Hole Cutter Plug Ejection Without a Longer Arbor
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Solution Overview
Problem
Hole cutters face difficulties in removing plugs, especially from thicker materials, due to waste material binding and requiring additional arbor length for ejection, which increases manufacturing costs and causes rotational runout.
Innovation Solution
A hole cutting tool with a hollow arbor allowing translation movement of a pilot guide and hole saw for plug ejection, eliminating the need for a lengthened arbor, using a locking mechanism to secure the pilot guide in drilling and eject positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the arbor is made longer to allow the hole saw to travel back towards the drill chuck during plug ejection, then plug ejection is enabled, but the arbor causes rotational runout and increases manufacturing cost
Solution Approach 1:
The arbor is divided into two functional segments: a first arbor portion that remains stationary and maintains rotational precision, and a second arbor portion that translates to enable plug ejection. This segmentation allows the ejection function to be added without compromising the rotational accuracy of the main arbor body.
Solution Approach 2:
Instead of extending the arbor in the radial direction (which would cause runout), the solution translates a portion of the arbor along the axial dimension. The second arbor portion moves axially relative to the first arbor portion, enabling plug ejection through longitudinal movement rather than radial extension.
2Ease of operation
If the arbor is made longer to facilitate plug ejection, then waste material can be ejected, but manufacturing cost increases
Solution Approach 1:
The arbor is segmented into a stationary first portion and a movable second portion. This allows the expensive precision-machined first portion to remain short and accurate, while the second portion handles the translation function for ejection, optimizing both performance and manufacturing cost.
Solution Approach 2:
The second arbor portion is designed to be dynamically movable relative to the first portion during the ejection cycle. This dynamic configuration allows the system to achieve plug ejection functionality without permanently increasing the overall arbor length, thereby reducing manufacturing costs.
3Ease of operation
If a lengthened arbor is used for plug ejection, then ejection is possible, but the arbor cannot be used in confined areas such as cupboards, switchboards, ground pits
Solution Approach 1:
By segmenting the arbor into a compact first portion and a movable second portion, the system achieves plug ejection capability without increasing the overall footprint when the tool is in use. The second portion translates along the axis rather than extending radially, maintaining compact dimensions for confined space operation.
Solution Approach 2:
The plug ejection function is achieved through axial translation of the second arbor portion rather than radial extension. This dimensional approach allows the tool to maintain a compact profile suitable for confined spaces while still providing effective plug ejection capability.
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A hole cutting tool (100) with plug ejection includes a hole saw (140) having a first central bore (141) and an arbor (106) having a second central bore (112) along a central axis (X-X). The arbor (106) is configured at one end to be coupled to a rotational drilling machine (102), and at the other end to be attached to the hole saw (140) in a first cutting position and detached from the hole saw (140) in a second ejection position. The hole cutting tool (100) also includes a pilot guide (162) having an ejection shoulder (170). The pilot guide (162) is slidably disposed within the second central bore (112) of the arbor (106) and received through the first central bore (141) of the hole saw (140). The pilot guide (162) being configured to translate along the central axis (X-X) between a first drilling position and the second ejection position.