Patent Publication Number: US-2017355115-A1

Title: Vertical injection molding machine, and method of molding composite molded parts by using vertical injection molding machine

Description:
FIELD OF THE INVENTION 
     This invention relates to a vertical injection molding machine having a mold comprising an upper mold and a lower mold for opening and closing the mold in a vertical direction, and to a method of molding composite molded parts in the vertical injection molding machine. This invention also relates to a vertical injection molding machine for injecting and filling resin to be a product body from an injection nozzle to a cavity of the mold against a fiber resin base material mounted in the mold, which is integrally molded with the product body resin, and manufacturing composite molded parts, and to a method of molding the composite molded parts by using the vertical injection molding machine. In particular, this invention relates to a vertical injection molding machine for injecting and filling resin to be the product body from the injection nozzle to a cavity of the mold against a long fiber resin sheet mounted in the mold, which is integrally molded with the product body resin, and manufacturing composite molded parts, and to a method of molding the composite molded parts by using the vertical injection molding machine. 
     DESCRIPTION OF THE RELATED ART 
     A conventional and common injection molding machine is designed to manufacture molded parts by sending granular thermoplastic resin as a material to a heating cylinder, sending out a predetermined amount of molten resin to a nozzle of an end part of a screw while melting the resin by rotation of a screw provided in the heating cylinder, injecting molten resin in a clamped mold cavity from an injection nozzle provided at the end part of the screw by forwarding the screw, and taking out solidified molded parts from the mold. 
     In a recent year, in order to achieve high degree of hardness of the molded parts, there has been spread a technology of manufacturing the molded parts consisting of not only thermoplastic resin, as materials of the molded parts, but a composite material such as carbon fiber reinforced plastic (CFRP) mixing carbon fiber to thermoplastic resin. Patent Document 1, which relates to such conventional technology, discloses a plasticizing device for kneading and mixing fiber reinforcing thermoplastic resin made by mixing thermoplastic resin and reinforcing fiber in a heating cylinder by rotation of a screw, after breaking the reinforcing fiber into several millimeters, injecting the fiber reinforcing thermoplastic resin to a cavity of the mold, and manufacturing molded parts consisting of the fiber reinforcing thermoplastic resin. 
     There is known a vertical injection molding machine for equipping a plurality of lower molds on a rotation table, and at a mold opening and closing/injecting stage, clamping an upper mold provided at the mold opening and closing/injecting stage and the lower mold sent to the mold opening and closing/injecting stage, injecting and filling molten resin in the mold after clamping, and at an ejecting stage, ejecting molded parts from the lower mold sent to the ejecting stage. The vertical injection molding machine having such a rotation table is capable of closing mold (clamping mold), injecting, measuring, and opening mold at the mold opening and closing/injecting stage, and of ejecting forward and backward at the ejecting stage at the same time. There can be realized shortening of molding cycle thereby. For example, Patent Document 2 discloses an insert molding capable of loading (mounting/positioning) an inserting object for insert molding on the lower mold at the ejecting stage of such vertical injection molding machine, after taking out the mold parts. 
     PRIOR ART 
     [Patent Document] 
     Patent Document 1: Japanese Patent Laid-Open Publication H11-034131 
     Patent Document 2: Japanese Patent Laid-Open Publication 2007-055097 
     Problem to be Solved by the Invention 
     As shown in Patent Document 1, there is known a method of obtaining molded parts consisting of fiber reinforcing thermoplastic resin having a relative short fiber of several millimeters. However, when products are obtained which is formed by integrating resin and relative long fibers of such as 50 or more than 100 millimeters, the method of Patent Document 1 is not appropriate because the fibers are broken into several millimeters in a heating cylinder. Furthermore, there can be thought that a long fiber resin sheet which is softened by heat is arranged in a cavity of the mold, resin is injected in the cavity of the mold in which the long fiber resin sheet is provided, and products made by integrating the long fibers and the resin can be obtained. In a common injection molding machine, a movable mold is designed to open and close the mold in a horizontal direction to a fixed mold. Therefore, when the resin to be a product body and the long fiber resin sheet to which the resin is impregnated are integrally molded, the long fiber resin sheet softened by heating should be held while standing at a predetermined position between the fixed mold and the movable mold. In this case, the long fiber resin sheet softened by heating may be bent at upper portion by the gravity and there is a risk to failure in molding thereby. 
