Cylindrical Die Rolling Process

Throughfeed Rolling

Throughfeed Rolling, also known as skewed axis rolling, is used to produce continuous lengths of rolled geometry by allowing parts to feed through the dies completely or for a controlled distance. The dies are on skewed axes with respect to the part which results in axial feeding during rolling. A throughfeed die has a starting section, dwell section, and relief section to accomplish controlled radial penetration of the blank, calibration of roundness and fullness the form, and disengagement of the die from the workpiece. The die face width is governed by the machine capacity and rolled form characteristics and is normally very narrow compared to the full length of rolled form.

A combination of infeed and throughfeed can be used to roll partial or full lengths on a part. This can result in incomplete or underfilled threads as the dies reach their rolling position while feeding takes place. The length of the underfilled thread section is dependent on the part feed rate, die geometry, and the plunge speed of the dies.

There are four main Throughfeed rolling modes:

• Straight Throughfeed
• Throughfeed & Open
• Infeed/Throughfeed
• Infeed/Throughfeed & Open

Straight Throughfeed rolling requires the dies to be positioned at fixed radial center distance. Blanks are introduced between the dies and are pulled through by the feeding action until the rolled workpiece leaves the dies completely. This type of rolling is used to produce full length rolled forms.

Throughfeed & Open rolling requires the dies to be at fixed radial center distance while the blank is introduced between them. The blank is pulled through by the feeding action until the dies are opened off the workpiece when desired length of rolled form is achieved. This type of rolling is used to produce partial length or full length rolled forms and can result in incomplete threads where the dies are opened.

Infeed/Throughfeed, also known as plungefeed, requires the dies to close onto the workpiece like the infeed process. Throughfeed action begins simultaneously as the dies penetrate the blank to their rolling position. Rolling is then carried out until part feeds through the dies completely. This type of rolling is used to produce full length or partial length rolled forms and can result in incomplete threads where the dies are initially closed.

Infeed/Throughfeed & Open requires the dies to close onto the workpiece and throughfeed roll until the dies are opened off the part when desired length of rolled form is achieved. This type of rolling is used to produce full length or partial length rolled forms and can result in incomplete threads where the dies are initially closed and where the dies opened.

Throughfeed rolling is primarily used for threaded rod applications and precision actuator screws for linear motion such as ball screws and lead screws.

Single Revolution Rolling

Single Revolution rolling, also known as incremental rolling, is used to roll discrete lengths of rolled geometry using one revolution of the dies to compete the rolling process. The dies are at fixed radial center distance and are aligned on parallel axis with the part which results in little to no axial feed of the workpiece during rolling. The rolled profile height gradually increases around the periphery of the dies in a starting section, maintains full height over a fixed circumference in a dwell section, then diminishes in height for a relief section. The penetration, dwell, and disengagement of the dies with the workpiece are all accomplished by the die design.

A single revolution die can also be manufactured with just a starting and dwell section without a relief section. The machine center distance control is used to open the dies and simulate the relief section. This can have the added benefit of extending die life by incrementally opening the dies further into the dwell section as normal tool wear progresses.

Single revolution dies typically have a cutout relief between the beginning of the penetration section and the end of the dwell section. This allows for part positioning and easy transfer through the dies.

This process can also be utilized to roll several independent forms on a single shaft by mounting multiple sets of single revolution dies on the same machine spindle. Shaft handling and over-all processing time is reduced. An alternator shaft with a thread and two serrations can be produced very quickly in a single handling by one machine rather than by three separate machines with handling between each.

Single revolution rolling is typically used to roll splines, serrations, knurls, threads, and worms, on power transmission shaft applications such as half-shafts and axle bars.