JP6274408B2 - Method for discharging gas in mold and molding mold to which the method is applied - Google Patents

Description

The present invention relates to an in-mold gas discharge method for discharging gas from a mold internal space into which a molding material made of molten metal, molten resin, or the like is injected, and a molding die to which the method is applied.

When molding is performed using a molding die, gas is discharged from the space in the die to suppress the occurrence of short shots and gas burns. The gas is discharged when the molding material is filled, and specific examples thereof are described in Patent Documents 1 and 2.
Patent Document 1 describes a technique for opening a gas vent hole to discharge gas when the gas pressure in the cavity exceeds a predetermined pressure, and Patent Document 2 is installed so as to protrude into the cavity. It is described that a gas is discharged by providing a notch in the protruding pin.

JP-A-9-277310 JP 2002-1776 A

However, in the gas discharge methods described in Patent Documents 1 and 2, there is still a problem that a molding defect that occurs because the gas cannot be smoothly discharged from the cavity still occurs. And it is considered that the inflow of gas into the cavity is not suppressed, and this point is not limited to the case where the molding material is a molten resin. For example, the molding material is melted. The same applies to the case of a metal.
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a gas discharge method in a mold that suppresses the inflow of gas into a cavity and discharges the gas, and a molding die to which the method is applied. And

According to the first aspect of the present invention, the in-mold gas discharge method includes a material supply path provided with a molding material injection port and a gas discharge port, and a cavity connected to the material supply path. Dividing the space in the mold along the flow of the molding material at a shielding position downstream of the gas discharge port and upstream of the cavity; and from the injection port into the material supply path A step B of injecting the molding material and sending the gas upstream of the shielding position in the material supply path to the outside through the gas discharge port without flowing into the cavity; the by releasing the state of being divided at the shielding position, the molding material have a step C that allows flow into the cavity, the gas outlet, the switching means for dividing the mold space The opening / closing means is formed in front Molding material is moved by receiving a force from the molding material in contact with the closing means to release the state of dividing the mold space.

A molding die according to a second aspect of the present invention that meets the above-described object includes a mold inner space including a material supply path provided with an injection port for a molding material and a cavity connected to the material supply path. In the molding die, a gas discharge port is provided in the material supply path, and the mold inner space is disposed downstream of the gas discharge port and upstream of the cavity along the flow of the molding material. The gas upstream of the shielding position in the material supply path does not flow into the cavity by the injection of the molding material from the injection port, but through the gas discharge port. Opening / closing means for bringing the gas into the outside is provided, and the gas discharge port is formed in the opening / closing means, and the opening / closing means is configured so that the molding material comes into contact with the opening / closing means and force is applied from the molding material. move by receiving, before The mold space to release the state of being divided by the shielding position, thereby flowing the moldable material has reached the shielding position in the cavity.

In the mold gas discharge method according to the first invention and the mold for molding according to the second invention, the gas discharge port is provided in a connection region to the cavity in the material supply path. preferable.

The method for discharging gas in a mold according to the first invention and the mold for molding according to the second invention include a cavity in the mold, along the flow of the molding material, on the downstream side of the gas discharge port, and in the cavity The gas at the upstream side of the shielding position in the material supply path is not allowed to flow into the cavity and is sent to the outside through the gas discharge port by injection of the molding material from the injection port. Therefore, the amount of gas flowing into the cavity can be suppressed, and filling of the molding material into the cavity and discharge of the gas from the cavity can be performed smoothly.

1 is a schematic diagram of a molding die to which an in-mold gas discharging method according to an embodiment of the present invention is applied. (A) is explanatory drawing which shows a mode that the space in a metal mold | die was divided | segmented, (B) is explanatory drawing which shows a mode that the state which divided | segmented the space in a metal mold | die was cancelled | released. It is a graph and a table | surface which show an experimental result. (A), (B) is explanatory drawing which shows the 1st modification of the structure which discharges | emits gas outside. (A), (B) is explanatory drawing which shows the 2nd modification of the structure which discharges | emits gas outside. (A), (B) is explanatory drawing which shows the 3rd modification of the structure which discharges | emits gas outside. (A), (B) is explanatory drawing which shows the 4th modification of the structure which discharges | emits gas outside. (A), (B) is explanatory drawing which shows the 5th modification of the structure which discharges | emits gas outside. (A), (B) is explanatory drawing which shows the 6th modification of the structure which discharges | emits gas outside.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
As shown in FIG. 1, a molding die 10 to which an in-mold gas discharging method according to an embodiment of the present invention is applied includes a material supply path 13 provided with an injection port 12 for molding material 11, A mold inner space 15 including a cavity 14 connected to the material supply path 13 is provided. Hereinafter, these will be described in detail.

