Methods, apparatus and systems for reducing warpage in polymers with continuous fibers

• US 9,527,250 B2
• Filed: 12/19/2011
• Issued: 12/27/2016
• Est. Priority Date: 12/19/2011
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Motor Engineering & Manufacturing North America Incorporated (Toyota Motor Corporation)
• Inventors: Gandhi, Umesh N.
• Primary Examiner(s): Tucker, Philip
• Assistant Examiner(s): WU, VICKI H
• Application Number:
  US13/330,444
• Publication Number:
  US 20130153121A1
• Time in Patent Office: 1,835 Days
• Field of Search: 156/242
• US Class Current: 1/1
• CPC Class Codes: B29C 70/56 Tensioning reinforcements before or during shaping
• CPC Class Codes: B32B 2262/101 Glass fibres
• CPC Class Codes: B32B 2305/08 Reinforcements
• CPC Class Codes: B32B 2305/10 Fibres of continuous length
• CPC Class Codes: B32B 27/12 next to a fibrous or filamentary layer
• CPC Class Codes: B32B 37/0015 to avoid warp or curl
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree

Abstract

Apparatus, systems and/or methods are provided to substantially reduce warping of a reinforced polymer. For example, by pre-stressing a glass component proportional to the difference between coefficients of linear expansions of glass and polymers, warping may be reduced when the resulting glass-polymer compound is cooled.

Claims

1. A method for reducing the warping of a molded polymer-continuous fiber compound, the method comprising:

determining a first amount of shrinking of a layer of continuous fiber in response to cooling, the first amount of shrinking being greater than zero;

determining a second amount of shrinking of a layer of polymer in response to cooling, the second amount of shrinking being greater than zero;

determining a pre-stress amount that causes the layer of continuous fiber to be dimensionally smaller than the layer of polymer when the layer of continuous fiber is pre-stressed by the pre-stress amount and that is based on a difference between the first amount of shrinking and the second amount of shrinking;

pre-stressing the layer of continuous fiber by approximately the pre-stress amount such that the layer of continuous fiber pre-stressed is dimensionally smaller than the layer of polymer;

heating the layer of polymer;

molding the layer of polymer heated to the layer of continuous fiber pre-stressed;

cooling the layer of continuous fiber pre-stressed and the layer of polymer heated; and

releasing the pre-stress of the layer of continuous fiber pre-stressed that is dimensionally smaller than the layer of polymer when from the pre-stress applied or after a temperature of the molded polymer-continuous fiber compound is at or below a predetermined threshold temperature value such that the layer of continuous fiber shrinks along with the layer of polymer to cause the molded polymer continuous fiber compound to be substantially flat.

2. The method of claim 1, wherein pre-stressing the layer of continuous fiber includes pre-stressing the layer of continuous fiber in two dimensions.

3. The method of claim 1, further comprising determining a degree of pre-stressing based on a coefficient of a linear expansion of a material of the continuous fiber layer of and a coefficient of a linear expansion of a material of the polymer layer of.

4. The method of claim 1, further comprising adding an inorganic filler or a modifier to at least one of the layer of continuous fiber or the layer of polymer.

8. The method of claim 4, wherein at least one of determining the first amount of shrinking or determining the second amount of shrinking is based on properties of the inorganic filler or the modifier.

5. A method of reducing the warping of a molded glass-reinforced polymer, the method comprising:

determining a dimensional difference between a continuous glass fiber tape and a polymer after cooling from a first temperature to a second temperature, based on a coefficient of linear expansion of the continuous glass fiber tape and a coefficient of linear expansion of the polymer;

determining a pre-stress amount that causes the continuous glass fiber tape to be dimensionally smaller than the polymer when the continuous glass fiber tape is pre-stressed by the pre-stress amount;

pre-stressing the continuous glass fiber tape by approximately the pre-stress amount by stretching and holding the continuous glass fiber tape at least one of horizontally or vertically by means of a device so that the continuous glass fiber tape is dimensionally smaller than the polymer;

heating the polymer;

adding the heated polymer to the pre-stressed continuous glass fiber tape to form a fiber-reinforced-polymer (FRP) composite;

molding the FRP composite;

cooling the FRP composite; and

releasing the continuous glass fiber tape pre-stressed that is dimensionally smaller than the polymer from the pre-stress applied when or after a temperature of the FRP composite is at or below a predetermined threshold temperature value such that the continuous glass fiber tape shrinks along with the polymer to cause the FRP composite to be substantially unwarped.

6. The method of claim 5, further comprising determining the pre-stress amount based on a coefficient of a linear expansion of a material of the continuous glass fiber tape and a coefficient of a linear expansion of a material of the polymer.

7. The method of claim 5, further comprising adding an inorganic filler or a modifier to the continuous glass fiber tape or the polymer.

9. The method of claim 7, wherein determining the dimensional difference between the continuous glass fiber tape and the polymer is further based on properties of the inorganic filler or the modifier.

10. The method of claim 5, wherein pre-stressing the continuous glass fiber tape includes stretching and holding the continuous glass fiber tape horizontally and vertically.