JP3160888B2 - Mold equipment for injection molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold apparatus for injection molding used for molding a molding material such as a thermoplastic resin.

[0002]

2. Description of the Related Art For example, in injection molding of a thermoplastic resin, a product is formed by filling a molten resin into a product-shaped cavity formed in a mold, and cooling and solidifying the resin. I have to.

In conventional injection molding, a molding machine performs a measuring step, a filling step, and a pressure-holding step. Taking an in-line screw molding machine as an example, in a heating cylinder device, a predetermined amount of melted resin is accumulated at a tip side in a cylinder body while a rotating screw is retracted (a measuring step). Next, the screw is advanced to inject the resin into the mold from the nozzle at the tip of the cylinder body, and the cavity is filled with the resin (filling step). Thereafter, an appropriate pressure is applied to the resin in the cylinder body by a screw to replenish the resin in an amount corresponding to the shrinkage due to cooling into the cavity (pressure keeping step).

On the other hand, the volume of a cavity in a mold is constant. Therefore, the pressure and amount of the resin filled in the cavity are basically determined by the control of the molding machine. Therefore, if there is an error in the control on the molding machine side, an error will occur in the pressure or amount of the resin filled in the cavity. In order to eliminate this error, it is conceivable to precisely control the screw and the like of the molding machine. However, the cause of the error is various such as temperature, variation in properties of the resin itself, and the like. For example, there is a long resin path from the screw to the cavity, but if there is an error that occurs in this resin path, even if the screw is precisely controlled, an error will occur in the pressure and amount of the resin filled in the cavity. Will be. That is, it is difficult to eliminate the error generated in the cavity only by controlling the molding machine.

In the conventional injection compression molding, for example, as described in JP-A-6-71698, after a resin is filled in a cavity, some components of a mold are removed. By reducing the volume of the cavity itself by moving it or switching the mold clamping force,
The resin in the cavity is compressed. However, compressing the resin by reducing the volume of the cavity does not have the effect of eliminating errors in the pressure and amount of the resin filled in the cavity.

In the case of performing compression after closing a gate from a resin passage to a cavity in injection compression molding, in a conventional mold apparatus, a means for closing the gate and a means for compression are separated. Was. On the other hand, in the mold apparatus described in JP-A-6-71698, means for closing the gate and means for compression are shared. As a configuration for this, a sleeve is movably incorporated in the fixed mold plate in the mold opening and closing direction, and this sleeve is pushed toward the movable mold by the buffer, and the cavity is formed between the concave mold of the fixed mold plate and the movable mold plate. It is formed so as to have a convex shape. First, the mold is closed with a weak mold clamping force, and the movable mold plate and the sleeve abut, but the fixed mold plate and the movable mold plate are slightly open, and the concave mold and the convex mold are fitted. Fill the cavity with resin without any. Next, when the fixed mold plate and the movable mold plate are closed by increasing the mold clamping force, the gate is closed by the fitting of the concave mold and the convex mold, and the compression is performed.

However, in the mold apparatus described in the above publication,
Since the resin passage to the cavity is formed by the gap between the fixed mold plate and the movable mold plate, the resin in the resin passage is closed with closing the fixed mold plate and the movable mold plate. , It must either enter the cavity while being compressed or return to the molding machine. Even if the resin in the resin passage can return to the molding machine side, the resin in the resin passage is compressed around the cavity by the fixed mold plate and the movable mold plate. And the pressure are unstable.

[0008]

As described above, in the conventional injection molding method, the pressure and amount of the molding material such as resin filled in the cavity are controlled by controlling the material supply device such as a heating cylinder device. Therefore, there is a problem that it is difficult to accurately control the pressure and amount of the molding material. Also, as a mold apparatus for injection compression molding, JP-A-6-71698 discloses that a means for closing a gate and a means for compression are commonly used. In the mold apparatus described in (1), the volume of the resin passage, which is a material passage, is also reduced along with the compression operation, so that there is a problem that the amount and pressure of the final molding material in the cavity become unstable. there were.

An object of the present invention is to solve such a problem, and it is an object of the present invention to accurately control the pressure and amount of a molding material filled in a cavity.

[0010]

According to a first aspect of the present invention, there is provided an injection molding die apparatus, comprising: a first die having a material passage therein; and a first die having a material passage therein. And a second mold body which forms a cavity between the first mold body and the first mold body when the mold is closed, and the first mold body and the second mold body are mutually opposed against the mold clamping force. An urging means for urging the material in an opening direction, wherein the first mold has a direct gate for communicating the material passage with the cavity;
Has a gate closing portion that fits into the direct gate as the second mold and the first mold close.

