Self-Centering Assembly Machine for Lost-Pattern Strata

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Solution Overview

Problem

The investment casting process faces challenges in precisely assembling layers of a model due to variations in geometry, leading to poor matching at bonding joints, leakage zones, and sticking problems, which complicates the assembly process and results in model scraps.

Innovation Solution

A machine with self-centering members that allow for automatic adjustment and movement in a plane orthogonal to the bonding direction, using rolling balls and spring-loaded pushers to ensure precise alignment and bonding of strata with inclined slopes, and a method involving a specific adhesive with controlled viscosity for constraint-free assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional bonding tools are used to assemble strata, then the assembly process can be performed, but geometric variations lead to poor matching at bonding joints and leakage zones

Engineering Contradiction:
Improvebonding joint matching precisionVSAvoidbonding joint reliability
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies preliminary action by providing preliminary adjustment means that allow adjustment of the position of at least one support relative to the other support before the bonding operation. This preliminary adjustment compensates for geometric variations in the strata, ensuring proper matching at bonding joints before the actual bonding occurs, thereby preventing leakage zones and poor matching.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent applies dynamics by making the bonding tool adjustable and adaptable. The preliminary adjustment means enable dynamic repositioning of supports to accommodate variations in strata geometry. This dynamic capability allows the same bonding tool to handle different batches of strata with varying geometries, maintaining bonding joint reliability without requiring dedicated tools for each batch.

Inventive Principle:
Principle #15Dynamics

2Manufacturing precision

If three-dimensional adjustment tools are used to accommodate geometric variations, then bonding precision can be improved, but the adjustment process must be repeated for each batch increasing complexity

Engineering Contradiction:
Improvestrata assembly precisionVSAvoidadjustment process complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies universality by designing a bonding tool with preliminary adjustment means that can accommodate multiple batches of strata with different geometric variations. The adjustment mechanism is configured to handle variations within tolerance ranges across different batches, making the same tool universally applicable rather than requiring dedicated adjustment procedures for each batch. This reduces device complexity while maintaining precision.

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

3Productivity

If single batch adjustment is performed, then assembly can be completed, but variations within the same batch cause sticking problems and compressive/tensile stresses

Engineering Contradiction:
Improveassembly throughputVSAvoidbonding joint uniformity
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by enabling adjustment before bonding to accommodate variations within the same batch. The preliminary adjustment means allow the operator to position supports correctly before the bonding process begins, preventing sticking problems and non-uniform stresses that would occur during bonding. This ensures bonding joint uniformity while maintaining assembly throughput.

Inventive Principle:
Principle #10Preliminary action

4Reliability

If frequent adjustments are made to accommodate variations, then bonding quality can be maintained, but the assembly process becomes more complex and time-consuming

Engineering Contradiction:
Improvebonding joint qualityVSAvoidadjustment time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent applies universality by designing adjustment means that can handle multiple batches and variations with a single configuration. The preliminary adjustment mechanism is capable of accommodating geometric variations across different batches within tolerance ranges, eliminating the need for frequent re-adjustments. This maintains bonding joint quality while minimizing adjustment time and process complexity.

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

The solution enables a more precise and complex assembly of strata with reduced leakage and sticking issues, allowing for a single nominal adjustment and minimizing model scraps by accommodating geometric variations within and between batches.

Implementation Method 1

self-centering members of the strata, during the assembly position of the strata, in a plane orthogonal to the direction of bonding... the self-centering members comprise: a set of rolling balls allowing movement in at least one direction contained in the plane orthogonal to the bonding direction; a pair of spring-loaded pushers oriented in the same direction of movement of the set of balls

Methodology Applied
Scientific EffectMechanical self-centering mechanism:

Implementation Method 2

the supply of a glue for assembling the strata at a bonding temperature, the adhesive having a Brookfield viscosity of between 700 and 1800 mPa.s at the bonding temperature, preferably a Brookfield viscosity of between 1000 and 1500 mPa.s, the bonding temperature preferably being between 110°C and 130°C

Methodology Applied
Scientific EffectAdhesive bonding: Adhesive

Implementation Method 3

the adhesive having a Brookfield viscosity of between 700 and 1800 mPa.s at the bonding temperature... the bonding temperature preferably being between 110°C and 130°C

Methodology Applied
Scientific EffectViscosity control:

Data Source

PatentEP2723518B8Machine and method for assembling a pattern for lost-pattern moulding, and corresponding moulding method
Publication Date: 2015.10.28 PEUGEOT CITROEN AUTOMOBILES SA

AI summary

The invention relates to a machine for assembling by adhesive bonding of strata of a pattern for a lost-pattern moulding method, the machine (20) comprising: a first support (24) for a first stratum (40) of the pattern; a second support (26) for a second stratum (60) of the pattern; the first and second supports (24, 26) being designed to be moved towards one another, in an adhesive-bonding direction, in order to adhesively bond the first and second strata (40, 60) together, the assembly machine (20) comprising members (30, 38) for the self-centring of the strata, when placing the strata (40, 60) in an assembly position, in a plane orthogonal to the adhesive-bonding direction.