JP2003001668A - Molding apparatus for multilayered molded object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molding apparatus capable of accurately molding a multilayered molded object. SOLUTION: In a first material supply part, the molding material thermally melted in a melting tank 32 is metered by retracting the plunger 34 inserted into a first cylinder 36 to be stored in a first material storage part 44 and, in a second material supply part 24, the molding material plasticized/kneaded by the rotary motion of the screw 56 inserted into a second cylinder 54 is metered to be stored in the second material storage part 58 provided to the leading end of the second cylinder 54. Then, the molding material stored in the first material storage part 44 is injected in a cavity before the molding material in the second material storage part 58 is injected in the cavity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding apparatus for molding a multi-layer molded body made of a plurality of materials having different characteristics.

[0002]

2. Description of the Related Art As a molding device of this type, a device disclosed in Japanese Patent Laid-Open No. 5-104578 has been proposed.

As shown in FIG. 4, this molding apparatus includes an injection nozzle 3 which is press-contacted to a runner 2 portion of a mold 1,
A first resin supply unit 4 for supplying the first resin to the injection nozzle 3 to form the outer layer of the multilayer molded body, and a second resin supply to the injection nozzle 3 for forming the inner layer of the multilayer molded body. Two
And a resin supply portion 5 of the same, and a shaft hole 7 continuous with the nozzle hole 6 at the tip is formed in the injection nozzle 3, and the inner cylindrical body 8 is housed in the shaft hole 7 so as to be able to move forward and backward. . And
The annular gap between the shaft hole 7 and the inner cylinder 8 is the first resin passage 9
The inside of the inner cylindrical body 8 serves as a second resin passage 10. The inner cylindrical body 8 has the second resin passage 1 inside thereof.
A needle valve (not shown) for opening and closing 0 is installed, and it is driven forward and backward by a drive cylinder (not shown) to open and close the first resin passage 9 as appropriate. That is, the tip end portion of the inner cylindrical body 8 comes into contact with the tapered surface 7a of the tip end portion of the shaft hole 7 during the forward movement so that the first resin passage 9
Is closed and the passage 9 is opened by the backward movement.

When a multi-layer molded body is molded by this molding apparatus, first, with the second resin passage 10 inside the inner cylindrical body 8 closed, the inner cylindrical body 8 is retracted to the first position. The resin passage 9 is opened, and the injection nozzle 3 from the first resin supply unit 4 is opened.
A predetermined amount of the first resin through the cavity 11 of the mold 1.
The second resin is then injected into the cavity 11 through the injection nozzle 3 by advancing the inner cylinder 8 and opening the needle valve. At this time, since the first resin does not completely lose fluidity in the cavity 11, the second resin is
Into the inside of the resin, and as a result, a two-layer inner and outer molded body is formed.

[0005]

However, in the above-mentioned conventional molding apparatus, the tip end portion of the inner cylindrical body 8 is brought into contact with the tapered surface 7a of the shaft hole 7 inside the injection nozzle 3 so that the first resin passage 9 is formed. Since it has a structure that opens and closes
At the time of completion of the injection for one cycle, the second resin remains in the portion extending from the tip end portion of the inner cylindrical body 8 to the nozzle hole 6, and at the time of the next injection, the remaining second resin is mixed with the first resin. However, there is a problem that product quality deteriorates.

[0006] Further, Japanese Patent Laid-Open No. 2000-20 by the present applicant.
2858 discloses a first molding method for forming an outer layer of a multilayer molded body.
There is disclosed a molding device in which the resin injection port of (1) and the injection port of the second resin for molding the inner layer of the multilayer molded body are independent of each other. Inorganic filler such as filler for adjusting the specific gravity of the first resin or the second resin, since the second resin has a structure in which it is liquefied in the first and second melting tanks and then injected. If it contains, the inorganic filler may be precipitated in each dissolution tank, and the molten resin and the inorganic filler may be separated, so molding using a material containing the inorganic filler There is a problem that the body cannot be molded.

