JP3222832B2 - Injection molding apparatus and injection molding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an injection molding apparatus and an injection molding method.

[0002]

2. Description of the Related Art Conventionally, in an injection molding machine, resin injected from an injection nozzle of an injection device is sent to a runner through a sprue of a mold device, and then passes through a sub-runner branched from the runner. To the gate, through which the cavity is filled.

FIG. 2 is a first view showing a structure near a conventional gate, FIG. 3 is a view showing a state of a molded product during a conventional mold opening process, and FIG. 4 is a view showing a structure near a conventional gate. It is a 2nd figure. In the figure, 111 is a sub-runner, 112 is a gate, and 113 is a cavity space. In the injection step, the resin injected from an injection nozzle (not shown) is sent to a runner (not shown) through a sprue (not shown), and then sent to a gate 112 through a sub-runner 111 branched from the runner. Gate 112
To fill the cavity space 113. And
When the filling of the resin is completed, a pressure-holding step is started to maintain the pressure of the resin in the cavity space 113, and a cooling step is started to cool the resin in the cavity space 113,
Is solidified. Subsequently, the mold is opened by driving a mold clamping device (not shown), and the molded product formed in the cavity 113 is taken out.

[0004] At this time, as the mold is opened, the sub-runner portion P1 and the molded product portion P3 of the solidified resin are separated at the gate portion P2. As a result, the gate portion P2 is broken, but if the resin is not sufficiently cooled during the cooling step, the cut of the resin becomes poor, and a gate residue 114 is formed at the tip of the gate portion P2 on the molded product portion P3 side.
Is formed.

If the gate 112 is a pinpoint gate, a hot runner gate, or the like, the resin is hardly cut, and the gate residue 114 is easily formed. Therefore, the tip end of the gate residue 114 is
The mold device, the molded product and the like are designed so as not to protrude from the surface of No.3. That is, as shown in FIG. 4, the gate 112 is largely dropped into the cavity space 113,
The thickness δ1 near the gate 112 is changed to the cavity space 113.
Is sufficiently smaller than the thickness δ2.

[0006]

However, in the conventional injection molding machine, since the gate 112 is dropped into the cavity space 113, the thickness is 1 [m].
m] When trying to mold the following molded article, the gate 112
Of the gate 1 when filling the cavity space 113 with the resin in the injection step becomes extremely small.
The pressure loss in the vicinity of 12 becomes large. As a result, it becomes difficult to fill the resin.

Further, since the pressure of the resin is concentrated near the gate 12, warpage occurs in the molded product, and the quality of the molded product is reduced. Further, since the pressure of the resin required for filling increases, not only the size of the injection device but also the size of the mold device and the mold clamping device increases accordingly, and the size of the injection molding machine increases.

The present invention solves the above-mentioned problems of the conventional injection molding machine, can easily fill the resin, improve the quality of the molded product, and reduce the size of the injection molding machine. And an injection molding method.

[0009]

For this purpose, in the injection molding apparatus according to the present invention, a cavity is provided between the stationary die and the stationary die so as to be able to come into contact with and separate from the stationary die. A movable mold for forming a space, a gate push-in pin having a front end facing the cavity space, and the front end facing the gate, and being disposed so as to be able to move forward and backward; And a pin driving means which is moved to the pushing position after the injection step is completed. Then, the gate is dropped into the cavity space, the thickness of the vicinity of the gate in the cavity space is made smaller than the thickness of the cavity space, and becomes large when the gate pushing pin is placed at the retracted position. It is reduced when the pin is in the advanced position. In another injection molding apparatus of the present invention, the front end of the gate push-in pin is located rearward of the molded part at the retracted position.

In the injection molding method of the present invention, the mold closing device is driven to close and close the mold. In the injection step, the resin is filled into the cavity through a gate, and in the pressure holding step, the cavity is filled. In the cooling step, the resin in the cavity space is cooled while maintaining the pressure of the resin inside, and the mold clamping device is driven to open the mold. And, in the injection step, the gate push pin arranged opposite to the gate is placed at a retracted position where the front end is behind the molded product part, so that the thickness near the gate in the cavity space is increased, and the injection is performed. After the process is completed, it is advanced and placed at the pushing position to reduce the thickness of the cavity space near the gate.

