difficult to properly control the injection amount, and prevents the resin material used in a previous injection process from mixing with the current resin material.

[0016] Furthermore, the plurality of fusion holes in the fusion portion each have a horizontal cross section of a substantially identical rectangular shape, are arranged in a row along the width direction, and are inclined so that the horizontal cross-sectional area of ​​the lower part is equal to or less than the horizontal cross-sectional area of ​​the upper part.

[0017] Each melting part has a rectangular parallelepiped housing structure, and the melting holes provided inside are arranged in a row (one or more rows) of openings with a horizontal cross section that is approximately rectangular (for example, including a rectangular shape with rounded corners). This allows the partitions between the melting holes to be as thin as possible and arranged closely together, resulting in a high aperture ratio. In other words, the maximum inlet area for the resin material can be secured for the size of each melting part. Furthermore, the melting holes have a rectangular horizontal cross section and are inclined so that the area does not increase from top to bottom, making it relatively easy to form a smooth inner wall.

[0018] It is also preferable that the plurality of fusion holes in the fusion zone have substantially the same substantially rectangular horizontal cross section, are arranged in a row along the width direction, and the fusion holes of adjacent fusion zones are arranged shifted from each other in the width direction.

[0019] In this unit-type injection molding melter, the multiple melt holes in each melting section are arranged offset in the width direction. Therefore, heat from the melting section heater does not pass much through the space within the melting holes, but is mostly conducted through the melting section material to the adjacent melting section. Specifically, heat from the melting section heater does not pass through the resin material with low thermal conductivity or the air layer within the melting holes, but is conducted through the melting section material with high thermal conductivity (typically cemented carbide). Therefore, even in a unit-type melting device with multiple melting sections arranged on top of each other, the resin material can be melted uniformly and efficiently.

[0020] In some cases, the molten portion comprises a main body portion having a plurality of grooves that are open on one side and extend vertically, and a closed outer wall on the opposite side, and a lid member that is attached opposite to one side of the main body portion and closes the grooves of the main body portion, and when closed, the grooves of the main body portion and the lid member form a molten hole.

[0021] Each melting section in this melting device for an injection molding machine is composed of two components: a main body having a groove that opens to one side of the body, and a lid that is attached opposite the open side of the main body to close the groove (hereinafter referred to simply as a "separate melting section"). Simply stacking the two components allows the formation of a melting hole. When the melting section is made of cemented carbide, it is preferable to stack the main body and lid and then attach them by adhesive heat treatment. This structure allows the main body to be manufactured simply by carving an open groove from a plate-like material or by molding it in a mold, and then closing it with a lid to create a melting section with an internal melting hole. This structure is particularly advantageous when using a unit-type melting device in which melting sections are arranged in parallel according to the amount of resin material to be injected, as described above.

[0022] The cover member of any of the melting parts may also be the closed outer wall of the body part of another melting part, or the outer wall of the melter heater part.

[0023] In the case of a split-type melter for a unit-type injection molding machine as described above, the lid that closes the main body, which has an open channel groove as a melting hole, is not a separate, independent part, but is made to double as the outer wall of the other melting parts and the heater housing part, which not only significantly reduces the number of parts but also makes it possible to make the entire unit more compact.

[0024] Furthermore, the fusion zone is made of cemented carbide.

[0025] Cemented carbide is a sintered body made of tungsten carbide (WC) powder and cobalt (Co) as a binder, and titanium carbide (TiC) or tantalum carbide (TaC) may also be added. If such cemented carbide is used to form the fusion zone, it has high wear resistance due to its high hardness, and is also excellent when injecting resin materials such as high-strength fibers.

[0026] In addition, cemented carbide has a high thermal conductivity, so the melting hole can be sufficiently heated without the heater being heated to a higher temperature than necessary, and this is advantageous in that it allows for rapid and uniform heating control.Furthermore, cemented carbide is produced by compressing a uniform mixture of tungsten carbide (WC) and cobalt (Co) powders using a press or the like to form them, and then sintering them, so even if it has a high hardness, it has the advantage of being easy to process if it has a structure consisting of a main body and a lid, such as the split melter described above.

[0027] In addition, as a melter for another injection molding apparatus, there is provided a melter for an injection molding apparatus that melts a resin material (resin pellets) in a plunger-type injection molding apparatus that does not have a vertical structure resin extrusion screw, and the melter is equipped with: a cylindrical melting portion formed of cemented carbide and having a plurality of melting holes that penetrate vertically inside and whose inner diameter cross-sectional area decreases or at least does not increase from top to bottom; and a heating heater arranged on the outer periphery of the melting portion, and the melting holes have a hole diameter and number that obtain an opening rate that is calculated in advance depending on the resin material and the desired injection amount.

[0028] The melter example for the other injection molding machine described above uses a cylindrical melter similar to the conventional melter, made of cemented carbide. Conventionally, melters have been made of copper (Cu), which has a relatively high thermal conductivity. However, in the case of resin materials such as high-strength fibers, the melter must have high wear resistance, as described above. This requirement can be met by using cemented carbide, which has high strength and thermal conductivity, as the melter material.

[0029] However, cemented carbide is a sintered body formed in a mold, and melting holes must be drilled after cylindrical molding, but because of its low toughness, it is necessary to avoid cracks by narrowing the distance between melting holes too much. Therefore, with this cylindrical melter, an appropriate aperture ratio is calculated in advance according to the resin material and the required injection amount, and the hole diameter and number are controlled to ensure the required aperture ratio, thereby providing a melter for high-strength resin materials while avoiding the drawback of low toughness of cemented carbide.

[0030] The present invention also provides an injection-molded product using a resin material molded by the melter for the injection molding apparatus described above. The resin material may be a long-fiber thermoplastic resin, and the length of the long-fiber thermoplastic resin may be 3 mm or more, preferably 5 mm or more.

[0031] The melter described above has the advantage of being compact and capable of large-volume injection, yet adaptable to various resin materials (resin pellets). This melter also allows for the production of injection-molded products for mass production as general-purpose products, something previously impossible. Long-fiber thermoplastic resins, in particular, have high mechanical strength and light weight, and offer many advantages over metals and conventional resins. Their market is expected to expand in the future. Because this melter has a roughly rectangular casing made of cemented carbide and a melting hole with a rectangular cross section, this melter can easily mass-produce such long-fiber thermoplastic resins. In particular, injection-molded products of long-fiber thermoplastic resins measuring 3 mm or more, preferably 5 mm or more, are evidence that they are manufactured according to the present invention.

[0032] Furthermore, an injection molding apparatus using the melter for injection molding apparatus of the present invention as described above is provided with a melt cone section below the melting section of the melter that receives the resin material discharged from the melt hole and discharges it below, and it is preferable that the melt cone section has an upper inlet that receives the resin material discharged from the melt hole with an inner diameter that is approximately square, and has a through-hole that has an approximately square pyramid shape with its apex at the bottom over the entire area from the inlet to the lower outlet or partway through.

[0033] The melter for an injection molding machine of the present invention described above is connected to a melt cone section that receives (confluent) the molten resin material from the melt section and guides it to a nozzle section that receives (confluent) the molten resin material from the melt section and discharges it into the mold. This melt cone section has a through-hole with an inverted quadrangular pyramid-shaped section whose horizontal cross-sectional area decreases downward from a substantially rectangular inlet on the melt hole side. A melt cone section with this structure has the advantage that, because each melt section is substantially rectangular, the molten resin material from the melt hole can be converged and discharged downward without leakage at the inlet with a substantially rectangular inner diameter.