[0007]

Therefore, in the invention described in claim 1, the molding material heated and melted in the melting tank is stored in the first material storing portion at the tip of the first cylinder in which the plunger is inserted. In addition, the first material supply for measuring the amount of the molding material to be injected into the cavity of the mold by retracting the plunger to a predetermined position by the pressure from the molding material stored in the first material storage section. Part and the second cylinder at the tip of the second cylinder while plasticizing and kneading the molding material by the rotational movement of the screw inserted in the second cylinder.
Secondly, the amount of the molding material to be injected into the cavity is stored by storing the material in the material storage portion and retracting the screw to a predetermined position by the back pressure of the molding material stored in the second material storage portion. A molding device for a multilayer molded body, comprising at least one material supply part, wherein each of the first material supply part and the second material supply part supplies a molding material to the cavity. It is supplied to the cavity from each injection port independent from each other through each supply route independent from each other, and at each injection port, a shut-off pin that opens and closes independently is provided. In the molding apparatus, the molding material initially supplied into the cavity is supplied from the first material supply unit. In the second material supply unit, which is a so-called in-line screw injection mechanism, when the molding material stored in the second material storage unit is gel or soft paste and has an extremely soft property, the melted material in the second material storage unit is There is a possibility that so-called backflow may occur that escapes to the rear end side of the second cylinder along the groove of the screw, and the injection accuracy may deteriorate, but in the so-called plunger type injection mechanism, the first material supply unit Does not cause backflow-like phenomena. That is, in the first material storage section, the amount of the molding material to be injected from the first material supply section into the cavity can be accurately measured,
And the measured amount of molding material is reliably supplied to the cavity.

On the other hand, since the material may be supplied from the second material supply section to the cavity sequentially so as to fill the remaining space of the cavity, the injection precision of the multilayer molded article is such that the molding material is first supplied to the cavity. It depends on the injection accuracy of the first material supply section.

Therefore, by first supplying the material into the cavity from the first material supplying section having high injection accuracy,
In general, a multilayer molded body can be molded with good injection accuracy.

In particular, when molding a molded body in which two kinds of materials having different characteristics are arranged in two layers, the inner space and the outer space of the cavity are eliminated when the molding material is supplied from the second material supply portion to the cavity. Like this,
Since the injection accuracy of the first material supply unit substantially matches the injection accuracy of the molded body, the injection accuracy of the inner and outer two-layer molded body becomes extremely high.

According to a second aspect of the invention, in the first aspect of the invention, the second material supply section assists the backward movement of the screw due to the back pressure of the molding material in the second material storage section. The feature is that an assist cylinder is attached. If the molding material stored in the second material storage section of the second material supply section has an extremely soft property such as gel or soft paste, the pressure in the second material storage section is unlikely to rise, and it is sufficient for the screw. There is a possibility that accurate measurement cannot be performed because the back pressure does not act, but by providing the assist cylinder, even if the pressure in the second material storage part is small, the screw is retracted by the action of the assist cylinder, The amount of molding material to be injected into the cavity from the second material supply unit can be accurately measured.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the first material supply unit applies pressure to a passage for pumping a molding material from the melting tank into the first cylinder. A melt in the melt tank for pumping the molding material from the melt tank to the first material reservoir, using a pressure in the first material reservoir detected by the pressure sensor during measurement. It is characterized in that the pressure applied to the material and the back pressure of the plunger are controlled. This controls the retracting speed of the plunger within the second cylinder.

According to the invention described in claim 4, in the invention described in any one of claims 1 to 3, when a molding material containing an inorganic filler is used, the molding material containing the inorganic filler is It is characterized in that the material is supplied from the two material supply parts to the cavity. When the molding material containing the inorganic filler for adjusting the specific gravity is heated and melted in the melting tank of the first material supply section, the inorganic filler may precipitate in this melting tank, but the second material supply section When a molding material containing an inorganic filler is charged, it is kneaded by the screw inserted in the second cylinder, so that the molding material in which the inorganic filler is evenly distributed is stored in the second material storage section.

[0014]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram showing a schematic structure of a molding apparatus according to the present invention, showing an example of a molding apparatus 20 for molding a two-layer inner and outer molded body made of two kinds of molding materials having different properties from each other. ing.

The molding apparatus 20 is mainly composed of a first material supply unit 22 and a second material supply unit 24, and a runner (not shown) in the mold that communicates with a cavity (not shown) in the mold. The ejection ports from the respective supply units 22 and 24 that open at 1 are arranged in parallel in one nozzle 30.

The first material supply section 22 includes a melting tank 32 for melting the first material, a first cylinder 36 in which a plunger 34 is inserted, and a first shutoff pin for opening and closing the first injection port 26. And 38.

A heater (not shown) is installed in the outer peripheral area of the melting tank 32 to melt the first material charged into the melting tank 32.

The first material melted in the melting tank 32 is pressure-fed to the first material reservoir 44 at the tip of the first cylinder 36 by the pressure of the air introduced from the air inlet 40 through the supply passage 42. It First material storage section 44
Is a space defined inside the first cylinder 36 by the tip of the first cylinder 36 and the plunger 34.

