JPS6311966B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to a crosshead device for an extruder that extrudes and coats the surface of a core material of an electric wire or the like with a resin or the like. (Prior Art) A crosshead device for an extruder for coating the surface of a core material such as an electric wire with a coating material such as a resin is well known.
In these crosshead devices, the coating material must be coated with a uniform thickness all around the circumference, so an important issue is how to uniformly spread the coating material supplied from the extruder in the circumferential direction. be. To solve these problems, for example, Japanese Patent Publication No. 53-43544, Japanese Utility Model Application Publication No. 146317-1982,
The technique described in Japanese Unexamined Patent Publication No. 57-95018 and the like is known. In order to spread the coating material supplied from the extruder uniformly over the entire circumferential direction of the core material, this conventional type has an annular material reservoir and applies pressure to the material over the entire circumferential direction. In this method, the pressure is made uniform over the entire circumferential direction by keeping the pressure constant or by branching the material supply section that supplies the material from the extruder to the entire circumferential direction of the core material to make the passage lengths equal. (Problems to be Solved by the Invention) The above-mentioned conventional method provides an annular material reservoir and a branch passage to equalize the pressure of the coating material supplied to the outer peripheral surface of the core material over the entire circumferential direction. This is an attempt to equalize the supply amount and obtain a coating layer of uniform thickness, but it was difficult to obtain a uniform pressure distribution by simply providing an annular material reservoir or a branch path. . In particular, in multi-layer coatings, the outer layer material is coated extremely thinly, resulting in subtle unevenness in pressure distribution.
There was a problem that the thickness of the coating layer was non-uniform. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a crosshead device for an extruder that can provide a more uniform pressure distribution than conventional devices. (Means for Solving the Problems) In order to solve the above problems, the present invention takes the following measures. That is, the features of the present invention are as follows:
A distributor fitting hole is provided in the crosshead provided at the outlet of the extruder, a covering material outlet hole communicating with the extruder outlet is opened in the fitting hole, and a distributor is fitted into the fitting hole,
A core material insertion hole is provided at the center of the distributor, through which the core material runs, and a coating material supplied from the outlet hole is spread uniformly in the circumferential direction on the outer peripheral surface of the distributor. A passage is formed on one end surface of the distributor, and a conical passage is provided on the one end side of the distributor for supplying the coating material from the passage to the outer peripheral surface of the core material running through the insertion hole. In the extruder crosshead device thus formed, the outer circumferential surface of the distributor includes a coating material receiving recess communicating with the outlet hole, an annular recess communicating with the conical passage, and a development connecting these recesses. a passage is formed, and at the connection part of the expansion passage with the annular recess,
A plurality of triangular weirs whose triangular bases overlap the edges of the annular recess are provided in the circumferential direction, and a branch passageway is connected to the outside of both hypotenuses of each triangular weir and communicates with the annular recess. The branch passages on both sides of each weir are connected at the top side of the triangular weir, and the connecting part communicates with the receiving recess through the expansion passage, and the weir is connected to the covering material in the branch passages on both sides. The water is at a height that allows the water to pass through the upper surface of the weir and flow into the annular recess. (Function) According to the present invention, the coating material extruded from the extruder is supplied from the coating material outlet hole of the crosshead to the receiving recess formed on the outer peripheral surface of the distributor. The coating material supplied to the receiving recess passes through the expansion passage and reaches the branch passage. The coating material that has arrived at the branch passage is supplied to the annular recess through the branch passage, and reaches the annular recess after passing over a triangular weir sandwiched between the branch passages. Since such branch passages and weirs are provided along the circumferential direction of the annular recess, the coating material is supplied to the annular recess from the entire circumference of the annular recess.
