MOLD DEVICE FOR MOLDING A PREFORM

Abstract: A mold device for molding a preform in which a lip mold (12) is provided on the lower surface of a tranfer plate (3) rotatably mounted above a machine bed (1), and the lip mold is moved up and down together with a core mold (13) to carry out opening and closing a mold without vertically moving the cavity mold (6) with respect to the lip mold or without vertically moving the transfer mold together with the lip mold with respect to the fixed cavity mold.

Description: BACKGROUND OF THE INVENTION Field of the Invention This invention relates to a mold device for molding a preform incorporated into a rotary type injection blow molding machine. Description of the Prior Art A molding machine for continuously carrying out a series of operation from injection molding of a preform to blow molding of a container such as a bottle has been already well known in Japanese Patent Publication No. 53-22096. In a mold device for molding a preform disposed in this known molding machine, a cavity mold is moved up and down with respect to a neck mold provided underside of an upper base plate above a machine bed to open and close a mold. Therfore, when the mold is opened, a nozzle of an injection apparatus has to be released, which entails a longer cycle of injection molding. In addition, the nozzle brings forth stringiness, leakage or the like according to the kind of resin. In view of the foregoing, an attempt has been made so that a cavity mold is secured onto a machine bed, and a neck mold is moved up and down. In this case, the neck mold has to be moved up and down together with a transfer plate. This poses another problems such that the apparatus becomes complicated in terms of other operating portions and that it takes time to rotate the transfer plate immediately after opening of the mold to transfer a preform together with the neck mold to a next operating portion. OBJECTS AND SUMMARY OF THE INVENTION This invention has been achieved in order to solve the above-described prior art problems. It is an object of the present invention to provide a mold device for molding a preform in which a cavity mold and a transfer plate are not moved up and down but a lip mold serving as a molding mold and a retaining mold in the outer periphery of an opening of a preform may be moved up and down to open and close a mold. It is a further object of this invention to provide a new mold device for a rotary molding machine in which both a cavity mold and a blow mold for molding a preform may be disposed on a machine bed despite the fact that a lip mold is mounted movably up and down on the lower surface of a transfer plate. For achieving the above-described objects, this inventions provides an arrangement wherein a cavity mold is secured onto a machine bed, a lip mold serving as a retaining mold for molving an outer peripheral portion of an opening of a preform at an upper part of the cavity mold together with a mold place plate is disposed on the lower surface of a transfer plate underside of an upper base plate, and a core mold extending through holes formed in the upper base plate and transfer plate to be fitted into the retaining mold is arranged upwardly of the upper base plate, said lip mold being resiliently mounted on the transfer plate by means of a vertical shaft and a spring member so that the lip mold may be moved up and down with respect to the cavity mold by the core mold. The present invention provides a further arrangement wherein said mold place plate is conected to lower ends of a plurality of vertically movable vertical shafts extending through the transfer plate, and a spring member for always urging the mold place plate together with the lip mold against the lower surface of the transfer plate through the vertical shafts is provided between a connecting plate provided over the upper ends of the vertical shafts and said transfer plate. In this way, when the lip mold at the under surface of the transfer plate, together with the core mold inserted while extending through the holes from above of the upper base plate, is urged against the transfer plate by the vertical shafts and the spring member so that the former may be moved to be opened and closed with respect to the cavity mold, the opening and closing of the mold can be done merely by upward and downward movement of the lip mold, and the cavity mold may be fixed. Therefore, since the injection device may be always placed in nozzle-touching state thus enhancing the molding cycle. In addition, no stringiness or leakage of resin occurs. Since a clamping device may be provided on the core mold side alone, the structure of the injection molding operating portion may be simplified. In the case where the lip mold at the under surface of the transfer plate, together with the core mold inserted while extending through the holes from above of the upper base plate, is urged against the lower surface of the transfer plate by the vertical shafts extending through the transfer plate and the spring member for always upwardly biasing the vertical shaft so that the former may be moved to be opened and closed with respect to the cavity mold, not only the cavity mold but the blow mold are not moved up and down but may be installed on the lower base plate since the vertical shafts do not disturb the transfer plate in rotation in connection with the blow mold. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional front view of a mold device for molding a preform according to the present invention; FIG. 2 is a longitudinal sectional side view; FIG. 3 is a longitudinal sectional view during the injection molding; FIG. 4 is a longitudinal sectional side view of a temperature-control operating portion; FIG. 5 is a longitudinal sectional side view of an orientation and blow operating portion; FIG. 6 is a longitudinal sectional front view showing the upper portion of a rotary type injection blow molding machine provided with a mold device for molding a preform in accordance with a further embodiment; FIG. 7 is a longitudinal sectional view of a mold device in a preform molding operating portion; FIG. 8 is a longitudinal sectional side view thereof; and FIG. 9 is a longitudinal sectional side view in the state where a mold is opened. DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawings, reference numeral 1 designates a machine bed, and 2 denotes an upper base plate provided above the machine bed, and a transfer plate 3 is rotatably mounted on the underside of the upper base plate. While the overall construction of the molding machine is omitted in the drawings, the upper base plate is secured to a plurality of supports in the periphery of the machine bed, and the transfer plate 3 is designed so that it is rotated and moved intermittently through 90° by a rotary device provided in the center of the upper base plate 2. These upper base plate 2 and transfer plate 3 are formed with holes 4 and 5 having a required diameter which are superposed each other at their stop positions, and the positions of the upper base plate 1 formed with the holes constitute operating portions including molding, temperature-controlling, orientation and blow molding and releasing of a preform, and respective apparatuses therefor are arranged. FIG. 1 is a longitudinal sectional view showing a mold device for molding a preform, in which a cavity mold 6 for molding an outer surface of a bottom of a preform is sectured together with a runner mold 7 to the machine bed 1. The required number of vertical shafts 8 are projected vertically from a member 10 in a paired relation with the holes 5 spaced apart on the lower surface of the transfer plate 3, and mold place plates 9 vertically movably extend through th vertical shafts 8, 8, respectively. A spring member 11 is provided between the mold place plate 9 and a flange 8a at the lower end of the vertical shaft, the mold place plate 9 being always biased toward the transfer plate under the pressure of the spring. A lip mold serving as a retaining mold for forming an outer peripheral portion of an opening of a preform is mounted on the mold place plate 9 and set to a position where the lip mold is closed with respect to the cavity mold 6 directly below the hole 5. While not shown in the drawing, the lip mold 12 comprises a split mold, which is opened and closed laterally together with the mold place plate 9. A core mold 13 for molding an inner surface of a preform is connected to a member 14 at the forward end of a piston of a clamping cylinder (not shown) provided at the upper part of the support of the upper base plate 2. The forward end surface of the core mold 13 constitutes a mold surface 15 for forming a cavity together with the cavity mold 6 and lip mold 12, and a shoulder 16 is formed in the upper periphery of the mold surface 15 so that the shoulder may contact with the upper surface of the lip mold 12. Mounted on both sides of the core mold of the member 14 are pressing shafts 17 which extend through holes formed on both sides of the holes 4 and 5 and come into contact with the mold place plate 9. Reference numeral 18 designates a guide pin. In the above-described construction, where the transfer plate 3 stops and the holes 4 and 5 are superposed each other, when the core mold 13 together with the member 14 is moved in a mold-closing direction by the clamping cylinder, the core mold 13 reaches the lip mold 12 from the holes 4 and 5, the mold surface 15 at the forward end thereof occupies a position with the lip mold 12, and the shoulder 16 comes into contact with the upper surface of the lip mold 12. At that time, the pressing shaft 17, which has moved down along with the core mold 13, comes into contact with the mold place plate 9 to downwardly move the lip mold 12 together with the core mold 13 to the cavity mold 6 through the mold place plate 9. Thereby, the cavity mold 6, the lip mold 12 and the core mold 13 are closed to form a cavity for a flat preform. After the molds have been closed, a clamping force is applied, and molten resin is poured into the cavity from the injection apparatus 19 always in nozzle-touching with the gate of the hot runner mold 7 to mold a flat preform 20. Thereafter, when the core mold 13 is moved upward, the lip mold 12 is also returned under the spring pressure to the lower surface of the transfer plate 3 while being in contact with the shoulder 16 at the forward end of the core mold. At that time, since the open peripheral edge of the preform 20 is held between the core mold surface 14 and the lip mold 12 surface, it is released from the cavity mold 6 and moved together with the lip mold 12 toward the transfer plate. After the mold place plate 9 has been placed in contact with the lower surface of the transfer plate, the core mold 13 is slipped out of the lip mold 12 and returned to its original position, i.e., the upper portion of the upper base plate 2. As the result, the preform 20 is left on the lip mold as shown by the chain lines in FIG.1. The preform 20 together with the lip mold 12 is transferred while maintaining that state to the subsequent operating portion by rotation of the transfer plate 3. FIG. 4 is a longitudinal sectional view of a temperature-control operating portion which includes a temperature control pot 22 connected to a cylinder device 21 provided on the machine bed 1 and disposed movably up and down and a vertically movable temperature control core 23 disposed on the upper base plate 2, which holds the preform 20 between it and the lip mold 12 for temperature control. The