[0034] Furthermore, in the injection molding apparatus having the melter for the injection molding apparatus described above, it is preferable that the melt cone portion causes the molten resin discharged from the melt holes of the plurality of melting portions across adjacent melting portions arranged in parallel to join with an inlet above the through bore and discharge it from below the through bore.

[0035] In the case where the injection molding apparatus has a structure in which multiple melting sections are arranged in parallel in the width direction, a melt cone section that receives the molten resin material may be provided for each melter, but in this example, a melt cone section may be provided below adjacent melting sections that join the molten resin material discharged from the multiple melting sections and discharge it downward. Such a melt cone section can be easily customized to an injection molding machine that manufactures injection-molded products requiring large volumes of resin by arranging multiple melting sections in parallel, while providing a configuration that makes it easy to control the injection amount.

[0036] The through-hole of the melt cone portion may have a slit shape with its outlet below extending in the width direction of the plurality of melt portions.

[0037] In this case, the width of the slit-shaped outlet of the through-hole of the melt cone portion, which has a lower outlet formed in a slit shape, may change midway along the longitudinal direction of the outlet.

[0038] In the melt cone section described above, it was assumed that its outlet (discharge port) was typically hole-shaped, but if the outlet (discharge port) of the melt cone section is hole-shaped, the outlet of the nozzle (described below) connected to it will also be hole-shaped, and when molten resin material is injected from multiple injection holes in the nozzle, the injected resin material will temporarily separate, then merge, and then cool and solidify, making it prone to weld lines and sometimes resulting in undesirable strength and appearance. In contrast, if the outlet of the melt cone section is shaped like a long slit, the resin material will not be injected separately, preventing the occurrence of weld lines and enabling the production of a final injection-molded product with desirable strength and appearance.

[0039] Furthermore, if the outlet of such a melt cone section is shaped like a slit, the width can be changed along the way. For example, by widening the slit width in the area where you want to increase the thickness of the injection-molded product, the molten resin material will be injected (fall) at the same speed (uniform) in the longitudinal direction, allowing you to produce a molded product with a uniform thickness without the formation of weld lines.

[0040] It is also preferable that melt cone heater sections each accommodating a heater be provided on both sides of the outer wall of each of the melt cone sections so that heat is introduced to the through-hole.

[0041] In the above example, by providing a heater section on the outer wall of the melt cone section similar to that of the melt section, heat is input throughout the entire flow path of the molten resin material from the melt section to when it is injected through the nozzle (described below), preventing the viscosity of the molten resin material from constantly increasing. As a result, there is no need to apply more heat than necessary to the melt section, allowing the injection molding device to operate at a lower power consumption level and reducing unevenness in heat transfer.

[0042] Furthermore, it is preferable that the lower end of the melt cone section is provided with a nozzle section that receives the molten resin material from the outlet of the melt cone section and injects it below, the nozzle section has an internal flow path whose horizontal cross-sectional area decreases from the upper inlet to the lower outlet, and above the internal flow path a seat-facing section is formed into which the lower end of the melt cone section is inserted as a stopper to prevent downward penetration, and the lower end of the melt cone section and the upper end of the nozzle section are connected from their outer peripheries with a connecting jig.

[0043] The melt cone section described above is connected at its lower end to a nozzle section for injecting the molten resin material. The nozzle section attached to the lower end of the melt cone section allows for easy vertical positioning by simply inserting the nozzle section and fastening it with a connecting jig (nut, etc.) after providing a counterbore above the inner flow path that acts as a stopper when the lower end of the melt cone is inserted. The horizontal cross-sectional area of ​​the inner flow path is reduced toward the injection port, allowing the molten resin material to fully merge at the injection port, enabling rapid, large-volume injection. Furthermore, even if the tip of the melt cone section is shortened, it can be securely fastened simply by inserting it above the nozzle section, allowing for the nozzle section itself to be shortened. This eliminates the need for elaborate surface processing, such as tapering the inner flow path, thereby reducing the cost of the nozzle section.

[0044] Furthermore, in the case of the nozzle portion, the lower end of the melt cone portion and the upper end of the nozzle portion are fastened uniformly from the outer periphery, so it can be manufactured by a process of bonding the connecting jig together while facing each other along the central axis, which is advantageous in that it can be manufactured from a super-hard sintered body without significantly increasing processing costs.

[0045] It is also preferable that the outer peripheral wall of the nozzle portion has a diameter that decreases stepwise in the vertical direction.

[0046] In this case, by giving the nozzle section an outer shape that reduces its horizontal cross-sectional area in a stepped manner and reducing the diameter of the lower end of the through-hole in the connecting jig (nut, etc.) between the melt cone section and the nozzle section, a vertical fastening force can be applied approximately uniformly across the entire fastening portion of the connecting jig. While a tapered outer shape would require too tight tolerances and significantly increase costs, a stepped outer shape does not apply radial forces, eliminating the tolerance problem and offering the advantage of extending the life of the connecting jig.

[0047] It is also preferable to insert washers made of a highly thermally conductive metal into the gap between the countersunk portion of the inner flow path of the nozzle portion and the lower end of the melt cone portion, and into the gap between the reduced diameter portion at the lower end of the connecting jig and the stepped portion on the outer periphery of the nozzle portion.

[0048] By inserting washers into the gap between the melt cone portion and the nozzle portion, and the gap between the nozzle portion and the connecting jig (nut, etc.), leakage of molten resin material is suppressed, and a structure with high heat transfer properties can be provided.

[0049] Preferably, heat transfer fins are provided on the outer wall of the connecting jig.

[0050] By providing heat transfer fins on the outer wall of the connecting jig, the outer surface area is increased, which is advantageous in that the cooling and heating effect of the connecting jig is enhanced.

[0051] Furthermore, it is preferable that the surface of the cemented carbide that houses the heating heater in the melting heater section and / or the melt cone heater section is formed with a ceramic insulating layer produced by thermal spraying and a heater layer formed by nickel-based alloy plating on the surface of the insulating layer.

[0052]

[0003] The heater section, which houses (disposes) a heater such as an electric heating wire, is provided with an insulating layer made of thermally sprayed ceramics, and a thin heater layer made of high-resistance nickel-based alloy plating is then provided on top of that, significantly improving heater performance for melting resin materials. Specifically, band heaters have traditionally been used to heat containers, but an air gap with low thermal conductivity exists between the band heater and the melter, which causes problems with heat transfer to the resin material. In contrast, by providing a heater layer made of high-resistance nickel-based alloy plating and an electric heating wire or other heat source on top of the insulating layer in the heater section for the melter and the heater section for the melt cone, no air gap exists between the heater layer and the cemented carbide material, allowing for the formation of an ultra-thin heater layer (e.g., 10 microns) with excellent heat transfer. This is a major advantage in that it allows for the miniaturization of the melter and melt cone, and ultimately allows for the provision of a large-capacity injection molding machine in a narrow space.

[0053] The melter for injection molding of the present invention can provide a plunger-type injection molding device with a vertical structure that does not have a resin extrusion screw, which is capable of uniform and rapid heat input despite low power consumption and can injection mold large volumes of resin material.

