JP2003231123A - Material supplying method and apparatus therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact material supply apparatus low in cost capable of always supplying a proper amount of a material to an injection chamber. <P>SOLUTION: The material supply apparatus is equipped with an injection cylinder 12 having a nozzle 11 connected to the lower end thereof and having the injection chamber 13 extended in an almost vertical direction, an injection plunger 14 provided to the upper part of the injection cylinder 12 and capable of sliding in the injection chamber 13 at a lower part thereof, a jacket 22 connected to the injection cylinder 12 and having a material supply passage 21 extended in an almost horizontal direction, a material supply plunger 25 provided to the lateral part of the jacket 22 and slidable in the material supply passage 21, a hopper 27 connected to the jacket 22 to store a material Ps, a first communication passage 23 formed to the injection cylinder 12 to allow the injection chamber 13 and the material supply passage 21 to communicate with each other and a second communication passage 28 formed to the jacket 22 to communicate with the material supply passage 21 and communicating with the hopper 27 at its upper end. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material supply method and an apparatus therefor, and is particularly suitable for application to a vertical plunger injection molding apparatus.

[0002]

2. Description of the Related Art In a vertical plunger type injection molding apparatus or the like, when a material such as a resin pellet is supplied into an injection chamber of an injection cylinder, it has been customary to utilize the natural flow of the material itself.

FIG. 4 shows an example of such a conventional material supply apparatus for a vertical plunger type injection molding apparatus, for example. That is, the hopper 1 in which the resin pellets Ps are stored
The lower end of 01 is fixed to the jacket 103 attached to the upper end of the injection cylinder 102. Hopper 1
01 and the injection chamber 1 formed in the injection cylinder 102
04 is the material supply passage 105 formed in the jacket 103 and the communication passage 1 formed in the injection cylinder 102.
It is connected via 06. Therefore, the resin pellet Ps in the hopper 101 passes through the material supply passage 105 and the communication passage 106, and the injection chamber 10 of the injection cylinder 102.
It is thrown into 4.

The resin pellet Ps charged into the injection chamber 104 is gradually heated and melted by the heat generated by the band heater 107 surrounding the injection cylinder 102. The injection plunger 108 slidably fitted in the injection chamber 104 has its upper end side connected to an actuator 109 such as a hydraulic cylinder, and is fixed to the lower end of the injection cylinder 102 by the operation of this actuator 109. The descent is started toward the nozzle 110 side. By the descending operation of the injection plunger 108, the resin pellet Ps in the injection plunger 108 is strongly pressed against the inner wall surface of the injection cylinder 102 and the torpedo 111 assembled to the lower part of the injection chamber 1104, and its melting is accelerated. Then, the further downward movement of the injection plunger 108 causes the molten resin Pm to be injected from the nozzle 110 into the molding cavity of a mold (not shown).

Another example of a conventional material supply device is shown in FIG. This is one in which a feeder 112 is interposed between the hopper 101 and the jacket 103, and elements having the same functions as those of the material supply apparatus shown in FIG. 4 are designated by the same reference numerals.

The feeder 112 has a housing 114 connected to the jacket 103 via an end plate 113, a feed screw 115 rotatably accommodated in the housing 114, and a screw drive motor for rotatably driving the feed screw 115. 116 and. Hopper 1
01 is attached to the housing 114 of the feeder 112, and the resin pellets Ps in the hopper 101 flow down into the housing 114 via a charging path 117 formed in the housing 114. When the rotation of the feed screw 115 is stopped, the resin pellets Ps are discharged from the injection cylinder 1
No. 02 is not supplied into the injection chamber 104, but the screw driving motor 116 is operated to rotate the feed screw 115, so that the resin pellet Ps in the housing 114 forms a connection path 118 formed in the housing 114 and the end plate 113. The injection cylinder 102 from the material supply passage 105 of the jacket 103 through the communication passage 106.
Are sent into the injection chamber 104 of

[0007]

