SHOT BLASTING MACHINE WITH A BELT CONVEYOR FOR THE TREATMENT OF METAL PIECES

Abstract

A shot-blasting machine for the treatment of metal pieces and the related shot-blasting system. In particular, a shot blasting machine provided with special support devices to improve the operation of its conveyor belt, so as to overcome technical drawbacks that are rather common in conventional shot blasting machines having a metallic conveyor belt.

Claims

1. A shot blasting machine having a metallic conveyor belt for the treatment of metal pieces comprising: a closed circuit conveyor belt for moving said metal pieces, said conveyor belt comprising a sequence of horizontal slats hinged onto two lateral chains; one or more centrifugal turbines having the function of projecting abrasive material at high speed against said metal pieces; at least two support devices positioned below said lateral chains, the at least two support device comprising a sequence of rollers which rotate resting on the links and the pins of said lateral chains during the continuous movement of said conveyor belt.

2. The shot blasting machine according to claim 1, wherein said conveyor belt 4 comprises a concave portion, inside which said metal pieces are hit by a stream of said abrasive material at high speed.

3. The shot blasting machine according to claim 1, wherein said support devices are positioned below said lateral chains of said conveyor belt at said concave portion.

4. The shot blasting machine according to claim 1, wherein said support devices comprise a bearing structure or frame and a sequence of rollers.

5. The shot blasting machine according to claim 4, wherein said frame comprises a support base from which perforated walls branch out, parallel to each other and perpendicular to said support base.

6. The shot blasting machine according to claim 1, wherein said rollers are inserted into holes provided in said perforated walls of said frame.

7. The shot blasting machine according to claim 1, wherein said support devices comprise a sequence of rollers in a number comprised between 8 and 30.

8. The shot blasting machine according to claim 7, wherein said number of rollers is comprised between 10 and 20.

9. The shot blasting machine according to claim 1, wherein said at least two support devices support the continuous movement of the two lateral chains of the conveyor belt.

10. A shot blasting machine having at least two support devices comprising a sequence of rollers inserted in a support frame, said support devices being positioned below a concave portion of a conveyor belt of said shot blasting machine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0037] The metal belt shot blasting machine for the treatment of metal pieces of the invention will now be described in detail with reference to the appended FIGS. 1-4, which are to be considered merely illustrative and not limiting the scope of the present invention.

[0038] FIG. 1 shows a sectional view of a shot blasting system comprising a metal belt shot blasting machine with the characteristics of the prior art.

[0039] FIG. 2 shows an enlargement of the sectional view of FIG. 1 at the concave portion of the closed-loop conveyor belt.

[0040] FIG. 3 shows a perspective view of a support device in accordance with the present invention.

[0041] FIG. 4 shows a cross-sectional view of a conveyor belt of a metal belt shot blasting machine comprising support devices in accordance with the present invention.

[0042] With reference to FIG. 1, a schematic illustration of a conventional shot blasting system 1 is shown, which comprises a metal belt shot blasting machine 2 for the treatment of metal pieces 3.

[0043] The belt shot blasting machine 2 comprises a closed-loop conveyor belt 4 for the movement of metal pieces 3 to be cleaned, this conveyor belt 4 being composed of a sequence of horizontal metal slats hinged onto two lateral chains 5.

[0044] The conveyor belt 4 of the shot blasting machine 2 is shaped in a closed loop so as to comprise a concave portion 6 within which metal pieces 3 are hit by a stream of abrasive material (shots) at high speed.

[0045] The lateral chains 5 are connected to a drive shaft 7 and this connection allows the continuous movement of the conveyor belt 4. A centrifugal turbine 8 is used to project the shots at high speed against the metal pieces 3 in the concave portion 6 of the conveyor belt 4. The turbine 8 is an integral part of the belt shot blasting machine 2.

[0046] The continuous advancement of the conveyor belt 4 has the effect of mixing the metal pieces 3 within its concave portion 6, so that the metal pieces 3 evenly present all their surfaces to the action of the abrasive streams launched by the centrifugal turbine 8.

[0047] In the shot blasting system 1 shown in FIG. 1 the metal pieces 3 are loaded manually by an operator 9. Alternatively, the metal pieces 3 can be loaded automatically onto the conveyor belt 4 using a hydraulic tipping bucket.

[0048] A gear motor 10 is used to appropriately adjust the speed of the conveyor belt 4 during the treatment of the metal pieces 3. The gear motor 10 also has the function of reversing the direction of travel of the conveyor belt 4, once the blasting treatment has been completed: in this way, the metal pieces 3 can be easily unloaded and recovered after the cleaning treatment in the shot blasting system 1.

[0049] FIG. 2 is a cross-sectional view showing an enlargement of the closed-loop conveyor belt 4 used in the shot blasting system 1 in FIG. 1 above.

[0050] The conveyor belt 4 consists of a continuous sequence of metal slats 11 hinged to the links 12 of two chains 5 located on either side of each metal slat 11. The lateral chains are set in motion by the drive shaft 7 shown in FIG. 1 and have the function of supporting the metal slats 11. The movement of the lateral chains 5 causes the metal slats 11 to advance along the closed loop of the conveyor belt 4.

