System and method for vacuum bag fabrication

Abstract

A system and method for vacuum bag assembly fabrication via the vacuum bag method that reduces the amount of trapped air. The inventive system includes a chamber adapted to contain a vacuum bag and first and second evacuating mechanisms. The first evacuating mechanism serves to evacuate the bag and vent to atmosphere. The second evacuating mechanism serves to evacuate and vent the chamber to atmosphere. Thus, generally, the inventive method includes the steps of placing a vacuum bag lay up in an air tight chamber; and evacuating the vacuum bag lay up and the air tight chamber at the same time. In practice, the assembly would consist of at least two components and a heat curable composition. The components can be parts to be bonded together or layers of cloth to be made into a laminate. In this case, the heat curable composition would be a catalyzed adhesive or resin.

What is claimed is:  
     
         1 . An improved system of vacuum bag fabrication, said system comprising: 
 a chamber means adapted to contain a vacuum bag;    a first evacuating means for evacuating and venting said vacuum bag to atmosphere; and    a second evacuating means for evacuating and venting said chamber to atmosphere.    
     
     
         2 . The invention of  claim 1  in which said first and second evacuating means are combined.  
     
     
         3 . A system for fabricating an assembly of at least two components and a heat curable composition, said system comprising: 
 a vacuum bag lay up; said lay up including said components and said curable composition;    an air tight chamber;    a second evacuating means for evacuating and venting to atmosphere said vacuum bag lay up and said air tight chamber;    a curing means for curing said curable composition; and    a moving means for moving said vacuum bag lay up from said air tight chamber to said curing means.    
     
     
         4 . The invention of  claim 3  in which said first and second evacuating means are combined.  
     
     
         5 . The invention of  claim 3  in which said components are fabrics and said heat curable composition is a catalyzed resin.  
     
     
         6 . The invention of  claim 3  in which said heat curable composition is a catalyzed adhesive.  
     
     
         7 . The invention of  claim 3  in which said curing means is capable of subjecting said curable composition to sufficient heat for a sufficient time to effect complete cure with optimum interlaminar bond strength.  
     
     
         8 . The invention of  claim 3  in which said curing means is capable of: 
 increasing temperature at a fast rate to cure temperature for said curable composition and maintaining said cure temperature for a sufficient time to effect complete cure.  
 
     
     
         9 . The invention of  claim 8  in which said fast rate is about 8-12° C. per minute.  
     
     
         10 . A method of fabricating an assembly comprising the steps of: 
 placing a vacuum bag lay up in an air tight chamber; and    evacuating said vacuum bag lay up and said air tight chamber at the same time.    
     
     
         11 . A method of fabricating an assembly of at least two components and a heat curable composition comprising the steps of: 
 a) making a vacuum bag lay up; said lay up including said components and said curable composition;    b) placing said vacuum bag lay up in an air tight chamber;    c) evacuating said vacuum bag lay up and said air tight chamber at the same time;    d) maintaining vacuum on said vacuum bag lay up and said air tight chamber for a first short period;    e) venting said chamber to atmosphere;    f) maintaining vacuum on said vacuum bag lay up for a second short period;    g) moving said vacuum bag lay up to an oven;    h) curing said curable composition;    i) venting said vacuum bag lay up to atmosphere; and    j) removing said assembly from said vacuum bag lay up.    
     
     
         12 . The invention of  claim 11  in which said components are fabrics and said heat curable composition is a catalyzed resin.  
     
     
         13 . The invention of  claim 11  in which said heat curable composition is a catalyzed adhesive.  
     
     
         14 . The invention of  claim 11  in which said first short period is approximately 30 minutes.  
     
     
         15 . The invention of  claim 11  in which said second short period is approximately 10 minutes.  
     
     
         16 . The invention of  claim 11  in which said step of curing comprises subjecting said curable composition to sufficient heat for a sufficient time to effect complete cure with optimum interlaminar bond strength.  
     
     
         17 . The invention of  claim 11  in which said step of curing comprises the steps of: 
 a) increasing temperature at a fast rate to cure temperature for said curable composition; and  
 b) maintaining said cure temperature for a sufficient time to effect complete cure;  
 whereby adequate but less than optimum interlaminar bond strength is developed so that, if necessary, said components may be easily reworked.  
 
     
     
         18 . The invention of  claim 17  in which said fast rate is about 8-12° C. per minute.  
     
     
         19 . A system for curing a curable composition for easy rework, said system comprising an oven capable of: 
 a) increasing temperature at a fast rate to cure temperature for said curable composition; and    b) maintaining said cure temperature for a sufficient time to effect complete cure; 
 whereby curing said curable composition in said oven develops adequate but less than optimum interlaminar bond strength in said curable composition.  
   
     
     
         20 . The invention of  claim 19  in which said fast rate is about 8-12° C. per minute.  
     
     
         21 . A method of curing a curable composition for easy rework, said method comprising the steps of: 
 a) increasing temperature at a fast rate to cure temperature for said curable composition; and    b) maintaining said cure temperature for a sufficient time to effect complete cure; 
 whereby adequate but less than optimum interlaminar bond strength is developed.  
   
     
     
         22 . The invention of  claim 21  in which said fast rate is about 8-12° C. per minute.