JP3913630B2 - Injection mold - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an injection mold.
[0002]
[Prior art]
Since injection molding is suitable for mass production of thermoplastic resin molded products, it is applied to the production of various molded products. Large-scale products such as automotive instrument panels and radiator grills are also manufactured by injection molding, but those that use a large amount of thermoplastic resin are generally injection molds that have multiple gates using the hot runner method. Manufacture.
[0003]
However, the larger the product to be manufactured, the more difficult it is to supply the thermoplastic resin uniformly into the cavity, and it was difficult to obtain a product having uniform strength.
[0004]
That is, in the hot runner type injection molding die, the molten thermoplastic resin is injected while heating the resin passage for supplying the molten resin from the nozzle to the molding cavity, so that all the resin passages are not kept at a uniform temperature. Further, it becomes difficult to uniformly supply the thermoplastic resin into the cavity, and a product having uniform strength cannot be obtained.
[0005]
However, after the mold is supplied with molten thermoplastic resin to the molding cavity, the mold is opened to take out the injection molded product, so that the temperature of the gate part is lower than the other resin passage parts, and the viscosity of the molten thermoplastic resin The viscosity of the molten thermoplastic resin between the gates tends to vary depending on the position of each gate.
[0006]
Therefore, it becomes difficult to accurately control the amount of molten thermoplastic resin supplied from each gate, and in particular, in the case of a large product requiring many gates, it is possible to obtain a product having uniform strength as a whole. It was difficult.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to provide a hot runner type injection mold in which the temperature control of the gate is easy and the supply amount of the molten thermoplastic resin can be accurately controlled in view of the above drawbacks. There is.
[0008]
Injection mold of the present invention is made of fixed and openable to the installed mobile, a mold cavity formed by the fixed mold and the moving mold, a nozzle provided in the fixed mold, hot runner a injection mold which communicates with a resin flow path system, the above-mentioned fixed type, a gate bush resin passage disposed therein is placed in the mobile direction, the resin passageway in the gate bush, with its lower end communicates with the gate formed on the tip portion of the gate bush tapers, as in the inside resin passage of the gate bush may the gate of the gate bush opened and closed, reciprocating freely valve pin is installed, the groove holes in the vicinity of the gate of the outer wall of the gate bush is formed, contact outwardly tapered and become part of the resin passage of the gate bush The and thermocouple groove hole is a band heater disposed so as to surround the periphery thereof with embedded, the outer wall of the gate bush, band heaters at predetermined intervals in the moving direction of the moving type winding that It is characterized by being turned .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
An injection mold according to the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an example of an injection mold according to the present invention, FIG. 2 is a cross-sectional view showing a hot runner portion, and FIG. 3 is a cross-sectional view showing a tip portion of a gate bush.
[0010]
The injection mold of the present invention comprises a fixed mold 1 and a movable mold 2, and the movable mold 2 is installed so as to move in the vertical direction in the drawing and open and close the mold. Reference numeral 3 denotes a molding cavity. The molding cavity 3 is formed by clamping the fixed mold 1 and the movable mold 2.
[0011]
The fixed mold 1 includes a fixed mold plate 11, a hot runner block 12, a nozzle 13, a plurality of gate bushes 14, 14, a plurality of cylinders 15, 15, and a plurality of valve pins 16, 16. Reference numeral 131 denotes a band heater wound around the nozzle 13 in order to heat the nozzle 13.
[0012]
The hot runner block 12 is provided with a resin passage 121 therein and is fixed horizontally (horizontal in the drawing) with respect to the fixed mold plate 11. The nozzle 13 is installed at the approximate center of the upper surface of the hot runner block 12 so as to communicate with the resin passage 121.
[0013]
Gate bushes 14 and 14 are installed at predetermined positions on the lower surface of the hot runner block 12 in the moving direction of the movable mold 2. A resin passage 141 is provided inside the gate bush 14, an upper end portion of the resin passage 141 communicates with a resin passage 121 provided in the hot runner block 12, and a lower end portion thereof is tapered to be a distal end portion of the gate bush 14. The gate 142 is connected to the gate 142.
[0014]
The cylinders 15 and 15 are installed at positions corresponding to the gate bushes 14 and 14 on the upper surface of the hot runner block 12. A plurality of cylindrical leg columns 151 are erected on the hot runner block 12, and a cylinder fixing plate 153 is installed on the cylindrical leg column 151, and the cylinder 15 is installed on the cylinder fixing plate 153 via a heat insulating material 152. ing.
[0015]
That is, the cylinder 15 is fixed to the upper surface of the hot runner block 12 via the cylindrical leg column 151, the cylinder fixing plate 153, and the heat insulating material 152. By doing so, it is possible to prevent the cylinder 15 from becoming hot even when the hot runner block 12 becomes hot.
[0016]
