Injection molding machine

Abstract

The present invention provides an injection molding machine that reduces the operation burden of an operator during the cleaning operation. An injection molding machine, when instructed to perform the cleaning of a receiving tray that discharges the plasticized resin (S11: receiving tray), causes the heating cylinder in the standby position to discharge the plasticized resin at a first discharge speed (S12). The receiving tray is provided on the discharge path for discharging the plasticized resin from the heating cylinder in the standby position. When instructed to perform the cleaning of a conveyor that discharges the plasticized resin (S11: conveyor), the heating cylinder in the standby position discharges the plasticized resin at a second discharge speed that is slower than the first discharge speed (S18).

Description

Technical Field

[0001] The present invention relates to an injection molding machine that injects a plasticized resin into a mold to form an injection molded product. Background Art

[0002] Patent Document 1 discloses a vertical injection molding machine having a heating cylinder that moves up and down between a contact position where it contacts a resin injection hole of a mold and a retraction limit position above the contact position. In addition, Patent Document 1 describes the content of performing a purging operation of discharging the plasticized resin in the heating cylinder.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2012 - 153110 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] In the injection molding machine described in Patent Document 1, an operator needs to place a receiving tray for receiving the plasticized resin at a positioning portion directly below the heating cylinder before performing the purging operation and remove it from the positioning portion before performing injection molding again. Moreover, when the amount of the plasticized resin discharged by the purging operation is large, the operator needs to remove the plasticized resin in the receiving tray during the purging operation.

[0008] Therefore, in the injection molding machine having the above structure, there is a problem that the operation burden on the operator during the purging operation is large. In addition, this problem occurs not only in vertical injection molding machines but also in horizontal injection molding machines in which the heating cylinder moves in the horizontal direction.

[0009] The present invention has been made to solve such problems of the prior art, and an object thereof is to provide an injection molding machine that reduces the operation burden on the operator during the purging operation.

[0010] Means for Solving the Problems

[0011] The present invention provides an injection molding machine to solve the above problems. The injection molding machine injects plasticized resin into a mold to manufacture an injection molded product, and is characterized by having: a heating cylinder, a nozzle formed at the front end of which moves between an injection position and a standby position, the injection position being a position where the heating cylinder communicates with the cavity of the mold, and the standby position being a position where the heating cylinder is separated from the mold; a conveyor configured on a discharge path for discharging the plasticized resin from the heating cylinder in the standby position to convey the plasticized resin discharged from the nozzle to the outside of the injection molding machine; and a control device for controlling the operations of the heating cylinder and the conveyor. When the control device is instructed to perform a cleaning operation of a receiving tray for discharging the plasticized resin from the receiving tray, the heating cylinder in the standby position discharges the plasticized resin at a first discharge speed. The receiving tray is arranged on the discharge path for discharging the plasticized resin from the heating cylinder in the standby position. When the control device is instructed to perform a cleaning operation of the conveyor for discharging the plasticized resin from the conveyor, the heating cylinder in the standby position discharges the plasticized resin at a second discharge speed slower than the first discharge speed.

[0012] According to the above structure, it is possible to select a "receiving tray cleaning operation" that requires an operator to place and remove the receiving tray and a "conveyor cleaning operation" that can automatically discharge the plasticized resin through the conveyor. As a result, the operation burden of the operator for disassembling and assembling the receiving tray during the cleaning operation can be reduced.

[0013] In addition, if the plasticized resin is strongly discharged during the conveyor cleaning operation, the plasticized resin reaching the surface of the conveyor may fly out of the conveyor or may invade the inside of the conveyor. Moreover, the scattering or invasion of the plasticized resin increases the burden on the operator for maintaining the injection molding machine. Therefore, as described above, by making the discharge speed during the conveyor cleaning operation slower than that during the receiving tray cleaning operation, the conveyor cleaning operation can be achieved well without increasing the maintenance burden.

[0014] Furthermore, the injection molding machine of the present invention may be characterized in that the injection molding machine has a resin pressure sensor for detecting the resin pressure applied to the plasticized resin in the heating cylinder. When the control device is instructed to perform the conveyor cleaning operation, if the resin pressure detected by the resin pressure sensor is above a threshold value, the heating cylinder in the standby position discharges the plasticized resin at the second discharge speed. If the resin pressure detected by the resin pressure sensor is less than the threshold value, the heating cylinder in the standby position discharges the plasticized resin at a third discharge speed slower than the second discharge speed.

[0015] When the resin pressure is above the threshold value, it means that the viscosity of the plasticized resin in the heating cylinder is high to a certain extent. Therefore, the possibility of the plasticized resin reaching the conveyor flying or intruding is low. On the other hand, when the resin pressure is less than the threshold value, it means that the viscosity of the plasticized resin in the heating cylinder is low. Therefore, the possibility of the plasticized resin reaching the conveyor flying or intruding is high. Therefore, with the above structure, by adjusting the discharge speed according to the resin pressure (in other words, the viscosity of the plasticized resin), it is possible to balance maintaining the productivity of the cleaning operation and reducing the maintenance burden.

