IT202100024245A1 - Apparatus and method for laser welding of cutting tools - Google Patents

Description

DESCRIPTION of the industrial invention entitled:

"Apparatus and method for laser welding of cutting tools",

DESCRIPTION TEXT

Field of invention

The present invention relates generally to the production of cutting tools, particularly diamond cutting tools, and is been developed with particular reference to the subject of laser welding of cut segments to a relative disc-shaped core.

Prior art

Cutting tools of the type indicated usually consist of a metal core and a diamond part. The metal core, usually a high-strength steel disc, is flat and ? peripherally equipped with the diamond part. The diamond part can? be a continuous crown, a continuous band or segmented, and ? usually formed from an alloy of industrial diamond and metal powders.

As far as is of interest here, the cutting discs with segmented crown are generally obtained by means of two main processing steps. In a first phase, the diamond segments are produced through a sintering process. In a subsequent phase, the aforementioned segments - destined to make the ?teeth? of the tool - are welded to the steel core, using a laser source.

Figure 1 exemplifies a portion of a generic diamond disc, indicated as a whole with 1, including the relative core 2 and the diamond segments 3 welded peripherally. In the example, the soul 2 ? provided, along its circumference, with grooves or radial cuts 2a (essentially having cooling functions, in the use of the tool), which define sectors 2b, on the outer edge of which the segments 3 are welded.

The laser welding equipment currently used in the production of diamond tools generally use a positioning system with linear and polar axes, designed to position the area to be welded (i.e. the diamond segment - core junction) below an optical system, also equipped with two interpolated axes (X and Y, in figure 1), able to draw the motif or welding pattern. The use of latest generation fiber optic laser generators allows you to move the focusing head of the laser beam, thanks to the fact that the movement is ? allowed by the fiber itself, as it is flexible. Therefore, thanks to the optical fiber, the laser beam, by means of a focusing optics, is moved along the required welding path, substantially in correspondence with the segment 3 - sector 2b interface.

This mode? welding therefore implies movements of the focusing head. These movements must be extremely precise, in order to ensure the necessary quality? of the process: there? complicates the realization of the welding apparatus as a whole. In addition, in the known apparatuses indicated, the cores are usually loaded and processed horizontally, or substantially parallel to the ground: this entails a significant footprint of the apparatus, particularly if one considers that it must be designed to process discs having very different diameters between them, for example between 100 and 1600 mm.

Summary and purpose of the invention

The present invention essentially proposes to indicate an apparatus and a method for laser welding of cutting tools which is immune to one or more? of the drawbacks mentioned above.

This and still other aims, which will become clearer hereinafter, are achieved according to the present invention by an apparatus and a method for laser welding of diamond cutting tools having the characteristics of claims 1 and 13, respectively. Preferred characteristics of the apparatus according to the invention are indicated in the sub-claims. The claims form an integral part of the technical teaching provided herein in relation to the invention.

Brief description of the drawings

Further objects, characteristics and advantages of the present invention will become clear from the following detailed description, made with reference to the attached drawings provided purely by way of non-limiting example, in which:

- figure 1 ? a schematic front elevation view of a portion of a generic diamond cutting tool, obtainable by means of the apparatus according to the invention;

- figure 2 ? a schematic side elevation view of a welding apparatus according to possible embodiments of the invention;

- figure 3 ? a schematic front elevation view of an internal machining unit of the apparatus of figure 2;

- figure 4 ? a partial and schematic perspective view of the working group of figure 3;

- figures 5-8 are schematic perspective views of as many parts of the working group of figure 3;

- figure 9 ? a schematic representation of a laser scanning group of the group of figures 3-4; And

- figure 10 ? a schematic representation of possible welding profiles obtainable by means of the apparatus according to the invention.

Description of preferred embodiments of the invention

In figure 2, with 10 ? indicated as a whole a welding apparatus according to possible embodiments of the present invention. Preferably the apparatus 10 ? configured as a ?stand alone? machine; that is, a machine dedicated exclusively to carrying out the welding operation, which is fed with metal cores 2 and cutting segments 3, particularly diamond segments, for the production of cutting tools. The modalities? of realization of the souls and of the segments of cut can be of type of per s? known, and regardless of the purpose? of the present invention. In the following it will be assumed that the cutting segments are diamond segments, so that the tools produced by the apparatus 10 will hereinafter also be identified as diamond discs, for simplicity.

The apparatus 10 has a supporting structure 11 which includes a pedestal or base 12 and is configured to support a plurality? of peripheral panels and top panels, some of which are indicated with 13. With the base 12, the panels 13 delimit a protected area, also closed at the top, in which? housed a? unit? of work 20, visible only partially in figure 2. Preferably, some of the panels are part of one or more? doors 14, for example mounted sliding on linear guides, in order to allow access to the aforesaid work area, for example for the purpose of loading cores 2 and diamond segments 3, as well as for unloading the finished diamond discs 1. At least a panel 13 pu? be transparent, to allow an operator to visually check from the outside at least part of the unit? of work 20. Moreover, within the protected area can be provided for one or more? cameras, not shown, for such a visual check by means of a suitable display device, for example belonging to a user interface described below.

