JPS6364296B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a multilayer annular die.

Generally, in a multilayer annular die, a large number of annular channels are fitted one after another in substantially the same position in the axial direction and concentrically in the radial direction, leading to a discharge port. When side-feeding resin to a multilayer annular die as described above, the resin can be easily supplied to the outermost layer by directly introducing it from the side, but it is difficult to feed the resin to the annular flow path of the inner layer from the second layer onward. However, if an attempt was made to feed directly from the side as used in the conventional side feed method, the communication path from the nozzle to the annular flow path would be blocked by the annular flow path in the outer layer, making spatial arrangement difficult. .

Furthermore, in such a multilayer annular die,
Unless the flow rate of the resin discharged through the annular channel is made uniform, the thickness of the resin film will not be uniform.
Furthermore, if the resin remains in the die, there is a risk of thermal deterioration. Therefore, in a multilayer annular die,
Uniformity of flow rate and transit time is desired. An example of a multilayer annular die that meets the above-mentioned demand for uniform thickness can be found in Japanese Utility Model Publication No. 51-21117.
The die is rotated as a means to equalize the flow rate of the resin. However, considering the die of this publication, for example, the receiving part of the annular groove formed in the rotating part communicates with the through passage in the fixed mold support, and furthermore, the symmetrical shape of the receiving part is Passages are provided at two locations and communicate with the mold chamber. Therefore, in the case of this die, the resin fed from the fixed through passage flows through the rotating receiving part to the two rotating passages, and at this time, the resin is transferred between the through passage and the two passages. At moments of rotation angle when the relative positions of the two are equidistant, resin flows evenly from the through passage to the receiving part, but at many other times, a larger amount flows toward the passage of the receiving part, which has a shorter distance. flows, and only a small amount flows to other receptors, causing stagnation. Therefore, this stagnation causes thermal deterioration of the resin, and also causes the flow of resin around the mold chamber to vary in size, and also causes periodic fluctuations in the flow rate of the resin over time. Furthermore, it requires a bearing means for rotatably supporting the die, a leak prevention means between the fixed part and the rotating part, a rotary power means, etc., which makes the structure complicated and expensive.

Therefore, the present invention aims to equalize the flow rate of resin in the annular flow path without rotating the die.

That is, in the present invention, a parting surface is provided in the direction transverse to the axis of the annular flow path at the rear of the annular flow path (hereinafter, the direction opposite to the traveling direction of the resin flow is referred to as the rear), and the parting surface is used to prevent the inner layer of resin from forming. The communication passage is divided at a radial position that does not obstruct the passage, and after the passage is divided, the divided passage is guided to the annular flow passage entrance parallel to the axis.
In this way, the communication passages corresponding to each layer can be easily arranged spatially so that their positions do not interfere with each other by shifting the radius and angular phase in the radial direction from each other at the rear of each annular flow path. Therefore, the multilayer die as a whole can be made smaller and lighter.

In addition, when dividing the communication passage, if the flow passages are formed so that the hydrodynamic shape for the flow is the same, the fluid can flow from the resin supply port to the entrance of the annular flow passage through any of the divided communication passages. The resistance can be kept constant regardless of the extrusion molding conditions, and the flow in the annular channel can be kept uniform around the circumference of the channel, which is preferable from the perspective of ensuring uniformity of extruded film thickness. .

Furthermore, the opposing surfaces constituting the parting surfaces that form the communication passages described above are fixed to each other, so that the shape of the communication passages is constant, there is no stagnation in the flow of the resin, and the extruded film thickness is reduced as described above. In addition to ensuring the uniformity of the resin, it can also prevent thermal deterioration of the resin.

That is, the outline of the present invention is such that the plasticized resin is supplied from a plurality of supply ports or is supplied from one supply port and then divided into a plurality of parts inside a die to substantially form a plurality of supply ports. None, in a die arranged such that the supply port passes through a plurality of communication passages, a plurality of annular channels, and then a discharge port, and this die has a plurality of channels in a direction transverse to the axis of the annular channel. A parting surface is formed, opposing surfaces forming these parting surfaces are fixed to each other, and the communication passage is used to divide the resin flow into a plurality of parts and then supply the resin flow to the entrance of the annular flow passage. The portions that divide the resin flow are in contact with each of the parting surfaces and communicate with each other, and the portions that divide the resin flow are divided into dividing channels that are divided into multiples of 2 from the starting point. The end points are arranged symmetrically with respect to the axis, and the flow paths divided in this way do not mutually connect to each other at any point that has the same travel distance from the starting point to the end point of the resin division. This is a multilayer annular die characterized by having the same cross-sectional shape and the same length.