preform 20 after having been subjected to temperature control is further transferred to the succeeding operating portion by rotation of the transfer plate 3. FIG. 5 shows the orientation and blow molding operating portion in longitudinal section, which includes a blow mold 24 arranged movably up and down on the machine bed 1 and a blow core 25 provided on the upper base plate 2. Reference numeral 26 designates an elevating cylinder, and 27 designates a piston. The blow mold 26 is opened and closed inwardly and outwardly by the cylinder device (not shown), and the blow core 25 is internally provided with an orientation rod 29, and brought into abutment with the lip mold 12 fromthe holes 4 and 5 to orient the preform 20 to the bottom of the mold and expand it to the mold face of the cavity, thus molding a container 30 having a predetermined shape as indicated by the chain lines. After the mold has been opened, the mold 26 is moved down to the position not to contact with the vertical shaft 8, and the molded container 30 is fed to the succeeding operating station by rotation of the transfer plate 3. The lip mold 12 with the container 30 released at said operating portion is again fed to the injection molding operating portion. FIG. 6 and thereafter drawings show a device according to a second embodiment incorporated into a rotary type injection blow molding machine. A lower base plate 102 is placed on and secured to a machine bed 101. Reference numeral 103 designates an upper base plate provided above the machine bed, and a transfer plate 104 is rotatably mounted on the underside of the upper base plate. The upper base plate 103 is secured to a plurality of supports 105 in the periphery of the machine bed. The transfer plate 114 is designed so that it is intermittently rotated and moved through 90° by a rotary device 106 provided in the center of the upper base plate 103. These upper base plate 103 and transfer plate 104 are formed with holes 107 and 108 having a required diameter which are superposed each other at their stop positions, and the positions of the upper base plate 103 formed with the holes constitute operating portions including molding, temperature-controlling, orientation and blow molding and releasing of a preform, and respective apparatuses therefore are arranged. A cavity mold 109 for molding an outer surface of a bottom of a preform together with a hot runner mold 110 is secured onto the lower base plate 102 in the molding operating portion. A blow mold 111 is installed closeably in a horizontal direction on the lower base plate 102 in the orientation and blow molding portion. Vertical shafts 112 are provide parallel to each other in a paired relation with the hole 108 spaced apart in a circumferential direction on the undersurface of the holes of the transfer plate 104. A mold place plate 114, which is opened and closed inwardly and outwardly, is mounted on the lower end of the vertical shaft 112 through a guide member 113. The vertical shaft 112 is integrally connected by connecting plates 115 provided over the upper end in a paired relation, and a spring member 117 is compressively encased in a receiving tube 116 extending through the transfer plate 104 underside of the connecting plate 115. The upper end of the spring member 117 contacts with the connecting plate 115 to always upwardly urge the pair of vertical shafts 112 through the connecting plate 115 so that the mold place plate 114 mounted on the lower end of the vertical shaft 112 is pressed against the lower surface of the transfer plate 104. A retaining and lip mold 118 for molding an outer peripheral portion of an opening of a preform comprises a pair of split molds, each of which is mounted on the central portion of the mold place plate 114 and set to be opened and closed together with the mold place plate 114 directly below the hole 108 of the transfer plate 104. A core mold 119 for molding an inner surface of a preform is mounted on the lower side of a clamping member 121 over the upper ends of a plurality of vertical clamping rods 120 which extend through the transfer plate 104 and are vertically positioned, the core mold 119 being positioned upwardly of the holes 107 and 108. The forward end surface of the core mold 119 fits into the lip mold 118 to constitute a mold surface 119a forming a cavity together with the cavity mold 109. A shoulder 119b is formed in the upper periphery of the mold surface 119a into contact with the upper surface of the lip mold 118. In the above-described construction, where the transfer plate 104 stops and the holes 107 and 108 are superposed each other, when the core mold 119 together with the clamping mold 120 is moved in a mold-closing direction by the clamping cylinder 122 on the underside of the lower base plate 102, the core mold 119 reaches the lip mold 118 from the holes 107 and 108, the mold surface 119a at the forward end is fitted into the lip mold 118 and the shoulder 119b comes into contact with and press the upper surface of the lip mold 118. Thereby the mold place plate 114 is moved downward together with the vertical shafts 112 against the spring member 117 and comes into contact with the upper surface of the cavity mold 109. The cavity mold 109, the lip mold 118 and the core mold 119 are closed. After the mold has been closed, a clamping force is applied, and molten resin is poured into the cavity from an injection apparatus (not shown) always placed in nozzle-touching with the gate of the hot runner mold 110 to mold a flat preform 123. Thereafter, when the mold is opened by the clamping cylinder 122 to move the core mold 119 upward, the mold place plate 114 together with the vertical shafts 112 is also returned under the spring pressure to the lower surface of the transfer