The apparatus 10 comprises a user interface 15, provided with physical commands 15a (such as buttons, keys, selectors, etc.) and with a screen 15b, preferably of the tactile type, to which ? possibly associated with a keyboard 15c, for example a membrane keyboard. The user interface 15 integrates or ? associated with a?unit? of control, for example based on a Personal Computer, particularly with system Windows?, on which? loaded the application software which supervises the functioning of the apparatus 10; the unit? control ? schematically represented by block CU in figure 9. As will be seen, the control system of the apparatus, including the unit? CU and the user interface 15, has means for acquiring at least information representative of a type of core 2 to be treated and/or a type of cutting disc 1 to be obtained.

The apparatus 10 preferably includes other units? functional, not visible in figure 2, such as for example an electrical cabinet, a unit? of power of the laser welding system, a? unit? for cooling the laser welding system, a connection to a fume extraction system, a connection to an external pneumatic system, an air treatment unit.

The unit of work 20, what ? mounted on the base 12, ? shown in different views in Figures 3-5.

With 21? and 21? a loading or feeding arrangement for the cores 2 and an unloading arrangement for the diamond discs 1 are indicated. The loading arrangement 21? includes a stationary mast mount 22? (figure 4), carried by the base 12 and provided with a pin which protrudes frontally, ie in the Z direction of figure 4, which ? configured to be committable ? preferably with minimum tolerance - in the central hole of the cores 2 of the diamond discs 1 to be obtained (such a central hole is exemplified in figure 1, reference 2c). In the figures, the aforementioned pin is not ? visible, but assume it is identified by reference 22a?. With 23? ? indicated a mobile mast support, which ? mounted on a carriage or slide 24 arranged in a forward position with respect to the stationary support 22?. Sled 24? ? movably mounted on the base 12, to move in front of the support 222, transversely and parallel to it, ie in the direction X of figure 4, between at least one inoperative position, such as the one visible in the figures, and an operative position. For this purpose the slide 24? ? mounted on a suitable linear translation system 24a? (figure 4) operated by means of a relative actuator, which can? be a fluid cylinder or an electric motor.

Support 23? ? itself movably mounted on the slide 24?, by means of a relative motorized guide system 23a?, in order to be displaceable linearly between a forward position and a rearward position with respect to the stationary support 22?, i.e. in the Z direction of figure 4. The mobile support 23 ? ? equipped, in a position generally coaxial with respect to that of the pin 22a? of the stationary support 22?, of a releasable gripping system 23b?, capable of retaining and releasing a core 2 centrally supported by the pin 22a? of the stationary support 22?, as hereinafter explained. Preferably, the gripping system 23b? ? configured to hold each core at its front, and pu? include for this purpose a device with suction cups and one or more? electromagnets.

Download arrangement 21? ? substantially similar in construction to the loading arrangement 21?, and therefore including a stationary support 22? with pin 22a?, a movable support 23? with associated guidance systems 23a? and grip 23b?, mounted on a slide 24? with relative translation system 24a?. In the case of the download arrangement 21?, the movable support 23? and the related gripping system 23b? they are used for moving the diamond discs 1, as explained below. The 22a stud? of the stationary support 22? of provision 21? can? have a smaller diameter than the homologous pin 22? of provision 21?.

The useful height of the upright supports 22?, 22? and 23?, 23?, understood for example as the distance between the base 12, on one side, and each of the pins 22a? and 22a? or the 23a grip system? and 23? of the supports 22? or 23?, on the other side, ? such as to allow the support of cores 2 and discs 1 of different diameters, indicatively between 100 and 1,200 mm.

With 25 ? Overall, is an upright support structure indicated, carried by the base 12, in a position generally intermediate to the arrangements 21? and 21?. At the front of structure 25 ? slidably mounted a carriage or slide 26, for example by means of parallel linear guides, not indicated. From the slide 26 protrudes frontally a motorized spindle 27 (figure 3), which can be actuated in rotation, in a controlled manner, by a related electric motor, not visible, carried at the rear by the slide 26. As can be seen, the spindle 27 is? configured to selectively receive each metal core 2 to be processed, and ? controllable in rotation to bring different edge portions of core 2 in correspondence with a welding area.

