DESCRIPTION

Technical field

This invention relates to a machine for mirror polishing jewellery, goldsmith’s, silversmith’s and costume jewellery products and the relative mirror polishing method.

Background art

According to the current state of the art, there are mirror polishing machines, described in Italian patent No. 1427267, which comprise robotic arms mounted on a load-bearing frame and movable about two or more axes.

In particular, a first robotic arm supports a tool holder head, mounted directly on its end, which is designed to impart to the mirror polishing tool a translational movement independent of the plurality of rotational movements of the robotic arm.

The mirror polishing tool is of the so-called“ fan” type and performs the processing on the outer surface of an object to be mirror polished. It is supported by the above-mentioned tool holder head and has one or more plates equipped with a mirror polishing tip and one or more plates equipped, on the other hand, with a tip made of electrically conductive material.

The object to be mirror polished is, on the other hand, retained by two counter-tips which engage two gripping holes specially defined along an axis of symmetry of the object.

The processing is performed by moving the tool holder head to a safety height from the surface to be processed and it therefore performs a very fast and precise secondary movement which allows an alternating micrometric linear sliding to be imparted to the tool, at each of the predetermined incision points.

In order to perform the mirror polishing, the tool, in effect, uses a contact member which detects the shape of the outer surface of the object to be processed, in such a way as to identify the trend of the diametric and/or longitudinal generatrices along which the incisions will be made.

In this type of machine, the detection of the shape of the outer surface of the object to be mirror polished is performed by a laser scanner (or by other suitable detection means) applied to the end of the robotic arm.

The scanner, after carrying out the detection, is unloaded and changed with the tool holder head which is zeroed bringing into contact its movable part, that is to say, that which retains the tool, with its fixed part, that is to say, that coupled to the end of the robotic arm.

Since the scanner, once it has detected the shape of the master piece, can no longer be used, this type of machine can mirror polish items with symmetrical surfaces or those items which, although having irregular shapes, have a circular cross section relative to the axis of symmetry defined by the two counter-tips.

This is because the machine is unable, along each incision section, to provide with an appreciable correctness, point by point, the different distance between the outer surface of the object to be mirror polished and the axis of symmetry defined by the two counter-tips.

These machines therefore do not enable the mirror polishing of objects with an oval, elliptic, semi-circular or quadrangular section or, in any case, non- circular cross-section.

Another drawback of this machine is due to the fact that, even though it is equipped with a second robotic arm for gripping and positioning the object to be mirror polished in the counter-tips, in the case of extremely irregular shapes, that is to say, abnormal, the second robotic arm is unable to pick up the object for positioning it between the counter-tips and the mirror polishing must therefore be interrupted, with all the resulting economic consequences.

Aim of the invention

The aim of the invention is to overcome the above-mentioned drawbacks of prior art types of machine for mirror polishing jewellery, goldsmith’s, silversmith’s and costume jewellery products which allows objects of any imaginable shape to be mirror polished, even with extremely irregular surfaces.

In the context of the above-mentioned purpose, an aim of the invention is to provide a machine for mirror polishing jewellery, goldsmith’s, silversmith’s and costume jewellery products, which provides a high quality product with maximum efficiency.

Another aim of the invention is to allow the automatic processing of any object, even of a strange and abnormal shape, without the continuous intervention of an operator.

Yet another aim of the invention is to provide a machine for mirror polishing jewellery, goldsmith’s, silversmith’s and costume jewellery products, with means which are easily available on the market and using materials of common use, in such a way that the device is economically competitive. This purpose, as well as these and other aims, which will become clearer from the following description, are achieved by a machine for mirror polishing jewellery, goldsmith’s, silversmith’s and costume jewellery products according to the invention, comprising, on a load-bearing frame: at least a first robotic arm designed to be moved by a central data processing unit, along several axes in a plurality of rotary movements, for supporting a tool holder head equipped with a tool for processing at least one series of objects to be mirror polished substantially identical to each other;

supporting means for stopping in the operating position and for rotating along a relative axis each of the objects of said series;

means for detecting the outer surfaces of an initial object of said series of objects, connected to said central unit for storing the shape of the initial object and/or for controlling the outer surfaces of each of the objects to be mirror polished;

said tool holder head being designed to activate said tool alternately along a direction of movement, in such a way that it can translate in one direction or the other independently of the plurality of rotary movements of said at least one first robotic arm;

said detection means being designed to be moved by said central unit along guide means, formed on said load-bearing frame, between a rest position of the detection means and a scanning position of the initial object or of one of the objects to be mirror polished.

