Method of flash-butt welding

• US 6,294,752 B1
• Filed: 01/20/2000
• Issued: 09/25/2001
• Est. Priority Date: 12/16/1999
• Status: Expired due to Fees

• Current Assignee: E.O. Paton Electric Welding Institute Of The National Academy Of Sciences Of Ukraine
• Original Assignee: E.O. Paton Electric Welding Institute Of The National Academy Of Sciences Of Ukraine
• Inventors: Krivonos, Vadim P., Krivenko, Valeriy G., Kuchuk-Yatsenko, Sergei I., Didkovskiy, Alecsandr V., Bogorskiy, Mikhail V., Gorishnyakov, Alexei I.
• Primary Examiner(s): Dunn, Tom
• Assistant Examiner(s): DUNN, COLLEEN P
• Application Number:
  US09/488,174
• Time in Patent Office: 614 Days
• Field of Search: 219/100, 219/55, 219/61.5, 219/86.41, 219/86.7, 219/86.61, 219/91.1, 219/104, 219/110
• US Class Current: 219/100
• CPC Class Codes: B23K 11/04 Flash butt welding

Abstract

A method of flash-butt welding in which the travel speed (V_t) of the machine mobile plate and the welding voltage (U₂) are changed (by preset programs) and the travel speed is controlled through negative feedback by welding current, the voltage being changed discretely for each flashing fixed interval of t_m duration as a function of the increment of the actual average speed of flashing details of shortening (V_a) during the previous flashing interval, V_a value being maintained at the present level, lower than V_m. The invention envisages a change of the coefficient of enhancement of the negative feedback in a discrete manner for each preset flashing interval of t_m duration as a function of V_a increment during the previous flashing interval. The invention further provides for an increase in the value of U₂ and a decrease of the coefficient of negative feedback to the set value until the speed has reached the set value of speed V_f at which upsetting is switched on, or after the set value of Q_m has been reached, U₂ is increased and the coefficient of negative feedback is decreased to the set value, these values remaining constant until upsetting is switched on.

Claims

1. A method of flash-butt welding in which the travel speed (V_t) of the machine mobile plate and the welding voltage (U₂) are changed and the travel speed is controlled through negative feedback by welding current, characterized in that the voltage is changed discretely for each flashing fixed interval of t_m duration as a function of the increment of the actual average speed of flashing details of shortening (V_a) during the previous flashing interval, V_a value being maintained at the preset level, lower than V_t.

2. A method of item 1 characterized in that the coefficient of enhancement of the negative feedback is changed discretely for each preset flashing interval of t_m duration as a function of V_a increment during the previous flashing interval.

3. A method of item 1 characterized in that after the set number of intervals has been reached, U₂ values are increased and the negative feedback coefficient is reduced to the set value.

4. A method of item 1 characterized in that after the set value of Q_m (optimal quantity of heat (energy) transferring to the butt ends of parts being welded) has been reached, U₂ is increased and the negative feedback coefficient is reduced to a preset value.

5. A method of item 1 characterized in that after the assigned level of V_a has been reached in the final period of flashing, upsetting is switched on.

6. A method of flash but welding of two similar cross sections using a welding machine wherein V_t is a travel speed of a mobile plate of the welding machine;

U₂ is a monitored value of welding voltage;

V_a is an average speed of flashing which is represented by a speed with which the two similar cross sections to be welded are brought together for welding; and

wherein t_m is a fixed time interval for each flashing, the method comprising the steps of;

generally controlling V_t and U₂ as per a predetermined program based on parameters of the cross sections to be welded;

modifying welding voltage U₂ for each time interval t_m as a function of an increment of average speed V_a; and

selectively maintaining the average speed V_a to be lower than V_t.

7. A method as in claim 6 including the step of controlling the speed V_t based on a feedback from a measured value of welding current.

8. A method as in claim 6 including the step of upsetting which is a fast drawing together of molten surfaces of said two similar cross sections, wherein the step of upsetting is switched on automatically after an assigned value of V_a is reached.