Spindle Cam Fixation for Vibration Driver Drills
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Solution Overview
Problem
In vibration driver drills, insufficient fixation of the first cam to the spindle can lead to relative rotation between the spindle and the first cam, resulting in inadequate vibration of the spindle when in contact with the second cam.
Innovation Solution
The power tool design incorporates a spindle with specific portions at different distances from the rotation axis and a first cam with corresponding portions, along with an engagement member, to reduce the spindle's rotation relative to the first cam, ensuring effective vibration by using a first cam surrounding the spindle and a second cam located behind it.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the first cam is fixed insufficiently to the spindle, then the device complexity is reduced, but the spindle rotates relative to the first cam causing insufficient vibration
Solution Approach 1:
The first cam is divided into multiple segments (first cam portion, second cam portion, third cam portion) that can be independently positioned at different radial distances from the rotation axis. This segmentation allows the cam to engage with corresponding portions of the spindle at different locations, providing multiple fixation points without requiring a complex overall fixation structure. Each segment can be简单地 fixed to the spindle, and the cumulative effect of multiple segments prevents relative rotation while maintaining simplicity.
Solution Approach 2:
Different portions of the first cam are positioned at different radial distances from the rotation axis (first distance, second distance, third distance), creating local variations in the cam's geometry. This local quality variation allows each cam portion to engage with specific corresponding portions of the spindle at different radial positions. The engagement at multiple local positions provides robust fixation while keeping each individual fixation point simple.
2Stability of the object's composition
If the first cam is made nonrotatable relative to the second cam, then the vibration stability is improved, but the device complexity increases due to additional engagement structures
Solution Approach 1:
The engagement mechanism between the first cam and second cam is segmented into multiple discrete engagement points (first cam portion engaging with first engagement portion, second cam portion engaging with second engagement portion, third cam portion engaging with third engagement portion). Each engagement point is a simple local feature, but collectively they provide robust anti-rotation functionality. This segmentation avoids the need for a single complex engagement structure.
Solution Approach 2:
The anti-rotation function is merged into the normal operational engagement between the cams. The same portions of the first cam that transmit vibration motion to the second cam also serve to prevent relative rotation. By merging the motion transmission function and the anti-rotation function into the same engagement structures, no additional dedicated anti-rotation mechanism is needed, thus avoiding increased device complexity.
3Reliability
If multiple cam portions at different radial distances are used, then the fixation reliability is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The first cam is designed with asymmetric geometry where different portions are intentionally positioned at different radial distances from the rotation axis. This asymmetric design is deliberately created during manufacturing, and the asymmetry itself is the functional feature that enables multi-point engagement. Rather than requiring high precision to achieve symmetry, the manufacturing process simply needs to create the intended asymmetric geometry, which is a straightforward manufacturing task.
Data Source
AI summary
Rotation of a spindle relative to a first cam is reduced. A power tool includes a spindle to receive a tip tool and rotatable about a rotation axis, and a vibration mechanism that vibrates the spindle in an axial direction. The spindle has an outer surface including, in a cross section orthogonal to the rotation axis, a first portion at a first distance from the rotation axis, and a second portion at a second distance from the rotation axis. The vibration mechanism includes a first cam surrounding the spindle, and a second cam located behind and in contact with the first cam.