At the time of molding, first, both molds are closed with a weak clamping force, and both molds are not yet closed by the force applied by the urging means. In this state, a filling step of supplying the molding material to the material passage and filling the molding material from the direct gate of the first mold body into the cavity is performed.

Subsequent to the filling step, the supply of the molding material to the mold apparatus is continued, and the two mold bodies are displaced from each other to balance the pressure of the molding material in the mold apparatus with the mold clamping force. Then, a pressure adjusting step of adjusting the pressure of the molding material in the cavity is performed. That is, in this pressure adjusting step, both molds are opened to each other against the mold clamping force due to the pressure of the molding material in the mold apparatus. It is determined by the balance with the clamping force and becomes larger as more molding material is supplied in the mold apparatus. In other words, even if there is an error in the amount of the molding material supplied from the material supply device, the error is absorbed by the change in the opening amount, and the pressure of the molding material in the cavity becomes constant.

After the pressure adjusting step, the mold clamping force is increased to close both molds, the molding material in the cavity is returned to the material supply device side, and the second mold is inserted into the direct gate of the first mold. A metering step is performed to leave a certain amount of molding material in the cavity when the gate closes after the gate closing part of the body has begun to fit. That is, when the pressure adjustment step is completed, the amount of the molding material in the cavity is not constant, but the amount of the molding material in the cavity is made constant by the subsequent measurement step.
Thus, the pressure adjustment step and the metering step accurately control the pressure and amount of the molding material filled in the cavity.

After this measuring step, that is, after the gate is closed, a compression step of completely closing both molds and compressing the molding material in the cavity is performed. Thereby, the shrinkage accompanying the solidification of the molding material is compensated, and it is not necessary to perform a pressure-holding step on the material supply device side for this compensation.

By the way, the direct gate has an advantage that the curing of the molding material to the cavity is reduced, whereby the transferability from the mold apparatus to the product is improved. Molding material smoothly returns to the material passage. In addition, since the gate is a direct gate, all the pressure of the molding material related to the pressure adjustment is applied to the mold in the cavity, and the pressure is adjusted based on the cavity, so that the pressure of the molding material in the cavity is reduced. It is kept constant.

According to a second aspect of the present invention, there is provided an injection mold apparatus.
In order to achieve the above object, a fixed mold having a material passage therein, a movable mold that opens and closes the fixed mold and forms a cavity between the fixed mold when the mold is closed, and the fixed mold fixed to the movable mold A movable body that is supported so as to be openable and closable in the opening and closing directions of the mold and the movable mold and abuts on the fixed mold, and an urging unit that urges the movable body toward the fixed mold with respect to the movable mold; The fixed mold has a direct gate that allows the material passage to communicate with the cavity, and the movable mold is configured such that the movable mold and the movable body are closed with the movable mold and the fixed mold closed. It has a gate closing portion fitted into the direct gate.

At the time of molding, a filling step, a pressure adjusting step, a measuring step, and a compressing step are performed in the same manner as in the injection molding die apparatus of the first aspect. First, the fixed mold and the movable mold are closed with a weak mold clamping force, and the movable body and the fixed mold are closed, while the movable body and the movable mold are still open. In this state, a filling process is performed in which the molding material is supplied to the material passage and the molding material is filled into the cavity from the fixed direct gate. In the pressure adjustment step following the filling step, the movable body and the fixed mold are opened with respect to the movable mold in accordance with the supply of the molding material to the mold apparatus, and the pressure of the molding material in the mold apparatus, the mold clamping force, and the like. By adjusting the pressure of the molding material in the cavity. In the measuring step after the pressure adjusting step, the movable mold and the moving body are closed by increasing the mold clamping force, and the molding material in the cavity is returned to the material supply device side. A fixed amount of molding material remains in the cavity when the gate closes after the movable gate closing portion starts to fit into the fixed direct gate. After this measuring step, that is, after the gate is closed, the movable mold and the moving body are closed until they abut against each other, and a compression step of compressing the molding material in the cavity is performed. The effect of the gate being a direct gate is the same as that of the injection molding die apparatus according to the first aspect of the present invention.

According to a third aspect of the present invention, in the injection molding apparatus of the first aspect, the first mold body keeps a thermoplastic resin in a material passage to the direct gate in a molten state at all times. It has a hot runner mechanism and a gate opening and closing mechanism for opening and closing the direct gate.