[0051] The concave portion 6 of the conveyor belt 4 encloses the metal pieces 3 inside it for the time strictly necessary for the shot blasting treatment. The abrasive launched by the centrifugal turbine 8 hits equally both the metal pieces 3 to be treated and the metal slats 11 of the conveyor belt 4, which are subject to heavy wear over time as they are directly hit by the high-speed stream of shots.

[0052] The most critical components of the conveyor belt 4 are the two lateral chains 4, consisting of a continuous succession of links 12 and pins 13, which keep the metal slats 11 hinged. As already explained in the section on the state of the art, it is mainly the links 12 and pins 13 that wear out quickly, resulting in gradual thinning of the pins 13 and, at the same time, gradual widening of the openings of the links 12.

[0053] As a result, unwanted play is created over time between pins 13 and links 12, and the formation of this play is particularly pronounced at the concave part 6 of the conveyor belt 4 due to the joint action of the force of gravity of the metal pieces 3 and the centrifugal force of the shots hitting the links 12 and pins 13. Metal pieces 3 can get jammed at the gaps created between pins 13 and links 12. This jamming of metal pieces 3 can cause the conveyor belt 4 to stop moving and, in the worst case scenario, breakage of components inside the shot blasting machine 2.

[0054] The present invention solves the above technical problem by counteracting the formation of unwanted play between links 12 and pins 13 of the two lateral chains 5. The technical problem is solved by inserting into the shot blasting machine 2 at least two support devices having the characteristics of the present invention at the lateral chains 5 of the conveyor belt 4.

[0055] FIG. 3 shows a perspective view of a support device 14 in accordance with the present invention. The support device 14 comprises a support structure or frame 15 and a sequence of rollers 16.

[0056] The frame 15 has the function of supporting the sequence of rollers 16 and comprises a support base 17, from which perforated walls 18 branch out parallel to each other and perpendicular to the support base 17. Each wall 18 is provided with a sequence of holes 19 of a suitable size to accommodate the rollers 16.

[0057] The perforated walls 18 can vary in number, but are generally present in a number comprised between two and five. In particular, in the embodiment of the invention shown in FIG. 3, the frame 15 comprises three perforated walls 18 parallel to one other.

[0058] The rollers 16 are inserted into the holes 19 in the perforated walls 18 in such a way that they can rotate unrestrained within these holes 19. A variable number of rollers 16 can be inserted into the holes 19 and this number depends on the extension in length of the concave portion 6 of the conveyor belt 4 of the shot blasting machine 2. In general, the support devices 14 of the present invention comprise a sequence of rollers 16 in a number generally comprised between 8 and 30, preferably comprised between 10 and 20.

[0059] The material constituting the support device 14 shown in FIG. 3 is preferably steel with high wear resistance. It is therefore a device with a very simple structure and easy construction. Its use inside a metal belt shot blasting machine presents no drawbacks, as it can be easily inserted below the lateral chains 5 of the conveyor belt 4. Similarly, the support device 14 can be easily removed from the shot blasting machine when maintenance work on the conveyor belt 4 is required from time to time.

[0060] FIG. 4 shows a sectional view of a conveyor belt 4 of a metal belt shot blasting machine comprising the support device 14 shown in FIG. 3.

[0061] The support device 14 of the present invention is inserted at the concave portion 6 of the conveyor belt 4. In particular, the support device 14 is positioned below the lateral chains 5 of the conveyor belt 4.

[0062] The support device 14 is positioned so that the rollers 16 are in close contact with the links 12 and pins 13 of the lateral chains 5 of the conveyor belt 4. As a result, the continuous movement of links 12 and pins 13 is transferred to the sequence of rollers 16, so as to determine their rotation about their axes.

[0063] As there are two lateral chains 5 at the edges of the conveyor belt 4, at least two support devices 14 are required: each is inserted below each lateral chain 5 to support their movement at the concave portion 6 of the conveyor belt 4.

[0064] The rollers 16 are supported in their rotational movement by a frame 15 having the construction characteristics described with reference to FIG. 3: they can therefore rotate within the holes 19 in the perforated walls 18.

[0065] The presence of the support device 14 and rollers 16 in close contact with the links 12 and pins 13 inhibits a slackening of the lateral chains 5 and prevents the formation of unwanted and deleterious play between pins 13 and links 12. As a result, the risk of jamming of metal pieces in the concave portion 6 of the conveyor belt 4, a rather frequent risk in conventional shot blasting machines of the prior art, is prevented. The metal belt shot blasting machine can therefore run for a long time without incurring any stoppage of the movement of its conveyor belt 4.

[0066] The present invention is not limited to the particular embodiments previously described in relation to FIGS. 1-4, but numerous modifications can be made to it in detail, within the reach of the person skilled in the art, without thereby departing from the scope of the invention itself, as defined in the appended claims.