In the case of the conventional material supply apparatus shown in FIG. 4, since the resin pellets Ps are supplied obliquely from above to the injection chamber 104 of the injection cylinder 102, the hopper 101 is moved to the injection cylinder 102. Since it needs to be installed at a position considerably higher than the upper end, workability for inspection and replenishment of the resin pellets Ps may deteriorate. Further, since the amount of resin pellets Ps to be injected into the injection chamber 104 cannot be regulated, more resin pellets Ps than necessary are supplied into the injection chamber 104, or conversely, the resin pellets Ps are moved as the injection plunger 108 moves up and down. May be returned to the communication passage 106 side, and the amount of the molten resin Pm injected from the nozzle 110 into the mold may be insufficient. In particular, when an amorphous material such as polycarbonate is excessively supplied to the injection chamber 104, the injection stroke of the injection plunger 108 is gradually shortened, and the injection pressure is not sufficiently transmitted to the mold side. The dimensional fluctuation of the injection molded product is caused, and in the worst case, a short circuit occurs.

Such a problem can be alleviated to some extent by incorporating the feeder 112 shown in FIG. 5 into the material supply device. That is, the injection chamber 10
4 controls the amount of resin pellets Ps supplied to No. 4 by the number of rotations of the screw drive motor 116, or turns it on / off.
It can be controlled by switching off.
However, incorporating such an expensive feeder 112 into a small-sized injection molding apparatus leads to an increase in size of the apparatus and also has a problem in terms of equipment cost. Further, even if the feeder 112 is used, it is basically difficult to control the material supply amount to the injection chamber 104 with high accuracy, and in a continuous operation for a long time, the resin inside the injection chamber 104 is The pellets Ps may gradually accumulate, and the transmission of the injection pressure to the mold side may become insufficient, leading to dimensional fluctuations and short circuits of the molded product.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a simple method capable of always supplying an appropriate amount of material to an injection chamber and a compact material supply apparatus therefor at low cost.

[0010]

The first aspect of the present invention is as follows.
The step of causing the material stored in the hopper to flow down into a substantially horizontally extending material supply passage formed in the jacket, and the material flowing down into the material supply passage is formed in the injection cylinder by the forward movement of the material supply plunger. And pushing the material into the injection chamber into a substantially vertically extending injection chamber, and lowering the material fed into the injection chamber by the downward movement of the injection plunger while holding the material supply plunger at its forward end. And a step of determining whether the lower end position of the injection plunger is lowered to a preset position, the injection plunger is lowered to the preset position. If not, push the material in the material supply passage into the injection plunger If the step is not performed prior to the next injection operation and the injection plunger is lowered to a preset position, the step of pushing the material in the material supply passage into the injection plunger is performed prior to the next injection operation. A material supply method characterized by the above.

According to a second aspect of the present invention, an injection cylinder having an injection chamber extending substantially vertically with a nozzle connected to a lower end thereof, and a lower part provided above the injection cylinder and sliding inside the injection chamber. A movable injection plunger,
A jacket connected to the injection cylinder and having a material supply passage extending substantially horizontally, a material supply plunger provided on the side of the jacket and slidable in the material supply passage, and connected to the jacket And a first communication passage formed in the injection cylinder for communicating the injection chamber with the material supply passage, and a lower end formed in the jacket for communication with the material supply passage. Second with the upper end communicating with the hopper
The material supply device is characterized in that the material supply device is provided.

According to the present invention, the material stored in the hopper is caused to flow into the material supply passage through the second communication passage of the jacket by moving the material supply plunger to its retracted end position. On the other hand, by moving the material supply plunger to its forward end position in a state where the injection plunger is moved to its rising end position, the material flowing down into the material supply passage is transferred to the inside of the injection chamber via the first communication passage. And the material supply plunger is held at its forward end position while the injection plunger is moved to its descending end position to eject the material fed into the injection chamber from the nozzle.

Here, if the injection plunger has not descended to the preset position, the injection plunger is driven and the next injection operation is performed without pushing the material in the material supply passage into the injection plunger. Be seen. On the contrary, when the injection plunger is lowered to the preset position, the material supply plunger is driven to push the material in the material supply passage into the injection plunger, and then the injection plunger is driven to perform the next injection work. .

