JPH11105101A - Mold for tubular member and manufacture of the member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a tubular member for continuously molding the member with excellent strength and rigidity in a circumferential direction circumferentially efficiently reinforced by a fibrous reinforcing material by substantially uniformly orienting reinforcing material in inner and outer layers of the member in the case of molding to rotate a molding material mixture containing the reinforcing material and thermoplastic resin flowing in an annular channel of the mold. SOLUTION: In the mold for a tubular member, an annular channel 3 is constituted by an inner mold 1 and an outer mold 2. A rotating unit 22 rotating by a driving means at a rotary shaft extended in the same direction as an extruding direction of a molding material mixture as a center is provided at least part or all of the molds 1, 2. At least one protrusion 21 of a substantially columnar shape protruding into the channel 3 is provided at the unit 22. The method for manufacturing the member comprises the steps of passing the molding mixture while rotating the rotating unit, molding the mixture in a tubular state so as to receive a twisted shearing force in a rotating direction from the unit, and forming the member obtained by orienting fiber reinforcing material in the circumferential direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for forming a tubular body suitable for use in producing a resin tubular body reinforced by a reinforcing material, and to a method for producing a tubular body using the mold. .

[0002]

2. Description of the Related Art Conventionally, in order to increase the strength of a resin tubular body, a fibrous reinforcing material has been mixed.

However, according to the conventional method, since the fibrous reinforcing material is oriented in the extrusion direction, the fiber is reinforced in the extrusion direction, that is, in the longitudinal direction of the tubular body, but is not reinforced in the circumferential direction of the tubular body. There was a disadvantage.

In order to solve such a drawback, for example, as described in Japanese Utility Model Application Laid-Open No. 61-71421, a nipple (inner die) and a die (outer die) provided coaxially with the nipple are disclosed. And a die for forming a tubular body in which one of a nipple and a die is rotationally driven.

[0005]

However, in such a mold for forming a tubular body, the reinforcing material is oriented in the direction in which the shearing force acts due to the effect of the shearing force given by rotation of one of the nipple and the die. However, in a range where the influence of the shearing force is not exerted, the effect cannot be exhibited, and the reinforcing material is not oriented in the circumferential direction. That is, for example, when the nipple rotates, the reinforcing material is oriented in the circumferential direction of the tubular body in the vicinity of the inner layer in contact with the nipple of the formed tubular body, but in the vicinity of the outer layer remote from the nipple, the reinforcing material is used. Are not oriented in the circumferential direction of the tubular body, but are merely oriented in the longitudinal direction.

The present invention has been made in view of such problems in a conventional mold for forming a tubular body, and an object thereof is to provide an annular flow path (hereinafter, referred to as an annular flow path) of the mold. In the molding in which the reinforcing material mixed resin flowing in the annular flow path is rotated, the reinforcing material can be oriented substantially uniformly in the circumferential direction in the inner and outer layers of the tubular body, and the reinforcing material efficiently reinforces the circumferential direction. An object of the present invention is to provide a mold for forming a tubular body capable of continuously forming a tubular body having excellent strength and rigidity in a circumferential direction and a method of manufacturing the tubular body.

[0007]

In order to achieve the above object, a mold for forming a tubular body according to the present invention has an annular flow path composed of an inner mold and an outer mold. At least one part or all, provided with a rotating part that rotates about a rotating shaft extending in the same direction as the extrusion direction of the molding material mixture containing the reinforcing material and the thermoplastic resin and that is driven by the driving means,
The rotating portion is provided with at least one substantially cylindrical projection projecting into the annular flow path.

A method for producing a tubular body according to the present invention is a method for producing a tubular body using the mold, wherein a molding material mixture containing a reinforcing material and a thermoplastic resin is connected thereto by an extruder. Introduced into the annular flow path of the mold, at least a part or all of the inner mold and the outer mold constituting the annular flow path,
A rotating portion is provided which is rotated about a rotating shaft extending in the same direction as the extrusion direction of the molding material mixture and which is rotated by a driving means, and at least one substantially cylindrical convex portion is provided on the rotating portion to project into the annular flow path. The molding material mixture is passed while rotating the rotating portion, and the mixture is formed into a tubular shape so that the mixture receives a torsional shearing force in the rotating direction from the rotating portion, and the fibrous reinforcing material is circumferentially oriented in a tubular shape. It is characterized in that a molded body is formed.

