Heat conduction mechanism

Abstract

To make temperature distribution in a root part of a heating cylinder where non-uniform temperature distribution exists be appropriate, and improve molding stability.SOLUTION: An injection device 10 has a heat conduction mechanism which has a cooling cylinder 12 as a cooling member, which cools a pellet as an object by being cooled by a water flow pipe 152 as a cooling source, and a heating cylinder 11 as a heating member, which heats the pellet by being heated by band heaters 101 to 106 as heating sources, and has non-uniform heat input density of a mass of the band heater 101 for heating a part in which a temperature gradient of the heating cylinder 11 is caused, in a direction away from the cooling cylinder 12.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a heat transfer mechanism. [Background technology]

[0002] Some injection molding machines have an injection unit that has a cooling cylinder that cools pellets, which are solid resins, placed in a hopper to prevent the pellets from unintentionally melting, and a heating cylinder that heats the pellets to melt them (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-290464 Summary of the Invention [Problem to be solved by the invention]

[0004] If the temperature distribution in the heating cylinder is unstable, the movement of the resin inside the heating cylinder will also become unstable, which may result in molding defects. On the other hand, the boundary between the heating cylinder and the cooling cylinder or its vicinity is a part that generates a temperature gradient, so the temperature distribution is likely to become unstable.

[0005] An object of the present invention is to improve molding stability by optimizing the temperature distribution at the base of a heating cylinder where a non-uniform temperature distribution exists. [Means for solving the problem]

[0006] The heat conduction mechanism of the present invention, which was completed with this objective in mind, is a heat conduction mechanism that has a cooling member that cools an object by being cooled by a cooling source, and a heating member that heats the object by being heated by a heating source, and is characterized in that the temperature distribution in the part of the heating member that generates a temperature gradient is changed depending on the physical properties of the object. Here, the heat input density of the heat source, which is a single unit that heats a portion of the heating member that generates a temperature gradient, may be non-constant in a direction away from the cooling member. The heat input density may be gradually increased in a direction away from the cooling member. The heat source may be characterized in that the spacing between the plurality of heating wires built into the heat source mass gradually decreases in a direction away from the cooling member. The heat input density may be determined in accordance with physical properties that differ for each type of object. Furthermore, the cooling cylinder constituting the injection device of the injection molding machine serves as the cooling member to cool the resin as the object, and the heating cylinder constituting the injection device serves as the heating member to heat the resin, and the heat density of the band heater serving as the mass heating source that heats the portion of the heating cylinder that generates the temperature gradient may be characterized in that it is not constant in the direction away from the cooling member. The heating element may also be characterized in that a plurality of slits are provided in the portion that generates the temperature gradient to form a plurality of fins, and one or more heating wires are respectively arranged at the tip portion of each of the plurality of fins. The heat input density at the portion where the temperature gradient is generated may not be constant in a direction away from the cooling member. The heating element may be characterized in that the heat input densities of the plurality of heat sources that heat the portion of the heating element that generates the temperature gradient are different from each other. The heat input density of the plurality of heat sources may increase as the heat sources are located farther away from the cooling member. [Effects of the Invention]