[0054]

[0023] Figure 1 shows a first melter example 1 of the present invention, which is composed of three melting sections and a heater housing section. The main body of the four-hole melting section of melter example 1 is shown. The main body of the four-hole melting section of melter example 1 is shown. The heater housing section of melter example 1 is shown. An exploded perspective view showing each component of melter example 2 of the first invention is shown. A melter example 3 of the first invention is shown. (a) and (c) show melter example 1 of the second invention, and (b) and (d) show melter example 2 of the second invention. (a) shows a perspective view of melter example 1 of the second invention, and (b) shows a perspective view of melter example 2 of the second invention. The bottom nozzle provided below the first and second melter examples of the present invention and the heater housing section around the bottom nozzle are shown. (a) shows a top view of each melter constituting melter example 4 of the second invention, and (b) shows a top view of melter example 4, which is a combination of the melters shown in (a). Photographs of a melter 710 as a fourth embodiment of the melter are shown, with (a) being a schematic top view of the melter, (b) being a schematic bottom view showing the opposite side of (a), and (c) being a perspective view in which the melter heater section on the side of the melter 0 can be seen. A schematic vertical cross-sectional view showing the state in which the melt cone section and the nozzle section are connected to the melt section of FIG. 11 is shown, with (a) being connection example 1 and (b) being connection example 2, which is an improvement on (a). A perspective view showing the state in which the melt cone section and the nozzle section of FIG. 12 are connected is shown. A perspective view of the melt cone section as seen from diagonally above right in FIG. 13 is shown. A vertical cross-sectional view of FIG. 13 is shown. 16A is a schematic top view of the single melter shown in FIG. 11, (b) is a schematic top view of the melt cone section arranged across the melter in (a), and (c) is a schematic side view of the melt cone section in (b). A modified example of the outlet of the melt cone section in FIG. 16 is shown from the same perspective and in the same manner as in FIG. 16, where (a) is a schematic top view of the single melter, (b) is a schematic top view of the melt cone section arranged across the melter in (a), and (c) is a schematic side view of the melt cone section in (b). This is a modified example of Figure 17, where (a) is a schematic top view of a single melter, (b) is a schematic top view showing a melt cone section arranged across the melter of (a), and (c) is a schematic side view of the melt cone section of (b).

[0055] In a plunger-type injection molding apparatus that melts resin pellets in a vertical structure without a resin extrusion screw, a collection of resin pellets is pressed by a plunger, melted through multiple melt holes in a melting section, and injected downward, as shown in Patent Document 3, etc. The present invention provides a new melter and an injection molding apparatus equipped with this melter. Specifically, as described above, the present invention provides two types of melters and a melt cone section and a nozzle section of an injection molding apparatus equipped with this melter. Below, an example of a melter having a substantially rectangular parallelepiped shape, other examples of cylindrical melters made of cemented carbide, examples of a melt cone section, examples of a nozzle section, etc. are illustrated and described.

[0056] <<Example 1 of a Melter Having a Rectangular Shape for an Injection Molding Apparatus of the Present Invention>> As a first example of a melter for an injection molding apparatus of the present invention, melter 10 will be described below with reference to Figures 1 to 4 and 11. First, Figure 1 shows melter 10, which is composed of three melting portions 12 and a melter heater portion 14, with (a) being a schematic diagram of melting portion 12a of melter 10 as seen from the side, (b) being a schematic diagram of melting portion 12b of melter 10 as seen from the side, (c) being a schematic diagram of melter 10 as seen from the front, (d) being a schematic diagram of melter 10 as seen from the top, and (e) being a schematic diagram of heater housing portion 14 of melter 10 as seen from the side.

[0057] As shown in the front view (FIG. 1(c)) and the top view (FIG. 1(d)), the melter 10 for the injection molding device has a single housing structure, with a plate-shaped four-hole melting section 12a, a three-hole melting section 12b, and a four-hole melting section 12c stacked and facing each other in the shorter width direction (left and right direction in FIG. 1(c)) from the side to form the melter 12. In addition, as shown in FIG. 1(e), the outer wall side of the melting section 12 is sandwiched from both sides by melter heater sections 14, the surface of which is coated with a plating layer (described below) containing built-in heating wires 16. In addition, as will be described later, the four-hole melting portion 12a, the three-hole melting portion 12b, and the four-hole melting portion 12c are each composed of a main body portion that is open on one side and a lid member that closes it from the opposite side, and in the case of the melter 10 shown in Figure 1, the four-hole melting portion 12a, the three-hole melting portion 12b, and the four-hole melting portion 12c are each composed of lid members 22a, 22b, and 22c that are attached to the main body portion (in this specification, the main body portions of the four-hole melting portions 12a, 12c, and the three-hole melting portion 12b may be simply referred to as the four-hole melting portions 12a, 12c, and the three-hole melting portion 12b, or as the main body portion 12a, 12c, and the main body portion 12b). Below, the four-hole melting portions 12a, 12c, the three-hole melting portion 12b, and the heater accommodating portion 14 will be described in detail.

[0058] Figure 2 shows the main body portions 12a and 12c of the four-hole fusion portion, and Figures 2(a), (c), and (d) are respectively viewed from approximately the same perspective as Figures 1(a), (c), and (d), with (a) showing a side view of the four-hole fusion portion 12a and 12c, (c) showing a front view of the main body portions 12a and 12c of the four-hole fusion portion, (d) showing a top view of the main body portions 12a and 12c of the four-hole fusion portion (the same perspective as the top view of Figure 1(d) rotated 90 degrees clockwise), and (f) showing an oblique view illustrating a groove portion 24 as one of the four holes of the main body portions 12a and 12c of the four-hole fusion portion.

[0059] As can be seen in Figures 2(a) and 2(f), the main bodies 12a and 12c of the four-hole melting section have grooves 24 (the grooves 24 may have portions with no change in area in the vertical direction) formed in a plate-like member so that the area of ​​the horizontal cross section does not increase from top to bottom, forming four melting holes 20. The grooves 24 (melting holes 20) are inclined at the same angle in opposite directions so that the width in the width direction (left-right direction in Figure 2(a)) narrows from above where the resin pellets are introduced. The grooves 24 (melting holes 20) have rectangular recesses formed in the main bodies 12a and 12c, and each groove 24 has a rectangular open channel in horizontal cross section that is open to the side (downward in Figure 2(d)) as shown in Figure 2(d). Four grooves 24 are provided in a row along the width direction by inner frames 18b on both sides of the width direction of each of the main bodies 12a and 12c and outer frames 18a that serve as partitions between the grooves 24.

[0060] Then, by attaching a plate-shaped cover member 22 (see FIGS. 1(a) and 1(c)) to the main body portions 12a and 12c from the side (below in FIG. 2(d)) and closing the grooves 24, four melt holes 22 are formed in the width direction within the melting portions 12a and 12c, each having a square horizontal cross section whose area does not increase from top to bottom (the horizontal cross-sectional area of ​​the lower portion is equal to or less than the horizontal cross-sectional area of ​​the upper portion). In particular, in the example of the four-hole melting portions 12a and 12c in FIGS. 1 and 2, a cemented carbide is used that is formed in a mold from powder such as tungsten carbide (WC) and sintered, as described below. Therefore, the melting holes 20 can be formed by providing open grooves 24 in a plate-shaped member such as the main body portions 12a and 12c.

