Abstract:
A plastic material injection molding system includes a feeding nozzle, a forming mold having a cave therein, and a material-passing mold having a runner therein. The runner communicates both the feeding nozzle and the cave, and has two curved parts therein for slowing down the plastic material injected from the feeding nozzle in order.

Description:
RELATED APPLICATIONS 
     This application claims priority to Taiwanese Application Serial Number 100103918, filed Feb. 1, 2011, which is herein incorporated by reference. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a molding system, more particular to a plastic material injection molding system. 
     2. Description of Related Art 
     In a process of making a plastic product by a conventional injection molding method, mold designs, plastic material qualities, plastic material feeding pressures or internal parameters (e.g. time, temperature, pressure, flow speed) of plastic material in mold may be one of the factors for the plastic product to be imperfect. Commonly, these imperfections can be wrinkles, blisters, scrapes, granulations or feeding-point shadows formed on a surface of the plastic product etc. 
     Refer to  FIG. 1  in which  FIG. 1  is a top view of a plastic product P made by a conventional injection molding method. Regarding to the so-called feeding-point shadow D, after the plastic product P is formed in the mold, the feeding-point shadow D is always existed, corresponding to the position of feeding-point, on a surface of the plastic product P opposite to the feeding-point of the mold. Thus, comparing to other area of the surface of the plastic product P, the feeding-point shadow D is with a darker color so as to cause uneven quality of color of the plastic product P. 
     Therefore, since the plastic product made by the conventional injection molding method mentioned above still obviously exists inconveniences and disadvantages which are needed to be improved, especially to the feeding-point shadow of the plastic product. 
     SUMMARY 
     The present invention is to disclose a plastic material injection molding system, which can provide a plastic product without feeding-point shadows thereon by an injection molding method. 
     The present invention is to disclose a plastic material injection molding system, which can decrease the boosting pressure of the plastic material being fed into the mold so as to provide a plastic product with consistent color and brightness on appearance, and reduce possibilities that feeding-point shadows existed on the surface of the plastic product when the plastic product is formed. 
     According to one practice of the invention, the plastic material injection molding system comprises a feeding nozzle, a forming mold and a material-passing mold. The feeding nozzle feeds liquid plastic material to the forming mold via the material-passing mold. The forming mold is provided with a forming cavity therein, and the forming cavity forms the liquid plastic material into a plastic product. The material-passing mold is disposed between the feeding nozzle and the forming mold. The material-passing mold is provided with a material-feeding runner therein, the material-feeding runner is in communication with both the feeding nozzle and the forming cavity. The material-feeding runner comprises a first bending section and a second bending section. The first bending section and the second bending section decrease flow speed and boosting pressure of the liquid plastic material sequentially. 
     In one embodiment of the practice, the material-feeding runner further comprises a U-turn section. The U-turn section is disposed between the forming cavity and the second bending section. Thus, when the liquid plastic material in the material-feeding runner travels to the material-passing mold via the U-turn section, a traveling journey of the liquid plastic material to the material-passing mold can be extended so that the flow speed and the boosting pressure of the liquid plastic material can be further decelerated again. Furthermore, the space of the U-turn section is shrunk gradually towards a direction far away from the second bending section. 
     In another embodiment of the practice, the material-passing mold further comprises a male die block and a female die block capable of assembling together. The male die block has a first waved surface at one side thereof. The female die block has a recess and a second waved surface at one side thereof, and the second waved surface is an inner surface of the recess. After the male die block and the female die block are assembled together, wave peaks and wave troughs of the first waved surface and wave peaks and wave troughs of the second waved surface are staggered so as to form the first bending section and the second bending section. 
     In the embodiment, the female die block further comprises a protrusion connected the second waved surface, and extended from the second waved surface towards the first waved surface. The protrusion is located at the first bending section, and is vertically aligned with the feeding nozzle for guiding the liquid plastic material to the second bending section. 
     In another embodiment of the practice, the material-feeding runner further comprises a buffer section. The buffer section is disposed between the feeding nozzle and the first bending section for buffering the liquid plastic material. 
     To sum up, since the plastic material injection molding system of the invention is designed for decreasing flow speed and boosting pressure of the liquid plastic material, the liquid plastic material can be filled in the forming cavity uniformly and sequentially before the plastic product is formed, so as to reduce possibilities that feeding-point shadows existed on the surface of the plastic product to degrade the plastic product with inconsistent color and brightness on appearance. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be apparent to those skilled in the art by reading the following detailed description of a preferred embodiment thereof, with reference to the attached drawings, in which: 
         FIG. 1  is a top view of a plastic product made by a conventional injection molding method. 
         FIG. 2  is a top view of a plastic material injection molding system according to an embodiment of the present invention. 
         FIG. 3  is a section view of the plastic material injection molding system and an enlarged view of a material-feeding runner according to the embodiment of the present invention. 