     This invention is made taking the above problems into consideration, and an object of the same is to provide a vertical injection molding machine for suppressing forming defective molded parts in the composite molded parts, when the resin to be a product body and the long fiber resin sheet are integrally molded, and a method of molding the composite molded parts in the vertical injection molding machine. 
     Means for Solving the Problem 
     According to the invention of a vertical injection molding machine, there is provided a vertical injection molding machine comprising a rotary table rotatably provided in an axial direction as a vertical direction, lower molds provided on an upper surface of the rotary table, and an upper mold for opening and closing the lower molds, a vertical injection molding machine opening and closing mold in a vertical direction, wherein a space is formed by the lower molds and the upper mold when the lower molds and the upper mold are closed, a fiber resin base material and resin injected from an injection unit being inserted to the space, and an upper and a lower directions of the fiber resin base material are matched to a mold opening and closing direction of the upper mold and the lower molds, when a plane surface part of the fiber resin base material faces the lower molds, and when the plane surface part of the fiber resin base material facing the lower molds is defined as a lower surface, and an opposite surface being defined as an upper surface. 
     A vertical injection molding machine of the present invention comprises a conveying device for mounting the fiber resin base material so that a plane surface part of the fiber resin base material faces the lower molds. 
     A vertical injection molding machine of the present invention comprises a heater for heating the fiber resin base material mounted on the lower molds. 
     According to a vertical injection molding machine of the present invention, when the fiber resin base material is mounted on the lower molds, the heater is provided for freely elevating and lowering at a position on the upper surface of the fiber resin base material. 
     According to a vertical injection molding machine of the present invention, the fiber is a glass fiber and/or carbon fiber. 
     A method of molding composite molding parts in a vertical injection molding machine according to the present invention comprises steps of; 
     moving the lower molds on which the fiber resin base material is mounted to a clamping position on the upper mold by rotating the rotary table after the fiber resin base material is mounted on the lower molds, 
     clamping the upper mold and the lower molds at the clamping position, pressing the fiber resin base material arranged therebetween and molding into a predetermined shape, 
     injecting resin from an injection unit to a cavity formed by clamping the upper mold and the lower molds having the fiber resin base material molded into a predetermined shape, and 
     integrally molding the resin to be a product body injected from the injection unit and the fiber resin base material. 
     According to the present invention related to a method of molding composite molding parts in a vertical injection molding machine, the fiber resin base material is mounted on the lower molds by the conveying device. 
     According to the present invention related to a method of molding composite molding parts in a vertical injection molding machine, after the fiber resin base material is mounted on the lower molds, the fiber resin base material is heated and softened by the heater provided at a position on the upper surface of the fiber resin base material, after that, the lower molds on which the softened fiber resin base material is mounted is moved to a clamping position on the upper mold by rotating the rotary table. 
     Effect of Invention 
     According to the present invention, direction of an upper and a lower surfaces of a fiber resin base material to be mounted on a lower mold are a vertical direction. When the fiber resin base material is mounted in a manner that the lower surface of the plane surface part of the fiber resin base material has face contact with the lower mold, the fiber resin base material mounted on the lower mold can be stably held without displacement. Accordingly, when the resin to be a product body which is injected from an injection nozzle and the fiber resin base material are integrally molded, it becomes possible to integrally mold the fiber resin base material at a predetermined position of the product body. Furthermore, when the fiber resin base material mounted on the lower mold is softened by heating by a heater, the softened fiber resin base material is not held while standing as conventional, and it can be avoided to mold defective molded parts due to bending at upper portion of the softened fiber resin base material by the gravity. 
