Abrasive Waterjet Piercing Device with Annular Flow Path

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Solution Overview

Problem

Conventional abrasive waterjet systems face difficulties in piercing composite and brittle materials due to hydrostatic pressure buildup, which can cause delamination or cracking, and require additional techniques like pressure ramping or vacuum assist devices to mitigate damage.

Innovation Solution

The use of a piercing device with a mixing tube and secondary tube configuration that introduces air into the abrasive waterjet, allowing for effective piercing of composite and brittle materials without additional hardware, reducing hydrostatic pressure and enabling precise control of hole diameter and kerf width.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the jet nozzle size is reduced to achieve smaller hole diameter and kerf width, then the hole diameter and kerf width are reduced, but it becomes difficult to pierce certain materials and control hydrostatic pressure

Engineering Contradiction:

Improvehole diameter and kerf widthVSAvoidnozzle size reduction difficulty

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

A piercer rod is introduced as an intermediary component between the mixing tube and the workpiece. The piercer rod has a diameter smaller than the mixing tube inner diameter, creating an annular flow path that allows water to flow around it. This intermediary structure enables precise hole diameter control while maintaining effective piercing capability through the annular jet configuration.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If conventional abrasive waterjet is used to pierce composite and brittle materials, then material removal occurs, but hydrostatic pressure buildup causes delamination or cracking

Engineering Contradiction:

Improvematerial removalVSAvoidhydrostatic pressure damage

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The harmful hydrostatic pressure is extracted or removed from the piercing process by using an annular jet configuration where water flows around the piercer rod. This configuration prevents pressure buildup within a closed cavity by allowing continuous pressure relief through the annular flow path, while still achieving effective material removal through the abrasive jet.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of using a solid rod that blocks water flow (which creates pressure buildup), the invention inverts the approach by using a thin piercer rod that allows water to flow around it in an annular path. This inversion transforms the blocking configuration into a flow-through configuration, eliminating hydrostatic pressure while maintaining piercing function.

Inventive Principle:

Principle #13The other way round (Inversion)

3Object-affected harmful factors

If pressure ramping or vacuum assist devices are used to mitigate piercing damage, then material damage is reduced, but device complexity and process time increase

Engineering Contradiction:

Improvepiercing damageVSAvoidadditional hardware

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The annular jet configuration inherently prevents hydrostatic pressure buildup through its geometry, eliminating the need for external pressure control systems. The water flow automatically relieves pressure by flowing around the piercer rod, making the system self-regulating and eliminating the need for vacuum assist devices or complex pressure ramping controls.

Inventive Principle:

Principle #25Self-service

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 configuration allows for precise piercing of composite and brittle materials without damage, reducing hole diameters and kerf widths, and enabling the use of larger abrasives while maintaining effective material removal, thus overcoming the limitations of conventional techniques.

Implementation Method 1

The use of a piercing device with a mixing tube and secondary tube configuration that introduces air into the abrasive waterjet

Methodology Applied

Scientific EffectAir entrainment: Air Entrainment

Implementation Method 2

Abrasives can be added to the waterjet to improve the cutting or piercing power of the waterjet. Adding abrasives results in an abrasive-laden waterjet referred to as an 'abrasive waterjet' or an 'abrasive jet.'

Methodology Applied

Scientific EffectAbrasion: Abrasion

Data Source

PatentUS8821213B2Piercing and/or cutting devices for abrasive waterjet systems and associated systems and methods

Publication Date: 2014.09.02 HYPERTHERM INC

AI summary

Embodiments of abrasive jet piercing and/or cutting devices are described herein. In some embodiments, a piercing device includes a holding or positioning device coupling a mixing tube to a secondary tube. The holding device has one or more passages extending to at least an intermediate portion of the piercing device. The one or more passages allow air to contact or mix with an abrasive waterjet as it travels through the piercing device. In some embodiments, a cutting device includes two plates configured so as to form a slot between the two plates. The cutting device can be placed directly on a workpiece, and an abrasive waterjet can be directed at the workpiece through the slot. An abrasive waterjet system utilizing the piercing and cutting devices disclosed herein can pierce holes and cut slots in materials that have reduced hole diameters and kerf widths, respectively.