Hot-runner nozzle, injection molding die, manufacturing method of resin molded product, and manufacturing method of hot-runner nozzle

Abstract

To develop a hot-runner die that is capable of suppressing temperature drop at a tip of a hot-runner nozzle, is highly durable, and is capable of manufacturing at a low cost.SOLUTION: There is provided a hot-runner nozzle, comprising: a nozzle body that is a tube defining a flow path for a molten resin; a gate that is a connection part of a cavity defined in a die and the nozzle body; a valve pin that opens and closes the gate; and a heater that is attached to an outer periphery of the nozzle body, wherein the heater is attached to at least a part of an outer periphery of a straight pipe portion, the heater is not attached to at least a part of a tapered portion, and a plurality of highly thermally conductive materials made of a material having a higher thermal conductivity than a material of a base portion of the nozzle body are installed inside the nozzle body from the straight pipe portion in which the heater is attached to the outer periphery to at least a part of the tapered portion in which the heater is not attached to the outer periphery.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a mold for injection molding plastics and the like, and particularly to a hot runner nozzle and an injection molding mold equipped with the same.

Background Art

[0002] As molding molds for injection molding thermoplastic resins such as plastics, cold runner molds and hot runner molds are known. The cold runner mold has the advantage of a simple structure, but since the resin solidifying in the runner part becomes waste material, it is desirable to use a hot runner mold with less resin waste material from the viewpoints of improving economy and reducing environmental load. By using a hot runner mold in which all of the runner parts are heated, a resin molded product can be obtained with almost no generation of resin waste material.

[0003] Although it varies depending on the type of molding material and molding conditions, generally, when the injection molding machine is operating stably and continuously for molding, the temperature of each part of the hot runner body does not change significantly, and problems such as the occurrence of appearance defects in the molded product are unlikely to occur. On the other hand, when some trouble occurs during continuous molding, for example, when a chuck error occurs when taking out the molded product from the mold using a take-out machine, continuous molding may be temporarily stopped for about several minutes to deal with the trouble. Then, the balance between the amount of heat flowing into the hot runner and the amount of heat flowing out changes, and the temperature distribution in the hot runner body can change from the steady state during continuous operation. Specifically, there is a high possibility that the temperature of the body tip portion close to the cavity will decrease.

[0004] After dealing with the trouble and restarting continuous molding, it is necessary to perform molding for adjustment, for example, several shots, so that the temperature distribution at various locations of the hot runner body returns to the steady state and stabilizes.

[0005] During the shot for adjustment, since the temperature of the lowered body tip has not fully recovered, a decrease in the fluidity of the resin or solidification may occur. When the fluidity of the resin decreases, transfer defects may occur where the shape of the mold forming surface is not faithfully transferred to the resin molded product, or flow marks may appear on the appearance of the resin molded product. Also, if the solidified resin clogs the gate, a short shot may occur because a sufficient amount of resin is not injected into the cavity.

[0006] To suppress the decrease in the temperature of the resin near the tip of the hot runner body, it may be considered to further heat the body and keep the temperature high. However, the temperature outside the tip rises excessively, which may cause decomposition and deterioration of the resin. The generation of silver streaks due to the generation of gas by thermal decomposition, the generation of black streaks due to carbonization of a part of the resin, and the occurrence of mold release defects due to changes in the physical properties of the resin may occur.

[0007] Patent Document 1 describes a hot runner nozzle including a cylindrical member in which a flow path for the molten resin is formed and an outer layer formed in more than half of the side surface region of the cylindrical member, and the thermal conductivity of the material of the outer layer is greater than the thermal conductivity of the material of the cylindrical member.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] In the hot runner nozzle described in Patent Document 1, by arranging a high thermal conductivity material in more than half of the side surface region of the cylindrical member, it is possible to reduce the temperature drop at the nozzle tip and the temperature variation across the entire nozzle, and an effect of suppressing the occurrence of molding defects and appearance defects of the molded product during continuous operation can be expected.

[0010] In Patent Document 1, since a high thermal conductivity material, which is a different material, is arranged in the majority region of the side surface of the cylindrical member, a hot runner nozzle is manufactured using laser cladding or thermal diffusion bonding. However, a relatively special processing apparatus is required, and the manufacturing cost does not necessarily become low.

[0011] Further, when a high thermal conductivity material with a relatively low hardness is used as the outer layer, when a load is applied during apparatus assembly or during apparatus use, the portion in contact with other members is likely to undergo plastic deformation. For this reason, the positional accuracy of the hot runner nozzle is likely to decrease, and the durability of the apparatus is not necessarily sufficient.

[0012] Also, in Patent Document 1, regarding how to control the temperature of the hot runner nozzle while temporarily stopping the continuous molding to deal with troubles and the like, no study has been made. Therefore, there has been a demand for a hot runner mold that can suppress a temperature drop at the tip of the hot runner nozzle, has excellent durability, and can be manufactured at low cost.

Means for Solving the Problems

[0013] One aspect of the present invention includes a nozzle body that is a cylinder defining a flow path for molten resin, a cavity defined in a mold, a gate as a connection portion between the nozzle body and the cavity, a valve pin that can advance and retreat in the cylinder to open and close the gate, and a heater attached to the outer periphery of the nozzle body. The flow path includes a straight pipe portion with a constant flow path cross-sectional area and a tapered portion where the flow path cross-sectional area decreases toward the gate. The heater is attached to at least a part of the outer periphery of the straight pipe portion, and the heater is not attached to at least a part of the tapered portion. Inside the nozzle body, a plurality of high thermal conductivity materials made of a material having a higher thermal conductivity than the material at the base of the nozzle body are installed from the straight pipe portion with the heater attached to its outer periphery to at least a part of the tapered portion where the heater is not attached to its outer periphery. This is a hot runner nozzle characterized by the above.

Effects of the Invention

[0014] According to the present invention, it is possible to provide a hot runner mold that can suppress a temperature drop at the tip of a hot runner nozzle, has excellent durability, and can be manufactured at low cost.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Mode for Carrying Out the Invention

[0016] Referring to the drawings, a mold and an injection molding apparatus according to an embodiment of the present invention will be described. The following embodiments are illustrative, and for example, regarding the detailed configuration, those skilled in the art can appropriately modify and implement it without departing from the gist of the present invention.

[0017] In the drawings referred to in the following description of the embodiments and examples, unless otherwise specified, elements denoted by the same reference numerals have the same functions. In the drawings, when a plurality of the same elements are arranged, the assignment of reference numerals and their descriptions may be omitted. Also, for the convenience of illustration and description, the drawings may be schematically represented, so the shapes, sizes, arrangements, etc. of the elements shown in the drawings do not necessarily exactly match the actual objects.

[0018] [Embodiment 1] (Device Configuration) FIG. 5 is a schematic cross-sectional view showing the overall configuration of an injection molding apparatus (injection molding mold) according to Embodiment 1. FIG. 5 is a schematic diagram, and details such as bolts for fastening mold parts, bolt holes, wiring of heaters and thermocouples, water pipe piping, air piping, etc. are omitted from the illustration.