The thermoplastic resin as the molding material is
The hot runner mechanism keeps the mold in a molten state in the material passage both when the mold is closed and when the mold is opened. In particular, when the mold is opened, the gate opening / closing mechanism closes the gate to prevent leakage of the thermoplastic resin. In general, a gate of an injection molding die equipped with such a hot runner mechanism is a direct gate. However, as described above, by adopting a configuration in which a gate closing portion is fitted into the direct gate. In a mold apparatus for injection molding provided with a hot runner mechanism, molding including the filling step, the pressure regulation step, the measuring step, and the compression step becomes possible.

[0020]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an injection molding apparatus according to an embodiment of the present invention. 7 and 8 show examples of the product P to be molded.
The product P shown in FIG. 7 has one through hole P1 at the center, and the product P shown in FIG. 8 has a plurality of through holes P1. The axial direction of any of the through holes P1 matches the axial direction of the entire product P.

First, a first embodiment will be described with reference to FIGS. This embodiment is applied to injection molding using thermoplastic resin R as a molding material, and uses an in-line screw type injection molding machine as shown in FIG. In FIG. 5, reference numeral 1 denotes a heating cylinder device which is a material supply device. The heating cylinder device 1 has a substantially cylindrical cylinder body 2. In the cylinder body 2, a heater 3 for heating is provided on the outer periphery, and a nozzle 4 is provided at a tip portion (left portion in the figure). A hopper 5 is provided on the rear upper side of the cylinder body 2. The screw 6 is accommodated in the cylinder main body 2 so as to be rotatable and movable in the axial direction (left and right directions in the drawing). A piston rod 12 of a hydraulic cylinder 11 is fixedly connected to the rear side of the screw 6. That is, this hydraulic cylinder 11
Drives the screw 6 in the axial direction. The screw 6 is driven to rotate by an electric servomotor 13. In order to transmit rotation from the servo motor 13 to the screw 6, a gear 15 for transmitting rotation is spline-fitted to a spline cylinder 14 fixed to the outer periphery of the piston rod 12. That is, gear 15
Is stopped against the screw 6, but can move freely in the axial direction.

Reference numeral 21 denotes a direct pressure type mold clamping device. The mold clamping device 21 has a fixed platen 22 and a movable platen 23. The movable platen 23 is movable in the horizontal direction in the figure along the tie bar 24 and is driven by a hydraulic cylinder 25 via a mold clamping ram 26. The drive of the hydraulic cylinder 25 is controlled by a drive control device 27 including a servo valve and the like, so that the mold clamping force can be adjusted. The fixed mold 32 of the mold apparatus 31 is attached to the fixed platen 22, and the movable platen
The movable mold 33 is attached to 23. The mold clamping device 21 and the heating cylinder device 1 are comprehensively controlled by a control device such as a computer.

Next, the structure of the mold apparatus 31 will be described with reference to FIGS.
It will be described in detail based on. The mold apparatus 31 has the fixed mold 32 and the movable mold 33 as a second mold which constitute a first mold body 34.
Are opened and closed by the movement of the movable-side platen 23, and form a product-shaped cavity 35 therebetween when the mold is closed. The axial direction of the product P is fixed type 32 and movable type 33.
The mold opening and closing directions are matched. A movable plate 36, which is a movable body that abuts the fixed mold 32 to form the cavity 35, is supported by the movable mold 33 so as to be openable and closable in the mold opening and closing direction. This moving plate 36 is assembled to the movable mold 33,
In terms of molding function, a first mold body 34 is constituted together with the fixed mold 32. In the drawing, a parting line between the fixed die 32 and the movable plate 36 is indicated by PL1, and a parting line between the movable plate 36 and the movable die 33 is indicated by PL2.

The fixed die 32 includes a fixed mounting plate 41 mounted on the fixed platen 22, and a fixed main body 42 fixed to the movable die 33 side of the fixed mounting plate 41. A concave portion 43 is formed on the surface of the fixed die main body 42 on the movable die 33 side. The locate ring 44 is fixed to the fixed side mounting plate 41, and the fixed side mounting plate 41 and the fixed type main body 42 are fixed.
The sprue bush 45 is fixed inside the. This sprue bush 45 is used for the nozzle 4 of the heating cylinder device 1.
The sprue 46 has a material passage inside.
It has become. In addition, a direct gate 47 that allows the sprue 46 to communicate with the cavity 35 is formed in the fixed main body 42 that forms the cavity 35. The direct gate 47 has a substantially cylindrical shape whose axial direction coincides with the mold opening / closing direction. However, the shape of the direct gate 47 is not limited to a columnar shape, and may be any shape as long as the side generatrix is parallel to the mold opening and closing direction.

