Round Shaft Bit Retaining Sleeve for Wear Protection

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Solution Overview

Problem

Existing chisel designs face issues with wear optimization, uneven wear, and difficulty in reusing chisels after dismantling from holders, leading to increased assembly complexity and wear on cost-intensive chisel holders.

Innovation Solution

The chisel features a support element with a recess on its upper side to accommodate the chisel head, forming a labyrinthine closure for reduced rotational wear, and includes radially outer recesses for material excavation, along with a deflection section to facilitate easy assembly and disassembly, ensuring minimal wear on the chisel holder and even wear distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the support element is fixed in a rotationally fixed manner relative to the chisel holder, then the chisel holder is protected from wear, but the chisel experiences uneven wear and the support element works unevenly into the facing contact surface due to impact loads

Engineering Contradiction:
Improvechisel holder wear protectionVSAvoideven wear distribution
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The support element is designed to rotate relative to the chisel holder through a bearing arrangement, transforming the static fixed connection into a dynamic rotating connection. This allows the support element to self-adjust and distribute wear evenly across its circumference while the chisel rotates during operation, preventing concentrated wear at single contact points.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If the chisel is dismantled from the chisel holder, then worn chisels can be replaced, but assembly becomes more complicated requiring separate clamping tools to prestress the clamping sleeve

Engineering Contradiction:
Improvechisel replacement capabilityVSAvoidassembly complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The support element is designed with a preliminary action mechanism where it automatically prestresses the clamping sleeve during the assembly process itself, eliminating the need for separate clamping tools. The support element's geometry and positioning create the necessary prestressing force as the chisel is inserted into the holder, simplifying the assembly operation to a single insertion motion.

Inventive Principle:
Principle #10Preliminary action

3Stability of the object's composition

If the support element exerts rotating wear to enable chisel rotation, then even wear distribution is achieved, but increased wear occurs on the chisel holder

Engineering Contradiction:
Improveeven wear distributionVSAvoidchisel holder wear
Core Design Contradiction:
Stability of the object's compositionVSLoss of substance

Solution Approach 1:

The rotational wear function is extracted from the chisel holder and transferred to the support element. The support element rotates relative to the holder through a bearing, so that wear occurs on the support element rather than the expensive chisel holder. This separation allows the support element to enable even wear distribution on the chisel while protecting the holder from wear.

Inventive Principle:
Principle #2Taking out (Extraction)

4Adaptability or versatility

If the fastening sleeve is made resilient with a longitudinal slot for variable diameter, then different clamping states can be achieved, but the assembly process becomes more complex requiring precise positioning

Engineering Contradiction:
Improveclamping state adjustmentVSAvoidassembly positioning complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The fastening sleeve with longitudinal slot is designed to automatically self-position and self-adjust during assembly. The resilient material and slot geometry enable the sleeve to elastic-deform and snap into the correct position when the chisel is inserted, eliminating the need for precise manual positioning or complex alignment procedures. The sleeve serves itself by using the insertion force to achieve proper clamping state.

Inventive Principle:
Principle #25Self-service

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

This design ensures minimal rotational wear, easy assembly and disassembly, and even wear distribution across the chisel circumference, improving milling results and reducing wear on the chisel holder.

Implementation Method 1

The fastening sleeve is designed as a clamping sleeve, which is made of a resilient material, such as sheet steel... the support element has a bore which is dimensioned in such a way that the fastening sleeve is held in a prestressed state with a reduced outer diameter compared to its relaxed state

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

As the chisel shank is further inserted into the bore, the support element is moved into an area of the chisel shank that is not encompassed by the clamping sleeve. The fastening sleeve then springs open radially and braces itself in the bore of the chisel holder.

Methodology Applied
Scientific EffectElastic recovery: Elastic Recovery

Data Source

PatentEP2491228B1Round shaft bit with a retaining sleeve
Publication Date: 2019.07.10 BETEK
  • EP2491228B1 patent drawingFigure 1~2
  • EP2491228B1 patent drawingFigure 3~4
  • EP2491228B1 patent drawingFigure 5~6

AI summary

The invention relates to a bit, in particular a round shaft bit having a bit head and a bit shaft, wherein a fastening sleeve is held in the area of the bit shaft, and wherein a support element is associated with the bit and comprises a guide area. In order to be able to easily remove the bit from the bit receptacle, and optionally to be able to easily remount same, according to the invention, the support element comprises a deflection section in the area of the base thereof facing away from the bit head.