Abstract:
A mold equipped with a core having a plurality of columnar distal portions branched at a downstream side in the extrusion direction and arranged on a surface and a die having an aperture surrounding the distal portions as a whole with a distance with respect to the distal portions and used in the case where a softened flexible resin is injected from one end of a resin flow path formed between the core and the die and a pipe material having a plurality of liquid flow paths which are mutually independent formed by the flexible resin is extruded from the other end of the resin flow path, wherein the aperture of the die has a shape in which each part of a plurality of circles each having the same axis as a corresponding one of the distal portions and mutually having the same inner diameter are overlapped and mutually connected, and each of a diameter of a distal portion of the core is lager than or equal to a diameter of a distal portion adjacent to the outer side in the arrangement.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present invention relates to a mold and a manufacturing method, and in particular, relates to a mold used when manufacturing a tube by extrusion molding and a manufacturing method of a tube using the same. 
         [0003]    2. Related Art 
         [0004]    There exist a fluid transfer tube in which a plurality of mutually independent flow paths are integrally formed by a resin material. In JP-B-58-041180, manufacturing of a tube for piping equipped with tube portions of various specifications by a series of processes including extrusion molding is described. Thereby, manufacturing processes can be reduced as compared with the case of manufacturing by processing and building up a given metal tube. Note that the tube for piping described therein includes the one having the strength by which inlet backpressure or the like can be distributed. 
         [0005]    In JP-UM-A-6-000746, a structure in which a plurality of mutually parallel ink tubes are integrated by simultaneous molding. Thereby for example, an ink tube which enables to simultaneously supply a plurality of color materials can be supplied at low cast. 
         [0006]    In JP-B-7-002362, forming an opening having a predetermined bore diameter in a molded product by molding while injecting gas into inside of the molded product in the manufacturing of a pipe material by extrusion molding is described. Thereby size accuracy of the molded product which cannot be fully controlled only by a shape of a mold can be corrected. 
         [0007]    As described above, a multi line tube having a plurality of flow paths can be preferably used in various devices in which a plurality kinds of fluids are simultaneously treated. The multi line tube having continuous flow paths can be manufactured by extrusion molding using a mold equipped with a core which defines inner surface shapes of the flow paths and a die surrounding the outer side of the core with a space with respect to the core. A melt state or softened state material resin is injected into such a mold from one end of a resin flow path formed between the core and the die and a molded product is continuously extruded from an extrusion opening formed at the other end of the resin flow path. Accordingly, a long molded product can be continuously molded by continuously supplying a material resin. 
         [0008]    Incidentally, a plurality of flow paths having the same size are basically arranged in the specification of the multi line tube as described above. Accordingly, a mold having a core and die having the same size in response to each line of the multi line tube is fabricated. However, when a multi line tube is actually manufactured by using such a mold, there is a case that inner diameters of the flow paths mutually formed in the lines are different. In addition, in a particular application, a multi line tube in which flow paths having different diameters are combined may exist. At any rate, a multi line tube having the same inner diameter is a basic, so that a technology for manufacturing a multi line tube in which flow paths mutually having the same inner diameter are combined has been required. 
       SUMMARY 
       [0009]    An advantage of a first aspects of the invention is that it provides a mold equipped with a core having a plurality of columnar distal portions branched at a downstream side in the extrusion direction and arranged on a surface and a die having an aperture surrounding the distal portions as a whole with a distance with respect to the distal portions. The mold is used in the case where a softened flexible resin is injected from one end of a resin flow path formed between the core and the die and a pipe material having a plurality of liquid flow paths which are independent formed by the flexible resin is extruded from the other end of the resin flow path. Here, the aperture of the die has a shape in which each part of a plurality of circles each having the same axis as a corresponding one of the distal portions and mutually having the same inner diameter are overlapped and mutually connected and each of a diameter of a distal portion of the core is lager than or equal to a diameter of a distal portion adjacent to the outer side in the arrangement. Thereby, the difference between inner diameters caused by pressure distribution of material resin can be eliminated and the multi line tube equipped with the plurality flow paths mutually having the same inner diameter can be manufactured. 
