JP2013244685A - Pellet producing method, and pellet producing device - Google Patents

Abstract

A pellet manufacturing method and a pellet manufacturing apparatus which prevent an overload of a motor driven in a drying process and prevent a poorly formed resin material from flowing into the drying process.
A forming step 3 for forming pellets by a molten resin material, a conveying step 4 for transferring the pellets formed in the forming step along a flow path 5 using water, and water by the flow path 5 The drying process 6 which accommodates the pellet conveyed with this in the rotation tank 6a, removes water, drives the rotation tank 6a with the motor 6b, and dries the pellet. In the transport process 4, part of the water is collected in the flow path 5 between the formation process 3 and the drying process 6, and the pellets are transported to the drying process 6 together with the remaining water. And in the conveyance process 4, the quantity of the water which flows into the drying process 6 is adjusted according to the electric current value of the motor 6b.
[Selection] Figure 1

Description

  The present invention relates to a pellet manufacturing method and a pellet manufacturing apparatus for transporting pellets formed of a resin material using a liquid and drying the pellets.

  A pellet manufacturing apparatus includes a pellet forming apparatus that forms pellets with a resin material, and a transport apparatus that includes a flow path for transporting pellets formed by the pellet forming apparatus using a liquid for transport (hereinafter simply referred to as water). And a centrifugal drying device for drying the pellets conveyed together with water (see, for example, Patent Document 1).

  The pellet forming apparatus includes an extruder having a screw and a cutter having a cutter for cutting a molten resin material extruded from the extruder in water. The centrifugal drying device has a rotating tub in which pellets conveyed together with water by a flow path are accommodated, and a motor that drives the rotating tub.

  Further, the transport device has a dehydrating mechanism for collecting a part of the water that flows with the pellets in the flow path between the pellet forming device and the centrifugal drying device. The dewatering mechanism includes a scrap receiving member for collecting a poorly formed resin material flowing through the flow path, and a dewatering screen for collecting water through the water.

  Resin powder purified by a resin processing apparatus (not shown) is supplied to the extruder of the pellet forming apparatus configured as described above. The extruder is heated by an electric heater or steam, and melts the resin powder by rotating a screw. The molten resin material is sent to a die that forms the tip of the extruder. The die to which the molten resin material is sent pushes the molten resin material into a strand shape inside a cutter chamber disposed in water. The strand-shaped resin material extruded into the cutter chamber is cut by a cutter that rotates in water, thereby forming a pellet.

  After the pellet is formed, the water that has filled the inside of the cutter chamber when the resin material is cut flows along the flow path along with the pellet, thereby conveying the pellet along the flow path from the pellet forming apparatus to the centrifugal drying apparatus. . For this reason, the water used for conveying pellets is called PCW [Pellet Conveying Water]. The PCW water is partly recovered from the water flowing along with the pellets by the dehydration mechanism arranged upstream of the flow path with respect to the centrifugal drying device, and the remaining water is sent to the centrifugal drying device together with the pellets. Inflow. At this time, the water collected by the dehydration mechanism is stored in the PCW tank and supplied from the PCW tank to the cutter chamber of the pellet forming apparatus.

  In addition, the pellets conveyed from the pellet forming apparatus include poorly formed resin materials (hereinafter referred to as agglomerated resin materials) that are not formed into pellets due to defective cutting by the cutter but are agglomerated. Yes. The agglomerated resin material is recovered from the water flowing through the flow path by the scrap receiving member of the dewatering mechanism, and is subjected to primary dewatering as described above, and a part of the water carrying the pellets is recovered in the PCW tank. The

JP 2009-29032 A

  As described above, in the pellet forming apparatus, a strand-like shape discharged from a die in a molten state by rotating the cutter while pressing the cutter with a predetermined pressing force against the surface of the die of the extruder. The resin material is cut to form pellets.

  By the way, in the pellet manufacturing apparatus, when the manufacturing conditions such as the pellet forming speed (production amount) and the viscosity of the resin material to be used are changed, the pressing force of the cutter against the die of the extruder may not be appropriate immediately after the change. is there. In such a case, a gap is generated between the die and the cutter, and the resin material discharged from the die is not properly cut by the cutter. Therefore, a cutting failure occurs in which a normal pellet is not formed and an agglomerated resin material or a resin material in a state where a plurality of pellets are connected in a daisy chain (hereinafter referred to as a rosary resin material). End up.