The movable mold 33 includes a movable mounting plate 51 attached to the movable platen 23, and a movable main body 53 fixed to the fixed mold 32 side of the movable mounting plate 51 via a spacer block 52. It has. A cavity 35 is provided on the surface of the movable mold body 53 on the fixed mold 32 side.
Are formed. Furthermore, this convex part
A gate closing portion 55 that forms a through hole P1 of the product P is formed at the center of the 54 to protrude. This gate closing portion 55
The fixed die 32 and the movable plate 36 are closed, and the movable plate 36 and the movable die are further closed.
The fitting 33 is fitted into the direct gate 47 of the fixed mold 32 as it closes. Therefore, the side surface shape of the gate closing portion 55 is different from the direct gate
Equivalent to 47 side shapes. A projecting plate 56 is supported between the movable mounting plate 51 and the movable main body 53 so as to be movable in the mold opening and closing direction. A product projecting pin 57 and a sprue projecting pin 58 are fixed to the projecting plate 56. These protruding pins 57, 58 slidably penetrate the movable mold body 53 forming the cavity 35, and the tips thereof are located facing the cavity 35. A sprue lock 59 is formed in the gate closing portion 55 of the movable main body 53 at a position where the tip of the sprue protrusion pin 58 faces.

The moving plate 36 is formed in a frame shape, and the convex portion 54 of the movable main body 53 is slidably fitted therein. That is, the inner side surface of the movable plate 36 and the convex portion 54 fitted to each other are parallel to the mold opening / closing direction. Further, the inner side surface of the moving plate 36 is
It is continuous with the side. A spring 61 as an urging means is sandwiched between the movable plate 36 and the movable main body 53 in a compressed state. The spring 61 urges the movable plate 36 toward the fixed mold 32 with respect to the movable mold 33,
When the moving plate 36 and the fixed mold 32 are in contact with each other,
The movable mold 33 and the movable mold 33 are urged in a direction to separate them from each other against the mold clamping force. In addition, as the urging means for urging the moving plate 36, an air cylinder or the like can be used in addition to the spring. In order to guide the movable plate 36 with respect to the fixed mold 32, a guide pin 62 fixed to the fixed mold 32 is provided.
Slidably penetrates Further, a sleeve 65 fixed by a bolt 64 together with a stopper 63 on the fixed mold 32 side of the movable mold body 53 penetrates the movable plate 36 slidably. The stopper 63 restricts the maximum gap between the movable plate 36 and the movable die 33, that is, the maximum opening amount by hitting the movable plate 36 from the fixed die 32 side.

Next, the injection molding method will be described. In the heating cylinder device 1, the plasticizing step and the injection step are repeatedly performed. In the plasticizing step, the thermoplastic resin R supplied into the cylinder body 1 from the hopper 5 is melted and plasticized by heating by the heater 3 and kneading by the rotation of the screw 6. Along with this plasticization, the resin R is sent forward by the rotation of the screw 6 and is accumulated at the tip side in the cylinder body 1.
Accordingly, the screw 6 moves backward due to the pressure of the resin R. During the plasticizing step, the hydraulic cylinder 11 also applies an appropriate back pressure to the screw 6 forward. When it is detected that the screw 6 has retreated to a predetermined position, the hydraulic cylinder 11 is driven to
The resin R on the tip side in the cylinder body 1 is injected from the nozzle 4 and supplied to the sprue 46 of the mold apparatus 31. When it is detected that the screw 6 has advanced to the predetermined position, or when the screw 6 has advanced to the advance limit, the plasticizing process starts again.

The mold clamping device 21 first closes the fixed mold 32 and the movable mold 32 with a weak and constant mold clamping force F1. At this time, as shown in FIG. 1, the fixed die 32 and the movable plate 36 abut and close. On the other hand, the movable plate 36 and the movable mold 33 are opened with the initial opening amount A1, but the stopper 63 does not hit the movable plate 36. That is, the mold clamping force F1 and the force G of the spring 61 are balanced. Further, the gate closing portion 55 of the movable mold 33 is not fitted to the direct gate 47 of the fixed mold 32, and the sprue 46 and the cavity 35 are communicated by the opened gate 47. In this state, the resin R is injected from the heating cylinder device 1 to the sprue 46. This resin R is a sprue 46
Through the gate 47 to fill the cavity 35 (filling step).