Advantageously, the movement of the detection means between the rest positions, for example during the mirror polishing of the initial object, or of the objects of the series, and scanning of the initial object or of one of the objects to be mirror polished, without changing the tool holder head, allows the machine to perform the suitable measurements each time that an object to be mirror polished is loaded and mounted on the supporting means and therefore dynamically modify the position of the tool holder head relative to the shape of the surface to be mirror polished, adapting each time to the model stored in the central unit and the spatial orientation of the incision point.

Advantageously, the supporting means comprise a tip and a counter-tip, driven respectively by a first and a second motor controlled independently of each other by the central unit. The two tips, which are designed to retain the initial object (or each of the objects in the series) engaging it with two respective gripping holes defined in the initial object (and in each of the objects in the series), can in this way rotate the initial object (or each of the objects in the series) about its own axis independently or move at different heights relative to each other. Thanks to this system, it is possible to mount on the stop means objects of any shape and size, even very different from each other since the tip and the counter-tip move independently of each other along any axis of the object.

The supporting means also comprise an auxiliary motor connected to the tip and/or to the counter-tip for the rotation of the initial object or of each of the objects of the series, about the relative axis. For this reason, each object to be mirror polished, whether it is the initial object or any of the other objects in the series, may rotate about its axis in such a way as to suitably orient the surface portion to be mirror polished, offering it to the tool in such a way that the cutting direction of the latter at the incision point is always substantially normal relative to the surface to be mirror polished (a condition which, as is known, results in the best mirror polishing).

Alternatively, the supporting means comprise at least one fan for retaining the object to be mirror polished.

Advantageously, in this configuration, it will be possible to lock those objects which do not have gripping holes for engaging with the tip and the counter tip.

In this regard, if necessary also together with the fan, a gripper may be used. Preferably, the detection means comprise a three-dimensional laser scanner connected to the central unit.

Advantageously, the three-dimensional scanner is able to recognise the position of the gripping holes defined in the initial object (and in the other objects in the series), in such a way as to allow the correct positioning of the initial object (and/or of the objects in the series) between the tip and the counter-tip of the supporting means.

Even more preferably, the detection means are an artificial vision system (known as“computer vision”) which is able to create an approximate model of the real world, that is, three-dimensional, starting from two-dimensional images, in such a way as to allow not only the notching, but also the drawing and the incision on three-dimensional objects.

Advantageously, in order to automate the loading of the initial object and, more so, of the other objects of the series to be mirror polished, use is made of a second robotic arm connected to the load-bearing frame which is also - like the first arm - designed to be moved by the central unit along several axes in a plurality of rotational movements. This second robotic arm is therefore equipped with gripping means in such a way as to position the initial object or each of the objects of the series, on the supporting means. The processing method of the machine for mirror polishing jewellery, goldsmith’s, silversmith’s and costume jewellery products, according to the invention, comprises the following succession of steps:

positioning the initial object in the working position using the supporting means;

scanning the outer surfaces of the initial object using the detection means;

positioning the tool (14) by means of a primary movement for moving the tool holder head towards the object and/or the objects of the series; moving the tool holder head towards the initial object or towards an object of the series by means of a primary movement controlled by the central unit;

intermittently pressing the tool against the initial object, or any one of the objects to be mirror polished, at a predetermined incision point, with a secondary movement controlled by the central unit, moving the tool holder head alternatingly along the direction of movement, at the predetermined incision points of the initial object or of the objects of the series, until the mirror polishing is completed.

