JPH07241854A - Mold assembly provided with gas vent - Google Patents

Abstract

PURPOSE:To effectively vent gas and prevent burrs from being caused on a molded article. CONSTITUTION:A vent hole 10 opening to a cavity 3 is provided. A vent passage 11 communicating to the external air is allowed to communicate to the vent hole 10. A movable member 12 to be driven by a cylinder device 13 is slidably provided to the vent hole 10. The movable member 12 opens the vent possage 11 at the start of packing and moves up immediately before completion of packing to close the vent passage 11. At that time, the movable member 12 is continuously connected to the cavity 3. Accordingly, the vent passage 11 is open until the time just before completion of packing of resin, and a vent area can be made larger. Further, since no resin flows into the vent hole 10, no burr is caused on a molded article.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold device used for resin molding, and more particularly to a mold device with a gas vent for removing gas in a cavity.

[0002]

2. Description of the Related Art For example, in injection molding of a thermoplastic resin, a cavity is filled with a molten resin and then cooled and solidified to form a cavity-shaped product. Therefore, gas generated from the molten resin exists in the cavity in addition to gas such as air. If the air and the generated gas (hereinafter, simply referred to as gas) are not removed together with the filling of the molten resin, the gas in the cavity is compressed by the filling of the molten resin, and the resin filling failure occurs due to the increase of the internal pressure of the cavity. Furthermore, the gas in the cavity is instantaneously adiabatically compressed and reaches a high temperature of 600 ° C. or higher, causing various problems such as burning of the molded product.

In order to eliminate such obstacles, the conventional mold device is provided with a gas vent for removing the gas in the cavity to the outside of the mold. As an example of this gas vent, one or more concave grooves communicating with the cavity are formed in the parting surface where the fixed-side mold member and the movable-side mold member are butted against each other, and the gas in the cavity is discharged from the concave groove. A gas vent structure is known in which the gas is vented and the gas is vented to the outside from a deeper venting passage.

[0004]

In the above-mentioned gas vent having the concave groove for removing gas on the parting surface, when the molten resin flows into the concave groove, this remains as a burr on the product. In order to prevent this, generally, the depth of the concave groove can be formed only to a very small depth of about 0.005 to 0.03 mm, and if the vent area cannot be made large in this way, the gas gradually increases from the concave groove. Since the gas only escapes, the rate of filling the resin becomes faster than the rate of gas escape, and as a result, the problems such as the defective filling of the resin and the burning of the molded product still remain.

The present invention is intended to solve such a problem and efficiently eliminates the gas in the cavity,
Moreover, it is an object of the present invention to provide a mold device with a gas vent capable of preventing burrs from remaining on a product.

[0006]

In order to achieve the above-mentioned object, a mold device with a gas vent according to claim 1 of the present invention has a plurality of molds which are movable and which form a cavity inside during mold clamping. A member, a gas vent hole that opens into the cavity to vent the gas in the cavity to the outside of the mold member, and an opening / closing member that closes the gas vent hole immediately before the completion of the resin filling in the cavity Is.

According to a second aspect of the present invention, there is provided a die vent-equipped mold apparatus, wherein the opening / closing member is a movable member fitted into the gas vent hole so as to be movable, and the movable member is the cavity. Immediately before the completion of the filling of the resin inside, it is arranged so as to be continuously connected to the cavity.

According to a third aspect of the present invention, there is provided a mold device with a gas vent, wherein the opening / closing member is fitted in the gas vent hole so as to be movable, and the opening / closing pin is provided so as to be retractable in the cavity. A spring for projecting the opening / closing pin into the cavity is provided on the lower surface side of the opening / closing pin, and a passage communicating with the gas vent hole at the upper limit position of the opening / closing pin is provided on the outer peripheral surface of the opening / closing pin. It is arranged so as to be continuously connected to the cavity by the resin pressure filled in the cavity.

According to a fourth aspect of the present invention, there is provided a gas vent mold apparatus, wherein the opening / closing member is constituted by a slide member movably provided in a different direction with respect to the opening / closing direction of the mold member. The cavity is formed inside the member and the mold member, the slide member is provided with a communication hole communicating with the gas vent hole when the slide member is opened, and the slide member is filled with the resin in the cavity. It was closed just before the completion.

[0010]

In the mold apparatus with the gas vent according to the first aspect of the present invention, when the cavity is filled with the resin, the gas vent hole is opened until just before the completion of the filling of the resin. With the resin filling of
It goes out of the die member through the gas vent hole. For this reason, a large vent area can be taken until just before the resin is completely filled, and a large amount of gas can be vented.