Subsequently to the filling step, the screw 6 is set in the heating cylinder device 1 while the mold clamping force is maintained at F1.
The injection process is continued until it is detected that has advanced to the predetermined position, or until the screw 6 has advanced to the advance limit. That is, although the supply of the resin R from the heating cylinder device 1 to the mold device 31 is still continued, as shown in FIG.
The movable mold is movable against the fixed mold 32 and the movable plate 36 against the mold clamping force F1 given by the mold clamping device 21 whose hydraulic pressure is not closed.
33 is displaced in the opening direction. Thereby, the generated internal pressure is released. The enlarged opening A2 between the movable plate 36 and the movable mold 33 is determined by the balance between the pressure of the resin R in the mold apparatus 31 and the mold clamping force. More specifically, the mold clamping force F1, the force G of the spring 61, and the resin R in the mold apparatus 31 are movable molds.
The opening amount A2 is determined by the balance with the force H for retracting 33. The opening amount A2 increases as more resin R is supplied into the mold apparatus 31. In other words, even if there is an error in the amount of the resin R supplied from the heating cylinder device 1, the error is absorbed by the change in the opening amount, and the pressure of the resin R in the cavity 35 is adjusted to be constant ( Pressure regulation step). Thus, the pressure of the resin R in the cavity 35 can be accurately controlled.

The force G of the spring 61 is slightly weakened by increasing the opening amount from A1 to A2, and the mold clamping force given by the hydraulic cylinder 25 when the mold clamping ram 26 is pushed back together with the movable mold 33. Although it may change slightly, the change in the force G of the spring 61 and the change in the mold clamping force are negligibly small. That is, the variation in the pressure of the resin R, which balances with the force G of the spring 51 and the mold clamping force, which varies according to the displacement of the movable mold 33, is caused by the pressure generated when a different amount of resin R is filled in a cavity having a fixed volume. It is much smaller than the variation.

After the pressure adjusting step is completed, the mold clamping device 21 increases the mold clamping force to F2. Thereby, the movable plate 36 and the movable mold 33 are closed. Accordingly, extra resin R in the cavity 35
Returns from the gate 47 which is still open to the sprue 46, and the resin R in the sprue 46 returns to the cylinder body 2 of the heating cylinder device 1. The screw 6 retreats accordingly. Then, as shown in FIG. 3, when the gate closing portion 55 of the movable mold 33 starts to be fitted into the direct gate 47 of the fixed mold 32, the gate 47 closes. R remains (a weighing step).

After this measuring step, as shown in FIG. 4, the movable plate 36 and the movable mold 33 are closed until they come into contact with each other, and accordingly, the resin R in the cavity 35 is pressurized and compressed (compression step). ). The compression amount is equal to the opening amount A3 between the movable plate 36 and the movable mold 33 at the end of the measuring process. The opening amount A3 is equal to the fitting length of the gate closing portion 55 to the direct gate 47. The compression compensates for shrinkage of the resin R due to solidification due to cooling. Therefore, it is not necessary to perform the pressure holding step on the side of the heating cylinder device 1 for this compensation.

At the end of the pressure regulation step, the volume of the cavity 35, that is, the amount of the resin R in the cavity 35 is not constant. However, in the subsequent measuring step, the resin R in the cavity 35 returns to the sprue 46 as described above, and a certain amount of the resin R remains in the cavity 35 at the moment when the gate 47 is closed. Thus, the pressure and amount of the resin R filled in the cavity 35 are accurately controlled by the pressure adjustment step and the measurement step. And, in the subsequent compression step, in the weighing step preceding it,
Since a certain amount of the resin R is left at a certain pressure in the cavity 35, the compression is smoothly performed.

After the resin R in the cavity 35 is sufficiently cooled and solidified, the fixed mold 32, the movable mold 33 and the movable plate 36 are opened by the mold clamping device 21. At this time, the moving plate
With the opening of the fixed mold 33 and the resin 36, the resin R in the cavity 35, that is, the product P and the resin R solidified in the sprue 46,
Due to the difference in release resistance between the fixed mold 32 and the movable mold 33, the fixed mold 32 is first separated from the fixed mold 32. Next, a projecting rod (not shown) provided on the mold clamping device 21 pushes the projecting plate 56 toward the fixed mold 32, so that the sprue ejecting pin 58 projects the resin R solidified in the sprue 46 to move the movable mold. The product P is released from the movable die 33 and the product push-out pin 57 projects the product P from the movable die 33. In addition, sprue
After the resin R and product P solidified in 46 are taken out,
The mold is closed again, and the above steps are repeated.