[0016] As an example, the injection molding machine of the present invention may be characterized in that the injection molding machine has a screw that can advance, retreat, and rotate in the heating cylinder, and when the control device is instructed to perform the cleaning of the conveyor, the screw disposed at the position closest to the nozzle is rotated in the direction of moving the plasticized resin toward the nozzle side, thereby discharging the plasticized resin from the nozzle, and the discharge speed of the plasticized resin is adjusted by increasing or decreasing the rotation speed of the screw.

[0017] In addition, the injection molding machine of the present invention may be characterized in that the control device retracts the screw at regular intervals during the cleaning of the conveyor.

[0018] In addition, the plasticized resin reaching the conveyor solidifies into a rod shape and is discharged. Therefore, if the discharge of the plasticized resin is continuously performed for a long time, the rod-shaped plasticized resin becomes longer and is difficult to handle. Therefore, with the above structure, by retracting the screw at regular intervals, the space on the nozzle side of the screw in the heating cylinder becomes negative pressure, and the discharge of the plasticized resin is temporarily stopped. As a result, a plurality of plasticized resins that are short-segmented can be discharged from the conveyor.

[0019] As another example, the injection molding machine of the present invention may be characterized in that the injection molding machine has a screw that can advance, retreat, and rotate in the heating cylinder, and when the control device is instructed to perform the cleaning of the conveyor, the plasticized resin is intermittently discharged by advancing and retreating the screw.

[0020] In addition, the injection molding machine of the present invention may be characterized in that the injection molding machine has a resin pressure sensor that detects the resin pressure applied to the plasticized resin in the heating cylinder, and when the control device is instructed to perform the cleaning of the conveyor, the process of detecting the resin pressure by the resin pressure sensor and advancing the screw at a speed corresponding to the detected resin pressure is repeatedly executed.

[0021] The viscosity of the plasticized resin has the following tendency: the longer the residence time in the heating cylinder, the lower the viscosity; the shorter the residence time, the higher the viscosity. That is, the viscosity of the plasticized resin already in the heating cylinder at the start of the cleaning operation becomes relatively low, and the viscosity of the newly supplied plasticized resin to the heating cylinder during the cleaning operation becomes relatively high. Therefore, with the above structure, each time the screw advances, the resin pressure is detected and an appropriate advance speed is set, thereby enabling both the productivity of the cleaning operation to be maintained and the maintenance burden to be reduced.

[0022] In addition, the injection molding machine of the present invention may be characterized in that, when the control device is instructed to perform the conveyor cleaning, the conveying speed of the conveyor is adjusted according to the discharge speed of the plasticized resin discharged from the heating cylinder.

[0023] According to the above structure, the plasticized resin discharged through the cleaning operation can be discharged well outside the injection molding machine.

[0024] Effects of the Invention

[0025] According to the present invention, since the pan cleaning and the conveyor cleaning can be switched according to the situation, the operation burden of the operator during the cleaning operation can be reduced. In addition, by making the discharge speed during the conveyor cleaning slower than the discharge speed during the pan cleaning, the conveyor cleaning can be achieved well without increasing the maintenance burden. Description of the Drawings

[0026] Figure 1 is a front view of the injection molding machine of the first embodiment.

[0027] Figures 2A to 2D is an enlarged schematic view of the injection device.

[0028] Figure 3 is a hardware block diagram of the injection molding machine.

[0029] Figure 4 is a flowchart of the cleaning control process of the first embodiment.

[0030] Figure 5 is a flowchart of the cleaning control process of the second embodiment.

[0031] Figure 6 is a side view showing the schematic structure of the injection molding machine of the third embodiment.

[0032] Figure 7A 、 Figure 7B is a front view of the heating cylinder of the third embodiment observed from the front end side.

[0033] Description of Reference Numerals

[0034] 10, 10A... Injection molding machines, 20... Clamping device, 21... Mold, 22... Fixed-side mold, 23... Fixed platen, 24... Movable-side mold, 25... Movable platen, 30... Injection device, 31... Heating cylinder, 32... Screw, 33... Conveyor, 34... Fan (cooling device), 35... Cover, 36... Nozzle, 36a... Nozzle hole, 37... Housing, 37a, 37b, 37c... Slits, 38... Guide plate, 40... Display input device, 41... Resin pressure sensor, 50... Control device, 51... CPU, 52... ROM, 53... RAM, 61... Mold opening / closing motor, 62... Nozzle contact motor, 63... Metering motor, 64... Injection motor, 65... Conveyor forward / backward motor, 66... Conveyor drive motor, 67... Cover forward / backward motor. Detailed implementation mode

[0035] Hereinafter, the injection molding machine 10 of the present invention will be described based on the drawings. In addition, the embodiments of the present invention described below are examples showing the concretization of the present invention, and the scope of the present invention is not limited to the scope described in the embodiments. Therefore, the present invention can be implemented with various modifications to the embodiments.