  In this case, since the agglomerated resin material is received by the scrap receiving member, it can be removed from the water flowing through the flow path. However, since the bead-like resin material is about the same size as the pellet, it passes through the scrap receiving member, passes through the dewatering screen arranged on the downstream side of the flow path, and flows into the centrifugal drying device. . At this time, since the beaded resin material contains a large amount of water, the amount of water flowing into the centrifugal drying apparatus together with the beaded resin material is increased.

  Thus, when the amount of water flowing into the centrifugal drying device increases, the weight applied to the rotating tub in which the beaded resin material is accommodated together with the water increases, so the load on the motor that drives the rotating tub increases. End up. When the motor is overloaded, the centrifugal drying device is stopped, and when the centrifugal drying device is stopped, the whole pellet manufacturing apparatus is stopped.

  When the centrifugal drying device is stopped, a great amount of labor and time are required to perform the operation of removing a large amount of the bead-like resin material that has flowed into the rotary tank of the centrifugal drying device. As a result, it takes time to restart the pellet manufacturing apparatus.

  For this reason, even when a cutting failure occurs in the pellet forming apparatus, a large amount of water is prevented from flowing into the centrifugal drying apparatus together with the bead-like resin material, and the amount of water flowing into the centrifugal drying apparatus is appropriately controlled. It is demanded.

  Then, an object of this invention is to provide the pellet manufacturing method and pellet manufacturing apparatus which can solve the subject of the said related technique. An object of the present invention is to provide a pellet manufacturing method and a pellet manufacturing apparatus capable of preventing an overload of a motor driven in a drying process.

  In order to achieve the above-described object, a pellet manufacturing method according to the present invention includes a forming step of forming pellets with a molten resin material, and conveying the pellets formed in the forming step along a flow path using a liquid. And a drying step in which the pellets transported together with the liquid by the flow path are accommodated in a tank, and the pellets are dried by removing the liquid while driving the tank with a motor. In the transporting process, a part of the liquid is collected in the flow path between the forming process and the drying process, and the pellets are transported to the drying process together with the remaining liquid. In the transport process, the amount of liquid flowing into the drying process is adjusted according to the current value of the motor.

  In addition, the pellet manufacturing apparatus according to the present invention includes a pellet forming apparatus that forms pellets with a molten resin material, a transport apparatus that has a flow path for transporting pellets using liquid, and a pellet forming apparatus that uses a flow path. A tank for storing the pellets transported together with the liquid, and a motor for driving the tank, and a drying device for removing the liquid and driving the pellets while driving the tank with the motor. The transport device has a liquid recovery mechanism that recovers a part of the liquid flowing in the flow path between the pellet forming device and the drying device. The liquid recovery mechanism includes a filter member for allowing the liquid to pass therethrough, a filter adjustment member for adjusting the amount of liquid passing through the filter member, the filter adjustment member being provided to be movable with respect to the filter member, A moving mechanism that moves the filter adjusting member, and a control unit that controls the moving mechanism based on the current value of the motor.

  According to the present invention, the motor driven in the drying process is prevented from being overloaded by adjusting the amount of liquid flowing into the drying process together with the pellets according to the current value of the motor driven in the drying process. In addition, the poorly formed resin material can be prevented from flowing into the drying process.

It is a schematic diagram which shows the whole pellet manufacturing apparatus of embodiment. It is a front view which shows the dehydration mechanism with which the pellet manufacturing apparatus of embodiment is provided. It is a side view which shows the dehydration mechanism with which the pellet manufacturing apparatus of embodiment is provided. It is a flowchart for demonstrating control in the spin-drying | dehydration mechanism with which the pellet manufacturing apparatus of embodiment is provided.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

  In FIG. 1, the schematic diagram of the whole pellet manufacturing apparatus is shown.

  As shown in FIG. 1, a pellet manufacturing apparatus 1 according to an embodiment includes a pellet forming apparatus 3 that forms pellets with a resin material, and a flow path that conveys the pellets formed by the pellet forming apparatus 3 using water as a liquid. And a centrifugal drying device 6 for drying the pellets transported together with water from the pellet forming device 3 by the flow path 5.

  Although not shown, the pellet forming apparatus 3 includes an extruder having a screw and a cutter having a cutter for cutting the strand-shaped resin material extruded from the extruder in water. The centrifugal drying device 6 includes a rotating tank 6a in which pellets conveyed along with water by the flow path 5 are accommodated, and a motor 6b that drives the rotating tank 6a. The motor 6b rotates the rotating tank 6a. Remove the water while drying the pellets.

