Patent Abstract:
An extrusion molding apparatus for a product having a wood pattern and an extrusion molding method are disclosed, in which a second synthetic resin containing a wood powder of 80˜120 meshes at a predetermined ratio is fed to a die through a second extruder and then is coated on a surface of the product, thereby providing an esthetic surface and an improved durability. The extrusion molding apparatus is designed to successively produce a product having a wood pattern with a predetermined sectional shape by feeding a thermoplastic synthetic resin to an extruder and extruding the product through a die installed at an outlet of the extruder, wherein a second inlet is formed at one side of the die to fit a second synthetic resin thereinto, a second extruder which feeds the second synthetic resin is connected to the second inlet, and a second passage communicated with the second inlet of the die is formed to communicate with an original synthetic resin passage formed in the die, thereby coating the second synthetic resin on a surface of the product extruded from the die.

Full Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to an extrusion molding apparatus and an extrusion molding method, and more particularly to an extrusion molding apparatus for a product having a wood pattern and an extrusion molding method thereof, in which a second synthetic resin containing a wood powder of 80˜120 meshes at a predetermined ratio is fed to a die through a second extruder and then is coated on a surface of the product extruded from the die, thereby obtaining an esthetic surface and improving durability.  
           [0003]    2. Discussion of the Related Art  
           [0004]    Generally, extrusion molding is to successively manufacture products, such as pipes, rods, sheets, films, fibers, and coating cables, by extruding a thermoplastic synthetic resin, which has been heated and softened, from an extrusion die using an extruder.  
           [0005]    A conventional extrusion molding apparatus is configured to wind or cut the product by placing a pellet shaped thermoplastic synthetic resin in a hopper, softening it with a screw in a heating cylinder, extruding it from the die, and cooling it. The conventional extrusion molding apparatus is characterized in that a softening resin is successively extruded with a screw. The products having various sections may be made depending on shapes of holes of an extrusion die at an outlet of an extruder. Such extrusion molding is widely used in accordance with the development of polymer compounds such as synthetic resin and has become a basis of mass production.  
           [0006]    Among the products based on the above-described extrusion molding, there are the products having a constant section, such as a window frame and a doorframe. These products are on a high-grade trend to give an effect of raw lumber. If the product is manufactured using a general synthetic resin, it is likely that the product having a single color is manufactured. Therefore, the product coated with a film, such as sheet with a wood pattern, wood, and paper, to give an effect of raw lumber is recently coming out in the market.  
           [0007]    However, the product coated with such a film has several problems. Since the film is made of a material and characteristics different from those of the product, the film and the product respectively have different shrinkage depending on temperature changes. In this case, a problem arises in that it is likely to take the film, such as sheet, wood, and paper, off the product as time passes.  
         SUMMARY OF THE INVENTION  
         [0008]    Accordingly, the present invention is directed to an extrusion molding apparatus for a product having a wood pattern and an extrusion molding method that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.  
           [0009]    An object of the present invention is to provide an extrusion molding apparatus for a product having a wood pattern and an extrusion molding method, in which a second synthetic resin containing a wood powder of 80˜120 meshes is coated on a surface of the product at different ratios.  
           [0010]    Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the scheme particularly pointed out in the written description and claims hereof as well as the appended drawings.  
           [0011]    To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, in an extrusion molding apparatus for successively producing a product having a wood pattern with a predetermined sectional shape by feeding a thermoplastic synthetic resin to an extruder and extruding the product through a die installed at an outlet of the extruder, it is characterized in that a second inlet is formed at one side of the die to fit a second synthetic resin thereinto, a second extruder which feeds the second synthetic resin is connected to the second inlet, and a second passage communicated with the second inlet of the die is formed to communicate with an original synthetic resin passage formed in the die, thereby coating the second synthetic resin on a surface of the product extruded from the die.  
           [0012]    In another aspect of the present invention, an extrusion molding method for successively producing a product having a wood pattern with a predetermined sectional shape by feeding a thermoplastic synthetic resin to an extruder and extruding the product through a die installed at an outlet of the extruder, the extrusion molding method includes the steps of: forming a second passage in a synthetic resin passage in the die to communicate with the synthetic resin passage; and connecting a second extruder to the second passage so that the second synthetic resin is coated on a surface of the product extruded from the die.  