Sled 26 ? movable in the vertical direction (ie the Y direction in figure 4), between a lowered position and one between a plurality? of possible raised positions. In the lowered position, is the mandrel 27 at substantially the same height as the gripping system 23b? and 23b? of the supports 23? and 23?, in order to be able to load the cores 2 to be welded first on the mandrel 27, and then withdraw the diamond disks 1 from the mandrel 27, respectively. As will be seen, with slide 26 in its lowered position:

- referring to the loading arrangement 21?, following the displacement of the slide 24? in its operative position and the subsequent movement of the movable support 23? in its forward position, the central hole 2c of the core 2 to be treated is engaged on the mandrel 27, and is released there by the gripping system 23b?; the support 23? and sled 24? they then return to their respective initial position;

- referring to the unloading arrangement 21?, following the displacement of the slide 24? in its operative position and the subsequent movement of the movable support 23? in its advanced position, the gripping system 23b? engages the diamond blade 1 just welded; by the subsequent movement of the support 23? in its retracted position, the disk 1 is separated from the mandrel 27, and then transferred laterally thanks to the subsequent movement of the slide 24? in its inoperative position.

At spindle 27 ? preferably operatively associated with at least one electromagnet, to hold the core 2 to be welded in position.

In the raised position of the slide 26, or in each of its possible raised positions, a peripheral portion of a core to be welded is in a defined height position, within a welding area (indicated by WZ in figures 8 and 9), as explained below. Preferably, the front of the slide 26 and the front of each of the supports 22? and 22? lie essentially in the same vertical plane.

An actuator system is associated with the support structure 25 for causing the slide 26 to move between the lowered position and the raised positions, the latter depending on the diameter of the cores 2, or of the discs 1 to be obtained; in the example, this system comprises an electric motor 28 which rotates a worm screw 28a, and the slide 26? associated at the rear with a relative non-visible transmission element, such as a nut, meshed with the worm screw 28a. Other systems are obviously possible for causing the slide 26 to move, for example a pinion-rack system, or a system based on the use of a controllable linear actuator.

With 30 ? Overall, an automated diamond segment feed system or arrangement is indicated. 3. The system ? mounted in a fixed position, for example to one side of the support structure 25, and can be made according to the technique itself? Note. As exemplified in Figure 5, the system 30 can understand, for example, a warehouse 30a that ? loadable manually by an operator, to whom ? operatively associated with a tape 30a? for urging the segments 3 in a release timing device 30b, the latter being configured to individually release the segments 3 from the magazine 30a to a picking zone 30c. As an alternative to tape 30a? the power system segments can? be achieved through the use of a vibrating cup.

With 31 ? indicated as a whole an automated system for picking up and transferring the diamond segments 3. The system 31 ? precisely arranged to individually pick up a segment 3 released by the feed system 30, in correspondence with the area 30c, and then transport it up to a processing area, represented by the welding area described below. For this purpose, system 31 can be achieved by means of any handling system known in the sector, such as a pick and place system, for example equipped with a gripper or electromagnets for picking up the single segment 3 and transferring it to the area of welding. In figure 5, ? partially visible is an example of system 31, equipped with a mobile head 31a carrying a gripper 31b, configured for picking up the single segment 3 from the picking area 30c of the system 30.

The control system of the apparatus 10 comprises means for acquiring at least information representative of a type of core 2 to be treated and/or a type of cutting disc 1. For this purpose, one or more? parameters (for example the diameter of the core 2 and/or the number of its slots 2a or its sectors 2b) can? be set manually by an operator via interface 15; in addition or alternatively, the unit? control CU can? also have already stored the aforementioned parameters, in which case the? operator ? called to select only the corresponding type of starting core or tool to be made.

In various embodiments, the means for acquiring the aforementioned representative information may comprise an automatic detection system. To this end, in the example shown, with 32 ? Overall, such a detection system is indicated, configured to detect characteristics of interest of the cores 2 being processed, such as the position of at least one relative radial groove 2a (figure 1) and/or their diameter. In various embodiments, the system 32 includes a sensing member which is displaceable in a controlled manner, by means of relative actuator means, to detect, by means of relative sensor means, the position of at least one of the slots 2a of a core 2 being worked, and possibly also the diameter of the core itself. Preferably, the aforesaid sensor means are sensor means of the optical type. In preferential embodiments, the aforesaid detection body ? movable mounted transversely to the axis of the spindle 27, i.e. in the X direction of figure 4.

A possible realization of the aforesaid detection body? shown in figure 6. In the exemplified case, the member, indicated as a whole by 32a, is substantially fork-shaped and therefore includes two arms 32b, substantially parallel and spaced apart from each other, for supporting a photocell. In the example the photocell comprises an emitter 32c and a receiver 32d of a beam of electromagnetic radiation, for example visible light, which are each associated with a respective arm 32b in facing and axially aligned positions.

