WO1993016844A1

WO1993016844A1 - A sand collecting and regulating device for sandblasting machines

Info

Publication number: WO1993016844A1
Application number: PCT/IT1992/000017
Authority: WO
Inventors: Giorgio Fontana
Original assignee: Sabbiatura E Carrozzeria Fontana S.N.C.
Priority date: 1992-02-19
Filing date: 1992-02-19
Publication date: 1993-09-02

Abstract

The invention relates to the field or sandblasting machines. More precisely, the invention concerns a device able to collect the sand from a recipient (1) and to regulate the quantity of sand in the final mixture of sand and compressed air, using pressure difference between a sand aspiration conduit (3), positioned at one end in the recipient (1), and another conduit (2) in which compressed air circulates. The device comprises a deviating valve (4) to differentiate the pressure present in the said compressed air conduit (2) with respect to the pressure inside the recipient (1). The device comprises means for the opening and closing of the aspiration conduit (3) of the sand.

Description

A sand Collecting and Regulating Device for sandblasting Machines.

Description.

The invention relates to a sand collection and regulating device for sandblasting machines.

sandblasting is a finishing or cleaning operation consisting in the blasting, at high velocities on to the surfaces of the pieces to be treated, of a jet of abrasive particles suspended in compressed air or other gas.

Using this process it is possible to remove rust, oxide waste, paints, incrustations, to eliminate shavings and tool marks, and to give a silky finish to the surface of the treated objects.

According to the type of application abrasives are used which are of different types and grains, like for example sand, pumice, or even spherical metallic particles.

Prior art sandblasters comprise a container for the sand or other abrasive material, equipped with an inlet conduit for the air and inferiorly open at a valve for the regulation of the quantity of sand, which falls by force of gravity from the bottom of the container towards a conduit in which compressed air circulates. The sand which falls from the container mixes with the compressed air, forming an abrasive mixture which thereafter exits from a gun held by an operator.

In such sandblasting machines, the sand moves by force of gravity towards the inferior opening of the container, and from here, by means of a valve which substantially regulates the said opening, falls into the underlying conduit and is thence drawn away by the air, but often, because of condensation or sand impurity phenomenons, the sand tends to stick to the edges of the opening, thus progressively reducing its diameter -up until it is completely obstructed.

This phenomenon brings about a progressive drop in the percentage of sand used by the operator, up until the said sand flow is completely interrupted, with a consequent halting of activity while the opening is cleaned in order to re¬ establish correct functioning of the sandblasting machine.

The aim of the present ivention is to eliminate the above-described drawbacks and in particular to obtain a constant mix between the air and the sand, according to the desired parameters, thus avoiding the problems due to air condensation or sand impurity.

The said aims are fully attained by the sand collection and regulating device for sandblasting machines, object of the present invention, of the type comprising a recipient for the sand or other abrasive material and a conduit in which compressed air circulates and in which the formation of the mixture composed of air and sand is made, characterised in that it comprises: - an aspiration conduit for the sand or abrasive material contained in the recipient, positioned at one end in the said recipient and inserted at its other end in the compressed air conduit; - means for closing and opening the said sand aspiration conduit;

E - means for varying the internal pressure of the recipient and the pressure in the compressed air conduit, in such a way as consequently to regulate the quantity of air aspirated.

These and other characteristics will better emerge from the description that follows, of some preferred embodiments of the invention, illustrated purely in the form of non-limiting examples in the drawings, in which:

- Figure 1 shows, in full view, the device mounted on a sandblasting machine;

- Figure 2 shows a particular of the device;

- Figure 3 shows, according to a possible embodiment variant, . the connection between the compressed air conduit and the sand aspiration conduit;

Figure 4 shows the device applied to a sandblasting machine, according to a further embodiment variation.

With reference to the figures, 1 denotes a recipient of substantially cylindrical shape, with an inferior section that is truncoconical, the whole constituting the body of a sandblasting machine .

The recipient 1 is superiorly equipped with a funnel 14 through which the recipient 1 is filled with sand or other abrasive material, and is further equipped, on its lateral . cylindrical surface, with an inspection porthole 13 for maintenance and cleaning operations.

2 denotes a conduit into which, by means of a compressor which is not illustrated, compressed air is introduced, which flows in part into the recipient 1 and in part continues along the said conduit 2.

A two-way connection 5 is mounted on the conduit 2, into which the conduit 2 itself and a sand- aspirating conduit 3 flow together, said sand- aspirating conduit 3 being partially inserted internally to the said recipient 1.

Downstream of the connection 5 a mixture is thus formed of compressed air, coming from the conduit 2 and sand coming from the aspiration conduit 3. 6 denotes a manual lever which causes the vertical translation of a rod 8 located internally to the recipient 1, which rod's 8 terminal part runs internally to a hole 10 bored into a support 11 which support 11 is solid to the aspiration conduit 3.

