Oven for the thermal conditioning of preforms and control method of an air cooling device fitted to such an oven

Abstract

An oven ( 10 ) for the heat treatment of preforms and a method for operating an air-cooling device ( 42 ) fitted to such an oven includes controlling elements ( 58 ) to vary the cooling air flow rate onto the body ( 18 ) and bottom ( 20 ) of the preforms ( 12 ) along the heating path.

1 . Oven ( 10 ) for the heat treatment of thermoplastic preforms ( 12 ) each respectively comprising a first part ( 14 ,  16 ) in its definitive shape and a second part ( 18 ,  20 ) intended to be heated by heating means ( 30 ) arranged along at least part of a determined heating path followed by the preforms ( 12 ) travelling through the oven, the said oven ( 10 ) comprising a cooling system ( 36 ) capable respectively of cooling the first parts ( 14 ,  16 ) and the second parts ( 18 ,  20 ) of the preforms, characterized in that the cooling system ( 36 ) comprises at least one cooling device ( 42 ) capable of air-cooling at least the second part ( 18 ,  20 ) of the preforms ( 12 ), the said cooling device ( 42 ) comprising at least ventilation means ( 52 ) capable of delivering a given flow rate of cooling air and means ( 58 ,  64 ) for selectively varying, along the heating path of the preforms ( 12 ), at least the cooling air flow rate delivered by the said ventilation means ( 52 ) for cooling the said second parts ( 18 ,  20 ) of the preforms ( 12 ). 
     
     
         2 . Oven ( 10 ) according to  claim 1 , characterized in that the said means ( 58 ,  64 ) consist of at least one speed variator ( 58 ) associated with at least one of the ventilation means ( 52 ) of the said at least one cooling device ( 42 ) so that the variation in cooling air flow rate along the path is obtained by selectively operating the said speed variator ( 58 ) associated with the said ventilation means ( 52 ) independently of the other ventilation means ( 52 ) of the cooling device ( 42 ). 
     
     
         3 . Oven ( 10 ) according to  claim 2 , characterized in that the speed variator ( 58 ) is operated via at least one operating unit ( 60 ) to act on a drive motor ( 56 ) that drives the said associated ventilation means ( 52 ) so as selectively, along the heating path, to vary the air flow rate delivered for cooling at least the second parts ( 18 ,  20 ) of the preforms ( 12 ). 
     
     
         4 . Oven ( 10 ) according to  claim 1 , characterized in that the means ( 58 ,  64 ) at least consist of shut-off means ( 64 ) so that the variation in cooling air flow rate along the path is obtained by selectively operating each of the shut-off means ( 64 ) independently of the other shut-off means ( 64 ) of the cooling device ( 42 ). 
     
     
         5 . Oven ( 10 ) according to  claim 4 , characterized in that the shut-off means ( 64 ) can be operated selectively in terms of their position so as selectively, along the heating path, to vary the air-flow rate delivered for cooling at least the second parts ( 18 ,  20 ) of the preforms ( 12 ). 
     
     
         6 . Oven ( 10 ) according to  claim 1 , characterized in that the oven ( 10 ) comprises temperature measurement means ( 62 ) capable of measuring the internal temperature and/or the external temperature of the wall of the second part ( 18 ,  20 ) of the preforms ( 12 ) at least at a determined position along the heating path and of supplying at least one signal representative of one of the said measured temperatures or of the gradient corresponding to the difference between the said internal and external temperatures of the wall. 
     
     
         7 . Oven according to  claim 1 , characterized in that the cooling system ( 36 ) comprises at least one operating unit ( 60 ,  70 ) for operating the said at least one cooling device ( 42 ) which is capable of controlling the said means ( 58 ,  64 ) intended selectively along the heating path to vary the air flow rate for cooling at least the second parts ( 18 ,  20 ) of the preforms ( 12 ) so as to set the heat treatment of the preforms ( 12 ) along the heating path through real-time control of the said means ( 58 ,  64 ) of the cooling device ( 42 ). 
     
     
         8 . Oven ( 10 ) according to  claim 1 , characterized in that the oven ( 10 ) is of modular design comprising at least a number [n] of modules (M) in which the said heating means ( 30 ) are mounted arranged along all or part of the heating path, and in that the means ( 58 ,  64 ) for selectively varying the air flow rate for cooling at least the second parts ( 18 ,  20 ) of the preforms ( 12 ) are common to at least two modules (M) designed to form a series and/or parallel unit. 
     