[0019] The mold 1 is composed of a fixed mold 2 and a movable mold 3. The fixed mounting plate 4 of the fixed mold 2 is attached to the fixed platen 51, and the movable mounting plate 9 of the movable mold 3 is attached to the movable platen 52. The fixed mold 2 includes a fixed mounting plate 4 and a fixed mold plate 5 attached to the fixed mounting plate 4. A hot runner 20 is attached between the fixed mounting plate 4 and the fixed mold plate 5.

[0020] The movable mold 3 includes a movable mounting plate 9, a spacer block 8 attached to the movable mounting plate 9, a receiving plate 7, and a movable mold plate 6. In the space surrounded by the spacer block 8, an upper ejector plate 11 and a lower ejector plate 10 are arranged, and the upper ejector plate 11 and the lower ejector plate 10 sandwich and support the flange portions of two ejector pins 12. When the ejector rod 57 presses the lower ejector plate 10, the two ejector pins 12 sandwiched between the lower ejector plate 10 and the upper ejector plate 11 are configured to protrude into the two cavities 16 in conjunction with the lower ejector plate 10.

[0021] In FIG. 5, a pair of molds capable of forming two cavities 16 is illustrated, but the number of cavities in the embodiment is not limited to this. The internal space of the cavity 16 is defined by a fixed cavity insert 13 set in the recess of the fixed mold plate 5 and a movable core insert 14 set in the recess of the movable mold plate 6 abutting against each other at the parting line surface 15. Tubes 17 through which a temperature-controlled cooling medium (e.g., water) flows are provided in the fixed cavity insert 13, the movable core insert 14, the fixed mounting plate 4, the fixed mold plate 5, etc., and each part of the mold can be cooled. In particular, by cooling the fixed cavity insert 13 and the movable core insert 14 when the molten resin is injected into the cavity 16, the molten resin 50 in the cavity 16 can be quickly cooled and solidified.

[0022] Next, a molten resin supply system for injecting the molten resin into the cavity 16 via the hot runner 20 will be described. At the front of an injection cylinder 53 capable of injecting the molten resin, a nozzle 55 with a convex tip having an R shape is attached. The tip of the nozzle 55 is in close contact with a sprue bushing 21 having a recess with an R shape. The sprue bushing 21 is an inlet to the hot runner 20. When the molten resin 50 in the injection cylinder 53 is pushed out by a screw 54, the molten resin 50 is injected into the hot runner 20 from the sprue bushing 21.

[0023] The flow path 56 of the molten resin formed in the hot runner 20 branches at the manifold 22 connected to the sprue bush 21, and each branched flow path 56 is connected to the cavity 16 through the inside of the body 23 of the hot runner nozzle. The flow path 56 communicates with the gate 31 (FIG. 1), which is the injection port to the cavity 16, at the tip of the body 23. The body 23 is supported by the fixed mold plate 5 and the fixed cavity block 13. Incidentally, the gate 31 may be referred to as a connecting portion that connects the cavity defined in the mold and the nozzle body, and the body 23 may be referred to as the base of the nozzle body.

[0024] A valve pin 24 that can advance and retreat is incorporated in the body 23 of each hot runner nozzle to open and close the gate 31, which is the injection port of the molten resin into the cavity 16. The valve pin 24 is fixed to the fixed plate through the air cylinder 25. The fixed plate corresponds to a piston for driving the valve pin 24, and can open and close the gate 31 by advancing and retreating the valve pin 24 according to the air pressure supplied from the air controller 58. A temperature measuring means (for example, a thermocouple) and a heater are attached to each body 23 as will be described later, and these are connected to the temperature control unit 59.

[0025] (Procedure of resin molding) FIGS. 1 and 3 show enlarged cross-sectional views of the vicinity of the body 23 of the hot runner 20. FIG. 1 shows a state in which the opening of the gate 31 is closed by the valve pin 24, and FIG. 3 shows a state in which the valve pin 24 has retreated and the opening of the gate 31 is open, and the molten resin is filled in the flow path 56 or the cavity 16.

[0026] When high-pressure air is injected from the air controller 58 shown in FIG. 5 into the space on the fixed platen 51 side of the air cylinder 25, the valve pin 24 moves in the direction approaching the cavity 16, and the opening of the gate 31 is closed, resulting in the state shown in FIG. 1.

[0027] On one hand, when high-pressure air is injected from the air controller 58 shown in Fig. 5 into the space on the manifold 22 side of the air cylinder 25, the valve pin 24 moves in a direction away from the cavity 16, the gate 31 opens, and the state shown in Fig. 3 is reached.

[0028] When the molten resin 50 in the injection cylinder 53 as the supply part is pushed out by the screw 54 with the gate 31 open, the molten resin 50 passes through the flow paths 56 of the molten resin in the sprue bush 21, the manifold 22, and the body 23, and is filled into the cavity 16 from the gate 31. When the cavity 16 is filled with the molten resin 50 and the filling is completed, the gate 31 is closed. That is, high-pressure air is injected from the air controller 58 into the space on the fixed platen 51 side of the air cylinder 25, and the state shown in Fig. 1 is reached.

[0029] To cool the molten resin 50 filled in the cavity 16, a temperature-controlled medium (such as water) is passed through the pipes 17 installed on the fixed cavity block 13 and the movable core block 14 to solidify the molten resin 50 in the cavity 16. After cooling the resin in the cavity 16 to a temperature at which it can be taken out, the movable platen 52 is moved to move the movable mold 3 to the left side in Fig. 5 to open the mold. Further, the ejector rod 57 is protruded, and the ejector pin 12 sandwiched between the lower ejector plate 10 and the upper ejector plate 11 is protruded from the movable core block 14 to demold and take out the molded product. After taking out the molded product, the ejector rod 57 is retracted, and the movable platen 52 is moved to move the movable mold 3 to the right side in Fig. 5 to close the mold and define a cavity for the next molding. By repeating such operations, resin molded products can be continuously produced.

[0030] (Hot Runner Nozzle) The hot runner nozzle according to this embodiment will be described in detail. In the following description, when referring to the parts of the hot runner nozzle, the side closer to the gate 31 as viewed along the longitudinal direction of the nozzle may be referred to as the tip side, and the side farther from the gate 31 may be referred to as the base side. As shown in FIG. 1 or FIG. 3, the body 23 of the hot runner nozzle is supported by the fixed mold plate 5 on the base side, and the longitudinal position is defined by the contact surface 1S and the radial position is defined by the contact surface 1R. The tip side of the body 23 is supported by the fixed cavity block 13, and the radial position is positioned by the contact surface 2R. In other words, the nozzle body is fixed to the mold at least at the outer peripheral portion of the tapered region 33 (taper portion).