In this way one end 9 of the rod 8 may be inserted or not into the inlet of the aspiration conduit 3, obstructing its opening, with the effect of closing it. Thus, the rod 8 with the lever 6, the hole 10 and the support 11 constitute means for closing and opening the sand aspiration conduit 3.

12. denotes the support feet of the recipient 1.

A deviating or diversifying valve 4 is located on the compressed air conduit 2, which valve 4 regulates the quantity of compressed- air which is free to continue along the said conduit 2 as well as the quantity of air that enters the recipient 1.

The valve 4 is a means to diversify the internal pressure of the recipient and the pressure present in the compressed air conduit 2, and is manually activated by means of a lever 15.

The sand present in the recipient 1 is collected by means of the aspiration conduit 3 by depression, which is created when air is introduced at high pressure into the conduit 3.

The deviating valve 4 is a means to regulate the pressure difference between the conduit 2 and the recipient 1 in such a way as consequently to regulate the percentage of sand that is aspired and mixed with the compressed air. When the valve

4 is completely open the internal pressure of the recipient 1 is equal to that of the conduit 2, while the progressive closing of the said valve 4 causes a lowering of the air pressure in the conduit 2 with a consequent higher flow of sand in the aspiration conduit 3.

According to a possible embodiment variation, illustrated in figure 3, the conduit 2 can branch off, upstream of the connection with the aspiration conduit 3, into two branches 2a and 2b which rejoin at the two lateral intakes of a

E three-way connection 7, while at the central intake of the said connection 7 the aspiration conduit 3 is inserted in such a way that the sand is introduced into the conduit 2 in a substantially central position, guided laterally by the two air jets coming from the branches 2a and 2b.

In this way possible progressive erosions of the connection due to non-central entrance ^"of the sand are avoided.

According to a further embodiment variation (not illustrated) , the rod 8 can be moved, instead of by the manual lever 6, by a button-control, of the electropneumatic type, positioned on the handle of the operator's gun. A similar command, on the operator's gun, could be envisaged for the deviating valve 4.

According to a further embodiment, illustrated in figure 4, the aspiration conduit 3 can enter the recipient 1 through a sleeve 16 applied inferiorly to the said recipient 1 (for example, the said sleeve 16 could be screwed to the recipient) . In this way the necessary cleaning operations are simplified, since the sleeve 16 and thus the aspiration conduit 3 are easily dismountable, without having to open the porthole 13 to reach them. A further advantage is that the use of the sleeve 16 obviates the need to make a lateral hole in the recipient 1 for the introduction of the aspiration conduit 3.

Claims

A device for the collection and regulation of sand in a sandblasting machine, comprising a recipient (1) for the sand or other abrasive material, and a conduit (2) in which compressed air circulates and in which the mixture of air and sand is composed, characterised in that it comprises:

- an aspiration conduit (3) for the sand or other abrasive material contained in the recipient (1), positioned at one end in the said recipient (1) and inserted at its other end in the said compressed air conduit (2);

- means for closing and opening the said sand aspiration conduit (3) ; means for varying the internal pressure of the recipient and the pressure in the compressed air conduit (2), in such a way as consequently to regulate the quantity of air aspirated.

A device as in claim 1, wherein the said means for opening and closing the the said sand aspiration conduit (3) comprise: a rod (8) internal to the recipient (1), activated by means of a manually commanded lever (6) located externally to the recipient (1), one end (9) of the said rod (8) being slidable inside a guide hole (10) bored into a support (11) solid to a sleeve (2), in such a way as to close or open the conduit (2) intake.

3. A device as in claim 1, wherein the means to differentiate the internal pressure of the recipient (1) and the pressure present in the said compressed air conduit (2) comprise a deviating valve (4), located on the said conduit (2) which valve (4) limits by more or by less the air quantity which, passing into the said conduit (2) proceeds towards the connection with the said sand aspiration conduit (3), in such a way as consequently to vary the quantity of sand flowing into the conduit (2) through the aspiration conduit (3) .

4. A device as in claim 1, wherin the said conduit (2) is connected to the aspiration conduit (3) by means of a two-way connection (5) .

5. A device as in claim 1, wherein the said compressed air conduit (2) is connected to the aspiration conduit (3) by means of a three-way connection (7) with the said aspiration conduit (3) being inserted in a central tube and two branches (2a, 2b) of the compressed air conduit (2) being inserted in two tubes lateral to the said central tube.

6. A device as in claims 1 and 2, comprising a button, located on the handle of a gun used by an operator, to activate the gun (8) causing thus the flowing of the mixture, by means of an electropneu atic device.

7. A device as in claim 3,. comprising a command device for the deviating valve (4), positioned on the handle of a gun used by an operator.

8. A device as in claim 1, wherein the said aspiration conduit (3) is introduced into the said recipient (1) through a sleeve (16) applied inferiorly to the said recipient (1) and removable from the recipient (1).

TUTESHEET