Linear Motor Scan Unit Counterweighting for Guide Wear Reduction
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Solution Overview
Problem
Conventional component recognizing devices in surface mounting and component testing machines face accuracy issues due to wear in the ball screw and nut mechanism, leading to instability and decreased positioning accuracy, which affects long-term image recognition and component mounting quality.
Innovation Solution
A component recognizing device utilizing a linear motor and linear guides, where the linear motor's attraction force is managed by orienting the permanent magnets and coil portion to reduce stress on the guides, ensuring stable and accurate image recognition over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a ball screw shaft and ball and nut mechanism are used to drive the scan unit, then the device complexity is reduced and ease of manufacture is improved, but wear occurs in the ball screw and nut mechanism leading to decreased positioning accuracy and reliability over time
Solution Approach 1:
The patent replaces the ball screw and ball and nut mechanical transmission system with a linear motor that directly drives the scan unit along linear guides. This substitution eliminates the wear-prone mechanical transmission components while maintaining the ability to achieve precise positioning through direct electromagnetic drive, thereby resolving the contradiction between ease of manufacture and long-term positioning accuracy.
2Reliability
If a linear motor is used to drive the scan unit, then positioning accuracy is improved and reliability is enhanced, but excessively large stress is applied on the guide means causing wear and rattling
Solution Approach 1:
The patent positions the stator of the linear motor with its bottom surface facing downward, generating an upward attraction force on the mover that counteracts the downward gravitational force on the scan unit. This counterbalancing of forces reduces the stress on the linear guides, preventing excessive wear and rattling while maintaining the high positioning accuracy benefits of the linear motor system.
3Force
If the stator bottom surface is faced downward to counteract gravity, then the attraction force counteracts gravity reducing stress on guides, but the attraction force still acts on the guide means
Solution Approach 1:
By orienting the stator bottom surface downward, the linear motor generates an upward attraction force that directly counteracts the gravitational force on the scan unit. This configuration creates a balanced force system where the attraction force serves as a counterweight to gravity, significantly reducing the net stress on the linear guides while maintaining effective drive capability.
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 provides stable and accurate image recognition and component positioning, maintaining high mounting and inspection accuracy over a long term by minimizing wear and rattling in the guide system.
Implementation Method 1
a linear motor driving the scan unit in the moving direction by an interaction of magnetic fluxes generated by a stator and a mover while generating an attraction force between the stator and the mover
Implementation Method 2
the linear motor is driving the scan unit in the moving direction by an interaction of magnetic fluxes generated by permanent magnets and a coil portion
Data Source
AI summary
To enable image recognition of a component at a high degree of accuracy in a stable manner over a long term with a component recognizing device configured to take an image of a component by moving a scan unit having an imaging device using a linear motor, and a surface mounting machine and a component testing machine each equipped with the component recognizing device. The component recognizing device includes permanent magnets (732) that are fixed to a head unit (6) in a state where surfaces (732a) opposing a coil portion (733) are faced downward. The coil portion (733) is disposed at a position directly below the permanent magnets (732). An attraction force (FM) induced between the coil portion (733) and the permanent magnets (732) therefore acts on linear guides (72) in an upward direction (+Z direction) via a bottom frame (731). On the contrary, the own weights (Fig) of a scan unit (71) and the like act in a downward direction. It thus becomes possible to ease the influence of the attraction force (Fm) applied on the linear guides (72) correspondingly to the own weights (Fg).