NOISE REDUCTION APPLIANCE

Abstract

A noise reduction appliance for connection to, or integrally formed with, an outlet end of a blast nozzle, the blast nozzle having an outlet with a nozzle outlet diameter, the noise reduction appliance comprising an appliance body with a conduit formed therethrough, the conduit extending from an inlet opening of the appliance body to an outlet opening of the appliance body, the inlet opening of the appliance body having an inlet opening diameter substantially equal to the nozzle outlet diameter; and the outlet opening of the appliance body having an outlet opening diameter greater than the inlet opening diameter; wherein a radius of the conduit monotonically increases with distance, from the inlet opening to the outlet opening.

Description

TECHNICAL FIELD

The present invention relates to a noise reduction appliance for connection to, or integrally formed with, a blast nozzle for use in abrasive blasting works.

BACKGROUND

Any references to methods, apparatus or documents of the prior art are not to be taken as constituting any evidence or admission that they formed, or form part of the common general knowledge.

It is known to provide a blasting apparatus in which particles of abrasive material entrained in a stream of pressurised gas, most usually air, are expelled from a nozzle in a high velocity jet of the air that is directed onto a surface in order that the particles forcibly impact the surface to clean and/or abrade the surface.

This process is particularly beneficial in the preparation of a workpiece for further work such as painting, welding or coating in other chemicals or materials. Such activities can result in high frequency noise which can be destructive not only to the worker conducting the blasting activity but also those workers in the general proximity. While the worker conducting the blasting activity is typically required to wear personal protective equipment, referred to as PPE, in many cases the high frequency noises can still cause damage to someone's hearing.

As such, improvements to the equipment and/or PPE are beneficial in reducing workplace injury and/or long term hearing loss.

SUMMARY OF INVENTION

In an aspect, the invention provides a noise reduction appliance for connection to, or integrally formed with, an outlet end of a blast nozzle, the blast nozzle having an outlet with a nozzle outlet diameter, the noise reduction appliance comprising:

• • an appliance body with a conduit formed therethrough, the conduit extending from an inlet opening of the appliance body to an outlet opening of the appliance body, the inlet opening of the appliance body having an inlet opening diameter substantially equal to the nozzle outlet diameter; and
  • the outlet opening of the appliance body having an outlet opening diameter greater than the inlet opening diameter;
  • wherein a radius of the conduit monotonically increases with distance, from the inlet opening to the outlet opening.

In an embodiment, the radius of the conduit increases with distance from the inlet opening of the appliance to the outlet opening of the appliance to define a bell.

In an embodiment, the appliance body is formed with a female thread on a side of the inlet opening opposite the conduit of the appliance for forming a threaded connection with a complementary male thread about an outlet end portion of the blast nozzle.

In an embodiment, the appliance body is formed with a male thread on a side of the inlet opening opposite the conduit of the appliance for forming a threaded connection with a complementary female thread about an outlet end portion of the blast nozzle.

In an embodiment, the appliance body is integrally formed with the blast nozzle.

In an embodiment, the conduit between the inlet opening of the appliance body and the outlet opening of the appliance body defines a convex shape.

In an embodiment, the conduit comprises a smooth surface.

In an embodiment, the appliance body is configured to connect to the end of a blast nozzle such that the outlet end of the blast nozzle and the conduit at the inlet opening of the appliance body are fluidly connected.

In an embodiment, a diameter of the appliance body decreases along an outer diameter of the appliance so as to define a gripping portion or portion thereof of the appliance.

In an embodiment, the length between the inlet opening and the outlet opening is approximately 21 millimetres.

In an embodiment, the outlet opening diameter of the appliance body is approximately 40 millimetres.

In an embodiment, the radius of curvature of the conduit is approximately 19.9 millimetres.

In an embodiment, an axial length of the appliance body from the inlet opening to the outlet opening is approximately 21 millimetres.

In an aspect, the invention provides a method of reducing noise of a blast nozzle by use of an appliance connected to, or integrally formed, with an outlet end thereof the method comprising baffling and expanding a stream of gas from the nozzle outlet by means of the appliance.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way. The Detailed Description will make reference to a number of drawings as follows:

FIG. 1 is an isometric view of the noise reduction appliance according to an embodiment of the present invention.

