Gear Tooth Machining Path Control to Avoid Skiving Interference
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Solution Overview
Problem
Conventional gear machining methods, such as skiving, face limitations in producing specified flank geometries due to interference contours, which can lead to collisions and require alternative methods like gear shaping, and struggle with maintaining uniform toothing depth and high cutting speeds.
Innovation Solution
The method involves a two-stage machining process where the first stage generates the predominant flank geometry with axial feed, and the second stage uses a counteracting movement, including radial or tangential movements, to complete the flank geometry without axial overrun, allowing the machining tool to bypass interference contours and maintain uniform toothing depth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional skiving is used to machine gear teeth, then material is removed in a rolling machining motion, but the tool projects beyond the axial end of the gear teeth and may collide with interfering contours
Solution Approach 1:
The machining process is divided into two distinct operations: a first operation that machines the predominant part of the flank geometry with axial feed, and a second operation that machines the remaining part with modified relative movement. This segmentation allows the tool to complete machining before projecting beyond the gear teeth, avoiding collision with interfering contours while maintaining high productivity
Solution Approach 2:
The patent dynamically adjusts the relative movement between the skiving wheel and gear teeth between two operations. In the first operation, axial feed is used for efficient material removal. In the second operation, the relative movement is modified so the tool center distance from the gear rotation axis is changed, moving the tool center away from the gear teeth and counteracting the axial overrun, thus adapting the process to avoid collisions
2Productivity
If the axial feed is increased to improve productivity, then machining time is reduced, but the tool overrun beyond the gear teeth increases, risking collision with interfering contours
Solution Approach 1:
By segmenting the machining into two operations, the patent allows the first operation to use high axial feed for efficient material removal, while the second operation uses modified relative movement to complete the flank geometry without excessive tool overrun, thus resolving the contradiction between productivity and overrun distance
Solution Approach 2:
The patent changes the parameters of relative movement between the two operations. In the second operation, the distance of the tool center from the gear rotation axis is changed relative to the fixed movement path, and the resulting change in machining engagement is counteracted by an additional change in the relative movement, thus controlling the tool overrun distance while maintaining productivity
3Reliability
If gear shaping is used instead of skiving to avoid collisions, then collision risk is eliminated, but machining time increases and productivity decreases
Solution Approach 1:
The patent maintains the dynamic rolling machining motion of skiving (unlike conventional gear shaping) by using two operations with different relative movements. This allows the process to retain the high productivity of skiving while avoiding collisions, thus resolving the contradiction between reliability and productivity
4Productivity
If the cross-angle is increased to improve cutting speed, then productivity increases, but the tool envelope extends further axially, increasing the risk of collision with interfering contours
Solution Approach 1:
The patent changes the parameters of relative movement in the second operation to counteract the axial extension caused by larger cross-angles. By modifying the distance of the tool center from the gear rotation axis and adjusting the relative movement, the process can use larger cross-angles for higher cutting speeds while preventing collision with interfering contours
Data Source
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Figure 3a~3d
AI summary
The invention relates to a method for machining a toothing (2) having an axis of rotation (C), in which a machining tool (4), which is rotationally driven about its axis of rotation (B), removes material from the toothing while executing a relative motion between the machining tool and toothing to generate a flank geometry of the toothing, which has been predefined over the full width of the toothing, in a machining operation, wherein the predefined flank geometry matches a motion control that defines a motion path of the tool centre with respect to the toothing axis of rotation, said motion control having a defined, non-vanishing axial advancement with a defined advancing motion between machining tool and toothing, wherein in a first machining process, the relative motion is only executed for generating a part (5), more particularly a significant part, of the flank geometry according to this motion control, while a further part (6), more particularly the remaining part, of the flank geometry is generated in a second machining process, in which the distance between the tool centre and the toothing axis of rotation with respect to the fixed motion path changes in a manner wherein the tool centre moves away from the toothing, and in which the change to the machining operation caused thereby is counteracted by an additionally executed change in motion of the relative motion with respect to the motion control of the first machining process.