The plunger 34 is capable of advancing and retracting relative to the first cylinder 36, and when the plunger 34 is retracted by the pressure from the first material in the first material storage section 44. The position of 34 is detected by a sensor (not shown) such as a potentiometer, and the amount of the first material to be supplied from the first material supply unit 22 to the cavity is measured in the first material storage unit 44, Store.

At the connecting portion between the supply passage 42 and the dissolution tank 32 and at the connecting portion between the supply passage 42 and the first material storage portion 44, open-close type auxiliary shutoff pins 46, 4 are respectively provided.
8 is provided, and a pressure sensor 50 is provided in the supply passage 42. Each of the auxiliary shutoff pins 46 and 48 is opened when the first material is measured by the plunger 34 in the first material storage portion 44, and is otherwise closed at all times.

The first material storage section communicates with the first injection port 26 provided in the nozzle 30 described above. The first injection port 26 can be opened / closed by a first shut-off pin 38. The first injection port 26 is opened only when the first material in the first material storage section 44 is injected, and the other is otherwise opened. 1
The injection port 26 is closed so that the material does not drip. More specifically, the first shut-off pin 38 can be moved forward and backward by the drive cylinder 52, the forward movement by the drive cylinder 52 closes the first injection port 26, and the backward movement by the drive cylinder 52 causes the first shut-off pin 38 to move forward and backward. The ejection port 26 is opened.

The temperature of the supply passage 42, the first material reservoir 44 and the nozzle 30 is controlled by a heater (not shown) so that the melted first material does not solidify.

The second material supply unit 24 is provided with a second cylinder 54 having a plurality of band heaters (not shown) as a heating source mounted therein, and is rotatably inserted in the second cylinder 54 so as to be movable back and forth. And the screw 56 that is formed.

In the second cylinder 54, a second material reservoir 58 is defined by the tip of the second cylinder 54 and the screw 56. The second material storage portion 58 communicates with the second injection port 28 provided in the nozzle 30 described above via the openable second shutoff pin 60.

The second cylinder 54 has a screw 56.
The second material is supplied from a chamber (not shown) in synchronization with the rotation of the. The second material supplied into the second cylinder 54 is kneaded while being plasticized by the heat from the band heater and the rotation of the screw 56, and is mixed in the space in front of the screw 56, that is, the tip side of the second cylinder 54. Are sequentially metered to the defined second material storage section 58. still,
The second shut-off pin 60 is designed to open only when the second material in the second material reservoir 58 is injected in order to prevent the second material from dripping.

Second material to be stored in the second material storage section 58
The measurement of the material is performed by detecting the position of the screw 56 with a sensor (not shown) such as a potentiometer. That is, when the plasticized second material is gradually stored in the second material storage portion 58 with the rotation of the screw 56, the back pressure of the second material storage portion 58 increases,
Since the screw 56 moves backward relative to the second cylinder 54, the rotation of the screw 56 is stopped at the time when the screw 56 moves backward to a preset position, thereby ensuring the measurement accuracy.

In order to assist the backward movement of the screw 56 at this time, the screw 56 is provided with an assist cylinder 62 that smoothly retracts the screw 56 even if the back pressure of the second material storage portion 58 is small. It is installed. That is, the second material reservoir 5 is attached to the screw 56.
When even a slight back pressure from 8 is applied, a force in the direction of retracting the screw 56 is generated in the assist cylinder 62.

In the molding apparatus 20 configured as described above, the inside of the dissolution tank 32 of the first material supply section 22 is extremely soft (for example, JIS, as represented by a gel-like or soft paste-like oil-containing polymer material). A first material having an A of less than 15 degrees) is charged in advance in the form of pellets or blocks. The first material put into the melting tank 32 is melted at a predetermined temperature by the heater.

As shown in FIG. 2, the air pressure P2 is constantly applied to the first material in the dissolution tank 32 by the air introduced from the air introduction port 40, and the auxiliary shot-off pins 46 and 48 are opened. As a result, the melted first material flows into the first material storage portion 44, and the plunger 3
4 is retracted and the metering of the first material to be injected into the cavity is started.

Detected value P from the pressure sensor 50 at this time
0 is used to apply back pressure P1 to the plunger 34 so that the retreating speed of the plunger 34 does not increase too much. More specifically, the back pressure P1 is controlled so that P0-P1>α> 0. Here, α is a predetermined constant value. Also, P0 <α
In the case of, the air pressure P2 in the dissolution tank 32 is increased to control P0> α.

In this way, while controlling the retreat speed of the plunger 34, when the plunger 34 retreats to a predetermined measuring position, the auxiliary shot-off pins 46 and 48 are closed and the measuring is completed.