[0036] (First embodiment)

[0037] Figure 1 It is a front view of the injection molding machine 10 of the first embodiment. Figures 2A to 2D It is an enlarged schematic view of the injection device 30. Figure 3 It is a hardware block diagram of the injection molding machine 10. The injection molding machine 10 is a device that injects plasticized resin into a mold to form an injection molded product. The injection molding machine 10 of the first embodiment is a so-called "vertical" injection molding machine. As Figures 1 to 3 shown, the injection molding machine 10 mainly includes a clamping device 20, an injection device 30, a display input device 40, a resin pressure sensor 41, and a control device 50.

[0038] The clamping device 20 opens and closes and clamps the mold 21. Specifically, the clamping device 20 mainly includes a fixed platen 23 that supports the fixed-side mold 22, a movable platen 25 that supports the movable-side mold 24 directly above the fixed-side mold 22, and a mold opening / closing motor 61 that moves the movable platen 25 in the vertical direction.

[0039] The mold opening / closing motor 61 is a servo motor that moves the movable platen 25 in the vertical direction. The driving force of the mold opening / closing motor 61 is transmitted to the movable platen 25 through, for example, a toggle mechanism (not shown). As Figure 1As shown, when the movable platen 25 ascends, the fixed-side mold 22 separates from the movable-side mold 24. On the other hand, when the movable platen 25 descends, the fixed-side mold 22 abuts against the movable-side mold 24, forming a cavity (internal space) inside the mold 21. Moreover, when a downward pressure is further applied to the movable platen 25, the fixed-side mold 22 and the movable-side mold 24 are clamped together.

[0040] The injection device 30 plasticizes, measures, and injects the resin supplied from a hopper (not shown). The injection device 30 of the first embodiment is disposed above the clamping device 20. The injection device 30 mainly includes a heating cylinder 31, a screw 32, a conveyor 33, a fan 34, a cover 35, a nozzle contact motor 62, a metering motor 63, an injection motor 64, a conveyor advance / retreat motor 65, a conveyor drive motor 66, and a cover advance / retreat motor 67.

[0041] The heating cylinder 31 is a cylindrical member extending in the vertical direction. A nozzle hole 36a of a nozzle 36 for injecting and plasticizing the resin is formed at the front end (lower end) of the heating cylinder 31, and a supply port (not shown) for receiving the resin supplied from the hopper is formed on the base end (upper end) side of the heating cylinder 31. Moreover, a linear internal space from the supply port to the nozzle 36 is formed inside the heating cylinder 31. In addition, a belt heater (not shown) for heating the heating cylinder 31 can be installed on the outer peripheral surface of the heating cylinder 31.

[0042] The nozzle contact motor 62 is a servo motor that moves the injection device 30 in the vertical direction. The driving force of the nozzle contact motor 62 is transmitted to the injection device 30, causing the injection device 30 to move in the vertical direction between the injection position ( Figure 2A ) and the standby position ( Figures 2B to 2D ). The injection position is the position where the nozzle 36 at the front end of the heating cylinder 31 enters an opening (not shown) provided in the movable platen 25, so that the internal space of the heating cylinder 31 communicates with the cavity of the mold 21. The standby position is the position where the nozzle 36 at the front end of the heating cylinder 31 withdraws from the opening of the movable platen 25, so that the heating cylinder 31 separates from the mold 21. The standby position of the first embodiment is a position vertically above the injection position.

[0043] The screw 32 is a long rod-shaped member having a spiral groove formed on its outer peripheral surface. The screw 32 is accommodated in the internal space of the heating cylinder 31 in a state where it can advance, retreat, and rotate. The metering motor 63 is a servo motor that rotates the screw 32 inside the heating cylinder 31. The injection motor 64 is a servo motor that causes the screw 32 to advance and retreat inside the heating cylinder 31. The injection device 30 performs metering operations, injection operations, and purging operations by causing the screw 32 to advance, retreat, or rotate inside the heating cylinder 31.

[0044] The metering operation is an operation of metering a prescribed amount of plasticized resin on the front end side (nozzle 36 side) of the heating cylinder 31 by rotating the screw 32. At this time, the resin supplied to the heating cylinder 31 is plasticized by the frictional heat, shear heat generated between the heating cylinder 31 and the screw 32, and the heat generated by the belt heater. In addition, the plasticized resin moves along the spiral groove of the screw 32 to the front end side of the heating cylinder 31 and accumulates on the front end side of the heating cylinder 31. As a result, the screw 32 rotates and retreats while inside the heating cylinder 31.

[0045] The injection operation is an operation of injecting the plasticized resin metered on the front end side of the heating cylinder 31 through the nozzle 36 from the heating cylinder 31 by advancing the screw 32 when the injection device 30 is in the injection position. Thereby, the plasticized resin injected from the nozzle 36 is filled into the cavity of the mold 21.