[0009]

Embodiments of the present invention will now be described with reference to the drawings.

First, as shown in FIGS. 1A and 1B, the mold for forming a tubular body of the present invention comprises an inner mold (1) and an outer mold (2), and an inner mold (1) and an outer mold ( An annular flow path (3) is formed between the inner mold (1) and the outer mold (2) of the inner mold (1) and the rotating part (22) rotatably supported by the outer mold (2). This rotating part (22)
The required number of substantially cylindrical projections (2
1) is provided.

As shown in FIGS. 2A and 2B, the inner mold
(1) is provided with a rotating part (12) rotatably supported, and the rotating part (12) is provided with a required number of substantially cylindrical convex parts (11) projecting into the annular flow path (3). It may be. Further FIG.
As shown in FIG. 3B and FIG. 3B, rotating parts (12) and (22) rotatably supported by the inner mold (1) and the outer mold (2) are provided, and these rotating parts (12) and (22) are provided. Substantially cylindrical projections (11) and (21) projecting into the annular flow path (3) may be provided.

In the present invention, the substantially cylindrical projections (11) and (21)
The relationship between the height protruding into the annular flow path (3) and the size of the gap in the annular flow path (3) is shown in FIG. Assuming that the height protruding into the flow channel (3) is h and the size of the gap between the annular flow channels (3) is t, the height h of the projections (11) and (21) is from t / 10 to 99t. / 100 is desirable.

That is, the height h of the projections 11 and 21 is t / 1.
If it is less than 0, it is difficult to obtain the effects of the projections (11) and (21),
Conversely, when the height h of the projections (11) and (21) exceeds 99 t / 100, heat generation due to shearing is large and the resin temperature becomes non-uniform,
Since the influence of the shearing force is also non-uniform, not only the homogeneity of the reinforcing material (72) is hardly developed, but also the molding pressure may be extremely large.

The arrangement (arrangement method) of the plurality of substantially cylindrical projections (11) and (21) is not particularly limited.
Although they may be arranged in a random arrangement or may be regularly arranged, it is preferable to form a so-called staggered arrangement in the circumferential direction as shown in the figure.

Referring to FIG. 4, a plurality of substantially cylindrical projections are provided.
(11) The distances S1 and S2 between (21) are 1m at the shortest distance
m or more. Multiple substantially cylindrical protrusions (11)
(21) When the interval between the convex portions is less than 1 mm, the convex portions
(11) The flow of the resin between (21) and (21) is deteriorated, and the molding pressure may be abnormally large.

The rotating parts (12) and (22) have annular flow paths (3)
At least one substantially cylindrical projection (11) (21)
What is necessary is just to be provided.

According to the present invention, in forming by rotating a molding material mixture containing a reinforcing material and a thermoplastic resin flowing in the annular flow path (3) of the mold, the reinforcing material (72) is added to the tubular body (7). A tubular body (7) that is oriented substantially uniformly in the circumferential direction in the inner and outer layers of the thermoplastic resin layer (71) and is efficiently reinforced in the circumferential direction by the reinforcing material (72) and has excellent strength and rigidity (FIG. 5). ) Is continuously formed.

Referring now to FIG. 3, in the present invention, a rotating part (1) comprising an inner die (1) and an outer die (2) at least one of which rotates coaxially with the extrusion direction.
2) Assuming that the length of the flow path in (22) in the discharge direction is L, the value of L / t is preferably 1 or more in relation to the gap size t of the annular flow path (3). , And more preferably 5 or more and 100 or less. Here, if the value of L / t is less than 1, it is difficult to orient the reinforcing material (72) in the resin (71) in the direction of the shearing force.