In this embodiment, the control system of the apparatus ? preferably arranged in such a way as to carry out a detection step, based on the movement of the slide 26 and of the member 32a. For this purpose, after having taken charge of a core 2 by means of the mandrel 27, the slide 25 is translated vertically upwards (direction Y) up to an intermediate detection position, in which the core 2 is? capable of insinuating itself between the two arms 32b of the fork. After the translation of the slide 26 has stopped, the detection member 32a is translated laterally (direction X), and this translation is stopped when the light beam between the emitter 32c and the receiver 32d is interrupted by the core 2 which intervenes between them, cos? providing an indication of the diameter of the treated core. It should be noted that, in various embodiments, the diameter of the core 2 (as well as the number of its sectors 2b) is? a parameter which can be set manually via the user interface 15: the provision of the diameter verification function via the detection system 32 however allows to deal with any setting errors (for example an incorrect setting of the diameter on the interface 15, when the cores 2 actually loaded into the machine have a different diameter from the one set manually).

The exact position of a radial slot 2a of the core 2 is then identified, taken as a reference, and for this purpose a rotation of the spindle 27 is started, and therefore of the core 2: as can be understood, at a certain point of the rotation of the core 2 with respect to the photocell located near the edge of the core 2, between the emitter 32c and the receiver 32d will there be? to find a hollow 2a of the soul itself, with the receiver 32d that it will receive? the light beam again: in this way the angular position of the same is identified, and therefore of the sectors 2b of the core 2, for the purposes of the subsequent welding phase: this further information is then used by the control system of the apparatus to command the rotation of the mandrel 27, in order to position each sector 3b of the core 2 in succession in correspondence with the welding zone WZ.

Again in figure 3, with 33 ? indicates an arrangement or device for locking a single diamond segment 3 in the welding position, and with 34 ? indicated an arrangement or device for locking the core 2 in the welding position. The devices 33 and 34 are mounted on the support structure 25 and, in various preferential embodiments, each include a respective gripper, actuated by related actuator means, for example an electric or fluid actuator. The two devices 33 and 34, of conception per se? note, they are also represented in figure 7, where one of the two jaws of the gripper 33a of the device 33, and one of the two jaws of the gripper 34a of the device 34 are visible. In the same figure 7 the mandrel 27 is also partially visible bearing a relative 2, as well as the pick-up area 30c of the individual segments 3, with the gripper 31b of the feeding system 30.

The devices 33 and 34 are in a substantially stationary position (obviously regardless of the opening and closing movements of the relative jaws, which takes place in the Z direction of figure 4), with the previously indicated welding area which is substantially between the relative grippers 33a and 34a. The concept ? exemplified in figure 8, where the blocking devices 33 and 34 are partially visible, with the gripper 33a of the former which blocks a diamond segment 3 in abutting position on the relative sector 2b (laterally delimited by the two relative slots 2a) of the core being worked 2, the latter being in turn locked in position by the gripper 34a of the device 34. In figure 8, by way of example only, ? the welding zone WZ in an intermediate position between the two visible jaws of the grippers 33a and 34a is also indicated.

Finally, in figures 3 and 4, with 40 ? indicated overall a unit? welding, which comprises a laser scanning unit 50, described below. The unit 40 has a relative bearing structure or casing for the scanning group, this casing being preferably mounted on the support structure 25. Preferably, the unit? 40 has a case mounted in a stationary position, subject to possible prior adjustment of its position in the direction of depth? (Z, figure 4), to bring the optics of the unit closer or further away? 40 from the core 2 being processed and thus allow to maintain the best focus of the laser beam on the welding area, having to compensate for variable core thicknesses. There? That ? important to underline for the purposes of the present invention ? that, during the welding operations, the unit? 40 remains in a stationary position, i.e. it does not require any movement according to the X and Y axes. This possibility? ? allowed by the use of the particular laser scanning group 50 of the unit? 40, which integrates focusing means, to concentrate the laser beam and produce a welding spot to be addressed in the welding area WZ, and displacement means, to cause movement of the laser beam and make the welding spot follow a predetermined trajectory in the ?scope of the welding zone WZ; the moving means are controlled by the control system according to at least one piece of information representative of the type of cores to be treated and/or of discs to be obtained.

An example of a laser scanning group 50 ? schematically represented in figure 9. With reference to this figure 9, in various embodiments, the generator of the laser radiation used for welding purposes - schematically represented by block LG -? a diode laser generator, with modulable power from 0 to about 4000 W, particularly equipped with OF optical fiber for transporting the laser beam to the WZ processing area.

The laser beam B generated by the laser generator LG is preferably brought, via the optical fiber OF, to a collimator CL, and addressed to the scanning device in the strict sense, which deflects the beam B by 90°, in any case so as to point it into the laser beam. scope of the work area WZ.

