Sandblasting machine

Abstract

 In a sandblasting machine comprising a tank (2) for containing a mass of sand, equipped with an outfeed opening (6) and a substantially T-shaped connecting element (7), comprising a tank outfeed (6) tubular sleeve (12) and a tubular sleeve (13) transversal to the sleeve (12) and connected at a first end by a duct (8) to a source of compressed air (9) and at the second end, by a hose (10), to a nozzle (11) for dispensing a flow (F) of sand, there is, at the sleeve (12) upstream of the sand flow (F) dosing device (16), a pneumatic injector (17). (Figure 1).

Description

[0001] This invention relates to a sandblasting machine.

[0002] Prior art sandblasting machines comprise a case or tank for containing the sand, whose funnel-shaped lower end is connected, by a connecting element, on one side to a duct connected to an air compressor and on the other side to a flexible hose for connection to a nozzle out of which the pressurised jet of sand comes.

[0003] The above-mentioned connection, consisting of a block which substantially has the shape of an inverted T, comprises an upper tubular stretch inserted in a tank outfeed opening and a transversal lower tubular stretch for connecting the upper stretch to the compressed air feed duct and to the pressurised sand dispensing hose.

[0004] As is known, sandblasting machines of the above-mentioned type have several disadvantages.

[0005] In particular, for various reasons and in some circumstances, the connecting element is unable to guarantee correct feed and precise adjustment of the jet of pressurised sand.

[0006] Such disadvantages are usually due to the presence in the tank of stones or clumps of grains of sand, which, when they reach the upper tubular stretch of the connection, may obstruct or block sand flow feed to the flexible hose, despite the pressure generated by the flow of com-pressed air.

[0007] In addition to this, the gradual emptying of the tank results in a reduction in the pressure of the sand, and therefore in its flow, at the entrance to the connection and in the hose which feeds the nozzle.

[0008] The aim of this invention is, therefore, to overcome these disadvantages by providing a sandblasting machine where sand flow feed through the connecting element is not subjected to the disturbances which affect the sandblasting machines of the type described above.

[0009] Accordingly the invention achieves this aim with a sandblasting machine comprising the technical features described in one or more of the appended claims.

[0010] The technical features of the invention and its advantages are more apparent from the detailed description which follows, with reference to the accompanying drawings which illustrate a preferred, non-limiting embodiment of the invention, and in which:

• Figure 1 is a schematic view of a sandblasting machine according to this invention;
• Figure 2 is an enlarged view of a detail of Figure 1;
• Figure 3 illustrates a second embodiment of the detail of Figure 2;
• Figure 4 is an exploded view of the detail of Figure 3.

[0011] With reference to Figures 1 and 2, the numeral 1 denotes in its entirety a sandblasting machine.

[0012] The machine 1 comprises a tank 2 which is substantially in the shape of cylinder with an axis A, is adapted to contain a mass of sand and is supported by a trolley 3.

[0013] The numeral 4 denotes a funnel-shaped element inserted in an opening in the upper wall 5 of the tank, for filling the tank 2.

[0014] The lower end of the tank 2, having the shape of an inverted cone, comprises an outfeed opening 6 connected, by means of a connecting element 7 which substantially has the shape of an inverted T, on one side to an outfeed duct 8 for a source of compressed air or compressor, schematically illustrated with the block 9, and on the opposite side to a flexible hose 10, equipped at its free end with a nozzle 11 for delivering a flow F of pressurised sand.

[0015] More precisely, with reference in particular to Figure 2, the connecting element 7 comprises a sleeve 12 for outfeed from the tank 2, and a sleeve 13, transversal to the sleeve 12 and with a substantially horizontal axis, connected at a first end by the duct 8 to the compressor 9 and at the second end by the hose 10 to the nozzle 11.

[0016] As illustrated in Figure 1, the compressor 9 is also connected by a duct 8a derived from the duct 8 with the inside of the tank 2, in such a way that in practice it applies a predetermined pressure on the mass of sand.

[0017] The outfeed sleeve 12 comprises a first, upper portion 12a with an axis A, coaxial with the axis of the tank 2, and a second portion 12b, whose axis B is set at an angle of 45° to the axis A.

[0018] The two component portions 12a and 12b of the outfeed sleeve 12 form an elbow labelled 15 and the portion 12b is set at an angle to the transversal sleeve 13, in such a way as to feed the flow of sand to the hose 10 in a direction which is substantially the same as that of the flow of compressed air from the compressor 9.

