Injection molding machine

Abstract

An injection molding machine according to the present invention comprises the following: a cylinder that kneads an injection material supplied from the outside and supplies the kneaded injection material to the outside; a cover that covers the side surface of the cylinder and has a first region and a second region disposed at positions different from one another along a first direction which is the axial direction of the cylinder; a heater that is disposed between the cover and the cylinder and heats the cylinder; and a first heat pipe that thermally connects the first region and the second region of the cover. The first heat pipe is provided to the reverse side of the cover from the surface thereof covering the cylinder.

Description

Injection molding machine

[0001] The present disclosure relates to an injection molding machine, and more specifically to a technique for suppressing excessive temperature rise of a cylinder.

[0002] For molding molded products based on plastic resin or the like in factories, for example, the injection molding machine disclosed in Japanese Patent Application Laid-Open No. 2024-83759 (Patent Document 1) is used. The injection molding machine includes a cylinder that melts resin, which is the material of the molded product.

[0003] Japanese Patent Application Laid-Open No. 2024-83759

[0004] When the cylinder is exposed to ambient air, the temperature of the cylinder may drop sharply. Therefore, wrapping a heat-retaining cover around the outer circumference of the cylinder can prevent a sharp drop in the temperature of the cylinder. However, since heat release is suppressed by the cover, excessive heat may be supplied to the cylinder in some cases. This may cause excessive temperature rise in the cylinder.

[0005] The present disclosure has been made to solve such problems, and an object thereof is to suppress occurrence of excessive temperature rise in a cylinder of an injection molding machine.

[0006] In one aspect, an injection molding machine includes: a cylinder that kneads an injection material supplied from the outside and supplies the kneaded injection material to the outside; a cover that covers a side surface of the cylinder and has a first region and a second region arranged at mutually different positions along a first direction that is an axial direction of the cylinder; a heater arranged between the cover and the cylinder to heat the cylinder; and a first heat pipe that thermally connects the first region and the second region of the cover. Here, the first heat pipe is provided on a side of the cover opposite to a surface that covers the cylinder.

[0007] According to the injection molding machine of the present disclosure, occurrence of excessive temperature rise in a cylinder of the injection molding machine can be suppressed.

[0008] This figure shows the external appearance of an injection molding machine. This figure illustrates the structure of the cover and cylinder in Embodiment 1. This is a perspective view illustrating the configuration of the heat sink and heat pipe. This is Figure 1 showing the temperature detected by the temperature sensor and the duty cycle of the heater. This is Figure 2 showing the temperature detected by the temperature sensor and the duty cycle of the heater. This figure shows a first example of controlling the process of thermally isolating different areas of the cover. This figure shows a second example of controlling the process of thermally isolating different areas of the cover. This figure illustrates the structure of the cover and cylinder in Embodiment 2. This figure shows an example of controlling the process of thermally isolating different areas of the cover in Embodiment 2. This figure illustrates the structure of the cover and cylinder in Embodiment 3. This figure illustrates the structure of the cover in Modification 1. This figure illustrates the thickness of the cover in Modification 1. This figure illustrates the structure of the cover in Modification 2. This figure illustrates the thickness of the cover in Modification 2.

[0009] The embodiments of this disclosure will be described in detail below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and their descriptions will not be repeated.

[0010] [Embodiment 1] <Overall Configuration of Injection Molding Machine> The injection molding machine 100 in Embodiment 1 will be described below. Figure 1 is an external view of the injection molding machine 100. The overall configuration of the injection molding machine 100 will be explained using Figure 1.

[0011] The injection molding machine 100 is mounted on the XY plane. The direction perpendicular to the XY plane is defined as the Z-axis direction. Hereinafter, the positive direction of the Z-axis in Figure 1 may be referred to as the upper side or upward, and the negative direction as the lower side or downward. Although the injection molding machine 100 shown in Figure 1 is shown as a horizontal injection molding machine, the injection molding machine 100 in this embodiment is not limited to a horizontal type and may be a vertical injection molding machine.

[0012] The injection molding process performed by the injection molding machine 100 includes a mold closing process, a mold clamping process, an injection process, a holding pressure process, a cooling and plasticizing process, a mold opening process, and an ejection process. The injection molding machine 100 repeatedly performs the above injection molding process cycle. The injection molding machine 100 is capable of molding molded products of various shapes and materials, and performs injection molding processes according to the shape and material of the molded product.

[0013] The injection molding machine 100 includes a mold clamping device 10 for clamping the mold, an injection device 20 for melting and injecting the injection material, and an operation panel 30. In Figure 1, the mold clamping device 10 is positioned on the negative side of the X-axis relative to the injection device 20.

[0014] <Mold clamping device> The mold clamping device 10 in Embodiment 1 comprises a bed 11, a fixed platen 12, a mold clamping housing 13, a movable platen 14, a tie bar 15, a mold clamping mechanism 16, molds 17 and 18, a ball screw 19, and servo motors 80C and 80D.

[0015] The bed 11 holds the fixed platen 12, the clamping housing 13, and the movable platen 14. The clamping housing 13 and the movable platen 14 are each configured to slide on the bed 11 in the X-axis direction.

[0016] The fixed platen 12 is fixed to the end of the bed 11 on the side closer to the injection unit 20 (i.e., in the positive direction of the X-axis). The clamping housing 13 is located at the end of the bed 11 in the negative direction of the X-axis. The fixed platen 12 and the clamping housing 13 are connected by tie bars 15, which include multiple bars. The clamping housing 13 is movable in the X-axis direction on the bed 11. The injection molding machine 100 in Embodiment 1 has four tie bars 15. However, the number of tie bars 15 in the injection molding machine 100 is not limited to four; for example, there may be five or more.

[0017] The movable platen 14 is positioned on the bed 11 between the fixed platen 12 and the clamping housing 13. The movable platen 14 is configured to move in the X-axis direction. The clamping housing 13 and the movable platen 14 are connected by a clamping mechanism 16. The clamping mechanism 16 has a toggle mechanism. A ball screw 19 is connected to the toggle mechanism, and by driving a servo motor 80C located in the clamping housing 13 to rotate the ball screw 19, the movable platen 14 can be moved relative to the clamping housing 13 in the X-axis direction. Alternatively, a hydraulically driven linear cylinder may be used as the clamping mechanism 16.

[0018] Molds 17 and 18 are positioned on the movable platen 14 and the fixed platen 12, respectively. Molds 17 and 18 are positioned facing each other between the movable platen 14 and the fixed platen 12. The thickness of mold 17, the thickness of mold 18, and the distance between the movable platen 14 and the fixed platen 12 vary depending on the molded product being molded. Molds 17 and 18 are opened and closed by the drive of the mold clamping mechanism 16.

[0019] By moving the mold 17 in the X-axis direction using the mold clamping mechanism 16, the mold 17 and mold 18 can be brought into close contact, or the mold 17 can be separated from the mold 18. The process of transitioning from a separated state to a state in close contact with the mold 17 and mold 18 is called the "mold closing process". The process of tightening the mold with a large force to prevent it from opening due to the pressure during injection from the mold closed state is called the "mold clamping process". The process of transitioning from a state in close contact with the mold 17 and mold 18 to a separated state is called the "mold opening process". The servo motor 80C is a motor used in the mold closing process, mold opening process, and mold clamping process.

[0020] In the mold clamping process, molds 17 and 18 are clamped together, and molten injection material (resin) is filled into the molds. By cooling and solidifying the material, a molded product of the desired shape can be formed. After the molded product is formed, in the mold opening process, mold 17 is separated from mold 18, and the molded product can be removed from mold 17 by operating an ejector mechanism (not shown) located on the movable platen 14. The ejector mechanism is driven by a servo motor 80D located on the movable platen 14. Specifically, for example, the rotation of the servo motor 80D causes a pin (not shown) to protrude, releasing the molded product that is in close contact with mold 17. The servo motor 80D located in the movable platen 14 is a motor used in the ejection process. The process of removing the molded product using the ejector mechanism is called the "ejection process".

[0021] <Injection device> The injection device 20 includes a cylinder 22, a drive mechanism 24, a hopper 25, an injection nozzle 26, a nozzle touch device 27, servo motors 80A and 80B, heaters Ht1 and Ht2, temperature sensors Sr1 and Sr2, and a cooling device R1.

