JP2002127220A - Method for controlling heating of gate for multi-cavity mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent occurrence of a fault product due to unevenness of a gate temperature by enabling a suitable use of a control amount of a feedback control as that of another gate of same block when one gate is feedback temperature controlled, and surely and accurately performing uniformity of each gate temperature in the block. SOLUTION: A method for controlling heating of the gate for a multi-cavity mold comprises the steps of setting a supply electric energy for previously heating and holding the gates 5 according to respective gates 5 at respective manifolds 3 by a correction volume 11 of a multiple-point electric energy regulator in the mold of hot runner type, controlling the heating output signal of the many gates 5 according to a control signal when feedback temperature controlling of the one gate 5 to control the gates 5 to an equal temperature without difficulty, and eliminating unevenness of the temperatures of the many gates 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gate heating control method for heating and holding a large number of gates at a desired temperature in a hot runner type multi-cavity mold.

[0002]

2. Description of the Related Art When molding a synthetic resin product, the flow of the molten resin is distributed by a runner in a mold in a lot of individual pieces. The distribution by the runner includes a cold runner method in which the runner is not heated. There is a hot runner method of heating, and the latter hot runner method is often used when molding polyethylene terephthalate resin or the like.

A hot runner type mold gate is formed integrally with the runner and does not have a dedicated heating means, or is formed separately from the runner and has a dedicated heating means (such as a coil heater). Some are equipped.

In the case of heating a gate, there is a method of controlling the heating of individual gates by observing a condition such as burning of a product. However, in this method, accurate heating control of the gate is impossible. Therefore, it has been considered that temperature sensors are attached to all the gates, and the gates are heated and maintained at the optimum temperature by performing feedback control according to the detection signals of the temperature sensors.

Although this method can accurately control the heating of the gate, in the case of a multi-cavity mold, a large amount of control equipment such as sensor wiring and a temperature controller is required, so that equipment costs are reduced. Is enormous, and the structure and handling of the mold equipment is complicated and cumbersome, so it is not practical.Therefore, a large number of gates are divided into several blocks. Many control systems have been adopted in which temperature is controlled by feedback control using a sensor, and at this time, the remaining gates are also controlled by the same control amount.

[0006]

However, in this prior art, each gate is not necessarily provided due to variations in the heating capacity of the heating means mounted on the gate, the mounting accuracy of the mold, the expansion and contraction of the mold, and the like. However, it is not necessarily heated to the same temperature with the same power. Therefore, when the other gates are controlled according to the control amount of the feedback control of one gate,
There is a problem that a large difference in the heating temperature occurs between the gates and a defective molded product is generated.

Further, there is no standard for dividing a large number of gates into blocks, so that a large temperature difference may occur between gates in one block. In this case, it is not possible to perform temperature control for each block. There was a problem that it became possible.

Accordingly, the present invention has been made to solve the above-mentioned problems in the prior art, and when controlling the feedback temperature of one gate, the control amount of this feedback control is changed to the other gate of the same block. The technical issue is to make it possible to properly use the control amount as a control amount, and thereby to achieve the uniformization of each gate temperature in the block reliably and accurately, and to generate defective molded products due to the variation of the gate temperature. The purpose is to prevent.

[0009]

The means of the present invention for solving the above technical problems relates to a hot runner type multi-cavity mold in which a plurality of manifolds are arrayed and assembled on one base manifold. Applying the following processing to each manifold having a plurality of gates equipped with a coil heater for heating, in advance, for each gate,
The amount of electric power supplied to the coil heater required to heat and maintain the gate at the same constant temperature is adjusted and set by a correction volume corresponding to each gate of the multi-point electric energy adjuster. That is, when one temperature is feedback-controlled to a constant value, the temperature of the remaining gates is controlled by the obtained control signal.

A plurality of manifolds arranged and assembled on one base manifold are provided with cooling means for each manifold, and are mounted on the base manifold for each manifold.

As a result, each gate attached to one manifold is substantially equally affected by the cooling action and the accuracy of attachment to the base manifold.

Therefore, the main cause of the temperature difference between the gates of one manifold is the variation in the heating capacity of the coil heaters provided in the gates. Can be kept small enough by quality control in advance,
A large temperature difference does not occur between the gates of one manifold.

Prior to the operation of the mold, the mold was operated under substantially the same conditions as the actual operation, and the temperature of each gate was measured for each manifold, and the remaining temperature relative to the arbitrarily selected reference gate was measured. The temperature difference between the gates is eliminated by adjusting the corresponding correction volume of the multipoint power controller, and the correction volume is maintained in the adjusted state.

The actual operation of the mold is carried out with the correction volume being maintained in an adjusted state, that is, with all gates being heated to the same temperature, and only the reference gate being at the installed temperature. The heating temperature is feedback-controlled according to the temperature signal detected by the sensor.

In the feedback control of the reference gate, it is natural that the amount of power supplied to the reference gate is adjusted according to the obtained control signal, and the amount of power supplied to all the remaining gates is controlled by the same control signal. Although the adjustment is performed, the respective gates are controlled by the same control amount from the state where the adjustment is set to the same temperature in advance, so that the gates are controlled to the same temperature.

