Method and apparatus for automatically adjusting air pressure in a pneumatic weld head

• US 6,294,750 B1
• Filed: 08/31/1999
• Issued: 09/25/2001
• Est. Priority Date: 06/13/1997
• Status: Expired due to Term

• Current Assignee: Amada Miyachi America, Inc. (Amada Company Limited)
• Original Assignee: Miyachi Unitek Corp. (Amada Company Limited)
• Inventors: Al-Nabulsi, Talal M.
• Primary Examiner(s): Shaw, Clifford C.
• Application Number:
  US09/387,076
• Time in Patent Office: 756 Days
• Field of Search: 219/86.51, 219/110, 219/85.19, 219/86.22, 219/86.41, 219/86.61, 219/89, 219/91.1
• US Class Current: 219/85.22
• CPC Class Codes: B23K 11/255 the measured parameter being a force B23K11/253 takes precedence
• CPC Class Codes: B23K 11/31 Electrode holders and actuating devices therefornot restricted to resistance welding or severing by resistance heating B23K37/02
• CPC Class Codes: B23K 11/314 Spot welding guns, e.g. mounted on robots
• CPC Class Codes: B23K 11/315 with one electrode moving on a linear path
• CPC Class Codes: B23K 3/0338 Constructional features of electric soldering irons
• CPC Class Codes: B23K 3/08 Auxiliary devices therefor cleaning pipes or tubes or systems of pipes or tubes, e.g. before soldering, B08B9/02
• CPC Class Codes: G06Q 20/023 the neutral party being a clearing house

Abstract

A pressure regulator system for a pneumatically- or hydraulically-actuated weld head. The weld head includes a switching valve comprising several ports: an inflow port attached to a source of pressurized gas, preferably air; an exhaust port; a first line port; and a second line port. Two-way valves are provided on the first line port and the second line port. A valve sensor connected to a switch for determining weld force in the weld head is connected to means for simultaneously closing the first line port valve and the second line valve port when a desired weld force is attained between one or more electrodes and a workpiece, thereby maintaining a constant, maximum pressure in the cylinder and consequently maintaining the desired weld force between the electrode(s) and the workpiece during the welding operation.

Claims

1. A weld head for welding a workpiece comprising:

an electrode;

a cylinder comprising an actuating rod operatively connected to the electrode for pressing the electrode onto the workpiece responsive to a flow of pressurized fluid in the cylinder;

a force sensing mechanism for sensing when a predetermined weld force between the electrode and workpiece is reached; and

one or more valves responsive to the sensor for blocking fluid flow to and from the cylinder when the predetermined weld force is sensed and maintaining the predetermined weld force between the electrode and the workpiece while the workpiece is being welded.

2. The weld head of claim 1 wherein the force sensing mechanism comprises:

a first pressure sensor in fluid communication with an up port of the cylinder;

a second pressure sensor in fluid communication with a down port of the cylinder;

a weld force regulator in electrical communication with said first and second pressure sensors for monitoring the pressure in the upper and lower chambers of the cylinder; and

a force firing switch in electrical communication with the weld force regulator which changes state when a predetermined weld force between the electrode and workpiece is reached.

3. The weld head of claim 1 wherein the force sensing mechanism comprises:

an adjustment device for setting a predetermined weld force level;

a force setting spring operatively coupled to the electrode which compresses when the electrode is pressed onto a workpiece;

a means for measuring the compression of the force setting spring; and

a force firing switch that changes state when the predetermined weld force is reached.

4. The weld head of claim 3 wherein the means for measuring the compression of the force setting spring is one or more photo diodes.

5. The weld head of claim 1 wherein the force sensing mechanism comprises:

an adjustment device for setting a predetermined weld force level;

a force transducer operatively coupled to the electrode, said transducer being adapted to output an electrical signal that corresponds to a given weld force; and

a force sensor whose output changes state when a predetermined weld force is achieved.

6. The weld head of claim 1 wherein the force sensing mechanism comprises:

a second cylinder operatively coupled to a lower electrode such that the pressure in a lower chamber of said second cylinder varies as the upper electrode exerts a weld force on the workpiece;

an adjustment device for inputting the desired pressure level in the lower chamber of the second cylinder; and

a pressure responsive switch operatively coupled to the lower chamber of the second cylinder which changes state when a predetermined pressure in the lower chamber is reached.

7. The weld head of claim 1 wherein the force sensing mechanism comprises:

an adjustment device for setting a predetermined weld force level;

a force setting spring operatively coupled to the workpiece which compresses when the electrode is pressed onto a workpiece;

a means for measuring the compression of the force setting spring; and

a force firing sensor that changes state when a predetermined weld force is reached.

8. The weld head of claim 1 wherein the force sensing mechanism comprises:

an adjustment device for setting a predetermined weld force level;

a force setting spring operatively coupled to a workpiece which compresses when the electrode is pressed onto a workpiece; and

a force firing switch operatively coupled to and sensitive to the compression of the force setting spring such that the force firing switch closes when a predetermined weld force is achieved.