  Further, the transport device 4 has a dehydrating mechanism 8 as a liquid recovery mechanism for recovering a part of the water flowing together with the pellets in the flow path 5 between the pellet forming device 3 and the centrifugal drying device 6. . Further, the transport device 4 has a PCW tank 9 that stores the water collected by the dehydration mechanism 8, and is supplied from the PCW tank 9 to the pellet forming device 3 through the flow path 5 by a pump (not shown). ing. Therefore, the water for conveying the pellets is circulated so as to flow from the PCW tank 9 to the pellet forming apparatus 3 after flowing in the order of the pellet forming apparatus 3, the dehydrating mechanism 8, and the PCW tank 9.

  In FIG. 2, the front view of the spin-drying | dehydration mechanism 8 with which the pellet manufacturing apparatus 1 of embodiment is provided is shown. In FIG. 3, the side view of the spin-drying | dehydration mechanism 8 with which the pellet manufacturing apparatus 1 of embodiment is provided is shown.

  As shown in FIGS. 2 and 3, the dehydrating mechanism 8 is provided in the flow path 5 between the pellet forming device 3 and the centrifugal drying device 6. The dehydrating mechanism 8 has a scrap receiving member 11 for collecting the agglomerated resin material flowing through the flow path 5, a dehydrating screen 12 as a filter member for allowing water to pass through, and a dehydrating screen 12. A screen adjusting plate 13 serving as a filter adjusting member for adjusting the amount of water (opening / closing degree) passing through the dehydrating screen 12 so as to be movable, and a slide for sliding the screen adjusting plate 13 relative to the dehydrating screen 12 The mechanism 15, the flow meter 16 as a flow rate detector for detecting the flow rate of the water that has passed through the dehydration screen 12, and the slide mechanism 15 are controlled based on the current value of the motor 6 b and the flow rate detected by the flow meter 16. And a control unit 17 that performs.

  The weight of the scrap receiving member 11 is detected by a detector (not shown), and when the total weight of the agglomerated resin material collected by the scrap receiving member 11 exceeds a predetermined weight, a driving mechanism (not shown) Moved. By moving the scrap receiving member 11, the collected agglomerated resin material is discharged from the discharge path 18 communicating with the flow path 5. Thus, the pellet containing the agglomerated resin material conveyed with water from the pellet forming apparatus 3 is separated into the agglomerated resin material, the pellets, and water. If the pellets contain a beaded resin material, the beaded resin material passes through the scrap receiving member 11 and flows downstream along the flow path 5.

  The dewatering screen 12 has a plurality of holes through which water passes and is formed in a net shape. The dewatering screen 12 is disposed in the flow path 5 between the pellet forming device 3 and the centrifugal drying device 6. The screen adjustment plate 13 is disposed adjacent to the upstream side of the dewatering screen 12 and parallel to the dewatering screen 12. The screen adjusting plate 13 is slid parallel to the dewatering screen 12 so that the area that covers the dewatering screen 12 changes, and the amount of passage corresponding to the size of the area of the mesh portion of the dewatering screen 12 is multistage. Adjust with.

  The slide mechanism 15 has a hydraulic cylinder connected to the screen adjustment plate 13 and is controlled by the control unit 17.

  The control unit 17 is electrically connected to the motor 6b, the flow meter 16, and the slide mechanism 15. Then, the control unit 17 calculates the amount of water flowing into the centrifugal drying device 6 using the flow rate detected by the flow meter 16, and slides based on the calculated amount of water and the current value of the motor 6b. The mechanism 15 is controlled.

  The pellet forming method using the pellet manufacturing apparatus 1 configured as described above includes a forming step of forming pellets with a melted resin material, and the pellets formed in the forming step are transferred to the flow path 5 using water. A transporting process for transporting along the pellet, and a drying process for storing the pellets transported together with water by the flow path 5 in the rotating tank 6a, and removing the water while driving the rotating tank 6a by the motor 6b to dry the pellets. Have.

  In the transport process, part of the water is collected in the flow path 5 between the forming process and the drying process, and the pellets are transported to the drying process together with the remaining water. And in a conveyance process, the quantity of the water which flows in into a drying process is adjusted according to the electric current value of the motor 6b.