[0031] The flow path 56 of the molten resin formed inside the body 23 has a straight pipe region 32 (straight pipe portion) with a constant flow path diameter from the base side to the tip side, and a tapered region 33 (taper portion) where the flow path diameter decreases toward the tip side.

[0032] A heater 26 for heating the body 23 is attached to the outer periphery of the straight pipe region 32 of the body 23. A side view of the heater 26 is shown in FIG. 6(a), and a top view is shown in FIG. 6(b). The heater 26 is configured such that the heating wire is wound in a spiral shape with the folded portion at the tip. The heater 26 includes a closely wound region 34 and a closely wound region 36 where the heating wire is wound densely (narrow pitch), and a loosely wound region 35 where the heating wire is wound sparsely (wide pitch). The closely wound region corresponds to the portion where the heater is attached to the outer surface of the body at a relatively high density.

[0033] The heater 26 is mounted on the outer periphery of the cylindrical portion of the straight pipe region 32 of the body 23, and a cylindrical cover 28 is attached to the outer periphery of the heater 26. The tightly wound region 36 of the heater 26 is located on the tip side of the straight pipe region 32, the tightly wound region 34 is located on the root side of the straight pipe region 32, and the loosely wound region 35 is disposed between the tightly wound region 36 and the tightly wound region 34. Heat easily escapes from the root side of the body 23 to the fixed template 5 via the contact surface 1S and the contact surface 1R, and heat easily escapes from the tip side of the body 23 to the fixed cavity piece 13 via the contact surface 2R. For this reason, in order to suppress temperature drop, the tightly wound regions of the heater 26 are arranged on the root side and the tip side. In the middle between the root side and the tip side, since the body 23 is not in contact with other members, heat dissipation is small. In order to prevent the temperature of this portion from rising excessively due to heat storage, the loosely wound region 35 of the heater 26 is arranged in this portion.

[0034] In order to measure the temperatures of each part in the longitudinal direction of the body 23, a plurality of temperature measuring means are provided. Specifically, thermocouples are provided so as to be able to measure the temperatures of the temperature measurement points P1, temperature measurement point P2, temperature measurement point P3, and temperature measurement point P4 shown in FIGS. 1 and 3. The thermocouples are inserted into holes (wiring paths) formed inside the body 23, but for the sake of illustration convenience, only the wiring path of the thermocouple 27 that measures the temperature of the temperature measurement point P2 is drawn. The measurement results at each temperature measurement point are input to a temperature control unit 59 (FIG. 5), and the temperature control unit 59 controls the energization of the heater 26 based on the measurement results. The control method will be described later.

[0035] Implementing the heater 26 on the outer periphery of the body 23 on the tip side rather than the tapered region 33 where the flow path becomes smaller is difficult in terms of layout. For this reason, most (or all) of the heater 26 is attached to the straight pipe region 32 of the body 23. Therefore, the heat of the heater 26 hardly reaches the tip side rather than the tapered region 33 where the flow path becomes smaller, and the temperature of the body 23 in this portion is likely to decrease. Therefore, in the present embodiment, the high thermal conductivity material 30 is built into the body 23 from at least a part of the portion where the tightly wound region 36 of the heater 26 is arranged to at least a part of the tapered region 33. By providing the high thermal conductivity material 30, the heat supplied from the tightly wound region 36 of the heater 26 can be efficiently transferred to the tapered region 33, and it is possible to suppress the temperature of the tip portion of the hot runner nozzle from decreasing too much.

[0036] To explain the structure of the body 23 in which the high thermal conductivity material 30 is built in, a cross section cut along the line A-A in FIG. 1 is shown in FIG. 2(a), and a cross section cut along the line B-B in FIG. 1 is shown in FIG. 2(b). Further, a cross section cut along the line A-A in FIG. 3 is shown in FIG. 4(a), and a cross section cut along the line B-B in FIG. 3 is shown in FIG. 4(b). Here, the line A-A includes the temperature measurement point P2 and indicates a direction orthogonal to the longitudinal direction of the flow path 56 of the molten resin (or the flow direction of the molten resin or the axial direction of the valve pin 24). The line B-B includes the temperature measurement point P1 and indicates a direction orthogonal to the longitudinal direction of the flow path 56 of the molten resin (or the flow direction of the molten resin or the axial direction of the valve pin 24).

[0037] As shown in these cross-sectional views, in a plane orthogonal to the longitudinal direction of the hot runner nozzle, inside the body 23, high thermal conductivity materials 30 are arranged on a radial line centered on the valve pin 24. In other words, the high thermal conductivity materials 30 are arranged on a circumference centered on the valve pin 24 at equal angles (in this example, 72 degrees) from each other. The high thermal conductivity materials 30 efficiently conduct the heat supplied from the closely wound region 36 of the heater 26 to the taper region 33. By arranging them at equal angles in this way, the temperature uniformity of the body 23 in the taper region 33 can be enhanced. Also, in this embodiment, the high thermal conductivity materials 30 are evenly arranged inside the highly rigid body 23. For this reason, compared with the method of Japanese Patent Application Laid-Open No. 2020-99999 in which the tip side is coated with a high thermal conductivity member by a laser cladding method or the like, the rigidity of the hot runner nozzle on the tip side of the taper region 33 can be maintained at a higher level.

[0038] To fabricate a hot runner nozzle having such a structure, for example, the base material of the body 23 is processed in advance by cutting or the like to make it into a cylindrical shape, and holes for incorporating the high thermal conductivity materials 30 are formed. Then, after quenching, machining is performed to shape the portions that require dimensional accuracy, such as the contact surface 1R, the contact surface 1S, and the contact surface 2R. As the high thermal conductivity materials 30, for example, rod-shaped copper materials are prepared, and the tips are tapered at 120° to facilitate insertion into the holes formed in the body 23.

[0039] The rod-shaped copper is inserted into the holes formed in the body 23 with a clearance of intermediate fit of 0 to -10 μm, and the rod-shaped copper is hammered in so as to be press-fitted. The excess high thermal conductivity materials 30 (copper materials) protruding from the outer surface of the body 23 are cut by, for example, machining, and thus the body 23 incorporating the high thermal conductivity materials 30 is completed. Thus, according to this embodiment, a hot runner nozzle capable of suppressing a temperature drop at the tip portion can be fabricated without using laser cladding or diffusion bonding. Due to the structure in which the high thermal conductivity materials 30 are mechanically press-fitted into the body 23, it has excellent mechanical strength and durability, and can be manufactured at a much lower cost compared with fabricating a hot runner nozzle using laser cladding or diffusion bonding.

[0040] Returning to FIGS. 1 and 3, in the present embodiment, a heat insulating member 29 is interposed between the tip portions of the body 23 and the high thermal conductivity material 30 and the fixed cavity insert 13 to reduce the heat conduction from the tip portion of the hot runner nozzle to the mold. Further, in order to suppress the conduction of heat to the fixed cavity insert 13 in the vicinity of the contact surface 2R, a heat insulating groove 3R is provided in the hot runner nozzle. By adopting a structure provided with the heat insulating groove 3R, the area of the contact surface 2R is defined and the high thermal conductivity material 30 is prevented from directly contacting the fixed cavity insert 13.