         [0010]    Further, as for an embodiment, distal ends of the distal portions of the core extend to the outer side of the die form the aperture of the die in the mold. Thereby inner shapes of each flow path are faithfully reflected to a cross sectional shape of the core and the multi line tube having high size precision in inner surface shape can be manufactured. 
         [0011]    Further, as for another embodiment, the core includes a proximal portion mutually connected with the distal portions in the mold. Thereby, the material resin is evenly supplied and the multi line tube equipped with a plurality of flow paths mutually having the same inner diameter can be manufactured. 
         [0012]    Further, as a second aspect of the invention, there is provided a manufacturing method of a pipe material using a mold equipped with a core having distal portion branched into a plurality of portions at a downstream side in the extrusion direction and arranged on a surface and a die having an aperture surrounding the distal portions as a whole with a distance with respect to the distal portions and injecting a softened flexible resin from one end of a resin flow path formed between the core and the die and extruding a pipe material having a plurality of liquid flow paths formed by the flexible resin from the other end of the resin flow path. Here, the aperture of the die has a shape in which each part of a plurality of circles each having the same axis as a corresponding one of the distal portions and mutually having the same inner diameter are overlapped and mutually connected and each of a diameter of a distal portion of the core is lager than or equal to a diameter of a distal portion adjacent to the outer side in the arrangement. Thereby, the difference between inner diameters caused by pressure distribution of material resin can be eliminated and the multi line tube equipped with the plurality flow paths mutually having the same inner diameter can be manufactured. 
         [0013]    It should be noted here that the summary of the invention described above does not list all necessary characteristics of the invention and a sub-combination of these characteristics groups may also be an invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
           [0015]      FIG. 1  is a perspective view showing a shape of a multi line tube  100  extrusion-molded by a mold  300  according to an embodiment. 
           [0016]      FIG. 2  is a diagram schematically showing a structure of an extrusion molding equipment  200  for manufacturing the multi line tube  100  shown in  FIG. 1 . 
           [0017]      FIG. 3  is a perspective view separately showing a shape of a core plate  310  of the mold  300 . 
           [0018]      FIG. 4  is a perspective view separately showing a shape of a die plate  320  of the mold  300 . 
           [0019]      FIG. 5  is a perspective view showing a state in which the above described core plate  310  and the die plate  320  are built up. 
           [0020]      FIG. 6  is a perspective view separately showing a shape of lip plate  330  of the mold  300 . 
           [0021]      FIG. 7  is a perspective view showing a structure of the mold  300  with which the lip plate  330  is combined. 
           [0022]      FIG. 8  is a diagram showing a shape of a distal portion  340  of a core at an extrusion opening  334  of the mold  300 . 
           [0023]      FIG. 9  is a diagram showing a shape of a distal portion  340  of a core at the extrusion opening  334  of the mold  300  in another embodiment. 
       
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0024]    Hereinafter, the invention will be described through embodiments of the invention. However, the embodiments described below do not restrict the invention according to the claims. Further, it is not necessary that all of the combinations of characteristics illustrated in the embodiments are essential in the means to be solved by the invention. 
         [0025]      FIG. 1  is a diagram showing an appearance of a multi line tube  100  manufactured by extrusion molding by using a mold  300  according to an embodiment. As shown in  FIG. 1 , the multi line tube  100  is formed by a resin molded product  120  integrally forming a plurality of parallel liquid flow paths  110  which are mutually independent. Each of the liquid flow paths  110  communicates in the longitudinal direction of the multi line tube  100  and enables to individually distribute fluid such as liquid, air or the like. Such a multi line tube  100  can be preferably used for communicating an ink cartridge and a recording head, for example, in an ink jet system recording apparatus equipped with a fixed type ink cartridge and a recording head which reciprocates on a recorded object. In this case, ink having mutually different color flows in each of the liquid flow paths  110 . 
         [0026]    Note that such a multi line tube  100  can be manufactured by extrusion molding of, for example, a resin material such as polypropylene (PP), polyethylene (PE), olefin series thermal plasticity elastomer (TPE), styrene series TPE, polyamide series TPE, urethane series TPE, or the like. Further, the multi line tube  100  can be constructed in a multi layer manner by combining a plurality of materials depending on type of fluid to be distributed. 
