Injection mold data transmission system

The present invention relates to injection molding devices and procedures, and in particular, structures and methods for enabling and facilitating information transmission from injection molding sensors to control means without the need for cumbersome and expensive analog wiring connections. Regarding. The present invention also enhances reliability in the feedback control loop because many connections in the control system that can cause errors can be removed by the user.

Generally, injection molding is performed in a mold that operates at high temperature and high pressure. As is well known to those skilled in the art, a typical mold is maintained in a molten state until the material injected into the mold is completely filled in the mold cavity, and voids are formed in the mold cavity. It has means for heating the mold at multiple locations within the mold so that it does not occur (ie, a hot runner system). In addition, as is well known to those skilled in the art, in order to ensure the material properties of the part (eg, material strength, etc.) and to control the cooling and solidification rate of the material, the mold before injecting the material. It is desirable to heat.

In order to carry out such control, it is determined that the information from the mold sensor can be used between the controlled means (for example, the mold heater) and the mold sensor (for example, the mold temperature sensor). It is necessary to establish a closed-loop feedback system via a control means that enables the controlled means to be controlled according to a series of instructions. At present, the information from the injection molding sensor is transmitted to the control means in analog form by a wiring connection using a sensor-dedicated wire physically connected to each sensor and the control means via a series of connectors. These wires, used in combination with readily available connectors, form a sensor feedback cable. Generally, each cable requires two or more wires for each sensor disposed in the mold to carry an analog signal.

For example, when applied to thermal analog temperature, the number of cables required to transmit information from the mold to the control means depends on the number of sensor means arranged in the mold, but is typical. Commercially available mold configurations often exceed 48 pieces. For example, if the mold requires 30 sensor means, it typically requires 60 analog sensor wires. In addition, the sensor wires are generally configured such that there are seven thermal connection points between the sensor means and the control means for each sensor wire. Therefore, in the injection molding mold as described above, 420 connections are formed between the sensor means in the identified mold and the control means for the mold.

In a closed-loop feedback system such as the one described above, which has a large number of wires and connectors, 1) problems related to poor connection and low temperature solder connection that may feed back incomplete or intermittent data, 2) path of analog feedback cable. Inaccurate feedback due to temperature changes along, 3) the effect of electrical noise on low-level analog signals over the entire length of the feedback cable, 4) wire and cable storage, and people on cables located on the floor in the injection molding area. A number of problems caused by the total volume of cables and wires required, including simple problems such as tripping, and 5) various problems known to those of skill in the art, including other problems well known to those of skill in the art. May occur. As the number of sensors in a given mold increases, so does the number of wires and connections in traditional systems. Therefore, as molds become more complex or sophisticated and control of mold operation becomes more important, the chances of error in conventional control systems increase as well. In practice, one of the actual limits on the number of temperature sensors that can be effectively employed in an injection molding system arises from the limit on the number of sensors and control wires that can be managed by the system or system operator. ..

A preferred embodiment of the present invention comprises a sensor input circuit to be positioned within a mold or a thermally isolated enclosure disposed near the mold. Further, a signal processing means for converting an analog sensor signal from each sensor into a digital format is also provided. Further, in a preferred embodiment of the present invention, when the information from each mold temperature sensor is converted into a digital format, the transmitter is positioned in the heat insulating enclosure so as to transmit the information to the mold control means. The receiver is positioned in or near the mold control means to receive the digital information transmitted from the transmitter to the mold control means so as to enable the closed path control of the molding means.

The advantage of the present invention is that the signal transmission from the sensor input circuit to the mold control means can be achieved digitally, unlike conventional systems that require a large number of analog connections and have problems associated with them. It solves many analog connections and their associated problems.

By removing all but one of the analog connections with this digital interface, the possibility of errors due to the connection is almost completely eliminated. In addition, since the information is preferably converted to digital form in an adiabatic enclosure located near the mold itself, the possibility of electrical noise acting on the analog control signal is greatly reduced. In addition, by removing the large number of cables required by the prior art, 1) the cost of replacing a large number of wires is reduced, 2) the cable connection error is reduced, and 3) the large number required by the prior art. Save energy and space by eliminating the need to store through wires and cables, 4) Low level analog to high power cables that can be accidentally connected to the wrong means or cause damage, fire or electric shock. Elimination of safety hazards that occur when signals are sent, and 5) elimination of hazards that reduce safety that occur when a large number of wires and cables extend along the floor of the installation part of the injection mold. There are many benefits, including.