In the preferred embodiment, the movement means inside the scanning group 50 comprise at least two mirrors M1 and M2, preferably water-cooled and coated on the surface with materials suitable for reflecting the laser beam, which mirrors are actuated according to respective axes of actuation A1 and A2 by high speed galvanometers G1 and G2. The M1 and M2 mirrors moved by the G1 and G2 galvanometers allow to position the laser beam B in any point of a WZ working area defined by the type of a FL lens, particularly an F-Theta lens. Beam B is preferably collimated to obtain a spot having a diameter of between 0.15 and 0.5 mm, particularly a diameter of approximately 0.25 mm.

In the implementation example considered here, ? An F-Theta lens was employed which covers a WZ working area of approximately 160 x 160 mm. Although it is not excluded the use of lenses pi? large (for example up to cover an area of 400 x 400 mm) the limit of 160 x 160 mm must be understood as preferable since, beyond this measure, the deformation of the laser beam B can? be too high to allow good pointing and good distribution of energy inside the spot.

Thanks to the use of galvanometers G1 and G2, the speed? of displacement of the beam B, and therefore of the relative punctiform spot, ? very high, indicatively up to 10000 mm/sec; thanks to this high speed?, ? possible to scan and then subject to welding - very quickly and particularly with precision in the order of 5 ?rad - the entire area to be welded of each single segment 3.

Merely by way of example, the scanning groups that can be used in the application proposed here are those called ?Power Scanners? of IPG Photonics Corporation, Oxford, MA, USA.

The path or trajectory of the laser spot substantially in correspondence with the interface area between the segment 3 to be welded and the relative sector 2b (figure 1) of the core 2 is defined by the unit? control unit CU which, when selecting the operating program by means of the user interface 15, particularly on the basis of the type of core 2 and/or its characteristics (such as diameter and/or number of sectors), manages the profile to be submitted welding, i.e. the path or trajectory that the laser spot must follow, possibly with repeated subsequent steps. The operational program? arranged to control the scanning group 50 according to the different types of components to be welded, for example in terms of diameter of the cores 2, number and/or dimensions of the segments 3, and more? in general of parameters that can be entered via the user interface 15.

Will you appreciate it? that, thanks to the scanning device based on the use of two mirrors and related galvanometers, as well as? upon preparation of adequate operating programs, it is possible to define various welding profiles using the laser spot, according to needs.

Figure 10 exemplifies some possible alternative welding profiles for this purpose. It should be noted that in this figure, for simplicity?, the radial slots 2a of the cores 2 are not shown. In part a) of figure 10 ? exemplified the welding pattern W pi? simple, with the laser spot which substantially follows the interface profile between the core 2, or a related sector 2b, and the diamond segment 3. Part b) of figure 7 exemplifies a similar case, where however the welding pattern W ? intermittent. Parts b) and c) of figure 7 relate to welding pattern W pi? complex, and difficult to obtain - if not with extreme complication - by means of apparatuses according to the prior art. Part c) of the figure represents a serrated or zig-zag pattern W, obtainable substantially by nutating the sport laser, while part d) of the figure represents a pattern W substantially in the shape of an elongated cycloid (i.e. resembling a stretch of a curve of the trochoidal type, particularly epitrochoidal). Note that the weld pattern ? in any case obtained by following the interface profile between a segment 3 and the core 2 (or a sector 2b thereof), and therefore a theoretical arc.

A major advantage of using the 50 scanning group ? represented by the fact that the unit? of welding 40 which includes it, does not require movements of a focusing head of the laser beam according to two interpolated axes during the process, as instead typically occurs according to the prior art, thus avoiding the related problems mentioned in the introductory part of this description. The time needed to carry out the welding is also very reduced.

A further substantial advantage of the invention ? represented by the fact that the apparatus described allows the cores 2 and the discs 1 to be moved and processed by keeping them in a vertical position, or substantially perpendicular to the ground, with a significant reduction in the overall dimensions of the apparatus, despite the possibility to process discs with even very large diameters (as mentioned, indicatively up to 1600 mm in diameter).

The functioning of the apparatus 10 can? be schematically summarized as follows.

Is a certain number of cores 2 arranged manually on the appropriate pin 22a? of the stationary mast 22? of the loading system 212, and a certain number of segments 3 are loaded manually into the magazine 30a of the feeding system 30 (it should be noted that the loading of the cores 2 onto the aforementioned pin 22a2 could possibly be automated). Through the user interface 15, the operator sets the parameter or parameters necessary for welding, these parameters including for example the diameter of the cores 2, the number of the relative slots 2a or of the relative sectors 2b and/or of the corresponding diamond segments 3. How said, the software that equips the? unit? control CU can? already have stored the aforementioned parameters, in which case the? operator ? called to select only the corresponding type of starting core or tool to be made. In various preferential embodiments can? also the selection, for example via the interface 15, of a welding profile or pattern among a plurality? of possible welding profiles or patterns, such as those exemplified in figure 10. Moreover, in principle, the welding profile or pattern could be predetermined (for example that of part a) of figure 10), obviously depending on the diameter of the souls 2.

