Control device for use in injection molding machine

In an injection molding machine configured to extrude a melted resin under temperature control and inject the resin into metal molds to provide a molded product, there are provided an HMI section having a built-in general-purpose operating system and configured to control a display section equipped with a touch panel, control modules, such as a main control section, a sequence processing section and a servo command section, having a dedicated microprocessor for each control element of the injection molding machine, and a driver section having servo amplifiers, hydraulic drivers, and so on, configured to be controlled by the control modules and to drive-control an actuator of the injection molding machine, in which, by variously combining together the control modules, it is possible to provide various kinds of injection molding machines, that is, an electric operation type, a hydraulic type and a hybrid type of these combination.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2005-117148, filed Apr. 14, 2005, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a control apparatus for use in an injection molding machine.

2. Description of the Related Art

Known is, for example, an injection molding machine as disclosed in Jpn. Pat. Appln Kokai Publication No. 2001-191383.

An injection molding machine may use various kinds of controls, such as in the injection, in measuring, in mold opening and closing, in extruding, and in the application of temperature.

In the injection molding machine of the above Publication, control of the injection molding is performed by a specific control device that is usable only for the injection molding machine.

A type of Control of an actuator in the injection molding machine, as well as measuring, mold opening/closing and extrusion operations is selected depending on whether an electrical operation type or a hydraulic type is used.

Thus, the use of such control types differs depending on whether an electrical type of operation, a hydraulic type of operation or a hybrid type of operation is used.

In the prior art, when a control target is an electrical operation of an actuator, a dedicated control device has been used and, when the control target is a hydraulic operation, a corresponding special control device has been used.

Therefore, the conventional injection molding device requires a dedicated control device. As a result it is difficult to provide a general-purpose machine.

BRIEF SUMMARY OF THE INVENTION

An aspect of the present invention is to provide a control device for use in an injection molding machine. When a control target in the injection molding machine is changed, the control device can be tailored to each control element. As a result, the control device can handle such a situation through a combination of control modules. Thus, a general-purpose machine unit can be provided.

In one aspect of an embodiment of the present invention there is provided an injection molding machine for heating a synthetic resin material and, injecting a predetermined amount of molten synthetic resin material into a melted mold to obtain a molded product. The injection molding machine comprises a human/machine interface device having a general-purpose operating system. The interface device is configured to control a display section, to control a plurality of control modules having a dedicated microprocessor for each control element of the injection molding machine, and to control a driver, the driver section being configured to drive-control an actuator of the injection molding machine, wherein various kinds of injection molding controls can be performed through a specific combination of various control modules.

Additional aspects of various embodiments the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Aspects of the invention may be realized and obtained by means of instrumentation and combinations particularly pointed out hereinafter.

DETAILED DESCRIPTION OF THE INVENTION

The injection molding machine includes an injection molding machine body1, an injection screw4arranged so as to be inserted into a cylindrical barrel3. The injection machine also includes a hopper2.

The injection screw4is rotatable in the barrel3and freely movable forward and backward.

The barrel3communicates with the hopper2. A synthetic resin material is fed into the barrel through the hopper2. A plurality of heaters, not shown, are arranged at predetermined intervals on the outer periphery side of the barrel3. These heaters are adapted to heat the outer periphery of the barrel and melt the resin material fed into the barrel3.

The barrel3has an injection nozzle5at a forward end of the barrel3to allow the melted synthetic resin material to be injected.

A heating temperature of the barrel3is controlled by the plurality of heaters so that the melting degree of the melted resin material gradually increases when the resin moves toward the forward end of the barrel3.

The injection screw4is rotatably driven by a servomotor6for injection and moved forward and backward. That is, the servomotor6for injection transmits its rotation to a ball screw shaft11through a transmission mechanism comprising a pulley7, a timing belt8and a timing pulley9.

The ball screw shaft11is rotatably provided in a servo bracket10.

The ball screw shaft11is set in a ball nut12. The ball nut12is fixed by bolts to a thrust box13.

The injection screw4is rotatably joined at its rear end portion to the thrust box13through an S shaft and bearing (not shown).

The S shaft is rotatably connected to the thrust box13and mounted to a timing pulley14.

A servomotor17is also provided. The servomotor17has a rotation shaft which is connected to a pulley16.

A timing belt15is provided between the timing pulley14and the pulley16.

The timing pulley14, timing belt15and pulley16constitute a transmission mechanism.