[0041] As described above, in the hot runner nozzle of the present embodiment, in order to stably position the nozzle, the body 23 abuts against the fixed mold plate 5 on the base side and against the fixed cavity insert 13 on the tip side. In order to suppress the occurrence of a local temperature drop in the body 23 due to heat conduction at the contact portion, a closely wound region 34 and a closely wound region 36 of the heater 26 are arranged in the vicinity of the contact portion. At the tip side of the hot runner nozzle, it is difficult to mount the heater 26 in a tapered region 33 where the cross-sectional area of the molten resin flow path is narrowed toward the gate 31.

[0042] In the present embodiment, the high thermal conductivity material 30 is built into the body 23 from at least a part of the straight pipe region 32 where the closely wound region 36 of the heater 26 is arranged to at least a part of the tapered region 33. In a plane orthogonal to the longitudinal direction of the hot runner nozzle, the plurality of high thermal conductivity materials 30 are arranged on the radiation centered on the valve pin 24. It is desirable to use a material having a thermal conductivity of 100 W / m·K or more for the high thermal conductivity material 30, and preferably copper or a copper alloy is used. As the high thermal conductivity material 30, a material having relatively low rigidity but high thermal conductivity compared to the material of the body 23 can be used.

[0043] Near the tapered region 33, there is a temperature measurement point P1. Near the tightly wound region 36 (the contact portion with the fixed cavity piece 13) of the heater 26, there is a temperature measurement point P2. Near the loosely wound region 35 of the heater 26, there is a temperature measurement point P3. Near the tightly wound region 34 (the contact portion with the fixed template 5) of the heater 26, there is a temperature measurement point P4, respectively. Temperature measurement means such as thermocouples are provided at the temperature measurement points P1 to P4, and the temperature measurement results are input to the temperature control unit 59.

[0044] Based on the measurement results of each temperature measurement means, the temperature control unit 59 controls the power supplied to the heater 26. For example, the temperature control unit 59 can control the power supplied to the heater 26 based on the measurement result of the thermocouple installed at the temperature measurement point P2, taking the temperature measurement point P2 as the control point. That is because the temperature measurement point P2 is close to the tapered region 33 where the adverse effects of temperature drop are likely to become apparent and is also close to the tightly wound region 36 of the heater 26, so it can be said to be a control point suitable for enhancing control responsiveness. The temperature control unit 59 controls the energization of the heater 26 so that the temperature measured at the temperature measurement point P2 reaches a predetermined set temperature. It can also be said that the energization of the heater 26 is controlled so that the temperature near the boundary between the straight pipe region (straight pipe part) and the tapered region (tapered part) reaches a predetermined set temperature. Or, it can be said that the energization of the heater 26 is controlled so that the temperature near the part where the heater is attached at a relatively high density on the side close to the gate reaches a predetermined temperature.

[0045] Of course, the energization control of the heater 26 by the temperature control unit 59 is not limited to this method. For example, it may be controlled based on a mathematical formula using two or more of the temperature measurement results of the temperature measurement points P1 to P4. Or, a control method may be adopted in which the measurement result of the temperature measurement point P2 is taken as the master and the measurement results of other temperature measurement points are taken as the slaves. The temperature control unit 59 can control the energization of the heater 26 by any control method such as PID control.

[0046] In this embodiment, even when some trouble occurs during continuous molding and the continuous molding is temporarily interrupted to deal with the trouble, the above-described temperature control is continued. That is, the temperature control unit controls the energization of the heater using the measurement result of the temperature measurement means from when the regular supply of the molten resin from the hot runner nozzle to the cavity is stopped until the regular supply is resumed. Thereby, it is possible to suppress a large change in the temperature distribution in the hot runner body from the steady state during continuous operation. In particular, it is possible to suppress the occurrence of a temperature drop at the body tip portion close to the cavity. For this reason, when resuming continuous molding after dealing with the trouble, since the temperature distribution at each part of the hot runner body is maintained in a state close to the continuous operation state, the number of molding shots for adjustment can be significantly reduced (or made unnecessary) compared with the prior art.

[0047] According to this embodiment, the hot runner nozzle is excellent in durability, can be manufactured at low cost, and can be controlled so that each part of the nozzle can be maintained within a predetermined temperature range suitable for injection molding.

[0048] [Example 1] In Example 1, the body 23 was formed using stainless steel having excellent mechanical strength and a thermal conductivity of 25.1 W / m·K, and the high thermal conductivity material 30 was formed using a round bar of a copper alloy having a thermal conductivity of 323 W / m·K. The cross-sectional structure shown in FIGS. 2(a) and 2(b) was adopted.

[0049] Based on the front end face P0 of the body 23 shown in FIG. 1, a temperature measurement point P1 was set at a position 8 mm from P0, a temperature measurement point P2 was set at a position 14 mm from P0, a temperature measurement point P3 was set at a position 41 mm from P0, and a temperature measurement point P4 was set at a position 56 mm from P0. In addition, in order to cool and solidify the molten resin filled in the cavity 16 (FIG. 5), a medium (for example, water) adjusted to a temperature of 30°C was caused to flow through the pipe 17.

[0050] When the temperature of the temperature measurement point P2, which is a control point, was controlled to be 220 °C, the measurement results at each position were that the temperature measurement point P1 was 200 °C, the temperature measurement point P2 was 220 °C, the temperature measurement point P3 was 225 °C, and the temperature measurement point P4 was 200 °C.

[0051] According to this embodiment, since the temperature drop in the tapered region 33 is suppressed, the occurrence of a decrease in the viscosity and solidification of the molten resin near the tip of the nozzle is suppressed. For this reason, the occurrence of defects such as gate defects where resin does not flow out from the gate 31, filling defects where a fixed amount of resin is not injected from the gate 31, and transfer defects and molding defects caused by filling the cavity 16 with resin having a non-uniform viscosity is suppressed. For example, even when molding a resin material such as a resin mixed with glass fiber or carbon fiber, polyethylene terephthalate, polybutylene terephthalate, nylon, etc., which easily shows a sharp increase in melt viscosity when the temperature drops, the above-described effects can be exhibited.

[0052] [Comparative Example 1] In Comparative Example 1, the outer shape of the body was the same as that of Example 1, but it was configured not to incorporate the high thermal conductivity material 30. That is, the entire body was formed of stainless steel having a thermal conductivity of 25.1 W / m·K.

[0053] When the temperature of the temperature measurement point P2, which is a control point, was controlled to be 220 °C, the measurement results at each position were that the temperature measurement point P1 was 180 °C, the temperature measurement point P2 was 220 °C, the temperature measurement point P3 was 225 °C, and the temperature measurement point P4 was 190 °C.

