METHOD AND APPARATUS FOR INSPECTING ADHESIVE QUALITY

• US 20100019785A1
• Filed: 07/28/2008
• Published: 01/28/2010
• Est. Priority Date: 07/28/2008
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (General Motors Company)
• Inventors: Chen, Guanlong, Lin, Zongqing, Wang, Pei-Chung, Zhang, Yansong, Lai, Xinmin
• Granted Patent: US 8,878,093 B2
• Time in Patent Office: Days
• US Class Current: 324/696
• CPC Class Codes: B23K 11/115 by means of two electrodes placed opposite one another on both sides of the welded parts
• CPC Class Codes: B23K 11/256 the measured parameter being the inter-electrode electrical resistance
• CPC Class Codes: B23K 11/257 the measured parameter being an electrical current
• CPC Class Codes: B23K 11/258 the measured parameter being a voltage
• CPC Class Codes: G01N 27/048 for determining moisture content of the material

Abstract

A method and apparatus inspect a quality of an adhesive material used for joining a pair of work surfaces during a weld-bonding process. A pair of work pieces are at least partially bonded by a layer of the adhesive material, and the dynamic displacement of one or both electrodes is measured through a duration of the resistance welding process to determine relative moisture content of the adhesive. A control action is executed when the dynamic displacement exceeds a stored threshold value. The apparatus includes a welding device having a pair of electrodes for providing a clamping force and an electrical current necessary for forming the welded joint, a sensor for measuring a dynamic displacement of at least one of the pair of electrodes and/or another portion of the welding device during formation of the welded joint. A controller has an algorithm for determining a relative moisture using the dynamic displacement.

Claims

1. A method for determining a relative moisture content of an adhesive material that is used for joining a pair of work surfaces in conjunction with a resistance welding process utilizing a pair of electrodes, the method comprising:

using the resistance welding process to form a welded joint between the pair of work pieces, the pair of work pieces being at least partially separated by a layer of the adhesive material;

measuring a resistance value corresponding to the electrical resistivity of the adhesive material during the resistance welding process, the resistance value corresponding to the relative moisture content; and

executing a control action when the resistance value exceeds a stored threshold value.

2. The method of claim 1, wherein measuring the resistance value includes measuring a dynamic displacement corresponding to a thermal expansion and contraction of the pair of work surfaces during formation of the welded joint.

3. The method of claim 2, wherein measuring the dynamic displacement includes measuring a depth of an indentation formed by the pair of electrodes in the pair of work surfaces.

4. The method of claim 2, wherein measuring the resistance value includes at least one of directly measuring and calculating the electrical resistance of the adhesive material.

5. The method of claim 1, wherein the resistance welding process is a spot-welding process.

6. The method of claim 1, wherein executing a control action includes at least one of:

activating an indicator or an alarm, sending an electronic message to an external system, and shutting down the resistance welding process.

7. A method for determining a relative moisture content of a welded joint during a weld-bonding process, the method comprising:

measuring a value corresponding to a dynamic displacement of a pair of electrodes during the weld-bonding process;

comparing the value of the dynamic displacement to a stored threshold value to determine the relative moisture content; and

executing a control action when the value of the dynamic displacement exceeds the stored threshold value.

8. The method of claim 7, wherein executing a control action includes testing one of a strength of the welded joint and an actual moisture content of an adhesive material used in the formation of the welded joint.

9. The method of claim 7, wherein executing a control action includes at least one of:

forming additional spot welds, activating an indicator or an alarm, sending an electronic message to an external system, and shutting down the weld-bonding process.

10. The method of claim 7, wherein measuring a value corresponding to a dynamic displacement of a pair of electrodes includes measuring a movement of the pair of electrodes caused by the thermal expansion of the pair of work surfaces during formation of the welded joint.

11. The method of claim 7, wherein measuring a value corresponding to a dynamic displacement of a pair of electrodes includes measuring a distance between the pair of electrodes.

12. An apparatus for determining a relative moisture content of an adhesive material used in forming a welded joint between a pair of adjacent work pieces during a weld-bonding process, the apparatus comprising:

a welding device having a pair of electrodes operable for providing a clamping force and an electrical current necessary for forming the welded joint;

at least one sensor adapted for measuring a dynamic displacement of at least one of the pair of electrodes during formation of the welded joint; and

a controller having an algorithm for determining a relative moisture content of the adhesive material using the measured dynamic displacement;

wherein the controller is operable for executing a control action when the relative moisture content exceeds a threshold value.

13. The apparatus of claim 12, wherein the controller is operable for determining a resistance value of the adhesive material to the electrical current as the electrical current passes between the pair of electrodes, and for determining the relative moisture content at least in part using the resistance value.

14. The apparatus of claim 12, wherein the welding device is configured as a spot-welding device, and wherein the pair of adjacent work pieces are a pair of sheet metal portions of a vehicle.

15. The apparatus of claim 12, wherein the control action is selected from the group consisting of:

activating an indicator or an alarm, testing the welded joint, sending an electronic message to an external system, and shutting down the weld-bonding process.