[0007] According to the present invention, it is possible to optimize the temperature distribution at the base of the heating cylinder, where a non-uniform temperature distribution exists, and improve molding stability. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing an example of the configuration of an injection molding machine including an injection unit having a heat transfer mechanism according to a first embodiment and a mold clamping unit. [Figure 2] 2 is a graph showing the temperature distribution of a heating cylinder of the injection device of FIG. 1. [Figure 3] Graphs (A) and (B) show the molding stability of resins. [Figure 4] 10A and 10B are diagrams showing a specific example of a method for changing the heat input density of a band heater in the center line direction. [Figure 5] 10 is a diagram showing a part of the configuration of a heating cylinder of an injection device having a heat conduction mechanism according to a second embodiment. FIG. [Figure 6] 10 is a diagram showing a part of the configuration of a heating cylinder of an injection device having a heat conduction mechanism according to a third embodiment. FIG. [Figure 7] FIG. 1 is a diagram illustrating an image of anisotropy of thermal conduction. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. First Embodiment (Configuration of injection molding machine 1) FIG. 1 is a diagram showing an example of the configuration of an injection molding machine 1 equipped with an injection unit 10 having a heat transfer mechanism according to the first embodiment and a mold clamping unit 50. As shown in FIG. FIG. 2 is a graph showing the temperature distribution of the heating cylinder 11 of the injection device 10 of FIG. 3(A) and (B) are graphs showing the molding stability of the resin. The injection molding machine 1 shown in Figure 1 is a device used to manufacture resin products. The injection molding machine 1 heats and melts solid resin (hereinafter referred to as "pellets"), which is the material for the resin product, to turn it into molten resin. The molten resin is then injected into a mold, where it is cooled and solidified to form the resin product. The white arrows in Figure 1 indicate the direction in which the pellets and the molten resin formed by melting the pellets flow.

[0010] The injection molding machine 1 includes an injection device 10 that cools, melts, kneads, and weighs pellets and injects molten resin into the mold of the mold clamping device 50, and a mold clamping device 50 that clamps the mold. The injection device 10 includes a heating cylinder 11 as a heating member and a cooling cylinder 12 as a cooling member.

[0011] The heating cylinder 11 is a metallic, approximately cylindrical cylinder that heats and melts pellets as an object to turn them into molten resin. Specifically, the heating cylinder 11 is heated by the band heaters 101 to 106 that serve as heat sources, and thereby heats the pellets that pass through a through-hole 111 extending through the interior of the heating cylinder 11 in the direction of the center line, turning them into molten resin.

[0012] The band heaters 101 to 106 are heaters arranged so as to wrap around the outer peripheral surface of the heating cylinder 11 in the circumferential direction. Each of the band heaters 101 to 106 contains a heating wire, such as a nichrome wire (not shown), which serves as a heat source and extends in the circumferential direction of the heating cylinder 11. The number of heating wires contained in each of the band heaters 101 to 106 and their positions in the center line direction can be freely changed. Specific examples of the number of heating wires contained in the band heater 101 and their positions in the center line direction will be described later.

[0013] The cooling cylinder 12 is a metallic, substantially cylindrical cylinder that cools the pellets placed in the hopper. The cooling cylinder 12 is joined to the outer peripheral surface of the heating cylinder 11. A running water pipe 152, which serves as a cooling source, is disposed in the cooling cylinder 12 so as to extend in a direction perpendicular to the center line of the heating cylinder 11. The cooling cylinder 12 is cooled by cold water passing through the running water pipe 152, thereby cooling the pellets that pass through the through holes 151 that extend in a direction perpendicular to the center line of the heating cylinder 11. This prevents the pellets placed in the hopper from receiving heat from the heating cylinder 11 as they pass through the through holes 151 and melting, which can cause the pellets to adhere to the inside of the device.

[0014] Hereinafter, the root side of the heating cylinder 11 in the center line direction may be simply referred to as the "root side in the center line direction," and the tip side of the heating cylinder 11 in the center line direction may be simply referred to as the "tip side in the center line direction." Also, the radially inner side of the heating cylinder 11 may be simply referred to as the "radially inner side," and the radially outer side of the heating cylinder 11 may be simply referred to as the "radially outer side."

[0015] As described above, in the injection device 10, pellets fed into the hopper are cooled by the cooling cylinder 12 and then heated by the heating cylinder 11. In this way, a temperature gradient is generated at and in the vicinity of the boundary 400 between the heating cylinder 11 and the cooling cylinder 12. Specifically, a temperature gradient is generated in the region 300 indicated by the dashed line in FIG. 1.