9. The weld head of claim 1 wherein the force sensing mechanism comprises:

an adjustment device for setting a predetermined weld force level;

a force transducer operatively coupled to the workpiece which outputs an electrical signal which corresponds to a given weld force; and

force sensor whose output changes state when a predetermined weld force achieved.

10. A weld head for welding a workpiece comprising:

an electrode;

an offset electrode holder, operably coupled to an electrode holder adapter block by an electrode holder bar;

a cylinder comprising an actuating rod operatively connected to the electrode holder adapter block for pressing the electrode onto the workpiece responsive to a flow of pressurized fluid in the cylinder;

a force sensing mechanism for sensing when a predetermined weld force between the electrode and workpiece is reached; and

one or more valves responsive to the sensor for blocking fluid flow to and from the cylinder when the predetermined weld force is sensed and maintaining the predetermined weld force between the electrode and the workpiece while the workpiece is being welded.

11. The weld head of claim 10 wherein the force sensing mechanism comprises:

an adjustment device for setting a predetermined weld force level;

a strain gauge operatively coupled to the electrode holder bar, said strain gauge being adapted to output an electrical signal which corresponds to a given weld force; and

a force firing switch in electrical communication with the strain gauge whose output changes state when a predetermined weld force is achieved.

12. A method for welding in a welding system comprising a cylinder and an actuated cylinder rod, the method comprising the steps of:

moving an electrode onto a workpiece with the actuating rod by introducing pressurized fluid into a first chamber of the cylinder and exhausting fluid from a second chamber of the cylinder;

pressing the electrode against the workpiece with the actuating rod;

sensing when a predetermined weld force between the electrode and the workpiece is reached and simultaneously sealing the pressurized fluid in the cylinder in response thereto;

supplying electrical energy to the electrode on the workpiece to produce a weld;

maintaining a desired pressure in the cylinder corresponding to the predetermined weld force while the workpiece is being welded;

discontinuing the supply of electrical energy to the electrode when the weld is complete; and

retracting the electrode after the weld is complete by first introducing pressurized fluid into the second chamber of the cylinder and next exhausting fluid from the first chamber of the cylinder.

13. A pressure regulator system for a weld head comprising a pneumatic cylinder and a weld force switch having an open position and a closed position and which moves to a closed position when a predetermined weld force is attained in the weld head, the pressure regulator system comprising:

a switching valve comprising;

an inflow port;

an exhaust port;

an up line port; and

a down line port;

an up line port valve operatively connected to the up line port and a down line port valve operatively connected to the down line port, wherein each of said port valves is closed in an energized state and open in a de-energized state;

means for substantially simultaneously closing the up line port valve and the down line valve port when the weld force switch moves to the closed position; and

means for first switching said inflow port to said up line port and said exhaust port to said down port then substantially simultaneously opening the up line port valve and the down line valve port when the weld is complete.

14. A weld head for welding a workpiece comprising:

an electrode;

a cylinder comprising an actuating rod operatively connected to the electrode for pressing the electrode onto the workpiece responsive to a flow of pressurized fluid in the cylinder;

a force sensing mechanism for sensing when a predetermined weld force between the electrode and workpiece is reached; and

a brake mechanism responsive to said sensor for fixing the actuating rod of said air cylinder in a stationary position when the predetermined weld force is sensed and maintaining the desired position of the cylinder actuating rod that corresponds to the predetermined weld force while the workpiece is being welded.

15. A reflow solder head for reflow soldering a workpiece comprising:

an electrode;

a cylinder comprising an actuating rod operatively connected to the electrode for pressing the electrode onto the workpiece responsive to a flow of pressurized fluid in the cylinder;

a force sensing mechanism for sensing when a predetermined weld force between the electrode and workpiece is reached; and

one or more valves responsive to the sensor for blocking fluid flow to and from the cylinder when the predetermined solder force is sensed and maintaining the predetermined solder force between the electrode and the workpiece while the workpiece is being reflow soldered.

16. The reflow solder head of claim 15 wherein the force sensing mechanism comprises:

a first pressure sensor in fluid communication with an up port of the cylinder;

a second pressure sensor in fluid communication with a down port of the cylinder;

a reflow solder force regulator in electric communication with said first and second pressure sensors for monitoring the pressure in the upper and lower chambers of the cylinder; and

a force firing switch in electrical communication with the reflow solder force regulator which changes state when a predetermined reflow solder force between the electrode and workpiece is reached.

17. The reflow solder head of claim 15 wherein the force sensing mechanism comprises:

an adjustment device for setting a predetermined reflow solder force level;

a force setting spring operatively coupled to the electrode which compresses when the electrode is pressed onto a workpiece;

a means for measuring the compression of the force setting spring; and

a force firing switch that changes state when the predetermined reflow solder force is reached.

18. The reflow solder head of claim 17 wherein the means for measuring the compression of the force setting spring is one or more photo diodes.

19. The reflow solder head of claim 15 wherein the force sensing mechanism comprises:

an adjustment device for setting a predetermined reflow solder force level;

a force transducer operatively coupled to the electrode, said transducer being adapted to output an electrical signal that corresponds to a given reflow solder force; and

a force sensor whose output changes state when a predetermined reflow solder force is achieved.