[0022] The drive mechanism 24 includes a cylinder 22 extending in the X-axis direction. Inside the cylinder 22 is a screw 23 for mixing the injection material. The cylinder 22 has a cylindrical shape. More specifically, the cylinder 22 has a cylindrical shape with bottom surfaces on the injection nozzle 26 side and the hopper 25 side. Inside the cylinder 22 is a cavity for housing the screw 23 and the injection material. The shape of the cylinder 22 is not limited to a cylindrical shape; it may be a rectangular prism or a triangular prism, for example, as long as it is a columnar shape capable of housing the screw 23.

[0023] An opening for transporting the injection material is formed in the bottom surface of the cylinder 22 on the injection nozzle 26 side and the hopper 25 side. Hereinafter, the surface connecting the two bottom surfaces of the cylinder 22 will be referred to as the "side surface" of the cylinder 22. The side surface of the cylinder 22 corresponds to the curved surface in the cylindrical shape. The axial direction of the cylinder 22 will be referred to as the "first direction". In Embodiment 1, the first direction corresponds to the X-axis direction.

[0024] The injection molding machine 100 performs a process called the "plasticization process" using a screw 23. The plasticization process is a process of mixing the resin by heating the cylinder 22 with heaters Ht1 and Ht2 and rotating the screw 23. The cylinder 22 is heated by heaters Ht1 and Ht2 to, for example, 180°C to 350°C, melting the injection material. Heaters Ht1 and Ht2 are band heaters that cover the sides of the cylinder 22. In Embodiment 1, an example is shown in which the injection molding machine 100 has two heaters Ht1 and Ht2, but in certain situations the injection molding machine 100 may have three or more heaters, for example, 10 to 30 heaters. In addition, the sides of the cylinder 22 in Embodiment 1 are further covered by a cover that keeps the cylinder 22 warm. In Figure 1, the cover is omitted for simplicity of explanation; the structure of the cylinder 22, including the cover, will be described in detail using Figure 2.

[0025] The servo motor 80B in the drive mechanism 24 rotates the screw 23 with the X-axis direction as its central axis. In other words, the servo motor 80B is a motor used in the plasticization process. The injection molding machine 100 performs a process called the "injection process" and a process called the "holding pressure process". The injection process is the process of injecting the resin that has been plasticized in the plasticization process into the molds 17 and 18. The holding pressure process is the process of applying pressure to hold the resin injected in the injection process inside the molds 17 and 18. Driven by the servo motor 80A, the screw 23 slides in the negative direction of the X-axis. As a result, the plasticized resin is injected into the molds 17 and 18. The servo motor 80A is a motor used in both the injection process and the holding pressure process. After the holding pressure process is completed, a cooling process is performed in parallel to allow the molten molding material to solidify inside the mold, and a plasticization process is performed in parallel to melt, knead, and weigh the material for the next injection. Once the cooling and plasticizing processes are complete, the mold opening and ejection processes are performed to remove the molded product.

[0026] The hopper 25 is located on the positive Z-axis side of the cylinder 22 and stores the injection material before plasticization. That is, the hopper 25 stores the injection material in granular form before it is melted. The injection material stored in the hopper 25 is transported into the cylinder 22 by the drive of the screw 23. A cooling device R1 is positioned near the path through which the injection material passes from the hopper 25 to the cylinder 22.

[0027] The cooling device R1 cools the injection material supplied from the hopper 25 into the cylinder 22. This prevents the granular injection material stored in the hopper 25 from melting due to the heat generated by the heaters Ht1 and Ht2 in the injection molding machine 100. If the injection material melts before reaching the cylinder 22, it can cause blockages in the transport path of the injection material. In other words, in the injection molding machine 100, during the injection molding process, the heaters Ht1 and Ht2 heat the cylinder 22 by generating heat, while the cooling device R1 prevents the injection material in the hopper 25 from melting unintentionally. The cooling device R1 is, for example, a water-cooled device that circulates cooling water.

[0028] The control device 40 can adjust the output of the cooling device R1. The temperature sensor Sr4 detects the temperature of the cooling water circulated by the cooling device R1. The control device 40 acquires the temperature detected by the temperature sensor Sr4 and adjusts the output of the cooling device R1 according to the acquired temperature.

[0029] As shown in Figure 1, heater Ht1 is a heater that heats the area near the center of the cylinder 22, and heater Ht2 is a heater that heats a portion of the cylinder 22 that is closer to the cooling device R1 than heater Ht1.

[0030] The injection material inside cylinder 22 is transported by the rotation of screw 23 from the positive X-axis end P1 of cylinder 22 to the negative X-axis end P2 of cylinder 22. That is, the injection material is first heated by heater Ht2, and then heated by heater Ht1. This kneads the injection material. Temperature sensors Sr1 and Sr2 measure the temperature of cylinder 22 heated by heaters Ht1 and Ht2, respectively. Temperature sensors Sr1 and Sr2 are, for example, thermocouples.

[0031] The mixed injection material is transported to the injection nozzle 26 located at the end P2 of the cylinder 22. The nozzle touch device 27 slides the injection device 20 itself in the X-axis direction, bringing the injection nozzle 26 into contact with the sprue bush of the mold 18. As a result, the injection material is injected into the mold 18.

[0032] The base 21 is positioned on the positive X-axis side of the bed 11 and holds the drive mechanism 24, etc. The base 21 contains a control device 40 and a servo amplifier (not shown) inside. The servo amplifier supplies power to the servo motors 80A to 80D. The control device 40 acquires the temperatures detected by temperature sensors Sr1 and Sr2 and controls the heaters Ht1 and Ht2 respectively based on the acquired temperatures.

[0033] <Control Panel> The control panel 30 includes a display device 31 that displays information related to the injection molding process and an input device 32 that receives operations from the user. The control panel 30 is electrically connected to the control device 40. In the example shown in Figure 1, the control panel 30 is located on the negative side of the Y-axis of the injection molding machine 100. In some cases, the control panel 30 may be provided separately from the injection molding machine 100, for example, in a different room from the room in which the injection molding machine 100 is located.

[0034] The display device 31 is, for example, a display. The input device 32 consists of, for example, a number of buttons. In some cases, the display device 31 and the input device 32 may be integrated as a touch panel. The control panel 30 may also include a microphone and a speaker and accept user input using voice.

[0035] <Structure of the cover and cylinder> Figure 2 is a diagram illustrating the structure of the cover C1 and cylinder 22 in Embodiment 1. Figure 2(A) is a cross-sectional view of the cover C1 and cylinder 22 as seen from the negative X-axis side. Figure 2(B) is a view of the cover C1 and cylinder 22 as seen from the positive Z-axis side. In Figure 2(B), line II-II indicates the position of the cross-section shown in Figure 2(A).

[0036] Cover C1 covers the cylinder 22 so that its sides and heaters Ht1 and Ht2 are not exposed to the outside air. Heaters Ht1 and Ht2 are positioned between cover C1 and the cylinder 22. Heat sinks B1 and B2 are positioned on the outside of cover C1. As shown in Figure 2(A), the cross-sections of the screw 23, cylinder 22, heaters Ht1 and Ht2, heat sinks B1 and B2, and cover C1 are all substantially circular, forming substantially concentric circles around the rotation axis Ax of the screw 23. Of the screw 23, cylinder 22, heaters Ht1 and Ht2, cover C1, and heat sinks B1 and B2, the screw 23 is positioned furthest inward, and the heat sinks B1 and B2 are positioned furthest outward. Note that "outside of cover C1" corresponds to "the side of the cover opposite to the side covering the cylinder."

[0037] Heaters Ht1 and Ht2 heat the regions of cylinder 22 covered by region Rg1 of cover C1 and the regions of cylinder 22 covered by region Rg2 of cover C1, respectively. A target temperature is set for each region of cylinder 22. The target temperatures set for each region of cylinder 22 may be the same or different.