The present invention will be described more fully with reference to the accompanying drawings. As shown in FIG. 1, in the prior art, an injection molding apparatus is configured to have a large number of wires extending from the mold 1 to the mold control means 3. These wires transmit analog information from the mold 1 to the mold control means 3 and also transmit commands or switched electrical power from the mold control means 3 to the controlled element related to the mold 1. .. Due to its physical size, the mold control means 3 is properly operated by the mechanical operation of the mold / molding machine in the operating environment of the mold 1, that is, during the operation according to a typical injection molding process. Due to the environment where avoidance of danger due to contact is required, it is necessary to position it away from the mold 1. The controlled element according to the mold 1 is a mold heater (that is, a heat element) configured to heat the mold or the material injected into the mold, or injection molding as is well known to those skilled in the art. It may be a valve piston (that is, a valve gate) configured to reliably open and close the gate in the mold used in the process, and is a mold / material pressure detecting means such as a cavity pressure sensor. You may.

As shown in FIG. 3, the apparatus of the present invention 1) receives and processes signals from mold 1 and 2) mold 1, and generates a control signal to relate to mold 1. It includes a mold control means 4 for transmitting to one or more controlled elements. Each sensor 5 is arranged at a desired position on the mold 1, a desired position within the mold 1, or a desired position around the mold 1. These sensors can be configured to detect temperature, pressure, fluidity, or any other variable that the operator intends to monitor or measure. The temperature sensor input means typically consists of a bimetal thermocouple of a type well known in the prior art that produces an analog signal capable of measuring temperature. Similar sensor elements for pressure and other variables are well known to those of skill in the art.

In a preferred embodiment of the present invention, the heat insulating enclosure 6 is coupled to the mold 1 or the holding structure (7) in the vicinity of the mold. The heat insulating enclosure 6 can be made of a plastic or metal material, and a non-thermally conductive material is provided between the heat insulating enclosure 6 and the mold 1 itself.

Inside the heat insulating enclosure 6, a junction box 8 for accommodating an interface connection portion between each mold sensor and the IMDT thermal enclosure is arranged. The IMDT thermal enclosure contains electrical and electronic components, including signal processing means, transmitters, and power supplies. The junction box 8 is configured to provide a place for easily connecting the wires from each mold sensor means to the IMDT means. The junction box 8 is removable from the insulation enclosure 6 to facilitate quick replacement of defective components.

As shown in FIG. 2, the signal processing means of a preferred embodiment are a sensor tuning input circuit 9, an isolation circuit 10, a multiplexer 11, an amplifier 12, a microprocessor 13, an analog-to-digital converter 14, and a closed loop from the control means. It has a closed loop return logic.

The sensor adjustment input circuit 9 is connected to the IMDT input means 15 and functions to amplify the signal and filter noise from the analog input unit. The isolation circuit 10 is connected between the microprocessor 13 and the analog-to-digital converter 14 and functions to optically isolate the signal conditioning and conversion circuit from the logic circuit of the microprocessor. The multiplexer 11 is coupled to the analog digital circuit 14 and the state input circuit.

As a result, the signal output from the multiplexer 11 is transmitted to the analog-to-digital converter 14 having the conventional configuration. The resulting digital signal is transmitted to the microprocessor 13 via an optically isolated circuit for further signal processing within the microprocessor. The input unit of the transmitter 16 is coupled to the microprocessor 13 and transmits to a receiver connected to the mold control means. Although the present invention has described the components described above, other different components well known to those skilled in the art can also be used. Therefore, the present invention is limited only by the claims set forth below.

<figref num="1">It is explanatory drawing of the typical mold using the apparatus of the prior art and the control means concerning it.</figref><figref num="2">It is a schematic block diagram of a suitable embodiment which concerns on the apparatus of this invention.</figref><figref num="3">It is explanatory drawing of the typical mold which used the apparatus including this invention, and the control means concerning it.</figref>