CN112536973A

CN112536973A - Injection molding machine

Info

Publication number: CN112536973A
Application number: CN202010992474.4A
Authority: CN
Inventors: 樽家宏治; 中田匡英
Original assignee: Toyo Machinery and Metal Co Ltd
Current assignee: Toyo Machinery and Metal Co Ltd
Priority date: 2019-09-20
Filing date: 2020-09-21
Publication date: 2021-03-23
Also published as: JP2021049649A; JP7256720B2

Abstract

The invention provides an injection molding machine which reduces the operation burden of an operator in the cleaning operation. An injection molding machine is provided, wherein when execution of a tray purge for discharging plasticized resin from a tray is instructed (S11: tray), a heating cylinder at a standby position is caused to discharge plasticized resin at a first discharge speed (S12), the tray is provided on a discharge path for discharging plasticized resin from the heating cylinder at the standby position, and when execution of a conveyor purge for discharging plasticized resin from a conveyor is instructed (S11: conveyor), the heating cylinder at the standby position is caused to discharge plasticized resin at a second discharge speed slower than the first discharge speed (S18).

Description

Injection molding machine

Technical Field

The present invention relates to an injection molding machine that injects a plasticized resin into a mold to mold an injection-molded product.

Background

Patent document 1 discloses a vertical injection molding machine having a heating cylinder that moves up and down between a contact position where the heating cylinder contacts a resin injection hole of a mold and a retreat limit position above the contact position. Patent document 1 describes that a purging operation for discharging the plasticized resin in the heating cylinder is performed.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2012-153110

Disclosure of Invention

Problems to be solved by the invention

In the injection molding machine described in patent document 1, the operator needs to place the receiving tray for receiving the plasticized resin directly below the heating cylinder before performing the cleaning operation and remove the receiving tray from the positioning portion before performing the injection molding again. In addition, when the amount of the plasticized resin discharged by the purge operation is large, the operator needs to remove the plasticized resin in the receiving tray in the middle of the purge operation.

Therefore, the injection molding machine having the above-described configuration has a problem in that the operation load of the operator is large when the machine cleaning operation is performed. Further, this problem occurs not only in a vertical injection molding machine but also in a horizontal injection molding machine in which the heating cylinder moves in the horizontal direction.

The present invention has been made to solve the above-described problems of the prior art, and an object thereof is to provide an injection molding machine that reduces the operation load on the operator during the cleaning operation.

Means for solving the problems

In order to solve the above problems, the present invention provides an injection molding machine for producing an injection molded product by injecting a plasticized resin into a mold, the injection molding machine comprising: a heating cylinder having a nozzle formed at a distal end thereof, the nozzle being moved between an injection position where the heating cylinder communicates with a cavity of the mold and a standby position where the heating cylinder is separated from the mold, a conveyor disposed on a discharge path through which the plasticized resin is discharged from the heating cylinder at the standby position, the conveyor transporting the plasticized resin discharged from the nozzle to an outside of the injection molding machine, and a control device controlling operations of the heating cylinder and the conveyor; the control device causes the heating cylinder in the standby position to discharge plasticized resin at a first discharge speed when instructed to execute a ladle purge for causing the ladle to discharge the plasticized resin, the ladle being provided on a discharge path for discharging the plasticized resin from the heating cylinder in the standby position, and causes the heating cylinder in the standby position to discharge the plasticized resin at a second discharge speed slower than the first discharge speed when instructed to execute a conveyor purge for causing the conveyor to discharge the plasticized resin.

According to the above structure, "the tray cleaner" that requires the placement and the removal of the tray by the operator and "the conveyor cleaner" that can automatically discharge the plasticized resin by the conveyor can be selected. As a result, the burden of the operator for attaching and detaching the tray during the machine cleaning operation can be reduced.

Further, if the plasticized resin is forcibly discharged by the conveyor cleaner, the plasticized resin reaching the surface of the conveyor may scatter outside the conveyor or may enter the interior of the conveyor. Further, the scattering or intrusion of the plasticized resin increases the burden on the operator who maintains the injection molding machine. Therefore, as in the above configuration, by making the discharge speed in the conveyor cleaner slower than the discharge speed in the tray cleaner, the conveyor cleaner can be favorably realized without increasing the maintenance load.

