Method of making a fastening device for visually indicating tension

• US 7,958,614 B2
• Filed: 10/09/2007
• Issued: 06/14/2011
• Est. Priority Date: 10/09/2007
• Status: Active Grant

• Current Assignee: Stress Indicators Incorporated
• Original Assignee: Stress Indicators Incorporated
• Inventors: Popenoe, Charles H.
• Primary Examiner(s): Cozart; Jermie E
• Application Number:
  US11/869,266
• Publication Number:
  US 20090092457A1
• Time in Patent Office: 1,344 Days
• Field of Search: 294/46, 294/52, 295/251.1, 295/251.3, 411/13, 411/14, 156/165, 156/275.5, 156/275.7, 156/293
• US Class Current: 29/446
• CPC Class Codes: F16B 31/025 with a gauge pin in a longitudinal bore in the body of the bolt
• CPC Class Codes: G01L 5/243 using washers
• CPC Class Codes: Y10T 29/49863 with prestressing of part
• CPC Class Codes: Y10T 29/49874 Prestressing rod, filament or strand

Abstract

The present invention relates to fasteners and more specifically to a fastener adapted to visually indicate tension, and method of making thereof.

Claims

1. A method of making a fastening device adapted to visually indicate tension in the fastening device through changes in color or brightness comprising the steps of:

fitting an actuating means to a fastening device, wherein said actuating means responds in a predetermined manner to a displacement between first and second points in said fastening device, wherein said actuating means comprises a top surface;

attaching a colored indicator portion to the top surface of said actuating means;

providing an indicator window, said indicator window being transparent to light capable of curing light curable adhesive, said indicator window having top and bottom surfaces;

providing a window mount means attached to the fastening device in axial relationship with said actuating means for holding and limiting the movement of said indicator window between an upper shoulder and a lower shoulder;

providing a biasing means for resiliently biasing said colored indicator portion and said indicator window towards each other;

providing a means for absorbing an initial portion of the relative displacement between said first and second points until a preselected displacement has occurred, and using subsequent displacement to vary the distance between said indicator window and said colored indicator portion;

providing a flexible indicator means positioned between said indicator window and said colored indicator portion for altering the amount of light transmitted to said indicator window from said colored indicator portion, whereby the observed color change of the indicator will be concentrated in a selected portion of the total displacement change between said first and second points, said flexible indicator means defines a top surface and a bottom surface;

applying a predetermined tensile force to elongate said fastening device;

attaching the top portion of said actuating means to the bottom surface of said flexible indicator means by application of a first layer of light curable adhesive between the top surface of said actuating means and the bottom surface of said flexible indicator means;

attaching the top surface of said flexible indicator means to the bottom surface of said indicator window by application of a second layer of light curable adhesive between said top surface of said flexible indicator means and said lower surface of said indicator window;

applying an external force to position said indicator window against said lower shoulder; and

transmitting light capable of curing said first and second layers of light curable adhesive through said indicator window to cure said first and second layers of light curable adhesive while said fastening device is elongated under tension.

2. The method for producing fastening devices adapted to visually indicate tension according to claim 1, wherein the fastening device is a bolt.

3. The method for producing fastening devices adapted to visually indicate tension according to claim 1, wherein the fastening device is a stud.

4. The method for producing fastening devices adapted to visually indicate tension according to claim 1, wherein said first and second layers of light curable adhesive comprise of light curable silicone adhesive.

5. The method for producing fastening devices adapted to visually indicate tension according to claim 1, wherein the step of transmitting light capable of curing said first and second layers of light curable adhesive through said indicator window comprises the step of transmitting visible light through said indicator window.

6. The method for producing fastening devices adapted to visually indicate tension according to claim 1, wherein the step of transmitting light capable of curing said first and second layers of light curable adhesive through said indicator window comprises the step of transmitting ultraviolet light through said indicator window.