As shown in FIG. 1, the molding die 10 includes a fixed-side mold plate 17 fixed to a frame (not shown) via a fixed-side mounting plate 16, and a movable-side mold plate 19 attached to the movable-side mounting plate 18. And.
The movable side mold plate 19 is lifted and lowered together with the movable side mounting plate 18 by applying a force from a mold clamping device (not shown), and comes into contact with the fixed side mold plate 17 at the raised position.

The fixed-side mold plate 17 has a plurality of concave portions 20 on the lower side, and the movable-side mounting plate 18 has a plurality of convex portions 21 corresponding to the plurality of concave portions 20 on the upper side. In a state where the movable side mold plate 19 is in contact with the fixed side mold plate 17, between the movable side mold plate 19 and the fixed side mold plate 17, between each concave portion 20 and the convex portion 21 corresponding to each concave portion 20. A cavity (cavity) 14 provided in each of the gates 14, a gate 22 communicating with each cavity 14, and a runner 23 provided continuously with the gate 22 are formed. In the present embodiment, each runner 23 is a horizontally long cavity.

A sprue bush 24 having an injection port 12 for the molding material 11 is fitted into the fixed side mold plate 17, and a sprue 25 having a vertically long cavity is formed inside the sprue bush 24.
The sprue 25 whose upper side communicates with the injection port 12 is continuous with the plurality of runners 23 on the lower side, and forms a material supply path 13 integrally with the plurality of runners 23 and the plurality of gates 22.
The molding material 11 injected into the injection port 12 passes through the sprue 25 and branches into a plurality of runners 23, then passes through the gates 22 corresponding to the respective runners 23 and continues to each gate 22. Flow into the cavity 14.

Moreover, as shown in FIG. 1, FIG. 2 (A), (B), the movable side template 19 is provided with a mounting hole 26 formed continuously from the runner 23 on the lower side of the runner 23. A frame body 27, which is an example of an opening / closing means, is accommodated in the attachment hole 26.
As shown in FIG. 2, the piece body 27 includes a columnar portion 27 a having a smaller diameter than the lower columnar portion 27 b on the upper side, is accommodated in the attachment hole 26, and is attached to the lower side of the piece body 27. It is biased upward by (an example of an elastic body).
As shown in FIG. 2A, the top body 27 is given an upward force from the spring 28 and can project the upper side of the columnar portion 27 a into the runner 23 from the attachment hole 26.

A portion of the cylindrical portion 27a that protrudes into the runner 23 is provided with an inclined surface 32 that is inclined downward toward the upstream side on the upstream side along the flow of the molding material 11. Hereinafter, the upstream side along the flow of the molding material 11 is also simply referred to as “upstream side”, and the downstream side along the flow of the molding material 11 is also simply referred to as “downstream side”.
The piece body 27 is arranged at the upper limit position, and the downstream side of the inclined surface 32 is in close contact with the outer wall 31 of the runner 23 to divide the runner 23, and gas flows upstream and downstream from the contacted portion. Make it virtually impossible to come and go. Hereinafter, the position where the columnar portion 27a is in close contact with the outer wall 31 of the runner 23 is also referred to as a “shielding position”.

