Tool Holder Shank Stabilization With Axial Pin Locking

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Solution Overview

Problem

Existing solutions for stabilizing tool holder shanks on CNC machine tools are prone to accidental detachment due to vibrations, posing safety risks and potential machine damage, as radially inserted dowels can loosen and escape during machining.

Innovation Solution

The device uses elastic pins housed inside the ring nut to securely connect the tool holder shank, employing a bayonet-type coupling with recesses and protuberances on shaped half-rings and a circular crown, ensuring permanent stabilization without axial displacement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If radially inserted dowels are used to stabilize the tool holder shank on the ring nut, then the shank can rotate freely with the ring nut, but the dowels may loosen and escape due to vibrations and centrifugal force during machining

Engineering Contradiction:

Improvefree rotation capabilityVSAvoiddowel retention stability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The invention extracts the dowel from the ring nut and relocates it to the tool holder shank. The dowel is now inserted axially into the shank rather than radially into the ring nut, eliminating the problem of dowel loosening and ejection while maintaining the rotational coupling function between the shank and ring nut

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention inverts the traditional mounting approach by reversing the direction of dowel insertion from radial (into ring nut) to axial (into shank). This inversion places the dowel in a position where it is protected from centrifugal force and vibrations that cause loosening, while still achieving the same rotational stabilization function

Inventive Principle:

Principle #13The other way round (Inversion)

2Ease of operation

If dowels are inserted radially into the ring nut to fix the shank, then the shank and ring nut can rotate freely, but the dowels may be violently ejected causing safety risks and machine damage

Engineering Contradiction:

Improverotational freedomVSAvoiddowel ejection hazard

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The dangerous radial dowel insertion method is extracted and replaced with a safe axial insertion method. The dowel remains in the shank during rotation but cannot be ejected axially due to the shank structure, eliminating the safety hazard while preserving rotational freedom

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention converts the potentially harmful radial dowel configuration into a beneficial axial dowel configuration. The axial dowel provides the same rotational stabilization function but eliminates the ejection hazard, effectively converting a harmful design into a safe one

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Ease of manufacture

If traditional half-rings with grease coating are used to block the shank in the groove, then the half-rings remain in position, but the connection lacks permanent stabilization

Engineering Contradiction:

Improvesimple assembly processVSAvoidconnection permanence

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The invention applies preliminary action by pre-coating the half-rings with adhesive before assembly. This preliminary adhesive application ensures permanent stabilization of the half-rings in the groove, preventing any movement or loosening during subsequent machining operations while maintaining the simplicity of the assembly process

Inventive Principle:

Principle #10Preliminary action

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 solution effectively prevents accidental detachment of dowels, ensuring safety and machine integrity by maintaining the tool holder shank in a stable operating position, with enhanced resistance and reliability over time.

Implementation Method 1

The recesses 22 are predisposed to house respective elastic pins 24, by means of which the shaped half-rings 14 and 16 are firmly connected inside the ring nut 12

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

employing a bayonet-type coupling with recesses and protuberances on shaped half-rings and a circular crown, ensuring permanent stabilization without axial displacement

Methodology Applied

Scientific EffectMechanical coupling: Mechanical Fastener

Data Source

PatentEP3766616B1A device for the controlled stabilization of tool holder shanks

Publication Date: 2023.08.30 ALGRA SPA

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AI summary

A device for the controlled stabilization of tool holder shanks on the respective ring nut, said tool holder shanks, motorized or non-motorized, being predisposed for ER or other type fixing. Said device comprises a ring nut (12) and a tool holder shank (10) of a truncated conical shape provided externally with a groove (18) in which means (14, 16) connecting said ring nut (12) to the tool holder (10) are arranged inside said ring nut. Said connecting means consist of an annular body formed of at least two shaped half-rings (14, 16) that define opposite protrusions projecting outwardly and centrally to form a shaped prominence (20) having an arched-convex outer profile; on each of the shaped prominences (20) a recess (22) is made predisposed to house respective elastic pins (24), by means of which the shaped half-rings (14) and (16) are firmly connected inside the ring nut (12). lind holes (32).