           [0013]    In other aspect of the present invention, in an extrusion molding die for a product having a wood pattern, provided with a thermoplastic synthetic resin and a synthetic resin passage, the thermoplastic synthetic resin being installed at an outlet of an extruder so that it is to be fed to the extruder and then extruded in the product having a predetermined sectional shape such as the synthetic resin passage, a second inlet is formed at one side of the die to fed a second synthetic resin thereto, and the second inlet is formed to communicate with a second passage communicated with the synthetic resin passage of the die so that the second synthetic resin is coated on a surface of the product extruded from the die.  
           [0014]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
       
    
    
     BRIEF DESCRIPTION OF THE ATTACHED DRAWINGS  
       [0015]    The invention will be described in detail with reference to the following drawings in which like reference numerals refer to like elements wherein:  
         [0016]    [0016]FIG. 1 is a perspective view of a product manufactured by an extrusion molding method according to the present invention;  
         [0017]    [0017]FIG. 2 is a perspective view of an extrusion molding apparatus according to the present invention;  
         [0018]    [0018]FIG. 3 is a perspective view of a second extruder in an extrusion molding apparatus according to the present invention;  
         [0019]    [0019]FIG. 4 is a perspective view of an extrusion molding die according to the present invention;  
         [0020]    [0020]FIG. 5 is a front view of a second molding member which is a part of the extrusion molding die according to the present invention;  
         [0021]    [0021]FIG. 6 is a sectional view taken along line IV-IV of FIG. 3;  
         [0022]    [0022]FIG. 7 is a front view of a first molding member which is a part of the extrusion molding die according to the present invention;  
         [0023]    [0023]FIG. 8 is a sectional view taken along line VI-VI of FIG. 5;  
         [0024]    [0024]FIG. 9 is a sectional view taken along middle portions of the first and second molding members, illustrating combination of FIG. 4 and FIG. 6; and  
         [0025]    [0025]FIG. 10 is a front view of a first molding member which is a part of the extrusion molding die according to the present invention, illustrating a feeding state of a second synthetic resin.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0026]    Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.  
         [0027]    An extrusion molding product  1  according to the present invention, as shown in FIG. 1, is configured such that an original synthetic resin is coated with a second synthetic resin  1   b . The second synthetic resin  1   b  contains a wood powder of 80˜120 meshes and is coated on a surface of the original synthetic resin at different ratios so that a wood pattern  1   a  is formed.  
         [0028]    As shown in FIGS.  2  to  4 , an extrusion molding apparatus for manufacturing the aforementioned product  1  includes a first extruder  100 , a die  10  installed at an outlet of the first extruder  100 , and a second extruder  200  installed at a side of the die  10 .  
         [0029]    The first extruder  100  has the same configuration as that of a general extruder. That is, the first extruder  100  includes a heat cylinder  101  provided with a heater  102  on an outer surface, a hopper  103  for supplying a first thermoplastic synthetic resin to an inner portion of the heat cylinder  101 , a screw  104  for extruding the first synthetic resin softened by heat in the heat cylinder  101  to the die  10  by rotation, and a driver  110  for driving the screw  104 .  
         [0030]    Likewise, the second extruder  200  has the same configuration as that of a general extruder. The second extruder  200  includes a heat cylinder  201  provided with a heater  202 , a hopper  203 , a screw (not shown), and a driver  210 . The hopper  203  is supplied with a second synthetic resin which contains a wood powder of 80˜120 meshes to form a wood pattern  1   a  on a surface of the product  1  to be extruded.  
         [0031]    The die  10  connected with the first and second extruders  100  and  200 , as shown in FIGS.  4  to  10 , includes first synthetic resin passages  21  and  31  for extruding the first synthetic resin. The second extruder  200  is connected between two moldings  20  and  30  coupled to each other at the foremost among a plurality of moldings constituting the die  10 . The second synthetic resin is fed between the two moldings and then is extruded along a passage formed to communicate with the first synthetic resin passages  21  and  31 . Since the second synthetic resin passage is extruded around the first synthetic resin passages  21  and  31  by the above structure, the second synthetic resin is coated on the first synthetic resin passages  21  and  31  constituting the product  1 . Since the second synthetic resin contains a wood power of 80˜120 meshes, a wood pattern  1   a  is formed on a surface of the product  1 .  
