Applicants have further discovered that the vector control for the motor drives can be configured to run multiple motors, potentially four or more in an injection molding machine, one or more at a time. This is accomplished by multiplexing the controller CPU (central processing unit, i.e. computer) for the power sections of each motor. One of the drawbacks to implementing vector control for injection molding machine is that the controller CPU for this type of system is very complex and expensive. By sharing the controller CPU between several motors and power transistors, a significant cost savings is realized without sacrificing machine performance.

An object and advantage of this invention is to provide an injection molding machine having vector controlled AC induction motor drives that are rugged, are of simple construction, are reliable, have superior speed and torque capabilities and can be obtained at a cost comparable to permanent magnet servomotors.

A related object and advantage of the invention is to provide vector controlled AC induction motor drives for a full range of injection moulding machine sizes including those capable of 1000 tons or more of clamping force without having to gang together two or more motors in a single drive unit to provide the necessary power.

A further object and advantage of this invention is to provide an injection molding machine having vector controlled AC induction motor drives which provide performance equal to or better than the performance requirements of current state of the art injection molding machines at a reduced cost.

A still further object and advantage of this invention is to provide an injection moulding machine having vector controlled AC induction motor drives for the clamp unit, the extruder and injection unit, as well as the other closed loop motive power systems typically used on an injection molding machine, wherein the vector control for the motor drives is configured to run multiple motors.

Applicants have developed an injection molding machine drive system using vector controlled AC induction motors. Although the AC induction motor has been used extensively in industrial applications for many years, it has not been used extensively as a servomotor due to complex and expensive control requirements. Despite the advantages of induction motors compared to DC permanent magnet motors, such as low cost, light weight, reduced inertia, low maintenance and high efficiency, its primary application has remained in constant speed drive applications.

In the optimum molding condition setting system, when entering the data of the defective molded products into the molding defect elimination means, a defective point is entered into a filling pattern diagram being obtained by the molten material flow analysis means. As a result, the deficiency which occurs during a filling control process of the injection molding machine can be ascertained.

In the optimum molding condition setting system, the analysis result evaluation means compares the correction values of the molding conditions such as a mold temperature, a resin temperature, an injection speed, a cool time, etc. being obtained by the molding defect elimination means, with permissible values being obtained by the molten material flow analysis means. An alarm message can be issued and/or the value of the molding condition can be corrected again when the correction value of the molding condition exceeds the permissible value.

Data of a configuration of the mold model which are employed for the analysis by the molten material flow analysis means can be used by the molding defect elimination means.

Furthermore, the corrected value of the molding condition being obtained by the molding defect elimination means can be analyzed by the molten material flow analysis means, evaluated by the analysis result evaluation means and then set in the injection molding machine.

This system may preferably be connected to the injection moulding machine via a communication line so as to automate both a transfer of data regarding the molding defect and a setting of the molding condition.

In addition, the system may be provided with an IC card capable of writing the molding condition and/or an operating state of the injection moulding machine so that various data can be interchanged between the system and the injection molding machine.

Multiple Plastic Types

 

    When you use injection moulding, you have the option of molding two different types of plastic at once. This process is called co-injection molding. Therefore, you do not have to worry about access to a particular type of plastic.

 

Thermoplastics

 

    Injection moulding makes use of thermoplastics. Thermoplastics can be injected into the mold, then the excess can be remelted and used again. Therefore, injection molding machine can save you on materials. Thermoplastics can also come in a wide variety of densities or strengths.

 

Fillers

 

Injection molding provides you with the option of using fillers in your molds. Fillers are used to reduce the density of the plastic as it is molded as well as provide greater strength to the product once it is molded. This is another method of reducing the total cost of the process.

The molds used in the two processes are also quite different. The molds used during injection moulding remain sealed throughout the process. Hydraulic force can hold the molds in place or manual levers can hold them closed. The blow molding molds begin the process split apart while the molten plastic extrudes from the die head. When the machine extrudes enough plastic, the molds close around the material. These molds are held in place hydraulically.

 

Air

 

In injection moulding, minimizing the air present in the injected plastic is a top priority. Air bubbles diminish product quality. When set up correctly, the amount of injected plastic should completely fill the injection mold. Blow molding takes a different approach. The die head of a blow molding machine, reports Engineer's Handbook, contains a blowpin. The blowpin extends through the die head itself and into the actual mold. After the molds close, air is forced into the mold to expand the plastic to the limits of the mold cavity (hollow interior). Overall, injection moulding is simpler, more reliable, more versatile and more efficient than most other types of injection molding machine.

This object is achieved within the realm of process engineering, in accordance with the invention, with a plastics processing machine having a mould divided into two, with the mould halves secured to two mould clamping plates which may be moved apart for product removal. Specifically, the mould halves of the first product mould remain on the mould clamping plates, and the mould halves of the second product mould are clamped onto the mould halves of the first product mould. Advantageously, the molten raw plastics material to be processed and/or the operating means, such as electrical energy, hydraulic oil or cooling water, are supplied and in some cases removed again by means of changeable pipelines and/or flexible (hose) lines and cables. Constructionally the mould halves of the first product mould are clamped onto the mould clamping plates and have on their inwardly facing sides additional securing means for clamping on the mould halves of a second product mould.

shows a principal part of a controller 10 for drivingly controlling an injection molding machine for carrying out a molding data collecting method of the present invention. The controller 10 comprises a CPU 25 for CNC as a micro-processor for numerical control, CPU 18 for PC as a micro-processor for a programmable controller, a servo CPU 20 as a micro-processor for servo control and a pressure monitor CPU 17 for executing a sampling process by detecting an injection pressure and a screw back pressure from pressure detectors provided on an injection moulding body through an A/D convertor. Information is transmitted among respective micro-processors by selecting mutual input/output through a bus 22.

PCCPU 18 is connected to a ROM 13 for storing a sequence program for controlling a sequential action of the injection molding machine and a RAM 14 for use in temporarily storing data of an arithmetic operation. The CNCCPU 25 is connected to a ROM 27 for storing an automatic operation program to wholly control the injection moulding, and a RAM 28 for use in temporarily storing operation data.

The servo CPU 20 is connected to a ROM 21 for storing a control program dedicated for a servo control and a RAM 19 for temporarily storage data, and the pressure monitor CPU 17 is connected to a ROM 11 for storing a control program for a sampling process of the injection pressure and screw back pressure and with a RAM 12 for a temporarily storage of data. Further, the servo CPU 20 is connected to servo amplifiers for driving servomotors for respective axes such as clamping, injection, screw rotation, ejection, etc. and outputs from position/speed detectors attached to respective servomotors are fed back to the servo CPU 20. The current positions of the respective axes are calculated by the servo CPU 20 based on feedback pulses from the position/speed detectors and renewed and stored in current position storing resistors for the respective axes. A servo amplifier 15, a servomotor M and a position/speed detector P for one axis are shown in FIG. 1, and respective axes for clamping, injection, ejection, etc. have the same structure. With respect to the axis for screw rotation, however, the current position need not be detected and it is sufficient to detect only the speed.

An interface 23 is an input/output interface for connection to a host computer, etc.