RESISTANCE WELDING METHOD, RESISTANCE-WELDED MEMBER AND CONTROL APPARATUS FOR RESISTANCE WELDER, RESISTANCE WELDING EVALUATION METHOD, AND RESISTANCE WELDING EVALUATION PROGRAM

• US 20120248086A1
• Filed: 11/16/2010
• Published: 10/04/2012
• Est. Priority Date: 11/18/2009
• Status: Abandoned Application

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Watanabe, Goro, Ishii, Yasuhiro, Sato, Yasumoto, Kitayama, Tsunaji, Takao, Hisaaki, Teshima, Hideki, Uchida, Keisuke, Onda, Takahiro
• Application Number:
  US13/510,447
• Publication Number:
  US 20120248086A1
• Time in Patent Office: Days
• US Class Current: 219/162
• 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 11/252 using digital means
• 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

Abstract

In a resistance welding method, by controlling the power amount from a melting start time onward, the weld quality may be stabilized efficiently, even when a disturbance is present, because of the correlation between the amount of power input from the melting start start time and a resulting nugget. The resistance welding method includes: pressing an electrode against a workpiece; inputting power to the workpiece through the electrode to subject the workpiece to Joule heating; detecting the melting start time, which is the time at which at least a portion of the faying portion of a workpiece starts to melt when subjected to Joule heating; calculating a first power amount input into the workpiece from the melting start time; and determining whether the first power amount has reached a first set value; and continuing the Joule heating until the first power amount reaches the first set value.

Claims

1. A resistance welding method for forming a nugget by causing a faying portion to melt and solidify, comprising:

pressing an electrode against a workpiece;

subjecting the workpiece to Joule heating by inputting power through the electrode into the workpiece;

detecting a melting start time, which is a time at which at least a portion of a faying portion of the workpiece starts to melt;

calculating a first power amount, which is an integrated value of the power input into the workpiece via the electrode from the melting start time;

determining whether the first power amount or a welding index value that indexes a welding condition of the faying portion corresponding to the first power amount has reached at least a first set value; and

continuing the Joule heating from the melting start time until the first power amount or the welding index value reaches at least the first set value.

2. The resistance welding method according to claim 1, wherein detecting the melting start time further comprises:

calculating a second power amount, by integrating the total power input into the workpiece, in accordance with an elapsed time from an energization start time, which is a time at which energization of the electrode for Joule-heating the faying portion begins; and

determining the melting start time as a time at which the second power amount reaches at least a melting start power amount, which is a power amount input until at least a part of the faying portion actually begins to melt and is determined in advance in accordance with the elapsed time from the energization start time, or a second set value set on the basis of the melting start power amount.

3. The resistance welding method according to claim 1, wherein the Joule heating of the workpiece includes modifying a heating parameter of the workpiece based on whether the first power amount or the welding index value has reached at least the first set value.

4. A workpiece that has been welded using the resistance welding method according to claim 1.

5. A control apparatus for a resistance welder that includes an electrode that contacts an external surface of a workpiece and a power supply apparatus that supplies a current to the electrode for Joule-heating a faying portion of the workpiece, the control apparatus comprising:

a melting start time detection unit that detects a melting start time, which is a time at which at least a portion of the faying portion starts to melt when subjected to Joule heating;

a first power amount calculation unit that calculates a first power amount, by integrating the total power input into the workpiece via the electrode from the melting start time;

a first determination unit that determines whether the first power amount or a welding index value that indexes a welding parameter of the faying portion that corresponds to the first power amount has reached at least a first set value; and

a heating unit that performs the Joule heating from the melting start time until the first power amount or the welding index value reaches at least the first set value.

6. A resistance welder comprising:

an electrode that is pressed against a workpiece;

a power supply apparatus that supplies a current to the electrode for Joule-heating a faying portion of the workpiece; and

the control apparatus according to claim 5.

7. A control method for a resistance welder that includes an electrode, which contacts an external surface of a workpiece and a power supply apparatus that supplies a current to the electrode for Joule-heating a faying portion of the workpiece, the method comprising:

detecting a melting start time, which is a time at which at least a portion of the faying portion starts to melt while being subjected to Joule heating by a power input into the workpiece from the electrode;

calculating a first power amount, by integrating the total power input into the workpiece via the electrode from the melting start time;

determining whether the first power amount or a welding index value that indexes a welding condition of the faying portion corresponding to the first power amount has reached at least a first set value; and

continuing the Joule heating from the melting start time until the first power amount or the welding index value reaches at least the first set value.

8. A control program for a resistance welder that controls a computer to execute the control method for a resistance welder according to claim 7.

9. A resistance welding evaluation method, comprising:

pressing an electrode against a workpiece;

subjecting the workpiece to Joule heating by inputting power through the electrode into the workpiece;

detecting a melting start time, which is a time at which at least a portion of a faying portion of the workpiece starts to melt;

calculating a first power amount, by integrating the total power input into the workpiece via the electrode from the melting start time; and

estimating a welding parameter of the faying portion based on the first power amount.

10. The resistance welding evaluation method according to claim 9, wherein the welding parameter estimated is a size of a nugget, which is formed when the faying portion melts and solidifies, the size of the nugget is estimated based on the first power amount.

11. The resistance welding evaluation method according to claim 9, wherein detecting the melting start time further comprises:

calculating a second power amount, by integrating the total power input into the workpiece, in accordance with an elapsed time from an energization start time, which is a time at which energization of the electrode for Joule-heating the faying portion begins; and

determining the melting start time as a time at which the second power amount reaches at least a melting start power amount, which is a power amount input until at least a part of the faying portion actually begins to melt and is determined in advance in accordance with the elapsed time from the energization start time, or a second set value set on the basis of the melting start power amount.

13. A resistance welding evaluation program that controls a computer to execute the resistance welding evaluation method according to claim 9.

12. A resistance welding evaluation method, comprising:

calculating a second power amount, by integrating the total power input into a workpiece from an electrode pressed against the workpiece, in accordance with an elapsed time from an energization start time, which is a time at which energization of the electrode for Joule-heating a faying portion of the workpiece using the power input from the electrode begins; and

determining a melting start time as a time at which the second power amount reaches at least a melting start power amount, which is a power amount input until at least a part of the faying portion actually begins to melt and is determined in advance in accordance with the elapsed time from the energization start time, or a second set value set based on the melting start power amount,

wherein the melting start time at which at least a portion of the workpiece to be resistance-welded begins to melt is detected.

14. A resistance welding evaluation program that controls a computer to execute the resistance welding evaluation method according to claim 12.