In the injection molding machine according to the present invention, the injection molding machine may include a resin pressure sensor that detects a resin pressure applied to the plasticized resin in the heating cylinder, and the control device may cause the heating cylinder in the standby position to discharge the plasticized resin at the second discharge speed when the resin pressure detected by the resin pressure sensor is equal to or higher than a threshold value when the execution of the conveyor purge is instructed, and cause the heating cylinder in the standby position to discharge the plasticized resin at a third discharge speed slower than the second discharge speed when the resin pressure detected by the resin pressure sensor is lower than the threshold value.

The case where the resin pressure is equal to or higher than the threshold value means a state where the viscosity of the plasticized resin in the heating cylinder is high to some extent. Therefore, the plasticized resin reaching the conveyor is less likely to scatter or intrude. On the other hand, the case where the resin pressure is less than the threshold value means a state where the viscosity of the plasticized resin in the heating cylinder is low. Therefore, the plasticized resin reaching the conveyor is highly likely to scatter or intrude. Therefore, as in the above configuration, by adjusting the discharge speed in accordance with the resin pressure (in other words, the viscosity of the plasticized resin), it is possible to achieve both the productivity of maintaining the purge operation and the reduction of the maintenance load.

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 a heating cylinder, and the control device may discharge the plasticized resin from the nozzle by rotating the screw disposed at a position closest to the nozzle in a direction in which the plasticized resin is moved to the nozzle side when the conveyor purge is instructed to be executed, and adjust a discharge speed of the plasticized resin by increasing or decreasing a rotation speed of the screw.

In the injection molding machine according to the present invention, the control device may retract the screw at predetermined intervals during the cleaning of the conveyor.

The plasticized resin that has reached the conveyor solidifies in a rod-like shape and is discharged. Therefore, if the plasticized resin is continuously discharged for a long time, the rod-shaped plasticized resin becomes long, and it becomes difficult to handle. Therefore, as in the above-described configuration, by retracting the screw at predetermined intervals, the space on the nozzle side of the screw in the heating cylinder is made negative pressure, and the discharge of the plasticized resin is temporarily stopped. As a result, the plurality of short divided plasticized resins can be discharged from the conveyor.

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 a heating cylinder, and the control device intermittently discharges the plasticized resin by advancing and retreating the screw when instructed to perform the conveyor purge.

In the injection molding machine according to the present invention, the injection molding machine may include a resin pressure sensor that detects a resin pressure applied to the plasticized resin in the heating cylinder, and the control device may repeat, when the execution of the conveyor purge is instructed, a process of detecting the resin pressure by the resin pressure sensor and advancing the screw at a speed corresponding to the detected resin pressure.

The viscosity of the plasticized resin tends to be lower as the residence time in the heating cylinder is longer, and higher as the residence time is shorter. That is, the viscosity of the plasticized resin already in the heating cylinder at the start time of the purging operation becomes relatively low, and the viscosity of the plasticized resin newly supplied into the heating cylinder during the purging operation becomes relatively high. Therefore, as in the above configuration, the resin pressure is detected every time the screw is advanced, and an appropriate advance speed is set, whereby it is possible to achieve both maintenance of the productivity of the cleaning operation and reduction of the maintenance load.

In the injection molding machine according to the present invention, the control device may adjust the conveying speed of the conveyor in accordance with a discharge speed of the plasticized resin from the heating cylinder when the execution of the cleaning of the conveyor is instructed.

According to the above configuration, the plasticized resin discharged by the purge operation can be favorably discharged to the outside of the injection molding machine.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, since the tray cleaner and the conveyor cleaner can be switched according to the situation, the operation load of the operator during the cleaning operation can be reduced. Further, by making the discharge speed in the conveyor cleaner slower than that in the tray cleaner, the conveyor cleaner can be favorably realized without increasing the maintenance load.

Drawings

Fig. 1 is a front view of an injection molding machine of a first embodiment.

Fig. 2A to 2D are enlarged schematic views of the injection device.

Fig. 3 is a hardware block diagram of an injection molding machine.

Fig. 4 is a flowchart of the purge control processing of the first embodiment.

Fig. 5 is a flowchart of the purge control processing of the second embodiment.

Fig. 6 is a side view showing a schematic configuration of an injection molding machine according to a third embodiment.