     As a detail embodiment of the present invention, when the fiber resin base material is a long fiber resin sheet, direction of an upper and a lower surfaces of the long fiber resin sheet to be mounted on a lower mold are vertical direction. When the long fiber resin sheet is mounted in a manner that the lower surface of the plane surface part of the long fiber resin sheet is in face contact with the lower mold, the long fiber resin sheet mounted on the lower mold can be stably held without displacement. Accordingly, when the resin to be the product body which is injected from an injection nozzle and the long fiber resin sheet are integrally molded, it becomes possible to integrally mold the long fiber resin sheet at a predetermined position of the product body. Furthermore, when the long fiber resin sheet mounted on the lower mold is softened by heating by a heater, softened long fiber resin sheet is not held while standing as conventional, and it can be avoided to mold defective molded parts due to bending at upper portion of the softened fiber resin base material by the gravity. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a front view showing a vertical injection molding machine according to the present invention. 
         FIG. 2  is a plan view showing a vertical injection molding machine according to the present invention. 
         FIG. 3  is a left side view of a vertical injection molding machine comprising a robot (not shown) according to the present invention. 
         FIG. 4  is a perspective view showing a long fiber resin sheet, a product body (thermoplastic resin) and composite molded parts made by integrally molding the product body and the ling fiber resin sheet. 
         FIG. 5  is an explanatory drawing showing movement of a vertical injection molding machine according to the present invention. 
     
    
    
     PREFERRED EMBODIMENT 
     Referring to  FIGS. 1 to 5 , description will be made for some embodiments of the present invention. The present invention can be easily applied to other than that explained in the embodiments within a scope of the invention. 
     As a vertical injection molding machine  1  according to the present invention, there is described a vertical injection molding machine  1  for injecting and filling resin to be a product body  20  from an injection nozzle  19  to a cavity of a mold against a long fiber resin sheet  21  mounted in the mold, integrally molding the product body resin and the long fiber resin sheet  21 , and manufacturing composite molded parts  22 , and also described a method of molding the composite molded parts  22  by using the vertical injection molding machine  1 . However, limitation is not made to the long fiber resin sheet  21 , but a fiber resin base material for molding the composite molded parts  22  may be available. 
     The fiber resin base material used in the present invention is a mixture base material of a fiber and resin forming composite molding material, and there are included one comprising fibers aligned in one direction and the resin, one comprising fibers aligned in random and resin, and one comprising woven fabric fibers and resin, or the like. The resin may be impregnated in the fibers or may not be, or may be laminated. There are some fiber resin base materials which the resin is impregnated in the fibers, and for example, prepreg can be considered. There are some fiber resin base materials which the resin is not impregnated in the fibers, and for example, nonwoven fabric tangling fibers and fibrous resin is considered. 
     Hereinbelow, regarding a vertical injection molding machine  1  according to the present invention, a long fiber resin is described as a sheet fiber resin base material for forming composite molded parts  22 , however it is not limited thereto. 
     According to the embodiments of the vertical injection molding machine  1  of the present invention, the vertical injection molding machine  1  comprises a rotary table  7  rotatably provided in an axial direction as a vertical direction, lower molds  8   a ,  8   b  provided on an upper surface of the rotary table  7 , and an upper mold  9  for opening and closing to the lower molds  8   a ,  8   b , and opens and closes mold in a vertical direction. The vertical injection molding machine  1  also comprises a conveying device mounted on the lower molds  8   a ,  8   b  so as to face plane surface part of the long fiber resin sheet  21 , and a heater  14  for heating the long fiber resin sheet  21  mounted on the lower molds  8   a ,  8   b . When the plane surface part of the long fiber resin sheet  21  facing the lower molds  8   a ,  8   b  is defined as a lower surface, and an opposite surface is as an upper surface, an upper and a lower directions of the long fiber resin sheet  21  is matched to a mold opening and closing direction of the upper mold  9  and the lower molds  8   a ,  8   b.    
     Furthermore, according to the embodiments of the vertical injection molding machine  1  of the present invention, the long fiber resin sheet  21  is mounted on the lower molds  8   a ,  8   b  and the heater  14  is provided for freely elevating and lowering at a position on the upper surface of the long fiber resin sheet  21 . 