[0038] As shown in Figure 2(A), recesses U1 are formed on the negative Y-axis and negative Z-axis sides of the cross-sections of the cylinder 22, heater Ht2, heat sink B2, and cover C1. A thermocouple temperature sensor Sr2 is inserted into the recess U1. As a result, the temperature sensor Sr2 detects the temperature of the area heated by the heater Ht2.

[0039] The cover C1 prevents heat generated by heaters Ht1 and Ht2 from being released into the outside air. As a result, the power consumption of heaters Ht1 and Ht2 required to melt the injection material in the injection molding machine 100 can be reduced, thus achieving energy savings. The cover C1 is formed using, for example, glass wool.

[0040] The cover C1 that covers the side of the cylindrical cylinder 22 has a shape corresponding to the cylindrical side. The cylinder 22 has an end P1 through which the injection material is supplied from the hopper 25 side, and an end P2 through which the injection material is supplied to the injection nozzle 26. In other words, the inside of the cylinder 22 is open to allow the injection material to pass through.

[0041] The injection material is supplied from end P1 at a lower temperature than the inside of the cylinder 22. Therefore, the temperature at end P1 of the cylinder 22 is lower than the temperature at the center point Mp1 between end P1 and end P2. In addition, end P2 of the cylinder 22 is exposed to the outside air. Therefore, heat is released from end P2 of the cylinder 22. In other words, the heat inside the cylinder 22 is released from ends P1 and P2.

[0042] The center point Mp1 between end P1 and end P2 is the point where the distance X1 from end P1 to center point Mp1 and the distance X2 from end P2 to center point Mp1 are the same. Compared to other positions in the cylinder 22, center point Mp1 has the longest minimum distance between it and either end P1 or end P2. Center point Mp1 is the point in the cylinder 22 where heat is least easily released.

[0043] Therefore, the region near the center point Mp1 in the cylinder 22 is more prone to overheating compared to other regions. Thus, the injection molding machine 100 of Embodiment 1 uses heat pipes HR1 and HL1, as shown in Figure 2(B), to transfer heat from the area near the center point Mp1, which is prone to overheating, to other regions. Specifically, one end of the heat pipes HR1 and HL1 contacts a heat sink B1 located on the opposite side of the surface covering the cylinder 22 in region Rg1 of the cover C1, and the other end of the heat pipes HR1 and HL1 contacts a heat sink B2 located on the opposite side of the surface covering the cylinder 22 in region Rg2 of the cover C1.

[0044] When the temperature of the heat dissipation plate B1 is higher than the temperature of the heat dissipation plate B2, the heat pipes HR1 and HL1 lower the temperature of the heat dissipation plate B1 and increase the temperature of the heat dissipation plate B2. A predetermined liquid as a working fluid is sealed inside the heat pipes HR1 and HL1. The working fluid is, for example, water. The working fluid exchanges heat with the heat dissipation plate B1 at one end of the heat pipes HR1 and HL1 and is heated, thereby absorbing latent heat of vaporization and cooling the heat dissipation plate B1. The evaporated working fluid passes through the decompressed space or vacuum space and moves to the other end of the heat pipes HR1 and HL1, exchanges heat with the heat dissipation plate B2 arranged on the other end side, releases the latent heat of vaporization, and condenses. Thereafter, the condensed working fluid returns to the position where the working fluid evaporated through the inner wall on which a capillary structure (wick) is formed, and circulates in the flow path inside the heat pipes HR1 and HL1. Thereby, the heat pipes HR1 and HL1 can lower the temperature of the heat dissipation plate B1 and increase the temperature of the heat dissipation plate B2.

[0045] Thereby, heat near the center point Mp1 is transported from the region Rg1 of the cover C1 to the region Rg2 of the cover C1 via the heat pipes HR1 and HL1. Therefore, excessive temperature rise of the center point Mp1 of the cylinder 22 can be prevented. Furthermore, by supplying heat to the region Rg2 of the cover C1, the vicinity of the end portion P1 of the cylinder 22 whose temperature is lowered by the injection material can be warmed.

[0046] The injection molding machine 100 according to the first embodiment is configured such that it can not only thermally connect but also thermally insulate the region Rg1 and the region Rg2. Specifically, as shown in Fig. 2, the heat dissipation plate B1 is provided with actuators AR1 and AL1 that change the arrangement of the heat dissipation plate B1, and the heat dissipation plate B2 is provided with actuators AR2 and AL2 that change the arrangement of the heat dissipation plate B2. The actuators AR1 and AL1 are configured to be capable of moving the heat dissipation plate B1 in the radial direction, and the actuators AR2 and AL2 are configured to be capable of moving the heat dissipation plate B2 in the radial direction. By means of the actuators AR1, AL1, AR2, and AL2, the state can be changed between a state where the heat dissipation plates B1 and B2 are in contact with the cover C1 and a state where at least one of the heat dissipation plates B1 and B2 is not in contact with the cover C1. The control device 40 executes a process of thermally insulating the region Rg1 and the region Rg2 based on the satisfaction of a predetermined condition described later. The heat dissipation plates B1 and B2 are heat sinks that improve heat discharge efficiency, and are for example made of metal with high thermal conductivity such as aluminum, iron, and copper. Note that the actuators AR1, AL1, AR2, and AL2 can each operate independently, so it is possible to move only the heat dissipation plate B1, move only the heat dissipation plate B2, or move both the heat dissipation plate B1 and the heat dissipation plate B2.

[0047] In the example of Fig. 2, the cover C1 is shown as covering the entire side surface of the cylinder 22, but in one aspect, the cover C1 may cover only a part of the side surface of the cylinder 22. For example, the cover C1 may cover the half of the side surface of the cylinder 22 on the hopper 25 side, that is, the region from the center point Mp1 shown in Fig. 2 to the end portion P1.

[0048] Fig. 3 is a perspective view for explaining the configuration of the heat dissipation plate and the heat pipe. In Fig. 3, in addition to the heat pipe HR1 shown in Fig. 2(B), heat pipes HU1 and HD1 are shown. As shown in Fig. 2(B), the heat dissipation plates B1 and B2 have a shape corresponding to the curved surface of a cylinder, similarly to the cover C1. The heat pipe HL1 shown in Fig. 2(B) is obstructed by the heat dissipation plate B1 and not shown in Fig. 3.

[0049] When viewed from the negative X-axis side, heat pipe HR1 is positioned on the negative Y-axis side relative to screw 23, and heat pipe HL1 is positioned on the positive Y-axis side relative to screw 23. Also, when viewed from the negative X-axis side, heat pipe HU1 is positioned on the positive Z-axis side relative to screw 23, and heat pipe HD1 is positioned on the negative Z-axis side relative to screw 23. Hereafter, heat pipes HR1, HL1, HD1, and HU1 may be collectively referred to as "heat pipe H1".

[0050] In Embodiment 1, each of the heat pipes H1 is rod-shaped and has the same shape. Each of the heat pipes H1 is in contact with the heat sink B1 and the heat sink B2. Although Embodiment 1 describes a configuration in which four heat pipes H1 are provided, the number of heat pipes H1 is not limited to four; there may be one or five or more.

[0051] In the first embodiment, the injection molding machine 100 has a heat pipe H1 that thermally connects a region Rg1 of the cover C1 that covers a region of the cylinder 22 where overheating is likely to occur, and a region Rg2 of the cover C1 that covers a region of the cylinder 22 where heat is easily released. In other words, by providing the heat pipe H1, the injection molding machine 100 in the first embodiment can lower the temperature of region Rg1, which is closest to the center point Mp1 where heat is least likely to be released, and raise the temperature of region Rg2, which is near the end P1 and where heat is released more easily than in region Rg1. This makes it possible to bring the temperature of each region of the cylinder 22 heated by heaters Ht1 and Ht2 closer to the respective set target temperature. Furthermore, the injection molding machine 100 in the first embodiment can suppress overheating in the cylinder 22.

[0052] Furthermore, as shown in Figure 2, the region of cylinder 22 covered by region Rg2 is closer to the cooling device R1 than the region of cylinder 22 covered by region Rg1. In other words, since region Rg2, which exchanges heat with the heat pipe H1 via the heat sink B2, is closer to the cooling device R1 than region Rg1, the region of cylinder 22 covered by region Rg2 can exchange heat with the cooling device R1 via the end P1. That is, the temperature of the region of cylinder 22 covered by region Rg2 may decrease due to the cooling by the cooling device R1.

