Angled Screw Connector with Blind-Hole Positioning

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Solution Overview

Problem

Existing angled screw connections for workpieces are difficult to set correctly, prone to localization errors, and can result in unstable connections due to shifting workpieces and the risk of parts falling, especially when working overhead.

Innovation Solution

A cylindrical connector with a base body, cover surface, and lateral surface for form-fitting insertion into a blind hole, featuring diverging bores for screws that absorb shear forces and prevent shifting, with a recess allowing flush connection and edge-free outer surfaces to reduce the risk of workpiece splitting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If angled screws are used to connect workpieces, then the load-bearing capacity increases and shear stress on screws is reduced, but the installation becomes difficult and workpieces may shift during tightening

Engineering Contradiction:
Improveload-bearing capacityVSAvoidinstallation difficulty
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The connector is pre-inserted into blind holes in the workpieces before screwing begins. This preliminary positioning action prevents workpiece shifting during the subsequent angled screw installation, as the connector acts as a guide and stabilizing element that maintains proper alignment throughout the tightening process.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The connector serves as an intermediary component between the workpieces and the angled screws. By inserting the connector first into the blind holes, it mediates the connection process, providing a stable reference structure that eliminates localization errors and ensures accurate screw positioning while maintaining the beneficial angled screw configuration for high load-bearing capacity.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If metal plates are used with right-angle screws, then the connection is simple to install, but unfavorable shear stress occurs on the plate and connection stability is reduced

Engineering Contradiction:
Improveinstallation simplicityVSAvoidconnection stability
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The invention changes the critical parameter of screw angle from 90 degrees (right-angle) to an acute angle (typically 30-45 degrees). This parameter change transforms the stress distribution on the connector, reducing unfavorable shear stress while increasing tensile stress utilization, thereby improving connection stability while maintaining relatively simple installation through the use of pre-positioned blind holes.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If connectors with edge-facing bores are used, then screwing is simplified, but the risk of workpiece splitting increases at the end faces

Engineering Contradiction:
Improvescrewing simplicityVSAvoidworkpiece splitting risk
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

Instead of having bores penetrate the outer surface of the connector (which would create edges at the end faces), the invention inverts the approach by having bores penetrate only the base surface while leaving the outer surface edge-free. The bores extend through the connector body to receive angled screws, but the outer cylindrical surface remains intact, eliminating stress concentration points that would cause workpiece splitting while still allowing straightforward screw insertion.

Inventive Principle:
Principle #13The other way round (Inversion)

4Adaptability or versatility

If blind holes are not pre-drilled, then manufacturing flexibility is maintained, but incorrect connector placement and localization errors occur

Engineering Contradiction:
Improvemanufacturing flexibilityVSAvoidconnector placement accuracy
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The invention employs pre-drilled blind holes as a preliminary action that establishes precise positioning for the connector before final assembly. The blind holes act as guides that ensure correct connector placement and prevent localization errors, while the connector itself remains adaptable for use with pre-drilled holes in various workpiece configurations, maintaining manufacturing flexibility through standardized implementation.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3375947B1Connector for screwing two workpieces at an angle
Publication Date: 2023.06.07 KNAPP GMBH
  • EP3375947B1 patent drawingFigure 1~3

AI summary

The present invention relates to a connector (1) for diagonally screwing together two workpieces (2, 3), comprising a base body (4) with a base surface (5), a top surface (6) parallel thereto and a generally cylindrical outer surface (7) connecting these for positive locking insertion into a generally cylindrical blind hole (8) of at least one of the workpieces (2, 3), and a recess (9) in the top surface (6), from which at least two bores (10, 11) for receiving a screw (12, 13) each extend outwards at an angle (α).