FIG. 2 is a cross section of the noise reduction appliance of FIG. 1.

FIG. 3 is a front view of the noise reduction appliance of FIG. 1.

FIG. 4 is a rear view of the noise reduction appliance of FIG. 1.

FIG. 5 is a cross section flow diagram of the noise reduction appliance of FIG. 1.

FIG. 6 is a cross section of a noise reduction appliance integrally formed with a jacket of a blast nozzle without the blast nozzle liner according to an embodiment of the present invention.

FIG. 7 is a plurality of appliance geometries which were considered and tested during experimentation.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1 to 4 illustrate a preferred embodiment of the noise reduction appliance 10 according to an embodiment of the present invention. The noise reduction appliance 10 may be a separate component as seen in FIGS. 1 to 5. As such, the noise reduction appliance 10 as a separate component may be releasably coupled to a blast nozzle (not independently shown). In the preferred embodiment, the coupling is done by way of threaded engagement between the noise reduction appliance 10 and the blast nozzle. For example, as can be seen in FIG. 2, female threads are provided on the noise reduction appliance 10. Complementary male threads would be located on the blast nozzle. Alternatively, the blast nozzle may comprise female threads and the noise reduction appliance 10 may comprise the male threads for coupling together. The coupling of the blast nozzle and the noise reduction appliance 10 fluidly connects a conduit of the blast nozzle and the conduit 20 of the noise reduction appliance 10.

Throughout the specification reference is made to diameters of specific features. The person skilled in the art would readily appreciate that the diameter is the product of the radius times two.

Alternative releasable coupling means are known in the art which may be used to give effect to the present invention. In alternative embodiments, the noise reduction appliance 10 may be integrally formed, that is to say formed of a single piece construction, with the blast nozzle as seen in FIG. 6. The blast nozzle will have a conduit which runs therethrough fluidly connected with the conduit 20 of the noise reducing appliance 10. An outlet end of the blast nozzle comprises an outlet having a nozzle outlet diameter. The outlet conveys accelerated air and/or abrasive particles to a conduit 20 of the noise reduction appliance 10. Throughout the specification the noise reduction appliance 10 may be referred to as ‘the appliance’.

The noise reduction appliance 10 comprises a conduit 20. The conduit 20 is formed through the body 12 of the noise reduction appliance 10. The conduit 20 extends from an inlet opening 22 of the appliance body 12 through to an outlet opening 24 of the appliance body 12. Preferably, the inlet opening diameter 22D is equal or slightly larger than the nozzle outlet diameter. As the fluid being sprayed through the nozzle and the noise reducing appliance 10 is entrained with an abrasive, any shoulders will be ground away. In the alternative, if the inlet opening diameter 22D is too much larger, the fluid being sprayed through the nozzle may become turbulent which may reduce the noise reduction benefit. In some embodiments, the inlet opening diameter 22D may be substantially equal to the nozzle outlet diameter.

The outlet opening diameter 24D at the outlet opening 24 of the appliance 10 comprises a larger diameter than the inlet opening diameter 22D at the inlet opening 22. The change in diameter of the conduit 20 between the inlet opening 22 and the outlet opening 24 increases according to the distance from the inlet opening 22 towards the outlet opening 24. The increase in the diameter of the conduit 20 may be said to be monotonically increasing. As the diameter of the conduit 20 increase from the inlet opening diameter 22D to the outlet opening diameter 24D, the housing 12 of the appliance 10 defines a bell. The term bell being used generally to mean a shape which broadly conforms to a uniform bell curve. Accordingly, closest to a central axis 100 of the body 12 of the appliance 10, the conduit is substantially parallel with the central axis 100.

As the distance from the inlet opening 22 increases towards the outlet opening 24, the conduit 20 begins to flair out to a maximum diameter of the outlet opening diameter 24D. The conduit may flair out to a lip 32 as the thickness of a wall of the housing 12 of the appliance may provide some additional stability with the accelerated air exiting the outlet opening 24. Preferably, the conduit 20 between the inlet opening 22 and the outlet opening 24 defines a convex shaped boundary relative to the central axis 100. Accordingly, the shape of the housing 12 is convex relative to the central axis 100.