Advantageously, the central unit stores the shape of the initial object scanned by the detection means, creating a sample object (or“master”), in such a way as to use the information stored in the processing of the other objects of the series, which, as mentioned, are all substantially identical to the initial object.

Once the shape of the initial object has been stored, before processing the surface of an object of the series of objects to be mirror polished, the detection means scan the shape of this object and/or control the outer surfaces, in such a way as to compare it with said initial object (9’) and, advantageously, modify consequently the primary movement and/or the secondary movement, optimising the production, creating a perfectly mirror polished object, increasing the processing efficiency and minimising the rejects.

Obviously, during the processing of the initial object and of the objects to be mirror polished, the detection means are in the rest position. Advantageously, in order to overcome the technical difficulties which abnormal shapes can lead it, the detection means are able to recognise the position of the two gripping holes defined in the initial object, those which are designed to be engaged by the tip and by the counter-tip of the supporting means, in such a way as to correctly position the initial object and/or the objects of the series to be mirror polished.

Brief description of the drawings

Further features and advantages of the invention are more apparent in the detailed description below, with reference to a preferred, non-limiting embodiment of the machine for mirror polishing jewellery, goldsmith’s, silversmith’s and costume jewellery products, illustrated by way of example and without limiting the scope of the invention, with the aid of the accompanying drawings, in which:

Figure 1 schematically represents the machine 1 for mirror polishing jewellery, goldsmith’s, silversmith’s and costume jewellery products, according to the invention, with the scanner 5 in the rest position;

Figure 2 schematically represents the machine 1 of Figure 1 , with the scanner 5 in the scanning position.

Detailed description of preferred embodiments of the invention

With reference to the above-mentioned drawings, a preferred embodiment is shown of a machine for mirror polishing jewellery, goldsmith’s, silversmith’s and costume jewellery products, according to the invention, which is identified in its entirety with the numeral 1 and which comprises a machine for mirror polishing jewellery, goldsmith’s, silversmith’s and costume jewellery products, comprising, on a load-bearing frame 2, at least a first robotic arm 3 designed to be moved by a central data processing unit (not illustrated here), in a plurality of rotational movements along several axes. The arm 3 supports a tool holder head 4 equipped with a tool 14, of the“fan” type, for processing at least a series of objects 9 to be mirror polished, which are very similar to each other, in fact all substantially identical to each other apart from minor differences. The tool holder head 4 of the machine 1 is designed to activate the tool 14 alternately along a direction of movement 10, in such a way that it can translate in one direction or the other independently of the plurality of rotary movements of the first robotic arm 3.

The machine 1 also has a tip T driven by a first motor 1 T and a counter-tip 7” driven by a second motor 17” for stopping in the working position each of the objects 9 of the series (Figure 1 ). The two tips T and 7” hold in a first step an initial object 9’ which is used for sampling the shape to be processed, or each of the objects 9 when they are loaded.

The tip T and the counter-tip 7” engage the object 9’ (or the objects 9) in two respective gripping holes defined in the initial object 9’ (or in the objects 9) and allow the rotation about a relative axis 20 by means of the auxiliary motor (not illustrated).

The machine 1 comprises detection means 5, in this case a three- dimensional laser scanner 5, connected to the central unit, which scans the outer surfaces of the initial object 9’ (and the objects 9 of the series), for storing the shape of the initial object 9’ (and for controlling the outer surfaces of each of the objects 9 to be mirror polished).

The scanner 5 is moved by the central unit along guide means 6, defined on the load-bearing frame 2, between a rest position of the detection means 5 (Figure 1 ) and a scanning position of the initial object 9’ (or of one of the objects 9 to be mirror polished) (Figure 2).

With reference to Figures 1 and 2, the guide means comprise a slide 15, on which is mounted the laser scanner 5, moved along the direction of extension of the guide 6, with which it engages, with the guide 6 substantially parallel relative to the ground and which extends substantially parallel to the axis 20.

