EP1736289B1

EP1736289B1 - Apparatus for roughing surfaces, particularly in the machining of slabs of hard material

Info

Publication number: EP1736289B1
Application number: EP06012847A
Authority: EP
Inventors: Claudio Lovato
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-06-24
Filing date: 2006-06-22
Publication date: 2009-08-05
Anticipated expiration: 2026-06-22
Also published as: ES2331583T3; ATE438493T1; EP1736289A1; ITVI20050182A1; PT1736289E; PL1736289T3; DK1736289T3; DE602006008222D1

Abstract

This invention finds application in the machining of stones and the like, and relates to a method for forming surface markings particularly on slabs of hard material or the like, and to an apparatus for carrying out such method. The method comprises the steps of providing a plurality of tools (8) for forming surface markings that are aligned with predetermined center-to-center distances (i), translating the tools (8) parallel to the lying plane (À) to form a first succession of aligned and equally spaced markings (A), feeding the product (P) being machined relative to the tools (8) to form another succession (B) of aligned and equally spaced markings, different from the first succession (A), repeating the previous steps to cover the whole longitudinal extension of the surface (S) of the product (P). The successions of markings are either arranged in offset and non overlapping positions, or in at least partly overlapped positions according to a predetermined pattern.

Description

Field of the invention

This invention finds application in the machining of stones and the like, and particularly relates to an apparatus for forming a pattern of surface markings on flat or curved surfaces, particularly for surface machining of slabs of hard material or the like as for example known from EP 0422610 , showing an apparatus according to the preamble of claim 1.

Background of the invention

As is known, machining processes such as bush hammering, grooving, chiseling or others, on the surface of products of relatively hard material, such as marble, concrete or stone in general, generally having a plate-like shape, are carried out to add a particular aesthetic or functional effect to the product, which could not be obtained by other processes. These processes may add several degrees of roughness to the product surface, thereby possibly forming a particular pattern or texture thereon.
In prior art solutions, for instance, bush hammering is usually performed using a particular piston-operated tool, known as bush hammer, which may be formed of several different steel alloys. The tool is composed of a shank connected to a particular striking member which has a predetermined number of point- or wedge-shaped elements on its striking face. The points are generally arranged evenly on the tool face and they may be provided in various numbers depending on their size and on the tool size. The aesthetic effect is thus obtained by repeatedly striking the surface of the product with the bush hammer.
Bush hammering as well as slab displacement may be carried out either manually or automatically by means of special bush hammering machines.
An apparent drawback of the manual solution is the difficulty and slowness of the machining process. Furthermore, the tool striking pressure imparted by the operator is not always adequate to achieve the desired effect.
Automatic machining is conversely carried out in particular lines on which the slab is fed by means of rollers or bands and struck with one or more usually air-operated hammers, which strike against it at high pressure. The hammers are mounted to an arm that can be stationary or displaced transversely to the feed direction of the product being machined.
An apparent drawback of these solutions is that the machining tools strike the product on the line in repetitive patterns of one type. Therefore, although the machining process is faster than in manual solutions, it is still rather slow, as the tool is likely to operate on one point several times. Furthermore, this operation actually prevents the formation of particular patterns on the machined surface, which affects the aesthetic quality of the final product.
In order to obviate one or more of these drawbacks, a number of controlled machining solutions have been proposed.
JP10151620 discloses a bush hammering device for use with hard materials, particularly marbles, which comprises a support arm driven by a control apparatus, and with a single tool fitted thereon. While this solution partly overcomes the problem associated to the lack of control, it still has the apparent drawback that machining is carried out by a single tool. As a result, the process is still too slow and provides a non optimized yield.
EP0422610 discloses a device having a burner with a plurality of flaming nozzles or having a plurality of bush-hammering tools for surface treating of slabs, in which device the tools are moved in such a manner to realize successive marking arrangements over the flat surface either in offset, seamless positions or in overlapping positions.
However, this solution has the apparent drawback that markings realized by the burner are substantially continuous along a direction transverse to the feeding direction of the slab. Therefore, the resulting patterns are repetitive and the aesthetic quality of the final product is still affected. Moreover, flaming treatment doesn't allow a simple and accurate control of marking shape.
Another bush hammering device is known from DE 19953239 , which disclose a device having a plurality of hammering tools arranged to realize marking having uncontrolled patterns over the surface to be treated.