The supplied coating material is kept under a substantially uniform pressure over the entire circumferential direction by the expansion passage, the branch passage, and the weir. In this way, the pressure of the sheathing material, which has been made almost uniform over the entire circumferential direction, is further equalized in the annular recess, and is supplied to the outer circumferential surface of the core material through the conical passage. Form a coating layer of uniform thickness. (Example) Hereinafter, an example of the present invention will be described based on the drawings. A first embodiment of the invention is shown in FIG. 1, which is a two-layer coating crosshead device. In the figure, a crosshead main body 2 is attached to an extruder outlet 1, and a nipple holder 3 for spreading the inner layer material and a distributor 4 for spreading the outer layer material are fitted concentrically into the main body 2. Nipple holder 3
An inner layer material receiving part 5 and an outer layer material receiving part 6 are provided on the outer peripheral surface of the nipple holder 3 and the distributor 4, respectively. The material 7 and the outer layer material 8 are coated with a uniform thickness on the surface of the core material which passes through the conical passage 4a of the nipple holder 3 and the distributor 4 and passes through both 3 and 4. The distributor 4 equalizes the outer coating material 8 made of resin on the circumference of the outlet, and its details are as shown in FIGS. 2 and 3, and the coating material passage is It is as shown in FIGS. 4-6. That is, the distributor 4 is formed in a true cylindrical shape, and has a coating material receiving recess 9 on its outer circumferential surface, and a deployment passage 10 is connected to the recess 9, and a Y-shape is formed at the end of the passage 10. A branch passage 10a is provided in series, the terminal end of which is provided in series with an annular recess 10b, and the recess 10b is open to the end surface of the distributor 4,
It communicates with the conical passage. A triangular weir 11 is provided between the pair of branch passages 10a to equalize the pressure drop of the covering material. Said branch passage 1
The actual flow lines of the sheathing material inside 0a and the weir 11 are curves as shown by the imaginary lines in Figure 7, and if an equal flow rate is to be obtained at the outlet, the pressure drop will be equal on each streamline. The passage 10, branch passage 10a and weir 11 must be manufactured. However, since such processing is difficult in practice, the streamlines are approximated as shown by solid lines in FIG. 7 and manufactured. Therefore, in order to obtain a coating layer of uniform thickness, it is necessary to try and
Due to the error, it is necessary to correct the height of the weir 11 and the depth of the branch passage 10a. What is shown in FIG. 8 is a second embodiment of the present invention. A crosshead body 20 attached to the extruder outlet has a nipple holder fitting hole 21 and a distributor fitting hole 22 concentrically penetrating therethrough. The former insertion hole 21 is a straight hole, and the latter insertion hole 22 has a larger diameter than the former insertion hole 21 and is formed into a tapered hole that tapers toward the inside. Insert the nipple holder 2 into the nipple holder insertion hole 21.
3 are fitted, and the distributors 24 are respectively fitted into the distributor fitting holes 22.
A die 25 is integrally fitted into the axial center of the distributor 24. A core material insertion hole 26 is formed coaxially through the axial center of the nipple holder 23 and the die 25. A core material runs through the insertion hole 26 in the direction of arrow a in the figure. Nipple holder 23 and die 25, and distributor 24 and distributor fitting hole 2
The abutting and opposing end surfaces of the bottom surfaces of 2 are formed into a conical shape, and a conical passage 27 communicating with the core material insertion hole 26 is formed between the end surfaces. The distributor 24 is pressed inward in the axial direction by the die holder 28, and the outer circumferential tapered surface of the distributor 24 and the tapered surface of the distributor fitting hole 22 fit together, thereby forming the conical passage 27 into a predetermined position. Clearance is ensured. A nipple holder 2 is attached to the crosshead body 20.
An inner layer material outlet hole 29 and an outer layer material outlet hole 30 are provided facing and opening on the outer peripheral surfaces of the distributor 3 and the distributor 24, respectively. The inner layer material 31 supplied from the inner layer material outlet hole 29 is supplied to the nipple holder 23.