[0016] FIG. 2 shows a graph with the horizontal axis representing "cylinder position [mm]" and the vertical axis representing "temperature [°C]." The "cylinder position [mm]" on the horizontal axis represents the distance toward the tip end in the center line direction, when the boundary 400 between the heating cylinder 11 and the cooling cylinder 12 in FIG. 1 is taken as the starting point (0 mm). The region 300 shown by the dashed line in FIG. 2 corresponds to the region 300 shown in FIG. 1 described above. Therefore, as shown in FIGS. 1 and 2, when the boundary 400 between the heating cylinder 11 and the cooling cylinder 12 is taken as the starting point (0 mm), the region 300 is up to a distance of about 160 mm toward the tip end in the center line direction.

[0017] The graph shown in Figure 2 shows the temperature distribution of the heating cylinder 11 when the temperature control position in the center line direction of the heating cylinder 11 is changed to 45 mm, 75 mm, and 105 mm from the boundary 400 while the position of the band heater 101 is fixed. Line L1 shows the temperature distribution of the heating cylinder 11 when the distance from the boundary 400 is 45 mm. Line L2 shows the temperature distribution of the heating cylinder 11 when the distance from the boundary 400 is 75 mm. Line L3 shows the temperature distribution of the heating cylinder 11 when the distance from the boundary 400 is 105 mm.

[0018] As shown in FIG. 2, the temperature distribution in region 300 varies depending on the distance from boundary 400. This is because the heating cylinder 11 itself is heated by the band heater 101 to heat and melt the pellets cooled by the cooling cylinder 12. The temperature distribution in region 300 increases as the distance from boundary 400 decreases. In other words, the temperature gradient becomes steeper closer to boundary 400. Comparing region 300 with other regions, a temperature gradient occurs in region 300 regardless of the distance from boundary 400, as described above. In contrast, in regions beyond approximately 160 mm from boundary 400 (regions other than region 300), the temperature of the heating cylinder 11 remains sufficiently high. Note that the graph in FIG. 2 does not include the temperature distribution at the tip of the heating cylinder 11.

[0019] The appropriate temperature distribution in region 300 varies depending on the physical properties of the pellets. For example, the melting point, which is one of the physical properties of pellets, differs between GPPS (general-purpose polystyrene) and PP (polypropylene). Specifically, the melting point of GPPS (general-purpose polystyrene) is about 80 to 100°C, while the melting point of PP (polypropylene) is about 160°C.

[0020] The graph shown in Fig. 3(A) shows molding stability when the resin type is GPPS (general purpose polystyrene) for each temperature control position in the center line direction of the heating cylinder 11. The graph shown in Fig. 3(B) shows molding stability when the resin type is PP (polypropylene) for each temperature control position in the center line direction of the heating cylinder 11.

[0021] Specifically, in the graphs of Figures 3(A) and (B), the horizontal axis represents the shot number, and the vertical axis represents the moving average of the standard deviation of the 50-shot metering time, which serves as an index for evaluating molding stability. Furthermore, lines L11 to L13 in Figure 3(A) represent the temperature distribution of the heating cylinder 11 when the temperature control position in the centerline direction of the heating cylinder 11 is 45 mm, 75 mm, and 105 mm from the boundary 400, respectively. Furthermore, lines L21 to L23 in Figure 3(B) represent the temperature distribution of the heating cylinder 11 when the temperature control position in the centerline direction of the heating cylinder 11 is 45 mm, 75 mm, and 105 mm from the boundary 400, respectively. That is, the graphs of Figures 3(A) and (B) show the relationship between the weight stability of the molded product and the temperature distribution.

[0022] As shown in the graphs in Figures 3(A) and (B), the degree of molding stability varies depending on the type of pellet. Furthermore, regardless of the type of pellet, the temperature distribution of the heating cylinder 11 affects molding stability. Therefore, when attempting to achieve a temperature distribution that matches the physical properties of the pellets using a conventional heating cylinder, overshooting beyond the set pressure may occur, making it impossible to achieve the intended temperature distribution. In particular, when a steep temperature gradient is desired, achieving the intended temperature distribution becomes even more difficult, which may adversely affect molding stability.

