Material preheating device and injection molding machine

Abstract

The present invention relates to a material preheating device and an injection molding machine. The material preheating device (21) is a device that preheats a molding material (Mm) and supplies the molding material (Mm) to an injection device (1), and includes a preheating screw (23) that conveys the molding material (Mm) toward a front side in a rotational axis direction; a preheating cylinder (22) in which the preheating screw (23) is disposed; and a hot air heating passage (25) that is partitioned on an outer peripheral side of the preheating screw (23) inside the preheating cylinder (22), through which the molding material (Mm) passes while being heated by hot air, a hot air inflow port (22a) of the hot air heating passage (25) is disposed on the front side in the rotational axis direction of the preheating cylinder (22), and a hot air outflow port (22b) of the hot air heating passage (25) is disposed on a rear side in the rotational axis direction of the preheating cylinder (22).

Description

Technical Field

[0001] This invention relates to a material preheating device for supplying molding material to an injection unit and an injection molding machine. Background Technology

[0002] As a technology related to supplying molding materials to an injection device or the like in injection molding, there are, for example, the technologies described in Patent Documents 1 and 2.

[0003] Patent Document 1 describes "a material supply device for an injection apparatus, which has a feed cylinder with a heating mechanism on its outer periphery, a feed screw inside, a motor that drives the feed screw to rotate is mounted at the end of the feed cylinder, a hopper is mounted on the rear of the feed cylinder, and a delivery cylinder is mounted on the lower front side of the feed cylinder. The material supply device is characterized in that notches are formed at predetermined intervals on the screw scraper of the feed screw, and a baffle is provided in the notch relative to the screw scraper in the longitudinal direction, so that the front of the feed screw is in a higher inclined position relative to the injection screw in the injection heating cylinder, and the feed cylinder is inclinedly disposed in the material supply section of the injection heating cylinder via the delivery cylinder."

[0004] Patent document 2 discloses "a material supply device for an injection apparatus, comprising a feed cylinder having a feed screw inside, a motor for the feed screw mounted at the rear end of the feed cylinder, a hopper on the upper side of the rear end of the feed cylinder, and a delivery pipe on the lower side of the front end of the feed cylinder. The delivery pipe is mounted and fixed on the injection apparatus to a supply section having a temperature-regulating flow path for the injection apparatus. The material supply device is characterized in that a temperature-regulating flow path is provided inside the feed cylinder, and the inflow side of the temperature-regulating flow path is connected to the outflow side of the temperature-regulating flow path of the supply section to form a series of temperature-regulating loops throughout the feed cylinder and the supply section."

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 6-79754

[0008] Patent Document 2: Japanese Patent Application Publication No. 2011-148218 Summary of the Invention

[0009] The technical problem to be solved by the invention

[0010] However, if the screw inside the cylinder of the injection unit is rotated at high speed, the plasticization of the molding material inside the cylinder is completed in a short time, thus shortening the injection molding cycle of the injection molding machine. This enables high-cycle molding.

[0011] On the other hand, when the screw rotates at high speed, the heating of the molding material inside the cylinder becomes insufficient, and the molded product may sometimes contain unmelted molding material. The inclusion of unmelted molding material in the molded product can lead to defects such as poor appearance and reduced strength.

[0012] To solve this problem, it is possible to preheat the molding material using a material preheating device that supplies the molding material to the injection unit.

[0013] In the cases of "feed cylinder with heating mechanism on the outer periphery" in Patent Document 1 and "temperature regulating flow path provided inside feed cylinder" in Patent Document 2, it takes time to heat the molding material to the required temperature.

[0014] The objective of this invention is to solve the problems described above, and to provide a material preheating device and an injection molding machine capable of effectively preheating the molding material supplied to the injection unit.

[0015] means for solving technical problems

[0016] A material preheating device capable of solving the above-mentioned problems is used to preheat molding materials and supply them to an injection device. The device comprises: a preheating screw that conveys the molding material towards the front in the direction of rotation; a preheating cylinder in which the preheating screw is disposed; and a hot air heating channel located on the outer periphery of the preheating screw within the preheating cylinder. The molding material passes through the channel while being heated by hot air. The hot air inlet of the hot air heating channel is located at the front in the direction of rotation of the preheating cylinder, and the hot air outlet of the hot air heating channel is located at the rear in the direction of rotation of the preheating cylinder.

[0017] Another material preheating device capable of solving the above-mentioned problem is a device for preheating molding material and supplying it to an injection unit. It comprises: a preheating screw for conveying the molding material; a preheating cylinder containing the preheating screw; and a hot air heating channel partitioned inside the preheating cylinder on the outer periphery of the preheating screw, through which the molding material passes while being heated by hot air. The preheating screw has an internal flow path for allowing hot air to flow inside, a hot air inlet for allowing hot air to flow into the internal flow path, and an outlet for discharging hot air from the internal flow path to the hot air heating channel on the outer periphery. The preheating cylinder has a hot air outlet for allowing hot air to flow out of the preheating cylinder. This material preheating device also includes a cylindrical channel partitioning component disposed inside the preheating cylinder in a manner that surrounds the preheating screw, allowing hot air to pass through.