[0053] In order to maintain a high temperature in the cylinder 22 region covered by region Rg2, it is conceivable to increase the watt density of the heater Ht2. However, providing a heater with a high watt density may increase costs. Furthermore, providing a heater with a high watt density may also increase power consumption. In the injection molding machine 100 of Embodiment 1, heat is transferred from region Rg1 to region Rg2 by the heat pipe H1, so it is possible to suppress the decrease in temperature in the cylinder 22 region covered by region Rg2 without providing a heater with a high watt density as the heater Ht2.

[0054] In Embodiment 1, region Rg1 is an example of the "first region" in this disclosure. Region Rg2 is an example of the "second region" in this disclosure. Heat pipe HR1 is an example of the "first heat pipe" in this disclosure. Heat pipes HU1, HD1, and HL1 are examples of the "third heat pipe" in this disclosure. Heat sink B1 is an example of the "first heat sink" in this disclosure. Heat sink B2 is an example of the "second heat sink" in this disclosure.

[0055] Furthermore, in the example explained in Figure 2, region Rg1 of cover C1 covers the center point Mp1 of cylinder 22. However, if region Rg1 is closer to the center point Mp1 than region Rg2, region Rg1 does not need to cover the center point Mp1. In other words, region Rg1 should cover a region in cylinder 22 where heat is less easily released than the region covered by region Rg2.

[0056] The injection device 20 may also include a cylinder cover (not shown). The cylinder cover covers the cylinder 22, the screw 23, the heaters Ht1 and Ht2, the heat pipe H1, the heat sinks B1 and B2, and the cover C1. The cylinder cover is made of, for example, metal, and protects the cylinder 22 from external impacts and prevents the user from accidentally touching the surface of the cover C1, which becomes hot.

[0057] [Comparison of Temperature Changes] Figure 4 is the first figure showing the detected temperatures of temperature sensors Sr1 and Sr2 and the duty cycles of heaters Ht1 and Ht2. The upper part of Figure 4 shows graph G1, which shows the detected temperatures of temperature sensors Sr1 and Sr2, and the lower part of Figure 4 shows graph G2, which shows the duty cycles of heaters Ht1 and Ht2. Graphs G1 and G2 share the same horizontal time axis. The duty cycle is the ratio of the on period to the total on period of the heater. The higher the duty cycle, the higher the heater temperature and the greater the power consumption. The lower the duty cycle, the lower the heater temperature and the greater the power consumption.

[0058] As shown in Figure 2, heater Ht1 is located inside region Rg1 of cover C1, and heater Ht2 is located inside region Rg2 of cover C1. That is, heater Ht1 raises the temperature of the region of cylinder 22 covered by region Rg1 of cover C1, and heater Ht2 raises the temperature of the region of cylinder 22 covered by region Rg2 of cover C1. In addition, temperature sensor Sr1 detects the temperature of the region of cylinder 22 covered by region Rg1 of cover C1, and temperature sensor Sr2 detects the temperature of the region of cylinder 22 covered by region Rg2 of cover C1.

[0059] As described above, the cylinder 22 can be heated by heaters Ht1 and Ht2 to a temperature of, for example, 180°C to 350°C. That is, the target temperature range that the cylinder 22 can take is, for example, 180°C to 350°C. As described above, different target temperatures may be set for each region of the cylinder 22.

[0060] In the example shown in Figure 4, the target temperature of cylinder 22 is set to 180°C. In other words, a relatively low target temperature is set for cylinder 22. Figure 4 illustrates how the injection molding machine 100 of Embodiment 1 can suppress the occurrence of overheating that occurs when a relatively low target temperature is set for cylinder 22.

[0061] Referring to Figure 4, lines T1 and T2 in graph G1 indicate the detected temperatures of temperature sensors Sr1 and Sr2 in Embodiment 1, respectively. Lines Tz1 and Tz2 indicate the detected temperatures of temperature sensors Sr1 and Sr2 in the Comparative Example. The Comparative Example is an injection molding machine having a configuration in which the heat pipe H1 is removed from the injection molding machine 100 of Embodiment 1.

[0062] The control device 40 controls the heaters Ht1 and Ht2 based on the detected temperatures obtained from the temperature sensors Sr1 and Sr2. For example, the control device 40 controls the heaters Ht1 and Ht2 using PID control. This allows the control device 40 to determine the duty cycle of the heaters Ht1 and Ht2 according to the difference between the target temperature and the detected values ​​from the temperature sensors Sr1 and Sr2.

[0063] Furthermore, the control device 40 may not use PID control. Instead, if the temperature detected by the temperature sensor Sr1 is lower than the target temperature, the duty cycle of the heater Ht1 may be increased, and if the temperature detected by the temperature sensor Sr1 is higher than the target temperature, the duty cycle of the heater Ht1 may be decreased. Similarly, the control device 40 may increase the duty cycle of the heater Ht2 if the temperature detected by the temperature sensor Sr2 is lower than the target temperature, and decrease the duty cycle of the heater Ht2 if the temperature detected by the temperature sensor Sr2 is higher than the target temperature.

[0064] Lines D1 and D2 in graph G2 represent the duty cycles of heaters Ht1 and Ht2 in Embodiment 1, respectively. Lines Dz1 and Dz2 represent the duty cycles of heaters Ht1 and Ht2 in the comparative example, respectively.

[0065] First, let's focus on the lines Tz1 and Dz1 in the comparative example in Figure 4. In the comparative example without the heat pipe H1, as the detected temperatures of the temperature sensors Sr1 and Sr2 approach the target temperature, the control device 40 controls the duty cycle of the heaters Ht1 and Ht2 to decrease. That is, when the target temperature is reached, the control device 40 decreases the duty cycle to maintain the target temperature.

[0066] After exceeding the target temperature, a large overshoot occurs in the temperature detected by the temperature sensor Sr1 of the comparative example, as shown by the line Tz1 in graph G1. This is because, as mentioned above, the region of cylinder 22 detected by the temperature sensor Sr1 does not release heat easily.

[0067] As the temperature detected by the temperature sensor Sr1 significantly exceeds the target temperature, the control device 40 continues to maintain a state where the duty cycle of the heater Ht1 is 0%, as shown by line Dz1. In other words, power is no longer supplied to the heater Ht1. However, since the region of the cylinder 22 detected by the temperature sensor Sr1 does not easily release heat, even if heating by the heater Ht1 is stopped, the temperature in that region remains higher than the target temperature. If the temperature remains higher than the target temperature, overheating may occur near the center point Mp1 of the cylinder 22.

[0068] Next, let's focus on lines T1 and D1 in Embodiment 1. In Embodiment 1, which has a heat pipe H1, the overshoot along line T1 is smaller than the overshoot along line Tz1 after the temperature detected by the temperature sensor Sr1 exceeds the target temperature. This is because the heat from region Rg1 is transferred to region Rg2 by the heat pipe H1. As a result, in Embodiment 1, the timing at which the temperature detected by the temperature sensor Sr1 is controlled to the target temperature is earlier than in the comparative example, and it is possible to suppress the maintenance of a temperature higher than the target temperature.

[0069] Figure 5 is the second figure showing the detected temperatures of temperature sensors Sr1 and Sr2 and the duty cycles of heaters Ht1 and Ht2. The upper part of Figure 5 shows graph G3, which shows the detected temperatures of temperature sensors Sr1 and Sr2, and the lower part of Figure 5 shows graph G4, which shows the duty cycles of heaters Ht1 and Ht2. Graphs G3 and G4 share the same horizontal time axis.

[0070] In the example shown in Figure 5, the target temperature for cylinder 22 is set to 350°C. A relatively high target temperature is set for cylinder 22. Figure 5 illustrates how the injection molding machine 100 of Embodiment 1 can suppress the occurrence of temperature deficiency that can occur when a relatively high target temperature is set for cylinder 22.