The top 27 is formed with a gas passage 29 through which gas passes from the upper end to the lower end in the center in plan view, and more than half of the gas passage 29 is disposed on the inclined surface 32 at the upper end of the gas passage 29. A gas outlet 30 is provided. As shown in FIG. 1, a gas discharge path 33 that communicates the space below the top body 27 of the mounting hole 26 to the outside is formed in the movable side template 19. In the present embodiment, the gas discharge path 33 is formed by a single cavity, but is not limited to this, and for example, the whole or a part thereof may be porous (porous).
The inclined surface 32 of the columnar portion 27a does not adhere to the outer wall 31 of the runner 23 in a state where the frame body 27 is disposed at the upper limit position. For this reason, the gas on the upstream side of the shielding position in the runner 23 enters the gas flow path 29 from the gas outlet 30 arranged in the runner 23 in a state where the runner 23 is divided at the shielding position by the piece body 27. It flows in and flows out through the attachment hole 26 and the gas discharge path 33 in order.

The piece body 27 is positioned at the upper limit position until the molding material 11 injected into the sprue 25 from the injection port 12 reaches the piece body 27 and divides the runner 23 at the shielding position.
When the molding material 11 is injected from the inlet 12 into the sprue 25 with the piece body 27 dividing the runner 23, the gas upstream from the shielding position in the material supply path 13 is directed toward the shielding position. It is pushed away and sent out to the outside through the gas discharge port 30, the gas flow path 29, the mounting hole 26, and the gas discharge path 33. At this time, the gas on the upstream side from the shielding position in the material supply path 13 does not substantially flow into the cavity 14 because the runner 23 is divided by the piece body 27.

The top body 27 at the upper limit position descends when the molding material 11 reaches the top body 27, comes into contact with the inclined surface 32 of the cylindrical portion 27 a and receives a downward force from the molding material 11, As shown in FIG. 2B, the state where the runner 23 is divided at the shielding position is released.
Therefore, until the molding material 11 reaches the piece body 27, the gas upstream from the shielding position in the material supply path 13 is sent out to the outside without substantially flowing into the cavity 14.

By adopting the spring 28 having an appropriate elastic coefficient, the mold inner space 15 can be kept divided until the molding material 11 comes into contact with the piece body 27, and the molding material 11 is maintained in the piece body 27. It has been confirmed that the state in which the mold inner space 15 is divided can be released by contacting with.
Moreover, in this Embodiment, although the gas exhaust port 30 is provided with the structure which consists of a some slit of a micrometer order width | variety, and suppresses the penetration | invasion of the molding material 11, it is not limited to this. When the gas discharge port 30 is clogged with the molding material 11, the clogging can be removed by blowing air from the lower end of the gas flow path 29 toward the upper end.

Then, when the molding material 11 comes into contact with the piece body 27 and the state where the runner 23 is divided is released and the molding material 11 is sent downstream from the shielding position, the molding material 11 is downstream from the molding material 11. The gas is discharged to the outside through a parting line or a gap provided by an unillustrated component such as an ejector pin or an insert.
In this way, by discharging the gas in the material supply path 13 on the upstream side of the cavity 14, it is possible to prevent the gas on the upstream side from the shielding position in the material supply path 13 from flowing into the cavity 14. The amount of gas flowing into the cavity 14 from outside 14 can be reduced.

For this reason, it can suppress that the gas pressure in the cavity 14 when the molding material 11 reaches | attains the cavity 14 becomes high, and it becomes possible to fill the cavity 14 with the molding material 11 smoothly.
Furthermore, the fluidity of the molding material 11 in the mold inner space 15 is improved, and the molding mold 10 can be downsized.

Here, in order to fill the cavity 14 with the molding material 11, the gas in the mold inner space 15 to be discharged to the outside, in addition to the gas that originally existed in the mold inner space 15, After the molding material 11 flows into the mold inner space 15, there is a newly added gas in the mold inner space 15. The gas newly added in the mold inner space 15 is the gas generated from the molding material 11 flowing into the mold inner space 15 and the mold inner space from the outside when the molding material 11 is injected. 15 is a gas flowing into the gas.

The inventors of the present application conducted an experiment for investigating at which timing the gas was added into the mold space after the molding material was injected into the mold space.
In the experiment, a gas discharge port was provided on the most downstream side of the cavity, and other portions were sealed so that the gas flowed out from the mold inner space was performed only from the gas discharge port. Then, a resin as a molding material was injected into the mold inner space, and the amount of the injected resin and the volume of gas discharged from the mold inner space through the gas discharge port were measured. The amount of resin injected into the mold inner space is equal to the volume of the region filled with the resin in the mold inner space. Therefore, a value obtained by subtracting the volume of the region filled with resin in the mold inner space from the volume of gas discharged to the outside can be regarded as the amount of gas newly added to the mold inner space.