Fig. 7A and 7B are front views of the heating cylinder of the third embodiment as viewed from the front end side.

Description of the reference numerals

10. 10a … injection molding machine, 20 … mold clamping device, 21 … mold, 22 … fixed mold, 23 … fixed mold plate, 24 … movable mold, 25 … movable mold plate, 30 … injection device, 31 … heating cylinder, 32 … screw, 33 … conveyor, 34 … fan (cooling device), 35 … cover, 36 … nozzle, 36a … nozzle hole, 37 … box, 37a, 37b, 37c … slit, 38 … guide plate, 40 … display input device, 41 … resin pressure sensor, 50 … control device, 51 … CPU, 52 … ROM, 53 … RAM, 61 … mold opening and closing motor, 62 … nozzle contact motor, 63 … metering motor, 64 … injection motor, 65 … conveyor motor, 66 … conveyor driving motor, 67 cap advancing and retracting motor 67 ….

Detailed Description

The injection molding machine 10 of the present invention is explained below based on the drawings. The embodiments of the present invention described below are merely examples of embodying the present invention, and the scope of the present invention is not limited to the described scope of the embodiments. Therefore, the present invention can be implemented with various modifications to the embodiments.

(first embodiment)

Fig. 1 is a front view of an injection molding machine 10 of a first embodiment. Fig. 2A to 2D are enlarged schematic views of the injection device 30. Fig. 3 is a hardware block diagram of the injection molding machine 10. The injection molding machine 10 is a device for injecting a plastic resin into a mold to mold an injection molded product. The injection molding machine 10 of the first embodiment is a so-called "vertical" injection molding machine. As shown in fig. 1 to 3, the injection molding machine 10 mainly includes a mold clamping device 20, an injection device 30, a display and input device 40, a resin pressure sensor 41, and a control device 50.

The mold clamping device 20 opens and closes and clamps the mold 21. Specifically, the mold 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.

The mold opening and closing motor 61 is a servomotor that moves the movable platen 25 in the vertical direction. The driving force of the mold opening and closing motor 61 is transmitted to the movable platen 25 through, for example, a toggle mechanism (not shown). As shown in fig. 1, when the movable die plate 25 rises, the fixed die 22 is separated from the movable die 24. On the other hand, when the movable die plate 25 is lowered, the fixed die 22 abuts against the movable die 24, and a cavity (internal space) is formed inside the die 21. When downward pressure is further applied to the movable die plate 25, the fixed die 22 and the movable die 24 are clamped.

The injection device 30 plasticizes, meters, and injects the resin supplied from a hopper (not shown). The injection device 30 of the first embodiment is disposed above the mold clamping device 20. The injection device 30 mainly has a heating cylinder 31, a screw 32, a conveyor 33, a fan 34, a cap 35, a nozzle contact motor 62, a metering motor 63, an injection motor 64, a conveyor advancing and retreating motor 65, a conveyor drive motor 66, and a cap advancing and retreating motor 67.

The heating cylinder 31 is a cylindrical member extending in the vertical direction. A nozzle hole 36a of a nozzle 36 for injecting plasticized resin is formed at the tip (lower end) of the heating cylinder 31, and a supply port (not shown) for receiving resin supplied from the hopper is formed on the base end (upper end) side of the heating cylinder 31. Further, a linear inner space from the supply port to the nozzle 36 is formed inside the heating cylinder 31. A belt heater (not shown) for heating the heating cylinder 31 may be attached to the outer peripheral surface of the heating cylinder 31.

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, and the injection device 30 is moved in the vertical direction between the injection position (fig. 2A) and the standby position (fig. 2B to 2D). The injection position is a position where the nozzle 36 at the tip of the heating cylinder 31 enters an opening (not shown) provided in the movable die plate 25, and the internal space of the heating cylinder 31 communicates with the cavity of the mold 21. The standby position is a position where the nozzle 36 at the tip of the heating cylinder 31 is retracted from the opening of the movable die plate 25, and the heating cylinder 31 is separated from the mold 21. The standby position in the first embodiment is a position vertically above the injection position.