     
         9 . Method for operating a cooling device ( 42 ) which, being fitted to a heat treatment oven ( 10 ) according to  claim 1 , is intended to air-cool at least the second parts ( 18 ,  20 ) of the preforms ( 12 ) travelling through the oven ( 10 ) along a heating path, characterized in that the operating method comprises at least one step consisting in:
 operating the means ( 58 ,  64 ) in order selectively to vary the cooling air flow rate delivered at least to the said second parts ( 18 ,  20 ) of the preforms ( 12 ) along the heating path.   
     
     
         10 . Method according to  claim 9 , characterized in that the method comprises at least one step consisting in:
 measuring the internal temperature and/or the external temperature of the wall of the second part ( 18 ,  20 ) of the preform ( 12 ) so as to produce at least one signal representative of the internal and/or external temperature of the wall or of the gradient corresponding to the difference between the said internal and external temperatures.   
     
     
         11 . Method according to  claim 9 , characterized in that the method comprises at least one setting step consisting in:
 controlling the said means ( 58 ,  60 ) in real time in order, as a function of at least one data item such as at least one signal representative of temperature, to set the air flow rate for cooling at least the second parts ( 18 ,  20 ) of the preforms ( 12 ) which flow rate is delivered variably along the heating path.   
     
     
         12 . Method for heat treating preforms ( 12 ) in an oven ( 10 ) comprising at least one operating step according to  claim 9  which is implemented in combination with at least one of the following setting steps that consist in:
 setting the power of the heating means ( 30 ) so as to vary, along the heating path, the heating power delivered to the second parts ( 18 ,  20 ) of the preforms ( 12 ), particularly so as to establish stabilization zones. 
 
     
     
         13 . Method according to  claim 10 , characterized in that the method comprises at least one setting step consisting in:
 controlling the said means ( 58 ,  60 ) in real time in order, as a function of at least one data item such as at least one signal representative of temperature, to set the air flow rate for cooling at least the second parts ( 18 ,  20 ) of the preforms ( 12 ) which flow rate is delivered variably along the heating path.   
     
     
         14 . Oven ( 10 ) according to  claim 2 , characterized in that the oven ( 10 ) comprises temperature measurement means ( 62 ) capable of measuring the internal temperature and/or the external temperature of the wall of the second part ( 18 ,  20 ) of the preforms ( 12 ) at least at a determined position along the heating path and of supplying at least one signal representative of one of the said measured temperatures or of the gradient corresponding to the difference between the said internal and external temperatures of the wall. 
     
     
         15 . Oven according to  claim 2 , characterized in that the cooling system ( 36 ) comprises at least one operating unit ( 60 ,  70 ) for operating the said at least one cooling device ( 42 ) which is capable of controlling the said means ( 58 ,  64 ) intended selectively along the heating path to vary the air flow rate for cooling at least the second parts ( 18 ,  20 ) of the preforms ( 12 ) so as to set the heat treatment of the preforms ( 12 ) along the heating path through real-time control of the said means ( 58 ,  64 ) of the cooling device ( 42 ). 
     
     
         16 . Oven ( 10 ) according to  claim 2 , characterized in that the oven ( 10 ) is of modular design comprising at least a number [n] of modules (M) in which the said heating means ( 30 ) are mounted arranged along all or part of the heating path, and in that the means ( 58 ,  64 ) for selectively varying the air flow rate for cooling at least the second parts ( 18 ,  20 ) of the preforms ( 12 ) are common to at least two modules (M) designed to form a series and/or parallel unit. 
     
     
         17 . Oven ( 10 ) according to  claim 3 , characterized in that the oven ( 10 ) comprises temperature measurement means ( 62 ) capable of measuring the internal temperature and/or the external temperature of the wall of the second part ( 18 ,  20 ) of the preforms ( 12 ) at least at a determined position along the heating path and of supplying at least one signal representative of one of the said measured temperatures or of the gradient corresponding to the difference between the said internal and external temperatures of the wall. 
     
     
         18 . Oven according to  claim 3 , characterized in that the cooling system ( 36 ) comprises at least one operating unit ( 60 ,  70 ) for operating the said at least one cooling device ( 42 ) which is capable of controlling the said means ( 58 ,  64 ) intended selectively along the heating path to vary the air flow rate for cooling at least the second parts ( 18 ,  20 ) of the preforms ( 12 ) so as to set the heat treatment of the preforms ( 12 ) along the heating path through real-time control of the said means ( 58 ,  64 ) of the cooling device ( 42 ). 
     
     
         19 . Oven ( 10 ) according to  claim 3 , characterized in that the oven ( 10 ) is of modular design comprising at least a number [n] of modules (M) in which the said heating means ( 30 ) are mounted arranged along all or part of the heating path, and in that the means ( 58 ,  64 ) for selectively varying the air flow rate for cooling at least the second parts ( 18 ,  20 ) of the preforms ( 12 ) are common to at least two modules (M) designed to form a series and/or parallel unit.