Robot Wrist End Effector Thermal Expansion Management

Solution Overview

Problem

Vacuum robots face increased demands for reduced deflection and weight in their arms due to payload loads and thermal expansion, leading to higher manufacturing costs and potential deformation issues, which existing solutions attempt to address by using higher stiffness materials but result in increased weight and cost.

Innovation Solution

A robot arm design featuring a wrist and end effector combination made from materials with different coefficients of thermal expansion, where the connection between these components is configured to prevent deflection by using a frame member sandwiched between the members, with features such as slots and clamp plates to manage thermal expansion and minimize stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If higher stiffness materials are used to minimize deflection, then deflection is reduced, but weight and cost are increased

Engineering Contradiction:

ImprovedeflectionVSAvoidweight

Core Design Contradiction:

Stability of the object's compositionVSWeight of moving object

Solution Approach 1:

The wrist assembly uses a composite structure combining aluminum frame members with stainless steel end effector components. This multi-material approach optimizes the stiffness-to-weight ratio by placing high-stiffness material (stainless steel) only where needed at the end effector, while the main wrist structure uses lighter aluminum material.

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If higher stiffness materials are used to minimize deflection, then deflection is reduced, but cost is increased

Engineering Contradiction:

ImprovedeflectionVSAvoidcost

Core Design Contradiction:

Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The wrist assembly uses a composite structure combining aluminum frame members with stainless steel end effector components. This multi-material approach optimizes the stiffness-to-weight ratio by placing high-stiffness material (stainless steel) only where needed at the end effector, while the main wrist structure uses lighter aluminum material.

Inventive Principle:

Principle #40Composite materials

3Temperature

If the arm deforms due to thermal expansion, then additional height and clearances are needed, but this increases manufacturing costs

Engineering Contradiction:

Improvethermal expansionVSAvoidmanufacturing costs

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The connection assembly is specifically designed to accommodate and manage thermal expansion between components with different coefficients of thermal expansion. The aluminum wrist and stainless steel end effector are connected in a way that allows for differential expansion without causing harmful stresses or deformations, eliminating the need for additional clearance accommodations.

Inventive Principle:

Principle #37Thermal expansion

Solution Approach 2:

The wrist assembly uses a composite structure combining aluminum frame members with stainless steel end effector components. This multi-material approach optimizes the stiffness-to-weight ratio by placing high-stiffness material (stainless steel) only where needed at the end effector, while the main wrist structure uses lighter aluminum material.

Inventive Principle:

Principle #40Composite materials

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 effectively reduces deflection and weight while ensuring uniform thermal expansion and contraction, thereby minimizing additional costs associated with increased height, clearances, and Z-direction stroke requirements.

Implementation Method 1

the connection is configured to substantially prevent the different respective coefficients of thermal expansion to deflect the end effector relative to the wrist when the end effector and wrist are heated and/or cooled

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS10005190B2Robot with wrist and end effector different materials

Publication Date: 2018.06.26 PERSIMMON TECHNOLOGIES CORP

AI summary

An apparatus including a robot arm comprising a wrist, and an end effector. The wrist includes a frame member. The frame member includes a first material having a first coefficient of thermal expansion. The end effector is connected to the wrist at a connection. The end effector is configured to support a substrate thereon. The end effector includes a first member and a second member. At least one of the first and second members has a different second material with a different second coefficient of thermal expansion. The connection includes the first and second members being stationarily attached to each other with a portion of the frame member sandwiched therebetween. The connection is configured to substantially prevent the different respective coefficients of thermal expansion to deflect the end effector relative to the wrist when the end effector and wrist are heated and/or cooled.