[0054] For this reason, for example, when molding a resin material that easily shows a sharp increase in melt viscosity when the temperature drops, defects such as gate defects, filling defects, transfer defects, and molding defects were likely to occur. In addition, when restarting after interrupting continuous operation, it was necessary to perform a large number of adjustment shots until the quality of the molded product became stable.

[0055] As described above, in Example 1 in which the high thermal conductivity material 30 is incorporated, compared with Comparative Example 1 that does not include the high thermal conductivity material 30, the temperature drop in the tapered region 33 on the tip side in particular is suppressed, and the entire nozzle is controlled to be within a predetermined temperature range suitable for injection molding.

[0056] [Example 2] FIG. 7(a) shows a cross-sectional view of the tip side of the hot runner according to Example 2 cut along the axial direction of the valve pin 24. Further, FIG. 7(b) shows a cross-sectional view of the hot runner cut along line A-A in FIG. 7(a). Regarding matters common to Example 1, the description will be simplified or omitted.

[0057] In this embodiment, the outer diameter D2 of the high thermal conductivity material 30 is set to Φ3.5 mm. The minimum distance between the flow path 56 and the high thermal conductivity material 30, in other words, the wall thickness D1 of the body 23 located between the straight pipe region of the flow path 56 and the high thermal conductivity material 30, is set to 0.8 mm. The distance between the flow path 56 and the thermocouple 27, in other words, the wall thickness D3 of the body 23 located between the straight pipe region of the flow path 56 and the temperature measurement point P2, is set to 0.8 mm. Considering the mechanical strength and durability of the body 23, it is desirable that the wall thickness D1 and the wall thickness D3 be 0.8 mm or more.

[0058] When looking along the axial direction of the valve pin 24, when the range in which the high thermal conductivity material 30 extends is X1, the range of the closely wound region 36 of the heater 26 is X2, and the range that is half of the closely wound region 36 (on the gate 31 side) is X3, X1 extends to the gate 31 side more than X3 and is configured to include at least the entire area of X3. That is, when looking along the axial direction of the valve pin 24, the high thermal conductivity material 30 extends to the entire tapered region 33 (FIG. 1) of the flow path 56 on the tip side and extends to more than half of the closely wound region 36 on the root side.

[0059] Further, the thermocouple 27 is installed at the temperature measurement point P2 which is a temperature control point. The temperature measurement point P2 is arranged in X2 which is the range of the closely wound region 36. However, in order to control the temperature on the tip side of the hot runner with high precision and high responsiveness, it is desirable that the temperature measurement point P2 be arranged in the range of X3.

[0060] When the temperature of the temperature measurement point P2, which is a control point, was controlled to be 220°C, the measurement results at each position were: the temperature measurement point P1 was 190°C, the temperature measurement point P2 was 220°C, the temperature measurement point P3 was 254°C, and the temperature measurement point P4 was 219°C. According to this embodiment, since the temperature drop in the tapered region 33 is suppressed, the decrease in the viscosity and solidification of the molten resin near the tip of the nozzle are suppressed. Compared with the previous Comparative Example 1, the temperature drop in the tapered region 33 on the tip side in particular was suppressed, and the entire nozzle was controlled to be within a predetermined temperature range suitable for injection molding.

[0061] [Example 3] Fig. 8 shows a cross-sectional view of the tip side of the hot runner according to Example 3 cut along the axial direction of the valve pin 24. Descriptions of matters common to Example 1 or Example 2 are simplified or omitted.

[0062] In this embodiment, compared with Example 2, when viewed along the axial direction of the valve pin 24, the range in which the high thermal conductivity material 30 extends is expanded toward the root side. When the range in which the high thermal conductivity material 30 extends along the axial direction of the valve pin 24 is designated as X4, X4 is 44 mm. That is, when viewed along the axial direction of the valve pin 24, the high thermal conductivity material 30 extends to the tapered region 33 (Fig. 1) of the flow path 56 on the tip side and extends to the loosely wound region 35 of the heater 26 on the root side.

[0063] When the temperature of the temperature measurement point P2, which is a control point, was controlled to be 220°C, the measurement results at each position were: the temperature measurement point P1 was 192°C, the temperature measurement point P2 was 220°C, the temperature measurement point P3 was 236°C, and the temperature measurement point P4 was 209°C. According to this embodiment, since the temperature drop in the tapered region 33 is suppressed, the decrease in the viscosity and solidification of the molten resin near the tip of the nozzle are suppressed. Compared with the previous Comparative Example 1, the temperature drop in the tapered region 33 on the tip side in particular was suppressed, and the entire nozzle was controlled to be within a predetermined temperature range suitable for injection molding.

[0064] [Example 4] Referring to FIG. 9(a), Example 4 will be described. FIG. 9(a) shows a cross section taken along line A-A of FIG. 7(a), similar to FIG. 7(b) referred to in the description of Example 2. Regarding matters common to Example 1 or Example 2, the description will be simplified or omitted.

[0065] In Example 4, the outer diameter D2 of the high thermal conductivity material 30 was set to Φ2.5 mm, and it was arranged so as to be closer to the heater 26 than the melt resin flow path 56 when viewed in the thickness direction of the body 23.

[0066] When controlling so that the temperature of the temperature measurement point P2, which is the control point, becomes 220°C, the measurement results at each position were that the temperature measurement point P1 was 187°C, the temperature measurement point P2 was 220°C, the temperature measurement point P3 was 254°C, and the temperature measurement point P4 was 219°C. According to this example, since the temperature drop in the taper region 33 is suppressed, the decrease in the viscosity and solidification of the melt resin near the nozzle tip are suppressed. Compared with the above Comparative Example 1, the temperature drop in the taper region 33 on the tip side in particular was suppressed, and the entire nozzle was controlled to be within a predetermined temperature range suitable for injection molding.

[0067] [Example 5] Referring to FIG. 9(b), Example 5 will be described. FIG. 9(b) shows a cross section taken along line A-A of FIG. 7(a), similar to FIG. 7(b) referred to in the description of Example 2. Regarding matters common to Example 1 or Example 2, the description will be simplified or omitted. In Example 5, the outer diameter D2 of the high thermal conductivity material 30 was set to Φ4.5 mm, and the high thermal conductivity material 30 was shaped so as not to protrude to the heater 26 side beyond the outer diameter of the cylinder of the body 23.

[0068] When the temperature of the temperature measurement point P2, which is the control point, was controlled to 220°C, the measurement results at each position were: the temperature measurement point P1 was 193°C, the temperature measurement point P2 was 220°C, the temperature measurement point P3 was 256°C, and the temperature measurement point P4 was 221°C. According to this embodiment, since the temperature drop in the tapered region 33 is suppressed, the decrease in the viscosity and solidification of the molten resin near the tip of the nozzle are suppressed. Compared with the above-mentioned Comparative Example 1, the temperature drop in the tapered region 33 on the tip side in particular was suppressed, and the entire nozzle was controlled to be within a predetermined temperature range suitable for injection molding.

