Weld Roll Configurations
Throughout the tube and pipe mill industry, there are many "Weld Roll Configurations" in service today.
Weld Roll Configurations are influenced by several factors, such as:
- Tooling Design
- Type of material being formed/welded
- Tube/Pipe Mill Design/Configuration/Layout
- Type of welding, TIG, HF, ERW, Laser, etc.
- Personal preference
Whereas some operators will swear a certain weld roll configuration is the only one that will work for their tube mill, the true story is that many times more than one weld roll configuration will work for the same specific application
This article has been prepared to give an understanding to the wide variety of applications of the "A-F Weld Roll Configuration" examples, illustrating the pros and cons of the same, with no favoritism to any one design.
Weld Roll Configuration (A):
- Used predominately on smaller mechanical mills up to 3.000" max O.D., .250" max wall.
- This design is one of the most popular applications for High Frequency (HF) welding.
- The weld rolls are positioned in an upright "Y" configuration, offering individual adjustment of each top weld roll to maintain edges parallel before forging.
- Most weld box applications in this format either incorporate a three (3) roll individual clevis design or a three (3) roll symmetrical chuck style design.
- Chuck style design weld boxes offer single point adjustment to bring in all three (3) weld rolls symmetrically in or out on center while still allowing for individual weld roll adjustment if need be to keep the edges of the strip parallel. This design has proven a tremendous time saver in set up and operation for most applications.
Weld Roll Configuration (D & E):
- Both D & E are normally offered in the same format as previously outlined in configuration (A), (Individual clevis design), however the weld rolls are now presented in the upside down "Y" configuration.
- (D) This configuration uses a solid top roll, and offers no ability to adjust for mismatched edges of the strip should the one side of the contour wear before the other. Heat checking of the edges along the slot is common with this design.
- (E) This design uses a split roll, and usually incorporates a split top clevis design as well that would allow individual adjustment of the two (2) "halves" of the top rolls to keep the strips edges matched and parallel. However the set up and maintenance of this type of weld box is very difficult at best, and is rarely found out in the industry any more.
Weld Roll Configuration (B):
- This configuration is found on large and small tube/pipe mills.
- The bottom rolls of this type of design are part of the "ERW" application where the top weld rolls are the copper electrodes of the Electric Resistance Welding process
- Many times these bottom rolls are left in place when the welding process is converted to High Frequency (HF) welding. The draw back to this conversion is usually the weld box is very large, thus requiring large weld rolls, and with HF welding, this can become a problem with energy absorption and loss of weld power and heating up of the weld rolls.
- This configuration is widely used in TIG and Laser welding applications. It is found in two (2) roll, four (4) roll, or six (6) roll formats usually dictated by the type and tensile strength of the material being formed and welded.
- One of the drawbacks of this configuration is that if one of the top contours of one of the rolls begins to wear before the other, the ability to keep the strips edges matched/parallel for welding becomes an issue, unless the weld box incorporates a height adjustment on one of the opposing weld roll shafts. This is especially true with nonferrous weld rolls.
- This configuration is very easy to set up and operate.
Weld Roll Configuration (C):
- This configuration of four (4) rolls, (two (2) bottoms & two (2) tops), are normally found on larger tube/pipe mills from 3.000" O.D. and up, with wall thickness of .250" and above using High Frequency (HF) "coil and contact" welding
- These four (4) roll weld boxes are normally very robust in design and integrity with the ability to forge very heavy and high tensile materials.
- The top rolls are normally individually adjustable up and down for maintaining parallel of the strips edges.
- Some very large applications incorporate a fifth roll between the two bottom weld rolls for added support/squeeze and integrity.
Weld Roll Configuration (F):
- This application is set up similar to a four (4) roll "Turks Head Unit" which is most commonly used for straightening purposes on tube/pipe mills.
- This design incorporates "four (4)" individual clevises, with "four (4)" independent adjustments with the ability of the two (2) top rolls to maintain the strips edges parallel for welding.
- This design is rarely found in the industry today.
Robert A. Sladky
Vice President Tube Mill Engineering.