Field of the invention

The present invention relates to the field of marking surfaces by abrasion.

The invention has been developed with particular regard for an apparatus and process for marking surfaces of vehicles by abrasion. The surfaces which can be marked by means of the invention may be, for example, but in a non-limiting manner, the plate glass panes of the vehicles, the headlights, the rear-view mirrors and other portions and surfaces made of glass, plate glass, plexiglass, fibreglass, plastics material, metal and the like.

Technological background

It is known to mark the plate glass panes of vehicles, that is to say, the side windows, the windscreen and the rear window, for unique identification thereof for anti-theft purposes. The known marking system is carried out by means of surface abrasion of the plate glass panes and commonly makes use of a marking mask which reproduces in a negative state the marking code to be reproduced on the plate glass pane. The marking mask is supported on the plate glass pane to be marked and there is projected against it the abrasive material which makes the glass opaque in the zones left uncovered by the marking mask, leaving printed at that location the code or the symbol desired. This known methodology is described, for example, in the patent documents IT 19860003412 and IT 19860003374 which date from 1986 in the name of the same inventor Roberto Muriana.

The conventional marking system has a number of disadvantages which have caused the inventor to develop the innovative solution described below. In the conventional system, the marking mask against which the abrasive is projected is constituted by a frame, on which there are positioned the perforated tiles of the letters and numbers to be marked. If the equipment is not used correctly and checked periodically, there are brought about various disadvantages and a gradual worsening of the quality of the marking. For example, the perforated tiles of the marking mask tend to be consumed at the perimeter of the shape of the character, generating over time a marking which is not very sharp and has blurred edges. The perforated tiles also tend to become consumed at the external edges thereof with the result that a gap is formed between adjacent tiles and produces a marking which shows slight vertical stripes between one character and another. For these reasons, the tiles for the marking have to be replaced periodically with new tiles. The replacement of the tiles of the marking mask is delegated to the operators and it is not thereby easy to organize and programme the maintenance by, for example, the person who coordinates the marking of the vehicles at various separate sites. It is further difficult for this same person to manage to control the actual activity of marking carried out in the individual sites and by the individual operators.

Another disadvantage is constituted by the fact that the pressure of the air compressor which provides for projecting the abrasive is not easy to control for each marking and is at risk of being too low or too high. In the case of excessively low pressure, the marking may appear to be light at the centre and virtually invisible at the extremities of the writing. In the case of excessively high pressure, in addition to the fact that the marking is coarse, especially at the centre of the marking mask, both the perforated tiles of the marking mask and the nozzle for dispensing the abrasive become degraded more rapidly. Another disadvantage of the conventional system is the difficulty in correctly positioning the equipment on the plate glass panes or on the optical units of vehicles, especially if they have a given curvature, with the risk that the poor positioning may leave a space between the marking head of the equipment and the surface to be marked, affecting the good completion of the marking .

Another problem of the conventional marking is the fact that it is impossible to check that the operator places the correct code on the vehicle and therefore that it is impossible to prevent errors if not even occurrences of fraud in the marking process, which is critical per se during the subsequent administration of the marked vehicle for anti theft or insurance purposes.

Statement of invention

An object of the invention is to solve the problems and to overcome the disadvantages of the prior art by providing an apparatus and a process for marking surfaces by abrasion which is reliable, controllable, repeatable, precise and economical .

In order to achieve the objects set out, the invention relates to an apparatus and a process having the features indicated in the appended claims.

An advantage of the present invention is particularly that of overcoming the disadvantages of the prior art while, however, retaining the positive aspects thereof. For example, the type of marking by continuous abrasion in order to carry out opacification of the glass in the desired areas but without cutting it in such a manner that there are no occurrences of damage or cracks in the structure of the glass which therefore keeps the original resistance thereof unchanged. Furthermore, the system of the present invention can continue to make use of an atoxic abrasive such as corundum which is recovered by suction in order to safeguard the health of the operator .

Always with a view to protecting the health of the operator, in the system of the present invention it is possible to use cartridges for charging the abrasive in the equipment. In this manner, the operator does not come into contact with the abrasive, even though it is atoxic, such as corundum, not even during the step of recharging the equipment.

Notwithstanding the system of the present invention maintains the above-mentioned similarities to the conventional system, the differences and the improvements with respect to the prior art are numerous and significant and directly influence the quality of the marking.

An advantage of the invention is that perforated tiles are not used to carry out the marking. Instead, there is used a system by means of which the marking nozzle is moved automatically in order to carry out the marking. In particular, the marking nozzle can be moved in two directions, for example, along two mutually orthogonal axes which are located in a plane perpendicular to the abrasive jet which is projected from the nozzle. The dispensing of the abrasive can be adjusted automatically, by controlling the opening and closing of the nozzle. The apparatus can further be provided with an air pressure regulator which is, by way of non-limiting example, integrated in a coupling which is provided for an external air compressor so as to ensure dispensing which is as uniform as possible and therefore homogeneous marking.

