JPS5829209B2 - annular die - Google Patents

Description

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

Conventionally, in an annular die in which an outer die ring is fitted to an inner die ring, on the upstream side where the resin flows, they are tightly fitted except in the channel groove, and on the downstream side It has come to be widely used that an annular resin flow path is formed between the inner and outer circumferential rings, and the resin is fed under pressure from the bird or screw from the die axis direction.

Of course, there are many models in which the resin pumped by the screw is supplied from the side to the die shaft, and then flows into the inlet of the annular resin flow passage formed between the inner and outer die rings. used.

In this case, the inner die ring is provided with a manifold in the upstream part of the annular resin flow path described above for the purpose of uniformly supplying the resin three times in the circumferential direction of the inner and outer die rings. While the resin supplied from the manifold flows in the circumferential direction through the manifold, a part of the resin flow leaks through the gap between the inner and outer die rings, and together with the circumferential flow flowing inside the distribution manifold, the resin flows in the annular shape. What is done is to create an axial flow with a uniform flow distribution flowing through the flow path.

In the conventional method, when resin is supplied from the side to the die shaft, there is only one inlet into the annular resin flow passage, so the resin is supplied from the die outlet provided at the tip of the flow passage. The resin flow rate per unit width is determined from the position downstream of the inlet and from the position relative to the axis on the die ring circumference.
Achieving exactly the same 0° phase difference was only possible when flowing a fluid with a specific viscosity index through a die of a specific design.

Therefore, if a specific resin is used and extruded at a specific temperature, if the viscosity index of the resin under the conditions is known in advance and the die is designed and placed, the per unit width in the circumferential direction at the die outlet will be Although the resin flow rate can be made uniform, if the type or grade of resin is changed or the temperature conditions are changed, there will be a 180° phase difference between the downstream position corresponding to the inlet and the circumference of the die ring. The flow rate per unit width differs depending on the position, resulting in a tube with uneven thickness in the circumferential direction.

The present invention has been made to correct the above-mentioned drawbacks.

That is, the number of resin inflow ports into the annular resin flow path is two or more.

Furthermore, it is an object of the present invention to provide such an annular die that is not only easy to process but also reliably easy to clean.

In general, when installing cooling air or cooling water introduction and outlet channels, core material passages for coating, axially movable mandrels, etc. near the die axis, these additions are necessary near the die axis. Since the space is occupied by objects, it becomes necessary to supply resin from the side of the die to the die axis.The present invention is particularly useful in such cases, and it is possible to supply resin to the die ring inside the die axis. An annular die is fitted with an outer die ring, and an annular resin flow path is formed between the inner and outer die rings, and the depth of the resin flow path increases as it goes downstream toward the outer surface of the die ring, which is the inner side of the flow path. The so-called spiral mandrel die, in which a spiral manifold with a gradually decreasing diameter is installed, and the gap between the inner and outer die rings gradually becomes larger as it goes downstream, and finally consists of only an annular resin flow path, is shown in Figure 1. As shown in Figure 2, a resin supply opening and a channel groove connected thereto are provided along the die axis, and a plurality of channel grooves are provided radially from the end of the channel, with the outlet located upstream of the annular resin channel. It is known to have a helical manifold inlet.

In the present invention, resin is supplied from the side of the die to the die axis, but the number of resin inflow ports to the annular resin flow path is plural, and the flow path groove leading to the inflow port is connected to the die ring. Since it is distributed at equal intervals around the die ring circumference, even if you select a resin or operating conditions that differ from the planned viscosity index, the flow rate will remain within the pitch divided into equal intervals around the die ring circumference. It is possible to limit the change to .

Therefore, even if a deflection occurs in the extruded tube, the change in wall thickness can be limited to within the pitch that is subdivided according to the number of resin flow grooves, and the maximum wall thickness and minimum wall thickness The deviation can be kept much smaller than when there is only one resin supply port.

Furthermore, the shape of the flow groove from the resin supply port to the i-shaped resin flow path is the same no matter which flow path is taken after branching, even if there is a difference in direction. The flow resistance is constant regardless of the viscosity index of the resin flowing in the groove, and therefore the flow rate in the flow groove from the flow groove to the inlet of the annular resin flow path can be kept equal for each flow path. can.