Summary of the Invention

The object of this invention is to overcome the above drawbacks, by providing a method for forming a predetermined pattern of markings on flat or curved surfaces, particularly in surface machining of slabs of hard material or the like, that is highly efficient and cost-effective.
A particular object is to provide a method that allows to form evenly arranged markings over the surface of the product being machined.
A further object of the invention is to provide a method that optimizes individual product machining times, thereby speeding up the overall process.
Another object is to provide a method that allows machining to be carried out in a controlled manner.
Yet another object is to provide a method that allows to obtain an aesthetically pleasing finished product.
Another important object is to provide an apparatus for carrying out such method.
These and other objects, to be further detailed hereafter, are achieved thanks to an apparatus for forming evenly arranged markings on a substantially flat or curved surface of a product, comprising a support structure for the products being machined, with an in-feed portion and an out-feed portion, means for feeding the products to be machined along a lying plane in a longitudinal direction and with a predetermined feed pitch, a plurality of tools for machining the products, each of said tools defining one machining axis intersecting said flat surface, control means for said plurality of machining tools.
Tools have predetermined center-to-center distances therebetween along said longitudinal direction, which center-to-center distances being related to said feed pitch, directly proportional to the magnitude of said feed pitch and inversely proportional to the number of each tool of said plurality, said control means comprising means for translating said plurality of tools in a transverse direction essentially perpendicular to said longitudinal direction in such a way to prevent any repetition of strokes on a same point of the product (P).
According to the invention, said translating means comprise at least one carrier block on which is mounted said plurality of tools, said at least one carrier block operating in a direction essentially parallel to said transverse direction with no movement along said longitudinal direction, said translating means further comprising a plurality of supporting slides for each of said tools to be fitted on said at least one carrier block, said at least one carrier block having at least one guide which is slideably engageable by said supporting slides to adjust said center-to-center distances and provide different values thereof suitable for proper machining without repetition of strokes on a same point of the product.
Thanks to this particular configuration, the apparatus of the invention allows to form markings in a predetermined pattern over the surface of the product being machined.
Advantageously, the center-to-centre distances may have values substantially, but not necessarily, constant for all tools.
Also, the values of center-to-center distance may be directly proportional to the maximum diameter of each tool and may be dimensioned according to the following algorithm: $i = int [D / p] * p + p / n + kp$

with an experimental coefficient k of a predetermined value, preferably of 0 to 50.
Thanks to this configuration, the apparatus of the invention allows machining time optimization, thereby speeding up the overall process. Furthermore, the tools may be totally controlled in a simple and effective manner, thereby affording highly accurate and even machining.
This particular configuration provides a particularly pleasing aesthetic effect.

Brief description of the drawings

Further features and advantages of the invention will be more apparent from the detailed description of a preferred, non-exclusive embodiment of a method and related apparatus according to the invention, which are described as a non-limiting example with the help of the annexed drawings, in which:

FIG. 1 is a side view of an apparatus according to the invention;
FIG. 2 is a top view of the apparatus of FIG. 1; FIG. 3 is a perspective view of a first detail of the apparatus of FIG. 1;
FIG. 4 is a top view of the detail of FIG. 3;
FIG. 5 is a bottom view of the detail of FIG. 3;
FIG. 6 is a perspective view of a further detail of the apparatus of FIG. 1;
FIG. 7 is a view of a pattern of impression of evenly arranged markings according to the invention;
FIG. 8 shows a flowchart of a method for forming the evenly arranged markings according to the invention.

