Screw Shank Triangular Cross Section and Spiral Groove
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional screws used in wood and composite materials experience high friction resistance and difficulty in expelling wood chips, leading to increased effort and risk of cracking, especially when used in compound sheets mixed with plastic resin and wood chips.
Innovation Solution
A screw design featuring a shank with a rough triangular lower section, asymmetrical threads, and slantingly extending end cutting grooves to reduce friction and efficiently expel waste chips, along with a non-threaded section and circular protruding teeth for enhanced coupling and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the shank has a round cross section with full thread contact, then the thread can be screwed into the work-piece, but a relatively larger friction force is produced requiring more effort and time in operation
Solution Approach 1:
The shank cross-section is segmented from a complete circle to an arc-shaped section, removing a portion of the material. This segmentation reduces the contact area between the thread and work-piece, thereby reducing friction force while maintaining sufficient structural integrity for screwing operations.
Solution Approach 2:
The shank is designed with non-uniform cross-sectional geometry along its length. The upper section has a different arc-shaped cross-section than the lower section, optimizing the local contact characteristics. This local quality variation allows reduced friction in the upper section while maintaining strength in the lower section.
2Productivity
If the end cutting groove extends axially along the shank, then the thread can cut the work-piece, but it is difficult for wood chips to be expelled smoothly causing obstruction and cracking
Solution Approach 1:
The end cutting groove is extended from a simple axial groove to a three-dimensional spiral groove that winds along the shank in a helical pattern. This dimensional change creates a chip conveyor path that actively transports wood chips outward and upward, preventing obstruction and facilitating smooth expulsion during the screwing operation.
Solution Approach 2:
The spiral groove design converts the potentially harmful accumulation of wood chips into a beneficial chip evacuation system. The spiral geometry uses the rotational motion of screwing to actively propel chips outward, transforming the obstruction problem into an efficient chip removal mechanism that prevents cracking and improves operation.
3Reliability
If the screw is used for screwing into compound sheets mixed and compressed from plastic resin and wood chips, then connection is achieved, but waste chips cannot be effectively cut off due to axial groove limitations
Solution Approach 1:
The cutting groove is transformed from a two-dimensional axial feature to a three-dimensional spiral feature that wraps around the shank. This spiral configuration provides extended cutting edges that effectively slice through the composite material of plastic resin and wood chips, separating waste chips from the connection zone and improving both chip cutting and evacuation.
Solution Approach 2:
The spiral groove introduces asymmetric geometry to the otherwise symmetric cylindrical shank. This asymmetry creates directional chip flow and enhanced cutting action that is particularly effective for composite materials, allowing the groove to systematically remove waste chips while maintaining reliable connection quality.
Data Source
AI summary
A screw includes a shank and at least one end cutting groove. The shank includes a lower section disposed near an insertion end thereof and an upper section disposed near a head end thereof. The lower section has triangular transverse cross sections, and the upper section has circular transverse cross sections. A first thread is disposed on the lower section of the shank, and a second thread is disposed on the upper section of the shank. A non-threaded section is disposed between the lower section and the upper section of the shank. An outer diameter of the non-threaded section is larger than an outer diameter of the upper section. The end cutting groove is formed in the lower section of the shank, and an included angle between 3 and 9 degrees is formed between an extending direction of the end cutting groove and a longitudinal axis of the shank.