[0046] The purging operation is an operation of discharging the plasticized resin from the heating cylinder 31 when the injection device 30 is in the standby position. The purging operation is roughly divided into a plasticizing purging operation of rotating the screw 32 to discharge the plasticized resin and an injection purging operation of advancing and retreating the screw 32 to discharge the plasticized resin.

[0047] The plasticizing purging operation is an operation of rotating the screw 32 in the direction in which the plasticized resin moves toward the nozzle 36 side in a state where the screw 32 is disposed at the position closest to the nozzle 36 (hereinafter referred to as the "most advanced position"). In the plasticizing purging operation, in order to hold the screw 32 at the most advanced position, a back pressure is applied to the screw 32 by the injection motor 64. On the other hand, the injection purging operation is an operation of discharging the plasticized resin metered on the front end side of the heating cylinder 31 from the heating cylinder 31 through the nozzle 36 by advancing the screw 32 inside the heating cylinder 31.

[0048] The conveyor 33 serves to convey the plasticized resin discharged from the heating cylinder 31 to the outside of the injection molding machine 10 when the injection device 30 is in the standby position. That is, the conveyor 33 is disposed on the discharge path (directly below the nozzle hole 36a) for discharging the plasticized resin from the heating cylinder 31 in the standby position. In addition, in order to reduce the contact area with the plasticized resin, the surface of the conveyor 33 is formed in a mesh shape.

[0049] The driving force of the conveyor advance / retreat motor 65 is transmitted to the conveyor 33, causing the conveyor 33 to move between the forward position ( Figure 2C 、 Figure 2D ) and the retracted position ( Figure 2A 、 Figure 2B). The forward position is a position where the conveying surface (upper surface) of the conveyor 33 is arranged directly below the nozzle 36 (nozzle hole 36a) at the front end of the heating cylinder 31 in the standby position. The retracted position is a position where the conveyor 33 leaves the moving path of the heating cylinder 31. The forward position and the retracted position are the conveying direction (i.e., the conveying direction) in which the conveyor 33 conveys the plasticized resin. Figures 2A to 2D That is, the conveyor 33 moves forward and backward along the conveying direction of the plasticized resin.

[0050] When the conveyor 33 is in the forward position, the plasticized resin discharged from the nozzle 36 (nozzle hole 36a) at the front end of the heating cylinder 31 in the standby position reaches the conveying surface of the conveyor 33, and the injection device 30 (heating cylinder 31) cannot move from the standby position to the injection position. On the other hand, when the conveyor 33 is in the retreat position, the plasticized resin discharged from the nozzle 36 (nozzle hole 36a) at the front end of the heating cylinder 31 in the standby position does not reach the conveying surface of the conveyor 33, and the injection device 30 (heating cylinder 31) can move between the injection position and the standby position.

[0051] In addition, the driving force of the conveyor drive motor 66 is transmitted to the conveyor 33, so that the conveyor 33 is moved in a direction to discharge the plasticized resin reaching the conveying surface to the outside of the injection molding machine 10 ( Figures 2A to 2D The conveyor 33 may be configured to be able to switch the conveying speed. The conveyor 33 of the first embodiment may be able to switch between at least a first conveying speed and a second conveying speed. The first conveying speed is a speed faster than the second conveying speed.

[0052] The fan 34 is a cooling device that cools the plasticized resin conveyed on the conveyor 33. Specifically, the fan 34 blows air toward the conveying surface of the conveyor 33. In addition, the fan 34 is fixed at a predetermined position of the conveyor 33. That is, the fan 34 moves forward and backward integrally with the conveyor 33 that moves between the forward position and the retreat position. In addition, the air supply speed (air supply volume per unit time) of the fan 34 can be switched in conjunction with the conveying speed of the conveyor 33.

[0053] The cap 35 abuts against the front end of the heating cylinder 31 in the standby position, playing the role of blocking the nozzle 36. The cap advance / retract motor 67 is a servo motor that moves the cap 35 forward and backward. The driving force of the cap advance / retract motor 67 is transmitted to the cap 35, so that the cap 35 is in the blocking position ( Figure 2D ) and the opening position ( Figures 2A to 2C ) to move forward and backward.

[0054] like Figures 2A to 2DAs shown, the injection device 30 has a heating cylinder 31, a conveyor 33, and a box body 37 that houses a cover 35. The box body 37 has slits 37a, 37b, and 37c through which the heating cylinder 31, the conveyor 33, and the cover 35 pass respectively. That is, the heating cylinder 31, the conveyor 33, and the cover 35 pass through the slits 37a, 37b, and 37c and advance and retreat with respect to the internal space of the box body 37.

