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EP-4281248-B1 - A DRUM AND AN APPARATUS FOR THE SURFACE PROCESSING OF ROCK OR MOSAIC PIECES THROUGH ROTATION

EP4281248B1EP 4281248 B1EP4281248 B1EP 4281248B1EP-4281248-B1

Inventors

  • VICENTE FRAZÃO, Eliseu Manuel

Dates

Publication Date
20260506
Application Date
20220120

Claims (15)

  1. A drum (1) for the surface processing of rock or mosaic pieces through rotation comprising: - one or more longitudinal inner surfaces (2) forming a tube and aligned with a rotation axis of the drum, and - a plurality of plates (3), the plates: being adjacently provided on and connected to the one or more longitudinal inner surfaces (2), and having a surface with a hardness of at least 300 Brinell, each plate being so provided that such surface faces the interior of the drum, characterised in that each two adjacently provided plates (3) are apart by a predefined distance (d) in respective sides of the plates (3) which are substantially aligned with the rotation axis of the drum (1), the predefined distance (d) being substantially constant between two plates (3) and wherein the separation defines a not covered area of the inner surfaces (2), the separation being such that it provides a further element of tumbling and abrasion of the rock or mosaic pieces to be processed, and wherein each plate (3) is a bent plate, the bent being provided in a direction of the plate (3) which is substantially aligned with the rotation axis of the drum (1), and substantially centred and, wherein it has a cylindrical form, thereby comprising a single tubular longitudinal inner surface (2) with a circular cross-section.
  2. A drum according to the preceding claim wherein each plate has a substantially rectangular shape.
  3. A drum according to any of the preceding claims wherein each of the referred plates extends along a whole longitudinal section of the longitudinal inner surface.
  4. A drum according to any of the preceding claims wherein the referred surface with a hardness of at least 300 Brinell is a roughened surface.
  5. A drum according to any of the preceding claims wherein each plate comprises a first and a second sheet, the first sheet having the referred surface with a hardness of at least 300 Brinell and the second sheet being of a material suitable to weld the first sheet to the one or more longitudinal inner surfaces of the drum, optionally the first sheet being metallic, having a hardness of at least 300 Brinell.
  6. A drum according to any of the preceding claims wherein the surface of each plate has a hardness of at least 400 Brinell, more preferably at least 500 Brinell, even more preferably at least 600 Brinell, 700 Brinell or 800 Brinell, optionally the second sheet comprising steel, optionally the second sheet being made of an S235, S275 or S355 steel according to EN 10025, preferably S235.
  7. A drum according to any of the preceding claims wherein the predefined distance is the same for every pair of adjacently provided plates.
  8. A drum according to any of the preceding claims wherein the predefined distance is of 5-50 mm, preferably 20-40 mm, more preferably of 25 mm.
  9. A drum according to any of the preceding claims wherein each longitudinal inner surface has a length of 1,000-3,000 mm, preferably 2,000-4,000 mm, more preferably of 2,000, 2,500, 3,000 or 4,000 mm.
  10. A drum according to any of the preceding claims wherein the plates are rectangular, having a length equal to the length of the longitudinal inner surface and a width of 225-325 mm, preferably 250-300 mm, more preferably 275 mm.
  11. An apparatus for the surface processing of rock or mosaic pieces through rotation characterised in that it comprises the drum of any of the preceding claims and means for rotating the drum.
  12. An apparatus according to the previous claim wherein it further comprises control means configured to control the means for rotating the drum and thereby control the rotation of the drum, the control means being configured to provide the rotation of the drum with the adaptation of at least one operational parameter of the apparatus based on at least one physical property of the rock or mosaic pieces to be processed,, optionally the physical parameter comprising an average diameter of rocks prior to processing, a desired average diameter of rocks after processing, the form of rocks prior to processing, the desired form of rocks after processing and/or the average hardness of rocks to be processed.
  13. An apparatus according to claim 12 wherein the operational parameter comprises the rotation speed of the drum and/or the time of continuous rotation, optionally the apparatus being configured to provide a rotation speed of at least 5 rotations per minute (rpm), preferably from 10-20 rpm, more preferably of 10 or 15 rpm optionally the apparatus being configured to, in a continuous rotation of a plurality of rock or mosaic pieces, have two or more rotation speeds.
  14. An apparatus according to the previous claim, wherein it is configured to, in a continuous rotation of a plurality of rock or mosaic pieces, change the rotation speed from a first rotation speed to a second rotation speed, thereby having two or more rotation speeds.
  15. A method for processing the surface of a plurality of rock or mosaic pieces characterised in that it comprises the steps of: - providing a plurality of pieces of rock or mosaic inside the drum of the apparatus of any of the claims 11-14, - rotating the apparatus for an amount of time, optionally the rock pieces comprising limestone, slate, marble, granite or kyanite pieces.