Detailed description of a preferred embodiment

Referring to the above figures, the apparatus of the invention, generally designated by numeral 1, allows to form evenly arranged markings over a substantially flat surface of a product P, and particularly to bush-hammer a slab of hard material, such as marble or the like. The surface S to be machined extends over a lying plane π which defines a longitudinal direction X and a transverse direction Y.
As shown in FIG. 1, the apparatus 1 is composed of a substantially flat support structure 2 having an in-feed section 3 for the product P and a longitudinally opposite out-feed section 4. Means 5 are further provided for feeding the product P being machined, and convey it from the in-feed section 3 to the out-feed section 4. along the essentially horizontal lying plane p, in the longitudinal direction X. The means 5 preferably include a movable surface 6 between the sections 3 and 4, which is mounted, for instance, on a succession of idle rolls, driven by a common electrical motor, both not shown for their being widely used. The movable surface 6 is of common use, and made of a resilient material, having the property of withstanding machining stresses provided by the operation.
The means 5 allow the product P to be displaced over such lying plane p with a predetermined feed pitch p for each machining operation. A plurality of tools 8 specially designed for such machining operate over the movable surface 6, and are driven by suitable control means 9. Such tools 8 are suitably connected to suitable translating means 10 to be displaced in the transverse direction Y, essentially perpendicular to the longitudinal feed direction X, with movements s of predetermined wideness in such direction Y. The feed pitch p and the transverse movement s may nevertheless vary from a machining operation to another and may be preset before each operation.
Finally, each tool 8 operates along a machining axis W incident on the lying plane p, which is preferably, according to a preferred, non limiting embodiment of the invention, perpendicular to the work surface. According to the peculiar feature of the invention, the tools 8 are mounted with predetermined center-to-center distances i, which are related to the predetermined feed pitch p for the current machining process. This prevents multiple random striking on the same point during machining of the product P on the line, optimizing the overall surface machining process.
Preferably, the tools 8 are remotely controlled through a special logical unit 11, such as a processor controlled by specially designed software.
As shown in FIGS. 3-5, the translating means 10 include a carrier block 12 operating over the movable surface 6, with the tools 8 fitted thereon. The annexed figures show a block 12 with five similar tools 8 fitted thereon. This does not exclude the provision of a larger or smaller number n of tools 8. The block 12 is connected to the supporting structure 2 by means of a portal 13, which allows translation thereof in a direction Y₁ essentially parallel to the transverse direction Y of the lying plane p of the slab. Fitting of each tool 8 to the tool carrier block 12 is carried out by means of a plurality of supporting slides 14 which are slideably engageable on a pair of guides 15, 15' formed on the block 12. This allows displacement of each tool 8 to adjust the respective values of center-to-center distances i. By this arrangement, different values of center-to-center distances i may also provided, although being substantially equal for proper machining.
FIG. 6 shows one tool 8, consisting of a support member 16, extending in the work direction W, and an underlying striking member 17. This has a bottom surface 18 designed to interface with the product P being machined to operate thereon, and having a dimension D parallel to the longitudinal feed direction X of the product P along the support structure 2. On the bottom face 18, each tool 8 has a plurality of specially shaped e.g. blade-shaped, elements 19, evenly arranged on such face 18. These elements 19 are the real striking member operating on the product P being machined and have a predetermined radius of curvature in their end portion 20, which depends on the particular effect to be obtained in the specific machining process. Similarly, they may be also provided in various numbers. Each tool 8 is made of steel or other similar alloys and may be formed in casting molds. The material of each tool 8 shall have such hardness properties as to be able to form a marking on the surface S of the product P, by surface deformation of the material being machined.
Conveniently, the control means include a plurality of actuators 21, each associated to one respective tool 8, for transmitting thereto the requested operating motion along the work direction W to perform the striking operation on the product P. The actuators 21 are preferably of the pneumatic type and may interact with their respective tools 8 by means of a suitable spring mechanism 22.
FIG. 7 shows a particular exemplary pattern that can be obtained with the apparatus and the method as claimed.
A method for forming evenly arranged markings on the flat surface S of the product P comprises the following sequence of steps.
In a first step a), a plurality of tools 8 is provided, which are designed to form one or more aligned markings on the surface S, with predetermined center-to-center distances i, by reciprocating movements in a work direction W incident on the lying plane p.
In the next step b), the tools 8 are translated parallel to the lying plane p with movements s of predetermined wideness along the transverse direction Y to form a first succession A of aligned markings, equally spaced and arranged all along the transverse extension of the product P.
The machining steps are such that, as the carrier block 12 first passes over the surface S to be machined, a first succession of markings, aligned in the transverse direction Y, is formed, as shown in FIG. 7a. Markings are formed by deformation of the surface S of the product P being machined.
Each partial succession of markings formed by each tool 8 is spaced from the next one, at the respective median points, by a value corresponding to the preset center-to-center distance i. This value is directly proportional to the feed pitch p and inversely proportional to the number n of tools 8 fitted on the carrier block 12, and cannot be smaller than the dimension D of the bottom face 18 of each striking member 17. Particularly, the value of center-to-center distance i is dimensioned according to the algorithm: $i = int [D / p] * p + p / n + k p$

where k is an experimental coefficient of a predetermined value, preferably of 0 to 50. If the value of center-to-center distance i obtained from the above algorithm satisfies the following condition: $i - p > D$

