JPH0646655Y2 - Plasticizer of injection molding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a plasticizing device of an injection molding machine capable of preventing the material resin from being melted and fixed on the shaft surface of the supply portion of the injection screw. It is a thing.

[Conventional technology]

Conventionally, in the screw in-line type injection molding machine, the shaft of the injection screw is formed in the small diameter part in the supply part and the large diameter part in the measuring part, and in the plasticizing part it is formed in the taper part connecting the small diameter part and the large diameter part in series. Then, the injection screw was fitted in the plasticizing cylinder, and a casting cooling cylinder having a hole for cooling water was provided in the material supply portion of the plasticizing cylinder, and the casting screw was fitted in the plasticizing cylinder. The base end of the injection screw is slidably supported. Then, while supplying the material between the plasticizing cylinder and the injection screw while cooling the base end portion of the plasticizing cylinder with the cooling water through the cooling cylinder, the screw surface (shaft and flight) is rotated and rotated by the injection screw. The material in the groove is compressed by the plasticizing part of the injection screw and is sent forward while being plasticized, and is metered and stored in the material storage chamber in the tip of the plasticizing cylinder. The injection of the molten material in the material storage chamber is performed by the advance of the.

[Problems to be solved by the device]

By the way, in the injection screw having the above-described shape, the relationship between the frictional force comparison value between the screw material (metal) and the material (polyamide, polybutylene terephthalate, etc.) that is likely to cause defective engagement and the material temperature is shown in FIG. As shown, the frictional force is extremely large at or near the melting point of the material temperature, but at a certain temperature or less, the frictional force is sufficiently small that the material slips easily on the screw surface (shaft and flight surface), causing poor bite. It turns out that does not occur. Further, the ideal temperature distributions of the cylinder contact material and the screw contact material in the injection screw supply section are as shown in FIG. 2, and in the vicinity of the plasticized section of the injection screw supply section, both exceed the softening point, It can be seen that it is close to the melting point.

Therefore, when handling a material that is likely to cause biting failure, there is an injection screw supply unit inside the plasticizing cylinder set to a high temperature, as in the injection molding machine, which is separated from the cooling jacket, and the injection screw is Insufficient cooling of the shaft surface of the supply part of the injection screw causes the temperature of the material that comes into contact with the injection screw supply part, especially the shaft surface, to rise when molding is interrupted due to defective discharge of the molded product from the mold, etc. And the increase in frictional force makes it difficult for the material to slip on the screw surface. With this mechanism, the temperature of the material reaches the melting point and melts, and once the material has adhered to the shaft surface of the injection screw, another material adheres to the adhered material and a bridge phenomenon occurs in the groove of the injection screw. The material does not move forward due to the axial shape of the injection screw,
There is a problem that it takes time to restart the driving of the plasticizer.

On the other hand, as seen in Japanese Utility Model Laid-Open No. 61-130411, it is known to provide a heat pipe inside the injection screw that reaches the portion where the tip plasticizes the material, but does not cool the molten material. For that purpose, the temperature of the rear end of the heat pipe is adjusted by the temperature adjusting device provided at the base end of the injection screw to adjust the temperature of the front end of the pipe,
The temperature of the plasticizing portion of the injection screw where the tip of the heat pipe is located is adjusted, and the material cooling in the supply portion of the injection screw is not intended. Also, in order to prevent the heat of the heat pipe from being transmitted to the supply part of the injection screw, the diameter of the middle part of the pipe insertion hole is enlarged so as to form an annular space around the middle part of the heat pipe. In addition to the reduced rigidity of the screw, a heat pipe with a small outer diameter has a drawback that the diameter of the pipe insertion hole is also small, and it is very difficult to make the diameter large only in the middle of the hole.