The processing cycle can be subsequently started, provided that the doors 14 (figure 1) are closed.

After launch, mobile support 23? of loading format 21? does it move forward (direction Z) by means of the relative guide system 23a? (figure 4) to withdraw the first core 2 from the aforesaid pin 22a?, by means of the relative gripping system 23b?; as mentioned, the 23b grip system? can? include a suction cup device which, following the forward translation of the movable support 23?, couple to the core 2 and which, when subsequently the movable support 23? moves backwards, allow the core to be detached from the pin 22a?; the 23b gripping system? preferably also includes one or more? electromagnets, which are subsequently activated, to hold the core 2 withdrawn. The slide 24? is then actuated, so as to translate laterally (direction X) the movable support 23? and bring it into a position aligned with the spindle 27, given that in this phase the slide 26 is? in the respective lowered position. Via the 23a guidance system? the mobile support 23? is made to advance again until the central opening 2c (figure 1) of the core 2 fits on the mandrel 27. It should be noted that the mandrel 27 can? have at least a slightly truncated cone shape, in order to facilitate coupling. After this positioning, the electromagnet or electromagnets of the gripping system 23b? are deactivated, and at least one electromagnet of the mandrel 27 is instead activated, in order to keep the core 2 on it. The support 23? then it translates back again, and by operating the slide 24? can? be returned to the loading position.

The slide 26 is then raised, by means of the relative actuator system 28-28a, bringing the core 2 to the previously described intermediate position for detecting the position of a reference groove 2a. For this purpose, as previously described with reference to figure 6, the detection member 32a of the detection system 32 is translated and a rotation of the spindle 27 is started, in order to cause a corresponding movement of the core 2. After the detection of the position of the reference groove 2a, as previously described, the slide 26 is further translated upwards, until bringing the core itself into a relative machining position, in which the peripheral area of the core 2 is located within the area weld WZ (figure 8). Of course the entity? of the translation depends on the diameter of? core 2, this information being already? been acquired, as indicated above. At this point the gripper 34a of the locking device 34 is closed, in order to lock the core 2 in the welding position, as in figure 8. If necessary, before closing the gripper 34a, the mandrel 27 is again actuated in rotation, so that bring the sector 2b of the core 2 to a predefined position for the purposes of subsequent welding, as in figure 8; the entity? of the required rotation of the spindle 27 ? note to? unit? of control CU, on the base of? information acquired of position of the quarry 2a of reference, as well as? of other set or memorized parameters (for example one or more of the diameter of the core, number of sectors of the core and/or their angular development, angular development of the segments, etc.).

The feed system 30 releases a single diamond segment 3 to the pick-up area 30c, via the timing device 30b (figure 5). The pick-up and transfer system 31 is then actuated, with the gripper 31b of the relative movable head 31 which picks up the segment 3 from the pick-up area 30c and brings it to a respective processing position, in which the segment itself has its lower edge abutting on a corresponding edge portion of the core 2, or of a sector 2b thereof, in correspondence with the welding zone WZ. When segment 3 ? in this position, with the segment 3 in contact with the relative sector 2b of the core 2, as in figure 8, the gripper 33a of the locking device 33 is closed, in order to lock the segment 3 in position as well. The gripper 31b of the system 30 opens and returns to the initial position, for picking up a subsequent segment 3.

At this point the unit? control unit CU commands the start of the laser welding of the segment 3 on the relative sector 2b of the core 2. In particular, referring to figure 9, the unit? control CU commands the activation of the laser generator LG and of the galvanometers G1 and G2, so that the relative mirrors R1, R2 address the laser spot referred to in beam B in the zone WZ. The galvanometers are controlled so that the laser spot follows a trajectory such as to subject at least the interface zone between the segment 3 and the relative sector 2b of the core 2 to treatment, while the segment and core are locked in position. The points of the effective trajectory followed by the laser spot are determined by an interpolator implemented in the unit? control CU, as a function of the determined welding profile or pattern and of the information or information representative of the type of core 2 to be treated and/or of the disc 1 to be obtained. As mentioned, the welding profile can? be predetermined by the control system, or can? be chosen among various possible profiles (such as those exemplified in figure 10), thanks to the considerable flexibility? operation of scanning group 50.

The fumes that originate as a result of laser welding can be evacuated from the treatment area by means of an aspiration system.

At the end of the welding, the grippers 33a and 34a of the locking devices 33 and 34 open and the mandrel 27 is actuated to cause an angular movement of the core 2 such that a new sector 2b of the core itself is brought into the position of welding in figure 8; to there? this is followed by the closing of the gripper 34a; the system 31 then picks up a new segment 3 and transports it to the welding position of figure 8, as already described above, after which? also the gripper 33a is closed again, and the new laser welding is carried out. The cycle is repeated for all the segments 3 which must be welded on the core 2.