It is expanded in the circumferential direction in the gap between the fitting surfaces of the crosshead body 20 and the crosshead body 20, passes through the conical passage 27, and is coated on the surface of the core material. On the other hand, the outer layer material 32 supplied from the outer layer material outlet hole 30 is expanded in the circumferential direction in the gap between the fitting surfaces of the distributor 24 and the crosshead body 20, passes through the conical passage 27, and coats the surface of the core material. The surface of the inner layer material 31 is coated. In order to ensure uniform coverage of the outer layer material 32,
The outer peripheral surface of the distributor 24 has the ninth and tenth
It is molded into the shape shown in the figure. That is, on the outer peripheral surface of the distributor 24,
A spot-shaped receiving recess 33 is provided which matches the outer layer material outlet hole 30. A deployment passage 34 is connected from the receiving recess 33 for deploying the outer layer material 30 in the circumferential direction with a substantially equal pressure drop over the entire circumferential area. The terminal end of the expansion passage 34 is a branch passage 35 distributed in the circumferential direction, and within the passage 35, triangular weirs 36 are provided at equal intervals in the circumferential direction so that each streamline has a substantially equal pressure drop. It is provided. A ring-shaped reservoir 37 is provided which communicates with the branch passage 35 via this weir 36. Further, the outer peripheral edge of the ring-shaped reservoir 37 forms an edge of the distributor 24, and the peripheral edge is connected to the reservoir 37 through a predetermined gap from the inner peripheral surface of the distributor fitting hole 22. It is formed into an annular lip portion 38 that communicates with the conical passage 27. The groove shape of the ring-shaped reservoir 37 is the 11th, 1st
It is determined as shown in Figure 2. That is, when the outer layer material that has been made substantially uniform by the weir 36 flows into the ring-shaped reservoir 37, the non-uniform portion flows along the ring groove of the ring-shaped reservoir 37 and becomes Δgy, resulting in further uniformity. achieved. The pressure drop due to the flow △gy in this ring-shaped reservoir 37, △
Pressure drop when P passes through lip portion 38 △
The size of the ring-shaped reservoir 37 is determined so that it is smaller than Po. Furthermore, this ring-shaped reservoir 37
△ resulting in pressure drop △P due to flow △gy in
The flow distance l of gy is half the distance between the passages 35
The size of the ring-shaped reservoir 37 is determined so that it is larger than L. According to the second embodiment of the present invention, the outer layer material 32
from the receiving recess 33 to the deployment passage 34 and the branch passage 3
By passing through the weir 36 in 5, the pressure drop is substantially equal over the entire circumferential area. Further, in the ring-shaped reservoir 37, the pressure of the outer layer material 32 is completely equalized over the entire circumferential area, and the pressure of the outer layer material 32 is uniformly applied to the conical passage 27 beyond the lip 38.
This ensures that the coating has a uniform thickness. Furthermore, since the distributor 24 and the fitting hole 22 are fitted in a tapered manner, there is no looseness in the radial direction compared to the conventional right cylindrical fitting. Therefore, the gap between the lip portion 38 and the inner surface of the fitting hole 22 is made uniform over the entire circumferential direction. Furthermore, since the concentricity of the distributor 24 and its insertion hole 22 is accurate, the gap between the conical passages 27 is also made uniform.
Covering with uniform wall thickness can be ensured. Next, the results of actually manufacturing a two-layer foam skin wire for communication cables using the two-layer coated crosshead of the second embodiment are shown in the following table. In this two-layer foam skin wire, as shown in FIG. 13, the core material 39 is made of copper wire, the inner layer material 31 is made of HDPE for packaging, and the outer layer material 32 is made of solid HDPE.

[Table] As is clear from the above table, the thickness of the outer layer is extremely uniform. 14 and 15 is a third embodiment of the present invention, in which a ring groove 40 is recessed in the inner peripheral surface of the distributor fitting hole 22 of the crosshead main body 20, and an outer layer material is formed in the ring groove 40. The outlet hole 30 is open. The receiving recess 33 provided on the outer periphery of the distributor 24 is formed into a spot-like recess so as to coincide with the ring groove 40. The expansion passage 34 is connected to the receiving recess 33 so as not to intersect with the ring groove 40 .
