The plate roller shaft broke off of a drive roll with the bearing housing and bearings still installed. The engineering team evaluated the loading parameters and operational stress analysis and developed an interference shaft fit design. A new shaft was manufactured using a 4340 steel material and proved more viable than the original shaft design.

Project:

• Part: Plate Rolling Drive Roll
• Details: 24″ DIA. x 227″ OAL; 21,500 lbs.
• Customer: Global steel fabricator

Challenge:

• Drive shaft was fractured at the primary radius and was broken off of the roll with the bearing housing and bearings still installed.
• Welded shaft repair was analyzed and determined to pose a high risk of material cracking due to the high carbon content of the roll body.
• Loading parameters and operational stress analysis were evaluated by Western Machine’s engineering team and were critical to the design of the replacement shaft.

Engineered Solutions:

• Remove bearings and housings from both ends of the roll. Dimensionally inspect bearing shaft fits and housing fits.
• Non-destructive test the primary radius on the front shaft.
• Manufacture a steady rest carrier ring for boring out the broken shaft concentric to the roll body.
• Evaluate loading parameters to assist in the design calculations for the new shaft to be manufactured.
• Analyze operational stresses and develop an interference shaft fit design in place of the welded shaft repair to ensure the integrity of the newly manufactured replacement shaft.
• Manufacture new shaft using a 4340 steel material.

Result:

• The manufactured new shaft was installed with a .010″ interference fit into the roll body.
• Factor of safety values show that the replacement shaft is more viable than the original shaft design.