In the present invention, at least a part of at least one of the inner mold (1) and the outer mold (2) is rotatably supported, and the rotating parts (12) and (22) are driven by external rotating means. When both the inner mold (1) and the outer mold (2) rotate, they may rotate in the same direction or in opposite directions.

In the present invention, the rotational speed of at least one of the rotating parts of the inner mold (1) and the outer mold (2) is not particularly limited. Considering the orientation of the material (72), the rotation speed of the rotating part is 1 to
1000 rpm.

Here, if the rotation speed of the rotating part is less than 1 rpm, the effect of orientation of the reinforcing material cannot be sufficiently obtained. Conversely, if the rotation speed exceeds 1000 rpm, shear heat generation becomes remarkably difficult to form.

In the method of manufacturing a tubular body using the mold of the present invention, the tubular body (7) extruded from the mold as shown in FIG.
Preferably, in the take-off step, the tubular body (7) is cooled to a temperature at which the shape and inner and outer diameters of the tubular body (7) do not plastically change, and more preferably to ambient temperature (outside air temperature).

As means for cooling the tubular body (7), a method of passing the tubular body (7) through a coolant such as a water tank, a method of applying cool air with a blower or the like, and a method of passing a coolant through a cooling mold are used. Methods and the like can be cited, and are appropriately selected according to the dimensions of the product and the production line.

As the extrusion method in the present invention, any conventionally known method may be adopted, for example, a single screw extruder or a twin screw extruder is used.

As a method of picking up the cooled product,
A conventionally known arbitrary method may be employed, and for example, a belt type take-up machine, a caterpillar type take-up machine, a roll type take-up machine and the like can be appropriately used.

In the present invention, the thermoplastic resin (71), which is a raw material for production, is not particularly limited.
For example, ABS resin, fluorine resin, acrylic resin, polyethylene resin, polypropylene resin, vinyl chloride resin,
Polycarbonate, polystyrene, polyurethane, and the like, and resins that can be melt-molded such as modified resins thereof, blended resins, alloy resins, and the like can be given.

Examples of the reinforcing material (72) to be mixed with the thermoplastic resin (71) include glass fibers, carbon fibers, metal fibers, organic fibers such as ultrahigh molecular weight polyethylene fibers, and inorganic fibers such as ceramic fibers.

The fibers may be those to which a surface treatment agent or a binder is appropriately added according to the thermoplastic resin to be mixed.

In addition, those having a form capable of improving the strength in the direction when oriented, for example, a liquid crystal polymer which becomes a fibrous reinforcing material (72) by being subjected to shearing in a mold can also be used. Glass fibers are advantageous from the viewpoint of cost and handling.

As the reinforcing material (72) that is easily oriented in a molecule, a wholly aromatic liquid crystal polyester or a semi-aromatic liquid crystal polyester, which is a liquid crystal polymer, can be cited. Orientation.

As the form of the reinforcing material (72) to be mixed, a monofilament-like material such as milled fiber or cut fiber may be used as it is, a chopped strand in which several fibers are bundled, or a roving-like material. Continuous fibers may be used.

The mixing of the reinforcing material (72) and the thermoplastic resin (71) is achieved in an extruder after being dry-mixed with a mixer such as a tumbler, or the reinforcing material other than the main raw materials is mixed with the extruder. It may be achieved in the extruder fed from the middle. Alternatively, pre-mixed pellets manufactured using a strand die or the like may be used.

The reinforcing material mixed in the thermoplastic resin (71)
The shape of (72) may be a shape obtained by cutting continuous fibers such as glass fibers to an appropriate length, or a so-called whisker shape.

The length of the reinforcing material (72) is not particularly limited, but the aspect ratio (fiber length / fiber diameter) is preferably 1 or more.

When the aspect ratio is less than 1, the reinforcing effect by the fiber may not be exhibited.

When short glass fibers are used as the reinforcing material (72), the aspect ratio is preferably 1000 or less.
There is a possibility that the material is cut by the screw shaft of the extruder and the reinforcing effect corresponding to the length cannot be expected.