Description

FIELD OF THE INVENTION The present invention is enclosed in the area of rock or mosaic processing, in particular the processing of rocks such as limestone, slate, marble, granite or kyanite, in pieces, to provide a smoothening or ultimately a change of shape of such pieces of rock or mosaic through the tumbling of such pieces of rock or mosaic inside a rotating drum. From such procedure may result rocks with a pebble-like look. PRIOR ART EP 1 838 446 A1 forms the basis for the preamble of claim 1. Solutions exist in the art where the inside of a rock or mosaic pieces processing drum is entirely covered with pieces of a type of rock which is expected to be harder than the rock or mosaic to be processed. When rocks or mosaic to be processed are placed inside the drum, the machine rotates the drum and the tumbling of the pieces under processing on the referred covered walls of the drum provides for the smoothening of corners, and results, after an amount of time, in entirely smooth pieces of rock/mosaic. These pieces may be more or less irregular, depending on their initial form and desired final form, as well as on the time which they have been tumbled in the drum and speed of rotation of the drum. Within the context of the present invention, terms rock and stone are used interchangeably. Additionally, an abrasive substance may be added to the inside of the drum, to provide an additional abrasion and thereby smoothening of the rocks or mosaic under processing. Such is the case of patent application with publication number US5586925 A. Yet, such solutions have two main issues: consumption of time/energy and low durability. Drums and machines following such methodology are considerably time consuming, which also results in a considerable amount of energy, required to tumble an overall mass of rocks (in case of rock processing) which may reach 1 t typically during 6-10 h, to obtain a smooth pebble-like piece of rock. On the other hand, and even though the rocks covering the inside of the tumbler are harder than those being processed, still a high abrasion occurs on such covering rocks, in due course leading to the loss of all or at least parts of the abrasion surface. Such loss increases the need for maintenance, in order to again provide a surface covered with the harder rocks. The present solution innovatively overcomes such issues through a drum and apparatus comprising such drum which are simple and yet highly effective. SUMMARY OF THE INVENTION It is an object of the present invention a drum for the surface processing of rock or mosaic pieces through rotation as defined in claim 1. By comprising hard plates which are adjacently provided and yet apart by a predefined distance, the drum of the present invention provides that, upon rotation and thereby tumbling of rock or mosaic pieces provided inside the drum, a further abrasion is provided on the rock or mosaic pieces, not only by means of the plate having a hardness of at least 300 Brinell but also through the separation between plates, which creates a further element of tumbling and abrasion. Thus, the longitudinal inner surface of the drum does not need a full coverage as such not covered areas - formed by the separation between plates - provide for a higher efficiency. The hardness of the plates of the present invention (be it of 300 Brinell, 400 Brinell or higher) is a hardness as measured through EN ISO 6506-1:2005. Thus, independently of the relevant parameters of the pieces of rock - such as hardness, initial form, desired final form - the solution of the present invention results in a decrease in the time spent for a smoothening process of 70-90 %, for a same rotating speed. The predefined distance is advantageously the same for every pair of adjacently provided plates. It is also an object of the present invention an apparatus for the surface processing of rock or mosaic pieces through rotation which comprises the drum of the present invention, in any of its embodiments, and means for rotating the drum. Advantageously, the apparatus comprises control means configured to control the means for rotating the drum and thereby control the rotation of the drum, the control means being configured to provide the rotation of the drum with the adaptation of at least one operational parameter of the apparatus based on at least one physical property of the rock or mosaic pieces to be processed. Such solution allows to define programs for the processing of each type of rock (with a standard hardness), dependent of an initial form (e.g. round, elliptical, cubic, irregular) and desired final form (e.g. round, elliptical, cubic, irregular, depending of the initial form), thereby obtaining a rotation speed of the drum and/or the time of continuous rotation. It is yet an object of the present invention a method for processing the surface of a plurality of rock or mosaic pieces which comprises the steps of: providing a plurality of rock or mosaic pieces inside the dru