Next, let's explain in more detail with the help of drawings.

FIG. 1 shows an annular die having a resin supply port and a flow channel groove along the die axis using a conventional method.

In the figure, reference numeral 1 denotes a supply port through which resin is supplied under pressure by a screw of a screw extruder (not shown).

2 is the inner die ring.

A male thread is provided at the tip of the supply port 1, and is screwed into a male thread provided at the center of the rear end flange portion 3 of the inner die ring 2.

The resin supplied from the supply port 1 flows into a channel groove 4 provided in the die axis direction, reaches a branching point 5, and flows into a plurality of channel grooves 6 branching from the point and oriented in the radial direction. and inflow.

Reference numeral 7 denotes an inlet port that flows into an annular resin flow path 8, which will be described later.

The channel grooves 6 facing in the radial direction are distributed at equal angles in the radial direction when viewed from the die axis, and therefore the positions of the inflow lowers are distributed at equal intervals on the circumferential surface of the inner die ring 2. There is.

9 is a spiral manifold.

The resin passes through the channel groove, reaches the inflow lower, and flows into the spiral manifold 9.

An outer die ring 10 is fitted on the outside of the inner die ring 2, and is fastened to the flange portion 3 of the inner die ring with bolts (not shown).

An annular resin flow passage 8 is provided between the inner die ring and the outer die ring, and the gap formed by the flow passage is narrow on the upstream side where the resin flows, and gradually widens on the downstream side. There is.

The twisted spiral manifold 9 is deep on the upstream side where the resin flows, and gradually becomes shallower on the downstream side.

Reference numeral 11 indicates a portion where the manifold has completely disappeared and consists only of an annular resin flow path, and reference numeral 12 indicates a die discharge port formed from an annular slit.

The resin that has entered the inflow lower via the flow channel is transferred to the manifold 9.
The leakage flow is distributed in the circumferential direction of the die ring, but at the same time, the proportion of the leakage flow flowing in the die axial direction through the annular resin flow passage 8 consisting of the gaps between the inner and outer die rings gradually increases until finally. becomes an axial flow with a uniform flow rate in the circumferential direction.

FIG. 2 shows an embodiment of the invention.

In the figure, reference numeral 21 denotes a supply port through which resin is fed under pressure by a screw of a screw extruder (not shown).

22 is an inner die ring. A male thread is provided at the tip of the supply port 21, and is screwed into a female thread provided on the side of the outer die ring 23.

The resin supplied from the supply port 1 flows from the side of the die into the channel groove 24 provided in the die axis direction, passes through the fitted boundary surfaces of both the inner and outer die rings, and is applied to the outer surface of the inner die ring. A first branch channel enters the channel groove 25 carved in the die axis in the axial direction, reaches a first branch point 26, and is arranged symmetrically with respect to the die axis direction when viewed from the branch point. Groove 2
7.

The first branch channel grooves of each of the two branches form a 90° angle with the die axis when viewed from the branch point along the circumferential surface of the inner die ring, and the angle between each branch channel groove is 90°. They reach a position where the angles are 180° to each other and connect to the flow channel groove 28 parallel to the die axis.

The channel groove 28 parallel to the die axis has a second branch point 29 downstream thereof.
Then, it flows into the second branch channel groove 30, which is arranged symmetrically with respect to the die axis direction when viewed from the branch point.

Each of the second branch channel grooves, which are further branched into two, runs along the circumferential surface of the inner die ring at an angle of 45° with the die axis when viewed from the branch point. It reaches a position where the angles formed by the channel grooves are 90' to each other, and are connected to the channel grooves 31 parallel to the die axis.

In this way, the adjacent flow grooves on the inner manodrel circumferential surface have an angle of 90' with respect to the axis and are distributed at equal intervals on the circumferential surface, and then the annular resin flow passage 33 is formed. It is connected to a spiral manifold 34 through an inlet 32 provided at the most upstream position.

The resin reaches the inlet 32 through the channel groove, and then enters the manifold 3.
4.

An outer die ring 23 is placed on the outside of the inner die ring 22.
is fitted and fastened to the flange portion 35 of the inner die ring with bolts (not shown).