[0055] In addition, the nozzle 36 at the front end of the heating cylinder 31 is always located in the internal space of the box body 37. Thereby, it is possible to prevent an operator from touching the plasticized resin injected from the nozzle 36. However, the box body 37 may have a door (not shown) or the like for maintenance to expose the internal space.

[0056] The display input device 40 is a user interface and has a display screen for displaying various information that should be informed to the operator, and buttons, switches, a numeric keypad, etc. for accepting the operations of the operator. In addition, the display input device 40 may have a touch panel overlapping the display screen. The display input device 40 accepts, for example, an operation for instructing the operator to start the injection operation and an operation for instructing the operator to start the cleaning operation, and outputs an operation signal corresponding to the accepted operation to the control device 50.

[0057] The resin pressure sensor 41 detects the resin pressure in the heating cylinder 31 and outputs a detection signal showing the detection result to the control device 50. The resin pressure is the pressure applied to the plasticized resin metered in the space in front of the screw 32 in the heating cylinder 31. The resin pressure sensor 41 can, for example, detect the pressure applied to the screw 32 and use it as the resin pressure.

[0058] The control device 50 controls the operation of the injection molding machine 10 as a whole. The control device 50 acquires the operation signal output from the display input device 40, the detection signal output from the resin pressure sensor 41, and the encoded signal output from the encoders (not shown) of the respective motors 61 to 67. Moreover, the control device 50 drives the respective motors 61 to 67 and the fan 34 based on the various signals acquired.

[0059] The control device 50 has, for example, a CPU (Central Processing Unit) 51 as an arithmetic unit, a ROM (Read-Only Memory) 52 that stores various programs, and a RAM (Random Access Memory) 53 as a working area of the arithmetic unit. Moreover, the respective processes described later can be implemented by the CPU 51 reading and executing the programs stored in the ROM 52.

[0060] However, the specific structure of the control device 50 is not limited to this and can be implemented by hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array).

[0061] Next, with reference to Figure 4 , the operation of the injection molding machine 10 of the first embodiment will be described. Figure 4 is a flowchart of the cleaning control process of the first embodiment. The cleaning control process starts when the injection molding machine 10 receives a cleaning instruction from the outside. In addition, at the start time of the cleaning control process, the injection device 30 is in the standby position, the conveyor 33 is in the retracted position, and the cover 35 is in the open position.

[0062] The cleaning instruction can be, for example, instructed by an operator via the display input device 40, the execution timing of the cleaning operation can be preset in the control device 50 in advance, or it can be received from an external device via a communication interface (not shown).

[0063] The cleaning instructions are roughly divided into "drip tray cleaning" for discharging the plasticized resin from the drip tray (not shown) and "conveyor cleaning" for discharging the plasticized resin from the conveyor 33. The drip tray is a container that can be installed and removed by the operator on the discharge path of the plasticized resin discharged from the heating cylinder 31 in the standby position (i.e., below the heating cylinder 31).

[0064] First, the control device 50 determines the type of the received cleaning instruction (S11). When the control device 50 determines that the cleaning instruction is "drip tray cleaning" (S11: drip tray), it causes the heating cylinder 31 to discharge the plasticized resin at the first discharge speed (S12). That is, in step S12, the control device 50 executes a plasticizing cleaning operation or an injection cleaning operation. A method of adjusting the discharge speed by the plasticizing cleaning operation and the injection cleaning operation will be described later.

[0065] On the other hand, when the control device 50 determines that the cleaning instruction is "conveyor cleaning" (S11: conveyor), it obtains a detection signal representing the resin pressure at that time from the resin pressure sensor 41 (S13). Then, the control device 50 compares the resin pressure detected by the resin pressure sensor 41 with a threshold value (S14). The threshold value is stored in the ROM 52 in advance.

[0066] When the control device 50 determines that the resin pressure is equal to or higher than the threshold value (S14: Yes), it sets the discharge speed of the plasticized resin discharged from the heating cylinder 31 to the second discharge speed (S15). On the other hand, when the control device 50 determines that the resin pressure is lower than the threshold value (S14: No), it sets the discharge speed of the plasticized resin discharged from the heating cylinder 31 to the third discharge speed (S16).

[0067] Here, the first discharge speed, the second discharge speed, and the third discharge speed are the speeds of the plasticized resin passing through the nozzle 36. That is, the first to third discharge speeds are speeds that do not depend on the method of discharging the plasticized resin (plasticizing cleaning operation, injection cleaning operation). Moreover, the second discharge speed is slower than the first discharge speed. In addition, the third discharge speed is slower than the second discharge speed.

[0068] Next, the control device 50 moves the conveyor 33 from the standby position to the forward position and adjusts the conveying speed of the conveyor 33 in accordance with the discharge speeds set in steps S15 and S16 (S17). That is, when the second discharge speed is set, the control device 50 drives the conveyor 33 at the first conveying speed, and when the third discharge speed is set, the control device 50 drives the conveyor 33 at the second conveying speed. The relationship between the discharge speed and the conveying speed is stored in the ROM 52 in advance.