As described above, according to the configuration of the above embodiment, the pressure and amount of the resin R charged into the cavity 35 can be easily and accurately determined by the pressure adjusting step and the measuring step performed in the mold apparatus 31. Therefore, a high-precision product P with stable quality can be obtained. Also, by the compression process,
The transferability from the mold device 31 to the product P is improved, and the accuracy can be further improved.

Moreover, since the gate is a direct gate 47, the following effects can be obtained. Direct gate
47 is a sprue 46 to which the nozzle 4 of the heating cylinder device 1 is connected, which directly communicates with the cavity 35.
The material path to the cavity 35 is shorter than that of the side gate, etc.
There is an advantage that the hardening due to cooling is reduced. Thereby, the transferability from the mold apparatus 31 to the product P is improved, and the resin R in the cavity 35 can be smoothly returned to the sprue 46 at the time of the measuring step. In addition, the mold apparatus of the above embodiment
In 41, since the direct gate 47 is located at the position corresponding to the center of the product P, even when the resin R flows into the cavity 35 from the sprue 46, the sprue 46
When the resin R returns, the resin R flows more smoothly. Further, since the gate is a direct gate 47, the pressure of the resin R relating to the pressure adjustment, that is, the force that the resin R in the mold apparatus 31 applies to the mold apparatus 31 in the mold opening and closing direction, is almost completely fixed in the cavity 35 in the fixed mold 32. And the movable mold 33. Therefore, pressure adjustment is performed based on the cavity 35. This, combined with the fact that the resin R can flow smoothly during the measuring step, allows the pressure and amount of the resin R filled in the cavity 35 to be more accurately controlled. This ensures that the pressure of the resin R in the cavity 34 is kept constant.

In the first embodiment, the movable plate 36 is provided in addition to the fixed mold 32 and the movable mold 33. However, the movable plate 36 is not essential. For example, the mold apparatus of the first embodiment
In 31, the fixed mold 32 and the moving plate 36 may be integrated. In this case, an urging means such as a spring 61 for urging the fixed mold and the movable plate in a direction to open each other is assembled to one of the fixed mold and the movable mold, and is separated from the other when the mold is opened. The moving plate 36 is unnecessary because the gate is the direct gate 47. On the other hand, if the gate is a side gate, a moving plate different from the fixed type and the movable type is necessary to form a material passage such as a runner that can be separated from the cavity. However, when the fixed mold 32 and the movable plate 36 are integrated in the mold apparatus 31 of the first embodiment, when the mold is closed, the concave portion 43 of the fixed mold 32 and the convex portion 54 of the movable mold 33 are fitted to each other. Since the molds are separated when the mold is opened, alignment between the two becomes more severe. On the other hand, in the first embodiment, there is no problem since the moving plate 36 is always fitted to the convex portion 54 of the movable mold 33. Even if a movable plate different from the fixed type and the movable type is provided, the movable plate 36 can be assembled to the movable type 33 as in the first embodiment, or the movable plate can be assembled to the fixed type. is there.

Next, a second embodiment will be described with reference to FIG. Parts corresponding to those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The mold apparatus 31 of the second embodiment includes a fixed mold 32, a hot runner mechanism 71 that constantly keeps the thermoplastic resin R in a material passage to the direct gate 47 in a molten state, and a gate opening and closing that opens and closes the direct gate 47. The mechanism 72 is incorporated.

In order to constitute the hot runner mechanism 71, a spacer block 73 and a receiving plate 74 are provided on the fixed side mounting plate 41 side of the fixed type main body 42 forming the plurality of cavities 35, and these fixed side mounting plates 41 are provided. A manifold 75 is provided between the spacer block 73 and the receiving plate 74. The manifold 75 is provided therein with a runner 76 which is a branching material passage for connecting the sprue 46 to each cavity 35, and is provided with a heater (not shown) for heating the runner 76. I have. A plurality of valve casings 77 fixed to the manifold 75 are embedded in the receiving plate 74 and the fixed main body 42.
The inside of each valve casing 77 forms a material passage 78. The material passages 78 communicate with the final branch passages of the runners 76 of the manifold 75, respectively, and coaxially communicate with the corresponding direct gates 47 through the distal end openings of the valve casing 77, respectively. Each valve casing 77 is provided with a heater (not shown) for heating a material passage 78 therein. Further, the sprue bush 45 is also provided with a heater (not shown) for heating the sprue 46.

