Patent Publication Number: US-3880560-A

Title: Molding machine for synthetic resin article

Description:
United States Patent 11 1 Takahashi MOLDING MACHINE FOR SYNTHETIC RESIN ARTICLE Shigetoshi Takahashi, Nagoya, Japan [73] Assignee: Takahashi Seiki Co., Ltd.,  
 Nogoya-shi, Japan [22] Filed: May 31, 1974 [21] Appl. No.: 475,200  
 [75} Inventor:  
 [ 1 Apr. 29, 1975 Primary E.raminer.l. Howard Flint, Jr. Attorney, Agent, or Firm-Pennie &amp; Edmonds [57] ABSTRACT This invention relates to a molding machine for synthetic resin article, comprizing journals provided turnably and revolvably between upper and lower bearing boards, a central die plate whose both sides have been formed into mold fixing surfaces die plates which move forward and backward by mold tightening cylinders approachably to and releasably from each of said mold fixing surfaces of the central die plate, to guide rods mounted between the upper and lower positions of fixed boards provided on the base and said bearing boards and a suitable number of injection devices respectively onto the base at the positions outside the fixed boards in such a manner that the nozzles of said injection devices are capable of advancing and retreating to and from respective injection openings of the movable die plate.  
 3 Claims, 3 Drawing Figures PLIEHTEMMQ ms 3. 880.560  
 SHEET 30F 3 FIG.3-  
  I MOLDING M/\(&#39;IIINII FUR SYN&#39;I&#39;III&#39;I&#39;IIC RESIN AR&#39;I&#39;K&#39;LII This invention relates to a synthetic resin molding machine to mass-produce synthetic resin molded arti cles in which members of different colors or members of different kinds have been combined in integrity.  
  (onventionally in order to obtain a synthetic resin molded article such as lens for trafic indicator lamp or keys of typewriter. in which members of more than two colors havebeen joined in integrity. it has been usual lnethod either to adhere to one base-colored molded member another member which has been molded in difizrcnt color in advance. m f a l rality of members, each ofwhich has been pt i l M -d i different color. Such a method has retpn many bles to produce the molded articles ano been obtained only the molded articles which arc i damaged. It has been deemed diffictllt to mass-pr such kinds of synthetic resin molded articles suita and inexpensively. In order to eliminate the abov mentioned conventional demerits it is considered t mold an article in integrity which is provided with plural color of portions With conventional synthetip resin molding machines. however. it is difficult to fllilkt: sufficient mold tightening to carry out multicolor mold ing in view of the construction of mold tightening de vice in the molding machines and it is impossible tr, mass-produce multicolored molded articles of good quality with best yield.  
  The object ofthe present invention is to manufacture. a synthetic resin molding machine which has been com# pleted with the intention of carrying out multicolor molding quickly and easily.  
  The invention will be described below in more detail. in conjunction with the accompanying drawings. in which:  
  FIG. I is a partly broken elevation of a molding machine according to the present invention.  
  FIG. 2 is a partly broken top plan view of the same machine. and  
  I 3 is a section along the line llllll of FIG. 2.  
  Referring now FIGS. I throught 3, reference numerals lu. lh are left and right fixed boards provided oppositely at a regular space on the upper surface of the base. and between the four comers of said each fixed board In. Ih there are mounted four guide rods. 2 at predetermined intervals. Numerals i311. 3h represent mold tightening cylinders mounted oppositely {o said fixed boards la, lb. and the ends of pistons 4a, 4b of said mold tightening cylinders 31:, 3b are fixed to movable die plates 5a. 5b which are made to be guided by the guide rods 2. 2 passed through the four corners of the die plates. while with the back-wards and forwards movements of the pistons 4/) said movable die plates 51:. Share able to advance and retreat. Reference numerals 6a. 6b show bearing boards which are respectively fixed to the upper guide rods 2 and the lower guide rods 2 in the middle positions of the movable die plates 51: and 511. Between said bearing boards 6a, 61) there is journaled a central die plate 7 turnably with upper and lower shafts 8a 8b, both the surf&#39;lces of said central die plate 7 being mold fixing portions. Reference 9 is a rack for rotation which is provided to the upper bearing board 6a to rotate said die plate 7 and actuated with a pressure cylinder, and references II) are bearings provided at the supporting portions of the bearing boards 6a, 6b. Numeral II is a mold releasing cylinder which is provided at the center of the die plate 7 in such manner that pistons Ila, Ilh face the mold fixing surfaces 7a, 7b and the cylinder carried out a mold releasing operation on the side surface on which molding has been finished by the action of said pistons Ila, I ll: through oil pressure Numerals l2 and I3 are pressure oil supply opeiflngs and pressure oil feeding pipes respectively to operate each piston Ila of the mold releasing cylinder II alternately. References I4 and I5 are cooling water supply openings and cooling pipes respectively to feed cooling water to the die plate 7. Reference numerals I6u and [6b. I60 are injection devices which are arranged on the base at the outside positions of said fixed boards Ia, Ih in such a manner that nozzles 17a and l7h, 17c of said injection devices are capable of advancing or retreating of or from injec tion openings 51&#39; and 5d, of said movable die plates 5r, 5/).  