[0023] Therefore, the injection device 10 (see FIG. 1) having the heat conduction mechanism according to this embodiment realizes an appropriate temperature distribution by changing the temperature distribution in the region 300, which is the part of the heating cylinder 11 that generates the temperature gradient, according to the physical properties of the pellets. Specifically, the appropriate temperature distribution is realized by changing the temperature according to the physical properties of the pellets through the "optimization of heat input density" described below. Furthermore, as will be described later in the second embodiment, the appropriate temperature distribution can also be realized by changing the temperature according to the physical properties of the pellets through "anisotropy of heat conduction."

[0024] (Optimization of heat input density) FIG. 4 is a diagram showing a specific example of a method for changing the heat input density of the band heater 101 in the center line direction. In the region 300 of the heating cylinder 11 in Fig. 1 described above, the temperature gradient of the heating cylinder 11 can be changed in accordance with the physical properties of the pellets by changing the heat input density of the band heater 101 in the center line direction. This makes it possible to appropriately control the temperature distribution in the region 300 of the heating cylinder 11. Fig. 4 shows an enlarged portion of the region 300 of the heating cylinder 11 in Fig. 1.

[0025] 4 includes heating wires 131 to 139 that extend in the circumferential direction of the heating cylinder 11 and are spaced apart in the center line direction of the heating cylinder 11. The spacing between the heating wires 131 to 139 of the band heater 101 is not uniform in the center line direction of the heating cylinder 11. Therefore, the heat input density of the band heater 101 is not constant in the center line direction of the heating cylinder 11.

[0026] Specifically, of the heating wires 131 to 139 of the band heater 101, the heating wire 131 located closest to the base in the center line direction is arranged so that the distance between it and the heating wire 132 located next to it is the widest. Furthermore, the heating wire 139 located closest to the tip in the center line direction is arranged so that the distance between it and the heating wire 138 located next to it is the narrowest. That is, the heating wires 131 to 139 are arranged so that the distance between them gradually narrows from the base to the tip in the center line direction. This causes the heat input density to gradually increase from the base to the tip in the center line direction of the heating cylinder 11. The lengths of the white arrows extending radially in FIG. 4 indicate the magnitude of the heat input density of the band heater 101.

[0027] As described above, the number of heating wires and their positions in the direction of the center line built into the band heater 101 can be freely changed. Therefore, the number of heating wires and their positions in the direction of the center line are not particularly limited to the heating wires 131 to 139 shown in Fig. 4, and the number of heating wires and their positions in the direction of the center line can be determined depending on the physical properties of each type of pellet to be melted in the heating cylinder 11.

[0028] For example, suppose the types of pellets to be melted in the heating cylinder 11 are GPPS (general-purpose polystyrene) and PP (polypropylene). In this case, the number of heating wires and their positions in the center line direction can be determined depending on whether the material used is GPPS (general-purpose polystyrene), which has a melting point of approximately 80 to 100°C, or PP (polypropylene), which has a melting point of approximately 160°C. Specifically, if the material used is GPPS, which has a melting point lower than PP, the number of heating wires and their positions in the center line direction shown in FIG. 4 should be used, and if the material used is PP, which has a melting point higher than GPPS, the number of heating wires may be further increased. In this case, the heating wires may be positioned in the center line direction so that the spacing between them is narrower overall than that shown in FIG. 4, and the spacing between them gradually narrows from the base to the tip in the center line direction.

[0029] This makes it possible to change the temperature distribution in the region 300 of the heating cylinder 11 depending on the type of pellet. As a result, it is possible to realize an optimum temperature distribution for each type of pellet, thereby suppressing molding defects.

