Method of Controlling the Opening and Closing of a Blow Mold and Blowing Device for Implementing Same

Abstract

A method of controlling the opening and closing of a book-type blow mold that is used to produce containers from a thermoplastic material, such as PET, by blowing or blow-drawing heated preforms. The mold includes at least two mold halves which can be moved away from one another by rotating the same around a shared fixed pivot pin. The two mold halves are opened asymmetrically on either side of the parting plane thereof and, as a result, the mold half that is open the most forms a larger passage for introducing an auxiliary member, such as a clamp arm, into the mold.

1 . A method for controlling the opening and closing of a blow-molding mold of the hinged mold type for the manufacture of thermoplastic containers, particular PET containers, by blow-molding or stretch-blow-molding heated parisons, said mold comprising at least two mold halves that can be separated from one another by rotation about a fixed common axle of articulation,
 wherein said two mold halves are opened asymmetrically on each side of their parting plane,   whereby the widest-open mold half leaves more space for the introduction into the mold of an auxiliary member such as a gripper arm.   
   
   
       2 . The method as claimed in  claim 1 , wherein said two mold halves are controlled individually so that they open asymmetrically on each side of the parting plane. 
   
   
       3 . The method as claimed in  claim 1 , said two mold halves being controlled jointly by means of two respective link rods having first ends coupled rotationally (via the links) to said respective mold halves and second ends coupled rotationally to one another at a common axle that can move approximately parallel to the parting plane,
 wherein said two link rods have different lengths, the difference in their lengths being related to the difference in the asymmetric angles of opening of the two respective mold halves on each side of the parting plane, and wherein said common axle moves along a path external to the parting plane.   
   
   
       4 . The method as claimed in  claim 1 , said two mold halves being controlled jointly via two respective link rods of substantially the same length and having first ends coupled rotationally by links to said respective mold halves and second ends coupled rotationally to one another at a movable common axle,
 wherein said common axle can move in a path that is inclined with respect to the parting plane, the angle of inclination of the path being related to the asymmetry of opening of said two mold halves on each side of the parting plane.   
   
   
       5 . The method as claimed in  claim 1 , said mold belonging to a rotary molding device of the carousel type moving in a direction of rotation, and the parting plane of the mold running substantially along a radius of the molding device, wherein the rear mold half (considered in the direction in which the molding device rotates) has an angle of opening, with respect to said parting plane, which is greater than that of the front mold half. 
   
   
       6 . The method as claimed in  claim 1 , said mold belonging to a rotary molding device of the carousel type having a direction of rotation, and the parting plane of the mold running substantially along a radius of the molding device, wherein the front mold half (considered in the direction in which the molding device rotates) has an angle of opening, with respect to said parting plane, which is greater than that of the rear mold half. 
   
   
       7 . A molding device for manufacturing thermoplastic containers, particularly PET containers, by blow-molding or stretch-blow-molding heated parisons, said molding device comprising at least one blow-molding mold of the hinged mold type with at least two mold halves which can be separated from one another by rotation about a common axle of articulation under the action of actuating means, said molding device being designed for implementing the method as claimed in  claim 1 ,
 wherein the actuating means are designed in such a way that the two mold halves have respective angles of opening on each side of the parting plane of said mold which are not equal.   
   
   
       8 . The molding device as claimed in  claim 7 , wherein the actuating means comprise two distinct actuating means each functionally associated with a respective one of said two mold halves, and wherein said two actuating means are functionally associated with individual controls, independent of one another, so as to define respective angles of opening of said two mold halves one on each side of the parting plane which are not equal. 
   
   
       9 . The molding device as claimed in  claim 7 , in which the actuating means comprise two link rods having first ends rotationally connected by links respectively to said two mold halves and second ends rotationally connected at a common axle and control means capable of moving said common axle in a path running approximately parallel to the parting plane,
 wherein said two link rods have different lengths and in that the path of the common axle is external to the parting plane, the mold half driven by the shorter link rod having an angle of opening, with respect to the parting plane, which is larger than that of the other mold half.   
   
   
       10 . The molding device as claimed in  claim 9 , wherein the control means comprise a drive arm running transversely to the parting plane and wherein said drive arm has a first end articulated to a fixed axle and an opposite second end articulated to said axle common to the aforesaid link rods. 
   
   
       11 . The molding device as claimed in  claim 7 , in which the actuating means comprise two link rods of substantially the same length and having respective first ends rotationally connected by links to the two mold halves respectively and opposite second ends rotationally connected at a common axle, control means being functionally associated with said common axle in order to move it,
 wherein said control means for controlling the common axle are designed to drive said common axle in a path running approximately transversely to the parting plane and inclined at an angle with respect thereto, the angle of inclination of this path being related to the asymmetry of opening of the two respective mold halves.   
   
   
       12 . The molding device as claimed in  claim 11 , wherein the control means comprise a drive arm running approximately transversely to the parting plane Abut inclined at an angle with respect thereto, and wherein said drive arm has a first end articulated to a fixed axle and an opposite second end articulated to said axle common to the aforesaid link rods. 
   
   
       13 . The molding device as claimed in  claim 7 , built in the form of a rotary device of the carousel type moving in a direction of rotation, the parting plane of the mold running substantially radially, wherein it is the rear mold half (considered in the direction in which the carousel rotates) which has an angle of opening, with respect to the parting plane, which is greater than that of the other mold half. 
   
   
       14 . The molding device as claimed in  claim 7 , built in the form of a rotary device of the carousel type moving in a direction of rotation, the parting plane of the mold running substantially radially, wherein it is the front mold half (considered in the direction in which the carousel rotates) which has an angle of opening, with respect to the parting plane, which is greater than that of the other mold half.