20. The reflow solder head of claim 15 wherein the force sensing mechanism comprises:

a second cylinder operatively coupled to a lower electrode such that the pressure in a lower chamber of said second cylinder varies as the upper electrode exerts a reflow solder force on the workpiece;

an adjustment device for inputting the desired pressure level in the lower chamber of the second cylinder; and

a pressure responsive switch operatively coupled to the lower chamber of the second cylinder which changes state when a predetermined pressure in the lower chamber is reached.

21. The reflow solder head of claim 15 wherein the force sensing mechanism comprises:

an adjustment device for setting a predetermined reflow solder force level;

a force setting spring operatively coupled to the workpiece which compresses when the electrode is pressed onto a workpiece;

a means for measuring the compression of the force setting spring; and

a force firing sensor that changes state when a predetermined reflow solder force is reached.

22. The reflow solder head of claim 15 wherein the force sensing mechanism comprises:

an adjustment device for setting a predetermined reflow solder force level;

a force setting spring operatively coupled to a workpiece which compresses when the electrode is pressed onto a workpiece; and

a force firing switch operatively coupled to and sensitive to the compression of the force setting spring such that the force firing switch closes when a predetermined reflow solder force is achieved.

23. The reflow solder head of claim 15 wherein the force sensing mechanism comprises:

an adjustment device for setting a predetermined reflow solder force level;

a force transducer operatively coupled to the workpiece which outputs an electrical signal which corresponds to a given reflow solder force; and

force sensor whose output changes state when a predetermined reflow solder force achieved.

24. A reflow solder head for reflow soldering a workpiece comprising:

an electrode;

an offset electrode holder, operably coupled to an electrode holder adapter block by an electrode holder bar;

a cylinder comprising an actuating rod operatively connected to the electrode holder adapter block for pressing the electrode onto the workpiece responsive to a flow of pressurized fluid in the cylinder;

a force sensing mechanism for sensing when a predetermined reflow solder force between the electrode and workpiece is reached; and

one or more valves responsive to the sensor for blocking fluid flow to and from the cylinder when the predetermined reflow solder force is sensed and maintaining the predetermined reflow solder force between the electrode and the workpiece while the workpiece is being reflow soldered.

25. The reflow solder head of claim 24 wherein the force sensing mechanism comprises:

an adjustment device for setting a predetermined reflow solder force level;

a strain gauge operatively coupled to the electrode holder bar, said strain gauge being adapted to output an electrical signal which corresponds to a given reflow solder force; and

a force firing switch in electrical communication with the strain gauge whose output changes state when a predetermined reflow solder force is achieved.

26. A method for reflow soldering in a reflow soldering system comprising a cylinder and an actuated cylinder rod, the method comprising the steps of:

moving an electrode onto a workpiece with the actuating rod by introducing pressurized fluid into a first chamber of the cylinder and exhausting fluid from a second chamber of the cylinder;

pressing the electrode against the workpiece with the actuating rod;

sensing when a predetermined reflow solder force between the electrode and the workpiece is reached and simultaneously sealing the pressurized fluid in the cylinder in response thereto;

supplying electrical energy to the electrode on the workpiece to produce a reflow solder joint;

maintaining a desired pressure in the cylinder corresponding to the predetermined reflow solder force while the workpiece is being reflow soldered;

discontinuing the supply of electrical energy to the electrode when the reflow solder is complete; and

retracting the electrode after the reflow solder is complete by first introducing pressurized fluid into the second chamber of the cylinder and next exhausting fluid from the first chamber of the cylinder.

27. A pressure regulator system for a reflow solder head comprising a pneumatic cylinder and a reflow solder force switch having an open position and a closed position and which moves to a closed position when a predetermined reflow solder force is attained in the reflow solder head, the pressure regulator system comprising:

a switching valve comprising;

an inflow port;

an exhaust port;

an up line port; and

a down line port;

an up line port valve operatively connected to the up line port and a down line port valve operatively connected to the down line port, wherein each of said port valves is closed in an energized state and open in a de-energized state;

means for substantially simultaneously closing the up line port valve and the down line valve port when the reflow solder force switch moves to the closed position; and

means for first switching said inflow port to said up line port and said exhaust port to said down port then substantially simultaneously opening the up line port valve and the down line valve port when the reflow solder is complete.

28. A reflow solder head for reflow soldering a workpiece comprising:

an electrode;

a cylinder comprising an actuating rod operatively connected to the electrode for pressing the electrode onto the workpiece responsive to a flow of pressurized fluid in the cylinder;

a force sensing mechanism for sensing when a predetermined reflow solder force between the electrode and workpiece is reached; and

a brake mechanism responsive to said sensor for fixing the actuating rod of said air cylinder in a stationary position when the predetermined reflow solder force is sensed and maintaining the desired position of the cylinder actuating rod that corresponds to the predetermined reflow solder force while the workpiece is being reflow soldered.