In parallel with the measurement in the first material supply unit 22, the second material supply unit 24 also measures the amount of the second material to be injected into the cavity.

The second cylinder 54 of the second material supply section 24
In addition, a very soft (eg, JIS A) typified by a gel-like or soft paste-like oil-containing polymer material containing an inorganic filler such as a filler for adjusting the specific gravity.
The second material (less than 15 degrees) is charged as pellets or blocks.

The second material plasticized and kneaded by the heat from the band heater and the rotation of the screw 56 is the second material.
The screw 56 flows back into the material storage portion 58, and the back pressure of the second material storage portion 58 assists the assist cylinder 62 so that the screw 56 retracts in the second cylinder 54 and measures the second material to be injected into the cavity. Is started. Then, when the screw 56 retracts to a predetermined measuring position, the rotation of the screw 56 is stopped and the measuring is completed.

When the measurement in the first material supply section 22 and the second material supply section 24 is completed, the molding of the molded product is started.

First, in the first material supply section 22, the first
The shut-off pin 38 is opened, the plunger 34 is advanced, and the first material measured in the first material storage portion 44 is injected from the first injection port 26. Immediately after the injection is completed, the first shutoff pin 38 is closed, the second shutoff pin 60 of the second material supply unit 24 is opened, and the screw 5
6 is advanced to eject the second material measured in the second material storage portion 58 from the second injection port 28.

The first material injected from the first material supply section 22 is precisely metered and ejected in a prescribed injection amount, and the second material injected from the second material supply section 24 is the cavity of the mold. It is ejected so that there is no space left.

At this time, the first material in the cavity is solidified by cooling the skin portion in the mold, but the inside of the cavity has not completely lost the fluidity. The first material is filled in the cavity so as to enter the inside. The second shut-off pin 60 is thus left open for a predetermined time even after the second material is completely filled in the cavity, thereby maintaining the inside of the cavity at a predetermined pressure. After that, after a lapse of a predetermined time, the second shut-off pin 60 is advanced to move to the second
The ejection port 28 is closed.

In the molding apparatus 20 of the above-mentioned embodiment, as shown in FIG. 1, the first injection ports 26 independent of each other are provided.
Since the second injection port 28 and the second injection port 28 are arranged in parallel with each other in the nozzle 30, the first material and the second material do not mix in the nozzle 30, and the first and second layers are accurately formed in the cavity. The material and the second material can be filled.

Since the screw 56 of the second material supply unit 24 is provided with an assist cylinder 62 for assisting the backward movement of the screw 56, the second material supply unit 24 is extremely soft (for example, JIS A 15).
Even if the back pressure of the second material storage section 58 is small, the screw 56 is smoothly retracted, and the second material supply section 24 accurately measures the second material. As a result, the molding accuracy of the molded product can be improved.

Further, by using the detected value P0 of the pressure sensor 50, the plunger 3 of the first material supply section 22 at the time of measurement is measured.
By controlling the reverse speed of 4 the plunger 34
It is possible to reliably prevent the vehicle from retreating at a high speed and overshooting behind the set weighing position. That is, since the plunger 34 overshoots behind the set weighing position, the capacity of the first material storage unit 44 increases, and the accuracy of weighing the first material in the first material storage unit 44 increases. It is possible to reliably prevent the deterioration.

The molding apparatus 20 includes a first material supply section 22 and
The second material supply unit 24, which is an in-line screw type injection mechanism, is provided. Therefore, when the molded body is molded using a material containing an inorganic filler such as a filler, the second material supply unit 24 is used. A material containing an inorganic filler such as a filler in 24 can be added as the second material. That is, when the material containing the inorganic filler is put into the first material supply unit 22, the inorganic filler may be precipitated in the dissolution tank 32, but the second material supply unit 24 uses the in-line screw system. Since it is an injection mechanism, the inorganic filler can be supplied into the second material storage portion 58 without being separated, and a desired molded product can be molded.

Incidentally, in the above-mentioned embodiment, the air is introduced into the dissolution tank 32 to thereby dissolve the dissolution tank 3
The melted material (first material) in 2 is pumped to the first material reservoir 44, but as shown in FIG. 3, a piston 64 is arranged in the melt tank 32 and the piston 64 is moved forward. Thus, the melting material in the melting tank 32 may be pressure-fed to the first material storage section 44. Also in this case, the back pressure of the plunger 34 is controlled while the pressure is detected by the pressure sensor 50 as in the above-described embodiment.

Further, the present invention is not limited to the molding apparatus provided with one each of the first material supply section 22 and the second material supply section 24 as in the above-mentioned embodiment, but the first material The molding apparatus may be configured to include a plurality of supply units 22 and a plurality of second material supply units 24.

