GB2027372A - Improvements in Vibrating Finishing Machines - Google Patents

Abstract

A finishing machine comprises a vibrating annular tank 10 around which the mass of articles to be finished and a finishing agent pass in a turbulent manner under the effect of vibrations applied to the tank. The tank comprises at least two portions 11 and 12 of different depths connected to each other by intermediate sectors 13 and 14 the base 17 or 18 of each of which is shaped to provide a transition between the bases 15, 16 of the said portions of different depths. A sieve 22 is disposed at a higher level than that of the base 16 of the shallowest portion 12 and is preceded by a movable shutter 20 which can be placed between the said base 16 and the sieve 22 so as to force the contents of the tank through the said sieve when required. <IMAGE>

Description

SPECIFICATION Improvements in Vibrating Finishing Machines The present invention relates to vibrating finishing machines and, in particular, to machines of this type which comprise an annular tank around which the mass of articles to be finished and a finishing agent pass in a turbulent manner under the effect of vibrations applied to the tank.

In the very early machines the base of the tank was horizontal and, when treatment was completed, the tank had to be emptied and its contents sifted so as to separate the treated articles from the finishing agent.

In order to permit easier separation, therefore, the base of the tank has been made in the form of a helical convolution, thus providing in the base a step beyond which can be placed a sieve with a width of mesh through which only the finishing agent can pass. When the articles have to pass through the tank several times, the sieve or a device leading to it is displaced. So as to achieve a sufficient height to ensure good separation a barrier is placed in front of the step so that the mass has to cross the barrier before reaching the sieve.

It has been ascertained that, given the same conditions, treatment times were shorter in tanks with a helical base fitted with this type of barrier than in tanks of the same type not provided with a barrier, or tanks with a horizontal base. This seems to be due to the fact that the barrier causes a disturbance in the movement of the mass and increases the friction between the articles and the finishing agent by means of the accelerating and braking actions occurring between them.

Unfortunately, the presence of a step and a barrier in the tank causes the articles and the finishing agent to fall each time they pass through, and this repeated falling can cause damage if the articles are fragile.

The aim of the present invention is to improve finishing machines, of the type described above, so as to benefit from the advantages of the barrier without the articles having to fall.

For this purpose, according to the invention, the tank comprises at least two portions of different depths, joined together by intermediate sectors the base of each of which is shaped to provide a transition between the bases of the said portions of different depths.

The bases of the intermediate sectors may have a straight profile inclined at an angle of, for example, approximately 450 to the horizontal, the bases of the portions of the tank themselves being disposed horizontally.

The separating sieve is preferably positioned beyond the end of the least deep portion of the tank and, in that case, at a level higher than the base of the said portion to ensure a sufficient separation height.

The following is a more detailed description of one embodiment of the invention, reference being made to the accompanying drawings in which: Figure 1 is a diagrammatic longitudinal section through a portion of a tank having a helical base and comprising a barrier and a step, Figure 2 is a diagrammatic plan view of an improved machine according to the invention, Figure 3 is a section on the line Ill-Ill of Figue 2, and Figure 4 is a diagrammatic view of the developed longitudinal section of the machine.

In Figure 1, a machine of known type comprises an annular vibrating tank 1 the base 2 of which describes a convolution of a vertical helix. A step 3 is formed at the end of the convolution and is preceded by a barrier 4 which is inclined, for example, at 450. The purpose of this barrier is to ensure a sufficient height h between the sieve 5, which serves to. separate the articles and the finishing agent, and the lower portion 6 of the base of the tank.

When the sieve 5 is displaced from the barrier 4, as shown in Figure 1, the mass 7 of articles being treated and finishing agent falls to the bottom of the tank after having crossed the barrier and, if the articles are fragile, they can be damaged. However, the presence of the carrier causes a disturbance in the movement of the mass 7 which is favourable for the effectiveness of the treatment.

The machine represented in Figures 2 and 4 comprises an annular tank 10 of constant width and of U-shaped cross-section. (Figure 3).

