JPH0439022A - Series two-stage extruding machine - Google Patents

Abstract

PURPOSE:To contrive an improvement in extruding capacity, by a method wherein an outlet discharging raw materials to the second stage extruding machine from a middle of a tip side of a screw of the first stage extruding machine is provided and the screw of the first stage extruding machine of an outlet part is made into a multiple-flight form of at least two flights. CONSTITUTION:Raw materials plasticized and molten by the first stage extruding machine pass through an outlet 16 and sent to the second stage extruding machine through a joint pipe 7. In this instance, the raw materials at the outlet 16 are cut off by multiple flights 21 which are at least two flights of the tip parts 1a of a screw 1 by a rotation of the screw 1. Then since an extruding speed within a pipe is very slow as compared with that of the multiple flights 21 turning at a high speed, the raw materials are sent under a state where thin layers are accumulated. Therefore, a boundary surface is renewed always, mixing is accelerated, a degree of plasticization of resin or dispersion in temperatures is unified and the homogeneous raw materials are obtained. Then since shearing energy also applied to the resin at the time of cutting is effective in homogenizing of melting, an extruding capacity can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an in-line two-stage extruder applicable to an extruder for plasticizing and melting plastics, an extruder for rubber, and the like.

(Prior Art) Conventionally, as an extruder for plasticizing and melting plastic, a two-stage series extruder as shown in FIG. 8 has been proposed. This extruder has recently come into widespread use, especially when producing biaxially stretched films of polypropylene, polystyrene, and the like.

Usually, the screw 1' and cylinder 2' of the first stage extruder have a small diameter and high speed to have plasticizing and melting functions, and the screw 8 and cylinder 9 of the second stage extruder have a large diameter and low speed. The receiver has cooling, homogenizing, and pumping functions.

In addition, in the first stage extruder, 3 is a deceleration drive device, 4 is a drive electric motor, 5 is a heating heater, and 6 is a hopper, and in the second stage extruder, 10 is a deceleration drive device, 11 is a drive electric motor, and 12 is a heating device. 13 is a cylinder cooling unit,
14 is a die, and 15 is an extruded product. By sharing the functions between two extruders in this way, it becomes possible to extrude a large volume of products with good quality using a small extruder.

(Problems to be Solved by the Invention) In the conventional two-stage series extruder, the resin passes through the tip of the screw 1' of the first stage extruder, and then passes through the connecting pipe 7.
' and sent to the second stage extruder. However, when the screw rotation speed of the first-stage extruder is further increased in order to increase the extrusion amount beyond the conventional capacity, the temperature of the resin at the tip of the first-stage extruder increases, and unmelted substances are mixed in. This results in an extremely heterogeneous state. Therefore, in order to homogenize the second stage extruder, it was necessary to change the specifications such as increasing the diameter or lengthening the L/D.

In this way, in the series two-stage extruder shown in Fig. 8, when the screw rotation speed of the first-stage extruder is further increased in order to increase the extrusion amount beyond the conventional capacity, the raw material at the tip of the first-stage extruder is The temperature variation becomes large and unmelted substances are mixed in, resulting in an extremely non-uniform state. For this reason, it has been extremely difficult to increase the extrusion capacity beyond the conventional structure with the conventional structure.

In addition, a filter for filtering out foreign matter may be installed in the connecting pipe 7', but in this case, the raw material must be completely melted, and if unmelted matter gets mixed into the melt, the filter This causes blockage and pressure fluctuations at the tip of the first stage extruder.

The present invention aims to improve the extrusion capacity by homogenizing the raw material exiting the first stage extruder as much as possible.

(Means for Solving the Problems) For this reason, the present invention provides a two-stage extruder in which a first-stage extruder and a second-stage extruder are connected in series. In addition to providing an outlet leading to the second stage extruder that discharges the raw material to the side from a position midway through the screw, the screw of the first stage extruder at the part located at the same exit is
It is a multi-flight shape with more than one strip, or a similar shape, and is used as a means to solve the problem.

(Function) As the screw rotates, the raw material is transported to the first place by flight.
It is cut at the exit of the stage extruder and advances while being made into a thin layer. Therefore, as the screw rotates, the raw materials in different grooves are successively thinned and stacked, so that the boundary surfaces are constantly updated and mixing is promoted efficiently. As a result, variations in the degree of plasticization of the resin and variations in temperature are made uniform, and a homogeneous raw material can be obtained. Furthermore, the shearing energy given to the resin during cutting is also effective in homogenizing the melt.