Another advantage of the invention is to have a given degree of adaptability of the front portion of the head so as to be adapted to the potential convexity/concavity of the surface to be marked. This characteristic is ensured by the presence of a resilient component which is mounted on the end of the nozzle which is supported on the surface to be marked.

Another advantage is the particularly low use of abrasive product as a result of the automatic regulation of the dispensing operation by the nozzle. Furthermore, the abrasive is practically recovered completely by a suction unit which is provided in the equipment, thereby reducing the risk that it becomes introduced into the gap between the glass and the frame of the vehicle or inside the passenger compartment. The lower consumption of abrasive also brings about less wear of the nozzle and of all the members which are struck by the abrasive itself.

The use of an electronic control allows control of various operating parameters, such as, for example, the number of vehicles marked by each individual equipment item, the number of glass panes or surfaces marked by each individual equipment item, which identification codes have been marked (number plate, frame, QR code, etc.) and for how many times, what are the times which pass between the registration of the vehicle, the marking thereof and the publication of the documents which attest to the marking having been carried out (for example, the identification certificate), what are the marking times of each individual vehicle and/or glass pane, etc. According to an advantageous aspect, the operation of the equipment of the invention depends on a preliminary authorization process which requires that any vehicle to be marked have to be first registered and controlled before the apparatus receives permission for marking. Another advantage is that the equipment of the invention allows very accurate estimates to be produced for maintaining it. For example, knowing the maximum number of markings which can be carried out by each individual component before wearing out (nozzle, suckers, support mats, etc.), it is possible to intervene in order to maintain the equipment in an efficient state and consequently also the quality of the marking. The intervention information can also be notified to the operator via the control console.

Another advantage of the invention is the fact that the head of the apparatus is anchored to the glass or more generally to the surface to be marked via very powerful suckers which allow the operator not to have to hold the equipment via the handle thereof during the marking operation. The fixing of the head by the adhesion provided by the suckers allows repetition of the marking operation on the same surface until the pressure of the suckers is reduced in order to remove the head. The secure anchoring provided by the suckers allows the position of the head to be kept steady for the whole of the time necessary. Furthermore, the apparatus of the invention is capable of autonomously managing the flow of air/abrasive admixture in order to dispense the correct dose of abrasive and at the correct operating pressure.

With the system of the invention, the codes to be marked are transmitted via software. The codes can be transmitted from a remote processor to the processor mounted on the apparatus or can be input manually by an operator directly at the apparatus itself. In any case, the codes can be subjected to a preventive electronic control before permission is given for the actual marking operation itself. Furthermore, there can be used an optical recognition system for the number plate or the frame in the step of authorizing the marking.

Another very advantageous aspect is that it is possible to be able to design any character and symbol within a predefined marking area. The marking which can be carried out by means of the present invention can therefore extend beyond the simple sequence of characters which can be obtained with the conventional system. The firmware of the apparatus may provide for multiple characters to be managed (for example, oriental characters, ideographs, various icons and symbols) and also graphical logos, for example, the logos of the various automotive manufacturers. It is also possible by means of the invention to carry out the marking of a QR code, for example, on the windscreen of a vehicle, which can readily replace the application of an adhesive tag or other countermark, with the advantage that the QR code can already be generated dynamically during the authorization step.

The equipment is configured in such a manner that the predefined marking area can be positioned at the edge of a surface, for example, at the edge of a plate glass pane of the vehicle, behind a frame portion which projects further than the surface to be marked. In this manner, it is possible to mark, for example, a QR code in the lower zone of the windscreen of a vehicle, near the bonnet, thereby advantageously making use of the black strip which is produced on all modern windscreens in order to mask the wiring and the recesses of the instrument panel on the body of the vehicle. The marking of the QR code on the black strip of the windscreen has the substantial advantage of generating a good light/dark contrast for the optical detection of the code with commercial readers.

According to a first aspect, there is described an apparatus for marking surfaces by abrasion which comprises a dispensing group for a flow of air and abrasive. The flow is conveyed to a marking nozzle which is advantageously mounted in a movable manner on a marking head. There is further provided a selective shut-off valve for the flow of air and abrasive. A control group is configured to control both the selective opening and closing of the shut-off valve and the movement of the marking nozzle in a marking plane. The marking plane is substantially transverse to an emission direction of the mixture of air and abrasive from the marking nozzle on a surface to be marked.

According to a particularly advantageous aspect, the marking nozzle can be mounted on a system of at least two carriages which are movable in translation in the marking plane in two mutually orthogonal directions by means of respective motorized transmissions which are controlled by the control group.