In the downstream region after the annular resin flow path 33, the resin flow path is configured exactly the same as shown in FIG.
After flowing into the manifold, a leakage flow flows in the die axial direction through the annular resin flow passage 33 together with the circumferential flow flowing in the manifold, and the proportion of the leakage flow gradually increases as it goes downstream, and finally the leakage flow flows in the circumferential direction. This results in an axial flow with a uniform flow rate throughout.

A portion 36, in which the manifold has completely disappeared and only an annular resin flow path is formed, is a die discharge port formed from an annular slit.

Reference numeral 38 denotes a hollow portion provided in the die axis, into which an air introduction pipe 39 and an air discharge pipe 42 are inserted.

Reference numeral 40 denotes a guide portion of the air introduction tube, and 41 an elbow for connecting the air introduction tube 39 and the guide portion 40 of the tube.

The air discharge pipe 42 is provided with partition walls 43 and 44 on its outer periphery, and its outer periphery is supported on the inner surface of the air introduction pipe 39.

45 and 46 are supports for fixing the air introduction pipe 39 to the die hollow part 38.

47 and 48 are nozzles supported by an air introduction pipe and an air discharge pipe, respectively.

Cooling air is supplied to the guide section 40 of the air introduction pipe and the air discharge pipe 4.
2, is ejected from a nozzle composed of 47 and 48, and after circulating in a bubble made of an extruded resin tube enters the air exhaust pipe 42,
It is discharged outside the die through the path indicated by the arrow.

Instead of air, a liquid such as water may be circulated inside the air inlet pipe and the air outlet pipe.

In this case, a core is attached to the tip of the inner die ring, and the liquid that flows in from the inlet pipe flows through the core, enters the discharge pipe, and is discharged outside the die.

FIG. 3 is a plan view of a portion of the inner die ring related to the resin flow path.

The symbols in the figure are exactly the same as those explained in FIG.

FIG. 4 shows another embodiment of the invention.

In this figure, the flow groove provided in the inner die ring is the third
This embodiment is the same as the embodiment shown in the figure, but the shape of the resin flow path connected downstream of the flow channel groove is different from the previous example.

That is, the manifold that flows through the inlet 32 is not spiral-shaped twisted in the same direction starting from the inlet 32, but is arranged like a coat hanger so that it is symmetrical with respect to the die axis direction when viewed from the inlet 32. Manifold 3
4'.

However, this manifold differs from the above-mentioned flow groove in that both the inner and outer die rings are tightly fitted in the upstream direction of the manifold, and the manifold 34'
In the downstream direction, a gap is provided between both the inner and outer die rings to generate an axial flow flowing between the gaps together with a circumferential flow flowing through the manifold.

In this way, an annular resin flow path is formed downstream of the manifold 34'.

The above-mentioned manifold 34' does not necessarily have to be formed of a part of a spiral, and may have any shape close to that of a coat hanger; The detour flow flowing in the axial direction must have the same flow rate per unit width, ie, flow resistance, regardless of the position on the circumference of the die ring.

Therefore, it is preferable that the annular resin flow path downstream of the manifold has the longest axial distance at the inflow port 32, and gradually shortens the axial distance as it moves away from the inflow port 32 in the circumferential direction.

In the embodiments described above, the number of branches of the channel grooves provided on the inner peripheral surface of the die ring was all two, and the number of branched channel grooves was four.

However, the number of branches may be one or two or more.

If branching is performed n times, the number of channel grooves after branching is 2n.

FIG. 5 relates to a multilayer annular die according to the present invention, in which an outer die ring is sequentially fitted in an annular manner to an inner die ring.

51 is the innermost first die ring, 52 is a second die ring fitted on the outside of the first die ring, and 53 and 54 are third and fourth die rings fitted on the outside of the first die ring.

Resin is pumped by a first screw (not shown in this figure) and is supplied into the die through a first resin supply port 55.

The resin supplied from the supply port 55 flows into the channel groove 56 provided from the side of the die toward the die axis direction, passes through the fitted boundary surface between the first die ring 51 and the second die ring 52, and enters the second die ring 52. 1. The flow path groove 57 is formed on the outer surface of the die ring in the direction of the die axis, reaches a first branch point 58, and is arranged symmetrically with respect to the die axis direction when viewed from the branch point.
It flows into the branch channel groove 59.

