Method and design for productive quiet abrasive blasting nozzles

Patent metadata

Field	Value
Publication number	US-12280468-B2
Application number	US-202016819035-A
Country	US
Kind code	B2
Filing date	Mar 13, 2020
Priority date	Dec 11, 2018
Publication date	Apr 22, 2025
Grant date	Apr 22, 2025

Abstract

Reduced noise abrasive blasting assemblies and systems are described. The new assemblies and systems are comprised of standard blast hose, accelerator hose, couplings and nozzle. The improved abrasive blasting system maintains abrasive particle velocity while decreasing the exit gas velocity and consequently decreasing sound production. This is accomplished through an acceleration section with reduced inner diameter and sufficient length to provide the necessary abrasive particle velocity. The new system maintains the productivity and efficiency of conventional abrasive blasting systems but with greatly reduced acoustic noise production and reduces operator fatigue due to the lower weight of the carried portion of the system.

First claim

The invention claimed is:

1. A productive abrasive blasting nozzle, comprising:
a converging portion having a converging internal diameter;
a throat having an internal diameter connected to the converging portion, wherein the throat has a length extending from a beginning of the throat to an end of the throat;
a diverging portion having an internal diameter connected to the throat; and
a straight portion having an internal diameter connected to and immediately following the diverging portion;
wherein the straight portion has a length such that a velocity of gas exiting the blasting nozzle is reduced by at least 30% relative to the blasting nozzle with the straight portion removed, when operated with a predetermined gas and particle mix and pressure;
wherein, in operation, fluid flows through the converging portion, the throat, the diverging portion, and the straight portion, in that order; and
wherein the length, L, of the straight portion is at least L*, as given by the following equation:

L
*

=

D

4
⁢

(

f
_

+

f
abrasives

)

⁡

[

1
-

M
2

γ
⁢

⁢

M
2

+

γ
+
1

2
⁢
γ

⁢

ln
⁡

(

(

γ
+
1

)

⁢

M
2

2
+

(

γ
-
1

)

⁢

M
2

)

]

where D is a diameter of the straight section, M is the Mach number of the fluid at an entrance to the straight portion, f is the average friction factor of the straight portion, f abrasives is the friction factor of the particles in the fluid flow, and γ is the specific heat ratio of the fluid flow, for a predetermined gas and abrasive particle mixture.

2. The productive abrasive blasting nozzle of claim 1 , wherein an internal diameter of the straight portion is less than a largest internal diameter of the converging portion.

3. A productive abrasive blasting nozzle assembly comprising the reduced noise abrasive blasting nozzle of claim 1 .

4. The productive abrasive blasting nozzle of claim 1 , wherein the nozzle is configured such that, for the predetermined gas and particle mix and pressure, supersonic flow occurs inside of the nozzle and the supersonic gas flow accelerates the abrasive particles in the straight section.

5. The productive abrasive blasting nozzle of claim 1 , wherein the nozzle is configured such that gas Mach number for the predetermined gas and particle mix and pressure is lower at the exit of the straight portion than at the exit of the diverging portion, thereby reducing noise of operation.

6. The productive abrasive blasting nozzle of claim 5 , wherein the nozzle is configured such that gas Mach number for the predetermined gas and particle mix and pressure is reduced from greater than one at the exit of the diverging portion to one at the exit of the straight portion.

7. The productive abrasive blasting nozzle of claim 1 , wherein the length of the straight portion is at least twenty percent of the internal diameter of the straight portion.

8. The productive abrasive blasting nozzle of claim 1 , wherein the length of the straight portion is less than ten times the internal diameter of the straight portion.

9. The productive abrasive blasting nozzle of claim 1 , wherein the length of the straight portion is between 1″ and 10″.

10. The productive abrasive blasting nozzle of claim 1 , wherein the length of the straight portion is 2.5″.

11. The productive abrasive blasting nozzle of claim 1 , wherein the straight portion is configured to be attached to and detached from the diverging portion.

12. The productive abrasive blasting nozzle of claim 11 , further comprising one or more additional straight portions configured to be attached to and detached from the diverging portion, wherein the straight portion and the one or more additional straight portions each have a different length or inner diameter.

13. The productive abrasive blasting nozzle of claim 12 , wherein each of the one or more additional straight portions has a length such that, when operated with a different predetermined gas and particle mix and pressure, a velocity of gas exiting the blasting nozzle is reduced by at least 30% relative to the blasting nozzle with the straight portion removed.

14. The productive abrasive blasting nozzle of claim 1 , wherein the straight portion is cylindrical in shape.

15. The productive abrasive blasting nozzle of claim 1 , wherein the nozzle is a #4 nozzle, a #5 nozzle, a #6 nozzle, a #7 nozzle, or a #8 nozzle.

16. The

Assignees

• Kennametal Inc

Inventors

• Sullivan Christopher

Classifications

• B24C3/02

  characterised by the arrangement of the component assemblies with respect to each other (B24C3/08, B24C3/18 take precedence) · CPC title

• B24C7/0046

  the abrasive material being fed in a gaseous carrier · CPC title

• B24C7/0053

  with control of feed parameters, e.g. feed rate of abrasive material or carrier · CPC title

• B05B1/002

  designed to reduce the generation or the transmission of noise or to produce a particular sound; associated with noise monitoring means · CPC title

• B24C7/0061

  of feed pressure · CPC title