Next, embodiments of the present invention will be described with reference to the drawings.

In Fig. 1, 1 and 2 are first and second resin supply ports;
3 is a feed block into which the supply ports for these resins are screwed. Connecting passages 4, 5 are bored in the feedblock 3, and the connecting passages 4, 5 form internal feedblock portions 41, 51 of the connecting passages within the block and their orientation is Change direction from radial to parallel to the die axis.

A spacer 6 is fixed adjacent to the feedblock 3, and the parting surface 7 where the spacer and the feedblock contact each other has a dividing groove 10 for dividing each communication passage 4, 5 as shown in FIG.
and 11 are provided. 8 and 9 are the starting points of the dividing groove,
12 and 13 are the end points of the dividing grooves. The cross-sectional shape of the dividing groove can be any shape, such as a semicircle, a rectangle added to the end of a semicircle, or an elongated circle divided in half by the short axis, but the shape is as close to a circle as possible with no resin retention area. It is preferable that In addition, in the example shown in Fig. 1, the dividing groove is provided only on the spacer side, but it can be placed on the feedblock side opposite to the parting surface 7, or at the same relative position with respect to the parting surface. There is no problem even if it is provided on both sides.

FIG. 4 shows another embodiment of the invention. In the embodiment shown in FIG. 3, the resin dividing groove has a circular arc shape, but this does not necessarily have to be a circular arc shape. In the embodiment shown in FIG. 4, the dividing groove is composed of a straight line or a broken line in which several straight lines are connected from the starting point to the ending point. Further, in this example, the cross-sectional shape is large near the starting point and small near the ending point. The cross-sectional shape of the two divided grooves is such that the large portions are large and the small portions are small in accordance with the travel distance from the dividing starting points 8 and 9, and the total length of each portion corresponding to each cross-sectional shape is Equally done.

In any case, the dividing groove should be in contact with the parting surface, and the multiple flow paths divided from one starting point will have a mutual cross section at any part that has the same travel distance from the starting point to the ending point of the resin dividing. Since the shapes are the same and the lengths are the same, the fluid resistance of the resin flowing therein is the same for all communication passages divided in the section from the starting point to the ending point. , it does not change even if the type of resin flowing through it or the temperature conditions are changed. Moreover, even if a change in extrusion speed, that is, a change in shear rate, occurs as a dynamic change factor, no discrepancy occurs. The method of configuring the flow passages as described above means that divided flow passages that are hydrodynamically the same are provided.

A base 15 of a mandrel 14 is fixedly provided on the resin outlet side end surface of the spacer 6 and in contact with it, and a parting surface 16 of the base that is in contact with the spacer 6 has dividing grooves 17 and 18 as shown in FIG.
is provided. 19 and 20 are the starting points of the dividing groove, 2
1 and 22 are the end points of the dividing grooves. The terminal points 12 and 13 are communicated with the starting points 19 and 20. In this case as well, please refer to A-A for details on how to provide the dividing grooves, such as the cross-sectional shape of the dividing grooves and how to arrange them.
Performs the same hydrodynamic division as in the cross section.

In the above embodiment, one parting surface has one
The two communicating passages 4 and 5 are divided into two, and if they pass through the parting surface n times, it is possible to create divided flow passages within ²ⁿ . If we pay attention to the flow paths at each divided end, all the flow paths are designed to have the same flow resistance from a hydrodynamic perspective.

The division on the same parting surface is not limited to two divisions, and divisions may be repeated starting at the end point of the two-divided groove to create divided flow paths in multiples of two.

From the end points 21, 22 of the dividing groove provided on the end face of the base 15 of the mandrel 14, mandrel base inner portions 43, 53 of communication passages are provided so as to penetrate the base in the die axis direction.

The connecting holes pass through the base and then form the starting points 4 of the spiral grooves 44, 54 starting from the hem of the mandrel.
5,55. Starting point 45 of the spiral groove,
55 are usually provided at equal intervals on the circumference of the mandrel so as to ensure a uniform flow rate over the entire circumference of the subsequent annular flow path. 23 is a spiral ring fitted on the outside of the mandrel 14, and the base 24 of the ring is provided with a communication passage 53 that passes through the base of the mandrel and a communication passage 56 that reaches the starting point of the spiral groove after passing through. There is.