FIG. 3 shows the result of the experiment. In the graph and table of FIG. 3, the gas volume is the volume (cm ³ ) of gas exhausted to the outside from the mold interior space, and the filling volume is the amount of resin present in the mold interior space, ie, The volume (cm ³ ) of the region filled with the resin in the mold inner space is shown. The measurement position (mm) indicates the position (mm) of the screw that pushes the resin into the mold inner space from the injection port, and the resin injected into the mold inner space as the measurement position increases. Needless to say, the amount increases. The resin passes through the sprue, the runner, and the gate in this order from the injection port, and is filled into the cavity. At the metering position 1.8 mm where the vertical line is drawn, the resin begins to enter the sprue from the inlet, and at the metering position 4.8 mm where the vertical line is drawn, the resin begins to flow into the cavity and the vertical line is drawn. It has been confirmed during the experiment that the resin is filled in the entire mold space including the cavity at the weighing position of 10.5 mm.

In the experiment, the gas volume and the filling volume were each measured at 6 metering positions including 1.8 mm, 4.8 mm and 10.5 mm metering positions.
In the table of FIG. 3, the gas volume difference (cm ³ ) is a value obtained by subtracting the gas volume at the nth measurement position from the gas volume at the (n + 1) th measurement position, for example, at the measurement position of 2.8 mm. It is 0.82 cm ^{3 obtained} by subtracting a gas volume of 0.92 cm ³ at a measuring position of 1.8 mm from a gas volume of 1.74 cm ³ . The filling volume difference (cm ³ ) in the table of FIG. 3 is a value obtained by subtracting the filling volume at the nth weighing position from the filling volume at the (n + 1) th weighing position.

The gas increase rate in the table of FIG. 3 is the ratio of the amount (volume) of gas newly added in the mold inner space to the area where the resin is newly filled in the mold space. When the filling volume difference is ΔVc, the gas increase rate can be obtained by the calculation formula of (ΔVg−ΔVc) / ΔVc, that is, (ΔVg / ΔVc) −1.
As a result of the experiment, it was confirmed that the gas increase rate was larger before the resin flowed into the cavity than the value after the resin started flowing into the cavity.
Therefore, discharging the gas upstream of the shielding position before the molding material reaches the cavity means that when the resin is injected into the mold inner space, the gas newly added into the mold inner space is transferred to the cavity. It means to suppress the approach effectively.

Here, it can be said that the gas discharge port and the shielding position should be provided as close to the cavity as possible on the upstream side of the cavity in order to suppress the gas intrusion into the cavity to the maximum extent. In addition to suppressing the entry of gas newly added into the mold space as the resin is filled into the cavity, the gas that has been in the material supply path before filling the resin enters the cavity. This is because it can be suppressed.
In this embodiment, the entire volume of the material supply path 13 is V, and the gas discharge port has a volume from the downstream end of the material supply path 13 of 0. It is provided in a region (connection region to the cavity 14 of the material supply path 13) that is 15V or less.

The material supply path has a different configuration depending on the molding die. For example, there is a molding die having no runner. And considering that it is important to provide a shielding position upstream of the cavity and exhaust the gas upstream from the shielding position without flowing into the cavity, the gas outlet is formed in the opening and closing means There is no need to be. Furthermore, the mold interior space may be divided on the downstream side of the gas discharge port and on the upstream side of the cavity, and the shielding position can be provided, for example, in the sprue.
Hereinafter, modifications of the structure for discharging gas to the outside will be described. In addition, about the structure similar to this Embodiment, the same code | symbol is attached | subjected and concrete description is abbreviate | omitted.