[0071] Referring to Figure 5, lines T3 and T4 in graph G3 show the detected temperatures of temperature sensors Sr1 and Sr2 in Embodiment 1, respectively. Lines Tz3 and Tz4 show the detected temperatures of temperature sensors Sr1 and Sr2 in the comparative example. Lines D3 and D4 in graph G4 show the duty cycles of heaters Ht1 and Ht2 in Embodiment 1, respectively. Lines Dz3 and Dz4 show the duty cycles of heaters Ht1 and Ht2 in the comparative example, respectively. The comparative example is an injection molding machine having a configuration in which the heat pipe H1 is removed from the injection molding machine 100 of Embodiment 1.

[0072] Let's focus on the lines Tz4 and Dz4 in the comparative example in Figure 5. In the comparative example without a heat pipe H1, external factors such as the operation of the cooling device R1 and the change in the type of injection material can cause the temperature of the region of the cylinder 22 covered by region Rg2 of the cover C1 to decrease. That is, the temperatures detected by temperature sensors Sr1 and Sr2 become lower than the target temperature. As a result, the control device 40 controls the duty cycle of heaters Ht1 and Ht2 to increase. In the example in Figure 5, as the temperature detected by temperature sensor Sr2 shown by line Tz4 decreases, the control device 40 maintains the duty cycle of heater Ht2 at its maximum value (100%).

[0073] However, in the comparative example, heat from the cylinder 22 is released from the end P1 due to external factors such as the operation of the cooling device R1. As a result, the temperature of the region of the cylinder 22 covered by the region Rg2 of the cover C1 near the end P1 cannot be raised to the target temperature, and the state of insufficient temperature is maintained.

[0074] Next, let's focus on lines T4 and D4 in Embodiment 1. In Embodiment 1, which has a heat pipe H1, after the temperature detected by the temperature sensor Sr2 decreases, it converges to the target temperature at an earlier timing than line Tz4. This is because the heat from region Rg1 is transferred to region Rg2 by the heat pipe H1. As a result, as shown by line T4, in Embodiment 1, the temperature detected by the temperature sensor Sr2 is controlled to the target temperature faster than in the comparative example, and it is possible to prevent insufficient temperature in the region of the cylinder 22 covered by region Rg2 of the cover C1.

[0075] <Control Example 1> Figures 2 to 5 describe a configuration in which heat from region Rg1, where heat is difficult to dissipate, is transferred to region Rg2, where heat is easily dissipated, using a heat pipe H1. However, it is possible that the heat pipe H1 may cause an excessive decrease in the temperature of the region of cylinder 22 covered by region Rg1 of cover C1, or an excessive increase in the temperature of the region of cylinder 22 covered by region Rg2 of cover C1. Figure 6 describes a process to thermally isolate region Rg1 and region Rg2 when an excessive decrease in the temperature of region Rg1 or an excessive increase in the temperature of region Rg2 occurs.

[0076] Figure 6 shows a first example of controlling the process of thermally isolating region Rg1 and region Rg2. The flowchart shown in Figure 6 is stored as a program in a memory device accessible by the control device 40. The control device 40 repeatedly executes the flowchart shown in Figure 6 while the injection molding process is being performed by the injection molding machine 100.

[0077] The control device 40 acquires the temperature detected by the temperature sensor Sr1 (step S101). The control device 40 acquires the temperature detected by the temperature sensor Sr2 (step S102). The control device 40 compares the temperature detected by the temperature sensor Sr1 acquired in step S101 with a first target value, and compares the temperature detected by the temperature sensor Sr2 acquired in step S102 with a second target value.

[0078] The first target value is, for example, the lower limit of the temperature in the region of cylinder 22 covered by region Rg1 of cover C1. The first target value may be a predetermined temperature higher than the lower limit of the temperature in the region of cylinder 22 covered by region Rg1 of cover C1. The second target value is, for example, the upper limit of the temperature in the region of cylinder 22 covered by region Rg2 of cover C1. The second target value may be a predetermined temperature lower than the upper limit of the temperature in the region of cylinder 22 covered by region Rg2 of cover C1. Since the heat pipe H1 is provided to transfer heat from region Rg1 to region Rg2, the first target value is higher than the second target value.

[0079] The first target value is the temperature at which there is a risk of insufficient heat in the region of cylinder 22 covered by region Rg1 of cover C1. The second target value is the temperature at which there is a risk of overheating in the region of cylinder 22 covered by region Rg2 of cover C1. The first and second target values ​​are determined according to the target temperature. The control device 40 determines whether the temperature detected by temperature sensor Sr1 is below the first target value or whether the temperature detected by temperature sensor Sr2 is above the second target value (step S103).

[0080] If the temperature detected by temperature sensor Sr1 falls below the first target value, or if the temperature detected by temperature sensor Sr2 exceeds the second target value (YES in step S103), the control device 40 performs a process to thermally isolate region Rg1 and region Rg2 (step S104). After that, the control device 40 terminates the process shown in Figure 6. If the temperature detected by temperature sensor Sr1 does not fall below the first target value, and the temperature detected by temperature sensor Sr2 does not exceed the second target value (NO in step S103), the control device 40 terminates the process shown in Figure 6.

[0081] The following describes the process of thermally isolating regions Rg1 and Rg2 in step S104. The process in step S104 is to move at least one of the heat sinks B1 and B2. Specifically, it is a process of moving heat sink B1 radially using actuators AR1 and AL1, and / or moving heat sink B2 radially using actuators AR2 and AL2. By moving at least one of the heat sinks B1 and B2 through this process, heat sink B1 and / or heat sink B2 become non-contact with cover C1. As a result, regions Rg1 and Rg2 of cover C1 are thermally isolated. That is, heat from region Rg1 is no longer transferred to region Rg2. In this way, the injection molding machine 100 can thermally isolate regions Rg1 and Rg2 without increasing the workload of the user. Actuators AR1 and AL1 may also stop the circulation of the working fluid in the heat pipe H1 by driving a switching device provided in the flow path of the heat pipe H1.

[0082] Furthermore, the process in step S104 may be, for example, a process to notify the user that the heat pipe H1 should be removed. Specifically, the control device 40 notifies the user that the heat pipe H1 should be removed using a display device 31, a speaker (not shown), an indicator light, etc. This allows the injection molding machine 100 to notify the outside that the presence of the heat pipe H1 may cause insufficient temperature in region Rg1 or excessive temperature rise in region Rg2. By removing the heat pipe H1, the user can thermally isolate region Rg1 and region Rg2.

[0083] The process in step S104 may be either a process to change the arrangement of at least one of the heat sinks B1 and B2, or a process to inform the user that the heat pipe H1 should be removed, or both may be performed simultaneously. Note that temperature sensor Sr1 is an example of the "first temperature sensor" in this disclosure. Also, temperature sensor Sr2 is an example of the "second temperature sensor" in this disclosure.

[0084] <Control Example 2> In Figure 6, a control example is shown in which a process is performed to thermally isolate regions Rg1 and Rg2 by comparing the detected temperatures of temperature sensors Sr1 and Sr2 with the first target value and the second target value, respectively. The first target value and the second target value are temperatures set for cylinder 22. In Figure 7, a control example is shown in which a process is performed to thermally isolate heat pipe H1 from regions Rg1 and / or Rg2 by comparing the detected temperatures of temperature sensors Sr1 and Sr2 with the first overheat reference value and the second overheat reference value, respectively. The first overheat reference value and the second overheat reference value are temperatures set for heat pipe H1.

[0085] Generally, heat pipes have a set heat resistance temperature. Using a heat pipe when it exceeds its heat resistance temperature may cause it to break. For example, the first and second overheating threshold values ​​are the heat resistance temperatures of the heat pipe H1. Alternatively, the first and second overheating threshold values ​​may be the temperature of the cylinder 22 when region Rg1 or region Rg2 of the cover C1 reaches the heat resistance temperature of the heat pipe H1. When the temperature detected by the temperature sensor Sr1 exceeds the first overheating threshold value, thermal isolation between the heat pipe H1 and region Rg1 can prevent the heat pipe H1 from exceeding its heat resistance temperature and breaking. Similarly, when the temperature detected by the temperature sensor Sr2 exceeds the second overheating threshold value, thermal isolation between the heat pipe H1 and region Rg2 can prevent the heat pipe H1 from exceeding its heat resistance temperature and breaking.