         [0027]      FIG. 2  is a diagram schematically showing a structure of an extrusion molding equipment  200  for manufacturing the multi line tube  100  shown in  FIG. 1  by extrusion molding. As shown in  FIG. 2 , the extrusion molding equipment  200  includes a hopper  210  for supplying a resin material into the mold  300  described below. The resin material supplied into the mold  300  in a molten state from the hopper  210  is extruded from the mold  300  as the multi line tube  100 , and then, routed through a sizing plate  220  which regulates size and a chiller  230  disposed immediate aftermath of the sizing plate  220  and picked up by a pick up device  240 . Further, the picked up resin material is cut to a predetermined length by a cutting machine  250 , thus making a product. 
         [0028]    Here, the mold  300  is formed by combining a core plate  310  having a core portion which defines an inside shape of the multi line tube  100  to be extruded, a die plate  320  forming a resin flow path  301  by surrounding a circumference of the core portion  314  laminated on the core plate  310 , and a lip plate  330  disposed on the termination of the mold  300  and defining an outer shape of the multi line tube  100 . 
         [0029]      FIG. 3  is a perspective view separately showing the core plate  310  forming the mold  300  used in the above described extrusion molding equipment  200 . As shown in  FIG. 3 , the core plate  310  includes a rectangular flange portion  312  having the same plane size as an outer shape of the mold  300  and a core portion  314  rising at approximately the center of the flange portion  312 . 
         [0030]    The flange portion  312  includes a fastening bolt opening  311  through which a fastening bolt is inserted when the core plate  310  is fastened with the die plate  320  and the lip plate  330  described below. Further, a cutout portion  313  into which a tool can be inserted when disintegrating after the mold  300  is once built up is also formed. 
         [0031]    The core potion  314  includes a single proximal portion  316  and a plurality of distal portions  340  branched to be formed at the upper end of the proximal portion  316 . Further, a resin guiding groove  317  for guiding a melted resin onto the surface of the core portion  314  is formed on the flange portion  312  and around the proximal portion  316 . The resin guiding groove  317  is communicated with the hopper  210  through an injection opening  315 . 
         [0032]      FIG. 4  is a perspective view separately showing a shape of the die plate  320 . As show in  FIG. 4 , the die plate  320  includes a building frame  322  of a cube as a whole. A fastening bolt opening  321  through which a fastening bolt is inserted when building up as the mold  300  and a cutout portion  323  into which a tool is inserted when disintegrating are formed in the die plate  320 . Further, a through opening  324  is formed at the center of the die plate  320 . 
         [0033]    In  FIG. 4 , only an aperture of the through opening  324  at upper end side can be seen. However, the through opening  324  is formed through the whole thickness of the die plate  320 . In addition, the inner diameter thereof is enlarged toward downward and has an inner space one size larger than the core portion  314  of the core plate  310 . 
         [0034]      FIG. 5  shows a state where the die plate  320  shown in  FIG. 4  is combined with the core plate  310  shown in  FIG. 3 . As shown in  FIG. 5 , the flange portion  312  of the core plate  310  and the building frame  322  of the die plate  320  have mutually the same plane size, so that the core plate  310  and the die plate  320  are combined to be a one cube as a whole. In addition, the distal portion  340  of the core portion  314  extends on the upper side than the upper surface of the die plate  320  through the through opening  324 . 
         [0035]      FIG. 6  is a perspective view separately showing a shape of the lip plate  330  of the mold  300 . As shown in  FIG. 6 , the lip plate  330  is a rectangle plate  332  having the same plane size as the core plate  310  and the die plate  320  as a whole and has an extrusion opening  334  from which a molded product is extruded at the center. An inner surface shape of the extrusion opening  334  has a similar shape as a manufactured molded product, that is, an outer shape of the multi line tube  100  in the embodiment. In addition, the lip plate  330  includes a fastening bolt opening  331  which is engaged with the fastening bolt opening  321  of the die plate  320 . 