The screw 32 is a long rod-shaped member having a spiral groove formed on an outer peripheral surface thereof. The screw 32 is accommodated in an inner space of the heating cylinder 31 in a state capable of advancing, retreating, and rotating. The metering motor 63 is a servomotor that rotates the screw 32 in the heating cylinder 31. The injection motor 64 is a servo motor that advances and retreats the screw 32 in the heating cylinder 31. The injection device 30 performs a metering operation, an injection operation, and a purge operation by advancing, retreating, or rotating the screw 32 in the heating cylinder 31.

The metering operation is an operation of metering a predetermined amount of the plasticized resin on the tip 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 frictional heat, shear heat, and heat generated by the belt heater, which are generated between the heating cylinder 31 and the screw 32. The plasticized resin moves to the distal end side of the heating cylinder 31 along the spiral groove of the screw 32 and accumulates on the distal end side of the heating cylinder 31. As a result, the screw 32 moves backward while rotating in the heating cylinder 31.

The injection operation is an operation of injecting the plasticized resin metered to the distal end side of the heating cylinder 31 from the heating cylinder 31 through the nozzle 36 by advancing the screw 32 when the injection device 30 is located at the injection position. Thereby, the plasticized resin injected from the nozzle 36 is filled into the cavity of the mold 21.

The purge operation is an operation of discharging the plasticized resin from the heating cylinder 31 when the injection device 30 is located at the standby position. The purging operation is roughly divided into a plasticizing purging operation for discharging the plasticized resin by rotating the screw 32 and an injection purging operation for discharging the plasticized resin by advancing and retreating the screw 32.

The plasticizing purge operation is an operation of rotating the screw 32 in a direction to move the plasticized resin toward the nozzle 36 while the screw 32 is disposed at a position closest to the nozzle 36 (hereinafter referred to as "most advanced position"). In the plasticizing purge operation, back pressure is applied to the screw 32 by the injection motor 64 in order to hold the screw 32 in the most advanced position. On the other hand, the injection purge operation is an operation of discharging the plasticized resin metered to the tip side of the heating cylinder 31 from the heating cylinder 31 through the nozzle 36 by advancing the screw 32 in the heating cylinder 31.

The conveyor 33 functions 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 located at the standby position. That is, the conveyor 33 is disposed on a discharge path (directly below the nozzle hole 36a) through which the plasticized resin is discharged 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 becomes mesh-like.

The driving force of the conveyor advancing-retreating motor 65 is transmitted to the conveyor 33, and the conveyor 33 is advanced and retreated between the advanced position (fig. 2C, 2D) and the retreat position (fig. 2A, 2B). The forward position is a position where the conveyance surface (upper surface) of the conveyor 33 is disposed directly below the nozzle 36 (nozzle hole 36a) at the front end of the heating cylinder 31 in the standby position. The retreat position is a position where the conveyor 33 is away from the moving path of the heating cylinder 31. The forward position and the retreat position are positions separated in the conveying direction (i.e., the left-right direction in fig. 2A to 2D) in which the conveyor 33 conveys the plasticized resin. That is, the conveyor 33 advances and retreats in the conveying direction of the plasticized resin.

When the conveyor 33 is located at the forward position, the plasticized resin discharged from the nozzle 36 (nozzle hole 36a) at the tip of the heating cylinder 31 located at the standby position reaches the conveyance 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 located at the retreat position, the plasticized resin discharged from the nozzle 36 (nozzle hole 36a) at the tip of the heating cylinder 31 located at the standby position does not reach the conveyance surface of the conveyor 33, and the injection device 30 (heating cylinder 31) can move between the injection position and the standby position.

Further, the driving force of the conveyor driving motor 66 is transmitted to the conveyor 33, and the conveyor 33 is rotated in a direction (counterclockwise direction in fig. 2A to 2D) in which the plasticized resin reaching the conveying surface is discharged to the outside of the injection molding machine 10. The conveyor 33 may be configured to be capable of switching the conveyance speed. The conveyor 33 according to the first embodiment can be switched to at least a first conveyance speed and a second conveyance speed. The first conveyance speed is faster than the second conveyance speed.

The fan 34 is a cooling device that functions to cool the plasticized resin conveyed on the conveyor 33. Specifically, the fan 34 blows air toward the conveying surface of the conveyor 33. The fan 34 is fixed to 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 retracted position. The blowing speed of the fan 34 (blowing amount per unit time) can be switched in conjunction with the conveying speed of the conveyor 33.