The fiber diameter is preferably about 1 to 100 μm, and the fiber length is preferably about 1 μm to 100 mm.

The mixing of the reinforcing material (72) and the thermoplastic resin (71)
This is achieved in an extruder after dry mixing in a mixer such as a tumbler.

In some cases, mixed pellets formed by using a strand die or the like may be used.

The mixing ratio of the reinforcing material (72) to the thermoplastic resin (71) is within a range in which the whole composition can be molded in the following extrusion step, and the mixing ratio is required for the composition of the thermoplastic resin and the product required. It is appropriately selected depending on the performance.
A suitable range is 80% by volume, preferably 2 to 50% by volume.

In the present invention, the inner mold (1) or the outer mold
As means for rotating the rotating part of (2), for example, as shown in FIG. 4b, the rotating part (12) of the inner mold (1) (or outer mold) of the mold is used.
The sprocket wheel (W1) is attached to the rotating shaft (1a), and the sprocket wheel (W1)
A power transmission mechanism such as a belt or chain between the motor and the sprocket wheel (W2) attached to the rotating shaft (41) of the motor (4)
(5) and rotate the motor (4) with the rotating part (1
You may make it transmit to 2).

(Function) In the mold for forming a tubular body of the present invention, the annular flow path is constituted by an inner mold and an outer mold, and at least one or both of the inner mold and the outer mold is provided with a resin mixed with a reinforcing material. A rotation unit is provided rotatably supported about a rotation axis extending in the same direction as the extrusion direction of the molding material mixture including the reinforcing material and the thermoplastic resin, and the rotation unit is driven and rotated by drive rotation means, The rotating portion is provided with at least one substantially cylindrical convex portion protruding into the annular flow path, and the method of manufacturing a tubular body according to the present invention includes manufacturing the tubular body using the mold. A method, wherein a molding material mixture containing a reinforcing material and a thermoplastic resin is introduced from an extruder into an annular flow path of the mold connected thereto, and molding is performed while rotating a rotating portion of the mold. After passing the material mixture, the mixture To form a tubular molded body in which the fibrous reinforcing material is oriented in the circumferential direction, according to the present invention, according to the present invention, the flow path between the convex portions of the rotating portion In the portion, the reinforcing material mixed resin in the vicinity of the rotating portion surface is oriented in the circumferential direction of the annular flow channel under the influence of the shearing force due to the rotation of the rotating portion itself corresponding to the flow channel portion, and the tip surface of each convex portion The nearby reinforcing material-mixed resin is oriented in the circumferential direction of the annular flow path under the influence of the shearing force due to the rotation of the projection itself.

As a result, it is possible to obtain a uniform tubular body in which the reinforcing material is substantially uniformly circumferentially oriented from the inner layer to the outer layer of the tubular body to be formed. In addition, if the inner mold or the outer mold near the outlet of the annular flow path is cooled, it becomes easier to appropriately solidify the resin in the molten state and to obtain the desired orientation of the reinforcing material.

[0044]

Next, examples of the present invention will be described with reference to the drawings together with comparative examples.

Example 1 A tubular body (7) shown in FIG. 5 having an outer diameter of 60.0 mm and a thickness of 5.0 mm was obtained by using the mold for forming a tubular body of the present invention shown in FIG.
Was manufactured.

The thermoplastic resin (71) has a density of 0.9.
35 g / cm ³ , melt index 0.20 g / 1
Medium density polyethylene that was 0 minutes was used.

As the reinforcing material (72) mixed with the thermoplastic resin (71), 10% by weight of a glass fiber chopped strand having a diameter of 15 μm and a length of 5 mm was dry-mixed with a mixer.

As shown in FIG. 4B, a rotating shaft (1a) is protruded from the rotating portion (12) of the inner mold (1) of the mold, and a sprocket wheel (W1) is attached to the rotating shaft (1a). A power transmission mechanism (5) such as a belt or a chain is stretched between the sprocket wheel (W1) and the sprocket wheel (W2) attached to the rotating shaft (41) of the motor (4) to rotate the motor (4). Is transmitted to the rotating part (12) of the mold.