then the actually set value of center-to-center distance i for each tool 8 will be $i^{'} = i - p$
In the next step c), the product P being machined is fed relative to the plurality of tools 8 and parallel to the lying plane p, with a feed pitch p of predetermined wideness in the longitudinal direction X. Such relative feed may occur either by moving the movable surface 6 or by feeding the carrier block 12 parallel to the lying plane p. Thus, the surface to be machined S will be ready for another succession of aligned and equally spaced markings B, different from the former A. According to the invention, as shown in FIG. 7b, this second succession of markings B is arranged on the working surface S in offset and non overlapping positions, or in at least partly overlapped positions according to a predetermined pattern. Finally, in step d), the previous steps are repeated in such a manner as to cover the whole longitudinal extension of the surface S of the product P.
The above disclosure clearly shows that the method and apparatus of the invention fulfill the intended objects and particularly optimize individual product machining times, thereby speeding up the whole process.
The combination of the means that form the apparatus and the sequence of steps that form the method allows to form successive markings on the product being machined, which are arranged on the surface either in offset, non-overlapping positions or in at least partly overlapped positions according to a predetermined pattern, thereby preventing any undesired repeated strokes on one or more points of the product surface.
The method and apparatus of this invention are susceptible to a number of changes or variants, within the inventive concept disclosed in the appended claims. All the details thereof may be replaced by other technically equivalent parts, and the materials may vary depending on different needs, without departure from the scope of the invention.
While the method and apparatus has been described with particular reference to the accompanying figures, the numerals referred to in the disclosure and claims are only used for the sake of a better intelligibility of the invention and shall not be intended to limit the claimed scope in any manner.

Claims

An apparatus for forming evenly arranged markings on a substantially flat or curved surface (S) of a product (P), comprising:
- a support structure (2) for the products (P) being machined, with an in-feed portion (3) and an out-feed portion (4);

- means (5) for feeding the products (P) to be machined along a lying plane (π) in a longitudinal direction (X) and with a predetermined feed pitch (p);

- a plurality of tools (8) for machining the products (P), each of said tools(8) defining one machining axis (W) intersecting said flat surface (S);

- control means (9) for said plurality of machining tools (8),
wherein said tools (8) have predetermined center-to-center distances (i) therebetween along said longitudinal direction (X), which are related to said feed pitch (p), said center-to-center distances (i) being directly proportional to the magnitude of said feed pitch (p) and inversely proportional to the number (n) of each tool (8) of said plurality, said control means (9) comprising means (10) for translating said plurality of tools (8) in a transverse direction (Y₁) essentially perpendicular to said longitudinal direction (X) in such a way to prevent any repetition of strokes on a same point of the product (P);
characterized in that said translating means (10) comprise at least one carrier block (12) on which is mounted said plurality of tools (8), said at least one carrier block (12) operating in a direction essentially parallel to said transverse direction (Y₁) with no movement along said longitudinal direction (X), said translating means further comprising a plurality of supporting slides (14) for each of said tools (8) to be fitted on said at least one carrier block (12), said at least one carrier block (12) having at least one guide (15) which is slideably engageable by said supporting slides (14) to adjust said center-to-center distances (i) and provide different values thereof suitable for proper machining without repetition of strokes on a same point of the product (P).
An apparatus as claimed in claim 1, characterized in that said feeding means (5) comprise a movable surface (6) for displacing the product (P) along said longitudinal direction (X).
An apparatus as claimed in claim 1, characterized in that said translating means (10) are designed for translating said plurality of tools (8) in said transverse direction (Y₁) with movements (s) of predetermined wideness.
An apparatus as claimed in claim 1, characterized in that each tool (8) of said plurality comprises a support member (16) extending in said work direction (W) and a striking member (17) with a bottom face (18) having a dimension (D) essentially parallel to said longitudinal feed direction (X) of the product (P).
An apparatus as claimed in the preceding claim, characterized in that said value of center-to-center distance (i) is not smaller than said dimension (D) of said bottom face (18).
An apparatus as claimed in the preceding claim, characterized in that said value of center-to-center distance (i) is directly proportional to the longitudinal dimension (D) of each tool (8) of said plurality.
An apparatus as claimed in the preceding claim, characterized in that said value of center-to-center distance (i) is dimensioned according to the following algorithm: $i = int [D / p] * p + p / n + k * p$

where k is an experimental coefficient of a predetermined value, preferably of 0 to 50.
An apparatus as claimed in claim 1, characterized in that said control means (9) comprise a logical unit (13) for setting and adjusting said feed pitch (p) and said transverse movement (s).
An apparatus as claimed in claim 1, characterized in that said control means (9) comprise a plurality of actuators (21) associated to each of said tools (8) for transmitting thereto an operating motion along said work direction (W).
An apparatus as claimed in the preceding claim, characterized in that said actuators (21) are of the pneumatic type, said operating motion being essentially perpendicular to said movable surface (6).
An apparatus as claimed in claim 4, characterized in that said striking members (17) have at least one specially shaped element (19) on their respective bottom faces (18), which is adapted to interact by surface deformation with the product (P) lying on said movable surface (6).