Gear Production
Issue link: http://gear.epubxp.com/i/262216
8—GEAR Production Supplement F E A T U R E of these solutions achieved the full promise that many in our industry believed skiving held, particularly in comparison to shaping. On paper, at least, it's long been recognized that skiving would be a much more productive process than shaping for cutting many (but not all) internal gears. Shaping generates the gear teeth with an oscillating stroke movement—a downstroke that performs the cut followed by a nonproductive return stroke. Consequently, a great portion of the shaping cycle time consists of noncontact time and acceleration/deceleration of the stroke movements. Power skiving, on the other hand, is a continuous cutting process that produces a gear in a much shorter time because it almost entirely avoids noncontact situations as well as frequent acceleration movements. This continuous cutting process makes power skiving about four times faster than shaping. Similar to hobbing, the skiving cutter can produce the gear in one or more cuts. Each cut performs a radial in feed, or depth of cut, followed by an axial advance movement on every tooth over the entire gear face. The rotating skiving cutter intersects the rotating gear at an angle (the cross-axis angle). The cutting speed, which is the speed of the cutter tooth tip along the gear tooth gap, is a result of both the circumferential speed and the cross-axis angle of the cutter. While this concept seems practical, an economical and effective skiving solution proved to be elusive for more than 100 years. Machines and cutting spindles simply weren't robust and rigid enough to minimize vibrations caused by the high spindle rpms and signifcant cutting forces generated by the skiving process; cutting conditions were such that tool life was prohibitively low; tool substrate and coating materials were not yet at today's advanced high levels; and, most signifcantly, no method existed for end users to adequately simulate and optimize the skiving process in advance. Today, Gleason Power Skiving completely solves all of these century-old challenges, and more. Gleason Power Skiving: As much as eight times faster than shaping. Here's one example: Part Type: Internal Spur Gear Internal Diameter: 350 mm (13.8") Module 4 mm (DP 6.35) No. of Teeth: 90 Face Width: 100 mm (3.94") Prole Depth: 8.6 mm (0.34") Qualit y Required: DIN 8 (AGMA 9) Machining Time: Shaping: 40 min.* Machining Time: Gleason Power Skiving: 11 min.* *not including loading/unloading time 0314_MMS_Gear_RussFeature_EDIT.indd 8 2/13/2014 2:42:25 PM