         FIG. 4  is a perspective view of a male die block and female die block according to the embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawings. 
     Since the plastic product P made by the conventional injection molding method mentioned above always exists with imperfections of the feeding-point shadow D ( FIG. 1 ) on the surface of the plastic product P, thus, the feeding-point shadow D is with a darker color so as to cause uneven quality of color on the integral appearance. Therefore, after analyzing and researching constantly by the inventor of the present invention, the inventor has found the main reason why the feeding-point shadow D generated on the surface of the plastic product P, that is, the boosting pressure of the plastic material being filled into the mold is so huge, thus, when the plastic material is delivered into a cavity of the mold, the beginning part of the plastic material impacts to the inner surface of the cavity and spreads radially neighboring to a center portion thereof so that the beginning part and the following part of the plastic material are not hardened simultaneously (i.e. the beginning part of the plastic material is quicker to be hardened than the following part of the plastic material to be hardened). Therefore, there are different in color and brightness on appearance of the surface of the plastic product. 
     As a result, the inventor provides a plastic material injection molding system capable of slowing down the boosting pressure of the plastic material being filled into the mold so as to reduce possibilities of the feeding-point shadows existed on the surface of the plastic product to improve consistent color and brightness on appearance of the plastic product. 
     Refer to  FIG. 2  and  FIG. 3  in which  FIG. 2  is a top view of a plastic material injection molding system according to an embodiment of the present invention, and  FIG. 3  is a section view of the plastic material injection molding system and an enlarged view of a material-feeding runner according to the embodiment of the present invention. 
     The plastic material injection molding system  100  comprises a material-feeding element  200  and a forming mold device  300 . The forming mold device  300  comprises a forming mold  400  and a material-passing mold  500 . The material-feeding element  200  is provided with a material-feeding nozzle  210 . The material-feeding element  200  connects a material-supply end so that the material-feeding element  200  can inject liquid plastic material M (e.g. Polyvinyl chloride, PVC or Acrylonitrile Butadiene Styrene, ABS) with high temperature and high pressure by the material-feeding nozzle  210 . The forming mold  400  is assembled by at least two die blocks forming a forming cavity  410  therein after the die blocks assembled. The liquid plastic material M is formed into a plastic product (e.g. external case and plastic component) through the forming cavity  410  of the forming mold  400 . 
     The material-passing mold  500  can be independent to or separated from the forming mold  400  and the material-feeding element  200 , and the material-passing mold  500  also can be assembled with the forming mold  400  and the material-feeding element  200  so that the material-passing mold  500  is disposed between the forming mold  400  and the material-feeding element  200 . 
     The material-passing mold  500  is provided with a material-feeding runner  510  formed therein as a tunnel. Two opposite ends of the material-feeding runner  510  are respectively communicated with the material-feeding nozzle  210  and the forming cavity  410 . Thus, the material-feeding runner  510  guides the liquid plastic material M injected from the material-feeding nozzle  210  to the forming cavity  410 . 
     Substantially, the material-feeding runner  510  is outlined as an “S” letter, and the material-feeding runner  510  comprises a first bending section  513  and a second bending section  514  connected continually to the first bending section  513 . 
     Therefore, after the material-feeding nozzle  210  injects a continuous stream of liquid plastic material M into the forming cavity  410  via the material-feeding runner  510 , the liquid plastic material M sequentially pass through the first bending section  513  and the second bending section  514  before the liquid plastic material M entering into the forming cavity  410 . 
     Since the first bending section  513  and the second bending section  514  are non-linear, comparing to other linear passages, the first bending section  513  and the second bending section  514  can respectively extend a traveling journey of the liquid plastic material M so as to decelerate the flow speed of the liquid plastic material M. 
     Since the flow speed of the liquid plastic material M is slowed down by the first bending section  513  and the second bending section  514 , the boosting pressure of the liquid plastic material M is decreased as well. On the other words, the first bending section  513  and the second bending section  514  can help to decrease the boosting pressure of the liquid plastic material M in the material-feeding runner  510 . 
     Thus, when the beginning part and the following part of the liquid plastic material M filled into the cavity, the beginning part and the following part of the liquid plastic material M will not cause that the beginning part and the following part of the liquid plastic material M are not hardened simultaneously or the beginning part thereof is hardened quickly than the following part thereof, so that the beginning part and the following part of the liquid plastic material M are similar in color and brightness on appearance of the surface of the plastic product. 
     In one embodiment of the invention, the material-feeding runner  510  further comprises an inlet section  511  and a buffer section  512 . The inlet section  511  is substantially presented as a linear passage, arranged between the buffer section  512  and the material-feeding nozzle  210 , and directly communicated both the buffer section  512  and the material-feeding nozzle  210 . The buffer section  512  is arranged between the inlet section  511  and the first bending section  513  and directly communicated both the inlet section  511  and the first bending section  513 . Since a width W 1  of the buffer section  512  is larger than a width W 2  of the first bending section  513 , thus, the buffer section  512  play as a buffer before the liquid plastic material M ready get into the first bending section  513 . 