The inventors have conducted a substantial amount of experimentation to reduce the noise coming from a blast nozzle. The inventor developed and tested many different shapes of conduits as seen generally in FIG. 7 using preferred materials as well as 3D printed prototypes. During this process, the inventor became aware of differences between the 3D printed prototypes when compared with identical machined counterparts. In this particular application, the inventor discovered that the surface of the conduit 20 between the inlet opening 22 and the outlet opening 24 being smooth resulted in improved noise reduction when compared to 3D printed versions. While there is no quantitative value for the level of smoothness, there preference is for smooth to the touch. This level may be provided by standard machining. As above, the fluid being sprayed through the noise reduction appliance is entrained with an abrasive, any imperfections will be smoothed by the abrasive. Without being bound by theory, it is hypothesised that the conduit 20 having a smooth surface may allow the accelerated air exiting the outlet opening 24 additional surface area to bond to thereby providing more expansion prior to exiting through the outlet opening 24. This is understood to reduce the speed of the outermost layer of air at the boundary layer. This reduction is hypothesised to reduce the turbulent flow which produces the screech tones caused by the turbulent air generated at the boundary layer between the jets of accelerated air, with or without abrasive material, and the ambient air adjacent the jets of accelerated air.

Accelerating air in the context of the present specification means accelerating air at a pressure greater than ambient pressure. The present invention has been designed for optimal performance at an operating pressure between 80 and 100 psi with the preferred operating pressure being 100 psi. The present invention will still work at operating pressures outside of this range but may have reduced efficiency.

As seen in FIG. 6, the jacket of the blast nozzle and the appliance 10A are integrally formed. The blast nozzle liner is received within an internal recess of the jacket or a channel extending along axis 100 to or towards the inlet opening 22 of the noise reduction appliance 10A. As mentioned above, the conduit of the blast nozzle outlet is preferably equal to or slightly smaller than the inlet opening 22 of the noise reduction appliance 10A. In some embodiments, the diameter of the appliance body 12 may decrease along the length of the appliance 10A and/or blast nozzle and then increase back to an original diameter so as to define a gripping portion 40. Said gripping portion 40 may include rubber holds for increasing the ability of the appliance 10A to be gripped. The rubber holds may also consist of other materials known in the art that aid to increase operator grip. The rubber holds may be applied with adhesive and/or may be embedded in the housing 12 of the appliance 10A. Gripping the appliance 10A may be particularly difficult if it becomes wet.

The present invention is intended to be used with conventional and non-conventional sized blast nozzles. Example of one of the preferred embodiments is provided below with measurements provided in millimetres.

An example of a preferred embodiment of the appliance 10A is provided above. From the above, the preferred length 26 between the inlet opening and the outlet opening is 21 millimetres. The preferred outlet opening diameter 24D is 40 millimetres. The preferred radius of curvature of the conduit 20 as it flairs outward from the central axis 100 from the inlet opening 22 to the outlet opening 24 is 19.9 millimetres.

While the inlet opening 22 may change relative to the standard sizing of blast nozzle and/or appliance 10 being used, the inventors have found that the advantageous benefits remain provided the outlet opening 24 is substantially 40 millimetres, the radius of curvatures of the conduit 20 is 19.9 millimetres and the length from the inlet opening 22 to the outlet opening 24 is substantially 21 millimetres. The table below sets out noise reduction results related to testing of two different geometry prototype appliances 10 as shown in FIG. 7 of the Drawings, at nozzle inlet pressure range from 80-110 psi. The largest noise reduction and most preferred embodiment is the geometry of prototype 3 (as seen in FIG. 7).

By way of example, the present invention when tested at various operating pressures resulted in the following outcomes. As can be seen from the table below, when compared to a blast nozzle without the appliance 10, 10A the Sound Level A-weighted fast maximum is at least 0.5 db higher without an appliance 10, 10A being used with the blast nozzle. In the extreme cases, the appliance 10, 10A results in a reduction of 7.6 db.