In the first modification, as shown in FIGS. 4A and 4B, the frame body 35 which is an example of the opening / closing means has no gas discharge port, and the gas discharge port 36 is located in the fixed-side mold plate 37. It is provided on the attached exhaust member 38. The exhaust member 38 disposed so that the gas exhaust port 36 faces (exposes) the runner 39 communicates with a gas exhaust path 40 formed in the fixed-side template 37 on the gas exit side. The shielding position where the top body 35 disposed at the upper limit position by the urging force of the spring 28 is in close contact with the outer wall 39 a of the runner 39 is disposed downstream of the gas discharge port 36.

As shown in FIGS. 5A and 5B, the second modification has a vertical path 43 in which the runner 41 communicates with the horizontal path 42 and the horizontal path 42, and the horizontal path 42 and the vertical path 43 In the communication area, the frame body 45 having the gas discharge port 44 provides a shielding position.
The top body 45 can advance and retreat along the horizontal path 42, and a part of the top body 45 projects into the runner 41 at the forward movement position, thereby dividing the runner 41 at the shielding position downstream of the gas discharge port 44. The gas upstream of the position where 45 protrudes is brought into a state where it can be discharged from the gas discharge port 44. 5A and 5B, the description of the elastic body that urges the top body 45 is omitted, and this is the same in FIGS.

In the third modified example, as shown in FIGS. 6A and 6B, a top body 50 that can advance and retreat in the horizontal direction is disposed in an area where the horizontal path 48 and the vertical path 49 of the runner 47 communicate with each other. Yes. The top body 50 divides the runner 47 at the forward movement position by contacting the outer wall 49a of the vertical path 49 to provide a shielding position. The exhaust member 52 provided with the gas exhaust port 51 is arranged so that the gas exhaust port 51 faces the runner 47 on the upstream side of the shielding position, and the gas outlet side of the exhaust member 52 communicates with the gas exhaust path 53. ing.

In the first, second, and third modified examples, the gas discharge port communicates with the runner in the state where the inner space of the mold is divided at the shielding position, whereas the fourth, fifth, and sixth described below. In the modified example, the gas discharge port communicates with the sprue in a state where the inner space of the mold is divided.
As shown in FIGS. 7 (A) and 7 (B), the fourth modified example is a top / bottom piece having a gas discharge port 56 at the upper end below the sprue 55 formed in the sprue bushing 54. 57 is arranged. The frame body 57 in which the gas flow path 58 communicating with the gas discharge port 56 is formed inside shuts off the sprue 55 and the runner 61 at the rising position, and arranges the gas discharge port 56 in the sprue 55. The gas in the sprue 55 passes through the gas discharge port 56 and the gas flow path 58 and is discharged to the outside through the gas discharge path 59. Then, when the molding material 11 comes into contact with and is pushed down, the piece body 57 releases the state where the mold inner space 60 has been divided, and causes the molding material 11 to flow into the runner 61.

As shown in FIGS. 8A and 8B, the fifth modified example is different from the fourth modified example in that the gas discharge port 62 is provided not in the piece body 63 but in the exhaust member 64. ing. In the exhaust member 64, the gas discharge port 62 is disposed in a sprue 66 formed in the sprue bush 65, and the gas discharge side is continuous with the gas discharge path 67. The point that the piece 63 is lowered by the contact of the molding material 11 to release the state where the mold inner space 68 is divided and the molding material 11 flows into the runner 69 is the same as in the fourth modification example. The same.

In the fifth modification example, the exhaust member 64 is fixed to the stationary side mold plate 17, whereas in the sixth modification example, as shown in FIGS. The sprue bush 71 is fixed. In the sixth modification, the gas discharge port 72 formed in the exhaust member 70 is provided on the upstream side of the sprue 73 as compared with the gas discharge port 62 of the fifth modification. The gas outlet side of the exhaust member 70 is continuous with the gas discharge path 74. In the sixth modification, the same components as those in the fifth modification are denoted by the same reference numerals as those in the fifth modification, and detailed description thereof is omitted.

