JPH07137102A - Injection device - Google Patents

Abstract

PURPOSE:To cool a screw almost without changing a structure of an injection device. CONSTITUTION:A heating cylinder 1 and a screw 21 which is arranged in the heating cylinder l rotatably and movably back and forth and has a hollow sealed inside thereof are provided. In a measuring process, when the screw 21 is retracted rotatably, a resin supplied into the heating cylinder 1 is melted and stored in the front part of the screw 2. At this time, the resin receives a shearing force and heats. A high temperature part H is formed near the tip of the screw 21. A low temperature part L having a radiating means is formed near the back end, and a heating medium is sealed in the hollow. Accordingly, the heat of the screw 21 is absorbed by the heating medium at the high temperature part L and radiated at the law temperature part L, so that the screw 21 can be cooled almost without changing a structure of an injection device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection device.

[0002]

2. Description of the Related Art Conventionally, a resin which is heated and melted in a heating cylinder is filled in a cavity of a mold at a high pressure and then cooled to be solidified or hardened.
Next, there are two types of injection molding machines that open the mold to take out the molded product, a plunger type that advances and retracts the plunger to perform injection molding, and a screw type that advances and retracts the screw to perform injection molding. . A plunger-type injection molding machine is generally inferior to a screw-type injection molding machine in terms of plasticizing ability of a resin, and a loss of injection pressure is large. It is used.

FIG. 2 is a sectional view of a main part of an injection device in a conventional injection molding machine. As shown in the figure, a screw 2 is rotatably and movably arranged in a heating cylinder 1 of the injection device. Here, although the screw 2 is in a state where the injection molding shot is finished, the screw is subsequently heated and melted toward the next injection molding shot, and the resin is accumulated at the tip of the screw head 9. To be
Therefore, the screw 2 is driven by a drive system (not shown) and retracts. At this time, the resin supplied from the hopper (not shown) is heated in the heating cylinder 1 while moving forward in the groove 3 by the rotation of the screw 2. Then, they are melted and stored at the tip of the screw head 9.
The pressure of the resin in the heating cylinder 1 generated by the melting serves as a reaction force against the screw 2, and the reaction force causes the screw 2 to retract.

Subsequently, in the injection step, the resin stored at the tip of the screw head 9 is injected from the injection nozzle 4 by pushing the screw 2 forward (to the left in the drawing) by the drive system, and a mold not shown Filled in the cavity. At this time, a part of the resin tries to flow backward (to the right in the figure) through the groove 3 of the screw 2 due to the reaction force against the injection pressure applied at the time of injection. Therefore, in order to prevent this, the check ring 6 is arranged in front of the screw 2.
Then, in order to prevent the check ring 6 from coming off the screw 2, the screw main body portion 8 of the screw 2 and the screw head 9 are separately formed, and the screw portion 14 is screwed (rago).
By doing so, both are fixed.

The screw head 9 has a large diameter portion 9a and a small diameter portion 9b. By making the outer diameter of the large diameter portion 9a larger than the inner diameter of the check ring 6, the check ring 6 does not come off. It is like this. Further, the check ring 6 forms an annular resin flow passage 10 between itself and the small diameter portion 9b of the screw head 9, and opens the resin flow passage 10 in the measuring step in which the screw 2 retracts. 10
The resin is sent to the tip of the screw head 9 via. On the other hand, in the injection process in which the screw 2 advances, the check ring 6 abuts the seal ring 11 to close the resin flow path 10 and prevent the resin from flowing back. In addition, 12 is a check ring 6 and a screw head 9.
Is a locking portion for preventing relative rotation of the.

[0006]

However, in the conventional injection device, the resin receives a shearing force in the measuring process to generate heat, and the screw 2 is overheated, causing the resin to burn. . The resin burn occurs particularly in the metering zone near the tip of the screw head 9.

Therefore, it can be considered that the screw 2 is hollow and water or air is supplied from the end surface of the screw 2 to cool the screw 2 by the water or air.
However, as described above, the screw 2 is retracted while rotating in the measuring process, and is advanced in the injection process. Therefore, it is difficult to supply water or air into the screw 2 that moves forward and backward or rotates due to the structure of the injection device, and the cost increases.

