Mounting Head Position Retainer for SMT Maintenance
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Solution Overview
Problem
Existing mounting heads face issues with maintenance properties and device reliability due to the mechanical valve structure's reliance on a rotary motor drive unit, which causes the switching member to drop when powered off, leading to potential component drop and hindered maintenance operations.
Innovation Solution
Incorporating a position retainer, such as a magnetic spring, to hold the movable portion away from the valve spool's pressure application positions during power-off, preventing accidental pressure switching and allowing for maintenance without component loss, and utilizing a linear motor for precise movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a rotary motor drive unit is used to move the switching member, then the valve spool can be positioned accurately during operation, but the switching member drops when powered off, causing maintenance obstacles and component loss
Solution Approach 1:
The patent replaces the purely mechanical spring-based positioning system with a magnetic field-based positioning system. The magnetic valve spool positioning mechanism uses magnetic attraction forces to hold the valve spool in its neutral position during power-off, eliminating the need for mechanical springs that can fail or cause unwanted movement. This substitution maintains positioning accuracy while preventing the switching member from dropping during maintenance operations.
Solution Approach 2:
The patent changes the physical state and interaction parameters of the valve spool positioning mechanism. Instead of relying on mechanical contact and spring force, the system uses magnetic field parameters to control the valve spool's position. The magnetic field strength and distribution are adjusted to provide sufficient holding force during power-off while allowing precise positioning during operation, thereby resolving the contradiction between positioning accuracy and maintenance reliability.
2Ease of operation
If the switching member is allowed to move freely when powered off, then maintenance operations can be performed, but the valve spool moves to the positive pressure application position causing component drop
Solution Approach 1:
The patent introduces a magnetic field as an intermediary force between the power supply system and the valve spool. During power-off, the magnetic field acts as a mediator that maintains the valve spool in its neutral position without requiring continuous power input. This intermediary magnetic field prevents the valve spool from moving to the positive pressure application position, thereby preventing component drop while still allowing maintenance operations to be performed.
Solution Approach 2:
The patent applies preliminary anti-action by using the magnetic field to counteract any potential movement of the valve spool before it can reach the positive pressure application position. The magnetic holding force is continuously applied during power-off to prevent the valve spool from moving, thereby preventing the harmful effect of component drop before it can occur.
3Device complexity
If a mechanical spring is used to hold the switching member, then the structure is simple, but the spring may contact the valve spool at pressure application positions causing unwanted pressure switching
Solution Approach 1:
The patent substitutes the mechanical spring system with a magnetic field-based system. The magnetic field provides a non-contact holding force that eliminates the risk of mechanical contact between the spring and valve spool at pressure application positions. This substitution maintains structural simplicity while significantly improving pressure control reliability by eliminating unwanted pressure switching caused by spring contact.
Solution Approach 2:
The magnetic field serves as an intermediary that provides the holding force without direct mechanical contact. This intermediary approach allows the system to maintain simplicity while avoiding the harmful contact between spring and valve spool, thereby preventing unwanted pressure switching and improving overall reliability.
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
Enhanced maintenance properties and improved device reliability by preventing component drops and allowing for safe rotation of the mounting head during power-off, with the magnetic spring providing stable retention and high positional accuracy.
Implementation Method 1
Inclining the lower end portion of the yoke 132 rearward, a magnetic spring 142 is integrated into the lower end portion of the yoke 132. The magnetic spring 142 includes a magnetic body 144 and a magnet 146.
Data Source
AI summary
A mounting head includes a pickup nozzle, a shaft member, a drive unit, and a position retainer. The shaft member has a cylindrical shape and moves in an axial direction to switch a pressure applied to the pickup nozzle between negative and positive pressures. First and second movement ends in the axial direction are negative and positive pressure application positions, respectively, where negative and positive pressure, respectively, is applied to the pickup nozzle. The drive unit includes a drive source that moves a movable portion in the axial direction. The movable portion contacts the shaft member when moved in the axial direction, to move the shaft member between the negative and positive pressure application positions. During a power-off period of the drive source, the position retainer holds the movable portion in a predetermined position away from the shaft member located at the negative or positive pressure application positions.