[0030] In summary, the injection device 10 having the heat conduction mechanism according to the first embodiment of the present invention only needs to have the following configuration, and can take on a variety of different embodiments. That is, the injection device 10 has a cooling cylinder 12 as a cooling member that cools the target object, the pellets, by being cooled by the running water pipe 152 that is a cooling source, and a heating cylinder 11 as a heating member that heats the pellets by being heated by the band heaters 101 to 106 that are heating sources, and has a heat conduction mechanism that changes the temperature distribution in the part of the heating cylinder 11 that generates a temperature gradient according to the physical properties of the heating cylinder 11.

[0031] This makes it possible to appropriately control the temperature distribution in the portion of the heating cylinder 11 where a temperature gradient is generated by changing the heat input density of the band heater 101, which is a single heat source that heats the portion of the heating cylinder 11 where a temperature gradient is generated, in the center line direction. In other words, without adopting a method of arranging multiple band heaters with different heat input densities, by simply arranging one band heater 101 in the portion of the heating cylinder 11 where a temperature gradient is generated, the temperature distribution in that portion can be appropriately controlled and stabilized in accordance with the physical properties of the pellets.

[0032] Here, the heat input density of the band heater 101 may be characterized by gradually increasing in the direction away from the cooling cylinder 12. As a result, the heat input density of the band heater 101, which is a single heat source that heats the portion of the heating cylinder 11 that generates the temperature gradient, gradually increases in the direction away from the cooling cylinder 12. As a result, the temperature distribution at the base of the heating cylinder 11, where non-uniform temperature distribution exists, can be optimized, and molding stability can be improved.

[0033] Furthermore, the heating wires 131 to 139 built into the band heater 101 may be arranged at intervals that gradually become closer in the direction away from the cooling cylinder 12 . As a result, the spacing between the heating wires 131 to 139 built into the band heater 101, which is a single heat source that heats the portion of the heating cylinder 11 that generates the temperature gradient, gradually becomes closer in the direction away from the cooling cylinder 12. As a result, even if the magnitude of the output of each of the heating wires 131 to 139 is kept constant (for example, the voltage is constant), the temperature distribution can be optimized so that the heat input density of the band heater 101 gradually increases in the direction away from the cooling cylinder 12.

[0034] Also, the heat input density of the band heater 101 may be determined in accordance with the physical properties that differ for each type of pellet. This makes it possible to perform injection molding according to the different physical properties of each type of pellet material. For example, as in the above example of GPPS (general-purpose polystyrene) and PP (polypropylene), it is now possible to efficiently perform injection molding using multiple types of pellets with different melting points using a single injection molding machine.

[0035] Furthermore, the cooling cylinder 12 constituting the injection device 10 of the injection molding machine 1 may be a cooling element that cools the pellets, the heating cylinder 11 constituting the injection device 10 is a heating element that heats the pellets, and the heat input density of the band heater 101, which is a single heat source that heats the part of the heating cylinder 11 that generates the temperature gradient, may not be constant in the direction away from the cooling cylinder. This makes it possible to appropriately control the temperature distribution in the portion of the heating cylinder 11 where the temperature gradient is generated by changing the heat input density of the band heater 101, which is a single heat source that heats the portion of the heating cylinder 11 where the temperature gradient is generated, in the center line direction. As a result, it is possible to stabilize the temperature distribution in the portion of the heating cylinder 11 where the temperature gradient is generated.

[0036] <Second embodiment> FIG. 5 is a diagram showing a part of the configuration of a heating cylinder 21 of an injection device 20 having a heat conduction mechanism according to the second embodiment. Figure 5 shows an enlarged view of a portion of the heating cylinder 21 where a temperature gradient is generated. The portion shown in Figure 5 corresponds to the portion shown in Figure 4 described above. As shown in Figure 5, slits 231 to 239 that form fins 221 to 228 are provided in the portion of the heating cylinder 21 where a temperature gradient is generated. The slits 231 to 239 are arranged at intervals along the centerline so as to extend in the radial direction. As a result, the fins 221 to 228 formed by the slits 231 to 239 are also arranged at intervals along the centerline so as to extend in the radial direction. Note that air is provided in the slits 231 to 239.