[0061] Furthermore, because the main bodies 12a and 12c of the melting hole 20 are plate-shaped members with grooves 24, the length in the plate thickness direction (the vertical direction in FIG. 2(d)) is the same from the inlet opening 20a to the outlet opening 20b. As shown in FIG. 2(a), the width direction is linearly inclined from both sides to gradually reduce the width direction, thereby gradually reducing the opening area from the inlet opening 20a with a rectangular cross section to the outlet opening 20b. Since the area of ​​the inlet opening 20a significantly affects the amount of resin pellets that can be introduced into the melting zone 12a, the opening ratio of the inlet opening 20a must be as large as possible, and the thickness of the frame 18 (inner frame 18a, outer frame 18b) at the inlet opening 20a must be thin. In the case of the melting zone 12a, which is made of cemented carbide as described below, the opening ratio of the inlet opening 20a is known to be approximately 58%. In contrast, in a typical conventional cylindrical melting part, when it is made of copper (Cu), the opening ratio is about the same, but when it is made of cemented carbide (WC, etc.), which will be described later, it is known that only a significantly smaller opening ratio (about 28%) can be achieved due to its low toughness. Therefore, the opening ratio of the inlet opening 20a of the melting vessel 12a is large, and this is particularly noticeable when cemented carbide is used as the material.

[0062] Next, Figure 3 shows the main body 12b of the three-hole fusion part, and like Figure 2, Figures 3(a), (c), and (d) are respectively shown from approximately the same perspective as Figures 1(a), (c), and (d), with (a) being a side view of the main body 12b of the three-hole fusion part, (c) being a front view of the main body 12b of the three-hole fusion part, and (d) being a top view of the main body 12b of the three-hole fusion part (same perspective as Figure 2(d)). Note that the perspective view illustrating the groove 25 as one of the three of the main body 12b of the three-hole fusion part is omitted, and instead, refer to Figure 2(f) which shows a perspective view of the groove 24 of the main bodies 12a and 12c of the four-hole fusion part.

[0063] Like the main bodies 12a and 12c of the four-hole fusion section, the main body 12b of the three-hole fusion section has grooves 25 formed so that the width in the width direction (left and right direction in FIG. 3(a)) narrows across the vertical direction of the plate-like member, with inclined surfaces on both sides at the same angle in opposite directions, so that the horizontal cross section does not increase in area from top to bottom (the horizontal cross section area of ​​the lower part is equal to or less than that of the upper part), forming three fusion holes 20. These grooves 25 (fusion holes 21) are also rectangular open channels in the horizontal cross section of the main body 12b that are open to the side (the lower part in FIG. 3(d)), and three grooves 25 are provided in a row along the width direction, each separated by outer parts 19b on both sides of the width direction of the main body 12b and inner frames 19a that separate the grooves 25.

[0064] Then, by attaching a plate-shaped cover member 22 (see FIGS. 1(a) and 1(c)) to the main body portion 12b and closing the groove portion 25, three melting holes 21 are formed in the melting portion 12b, each having a square horizontal cross section and tapering at an equal inclination angle in the width direction. As mentioned above, this configuration is suitable for use with cemented carbide that is molded and sintered using a casting mold.

[0065] Furthermore, the melting hole 21 has a main body 12b in which a groove 25 with a square cross section is provided in a plate-like member, and since the length in the plate thickness direction (the vertical direction in Figure 3(d)) is constant, it is necessary to make the opening rate of the inlet opening 21a as large as possible in order to increase the amount of resin pellets that can be input, and it is also necessary to make the thickness of the frame portion 19 (inner frame 19a, outer frame 19b) at the position of the inlet opening 21a thin, which is similar to the main body portions 12a and 12c of the four-hole melting hole in Figure 2.

[0066] Also, Fig. 4 shows the melter heater portion 14. Like Figs. 2 and 3, Figs. 4(a), 4(c), and 4(d) are taken from substantially the same viewpoints as Figs. 1(a), 1(c), and 1(d), respectively, with Fig. 4(a) being a side view of the melter heater portion 14, Fig. 4(c) being a front view of the melter heater portion 14, and Fig. 4(d) being a cross-sectional view taken along line A-A in Fig. 4(a).

[0067] The melter heater section 14 is made of cemented carbide and comprises a frame 14b along both the top and bottom edges and one side edge of the plate-shaped member, and a heater mounting surface 14a that is flat and lower than the frame 14b. An insulating layer is formed on the heater mounting surface 14a by thermally spraying a ceramic such as alumina (aluminum oxide) onto the polished surface of the cemented carbide. The surface of this insulating layer is then plated with a high-electrical resistance nickel-based alloy, forming a heater layer (not shown) equipped with a heating wire 16, as shown in Figure 1(e). This structure eliminates the air gap between the heater layer and the cemented carbide member, resulting in an ultra-thin heater layer (e.g., 10 microns) with excellent heat conductivity.

[0068] Furthermore, in the heater layer, a heat-resistant insulating film is applied on the nickel-based alloy plating layer to prevent short circuits and electric shock due to exposure of the current-carrying surface. The end of the heating wire 16 has a plate-like piece (see plate-like piece 714c in Fig. 11(c)) protruding from the other side (the right side in Fig. 4(a)) where there is no frame part 14b. When this plate-like piece (714c) is connected to an external power source (not shown), the heating wire 16 and the plating layer generate heat, and the heat is conducted to the entire melter heater part 14, thereby functioning as an ultra-thin heater layer.

[0069] <<Examples 2 to 4 of a Melter Having a Rectangular Parallelepiped Shape for an Injection Molding Apparatus of the Present Invention>> Next, as modifications of the first embodiment of the melter for an injection molding apparatus of the present invention shown in Figures 1 to 4, etc., a melter 110 according to a second embodiment and a melter 210 according to a third embodiment will be described with reference to Figures 5, 6, and 10, respectively. Note that Figure 5 is an exploded perspective view showing the components of the melter 110 for an injection molding apparatus. Figure 6 also shows the melter 210 for an injection molding apparatus, with Figures 6(a), 6(c), and 6(d) being views taken from approximately the same perspective as Figures 1(a), 1(c), and 1(d), respectively. Figure 6(a) is a side view of the three-hole melting portion of the melter 210, Figure 6(c) is a front view of the melter 210, and Figure 6(d) is a top view of the melter 210. 10A shows a top view of a melter 510 as a modified example of the melters 110 and 210 shown in FIGS. 5 and 6, and FIG. 10B shows a top view of a melter 610 as melter example 4, which is a further combination of the melter 510.

[0070] First, as shown in Fig. 5, the melter 110 for an injection molding machine is configured by stacking, from the side (left side of Fig. 5) in the widthwise direction, a three-hole melting section 112a opening to the right, a heater accommodating section 114 consisting of a receiving section 114(1) opening to the right and a plate-shaped lid member 114(2) closing it, and two three-hole melting sections 112b opening to the left. The main sections 112a and 112b of the three-hole melting section have a horizontal cross section whose area does not increase from top to bottom, similar to the main section 12b of the three-hole melting section shown in Fig. 3(a) etc., and form melting holes 120 with grooves that are rectangular open channels opening to the left side. Three melting holes 120 (grooves) are arranged in a row along the widthwise direction, each of which is formed by inner frames 118b on both sides of the main sections 112a and 112c in the widthwise direction and outer frames 118a that serve as partitions between the melting holes 120 (grooves).

