Method for starting a resin pellet manufacturing apparatus, method for manufacturing resin pellets, and resin pellet manufacturing apparatus
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- KOBE STEEL LTD
- Filing Date
- 2023-10-10
- Publication Date
- 2026-07-07
Smart Images
Figure 0007886305000001 
Figure 0007886305000002 
Figure 0007886305000003
Abstract
Description
Technical Field
[0001] The present invention relates to a method for starting a resin pellet manufacturing apparatus, a method for manufacturing resin pellets, and a resin pellet manufacturing apparatus.
Background Art
[0002] Conventionally, a pellet manufacturing apparatus for manufacturing resin pellets has been known. For example, Patent Document 1 discloses a granulating apparatus (pellet manufacturing apparatus) including a PCW (PELLET COOLING / TRANSPORT WATER) tank (water tank), a forward path, a circulation tank (water chamber), and a return path. In this technology, a circulation flow path is formed in which pellet cooling and transport water (pellet cooling water) flowing from the PCW tank to the circulation tank through the forward path flows from the circulation tank to the PCW tank through the return path. The return path connects the circulation tank and the PCW via above the circulation tank. The granulating apparatus further includes a die (die plate) having a die hole (die hole) facing the water chamber, and a cutter blade (cutter) disposed in the circulation tank for cutting the molten resin discharged from the die hole to manufacture resin pellets.
[0003] Before starting the production of resin pellets, this granulating apparatus flows a heat medium inside the die to heat the die. In this state, after circulating the pellet cooling and transport water in the circulation flow path, the circulation is stopped, the pellet cooling and transport water is discharged from the circulation tank, and a predetermined amount of pellet cooling and transport water is stored in the circulation tank. Then, heat exchange is performed between the pellet cooling and transport water stored in the circulation tank and the die to warm the pellet cooling and transport water.
Prior Art Documents
Patent Documents
[0004]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0005] The technology described in Patent Document 1 is not economical because it discharges the pellet cooling water from the circulation box to the outside of the circulation channel in order to lower the water level of the pellet cooling water. Specifically, in the above granulation apparatus, the circulation box is filled with pellet cooling water by stopping the circulation after it has been circulated, but at the time the circulation is stopped, the pellet cooling water has accumulated up to the upper end of the forward path, resulting in a high water level. Due to this high water level, excessive water pressure acts inside the circulation box, which can push back the resin present inside the die holes, potentially causing the pellet cooling water to enter the die holes. For this reason, the above granulation apparatus lowers the water level of the pellet cooling water by discharging it from the circulation box to the outside of the circulation channel. However, since pellet cooling water discharged to the outside of the circulation channel is generally discarded, discharging the pellet cooling water to the outside of the circulation channel in order to lower the water level leads to an increase in waste and is not economical.
[0006] This invention has been made in view of the above problems, and aims to reduce the amount of pellet cooling water that is wasted. [Means for solving the problem]
[0007] A method for starting a resin pellet manufacturing apparatus according to one aspect of the present invention comprises a circulation channel having a forward path for pellet cooling water discharged from a water tank by a pump to a water chamber and a return path for the pellet cooling water to return from the water chamber to the water tank via the upper part of the water chamber; a die plate having a plurality of die holes and positioned facing the water chamber; and a cutter positioned in the water chamber for cutting molten resin discharged from the plurality of die holes to granulate resin pellets, wherein the method for starting a resin pellet manufacturing apparatus transports the granulated resin pellets from the water chamber while cooling them with the pellet cooling water flowing through the circulation channel, and further comprises a water supply step in which, before starting the production of the resin pellets, the pellet cooling water stored in the water tank is supplied to the water chamber by the pump to fill the water chamber, and then the water supply of the pellet cooling water is stopped so that the water level of the pellet cooling water reaches a target water level set to be lower than the upper end of the return path.
[0008] In this configuration, the supply of pellet cooling water is stopped in the water supply process when the water level reaches the target level. Therefore, compared to the case where the water level of the pellet cooling water is set to the target level by circulating the pellet cooling water in the circulation channel and then discharging it, the amount of pellet cooling water that is wasted can be reduced.
[0009] In the above configuration, during the water supply process, a portion of the pellet cooling water discharged from the water tank by the pump may be returned to the water tank while water is supplied to the water chamber.
[0010] In this configuration, during the water supply process, some of the pellet cooling water is returned to the water tank while the remaining pellet cooling water is supplied to the water chamber. This reduces the flow rate of pellet cooling water into the water chamber compared to the case where some of the pellet cooling water is not returned to the water tank. As a result, the rate at which the pellet cooling water accumulates in the water chamber becomes relatively slow, making it easier to stop the water supply when the water level of the pellet cooling water reaches the target level.
[0011] In the above configuration, the water supply step may involve supplying the pellet cooling water to the water chamber through an auxiliary channel having an inner diameter smaller than the inner diameter of the forward path and arranged in parallel with at least a portion of the forward path.
[0012] With this configuration, in the water supply process, pellet cooling water is supplied to the water chamber through an auxiliary channel having a smaller inner diameter than the inner diameter of the supply channel. Compared to the case where water is supplied solely through the supply channel, the flow rate of pellet cooling water flowing into the water chamber can be reduced. As a result, the rate at which pellet cooling water accumulates in the water chamber becomes relatively slower, making it easier to stop the water supply when the water level of the pellet cooling water reaches the target level.
[0013] In the above configuration, the system further includes a rotation step, which is performed at least after the water supply step, in which the cutter is rotated while in contact with the die plate, and in the rotation step, the cutter is rotated while the pellet cooling water is supplied to the water chamber through the auxiliary channel.
[0014] During the rotation process, the frictional heat generated by the rotation of the cutter in contact with the die plate can cause the die plate temperature to rise excessively. However, with the above configuration, pellet cooling water is supplied from the auxiliary channel, allowing the die plate temperature to be controlled.
[0015] In the above configuration, during the rotation process, the pellet cooling water may be supplied to the water chamber while the pellet cooling water is discharged through a discharge channel that connects the water chamber to the outside of the water chamber.
[0016] With this configuration, the pellet cooling water in the water chamber can be replaced while being agitated by a cutter rotating within the water chamber. This suppresses localized boiling within the water chamber. As a result, the surface temperature of the die plate facing the water chamber is kept uniform.
[0017] Furthermore, with the above configuration, the resin that drips out from the die holes of the die plate and is scooped up by the cutter can be removed to the outside of the water chamber along with the pellet cooling water discharged from the water chamber.
[0018] In the above configuration, during the rotation process, the amount of pellet cooling water discharged through the discharge channel may be adjusted so that the water level of the pellet cooling water in the water chamber is maintained at the target water level.
[0019] This configuration makes it possible to prevent the water level of the pellet cooling water from being located at a level that deviates from the target water level during the rotation process.
[0020] In the above configuration, during the water supply process, a flow path switching mechanism, which is located downstream of the pump in the forward path and can switch between a first state in which both the water chamber and the water tank are destinations for the pellet cooling water, a second state in which one of the water chamber and the water tank is the destination for the pellet cooling water, and a third state in which the other of the water chamber and the water tank is the destination for the pellet cooling water, may be set to the first state to supply the pellet cooling water to the water chamber.
[0021] In this configuration, during the water supply process, the flow path switching mechanism is in the first state, so that some of the pellet cooling water returns to the water tank while the remaining pellet cooling water is supplied to the water chamber. This reduces the flow rate of pellet cooling water flowing into the water chamber compared to the case where some of the pellet cooling water is not returned to the water tank. Furthermore, when it becomes necessary to circulate the pellet cooling water, the flow path switching mechanism can be switched to the second state to set the destination of the pellet cooling water to the water chamber. Moreover, when it is necessary to switch the destination of the pellet cooling water to the water tank, the flow path switching mechanism can be set to the third state. In this way, by providing a flow path switching mechanism, it becomes easy to switch the destination of the pellet cooling water according to the purpose.