[0086] Figure 7 shows a second example of controlling the process of thermally isolating the heat pipe H1 from region Rg1 and / or region Rg2. The flowchart shown in Figure 7 is stored as a program in a memory device accessible by the control device 40. The control device 40 repeatedly executes the flowchart shown in Figure 7 while the injection molding process is being performed by the injection molding machine 100.

[0087] The control device 40 acquires the temperature detected by the temperature sensor Sr1 (step S201). The control device 40 acquires the temperature detected by the temperature sensor Sr2 (step S202). The control device 40 compares the temperature detected by the temperature sensor Sr1 acquired in step S201 with a first overheat reference value, and compares the temperature detected by the temperature sensor Sr2 acquired in step S202 with a second overheat reference value.

[0088] The first overheating threshold is the temperature in the region of cylinder 22 where the temperature in region Rg1 may exceed the heat resistance temperature of the heat pipe H1. The first overheating threshold is determined according to the heat resistance temperature of the heat pipe H1. The control device 40 determines whether the temperature detected by the temperature sensor Sr1 exceeds the first overheating threshold (step S203).

[0089] If the temperature detected by the temperature sensor Sr1 exceeds the first overheating threshold (YES in step S203), the control device 40 performs a process to thermally isolate the heat pipe H1 from the region Rg1 (step S204). If the temperature detected by the temperature sensor Sr1 does not exceed the first overheating threshold (NO in step S203), the control device 40 proceeds to step S205.

[0090] The second overheating threshold is the temperature in the region of cylinder 22 where the temperature in region Rg2 may exceed the heat resistance temperature of the heat pipe H1. The second overheating threshold is determined according to the heat resistance temperature of the heat pipe H1. The control device 40 determines whether the temperature detected by the temperature sensor Sr2 exceeds the second overheating threshold (step S205).

[0091] If the temperature detected by the temperature sensor Sr2 exceeds the second overheating threshold (YES in step S205), the control device 40 performs a process to thermally isolate the heat pipe H1 from the region Rg1 (step S206). After that, the control device 40 terminates the process shown in Figure 7. If the temperature detected by the temperature sensor Sr2 does not exceed the second overheating threshold (NO in step S205), the control device 40 terminates the process shown in Figure 7.

[0092] The following describes the process of thermally isolating the heat pipe H1 from region Rg1 in step S204. The process in step S204 is to drive the actuators AR1 and AL1 provided on the heat sink B1. Specifically, when the temperature detected by the temperature sensor Sr1 exceeds the first overheating reference value, the control device 40 drives actuators AR1 and AL1 to make the heat sink B1 non-contact with the cover C1. As a result, the heat pipe H1 is thermally isolated from region Rg1 of the cover C1.

[0093] Next, the process of thermally isolating the heat pipe H1 from region Rg2 in step S206 will be described. The process in step S206 is to drive the actuators AR2 and AL2 provided on the heat sink B2. Specifically, when the temperature detected by the temperature sensor Sr2 exceeds the second overheating reference value, the control device 40 drives actuators AR2 and AL2 to make the heat sink B2 non-contact with the cover C1. As a result, the heat pipe H1 is thermally isolated from region Rg2 of the cover C1.

[0094] Furthermore, the processes in steps S204 and S206 may, for example, be processes that notify the user that the heat pipe H1 should be removed. Specifically, the control device 40 notifies the user that the heat pipe H1 should be removed using a display device 31, a speaker (not shown), an indicator light, etc. This allows the injection molding machine 100 to notify the outside that the heat pipe H1 may be overheated. By removing the heat pipe H1, the user can thermally isolate the heat pipe H1 from regions Rg1 and Rg2.

[0095] The process in step S204 may be either a process to drive actuators AR1 and AL1 or a process to inform the user that the heat pipe H1 should be removed, or both may be performed simultaneously. Similarly, the process in step S206 may be either a process to drive actuators AR2 and AL2 or a process to inform the user that the heat pipe H1 should be removed, or both may be performed simultaneously. Note that temperature sensor Sr1 is an example of the "first temperature sensor" in this disclosure. Temperature sensor Sr2 is an example of the "second temperature sensor" in this disclosure.

[0096] This prevents the heat pipe H1 from overheating beyond its heat resistance temperature and being damaged in the injection molding machine 100 of Embodiment 1.

[0097] [Embodiment 2] The injection molding machine in Embodiment 2 will be described below with reference to Figure 8. Figure 8 is a diagram illustrating the structure of the cover C1 and cylinder 22 in Embodiment 2. Note that in Embodiment 2, the same configuration as in Embodiment 1 will not be repeated in the description.

[0098] Figure 8(A) is a cross-sectional view of the cover C1 and cylinder 22 as seen from the negative X-axis side in Embodiment 2. Figure 8(B) is a view of the cover C1 and cylinder 22 as seen from the positive Z-axis side in Embodiment 2. Line III-III in Figure 8(B) indicates the position of the cross-section shown in Figure 8(A).

[0099] In Embodiment 2, in addition to heat pipes HR1 and HL1, there are heat pipes HR2 and HL2. Hereinafter, heat pipes HR2 and HL2 will be collectively referred to as "heat pipe H2". Note that heat pipe H2 may include four heat pipes, or it may include five or more heat pipes, similar to heat pipe H1.

[0100] In the injection molding machine of Embodiment 2, a heat pipe H2 is used to thermally connect region Rg1 of the cover C1 with region Rg3, which is closer to the end P2 of the cylinder 22 than region Rg1, thereby transferring heat from region Rg1 to region Rg3. Region Rg1 is the region closer to the center point Mp1 than region Rg3. As shown in Figure 8, region Rg3 is the region closer to the injection nozzle 26 than region Rg1. Therefore, the region of the cylinder 22 covered by region Rg3 of the cover C1 easily releases heat through heat exchange with the injection nozzle 26. A heater Ht3 is placed inside region Rg3. A heat sink B3 is placed outside region Rg3. Furthermore, the injection molding machine in Embodiment 2 is further equipped with a temperature sensor Sr3 for detecting the temperature of region Rg3.

[0101] As shown in Figure 8, in the injection molding machine of Embodiment 2, a region Rg1 in which heat is difficult to dissipate and a region Rg3 in which heat is easily dissipated are thermally connected by a heat pipe H2 in the cover C1. In other words, by providing the heat pipe H2, the injection molding machine of Embodiment 2 can lower the temperature of region Rg1, which includes the central point Mp1 in which heat is most difficult to dissipate, and raise the temperature of region Rg3, which is near the end P2 and in which heat is more easily dissipated than in region Rg1. As a result, it is possible to bring the temperature of each region of the cylinder 22 closer to the set target temperature, and in the injection molding machine of Embodiment 2, overheating in the cylinder 22 can be suppressed.

[0102] Heat pipe H2 is an example of a "second heat pipe" in this disclosure. Region Rg3 is an example of a "third region" in this disclosure.

[0103] Figure 9 shows an example of control for the process of thermally isolating region Rg1 and region Rg2, and the process of thermally isolating region Rg1 and region Rg3 in Embodiment 2. The control device 40 repeats the execution of the flowchart shown in Figure 9 while the injection molding process is being performed by the injection molding machine 100.

[0104] The control device 40 acquires the temperature detected by the temperature sensor Sr1 (step S301). The control device 40 also acquires the temperature detected by the temperature sensor Sr2 (step S302). Furthermore, the control device 40 acquires the temperature detected by the temperature sensor Sr3 (step S303).

[0105] The control device 40 determines whether the temperature detected by the temperature sensor Sr1 has fallen below the first target value (step S304). If the temperature detected by the temperature sensor Sr1 has fallen below the first target value (YES in step S304), the control device 40 performs a process to thermally isolate region Rg1 and region Rg2, and a process to thermally isolate region Rg1 and region Rg3 (step S305). As a result, the injection molding machine of the second embodiment can prevent the temperature of the region of the cylinder 22 covered by region Rg1 of the cover C1 from falling significantly below the first target value. After that, the control device 40 terminates the process shown in Figure 9.