[0037] Two heating wires 212 are disposed at the radially outer tip portions of each of the fins 221 to 228. A heat insulating material 214 is disposed on the radially outer side of the heating wires 212 to prevent the thermal energy output from the heating wires 212 from escaping radially outward. Furthermore, a temperature sensor 213 capable of measuring the temperature of each fin is disposed on the radially inner side of each of the fins 221 to 228. With this configuration, by varying the output of each of the two heating wires 212 disposed on each of the multiple fins 221 to 228, it becomes possible to individually control the temperatures of the fins 221 to 228.

[0038] For example, temperature control is possible depending on whether the material used is GPPS, which has a lower melting point than PP, or PP, which has a higher melting point than GPPS. Specifically, when GPPS is used, the temperature distribution in the fins 221 to 228 is stabilized while the overall temperature is higher than in the case of PP. Furthermore, when PP is used, the temperature distribution in the fins 221 to 228 is stabilized while the overall temperature is lower than in the case of GPPS.

[0039] 5 shows a configuration in which two heating wires 212 are arranged on each of the fins 221 to 228, but the number of heating wires 212 arranged on each of the fins 221 to 228 is not particularly limited and may vary. For example, the number of heating wires 212 arranged may gradually increase toward the tip end in the center line direction, such as one heating wire 212 arranged on the fin 221, two heating wires 212 arranged on the fin 222, and three heating wires 212 arranged on the fin 223. This allows the heat input density to gradually increase from the base end toward the tip end in the center line direction without changing the output of each heating wire 212.

[0040] (Anisotropy of thermal conductivity) As described above, the slits 231 to 239 are provided in a portion of the region 300 of the heating cylinder 21 of the injection device 20, and air is disposed in the slits 231 to 239, thereby realizing anisotropy of thermal conduction. That is, the thermal conductivity in the centerline direction is smaller than the thermal conductivity in the radial direction. Specifically, the portion of the heating cylinder 21 where a temperature gradient is generated is provided with a metal member that serves as the base material of the heating cylinder 21 and air that has a different thermal conductivity from that of the metal member.

[0041] As a result, the thermal energy output from the heating wire 212 flows predominantly in a direction perpendicular to the center line direction of the heating cylinder 21 (from the outside to the inside in the radial direction), thereby suppressing the thermal energy from the heating wire 212 from flowing toward the center line direction. As a result, the thermal energy from the heating wire 212 is suppressed from escaping toward the cooling cylinder 12 side (the root side in the center line direction), thereby achieving efficient heat conduction in the part of the heating cylinder 21 that generates a temperature gradient.

[0042] In summary, the injection device 20 having the heat conduction mechanism according to the second embodiment of the present invention only needs to have the following configuration, and can take on a variety of different embodiments. That is, the injection device 20 has a cooling cylinder 12 as a cooling member that cools the target object, the pellets, by being cooled by a flowing water pipe 152 that is a cooling source, and a heating cylinder 11 as a heating member that heats the pellets by being heated by a heating wire that is a heating source, and has a heat conduction mechanism in which a plurality of slits 231 to 239 that form a plurality of fins 221 to 228 are provided in the part of the heating cylinder 11 that generates a temperature gradient, and one or a plurality of heating wires 212 are respectively arranged at the tip portion of each of the fins 221 to 228.

[0043] This makes it possible to individually control the temperatures of the fins 221 to 228 by varying the output of each of the one or more heating wires 212 arranged at the tip of each of the fins 221 to 228. As a result, the temperature distribution in the part of the heating cylinder 21 that generates the temperature gradient can be stabilized according to the physical properties of the pellets.