The central unit allows the positioning of the tool 14 by means of a primary movement for moving the tool holder head 4 towards the object 9 (or 9’) and a secondary movement of the tool holder head 4 so that the tool 14 touches the object 9 (or 9’) at a predetermined incision point. In the embodiment described here, the machine 1 comprises a second robotic arm 8 connected to the load-bearing frame 2. Similarly to the robotic arm 3, this element 8 is moved by the central unit along several axes in a plurality of rotational movements and is equipped with gripping means, for example a gripping protrusion 18, in such a way as to position the initial object 9’ or each of the objects 9 on the tip T and the counter-tip 7”.

In the variant described, the three-dimensional scanner 5 knows how to recognise the position of the gripping holes for the correct positioning of the initial object 9’ and/or of the objects 9 when they are placed between the tip T and the counter-tip 7”.

In practice, the initial object 9’ of the set of objects 9 to be mirror polished, all substantially identical to each other, is positioned between the tip T and the counter-tip 7” by means of the gripping protrusion 18 connected to the end of the arm 8.

The scanner 5, mounted on the slide 15 which translates on the guide 6, moves to the scanning position and detects the shape of the outer surfaces of the initial object 9’ and stores it in the central unit, creating a sample object.

The slide 15 translates on the guide 6 carrying the scanner 5 to the rest position, after which the head 4 performs the primary movement for moving towards the object 9’ and the secondary movement for pressing the tool 14 at the predetermined incision point, until the mirror polishing has been completed.

The object 9’ is then processed by the tool 14 thanks to the movements imparted by the unit to the tool holder head 4, mounted on the robotic arm 3.

Obviously, the initial object 9’ is removed and despatched for cleaning, whilst the second arm 8 picks up the second object 9 of the series from the storage system 19 and loads it on the tip T and the counter-tip 7”.

In this regard, the storage system 19 is equipped with a series of rods 21 a, 21 b, 21 c and 21 d, each of which is provided with a row of objects to be mirror polished. The objects of each rod 21 a, 21 b, 21 c and 21 d are all of the same type, whilst they may vary depending on the rod selected.

For example, the objects 9 of the rod 21 a are equal to those of the rod 21 b, but different from those of 21 c and from those of 21 d.

Since the object 9 is substantially identical to the initial object 9’, the unit recalls the information stored previously and activates the scanner 5 which returns to scanning the object 9 to check that there are no deformities, even imperceptible, with the sample object and - if this is the case - to prevent mirror polishing in an incorrect manner.

Firstly, the scanner 5 recognises the position of the gripping holes defined in the object 9, in such a way that the gripping protrusion 18 can correctly position the object 9 on the tip 7’ and the counter-tip 7”.

After completing its purpose, the scanner returns again to the rest position and the object 9 is mirror polished in the same way as the initial object 9’. The scanning and mirror polishing cycle of the objects 9 of the series continues until the objects of the series to be mirror polished are finished. From the above description it may be seen how the invention achieves the preset purpose and aims and in particular the fact that a machine is made for mirror polishing jewellery, goldsmith’s, silversmith’s and costume jewellery products which allows the mirror polishing of objects of any shape, even asymmetrical ones and which have extremely irregular surfaces.

In particular, the possibility of scanning each object before the processing and the fact that the tip and the counter-tip are movable freely from each other, because they are equipped with independent motor means, allows the mirror polishing machine to automatically process any object, even with a strange and abnormal shape and to provide a jewellery, goldsmith’s, silversmith’s and costume jewellery product of high quality at maximum efficiency.

Lastly, the use of means which are easily available on the market and the use of common materials makes the device economically competitive.

The invention can be modified and adapted in several ways without thereby departing from the scope of the inventive concept.

Moreover, all the details of the invention may be substituted by other technically equivalent elements.

In practice, the materials used, as well as the dimensions, may be of any type, depending on requirements, provided that they are consistent with their production purposes.