[0071] The main body 112a of the leftmost three-hole melting part has melting holes 120 open to the right, and a receiving part 114(1) constituting the melter heater part 114 is disposed on top of it from the right side, with the side wall 114(1)c of the receiving part 114(1) closing the melting holes 120. In this way, the main body 112a and receiving part 114(1) of the three-hole melting part form the melting part 112a having three melting holes 120 inside.

[0072] Next, the melter heater section 114, like the melter heater section 14 in Fig. 4, is composed of the aforementioned receiving section 114(1) that is open to the right and is made up of a frame section 114(1)b that surrounds the three edges of the plate-like member and a heater arrangement surface 114(1)a that is lower than the frame section 114(1) and a plate-like lid member 114(2) that closes it. Similar to the melter heater section 14 in Fig. 4 described above, the heater arrangement surface 114(1)a of the receiving section 114(1) has an ultra-thin heater layer on its surface that is made up of an insulating layer, a plating layer, and an electric heating wire (not shown), and heat from the heater layer is conducted to the entire receiving section 114(1) and lid member 114(2) made of cemented carbide with high thermal conductivity, thereby functioning as a plate-like heater.

[0073] Furthermore, a main body 112b of the three-hole melting section is disposed on top of the heater housing section 114 from the right side. This main body 112b of the three-hole melting section has the same structure as the main body 112a of the three-hole melting section described above, but with the open side reversed left and right, and the three melting holes 120 that open to the left are closed with a cover member 114(2) of the melter heater section 114, thereby forming the melting section 112b having three melting holes 120 therein. Therefore, the melter heater section 114 is sandwiched between the three-hole melting sections 112a, 112b on both the left and right sides and serves as a cover member for both, and heat is conducted near both melting sections 112a, 112b, resulting in good thermal efficiency and further achieving a reduction in the number of components and a compact design.

[0074] 5, a main body 112b of the same three-hole melting part is disposed on the right side of the main body 112b of the three-hole melting part attached to the right of the melter heater 114. In this case, the side wall of the main body 112b of the three-hole melting part also serves as a cover member for the main body 112b of the three-hole melting part on the right side, which again achieves a reduction in the number of parts and size, and also improves heat conduction efficiency because the distance from the melter heater housing 114 can be made shorter.

[0075] Fig. 6 shows a melter 210 as a third embodiment of the melter, which is obtained by further assembling a melter heater portion 114 and a three-hole melting portion 112b to the melter 110 of Fig. 5. Note that Figs. 6(a), (c), and (d) are views taken from approximately the same viewpoint as Figs. 1(a), (c), and (d), respectively, with Fig. 6(a) showing a side view of the main bodies 112a and 112b of the three-hole melting portion of the melter 210, Fig. 6(c) showing a front view of the melter 210, and Fig. 6(d) showing a top view of the melter 210 (from the same viewpoint as the top view of Fig. 1(d) rotated 90° clockwise).

[0076] As shown in the front view of Figure 6(c), the melter 210 is configured by stacking the open side of the receiving portion 114(1) of the melter heater portion 114 of Figure 5, with the left and right sides reversed, on the right side of the side wall of the main body portion 112b of the rightmost three-hole melting portion of the melter 110 shown in Figure 5. Furthermore, the main body portion 112b of the three-hole melting portion is stacked on the right side (outer wall) of the receiving portion 114(1) from the right side. In this melter 210, two units are stacked, each sandwiching the melter heater portion 114 between the three-hole melting portions 112a or 112b on both the left and right sides. All of the melting holes 120 of the four three-hole melting portions 112a or 112b are equidistant from the heater housing portion 114. This achieves a reduction in the number of components and a compact size, as in Figure 5, while also improving thermal efficiency and enabling large amounts of resin pellets to be melted quickly and uniformly.

[0077] 10 (a), two melting heaters 114 sandwich three melting portions 112b, 112c, and 112c. Specifically, the main body 112b of the three-hole melting portion is attached together with the lid member 22 to the right of the melting heater 114, and the main body 112c of the two-hole melting portion is attached together with the lid member 22 to the right of the lid member 22. The main body 112b of the three-hole melting portion is attached together with the lid member 22 to the right of the lid member 22, and the melting heater 114 described above is attached to the right of the main body 112b. The melting holes 120 in the melting portions 112b, 112c, and 112c have approximately rectangular openings similar to the melting holes 120 in FIGS. 5 and 6 and are arranged in the vertical direction (width direction). The melting holes 120 between adjacent melting portions 112b, 112c, and 112c are arranged with a vertical and widthwise offset. In this way, because the rows of melting holes in adjacent melting parts 112b, 112c, 112 are offset from each other, the heat input from the heater housing part does not pass through the air layer or resin material in melting hole 120, as shown by arrow A, but is conducted through the melting part material with high thermal conductivity, such as cemented carbide, which will be described later. For this reason, even if the arrangement is such that it is not directly adjacent to melter heater part 114 as shown in Figure 10, sufficient heat can be conducted to melting hole 120 in central melting part 112c.

[0078] Furthermore, by arranging the melting holes 120 as described above in a staggered arrangement so that the entire melting portion is sandwiched between the melter heater parts 114, it is possible to form a larger unit, melter 610, by combining multiple melter parts 510 as shown in Figure 10 (b), and even if the unit becomes larger, the thermal conductivity does not decrease, making it possible to manufacture a melter for a large-capacity injection molding device using low power.

[0079] FIG. 11 shows a photograph of a melter 710, which is a modification of the melters 10, 110, 210, and 510 described above as the fourth embodiment of the melter. Specifically, (a) is a schematic top view of the melter 710 (similar to FIG. 1(d)), (b) is a schematic bottom view showing the opposite side of (a), and (c) is a perspective view showing the melter heater 514 on the side of the melter 710. This melter 710 is made of a cemented carbide alloy, as described below, and it can be seen that a seven-hole melting portion 712a, a six-hole melting portion 712b, and a seven-hole melting portion 712c are arranged in parallel in order from the side to the short width direction. Furthermore, as described above, a comparison of FIGS. 11(a) and 11(b) reveals that the horizontal cross-sectional area of ​​the inlet opening (inlet port) 720a of each melting hole 720 on the top surface decreases toward the outlet opening (outlet port) 720a at the bottom.

[0080] Example Materials for the Melters Shown in the First to Fourth Embodiments of the Injection Molding Apparatus of the Present Invention The melting portions 12, 112, 212, 712 and the melting heater portions 14, 114, 714 of the melters 10, 110, 210, 510, 710 described above are manufactured from cemented carbide. Specifically, a uniform mixture of tungsten carbide (WC) and cobalt (Co) powder is pressurized using a press or the like to form a rough shape, pre-sintered, and subjected to a binder removal process. After pre-sintering, melting holes 20, 21, 120, 712 and positioning pinholes (not shown) are formed in the relatively easily processable pre-sintered body by cutting and drilling processes (machining), and the resulting pre-sintered body is then sintered at around 1300°C. Thereafter, the fusion holes 20, 21, 120, 720 and mating surfaces of the sintered body are machined by grinding and polishing processes, and then the mating surfaces are heated to cause interpenetration of the cemented carbide, resulting in diffusion bonding and forming the final product.