  In the synthetic resin molding machine thus con structed according to the present invention. metallic molds 20, 22 and 2|. 23 are respectively fixed to the front surfaces of the movable die plates 50, 5b and to the mold fixing surfaces 711 7h of said die plate 7, which oppose said front surfaces. Firstly, the mold tightening cylinders 30 are movedforward to press the metallic mold 20 as well as the movable die plate 5a against the metallic mold 2I so as to perform a mold tightening, and the nozzle I7u of the injection molding device Ifiu is moved forward to mold one member through the in jection opening 51&#39; of said die plate 50. After the molding of said one member. if the nozzle [7a of said injecondevice I and the movable die plate 5a are to rented to carry out a mold releasing. at the metallic mold 2| there may be left a mono-colored, halffinished article wherein one member only has been molded. On the other hand, the rack 9 for rotation which is provided in the upper board bearing 6a is operated to turn and revolve by 180 the central die plate 7 which is journaled turnably and revolvably between the bearing boards 6a, 6b with said shafts 8a, 8b. In succession, both the mold tightening cylinders 3a, 3b are advanced to press the metallic molds 20, 22 as well as the movable die plates 5a, 5b against the metallic molds 2 I, 23 (previously 23, 2I to carry out a mold tightening. and then the nozzles 17a and 17b, of the injection devices [6a and I6!), 16c are respectively advaneed. In such way, one member is molded with a pair of metallic molds 20, 21 (previously 23) through the injection opening 56&#39; by one injection device 16a, and at the same time two members of different colors are additionally molded, through the injection openings 5d, 50 to the metallic mold 23 (previously 21) in which only one member has been molded in the previous step by the injection devices 16b, 16c and to the mctall&#39;c mold 22 which is mold tightened under pressure agai st said metallic mold 23. As a result, an article moldec in integrity with three colors is produced in the metallic molds 23 (previously 2l 22.  
  Accordingly, if both the nozzles 17a and 1717, [7C of said injection devices 16a and 16b, 16c and the movable die plates 5a, 5b are retreated to perform a mold releasing, it results in that a three-colored, molded article may be left in one metallic mold 2I and a singlecolored, half-finished article in which only one member has been molded, in the other metallic mold 23. Therefore, if the article only of said metallic mold 21 is released by the mold releasing cylinder ll and the same operation is successively repeated by rotating the cen tral die plate 7 by 180 through the re-action of the rack 9 for,rotation, it results in that an article molded in integrity having three colors is manufactured in succession.  
  The embodiment shown in the drawings explains only the case of a three-colored molded article. In case of molding a four-colored article, however, if two injection openings 56 are provided in one die plate 50 and nozzles of the injection devices towards the same direction as that of mold tightening. Accordingly, it is recognized that the present machine brings about many advantages as a synthetic resin molding machine in the industries.  
 What is claimed is:  
  l. A molding machine for synthetic resin article, comprizing journals provided turnably and revolvably between upper and lower bearing boards, a central die plate whose both sides have been formed into mold fixing surfaces, die plates which move forward and backward by mold tightening cylinders, approachably to and releasably from each of said mold fixing surfaces of the central die plate, to be guided with rods mounted between the upper and lower positions of fixed boards provided on thebase and said bearing boards, and a suitable number of injection devices respectively onto the base at the positipm outside the fixed boards i such a manner t the nozzles of said injection devices capable f advancing and retreating to and from respecfivg ection openings of the movable die plate.  
  A oulding machine according to claim 1, characterized in that there are provided one injection device on one side of said central die plate and two injection evices on the other side.  
  3. A moulding machine according to claim 1, characyerized in that there are two injection devices on both iides of said central die plate.