The cap 35 abuts on the front end of the heating cylinder 31 in the standby position, and functions to close the nozzle 36. The lid advancing and retracting motor 67 is a servo motor that advances and retracts the lid 35. The driving force of the cap advancing-retracting motor 67 is transmitted to the cap 35, and the cap 35 is advanced and retreated between a closing position (fig. 2D) at which the nozzle 36 is closed and an opening position (fig. 2A to 2C) at which the nozzle 36 is opened.

As shown in fig. 2A to 2D, the injection device 30 includes a heating cylinder 31, a conveyor 33, and a case 37 accommodating a cover 35. The box 37 has

slits

37a, 37b, and 37c through which the heating cylinder 31, the conveyor 33, and the cover 35 are inserted. 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 case 37.

The nozzle 36 at the front end of the heating cylinder 31 is always located in the internal space of the case 37. This prevents the operator from hitting the plasticized resin injected from the nozzle 36. However, the case 37 may have a door (not shown) or the like that exposes the internal space for maintenance.

The display input device 40 is a user interface, and includes a display screen for displaying various information to be notified to the operator, and buttons, switches, a numeric keypad, and the like for receiving an operation by the operator. In addition, the display input device 40 may have a touch panel overlapping with a display screen. The display input device 40 receives, for example, an operation of the operator to start the injection operation and an operation of the operator to start the purge operation, and outputs an operation signal corresponding to the received operation to the control device 50.

The resin pressure sensor 41 detects the resin pressure in the heating cylinder 31, and outputs a detection signal indicating the detection result to the control device 50. The resin pressure is a 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 may, for example, detect the pressure applied to the screw 32 as the resin pressure.

The control device 50 controls the overall operation of the injection molding machine 10. The control device 50 acquires an operation signal output from the display input device 40, a detection signal output from the resin pressure sensor 41, and an encoding signal output from an encoder (not shown) of each of the motors 61 to 67. The control device 50 drives the motors 61 to 67 and the fan 34 based on the acquired various signals.

The control device 50 includes, for example, a CPU (Central Processing Unit) 51 as an arithmetic Unit, a ROM (Read-Only Memory) 52 in which various programs are stored, and a RAM (Random Access Memory) 53 as a work area of the arithmetic Unit. Further, each process described later can be realized by the CPU51 reading and executing a program stored in the ROM 52.

However, the specific configuration of the control device 50 is not limited to this, and may be realized by hardware such as an ASIC (application specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array).

Next, the operation of the injection molding machine 10 according to the first embodiment will be described with reference to fig. 4. Fig. 4 is a flowchart of the purge control processing of the first embodiment. The purge control process starts at a timing when the injection molding machine 10 receives a purge instruction from the outside. At the start of the purge control process, the injection device 30 is located at the standby position, the conveyor 33 is located at the retracted position, and the cover 35 is located at the open position.

The purge instruction may be, for example, an instruction from an operator via the display input device 40, may be set in the control device 50 in advance at the execution timing of the purge operation, or may be received from an external device via a communication interface (not shown).

The purge instruction is roughly divided into "purge of tray" for discharging plasticized resin from a tray (not shown) and "purge of conveyor" for discharging plasticized resin from the conveyor 33. The receiving tray is a container that can be attached and detached by an operator on a discharge path through which the plasticized resin is discharged from the heating cylinder 31 in the standby position (i.e., below the heating cylinder 31).

First, the control device 50 determines the type of the received purge instruction (S11). If the controller 50 determines that the purge instruction is "tray purge" (S11: tray), the controller 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 the plasticizing purge operation or the injection purge operation. A method of adjusting the discharge speed by the plasticizing purge operation and the injection purge operation will be described later.

On the other hand, when determining that the purge instruction is "conveyor purge" (S11: conveyor), the control device 50 acquires a detection signal indicating 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 advance in the ROM 52.

When determining that the resin pressure is equal to or higher than the threshold value (yes in S14), the control device 50 sets the discharge speed at which the plasticized resin is discharged from the heating cylinder 31 to the second discharge speed (S15). On the other hand, when determining that the resin pressure is less than the threshold value (S14: NO), the control device 50 sets the discharge speed of the plasticized resin from the heating cylinder 31 to the third discharge speed (S16).