[0069] Next, the control device 50 performs a plasticizing cleaning operation at the discharge speeds set in steps S15 and S16 (S18). In the plasticizing cleaning operation, the discharge speed can be adjusted by increasing or decreasing the rotational speed of the screw 32. That is, the control device 50 supplies a current corresponding to the discharge speed set in steps S15 and S16 to the metering motor 63. The relationship between the discharge speed and the current value is stored in the ROM 52 in advance.

[0070] The control device 50 calculates the number of rotations of the screw 32 during the plasticizing cleaning operation, and continues the plasticizing cleaning operation (S18) until the calculated number of rotations reaches the threshold number of rotations (S19: No). Moreover, when the calculated number of rotations reaches the threshold number of rotations (S19: Yes), the control device 50 causes the screw 32 to suck back (S20).

[0071] "Suck back" is a process of retracting the screw 32 in the heating cylinder 31. That is, the control device 50 drives the injection motor 64 in the direction in which the screw 32 retracts. As a result, the space on the nozzle 36 side at the front end of the screw 32 becomes negative pressure, and the discharge of the plasticized resin from the nozzle 36 stops.

[0072] Next, the control device 50 determines whether a predetermined amount of plasticized resin has been discharged (S21). For example, the control device 50 determines the amount of plasticized resin discharged by the plasticizing cleaning operation by multiplying the discharge speed set in steps S15 and S16 by the execution time of step S18.

[0073] Then, when the control device 50 determines that the predetermined amount of plasticized resin has not been discharged (S21: No), the control device 50 executes the processing after step S18 again. On the other hand, when the control device 50 determines that the predetermined amount of plasticized resin has been discharged (S21: Yes), the cleaning control process ends.

[0074] According to the first embodiment, for example, the following effects are achieved.

[0075] According to the first embodiment, it is possible to select "catch tray cleaning" in which the operator needs to place and remove the catch tray, and "conveyor cleaning" in which the plasticized resin can be automatically discharged by the conveyor 33. As a result, the operation burden on the operator for disassembling and assembling the catch tray and the like during the cleaning operation can be reduced.

[0076] In addition, if the plasticized resin is strongly discharged by conveyor cleaning, the plasticized resin reaching the surface of the conveyor 33 may fly outside the conveyor 33, or may enter the inside of the conveyor 33 through the gaps in the mesh holes. The scattering or intrusion of the plasticized resin increases the burden on the operator for maintaining the injection molding machine 10. Therefore, as in the first embodiment, by making the second discharge speed and the third discharge speed in conveyor cleaning slower than the first discharge speed in catch tray cleaning, conveyor cleaning can be achieved well without increasing the maintenance burden.

[0077] In addition, the case where the resin pressure is above the threshold value (S14: Yes) means that the viscosity of the plasticized resin in the heating cylinder 31 is high to a certain extent. Therefore, the possibility of the plasticized resin reaching the conveyor 33 flying or intruding is low. On the other hand, the case where the resin pressure is less than the threshold value (S14: No) means that the viscosity of the plasticized resin in the heating cylinder 31 is low. Therefore, the possibility of the plasticized resin reaching the conveyor 33 flying or intruding is high.

[0078] Therefore, as in the first embodiment, by adjusting the discharge speed according to the resin pressure (in other words, the viscosity of the plasticized resin), it is possible to balance maintaining the productivity of the cleaning operation and reducing the maintenance burden. In addition, the parameter for estimating the viscosity of the plasticized resin is not limited to the resin pressure, and may be the elapsed time after supplying the plasticized resin into the heating cylinder 31 or the like.

[0079] In addition, the plasticized resin that reaches the conveyor 33 solidifies into a rod shape and is discharged. Therefore, if the purging operation is continued for a long time, the rod-shaped plasticized resin becomes longer and is difficult to handle. Thus, as in the first embodiment, every time the number of rotations of the screw 32 reaches the threshold number of rotations, the screw 32 is retracted, whereby a plurality of plasticized resins that are divided short can be discharged from the conveyor 33.

[0080] In addition, the timing for retracting the screw 32 is not limited to the example of step S19. As another example, the control device 50 may retract the screw 32 at the timing when a predetermined time has elapsed after starting the plasticizing purging operation. That is, the control device 50 may retract the screw 32 at regular intervals during the conveyor purging.

[0081] In addition, the method of dividing the rod-shaped plasticized resin discharged from the conveyor 33 is not limited to the retraction of the screw 32. As another example, the control device 50 may move the lid 35 from the open position to the blocking position at regular intervals during the conveyor purging. Further, as another example, the injection molding machine 10 may have a cutter that cuts the rod-shaped plasticized resin conveyed on the conveyor 33 at regular intervals.