[0069] [Example 6] Referring to Fig. 9(c), Example 6 will be described. Fig. 9(c) shows a cross-section taken along line A-A of Fig. 7(a), similar to Fig. 7(b) referred to in the description of Example 2. Regarding matters common to Example 1 or Example 2, the description will be simplified or omitted.

[0070] In Example 6, the outer diameter D2 of the high thermal conductivity material 30 was set to Φ3.5 mm, and the high thermal conductivity material 30 was arranged on six radiation lines centered on the valve pin 24 on a plane perpendicular to the longitudinal direction of the hot runner nozzle. In other words, the six high thermal conductivity materials 30 are arranged on a circumference centered on the valve pin 24 so as to be separated from each other by an equal angle (in this example, 60 degrees).

[0071] When the temperature of the temperature measurement point P2, which is the control point, was controlled to 220°C, the measurement results at each position were: the temperature measurement point P1 was 193°C, the temperature measurement point P2 was 220°C, the temperature measurement point P3 was 254°C, and the temperature measurement point P4 was 219°C. According to this embodiment, since the temperature drop in the tapered region 33 is suppressed, the decrease in the viscosity and solidification of the molten resin near the tip of the nozzle are suppressed. Compared with the above-mentioned Comparative Example 1, the temperature drop in the tapered region 33 on the tip side in particular was suppressed, and the entire nozzle was controlled to be within a predetermined temperature range suitable for injection molding.

[0072] [Example 7] Referring to FIG. 9(d), Example 7 will be described. Similar to FIG. 7(b) referred to in the description of Example 2, FIG. 9(d) shows a cross-section taken along line A-A of FIG. 7(a). For matters common to Example 1 or Example 2, the description will be simplified or omitted.

[0073] In Example 7, the outer diameter D2 of the high thermal conductivity material 30 was set to Φ3.5 mm, and the high thermal conductivity materials 30 were arranged on four radiation lines centered on the valve pin 24 on a plane orthogonal to the longitudinal direction of the hot runner nozzle. In other words, the four high thermal conductivity materials 30 are arranged on a circumference centered on the valve pin 24 so as to be equally angled (90 degrees in this example) from each other.

[0074] When controlled so that the temperature of the temperature measurement point P2, which is the control point, becomes 220°C, the measurement results at each position were that the temperature measurement point P1 was 187°C, the temperature measurement point P2 was 220°C, the temperature measurement point P3 was 253°C, and the temperature measurement point P4 was 218°C. According to this example, since the temperature drop in the tapered region 33 is suppressed, the decrease in the viscosity and solidification of the molten resin in the vicinity of the nozzle tip are suppressed. Compared with the above-mentioned Comparative Example 1, the temperature drop in the tapered region 33 on the tip side in particular was suppressed, and the entire nozzle was controlled to be within a predetermined temperature range suitable for injection molding.

[0075] [Embodiment 2] Embodiment 2 will be described. For matters similar to those in Embodiment 1, the description will be simplified or omitted.

[0076] (Device Configuration) The overall configuration of the injection molding apparatus according to Embodiment 2 is the same as that of Embodiment 1 described with reference to FIG. 5. Also in the hot runner nozzle of the present embodiment, in order to stably position the nozzle, the body 23 abuts against the fixed mold plate 5 on the base side and against the fixed cavity block 13 on the tip side. In order to suppress a local temperature drop in the body 23 due to heat conduction at the abutting portion, a closely wound region 34 and a closely wound region 36 of the heater 26 are arranged in the vicinity of the abutting portion. On the tip side of the hot runner nozzle, it is difficult to mount the heater 26 in a tapered region 33 where the cross-sectional area of the molten resin flow path is narrowed toward the gate 31. In the present embodiment, a high thermal conductivity material 30 is incorporated inside the body 23 from at least a part of the portion where the closely wound region 36 of the heater 26 is arranged to at least a part of the tapered region 33. The plurality of high thermal conductivity materials 30 are arranged on a radiation line centered on the valve pin 24 in a plane orthogonal to the longitudinal direction of the hot runner nozzle. It is desirable to use a material having a thermal conductivity of 100 W / m·K or more for the high thermal conductivity material 30, and copper or a copper alloy is preferably used.

[0077] (Hot runner nozzle) The hot runner nozzle of the present embodiment is common with the embodiment in that the body 23 incorporates the high thermal conductivity material 30, but the arrangement position of the high thermal conductivity material 30 is different from that of Embodiment 1.

[0078] FIG. 10 shows a cross-sectional view of the tip side of the hot runner according to Embodiment 2 cut along the axial direction of the valve pin 24. Also, in order to explain the structure of the body 23 incorporating the high thermal conductivity material 30, a cross-section cut along line A-A in FIG. 10 is shown in FIG. 11(a), and a cross-section cut along line B-B in FIG. 10 is shown in FIG. 11(b).

[0079] In Embodiment 1 described with reference to FIG. 1 and the like, the rod-shaped high thermal conductivity material 30 extended such that the longitudinal direction of the rod was parallel to the axial direction of the valve pin 24. In the tapered region 33, the cross-sectional area of the molten resin flow path 56 is narrowed as it approaches the gate 31, so the wall thickness of the body 23 increases, and the distance separating the high thermal conductivity material 30 and the molten resin flow path 56 increases as it approaches the gate 31.

[0080] In this embodiment, as shown in FIGS. 10 to 11(b), the rod-shaped high thermal conductivity material 30 is inserted from the outer peripheral surface side of the cylindrical body 23 toward the flow path 56 side, and the longitudinal direction of the rod-shaped high thermal conductivity material 30 is inclined with respect to the axial direction of the valve pin 24. In other words, the rod-shaped high thermal conductivity material 30 is installed to be inclined in a direction closer to the valve pin 24 (or the flow path 56) as it is closer to the gate 31. Therefore, even at a position close to the gate 31 in the taper region 33, the heat in the tightly wound region 36 of the heater 26 is efficiently conducted to the flow path 56 of the molten resin through the body 23.

[0081] Also in this embodiment, on a plane orthogonal to the longitudinal direction of the hot runner nozzle, the high thermal conductivity material 30 is arranged on a radiation line centered on the valve pin 24 inside the body 23. In other words, the high thermal conductivity materials 30 are arranged on a circumference centered on the valve pin 24 at equal angular intervals from each other. The high thermal conductivity material 30 efficiently conducts the heat supplied from the tightly wound region 36 of the heater 26 to the taper region 33, and by arranging them at equal angles in this way, the temperature uniformity of the body 23 in the taper region 33 can be improved.

[0082] Further, since the high thermal conductivity material 30 is evenly arranged inside the body 23 with high rigidity, compared with the method of Japanese Patent Application Laid-Open No. 2020-99999 in which the tip side is coated with a high thermal conductivity member by a laser cladding method or the like, the rigidity of the hot runner nozzle on the tip side of the taper region 33 can be maintained at a higher level.