plate 4 while the lip mold 118 maintains in contact with the shoulder 119b of the core mold. At that time, since the open peripheral edge of the preform 123 is in the state held between the core mold surface 119a and the mold surface of the lip mold 118, it is released from the cavity mold 109 and moved together with the lip mold 118 toward the transfer plate. After the mold place plate 114 has been placed in contact with the lower surface of the transfer plate, the core mold 119 is slipped out of the lip mold 118 and returned to its original position, i.e. above the upper base plate 103. As the result, the preform 122 is left on the lip mold 118 as indicated by the chain lines in FIG. 9. The preform 122 together with the lip mold 118 is transferred, while maintaining that state, to the orientation and blow molding operating portion via the temperature control operating portion by rotation of the transfer plate 103. In the orientation and blow molding operating portion, a blow core 124 having an end shape similar to the core mold 119 is provided above the upper base plate 103. This blow core 124 is connected to an elevating device 126 in the form of an air cylinder 125, and urges the lip mold 118 together with the mold place plate 114 against the spring member 117 upon the upper surface of the closed blow mold 111, by the operation similar to the core mold 119. The preform 123 is axially oriented by means of an orientation rod 127 in the center of the blow core 124 and is radially expanded by air blow from the periphery of the orientation rod to mold a biaxially oriented container (not shown). The returning of the lip mold 118 to the lower surface of the transfer plate after molding is automatically effected under the spring pressure of the spring member 117 caused by the return of the opened blow core 124, and with this return, the container is also transferred toward the transfer plate in a state where the opening thereof is held by the lip mold 118. Then, the container is transferred to the succeeding release operating portion while being held by the lip mold 118 by rotation of the transfer plate 104. While the illustrated preform is flat, it is noted that other shapes may be employed for the preform. Moreover, the moving dimension of the lip mold can be the range of securing a space capable of transferring the preform together with the lip mold when the respective operating portions are opened. While in the above-described embodiment, a description has been made of molding a single preform, it is to be noted that a plurality of preforms may be simultaneously molded.

Claims: A mold device for molding a preform, in a mold for a rotary molding machine comprising a cavity mold (6 ; 109) for molding a preform installed on a machine bed (1 ; 101) so that said cavity mold is directed upwardly, a retaining and lip mold (12 ; 118) mounted together with a mold place plate (9 ; 114) on the lower surface of a rotatable transfer plate (3 ; 104) above the machine bed and being closed relative to said cavity mold, and a core mold (13 ; 119) which extends through said transfer plate and being fitted into the lip mold, said mold device being characterized in that said lip mold (12 ; 118) together with said core mold (13 ; 119) are disposed movably with respect to said cavity mold (6 ; 109) and are pressed against said transfer plate (3 ; 104) by use of vertical shafts (8 ; 112) and a spring member (11 ; 117). The mold device according to claim 1, wherein the required number of vertical shafts (8) are projected from the lower surface of said transfer plate (3) with holes (5) spaced apart, the mold place plate having the lip mold is vertically movably extended through said vertical shaft, and a spring member (11) for always urging the mold place plate together with the lip mold against the lower surface of the transfer plate is provided between the mold place plate (9) and the lower end of the vertical shaft (8). The mold device according to claim 1, wherein the vertical shafts (112) are vertically movably extended through the transfer plate (104) in a paired relation with the holes (108) spaced apart, said vertical shafts being integrally connected by connecting plates (115) at the upper end projected on the transfer plate (104), a guide member (113) is provided over the lower end projected on the underside of the transfer plate, said mold place plate (114) being mounted over said guide member (113) so that said mold place plate may be moved divisionally in inward and outward directions, and a spring member (117) for always pressing the mold place plate (114) together with the lip mold (118) against the lower surface of said transfer plate through said vertical shafts is provided between said connecting plate and said transfer plate. The mold device according to claim 3, wherein said spring member (117) comprises a coil spring, said spring being encased in a receiving tube which extends through said transfer plate. The mold device according to claim 1, wherein the forward end surface of said core mold (119) comprises a mold surface (119a) which fits into the lip mold (118) to form a cavity together with said cavity mold (109), and the upper peripheral portion of the said mold surface (119a) is formed into a shoulder (119b) in contact with the upper surface of said lip mold (118). The mold device according to claim 1, wherein said cavity mold (109) is secured onto the machine bed together with a hot runner mold (110).

Inventors: FUKUNISHI, YOSHIHIRO NISSEI ASB MACHINE CO.,LTD., KOGA, KOUHEI NISSEI ASB MACHINE CO.,LTD., KOSUGE, SATORU NISSEI ASB MACHINE CO.,LTD., NAKAMURA, YOSHINORI NISSEI ASB MACHINE CO.,LTD.
Applicants: NISSEI ASB MACHINE CO., LTD.
Application year: 1986
Main classification: B29C45
IPC codes: B29C49, B29C45