In the above-described embodiment, in the molding apparatus 20, not only the inner and outer two-layer molded product but also the left and right materials are different by opening the first injection port 26 and the second injection port 28 at the same time during molding. Molding molded products, 1st
By opening only one of the injection port 26 and the second injection port 28, a molded product of a single material can be molded, and there is also an advantage that one device can handle various molded products. is there.

[0047]

According to the first aspect of the present invention, even if the injection accuracy of the second material supply section is deteriorated, the first material is supplied from the first material supply section to the cavity before the injection of the molding material.
By supplying the molding material from the material supply unit to the cavity, the injection accuracy of the entire molding apparatus does not deteriorate as a whole.

If the molding material stored in the second material storage portion has an extremely soft property such as gel or soft paste, the pressure in the second material storage portion is unlikely to rise and the screw has a sufficient spine. There is a possibility that accurate measurement cannot be performed without the pressure acting, but according to the invention of claim 2,
Even if the pressure of the second material storage portion is small, the amount of molding material to be injected from the second material supply portion into the cavity can be accurately measured.

According to the third aspect of the invention, the retreating speed of the plunger in the second cylinder is controlled, and the amount of the molding material to be injected from the first material supply section into the cavity is accurately determined. Therefore, the molding accuracy of the molded product can be improved.

According to the invention described in claim 4, even if the molding material containing the inorganic filler is used, the molten resin in which the inorganic filler is evenly mixed is supplied to the second material storage portion. Therefore, the desired molded article can be molded with high accuracy without forming the dense and dense molding layers of the molded article formed of the material containing the inorganic filler.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a schematic configuration of a multilayer molding apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing a schematic configuration of a first material supply unit of the multilayer molding apparatus according to the present invention.

FIG. 3 is an explanatory diagram showing a schematic configuration of an example in which a first material supply unit is different.

FIG. 4 is an explanatory view showing a schematic configuration of a conventional multilayer molding apparatus.

[Explanation of symbols]

20 ... Molding device 22 ... First material supply section 24 ... Second material supply section 26 ... First ejection port 28 ... Second ejection port 32 ... Melting tank 34 ... Plunger 36 ... 1st cylinder 38 ... 1st shut-off pin 44 ... First material reservoir 50 ... Pressure sensor 54 ... Second cylinder 56 ... screw 58 ... 2nd material storage part 60 ... Second shut-off pin 62 ... Assist cylinder

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // B29L 9:00 B29L 9:00 F term (reference) 4F206 AG03 AP03 AP06 AR03 AR07 JA07 JB22 JD01 JD04 JL02 JM04 JN12 JN13 JN15 JP13

Claims (4)

[Claims] 1. A first cylinder at the tip of a first cylinder, into which a plunger is inserted, for a molding material heated and melted in a melting tank.
The amount of the molding material to be injected into the cavity of the mold is measured by retracting the plunger to a predetermined position with the pressure of the molding material stored in the first material storage section while being stored in the material storage section. The first material supplying section and the second material are stored in the second material storage section at the tip of the second cylinder while plasticizing and kneading the molding material by the rotational movement of the screw inserted in the second cylinder. At least one second material supply unit for measuring the amount of the molding material to be injected into the cavity by retracting the screw to a predetermined position with the back pressure of the molding material stored in the storage unit In the molding apparatus for a multilayer molded body, the molding materials supplied from the first material supply units and the second material supply units to the cavities are mutually Molded into a multi-layer molded product that is supplied to the cavity from each of the injection ports that are independent of each other through each of the independent supply paths, and that each of the injection ports is provided with a shut-off pin that opens and closes independently. In the apparatus, the molding material initially supplied into the cavity is supplied from the first material supply unit, and the apparatus for molding a multilayer molded body. 2. The assist cylinder for assisting the backward movement of the screw due to the back pressure of the molding material in the second material storage portion is attached to the second material supply portion. A molding apparatus for a multilayer molded article as described. 3. The first material supply unit has a pressure sensor in a path for feeding a molding material from the melting tank into the first cylinder, and the first material detected by the pressure sensor during measurement. A pressure applied to the melted material in the melt tank to pump the molding material from the melt tank to the first material reservoir using the pressure in the reservoir;
The back pressure of the said plunger is controlled, The shaping | molding apparatus of the multilayer molded body of Claim 1 or 2 characterized by the above-mentioned. 4. When a molding material containing an inorganic filler is used, the molding material containing the inorganic filler is supplied from the second material supply section to the cavity. A molding apparatus for a multilayer molded article according to any one of claims.