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION In the material feeding method according to the first embodiment of the present invention, the step of adjusting the amount of the material flowing down from the hopper into the material feeding passage by changing the retracted end position of the material feeding plunger. It can be further equipped.

The material supply apparatus according to the second aspect of the present invention may further include a sensor for detecting the lower end position of the injection plunger. In this case, the sensor may be capable of changing its mounting position along the up-and-down direction of the injection plunger.

The forward end position of the material supply plunger can be set in the first communication passage.

The material supply plunger may have its retracted end position adjustable so that the opening degree of the second communication passage can be changed.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the material supplying apparatus according to the present invention is applied to a vertical plunger type injection molding apparatus will be described in detail with reference to FIGS. 1 to 3. However, the present invention is only such an embodiment. Not limited to the above, any changes and modifications included in the concept of the present invention described in the scope of claims of the present specification are possible, and thus naturally applied to other technologies belonging to the spirit of the present invention. You can

FIG. 1 shows the schematic structure of the main part of the material supply apparatus in this embodiment, and FIG. 2 shows its injection state. That is, the injection chamber 1 formed in the injection cylinder 12 is above the injection cylinder 12 having the nozzle 11 pressed against the gate of a mold (not shown) at the lower end.
3, the injection plunger 14 slidably fitted to the injection chamber 3 is moved up and down in the injection chamber 13, the resin pellet Ps supplied into the injection chamber 13 is sent to the nozzle 11 side, and the nozzle 11 injects it into the mold. An ejection actuator 15 for performing the operation is provided. The injection actuator 15 may have any mechanism as long as it can move the injection plunger 14 up and down, but in general, a fluid that can pressurize the injection plunger 14 at an arbitrary pressure. Those using pressure are preferable. A pair of upper and lower sensors 16 and 17 for detecting the rising end position and the falling end position of the injection plunger 14 are attached to the injection actuator 15, and in this embodiment, the lower sensor with respect to the injection actuator 15 is attached. The mounting position of 17 can be arbitrarily changed along the vertical direction of the injection plunger 14.

A band heater 18 for softening and melting the resin pellets Ps supplied into the injection chamber 13 is wound around the lower portion of the injection cylinder 12.
In order to accelerate the heating by the band heater 18, a torpede 19 that causes the resin to flow down along the inner wall of the injection chamber 13 is provided below the injection chamber 13.
As is well known, the torpedo 19 is fixed to the center of the injection chamber 13 via spokes (not shown) that radially project from the outer circumference thereof.

In this embodiment, in order to maintain the molten state of the molten resin Pm injected from the nozzle 11 appropriately, the nozzle 11
The band heater 20 is also wound around the outer periphery of the mold, so that the molten resin Pm having an appropriate viscosity can be injected into the mold.

A jacket 22 having a material supply passage 21 extending substantially horizontally in the radial direction around the injection chamber 13 is fixed to the upper portion of the injection cylinder 12, and the above-mentioned injection cylinder 12 has a jacket 22. No. 22 of the material supply passage 21 extends in a straight line to connect the injection chamber 13 with the material supply passage 21 (second communication passage).
Communication passage 23) is formed. In the bracket 24 attached to the jacket 22, a material supply plunger 25 slidably fitted in the material supply passage 21 is reciprocated in the material supply passage 21.
A supply actuator 26 is provided for feeding the resin pellets Ps supplied therein into the injection chamber 13 via the communication passage 23. The forward end position of the material supply plunger 25 by the supply actuator 26 is set so that the tip of the material supply plunger 25 is located in the communication passage 23 adjacent to the injection plunger 14, as shown in FIG. Thereby, when the injection plunger 14 is lowered and the resin pellet Ps in the injection chamber 13 is pushed toward the nozzle 11 side, a problem that a part of the resin pellet Ps flows backward to the material supply passage 21 side is prevented beforehand. be able to. Further, the retreat end position of the material supply plunger 25 in the present embodiment can be arbitrarily changed along the longitudinal movement direction thereof.