In the tank 10 four portions can be seen, that is: two portions 11 and 12 with constant but different depths, for example, the depth of portion 11 being of the order of one and a half times that of portion 12, and two intermediate portions 13 and 14 in the form of sectors the bases of which provide a progressive transition between the bases of portions 1 1 and 12.

If the tank is cut through a vertical cylinder equidistant from its lateral walls and the section is developed, then Figure 4 is obtained in which can be seen the base 15 of portion 1 the base 17 of sector 13 which rises at, for example, 450 towards the base 16 of portion 12, and the base 18 of sector 14 which descends, for example also at 450, towards the base 15 of portion 11.

The tank can be made in one piece or by assembling suitable components. The lengths of the portions 1 1 and 12 can be equal or different.

With regard to the lengths of the transition sectors 13 and 14, this will depend on the difference of the depths and the shape of the bases 17 and 18. The latter can have a straight or curved profile, for example they may be S-shaped.

In Figure 4, the mass 19 of the articles to be finished and the finishing agent moves from the left to the right in the tank under the effect of vibrations applied to the tank by an appropriate known mechanism which is not shown. This corresponds to a clockwise direction in Figure 2.

In the deep portion 1 1 of the tank the average depth of the mass settles to a constant value a, but the necessity of climbing the slope 17 to reach the shallower portion 12 has the effect of reducing the depth so that in the shallower portion 12 the mass has a depth b which is less than the depth a.

Above the descending base 18 of the intermediate sector 14 there is provided a movable shutter 20, which is pivoted on a radial axis 21 and arranged so that it can be either raised, as shown in solid line in Figure 4, to let the mass through, or lowered, as shown by dotted lines, so as to contact the upper end of base 16 and thus form an upwardly inclined barrier which forces the mass to rise onto a sieve 22 disposed beyond the shutter, at a height h above the base 15, and extending out of the tank 10 (Figure 2).

When the shutter 20 is raised, the mass 19 descends the slope 18 to return to the base 15 of the deep portion 11. The mass is thus released in such a way as to enable the depth a to be obtained again.

It can therefore be seen that the mass 19 is subjected periodically to progressive disturbances as it moves around the tank, which disturbances promote the action of the finishing agent on the articles and increase the effectiveness of the treatment. In particular when passing along the slopes 17 and 18 the particles being treated tend to roll and this is particularly useful in the case of articles which, because of their shape, would otherwise tend to adopt a constant position in the mass, this being liable to obstruct the action of the finishing agent by impeding the distribution of the latter on the surfaces to be treated.

In spite of this, the articles do not suffer any impact.

To extract the articles, the shutter 20 is lowered and the mass moves up the said shutter in order to reach the sieve 22. The articles are retained by the sieve while the finishing agent falls onto the base 1 5 of the deep portion of the tank.

Furthermore it should be noted that the manufacture of an improved tank according to the invention is more economical than that of a tank with its base in the form of a helical convolution.

Claims (8)

Claims

1. A finishing machine comprising a vibrating annular tank around which the mass of articles to be finished and a finishing agent pass in a turbulent manner under the effect of vibrations applied to the said tank, wherein the tank comprises at least two portions of different depths connected to each other by intermediate sectors the base of each of which is shaped to provide a transition between the bases of the said portions of different depths.

2. A finishing machine according to claim 1, wherein the bases of the intermediate sectors have a straight inclined profile.

3. A finishing machine according to claim 2, wherein each intermediate sector base is inclined at substantially 450 to the horizontal, the bases of said portions being substantially horizontal.

4. A finishing machine according to any one of claims 1 to 3, comprising a separating sieve disposed beyond the end of a portion with the least depth.

5. A finishing machine according to claim 4, wherein the sieve is disposed at a higher level than that of the base of the portion with the least depth and is preceded by a movable device which can be placed between the said base and the sieve so as to force the contents of the tank through the said sieve.

6. A finishing machine according to claim 5, wherein the movable device is a pivoted shutter in front of the sieve which can be either raised or lowered at the end of the base of the portion with the least depth.

7. A finishing machine according to any one of claims 1 to 6, wherein the tank comprises two portions of different depths and equal lengths.

8. A finishing machine substantially as hereinbefore described with reference to Figures 2 to 4 of the accompanying drawings.