A die ring 25 is provided further outside the spiral ring 23. Between the mandrel 14 and the spiral ring 23 and the spiral ring 2
An annular flow path 47, 5 is provided between the die ring 25 and the die ring 25.
7 is provided. The annular channels 47 and 57 have a narrow gap at the inlet and widen toward the outlet, and the spiral grooves 44 and 54 have a starting point 4 corresponding to the inlet.
5 and 55 have a large cross-sectional area, and the cross-sectional area becomes smaller toward the outlet. Therefore, near the inlets of the annular channels 47, 57, most of the resin flow flows within the spiral grooves, but a portion of the resin flows as a leakage flow within the annular channels 47, 57, and reaches the exit where the spiral grooves end. In the vicinity, there is only a leakage flow, that is, a flow flowing down in the annular flow passages 47 and 57 in the axial direction.

Reference numeral 26 is a confluence point where the two flows merge after the two annular flow paths 47 and 57 are completed, and the two resins merge at this point and then flow through the common annular flow path 27.
The liquid flows down as a merged stream and is discharged from the discharge hole 28.

Although two supply ports are used in the above embodiment, the number of supply ports may be three or more. In that case, the number of connecting channels and annular channels must be equal to or greater than the number of supplies.

Further, even if there is only one supply port, FIG. 5 shows an embodiment in which the supply port is divided into a plurality of parts inside the die after supply to substantially form a plurality of supply ports.

In FIG. 5, 1 is a resin supply port, and 3 is a feed block into which the resin supply port is screwed. A communication passageway 4 is bored in the feedblock 3,
The communication passage is branched into two within the block.
Book communication paths 41 and 51 are created. The passage changes its orientation from radial to parallel to the die axis. There is a spacer 6 adjacent to the feedblock 3, and on the surface 7 where the spacer and the feedblock contact, there is a dividing groove 10 for dividing each communication passage 41, 51 as shown in FIG.
and 11 are provided. The dividing grooves are provided in the same manner as in the embodiment shown in FIG. Further, the structure of the portion after the spacer is exactly the same as that of the embodiment shown in FIG.

As described above, according to the present invention, even if a large number of annular channels are fitted concentrically, resin can be easily supplied to the inner annular channel. Also, since the number of resin supply ports to the annular flow path can be increased, multiple layers of supply ports can be provided at equal intervals around the circumference of the annular flow path, and the flow rate of resin can be made uniform around the circumference. be able to. Furthermore, since the resin does not stagnate, the resin does not deteriorate. Furthermore, since there is no need to rotate the die, there is an advantage that the structure is simple and inexpensive.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of the present invention, FIG. 2 is a sectional view taken along line AA in FIG. 1, and FIG. 3 is a sectional view taken along line BB in FIG.
FIG. 4 is a longitudinal sectional view showing another embodiment of the communication passage division, and FIG. 5 is a longitudinal sectional view showing another embodiment near the supply port. In these figures, 1 and 2 are supply ports, 4 and 5 are communication passages, 47 and 57 are annular flow passages, 28 is a discharge port,
7, 16 are parting surfaces, 10, 11, 17,
18 is a dividing groove, 8, 9, 19, 20 are starting points, 1
2, 13, 21, 22 are end points, 44, 54 are spiral grooves, and 45, 55 are starting points of the spiral grooves.

Claims (1)

[Claims] 1. Plasticized resin is supplied from a plurality of supply ports, or after being supplied from one supply port, is divided into a plurality of parts inside the die to substantially form a plurality of supply ports. None, in a die arranged such that the supply port passes through a plurality of communication passages, a plurality of annular channels, and then a discharge port, and this die has a plurality of channels in a direction transverse to the axis of the annular channel. A parting surface is formed, opposing surfaces forming the parting surface are fixed to each other, and the communication passage is configured such that the resin flow is further divided into a plurality of parts and then supplied to the entrance of the annular flow passage. The part that divides the resin flow is in contact with each of the parting surfaces and communicates with each other, and the part that divides the resin flow has dividing channels divided into multiples of 2 from the starting point. The end points are arranged symmetrically with respect to the axis, and the flow paths divided in this way are mutually connected to each other at any part that has the same travel distance from the starting point to the end point of the resin division. A multilayer annular die characterized by having the same cross-sectional shape and equal length. 2 The annular flow path has a spiral groove on its inner wall surface, and the spiral groove is a multi-filament spiral, and the starting points of the spiral grooves are provided at equal intervals on the circumference of the inner wall mandrel, and the annular flow path has a gap at its entrance. A multilayer annular die according to claim 1, wherein the gap is narrow and widens toward the exit.