The gate opening / closing mechanism 72 comprises a valve pin 82 which moves in the mold opening / closing direction by driving a hydraulic cylinder 81 provided on the fixed side mounting plate 41, and is provided for each of the plurality of direct gates 47. . The valve pin 82 is connected to the manifold 75 and the valve casing 77
It penetrates through the inside, and is inserted into and removed from the direct gate 77 so as to open and close the direct gate 77.

In the mold apparatus 31 of the second embodiment, the sprue protruding pin 58 which is used in the mold apparatus 31 of the first embodiment is unnecessary.

During molding, the thermoplastic resin R in the sprue 46 of the sprue bush 45, the runner 76 of the manifold 75, and the material passage 78 of the valve casing 77 is in a molten state when the mold is closed and when the mold is opened by heating the heater. Is kept. Accordingly, the thermoplastic resin R as a molding material is not wasted, and the molding cycle can be sped up.
At the time of opening the mold, as shown by a solid line in FIG. 6, the valve pin 82 is fitted into the direct gate 47 to close the direct gate 47, thereby preventing the molten thermoplastic resin R from leaking from the direct gate 47. .

In the mold apparatus 31 of the second embodiment, the filling step, the pressure adjusting step, the measuring step and the compression step can be performed in the same manner as in the mold apparatus 31 of the first embodiment. The same operation and effect as those of the first embodiment can be obtained. of course,
From the start of the filling step to the end of the compression step, the valve pin 82 comes out of the direct gate 47 and opens the direct gate 47 as shown by a chain line in FIG.

In the mold apparatus 31 according to the second embodiment, the one that closes the direct gate 47 is switched from the gate closing portion 55 of the movable mold 33 to the valve pin 82 of the fixed mold 32 as the mold is opened. At this time, in order to prevent the thermoplastic resin R from leaking from the gate 47, for example, the following may be performed. The axial dimensional relationship between the gate closing portion 55 and the direct gate 47 is such that the gate closing portion 55 closes the direct gate 47 over its entire length. After the compression step is completed, the valve pin 82 is brought into contact with the gate closing portion 55 before the mold is opened.
Until the valve pin 82 is fitted to the 47, the state where the valve pin 82 and the gate closing portion 55 are in contact with each other is maintained.

The injection molding die apparatus 31 provided with the hot runner mechanism 71 generally has a direct gate 47, but the gate closing portion 55 is fitted into the direct gate 47 by adopting a structure. , Hot runner mechanism
In the injection molding die apparatus 31 provided with 71, molding including the filling step, the pressure adjusting step, the measuring step, and the compression step becomes possible.

In the mold apparatus 31 of the second embodiment,
In order to close the direct gate 47 when the mold is opened, the valve pin 82 is fitted to the direct gate 47. However, the configuration for closing the direct gate when the mold is opened is not limited thereto. For example, an open gate system in which the gate is opened and closed by melting or solidifying the thermoplastic resin R in the gate portion by heating or cooling the hot chip is also used.

Further, the present invention is not limited to the above embodiment, and various modifications can be made. For example, the product P to be molded is not limited to the one shown in FIG. 7, but may be of various shapes. For example, as shown in FIG. 8, the product P may have a plurality of through holes P1. These through holes P1 are formed by fitting projections provided on one of the fixed type and the movable type with holes provided on the other, and this hole can be appropriately set as a direct gate. It is also possible to provide a plurality of direct gates for one cavity. Further, by arranging the direct gate so as to face the outer side surface of the product P, the configuration of the present invention can be applied to a product having no through hole.

In the above embodiment, the case where an in-line screw type injection molding machine is used has been described as an example, but various types of molding machines such as a plunger type may be used. As the mold clamping device, various types such as a toggle type and a direct pressure type as in the above embodiment can be used. The drive source of the mold clamping device is not limited to the hydraulic cylinder, but may be an electric motor or the like.

Further, in the above embodiments, injection molding of a thermoplastic resin has been described as an example. However, the present invention is not limited to injection molding of ceramics using a thermoplastic resin as a binder, injection molding powder metallurgy, or thermoforming. It is applicable to injection molding of various molding materials such as injection molding of curable resin.

[0050]

According to the first aspect of the present invention, there is provided an urging means for urging the first mold and the second mold in a direction in which the first mold and the second mold are opened to each other against the mold clamping force. Since the gate is closed as is closed, by performing the pressure adjustment step and the metering step in the mold apparatus, the pressure and amount of the molding material filled in the cavity can be easily and accurately controlled, and You can obtain high quality products with stable quality. The gate is a direct gate in the first mold, and the second mold is provided with a gate closing portion that fits in the direct gate as both molds close, so that the gate reaches the cavity. Since the curing of the molding material is reduced, the transferability from the mold apparatus to the product is improved, and the molding material in the cavity is smoothly returned to the material passage in the measuring step. At the same time, since the pressure is adjusted based on the cavity, the pressure and amount of the molding material filled in the cavity can be more accurately controlled.