[0022] In the above configuration, the return path includes an upper connection flow path that is connected to the upper part of the water chamber and extends upward, and an inclined flow path that includes a lower end connected to the upper connection flow path and is inclined upward from the lower end to the upper end of the return path. In the water supply process, the target water level may be set at a position lower than the lower end.
[0023] According to this configuration, since the target water level is set at a position lower than the lower end of the inclined flow path, the water pressure acting in the water chamber can be suppressed as compared with the case where the target water level is set at a position higher than the lower end. As a result, it is possible to efficiently suppress the resin existing inside the plurality of die holes of the die plate from being pushed back and the pellet cooling water from entering the inside of the plurality of die holes.
[0024] Furthermore, since it is not necessary to discharge the pellet cooling water in the inclined flow path, the amount of waste of the pellet cooling water can be reduced.
[0025] A method for manufacturing resin pellets according to another aspect of the present invention is a method for manufacturing resin pellets in a resin pellet manufacturing apparatus including a circulation flow path having an upstream path through which pellet cooling water discharged from a water tank by a pump reaches a water chamber and a downstream path through which the pellet cooling water reaches the water tank from the water chamber via above the water chamber. Before starting the production of the resin pellets, a water supply step of supplying the pellet cooling water stored in the water tank to the water chamber, a rotation step of rotating a cutter disposed in the water chamber in contact with a die plate having a plurality of die holes facing the water chamber, a heating step of heating the die plate to melt the resin present inside the plurality of die holes, a material supply step of supplying a resin material to the die plate from upstream, a production step of cutting the molten resin discharged from the plurality of die holes of the die plate with the cutter in the water chamber to granulate the resin pellets and conveying the resin pellets from the water chamber while cooling the resin pellets with the pellet cooling water to manufacture the resin pellets, and an operation stop step of stopping the heating of the die plate while molten resin is present inside the plurality of die holes and stopping the operation of the resin pellet manufacturing apparatus. In the water supply step, after filling the water chamber with the pellet cooling water, the supply of the pellet cooling water is stopped so that the water surface of the pellet cooling water becomes a target water level set at a position lower than the upper end of the downstream path.
[0026] According to this configuration, in the water supply step, the supply of the pellet cooling water is stopped corresponding to the target water level. Therefore, compared with the case where the water surface of the pellet cooling water is set to the target water level by discharging the pellet cooling water after circulating the pellet cooling water in the circulation flow path, the amount of waste of the pellet cooling water can be reduced.
[0027] In the above configuration, in the rotation step, the water surface of the pellet cooling water may be maintained at the target water level, and the rotational speed of the cutter may be set to be lower than the rotational speed of the cutter during the production step.
[0028] When the pellet cooling water level is maintained at the target level, the water pressure acting within the water chamber is suppressed, but cavitation may occur as the cutter rotates. In contrast, with this configuration, the cutter rotation speed is set lower than the cutter rotation speed during the manufacturing process, thus suppressing cavitation compared to when the cutter rotation speed is set to the same as or higher than the cutter rotation speed during the manufacturing process.
[0029] A resin pellet manufacturing apparatus according to another aspect of the present invention comprises: a water tank for storing pellet cooling water; a water chamber for receiving the pellet cooling water from the water tank; a forward path connecting the water tank and the water chamber; a return path connecting the water chamber and the water tank via the upper part of the water chamber; a water supply unit for supplying the pellet cooling water from the water tank to the water chamber through the forward path; a die plate having a plurality of die holes facing the inside of the water chamber; and a cutter disposed in the water chamber for granulating resin pellets by cutting molten resin discharged from the plurality of die holes of the die plate within the water chamber, wherein the water supply unit stops supplying the pellet cooling water when the water level of the pellet cooling water reaches a target water level set to be lower than the upper end of the return path before the start of resin pellet manufacturing.
[0030] With this configuration, the pump stops discharging the pellet cooling water in response to the target water level. Compared to the case where the pellet cooling water level is set to the target water level by circulating the pellet cooling water in the circulation channel and then discharging it, the amount of pellet cooling water wasted can be reduced.
[0031] In the above configuration, the device further comprises: a first auxiliary channel having an inner diameter smaller than the inner diameter of the forward channel and supplying the pellet cooling water flowing out of the water tank to the water chamber; a return channel branching off from the forward channel and connecting the forward channel and the water tank; and a channel switching mechanism for switching the destination of the pellet cooling water. The first auxiliary channel may start from the region of the forward channel between the water tank and the channel switching mechanism, or a predetermined region of the return channel, and end in the region of the forward channel between the channel switching mechanism and the water chamber, or the water chamber, and may be opened when supplying the pellet cooling water to the water chamber before the start of resin pellet production.
[0032] This configuration allows water to be supplied to the water chamber through a first auxiliary channel having a smaller inner diameter than the outer channel. This reduces the flow rate of pellet cooling water into the water chamber compared to supplying water exclusively through the outer channel. As a result, the rate at which pellet cooling water accumulates in the water chamber becomes relatively slower, making it easier to stop the water supply when the water level reaches the target level. Consequently, the amount of pellet cooling water discarded can be reduced.
[0033] In the above configuration, a second auxiliary flow path may be further provided, having an inner diameter smaller than the inner diameter of the forward flow path and different from the first auxiliary flow path, wherein the second auxiliary flow path may start from the region of the forward flow path between the water tank and the flow path switching mechanism, or from a predetermined region of the return flow path, and end at the tip of the rotating shaft of the cutter, and communicate with the water chamber.
[0034] Normally, resin pellets cut and granulated by the cutter are transported to the outside of the water chamber by pellet cooling water. However, these resin pellets may accumulate near the tip of the cutter's rotation axis due to the water flow generated in the water chamber by the cutter's rotation. In contrast, with this configuration, since the tip of the cutter's rotation axis is set at the end of the second auxiliary flow path, pellet cooling water can be discharged from this tip to move the resin pellets accumulated around it. This makes it possible to transport the accumulated resin pellets as usual.
[0035] In the above configuration, a discharge channel may be further provided for discharging the pellet cooling water from the water chamber to the outside of the water chamber. [Effects of the Invention]
[0036] This configuration makes it possible to reduce the amount of pellet cooling water that is wasted. [Brief explanation of the drawing]
[0037] [Figure 1] This figure shows a schematic configuration of a pellet manufacturing apparatus according to one embodiment of the present invention. [Figure 2] Figure 1 is an enlarged cross-sectional view of the die plate of the pellet manufacturing apparatus. [Figure 3] This is a flowchart showing a method for manufacturing resin pellets according to one embodiment of the present invention. [Figure 4] This figure shows the flow of pellet cooling water when supplying water using the water storage channel provided in the pellet manufacturing apparatus shown in Figure 1. [Figure 5] This figure shows the flow of pellet cooling water when water is supplied using the axial passage channel of the pellet manufacturing apparatus shown in Figure 1. [Figure 6] This figure shows a schematic configuration of a flow path switching mechanism according to a first modified embodiment of the present invention. [Figure 7] This figure shows a schematic configuration of a pellet manufacturing apparatus according to a second modified embodiment of the present invention. [Figure 8]Figure 7 is a schematic diagram showing the configuration of the flow path switching mechanism in the pellet manufacturing apparatus, where (a) shows the flow path switching mechanism in the first state, (b) shows the flow path switching mechanism in the second state, and (c) shows the flow path switching mechanism in the third state. [Modes for carrying out the invention]
[0038] <Configuration of pellet manufacturing equipment> Hereinafter, a pellet manufacturing apparatus 1 (resin pellet manufacturing apparatus) according to one embodiment of the present invention will be described with reference to the drawings. Figure 1 is a diagram showing the schematic configuration of the pellet manufacturing apparatus 1 according to one embodiment of the present invention. Figure 2 is an enlarged cross-sectional view of the die plate 20, which will be described later. In the following, the +Y direction in each figure will be referred to as the upward direction, and the -Y direction will be referred to as the downward direction.