In the mold apparatus with a gas vent according to the second aspect of the present invention, the movable member is continuously connected to the cavity to close the gas vent hole immediately before the resin is completely filled in the cavity. Resin does not enter the degassing hole when filling is completed. For this reason, burrs do not occur in the product.

Further, in the mold apparatus with a gas vent according to a third aspect of the present invention, when the cavity is filled with the resin, the opening / closing pin is moved into the cavity by a spring until the resin reaches the opening / closing pin. The gas is released from the cavity through the passage formed on the outer peripheral surface of the opening / closing pin and the gas vent hole, and the gas in the cavity escapes to the outside of the mold member through the passage of the opening / closing pin and the gas vent hole. When the resin in the cavity reaches the opening / closing pin, the opening / closing pin is pushed down by the resin pressure flowing into the cavity to close the gas vent, so that a special drive source for operating the opening / closing pin is unnecessary.

Further, in the mold apparatus with a gas vent according to a fourth aspect of the present invention, when the cavity is filled with the resin, the communication hole of the slide member and the gas vent hole are in communication with each other, and the gas in the cavity is connected. Goes out of the mold member as the molten resin is filled. The slide member is closed to form the product cavity immediately before the cavity 3 is completely filled with the molten resin, so that no trace of the gas vent hole formed facing the product is left.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a mold apparatus with a gas vent according to the present invention will be described below with reference to FIGS. The mold device comprises a fixed mold member 1 and a movable mold member 2. These mold members 1 and 2 move in the vertical direction in the drawing to open and close, and when the mold is clamped, a product shape The cavity 3 is formed. Further, a resin passage 4 is formed in the fixed-side mold member 1, and the resin passage 4
Has a gate 5 opened at the tip end so as to face the cavity 3, and the molten resin fed from the injection molding machine 6 is filled in the cavity 3 from the gate 5 through the resin passage 4. A valve device 8 having a valve pin 7 at its tip is provided in the resin passage 4, and the valve pin 7 is fitted into the gate 5 to open and close the gate 5. Further, the movable mold member 2 is provided with a gas vent 9 for venting the gas in the cavity 3. The gas vent 9 faces the cavity 3 and penetrates vertically in the drawing, and a gas vent passage having one end communicating with the gas vent hole 10 and the other end opening to the side surface of the movable mold member 2. It consists of 11 and. A movable member 12 is slidably guided as an opening / closing member in the gas vent hole 10, and the movable member 12 uses a cylinder device 13 as a drive source. In this embodiment, the piston rod of the cylinder device 13 is a movable member.
12 When the molten resin is filled in the cavity 3, the cylinder device 13 causes the movable member 12 to stand by below the degassing passage 11 in the drawing. As a result, the gas vent hole 10 and the gas vent passage 11 communicate with each other, and the gas vent 9
Opens. On the other hand, in order to close the gas vent 9, the movable member 12 is raised by the cylinder device 13, and the gas vent passage 11 is closed by the movable member 12. The movable member 12 with the gas vent passage 11 blocked by the movable member 12
At the position of, the tip surface of the movable member 12 and the inner surface of the cavity 3 of the movable-side mold member 2 are continuously connected. That is, when the gas vent 9 is closed, the movable member 12 constitutes a part of the cavity 3. As shown in FIG. 1, the cylinder device 13 that drives the movable member 12 is controlled by the control unit 15 including the timer means 14, and when the injection molding machine 6 is driven, its injection start signal is sent to the timer means 14. A signal is output to the control unit 15 after a lapse of a predetermined time from the start of injection of the injection molding machine 6 by the feeding and timer means 14, and the cylinder device 13 is driven based on this signal. In this case, the time from the start of injection of the injection molding machine 6 by the timer means 14 to the driving of the cylinder device 13 is the time from the start of the filling of the molten resin into the cavity 3 to immediately before the completion of the filling. That is, the time from the start of injection of the injection molding machine 6 until the molten resin is completely distributed in the cavity 3 is constant depending on the volume of the cavity 3, and based on this time, the timer means 14 accurately measures the cylinder device immediately before the completion of filling. The movable member 12 is driven to close the gas vent 9 by the movable member 12. As another means for controlling the hydraulic cylinder device 13 to be driven immediately before the completion of the filling of the molten resin, instead of the above-mentioned timer means 14, as shown in FIG. 3, the molten resin is finally filled. A sensor 16 for detecting the molten resin, which is located slightly closer to the gate 5 than the gas vent hole 10, is provided close to the cavity 3, and the control unit 15 can drive the cylinder device 13 by a detection signal from the sensor 16. it can. In this way, by controlling the cylinder device 13 based on the detection signal of the sensor 16, the cylinder device 13 can be driven more reliably just before the completion of resin filling, and as a means for controlling the drive timing of the cylinder device 13. Whether to use the timer means 14 or the sensor 16 may be appropriately selected.