In another injection molding method of the present invention, the gate push-in pin is advanced after the pressure-holding step is started. In still another injection molding method of the present invention, the gate pushing pin is further advanced after a cooling step is started.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic view of an injection molding apparatus according to an embodiment of the present invention, and FIG. 5 is a view showing a drive cylinder control valve according to the embodiment of the present invention. In the drawing, reference numeral 10 denotes a fixed platen, 11 denotes a fixed-side mounting plate, 12 denotes a runner stripper plate, and 13 denotes a fixed-side template, and a sprue bush 17 is provided at the center of the fixed-side mounting plate 11 and the runner stripper plate 12.
Is provided, and a sprue 18 is provided in the sprue bush 17.
Is formed. A runner 19 is formed in the fixed mold plate 13 so as to communicate with the sprue 18, and the sub-runner 2 is formed in communication with the runner 19.
0 is formed. The fixed mounting plate 11, the runner stripper plate 12, and the fixed mold plate 13 form a fixed mold 15, and the fixed mold 15 is detachably mounted on the fixed platen 10. When the fixed mold 15 is attached to the fixed platen 10, the fixed mold 15 is positioned by the locate ring 16.

Reference numeral 21 denotes a heating cylinder of the injection device;
Reference numeral 2 denotes an injection nozzle formed at the front end of the heating cylinder 21. The injection nozzle 22 is moved forward and backward together with the injection device, and is brought into and away from the sprue bush 17. A screw 23 is provided in the heating cylinder 21 so as to be rotatable and advance and retreat. Reference numeral 30 denotes a movable platen, and the movable platen 30 is disposed to be able to advance and retreat along a tie bar (not shown). 31 is a movable side mounting plate, 32 is an ejector space block, 33
Is a back plate, and 34 is a movable mold plate. When the mold is clamped, the movable mold plate 34 and the fixed mold plate 13 are brought into pressure contact with each other, and between the movable mold plate 34 and the fixed mold plate 13. A cavity space 36 is formed. The sub-runner 20
A gate 37 is formed between and the cavity space 36. The movable-side mounting plate 31, the ejector space block 32, the back plate 33, and the movable-side mold plate 3
The movable mold 35 is constituted by 4 and the movable mold 35 is detachably mounted on the movable platen 30.
Therefore, the movable mold 35 is disposed so as to be able to freely contact and separate from the fixed mold 15, and forms a cavity space 36 between the movable mold 35 and the fixed mold 15 at the time of mold clamping.

A mold clamping device for moving the movable platen 30 forward and backward to close, close and open the mold is provided behind the movable platen 30 (left side in FIG. 1). The mold clamping device includes a mold clamping cylinder 41 and a hydraulic circuit (not shown) for operating the mold clamping cylinder 41. The mold clamping cylinder 41 includes a cylinder body 42,
And a piston 43 disposed slidably (slidably) in the cylinder main body 42, and the inside of the cylinder main body 42 is partitioned by the piston 43. The piston 43 includes a head 44 and a rod 45. A first oil chamber 46 is provided on the head 44 side in the cylinder body 42, and a second oil chamber 47 is provided on the rod 45 side in the cylinder body 42.
Are respectively formed.

The first oil chamber 46 is provided with an oil passage L-1.
Is supplied through the oil passage L, and the oil in the second oil chamber 47 is supplied to the oil passage L.
Draining through -2, the piston 43 is advanced (moved to the right in FIG. 1), and the mold can be closed and clamped. Further, an oil passage L is provided in the second oil chamber 47.
When the oil in the first oil chamber 46 is drained through the oil passage L-1, the piston 43 is moved backward (moves to the left in FIG. 1) to open the mold. It can be carried out. In addition, hydraulic pressure is supplied to the first and second oil chambers 46 and 47 via a mold clamping cylinder control valve (not shown).

After the mold is closed and clamped, the injection process is started at a predetermined timing, and the resin is injected from the injection nozzle 22. The resin is sprue 18
To the runner 19, from the runner 19 to the gate 37 through the sub-runner 20, and through the gate 37 to fill the cavity space 36. When the injection step is completed, the pressure-holding step is started, the pressure of the resin in the cavity space 36 is maintained, and the cooling step is started to cool the resin.
The mold is opened while a molded product (not shown) is left on the fifth side. At this time, the molded product is pushed down.

