Ground Screw Thread Structure for Grip and Moldability
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Solution Overview
Problem
Larger threaded drive screws with uniform helical threads are cumbersome to manufacture and prone to dislodging due to reduced grip in the ground, making them unstable under wind and load conditions.
Innovation Solution
A molded screw with a conically shaped shank featuring alternating high and low threads in a spiral fashion, including recessed portions that reduce manufacturing difficulties and enhance grip in the ground, and projections for pole alignment and locking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform helical threads are used on the screw, then the manufacturing process is simplified, but the grip in the ground is reduced making the screw prone to dislodging
Solution Approach 1:
The screw thread is designed with alternating high and low sections along its length, creating local variations in thread profile. The high threads provide enhanced grip in specific zones while low threads allow dirt accumulation and flow, collectively improving overall stability without complicating the manufacturing process
2Reliability
If larger threaded drive screws are used to improve stability, then the grip in the ground is enhanced, but the screw becomes cumbersome and difficult to manufacture with a mold
Solution Approach 1:
The thread structure is segmented into alternating high and low sections along the screw length. This segmentation allows the thread to be formed in a single molding operation while creating zones of varying grip characteristics, avoiding the need for complex post-manufacturing assembly or larger overall screw dimensions
3Ease of manufacture
If uniform thread shape is used, then the manufacturing process is simplified, but the screw is prone to dislodging under wind and load conditions
Solution Approach 1:
The thread profile varies locally along the screw length with alternating high and low sections. The high threads engage the ground for strong mechanical interlocking while low threads create channels for dirt flow and accumulation, providing enhanced resistance to dislodging forces from wind and load
Data Source
AI summary
The present disclosure provides a molded screw preferably comprised of a sleeve portion to receive a pole, the sleeve portion connected to a conical shank terminating at a tip. The shank is in turn further comprised of at least one thread, the thread to facilitate drilling of the screw into the ground. The thread is further comprised of recessed portions that receive earth or dirt or other substances during the drilling process and stabilize the screw when it is set in the ground. In another embodiment, the shank is further comprised of a high and low thread, which spiral in alternating fashion to the tip of the screw.