When the above-mentioned injection plunger 14 is at its raised end position, the lower end of the injection plunger 14 is set at a position where it does not block the communication passage 23 of the injection cylinder 12.

A hopper 27 for storing a material such as resin pellets Ps, which is an injection molded product, is mounted on the jacket 22. The hopper 27 extends downward from the lower end of the hopper 27, and is connected to the hopper 27. A communication passage (first communication passage) 28 that communicates with the material supply passage 21 is formed. Therefore, the resin pellet Ps in the hopper 27 flows down from the communication passage 28 into the material supply passage 21 by its own weight, but since the material supply passage 21 is horizontal, the amount of the resin pellet Ps flowing down here is It stays in the desired equilibrium state. As described above, since the retreat end position of the injection plunger 14 can be arbitrarily changed, by setting the retreat end position of the injection plunger 14 to a position where the communication passage 28 is narrowed as shown in FIG. The amount of resin pellets Ps flowing down into the material supply passage 21 can be arbitrarily changed according to the amount of molten resin Pm injected from the nozzle 11.

Therefore, in the state shown in FIG. 1 in which the injection plunger 14 is retracted to its upper end defined by the upper sensor 16 and the material supply plunger 25 is at the backward end position, the hopper 27 passes through the communication passage 28. The resin pellet Ps that naturally flows into the material supply passage 21 stops inside the material supply passage 21 because the material supply passage 21 extends horizontally. When the nozzle 11 comes into contact with the mold with the mold clamped, the supply actuator 26
Is activated to start advancing the material supply plunger 25 from the retracted end position to the advanced end position, and the resin pellet Ps interposed in the material supply passage 21 is introduced into the injection chamber 13 from the communication passage 23. After the material supply plunger 25 reaches the advance end position, the injection actuator 15 operates and the injection plunger 14 starts descending from the ascending end position to the descending end position to remove the resin pellet Ps in the injection chamber 13. Push out to the nozzle 11 side. The molten resin Pm passing through the injection chamber 13 between the torpedo 19 and the injection cylinder 12 is injected from the nozzle 11 into the molding cavity (not shown) through the gate of the mold by the downward movement of the injection plunger 14.

When the amount of the resin pellets Ps supplied by the material supply plunger 25 is larger than the weight of the injection molded product, the amount of the resin in the injection chamber 13 increases with each shot, but in this embodiment. Since the lower sensor 17 detects the lower end position of the injection plunger 14, when the detection signal from the sensor 17 is not output even when the injection plunger 14 is lowered, that is, the injection plunger 14 is at the lower end position. If not reached, the material supply plunger 25 is not operated in the next shot, and only the injection plunger 14 is operated to perform the injection operation.
As a result, an optimum amount of resin can be always injected into the injection chamber 13.

[0027]

According to the material supply method of the present invention, when the injection plunger does not descend to the preset position during the injection work, the step of pushing the material in the material supply passage into the injection plunger is performed in the next injection work. If the injection plunger is lowered to a preset position, the step of pushing the material in the material supply passage into the injection plunger is performed prior to the next injection work, so that the material is injected by its own weight. It is possible to prevent the material from flowing down into the chamber, and it is possible to reliably prevent the excessive supply of the material from the material supply passage into the injection chamber.

When the retracting end position of the material supply plunger is changed to adjust the amount of material flowing down from the hopper into the material supply passage, the amount of material flowing down from the hopper into the material supply passage is regulated arbitrarily. It is possible to accurately supply the material according to the injection amount from the nozzle.

According to the material supply apparatus of the present invention, the jacket having the material supply passage extending substantially horizontally is connected to the injection cylinder, and the material supply plunger slidable in the material supply passage is provided on the side of the jacket. Since the first communication passage that connects the injection chamber and the material supply passage is formed in the injection cylinder, and the second communication passage whose lower end communicates with the material supply passage and whose upper end communicates with the inside of the hopper is formed in the jacket. The material can be prevented from excessively flowing down into the injection chamber by its own weight, and the material in the material supply passage can be fed into the injection chamber at any timing. Further, since an expensive and bulky material such as a feeder is not used, the material supply device can be made compact and at the same time can be manufactured at low cost.