The rotational speed of the inner mold (1) of the annular flow path (3), which is made to rotate coaxially with the extrusion direction, is 50 rpm, the rotational speed of the outer mold (2) is 0 rpm, and the rotating section (12) The size t of the annular gap of the flow path was 5.0 mm.

The effective length (La) of the rotating part (12) of the inner mold (1) in the extrusion direction was 100 mm.

At the substantially cylindrical projection (11), the diameter R of the circle
Was 2 mm, and the height h projecting into the annular flow path (3) was 4 mm. The number of the substantially cylindrical projections (11) is two in the circumferential direction,
A total of six in three rows were installed in the extrusion direction. Substantially cylindrical protrusion (1
The arrangement between 1) was made to be linearly located at a symmetrical position in the circumferential direction (180 ° symmetry) and at a position inclined by 90 ° in the extrusion direction. The distance between the protrusions in the extrusion direction between the substantially cylindrical protrusions (11) was S1 and S2 = 10 mm. Convex (1
The length Sd from the center of the end in the extrusion direction of 1) to the exit end in the extrusion direction of the inner die 1 was 20 mm.

The extruder (6) used was a single screw extruder, and the thermoplastic resin (71) had a melting temperature of 200 ° C. and the outer mold (2) had a temperature of 20 ° C.
The temperature was 0 ° C., and the inner mold (1) was neither cooled nor heated. The extrusion speed was 0.50 m / min.

Next to the cooling shaping die, a take-up process was performed by a belt-type take-up machine to take out the tubular body (7).

Example 2 In Example 1, the reinforcing material was mixed with the thermoplastic resin (71).
As (72), a mixture obtained by dry-mixing 10% by weight of a wholly aromatic liquid crystal polyester having a liquid crystal transition temperature by DSC of 280 ° C. with a mixer was used. Further, the temperature of the molten resin in the flow path of the rotating part is 290 ° C., the temperature of the outer mold (2) is 290 ° C.,
The molten resin temperature near the end of the non-rotating part flow path is 200 ° C.
The outer mold (2) was cooled to 200 ° C. to produce a tubular body (7).

Example 3 In Example 1, the height h of the projection (11) was 2.0 mm.

Comparative Example In Example 1, a molding die was used in which the rotating portion (12) of the inner die (1) was not provided with the substantially cylindrical projection (11).

Evaluation The tubular bodies (7) obtained in Examples 1 to 3 and Comparative Example were obtained.
The test pieces shown in FIGS.

That is, as shown in FIGS. 6 to 8, an outer layer, a middle layer, and an inner layer of a test piece were cut out from one side wall of the tubular body (7), and three sections from the outer surface to the inner surface of the tubular body (7) were cut out. It has a notch (76) to divide.

A tensile test was performed by pulling these test pieces from both ends, and the homogeneity of the reinforcing material (72) was compared based on the difference in tensile strength. Further, a ring-shaped test piece having a width of 30 mm was cut out and pulled in a radial direction while being held by a semicircular jig, thereby performing a circumferential tensile test.

Table 1 shows the results. (Each test value is n =
Average of 5)

[Table 1] As is clear from Table 1, in Examples 1 to 3, the tensile strength in the axial direction of the tubular body (7) is uniform without a large difference between the outer layer, the intermediate layer and the inner layer. And, the tensile strength in the circumferential direction is greatly increased as compared with the comparative example.

Incidentally, in the comparative example, the reason why the axial tensile strength of the outer layer is abnormally high is that the reinforcing material is not oriented in the circumferential direction near the outer mold which is not affected by the shearing force. The difference between the intermediate layer and the inner layer was large, and the tensile strength in the circumferential direction was small.

The embodiment of the present invention has been described with reference to the drawings. However, the specific configuration of the present invention is not limited to the illustrated embodiment, and the design may be changed within the scope of the present invention. Are included in the present invention.

