Tool Holder Dust Cap with Flexure Joint for Angled Drill Sealing

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Solution Overview

Problem

Existing tool holders for hand-held machine tools, such as hammer drills, face challenges in effectively sealing against dust and reducing abrasion of sealing rings when drills are used at angles, leading to inefficiencies and wear.

Innovation Solution

A tool holder design featuring a dust cap with a sealing ring, a middle section forming a flexure joint, and a conical inner surface that allows slight deflection, ensuring the sealing ring follows transverse movements and remains circumferential to the drill, reducing abrasion and maintaining a dust-tight seal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a rigid dust cap is used to seal the tool holder, then dust sealing is improved, but the sealing ring cannot accommodate transverse movements of angled drill bits, leading to increased abrasion and reduced reliability

Engineering Contradiction:

Improvedust ingressVSAvoidsealing ring durability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The dust cap transitions from a rigid structure to a dynamic structure by introducing a flexure joint in the middle section. This allows the sealing ring to move dynamically with angled drill bits while maintaining the dust-tight seal, resolving the contradiction between sealing effectiveness and component durability

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The middle section of the dust cap is designed as a flexible element that can deflect to accommodate transverse movements. This flexible structure allows the sealing ring to follow angled drill bits without compromising the overall sealing integrity or causing excessive wear

Inventive Principle:

Principle #30Flexible shells and thin films

2Object-affected harmful factors

If the sealing ring is made rigid to maintain seal integrity, then dust sealing is improved, but the sealing ring cannot follow transverse movements of drill bits, causing increased wear and reduced adaptability

Engineering Contradiction:

Improvedust sealingVSAvoidaccommodation of angled drill bits

Core Design Contradiction:

Object-affected harmful factorsVSAdaptability or versatility

Solution Approach 1:

The sealing system incorporates dynamic characteristics through the flexure joint, allowing the sealing ring to adapt its position while maintaining seal integrity. This enables the system to handle both dust sealing and accommodation of angled drill bits effectively

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The middle section's flexibility changes the mechanical parameters of the sealing ring, allowing it to deflect and follow angled drill bits. This parameter change enables the sealing ring to maintain contact with the drill bit while accommodating transverse movements

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If a solid hinge is introduced to allow sealing ring deflection, then adaptability to angled drill bits is improved, but the structural complexity of the dust cap increases

Engineering Contradiction:

Improvesealing ring deflectionVSAvoiddust cap structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The flexure joint is integrated directly into the middle section of the dust cap, merging the hinge function with the existing structural element. This eliminates the need for separate hinge components while providing the necessary deflection capability

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The middle section is designed as a thin, flexible structure that inherently provides hinge-like deflection capability. This approach avoids complex mechanical hinge mechanisms while achieving the desired adaptability through the flexible geometry of the dust cap itself

Inventive Principle:

Principle #30Flexible shells and thin films

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The design effectively seals the tool holder against dust ingress and reduces sealing ring abrasion when drills are used at angles, enhancing the durability and performance of the tool holder.

Implementation Method 1

The sealing ring can follow transverse movements of the drill or chisel. The sealing ring remains in full contact with the drill and seals the opening of the tool holder.

Methodology Applied

Scientific EffectSealing:

Implementation Method 2

The central section forms a solid hinge, allowing a slight deflection of the sealing ring transversely to the working axis.

Methodology Applied

Scientific EffectFlexure joint:

Implementation Method 3

The sealing ring remains in full contact with the drill and seals the opening of the tool holder. Furthermore, wear of the sealing ring caused by angled drill bits is reduced.

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentEP3107694B1Tool holder

Publication Date: 2019.11.27 HILTI AG

Figure 1
Figure 2

AI summary

A tool holder 2 for a hand-held power tool has a tubular main body 17 and a dust cap 27. The main body 17 has an end face 19 which is adjoined by a cylindrical or prismatic outer face 36. The dust cap 27 has a sealing ring 28, a central portion 29 and a seat 30 in succession in the introduction direction 20. The sealing ring 28 is arranged in front of the end side 19 of the main body 17 in the introduction direction 20. The seat 30 has a cylindrical or prismatic inner face 35, which rests against the outer face 36 of the main body 17. The central portion 29 has a conical inner face 39, the inside diameter 40 of which decreases in the introduction direction 20 down to the inside diameter 37 of the seat 30.