For this purpose, the back plate 33 and the movable mold plate 34 are made to penetrate, and the front end (the right end in FIG. 1)
The ejector pin 51 is disposed so as to face the cavity space 36. After the opening of the mold is started, the ejector pin 51 is protruded from the movable mold 35 to separate the molded product from the movable mold 35 and push it down. The head g formed at the rear end (left end in FIG. 1) of the ejector pin 51 is sandwiched and fixed by the ejector plates 52 and 53. The ejector plates 52, 53
Is supported so as to be able to move forward and backward, and advances the ejector pin 51 as it advances. An ejector rod 54 is brought into contact with the rear end of the ejector plate 53.

The ejector rod 54 is moved forward and backward by selectively supplying hydraulic pressure to an oil chamber of an ejector cylinder (not shown). Therefore, by operating the ejector cylinder, the ejector plate 52,
The ejector pin 51 can be moved forward and backward by moving the ejector pin 53 forward and backward. In addition, 55 is a guide rod. Further, the ejector plates 52 and 53, the back plate 33 and the movable mold plate 34 are made to penetrate, and the front end is formed in the cavity space 3.
A gate pushing pin 61 is provided facing the gate 6 and facing the gate 37. The gate push-in pin 61 has a rearmost retracted position, a push-in position set forward of the retracted position, and a projected position at which a molded product is projected.

The head h formed at the rear end of the gate pushing pin 61 is provided with a gate pushing pin plate 6.
It is sandwiched and fixed by 2, 63. The gate pushing pin plates 62 and 63 are supported so as to be able to move forward and backward, and advance the gate pushing pin 61 as they move forward. Further, a gate pushing rod 64 is brought into contact with the rear end of the gate pushing pin plate 63. Reference numeral 65 denotes a rod protruding rearward from the gate pressing pin plate 63.

Further, a pin driving means is provided for moving the gate pushing pin 61 forward and backward.
It comprises a drive cylinder 71, a hydraulic circuit (not shown) for operating the drive cylinder 71, and a control device (not shown) for operating the hydraulic circuit. The drive cylinder 7
1 has a cylinder main body 72 and a piston 73 slidably disposed in the cylinder main body 72, and the inside of the cylinder main body 72 is partitioned by the piston 73. The piston 73 includes a head 74 and the gate pushing rod 64. A first oil chamber 76 is provided on the head 74 side in the cylinder body 72, and a second oil chamber is provided on the gate pushing rod 64 side in the cylinder body 72. 77 is formed.

The first oil chamber 76 has an oil passage L-3.
Is supplied through the oil passage L, and the oil in the second oil chamber 77 is supplied to the oil passage L.
When drained through -4, the piston 73 is advanced, and the gate pushing pin 61 can be advanced through the gate pushing pin plates 62, 63. When the oil pressure is supplied to the second oil chamber 77 via the oil passage L-4 and the oil in the first oil chamber 76 is drained via the oil passage L-3, the piston 73 is retracted. The gate pushing pin 61 can be retracted via the gate pushing pin plates 62 and 63. The first and second oil chambers 76, 7
7 is supplied with hydraulic pressure via a drive cylinder control valve 81 shown in FIG.

The drive cylinder control valve 81 is connected to an oil passage L-
5, a hydraulic pump 83 as a hydraulic supply source via a pressure regulating valve 82 and an oil passage L-6, an oil tank 84 via an oil passage L-7, and a first oil via an oil passage L-3. The chamber 76 is connected to the second oil chamber 77 via an oil passage L-4, and takes positions A, B and N by selectively driving the solenoids a and b. Then, the solenoid a is driven,
When the solenoid b is stopped, the drive cylinder control valve 81 takes the position A, connects the oil passages L-5 and L-3, and the oil passages L-4 and L-7, and stops the solenoid a. When the solenoid b is driven, the drive cylinder control valve 81 takes the position B, connects the oil passages L-5 and L-4, and the oil passages L-3 and L-7, and connects the solenoids a and b. When stopped, the drive cylinder control valve 81 assumes the position N, and the oil passages L-3, L-4, L-5, and L-7 are shut off from each other. Therefore, when the solenoids a and b are selectively driven by the control device, the gate push pin 61 can be moved forward and backward or stopped via the gate push pin plates 62 and 63. The oil passage L-5 is provided with a pressure gauge 85 for measuring the oil pressure in the oil passage L-5.