Once the welding of the last segment 3 has been completed, the now finished diamond disc 1 is unloaded and a new core 2 is loaded.

For this purpose, the slide 26 which carries the disc 1 on the spindle 27 is translated towards the lowered position. Sled 24? of download arrangement 21? is it laterally translated to carry the relative movable support 23? in an aligned position in front of the mandrel 27. Through the relative guide system 23a?, the movable support 23? is it then made to advance, with the sucker device of its gripping system 23b? which detaches the disk 1 from the mandrel 27, after the electromagnet of the latter ? deactivated state; the electromagnet or the electromagnets of the gripping system 23b? they are then activated to hold the finished disk 1 (it should be noted that the system 23b? could also be without the sucker device, the electromagnet system alone also being sufficient). Sled 24? of provision 21? is then translated horizontally in the opposite position to the previous one, in order to carry the relative movable support 23? bearing the disc 1 in a frontally aligned position with the fixed support 22?: by means of the translation system 23a?, the movable support 23? is it advanced, so that the central opening 2c (figure 1) of the disc 1 is fitted onto the pin 22a? of the fixed support 22?; the electromagnet of the system 23b? is therefore deactivated, and the movable upright 23? is pushed back, cos? leaving on pin 22a? the disk 1. Meanwhile, as mentioned, the loading arrangement 21? can? be operated as previously described, for the withdrawal of a new core 2.

Are the strokes of the various mobile elements indicated controlled in a per se way? known, for example by using sensor means widely known in the field.

The apparatus 10 preferably also includes setting systems in order to allow the treatment of cores which differ from one another in terms of thickness and/or dimensions of the relative central hole 2c. In this perspective, for example, the pin 22a? of support 22? of loading format 21? they can be replaced in advance, according to the diameter of the aforementioned central hole 2c. The same applies to a possible centering element that equips the mandrel 27. The locking position of the pliers 33a and 34a can? be equally adjustable in advance (for example by means of knobs), according to the thickness of the cores to be treated, in order to achieve optimal centering in correspondence with the welding area. The same applies to the position of the gripper 31b of the feed system 30.

From the description given, the characteristics of the present invention are clear, so how clear are its advantages.

? clear that numerous variants are possible for the person skilled in the art to the apparatus described as an example, without thereby departing from the scope of the invention as as defined by the following claims.

Claims (15)