Here, the first discharge speed, the second discharge speed, and the third discharge speed are speeds of the plasticized resin passing through the nozzle 36. That is, the first to third discharge speeds are speeds independent of the method of discharging the plasticized resin (plasticizing purge operation, injection purge operation). The second discharge speed is slower than the first discharge speed. In addition, the third discharge speed is slower than the second discharge speed.

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

Next, the controller 50 executes the plasticizing purge operation at the discharge speed set in steps S15 and S16 (S18). In the operation of the plasticizing cleaner, the discharge speed can be adjusted by increasing or decreasing the rotation speed of the screw 32. That is, the control device 50 may supply the current having the magnitude 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 advance in the ROM 52.

The controller 50 calculates the number of revolutions of the screw 32 during the plasticizing operation, and continues the plasticizing operation until the calculated number of revolutions reaches the threshold number of revolutions (no in S19) (S18). When the calculated number of rotations reaches the threshold number of rotations (yes in S19), the controller 50 causes the screw 32 to be loosened (kick back) (S20).

The "loosening" is a process of retreating 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 is retracted. Thereby, the space on the nozzle 36 side of the tip of the screw 32 becomes a negative pressure, and the discharge of the plasticized resin from the nozzle 36 is stopped.

Next, the control device 50 determines whether or not a predetermined amount of the plasticized resin has been discharged (S21). The control device 50 determines the amount of the plasticized resin discharged by the plasticizing purge operation, for example, by multiplying the discharge speed set in steps S15 and S16 by the execution time of step S18.

Then, when determining that the predetermined amount of plasticized resin has not been discharged (S21: NO), the control device 50 executes the processing from step S18 onward again. On the other hand, when the control device 50 determines that the predetermined amount of the plasticized resin has been discharged (yes in S21), the purge control process is ended.

According to the first embodiment, for example, the following operational effects are achieved.

According to the first embodiment, "catch tray cleaner" that requires the catch tray to be placed and taken out by the operator and "conveyor cleaner" that can automatically discharge the plasticized resin by the conveyor 33 can be selected. As a result, the burden of the operator for attaching and detaching the tray during the machine cleaning operation can be reduced.

Further, if the plasticized resin is forcibly discharged by the conveyor cleaner, the plasticized resin reaching the surface of the conveyor 33 may scatter outside the conveyor 33 or may enter the interior of the conveyor 33 from the gap between the meshes. The scattering or intrusion of the plasticized resin increases the burden on the operator who maintains the injection molding machine 10. Therefore, as in the first embodiment, by making the second discharge speed and the third discharge speed in the conveyor cleaner slower than the first discharge speed in the tray cleaner, the conveyor cleaner can be favorably realized without increasing the maintenance load.

The case where the resin pressure is equal to or higher than the threshold value (yes in S14) means a state where the viscosity of the plasticized resin in the heating cylinder 31 is high to some extent. Therefore, the plasticized resin reaching the conveyor 33 is less likely to scatter or intrude. On the other hand, the case where the resin pressure is less than the threshold value (S14: no) means a state where the viscosity of the plasticized resin in the heating cylinder 31 is low. Therefore, the plasticized resin reaching the conveyor 33 is highly likely to scatter or intrude.

Therefore, as in the first embodiment, by adjusting the discharge speed in accordance with the resin pressure (in other words, the viscosity of the plasticized resin), it is possible to achieve both the productivity of maintaining the purge operation and the reduction of the maintenance load. The parameter for estimating the viscosity of the plasticized resin is not limited to the resin pressure, and may be an elapsed time after the plasticized resin is supplied into the heating cylinder 31.

Further, the plasticized resin that has reached the conveyor 33 is solidified into a rod shape and discharged. Therefore, if the purging operation is continued for a long time, the rod-shaped plasticized resin becomes long, and it becomes difficult to handle. Therefore, as in the first embodiment, by loosening the screw 32 every time the number of rotations of the screw 32 reaches the threshold number of rotations, the plurality of short divided plasticized resins can be discharged from the conveyor 33.