[0081] The melting parts 12, 112, 212, 712 and melter heater parts 14, 114, 714 made of cemented carbide have high hardness, which makes them highly wear-resistant and excellent for injecting resin materials such as high-strength fibers. Also, because of their high thermal conductivity, the melting holes 20, 21, 120, 720 can be sufficiently heated without the need to increase the heat input temperature higher than necessary through the heater layer formed by the heating wire and plating layer in the melter heater parts 14, 114, 714, allowing for rapid and uniform heating control. Furthermore, because cemented carbide is manufactured by molding a powder mixture using a press or the like and sintering it, the melting parts 12, 112, 212, 712 and melter heater parts 14, 114, 714 with open structures such as the main body and lid are easy to process and suitable for mass production, despite their high hardness.

[0082] <<Examples 1 and 2 of Melters for Other Injection Molding Apparatuses>> Next, melting portions 312 and 412 of melters 310 and 410 as melters for other injection molding apparatuses will be described with reference to Figures 7 and 8. Figure 7(a) shows a front view of melting portion 312, Figure 7(b) shows a top view of melting portion 312, Figure 7(c) shows a front view of melting portion 412, and Figure 7(d) shows a top view of melting portion 412. Figure 8(a) shows a perspective view of melting portion 312 as seen from the top surface side, and Figure 8(b) shows a perspective view of melting portion 412 as seen from the top surface side.

[0083] 7 and 8, the melting portions 312, 412 of these melters 310, 410 are each an integral, vertically extending, approximately cylindrical shape, extending in the vertical direction, and extending cylindrically from the upper portion of the main body 312a, 412a to the lower tip portion 312c, 412c, with a flange 312b, 412b projecting radially outwardly and expanding in diameter in an annular shape between the main body and the lower tip portion 312a, 412a to secure space for attaching a heater (heater housing portion) to the outer peripheral wall or for protecting the heater. Furthermore, the melting portions 312, 412 are provided with a plurality of melting holes 320, 420 in the shape of truncated cones that penetrate from the upper end to the lower end and gradually taper. It should be noted that the vertical direction of the molten parts 312, 412 in the side views shown in Figures 7(b) and 8(d) is actually the opposite of the vertical direction, and although Figures 7(a) and 8(c) show top views of the molten parts 312, 412, the following description will be based on the vertical positions on the drawings.

[0084] Each of the melt holes 320 and 420 has one melt hole at the axial center, and multiple melt holes 420 are provided concentrically at equal distances from the axial center in the radial direction. Furthermore, there are more melt holes 420 than melt holes 320. Specifically, as shown in Figures 7(a) and 7(c), the melt hole 320 has one melt hole at the axial center and five melt holes and eleven melt holes, respectively, provided at equal intervals along two concentric circles radially outward from the melt hole at the axial center, which are spaced at equal distances in the radial direction. The melt holes 420 have one melt hole at the axial center and five melt holes, twelve melt holes, and eighteen melt holes, respectively, provided at equal intervals along three concentric circles radially outward from the melt hole at the axial center, which are spaced at equal distances in the radial direction. Furthermore, the underside of each tip portion 312c, 412c is not flat, but is provided with guide portions 312d, 412d that surround the periphery of each melt hole 320, 420 and gently guide the resin pellets to the melt holes 320, 420. When resin pellets (resin material) are introduced into each melt hole 320, 420, these guide portions 312d, 412d allow them to enter the melt holes 320, 420 evenly and be transferred at approximately equal pressure.

[0085] The melting portions 312, 412 each have an outer shape formed from cemented carbide and are perforated with melting holes 320, 420. Specifically, similar to the melting devices 10, 110, and 210 for the injection molding apparatus of the first aspect of the present invention, a uniform mixture of tungsten carbide (WC) and cobalt (Co) powder is pressurized using a press or the like to form a rough cylindrical shape including a flange, which is then pre-sintered and de-bindered. After pre-sintering, the melting holes 320, 420 and guide portions 312d, 412d are formed in the relatively easily processable pre-sintered body through a drilling process and a cutting process (machining), and the pre-sintered body is then sintered at around 1300°C. The sintered product is then polished to form a final product made of cemented carbide.

[0086] However, because cemented carbide has low toughness, it is necessary to avoid cracking by narrowing the distance between the melt holes too much. For this reason, the appropriate aperture ratio is calculated in advance according to the resin material and the required injection amount, and the hole diameter and number are controlled to ensure the required aperture ratio.

[0087] In the case of the fusion zones 312 and 412, the aperture ratios of the fusion holes 320 (15 holes) and 420 (37 holes) at the tip ends 312c and 412c, which are the entrance openings, are approximately 28% and 54%, respectively. Therefore, the fusion zone 412 with a larger number of holes has a larger aperture ratio than the fusion zone 312 with a smaller number of holes, and it is clear that the fusion zone 412 is preferable from the viewpoint of increasing the injection volume. On the other hand, considering that cemented carbide is a low-toughness material, drilling the fusion zone 412 with a larger number of holes is more difficult or impossible. Furthermore, cemented carbide is formed from a mixed powder of tungsten carbide (WC) and cobalt (Co). The higher the tungsten carbide (WC) ratio and the lower the cobalt (Co) ratio, the higher the thermal conductivity tends to be. It is also known that the cobalt (Co) ratio and particle size affect the flexural strength (MPa). Therefore, an optimal design must be made in advance or an optimal melting portion must be selected in order to ensure the maximum possible opening rate that can be processed depending on the composition of the resin material and cemented carbide to be melted and the required injection amount.

[0088] <<Peripheral Devices (Melt Cone Unit and Nozzle Unit) of Melter for Injection Molding Apparatus of the Present Invention>> Figure 9 shows a melt cone unit 30 provided below the approximately rectangular parallelepiped melter 10, 110, 210, 510, 610, 710 shown in Figures 1 to 6 and 10, and a melt cone heater unit 40 disposed around the melt cone unit 30. (a) is a schematic front vertical cross-sectional view of this, and (b) is a schematic top view of the melt cone unit 30.

[0089] The melt cone section 30 receives (combines) the molten resin material discharged from the multiple melt holes 20, 21, 120, 720 of each of the melters 10, 110, 210, 510, 610, 710 and guides it to a nozzle section (described later) that injects it to the outside. The melt cone section 30 is composed of an outer peripheral wall 30a attached below the melters 10, 110, 210, 510, 610, 710 with a connecting jig such as a nut (see reference numeral 50 described later for a detailed example), and a through-hole 30b that receives (combines) the resin material discharged from the melt holes 20, 21, 120, 720 from an upper inlet 30d, guides it downward, and discharges it to the outside (nozzle section 60 described later) from an outlet 30c located at the lower center or the like.

[0090] The specific structures of the melt cone portion 30 and the nozzle portion 60 that injects the molten resin material discharged from the melt cone portion 30 to the outside will be described below by way of example.

[0091] 12A and 12B are schematic cross-sectional views showing the state in which the melt cone portion 30 and the nozzle portion 60, 160 are connected by connecting jigs 50, 150 below the melting portion 712 in FIG. 11, with (a) showing connection example 1 and (b) showing connection example 2, which is an improvement over (a). Also, FIG. 13 is a perspective view showing the state in which the melt cone portion 30 and the nozzle portion 60 in FIG. 12 are connected, FIG. 14 is a perspective view of the melt cone portion 30 viewed from diagonally above right in FIG. 13, and FIG. 15 is a cross-sectional view of FIG. 13.