[0083] To fabricate a hot runner nozzle having such a structure, for example, the base material of the body 23 is pre-machined by cutting or the like to form a cylindrical shape, and holes for incorporating the high thermal conductivity material 30 are formed. After quenching, machining is performed to shape portions that require dimensional accuracy, such as the contact surface 1R, the contact surface 1S, and the contact surface 2R. As the high thermal conductivity material 30, for example, a rod-shaped copper material is prepared, and the tip is tapered at 120° to facilitate insertion into the holes formed in the body 23. The rod-shaped copper is inserted into the holes formed in the body 23 with a clearance of intermediate fit between 0 and -10 μm and is tapped in so as to be press-fitted. The high thermal conductivity material 30 (copper material) protruding from the surface position of the body 23 is cut, for example, by machining, and thus the body 23 incorporating the high thermal conductivity material 30 is completed. Thus, according to the present embodiment, it is possible to fabricate a hot runner nozzle capable of suppressing a temperature drop at the tip portion without using laser cladding or diffusion bonding. Because of the structure in which the high thermal conductivity material 30 is mechanically press-fitted into the body 23, it has excellent mechanical strength and durability, and can be manufactured at a much lower cost compared to fabricating a hot runner nozzle using laser cladding or diffusion bonding.

[0084] In FIG. 10, with respect to the plane orthogonal to the axial direction of the valve pin 24, if the angle formed by the longitudinal direction of the rod-shaped high thermal conductivity material 30 is θ1, it is preferable that θ3 < θ1 < θ2. Here, θ3 is a straight line connecting the end portion on the gate 31 side of the taper region 33 and the position where the heater 26 bent at the tip as shown in FIG. 6(a) winds around the outer periphery of the body 23. In order to efficiently conduct the heat generated by the tightly wound region 36 of the heater 26, θ3 < θ1.

[0085] Also, when manufacturing the body 23, quenching is performed after forming holes for inserting the high thermal conductivity material 30. Here, θ2 is the limit angle at which the portion (FIG. 1) for forming the contact surface 1R and the contact surface 1S does not interfere with the hole machining tool. That is, θ1 < θ2 is set so that the tool does not interfere with the portion constituting the contact surface for positioning when forming the holes for inserting the high thermal conductivity material 30.

[0086] In the hot runner nozzle of this embodiment, when control was performed such that the temperature of the temperature measurement point P2, which is a control point, became 220°C, the measurement results at each position were as follows: the temperature measurement point P1 was 203°C, the temperature measurement point P2 was 220°C, the temperature measurement point P3 was 238°C, and the temperature measurement point P4 was 198°C. According to this embodiment, since the temperature drop in the tapered region 33 is suppressed, the occurrence of a decrease in the viscosity or solidification of the molten resin near the tip of the nozzle is suppressed. Compared with the above-described Comparative Example 1, the temperature drop in the tapered region 33 on the tip side in particular was suppressed, and the entire nozzle was controlled to be within a predetermined temperature range suitable for injection molding.

[0087] In this embodiment, even when some trouble occurs during continuous molding and continuous molding is temporarily interrupted to deal with the trouble, the above-described temperature control is continued. Therefore, it is possible to suppress a large change in the temperature distribution in the hot runner body from the steady state during continuous operation. In particular, it is possible to suppress the occurrence of a temperature drop at the tip of the body close to the cavity. For this reason, when resuming continuous molding after dealing with the trouble, since the temperature distribution at each part of the hot runner body is maintained in a state close to the continuous operation state, the number of molding shots for adjustment can be significantly reduced (or made unnecessary) compared with the conventional case.

[0088] In addition, in Embodiment 1, the end of the high thermal conductivity material 30 on the gate 31 side was sealed by the heat insulating member 29, and the high thermal conductivity material 30 was prevented from coming into contact with the molten resin in the flow path 56. If, for some reason, the vicinity of the heat insulating member 29 or the high thermal conductivity material 30 is damaged, in Embodiment 1, it cannot be said that there is no possibility that the pieces peeled off from the high thermal conductivity material 30 will mix into the molten resin. In that regard, in this embodiment, the high thermal conductivity material 30 has a structure inserted into the body 23 from the outer peripheral side of the body 23, and the tip of the high thermal conductivity material 30 on the gate 31 side is surrounded by the body 23. Therefore, even if the heat insulating member 29 is damaged, pieces peeled off from the high thermal conductivity material 30 will not mix into the molten resin.

[0089] [Other Embodiments] Note that the present invention is not limited to the embodiments and examples described above, and many modifications are possible within the technical idea of the present invention. For example, it is possible to implement by combining all or part of the different embodiments and examples described above.

[0090] The number of high thermal conductivity materials incorporated into the body is not limited to the above-described examples. The materials constituting the body and the high thermal conductivity material are not limited to the above-described examples. In short, a high thermal conductivity material made of a material having a higher thermal conductivity than the body may be incorporated into a body having high mechanical strength.

[0091] An example of arranging the high thermal conductivity material along a circle centered on the valve pin on a plane perpendicular to the axis of the valve pin has been shown, but other arrangement methods may also be used. For example, a plurality of high thermal conductivity materials may be dispersedly arranged on a plurality of concentric circles having different radii centered on the valve pin.

[0092] A hot runner nozzle provided with both the high thermal conductivity material of Embodiment 1 and the high thermal conductivity material of Embodiment 2 may be used. When viewed along a plane perpendicular to the flow path, for example, the high thermal conductivity material of Embodiment 1 and the high thermal conductivity material of Embodiment 2 may be alternately arranged around the valve pin. Alternatively, the high thermal conductivity material of Embodiment 1 may be arranged on a first circumference centered on the valve pin, and the high thermal conductivity material of Embodiment 2 may be arranged on a second circumference having a different radius.

[0093] In Embodiment 2, the high thermal conductivity material was driven into the body (cylinder) from the outer surface of the body, but the high thermal conductivity material may be driven into the body from the tip side of the body so that the longitudinal direction of the high thermal conductivity member is inclined with respect to the axial direction of the valve pin, that is, in the same manner as in Embodiment 1.

[0094] The arrangement position and the number of the temperature measuring means are not limited to the above examples, and the measuring means is not limited to a thermocouple.