[0044] Here, it may be characterized in that the heat input density at the portion of the heating cylinder 11 that generates the temperature gradient is not constant in the direction away from the cooling cylinder 12. As a result, the heat input density in the part that generates the temperature gradient is not constant in the direction away from the cooling cylinder 12, and therefore an appropriate temperature distribution is achieved in the part that generates the temperature gradient compared to when the heat input density is constant in the direction away from the cooling cylinder 12.

[0045] <Third embodiment> FIG. 6 is a diagram showing a part of the configuration of a heating cylinder 31 of an injection device 30 having a heat conduction mechanism according to a third embodiment. Fig. 6 shows an enlarged view of a portion of the region 300 of the heating cylinder 31. The portion shown in Fig. 6 corresponds to the portion shown in each of Figs. 4 and 5 described above. In the example shown in Fig. 6, instead of the band heater 101 that heats at least a portion of the region 300 of the heating cylinder 11 in Fig. 4, four band heaters 141 to 144, each shorter in length in the center line direction than the band heater 101, are arranged in the center line direction.

[0046] 1, the band heaters 141 to 144 in Fig. 6 do not have a constant heat input density along the centerline. The band heaters 141, located closest to the base along the centerline, have the smallest heat input density, and the band heater 144, located closest to the tip along the centerline, has the largest heat input density. In other words, the band heaters 141 to 144 are arranged so that the heat input density gradually increases from the base to the tip along the centerline. Note that the lengths of the white arrows extending radially in Fig. 6 indicate the magnitude of the heat input density of the band heaters 141 to 144.

[0047] Such a configuration can be realized by varying the number of heating wires (not shown) built into each of the band heaters 141 to 144. In this case, for example, the number of heating wires built into band heater 141 may be 1, the number of heating wires built into band heater 142 may be 2, the number of heating wires built into band heater 143 may be 3, and the number of heating wires built into band heater 144 may be 4. This makes it possible to optimize the temperature distribution so that the heat input density gradually increases from the base side toward the tip side in the center line direction, even when the output magnitude of each heating wire is constant (for example, the voltage is constant).

[0048] Alternatively, for example, the number of heating wires built into each of the band heaters 141 to 144 may be constant, and the magnitude of the thermal energy output from each of the band heaters 141 to 144 may be varied. This makes it possible to gradually increase the heat input density from the base toward the tip along the center line without considering the number of heating wires.

[0049] In summary, the injection device 30 having the heat conduction mechanism according to the third embodiment of the present invention only needs to have the following configuration, and can take on a variety of different embodiments. That is, the injection device 30 has a cooling cylinder 12 as a cooling member that cools the target object, the pellets, by being cooled by a running water pipe 152 that is a cooling source, and a heating cylinder 11 as a heating member that heats the pellets by being heated by band heaters 141 to 144 and 102 to 106 that are heating sources, and is an injection device 30 having a heat conduction mechanism characterized in that there is a difference in the heat input density of the band heaters 141 to 144 that are multiple heating sources that heat the parts of the heating cylinder 11 that create a temperature gradient.

[0050] As a result, there is a difference in the heat input density of the band heaters 141 to 144 that heat the portion of the heating cylinder 11 where the temperature gradient is to be generated, so that an appropriate temperature distribution is realized in the portion where the temperature gradient is to be generated.

[0051] Here, the band heaters 141 to 144 may be characterized in that the heat input density increases as the distance from the cooling cylinder 12 increases. As a result, the heat input density of the band heaters 141 to 144 that heat the part of the heating cylinder 11 that generates the temperature gradient increases the farther away from the cooling cylinder 12, thereby achieving an appropriate temperature distribution in the part that generates the temperature gradient.