[0092] In both connection example 1 (see Figure 12(a) and Figures 13 to 15) and connection example 2 (see Figure 12(b) and Figures 13 to 14), the melt cone section 30 receives (merges) the molten resin material discharged from the above-mentioned melt holes 20, 21, 120, and 720 from the upper inlet 30d into the through-hole 30b, and guides it downward. The upper part of this through-hole 30b becomes an inverted cone inner hole 30b1 whose inner diameter is approximately quadrangular pyramid-shaped (including a downward-facing roof shape), tapering downward as its horizontal cross-sectional area decreases, and the lower end of the inverted cone inner hole 30b1 connects to a cylindrical inner hole 30b2 of the same inner diameter, from which the molten resin material is discharged from the lower end.

[0093] As shown in Figure 13, the melt cone unit 30 has melt cone heaters 40 on both outer walls. Like the melter heaters 14, 114, and 714 described above, the melt cone heaters 40 are made of cemented carbide and comprise a frame 40b and a heater mounting surface 40a lower than the frame 40b. The heater mounting surface 40a is covered with an insulating layer sprayed with a ceramic such as alumina (aluminum oxide), and a heater layer plated with a nickel-based alloy and fitted with a heating wire (not shown). Furthermore, a heat-resistant insulating film is applied to the nickel-based alloy plating layer. Similar to the melter heaters 14, 114, and 714 described above, plate-like pieces 40c protrude from the area where the frame 40 is not present, connecting power from a power source to the heating wire (not shown) on the heater layer.

[0094] The molten resin material discharged from the melt cone portion 30 is received within the nozzle portions 60, 160. Both the nozzle portion 60 in Connection Example 1 (FIGS. 12(a), 13-15) and the nozzle portion 160 in Connection Example 2 (FIGS. 12(b), 13-14) have an internal flow path whose horizontal cross-sectional area decreases from the upper inlet 60e, 160e toward the lower outlet 60d, 160d, and the lower end of the melt cone portion 30 is inserted into a counterbore portion 60a, 160a formed above the internal flow path as a stopper to prevent downward penetration. The lower end of the melt cone portion 30 and the upper end of the nozzle portion 60, 160 are fastened together by nuts (connecting jigs) 50, 150 from the outer peripheries of both.

[0095] Next, in Connection Example 1 (FIGS. 12(a) and 13 to 15), the upper portion 60b of the nozzle portion 60 is cylindrical and has a constant outer diameter up to approximately the height of the counterbore portion 60a, and the outer peripheral wall of the lower portion 60c and the inner peripheral wall of the lower end portion 50b of the nut 50 are tapered. In contrast, in Connection Example 2 (FIGS. 12(b) and 13 to 14), the upper portion 160b is cylindrical and has a constant outer diameter up to approximately the height of the counterbore portion 160a, but its height is shorter than Connection Example 1 (arrow Z1<Z2 in FIG. 12), and the outer diameter of the outer peripheral wall of the lower portion 160c is reduced in a stepped manner relative to the upper portion 160b. Accordingly, the inner peripheral wall of the lower end portion 150b of the nut 150 also reduces in diameter. Therefore, in Connection Example 2, the fastening force of the nut 150 acts substantially uniformly in the vertical direction over the entire fastening portion of the nut 150, and no fastening force acts in the radial direction, resulting in a structure in which tolerances are not too tight.

[0096] In connection example 2 (FIG. 12(b), FIGS. 13-14), a first washer 70a and a second washer 70b made of a highly thermally conductive metal are inserted into a gap Z3 between the counterbore portion 160a of the inner flow path of the nozzle portion 160 and the lower end of the melt cone portion 30, and into a gap Z4 between the reduced diameter portion of the lower end 150b of the nut 150 and the stepped reduced diameter lower portion 160c on the outer periphery of the nozzle portion 160, thereby preventing leakage of the molten resin material. Note that the materials for the first washer 70a and the second washer 70b are typically inexpensive tough pitch copper or pure copper, which has the advantages of high thermal conductivity and softness, which allows for good interface compatibility and prevents heat retention.

[0097] The nuts 50 and 150 each have grooves on their outer walls, which increase their external surface area and form heat transfer fins 50a and 150b that enhance the cooling and heating effect. The nuts 50 and 150 are made of a material selected from chromium copper, a Cu alloy with high thermal conductivity and high strength, or a cemented carbide alloy, which has lower thermal conductivity than chromium copper but high wear resistance. Furthermore, the melt cone 30 does not require much wear resistance or thermal conductivity from the molten resin material, so inexpensive high-speed steel may be selected instead of cemented carbide.

[0098] Furthermore, the melt cone section 30 described with reference to Figures 12 to 15 has shown an example in which a single melt cone section 30 is connected to each single melter 710, but when forming a melter 810 in which multiple (three) melters 710 are arranged in parallel as shown in Figures 16 to 18, the melt cone section 30 may be connected across adjacent melters 710, and the molten resin material from the melt holes 720 of the three melters 710 may be received (merged) together.

[0099] First, Fig. 16(a) is a schematic top view of the single melter 710 shown in Fig. 11. Fig. 16(b) is a schematic top view showing three melters 710 of (a) arranged in parallel, with the melt cone section 130 arranged across the three melters 710. The melters 710 are shown in perspective, and the melt cone section 130 is shown with its through-hole 130b and outlet 130c indicated by thick lines. Furthermore, Fig. 16(c) is a schematic side view to help understand the position and size of the melt cone section 130 shown in the schematic top view of (b).

[0100] In this melt cone section 130, molten resin discharged from the melt holes 720 of three adjacent melt sections 710 merges into an inlet 130d above the through-hole 130b of one melt cone section 130 and is guided downward through the through-hole 130b. The through-hole 130b has an inverted cone shape with a reduced horizontal area and a downward-facing roof shape that is closed vertically at the bottom. Two outlets 130c (a first outlet 130c1 and a second outlet 130c2) are provided at both ends of the ridge of the roof. The molten resin material is discharged from the first outlet 130c1 and the second outlet 130c2 into a nozzle section (not shown). When using this type of melt cone section 130, several melt cone sections 130 are prepared, the melter 710 is connected according to the desired injection amount, and melt cone sections 130 are arranged across them. This allows for easy production of injection-molded products while customizing the injection amount of large volumes of resin.

[0101] Also provided are melt cone sections 230 having slit-shaped outlets and a modified melt cone section 330, as other examples of melt cone sections connected across multiple adjacent melters 710. Figures 17 and 18 show the melt cone sections 230, 330 from the same perspective and in the same manner as in Figure 16. Specifically, Figures 17(a) and 18(a) show schematic top views of a single melter 710, Figures 17(b) and 18(b) show schematic top views illustrating how the melt cone section 130 is arranged across three melters 710, and Figures 17(c) and 18(c) show schematic side views to help understand the position and size of the melt cone section 130.

[0102] First, in the melt cone section 230, as shown in Figures 17(b) and (c), a single melt cone section 230 is connected across three melters 710, as in the case of Figure 16, but the inlet 230c of the through hole 230b of the melt cone section 230 extends in the form of a slit of approximately the same width along the entire downward roof at the bottom of the through hole 230b.