     In the embodiment, the material-feeding runner  510  further comprises a U-turn section  515  and an outlet section  516 . The “U-turn” means the flow direction, not the shape of the section  515 . The U-turn section  515  is adjacent to the second bending section  514 , and the U-turn section  515  is arranged between the forming cavity  410  and the second bending section  514 . The outlet section  516  is substantially presented as a linear passage, and arranged between the U-turn section  515  and the forming cavity  410 , and directly communicated both the U-turn section  515  and the forming cavity  410 . Further, a lateral side of the outlet section  516  is connected to the left side of U-turn section  515  as same as a lateral side that the second bending section  514  connects to the left side of U-turn section  515 . 
     As such, simultaneously refer to a dotted arrow in  FIG. 3  as a traveling journey of the liquid plastic material M, when the liquid plastic material M is flowed into the U-turn section  515  through the second bending section  514 , the inner surface of the U-turn section  515  far away from the second bending section  514  (i.e. right side of the inner surface of the U-turn section  515 ) stops and redirects the liquid plastic material M to the left side of the inner surface of the U-turn section  515  in opposite so as to guide the liquid plastic material M into the forming cavity  410 . 
     Since the U-turn section  515  extends the traveling journey of the liquid plastic material M, the U-turn section  515  further decelerates the flow speed of the liquid plastic material M, on the other word, the U-turn section  515  decreases the boosted pressure of the liquid plastic material M. 
     Furthermore, in one preferred embodiment, the space of the U-turn section  515  is shrunk gradually towards a direction far away from the second bending section  514  so as to lead the liquid plastic material M to the left side of the U-turn section  515 . The caliber of the U-turn section  515  on the right side is also shrunk gradually towards the left side of the U-turn section  515  so as to lead the liquid plastic material M being far away from the second bending section  514 . 
     Refer to  FIG. 2  and  FIG. 4  in which  FIG. 4  is a perspective view of a male die block and female die block according to the embodiment of the present invention. 
     In one optional embodiment of the invention, the material-passing mold  500  further comprises a connection block  520 , a male die block  530 , and a female die block  540  in which the male die block  530  and the female die block  540  are capable of assembling together. The male die block  530  has a first waved surface  531  at one side thereof ( FIG. 4 ). The female die block  540  has a recess  541  and a second waved surface  542  at one side thereof ( FIG. 4 ), and the second waved surface  542  is an inner surface of the recess  541 . The inlet section  511  of the material-feeding runner  510  is disposed inside the connection block  520 . 
     After the male die block  530  and the female die block  540  are assembled together, wave peaks K and wave troughs V of the first waved surface  531  and wave peaks K and wave troughs V of the second waved surface  542  are staggered so as to form the buffer section  512 , the first bending section  513 , the second bending section  514 , and the U-turn section  515  therebetween ( FIG. 2 ). 
     Also, after the male die block  530  and the female die block  540  are assembled together, the connection block  520  is installed between the material-feeding nozzle  210 , the male die block  530  and the female die block  540 , thus, the inlet section  511 , the buffer section  512 , the first bending section  513 , the second bending section  514 , and the U-turn section  515  can be integrated substantially as the material-feeding runner  510  ( FIG. 2 ). 
     In the embodiment of the invention, the female die block  540  further comprises a protrusion  543 . The protrusion  543  is located at a wave peak K of the second waved surface  542 , and extended from the second waved surface  542  towards the first waved surface  531 , and the protrusion  543  is in the first bending section  513  and is vertically aligned with the buffer section  512  and the feeding nozzle  210  for guiding the liquid plastic material to the second bending section  514 . 
     Therefore, when the liquid plastic material M vertically enters into the first bending section  513  via the inlet section  511  and the buffer section  512  ( FIG. 2 ), since the protrusion  543  is straightly aligned with the feeding nozzle  210 , the liquid plastic material M is resisted by the protrusion  543  and the liquid plastic material M can flow through the first bending section  513  and the second bending section  514 . Therefore, since the protrusion  543  resists the high-pressured liquid plastic material M, the protrusion  543  can slow down the flow speed of the high-pressured liquid plastic material M, on the other word, the pressure of the liquid plastic material M also may be decreased. 
     Although the present invention has been described with reference to the preferred embodiments thereof, it is apparent to those skilled in the art that a variety of modifications and changes may be made without departing from the scope of the present invention which is intended to be defined by the appended claims. 
     The reader&#39;s attention is directed to all papers and documents which are filed concurrently with this specification and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference. 
     All the features disclosed in this specification (including any accompanying claims, abstract, and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.