Further, as seen in Japanese Utility Model Laid-Open No. 62-189119, an extruding screw is fitted in a heating cylinder, a cooling liquid supply pipe is inserted in a rear end portion of the screw, and a tip of the supply pipe is inserted into the extruding screw. It is known to discharge the supplied cooling liquid to the outside through a cooling liquid discharge pipe provided at the rear end of the extrusion screw, and circulate and supply the cooling liquid into the rear end of the extrusion screw. In the vicinity where is supplied on the extrusion screw, only the surface of the material that fills the groove of the extrusion screw is melted by the heat given from the heating cylinder, and the bridge phenomenon occurs where the entire surface is not melted and the groove of the extrusion screw is filled. The purpose of this is to cool the material from the base end side of the extrusion screw, and there is no idea to prevent the resin from sticking to the screw trough near the plasticizing part of the supply part of the injection screw of a certain shape. Shown No.

[Object of the Invention]

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to reliably prevent a resin sticking phenomenon that occurs in the vicinity of a plasticizing portion of a supply portion of an injection screw of a certain shape, and to improve the use of a plasticizing device. And

[Means for Solving the Problems]

The plasticizing device of the injection molding machine according to the present invention forms the shaft of the injection screw into a small diameter part in the supply part and a large diameter part in the measuring part,
The injection screw is fitted into a plasticizing cylinder, the screw base end portion is connected to a rotary drive device that reciprocates in the screw axial direction, and a heat pipe is provided inside the supply portion and the base end portion of the injection screw. At the same time, an exposed portion of the heat pipe exposed to the cooling water is provided at the base end portion of the injection screw inserted into the circulating cooling water of the box provided between the plasticizing cylinder and the rotary drive device. The above object is achieved by such a configuration.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 3 and 4.

In the figure, reference numeral 1 denotes a plasticizing cylinder, and a material inlet facing a material receiving portion at a front portion of a base end portion of an injection screw, which will be described later, is provided at an upper portion of a base end portion of the cylinder 1, and a tip of the plasticizing cylinder 1 is provided. An injection nozzle 2 is attached to the section.

Reference numeral 3 denotes an injection screw, and a shaft 4 of the screw 3 has a material receiving portion H at a front portion of a screw base end portion and a supply portion A continuous with the material receiving portion H.
Is formed in the small diameter portion, the measuring portion C is formed in the large diameter portion, and the plasticizing portion B is formed in the tapered portion connecting the small diameter portion and the large diameter portion in series. A spiral flight 5 is continuously provided around the axes of the material receiving portion H, the supply portion A, the measuring portion C, and the plasticizing portion B.

The injection screw 3 is fitted in the plasticizing cylinder 1 to define a material storage chamber 6 in the rear end of the injection nozzle 2 and is supported at the base end of the screw so as to be movable back and forth with respect to the storage chamber 6. ing.

At the rear of the base end of the injection screw 3, the plasticizing cylinder 1
Is connected to the rotary drive device 7 arranged at the rear of the
The injection cylinders 8 provided on both sides of the base end of the plasticizing cylinder 1 are connected to the frame.

The injection screw 3 can be rotated by a rotary drive device 7 and can be moved forward and backward with respect to the material storage chamber 6 in the rear end of the injection nozzle 2 by an injection cylinder 8 via the device 7.

Reference numeral 9 denotes a heat pipe, which is provided at the base end of the injection screw 3 and the center of the inside of the shaft 4 in the supply unit A so that the tip reaches near the plasticizing unit B.

A box 11 for circulating circulating cooling water is provided between the plasticizing cylinder 1 and the rotation driving device 7, and a rear portion of the base end portion of the injection screw 3 is passed through the cooling water and a hole 10 is bored there to form a heat pipe in the center of the inside. Expose 9 in cooling water.

[Action]

The material is fed via the material inlet onto the proximal end of the injection screw 3 in the plasticizing cylinder 1 and enters into each groove of the shaft 4 and the flight 5 of the screw 3.