[00016]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an overall perspective view showing an example of an arrangement state of a liner 4 and a gate 5 on a manifold side portion of a multi-cavity mold in which the present invention is implemented.
Four manifolds 3 are arranged and mounted on a base manifold 1 having one nozzle touch 2 at the center of the upper surface.

Each manifold 3 has 16 gates 5
Are fixed vertically and horizontally, and each gate 5 has a liner 4
Is connected to the nozzle touch 2 by the
Is branched in order from the portion connected to the nozzle touch 2 in the base manifold 1 to reach each manifold 3,
Also, each of the manifolds 3 branches in order to reach each gate 5.

The cooling of the manifolds 3 is achieved for each of the manifolds 3. Therefore, the cooling distribution in one of the manifolds 3 is constant. Therefore, the cooling is performed on one surface of the manifold 3 (the lower surface in the illustrated embodiment). The gates 5 arranged in a fixed manner receive a cooling action in accordance with this constant cooling distribution, so that even if a difference occurs in the degree of cooling action received between them, the difference is always constant. .

The gate 5 connected to the molding die 8 composed of a cavity and a core has a coil heater 6 mounted on the outer peripheral surface thereof and a shut-off pin for controlling opening and closing of the flow of the molten resin material from the runner 4. 7.

Each manifold 3 is combined with one temperature controller 9 and one multipoint power controller 10, and the temperature controller 9 is provided with a reference gate 5 arbitrarily selected.
, A temperature signal S1 as a detection signal from a temperature sensor (not shown) attached thereto, and calculates a value of the temperature signal S1 and a preset reference value, and determines a difference between the temperature signal S1 and a control signal S2. Is output to the multipoint power amount adjuster 10.

[0002] The multipoint power amount adjuster 10 has an adjustment volume 11 corresponding to each gate 5 for individually adjusting and setting the amount of electric power supplied to the coil heater 6 mounted on the gate 5. Prior to the actual operation of the mold, the adjustment volume 11 is individually adjusted, and the output signal S3 is set so that the heating temperature of each gate 5 becomes equal and constant.

The adjustment value of each adjustment volume 11 is fixedly held as it is. According to the adjustment value, the feedback control signal S2 for the reference gate 5 is applied to the remaining gate 5 in the feedback control of the reference gate 5. The output signal S3 is used as a control signal.
Control.

Prior to the actual operation of the mold, each correction volume 11 is adjusted so that a temperature sensor is attached to each gate 5 so that the detected value of each temperature sensor becomes equal to a preset set temperature value. It is better to perform the measurement while observing the detection value of this temperature sensor.

[00024]

Since the present invention has the above-described structure, the following effects can be obtained. The heating temperature of each gate in one block is adjusted and set to the same constant value in advance by the correction volume of the multipoint power amount adjuster, and while maintaining this adjustment state, the feedback of the gate temperature of one gate is performed. Since the temperature control of the remaining gates is performed using the control signal of the control, the temperature state of the gates can be equalized with little or no variation in the temperature of each gate. In addition to preventing defects, a uniform product can be stably molded.

In addition, since a large number of gates are divided into blocks in units of one manifold, each gate in one block is under almost the same thermal condition. There is no large temperature difference between the gates, and the temperature of each gate can be controlled accurately and stably.

[Brief description of the drawings]

FIG. 1 is an overall perspective view showing a configuration example of a runner of a manifold side mold for implementing the present invention.

FIG. 2 is an irregular cross-sectional view showing a relationship between a runner and a gate in the configuration example shown in FIG.

FIG. 3 is an enlarged sectional view of a gate portion shown in FIG. 2;

FIG. 4 is a configuration example diagram showing a unit configuration of an apparatus embodying the present invention.

[Explanation of symbols]

 1; Base manifold 2; Nozzle touch 3; Manifold 4; Runner 5; Gate 6; Coil heater 7; Shut-off pin 8; Mold 9; Temperature controller 10; Multipoint power controller 11; Correction volume S1; Temperature signal S2; Control signal S3; Output signal

Continued on front page F term (reference) 4F202 AK09 AP05 AR06 CA11 CB01 CK03 CK06 CK43 CK89 CN01 CN18 CN21 4F206 AK09 AP056 AR066 JA07 JL02 JP13 JP18 JQ81

Claims (1)

[Claims] 1. A hot runner type multi-cavity mold in which a plurality of manifolds (3) are arranged and assembled on one base manifold (1), a heating coil heater (6).
For each of the manifolds (3) having a plurality of gates (5) equipped with
(5) the amount of electric power supplied to the coil heater (6) required to heat and maintain the same constant temperature, the multi-point electric energy regulator (10)
The control signal obtained when the temperature of one of the plurality of gates (5) is feedback-controlled to a constant value is adjusted and set by a correction volume (11) corresponding to each of the gates (5). (S2) A method of controlling gate heating in a multi-cavity mold for controlling the temperature of the remaining gate (5).