Appliance	Pressure (psi)	Sound LAFmax (db)
Original	110	127.2
3	110	122.8
8	110	123.8
Original	100	127.4
3	100	121.9
8	100	122.5
Original	90	125.9
3	90	120.8
8	90	125.5
Original	80	128
3	80	120.4
8	80	125.1

The method of reducing noise of a blast nozzle by use of an appliance 10 connected to, or integrally formed 10A, with an outlet end thereof the method comprising baffling and expanding a stream of gas from the nozzle outlet by means of the appliance 10, 10A. The method may be accomplished using one of the appliances 10, 10A as described herein.

The appliance 10, 10A baffles the accelerated air through the inlet opening 22. Once passing through the inlet opening 22, the accelerated air is free to expand according to the shape of the conduit 20.

As mentioned above, through extensive experimentation with materials and designs, the inventors have invented a noise reduction appliance 10 for use with a blast nozzle. There is provided specific dimensions for the preferred embodiment of the noise reduction appliance 10. However, the inventor has found that the relative dimensions may be scaled to different size requirements while still achieving the benefits of noise reduction. Accordingly, while there are specific dimensions provided above, the broadest scope of the present invention should not be limited in any way to those dimensions.

Furthermore, while the present invention has been described with respect to pneumatic operation, it may reasonably be expected that such benefits may be achieved with hydraulic operation. Accordingly, it may best be described as accelerating a fluid through a conduit.

In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. The term “comprises” and its variations, such as “comprising” and “comprised of” is used throughout in an inclusive sense and not to the exclusion of any additional features.

It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect.

The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted by those skilled in the art.

Claims

1. A noise reduction appliance for connection to, or integrally formed with, an outlet end of a blast nozzle, the blast nozzle having an outlet with a nozzle outlet diameter, wherein the noise reduction appliance comprises:

an appliance body with a conduit formed therethrough, the conduit extending from an inlet opening of the appliance body to an outlet opening of the appliance body, the inlet opening of the appliance body having an inlet opening diameter substantially equal to the nozzle outlet diameter; and

the outlet opening of the appliance body having an outlet opening diameter greater than the inlet opening diameter;

wherein a radius of the conduit monotonically increases with distance, from the inlet opening to the outlet opening; and

wherein the conduit between the inlet opening of the appliance body and the outlet opening of the appliance body defines a convex shape.

2. A noise reduction appliance as claimed in claim 1, wherein the radius of the conduit increases with distance from the inlet opening of the appliance to the outlet opening of the appliance to define a bell.

3. A noise reduction appliance as claimed in claim 1, wherein the appliance body is formed with a female thread on a side of the inlet opening opposite the conduit of the appliance, for forming a threaded connection with a complementary male thread about an outlet end portion of the blast nozzle.

4. A noise reduction appliance as claimed in claim 1, wherein the appliance body is formed with a male thread on a side of the inlet opening opposite the conduit of the appliance, for forming a threaded connection with a complementary female thread about an outlet end portion of the blast nozzle.

5. A noise reduction appliance as claimed in claim 1, wherein the appliance body is integrally formed with the blast nozzle.

6. A noise reduction appliance as claimed in claim 1, wherein the conduit comprises a smooth surface.

7. A noise reduction appliance as claimed in claim 1, wherein the appliance body is configured to connect to the end of a blast nozzle such that the outlet end of the blast nozzle and the conduit at the inlet opening of the appliance body are fluidly connected.

8. A noise reduction appliance as claimed in claim 1, wherein an outer diameter of the appliance body decreases along a longitudinal section of the appliance so as to define a gripping portion or portion thereof of the appliance.

9. A noise reduction appliance as claimed in claim 1, wherein the length between the inlet opening and the outlet opening is 21 mm.

10. The noise reduction appliance as claimed in claim 1, wherein the outlet opening diameter of the appliance body is 40 mm.

11. A noise reduction appliance as claimed in claim 1, wherein the radius of curvature of the conduit is 19.9 mm.

12. A noise reduction appliance as claimed in claim 1; wherein an axial length of the appliance body from the inlet opening to the outlet opening is 21 mm.

13.-14. (canceled)