Doffer Gripper Fastening with Integrated Spring

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Solution Overview

Problem

The existing doffer gripper for spinning machines has high manufacturing costs due to its complex structure, which includes an additional steel spring for generating clamping force, increasing production expenses.

Innovation Solution

The doffer gripper integrates a one-piece elastic spring element with the free end of the elastic retaining strap and the rigid support element, eliminating the need for an additional steel spring, and uses elastic plastic for the spring element, which is molded onto the holding tab and support element, allowing for a single injection molded part production.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If an additional steel spring is used to generate clamping force on the doffer beam, then the clamping effect is sufficient, but the manufacturing cost increases

Engineering Contradiction:
Improveclamping forceVSAvoidmanufacturing cost
Core Design Contradiction:
ForceVSEase of manufacture

Solution Approach 1:

The patent merges the spring element with the retaining strap by molding the spring element directly onto the retaining strap during injection molding. This integration eliminates the need for separate steel springs and reduces the number of components, thereby lowering manufacturing costs while maintaining the necessary clamping force through the elastic deformation of the integrated spring element

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent replaces expensive steel springs with a molded plastic spring element that is integrated into the retaining strap. This plastic spring element achieves the required clamping force at lower cost, making the overall fastening element more economical to manufacture while maintaining functional effectiveness

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Force

If multiple separate components (steel spring, retaining strap, support element) are used, then the clamping force can be adjusted, but the device complexity increases

Engineering Contradiction:
Improvespring forceVSAvoidstructure complexity
Core Design Contradiction:
ForceVSDevice complexity

Solution Approach 1:

The patent combines multiple separate components (retaining strap, spring element, and support element) into a single integrated injection-molded part. The spring element is molded directly onto the retaining strap, which is in turn connected to the support element, creating a unified structure that reduces component count and assembly complexity while maintaining adjustable spring force through geometric design

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The integrated fastening element serves multiple functions simultaneously: the retaining strap provides attachment functionality, the molded-in spring element provides clamping force, and the support element provides structural stability. This multi-functional integration eliminates the need for separate components and simplifies the overall device structure

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 simplifies the structure, reduces manufacturing costs, and ensures a sufficient clamping effect with adjustable spring force, even with high manufacturing tolerances, by using a pre-bent spring element and multiple spring elements connected to the elastic holding tabs.

Implementation Method 1

at least one spring element (18a, 18b) arranged on two end faces (17a, 17b) of the elastic retaining straps (6a, 6b), said spring element (18a, 18b) being made of elastic plastic

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3206981B1Fastening for a doffer gripper
Publication Date: 2018.09.05 MASCHINENFABRIK RIETER AG
  • EP3206981B1 patent drawingFigure 1~2
  • EP3206981B1 patent drawingFigure 3~4
  • EP3206981B1 patent drawingFigure 5

AI summary

The invention relates to a doffer gripper (1) for fastening to a doffer bar (4), having a fastening element (5) which comprises two elastic holding lugs (6a, 6b) which are arranged at a spacing from one another and a rigid supporting element (7) which is arranged between the elastic holding lugs (6a, 6b), wherein the two elastic holding lugs (6a, 6b) are connected with a first end (27a, 27b) to the fastening element (5) and are positioned with a second free end (13a, 13b) in a rest position in each case via at least one spring element (18a, 18b). In order to simplify the construction of the doffer gripper (1), the at least one spring element (18a, 18b) is configured in one piece with the free end (13a, 13b) of the respective elastic holding lug (6a, 6b) and the rigid supporting element (7).