An object of the present invention is to solve the problems of the conventional injection device and to provide an injection device capable of cooling a screw without substantially changing the structure of the injection device.

[0009]

To this end, in the injection apparatus of the present invention, a heating cylinder and a hollow portion which is rotatably and movably arranged in the heating cylinder and which is sealed inside are formed. With a screw. Further, a high temperature portion is formed near the tip of the screw and a low temperature portion provided with a heat radiating means is formed near the rear end, and the heat medium is enclosed in the hollow portion.

[0010]

According to the present invention, as described above, in the injection device, the heating cylinder and the screw which is rotatably and reciprocally disposed in the heating cylinder and has a sealed hollow portion formed therein are formed. Have and. In the measuring step, when the screw is retracted while rotating, the resin supplied into the heating cylinder is melted and stored in front of the screw. At this time, the resin receives a shearing force and generates heat.

Further, a high temperature portion is formed near the tip of the screw and a low temperature portion provided with a heat radiating means is formed near the rear end, and a heat medium is enclosed in the hollow portion. Therefore, the heat of the screw is absorbed by the heat medium in the high temperature portion and is radiated in the low temperature portion.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 is a sectional view of an injection device according to a first embodiment of the present invention, FIG. 3 is an enlarged view of a screw according to the first embodiment of the present invention, and FIG. 4 is a sectional view taken along line AA of FIG. As shown in the figure, the heating cylinder 1 of the injection device
A screw 21 is rotatably and movably arranged therein.

Here, the screw 21 is in a state where the injection molding shot is finished, but subsequently, a measuring process is started, and the resin is heated and melted toward the next injection molding shot, so that the screw head 9 of the screw head 9 is melted. Stored at the tip.
Therefore, the screw 21 is driven by a drive system (not shown) and retracts. At this time, the resin supplied from the hopper (not shown) is heated in the heating cylinder 1 while moving forward in the groove 3 by the rotation of the screw 21. Then, they are melted and stored at the tip of the screw head 9. The pressure of the resin in the heating cylinder 1 generated by the melting serves as a reaction force against the screw 21, and the reaction force causes the screw 21 to retract.

Then, in the injection step, the resin stored at the tip of the screw head 9 is injected from the injection nozzle 4 by pushing the screw 21 forward (to the left in the drawing) by the drive system, and a mold not shown. Filled in the cavity. At this time, a part of the resin tries to flow backward (to the right in the drawing) through the groove 3 of the screw 21 due to a reaction force against the injection pressure applied when the resin is injected. Therefore, in order to prevent this, the check ring 6 is arranged in front of the screw 21. Then, in order to prevent the check ring 6 from coming off the screw 21, the screw main body portion 8 of the screw 21 and the screw head 9 are separately formed, and the screw portion 14 is screwed to fix them. There is.

The screw head 9 has a large diameter portion 9a and a small diameter portion 9b. By making the outer diameter of the large diameter portion 9a larger than the inner diameter of the check ring 6, the check ring 6 does not come off. It is like this. Further, the check ring 6 forms an annular resin flow channel 10 between itself and the small diameter portion 9b of the screw head 9, and opens the resin flow channel 10 in the measuring step in which the screw 21 retracts. 1
The resin is sent to the tip of the screw head 9 via 0. On the other hand, in the injection step in which the screw 21 advances, the check ring 6 abuts the seal ring 11 to close the resin flow path 10 and prevent the resin from flowing back. Reference numeral 12 is a locking portion for preventing the check ring 6 and the screw head 9 from rotating relative to each other.

By the way, the screw 21 has a hollow portion 31 formed by hollowing the inside over substantially the entire length.
A sleeve-shaped thin tube 32 is arranged over the entire length of the hollow portion 31, and the inside of the hollow portion 31 is decompressed and water or other fluid is enclosed as a heat medium. Further, the surface of the screw 21 is processed so that the heat medium can be conveyed by a capillary phenomenon. In this way, the screw 21 constitutes a thermopipe. The thermopipe has a high temperature portion H near the tip of the screw 21 and a low temperature portion L near the rear end.