1. An apparatus for laser welding of diamond cutting segments (3) to metal cores (2) of diamond cutting discs (1), comprising: - a first positioning arrangement (25-27), configured to position a metal core (2) at a respective first machining position, - a second positioning arrangement (31), configured to position a diamond cutting segment (3) at a respective second processing position, wherein the first machining position and the second machining position are such that, with the metal core (2) in the first machining position and the diamond cut segment (3) in the second machining position, the cutting segment diamond (3) has an edge abutting on a corresponding edge portion of the metal core (2), in correspondence with a welding area (WZ), the apparatus (10) further comprising: - a first locking arrangement (34), configured to lock the metal core (2) in the first machining position, - a second locking arrangement (33), configured to lock the diamond cutting segment (3) in the second machining position, - a control system (CU, 15, 32), including a unit? control (CU) and means (15, 32) for acquiring at least information representative of a type of metal core (2) to be treated and/or a type of diamond cutting disc (1) to be obtained, - a unit? welding (40), configured to direct a laser beam (B) generated by a laser radiation source (LG) within the welding area (WZ), to weld the diamond cut segment (3) to the metal core (2), in which the? unit? welding machine (40) comprises a laser scanning group (50) which integrates: - focusing means (FL), configured to concentrate the laser beam (B) and produce a welding spot to be directed into the welding area (WZ); - displacement means (G1, G2, M1, M2), configured to cause movement of the laser beam (B) and make the welding spot follow a predetermined trajectory within the welding area (WZ), the displacement means (G1, G2, M1, M2) being controllable by the control system (CU, 15, 32) according to said representative information. 2. The apparatus according to claim 1, wherein the laser scanning group (50) comprises at least two mirrors (M1, M2), actuated according to respective actuation axes (A1, A2), particularly by means of galvanometers (G1, G2) , and a focusing lens (FL), particularly an F-Theta lens. 3. The apparatus according to claim 1 or claim 2, wherein in the unit? of control (CU) ? implemented an interpolator, configured to use at least said representative information to identify points of the predetermined trajectory for the welding spot within the welding zone (WZ). 4. The apparatus according to any one of claims 1-3, wherein the unit? solder (40) has a support or casing for the laser scanning group (50) which ? mounted in a stationary position, without prejudice to a possible preventive adjustment of its position in a direction of depth? (Z). 5. The apparatus according to any one of claims 1-4, comprising at least one of: - a first feed arrangement (21?), configured for selective feeding of metal cores (2) to the first positioning arrangement (25-27), - a second feeding arrangement (30), configured for selective feeding of diamond cutting segments (3) to the second positioning arrangement (30), - an unloading arrangement (21?), configured for withdrawing diamond cutting discs (1) from the first positioning arrangement (25-27). 6. The apparatus according to any one of claims 1-5, wherein the first positioning arrangement (25-27) is configured to move each metal core (2) while keeping it in a vertical position. 7. The apparatus according to any one of claims 1-5, wherein: - the first supply arrangement (21?) ? configured to move each metal core (2) keeping it in a vertical position, e - the download arrangement (21?) ? configured to move each diamond cutting disc (1) keeping it in a vertical position. 8. The apparatus according to any one of claims 1-7, wherein the first positioning arrangement (25-27) comprises a post structure (25) and a slide (26), which is mobile mounted on the upright structure (25) and ? displaceable in a vertical direction (Y) between at least one lowered position and at least one raised position. 9. The apparatus according to any one of claims 1-8, wherein the first positioning arrangement (25-27) comprises a mandrel (27), which is configured to selectively receive each metal core (2) and ? controllable in rotation to bring different edge portions of the metal core in correspondence with the welding zone (WZ). 10. The apparatus according to any one of claims 1-9, wherein at least one of the first feed arrangement (21?) and the unload arrangement (21?) comprises: - a stationary upright support (22?, 22?), configured to support one or more? metal cores (2), respectively one or more? diamond cutting discs (1), - a mobile upright support (23?, 23?), which ? translatable in a horizontal direction (X) in front of the stationary mast support (22?, 22?), transversely and parallel to it, between at least one inoperative position and one operative position, in which the movable upright support (23?, 23?) ? also movable in a direction of depth? (Z) between a forward position and a rearward position with respect to the stationary mast support (22?, 22?), and wherein the movable upright support (23?, 23?) has a releasable gripping system (23b?, 23b?), configured to hold and release a metal core (2), respectively a diamond cutting disc (1) , compared to the stationary mast support (22?,22?). 11. The apparatus according to any one of claims 1-10, wherein the means (15, 32) for acquiring at least information representative of a type of metal core (2) to be treated and/or a type of diamond cutting disc ( 1) to be obtained comprise an automatic detection system (32), configured to detect at least one of a diameter of a metal core (2) being processed and an angular position of a radial slot (2a) of a metal core (2 ) under processing. 12. The apparatus according to any one of claims 5-11, wherein: - the second supply arrangement (30) comprises a release device (30b) configured to individually release diamond cutting segments (3) to a pick-up area (30c), the timing device (30c) being associated with a magazine (30a ) having a conveyor belt (30a?) or a vibrating bowl, and/or - the second positioning arrangement (31) comprises a gripping member (31a) configured to individually pick up a diamond cutting segment (3) from the second feeding arrangement (30), and subsequently transferring and releasing said diamond cutting segment (3) at the second processing position. 13. A method for laser welding diamond cutting segments (3) to metal cores (2) of diamond cutting wheels (1) in a welding apparatus (10), the method comprising: a) position a metal core (2) in correspondence with a first processing position and position a diamond cut segment (3) in correspondence with a second processing position, where, with the metal core (2) in the first position working position and the diamond cut segment (3) in the second processing position, the diamond cut segment (3) has an edge abutting on a corresponding edge portion of the metal core (2), in correspondence with an area of welding (WZ), b) activating at least one laser radiation source (LG) and directing a laser welding spot towards the welding area (WZ) by means of a laser scanning unit (50), the method including the steps of: i) acquire representative information of at least one of a type of metal cores (2) to be machined and a type of diamond cutting discs (1) to be obtained, ii) determining a weld profile; iv) concentrating a laser beam (B) by means of the laser scanning assembly (50), to produce the laser welding spot to be addressed in the welding area (WZ), and determining a predetermined trajectory for the laser welding spot which depends on the determined welding profile; v) using the laser scanning unit (50) to control the movement of the laser beam (B), to make the laser welding spot follow the predetermined trajectory, while the metal core (2) and the diamond cutting segment (3) are stuck in the first position and second position, respectively. 14. The method according to claim 13, wherein at least one of step iv) and step v) comprises actuating at least two mirrors (M1, M2) of the laser scanning group (50), according to respective actuation axes (A1, A2), to direct and move the laser beam (B) through a focusing lens (FL) which determines the laser welding spot. 15. The method according to claim 13 or claim 14, wherein the metal cores (2) to be processed and the diamond cutting discs (1) are moved in the welding apparatus (10) keeping them in vertical position.