The ejector cylinder is actuated to move the ejector plates 52 and 53 forward and backward, and the drive cylinder 71 is actuated to move the gate pushing pin plates 62 and 63 forward and backward. The dimensions of the ejector space block 32 are set so as to be adjusted. In the present embodiment, the drive cylinder 71 is provided behind the movable platen 30, but may be provided inside the movable platen 30. In addition, an electric motor such as a servomotor is used in place of the drive cylinder 71, and the rotational motion of the electric motor is converted into linear motion by motion direction converting means such as a ball screw, and the linear motion is converted into the gate pushing pin plates 62 and 63. Can also be transmitted to

Next, the operation of the injection molding apparatus having the above configuration will be described. FIG. 6 is a first diagram illustrating the operation of the injection molding device according to the embodiment of the present invention, and FIG. 7 is a second diagram illustrating the operation of the injection molding device according to the embodiment of the present invention. First, as the injection device (not shown) is advanced, the heating cylinder 21 is advanced (moves to the left in the drawing), and as shown in FIG.
Is pressed against the sprue bush 17. At this time,
A mold clamping force is generated by the mold clamping cylinder 41, mold clamping is performed, and the movable mold plate 34 is pressed against the fixed mold plate 13. At this point, the gate pushing pin 61 is located at the retracted position.

Subsequently, in an injection step, the screw 23 in the heating cylinder 21 is advanced by a driving means (not shown), and the resin stored in front of the screw 23 is injected from the injection nozzle 22 to the sprue 18.
To the runner 19, from the runner 19 to the gate 37 through the sub-runner 20, and through the gate 37 to fill the cavity space 36.

At this time, the gate pushing pin 61 is located at the retracted position, and the distance between the front end (right end in the figure) of the gate pushing pin 61 and the gate 37 is increased, so that the thickness near the gate 37 is increased. And the pressure loss in the vicinity of the gate 37 when the cavity space 36 is filled with resin in the injection step is reduced. Therefore, the resin can be easily filled.

Further, since the pressure of the resin does not concentrate near the gate 37, warpage does not occur in a molded product (not shown), and the quality of the molded product can be improved. Further, since the pressure of the resin required for filling is reduced, not only the size of the injection device but also the size of the mold device and the mold clamping device can be reduced correspondingly, and the size of the injection molding machine can be reduced. .

Subsequently, after the injection step is completed, the pressure holding step is started, and the pressure of the resin in the cavity space 36 is maintained. Then, the drive cylinder 71 is driven at a predetermined timing after the pressure-holding step is started, and as shown in FIG. 7, the gate push pin 61 is moved forward (moved rightward in the figure) to the push position. To be placed. as a result,
Since the distance between the front end of the gate pushing pin 61 and the gate 37 is reduced, the thickness in the vicinity of the gate 37 can be reduced, and a molded article having a predetermined shape can be formed.

Next, when the cooling process is started and the resin is solidified, the mold clamping cylinder 41 is driven, the movable platen 30 and the movable mold 35 are retracted, and the mold is opened. At this time, an ejector cylinder (not shown) is driven, and the ejector plate 5
2 (FIG. 1), 53 and the ejector pin 51 are advanced, and the molded product is ejected. At the same time, the drive cylinder 71 is driven, and the gate push-in pin 61 is further advanced to be placed at the projecting position, and the molded product is ejected.
In this way, the molded product can be removed from the mold device.

In the present embodiment, the drive cylinder 71 is driven after the pressure holding step is started, and the thickness in the vicinity of the gate 37 is reduced, so that the vicinity of the gate 37 is rapidly cooled in the cooling step. be able to. Therefore, it is possible to prevent the gate residue P114 from being formed at the tip of the gate portion P2 (see FIG. 3) with the mold opening.

In the present embodiment, the drive cylinder 71 is driven at a predetermined timing after the pressure-holding step is started. However, after the pressure-holding step is started, a further cooling step is performed. The drive cylinder 71 is driven at a predetermined timing after the start of the
Can be advanced and placed in the pushing position. It should be noted that the present invention is not limited to the above-described embodiment, but can be variously modified based on the gist of the present invention, and they are not excluded from the scope of the present invention.