[0019] Along the portion 12b of the sleeve 12 there is a dosing device comprising a tap or valve 16 for adjusting and stopping the sand feed flow F.

[0020] The numeral 17 denotes a pneumatic injector, positioned at the elbow 15 and connected, by a duct 18, to the compressor 9.

[0021] The injector 17 comprises a housing which consists of a cylindrical container 19 extending from the elbow 15 coaxially with the axis B, thus forming with the portion 12a and the mouth of the portion 12b of the sleeve 12 a Y-shaped structure labelled 20.

[0022] In the alternative embodiment illustrated in Figure 3, the cylindrical container 19, the portion 12a and the mouth of the portion 12b, forming the Y-shaped structure 20, are made in a single block 21 laterally formed by two walls 22 and 23 which are parallel with each other and with the plane in which the axes A and B lie.

[0023] With reference in particular to the exploded view in Figure 4, the com-pressed air injector 17 comprises an injector tube 24, fixed inside the housing 19 with a centring nipple 25 and a threaded locking flange 26 interposed between them, and connected to the duct 8 by a non-return valve 27.

[0024] The outfeed end of the injector tube 24 is substantially positioned at the zone where the axes A and B intersect. In other embodiments, not illustrated, the end of the injector tube 24 is positioned beyond the zone where the axes A and B intersect, towards the tap 16, but obviously without reaching it.

[0025] At the wall 22, which is the front wall for observers of Figure 3, there is a circular through opening 28 for inspection and maintenance. The opening is closed by a cover 29.

[0026] From the above description it is evident how in accordance with this invention the pneumatic injector 17 positioned between the tank 2 outfeed opening 6 and the tap 16 performs the function of ensuring a regular flow of sand and even facilitating the passage towards the hose 10 of any foreign bodies which are of incorrect size (for example, stones and clumps of sand caused by humidity).

[0027] If any feed blockages occur, or even for the sole purpose of checking, once the cover 29 has been removed from the wall 22, the opening 28 allows inspection both of the vertical portion 12a at the tank 2 outfeed, and of the mouth of the angled portion 12b upstream of the tap 16 and any necessary action to restore machine normal operating conditions.

[0028] The invention described above is susceptible of industrial application and may be modified and adapted in several ways without thereby de-parting from the scope of the inventive concept. Moreover, all the de-tails of the invention may be substituted by technically equivalent elements.

Claims

1. A sandblasting machine comprising a tank (2) for containing a mass of sand, equipped with an outfeed opening (6), a substantially T-shaped connecting element (7), comprising a tank outfeed (6) tubular sleeve (12) and a tubular sleeve (13) transversal to the sleeve (12) and connected at a first end by a duct (8) to a source of compressed air (9) and at the second end, by a hose (10), to a nozzle (11) for dispensing a flow (F) of sand, there being a sand flow (F) dosing device (16) along the sleeve (12), characterised in that the connecting element (7) comprises a pneumatic injector (17) at the sleeve (12).

2. The sandblasting machine according to claim 1, characterised in that the pneumatic injector (17) is positioned, at the sleeve (12), upstream of the dosing device (16).

3. The sandblasting machine according to claim 1 or 2, characterised in that the tank (2) outfeed sleeve (12) comprises a first portion (12a) having an axis (A) and a second portion (12b) having an axis (B) which is set at a predetermined angle relative to the axis (A), thus forming an elbow (15) with the first portion (12a), the injector (17) being provided at the elbow (15).

4. The sandblasting machine according to claim 3, characterised in that the axis (A) is substantially vertical and the angle is substantially 45°.

5. The sandblasting machine according to claim 3 or 4, characterised in that the injector (17) comprises a housing which consists of a cylindrical container (19) extending from the elbow (15) coaxially with the axis (B), thus forming a Y-shaped structure (20) with the portion (12a) and the mouth of the portion (12b) of the sleeve (12).

6. The sandblasting machine according to claim 5, characterised in that the cylindrical container (19), the portion (12a) and the mouth of the portion (12b), forming the Y-shaped structure (20), are made in a single block (21) laterally formed by two walls (22) and (23) which are parallel with each other and with the plane in which the axes (A) and (B) lie.

Drawing