At the time of injection molding, first, the injection screw 3 is rotated by the rotation driving device 7.
When is rotated, the material is sent to the plasticizing section B side while sliding on the surfaces of the shaft 4 and the flight 5 of the injection screw 3 and is compressed and plasticized in the plasticizing section B, and the molten material is measured by the measuring section C. In the material storage room 6
It accumulates inside. When the material is filled in the material storage chamber 6 by the rotation of the injection screw 3 by the rotary drive device 7 and the material pressure becomes high, it is detected by a pressure sensor (not shown), and the rotary drive device 7 is stopped by this detection signal, and the injection is performed. The cylinder 8 is activated.

The injection cylinder 3 advances the injection screw 3,
When the advance amount (injection amount) of the injection screw 3 reaches a predetermined value under the control of a device (not shown), the advance of the screw 3 is stopped. As a result, a predetermined amount of material is injected and filled from the inside of the material storage chamber 6 through the nozzle holes into the mold that has been clamped, and the pressure is maintained.

When the injection is completed, the mold side is cooled and released, and after the injection screw 3 is returned to the original position by the injection cylinder 8, the rotation of the injection screw 3 is started and the material storage chamber in the injection nozzle 2 is started. The material is supplied to 6, the injection screw 3 is measured and retracted by the material pressure, and the above-mentioned work is repeated.

In the above molding cycle, the hose is placed inside the box 11.
The cooling water is circulated and supplied via 13 and 14, and the cooling water comes into contact with the base end portion of the heat pipe 9 through the hole 10 provided in the injection screw 3 to cool it. The supply part A of the injection screw 3 is cooled by the pipe 9 so as to be below the melting point of the material. Therefore, even when the molding is interrupted due to defective ejection of the molded product from the mold, the temperature of the material in contact with the screw does not rise to the melting point at the injection screw supply portion, and the injection screw 3 and Since the frictional force with the material is kept sufficiently small, the material is sent from the supply section A of the screw 3 to the plasticizing section B side while sliding on the surfaces of the shaft 4 and the flight 5 of the injection screw 3. Become.

[Effect of device]

As described above, according to the present invention, the supply part of the injection screw can be cooled by using the heat pipe so that the material temperature becomes equal to or lower than the melting point. Even if the treatment is delayed, restarting can be performed smoothly, and materials that are likely to cause biting defects can be handled. Also,
Since the temperature setting range of the plasticizing cylinder is increased, it is easy to use a mixed material (alloy resin) of materials having different melting points.

In addition, the material flow from the injection section to the plasticizing section to the metering section of the injection screw is stable, so the metering time is stable, the kneading state is stable, and the molding quality can be improved. Even if a powdery material is mixed, no problem will occur, and black spots generated by long-term adhesion and retention in the transparent molded product will be reduced, so that the defective rate can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the frictional force comparison value between screw material (metal) and material and the material temperature, and FIG. 2 is the ideal temperature of the cylinder contact material and screw contact material in the injection screw supply part. FIG. 3 is a plane sectional view showing an embodiment of the present invention, and FIG. 4 is a sectional view taken along the line AA in FIG. 1 ... Plasticizing cylinder, 3 ... Injection screw 4 ... Shaft, 5 ... Flight, H ... Material receiving part, A ...
... Supply unit, B ... Plasticizing unit, C ... Measuring unit, 6 ... Material storage chamber, 7 ... Rotation drive device, 8 ... Injection cylinder, 9
...... Heat pipe, 10 …… hole, 11 …… box, 12 ……
Seal ring, 13, 14 ... Hose.

Claims (1)

[Scope of utility model registration request] 1. A shaft of an injection screw is formed in a small diameter part in a supply part and a large diameter part in a metering part, and in a plasticizing part it is formed in a taper part connecting the small diameter part and the large diameter part in series. Is inserted into a plasticizing cylinder, the base end of the screw is connected to a rotary driving device that reciprocates in the screw axial direction, and a heat pipe is provided inside the supply part and the base end of the injection screw. Plasticizer for an injection molding machine, characterized in that an exposed portion of a heat pipe exposed to cooling water is provided at a base end portion of an injection screw that is inserted into circulating cooling water of a box provided between the plasticizing cylinder and a rotary drive device. .