The valve pins 16, 16 pass through the resin passage 121 and the resin passage 141, and are installed in the cylinders 15, 15 so as to be able to move forward and backward so that their tip portions are located in the vicinity of the gate 142 of the gate bush 14. Thus, when the thermoplastic resin is not supplied, the valve pin 16 is inserted into the gate 142 and the gate 142 is closed, and when the thermoplastic resin is supplied, the valve pin 16 is pulled out from the gate 142 and the gate 142 is opened.
[0017]
A concave groove 144 is formed in the outer wall near the tip of the gate bush 14 (near the gate), and the thermocouple 4 is embedded in the concave groove 144. A band heater 143 is wound around the valve pin 16 to the vicinity of the tip of the gate bush 14. The thermocouple 4 is connected to a control device (not shown), and the band heater 143 is controlled by a signal from the control device according to the temperature measured by the thermocouple 4.
[0018]
The cylinders 15 and 15 are connected to a control device (not shown), and the advance and retreat of the valve pins 16 and 16 are controlled by signals from the control device. That is, according to the shape of the molding cavity 3, the amount of thermoplastic resin supplied from each gate bush 14 to the molding cavity is adjusted, the timing, time, etc. for opening and closing the gate 142 are determined and input to the control device. Then, the thermoplastic resin is uniformly supplied to the molding cavity 3 by advancing and retracting the valve pin 16 by a signal from the control device. As a result, an injection molded product having a uniform strength can be manufactured.
[0019]
The movable mold 2 includes a movable mold plate 21, a projecting plate 22 installed on the movable mold plate 21 so as to be movable back and forth, and a projecting pin 23 fixed to the projecting plate 22. The protruding pin 23 is inserted into a through hole formed in the movable mold plate 21 so as to correspond to the gate 142 of the gate bush 14.
[0020]
Next, a method for injection molding with the injection mold of the present invention will be described.
First, the valve pins 16 and 16 are advanced, and the mold 3 is clamped to form the cavity 3 with the gates 142 and 142 of the gate bushes 14 and 14 closed.
[0021]
Next, molten thermoplastic resin is supplied from the nozzle 13, and the cylinder 15 is operated according to a signal from the control device, the valve pin 16 is moved backward, and the gate 142 of the gate bush 14 is opened. Further, the band heater 143 is controlled by a signal from the control device according to the temperature measured by the thermocouple 4.
[0022]
At this time, the gate 142 of the gate bush 14 at a position where a large amount of thermoplastic resin should be supplied should be opened early, and the gate 142 of the gate bush 14 at a position where a small amount of thermoplastic resin should be supplied should be opened late.
[0023]
When the opening 142 of the gate bush 14 is opened, the nozzle 13 is communicated with the molding cavity 3 through the resin passages 121, 141 and 31, and the molten thermoplastic resin supplied from the nozzle 13 is filled into the molding cavity 3. .
[0024]
After filling the molten thermoplastic resin, the cylinder 15 is operated in accordance with a signal from the control device, the valve pin 16 is moved forward, the gate 142 of the gate bush 14 is closed, and after cooling the filled thermoplastic resin, the mold is molded. Open the projecting plate 22 and projecting pin 23 to take out the molded product.
[0025]
【The invention's effect】
Since the structure of the injection mold of the present invention is as described above, the temperature of the gate bush, particularly in the vicinity of the gate tip, can be accurately controlled, and the viscosity of the molten thermoplastic resin can be accurately controlled. Can be supplied accurately and stably. Therefore, even if it is a large molded article, a product having a uniform strength as a whole can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of an injection mold according to the present invention.
FIG. 2 is a cross-sectional view showing a hot runner portion.
FIG. 3 is a cross-sectional view showing a front end portion of a gate bush.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fixed type | mold 11 Fixed type | mold board 12 Hot runner block 13 Nozzle 14 Gate bush 142 Gate 143 Band heater 144 Concave groove hole 15 Cylinder 151 Cylindrical pedestal 152 Thermal insulation 153 Cylinder fixed board 16 Valve pin 2 Mobile mold 21 Mobile mold board 22 Protrusion Plate 23 Projection pin 3 Molding cavity 121, 141, 31 Resin passage 4 Thermocouple

Claims (1)

Consists fixed and openably installed a mobile, a molding cavity formed by the fixed mold and the moving mold, nozzles provided in the fixed type, in communication with the resin flow path of the hot runner system The fixed mold is provided with a gate bush in which a resin passage is provided in the moving mold direction, and the resin passage of the gate bush is tapered at the lower end thereof. with and communicates with a gate formed at the tip portion of the bush, in the resin passage of the gate bush, as can the gate of the gate bush opened and closed, retractably a valve pin is installed, the groove holes in the vicinity of the gate of the outer wall of the gate bush is formed, thermocouple to the recessed groove holes in the outer tapered and become part of the resin passage of the gate bush Embedded and band heaters so as to surround the periphery thereof is disposed with being in the outer wall of the gate bush, characterized in that the band heater at predetermined intervals in the moving direction of the mobile is wound Injection mold.

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