When the sensor for detecting the lower end position of the injection plunger is provided, it can be easily and surely detected whether or not the injection plunger has descended to the predetermined lower end position, and the material supply passage can be detected. It is possible to prevent an excessive supply of material from the inside into the injection chamber. Especially when this sensor can change its mounting position along the up-and-down direction of the injection plunger, the injection amount of the material from the nozzle can be easily and arbitrarily adjusted.

When the forward end position of the material supply plunger is set in the first communication passage, it is possible to surely prevent the problem that the material is pushed back to the material supply passage side due to the lowering operation of the injection injection plunger. It is possible to accurately specify the injection amount of the material from the nozzle.

In order to change the opening degree of the second communication passage,
If the retracting end position of the material supply plunger can be adjusted, the amount of material flowing down from the hopper into the material supply passage can be regulated arbitrarily and the material can be accurately supplied according to the injection amount from the nozzle. You can

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of an embodiment in which a material supply device according to the present invention is applied to a vertical plunger type injection molding device, showing a standby state.

FIG. 2 is a sectional view showing a state during an injection operation in the embodiment shown in FIG.

FIG. 3 is a cross-sectional view showing a state in which the flow amount from the hopper is regulated in the embodiment shown in FIG.

FIG. 4 is a sectional view showing an example of a conventional material supply device for a vertical plunger type injection molding device.

FIG. 5 is a cross-sectional view showing another example of a conventional material supply device for a vertical plunger type injection molding device.

[Explanation of symbols]

11 nozzles 12 injection cylinder 13 Injection chamber 14 Injection plunger 15 Injection actuator 16,17 sensor 18 band heater 19 Torpedo 20 band heater 21 Material supply passage 22 jacket 23 communication passage 24 bracket 25 Material Supply Plunger 26 Supply actuator 27 hoppers 28 passages Ps resin pellet Pm molten resin

Claims (7)

[Claims] 1. A step of causing the material stored in the hopper to flow down into a substantially horizontally extending material supply passage formed in a jacket, and a step of moving the material flowing down into the material supply passage by a forward movement of a material supply plunger. Extruding into a substantially vertically extending injection chamber formed in the injection cylinder, while holding the material supply plunger at its forward end,
Injecting the material sent into the injection chamber from the nozzle connected to the lower end of the injection cylinder by the downward movement of the injection plunger, and the lower end position of the injection plunger is lowered to a preset position. If the injection plunger has not descended to a preset position, the step of pushing the material in the material supply passage into the injection plunger is not performed prior to the next injection operation. A method of supplying material, wherein when the injection plunger is lowered to a preset position, the step of pushing the material in the material supply passage into the injection plunger is performed prior to the next injection operation. 2. The method according to claim 1, further comprising the step of adjusting the amount of material flowing down from the hopper into the material supply passage by changing the retracted end position of the material supply plunger. The material supply method described. 3. An injection cylinder having a nozzle connected to a lower end thereof and having an injection chamber extending substantially vertically, and an injection plunger provided above the injection cylinder and having a lower part capable of sliding in the injection chamber. A jacket connected to the injection cylinder and having a material supply passage extending substantially horizontally, a material supply plunger provided on a side of the jacket and capable of sliding in the material supply passage, and connected to the jacket. A hopper that stores material, a first communication passage that is formed in the injection cylinder and connects the injection chamber and the material supply passage, and a lower end that is formed in the jacket and that communicates with the material supply passage. A material supply device, comprising: a second communication path having an upper end communicating with the inside of the hopper. 4. The material supply apparatus according to claim 3, further comprising a sensor for detecting a lower end position of the injection plunger. 5. The material supply apparatus according to claim 4, wherein the sensor is capable of changing its mounting position along the vertical direction of the injection plunger. 6. The material supply apparatus according to claim 3, wherein a forward end position of the material supply plunger is set in the first communication passage. 7. The material supply plunger according to claim 3, wherein a retracting end position of the material supply plunger is adjustable so as to change an opening degree of the second communication passage. The material supply device according to.