The servomotor17moves the injection screw4material which is to be injected forward, determining an amount of the melted resin. The servomotor17transmits its rotation to the S shaft as set out above through the associated transmission mechanism as set out above to allow the injection screw4to be rotated.

The forward moving position of the injection screw4is determined by an amount of synthetic resin material injected.

In the forward position of the barrel3are provided metal mold halves18and a device19for opening/closing and clamping the metal molds.

When the melted resin material is injected from the injection nozzle5, the injection nozzle5is pushed into a nozzle inlet18aof one metal mold half18. In this state, the forward end4aof the injection screw4is moved forward and, by doing so, allows the resin material which is melted in the barrel3to be injected through the injection nozzle5. Thus, the resin material is charged into a cavity20defined by the metal mold halves18.

The device19has a fixing plate21that supports one of the metal mold halves18. A movable plate23is provided. The movable plate23holds a tie bar22which in turn supports the fixing plate21. The movable plate23can move toward and away from the fixing plate21.

The device19attaches the movable plate23to a toggle mechanism support plate25through a toggle type mold clamping mechanism24.

A servomotor26is provided on the toggle mechanism support plate25to drive the toggle type clamping mechanism24. A mold thickness adjusting mechanism27is provided. The mechanism27adjusts a mold thickness when the toggle type mold clamping mechanism24effects the mold clamping operation.

In the electrical type injection molding machine thus structured, the servomotor26is first driven for mold clamping. By doing so, the metal molds18start their mold closing operation. In addition, the injection nozzle5of the barrel3is pushed into the nozzle18aof the mold halves18.

Then, the measuring servomotor17, while being rotated, moves the injection screw4forward and effects a quantity of the melted resin material injected. Then, the injection servomotor6rotates the injection screw4to inject the melted resin.

The barrel3injects the melted resin through the injection nozzle5and charges the melted resin into the cavity20of the metal molds18.

As shown inFIG. 2, a control device of the electrical type injection molding machine1includes a main control section31for controlling each part of the injection molding machine, a sequence processing section32and a servo command section33.

The main control section31includes a CPU, ROM, RAM, etc. The main control section31allows to manage and monitor the injection molding machine1.

The sequence processing section32has a CPU, ROM, RAM, etc. The sequence processing section32allows to control the operation sequence of the injection molding machine1.

The servo command section33has a CPU, ROM, RAM, etc. The serve command section33allows to control the injection servomotor6and the measuring servomotor17.

The main control section31, the sequence processing section32and the servo command section33are electrically connected together through a bus line34.

The servo command section33controls a servo amplifier35in a driver section and drives the injection servomotor6. The rotation and current value of the injection servomotor6are detected by a detection section36.

The servo command section33receives a signal from the detection section36and detects the moved position and rotation speed of the injection screw4and the current value in the motor. Furthermore, the servo command section33performs feedback control based on the detected moved position of screw4and rotation speed of the screw4and current value in the motor and thus controls the servomotor6.

The servo command section33controls the servo amplifier35in the driver section and drives the servomotor17for measurement. The rotation and current value of the measuring servomotor17are detected by a detection section38.

The servo command section33receives a signal from the detection section38and detects the moved position and rotation speed of the injection screw4and current value of the servomotor. Furthermore, the servo command section33performs feedback control based on the moved position of screw4and rotation speed of the screw4and current value in the servomotor17. The servo command section33also controls the servomotor17for measurement.

An I/O40, etc., is electrically connected via I/O bus39to the sequence processing section32.

The main control section31, sequence processing section32and servo command section33each constitute a control module with a dedicated microprocessor for each control module.

The main control section31includes a communication interface section such as HMI section41. HMI section41is a human/machine interface device that is electrically connected to the main control section31through a LAN42such as Ethernet (registered trademark name).

The HMI section41is comprised of, for example, a personal computer and connected to a display section43. The display section43has a touch panel on a liquid crystal display screen to allow the display screen to be controlled.

The main control section31is connected via a cable45to an operation panel section44. The operation panel section44has a plurality of mechanical operation switches.

The main control section31is connected via a cable46to the touch panel of the display section43.

The main control section31is connected via a cable48to a temperature control section47. The temperature control section47controls the heating temperature of the plurality of heaters arranged on the outer periphery of the barrel3.

The display section43allows to display control parameters via the HMI section41and allows touch panel of the display section43to be controlled by the main control section31.

The display section43outputs a key signal to the main control section31by finger-touching any corresponding key on the touch panel on the display screen.

In such arrangement, the main control section31controls the temperature control section47. The temperature control section47controls the heating temperature of the plurality of heaters to melt the synthetic resin material transferred from the hopper2into the barrel3.