According to another particularly advantageous aspect, the marking head comprises a plurality of suckers which are selectively controlled in terms of suction in order to fix the marking head to the surface to be marked. In a preferred advantageous form, the suckers are connected to a vacuum pump via two alternating circuits which are connected to a first group of suckers and to a second group of suckers, respectively. A selector allows activation of the suction alternately on the suckers of the first group of suckers and/ or on the suckers of the second group of suckers. It is thereby also possible to connect the marking head to surfaces with a small extent or with accentuated curvature, such as, for example, the headlights of a vehicle.

According to another particularly advantageous aspect, the marking nozzle and the shut-off valve are mounted on a movable marking group in the marking plane. The marking group comprises a head which is intended to be supported against the surface to be marked. The head may comprise resilient members in order to be adapted to the formation of the surface to be marked. A suction group can be connected to the marking group in order to draw in the abrasive emitted by the marking nozzle during the marking of the surface. In a preferred advantageous form, the resilient members may comprise self-aligning bearings which are relatively compressible and which are arranged at the end of the head for the support against the surface to be marked. Additionally or alternatively, the resilient members may comprise resilient means which apply a resilient thrust to a retractable support member on which the marking nozzle is mounted .

According to another particularly advantageous aspect, the shut-off valve is a sleeve type valve which is mounted near the marking nozzle. The sleeve type valve is effective, does not wear substantially with respect to the valves of other types and is further simple and economical to replace after a predefined number of markings.

According to another particularly advantageous aspect, the dispensing group of a flow of air and abrasive comprises a tank of abrasive which is supplied from a replaceable abrasive cartridge. As mentioned above, this allows simple and effective control of the abrasive recharging operations, further protecting the health of the operators. Advantageously, the abrasive dispensing group may comprise a detection device for a minimum quantity of abrasive available for the marking.

According to another particular aspect, there is described a process for marking surfaces by means of an apparatus as broadly described above. The process comprises an initial step of authorizing the marking, wherein there is provided the transmission of a marking request to a remote node and the consequent possible reception of an authorization if the request is approved. The authorization which is processed by the remote node may contain the marking data which are capable of being processed by the control group of the apparatus. On the basis of the marking data received, therefore, the control group can transmit the instructions necessary for carrying out the marking of a surface. The marking instructions particularly allow connection of the marking head of the apparatus to the surface to be marked, for example, by activating in terms of suction the suckers with which the marking head is provided. The actual marking involves controlling the opening and closing of the shut-off valve for the flow of air and abrasive and the movement of the marking nozzle in accordance with one or more paths defined by the marking data. At the end of the marking, the emission of air and abrasive is deactivated and it is therefore possible to disconnect the marking head from the surface, which is automatically marked in a clean and clear manner.

Brief description of the drawings

Additional features and advantages will be appreciated from the following detailed description of a preferred embodiment with reference to the appended drawings which are given by way of non-limiting example and in which: Figure 1 is a perspective view of an apparatus for marking surfaces by abrasion, incorporating aspects of the present invention;

Figure 2 is a perspective view of a marking head of the apparatus for marking surfaces of Figure 1;

Figure 3 is a perspective front view of a marking frame of the marking head of Figure 2;

Figure 4 is a perspective rear view of the marking frame of Figure 3, in which the rear portion of a marking group which can better be seen in Figures 10-12 can be seen;

Figure 5 is a perspective view of a dispensing tank for an abrasive product, forming part of the marking head of Figure 2;

Figure 6 is a longitudinal section of the dispensing tank in accordance with the line VI-VI of Figure 5;

Figure 7 is another perspective view of the dispensing tank of Figure 5, wherein the configuration of the internal pipes can be seen more clearly;

Figure 8 is a cross-section in accordance with the line

VIII-VIII of Figure 6;

Figure 9 is a cross-section in accordance with the line

IX-IX of Figure 6;

Figure 10 is a rear view of the marking group of the marking head;

Figure 11 is a longitudinal section of the marking group in accordance with the line XI-XI of Figure 10, in a working position being supported on a surface to be marked;

Figure 12 is an exploded view of the front head of the marking group of Figure 10;

Figure 13 is a section in accordance with the line XIII-

XIII of Figure 10; and

Figure 14 is a section in accordance with the line XIV-

XIV of Figure 10. Detailed description

Figure 1 is a perspective illustration of a preferred though non-limiting embodiment of an apparatus 1 for marking surfaces by abrasion. The surfaces may be plate glass panes and glass panes in general, for example, the side windows, the windscreen and the rear window of a motor vehicle, as well as the glass panes of the headlights, the rear-view mirrors and other portions and in any case other surfaces which can be made of glass, plate glass, plexiglass, fibreglass, plastics material, metal and the like.