[0106] If the temperature detected by the temperature sensor Sr1 is not below the first target value (NO in step S304), the control device 40 compares the temperature detected by the temperature sensor Sr2 obtained in step S302 with the second target value. That is, the control device 40 determines whether the temperature detected by the temperature sensor Sr2 exceeds the second target value (step S306). If the temperature detected by the temperature sensor Sr2 exceeds the second target value (YES in step S306), the control device 40 executes a process to thermally isolate region Rg1 and region Rg2 (step S307). As a result, the injection molding machine of embodiment 2 can suppress the occurrence of overheating in the region of the cylinder 22 covered by region Rg2 of the cover C1.

[0107] If the temperature detected by the temperature sensor Sr2 is not below the second target value (NO in step S306), the control device 40 compares the temperature detected by the temperature sensor Sr3, acquired in step S303, with the third target value.

[0108] The third target value is, for example, the upper limit of the temperature set for the region of cylinder 22 covered by region Rg3 of cover C1. The third target value may be a predetermined temperature lower than the upper limit of the temperature set for the region of cylinder 22 covered by region Rg3 of cover C1. Since the heat pipe H2 is provided to transfer heat from region Rg1 to region Rg3, the first target value is a higher temperature than the third target value.

[0109] The control device 40 determines whether the temperature detected by the temperature sensor Sr3 exceeds the third target value (step S308). If the temperature detected by the temperature sensor Sr3 exceeds the third target value (YES in step S308), the control device 40 performs a process to thermally isolate region Rg1 and region Rg3 (step S309). As a result, the injection molding machine of embodiment 2 can suppress the occurrence of overheating in the region of the cylinder 22 covered by region Rg3 of the cover C1. After that, the control device 40 terminates the process shown in Figure 9. If the temperature detected by the temperature sensor Sr3 is not below the third target value (NO in step S308), the control device 40 terminates the process shown in Figure 9.

[0110] Furthermore, the control example described in Figure 6 can also be applied to the configuration of Embodiment 2 by taking into account the detected value of the temperature sensor Sr3. In addition, the injection molding machine in Embodiment 2 can also perform the process described in Figure 7.

[0111] [Embodiment 3] The injection molding machine in Embodiment 3 will be described below with reference to Figure 10. Figure 10 is a diagram illustrating the structure of the cover C1 and cylinder 22 in Embodiment 3. Note that in Embodiment 3, the same configurations as in Embodiments 1 and 2 will not be described again.

[0112] Figure 10(A) is a cross-sectional view of the cover C1 and cylinder 22 as seen from the negative X-axis side in Embodiment 3. Figure 10(B) is a view of the cover C1 and cylinder 22 as seen from the positive Z-axis side in Embodiment 3. The line IV-IV in Figure 10(B) indicates the position of the cross-section shown in Figure 10(A).

[0113] As shown in Figure 10(A), recesses U2 are formed on the negative Y-axis and negative Z-axis sides of the cross-sections of the cylinder 22, heater Ht1, heat sink B1, and cover C1. A thermocouple temperature sensor Sr1 is inserted into the recess U2. As a result, the temperature sensor Sr1 detects the temperature of the area heated by the heater Ht1.

[0114] In the injection molding machine 100 of Embodiment 3, the position of region Rg2 is different from that of Embodiment 1. As shown in Figure 10, region Rg2 is closer to the injection nozzle 26 than region Rg1. Therefore, the heat in the region of cylinder 22 covered by region Rg2 is easily released through the end P2 of cylinder 22.

[0115] In the injection molding machine of Embodiment 3, a region Rg1 in which heat is difficult to dissipate and a region Rg2 in which heat is easily dissipated are thermally connected by a heat pipe H1 in the cover C1. In other words, by providing the heat pipe H1, the injection molding machine of Embodiment 3 can lower the temperature of region Rg1 covering the central point Mp1 in which heat is most difficult to dissipate, and raise the temperature of region Rg2 covering the region of the cylinder 22 near the end P2 in which heat is more easily dissipated than in region Rg1. As a result, it is possible to bring the temperature of each region of the cylinder 22 closer to the set target temperature, and in the injection molding machine of Embodiment 3, overheating in the cylinder 22 can be suppressed.

[0116] In Embodiment 3, the heat pipe H1 is an example of the "first heat pipe" in this disclosure. Region Rg1 is an example of the "first region" in this disclosure. Region Rg2 is an example of the "second region" in this disclosure.

[0117] [Modification 1] Generally, a heat pipe requires a temperature gradient between the heat-absorbing surface and the heat-dissipating surface of the heat pipe, with the boiling point of the working fluid inside the heat pipe in between. That is, for a heat pipe to transport heat, the heat-absorbing surface of the heat pipe must be at or above the boiling point of the working fluid, and the heat-dissipating surface of the heat pipe must be at or below the boiling point of the working fluid. However, in the injection molding machine 100 of Embodiment 1, there may be cases where the temperature in region Rg1 is not at or above the boiling point of the working fluid, and where the temperature in region Rg2 is not at or below the boiling point of the working fluid. In such cases, the heat pipe H1 cannot transport heat from region Rg1 to region Rg2.

[0118] In Modification 1, the thickness of the cover C2 in region Rg1 of the injection device is different from the thickness of the cover C2 in region Rg2. Specifically, the thickness of the cover C2 in region Rg2 is greater than the thickness of the cover C2 in other regions. This allows the temperature on the heat absorption surface and the heat dissipation surface of the heat pipe H1 to be adjusted to a temperature at which the heat pipe H1 can transport heat, thereby enabling the heat pipe H1 to operate.

[0119] Figure 11 is a cross-sectional view of the cover C2 and cylinder 22 in Modification 1, viewed from the negative X-axis direction. Figure 12 is a view of the cover C2 and cylinder 22 in Modification 1, viewed from the positive Z-axis direction. Lines IV-IV and V-V in Figure 11 indicate the positions of the cross-sections shown in Figure 12.

[0120] Referring to Figures 11 and 12, in the modified example 1, the thickness of cover C2 in region Rg2 is greater than that of other regions including region Rg1. Therefore, less heat is transferred to region Rg2 from the heater Ht2 and cylinder 22 than to other regions including region Rg1. This makes it possible to adjust the temperature in region Rg2, which corresponds to the heat absorption surface of the heat pipe H1, to a temperature below the liquid boiling point of the working fluid of the heat pipe H1.

[0121] [Modification 2] In Modification 1, an example was described in which the thickness of the cover C2 in region Rg2 is made thicker than that of other regions including region Rg1, thereby adjusting the temperature in region Rg2, which corresponds to the heat absorption surface of the heat pipe H1, to a temperature below the liquid boiling point of the working fluid of the heat pipe H1. In Modification 2, an example is described in which the thickness of the cover C3 in region Rg1 is made thinner than that of other regions including region Rg2, thereby adjusting the temperature in region Rg1, which corresponds to the heat dissipation surface of the heat pipe H1, to a temperature above the liquid boiling point of the working fluid of the heat pipe H1.

[0122] Figure 13 is a cross-sectional view of the cover C3 and cylinder 22 in Modification 2, viewed from the negative X-axis direction. Figure 14 is a view of the cover C3 and cylinder 22 in Modification 2, viewed from the positive Z-axis direction. Lines VI-VI and VII-VII in Figure 13 indicate the positions of the cross-sections shown in Figure 14.

[0123] Referring to Figures 13 and 14, in the modified example 2, the thickness of cover C3 in region Rg1 is thinner than in other regions including region Rg2. Therefore, heat is transferred more easily from the heater Ht1 and cylinder 22 to region Rg1 than to other regions including region Rg2. This makes it possible to adjust the temperature in region Rg1, which corresponds to the heat dissipation surface of the heat pipe H1, to a temperature above the liquid boiling point of the working fluid of the heat pipe H1.

[0124] Thus, according to Modification 1 and Modification 2, however, it is possible to adjust the temperature so that the temperature on the heat-absorbing surface of the heat pipe is above the boiling point of the working fluid, and the temperature on the heat-dissipating surface of the heat pipe is below the boiling point of the working fluid. This prevents a situation where the temperature of the heat pipe differs from the operating conditions of the heat pipe, resulting in the heat pipe being unable to transport heat.