(Embodiment) The present invention will be described below with reference to the embodiments of the drawings. Figs. 1 to 7 show embodiments of the present invention, 3 is a deceleration drive device,
4 is a drive motor, 5 is a heating heater, 6 is a hopper, 8 is a second stage extruder screw, 9 is a cylinder, 10 is a reduction drive device, 11 is a drive motor, 12 is a heating heater, 13 is a cylinder cooling unit , 14 is a die, and 15 is an extruded product, which are the same as the conventional one shown in FIG.

Here, the differences from FIG. 8 will be explained. Reference numeral 1 denotes a first stage extruder screw, and the tip end 1a is configured in a multi-flight shape with two or more threads.

2 is a screw cylinder of the first stage extruder, and the screw l
It has an outlet 16 for discharging the raw material from a midway position of the tip 1a to the connecting pipe 7 leading to the second stage extruder.

Next, to explain the operation, the raw material plasticized and melted in the first stage extruder passes through the outlet 16 in FIG. 1 and is sent to the second stage extruder via the connecting pipe 7.

When the raw material is pushed out from the cylinder 2 to the outlet 16, the raw material at the outlet 16 is cut by two or more flights at the tip 1a of the screw 1 as the screw 1 rotates. In the case of FIG. 2, the raw material is cut twice in one rotation of the screw, and in the case of FIG. 4 (radial flights 21a are formed at the tip 21), the raw material is cut four times.

In addition, since the extrusion speed of the raw material in the tube at the outlet 16 is very slow compared to the speed of the multi-filament flight rotating at high speed, the raw material is transferred into a thin layer 2 as shown at the outlet 16 in FIGS. 2 and 4.
2.23 will be sent overlapping. The raw material is cut,
The state of thinning is better understood in FIGS. 3 and 5.

Although the embodiments shown in FIGS. 2 to 5 have a structure in which the raw material is cut with ordinary screw flights, the shape of the flights may be any shape, as long as the material can be cut. For example, the tip 1a in FIG. 3 is replaced with the tip 24 in FIG. 7, and the tip 21 in FIG. 5 is replaced with the tip 25 in FIG.
It may be modified as follows. Furthermore, in the above embodiments, a melt pump such as a gear pump may be used instead of the second stage extruder.

(Effects of the Invention) Since the present invention is configured as explained in detail above,
As the screw rotates, the raw material is cut by flights at the exit of the first-stage extruder and advances while being made into a thin layer.

Further, when the screw has a shape similar to a multi-flight shape, the raw material in the groove between the two flights is stacked until it is cut in one flight and cut in the next flight. Therefore, as the screw rotates, the raw materials in different grooves are successively thinned and stacked, so that the boundary surfaces are constantly updated and mixing is promoted efficiently. This equalizes variations in the degree of plasticization and temperature variations in the resin,
A homogeneous raw material is obtained. Furthermore, the shearing energy given to the resin during cutting is also effective in homogenizing the melt. From the above, the extrusion capacity of the two-stage in-line extruder can be significantly improved compared to conventional extruders.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view of a two-stage in-line extruder according to the first embodiment of the present invention, Fig. 2 is an enlarged sectional view of section A in Fig. 1, and Fig. 3 is a sectional view taken along line B-B in Fig. 2. 4 is an enlarged sectional view corresponding to FIG. 2 of the second embodiment of the present invention, FIG. 5 is a sectional view from C to C of FIG. 4, and FIG. 6 is a sectional view of the third embodiment. For example, Fig. 7 is a cross-sectional view of a screw with a structure different from Fig. 1, Fig. 7 is a sectional view of a screw of the fourth embodiment and a structure different from Fig. 1, and Fig. 8 is a conventional in-line two-stage extrusion. It is a side sectional view showing the machine. Explanation of main parts of the figure 1 - 1st stage extruder screw 1a... - Screw tip 2 - 1st stage extruder cylinder 8 - 2nd stage extruder screw 16 - Exit Figure 3 1A5r:! U Figure 2 JP) Figure 4

Claims (1)

[Claims] In a series two-stage extruder in which a first-stage extruder and a second-stage extruder are connected in series, a second stage extruder that discharges raw materials from a midway position of the screw to the side of the screw tip of the first-stage extruder Two stages in series, characterized by having an outlet leading to the stage extruder, and having the screw of the first stage extruder located at the exit in a multi-flight shape with two or more threads, or a shape similar to this. Extruder.