[0063]

According to the present invention, as described above, the mold for forming a tubular body of the present invention has an annular flow path composed of an inner mold and an outer mold.
In part or all of at least one of the inner mold and the outer mold,
A rotating part is provided which is rotated about a rotating shaft extending in the same direction as the extrusion direction of the molding material mixture containing the reinforcing material and the thermoplastic resin and is driven by driving means, and at least one of the rotating parts protrudes into the annular flow path. Two substantially cylindrical projections are provided, and the method of manufacturing a tubular body of the present invention is a method of manufacturing a tubular body using the mold, wherein a reinforcing material and a thermoplastic resin are used. The molding material mixture containing the mixture is introduced from an extruder into the annular flow path of the mold connected thereto, and the molding material mixture is passed while rotating the rotating part of the mold, and the mixture is rotated from the rotating part. According to the present invention, the reinforcing material is formed in the inner and outer layers of the tubular body by forming the tubular shaped body in which the fibrous reinforcing material is oriented in the circumferential direction. Can be oriented almost uniformly in the direction Te is an effect that it is possible to form the reinforcement by circumferentially effectively reinforced circumferential strength and rigidity in good tubular body continuously.

The molded article of the tubular body produced according to the present invention can be suitably used for applications requiring circumferential strength and rigidity, such as various pipes and poles.

[Brief description of the drawings]

FIG. 1a is an enlarged cross-sectional view of a main part showing a first example of a mold for forming a tubular body according to the present invention. FIG. 1b is an enlarged vertical sectional view of the main part.

FIG. 2A is an enlarged cross-sectional view of a main part showing a second example of the mold for forming a tubular body of the present invention. FIG. 2B is an enlarged vertical sectional view of the main part.

FIG. 3a is an enlarged cross-sectional view of a main part showing a third example of a mold for forming a tubular body according to the present invention. FIG. 3b is an enlarged vertical sectional view of the main part.

FIG. 4a is an enlarged cross-sectional view of a main part showing a mold for forming a tubular body used in an embodiment of the present invention. FIG. 4b is an enlarged vertical sectional view of the essential part, showing a state in which a rotating means is connected to a tubular body molding die.

FIG. 5 is a perspective view showing a state in which a test piece is cut out of a tubular body manufactured using the tubular body molding die of the present invention.

FIG. 6 is a perspective view showing an example of a test piece cut out from the tubular body of FIG.

FIG. 7 is a perspective view showing another example of the test piece.

FIG. 8 is a perspective view showing still another example of the test piece.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inner die 2 Outer die 3 Annular flow path 4 Motor (drive means) 6 Extruder 7 Tubular body 11 Convex part 12 Rotating part 21 Convex part 22 Rotating part 71 Thermoplastic resin 72 Reinforcement

Claims (2)

[Claims] 1. An annular flow path comprising an inner mold and an outer mold, wherein at least one or more of the inner mold and the outer mold has a direction in which a molding material mixture containing a reinforcing material and a thermoplastic resin is extruded. A rotating portion is provided which rotates about a rotating shaft extending in the same direction and is rotated by a driving means, and the rotating portion is provided with at least one substantially cylindrical projection projecting into the annular flow path. A mold for forming a tubular body. 2. A molding material mixture containing a reinforcing material and a thermoplastic resin is introduced from an extruder into an annular flow path of a mold connected to the extruder to form an inner mold and an outer mold forming an annular flow path. At least one part or the whole is provided with a rotating part which is rotated by a drive means around a rotating shaft extending in the same direction as the extrusion direction of the molding material mixture, and at least one part of the rotating part which protrudes into the annular flow path. Two substantially columnar convex portions are provided, and the molding material mixture is passed while rotating the rotating portion, and the mixture is formed into a tubular shape so that the mixture receives a torsional shearing force in the rotating direction from the rotating portion, thereby forming a fibrous material. A method for producing a tubular body, which forms a tubular molded body in which a reinforcing material is circumferentially oriented.