[0018] Furthermore, the injection molding machine is equipped with a preheating device for any of the aforementioned materials.

[0019] The effects of the invention

[0020] According to the above-mentioned material preheating device, the molding material supplied to the injection unit can be effectively preheated. Attached Figure Description

[0021] Figure 1 This is a cross-sectional view taken along the rotation axis, showing a material preheating device and an injection device according to one embodiment of the present invention.

[0022] Figure 2 yes Figure 1 An enlarged cross-sectional view of the material preheating device.

[0023] Figure 3 This is a cross-sectional view showing a material preheating device according to another embodiment.

[0024] Figure 4 This is a cross-sectional view showing a material preheating device according to another embodiment.

[0025] Figure 5 This is a cross-sectional view showing a material preheating device according to another embodiment.

[0026] Figure 6 This is a cross-sectional view showing a material preheating device according to another embodiment.

[0027] Figure 7 This is a cross-sectional view showing a material preheating device according to another embodiment. Detailed Implementation

[0028] Hereinafter, embodiments of the invention will be described in detail with reference to the accompanying drawings.

[0029] One embodiment of the material preheating device of the present invention can be used for Figure 1 The injection device 1 illustrated in . Figure 1 The injection device 1 shown is an injection molding machine, for example, mounted on a sliding base SB of a moving device that moves the injection device 1 forward and backward, injecting molding material into a mold device (not shown). In this embodiment, the injection device 1 includes: a cylinder 11 that is supplied with molding material preheated by a material preheating device and melts the molding material inside; a screw 12 that is driven to rotate inside the cylinder 11 to plasticize the molding material; and a heater 13 disposed around the cylinder 11 and heats the molding material inside the cylinder 11. A detailed description of this injection device 1 will be given later.

[0030] (Material preheating device)

[0031] The material preheating device 21 is located along the axial direction of the screw 12 of the injection device 1. Figure 1The material preheating device 21 is installed on the rear end of the cylinder 11, opposite to the front end 14 of the injection molding material, in the left-right direction. More specifically, the material preheating device 21 is connected to a through-hole-shaped supply section 11a provided on the cylinder 11 of the injection device 1 in the circumferential direction at a portion of the rear end of the cylinder 11, and supplies molding material Mm, which is substantially spherical, cylindrical, or other shaped resin particles, to the supply section 11a.

[0032] like Figure 2 As shown, the material preheating device 21 of this embodiment includes a preheating cylinder 22 and a preheating screw 23. The preheating screw 23 is disposed inside the preheating cylinder 22 and faces the front side in the direction of the rotation axis (in Figure 2 The middle section (top right) conveys the forming material Mm.

[0033] The preheating screw 23 shown in the figure has a spiral scraper 23b arranged around a rotating shaft 23a, which rotates circumferentially and extends along the rotation axis. Driving force from a motor (not shown) or other drive source inside the motor housing 24 is transmitted to the preheating screw 23, causing it to rotate. Here, the direction along the rotation axis 23a of the preheating screw 23 of the material preheating device 21 is referred to as the rotation axis direction. In this example, the rotation axis direction of the preheating screw 23 is a different direction from the direction along the rotation axis of the screw 12 of the injection device 1, i.e., the axial direction.

[0034] Hot air generated by heating and pressing air or other gases is delivered to the outer periphery of the preheating screw 23 inside the preheating cylinder 22.

[0035] In the material preheating device 21 with this structure, the molding material Mm supplied to the preheating cylinder 22 is heated by hot air conveyed there, and is conveyed to the front side in the direction of rotation axis by the rotation of the preheating screw 23 between the scrapers 23b on the outer periphery of the preheating screw 23. The channel for the molding material Mm on the outer periphery of the preheating screw 23 inside the preheating cylinder 22 is equivalent to the hot air heating channel 25 through which the molding material Mm passes while being heated by hot air.

[0036] In this embodiment, as Figure 2 As shown by the arrow, a through-hole-shaped hot air inlet 22a is provided on the front side of the hot air heating channel 25 in the direction of rotation axis, allowing hot air to flow from the outside of the preheating cylinder 22 into the interior. On the other hand, on the rear side (in the direction of rotation axis of the preheating cylinder 22)... Figure 2 A through-hole-shaped opening 22b is provided on a portion of the circumferential wall (such as the lower left side), and the molding material Mm is supplied to the interior of the preheating cylinder 22 through the opening 22b.

[0037] At this time, hot air flows into the hot air heating channel 25 from the front hot air inlet 22a in the direction of rotation axis, heating the molding material Mm while flowing towards the rear side in the direction of rotation axis in the hot air heating channel 25, and flowing out from the hot air heating channel 25 through the rear opening 22b in the direction of rotation axis. Additionally, in Figure 2 In the embodiment shown, the opening 22b is used not only as a material supply port for supplying the molding material Mm into the preheating cylinder 22, but also as a hot air outlet for allowing hot air to flow out from the hot air heating channel 25, thus serving as both a material supply port and a hot air outlet.