[0039] The pellet manufacturing apparatus 1 manufactures resin pellets. As shown in Figure 1, the pellet manufacturing apparatus 1 comprises a feeder 2, a mixer 4, a gear pump 6, a screen changer 8, a die holder 10, a die plate 20, a water chamber 30, a pelletizer 40, a water tank 50, a pump 60, a cooling device 70, a flow path switching mechanism 80, a dryer 90, a forward flow path 100, a return flow path 110, a water storage flow path 120 (first auxiliary flow path), an axial passage flow path 130 (second auxiliary flow path), a discharge flow path 140, and a return flow path 200.
[0040] Feeder 2 supplies resin materials such as polypropylene and polyethylene to mixer 4.
[0041] Mixer 4 is driven by a motor (not shown) to knead the resin material supplied from feeder 2. Mixer 4 supplies the kneaded resin material to a diverter valve (not shown). The diverter valve switches the destination of the resin kneaded by mixer 4. Specifically, the diverter valve switches the destination of the resin to either the gear pump 6 or to an external location outside the pellet manufacturing device 1.
[0042] The gear pump 6 applies pressure to the resin material supplied from the diverter valve, sending the resin material toward the die plate 20. The resin, pressurized by the gear pump 6, passes through the screen changer 8 and the die holder 10 to reach the die plate 20.
[0043] The screen changer 8 removes foreign matter contained in the resin supplied from the gear pump 6. The resin that has passed through the screen changer 8 proceeds to the die plate 20 via the die holder 10.
[0044] The die holder 10 holds the die plate 20. Inside the die holder 10, a die holder passage (not shown) is formed through which the resin material that has passed through the screen changer 8 flows.
[0045] The die plate 20 is held in the die holder 10 and is positioned facing the water chamber 30. The die plate 20 has a plurality of die holes 20H (Figure 2) facing the water chamber 30, a heat transfer medium channel 21 (Figure 2), and a temperature transmitter 22 (Figure 1). The plurality of die holes 20H connect the die holder passage and the inside of the water chamber 30, guiding the resin material that has passed through the die holder passage into the inside of the water chamber 30. That is, the resin material that has passed through the die holder passage and reached the plurality of die holes 20H is discharged into the water chamber 30 through the plurality of die holes 20H. Each die hole 20H is formed in a small diameter shape, so that the resin material discharged from each die hole 20H is formed into an elongated shape. The heat transfer medium channel 21 is a channel through which a heat transfer medium that heats the die plate 20 flows. For example, steam or hot oil can be used as the heat transfer medium. The temperature transmitter 22 measures the temperature of the die plate 20. The temperature measured by the temperature transmitter 22 is transmitted to a control device (not shown) or the like.
[0046] Returning to Figure 1, the water chamber 30 is a container that receives pellet cooling transport water PCW (pellet cooling water) from the water tank 50 and stores the pellet cooling transport water PCW. The pellet cooling transport water PCW is a liquid that cools the resin pellets produced in the pellet manufacturing apparatus 1 while transporting the resin pellets.
[0047] The pelletizer 40 cuts the resin material extruded from the die plate 20 to form resin pellets. In detail, the pelletizer 40 includes a pelletizer motor 42, a rotating shaft 44, a cutter holder 46, and a plurality of cutters 48.
[0048] The pelletizer motor 42 is the drive source that rotates the multiple cutters 48.
[0049] The rotating shaft 44 has one end connected to the pelletizer motor 42 and the other end 47 (tip) located inside the water chamber 30 to which the cutter holder 46 is attached, and transmits the rotational force generated by the pelletizer motor 42 to the cutter holder 46. The rotating shaft 44 is formed in a cylindrical shape, and the space radially inside the rotating shaft 44 communicates with the inside of the water chamber 30. The rotating shaft 44 is also connected to a hydraulic unit or pneumatic unit (not shown) and can move forward and backward in the axial direction. In other words, the rotating shaft 44 can move the cutter holder 46 closer to and further away from the die plate 20.
[0050] The cutter holder 46 is attached to the rotating shaft 44, surrounding the other end 47 of the rotating shaft 44 in the circumferential direction. Multiple cutters 48 are fixed to the cutter holder 46. In detail, the multiple cutters 48 are arranged at equal or unequal intervals along the circumferential direction on the radial end face of the cutter holder 46.
[0051] Multiple cutters 48 extend along the radial direction, starting from the radial end face of the cutter holder 46. As the rotating shaft 44 advances axially, the multiple cutters 48 come into contact with the surface of the die plate 20. As the pelletizer motor 42 drives the cutter holder 46 to rotate, the multiple cutters 48 rotate along the circumferential direction of the cutter holder 46 with the rotating shaft 44 as the center of rotation.
[0052] The water tank 50 is a container that stores pellet cooling transport water PCW. The water tank 50 has a heating device 52. The heating device 52 heats the pellet cooling transport water PCW stored in the water tank 50.
[0053] Pump 60 discharges the pellet cooling transport water PCW stored in the water tank 50 toward the water chamber 30. In this embodiment, pump 60 does not have a function to adjust the flow rate of the pellet cooling transport water PCW, but in other embodiments, pump 60 may have such a function.
[0054] The cooling device 70 is located downstream of the pump 60 and cools the pellet cooling transport water PCW that flows from the water tank 50 toward the water chamber 30.
[0055] The flow path switching mechanism 80 is a three-way valve located downstream of the pump 60 in the forward path 100 and has a first port connected to the first forward path portion 100a (described later), a second port connected to the second forward path portion 100b (described later), and a third port connected to the return flow path 110. The flow path switching mechanism 80 according to this embodiment can switch between a first state and a second state. The first state is a state in which the first forward path portion 100a and the second forward path portion 100b are connected, and the connection between the first forward path portion 100a and the return flow path 110 is prevented. The first state can be rephrased as a state in which the pellet cooling transport water PCW that has flowed out of the water tank 50 by the water flow generated by the pump 60 is sent to the water chamber 30. The second state is a state in which the first forward path portion 100a and the return flow path 110 are connected, and the connection between the first forward path portion 100a and the second forward path portion 100b is prevented. The second state can be rephrased as a state in which the pellet cooling transport water PCW that has flowed out of the water tank 50 is exclusively sent back to the water tank 50.
[0056] The dryer 90 is positioned above the water chamber 30 and dries the resin pellets. The dryer 90 has a separation device (not shown) for separating the resin pellets from foreign matter.
[0057] The forward passage 100 forms part of the circulation channel 300 and connects the water tank 50 and the lower part of the water chamber 30. The inner diameter of the forward passage 100 is set to approximately 12 to 14 inches. The forward passage 100 has a first forward passage section 100a located between the water tank 50 and the flow path switching mechanism 80, and a second forward passage section 100b located between the flow path switching mechanism 80 and the water chamber 30. As shown in Figure 1, the second forward passage section 100b is equipped with a water level gauge 102 for measuring the water level of the pellet cooling transport water PCW.
[0058] The return channel 110 branches off from the outbound channel 100 and connects the outbound channel 100 to the water tank 50.