The first branch channel groove of the two-branched button case is along the circumferential surface of the first die ring, and the angle with the die axis when viewed from the branch point is 90' with respect to each branch channel groove. reaches a position where the angle between them is 1800, and the channel groove 6 parallel to the die axis
Leads to 0.

The channel groove 60 parallel to the die axis has a second branch point 61 downstream thereof.
Then, it flows into the second branch channel groove 62 arranged symmetrically with respect to the die axis direction when viewed from the branch point.

The second branch channel groove of each button is further branched into two in this way, and each branch has an angle of 45 degrees with the die axis when viewed from the branch point along the circumferential surface of the first die ring. A position is reached where the angles formed by the channel grooves are 90' to each other, and the channel grooves 63 are connected to each other parallel to the die axis.

Furthermore, the flow channel groove reaches the inlet 64 and is formed into a spiral manifold 6 provided on the upstream side of the first annular resin flow channel 65.
Leads to 6.

Similarly, the resin pumped by a second screw not shown in this figure is supplied into the re-die through the second resin supply port 67.

The resin supplied from the supply port 67 flows into the channel groove 68 provided from the side of the die toward the die axis direction, passes through the fitted boundary surface between the second die ring 52 and the third die ring 53, and enters the second die ring 52 and the third die ring 53. The resin enters the flow channel groove carved on the outer surface of the second die ring, branches twice on the outer surface of the second die ring in the same manner as the first resin described above, passes through the inlet, and enters the second annular resin flow channel 6.
It connects to a spiral manifold 70 provided on the upstream inner side of 9.

Furthermore, the resin pumped by a third screw (not shown in this figure) is supplied into the re-die from the third resin supply lower 1.

The resin supplied from the supply lower 1 flows into the channel groove 72 provided from the side of the die toward the die axis direction, passes through the fitted boundary surface between the third die ring 53 and the fourth die ring 54, and then flows into the third die ring 53 and the fourth die ring 54. The resin enters the channel groove carved on the outer surface of the third die ring, branches twice toward the outer surface of the third die ring in the same manner as the first and second resins described above, and passes through the inlet into the third annular resin. It is connected to a spiral manifold 74 provided on the upstream side of the resin flow path 73.

In this way, the flows consisting of the three annular resin flow paths merge at the confluence point 75 to form a three-layer flow, which is discharged from the annular discharge lower part.

A first die ring tip piece 77 is attached to the tip of the first die ring 51, and a circular tubular hollow chamber 78 is formed at the rear of the center.

A connecting piece 79 is inserted into the hollow chamber 78 and can slide in the axial direction while lightly contacting the inner surface of the chamber.

A rod 80 is screwed into the rear end of the connecting piece 79, and a mandrel 81 whose tip is flared at the front end is screwed into the rod 80.

There is a drive mechanism (not shown) at the rear end of the rod 80.
0 can be moved in the axial direction.

The diverging part 82 at the tip of the mandrel is the fourth
An appropriate gap is maintained with the part 83 provided at the end outlet of the die ring, which also widens at the end, but by moving the mandrel 81 in the axial direction via the rod 80, the above-mentioned gap can be adjusted. The thickness of the tube extruded through this gap can be adjusted.

As described above, according to the present invention, the annular die is supplied with resin from the side with respect to the die axis, and when the resin reaches the annular resin flow path through the flow channel groove, two or more resin inflow ports are provided. can be provided.

It is extremely preferable to provide a large number of resin inlets distributed at equal intervals on the circumferential surface in order to ensure uniformity of the flow rate per unit width within the annular resin flow path.

Furthermore, since the flow path is branched by the flow path groove, processing is easier and cleaning is easier than in the case where the flow path is branched by a hole.

Further, although the channel grooves upstream of the inlet leading to the resin inlet mentioned above differ in direction with respect to the die axis, all of the channel grooves are the same in shape, and therefore, each channel groove has the same shape. It is easy to maintain the same flow rate of resin flowing through the tube.