     Furthermore, according to the embodiments of the vertical injection molding machine  1  of the present invention, the long fiber resin sheet  21  is formed by impregnating the resin into woven fabrics into which the long fibers are woven and solidifying the same. 
     Furthermore, according to the embodiments of the vertical injection molding machine  1  of the present invention, the long fiber is a carbon fiber. 
     Furthermore, according to the embodiments of a method of molding composite molded parts in the vertical injection molding machine  1  of the present invention, after the long fiber resin sheet  21  is mounted on the lower molds  8   a ,  8   b  by means of the conveying device, the long fiber resin sheet  21  is heated and softened by the heater  14  provided at a position on the upper surface of the long fiber resin sheet  21 , the lower molds  8   a ,  8   b  on which the softened long fiber resin sheet  21  is mounted are moved to a mold clamping position on the upper mold  9  by rotating the rotary table  7 , the upper mold  9  and the lower molds  8   a ,  8   b  are clamped at the mold clamping position, and the long fiber resin sheet  21  arranged therebetween is pressed and molded to a predetermined shape thereby. The resin is injected from the injection unit  3  to the cavity which includes the long fiber resin sheet  21  molded in a predetermined shape and is formed by clamping the upper mold  9  and the lower molds  8   a ,  8   b , and the resin to be a product body which is injected from the injection unit  3  and the long fiber resin sheet  21  are integrally molded. 
     The vertical injection molding machine  1  according to detailed embodiment of the present invention is designed to open and close the mold in a vertical direction, and comprises a clamping unit  2  for opening and closing the mold, an injection unit  3  for injecting thermoplastic resin in the mold provided in the clamping unit  2 , and a robot  5  as a conveying device for providing the long fiber resin sheet  21  to the clamping unit  2 . 
     The long fiber resin sheet  21  as a fiber resin base material according to the embodiment is also called as “thermoplastic resin” prepreg sheet, and formed by impregnating the thermoplastic resin into woven fabrics into which the long fibers of carbon fibers are woven and solidifying the same. In the embodiments hereinafter, as the fiber resin base material, the long fiber resin sheet is applied, however, the present invention is not limited to the same. 
     The clamping unit  2  comprises a rotary table  7  rotatably provided on a machine stand  6 , two lower molds  8   a ,  8   b  provided on the upper part of the rotary table  7 , the upper mold  9  for opening and closing each of the lower molds  8   a ,  8   b , a movable die plate  11  having a lower part on which the upper mold  9  is provided, three tie bars  12  for freely elevating and lowering to support the movable die plate  11 , and a toggle link mechanism (not shown) for elevating and lowering the movable die plate  11 . The rotary table  7  and the toggle link mechanism are driven by a servo motor (not shown) as a driving source. 
     As shown in  FIG. 1 , regarding two lower molds  8   a ,  8   b , a fixed mold  9  is arranged above the lower mold  8   b  so as to face the same, and the freely elevating/lowering heater  14  is arranged above the lower mold  8   a  so as to face the same. The heater  14  comprises an air cylinder  14   a  and the heater  14  is provided for freely elevating and lowering by the air cylinder  14   a.    
     The robot  5  comprises a link arm  15  having a plurality of arms and a suction part  16  attached to an end part of the link arm  15 , holds the long fiber resin sheet  21  mounted on the stand part  17  at the suction part  16  by using negative pressure, and conveys the long fiber resin sheet  21  to the predetermined position by the link arm  15 . 
     The injection unit  3  comprises a heating cylinder  18  for heating the thermoplastic resin and an injection nozzle  19  fitted on an end portion of the heating cylinder  18 , and injects molten thermoplastic resin from a horizontal direction to a cavity formed by clamping the upper mold  9  and the lower molds  8   a ,  8   b.    
     According to the vertical injection molding machine  1  having the above-mentioned structure, referring to  FIG. 5 , description will be made of an operation for manufacturing composite molded parts  22  by integrally molding (hybrid molding) the thermoplastic resin to be a product body  20  injected to the cavity of the mold shown in  FIG. 4  and the long fiber resin sheet  21 . 
