JPH0561086B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a two-layer extrusion mold for extrusion molding a two-layer resin pipe in which the core resin and the surface resin are different. It is possible to easily manufacture a two-layer molded pipe made of resin, and also it is possible to firmly adhere the surface resin layer and the core resin layer, and furthermore, the thickness of the surface resin layer can be freely adjusted. We provide extrusion molds.

The present invention will be explained in detail below with reference to Examples. Reference numeral 1 denotes a mold body, which is provided with a space 2 passing through it in the axial direction. A core resin inlet 3 is provided at the rear end of the space 2, and the core resin is fed into the core resin inlet 3 from a screw. space 2
A core 4 is attached to the core 4 by a spider 5, and a core resin extrusion path 6 is formed between the core 4 and the space 2. A heat insulating space 1 is provided on the front outer periphery of the mold body 1.
A surface layer mold 7 is attached to the surface layer mold 7 through a hole 0, and a resin reservoir portion 8 is provided in an annular shape in the circumferential direction of the surface layer mold 7. A surface layer resin inlet 26 is provided at a suitable location on the outer periphery of the surface layer mold 7, and the surface layer resin inlet 26 and the resin reservoir 8 are communicated through a communication pipe 9. Resin inlet 2
6. Surface layer resin is supplied to the resin reservoir 8 via the communication pipe 9. Resin reservoir part 8
A thin-walled cylindrical surface layer resin extrusion path 11 is provided toward the front inner circumferential direction, and an auxiliary resin reservoir portion 12 is provided in the middle of the surface layer resin extrusion path 11. On the outer peripheral side of the resin extrusion path 11 for the surface layer, there is a resin extrusion path 11 for the surface layer.
A flexible piece 11a having a triangular cross section is provided to adjust the interval between the outlets 14 of the surface layer mold 7.
1a, and by changing the screwing amount of the adjusting screw 13, the flexible piece 11a can be bent to adjust the interval between the outlets 14 of the surface resin extrusion path 11. Here, 15 is a heat medium passage through which a heat medium such as oil is passed for temperature control. Reference numeral 16 denotes a vacuum passage provided in the mold body 1, one end of which is connected to the outlet 14 of the surface layer resin extrusion passage 11.
and the outlet 17 of the core resin extrusion path 6, and the other end of the vacuum path 16 is communicated with a vacuum pump. A support bar 18 is provided protruding forward from the front end of the surface layer mold 7, and a support plate 19 is attached to the front end of the support bar 18. A contact plate 20 having a contact hole 24 in the center is disposed between the support plate 19 and the surface layer mold 7, and the support bar 18 can be slid through a slide hole 21 provided on the outer periphery of the contact plate 20. It can be inserted freely. The support bar 18 is provided with a male thread 23, and a contact plate adjustment nut 26 is screwed into the male screw 23 between the support plate 19 and the contact plate 20.
By screwing 5, the distance between the contact plate 20 and the outlet 14 of the surface resin extrusion path 11 can be adjusted. An outsizing die 27 is arranged in front of the contact plate 20.

Next, the operation of the two-layer extrusion mold constructed as described above will be explained. When a core resin such as polyvinyl chloride is supplied from the core resin inlet 3, it is extruded into a cylindrical shape from the outlet 17 through the core resin extrusion path 6.
The contact hole 24 of the contact plate 20 is reached. At this time, if the supply pressure and amount of the core resin from the core resin inlet 3 are changed, the speed at which the core resin is extruded from the outlet 17 will be changed. On the other hand, from the resin inlet 26 for the surface layer, acrylic,
When the surface resin such as AAS resin is supplied, it is extruded into a cylindrical shape from the outlet 14 through the surface resin extrusion path 11 and reaches the adhesion hole 24 of the adhesion plate 20, and the cylindrical surface resin layer is formed. It is brought into close contact with the outer surface of the cylindrical core material resin layer to form a two-layer resin tube, which is sized with an outsizing die 27 to become a product. When the resin layer for the surface layer is brought into close contact with the resin layer for the core material, by evacuating the resin layer through the vacuum passage 16, it is possible to bring the resin layer for the surface layer into close contact with the resin layer for the core material without allowing air to enter between them. If you want to change the thickness of the surface resin layer during extrusion molding as described above, contact plate 2
0 by moving it back and forth using the contact plate adjustment nut 25. At this time, when the contact plate 20 is moved forward, the surface resin layer becomes thinner. In other words, if the adhesion hole 24 of the adhesion plate 20 is located on the extension line of the extrusion direction of the surface resin extrusion path 11 (imaginary line in FIG. 1), the surface resin layer will not bend at the outlet 14 and the inner thickness will be the thickest. Substantially, the outlet area gradually decreases and the wall thickness becomes thinner as the outlet is located further forward than the extension line. In addition, when changing the thickness of the surface resin layer significantly when extrusion is not in progress, use the adjustment screw 13.
This can be done by adjusting the distance between the outlets 14 by adjusting the distance between the outlets 14. Furthermore, by changing the extrusion speed of the core resin while keeping the pressure and supply amount of the surface resin constant, the thickness of the surface resin layer can be changed even if the stretching amount of the surface resin layer is changed. . Furthermore, since the surface layer mold 7 is provided with a resin reservoir 8 and an auxiliary resin reservoir 12, the pressure of the surface layer resin can be made uniform and thin extrusion can be stabilized. Furthermore, the reason why the heat medium is passed through the heat medium passage 15 is to reduce the mutual influence between the core material resin and the surface layer resin, since their temperatures are different, and to maintain each resin at a predetermined temperature. For example, if the core resin is polyvinyl chloride,
At approximately 190℃, if the surface resin is acrylic resin,
The surface resin is kept at a high temperature of approximately 220℃ using a heat medium.

As described above, the present invention includes a cylindrical core resin extrusion path for extruding core resin into a cylindrical shape, and a cylindrical core resin extrusion path provided concentrically on the outer periphery of the core resin extrusion path to extrude surface layer resin into the cylinder. It has a surface layer resin extrusion path that extrudes a cylindrical core resin layer on the outer periphery of the core resin extrusion path. It can be used to extrude a cylindrical surface resin layer and cover it with a core resin layer, and it is easy to manufacture two-layered resin pipes of different types. An adhesion plate is provided in front of the exit of the extrusion path, and adhesion holes are provided in the adhesion plate to allow the surface resin to adhere to the outer peripheral surface of the core resin by sliding the surface resin on the inner surface. Since a hole was made to face the outlet of the resin extrusion path and have approximately the same diameter as this outlet, the core resin layer and the surface resin layer could be passed through the adhesive hole of the adhesive plate to make sliding contact with the adhesive hole. The resin layer for the surface layer can be brought into close contact with the outer peripheral surface of the resin layer for the core material, and the resin layer for the core material and the resin layer for the surface layer can be brought into close contact with each other. Since the adhesion plate with holes is movable back and forth, by moving the adhesion plate back and forth, the position where the surface resin layer adheres to the core resin layer can be changed back and forth, and the thickness of the surface resin layer can be adjusted. can be changed freely, and an adjustment screw is provided at the exit of the surface resin extrusion path to adjust the exit interval, so the adjustment screw can be used to adjust the interval between the exits of the surface resin extrusion path. By doing so, the thickness of the extruded resin for the surface layer can be adjusted.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view of the same resin extrusion path for the surface layer, in which 6 is the resin extrusion path for the core material, and 11 is the resin extrusion path for the surface layer. , 20 is an adhesion plate, and 24 is an adhesion hole.

Claims (1)

[Claims] 1 A cylindrical core resin extrusion path for extruding the core resin into a cylindrical shape, and a cylindrical core resin extrusion path provided concentrically on the outer periphery of this core resin extrusion path to extrude the surface layer resin into the cylindrical core material. A resin extrusion path for the surface layer that extrudes the resin in a cylindrical shape around the outer periphery, an adjustment screw provided at the outlet of the resin extrusion path for the surface layer to adjust the interval between the exits, and a resin extrusion path for the core material and a resin extrusion path for the surface layer. A close contact plate is disposed in front of the outlet of the channel so as to be movable back and forth, and a hole is bored in the close plate to face the outlet of the core resin extrusion channel and have a diameter substantially the same as that of the outlet. 1. A two-layer extrusion mold, characterized in that it is provided with an adhesion hole for bringing a surface layer resin into close contact with an outer circumferential surface of a core resin by slidingly contacting the inner surface of the mold.