[0038] By positioning the hot air inlet 22a at the front of the preheating cylinder 22 in the direction of rotation and the hot air outlet 22b (which serves as an opening) at the rear of the preheating cylinder 22 in the direction of rotation, hot air flows in the hot air heating channel 25 in the direction opposite to the conveying direction of the molding material Mm, i.e., the rearward direction of rotation. Each piece of molding material Mm is pressed against the scraper 23b by the rearward flow of hot air in the hot air heating channel 25, while being conveyed forward in the direction of rotation by the rotation of the preheating screw 23. As a result, the molding material Mm can be stably conveyed by the preheating screw 23, and the molding material Mm can be effectively heated within the preheating cylinder 22.

[0039] If the positions of the hot air inlet and outlet are reversed in the direction of rotation axis, then when the hot air flows forward in the same direction as the material being molded, the material is propelled forward by the hot air flow, causing unstable transport and resulting in the material passing through the hot air heating channel without a temperature rise. In this case, the preheating of the material becomes insufficient. This situation becomes particularly pronounced when the flow rate of hot air to the preheating cylinder is increased to rapidly raise the temperature of the material shortly before supplying it to the injection unit in order to speed up the molding cycle.

[0040] Furthermore, the hot air inlet 22a is positioned further forward in the direction of rotation than the hot air heating channel 25, and the opening 22b of the hot air outlet is positioned rearward in the direction of rotation of the hot air heating channel 25. When the hot air inlet 22a and the hot air outlet are configured in this way, the molding material Mm is exposed to hot air and heated in most of the hot air heating channel 25, thus the molding material Mm is efficiently heated in the hot air heating channel 25.

[0041] The material preheating device 21 is particularly useful for high-cycle molding, especially when using the injection device 1 to manufacture molded products such as caps for plastic bottles. It involves repeatedly performing a series of processes in a relatively short cycle until the molding material Mm is melted and injected into the mold device to obtain the molded product.

[0042] In high-cycle molding, the screw 12's rotational speed is increased within the cylinder 11 of the injection unit 1, rapidly completing the plasticization of the molding material Mm and shortening the time required for the molding material to accumulate at the front end 14 of the cylinder 11. At this time, the molding material is rapidly transferred to the front end 14 of the cylinder 11 without being adequately heated by the heaters 13 located around the cylinder 11. Even with increased heating temperatures of the heaters 13, the heating of the molding material Mm becomes insufficient due to its short residence time within the cylinder 11. Consequently, the molten molding material injected into the mold assembly from the front end 14 of the cylinder 11 sometimes contains unmelted material. The inclusion of unmelted material in the molded product can lead to defects such as poor appearance and reduced strength.

[0043] In contrast, when the molding material is preheated before being supplied to the injection unit 1 using the material preheating device 21 of this embodiment, the molding material Mm can be heated to a relatively high temperature by the material preheating device 21 before being supplied to the injection unit 1. As a result, even if the molding material is conveyed to the front end 14 of the cylinder 11 in a short time during high-cycle molding, the molding material will be sufficiently heated to become molten, which can effectively suppress the mixing of unmelted molding material into the molded product.

[0044] In the material preheating device 21, various devices or machines that generate hot air can be connected to the hot air inlet 22a of the preheating cylinder 22. For example, in Figure 2 Although not shown in the diagram, a jacket heater or other hot air heater, as well as a hot air compressor such as a fan or blower, can be installed outside the preheating cylinder 22. These hot air heaters and compressors constitute a hot air generator, where air or other gases compressed by the compressor are heated by the heaters to produce hot air. The hot air is delivered to the hot air inlet 22a by connecting the heaters and compressors. The material preheating device 21 can include such equipment or machinery as the hot air heaters and compressors, but equipment or machinery not included in the material preheating device 21 can also be used to generate hot air.

[0045] In addition, in this example, a material discharge port 22d for discharging material from the preheating cylinder 22 is formed on the peripheral wall portion on the front side in the direction of rotation axis of the preheating cylinder 22, on the lower side of the front end of the preheating screw 23.

[0046] More preferably, as shown in the illustrated embodiment, the hot air inlet 22a is located at a position, for example, on the front wall 22c of the preheating cylinder 22, in the direction of rotation of the preheating screw 23. At this time, the molding material Mm, which is conveyed to the vicinity of the front end of the preheating screw 23, is sufficiently heated while being pressed against the scraper 23b of the preheating screw 23 by hot air blown from the front of the hot air inlet 22a. Then, the molding material Mm is supplied to the injection unit 1 through the material outlet 22d and the connecting cylinder 22e on the lower side of the front end of the preheating screw 23. Furthermore, here, each piece of molding material Mm that has passed through the hot air heating channel 25 comes into contact with the hot air at the front end of the preheating screw 23, thereby suppressing deviations in the way it falls from the hot air heating channel 25 to the material outlet 22d, and ensuring a stable supply to the injection unit 1.

[0047] However, as shown in the figure, the preheating screw 23 and preheating cylinder 22, which extend parallel to each other, are preferably arranged in an inclined posture with the front portion positioned higher in the vertical direction than the rear portion in the direction of the rotation axis. As a result, the molding materials Mm conveyed within the preheating cylinder 22 to the front side in the direction of the rotation axis are conveyed in a state where they are biased towards the scraper 23b side of the preheating screw 23 by their own weight, thus stabilizing the conveying of the molding materials Mm based on the preheating screw 23. However, the preheating screw and preheating cylinder can also be arranged in a horizontal direction as described in the embodiments described later.

[0048] A supply cylinder 22f that guides the molding material Mm to the opening 22b can be installed at the opening 22b. Furthermore, a connecting cylinder 22e can be provided at the material outlet 22d, which is connected to the supply section 11a of the injection device 1 and guides the molding material Mm from the material outlet 22d to the supply section 11a. Both the supply cylinder 22f and the connecting cylinder 22e can be cylindrical or the like, and in this example, they extend along the vertical direction, but they can also be arranged in a direction inclined relative to the vertical direction.

[0049] Additionally, an insulation element (not shown) can be installed around the preheating cylinder 22.

[0050] exist Figure 3 The diagram shows another embodiment of a material preheating device 61. This material preheating device 61 has a structure that is substantially the same as the material preheating device 21 described above, except that it includes a hot air circulation path 66, a hot air heater 67a, and a hot air compressor 67b.

[0051] A hot air circulation path 66 located outside the preheating cylinder 62 circulates hot air that flows out of the preheating cylinder 62 through the opening 62b (which serves as the hot air outlet) and returns to the interior of the preheating cylinder 62 through the hot air inlet 62a. A hot air heater 67a and a hot air compressor 67b are disposed along the middle of the hot air circulation path 66. More specifically, the hot air circulation path 66 has an inflow path 66a connecting the hot air heater 67a and the hot air inlet 62a, and an outflow path 66b connecting the supply cylinder 62f and the hot air compressor 67b.

[0052] In the supply cylinder 62f, at a position upstream in the supply direction of the molding material Mm from the location where it connects to the outflow side flow path 66b, a hot air blocking member 62g, which is driven to open and close by a drive source (not shown), can be provided. During hot air circulation, when hot air flows from the opening 62b, which serves as both a material supply port and a hot air outlet, to the supply cylinder 62f, closing the hot air blocking member 62g can prevent it from flowing through the supply cylinder 62f and towards the outflow side flow path 66b. On the other hand, when the molding material Mm is supplied to the interior of the preheating cylinder 62, opening the hot air blocking member 62g allows the molding material Mm to enter the preheating cylinder 62 through the supply cylinder 62f from the opening 62b.

[0053] exist Figure 3 In the material preheating device 61, hot air flowing out of the opening 62b is drawn in by the hot air compressor 67b and sequentially passes through the supply cylinder 62f and the outflow side passage 66b of the hot air circulation path 66 to reach the hot air compressor 67b. Then, while being compressed by the hot air compressor 67b, the hot air is heated by the hot air heater 67a arranged parallel to the hot air compressor 67b, and then conveyed to the hot air inlet 62a through the inflow side passage 66a of the hot air circulation path 66. By circulating the hot air in the hot air circulation path 66 in this way, the energy consumption efficiency required for the generation of hot air can be improved.

[0054] Furthermore, a hot air compressor (not shown) that is different from the hot air compressor 67b shown in the figure can be installed midway through the outlet side flow path 66b of the hot air circulation flow path 66. In this case, the suction of hot air from the opening 62b and the compression of hot air to the hot air compressor 67b on the hot air inlet 62a side are promoted by this different hot air compressor.

[0055] exist Figure 4Another embodiment of the material preheating device 71 is shown. In this material preheating device 71, the hot air inlets 22a and 62a provided in the aforementioned material preheating devices 21 and 61 are not formed in the front wall 72c of the preheating cylinder 72. Instead, a hot air heater 77a is arranged inside the preheating cylinder 72, closer to the front wall 72c than the preheating screw 73 in the rotational axis direction. Furthermore, a material supply port 72b and a supply cylinder 72f are provided on the rear side of the preheating cylinder 72 in the rotational axis direction, and a hot air outlet 72g and an outlet cylinder 72h are provided on the rear side of the material supply port 72b. Although not shown in the figure, a hot air compressor connected to the hot air outlet 72g and the outlet cylinder 72h can be connected to the outside of the preheating cylinder 72.

[0056] exist Figure 4 In the material preheating device 71, gas heated by the hot air heater 77a is drawn into the hot air compressor connected to the hot air outlet 72g to become hot air, which flows in the hot air heating channel 75 toward the rear side in the direction of rotation axis. Therefore, the hot air heater 77a and the hot air compressor are used to generate hot air.

[0057] Here, the outlet of the hot air heating channel 75 at the front end of the preheating screw 73 functions as a hot air inlet located at the front side of the preheating cylinder 72 in the direction of rotation axis. Through the operation of the hot air compressor connected to the hot air outlet 72g, a negative pressure environment is sometimes created near the front end of the preheating screw 73. This stabilizes the delivery of the molding material Mm near this front end. Furthermore, at this time, through the operation of the hot air compressor on the hot air outlet 72g side, gas can be drawn from the injection device 1 side through the material discharge port 72d and the connecting cylinder portion 72e into the preheating cylinder 72. If necessary, a gas suction port may also be provided at the front end wall portion 72c, the connecting cylinder portion 72e, or other suitable locations on the front side of the preheating cylinder 72 in the direction of rotation axis.

[0058] When the hot air outlet 72g is positioned further rearward than the material supply port 72b in the direction of rotation as in this embodiment, most of the molding material Mm supplied from the material supply port 72b and conveyed to the front side in the direction of rotation can be heated by contact with the hot air.

[0059] exist Figure 4 The hot air generated in the material preheating device 71 shown can also be circulated and reused repeatedly in the hot air circulation path. Figure 5In another embodiment of the material preheating apparatus 81 shown, a hot air inlet 82a is formed in the front wall portion 82c of the preheating cylinder 82, and a hot air circulation path 86 is provided connecting the hot air outlet 82g to the hot air inlet 82a. A hot air compressor 87b is disposed in the middle of the hot air circulation path 86. The hot air circulation path 86 is composed of an outlet cylinder portion 82h that serves as an outlet-side flow path connecting the hot air outlet 82g and the hot air compressor 87b, and an inlet-side flow path 86a that connects the hot air compressor 87b and the hot air inlet 82a.

[0060] exist Figure 6 Another embodiment of the material preheating device 91 is shown. Figure 6 In the material preheating device 91, the rotating shaft 93a of the preheating screw 93 is, for example, composed of a cylindrical perforated metal plate, a mesh component, or a honeycomb structure component. The front end of the preheating screw 93 is open and has a cylindrical shape with multiple holes penetrating its peripheral wall. Thus, as Figure 6 As indicated by the arrow, the preheating screw 93 has an internal flow path 93c that allows hot air to flow inside the rotating shaft 93a, and a discharge hole that serves as a hole in the aforementioned peripheral wall, discharging hot air from the internal flow path 93c to the hot air heating channel 95 on the outer periphery. The discharge hole is set to a size that prevents the molding material Mm from passing through.

[0061] Most of the hot air from the hot air inlet 92a enters the internal flow path 93c of the preheating screw 93 and is discharged from the exhaust hole on the peripheral wall of the rotating shaft 93a into the hot air heating channel 95, where it heats the molding material Mm conveyed. Additionally, a portion of the hot air sometimes does not flow into the internal flow path 93c, but instead flows from the front end of the preheating screw 93 into the hot air heating channel 95.

[0062] and, Figure 6 The material preheating device 91 includes a cylindrical channel partition 98, which is arranged inside the preheating cylinder 92 around the preheating screw 93 and partitions a hot air heating channel 95. Multiple through holes are provided on the channel partition 98, preventing the molding material Mm from passing through, thereby allowing hot air to pass through. A hot air discharge path 98a is partitioned between the channel partition 98 and the inner surface of the preheating cylinder 92, conveying hot air from the hot air heating channel 95 to the hot air outlet 92g.

[0063] Hot air discharged from the aforementioned discharge hole of the rotating shaft 93a of the preheating screw 93 heats the molding material Mm in the hot air heating channel 95 and then flows through the channel partition 98 to the hot air discharge path 98a. In the hot air discharge path 98a, the hot air flows toward the rear side in the direction of the rotating shaft and reaches the hot air outlet 92g.

[0064] exist Figure 6 In this embodiment, the channel width of the hot air heating channel 95, which is divided between the outer peripheral surface of the preheating screw 93 (more specifically, the rotating shaft 93a) and the channel dividing member 98, is preferably set to be longer than or equal to the length of one molding material Mm but less than the length of two molding materials Mm. This prevents the molding materials Mm from overlapping radially in the hot air heating channel 95 during transport, thus making it easier to heat them with hot air flowing radially in the hot air heating channel 95.

[0065] Figure 6 Other structures of the material preheating device 91 shown are similar to Figure 4 The material preheating device 71 is essentially the same. However, the structure of the material preheating device 91 can be modified, such as... Figure 3 As shown, the hot air heater 97a is placed in the middle of the hot air circulation path 96 instead of inside the preheating cylinder 92, and / or the hot air outlet 92g and the material supply port 92b are combined into one and set as a dual-purpose opening.

[0066] exist Figure 7 Another embodiment of the material preheating apparatus 101 is shown. In this material preheating apparatus 101, the preheating cylinder 102 and the preheating screw 103 are arranged substantially parallel in the horizontal direction. Alternatively, in this embodiment, the preheating cylinder and the preheating screw may be arranged at an angle relative to the horizontal direction as in the embodiment described above.

[0067] In the material preheating device 101, the molding material Mm is drawn from the rear side (in the direction of rotation axis) of the preheating cylinder 102. Figure 7 The material is supplied to the interior through the material supply port 102b (located on the right side), and after being conveyed to the outer periphery of the preheating screw 103, it is supplied from the front side (located in the direction of the rotation axis) in the direction of the rotation axis. Figure 7 The material outlet 102d (left side) supplies the material to the injection device 1.

[0068] Regarding the preheating screw 103, the rotating shaft 103a is made of a perforated metal plate or the like, and has an internal flow path 103c for hot air to flow inside, a hot air inlet 102a for hot air to flow into the internal flow path 103c, and a discharge hole for hot air to be discharged from the internal flow path 103c to the outer periphery of the hot air heating channel 105. Furthermore, the preheating cylinder 102 is provided with a hot air outlet 102g from which hot air after heating the molding material Mm flows out.

[0069] Hot air flows from the hot air inlet 102a of the preheating screw 103 into the internal flow path 103c, and is discharged through the exhaust hole into the hot air heating channel 105 located on the outer periphery of the preheating screw 103, heating the molding material Mm. Afterward, the hot air flows out to the outside from the hot air outlet 102g of the preheating cylinder 102.

[0070] In this example, the hot air inlet 102a is located at the rear base end of the preheating screw 103 in the direction of rotation axis, but it can also be located at other parts, such as the front end in the direction of rotation axis. The end opposite to the side where the hot air inlet 102a is located, either the front end or the base end of the preheating screw 103, can be a closed structure without an opening. Here, the front end of the preheating screw 103 is sealed.

[0071] Inside the preheating cylinder 102, a cylindrical channel partition member 108 is provided to partition the hot air heating channel 105 around the preheating screw 103. In order to prevent the molding material Mm from overlapping in the radial direction in the hot air heating channel 105 and thus make the molding material Mm easy to heat, the channel width of the hot air heating channel 105 between the outer peripheral surface of the preheating screw 103 and the channel partition member 108 is preferably set to be more than the length of one molding material Mm and less than the length of two molding materials Mm.

[0072] By providing the channel partitioning component 108, a hot air discharge path 108a can be partitioned between the inner surface of the preheating cylinder 102 and the channel partitioning component 108 to transport hot air from the hot air heating channel 105 to the hot air outlet 102g.

[0073] exist Figure 7 In the case shown, the hot air outlet 102g is located on the rear side of the preheating screw 103 in the rotational axis direction on the peripheral wall of the preheating cylinder 102. At this time, the hot air from the hot air heating channel 105, after passing through the channel partition 108, flows in the hot air heating channel 105 towards the rear side in the rotational axis direction where the hot air outlet 102g is located, as indicated by the arrow in the figure. Alternatively, the hot air outlet may also be located on the front side in the rotational axis direction of the preheating screw.

[0074] Here, both the hot air inlet 102a and the hot air outlet 102g are located on the rear side of the preheating screw 103 in the direction of its rotation axis. Alternatively, when the hot air inlet is located on either the front or rear end of the preheating screw in the direction of its rotation axis, the hot air outlet is sometimes preferably located on the other end of that direction. In this case, the hot air inlet and the hot air outlet are located on opposite sides in the direction of rotation axis, i.e., one end and the other end. Therefore, the hot air flowing into the internal flow path from the hot air inlet can easily diffuse throughout the entire rotation axis direction of the hot air heating channel.

[0075] exist Figure 7 In the material preheating device 101, a hot air heater 107a and a hot air compressor 107b are disposed outside the preheating cylinder 102, and the hot air heater 107a and the hot air compressor 107b are connected to the hot air inlet 102a. Furthermore, the material preheating device 101 also includes a hot air circulation path 106, which includes an inflow side path 106a connecting the hot air inlet 102a and the hot air heater 107a, and an outflow side path 106b connecting the hot air outlet 102g and the hot air compressor 107b. Thus, after the hot air flows out from the hot air outlet 102g to the outside of the preheating cylinder 102, it is heated and compressed by the hot air heater 107a and the hot air compressor 107b, and then returns from the hot air inlet 102a to the inside of the preheating cylinder 102 for circulation. As needed, a hot air compressor (not shown) may be installed in the middle of the outflow side flow path 106b of the hot air circulation flow path 106.

[0076] Additionally, a sealing ring 109 can be installed at the connection between the inflow side flow path 106a and the preheating screw 103. This sealing ring 109 allows the preheating screw 103 to rotate relative to the inflow side flow path 106a and prevents hot air from flowing out. The preheating screw 103 is driven by a motor 111 via pulleys 110 of two different sizes, for example, at its base end located outside the preheating cylinder 102. Holes for the preheating screw 103 to pass through are provided on the front and rear walls of the preheating cylinder 102, and the preheating screw 103 is mounted in each hole via bearings.

[0077] The material preheating devices 21, 61, 71, 81, 91, and 101 described above can be equipped with a control unit that controls the operation of the material preheating devices 21, 61, 71, 81, 91, and 101. This control unit can be an inherent control unit of the material preheating devices 21, 61, 71, 81, 91, and 101, or it can be included in a control unit that controls the operation of the injection device 1 (described later) and, in turn, controls the operation of the injection molding machine equipped with the material preheating devices 21, 61, 71, 81, 91, and 101 and the injection device 1.

[0078] In particular, in material preheating devices 21, 61, 71, 81, and 91, it is sometimes preferable to have a control unit that increases or decreases the flow rate of hot air during the conveying of molding material in the hot air heating channel. Typically, it is possible to control the flow of hot air in the hot air heating channel to alternately and repeatedly stop the flow, so that the hot air flows intermittently.

[0079] When the hot air is kept at a constant flow rate, if the flow rate is increased to supply high-speed heating for the molding material Mm, the hot air encounters resistance as it travels backward along the rotation axis, making it difficult for the material Mm to move forward. Idling of the preheating screw can also lead to a situation where the molding material Mm cannot be delivered.

[0080] On the other hand, when the flow rate of the hot air is increased or decreased, the molding material Mm can be conveyed towards the front in the direction of the rotation axis at least during periods when the flow rate of the hot air is relatively low, and the flow rate can be increased during periods when the flow rate of the hot air is relatively high. Preferably, from this point of view, the flow rate of the hot air, the period of flow and flow cessation, the rotational speed of the preheating screw, or other conditions are set.

[0081] Furthermore, the control unit can increase or decrease the rotational speed of the preheating screw for purposes such as adjusting the conveying speed of the molding material Mm. It can also establish a correlation between the increase or decrease in the hot air flow rate and the increase or decrease in the rotational speed of the preheating screw. For example, it is possible to increase the rotational speed of the preheating screw when the hot air flow rate is decreased, and decrease the rotational speed of the preheating screw when the hot air flow rate is increased.

[0082] (Injection device)

[0083] like Figure 1 As illustrated, the injection device 1, which can utilize the material preheating device 21 as described above, mainly comprises: a cylinder 11 that melts the molding material supplied from the material preheating device 21 inside; a screw 12 that is driven to rotate inside the cylinder 11 to plasticize the molding material; and a rear side disposed in the axial direction of the screw 12. Figure 1 The metering motor 31 (on the right side) and the injection motor 41 disposed further rearward on the metering motor 31.

[0084] A heater 13 is arranged around the cylinder body 11 to heat the molding material inside the cylinder body 11. The front end side of the cylinder body 11 in the axial direction ( Figure 1 The cylinder 11 has a front end portion 14 with decreasing inner and outer diameters on its left side, and a heater 13 is also arranged around the front end portion 14. Furthermore, the cylinder 11 has a through-hole-shaped supply section 11a on its rear end side in the axial direction, and the aforementioned material preheating device 21 is installed in the through-hole-shaped supply section 11a.

[0085] The metering motor 31 and the injection motor 41 are respectively fixed to the rear side of the respective axis of two motor support plates 32 and 42, which are arranged vertically and spaced apart on the sliding base SB. The screw 12 is driven to rotate by the metering motor 31 and to move forward and backward by the injection motor 41. The two motor support plates 32 and 42 are connected to each other by rods 51 at multiple locations on the upper and lower sides of the metering motor 31.

[0086] The metering motor 31 mainly includes a rotor 33, a stator 34 disposed around the rotor 33, and a stator frame 35 surrounding the rotor 33 and the stator 34, with the stator 34 disposed on its inner surface. The rotor 33 of the metering motor 31 is supported at each end in the axial direction by bearings 33a on the inner side of the stator frame 35. Furthermore, the rotor 33 is splined around a metering spline shaft 36, which is connected to a screw mounting portion 37 on which a screw 12 is mounted. Additionally, one or more keys 36a corresponding to keyways disposed on the inner circumferential surface of the rotor 33 are formed at the rear end of the outer circumferential surface of the metering spline shaft 36 in the axial direction. Thus, rotational driving force can be transmitted from the metering motor 31 to the screw 12, causing the screw 12 to rotate.

[0087] The injection motor 41 mainly comprises: a rotor 43, a stator 44 disposed around the rotor 43, and a stator frame 45 arranged around the rotor 43 and the stator 44, with the stator 44 having an inner surface. Each end of the rotor 43 in its axial direction is supported by bearings 43a on the inner side of the stator frame 45. The rotor 43 of the injection motor 41 is connected to a drive shaft. More specifically, the drive shaft comprises: an injection spline shaft 46 splined through a slot 43b provided on the inner circumference of the cylindrical rotor 43; a lead screw shaft 48 connected to the injection spline shaft 46; and a rotating shaft portion 50 rotatably mounted on the inner side of the metering spline shaft 46 via bearings 49. A lead screw nut 47 screwed to the lead screw shaft 48 is mounted on a motor support plate 42 via a pressure detector 38 described later. Through this structure, the rotational driving force generated by the injection motor 41 is converted into a linear driving force in the axial direction of the screw 12 and transmitted to the screw 12.

[0088] Additionally, a pressure detector 38 is disposed between the stator frame 45 of the injection motor 41 and the motor support plate 42. This pressure detector 38 is mounted on both the motor support plate 42 and the lead screw nut 47, and detects the load acting on it along the transmission path of the driving force from the injection motor 41 to the screw 12. A cylindrical portion 39 is sandwiched between the pressure detector 38 and the stator frame 45. Furthermore, an encoder 45a is provided on the rear end face of the stator frame 45 of the injection motor 41. This encoder 45a is connected to the rotor 43 via a shaft portion 45b to detect the rotation of the rotor 43.

[0089] An example of the molding process based on an injection molding machine equipped with such an injection device 1 will be described. In the latter half of the previous molding process, with a predetermined amount of molding material already metered and placed inside the cylinder 11, a mold closing process is performed, in which the mold device (not shown) is closed to set the mold to a closed state. Next, a filling process is performed in sequence, in which the molding material is injected into the mold device by the advance of the screw 12 to fill the cavity in the mold device, and a pressure holding process is performed, in which the screw 12 is further advanced to maintain the molding material located inside the front end 14 of the cylinder 11 at a predetermined pressure.

[0090] Furthermore, a cooling process is then performed to cool and solidify the molding material filled in the mold device to obtain a molded article. At this time, a metering process is performed as follows: while heating based on the heater 13, the molding material supplied from the material preheating device 21 into the cylinder 11 is fed toward the front end 14 of the cylinder 11 by the rotation of the screw 12 and melted, thereby placing a predetermined amount of molding material at the front end 14.

[0091] In this metering process, in this embodiment, the molding material supplied to the cylinder 11 has been heated to an appropriate temperature by the material preheating device 21. Therefore, even if the screw 12 rotates at high speed and the molding material is conveyed to the front end 14 of the cylinder 11 in a short time, the molding material can be fully plasticized. As a result, the metering time is shortened, and the molding cycle can be shortened.

[0092] In addition, there is a subsequent removal process where the molded part is removed from the mold device by means of an ejector device or similar means, after the mold device is opened and the mold is set to the open state.

[0093] Symbol Explanation

[0094] 1-Injection device; 11-Cylinder body; 11a-Supply section; 12-Screw; 13-Heater; 14-Front end; 21, 61, 71, 81, 91, 101-Material preheating device; 22, 62, 72, 82, 92, 102-Preheating cylinder; 22a, 62a, 82a, 92a, 102a-Hot air inlet; 22b, 62b-Opening (material supply port, hot air outlet); 72b, 82b, 92b, 102b-Material supply port; 22c, 62c, 72c, 82c, 92c-Front end wall; 22d, 62d, 72d, 82d, 9 2d, 102d - Material discharge port; 22e, 62e, 72e, 82e, 92e, 102e - Connecting cylinder section; 22f, 62f, 72f, 82f, 92f, 102f - Supply cylinder section; 62g - Hot air blocking component; 72g, 82g, 92g, 102g - Hot air outlet; 72h, 82h - Outflow cylinder section; 23, 63, 73, 83, 93, 103 - Preheating screw; 23a, 63a, 73a, 83a, 93a, 103a - Rotating shaft; 23b, 63b, 73b, 83b, 93b, 103b - Scraper; 93c, 10 3c - Internal flow path; 24, 64, 74, 84, 94 - Motor housing; 25, 65, 75, 85, 95, 105 - Hot air heating channel; 66, 86, 96, 106 - Hot air circulation flow path; 66a, 86a, 96a, 106a - Inflow side flow path; 66b, 106b - Outflow side flow path; 67a, 77a, 87a, 97a, 107a - Hot air heater; 67b, 87b, 97b, 107b - Hot air compressor; 98, 108 - Channel partition components; 98a, 108a - Hot air discharge flow path; 110 - Pulley; 111 - Motor; 3 1-Metering motor, 32-Motor support plate, 33-Rotor, 33a-Bearing, 34-Stator, 35-Stator frame, 36-Metering spline shaft, 36a-Key, 37-Screw mounting part, 38-Pressure detector, 39-Cylindrical part, 41-Injection motor, 42-Motor support plate, 43-Rotor, 43a-Bearing, 43b-Slot, 44-Stator, 45-Stator frame, 45a-Encoder, 45b-Shaft, 46-Injection spline shaft, 47-Lead screw nut, 48-Lead screw shaft, 49-Bearing, 50-Rotating shaft, 51-Rod, Mm-Molding material, SB-Sliding base.

Claims

1. A material preheating apparatus for preheating a molding material and supplying the molding material to an injection device, the material preheating apparatus comprising: The preheating screw conveys the molding material. The preheating cylinder is equipped with a preheating screw inside; The hot air heating channel is divided inside the preheating cylinder on the outer periphery of the preheating screw, through which the molding material is heated by hot air while passing; and The material discharge port discharges the molding material in a direction different from the conveying direction of the preheating screw. The preheating screw has an internal flow path for hot air to flow inside, a hot air inlet for hot air to flow into the internal flow path, and an outlet for hot air to be discharged from the internal flow path to the hot air heating channel on the outer periphery. The preheating cylinder has a hot air outlet that allows hot air to flow out of the preheating cylinder. The material preheating device includes a cylindrical channel partition component, which is arranged inside the preheating cylinder to surround the preheating screw, through which hot air passes. The width of the hot air heating channel, which is divided between the outer peripheral surface of the preheating screw and the channel dividing component, is greater than or less than the length of one molding material and less than the length of two molding materials.

2. The material preheating device according to claim 1, wherein, It has a hot air discharge path, which is divided between the inner surface of the preheating cylinder and the channel dividing component, and delivers hot air from the hot air heating channel to the hot air outlet.

3. The material preheating device according to claim 1 or 2, wherein, The hot air inlet is located at one end of the preheating screw along its rotation axis, and the hot air outlet is located at the other end of the preheating screw along its rotation axis.

4. The material preheating device according to claim 1 or 2, wherein, It includes a hot air heater and a hot air compressor, which are disposed outside the preheating cylinder and connected to the hot air inlet for generating hot air.

5. The material preheating device according to claim 1 or 2, wherein, It has a hot air circulation path, which allows hot air flowing out of the hot air outlet to exit to the outside of the preheating cylinder to return to the inside of the preheating cylinder through the hot air inlet for circulation.

6. An injection molding machine comprising a material preheating device according to any one of claims 1 to 5.

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