When the resin material is injected through the injection nozzle5of the barrel3into the cavity20, the sequence processing section32and servo command section33are controlled.

First, the servo command section33controls the servo amplifiers37and drives the measuring servomotor17. The servomotor17rotates the injection screw4to move the melted resin forward and determine the melted resin amount injected from the barrel3.

Then, while the injection screw4is rotated, the injecting servomotor6is driven to move the resin forward. The injection screw4pushes the melted resin through the injection nozzle5via the forward end4a. By doing so, the mold cavity20is filled with the melted resin which is through the injection nozzle5past the nozzle inlet18aof the mold halves18.

When the filling of the melted resin material is finished, the device19is operated for the closing and clamping of the mold halves18. The mold halves18are moved apart from the barrel3. The device19opens the metal molds and a molded product is taken out from the metal mold halves18.

The above description of operation is for the electrical type injection molding machine. However, it is also possible to use a hydraulic type injection molding machine in place of the electrical type injection molding machine.

In the case of the hydraulic type injection molding machine, a hydraulic driver for relief/flow control is used. In this case, the injection servomotor6and measuring servo motor17may not be used.

A control device of the hydraulic type injection molding machine does not use the servo command section33and servo amplifiers35,37connected to the servo command section33as well as the injection servomotor6, measuring servomotor17and so on.

As shown inFIG. 3, the control device disconnects the servo command section33and servo amplifiers35,37connected to the section33as well as the injection servomotor6and measuring servomotor17and so on and, instead, connects a hydraulic I/O51to a bus line34. In this case, the hydraulic I/O51is connected to hydraulic drivers52and53.

The hydraulic driver52moves the injection screw4forward and backward so that the injection screw4injects the molted resin. On the other hand, the hydraulic driver53moves the injection screw forward and backward so that the hydraulic driver53measures an amount of melted resin injected.

When the injection molding machine is changed from the electrical type injection molding machine to the hydraulic type injection molding machine, a change is made to the configuration of the injection screw. Indeed, the injection screw4driven by the injection servomotor6in an electrical type injection molding machine is changed to an injection screw driven under a hydraulic pressure in a hydraulic type injection molding machine.

A barrel3having a different structure is employed in the hydraulic type injection molding machine compared to a barrel3in the electrical operation type injection molding machine. As such, the injection molding machine per se maybe wholly replaced.

However, the control device has a dedicated CPU for each of the main control section31, the sequence processing section32, and the servo command section33. The control device provides a control module, that is, a unit modularized for each control element. Therefore, the main control section31, the sequence processing section32, and the servo command section33in the main control device are individually exchangeable.

In this way, when the injection molding machine is changed from the electrical operation type to the hydraulic type, the servo command section33and so on are disconnected from an associated circuit and, instead, the hydraulic I/O51is connected to the bus line34. The hydraulic I/O51is connected to hydraulic drivers52and53. In this case, if the sequence processing section32in the electrical type injection molding machine is different from a sequence processing section32in the hydraulic type injection molding machine, an appropriate hydraulic type sequence processing section can be used.

As a result, even if a change is made from the electrical type injection molding machine to the hydraulic type injection molding machine, replacing the control device as a whole, may not be needed. In this case, an exchange may be made in control module units.

It is also possible for the injection molding machine to use any proper electrical type/hydraulic type combination as a hybrid type injection molding machine.

A control device that can be used in the hybrid type injection molding machine, is shown inFIG. 4. A hydraulic I/O51is connected to a bus line34as in the control device shown inFIG. 2. The hydraulic I/O51is connected to the hydraulic drivers52and53. Furthermore, a sequence processing section32is replaced by a hybrid type. Thus, it may not be necessary to replace the control device as a whole.

Incidentally, the sequence processing section32has initially a built-in sequence control program corresponding to an electrical, a hydraulic and a hybrid type operation. The sequence processing section32is constructed so that any corresponding sequence control program can be selected.

Accordingly, the sequence processing section32is not replaced by a new one and can be readily tailored to meet a specific need by selecting any sequence control program.

As evident from the above, even if the injection molding machine is changed to any of the electrical, hydraulic and hybrid type operation, the control device does not need to be changed as a whole. It is possible to readily adapt to any configuration through the change of any possible control module combination. As a result, the control device provides an excellent general-purpose device and provides higher economic benefits.

Furthermore, the control device described herein achieves an enhanced processing capability, by allowing the exchange of the main control section31and sequence processing section32.