         [0032]    The wood pattern  1   a  is distinctly formed on the surface of the product  1  by the two moldings  20  and  30  at the end among the moldings of the die  10 . That is, a connecting passage  40  is formed between the second molding member  20  at the end of the die  10  and the first molding member  30  next to the second molding member  20 . The second synthetic resin containing a wood powder formed by grinding wood is fed to the connecting passage  40 . The connecting passage  40  is connected with the second extruder  200 . The second synthetic resin which passed through the connecting rod  40  moves to the synthetic resin passages  21  and  31  along a passage formed inside the first and second molding members  20  and  30  and is coated on the surface of the synthetic resin extruded by pressure of the first extruder.  
         [0033]    The first molding member  30 , as shown in FIGS.  4  to  6  and FIG. 9, includes half of the connecting passage  40  having a screw for connecting to the second extruder. The synthetic resin passage  31  is formed inside the first molding member  30 , and a slit surface  32  is formed around the synthetic resin passage  31  at a height lower than a surface of the first molding member  30  so that the second synthetic resin flows to the synthetic resin passage  31 . A retainer groove  30  connected to the connecting passage  40  is formed around the slit surface  32 . The retainer groove  33  is lower then the slit surface  32 . Therefore, after the second synthetic resin is completely filled in the retainer groove  33 , it passes through the slit surface  32  toward the synthetic resin passage  31  by pressure of the second synthetic resin and then extruded through the whole surface.  
         [0034]    The second molding member  20 , as shown in FIG. 4, and FIGS.  7  to  9 , is symmetrically formed to engage with the first molding member  30 . Half of the connecting passage  40  having a screw for connecting with the second extruder is formed in the second molding member  20  so that the complete connecting passage  40  is formed together with the connecting passage  40  formed in the first molding member  30 . In the same manner as the first molding member  30 , the synthetic resin passage  21  is formed in the second molding member  20 . A lead surface  22  is formed around the synthetic resin passage  21  together with the slit surface  32 , thereby forming a space where the second synthetic resin flows. A retainer groove  23  connected to the retainer groove  33  of the first molding member  30  is formed around the lead surface  22 . Particularly, the second molding member  20 , as shown in FIGS.  7  to  9 , includes a plurality of nozzle grooves  24  formed with a curved section, which is higher than the retainer groove  23  but lower than the lead surface  22 , between the retainer groove  23  and the synthetic resin passage  21 . Each of the nozzle grooves  24  includes a distal end  24   a  supplied with the second synthetic resin at a greater amount than that supplied to any other portions, thereby forming a wood pattern. The distal end  24   a  has a sectional area smaller than that of any other portions to serve as a nozzle. The nozzle grooves  24  are inclined at a predetermined angle along an incoming direction of the second synthetic resin so that the second synthetic resin readily moves to the nozzle grooves  24  through the retainer groove  23 .  
         [0035]    The retainer grooves  23  and  33  of the first and second molding members  20  and  30 , as shown in FIG. 9, are formed to surround the synthetic resin passages  21  and  31  and have a curved section with a predetermined gradient.  
         [0036]    [0036]FIG. 9 is a sectional view illustrating a coupling state of the first and second molding members  20  and  30 . As shown in FIG. 9, the second synthetic resin is introduced into the retainer grooves  23  and  33  through the connecting passage  40  and then moves to the synthetic resin passages  21  and  31  through the space between the slit surface  32  and the lead surface  22 . Particularly, as shown in FIG. 7, since the portion where the nozzle grooves  24  are formed has a greater passage area than any other portions, the second synthetic resin moves at a greater amount, thereby resulting in that a wood pattern  1   a  is formed on the surface of the product  1 .  
         [0037]    The operation of the aforementioned extrusion molding apparatus will now be described based on the flow of the first and second synthetic resins.  
         [0038]    First, the first synthetic resin, as shown in FIGS. 2 and 3, is fed to the first extruder  101  through the hopper  103  and moves to the die  10  by pressure of the rotating screw  104 . At this time, the first synthetic resin moves while being softened by the heater  102 . The first synthetic resin moved to the die  10  by the screw  104  is extruded in accordance with shapes of the first synthetic resin passages  21  and  31  formed in the die  10 , so that the product  1  is successively produced.  