The timing of loosening the screw 32 is not limited to the example of step S19. As another example, the controller 50 may loosen the screw 32 at a timing when a predetermined time has elapsed after the start of the plasticizing cleaning operation. That is, the controller 50 may loosen the screw 32 at predetermined intervals during the cleaning of the conveyor.

The method of dividing the rod-shaped plasticized resin discharged from the conveyor 33 is not limited to loosening and retreating of the screw 32. As another example, the controller 50 may move the cover 35 from the open position to the closed position at predetermined intervals during the conveyor cleaning. 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 predetermined intervals.

(second embodiment)

Next, the operation of the injection molding machine 10 according to the second embodiment will be described with reference to fig. 5. Fig. 5 is a flowchart of the purge control processing 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.

The control device 50 of the second embodiment performs the processing of steps S31 to S40 of fig. 5 instead of steps S13 to S21 of fig. 4. At the start time of the purge control processing of the second embodiment, the injection device 30 is located at the standby position, the conveyor 33 is located at the retracted position, and the cap 35 is located at the blocking position.

When determining that the purge instruction is "conveyor purge" (S11: conveyor), the control device 50 of the second embodiment sets the discharge speed of the plasticized resin from the nozzle 36 in accordance with the current resin pressure (S31 to S34). Further, the control device 50 moves the conveyor 33 from the standby position to the forward position and adjusts the conveyance speed of the conveyor 33 in accordance with the discharge speed set in steps S33 and S34 (S35). The processing of steps S31 to S35 is common to steps S13 to S17 of fig. 4.

Next, the controller 50 moves the cover 35 from the closing position to the opening position (S36). Next, the control device 50 executes the injection purge operation at the discharge speed set in steps S33 and S34 (S37). By increasing or decreasing the forward speed of the screw 32, the discharge speed can be adjusted during the injection cleaning operation. That is, the control device 50 may supply the current having the 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 advance in the ROM 52.

Next, the control device 50 determines whether or not a predetermined amount of the plasticized resin has been discharged (S38). The control device 50 can determine the amount of the plasticized resin discharged in the injection purge operation by, for example, multiplying the discharge amount of the plasticized resin in each injection purge operation by the number of execution times of step S37.

When the control device 50 determines that the predetermined amount of the plasticized resin has not been discharged (no in S38), the control device moves the cap 35 from the open position to the closed position (S39), causes the injection device 30 to perform the metering operation (S40), and then performs the processing of step S31 and subsequent steps again. That is, the control device 50 intermittently discharges the plasticized resin by repeatedly executing 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 the plasticized resin has been discharged (yes in S38), the purge control process is terminated.

The viscosity of the plasticized resin tends to be lower as the residence time in the heating cylinder 31 is longer, and tends to be higher as the residence time is shorter. That is, the viscosity of the plasticized resin already in the heating cylinder 31 at the start time of the purge control process becomes relatively low, and the viscosity of the plasticized resin newly supplied into the heating cylinder 31 in the purge control process becomes relatively high.

Therefore, as in the second embodiment, each time the screw 32 is advanced, the resin pressure is detected, and an appropriate advance speed is set, whereby the first half of the multiple injections selects the third discharge speed, and the second half selects the second discharge speed. This can achieve both the productivity of the maintenance operation and the reduction of the maintenance load.

(third embodiment)

Next, an injection molding machine 10A according to a third embodiment will be described with reference to fig. 6, 7A, and 7B. Fig. 6 is a side view showing a schematic structure of the injection molding machine 10A. Fig. 7A and 7B are front views of the heating cylinder 31 as viewed from the distal end side thereof. Note that the same reference numerals are given to components that serve the same functions as those of the first embodiment, and detailed description thereof is omitted.

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) is moved in the horizontal direction between an injection position and a standby position which are separated in the horizontal direction. That is, the injection molding machine 10A of the third embodiment is different from the injection molding machine 10 of the first embodiment in that the positional relationship of the main constituent members 22 to 25, 31 to 32 is reversed by 90 °.

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 functions to guide the plasticized resin discharged from the heating cylinder 31 by the purging operation to the conveying surface of the conveyor 33. The driving force of the guide plate advancing and retreating motor (not shown) is transmitted to the guide plate 38, and the guide plate 38 is moved between the retreat position (fig. 7A) and the guide position (fig. 7B).