This relationship does not change even if the factors that affect the viscosity index, such as the type of resin or temperature conditions, change, and the advantage is that no special consideration is required for operating conditions in order to ensure uniformity of flow rate. It has the following.

Examples of cases where it is difficult to feed the resin under pressure from the center of the die axis include when coating core materials such as electric wires with resin, or when cooling the inner surface of tubes with cooling air or water. There are cases where it is desired to move back and forth in the axial direction.

The latter two embodiments have been explained using the examples shown in FIGS. 2 and 5.

In a multi-layer annular die in which an outer die ring is sequentially fitted to a cut inner die ring, the innermost die ring and the annular resin flow passage fitted therein, that is, the innermost layer Even if it is possible to adopt the method of supplying resin from the shaft core to the resin flow path as shown in Figure 1, for the resin flow path outside of that method, it is necessary to feed the resin from the side to the die axis. It is much easier to arrange the flow path grooves.

Therefore, the advantages of the present invention over the multilayer annular die shown in FIG. 5 are extremely large.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway vertical cross-sectional view of an example according to a conventional method;
FIG. 2 is a partially cutaway vertical sectional view of an embodiment of the present invention, FIG.
FIG. 4 is a plan view of a portion of the inner die ring that is related to the resin flow path among the die rings that are fitted together, and FIG. 5 is a partially cutaway longitudinal section of another embodiment of the present invention. It is a diagram. In these figures, 1.21.51, 67.71 are resin supply ports, 4.6.24.25.27.28.30.31.5
6.57.59.60.62, 63.68.72 are channel grooves, 2.22.51° is inner die ring, 10.2
3.52.53.54 is an outer die ring or a die ring fitted sequentially on the outer side; 8.11.33.36.
65.69.73 is an annular resin flow path, 9.34.66
．． 70.74 is a spiral manifold, 34' is a manifold, 38 is a hollow part, 39.40 is a fluid introduction pipe, 4
Similarly, 2 is a discharge pipe, and 81 is a mandrel.

Claims (1)

[Scope of Claims] 1. In an annular die in which an outer die ring is fitted to an inner die ring, the inner and outer peripheries of this fitting are located on the upstream side where the resin flows other than the channel grooves described later. are tightly fitted, and on the downstream side, an annular resin flow path is formed between the inner and outer die rings, and the resin pumped from the screw is pushed from the side to the die axis. Then, the groove is branched into two, and each of the branched flow grooves can be seen from the branching point. The flow path grooves are arranged symmetrically with respect to the die axis direction, and the number of branching of the flow path grooves described above is made such that the branching is performed once or multiple times consecutively on the circumferential surface, so that the branched flow paths are An annular die characterized in that grooves are positioned so as to be distributed at equal intervals on the circumferential surface, and the channel grooves are connected from the positions to resin flow passages provided downstream of the circumferential surface. . 2. The annular die according to claim 1, which is a multilayer annular die in which an outer die ring is sequentially fitted into an inner die ring. 3. A spiral manifold whose depth gradually decreases as it goes downstream is placed at the upstream part of the annular resin flow path and on the outer surface of the die ring which is inside the flow path, and is branched and placed on the die ring peripheral surface. The annular die according to claim 1, wherein the flow grooves arranged at equal intervals are connected to the starting point of the manifold. 4 A manifold is provided on the outer surface of the die ring at the upstream side of the annular resin flow path and inside the flow path, and the inner and outer die rings are tightly fitted in the upstream direction of the manifold when viewed in the die axis direction. A patent claim in which a gap is provided between both the inner and outer die rings in the downstream direction of the manifold, and the flow channels are branched and connected to manifold starting points arranged at equal intervals on the circumferential surface of the die ring. An annular die according to scope 1. 5. The annular die according to claim 1, wherein the inside of the inner die ring is hollow in the axial direction, and a fluid introduction pipe and a fluid discharge pipe are provided in the hollow part. 6. The annular die according to claim 1, wherein the inside of the inner die ring is hollow in the axial direction, and a manodrel that is movable in the axial direction and in the front-rear direction is provided in the hollow part. 7. The annular die according to claim 1, wherein the inside of the inner die ring is hollow in the axial direction, and a core material movable in the axial direction and in the extrusion direction is passed through the hollow portion.