         [0039]    The aforementioned extrusion method is the same as the operation of the typical extrusion molding apparatus. In addition to the above method, in the present invention, the second synthetic resin containing a wood powder of 80˜120 meshes, as shown in FIGS. 2 and 3, is fed to the second extruder  200  through the hopper  203  and moves through the screw and the second passage  40  formed at a side of the die  10  while being softened by the heater  202 . The second synthetic resin introduced into the side between the first and second molding members  20  and  30 , as shown in FIG. 9, is introduced around the first synthetic resin passages  21  and  31  through the space formed by the retainer grooves  23  and  33  of the first and second molding members  20  and  30 . At this time, the second synthetic resin is also introduced into the space formed by the nozzle grooves  24  and the slit surface  32 . Afterwards, the second synthetic resin is fed to the distal end  24   a  of the nozzle groove  24  and at the same time moves to the surface of the first synthetic resin extruded through the space formed by the slit surface  32  and the lead surface  22 . Therefore, the first synthetic resin is coated with the second synthetic resin. At this time, since the second synthetic resin extruded through the nozzle grooves  24  has a greater amount, the wood pattern  1   a  is formed on the surface of the product  1 .  
         [0040]    The operation of the first and second molding members  20  and  30  will be described in more detail.  
         [0041]    The second extruder is connected to the first and second molding members  20  and  30  through the connecting passage  40  so that the second synthetic resin containing a wood powder is fed to the first and second molding members  20  and  30 . The second synthetic resin, as shown in FIG. 9, is fed to the retainer grooves  23  and  33  of the first and second molding members  20  and  30 . At this time, the nozzle grooves  24  are inclined at a predetermined angle along a flow of the second synthetic resin introduced into the retainer grooves  23  and  33 . Accordingly, the second synthetic resin is also fed to the nozzle grooves  24 . Once the second synthetic resin is fully filled in the retainer grooves  23  and  33 , the second synthetic resin moves to the whole surface of the synthetic resin passages  21  and  31  through the space, which is formed by the slit surface  32  and the lead surface  22 , by the pressure of the second extruder. As a result, the synthetic resin moving through the whole surface of the synthetic resin passages  21  and  31  is coated with the second synthetic resin. At this time, since the second synthetic resin moves to the space formed by the nozzle grooves  24  and the slit surface  32  at a greater amount, the wood pattern  1   a  is formed on the surface of the product  1 . That is, as shown in FIG. 10, the wood pattern  1   a  is formed on lower and upper surfaces of the product  1 .  
         [0042]    The second synthetic resin contains a wood powder obtained by grinding wood as described above. However, the second synthetic resin may be formed of other materials as the case may be.  
         [0043]    Furthermore, the retainer grooves  23  and  33  are formed to surround the synthetic resin passages  21  and  31  so that the whole surface of the synthetic resin is equally coated with the second synthetic resin. That is, at a portion close to the connecting passage  40  supplied with the second synthetic resin, the retainer grooves  23  and  33  are formed far away from the synthetic resin passages  21  and  31 . By contrast, at a portion far away from the connecting passage  40 , the retainer grooves  23  and  33  are formed close to the synthetic resin passages  21  and  31 . Also, it should be noted that the retainer grooves  23  and  33  are bent depending on sectional shapes of the synthetic resin passages  21  and  31 .  
         [0044]    Furthermore, even if a molding member is designed by considering various cases, the second synthetic resin is introduced into the synthetic resin passages  21  and  31  at different ratios depending on position. In this case, some wood pattern may naturally be formed. However, in the present invention, since the nozzle grooves  24  are formed, accurate wood pattern can artificially be formed.  
         [0045]    As described above, the extrusion molding apparatus for a product having a wood pattern and the extrusion molding method according to the present invention have the following advantages.  
         [0046]    Since the product having a wood pattern is formed by the first and second synthetic resins, the wood pattern is not taken off and esthetic appearance can be obtained.  
         [0047]    In addition, the finished product is manufactured by one time process, and no process of wrapping a sheet paper of a wood pattern is required. This reduces the process steps and thus enhances the productivity.  
         [0048]    The foregoing embodiments are merely exemplary and are not to be construed as limiting the present invention. The present teachings can be readily applied to other types of apparatuses. The description of the present invention is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art.

Technology Classification (CPC): 1