[0082] (Second Embodiment)

[0083] Next, with reference to Figure 5 , the operation of the injection molding machine 10 of the second embodiment will be described. Figure 5 is a flowchart of the purging control process of the second embodiment. The hardware configuration of the injection molding machine 10 of the second embodiment is common to that of the first embodiment.

[0084] The control device 50 of the second embodiment executes Figure 5 the processes of steps S31 to S40 in place of Figure 4 the processes of steps S13 to S21. In addition, at the start time of the purging control process of the second embodiment, the injection device 30 is in the standby position, the conveyor 33 is in the retracted position, and the lid 35 is in the blocked position.

[0085] When the control device 50 of the second embodiment determines that the purging instruction is "conveyor purging" (S11: conveyor), it discharges the plasticized resin from the nozzle 36 at a discharge speed set according to the current resin pressure (S31 to S34). In addition, the control device 50 moves the conveyor 33 from the standby position to the forward position and adjusts the conveying speed of the conveyor 33 in accordance with the discharge speed set in steps S33 and S34 (S35). The processes of steps S31 to S35 are common to Figure 4 the processes of steps S13 to S17.

[0086] Next, the control device 50 moves the lid 35 from the blocking position to the open position (S36). Next, the control device 50 performs an injection cleaning operation at the discharge speed set in steps S33 and S34 (S37). The discharge speed can be adjusted during the injection cleaning operation by increasing or decreasing the forward speed of the screw 32. That is, the control device 50 can supply a current of a magnitude corresponding to the discharge speed set in steps S33 and S34 to the injection motor 64. The relationship between the discharge speed and the current value is stored in the ROM 52 in advance.

[0087] Next, the control device 50 determines whether a predetermined amount of plasticized resin has been discharged (S38). The control device 50 can, for example, determine the amount of plasticized resin discharged during the injection cleaning operation by multiplying the discharge amount of the plasticized resin in each injection cleaning operation by the number of executions of step S37.

[0088] Then, when the control device 50 determines that the predetermined amount of plasticized resin has not been discharged (S38: No), it moves the lid 35 from the open position to the blocking position (S39), causes the injection device 30 to perform a metering operation (S40), and then repeats the processing after step S31 again. That is, the control device 50 intermittently discharges the plasticized resin by repeatedly performing the process of detecting the resin pressure by the resin pressure sensor 41 (S31) and the process of advancing the screw 32 at a speed corresponding to the detected resin pressure (S32 to S37). On the other hand, when the control device 50 determines that the predetermined amount of plasticized resin has been discharged (S38: Yes), it ends the cleaning control process.

[0089] The viscosity of the plasticized resin has the following tendency: the longer the residence time in the heating cylinder 31, the lower the viscosity; the shorter the residence time, the higher the viscosity. That is, the viscosity of the plasticized resin already in the heating cylinder 31 at the start of the cleaning control process becomes relatively low, and the viscosity of the newly supplied plasticized resin into the heating cylinder 31 during the cleaning control process becomes relatively high.

[0090] Therefore, as in the second embodiment, each time the screw 32 is advanced, the resin pressure is detected and an appropriate forward speed is set. As a result, the third discharge speed is selected for the first half of the multiple injections, and the second discharge speed is selected for the second half. This can balance maintaining the productivity of the cleaning operation and reducing the maintenance burden.

[0091] (Third Embodiment)

[0092] Next, referring to Figure 6 and Figure 7A 、 Figure 7B , the injection molding machine 10A of the third embodiment will be described. Figure 6 is a side view showing the schematic structure of the injection molding machine 10A. Figure 7A 、Figure 7B This is a front view observed from the front end side of the heating cylinder 31. In addition, structural components that perform the same functions as those in the first embodiment are labeled with the same reference numerals in the drawings, and detailed descriptions thereof are omitted.

[0093] The injection molding machine 10A of the third embodiment is a so-called "horizontal" injection molding machine in which the injection device 30 (heating cylinder 31) moves horizontally between an injection position and a standby position separated in the horizontal direction. That is, the difference between the injection molding machine 10A of the third embodiment and the injection molding machine 10 of the first embodiment is that the positional relationship of the main component parts 22 to 25 and 31 to 32 is reversed by 90°.

[0094] In addition, the injection molding machine 10A of the third embodiment has a guide plate 38 instead of the cover 35. However, the injection molding machine 10A may also have a cover 35. The guide plate 38 serves to guide the plasticized resin discharged from the heating cylinder 31 through the purging operation to the conveying surface of the conveyor 33. The driving force of a guide plate advancing / retreating motor (not shown) is transmitted to the guide plate 38, causing the guide plate 38 to move between a retracted position ( Figure 7A ) and a guiding position ( Figure 7B ).

[0095] The retracted position is a position that is out of the movement path of the heating cylinder 31. The guiding position is a position on the movement path of the heating cylinder 31. That is, when the guide plate 38 is in the retracted position, the plasticized resin discharged from the heating cylinder 31 in the standby position does not reach the guide plate 38, and the injection device 30 (heating cylinder 31) can move between the standby position and the injection position. On the other hand, when the guide plate 38 is in the guiding position, the plasticized resin discharged from the heating cylinder 31 in the standby position reaches the guide plate 38, and the injection device 30 (heating cylinder 31) cannot move from the standby position to the injection position.