According to the second aspect of the present invention, there is provided a movable body which is supported by a movable mold so as to be openable and closable and which abuts on a fixed mold, and an urging means for urging the movable body toward the fixed mold. Since the gate closes as the movable mold closes, the pressure and amount of the molding material filled in the cavity can be easily and accurately controlled by performing the pressure adjustment step and the measurement step in the mold device. It is possible to obtain high-precision products with stable quality. In addition, the gate is a fixed type direct gate, and the movable mold has a gate closing part that fits inside the direct gate as the moving body and the movable mold close, so pressure regulation is performed based on the cavity. In the measuring step, the pressure and the amount of the molding material filled in the cavity can be more accurately controlled by smoothly returning the molding material in the cavity to the material passage. Further, since the gate is a direct gate, curing of the molding material to the cavity is reduced, and transferability from the mold device to the product is improved.

According to the third aspect of the present invention, in addition to the effect of the first aspect of the present invention, the use of the hot runner mechanism makes it possible to eliminate the waste of the thermoplastic resin as the molding material and also to speed up the molding cycle. Performing the pressure regulation step, the measurement step, and the compression step in the injection molding die apparatus equipped with a hot runner mechanism, the gate is a direct gate,
This is made possible by adopting a configuration in which the gate is closed by a gate closing portion fitted into the gate.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of an injection molding die apparatus according to the present invention, showing a state before a filling step.

FIG. 2 is a cross-sectional view in which a part of the above is closed, showing a pressure adjusting step.

FIG. 3 is a cross-sectional view in which a part of the above is closed, showing a measuring step.

FIG. 4 is a cross-sectional view in which a part of the above is closed, showing a compression step.

FIG. 5 is a side view, partially in section, showing the entire apparatus used for injection molding;

FIG. 6 is a sectional view showing a second embodiment of the injection molding die apparatus of the present invention.

FIG. 7 is a perspective view showing a product molded by the injection molding die apparatus of the above-mentioned two embodiments.

FIG. 8 is a perspective view showing another example of a product to be molded.

[Explanation of symbols]

 31 Mold device 32 Fixed mold 33 Movable mold (second mold) 34 First mold 35 Cavity 36 Moving plate (moving body) 46 Sprue (material passage) 47 Direct gate 55 Gate closing part 61 Spring (biasing) Means) 71 Hot runner mechanism 72 Gate opening / closing mechanism 76 Runner (material passage) 78 Material passage

Continuation of front page (56) References JP-A-1-209119 (JP, A) JP-A-6-297513 (JP, A) JP-A-7-329125 (JP, A) JP-A-55-74849 (JP) JP-A-7-232358 (JP, A) JP-A-6-71698 (JP, A) JP-A-7-329124 (JP, A) JP-A-58-130714 (JP, U) (58) Field surveyed (Int.Cl. ⁷ , DB name) B29C 45/26-45/44

Claims (3)

(57) [Claims] A first mold having a material passage therein;
A second mold body that opens and closes with respect to the first mold body and forms a cavity with the first mold body when the mold is closed, and clamps the first mold body and the second mold body with each other; Biasing means for biasing each other in a direction to open against each other, wherein the first mold body includes:
A direct gate that communicates the material passage with the cavity, wherein the second mold fits into the direct gate as the second mold and the first mold close. A mold device for injection molding, comprising a gate closing portion. 2. A fixed mold having a material passage therein, a movable mold that opens and closes the fixed mold and forms a cavity between the fixed mold when the mold is closed, and the movable mold includes the fixed mold and the movable mold. A movable body that is supported so as to be openable and closable in the opening and closing direction of the mold and abuts on the fixed mold, and a biasing unit that biases the movable body toward the fixed mold with respect to the movable mold; And a direct gate that communicates the material passage with the cavity. The movable mold includes a direct gate inside the movable gate when the movable mold and the movable body are closed with the movable mold and the fixed mold closed. An injection molding die apparatus, comprising: a gate closing portion that fits into a mold. 3. The first mold body has a hot runner mechanism for keeping a thermoplastic resin in a material passage to the direct gate in a molten state at all times, and a gate opening / closing mechanism for opening and closing the direct gate. The mold apparatus for injection molding according to claim 1, wherein: