JP3514737B2 - Multilayer circular die for extrusion equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer circular die of an extrusion molding apparatus for molding a multilayer pipe made of different kinds of resins. 2. Description of the Related Art A conventional multilayer die of an extrusion molding apparatus is disclosed in Japanese Utility Model Registration No. 2569383. According to the above publication, a multilayer circular die of an extrusion molding apparatus has a die body having a die hole opening forward in a resin extrusion direction, a die body extending in a front-rear direction, and being inserted into the die hole. A mandrel to be fitted, an annular space formed between each rear side of the inner peripheral surface of the die hole and the outer peripheral surface of the mandrel, a multilayer molded cylinder fitted to the annular space, and the die Between the rear side of the inner peripheral surface of the hole and the outer peripheral surface of the multilayer molding cylinder, and between the rear side of the outer peripheral surface of the mandrel and the inner peripheral surface of the multilayer molding cylinder, and between these molding cylinders. A plurality of cylindrical upstream-side gaps formed between them, and a cylindrical downstream gap formed between each front side of the inner peripheral surface of the die hole and the outer peripheral surface of the mandrel, Each upstream space is communicated with the downstream space. Further, an intermediate space is formed between the inner peripheral surface on the rear side of the die hole and the outer peripheral surface on the front side of each of the molding cylinders facing the inner peripheral surface. Of these, the front end of the radially inner upstream gap is opened more forward than the front end of the upstream gap outside the radially inner gap. The extrusion molding apparatus is provided with a plurality of extruders capable of extruding the resin melted by heating toward the rear end of each of the upstream gaps. When a product having a multilayer tube shape is to be molded by the above-mentioned extrusion molding apparatus, first, a desired resin is extruded and supplied toward each upstream side gap by each of the above extruders. Then, these resins flow forward through the respective upstream gaps, and at this time, a tubular intermediate molded product corresponding to the respective upstream gaps is formed. Further, with the extrusion of the resin by each of the extruders, when each of the intermediate molded products reaches the midway space, the intermediate molded products flow forward in the midway space, and sequentially have the same shaft. Superimposed on each other in the center, another intermediate molded article having a multilayer tube shape corresponding to the intermediate space is formed. Further, as the resin is extruded by each of the extruders, the other intermediate molded product is allowed to pass from the midway space to the downstream space, and at this time, the shape of the other intermediate molded product is adjusted. It is formed into a desired multilayer pipe shape, which is extruded forward of the die, and is made into a product through a water cooling device and a take-off machine. [0008] The above-mentioned prior art has the following problems. That is, as described above, since the multi-layered molding body is inserted between the inner peripheral surface of the die hole and the outer peripheral surface of the mandrel, the intermediate cavity is formed at the front side. The shape is a frustoconical cylinder that tapers toward. Therefore, when the product is molded as described above, the diameter of the other intermediate molded product is shrunk as the intermediate product flows forward in the intermediate space, and the diameter is greatly changed. . Here, the types of resin of the respective intermediate molded articles constituting the other intermediate molded articles are different from each other. Particularly, when the respective viscosities are different from each other, the circumferential direction of each intermediate molded article is different. Tend to flow non-uniformly in the radial direction due to the variation in the diameter of the other intermediate molded product, and as a result, the thickness of each part in the circumferential direction of each intermediate molded product in the other intermediate molded product The dimensions may be non-uniform. That is, when trying to obtain a product in the form of a multilayer tube, the thickness of each part in the circumferential direction of each tube constituting the product may be insufficient in view of desired accuracy. The present invention has been made in view of the above circumstances. When an extrusion molding apparatus is to be used to obtain a product having a multilayer tube shape, the dimensions of each tube constituting the product are desired. It is an object of the present invention to be able to achieve the accuracy of Another object of the present invention is to make it easy to assemble an extruder even in the case described above. [0014] A multilayer circular die of an extrusion molding apparatus according to the present invention for solving the above-mentioned problems is as follows. According to the first aspect of the present invention, there is provided a die body 8 having a die hole 7 opening forward in the extrusion direction of the resin 3.
And a mandrel 11 extending in the front-rear direction and fitted into the die hole 7, and an annular space 1 formed between respective rear sides of an inner peripheral surface of the die hole 7 and an outer peripheral surface of the mandrel 11.
2 and a multi-layer molded cylinder 1 fitted into the annular space 12
4, between the rear side of the inner peripheral surface of the die hole 7 and the outer peripheral surface of the multilayer molding cylinder 14, and / or the rear side of the outer peripheral surface of the mandrel 11 and the inner periphery of the multilayer molding cylinder 14. A plurality of cylindrical upstream-side voids 17 formed between the surfaces and / or between the respective formed cylindrical bodies 14, and respective front portions of the inner peripheral surface of the die hole 7 and the outer peripheral surface of the mandrel 11. And a cylindrical circular die of an extruder in which each of the upstream cavities 17 is communicated with the downstream cavities 18. The outer periphery of the mandrel 11 The rear side of the face,
A cylindrical intermediate portion 19 is formed between the inner peripheral surface of each of the molding cylinders 14 facing the rear side of the outer peripheral surface, and the outermost one of the upstream-side voids 17 in the radial direction is formed. The front end of the side gap 17 (A) is connected to the upstream side gap 17
A front end portion of (B) is opened more on the front side relative to the intermediate portion gap 19, [0017] upper Symbol die hole 7, the mandrel 11, and the molded tubular body 14 and disposed on the same axis 9 The die hole 7
The rear side of the inner peripheral surface and the inner and outer peripheral surfaces of each of the molding cylinders 14 each have a truncated conical shape tapered forward, and the rear end sides of the inner and outer peripheral surfaces facing each other are mutually connected. by surface bonding, to the said mandrel 11 and the shaped cylindrical body 14 is supported to the die body 8, [0018] among the above SL each forming cylindrical body 14, shaped cylindrical body 14 more outward in the radial direction (a) The vertical angle .theta.1 at the front end of each of them is larger than the vertical angle .theta.2 of the inner cylindrical body 14 (B). Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes an extrusion molding apparatus.
The extrusion molding apparatus 1 includes a multilayer circular die 2 and a different kind of thermoplastic resin 3 heated and melted toward the die 2.
And a screw-type or positive-displacement type extruder 4 which can be extruded by pressurizing. This extruder 4
The resin 3 extruded from the die 2 is formed into a multilayer tube shape by passing through the die 2, and is continuously extruded from the die 2, and is formed into a product 5 through a water cooling device and a take-off machine (not shown). In the figure, the arrow Fr indicates the resin 3 by the die 2.
2 shows the front in the pushing direction of the. The type of the resin 3 extruded by each of the extruders 4 is a viscosity, a component,
They differ from each other in color and the like. The die 2 has a die body 8 having a die hole 7 opening forward in the extrusion direction of the resin 3, and the die hole 7 has an axial center 9 extending in the front-rear direction. 8 penetrates back and forth. The front side of the inner peripheral surface of the die hole 7 has a circular cross-section at each part in the axial direction, has a substantially uniform diameter, and the rear side has a truncated cone shape tapered forward. A mandrel 11 is provided on the shaft center 9 and extends in the front-rear direction (axial direction) and is fitted into the die hole 7. The cross section of the front part of the mandrel 11 in the front-rear direction is circular. , And have substantially uniform diameters. Between the inner peripheral surface of the die hole 7 and the outer peripheral surface of the mandrel 11, an annular space 12 in the shape of a truncated cone that is tapered forward is formed forward. On the shaft center 9, there are provided multilayer molding cylinders 14 fitted into the annular space 12, and each of the molding cylinders 14 has a shape of a truncated cone that is tapered forward, and They are fitted and laminated in the radial direction. The rear side of the inner peripheral surface of the die hole 7, the rear side of the outer peripheral surface of the mandrel 11,
Each of the outer peripheral surfaces is formed in a truncated cone shape tapered forward, and in the die hole 7, the mandrel 11, and each forming cylinder 14, the respective rear end sides of the inner and outer peripheral surfaces facing each other. The mandrel 11 and each forming cylinder 14 are detachably fastened to the die body 8b side by fasteners 15 on the entire surface in the circumferential direction. As a result, the mandrel 11 and each of the molding cylinders 14 are detachably supported at the rear end side of the die body 8 in a cantilever manner, and the front sides thereof are free ends. When the fasteners 15 are loosened, the mandrel 11 and the molding cylinders 14 can be disassembled with respect to the die body 8. Between the rear side of the inner peripheral surface of the die hole 7 and the outer peripheral surface of the multilayer molding cylinder 14, between each of the molding cylinders 14, and the rear side of the outer peripheral surface of the mandrel 11. And between the inner peripheral surface of the multilayer molding cylinder 14
A plurality of upstream-side voids 17 each having a tapered frustoconical shape tapering toward the front are formed. These upstream gaps 17 are stacked in the radial direction, and each front end is opened forward. Between the inner peripheral surface of the die hole 7 and the outer peripheral surface of the mandrel 11, there is a circular cylindrical shape whose cross section in the front-rear direction is circular and whose diameters are almost uniform. A downstream gap 18 is formed. The front end of each of the upstream gaps 17 communicates with the rear end of the downstream gap 18, and the front end of the downstream gap 18 is opened forward. A rear side of the outer peripheral surface of the mandrel 11;
Between the inner peripheral surface of each of the molding cylinders 14 facing the rear side of the outer peripheral surface, an intermediate space 19 having a circular cylindrical shape whose cross sections in the front-rear direction are circular and whose diameters are substantially uniform to each other is formed. The intermediate gap 19 is located on the same axis 9 as the downstream gap 18 and has substantially the same diameter.
They are communicated integrally with each other. Then, of the upstream gaps 17, the upstream gap 1 that is more outward in the radial direction is used.
7 (e.g., (A) is attached), and the front end of the upstream space 17 (e.g., (B) added) is located forward of the front end of the midway space 19. It is open. The apex angle θ1 of the imaginary vertex at the front end of the outermost forming cylinder 14 (for example, the one described in (A)) in the radial direction of each of the above-described forming cylinders 14 is set to the inner side. Of the imaginary apex at the front end of each of the molded cylinders 14 (for example, those of (B)) is larger than the apex angle θ2. Is thicker than the front side. A heater 22 is provided for heating the die 2 appropriately and holding the resin 3 in the die 2 in a molten state. According to the above configuration, a cylindrical midway gap 19 is formed between the rear side of the outer peripheral surface of the mandrel 11 and the inner peripheral surface of each of the molding cylinders 14 facing the rear side of the outer peripheral surface. The front end of the upstream gap 17 (A), which is radially outer, of the upstream gaps 17 is formed in the intermediate gap with respect to the front end of the upstream gap 17 (B). 1
9 are opened to the front side. For this reason, when the product 5 having a multilayer tube shape is to be molded by the extrusion molding apparatus 1, first,
The respective extruders 4 extrude and supply a desired resin 3 toward the respective upstream gaps 17. Then, these resins 3 flow forward through the upstream gaps 17, and at this time,
A tube-shaped intermediate molded product 2 corresponding to each upstream space 17 described above.
4 is formed. Further, as the resin 3 is extruded by each of the extruders 4, each of the intermediate molded products 24 is displaced from the intermediate space 1
9, the intermediate moldings 24 flow forward in the halfway gaps 19, and the same axial center 9 is sequentially formed.
On top of each other, another intermediate molded product 25 having a multilayer tube shape corresponding to the intermediate space 19 is formed. Further, with the extrusion of the resin 3 by each of the extruders 4, the other intermediate molded product 25 is passed from the midway gap 19 to the downstream gap 18, and at this time,
The shape of the other intermediate molded product 25 is adjusted to a desired multilayer tube shape, which is extruded to the front of the die 2 and formed into a product 5 via a water cooling device and a take-off machine. Here, as described above, the middle space 19
Are formed along the outer peripheral surface of the mandrel 11, and the cross-sectional shape of the mandrel 11 is substantially uniform at each part in the front-rear direction. Are also substantially uniform. For this reason, as described above, when the product 5 is molded, the intermediate molded products 24 molded in the upstream gaps 17 are successively overlapped with each other in the intermediate gap 19 to form another intermediate molded product. When the article 25 is molded, it is possible to prevent the diameter dimension of the other intermediate molded article 25 from being largely fluctuated, such as being shrunk. Therefore, since the diameter of the other intermediate molded product 25 is not largely changed, the other intermediate molded product 2 is not changed.
Even if the material of the resin 3 of each of the intermediate molded products 24 that constitutes 5 is different from each other, it is possible to prevent the thickness dimensions of the respective portions in the circumferential direction of each of the intermediate molded products 24 from being uneven, that is, The dimensions of each tube constituting the multilayer tube-shaped product 5 can be adjusted to a desired accuracy. As described above, the die hole 7, the mandrel 11, and each of the molding cylinders 14 are disposed on the same axis 9, and the rear side of the inner peripheral surface of the die hole 7 The inner and outer peripheral surfaces of the molded cylindrical body 14 are each formed into a truncated conical shape tapered forward, and the respective rear end portions of the inner and outer peripheral surfaces facing each other are surface-bonded to each other to form the mandrel 11 and the respective moldings. The cylindrical body 14 and the die body 8 are supported. Therefore, when the die body 8, the mandrel 11, and each of the molding cylinders 14, which are the components of the extrusion molding apparatus 1, are disassembled and subjected to maintenance and inspection, etc., the assembly work is required. First, the mandrel 11 and each of the molding cylinders 14 are fitted into the die hole 7 of the die body 8 in a predetermined order, and the rear end portions of the inner and outer peripheral surfaces facing each other are fitted. The sides are surface bonded to each other. Then, by this fitting, these 7, 11, and 14 are automatically assembled on the same shaft center 9. Therefore, in the above assembling work, since the respective component parts are automatically centered, the assembling work can be facilitated. Further, as described above, the apex angle θ1 of the front end of the radially outer molding cylinder 14 (A) of each molding cylinder 14 is set to the molding cylinder 14 (B ) Are each larger than the apex angle θ2. For this reason, each of the molded cylinders 14 has a larger thickness at the rear portion than at the front portion. Here, as described above, the die hole 7, the mandrel 11, and each of the molding cylinders 14 are cantilevered by the die body 8 because their rear ends are surface-bonded to each other and are cantilevered. When the thickness of the rear side of each molding cylinder 14 is increased, the mandrel 1 with respect to the die body 8 is increased.
1, and the support of each molding cylinder 14 is further strengthened. Therefore, even when the molten resin 3 pressurized in each of the upstream gaps 17 passes while applying an external force to each of the molding cylinders 14 during molding of the product 5, each of the upstream gaps 17 is not affected. Is maintained with high precision, and therefore, the dimensions of each tube constituting the multilayer tube-shaped product 5 can be more reliably made to the desired accuracy. Although the above description is based on the illustrated example, the die hole 7
The axis 9 may extend horizontally, vertically, or obliquely upward. Further, an upstream gap 17 between the inner peripheral surface of the die hole 7 and the outer peripheral surface of the multilayer molding cylinder 14, and an upstream gap 17 between the outer peripheral surface of the mandrel 11 and the inner peripheral surface of the multilayer molding cylinder 14. The side gap 17 may not be provided. The effects of the present invention are as follows. According to the first aspect of the present invention, there is provided a die body having a die hole opening forward in the resin extrusion direction, a mandrel extending in the front-rear direction and fitted into the die hole,
An annular space formed between each rear side of the inner peripheral surface of the die hole and the outer peripheral surface of the mandrel, a multilayer molded cylinder fitted into the annular space, and an inner peripheral surface of the die hole. Between the rear side and the outer peripheral surface of the multilayer molding cylinder and / or between the rear side of the outer peripheral surface of the mandrel and the inner peripheral surface of the multilayer molding cylinder and / or between these molding cylinders A plurality of molded cylindrical upstream-side gaps, and a cylindrical downstream gap formed between each front side of the inner peripheral surface of the die hole and the outer peripheral surface of the mandrel, In a multilayer circular die of an extrusion molding apparatus in which an upstream space communicates with a downstream space, a rear part of an outer peripheral surface of the mandrel and an inner peripheral part of each of the molding cylinders facing the rear part of the outer peripheral surface are provided. Between the upper surface and the upper surface side Among the gaps, the front end of the radially outer upstream gap is opened more forward with respect to the midway gap than the front end of the inner upstream gap. For this reason, when a product having a multilayer tube shape is to be formed by the extrusion molding apparatus, first, a desired resin is extruded and supplied toward each upstream side gap by each of the extruders. Then, these resins flow forward through the respective upstream gaps, and at this time, a tubular intermediate molded product corresponding to the respective upstream gaps is formed. Further, when each of the intermediate molded products reaches the midway gap along with the extrusion of the resin by each of the extruders, the intermediate molded products flow forward in the midway space while sequentially passing through them. Another intermediate molded product having a multilayer tube shape corresponding to the midway space is formed by being overlapped on the same axis. Further, as the resin is extruded by each of the extruders, the other intermediate molded product is allowed to pass from the midway space to the downstream space, and at this time, the shape of the other intermediate molded product is adjusted. It is formed into a desired multilayer pipe shape, which is extruded forward of the die, and is made into a product through a water cooling device and a take-off machine. Here, as described above, the midway gap is:
It is molded along the outer peripheral surface of the mandrel, and since the cross-sectional shape of the middle part of the mandrel is made substantially uniform at each part in the front-rear direction, each part in the front-rear direction of the halfway gap is used. Can be made substantially uniform. For this reason, as described above, when molding a product, each of the intermediate molded products molded in each of the upstream-side voids is
When another intermediate molded product is formed by being sequentially superimposed on each other in the midway space, it is possible to prevent the diameter dimension of the other intermediate molded product from being largely fluctuated, such as being shrunk. Therefore, since the diameter of the other intermediate molded products cannot be largely changed, even if the resin material of each intermediate molded product constituting the other intermediate molded products is different from each other, each of these intermediate molded products is different. It is possible to prevent the thickness dimension of each part in the circumferential direction of the molded article from being non-uniform, that is, it is possible to make the dimensions of each pipe constituting the multilayer pipe-shaped product to a desired accuracy. [0056] Also, the die hole, disposed mandrel, and the molded tubular body on the same axis, and the rear side of the inner circumferential surface of the die hole, among the above molded cylinder, and the outer peripheral surface Each is formed to have a frusto-conical shape tapered toward the front, and the inner and outer peripheral surfaces facing each other are surface-joined to each other at the rear end side, and the mandrel and each molded cylindrical body are supported by the die body. is there. Therefore, when assembling the die body, the mandrel, and the molding cylinders, which are the components of the extrusion molding apparatus, after disassembling and performing maintenance and inspection, etc., first, For the die hole of the die body,
The mandrel and the molding cylinders are fitted in a predetermined order, and the rear end portions of the inner and outer peripheral surfaces facing each other are surface-joined to each other. Then, these fittings automatically assemble them on the same axis. Therefore, in the above assembling work, since the respective components are automatically centered, the assembling work can be facilitated. [0059] Among the above molded cylindrical body, the apex angle of the front end of the more outer molded tubular body in the radial direction, than this is made larger than each than the top angle of the inner molded tubular body. Therefore, each of the above-mentioned molded cylinders can be made thicker on the rear side than on the front side. Here, as described above, the die hole, the mandrel, and each molding cylinder are surface-joined at their rear ends and are cantilevered by the die body. When the thickness of the rear part is increased, the support of the mandrel and each molding cylinder with respect to the die main body is further strengthened. Therefore, even when the molten resin pressurized in each of the upstream gaps passes while applying an external force to each of the molding cylinders during the molding of the product, the size of each of the upstream gaps is not limited to the precision. Therefore, the dimensions of each pipe constituting the multilayer pipe-shaped product can be more reliably and accurately adjusted to a desired level.

[Brief description of the drawings] FIG. 1 is an overall side sectional view of an extrusion molding apparatus. FIG. 2 is an enlarged sectional view taken along line 2-2 of FIG. [Explanation of symbols] 1 Extrusion equipment 2 dies 3 resin 4 Extruder 5 Products 7 Die hole 8 die body 9 axis center 11 Mandrel 12 Annular space 14 Molded cylinder 17 Upstream air gap 18 Downstream gap 19 Midway void 24 Intermediate molded products 25 Other intermediate molded products θ1 apex angle θ2 apex angle

Claims (1)

(57) [Claim 1] A die body having a die hole opening forward in the resin extrusion direction, a mandrel extending in the front-rear direction and fitted into the die hole, An annular space formed between each rear side of the inner peripheral surface of the die hole and the outer peripheral surface of the mandrel, a multilayer molded cylinder fitted into the annular space, and an inner peripheral surface of the die hole. Between the rear side and the outer peripheral surface of the multilayer molding cylinder and / or between the rear side of the outer peripheral surface of the mandrel and the inner peripheral surface of the multilayer molding cylinder and / or between these molding cylinders A plurality of molded cylindrical upstream-side gaps, and a cylindrical downstream gap formed between each front side of the inner peripheral surface of the die hole and the outer peripheral surface of the mandrel, Multi-layer circular die of extrusion molding equipment with upstream gap communicating with downstream gap And forming a cylindrical intermediate portion between the rear side of the outer peripheral surface of the mandrel and the inner peripheral surface of each of the molding cylinders facing the rear side of the outer peripheral surface. of more the front end portion of the outer upstream side gap, which is opened more on the front side relative to the middle portion gap than the front end of the inner upstream gap, upper Symbol die hole, a mandrel, and each forming in the radial direction The cylindrical body is disposed on the same axis, and the rear side of the inner peripheral surface of the die hole and the outer peripheral surface of each of the molded cylindrical bodies are each formed into a truncated conical shape that is tapered toward the front. facing the above one another to a surface bonded to the rear end side of the outer peripheral surface, and said mandrel and each of the forming tube body is supported on the die body, among the above SL each forming cylinder, more outward in the radial direction The vertical angle of the front end of the molded cylinder of Multilayer Sakyuradai of press-molded device Kikushi.