JP3914477B2 - 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, in the gate type injection molding, there is obtained a so-called molded product with a gate in which the resin of the gate portion of the injection mold remains in the molded product, and this gate portion needs to be removed, which is troublesome.
[0004]
Recently, a fixed mold and a movable mold that can be freely opened and closed are used to eliminate these drawbacks. The fixed cavity and the mold cavity formed by the movable mold and the nozzle provided in the fixed mold are the hot runner method. The injection mold is communicated with the resin flow path, and the fixed mold is provided with a hot runner block in which a resin passage is provided and a resin passage in communication with the resin passage is provided in the fixed mold. The gate bush is installed in the moving mold direction, and an injection mold is used in the resin passage in the gate bush so that the valve pin can open and close the gate of the gate bush. It is coming.
[0005]
In the above injection mold, a gateless molded product can be obtained by closing the gate by advancing the valve pin to the back (exit) of the gate of the gate bush.
[0006]
However, since the injection mold is a hot runner method, the hot runner block becomes hot, so the cylinder for moving the valve pin back and forth is installed with a recess in the fixed mold (or fixed mold plate). The valve pin was slidably inserted into the through hole of the valve pin guide fitted in the hot runner block.
[0007]
Since the valve pin guide is simply inserted into the hot runner block, the leveling accuracy is poor and the valve pin becomes long. Therefore, the thermoplastic resin heated and pressurized is inserted into the gate bush so that it can be moved forward and backward without leaking. This makes it difficult to cause troubles such as the valve pin biting into the valve pin guide during operation. In addition, the fixed mold (or the fixed mold plate) has to be provided with a recess for installing the cylinder, which increases the cost.
[0008]
[Problems to be solved by the invention]
In view of the above-mentioned drawbacks, the object of the present invention is that the leveling accuracy of the valve pin guide is good, and the valve pin can be inserted into the gate bush so that the thermoplastic resin heated and pressurized can be freely advanced and retracted without any trouble during operation. The object is to provide an injection mold that is unlikely to occur.
[0009]
[Means for Solving the Problems]
Injection mold according to claim 1 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 , an injection mold that are communicated with the resin flow path of the hot runner system, the above-mentioned fixed type is installed the hot runner block in which the resin passage disposed therein is a resin passage communicating with said resin passage There is a gate bushing disposed therein is placed in the mobile direction, the resin passageway in the gate bush are installed valve pin, the valve pin is in the installed cylinder the hot runner block or fixed, as can the gate of the gate bush opened and closed, are movably connected, and, to a screw hole formed on the upper surface of the hot runner block, Characterized in that it is slidably inserted into the through hole of the fixed valve pin guide by screwing the screws that Kira in circumference.
[0010]
The injection mold according to claim 2 is the injection mold according to claim 1, wherein the cylinder is installed on the hot runner block via a heat insulating member, and is heated and pressurized. The valve pin can be inserted into and retracted from the gate bush without leakage of molten thermoplastic resin, and trouble during operation is less likely to occur.
[0011]
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, and FIG. 2 is a cross-sectional view showing a hot runner portion.
[0012]
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.
[0013]
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, a plurality of valve pins 16, 16, and a plurality of valve pin guides 17, 17. Reference numeral 131 denotes a band heater wound around the nozzle 13 in order to heat the nozzle 13.
[0014]
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.
[0015]
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.
[0016]
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. Reference numeral 151 denotes a cylindrical pedestal, and reference numeral 153 denotes a cylinder fixing plate on which a heat insulating material 152 is laminated. The heat insulating member is formed of a cylinder fixing plate 153 in which a cylindrical leg column 151 and a heat insulating material 152 are laminated.
[0017]
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.
[0018]
That is, the cylinder 15 is fixed to the upper surface of the hot runner block 12 via the cylindrical leg column 151, the heat insulating material 152 and the cylinder fixing plate 152. By doing so, it is possible to prevent the cylinder 15 from becoming hot even when the hot runner block 12 becomes hot.
[0019]
Reference numeral 17 denotes a valve pin guide which is threaded around and has a through hole. The valve pin guide 17 is screwed into the screw hole of the hot runner block 12 that is screwed so as to be screwed into the screw of the valve pin guide 17.
[0020]
Further, the valve pin guide 17 is screwed so that its through hole corresponds to the cylinder 15 and is parallel to the gate bush 14, and the thickness of the through hole does not leak the molten thermoplastic resin. The thickness is such that the valve pin 16 can be slidably inserted.
[0021]
The valve pins 16, 16 are slidably inserted into the through holes of the valve pin guide 17, pass through the resin passage 121 and the resin passage 141, and the cylinder 15, When the thermoplastic resin is not supplied, the valve pin 16 is inserted into the gate 142 to close the gate 142, and the thermoplastic resin is supplied from the gate 142. The valve pin 16 is pulled out and the gate 142 is opened.
[0022]
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.
[0023]
Reference numeral 143 denotes a band heater for heating the gate bush 14.
[0024]
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.
[0025]
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.
[0026]
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.
[0027]
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.
[0028]
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. .
[0029]
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.
[0030]
【The invention's effect】
Since the configuration of the injection molding die of the present invention is as described above, the leveling of the valve pin guide is performed with high precision, and the thermoplastic resin heated and pressurized with the valve pin on the gate bush does not leak, and The valve pin can be inserted into the valve pin guide so that it can move forward and backward, and troubles are unlikely to occur during operation.
[0031]
In addition, if the cylinder that moves the valve pin back and forth is installed in the hot runner block, the device can be downsized, the manufacturing cost of the device can be reduced, and the distance between the cylinder and the valve pin guide can be shortened. So that troubles are less likely to occur during operation. Therefore, an injection molded product can be manufactured efficiently at low cost.
[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.
[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 15 Cylinder 151 Cylindrical pedestal 152 Thermal insulation 153 Cylinder fixed board 16 Valve pin 17 Valve pin guide 2 Mobile mold 21 Mobile mold board 22 Protrusion board 23 Protruding pin 3 Molding cavity 121, 141, 31 Resin passage

Claims (2)

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 a injection mold are, in the fixed type, hot runner block is installed that the resin passage is internally provided, the gate bushing resin passage communicating with said resin passage disposed therein is mobile direction is installed in, the resin passage in the gate bush are installed valve pin, the valve pin is in the installed cylinder the hot runner block or fixed, as may the gate of the gate bush opened and closed in, which is movably connected, and, to a screw hole formed on the upper surface of the hot runner block, screwing the screws that Kira around Injection mold, characterized by being slidably inserted into more through holes of the fixed valve pin guide.   The injection mold according to claim 1, wherein the cylinder is installed on the hot runner block via a heat insulating member.

Images