         [0036]      FIG. 7  is a perspective view showing a state in which the lip plate  330  shown in  FIG. 6  is further combined with the combined body shown in  FIG. 5 . As shown in  FIG. 7 , the core plate  310 , the die plate  320 , and the lip plate  330  are mutually laminated and the cubic mold  300  as a whole are formed. In addition, the distal portion  340  of the core potion  314  is slightly projected from the extrusion opening  334  of the lip plate  330 . Note that the core plate  310 , die plate  320 , and the lip plate  330  are integrated by the fastening bolt inserted in the fastening bolt openings  311 ,  321  and  331  although the fastening bolt is omitted in  FIG. 7 . 
         [0037]      FIG. 8  is a diagram showing a shape of the distal portion  340  of the core in the inner portion of the extrusion opening  334  of the mold  300 . Note that like reference numerals are used to denote like elements in  FIG. 7  and the repeated descriptions will be omitted. 
         [0038]    As shown in  FIG. 8 , the resin flow path  301  is formed between the surface of the core portion  314  and an inner surface of the die plate  320  in the inner portion of the mold  300 . The extrusion opening  334  is a termination of the resin flow path  301  and an outer shape of the extruded resin molded product  120  follows the inner shape of the extrusion opening  334 . 
         [0039]    On the other hand, cross sectional shapes of the liquid flow paths  110  formed in the inner portion of the resin molded product  120  extruded from the extrusion opening  334  follow the shape of the distal portion  340  of the core portion  314 . In this regard, when a material resin particularly used in molding has elasticity, there is a case that the size of the distal portion  340  of the core portion  314  and the inner diameter of the liquid flow paths  110  formed in the resin molded product  120  are different because the molding pressure applied to the resin material during molding is released after the molding. 
         [0040]    On the contrary, in the mold  300  as shown in  FIG. 8 , the outer diameter of a pair of the distal portions  341  and  344  positioned at outer side is reduced than that of the distal portions  342  and  343  positioned at inner side. Thereby when the resin molded product  120  is released from molding pressure, the inner diameter of the liquid flow paths  110  corresponding to the both ends of the distal portions  341  and  344  becomes lager. As a result, the inner diameters of the liquid flow paths  110  corresponding to the distal portions  341 ,  342 ,  343 ,  344  become mutually equal. 
         [0041]    To be more specific, the mold  300  was manufactured in which all of the inner diameter of each line of the extrusion opening  334  should be 5.3 mm, the outer diameter of the distal portions  342  and  343  of the core portion  314  positioned at inner side should be 1.9 mm, and the outer diameter of the distal portions  341  and  344  positioned at outer side should be 1.7 mm. Then, the resin molded product  120  extruded from the extrusion opening  334  was regulated in the sizing plate  220  shown in  FIG. 2  and the multi line tube  100  in which outer diameter of each line becomes 4.3 mm was obtained. At this time, all of the inner diameters of the four liquid flow paths  110  were the same 1.6 mm. 
         [0042]      FIG. 9  is a diagram showing a shape of the mold  300  preferably used in the case where another multi line tube  100  which is different in specifications is manufactured viewed from the same view point as in  FIG. 8 . The mold  300  shown in  FIG. 9  is used when a multi line tube  100  having nine liquid flow paths  110  is manufactured. Here, three classes of diameters are mixed in the distal portion  340  of the core portion  314 . That is, the pare of the distal portions  341  and  349  positioned at outermost sides has the most small diameter D 3  and three distal portions  344 ,  345  and  346  positioned at the center have the most large diameter D 1 . Moreover, each two distal portions  342 ,  343  and  347 ,  348  positioned therebetween have an intermediate diameter D 2 . In such a manner, the distal portions  340  of the core portion  314  are formed so that a diameter of a distal portion is larger than or equal to a diameter of a distal portion arranged at the outer side. As a result, the multi line tube  100  equipped with liquid flow paths  110  having even inner diameters can be manufactured. 
         [0043]    The invention is described above by using the embodiments. However, the technical scope of the invention is not limited to the scope described in the above embodiment. It is obvious for the person skilled in the art that various modifications and changes can be made in the above embodiments. It is obvious that the embodiment in which such modifications and changes are made is also included in the technical scope of the invention from the description of the claims.