  In the transporting process, the water passing through the dehydrating screen 12 is collected, and the amount of water passing through the dehydrating screen 12 is controlled based on the flow rate of the water that has passed through the dehydrating screen 12 and the current value of the motor 6b. The control unit 17 adjusts the amount of water flowing into the centrifugal drying device 6 in the drying process by controlling the passing amount of the dehydration screen 12.

  In the transporting process, after adjusting the amount of water flowing into the drying process, when the current value of the motor 6b driven in the drying process becomes smaller than a predetermined value, the passing amount of the dewatering screen 12 is increased.

  About the above pellet manufacturing method, the operation | movement which adjusts automatically the quantity of the water which flows in into the rotation tank 6a of the centrifugal drying apparatus 6 is demonstrated. In FIG. 4, the flowchart for demonstrating control in the spin-drying | dehydration mechanism 8 with which the pellet manufacturing apparatus 1 of embodiment is provided.

  As shown in FIG. 4, in the pellet manufacturing method, the pellet manufacturing apparatus 1 starts manufacturing pellets (step S1). In step S2, the current value of the motor 6b of the centrifugal drying device 6 is equal to or less than a predetermined current value ( It is determined whether the control unit 17 is in a normal state).

  When the current value of the motor 6b is equal to or less than the predetermined current value, the control unit 17 continues the production of pellets without adjusting the amount of water passing through the dehydration screen 12 (step S8). Moreover, the control part 17 returns to step S2 and monitors the electric current value of the motor 6b.

  When the current value of the motor 6b is larger than the predetermined current value, the control unit 17 calculates the amount of water that has flowed to the PCW tank 9 through the dehydration screen 12, based on the flow rate detected by the flow meter 16. . Subsequently, in step S <b> 3, the control unit 17 subtracts the amount of water that has passed through the dehydration screen 12 from the total amount of water used in the transport device 4, thereby reducing the amount of water flowing into the centrifugal drying device 6. Calculate (first calculation).

  Subsequently, the control unit 17 controls the slide mechanism 15 based on the amount of water obtained in the first calculation and the current value of the motor 6b corresponding to the load generated in the centrifugal drying device 6 ( Step S4). At this time, the control unit 17 controls the position of the screen adjustment plate 13 by the slide mechanism 15 so that the amount of water flowing into the centrifugal drying device 6 is reduced, that is, the passage amount of the dehydration screen 12 is increased. Thus, the passage amount of the dehydration screen 12 is adjusted in multiple stages according to the amount of water flowing into the centrifugal drying device 6 and the current value of the motor 6b.

  Next, by adjusting the screen adjusting plate 13, the amount of water flowing into the centrifugal drying device 6 is adjusted, and then the current value of the motor 6b of the centrifugal drying device 6 is reduced, and the load on the motor 6b is reduced. . After adjusting the passing amount of the dehydrating screen 12, the control unit 17 determines whether the current value of the motor 6b of the centrifugal drying device 6 is equal to or less than a predetermined current value (normal state) in step S5. Determine whether. Then, when the current value of the motor 6b of the centrifugal drying device 6 becomes equal to or lower than the predetermined current value, the control unit 17 again determines in step S6 based on the current value and the flow rate detected by the flow meter 16. The amount of water flowing into the centrifugal drying device 6 is calculated (second calculation).

  Subsequently, the control unit 17 controls the slide mechanism 15 based on the amount of water obtained by the second calculation and the current value of the motor 6b (step S7). At this time, the control unit 17 controls the position of the screen adjustment plate 13 by the slide mechanism 15 so that the amount of water flowing into the centrifugal drying device 6 is increased, that is, the passing amount of the dehydration screen 12 is decreased. Thus, the passage amount of the dewatering screen 12 is adjusted. Thereafter, the formation of pellets is continued (step S8).

  As described above, according to the pellet manufacturing apparatus 1 of the embodiment, the amount of water flowing into the centrifugal drying device 6 and the centrifugal drying device 6 even when a pellet formation failure occurs in the pellet forming device 3. The amount of water flowing into the centrifugal drying device 6 is automatically adjusted according to the current value of the motor 6b that is driven by. As a result, the amount of water flowing to the centrifugal drying device 6 is reduced, the motor 6b driven by the centrifugal drying device 6 is prevented from being overloaded, and a bead-like resin material containing a large amount of water flows into the centrifugal drying device 6. That can be suppressed. As a result, it is possible to prevent the centrifugal drying device 6 from being overloaded and stopped, and the entire pellet manufacturing device 1 from being stopped, leading to an increase in the productivity of the pellet manufacturing device 1.