[0095] This specification discloses at least the following matters. [Item 1] A nozzle body which is a cylinder defining a flow path for molten resin, a cavity defined in a mold and a gate as a connection portion between the nozzle body, a valve pin capable of advancing and retreating in the cylinder to open and close the gate, and a heater attached to the outer periphery of the nozzle body, wherein the flow path includes a straight pipe portion with a constant flow path cross-sectional area and a tapered portion with a decreasing flow path cross-sectional area toward the gate, the heater is attached to at least a part of the outer periphery of the straight pipe portion, and the heater is not attached to at least a part of the tapered portion, inside the nozzle body, a plurality of high thermal conductivity materials made of a material having a higher thermal conductivity than the material of the base portion of the nozzle body are installed from the straight pipe portion with the heater attached to the outer periphery to at least a part of the tapered portion where the heater is not attached to the outer periphery, characterized in that it is a hot runner nozzle. [Item 2] The nozzle body is fixed to the mold at least at the outer peripheral portion of the tapered portion, characterized in that it is the hot runner nozzle according to Item 1. [Item 3] The high thermal conductivity material is installed inside the nozzle body such that the longitudinal direction is parallel to the axial direction of the valve pin, characterized in that it is the hot runner nozzle according to Item 1 or 2. [Item 4] The high thermal conductivity material is installed inside the nozzle body such that the longitudinal direction is inclined with respect to the axial direction of the valve pin, characterized in that it is the hot runner nozzle according to Item 1 or 2. [Item 5] In a plane orthogonal to the longitudinal direction of the flow path, the plurality of high thermal conductivity materials are arranged along a circumference centered on the valve pin, characterized in that it is the hot runner nozzle according to any one of Items 1 to 4. [Item 6] On the outer periphery of the straight pipe portion near the gate, the heater is attached at a relatively high density. The hot runner nozzle according to any one of Matters 1 to 5, characterized in that. [Matter 7] A thermometer measuring means is provided in the nozzle body, and a temperature control unit controls energization of the heater using the measurement result of the thermometer measuring means. The hot runner nozzle according to any one of Matters 1 to 6, characterized in that. [Matter 8] The temperature control unit controls energization of the heater using the measurement result of the thermometer measuring means so that the temperature near the boundary between the straight pipe portion and the tapered portion becomes a predetermined temperature. The hot runner nozzle according to Matter 7, characterized in that. [Matter 9] The temperature control unit controls energization of the heater using the measurement result of the thermometer measuring means so that the temperature near the portion where the heater is attached at a relatively high density on the side near the gate becomes a predetermined temperature. The hot runner nozzle according to Matter 7, characterized in that. [Matter 10] The temperature control unit controls energization of the heater using the measurement result of the thermometer measuring means from when the regular supply of the molten resin from the hot runner nozzle to the cavity is stopped until the regular supply is resumed. The hot runner nozzle according to any one of Matters 7 to 9, characterized in that. [Matter 11] A method for manufacturing a hot runner nozzle, which is a method for manufacturing the hot runner nozzle according to any one of Matters 1 to 10, comprising: Forming a flow path for the molten resin and a plurality of recesses in a base material of the hot runner nozzle. Press-fitting the high thermal conductivity material into each of the plurality of recesses. A method for manufacturing a hot runner nozzle, characterized in that. [Matter 12] A hot runner nozzle according to any one of Items 1 to 10, a supply unit that supplies molten resin to the hot runner nozzle, and a mold that defines the cavity. An injection molding die, characterized in that. [Item 13] Injecting molten resin into the cavity using the hot runner nozzle according to any one of Items 1 to 10. A method for manufacturing a resin molded product, characterized in that.

Explanation of Reference Numerals

[0096] 1... Mold / 1R, 1S... Contact surface / 2... Fixed mold / 2R... Contact surface / 3... Movable mold / 3R... Heat insulation groove / 5... Fixed mold plate / 13... Fixed cavity insert / 16... Cavity / 20... Hot runner / 23... Body / 24... Valve pin / 26... Heater / 27... Thermocouple / 28... Cover / 29... Heat insulation member / 30... High thermal conductivity material / 31... Gate / 32... Straight pipe region / 33... Taper region / 34... Tightly wound region / 35... Loosely wound region / 36... Tightly wound region / 56... Flow path / 59... Temperature control unit / P1 to P4... Temperature measurement points

Claims

1. A nozzle body which is a cylinder defining a flow path for molten resin, a cavity defined in a mold and a gate as a connection portion between the nozzle body, a valve pin capable of advancing and retreating in the cylinder to open and close the gate, and a heater attached to the outer periphery of the nozzle body, wherein the flow path includes a straight pipe portion with a constant flow path cross-sectional area and a tapered portion with a decreasing flow path cross-sectional area toward the gate, the heater is attached to at least a part of the outer periphery of the straight pipe portion, and the heater is not attached to at least a part of the tapered portion, inside the nozzle body, a plurality of high thermal conductivity materials made of a material having a higher thermal conductivity than the material of the base portion of the nozzle body are installed from the straight pipe portion with the heater attached to the outer periphery to at least a part of the tapered portion where the heater is not attached to the outer periphery, characterized in that it is a hot runner nozzle.

2. The nozzle body is fixed to the mold at least at the outer peripheral portion of the tapered portion, characterized in that it is the hot runner nozzle according to claim 1.

3. The high thermal conductivity material is installed inside the nozzle body such that the longitudinal direction is parallel to the axial direction of the valve pin, characterized in that it is the hot runner nozzle according to claim 1.

4. The high thermal conductivity material is installed inside the nozzle body such that the longitudinal direction is inclined with respect to the axial direction of the valve pin, characterized in that it is the hot runner nozzle according to claim 1.

5. In a plane orthogonal to the longitudinal direction of the flow path, the plurality of high thermal conductivity materials are arranged along a circumference centered on the valve pin, characterized in that it is the hot runner nozzle according to any one of claims 1 to 4.

6. The heater is attached to the outer periphery of the straight pipe portion on the side close to the gate with a relatively high density, characterized in that it is the hot runner nozzle according to any one of claims 1 to 4.

7. The nozzle body is provided with temperature measuring means, and a temperature control unit controls energization of the heater using the measurement result of the temperature measuring means, characterized in that it is the hot runner nozzle according to any one of claims 1 to 4.

8. The temperature control unit controls energization of the heater using the measurement result of the temperature measuring means such that the temperature near the boundary between the straight pipe portion and the tapered portion becomes a predetermined temperature, characterized in that it is the hot runner nozzle according to claim 7.

9. The temperature control unit controls energization of the heater using the measurement result of the temperature measurement means so that the temperature in the vicinity of a portion where the heater is attached at a relatively high density on the side closer to the gate reaches a predetermined temperature. The hot runner nozzle according to claim 7, characterized in that.

10. The temperature control unit controls energization of the heater using the measurement result of the temperature measurement means during the period from when the regular supply of the molten resin from the hot runner nozzle to the cavity is stopped until the regular supply is resumed. The hot runner nozzle according to claim 7, characterized in that.

11. A method for manufacturing a hot runner nozzle for manufacturing the hot runner nozzle according to any one of claims 1 to 4, forming a flow path for the molten resin and a plurality of recesses in a base material of the hot runner nozzle; press-fitting the high thermal conductivity material into each of the plurality of recesses. A method for manufacturing a hot runner nozzle, characterized in that.

12. An injection mold comprising the hot runner nozzle according to any one of claims 1 to 4, a supply unit that supplies molten resin to the hot runner nozzle, and a mold that defines the cavity. Characterized in that.

13. Injecting molten resin into the cavity using the hot runner nozzle according to any one of claims 1 to 4. A method for manufacturing a resin molded product, characterized in that.

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