[0125] In addition to the injection apparatus described in Modification 1 and Modification 2, the thickness of region Rg1 and region Rg2 of the cover may differ from the thickness of other regions of the cover C1. Furthermore, instead of changing the thickness of the cover, the material may be changed depending on the region of the cover. Specifically, region Rg2 is made of a material that conducts heat less efficiently than region Rg1. This makes it possible to adjust the temperature so that the temperature on the heat-absorbing surface of the heat pipe is above the boiling point of the working fluid, and the temperature on the heat-dissipating surface of the heat pipe is below the boiling point of the working fluid.

[0126] Furthermore, the examples described in Modification 1 and Modification 2, where the thickness of the cover differs for each region, can also be applied to Embodiments 2 and 3.

[0127] In the embodiments 1 to 3 and modifications 1 and 2 described above, the heat pipe was provided on the side of the cover opposite to the side covering the cylinder. For example, even if the heat pipe is provided between the heater and the cover, heat can be transported from a region in the cylinder 22 where heat is difficult to release to a region where heat is easily released.

[0128] However, if a heat pipe is installed inside the cover, the heat pipe will be in contact with the cylinder and heater and will therefore become hot. Specifically, if a heat pipe is installed inside the cover, it may be heated to temperatures of, for example, 180°C to 350°C. Under these conditions, in order for the heat pipe to transport heat, it becomes necessary to use a working fluid with a boiling point higher than the temperature at which the heat pipe can be heated. Generally, a heat pipe using a working fluid with a boiling point higher than 180°C to 350°C is more expensive than a heat pipe using a working fluid with a boiling point lower than 180°C to 350°C. Therefore, an injection molding machine equipped with a heat pipe inside the cover may have higher manufacturing costs than the injection molding machines described in Embodiments 1 to 3 and Modifications 1 and 2 described above.

[0129] In the injection molding machines described in Embodiments 1 to 3 and Modifications 1 and 2 above, the heat pipe is located on the outside of the cover, and its temperature is lower than when the heat pipe is located on the inside of the cover. Therefore, a working fluid with a lower boiling point can be used, thereby reducing the manufacturing cost of the injection molding machine. Furthermore, in the injection molding machines described in Embodiments 1 to 3 and Modifications 1 and 2, if the temperature of the heat pipe does not exceed 100°C, water can be used as the working fluid, further reducing the manufacturing cost of the injection molding machine.

[0130] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this disclosure is indicated by the claims rather than the foregoing description, and all modifications within the meaning and scope of equivalents of the claims are intended.

[0131] 10 Clamping device, 11 Bed, 12 Fixed platen, 13 Clamping housing, 14 Movable platen, 15 Tie bar, 16 Clamping mechanism, 17, 18 Mold, 19 Ball screw, 20 Injection device, 21 Base, 22 Cylinder, 23 Screw, 24 Drive mechanism, 25 Hopper, 26 Injection nozzle, 27 Nozzle touch device, 30 Control panel, 31 Display device, 32 Input device, 40 Control device, 80A-80D Servo motor, 100 Injection molding machine, AR1AL1,AR2,AL2 Actuator, Ax Rotating shaft, B1-B3 Heat sink, C1-C3 Cover, H1,H2,HD1,HL1,HL2,HR1,HR2,HU1 Heat pipe, Ht1-Ht3 Heater, R1 Cooling device, Sr1 to Sr4 temperature sensors.

Claims

1. An injection molding machine comprising: a cylinder for kneading an injection material supplied from the outside and supplying the kneaded injection material to the outside; a cover that covers the side of the cylinder and has a first region and a second region arranged at mutually different positions along a first direction which is the axial direction of the cylinder; a heater disposed between the cover and the cylinder for heating the cylinder; and a first heat pipe that thermally connects the first region and the second region of the cover, wherein the first heat pipe is provided on the side of the cover opposite to the side that covers the cylinder.

2. The injection molding machine according to claim 1, wherein the first region is closer to the center point of the cover than the second region in the first direction.

3. The injection molding machine according to claim 1 or claim 2, further comprising a nozzle for injecting a kneaded injection material into a mold, wherein the second region is a region closer to the nozzle than the first region.

4. The injection molding machine according to any one of claims 1 to 3, further comprising a cooling device for cooling the injection material supplied to the cylinder, wherein the second region is a region closer to the cooling device than the first region.

5. The injection molding machine according to any one of claims 1 to 4, further comprising: a first temperature sensor for detecting the temperature of the first region; a second temperature sensor for detecting the temperature of the second region; and a control device connected to the first temperature sensor and the second temperature sensor, wherein the control device acquires the temperature detected by the first temperature sensor, acquires the temperature detected by the second temperature sensor, and when the temperature detected by the first temperature sensor falls below a first target value, or when the temperature detected by the second temperature sensor exceeds a second target value, it performs a process to thermally isolate the first region and the second region, and the first target value is a temperature higher than the second target value.

6. The injection molding machine according to claim 5, wherein the control device informs the user that the first heat pipe should be removed during the shut-off process.

7. An injection molding machine according to any one of claims 1 to 4, further comprising: a first temperature sensor for detecting the temperature of the first region; a second temperature sensor for detecting the temperature of the second region; and a control device connected to the first temperature sensor and the second temperature sensor, wherein the control device acquires the temperature detected by the first temperature sensor, acquires the temperature detected by the second temperature sensor, performs a process to thermally isolate the first heat pipe and the first region when the temperature detected by the first temperature sensor exceeds a first overheating threshold, and performs a process to thermally isolate the first heat pipe and the second region when the temperature detected by the second temperature sensor exceeds a second overheating threshold.

8. The injection molding machine according to claim 2, wherein the cover further comprises a third region different from the first and second regions, the injection molding machine comprising a nozzle for injecting kneaded injection material into a mold, a cooling device for cooling the injection material supplied to the cylinder, and a second heat pipe for thermally connecting the third region and the first region, the second region being closer to the nozzle and the cooling device than the first region, the third region being closer to the nozzle than the first region, and the first region being closer to the center point than the third region.

9. The injection molding machine according to claim 8, further comprising: a first temperature sensor for detecting the temperature of the first region; a second temperature sensor for detecting the temperature of the second region; a third temperature sensor for detecting the temperature of the third region; and a control device connected to the first temperature sensor, the second temperature sensor, and the third temperature sensor, wherein the control device acquires the temperature detected by the first temperature sensor, acquires the temperature detected by the second temperature sensor, acquires the temperature detected by the third temperature sensor, performs a process to thermally isolate the first region and the second region and a process to thermally isolate the first region and the third region if the temperature detected by the first temperature sensor falls below a first target value; performs a process to thermally isolate the first region and the second region if the temperature detected by the second temperature sensor exceeds a second target value; and performs a process to thermally isolate the first region and the third region if the temperature detected by the third temperature sensor exceeds a third target value, and the first target value is a temperature higher than the second target value and the third target value.

10. An injection molding machine according to any one of claims 1 to 4, further comprising a first heat sink arranged in the first region and a second heat sink arranged in the second region, wherein the first heat pipe is thermally connected to the first region via the first heat sink and thermally connected to the second region via the second heat sink.

11. The injection molding machine according to claim 10, further comprising: a first temperature sensor for detecting the temperature of the first region; a second temperature sensor for detecting the temperature of the second region; a control device connected to the first temperature sensor and the second temperature sensor; and an actuator for changing the arrangement of at least one of the first heat sink and the second heat sink in the radial direction, wherein the first heat pipe is thermally connected to the first region via the first heat sink and thermally connected to the second region via the second heat sink; the control device acquires the temperature detected by the first temperature sensor and the temperature detected by the second temperature sensor; if the temperature detected by the first temperature sensor falls below a first target value, or if the temperature detected by the second temperature sensor exceeds a second target value which is less than or equal to the first target value, it performs a process to thermally isolate the first region and the second region; and in the isolation process, the actuator changes the arrangement of at least one of the first heat sink and the second heat sink.

12. The injection molding machine according to any one of claims 1 to 11, further comprising a third heat pipe that thermally connects the first region and the second region.

13. The injection molding machine according to any one of claims 1 to 12, wherein the thickness of the cover in the first region is thinner than the thickness of the cover in the second region.

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