  In the above-described embodiment, the passing amount (opening / closing degree) of the dehydration screen 12 is adjusted based on the amount of water flowing into the centrifugal drying device 6 in the drying step and the current value of the motor 6b driven in the drying step. However, any configuration may be used as long as the amount of passage of the dewatering screen 12 is adjusted based on at least the current value of the motor 6b. Furthermore, the pellet manufacturing apparatus 1 is configured to adjust the passage amount of the dehydration screen 12 based on the current value of the motor 6b and other detection values related to the amount of water flowing into the centrifugal drying device 6. Also good.

  In this embodiment, the slide mechanism 15 is controlled based on the amount of water flowing into the centrifugal drying device 6 and the current value of the motor 6b, but the amount of water flowing into the centrifugal drying device 6 is changed. Instead of using, the slide mechanism 15 may be controlled based only on the current value of the motor 6b.

  In the present embodiment, the centrifugal drying device 6 having the rotating tank 6a is used. However, the centrifugal drying apparatus 6 is not limited to the rotating tank, and water is removed while driving the tank containing the pellets by a motor. Of course, as long as the pellet is dried, the tank may reciprocate, and other drying devices may be employed.

  Other drying devices that can be used in place of the centrifugal drying device include a drying device configured to blow cold air on the pellets in the tank while being driven by a motor, and the heater in the pellets in the tank. And a drying device configured to add.

  In addition to the mechanical and electrical flow meters, an ultrasonic flow sensor may be used as the detector. Moreover, in the pellet manufacturing apparatus 1 of embodiment, although water was used as a liquid for conveying a pellet, other liquids, such as a chemical | medical solution containing various additives, may be used as needed. Of course.

DESCRIPTION OF SYMBOLS 1 Pellet production apparatus 3 Pellet formation apparatus 4 Conveyance apparatus 5 Flow path 6 Centrifugal drying apparatus 6a Rotating tank 6b Motor 8 Dehydration mechanism 12 Dehydration screen 16 Flowmeter

Claims (6)

A forming step of forming pellets with a melted resin material, a transporting step of transporting the pellets formed in the forming step along a flow path using a liquid, and the liquid transported together with the liquid A drying step of storing the pellets in a tank and drying the pellets by removing the liquid while driving the tank with a motor, and in the conveying step, between the forming step and the drying step A part of the liquid, and a part of the liquid is collected, and the pellet is transferred to the drying step together with the remaining liquid,
In the conveying step, the amount of the liquid flowing into the drying step is adjusted according to the current value of the motor, and the pellet manufacturing method.   In the transporting step, the liquid passing through the filter member is collected, and the amount of the liquid passing through the filter member is determined based on the amount of the liquid flowing into the drying step and the current value of the motor. The pellet manufacturing method of Claim 1 controlled.   In the conveyance step, after adjusting the amount of the liquid flowing into the drying step, when the current value of the motor becomes a predetermined current value or less, the passing amount of the filter member is reduced. 2. The pellet manufacturing method according to 2. A pellet forming apparatus for forming pellets with a molten resin material;
A transport device having a flow path for transporting the pellets using a liquid;
A tank for storing the pellets transported together with the liquid from the pellet forming apparatus by the flow path; and a motor for driving the tank; removing the liquid while driving the tank with the motor; A drying device for drying the pellets,
The transport apparatus is a pellet manufacturing apparatus having a liquid recovery mechanism for recovering a part of the liquid flowing in the flow path between the pellet forming apparatus and the drying apparatus,
The liquid recovery mechanism is
A filter member for passing and collecting the liquid;
A filter adjusting member provided so as to be movable with respect to the filter member, and for adjusting an amount of the liquid passing through the filter member;
A moving mechanism for moving the filter adjusting member with respect to the filter member;
And a control unit that controls the moving mechanism based on a current value of the motor. A flow rate detector for detecting the flow rate of the liquid that has passed through the filter member;
The control unit calculates the amount of the liquid flowing into the drying device using the flow rate detected by the flow rate detector, and the moving mechanism based on the amount of the liquid and the current value of the motor. The pellet manufacturing apparatus of Claim 4 which controls.   The control unit adjusts the amount of the liquid flowing into the drying device by controlling the moving mechanism, and then the passage of the filter member when the current value of the motor becomes a predetermined current value or less. The pellet manufacturing apparatus of Claim 5 which controls the said moving mechanism so that quantity may become small.

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