Sectional Hob Wedge Clamping for Chatter-Free Gear Cutting
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Solution Overview
Problem
Existing sectional hobs face instability in blade attachment, leading to potential chattering during gear cutting, which impairs machining precision, and require significant time and labor for precise phase matching of saw-toothed cutting edges.
Innovation Solution
The use of wedge members aligned along the center axis of the hob body to securely press and attach blades, providing a large contact area for stable attachment and preventing chattering, while allowing for precise positioning of saw-toothed cutting edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single radial fastening screw with a tapered head part is used to pressurize one blade against an inclined surface, then the blade attachment becomes unstable, leading to chattering during gear cutting and impaired machining precision
Solution Approach 1:
The fastening system is segmented from a single radial fastening screw into multiple wedge members (typically three) that are distributed around the circumference of the hob body. Each wedge member independently pressurizes the blade at different angular positions, providing stable and uniform attachment. This segmentation prevents the instability and chattering that occur with a single fastening point, thereby maintaining high machining precision during gear cutting operations.
2Manufacturing precision
If multiple grooves are formed in the circumferential direction with supporters and blades positioned using adjusting screws and hold-down pieces, then the saw-toothed cutting edges can form a spiral shape with constant lead, but it requires much time and labor for precise positioning and phase matching
Solution Approach 1:
The wedge members are pre-positioned at specific angular intervals (e.g., 120 degrees apart) on the hob body, with their pressing surfaces oriented to automatically align with the blade's inclined surface. This preliminary arrangement eliminates the need for time-consuming adjustment of supporters and hold-down pieces during assembly. The blade can be directly attached using the pre-configured wedge members, significantly reducing positioning time while maintaining the required phase precision of the spiral cutting edges.
3Device complexity
If the tapered head part of the radial fastening screw abuts against the inclined surface of the blade in a line contact, then the attachment is simple, but the contact area is small and the attachment is unstable
Solution Approach 1:
The fastening approach transitions from line contact (one-dimensional) to surface contact (two-dimensional) by introducing wedge members with pressing surfaces that contact the blade's inclined surface over an extended area. The wedge members distribute the fastening force across multiple contact points along the inclined surface, creating a larger effective contact area. This dimensional change from line to surface contact significantly improves attachment stability while maintaining relatively simple device complexity, as each wedge member remains a compact component.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution ensures stable blade attachment, prevents chattering, and enhances machining precision without requiring extensive time or labor for phase matching, maintaining high precision during gear cutting.
Implementation Method 1
a plurality of wedge members 6 lined up in a center axis direction O of the hob body 1 to press onto the blade 4
Data Source
Figure 1
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AI summary
This sectional hob is provided with: a cylindrical hob body; a plate-shaped blade having a saw-toothed cutting edge, the blade being disposed in at least one attachment seat formed in an outer peripheral part of the hob body such that a direction of the cutting edge is parallel to a center axis direction of the hob body; and a plurality of wedge members configured to detachably-fix the blade disposed in the attachment seat to the hob body, the wedge members being installed in a recess formed on the outer peripheral part of the hob body, wherein the recess is adjacent to the attachment seat in a circumferential direction of the hob body, and the plurality of the wedge members are disposed in a line in the center axis direction in the recess.