[0032]

As described above in detail, according to the present invention, in an injection molding apparatus, a fixed die and a fixed die are disposed so as to be able to freely contact and separate from the fixed die. A movable mold that forms a cavity space between, a front end facing the cavity space, and a gate pushing pin disposed so as to be able to advance and retreat with the front end facing the gate, and the gate pushing pin, A pin driving means which is placed at the retracted position in the injection step, and is advanced and placed at the pushing position after the injection step is completed. Then, the gate is dropped into the cavity space, the thickness of the vicinity of the gate in the cavity space is made smaller than the thickness of the cavity space, and becomes large when the gate pushing pin is placed at the retracted position. It is reduced when the pin is in the advanced position.

In this case, in the injection step, since the distance between the front end of the gate pushing pin and the gate becomes longer, the thickness of the cavity space near the gate becomes larger,
In addition, pressure loss near the gate in the cavity space when the cavity space is filled with resin is reduced.
Therefore, even if the gate is dropped into the cavity space and the thickness of the cavity space near the gate is made smaller than the thickness of the cavity space, the resin can be easily filled. Further, since the pressure of the resin is not concentrated near the gate in the cavity space, warpage does not occur in the molded product, and the quality of the molded product can be improved.

Further, since the pressure of the resin required for filling is reduced, not only the size of the injection device can be reduced, but also the size of the mold device and the mold clamping device can be reduced accordingly. The injection molding machine can be downsized. Then, after the injection step is completed, the distance between the front end of the gate pushing pin and the gate is reduced, so that the thickness of the cavity space near the gate is reduced, and it is possible to mold a molded article of a predetermined shape. it can.

Further, in the cooling step, the vicinity of the gate in the cavity space can be rapidly cooled, so that it is possible to prevent a gate residue from being formed at the tip of the gate portion when the mold is opened.

[Brief description of the drawings]

FIG. 1 is a schematic view of an injection molding apparatus according to an embodiment of the present invention.

FIG. 2 is a first diagram showing a structure near a conventional gate.

FIG. 3 is a view showing a state of a molded product during a conventional mold opening process.

FIG. 4 is a second diagram showing a structure near a conventional gate.

FIG. 5 is a diagram showing a drive cylinder control valve according to the embodiment of the present invention.

FIG. 6 is a first diagram illustrating an operation of the injection molding apparatus according to the embodiment of the present invention.

FIG. 7 is a second diagram illustrating the operation of the injection molding apparatus according to the embodiment of the present invention.

[Explanation of symbols]

 15 Fixed mold 35 Movable mold 36 Cavity space 37 Gate 41 Mold clamping cylinder 61 Gate pushing pin 71 Drive cylinder

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B29C 45/26-45/44 G11B 7/26 511

Claims (5)

(57) [Claims] (A) a fixed mold; and (b) a movable mold that is disposed so as to be able to contact and separate from the fixed mold and forms a cavity space between the fixed mold and the mold when clamping. c) a gate pushing pin which is disposed so as to be able to move forward and backward with the front end facing the cavity space and the front end facing the gate; and (d) placing the gate pushing pin at the retracted position in the injection step; After the injection step is completed, the apparatus further includes a pin driving means for moving forward and placing it at the pushing position . (E) The gate is dropped into the cavity space,
The thickness near the gate in the cavity space
And the gate pushing pin
The gate push pin is large when the
An injection molding apparatus characterized in that it is reduced in size when placed in an advanced position . 2. In the retracted position, the gate is pushed in.
2. The method according to claim 1, wherein the front end of the pin is located behind the molded part.
Injection molding equipment. Wherein (a) type of clamping device is driven by the mold closing and mold clamping gastric row, in (b) injection process, through the gate and filling the resin into the cavity, (c) In the pressure-holding step , to maintain the pressure of the resin in the cavity space, in (d) a cooling step, the resin in the cavity space is cooled and performs mold opening by driving the (e) the mold clamping device, (f) the gate In the injection step, the front end of the gate pushing pin disposed opposite to the
Gates in the cavity to position it retracted position where the
By increasing the thickness of the vicinity of, after the injection process has been completed, to position it depressed position is advanced gate in the cavity
Injection molding, characterized in that the thickness in the vicinity of is reduced . 4. The injection molding method according to claim 3 , wherein the gate pressing pin is advanced after a pressure holding step is started. 5. The injection molding method according to claim 3 , wherein the gate pushing pin is advanced after a cooling step is started.