[0059] The water storage channel 120 is arranged in parallel with at least a portion of the forward path 100. The water storage channel 120 has an inner diameter smaller than the inner diameter of the forward path 100. Specifically, the inner diameter of the water storage channel 120 is set to approximately 2 to 3 inches. As shown in Figure 1, the water storage channel 120 according to this embodiment starts from a predetermined area in the first forward path portion 100a and ends at a predetermined area in the second forward path portion 100b. That is, the water storage channel 120 has a structure that branches off from the first forward path portion 100a and reaches the second forward path portion 100b. The water storage channel 120 is provided with a water storage channel valve 122. The water storage channel valve 122 is an on / off valve that can switch between an open state in which the water storage channel 120 is open and a closed state in which the water storage channel 120 is sealed. In this embodiment, the water storage channel valve 122 functions as a water supply unit that supplies pellet cooling transport water PCW from the water tank 50 to the water chamber 30 through the forward path 100.
[0060] The shaft passage 130 is arranged in parallel with at least a portion of the forward passage 100. The shaft passage 130 has an inner diameter smaller than the inner diameter of the forward passage 100. Specifically, the inner diameter of the shaft passage 130 is set to about 2 to 3 inches. In this embodiment, the shaft passage 130 starts from a predetermined region of the first forward passage portion 100a, passes through the inside of the rotating shaft 44, and ends at the other end 47 of the rotating shaft 44, communicating with the water chamber 30. The shaft passage 130 is provided with a shaft passage valve 132. The shaft passage valve 132 is an on / off valve that switches between an open state in which the shaft passage 130 is open and a closed state in which the shaft passage 130 is sealed.
[0061] The discharge channel 140 connects the bottom of the water chamber 30 to a discharge tank (not shown) provided by the pellet manufacturing apparatus 1. The discharge channel 140 is equipped with a discharge channel valve 142 whose opening degree can be adjusted. When the discharge channel valve 142 is opened, the pellet cooling transport water PCW stored in the water chamber 30 flows into the discharge tank.
[0062] The return channel 200 extends above the water chamber 30 and connects the water chamber 30 and the water tank 50. In detail, the return channel 200 has an upper connecting channel 150, an upward inclined channel 160 (inclined channel), a dryer connecting channel 170, and a water tank connecting channel 180.
[0063] The upper connecting channel 150 is connected to the upper end of the water chamber 30 and extends upward from that upper end.
[0064] The upward inclined channel 160 slopes upward toward the dryer 90. The upward inclined channel 160 has a base end 162 (lower end) connected to the upper connecting channel 150 and an upper end 163 (upper end) connected to the dryer connecting channel 170. As shown in Figure 1, the upper end 163 is located at the uppermost (highest) position in the return channel 200. Specifically, the upper end 163 is located about 20 m above the upper end of the water chamber 30.
[0065] The dryer connection channel 170 connects the upper end 163 of the upward inclined channel 160 to the dryer 90.
[0066] The water tank connection channel 180 extends downward from the dryer 90 and connects the dryer 90 to the water tank 50.
[0067] The water chamber 30, water tank 50, forward path 100, and return path 200 described above constitute a circulation channel 300. In the circulation channel 300, pellet cooling transport water PCW discharged from the water tank 50 by the pump 60 reaches the water chamber 30 through the forward path 100, and the pellet cooling transport water PCW flowing out of the water chamber 30 reaches the water tank 50 via the return path 200 (upper connecting channel 150, upward inclined channel 160, dryer connecting channel 170, and water tank connecting channel 180), passing above the water chamber 30.
[0068] <Method for manufacturing resin pellets in a resin pellet manufacturing apparatus> Next, the method for manufacturing resin pellets in the pellet manufacturing apparatus 1 according to this embodiment will be described. Figure 3 is a flowchart showing the method for manufacturing resin pellets. Figure 4 shows the flow of pellet cooling water when supplying water to the water chamber 30 using the water storage channel 120. Figure 5 shows the flow of pellet cooling transport water PCW when supplying water to the water chamber 30 using the axial passage channel 130. In the following, it is assumed that solidified resin has clogged the inside of the die hole 20H of the die plate 20 after the previous manufacturing process (described later).
[0069] Referring to Figure 3, first, a water supply process is performed to supply pellet cooling transport water PCW stored in the water tank 50 to the empty water chamber 30 (step S1). In the water supply process, the pellet cooling transport water PCW is sent to the water chamber 30 using the water storage channel 120. Specifically, the channel switching mechanism 80 is switched to the second state (the state in which the first forward path portion 100a and the return channel 110 are connected), and the water storage channel valve 122 is switched to the open state to open the water storage channel 120. When the pump 60 is started in this state, as shown in Figure 4, a portion of the pellet cooling transport water PCW discharged from the water tank 50 by the pump 60 flows back to the water tank 50 through the return channel 110, and the remaining pellet cooling transport water PCW flows to the water chamber 30 through the water storage channel 120.
[0070] In the water supply process, the water chamber 30 is filled with pellet cooling transport water PCW supplied to the water chamber 30 through the water storage channel 120. Then, referring to the measurement value of the water level gauge 102, when the water level (water surface) of the pellet cooling transport water PCW reaches the target water level TL (Figure 1), which is lower than the upper end 163 of the upward inclined channel 160, the water storage channel valve 122 is switched to the closed state to stop the supply of pellet cooling transport water PCW.
[0071] The target water level TL is lower than the water level of the pellet cooling transport water PCW when the circulation of the pellet cooling transport water PCW is stopped after it has been circulated. Preferably, the target water level TL is set at a position (height) that suppresses excessive water pressure acting on the water chamber 30. More specifically, it is preferable that the target water level TL is set at a position (height) that can suppress the generation of water pressure that would push back the resin material present in the multiple die holes 20H of the die plate 20, causing the pellet cooling transport water PCW to enter the multiple die holes 20H. As shown in Figure 1, in this embodiment, the target water level TL is set higher than the top of the water chamber 30 and lower than the base end 162 of the upward inclined flow channel 160. That is, the target water level TL is set in any region of the upper connecting flow channel 150.
[0072] Next, a rotation process is performed in which the cutters 48 are rotated while in contact with the die plate 20 (step S2). First, in the rotation process, pellet cooling transport water PCW is supplied to the water chamber 30 through the axial passage 130. Specifically, the flow path switching mechanism 80 is set to the second state (the state in which the forward first part 100a and the return flow path 110 are connected), and the axial passage valve 132 is opened to open the axial passage 130. In this way, as shown in Figure 5, a portion of the pellet cooling transport water PCW that has flowed out of the water tank 50 flows back into the water tank 50 through the return flow path 110, and the remaining pellet cooling transport water PCW flows into the water chamber 30 through the axial passage 130.
[0073] In the rotation process according to this embodiment, pellet cooling transport water PCW is supplied to the water chamber 30, while a portion of the pellet cooling transport water PCW is discharged through the discharge channel 140. Specifically, the flow rate of the pellet cooling transport water PCW discharged from the water chamber 30 is adjusted by adjusting the opening degree of the discharge channel valve 142, and the pellet cooling transport water PCW is discharged in this manner. This makes it possible to maintain the water level of the pellet cooling transport water PCW at the target water level TL.
[0074] Then, while the pellet cooling transport water PCW is being supplied and discharged, the rotating shaft 44 is advanced axially to bring the multiple cutters 48 into contact with the die plate 20, and the pelletizer motor 42 is started to rotate the multiple cutters 48. Note that the rotation of the multiple cutters 48 may start at an earlier point than the rotation process, for example, at the water supply process.
[0075] Furthermore, in the rotation process according to this embodiment, the output of the pelletizer motor 42 is adjusted so that the rotational speed of the multiple cutters 48 is smaller than the rotational speed of the multiple cutters 48 during the manufacturing process described later.
[0076] Next, a heating process is performed in which a heat transfer medium is flowed through the heat transfer medium channel 21 (Figure 2) of the die plate 20 to heat the die plate 20 (step S3). In the heating process according to this embodiment, pellet cooling transport water PCW is supplied through the water storage channel 120 or the shaft passage channel 130, and the pellet cooling transport water PCW is discharged through the discharge channel 140. During this time, the rotation of the multiple cutters 48 continues.
[0077] Next, a waiting process is performed (step S4) in which the die plate 20 waits until it reaches a predetermined temperature (the temperature at which the resin material packed in the die hole 20H melts). As described above, the temperature of the die plate 20 is measured by the temperature transmitter 22, so whether or not the predetermined temperature has been reached is determined based on the measurement value of the temperature transmitter 22.
[0078] Next, once the die plate 20 reaches a predetermined temperature, a circulation process is performed to circulate the pellet cooling transport water PCW (step S5). In the circulation process, the flow path switching mechanism 80 is switched to the first state (the state in which the first forward path portion 100a and the second forward path portion 100b are connected) to circulate the pellet cooling transport water PCW through the circulation flow path 300.
[0079] Next, a startup process is performed to start the mixer 4, feeder 2, and gear pump 6 (step S6). During the startup process, the resin material newly supplied from the feeder 2, mixed in the mixer 4, and pressurized by the gear pump 6 reaches the multiple die holes 20H, pushing the molten resin present in the multiple die holes 20H into the water chamber 30. In other words, the startup process is a process (material supply process) in which resin material is supplied to the die plate 20 from upstream (upstream in the direction of resin material transport).
[0080] Each of the steps from step S1 to step S6 described above corresponds to the method for starting the pellet manufacturing apparatus 1.
[0081] Next, the manufacturing process for producing resin pellets is carried out (step S7). First, in the manufacturing process, the molten resin discharged into the water chamber 30 is cut by multiple cutters 48 to granulate resin pellets. At this time, pellet cooling transport water PCW is supplied from the axial passage channel 130 so that the resin pellets do not accumulate near the rotation center of the cutters 48 (near the other end 47) due to the water flow generated in the water chamber 30 by the rotation of the multiple cutters 48. Next, the resin pellets are cooled by the pellet cooling transport water PCW stored in the water chamber 30 and transported to the dryer 90 by the pellet cooling transport water PCW flowing out of the water chamber 30. After the resin pellets are dried by the dryer 90, the dried resin pellets are discharged to the outside of the pellet manufacturing apparatus 1. This produces resin pellets.
[0082] Furthermore, resin pellets produced immediately after the start of the manufacturing process may not meet the quality standards for the product, and therefore these resin pellets may be discarded. In this case, the process up to the disposal of these resin pellets may be considered as part of the start-up method for the pellet manufacturing apparatus 1.
[0083] Next, once a predetermined number of resin pellets have been produced in the manufacturing process, a shutdown process is performed to stop the operation of the pellet manufacturing apparatus 1 (step S8). In the shutdown process, the operation of the mixer 4, feeder 2, and gear pump 6 is stopped to stop the supply of resin material, and the heating of the die plate 20 is stopped while molten resin is present inside the multiple die holes 20H. Then, the pellet cooling transport water PCW is circulated in the circulation channel 300 and the apparatus waits until the resin material packed inside the die holes 20H reaches a predetermined temperature (the temperature at which the molten material packed inside the die holes 20H solidifies). As a result, the resin material packed inside the die holes 20H exchanges heat with the circulating pellet cooling transport water PCW and solidifies inside the die holes 20H. In this way, the next operation of the pellet manufacturing apparatus 1 can be restarted from the state described above, "where solidified resin is packed inside the die holes 20H of the die plate 20". That is, the next operation can be restarted from the state in step S1. After that, the operation of the pellet manufacturing apparatus 1 is stopped.
[0084] As described above, in the water supply process according to this embodiment, the supply of pellet cooling transport water PCW is stopped in accordance with the target water level TL. Therefore, compared to the case in which the water level of pellet cooling transport water PCW is set to the target water level TL by circulating the pellet cooling transport water PCW in the circulation channel 300 and then discharging the pellet cooling transport water PCW, the amount of waste pellet cooling transport water PCW can be reduced.
[0085] Furthermore, in the water supply process according to the above embodiment, some of the pellet cooling transport water PCW is returned to the water tank 50, while the remaining pellet cooling transport water PCW is supplied to the water chamber 30. This reduces the flow rate of pellet cooling transport water PCW flowing into the water chamber 30 compared to the case where some of the pellet cooling transport water PCW is not returned to the water tank 50. As a result, the rate at which the pellet cooling transport water PCW accumulates in the water chamber 30 becomes relatively slow, making it easier to stop the water supply when the water level of the pellet cooling transport water PCW reaches the target water level TL.
[0086] Furthermore, in the water supply process according to the above embodiment, since the pellet cooling transport water PCW is supplied to the water chamber 30 through a water storage channel 120 having an inner diameter smaller than the inner diameter of the forward passage 100, it becomes easier to stop the water supply when the target water level TL is reached. Specifically, as described above, since the inner diameter of the forward passage 100 (forward passage second section 100b) is set to about 12 to 14 inches, if water is supplied exclusively using the forward passage second section 100b, the pellet cooling transport water PCW rapidly accumulates in the water chamber 30. Therefore, in this case, it is difficult to stop the water supply when the target water level TL is reached. In contrast, as in this embodiment, if the pellet cooling transport water PCW is supplied through a water storage channel 120 having an inner diameter smaller than the inner diameter of the forward passage 100, the flow rate of the pellet cooling transport water PCW flowing into the water chamber 30 can be reduced compared to the case where water is supplied exclusively through the forward passage second section 100b. As a result, the rate at which the pellet cooling transport water PCW accumulates in the water chamber 30 becomes relatively slow, making it easier to stop the water supply in the water supply process when the water level of the pellet cooling transport water PCW reaches the target water level TL.
[0087] Furthermore, in order to reduce the flow rate of the pellet cooling transport water PCW flowing into the water chamber 30, it is conceivable to equip the pellet manufacturing apparatus 1 with a pump that has a flow rate adjustment function instead of the pump 60 according to this embodiment. However, since pumps with such functions are generally expensive, such measures may increase the manufacturing cost of the pellet manufacturing apparatus 1. In contrast, in this embodiment, the flow rate of the pellet cooling transport water PCW can be reduced without using the expensive pump mentioned above, thus suppressing an increase in manufacturing costs.
[0088] Furthermore, in the rotation process according to the above embodiment, pellet cooling transport water PCW is supplied through the axial passage 130, so the temperature of the die plate 20 can be controlled. Specifically, in the rotation process, the temperature of the die plate 20 may rise excessively due to frictional heat generated by the rotation of the multiple cutters 48 that are in contact with the die plate 20. In contrast, with the above configuration, the temperature of the die plate 20 can be controlled by the pellet cooling transport water PCW supplied from the axial passage 130. That is, it is possible to suppress an excessive rise in the temperature of the die plate 20.
[0089] In particular, in the rotation process according to the above embodiment, pellet cooling transport water PCW is supplied through the axial passage 130 rather than the water storage passage 120. That is, pellet cooling transport water PCW can be supplied through the axial passage 130, which terminates at the other end 47 located near the die plate 20. As a result, pellet cooling transport water PCW can be supplied near the die plate 20, thereby more reliably suppressing an excessive rise in the temperature of the die plate 20.
[0090] Furthermore, in the rotation process according to the above embodiment, the pellet cooling transport water PCW is supplied and discharged while the multiple cutters 48 are rotated. That is, the pellet cooling transport water PCW in the water chamber 30 can be agitated by the multiple cutters 48 rotating in the water chamber 30 while the water in the water chamber 30 is replaced. This suppresses the occurrence of localized boiling in the water chamber 30. As a result, the surface temperature of the die plate 20 facing the water chamber 30 is kept uniform.
[0091] Furthermore, with the above configuration, the resin that drips out from the die holes 20H of the die plate 20 and is scooped up by the multiple cutters 48 can be removed to the outside of the water chamber 30 together with the pellet cooling transport water PCW discharged from the water chamber 30.
[0092] Furthermore, in the rotation process according to the above embodiment, the flow rate of the pellet cooling transport water PCW discharged from the discharge channel 140 is adjusted so that the water level of the pellet cooling transport water PCW is maintained at the target water level TL. This prevents the water level of the pellet cooling transport water PCW from being located at a water level that deviates from the target water level TL.
[0093] Furthermore, in the water supply process according to the above embodiment, since the target water level TL is set at a position lower than the base end 162 of the upward inclined flow channel 160, the water pressure acting inside the water chamber 30 can be suppressed compared to the case where the target water level TL is set at a position higher than the base end 162. This effectively prevents the pellet cooling transport water PCW from entering the die holes 20H by pushing back the resin material present inside the multiple die holes 20H of the die plate 20.
[0094] Furthermore, in the water supply process according to the above embodiment, there is no need to discharge the pellet cooling transport water PCW in the upward inclined channel 160, thus reducing the amount of waste pellet cooling transport water PCW. Specifically, if a method is adopted in which the pellet cooling transport water PCW is supplied to the upper end 163 of the upward inclined channel 160 by circulating it, and then the water level of the pellet cooling transport water PCW is set to the target water level TL by discharging the pellet cooling transport water PCW, then the pellet cooling transport water PCW accumulated in the submerged area AR shown in Figure 1 will be discharged. In contrast, in the water supply process according to this embodiment, after filling the water chamber 30 with pellet cooling transport water PCW, the supply of pellet cooling transport water PCW is stopped when the water level of the pellet cooling transport water PCW corresponds to the target water level TL. In this way, water does not accumulate in the submerged area AR, so there is no need to discharge the pellet cooling transport water PCW. As a result, the amount of waste pellet cooling transport water PCW is reduced.
[0095] Furthermore, in the rotation process according to the above embodiment, the output of the pelletizer motor 42 is adjusted so that the rotation speed of the multiple cutters 48 is smaller than the rotation speed of the multiple cutters 48 during the manufacturing process, thereby suppressing the occurrence of cavitation in the water chamber 30. As described above, during the rotation process, the water level of the pellet cooling transport water PCW is maintained at the target water level TL, and the water pressure acting in the water chamber 30 is suppressed. For this reason, if the rotation speed of the multiple cutters 48 during the rotation process is set to be the same as or larger than the rotation speed of the multiple cutters 48 during the manufacturing process, cavitation may occur. In contrast, in this embodiment, the output of the pelletizer motor 42 is adjusted so that the rotation speed of the multiple cutters 48 during the rotation process is smaller than the rotation speed of the multiple cutters 48 during the manufacturing process, thereby suppressing the occurrence of cavitation.
[0096] Furthermore, in the pellet manufacturing apparatus 1 according to the above embodiment, the pump 60 stops discharging the pellet cooling transport water PCW in accordance with the target water level TL. Therefore, by circulating the pellet cooling transport water PCW in the circulation channel 300 and then discharging the pellet cooling transport water PCW, the amount of waste pellet cooling transport water PCW can be reduced compared to the case where the water level of the pellet cooling transport water PCW is set to the target water level TL.
[0097] Furthermore, in the pellet manufacturing apparatus 1 according to the above embodiment, water can be supplied to the water chamber 30 through a water storage channel 120 having an inner diameter smaller than the inner diameter of the forward passage 100. This reduces the flow rate of pellet cooling transport water PCW flowing into the water chamber 30 compared to the case where water is supplied exclusively through the forward passage 100. As a result, the rate at which pellet cooling transport water PCW accumulates in the water chamber 30 becomes relatively slower, making it easier to stop the water supply when the water level of the pellet cooling water reaches the target water level TL. Consequently, the amount of waste pellet cooling transport water PCW can be reduced.
[0098] Furthermore, in the pellet manufacturing apparatus 1 according to the above embodiment, since the endpoint of the axial passage channel 130 is set to the other end 47, that is, the tip of the rotating shaft 44, it becomes possible to transport resin pellets that are accumulating near the other end 47 as usual. Specifically, resin pellets cut and granulated by the multiple cutters 48 are normally transported to the outside of the water chamber 30 by pellet cooling transport water PCW. However, the resin pellets may accumulate near the other end 47 due to the influence of the water flow generated in the water chamber 30 by the rotation of the multiple cutters 48. In contrast, with this configuration, since the endpoint of the axial passage channel 130 is set to the other end 47, pellet cooling water can be discharged from the other end 47 to move the resin pellets accumulating around the other end 47. This makes it possible to transport resin pellets that are accumulating near the other end 47 as usual.
[0099] Furthermore, since the pellet manufacturing apparatus 1 according to the above embodiment is equipped with a discharge channel 140, the pellet cooling transport water PCW can be discharged.
[0100] Furthermore, in the heating process according to this embodiment, pellet cooling transport water PCW is supplied through the water storage channel 120 or the axial passage channel 130, and the pellet cooling transport water PCW is discharged through the discharge channel 140. In other words, the pellet cooling transport water PCW in the water chamber 30 is replaced as needed. With this configuration, it is possible to suppress an excessive rise in the water temperature of the pellet cooling transport water PCW in the water chamber 30.
[0101] Furthermore, in the heating process according to this embodiment, multiple cutters 48 rotate. With this configuration, the rotation of the multiple cutters 48 agitates the pellet cooling transport water PCW stored in the water chamber 30, and the water temperature in the water chamber 30 becomes uniform. As a result, the die plate 20 can be heated uniformly.
[0102] Furthermore, in the starting method of the pellet manufacturing apparatus 1 according to the above embodiment, unlike the method in which the pellet cooling transport water PCW is circulated in the circulation channel 300 and then discharged to set the water level of the pellet cooling transport water PCW to the target water level TL, there is no need to discharge the pellet cooling transport water PCW. Therefore, the pellet manufacturing apparatus 1 can be started relatively quickly.
[0103] The pellet manufacturing apparatus 1 according to one embodiment of the present invention has been described above. However, the present invention is not limited to the above-described form. The following modified embodiments are possible in the present invention.
[0104] (1) In the above embodiment, an example was described in which the flow path switching mechanism 80 consists of a three-way valve, but instead, the flow path switching mechanism may consist of two on-off valves. Figure 6 is a diagram showing the schematic configuration of the flow path switching mechanism 80A according to this modified embodiment. As shown in Figure 6, the flow path switching mechanism 80A according to this modified embodiment has a first on-off valve 81A and a second on-off valve 82A. The first on-off valve 81A is an on-off valve that switches between an open state in which the first forward passage portion 100a and the second forward passage portion 100b are in communication and a closed state in which both portions 100a and 100b are blocked. The second on-off valve 82A is an on-off valve that switches between an open state in which the return passage 110 is open and a closed state in which the return passage 110 is blocked. For example, by opening the first on-off valve 81A and closing the second on-off valve 82A, a water flow similar to the first state related to the flow path switching mechanism 80 of the above embodiment can be realized. Furthermore, by closing the first on-off valve 81A and opening the second on-off valve 82A, a water flow similar to the second state of the flow path switching mechanism 80 according to the previous embodiment can be achieved. Also, by opening the first on-off valve 81A and opening the second on-off valve 82A, both the water chamber 30 and the water tank 50 can be used as destinations for the pellet cooling transport water PCW.