Next, the operation of the above configuration will be described. During molding, the fixed mold member 1 and the movable mold member 2
With the molds clamped and the valve pin 7 raised to open the gate 5, the molten resin is injected from the nozzle (not shown) of the injection molding machine 6. This resin passes through the resin passage 4 and
It flows into the cavity 3 from the opened gate 5. Immediately after starting the injection of the injection molding machine 6, as shown in FIG. 1, the movable member 12 that opens and closes the gas vent 9 has a degassing passage.
Located on the lower side of the drawing than the reference numeral 11, the gas in the cavity 3 flows out of the movable mold member 2 from the gas vent passage 11 through the gas vent hole 10 together with the filling of the molten resin. Thereafter, as shown in FIG. 2, immediately before the molten resin in the cavity 3 is completely filled, the cylinder device 13 is driven based on a signal from the timer means 14 shown in FIG. 1 or the sensor 16 shown in FIG. Then, the movable member 12 is raised. When the movable member 12 is raised in this manner, the tip end surface of the movable member 12 is continuously connected to the cavity 3, and the movable member 12 blocks the gas vent passage 11 and the gas vent 9. When the resin filling in the cavity 3 is completed,
The valve pin 7 is lowered in the figure to close the gate 5. After that, the fixed side mold member 1 and the movable side mold member 2 are opened with the resin filled in the cavity 3 solidified, and the solidified product is taken out.

As described above, according to the configuration of the above embodiment, the gas in the cavity 3 escapes from the gas vent hole 10 and the gas vent passage 11 and is vented until just before the molten resin in the cavity 3 is completely filled. The large area allows for a large amount of degassing. Moreover, since the front end surface of the movable member 12 and the inner surface of the cavity 3 are continuously connected immediately before the molten resin in the cavity 3 is completely filled, the resin does not flow into the gas vent hole 10, so that the product does not burr. Does not remain.

FIG. 4 and FIG. 5 show a second embodiment of the present invention. The same parts as those of the first embodiment are designated by the same reference numerals, and the detailed description thereof will be omitted. In the second embodiment, an opening / closing member for opening / closing the gas vent 9 is provided as the gas vent hole 10
The opening / closing pin 20 is slidably mounted along the opening / closing pin 20. A flange portion 21 is formed on the lower peripheral edge of the opening / closing pin 20, and the flange portion is formed on the lower peripheral edge of the gas vent hole 10.
A recess 22 that houses 21 is formed. Further, the fixed plate 23 to which the fixed-side mold member 1 is attached is provided with a recessed recess 25 having a diameter smaller than that of the recess 22, corresponding to the recess 22.
A spring 24 for urging the opening / closing pin 20 is housed inside the recess 25. That is, the opening / closing pin 20 is arranged such that the flange portion 21 abuts on the step portion 22 a of the concave portion 22 by the spring 24 in the concave portion 25, and the tip end portion of the opening / closing pin 20 projects into the cavity 3. In this manner, in the state where the tip end portion of the opening / closing pin 20 projects into the cavity 3, a groove-shaped passage 26 that connects the cavity 3 and the degassing passage 11 is formed on the outer peripheral surface of the opening / closing pin 20. As shown in FIG. 4, the protrusion amount t of the opening / closing pin 20 in the cavity 3 is equal to the distance t1 between the flange portion 21 and the fixed plate 23, and
As the spring 24 for urging the opening / closing pin 20, a spring having a strength to be compressed by the resin pressure filled in the cavity 3 is used. That is, when the molten resin is filled in the cavity 3, the opening / closing pin 20 abuts the flange portion 21 of the opening / closing pin 20 against the step portion 22a by the spring 24 at the start of filling the molten resin so that the tip end portion of the opening / closing pin 20 is in the cavity 3 It projects inside. Thus, in the state where the opening / closing pin 20 projects into the cavity 3, as shown in FIG. 4, the cavity 3 and the degassing passage 11 communicate with each other by the passage 26 formed on the outer peripheral surface of the opening / closing pin 20, When the cavity 3 is filled with the molten resin, the gas in the cavity 3 is removed from the degassing passage 11 through the passage 26. After this, the filling of the molten resin in the cavity 3 proceeds, and immediately before the molten resin is completely filled in the cavity 3, that is, when the molten resin reaches the opening / closing pin 20,
The opening / closing pin 20 is pushed down against the urging force of the spring 24 by the resin pressure filled in the cavity 3. When the cavity 3 is completely filled with the molten resin, the lower end portion of the flange portion 21 of the opening / closing pin 20 abuts the fixing plate 23, as shown in FIG. At this time, the tip surface of the movable member 12 and the inner surface of the cavity 3 are continuously connected, and the gas vent passage 11 is closed by the opening / closing pin 20 and the gas vent 9 is closed. When the fixed side mold member 1 and the movable side mold member 2 are opened to take out the product which is the resin solidified in the cavity 3, the opening / closing pin 20 is returned by the spring 24.

