Resistance Welding Machine Pinch Point Safety Sensor

• US 20080302766A1
• Filed: 12/21/2006
• Published: 12/11/2008
• Est. Priority Date: 12/30/2005
• Status: Active Grant

• Current Assignee: Roger Hirsch
• Original Assignee: Roger Hirsch
• Inventors: Hirsch, Roger
• Granted Patent: US 9,555,498 B2
• Time in Patent Office: Days
• US Class Current: 219/108
• 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 11/25 Monitoring devices
• CPC Class Codes: B23K 11/256 the measured parameter being the inter-electrode electrical resistance

Abstract

There is described a continuity sensing system that operates with a resistance-welding machine. This sensing system measures continuity between the welding electrodes after the welding machine has been initiated and prevents application of high electrode force between the electrodes if the continuity measured is below a reference level. The result is a fully passive system that prevents serious high electrode force that would cause serious pinch-point injury to the operator of the welder. The present invention also includes methods of controlling pneumatic systems on resistance-welding machines to apply low force between welding electrodes until continuity between the welding electrodes has been detected.

Claims

1. A pinch point safety sensor for a resistance welder having electrodes which are brought together under high force to effect a weld, wherein an electrical circuit is provided which limits electrode force until and unless only low resistance material such as metal is detected between said electrodes.

2. The pinch point safety sensor recited in claim 1, which is fully passive and does not permit operator adjustment.

3. The pinch point safety sensor recited in claim 2, which cannot be bypassed.

4. The pinch point safety sensor recited in claim 1, which has a pressure regulator to regulate electrode closing force, wherein predetermined settings of the electric circuit inhibits closing of said electrode to reach high force.

5. The pinch point safety sensor recited in claim 1, wherein a continuity sensor in said circuit ascertains whether or not to introduce high force to said electrodes.

6. The pinch point safety sensor recited in claim 5, wherein said continuity sensor has a comparator which has a predetermined reference voltage.

7. The pinch point safety sensor recited in claim 6, wherein relay means is connected to said comparator and said relay means is energized when said voltage is below said reference voltage.

8. The pinch point safety sensor recited in claim 7, wherein said relay means when energized signals said welder that continuity has been detected between said electrodes.

9. A pinch point safety sensor for a resistance welder having electrodes which are brought together under high force to effect a weld, wherein application of high force to said electrodes is restrained until and unless only low resistance material such as metal is detected between said electrodes by signal means.

10. The pinch point safety sensor recited in claim 9, wherein said resistance welder has a ram and means to apply low force and high force to its associated electrodes, wherein pneumatic means counterbalances a portion of the weight of said welder ram prior to receipt of a signal from said signal means.

11. In the pinch point safety sensor recited in claim 10, wherein said welder has multiple welding heads, and said pneumatic means is adapted to close said welding heads with low force prior to receipt of a signal from said signal means.

12. In the pinch point safety sensor recited in claim 9, wherein said welder has motor means for closing said electrodes against a work piece, and said sensor has means to prevent closing action of said motor means and application of high force to close said electrodes prior to receipt of a signal from said signal means detecting only low resistance material such as metal between said electrodes.

13. In the pinch point safety sensor recited in claim 12, wherein said motor means is adapted to close said electrodes against a work piece, and said sensor has means to prevent application of closing action of said motor means under high force prior to receipt of a signal from said signal means.

14. In the pinch point safety sensor recited in claim 9, wherein said sensor has a controller which ascertains whether high force is to be applied to said electrodes.

15. In the pinch point safety sensor recited in claim 14, wherein said sensor has high pressure and low pressure valve means.

16. In the pinch point safety sensor recited in claim 15, wherein said valve means comprises a high pressure solenoid valve and a low pressure solenoid valve.

17. In the pinch point safety sensor recited in claim 14, wherein shuttle valve means and a regular is connected to said sensor to block high pressure until low resistance material is detected between said electrodes.

18. In the pinch point safety sensor recited in claim 9, wherein said sensor is connected to a welding transformer in an electric circuit, and said signal for said signal means is detected from the low voltage side of said transformer.

19. In the pinch point safety sensor recited in claim 9, wherein said sensor is connected to a welding transformer in an electric circuit, and said signal for said signal means is detected from the primary high voltage side of said transformer.

20. A pinch point safety sensor for a resistance welder having electrodes which are brought together under high force to effect a weld, wherein said sensor comprises an isolation transformer, an amplifier integrator, a RMS converter and a comparator connected to output relay means for directing said welder to limit electrode force until and unless only low resistance material such as metal is detected between said electrodes.

21. A pinch point safety sensor for a resistance welder having electrodes which are brought together under high force to effect a weld, wherein said sensor comprises an amplifier integrator, a RMS converter and a comparator connected to output relay means for directing said welder to limit electrode force until and unless only low resistance material such as metal is detected between said electrodes.