The other configurations are the same as those of the second embodiment. According to the third embodiment of the present invention, even if the distributor 24 and its insertion hole 22 are rotated relative to each other, the receiving recess 33 and the outlet hole 30 are not connected to the ring groove 40.
Since they are always in communication via the distributor 24, assembly and adjustment of the distributor 24 becomes extremely easy. Note that the ring groove 40 is connected to the distributor 2.
4 and the ring groove 40 is used as a receiving recess, the same effect as in the third embodiment can be obtained. It should be noted that the present invention is not limited to each of the embodiments described above, and can be applied not only to a two-layer coated crosshead but also to other coated crossheads.
Further, the core material is not limited to an electric wire, but may be a pipe or the like. Furthermore, although the distributor and nipple holder are shown as being fitted directly into the crosshead body, they may be fitted into the crosshead body via a cartridge, or the distributor and the die may be integrated. . (Effects of the Invention) According to the present invention, on the outer peripheral surface of the distributor, the coating material is spread uniformly over the entire circumference in the circumferential direction via the development path, the branch passage, the weir, and the annular recess. This makes it possible to perform uniform coating, and when processing the expansion passage, even if the expansion passage is processed with rougher precision than before, the pressure of the coating material is uniform in the reservoir, allowing rough processing and making processing easier. This is something that will be promoted.

[Brief explanation of the drawing]

1 to 7 show a first embodiment of the present invention, in which FIG. 1 is a sectional view of a two-layer coated crosshead, FIG. 2 is a front view of a distributor, and FIG. 4 is a developed view of the outer circumferential surface of the distributor, FIGS. 5 and 6 are sectional views taken along lines - and - in FIG. 4, and FIG. 7 is an explanatory diagram showing streamlines of the covering material. , FIG. 8 is a sectional view of a two-layer coated crosshead showing a second embodiment of the present invention, FIG. 9 is a front view of the same distributor, FIG. 10 is a sectional view taken along the line of FIG. Fig. 12 is an explanatory diagram for determining the groove shape of the ring-shaped reservoir;
14 is a sectional view showing a third embodiment of the present invention, and FIG. 15 is a front view of the same distributor. 20... Crosshead main body, 24... Distributor, 27... Conical passage, 32... Covering material, 33... Receiving recess, 34... Expansion passage, 37
...Tamebe, 38...Rip section.

Claims (1)

[Claims] 1. A distributor fitting hole is provided in the crosshead provided at the outlet of the extruder, and a coating material outlet hole communicating with the extruder outlet is opened in the fitting hole, and a distributor fitting hole is opened in the fitting hole, and a coating material outlet hole communicating with the extruder outlet is opened in the fitting hole. A distributor is inserted into the distributor, and the center of the distributor is provided with a core material insertion hole through which the core material runs, and the outer peripheral surface of the distributor is provided with a covering material supplied from the outlet hole. A passage is formed in which the covering material from the passage is sent to one end surface of the distributor, and the outer circumferential surface of the core material running through the insertion hole is formed on the one end surface side of the distributor. In a crosshead device for an extruder in which a conical passage is formed for supplying the distributor, the outer peripheral surface of the distributor includes a coating material receiving recess that communicates with the outlet hole, and an annular recess that communicates with the conical passage; A development passage is formed that communicates both of these recesses, and at a connecting portion of the development passage with the annular recess,
A plurality of triangular weirs whose triangular bases overlap the edges of the annular recess are provided in the circumferential direction, and branch passages are connected to the outside of both hypotenuses of each of the triangular weirs and communicate with the annular recess. The branch passages on both sides of each weir are connected at the top side of the triangular weir, and the connecting part communicates with the receiving recess through the expansion passage, and the weir is connected to the covering material in the branch passages on both sides. A crosshead of an extruder, characterized in that the crosshead of an extruder is set at a height such that the liquid can pass through the upper surface of the weir and flow into the annular recess.