As described above, according to the configuration of the above-described embodiment, the gas in the cavity 3 is discharged from the passage 26 of the opening / closing pin 20 and the degassing passage 11 until just before the molten resin in the cavity 3 is completely filled. It is possible to escape and release a large amount of gas.
Further, since the tip end surface of the movable member 12 and the cavity 3 are continuously connected immediately before the molten resin in the cavity 3 is completely filled, no burrs are left on the product. Further, in this embodiment, since the opening / closing pin 20 for opening / closing the gas vent passage 11 is operated by the resin pressure filled in the cavity 3,
The cylinder device 13 for driving the open / close pin 20 and the control means for the cylinder device 13 as in the first embodiment are not required. For this reason, the structure is simple, and moreover, the opening / closing pin 20 can be surely continuously connected to the cavity 3 immediately before the molten resin is completely filled in the cavity 3.

FIG. 6 shows a third embodiment of the present invention. The same parts as those of the first embodiment are designated by the same reference numerals, and the detailed description thereof will be omitted. In the present embodiment, an opening / closing member for opening / closing the gas vent 9 is constituted by a plate-shaped slide member 30 that moves to the left and right in the drawing with respect to the opening / closing direction of the fixed mold member 1 and the movable mold member 2. The slide member 30 is slidably guided by a cylinder device 13 along a groove 31 formed on a parting surface of the movable mold member 2. Then, at the time of mold clamping, the fixed side mold member 1, the movable side mold member 2 and the slide member 30 form a cavity 3, and the slide member 30 has a slide member.
A communication hole (32) is formed which communicates with the gas vent hole (10) when the opening (30) is opened.

Then, the fixed mold member 1 and the movable mold member 2 are clamped, and the cavity 3 of each of these mold members 1 and 2 is filled with molten resin. At the start of filling the molten resin, the slide member 30 is open.
The communication hole 32 and the gas vent hole 10 communicate with each other. Therefore, when the molten resin is filled, the gas in the cavity 3 is removed from the gas vent passage 11 through the communication hole 32 and the gas vent hole 10. After this, immediately before the molten resin is completely filled in the cavity 3, the cylinder device 13 is driven by the timer means 14 shown in FIG. 1 or the sensor 16 shown in FIG. To close the gas vent hole 10 and close the gas vent 9. As described above, in the mold clamping state in which the gas vent hole 10 is blocked by the slide member 30, the fixed side mold member 1, the movable side mold member 2 and the slide member 30 form the cavity 3. Then, in a state where the resin filled in the cavity 3 is solidified, the fixed side mold member 1 and the movable side mold member 2 are opened to take out the solidified product.

As described above, according to the configuration of this embodiment,
As in the above-described embodiment, the gas in the cavity 3 escapes from the communication passage 32 of the slide member 30 until just before the molten resin in the cavity 3 is completely filled, so that a large amount of gas can be released and the molten resin Since the gas vent hole 10 is closed by the slide member 30 immediately before being completely filled, burrs do not remain on the product. Moreover, in this embodiment, the slide member 30
Since the cavity 3 is formed by the fixed-side mold member 1, the movable-side mold member 2, and the slide member 30 in a state where the gas vent hole 10 is closed by the gas vent hole 10 that opens to the product facing the cavity 3. No trace of

The present invention, which has been described in detail with respect to each embodiment of the present invention, is not limited to the above-mentioned embodiments, and various modifications can be made within the scope of the present invention. For example, although the valve gate type mold is shown as the mold device of each of the above-described embodiments, the basic structure of the mold device may be set appropriately. Further, although the hydraulic cylinder device is used as the drive source in the first and third embodiments, various drive sources such as a motor may be used. Furthermore, in the third embodiment, the slide member has a thin plate shape. Although the one used was used, its shape may be appropriately set.