The retreat position is a position away from the moving path of the heating cylinder 31. The guide position is a position on the moving path of the heating cylinder 31. That is, when the guide plate 38 is located at the retreat position, the plasticized resin discharged from the heating cylinder 31 located at the standby position does not reach the guide plate 38, and the injection device 30 (the heating cylinder 31) can move between the standby position and the injection position. On the other hand, when the guide plate 38 is located at the guide position, the plasticized resin discharged from the heating cylinder 31 located at 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.

The conveyor 33 according to the third embodiment is fixed directly below the nozzle 36 at the distal end of the heating cylinder 31 in the standby position and directly below the guide plate 38 in the guide position. That is, both the plasticized resin leaking little by little from the heating cylinder 31 in the standby position and the plasticized resin forcibly discharged from the heating cylinder 31 in the standby position and reaching the guide plate 38 reach the conveying surface of the conveyor 33, and are conveyed to the outside of the injection molding machine 10A.

The injection molding machine 10A of the third embodiment executes the purge control process shown in fig. 4 or 5. However, the control device 50 of the third embodiment moves the guide plate 38 from the retreat position to the guide position after moving the injection device 30 (the heating cylinder 31) from the injection position to the standby position. Then, the control device 50 of the third embodiment moves the guide plate 38 from the guide position to the retreat position before moving the injection device 30 (the heating cylinder 31) from the standby position to the injection position.

According to the third embodiment, the plasticized resin forcibly discharged from the nozzle 36 at the tip end of the heating cylinder 31 by the purging operation hits the guide plate 38 at the guide 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 purge operation can be reliably and efficiently discharged to the outside of the injection molding machine 10A by the conveyor 33.

Claims

1. An injection molding machine for producing an injection molded article by injecting a plasticized resin into a mold,

comprising:

a heating cylinder having a nozzle formed at a distal end thereof that moves between an injection position where the heating cylinder communicates with a cavity of the mold and a standby position where the heating cylinder is separated from the mold,

a conveyor disposed on a discharge path through which the plasticized resin is discharged from the heating cylinder at the standby position, and configured to convey the plasticized resin discharged from the nozzle to the outside of the injection molding machine, and

a control device for controlling the actions of the heating cylinder and the conveyor;

the control device causes the heating cylinder in the standby position to discharge plasticized resin at a first discharge speed in a case where execution of a purge of a receiving tray that causes the receiving tray to discharge the plasticized resin is instructed, the receiving tray being provided on a discharge path that discharges the plasticized resin from the heating cylinder in the standby position,

the control device causes the heating cylinder in the standby position to discharge plasticized resin at a second discharge speed slower than the first discharge speed when instructed to execute a conveyor purge for causing the conveyor to discharge plasticized resin.

2. The injection molding machine of claim 1,

the injection molding machine has a resin pressure sensor that detects a resin pressure applied to plasticized resin in the heating cylinder,

the control means, in the case of being instructed to perform the conveyor purge,

causing the heating cylinder in the standby position to discharge plasticized resin at the second discharge speed when the resin pressure detected by the resin pressure sensor is equal to or higher than a threshold value,

and causing the heating cylinder in the standby position to discharge plasticized resin at a third discharge speed slower than the second discharge speed when the resin pressure detected by the resin pressure sensor is less than a threshold value.

3. The injection molding machine of claim 2,

the injection molding machine has a screw rod capable of advancing, retreating and rotating in a heating cylinder,

the control device, when instructed to perform the conveyor purge, rotates the screw disposed at a position closest to the nozzle in a direction in which the plasticized resin is moved to a 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. An injection molding machine according to claim 3, wherein the control device retracts the screw at predetermined intervals in the conveyor purge.

5. The injection molding machine of claim 1,

the control device intermittently discharges the plasticized resin by advancing and retreating the screw in a case where execution of the conveyor purge is instructed.

6. The injection molding machine of claim 5,

the control device repeatedly executes, when instructed to execute the conveyor purge, a process of detecting a resin pressure by the resin pressure sensor and advancing the screw at a speed corresponding to the detected resin pressure.

7. The injection molding machine according to any one of claims 2 to 6, wherein the control device adjusts a conveying speed of the conveyor in accordance with a discharge speed of the plasticized resin from the heating cylinder in a case where execution of the cleaning of the conveyor is instructed.