The thin tube 32 is arranged concentrically with the screw 21, and has a gas passage 35 inside and a liquid passage 36 outside.
Is formed. A hole 39 for supplying gas to the gas passage 35 is formed in a portion corresponding to the high temperature portion H of the thin tube 32, and a gas is added to the liquid in the portion corresponding to the low temperature portion L of the thin tube 32. Hole 4 for supplying to passage 36
0 is formed. Further, a fin 41 as a heat radiation means is formed on the outer periphery of the low temperature portion L of the screw 21,
The low temperature part L is air-cooled.

In the injection apparatus having the above-mentioned structure, the heat medium enclosed in the hollow portion 31 is vaporized by absorbing heat in the high temperature portion H, becomes a gas, passes through the hole 39 and passes through the gas passage 35. It flows toward the low temperature part L. On the other hand, in the low temperature portion L, the gas flowing through the gas passage 35 enters the fluid passage 36 through the hole 40, and the low temperature portion L is air-cooled to remove heat and condense into liquid. . Then, the liquid flows through the fluid passage 36 toward the high temperature portion H by the capillary phenomenon.

In this way, the heat of the tip of the screw 21 can be absorbed in the high temperature portion H and can be dissipated in the low temperature portion L. Therefore, by repeating this cycle, the heat energy from the high temperature portion H to the low temperature portion L can be increased. Move
It is possible to prevent the screw 21 from being overheated. Further, since the thermopipe is built in the screw 21, it is not necessary to dispose a pipe or the like for conveying the heat medium between the heating cylinder 1 and the screw 21.
Therefore, the structure of the injection device can be simplified.

Next, a second embodiment of the present invention will be described. FIG. 5 is a sectional view of an essential part of an injection device according to the second embodiment of the present invention. In the figure, 1 is a heating cylinder of an injection molding machine, 21 is a screw that is rotatably and movably arranged in the heating cylinder 1, 51 is a water cooling jacket as a heat radiating means, 52 is a water chamber, and 53 is a seal. It's a ring.

In this case, the water cooling jacket 51 is arranged so as to surround the low temperature portion L of the screw 21 and is fixed to the main body of the injection device. Also, the water cooling jacket 5
1 has a water chamber 52, and water is supplied to the water chamber 52. Then, the amount of water supplied to the water chamber 52 is adjusted by a control device (not shown). It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made based on the spirit of the present invention, and they are not excluded from the scope of the present invention.

[0022]

As described above in detail, according to the present invention, the injection device includes the heating cylinder and the hollow portion which is rotatably and movably disposed in the heating cylinder and is sealed inside. And the formed screw. In the measuring process, when the screw is retracted while rotating,
The resin supplied into the heating cylinder is melted and stored in front of the screw. At this time, the resin receives a shearing force and generates heat.

Further, a high temperature portion is formed near the tip of the screw and a low temperature portion provided with a heat radiating means is formed near the rear end of the screw, and a heat medium is enclosed in the hollow portion. Therefore, the heat of the screw is absorbed by the heat medium in the high temperature portion and is radiated in the low temperature portion, so that the screw can be cooled without substantially changing the structure of the injection device.

[Brief description of drawings]

FIG. 1 is a sectional view of an injection device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part of an injection device in a conventional injection molding machine.

FIG. 3 is an enlarged view of the screw according to the first embodiment of the present invention.

4 is a cross-sectional view taken along the line AA of FIG.

FIG. 5 is a sectional view of an essential part of an injection device according to a second embodiment of the present invention.

[Explanation of symbols]

 1 Heating Cylinder 21 Screw 31 Hollow Part 41 Fin 51 Water Cooling Jacket H High Temperature Part L Low Temperature Part

Claims (1)

[Claims] 1. A heating cylinder; and (b) a screw which is rotatably and reciprocally disposed in the heating cylinder and has a sealed hollow portion formed therein. ) An injection device characterized in that a high temperature part is formed near the tip of the screw, a low temperature part provided with a heat radiating means is formed near the rear end, and (d) a heat medium is enclosed in the hollow part.