From the above, the in-mold gas discharge method of the present embodiment applied to the molding die 10 has the following contents.
That is, in the mold gas discharge method of the present embodiment, the mold space 15 is divided at the shielding position on the downstream side of the gas discharge port 30 and on the upstream side of the cavity 14, and the injection port 12. A step B of injecting the molding material 11 into the material supply path 13 and sending the gas upstream from the shielding position in the material supply path 13 to the outside via the gas discharge port 30 without flowing into the cavity 14; And a step C of releasing the state in which the mold inner space 15 is divided at the shielding position and allowing the molding material 11 to flow into the cavity 14.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and all changes in conditions and the like that do not depart from the gist are within the scope of the present invention.
For example, the present invention is not applied only to a molding die in which the molding material is a molten resin, but a molding die (die casting) in which the molding material is a molten metal, or the molding material is a metal. The present invention is also applicable to a molding die that is a powder of the above.
Further, in the present embodiment, the state in which the mold interior space is divided by the arrival of the molding material reaching the piece body is released, but the state in which the mold interior space is divided at a predetermined timing using the sequencer is released. You may make it cancel.
The opening / closing means is not limited to the frame having two columnar parts, and may have other shapes.

10: Mold for molding, 11: Material for molding, 12: Injection port, 13: Material supply path, 14: Cavity, 15: Internal space of the mold, 16: Fixed side mounting plate, 17: Fixed side template, 18 : Movable side mounting plate, 19: movable side template, 20: concave portion, 21: convex portion, 22: gate, 23: runner, 24: sprue bush, 25: sprue, 26: mounting hole, 27: piece body, 27a 27b: cylindrical portion, 28: spring, 29: gas flow path, 30: gas discharge port, 31: outer wall, 32: inclined surface, 33: gas discharge path, 35: piece body, 36: gas discharge port, 37 : Fixed side template, 38: exhaust member, 39: runner, 39a: outer wall, 40: gas discharge path, 41: runner, 42: horizontal path, 43: vertical path, 44: gas discharge port, 45: top body, 47: runner, 48: horizontal road, 49: vertical road, 49a: outer wall 50: Top body, 51: Gas exhaust port, 52: Exhaust member, 53: Gas exhaust path, 54: Sprue bush, 55: Sprue, 56: Gas exhaust port, 57: Top body, 58: Gas flow path, 59 : Gas discharge path, 60: mold inner space, 61: runner, 62: gas discharge port, 63: piece body, 64: exhaust member, 65: sprue bush, 66: sprue, 67: gas discharge path, 68: Mold inner space, 69: runner, 70: exhaust member, 71: sprue bush, 72: gas outlet, 73: sprue, 74: gas outlet

Claims (4)

The gas exhaust space is formed along the flow of the molding material through a mold inner space comprising a material supply path provided with a molding material inlet and a gas outlet and a cavity connected to the material supply path. Dividing at a shielding position on the downstream side of the outlet and on the upstream side of the cavity; and
The molding material is injected into the material supply path from the injection port, and the gas upstream from the shielding position in the material supply path is not allowed to flow into the cavity, but to the outside through the gas discharge port. Sending out process B;
To release the state in which the mold space divided by the shielding position, the molding material have a step C that can flow into the cavity,
The gas discharge port is formed in an opening / closing means for dividing the inner space of the mold,
The open / close means moves when the molding material comes into contact with the open / close means and receives a force from the molding material, and releases the state in which the inner space of the mold is divided. Internal gas discharge method. 2. The method for discharging gas in a mold according to claim 1 , wherein the gas discharge port is provided in a connection region to the cavity in the material supply path. In a molding die provided with a mold inner space consisting of a material supply path provided with a molding material injection port and a cavity connected to the material supply path,
A gas discharge port is provided in the material supply path,
The mold interior space is divided along the flow of the molding material at a shielding position downstream of the gas discharge port and upstream of the cavity, and the molding material is injected from the injection port. The gas upstream of the shielding position in the material supply path by the gas does not flow into the cavity, and is provided with opening and closing means for sending out to the outside through the gas discharge port,
The gas discharge port is formed in the opening / closing means,
The opening / closing means releases the state where the molding material is moved by contact with the opening / closing means and receives a force from the molding material to divide the inner space of the mold at the shielding position. A molding die, wherein the molding material reaching a position is allowed to flow into the cavity. 4. The molding die according to claim 3 , wherein the gas discharge port is provided in a connection region to the cavity of the material supply path.

Images