GB2084910A - Improvements in shot blast machines - Google Patents

Abstract

A shot blast machine in which the blades 9 are formed outwardly of the rims 19 of the discs with a raised portion 20 on one or both sides so that the abrasive diverges for delivery over a wide arc in the axial direction of the wheel. <IMAGE>

Description

SPECIFICATION Improvements in shot blast machines This invention relates to improvements in abrasive or shot blast cleaning machines.

Shot blase or abrasive cleaning machines are normally constructed with a plurality of rotary blades, each mounted between a pair of discs or projected from one side of a single disc rotating about an impeller to which the abrasive, commonly in the form of shot or grit, is supplied and by which it is distributed to the blades and thrown out by centrifugal force onto the articles to be cleaned. The abrasive is supplied to the blades through an aperture in a stationary control cage as they rotate.

The stream of abrasive from the blades travels radially outwards and only spreads to a very limited degree and accordingly is deflected back from the articles being cleaned into the stream from the blades and reduces the velocity of the shot ejected from the blades, and the object of the invenion is to increase the arc over which the abrasive is distributed onto the articles, and to prevent the shot from being deflected back into the stream from the blades.

According to the invention each blade of an abrasive or shot blast cleaning machine is mounted between two discs or wheels or on one side of a single disc and comprises a plate formed with a wedge shaped projection at the delivery end of the blade to divide the abrasive or shot projected centrifugally from each blade into two streams to impinge on articles to be cleansed at diverging angles to increase the angle of contact on the articles.

The invention will be described with reference to the accompanying drawings:- Figure 1 is a plan view of the wheel centre line through a typical shot blast machine.

Figure 2 is a vertical section through a typical wheel hood, the wheel and the blade.

Figure 3 is a plan of a blade to a larger scale side elevation of a blade.

Figure 4 is a side elevation of a blade.

Figure 5 is a section on line 5-5 of Fig. 3.

Figure 6 is a section on line 6-6 of Fig. 3.

Figure 7 is a front view of a further blade.

Figure 8 is a section on line 8-8 of Fig. 7.

Figure 9 is an end view of the blade shown in Fig. 7.

Figure 10 is a perspective view of a wheel shown in Fig. 1 and 2.

A sand blasting machine is constructed with a wheel 8, a hood 1 having a lining 3,4 and base 2. The hood is formed with a hood end 5 and a curved lining 6, and a side end lining surrounding the wheel (or the linings may be omitted) and a central abrasive impeller 11 in dispenser 1 2. A seal 1 3 is mounted between the hood 1 and a seal retension disc 14. A dust retension 16 is mounted on a hub 10 which is driven by a motor 1 8. The impeller 11 is held by a screw 30. The dispenser 1 2 is adjusted by releasing a clamp plate 1 2a.

The central impeller 11 is supplied with abrasive from a feed chute which fits into the dispenser 1 2 forming a stationary control cage having an aperture therein through which the abrasive passes in turn to a plurality of blades 9 mounted between discs 1 9 or to a single disc forming wheel 8, and rotating concentrically with the impeller 11. The aforesaid description of the machine is all of known construction.

The blades 9 extend radially outwards beyond the circumference of the discs 1 9 in which they are mounted in guide grooves 1 9a (also of known construction) and are formed with raised portions 20 of wedge shape to divide the shot discharged along the blades into two diverging streams so that the shot impining on the article to be cleaned rebounds from the surface at acute angles thereto and accordingly rebounds therefrom at diverging angles and does not interfere with the stream from the blades. A raised lip 9a on the longitudinal edges of the face of the blades terminates short of the end of the blades to allow the stream of shot discharged from the blades to fan out when deflected by the wedges 20. The back of the blades may be formed with a recessed portion 9b along the longitudinal edges to engage the grooves 19a.

in the construction shown in Figs. 3-6 each blade 9 is positioned between the discs 19 by a projecting member 21 resting against a bar 22 extending transversely between the discs 1 9 the blades being held in position by centrifugal force during the rotation of the discs 19.

In the construction shown in Figs. 7-9 the back of each blade is formed with two projecting members 21a engaging a transverse bar 22 extending between the discs 19, and to which the blade is affixed by a screw 21a.

With a single sided disc or wheel the blades are mounted on one side only and are located in grooves or otherwise affixed to the disc or wheel.

The wedge 20 is positioned with the apex directed inwardly of the blade.

The abrasive as it is thrown out by centrifugal force impinges upon the wedge shaped portion and is directed outwardly over a iarge arc to increase the area of contact with the article to be cleaned. The angle of the wedge is preferably between 30 to 60 .

The inner surface of the discs are preferably case hardened to prolong their life.

The blades may be formed with raised wedges 20 on one or on both sides so that the machine may be operated to rotate in either direction.

The wedge 20 may be cast as part of the blade or of a harder metal such as Tungsten Carbide secured to the face of the blade.

In a modification the blade may be formed to direct the shot at an angle to the longitudinal axis of the blade.

Trials have been carried out on the following machines which gave excellent results.

The machine is constructed with discs or wheels and side plates forming guides for the blades approximately 22" wide, hardened all over including the inner faces, to support a flat wheel blade 9 i.e. no lip on edges, so that the wheel blades 9 project a distance beyond the end of the disc or wheel 1 9 so that each blast pattern spreads from approximately 2 to approximately 2' at 2' or 3' from the periphery of the discs or wheel.

And it has been found that with the blades constructed as herein described with each machine directing the stream of abrasive in two diverging directions, that a far greater cover can be obtained from each machine and substantial savings can be made in the power consumed or alternatively, smaller numbers of machines can be used to carry out the cleaning of the articles and blasting times can be greatly reduced because of the wider coverage and less particle inter-reaction.

Claims (5)

1. An abrasive or shot blast cleaning machine in which each throwing blade is mounted between two discs or wheels or on the side of a single disc and comprises a plate formed with a wedge shaped projection on the delivery end of the front side of the plate to divide the abrasive or shot or grit projected centrifugally from each blade into two streams to impinge on articles to be cleaned at diverging angles to increase the angle of contact of the streams on the articles.

2. An abrasive or shot blast cleaning machine, as in claim 1, which the blades slide in grooves in the discs to project radially therefrom and are provided with a projection(s) on their rear side to engage a bar extending transversely between the discs.

3. An abrasive or shot blast cleaning machine as in claim 2, in which the bar is attached by a screw to the rear side of the.

blade.

4. An abrasive or shot blast cleaning machine as in claim 1 in which the blade is carried on the side of a single disc.

5. An abrasive or shot blast cleaning machine substantially as described with reference to the accompanying drawings.