[0105] (2) In the above embodiment, an example was described in which the pellet manufacturing apparatus 1 is equipped with a water storage channel 120, but the water storage channel 120 is not essential. This will be explained in detail below.
[0106] Figure 7 is an exploded view of the pellet manufacturing apparatus 1B according to this modified embodiment. Figure 8 is a schematic diagram showing the configuration of the flow path switching mechanism 80B according to this modified embodiment. Figure 8(a) shows the flow path switching mechanism 80B in the first state, Figure 8(b) shows the flow path switching mechanism 80B in the second state, and Figure 8(c) shows the flow path switching mechanism 80B in the third state. In this modified embodiment, the differences from the above embodiment will be explained in detail, and the explanation of common points will be omitted.
[0107] As shown in Figure 7, the pellet manufacturing apparatus 1B differs from the pellet manufacturing apparatus 1 according to the previous embodiment in that it does not have a water storage channel 120. In addition, the pellet manufacturing apparatus 1B is equipped with a channel switching mechanism 80B instead of the channel switching mechanism 80 according to the previous embodiment.
[0108] The flow path switching mechanism 80B is a three-way valve located downstream of the pump 60 in the forward path 100 and has a first port connected to the first forward path portion 100a, a second port connected to the second forward path portion 100b, and a third port connected to the return flow path 110. As shown in Figures 8(a) to 8(c), the flow path switching mechanism 80B can switch between a first state, a second state, and a third state. The first state in this modified embodiment (Figure 8(a)) is a state in which the first forward path portion 100a is connected to both the second forward path portion 100b and the return flow path 110. The first state can be rephrased as a state in which both the water chamber 30 and the water tank 50 are destinations for the pellet cooling transport water PCW. The second state in this modified embodiment (Figure 8(b)) is a state in which the first forward passage portion 100a and the second forward passage portion 100b are connected, while preventing the first forward passage portion 100a from connecting with the return passage 110. The second state can be rephrased as a state in which the water chamber 30 is the destination for the pellet cooling transport water PCW. The third state in this modified embodiment (Figure 8(c)) is a state in which the first forward passage portion 100a and the return passage 110 are connected, while preventing the first forward passage portion 100a and the second forward passage portion 100b from connecting. The third state can be rephrased as a state in which the water tank 50 is exclusively the destination for the pellet cooling transport water PCW.
[0109] In the water supply process for this pellet manufacturing apparatus 1B, the pellet cooling transport water PCW is supplied to the water chamber 30 by closing the axial passage valve 132 while the flow path switching mechanism 80B is set to the first state.
[0110] Furthermore, in the rotation process of this pellet manufacturing apparatus 1B, the flow path switching mechanism 80B is set to the third state, and the axial passage valve 132 is opened to open the axial passage 130, thereby supplying pellet cooling transport water PCW to the water chamber 30 through the axial passage 130.
[0111] Furthermore, as shown in Figure 7, the first forward passage portion 100a of the pellet manufacturing apparatus 1B is provided with a flow control valve 105B, which is a valve whose opening degree can be adjusted. By reducing the opening degree of the flow control valve 105B, the flow rate of the pellet cooling transport water PCW flowing into the water chamber 30 can be reduced.
[0112] As described above, in the water supply process of the pellet manufacturing apparatus 1B according to this modified embodiment, the flow path switching mechanism 80B is set to the first state (a state in which the first forward path portion 100a is connected to both the second forward path portion 100b and the return flow path 110), so that some of the pellet cooling transport water PCW returns to the water tank 50, while the remaining pellet cooling transport water PCW is supplied to the water chamber 30. As a result, the flow rate of pellet cooling transport water PCW flowing into the water chamber 30 can be reduced compared to the case in which some of the pellet cooling transport water PCW is not returned to the water tank 50. As a result, the rate at which the pellet cooling transport water PCW accumulates in the water chamber 30 becomes relatively slow, making it easier to stop the water supply in accordance with the target water level TL. In other words, in the water supply process, the same effect as when the pellet cooling transport water PCW is supplied to the water chamber 30 using the water storage flow path 120 or the axial passage flow path 130 according to the previous embodiment can be achieved without using the water storage flow path 120 or the axial passage flow path 130 according to the previous embodiment.
[0113] Furthermore, when it becomes necessary to circulate the pellet cooling transport water PCW in a circulation process or other manner, the flow path switching mechanism 80B can be switched to the second state (a state in which the first forward path portion 100a and the second forward path portion 100b are connected) to set the destination of the pellet cooling transport water PCW to the water chamber 30.
[0114] Furthermore, if it is necessary to switch the destination of the pellet cooling transport water PCW to the water tank 50, for example, when supplying water through the axial passage 130, the passage switching mechanism 80B should be set to the third state (a state in which the forward passage first part 100a and the return passage 110 are connected).
[0115] Thus, the pellet manufacturing apparatus 1B according to this modified embodiment is equipped with a flow path switching mechanism 80B instead of the flow path switching mechanism 80 according to the previous embodiment, making it possible to easily switch the destination of the pellet cooling transport water PCW according to the purpose.
[0116] Furthermore, the pellet manufacturing apparatus 1B according to this modified embodiment is equipped with a flow control valve 105B, which is a valve whose opening degree can be adjusted. Therefore, for example, when the flow path switching mechanism 80B is set to the first state, the flow rate of the pellet cooling transport water PCW supplied to the water chamber 30 can be further reduced by setting the opening degree of the flow control valve 105B to a smaller value. As a result, the rate at which the pellet cooling transport water PCW accumulates in the water chamber 30 becomes even slower, making it even easier to stop the water supply when the water level of the pellet cooling water corresponds to the target water level TL.
[0117] (3) In the above embodiment, an example was described in which pellet cooling transport water PCW is supplied to the water chamber 30 through the water storage channel 120 in the water supply process. However, instead, the pellet cooling transport water PCW may be supplied through the shaft passage channel 130. In other words, the shaft passage valve 132 of the shaft passage channel 130 may function as the water supply unit according to the present invention. Alternatively, in the water supply process, the pellet cooling transport water PCW may be supplied to the water chamber 30 using both the water storage channel 120 and the shaft passage channel 130. That is, the water storage channel valve 122 of the water storage channel 120 and the shaft passage valve 132 of the shaft passage channel 130 may function as the water supply unit according to the present invention.
[0118] (4) In the above embodiment, a water storage channel 120 was described that starts from a predetermined region in the first forward channel portion 100a and ends in a predetermined region in the second forward channel portion 100b. However, the starting and ending points of the water storage channel 120 are not limited to these. Although not shown in the figures, the water storage channel 120 may start from a predetermined region in the return channel 110. Also, although not shown in the figures, the water chamber 30 may be the ending point.
[0119] (5) In the above embodiment, an axial passage 130 was described that starts from a predetermined region of the first forward passage 100a and ends at the other end 47 of the rotating shaft 44. However, the starting point of the axial passage 130 is not limited to this. Although not shown in the figures, the axial passage 130 may start from any region of the return passage 110.
[0120] (6) The pellet manufacturing apparatus 1 according to the above embodiment may further include a water volume adjustment channel that starts from the upper part of the water chamber 30 or a region of the upper connecting channel 150 that is lower than the target water level TL, and ends at a discharge tank (not shown).