[0103] If the outlet 230c is shaped like a slit, when the molten resin material is injected, the injected resin material is released without separating, so that the molded product is less likely to have weld lines and has high strength.

[0104] On the other hand, the melt cone portion 330 also has a slit-shaped outlet 330c, but as shown in Figures 19(b) and 19(c), the slit width of the outlet 330c changes midway along its length. Specifically, the outlet 330c is formed by a first outlet 330c1, which has a narrow slit width that is roughly the same, and a second outlet 330c2, which has a wider slit width than the first outlet 330c. Although not shown, the slit width of the outlet 330c may also be continuously changed.

[0105] When the slit width is changed in this way, even if the speed of the molten resin material is made uniform, parts with wider slit widths can be placed in areas where the thickness of the molded product is desired to be increased, and parts with narrower slit widths can be placed in other areas to reduce the thickness of the molded product, making it possible to produce uniform molded products without the occurrence of weld lines.

[0106] Various embodiments of the present invention have been described above, but the embodiments shown in this specification and the drawings are merely examples of the present invention, and it will be apparent to those skilled in the art that various other improvements and modifications exist from the concept and teachings of the claims.

[0107] 10,110,210,310,410,510,610,710,810 Melter 12,112,212,312,412,712, Melting portion 14,114,714 Melter heater portion 14a,714a Heater arrangement surface 16 Heating wire (heater) 18,19,118 Frame portion 20,21,120,320,420,720 Melting hole 30,130,230,330 Melt cone portion 30b,130b,230b,330b Through-hole 30c,130c,230c,330c, Outlet 130c1 First outlet 130c2 Second outlet 330c1 Narrow width 330c2 Wide width portion 30d, 130d, 230d, 330d Inlet 40 Melt cone heater portion 50, 150 Connecting jig (nut) 50a, 150a Fin 60, 160 Nozzle portion 70 Washer 80 Heating means Z3, Z4 Gap

Claims

1. A melter for an injection molding device that melts a resin material in a plunger-type injection molding device that does not have a vertical resin extrusion screw, the melter having a rectangular casing structure, the melter having a melting section having a plurality of melting holes that penetrate vertically inside the melting section and whose area does not increase from top to bottom, and a melting section heater section that is disposed on one outer wall so as to input heat at least up to the lower part of one side of the outer wall of the width length of the melting section, and that houses a heater.

2. The melter for an injection molding apparatus according to claim 1, wherein the melting portion is made of a cemented carbide.

3. A melter for an injection molding apparatus as described in claim 1, further characterized in that the melter heater portion is arranged on both outer walls of the long width of the melt portion, thereby sandwiching the melt portion from the short width side.

4. A melter for an injection molding apparatus as described in claim 3, characterized in that the melter comprises a plurality of melting sections and the melter heaters sandwiching them from the narrow width direction, the outer walls of which are arranged in parallel in the narrow width direction.

5. A melter for an injection molding apparatus as set forth in any one of claims 1 to 4, characterized in that the multiple melt holes which the melting part has inside each have substantially identical substantially rectangular horizontal cross sections, are arranged in a row along the width direction, and are inclined so that the horizontal cross-sectional area of ​​the lower part is equal to or less than the horizontal cross-sectional area of ​​the upper part.

6. A melter for an injection molding apparatus as described in claim 3, characterized in that the melt holes in the melt portion have substantially the same substantially rectangular horizontal cross section and are arranged in a row along the width direction, and the melt holes of adjacent melt portions are arranged with a shift from each other in the width direction.

7. A melter for an injection molding apparatus as described in any one of claims 1 to 6, characterized in that the melting portion comprises a main body having a plurality of grooves that are open on one side and extend vertically, and an outer wall that is closed on the opposite side, and a lid member that is attached opposite to the one side of the main body and closes the grooves of the main body, and when closed, a melting hole is formed by the grooves of the main body and the lid member.

8. A melter for an injection molding apparatus as described in claim 7, characterized in that the cover member of any of the melting sections is a closed outer wall of a main body section of another melting section, or is an outer wall of a heater section for the melter.

9. An injection-molded product using a resin material molded by the melter for an injection molding apparatus according to any one of claims 1 to 8.

10. The injection molded article according to claim 9, wherein the resin material is a long fiber thermoplastic resin.

11. An injection molding apparatus comprising a melt cone section below the melt section of a melter for an injection molding apparatus as described in any one of claims 1 to 8, which receives resin material discharged from a melt hole and discharges it below, wherein the melt cone section has an upper inlet that receives the resin material discharged from the melt hole with an inner diameter that is approximately rectangular, and the entire area from the inlet to the lower outlet has an approximately square pyramid shape or a downward-facing roof shape with its apex facing downward.

12. In an injection molding apparatus having a melter for an injection molding apparatus as described in claim 4, the melt cone portion causes the molten resin discharged from the melt holes of the plurality of melting portions across a plurality of adjacent melting portions arranged in parallel to merge with an inlet above the through hole and discharge it from below the through hole, characterized in that the melt cone portion causes the molten resin discharged from the melt holes of the plurality of melting portions to merge with an inlet above the through hole and discharge it from below the through hole.

13. The injection molding apparatus according to claim 12, wherein the through hole of the melt cone portion has a lower outlet formed into a slit shape extending in the width direction of the multiple melt portions.

14. The injection molding apparatus according to claim 13, characterized in that the through hole of the melt cone section, whose lower outlet is formed in a slit shape, has a width of the slit-shaped outlet that changes midway along the longitudinal direction of the outlet.

15. An injection molding apparatus as described in any one of claims 11 to 14, characterized in that a melt cone heater section is provided on both sides of the outer wall of each of the melt cone sections, the melt cone heater section housing a heater so that heat reaches the through hole.

16. An injection molding apparatus as claimed in any one of claims 11 to 15, characterized in that the lower end of the melt cone section is provided with a nozzle section which receives molten resin material from the outlet of the melt cone section and injects it downward, the nozzle section having an internal flow passage whose horizontal cross-sectional area decreases from the inlet at the upper side towards the outlet at the lower side, and a seat groove section is formed above the internal flow passage as a stopper for preventing downward intrusion into which the lower end of the melt cone section is inserted, and the lower end of the melt cone section and the upper end of the nozzle section are connected at their outer peripheries by a connecting jig.

17. The injection molding apparatus according to claim 16, wherein the outer peripheral wall of the nozzle portion tapers in a stepped manner in the vertical direction.

18. An injection molding apparatus as described in claim 16 or 17, characterized in that washers made of highly thermally conductive metal are inserted and arranged in the gap between the seat facing portion of the inner flow path of the nozzle portion and the lower end of the melt cone portion, and in the gap between the reduced diameter portion of the lower end of the connecting jig and the stepped portion on the outer periphery of the nozzle portion.

19. The injection molding apparatus according to any one of claims 16 to 18, characterized in that fins for heat transfer are provided on the outer wall of the connecting jig.

20. An injection molding apparatus characterized in that the surface of the cemented carbide that houses the heating heater in the melting heater section as described in claim 1 and / or the melt cone heater section as described in claim 15 is formed with a ceramic insulating layer produced by thermal spraying and a heater layer formed by nickel-based alloy plating on the surface of the insulating layer.

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