[0052] <Modification> FIG. 7 is a diagram showing an image of the anisotropy of thermal conduction. The example shown in FIG. 6 above is a configuration in which the heat input density gradually increases from the base to the tip in the centerline direction (a "heat input density optimization" configuration). However, the "thermal conduction anisotropy" configuration shown in the first embodiment may be added. Specifically, a configuration in which the thermal conductivity in the centerline direction is lower than the thermal conductivity in the radial direction may be added to the configuration in which the heat input density gradually increases from the base to the tip in the centerline direction. This allows the thermal energy output from each of the band heaters 141 to 144 to flow predominantly in a direction perpendicular to the centerline direction of the heating cylinder 31 (from the outer side to the inner side in the radial direction), thereby suppressing the thermal energy from the band heaters 141 to 144 from flowing toward the centerline. As a result, the thermal energy from the band heaters 141 to 144 is prevented from escaping toward the cooling cylinder 12 in FIG. 1 (the base side in the centerline direction), thereby achieving efficient thermal conduction in the portion of the heating cylinder 31 where a temperature gradient is generated. Furthermore, when trying to create a temperature distribution in the center line direction, the range of influence of each of the band heaters 141 to 144 when the ``thermal conduction anisotropy'' configuration is added (shown by the solid line) is easier to control because the range of influence in the center line direction is narrower than the range of influence of each of the band heaters 141 to 144 when the ``thermal conduction anisotropy'' configuration is not added (shown by the dashed line).

[0053] The "optimization of heat input density" and "anisotropy of heat conduction" in the above-mentioned heat conduction mechanism may be controlled by an information processing device having a function of accepting and setting input of molding conditions including the type and physical properties of pellets, and a function of changing or correcting the set molding conditions. Such an information processing device may be included as part of the above-mentioned injection molding machine, or may be connected to the injection molding machine via a network. [Explanation of symbols]

[0054] 1... injection molding machine, 10, 20, 30... injection unit, 11, 21, 31... heating cylinder, 12... cooling cylinder, 50... mold clamping unit, 101, 102, 103, 104, 105, 106, 141, 142, 143, 144... band heater, 131, 132, 133, 134, 135, 136, 137, 138, 139, 212... heating wire, 111... through hole, 221, 222, 223, 224, 225, 226, 227, 228... fin, 231, 232, 233, 234, 235, 236, 237, 238, 239... slit, 152... water pipe, 400... boundary portion

Claims

1. a cooling member that is cooled by a cooling source to cool an object, and a heating member that is heated by a heating source to heat the object, The temperature distribution of the portion of the heating member where the temperature gradient is generated is changed according to the physical properties of the object. Heat transfer mechanism.

2. The heat input density of the heat source that heats the portion of the heating element that generates the temperature gradient is not constant in a direction away from the cooling element. The heat transfer mechanism of claim 1 .

3. The heat input density gradually increases in a direction away from the cooling member. The heat transfer mechanism of claim 2 .

4. The arrangement intervals of the plurality of heating wires built into the heat source mass become gradually closer in a direction away from the cooling member. The heat transfer mechanism of claim 3 .

5. The heat input density is determined according to physical properties that differ for each type of object. The heat transfer mechanism of claim 2 .

6. a cooling cylinder constituting an injection device of an injection molding machine serves as the cooling member to cool the resin as the object, and a heating cylinder constituting the injection device serves as the heating member to heat the resin; a band heater as the heat source for heating the portion of the heating cylinder that generates the temperature gradient, the band heater having a heat density that is not constant in a direction away from the cooling member; The heat transfer mechanism of claim 2 .

7. a plurality of slits for forming a plurality of fins are provided in a portion of the heating member where a temperature gradient is generated; One or more heating wires are disposed at the tip portions of each of the plurality of fins. The heat transfer mechanism of claim 1 .

8. The heat input density in the portion causing the temperature gradient is not constant in a direction away from the cooling member. The heat transfer mechanism of claim 7.

9. The plurality of heating sources that heat the portion of the heating member that generates the temperature gradient have different heat input densities. The heat transfer mechanism of claim 1 .

10. The heat input density of the plurality of heat sources increases as the heat sources are spaced apart from the cooling member. The heat transfer mechanism of claim 9.

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