[0121] (7) In the above embodiment, an example was described in which the water storage channel valve 122 functions as the water supply unit according to the present invention, but instead, the pump 60 may function as the water supply unit. In this case, stopping the water supply in the water supply process may be achieved by stopping the operation of the pump 60. The operation of the pump 60 may be stopped manually, or the operation may be automatically stopped by a control device (not shown) provided in the pellet manufacturing apparatus 1. [Explanation of symbols]
[0122] 1, 1B: Pellet manufacturing equipment 20: Die plate 20H: Die hole 30: Water room 44: Rotation axis 47: Other end (tip of the rotating shaft) 48: Cutter 50: Water tank 60: Pump 80, 80A, 80B: Flow path switching mechanism 100: Outbound journey 110: Return channel 120: Water storage channel (first auxiliary channel) 122: Water storage channel valve (water supply section) 130: Axial passage channel (second auxiliary channel) 140: Discharge channel 150: Upper connecting channel 160: Upward inclined channel (inclined channel) 162: Base end (lower end) 163: Upper end 200: Return trip 300: Circulation channel PCW: Pellet Cooling Water (Pellet Cooling Water) TL:Target water level
Claims
1. A method for starting a resin pellet manufacturing apparatus comprising: a circulation channel having a forward path for pellet cooling water discharged from a water tank by a pump to a water chamber and a return path for the pellet cooling water to return from the water chamber to the water tank via the upper part of the water chamber; a die plate having a plurality of die holes and positioned facing the water chamber; and a cutter positioned in the water chamber for cutting molten resin discharged from the plurality of die holes to granulate resin pellets, wherein the granulated resin pellets are transported from the water chamber while being cooled by the pellet cooling water flowing through the circulation channel, Before commencing the production of the resin pellets, the system includes a water supply step in which the pellet cooling water stored in the water tank is supplied to the water chamber by the pump to fill the water chamber, and then the supply of the pellet cooling water is stopped so that the water level of the pellet cooling water reaches a target water level set to be lower than the upper end of the return path. How to start up a resin pellet manufacturing machine.
2. In the water supply process, water is supplied to the water chamber while returning a portion of the pellet cooling water discharged from the water tank by the pump back to the water tank. A method for starting up a resin pellet manufacturing apparatus according to claim 1.
3. In the water supply process, the pellet cooling water is supplied to the water chamber through an auxiliary channel having an inner diameter smaller than the inner diameter of the forward path and arranged in parallel with at least a portion of the forward path. A method for starting a resin pellet manufacturing apparatus according to claim 1 or 2.
4. The process further comprises a rotation step, which is performed at least after the water supply step, and in which the cutter is rotated while in contact with the die plate, In the rotation process, the cutter is rotated while the pellet cooling water is supplied to the water chamber through the auxiliary channel. A method for starting up a resin pellet manufacturing apparatus according to claim 3.
5. In the rotation process, the pellet cooling water is supplied to the water chamber, and the pellet cooling water is discharged through a discharge channel that connects the water chamber to the outside of the water chamber. A method for starting up a resin pellet manufacturing apparatus according to claim 4.
6. In the rotation process, the amount of pellet cooling water discharged through the discharge channel is adjusted so that the water level of the pellet cooling water in the water chamber is maintained at the target water level. A method for starting a resin pellet manufacturing apparatus according to claim 5.
7. In the water supply process, a flow path switching mechanism, located downstream of the pump in the forward path and capable of switching between a first state in which both the water chamber and the water tank are destinations for the pellet cooling water, a second state in which one of the water chamber and the water tank is the destination for the pellet cooling water, and a third state in which the other of the water chamber and the water tank is the destination for the pellet cooling water, is set to the first state to supply the pellet cooling water to the water chamber. A method for starting up a resin pellet manufacturing apparatus according to claim 2.
8. The return path includes an upper connecting channel connected to the upper part of the water chamber and extending upward, and an inclined channel including a lower end connected to the upper connecting channel, which slopes upward from the lower end to the upper end of the return path. In the water supply process, the target water level is set at a position lower than the lower end. A method for starting a resin pellet manufacturing apparatus according to claim 7.
9. A method for manufacturing resin pellets in a resin pellet manufacturing apparatus, comprising a circulation path having a forward path for pellet cooling water discharged from a water tank by a pump to a water chamber and a return path for the pellet cooling water to return from the water chamber to the water tank via the upper part of the water chamber, Before starting the production of the resin pellets, a water supply step is performed to supply the pellet cooling water stored in the water tank to the water chamber. A rotation step in which a cutter placed inside the water chamber is rotated while in contact with a die plate having a plurality of die holes facing the water chamber, A heating step in which the die plate is heated to melt the resin present inside the plurality of die holes, A material supply process for supplying resin material from upstream to the die plate, A manufacturing process for producing resin pellets, comprising: cutting molten resin discharged from multiple die holes of the die plate with the cutter in the water chamber to granulate the resin pellets, and transporting the resin pellets from the water chamber while cooling them with pellet cooling water; The system includes a shutdown step in which heating of the die plate is stopped while molten resin is present inside the plurality of die holes, and the operation of the resin pellet manufacturing apparatus is stopped. In the water supply process, after filling the water chamber with the pellet cooling water, the supply of the pellet cooling water is stopped so that the water level of the pellet cooling water reaches a target level set to be lower than the upper end of the return path. A method for manufacturing resin pellets.
10. In the rotation process, the water level of the pellet cooling water is maintained at the target level, and the rotation speed of the cutter is set to be lower than the rotation speed of the cutter during the manufacturing process. A method for producing resin pellets according to claim 9.
11. A resin pellet manufacturing apparatus, A water tank that stores pellet cooling water, A water chamber that receives the pellet cooling water from the water tank, The forward path connecting the water tank and the water chamber, A return path connecting the water chamber and the water tank, passing above the water chamber, A water supply unit that supplies the pellet cooling water from the water tank to the water chamber through the forward path, A die plate having a plurality of die holes facing the inside of the water chamber, The system includes a cutter located in the water chamber, which granulates resin pellets by cutting the molten resin discharged from a plurality of die holes in the die plate within the water chamber, The water supply unit stops supplying the pellet cooling water when the water level of the pellet cooling water reaches a target level set to be lower than the upper end of the return path, before the production of the resin pellets begins. Resin pellet manufacturing equipment.
12. A first auxiliary channel having an inner diameter smaller than the inner diameter of the forward channel, which supplies the pellet cooling water flowing out of the water tank to the water chamber, A return channel that branches off from the aforementioned forward channel and connects the aforementioned forward channel and the aforementioned water tank, The system further includes a flow path switching mechanism for switching the destination of the pellet cooling water, The first auxiliary channel starts in the region between the water tank and the channel switching mechanism in the forward path, or in a predetermined region in the return channel, ends in the region between the channel switching mechanism and the water chamber in the forward path, or in the water chamber, and is opened when supplying the pellet cooling water to the water chamber before the start of the resin pellet manufacturing process. The resin pellet manufacturing apparatus according to claim 11.
13. The system further comprises a second auxiliary channel having an inner diameter smaller than the inner diameter of the forward channel and different from the first auxiliary channel, The second auxiliary flow path starts from the region between the water tank and the flow path switching mechanism in the forward path, or from a predetermined region in the return flow path, and ends at the tip of the rotating shaft of the cutter, and communicates with the water chamber. The resin pellet manufacturing apparatus according to claim 12.
14. The system further includes a discharge channel for discharging the pellet cooling water from the water chamber to the outside of the water chamber. A resin pellet manufacturing apparatus according to any one of claims 11 to 13.