[0023]

According to the die apparatus with a gas vent according to the first aspect of the present invention, a plurality of mutually movable die members that form cavities inside when the die is clamped, and a cavity that is opened in the cavities. By providing a gas vent hole for venting the gas inside the mold member to the outside of the mold member and an opening / closing member for closing the gas vent hole immediately before the completion of the filling of the resin in the cavity, the cavity is held until just before the filling of the resin is completed. The gas inside escapes when the resin is filled, and gas can be efficiently released.

Further, according to the mold apparatus with a gas vent according to a second aspect of the present invention, the opening / closing member is constituted by a movable member fitted to the gas vent hole so as to be movable.
Since the movable member is arranged so as to be continuously connected to the cavity immediately before the filling of the resin in the cavity is completed, the resin does not flow into the gas vent hole, so that no burr remains on the product.

According to the mold apparatus with a gas vent according to a third aspect of the present invention, the opening / closing is provided so that the opening / closing member is fitted in the gas vent hole so as to be movable and to be retractable in the cavity. The opening and closing pin is provided with a spring for projecting the opening and closing pin into the cavity, and the opening and closing pin is provided with a passage communicating with the gas vent hole at the upper limit position of the opening and closing pin. Since the pin is arranged so as to be continuously connected to the cavity by the resin pressure filled in the cavity, a special drive source for operating the opening / closing pin is not required.

According to a fourth aspect of the present invention, there is provided a die vent-equipped mold apparatus, wherein the opening / closing member is constituted by a slide member movably provided in different directions with respect to the opening / closing direction of the mold member. The cavity is formed inside the member and the mold member, and the slide member is provided with a communication hole that communicates with the gas vent hole when the slide member is opened. By closing just before the completion of filling, there is no trace of a vent hole that opens into the cavity in the product.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a mold showing a molding state immediately after the start of filling according to a first embodiment of the present invention.

FIG. 2 is a sectional view of the mold showing a molding state just before the completion of filling.

FIG. 3 is a sectional view of a mold showing a modified example of the control means of the cylinder device.

FIG. 4 is a cross-sectional view of a mold showing a molding state immediately after the start of filling according to the second embodiment of the present invention.

FIG. 5 is a sectional view of the mold showing a molding state when the filling is completed.

FIG. 6 is a sectional view of a mold showing a third embodiment of the present invention.

[Explanation of symbols]

 1 Fixed-side mold member (mold member) 2 Movable-side mold member (mold member) 3 Cavity 9 Gas vent 10 Gas vent hole 12 Movable member (open / close member) 20 Open / close pin (open / close member) 24 Spring 26 Passage 30 Slide Member (opening / closing member) 32 communication hole

Claims (4)

[Claims] 1. A plurality of mutually movable mold members that form a cavity inside when the mold is clamped, and a gas vent hole that opens into the cavity to vent gas inside the cavity to the outside of the mold member. A mold device with a gas vent, which is provided with an opening / closing member that closes the gas vent hole immediately before the completion of filling the resin in the cavity. 2. The opening / closing member is constituted by a movable member which is fitted in the gas vent hole so as to be movable, and the movable member is continuously connected to the cavity just before the completion of the resin filling in the cavity. The mold device with a gas vent according to claim 1, wherein the mold device is equipped with a gas vent. 3. The opening / closing member is constituted by an opening / closing pin fitted in the gas vent hole so as to be movable and capable of retracting into / from the cavity, and the opening / closing pin is provided on the lower surface side of the opening / closing pin in the cavity. And a passage communicating with the gas vent hole at the upper limit position of the open / close pin, and the open / close pin is continuously connected to the cavity by the resin pressure filled in the cavity. The mold device with a gas vent according to claim 1, wherein the mold device is equipped with a gas vent. 4. The opening / closing member is constituted by a slide member movably provided in a direction different from the opening / closing direction of the mold member, and the cavity is formed inside the slide member and the mold member. 2. The slide member according to claim 1, wherein the slide member is provided with a communication hole that communicates with the gas vent hole when the slide member is opened, and the slide member is closed immediately before the completion of the filling of the resin in the cavity. Mold device with gas vent.