Abrasive Blasting Nozzle Control to Prevent Media Slug Formation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Abrasive blasting apparatuses face issues with blast media slugs forming due to inadequate airflow and residual media in the hose, leading to loss of control and potential damage or harm during operation.
Innovation Solution
A control system with a deadman's switch featuring an intermediate position that establishes airflow before and maintains it after blast media delivery, preventing slug formation by ensuring a continuous airflow to flush residual media from the hose.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If compressed air and blast media are supplied together to the blast hose, then the blasting operation can commence, but blast media accumulates and forms slugs due to insufficient initial airflow
Solution Approach 1:
The system performs preliminary action by establishing compressed airflow through the blast hose before introducing blast media. The control system sequences the supply so that air flow is commenced first, allowing the hose to be pressurized and ready to carry media, then blast media is introduced subsequently. This preliminary establishment of airflow prevents media accumulation and slug formation that would occur if both were supplied simultaneously.
2Productivity
If compressed air and blast media supply are stopped together, then the blasting operation can be terminated, but residual blast media remains in the hose and forms or enlarges slugs upon reintroduction
Solution Approach 1:
The system maintains continuity of useful action by keeping compressed air flowing through the blast hose for a period after blast media supply is stopped. This continuous airflow serves to flush residual media from the hose, clearing it before the next blasting operation begins. When blasting is restarted, the hose is already clear of residual media, preventing slug formation that would occur if both air and media were stopped together.
3Device complexity
If a deadman's switch with only two positions is used, then the control system is simple, but it cannot establish airflow before media delivery or flush residual media
Solution Approach 1:
The control system applies segmentation by dividing the deadman's switch into three distinct positions: first position for air-only supply, second position for simultaneous air and media supply, and third position for air-only flow after media cessation. This segmentation allows independent control of air and media delivery, enabling the system to establish airflow before media introduction and to flush residual media after media supply stops, thereby preventing slug formation while maintaining relatively simple control mechanism.
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 control system significantly reduces the frequency and severity of blast media slugs, enhancing user safety and control by ensuring a consistent airflow and flushing residual media, thereby preventing unintended slug ejection.
Implementation Method 1
a flow of compressed air is used to entrain blast media such as sand, grit or glass beads
Implementation Method 2
supply of compressed air can be established before introduction of blast media and compressed air continues to flow for a period after the supply of blast media ceases
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A control system for controlling abrasive blasting apparatus (100) and an abrasive blasting apparatus including such a control system. The control system controls delivery of air and blast media to a blast nozzle (3) of the abrasive blasting apparatus (100). The control system includes a deadman's switch (60), the deadman's switch (60) features a user operable control. The user operable control is moveable from a first position, where the control system causes the abrasive blasting apparatus to not deliver air or blast media, to a second position where the control system causes the abrasive blasting apparatus (100) to deliver both air and blast media. When the user operable control is in an intermediate position between the first and second positions, the control system causes the abrasive blasting apparatus to deliver air but not blast media. The control system may have control elements whose state may be sequentially changed by the user operable control as it moves.