     As shown in  FIG. 5( a ) , a sheet of a plurality of long fiber resin sheets on the stand part  17  is held at the suction part  16  of the robot  5 , and mounted so that the lower surface of the long fiber resin sheet  21  is in contact with the upper part of the lower mold  8   a  facing the heater  14 . After fixing on the mold, as shown in  FIG. 5( b ) , the heater  14  is lowered close to the long fiber resin sheet  21  by the air cylinder  14   a  and the long fiber resin sheet  21  is heated and softened by the heater  14 . After that, the heater  14  elevates to an original position by the air cylinder  14   a.    
     Next, by rotating the rotary table  7  clockwise at 180°, as shown in  FIG. 5( c ) , the lower mold  8   a  and the lower mold  8   b  switch positions to each other, the lower mold  8   a  on which the long fiber resin sheet  21  is attached is disposed at a position on the upper mold  9 . By lowering and clamping the upper mold  9  toward the lower mold  8   a , the long fiber resin sheet  21  arranged between the upper mold  9  and the lower mold  8   a  is pressed to be molded in a predetermined shape. 
     Next, as shown in  FIG. 5( d ) , the thermoplastic resin is injected from the injection nozzle  19  of the injection unit  3  to the cavity formed by clamping the upper mold  9  and the lower mold  8   a , and the thermoplastic resin to be the product body  20  injected from the injection nozzle  19  and the long fiber resin sheet  21  are integrally molded thereby. After cooling the integrally molded composite molded parts  22 , the mold is opened. 
     By rotating the rotary table  7  counterclockwise at 180°, the lower mold  8   a  with the composite molded parts  22  returns to the original position facing the heater  14 . After the composite molded parts  22  is left from the mold by an ejecting device (not shown), the composite molded parts  22  is taken out by using the suction part  16  of the robot  5 . By using two lower molds  8   a ,  8   b  alternately, and carrying out a series of operation as mentioned, the composite molded parts  22  to be the product can be mass produced. 
     As mentioned above, according to the vertical injection molding machine  1  of the embodiment of the present invention, since the upper and lower directions or the long fiber resin sheet  21  mounted on the lower molds  8   a ,  8   b  becomes the vertical direction, when the lower surface of the plane surface part of the long fiber resin sheet  21  is in face contact with the lower mold  8   a ,  8   b , the long fiber resin sheet  21  mounted on the lower mold  8   a ,  8   b  can be stably held without displacement. When the thermoplastic resin to be the product body  20  which is injected from the injection nozzle  19  and the long fiber resin sheet  21  are integrally molded, it becomes possible to integrally mold the long fiber resin sheet  21  at a predetermined position of the product body  20 . Furthermore, when the long fiber resin sheet  21  mounted on the lower mold  8   a ,  8   b  is softened by heating by the heater  14 , the softened long fiber resin sheet  21  is not held while standing as conventional, and it can be avoided to mold defective molded parts due to bending at upper portion of the softened fiber resin base material by the gravity. 
     The description is made of one aspect of the embodiments of the present invention, in particular of the embodiment to which the long fiber resin sheet is applied as the fiber resin base material. The present invention should not be limited thereto, and any modification is available within a scope of the invention. For example, according to the present embodiment, two lower molds  8   a ,  8   b  are provided on the rotary table  7  in a diameter direction, however three or four lower molds may be provided equidistantly on the rotary table  7 . 
     REFERENCE NUMERALS 
     
         
           1 . vertical injection molding machine 
           2 . clamping unit 
           3 . injection unit 
           5 . robot (conveying device) 
           6 . machine stand 
           7 . rotary table 
           8   a ,  8   b . lower mold 
           9 . upper mold 
           11 . movable die plate 
           12 . tie bar 
           14 . heater 
           14   a . air cylinder 
           15 . link arm 
           16 . suction part 
           17 . stand part 
           18 . heating cylinder 
           19 . injection nozzle 
           20 . Product body (thermoplastic resin injected to a cavity of mold) 
           21 . long fiber resin sheet (fiber resin base material) 
           22 . composite molded parts