[0096] Moreover, the conveyor 33 of the third embodiment is fixed directly below the nozzle 36 at the front end of the heating cylinder 31 in the standby position and directly below the guide plate 38 in the guiding position. That is, both the plasticized resin that leaks out little by little from the heating cylinder 31 in the standby position and the plasticized resin that is strongly discharged from the heating cylinder 31 in the standby position and reaches the guide plate 38 reach the conveying surface of the conveyor 33 and are conveyed to the outside of the injection molding machine 10A.

[0097] The injection molding machine 10A of the third embodiment executes Figure 4 or Figure 5The purging control process shown. However, in addition, after the control device 50 of the third embodiment moves the injection device 30 (heating cylinder 31) from the injection position to the standby position, it moves the guide plate 38 from the retracted position to the guiding position. Moreover, before the control device 50 of the third embodiment moves the injection device 30 (heating cylinder 31) from the standby position to the injection position, it moves the guide plate 38 from the guiding position to the retracted position.

[0098] According to the third embodiment, the plasticized resin forcefully discharged from the nozzle 36 at the front end of the heating cylinder 31 by the purging operation hits the guide plate 38 in the guiding position and is guided to the conveying surface of the conveyor 33. As a result, in the horizontal injection molding machine 10A, the plasticized resin discharged by the purging operation can be reliably and efficiently discharged to the outside of the injection molding machine 10A through the conveyor 33.

Claims

1. An injection molding machine that injects plasticized resin into a mold to manufacture injection molded products, characterized in that: It has: A heating cylinder, and a nozzle formed at its front end moves between an injection position and a standby position. The injection position is the position where the heating cylinder communicates with the cavity of the mold, and the standby position is the position where the heating cylinder is separated from the mold. A conveyor is arranged on the discharge path for discharging the plasticized resin from the heating cylinder in the standby position, and conveys the plasticized resin discharged from the nozzle to the outside of the injection molding machine, and A control device that controls the operations of the heating cylinder and the conveyor; When the control device is instructed to perform a receiving tray cleaning operation for discharging the plasticized resin from the receiving tray, the heating cylinder in the standby position discharges the plasticized resin at a first discharge speed. The receiving tray is arranged on the discharge path for discharging the plasticized resin from the heating cylinder in the standby position. When the control device is instructed to perform a conveyor cleaning operation for discharging the plasticized resin from the conveyor, the heating cylinder in the standby position discharges the plasticized resin at a second discharge speed slower than the first discharge speed. The control device can select the receiving tray cleaning operation and the conveyor cleaning operation according to the cleaning instruction. The injection molding machine has a resin pressure sensor for detecting the resin pressure applied to the plasticized resin in the heating cylinder. When the control device is instructed to perform the conveyor cleaning operation, it adjusts the discharge speed of the plasticized resin according to the resin pressure detected by the resin pressure sensor.

2. The injection molding machine according to claim 1, characterized in that: When the control device is instructed to perform the conveyor cleaning operation, When the resin pressure detected by the resin pressure sensor is above the threshold value, the heating cylinder in the standby position discharges the plasticized resin at the second discharge speed. When the resin pressure detected by the resin pressure sensor is less than the threshold value, the heating cylinder in the standby position discharges the plasticized resin at a third discharge speed slower than the second discharge speed.

3. The injection molding machine according to claim 2, characterized in that: The injection molding machine has a screw that can move forward, backward and rotate in the heating cylinder. When the control device is instructed to perform the conveyor cleaning operation, it rotates the screw arranged at the position closest to the nozzle in the direction that makes the plasticized resin move toward the nozzle side, thereby discharging the plasticized resin from the nozzle. The discharge speed of the plasticized resin is adjusted by increasing or decreasing the rotation speed of the screw.

4. The injection molding machine according to claim 3, characterized in that, The control device retracts the screw at regular intervals during the conveyor cleaning operation.

5. The injection molding machine according to claim 1, characterized in that: The injection molding machine has a screw that can move forward, backward and rotate in the heating cylinder. When the control device is instructed to perform the conveyor cleaning operation, it intermittently discharges the plasticized resin by moving the screw forward and backward.

6. The injection molding machine according to claim 5, characterized in that when the control device is instructed to perform the conveyor cleaning, the process of detecting the resin pressure by the resin pressure sensor and advancing the screw at a speed corresponding to the detected resin pressure is repeatedly executed.

7. The injection molding machine according to any one of claims 2 to 6, characterized in that, when the control device is instructed to perform the conveyor cleaning, the conveying speed of the conveyor is adjusted according to the discharge speed of the plasticized resin discharged from the heating cylinder.

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