The apparatus 1 comprises a base 2 which is provided, for example, with rollers for ease of movement, for example, around a vehicle for marking all the plate glass panes thereof. There is mounted on the base 2 a suction group 3 with a tank 4, in which there is received the abrasive which is used for the marking operation, together with the residues of the abraded surface. There is mounted above the suction group 4 a support structure 5, to which there is fixed an electric and/or electronic central control unit 6 with a general power supply switch 7. The apparatus 1 is supplied with electricity, for example, via an electric power supply cable 9. Alternatively or additionally, the apparatus 1 may also be supplied by means of electrical accumulators. The apparatus comprises an inlet for compressed air (not visible in the Figure) which is supplied by an external source and which is normally available in the workshops where the preparation of the vehicles and the marking thereof are carried out. An integrated pressure regulator is provided in the compressed air inlet in order to ensure dispensing which is as uniform as possible and therefore homogeneous marking. It is possible to provide a bottle of compressed air so as to make the apparatus 1 independent of the availability of an external source of compressed air. A suction pipe 10 places the suction group 3 in communication with a marking head 8, which can also be seen in Figure 2 according to a different perspective from that in Figure 1. The marking head 8 receives an electrical power supply from the central control unit 6 via electrical conductors which are preferably received in a tubing (not shown in the Figures) which runs parallel with the suction pipe 10. There is mounted on the marking head 8 an electronic control group 11 with a display device and data input device, for example, a touch-screen 12. When not in use, the marking head 8 can be placed on the support structure 5. In this position, the touch-screen 12 is orientated with an inclination with respect to the vertical which is ergonomic for use and display by an upright operator alongside the apparatus 1. In order to carry out the marking, the marking head 8 is taken by the support structure 5 by gripping it with two lateral handles, one of which is advantageously constituted by a dispensing tank 13 for abrasive which will be described in greater detail below. There are advantageously arranged on the other lateral handle 14 the controls for carrying out the marking operation which may comprise an activation push button 15 and a deactivation push-button 16 in addition to a potential vent push-button 17, the function of which will become clearer below. When the marking head 8 is gripped by an operator, the touch-screen 12 is orientated with a greater inclination with respect to the vertical than when the marking head is rested on the support structure 5 so as to be ergonomic for reading by the operator. A support bar 18, which is preferably of the telescope-like type, is available where necessary for supporting the marking head 8 when the operating conditions require an additional support or an extension. The support bar 18 which, when not in use, may remain engaged with the support structure 5, as can be seen in Figure 1, has a support foot 19 at an end thereof, while the other end is provided with a coupling 20, preferably a bayonet type coupling or more generally a coupling of the rapid-fit type, which can engage in a corresponding seat 21 which is formed in the marking head 8, as can be seen in Figure 2.

The marking head 8 is the electromechanical group which is specifically assigned to the marking of the surfaces by abrasion. The marking head 8 comprises a casing 22, for example, made from plastics material. The casing 22 can be constructed as two half-shells, a lower half-shell 23 and an upper half-shell 24. A casing 25 for receiving the electronic control group 11, which is closed by a cover 26, on which the touch-screen 12 is mounted, is integrated in the upper half shell 24. There is formed in the rear portion of the casing 22 an opening 28, to which there reaches the end of the suction pipe 10 which is fixed to the opening 28, for example, by means of a rapid-fit coupling, a bayonet type coupling, a thread or the like. At the opposite side to the opening 28, the marking head 8 is closed at the front by a marking frame 30.

Figures 3 and 4 illustrate in greater detail the marking frame 30 which has a peripheral frame 31 which is shaped to receive in a sealing manner the edge of the casing 22. There projects from the marking frame 30 a group of suckers 32 which are intended to fix the marking head 8 to the surface to be marked, as will be described in greater detail below. The suckers 32 are arranged in an inverted U-shaped configuration around a marking opening 33, which preferably but in a non-limiting manner has a rectangular shape with rounded corners and which defines the area inside which the marking of the surface can be carried out. Each sucker 32 has a sealing lip 34 which extends annularly around the end of a suction pipe 36 which runs axially inside a rod 38 which fixes the sucker 32 to the marking frame 30. In the example of the Figures, there are eight suckers 32 even if there may be provided a greater or smaller number of suckers in accordance with the dimensions of the marking frame 30, the dimensions of the suckers 32, the application requirements and so on. The suckers 32 are subdivided into a first group of suckers 32a and a second group of suckers 32b. The first group of suckers 32a is formed by the two suckers 32 which are arranged lowest on the marking frame 30, at the two sides of the marking opening 33. The second group of suckers 32b comprises all the other suckers 32. The suction pipes 36 of the suckers 32a of the first group are in communication with a first common collector pipe 40a which is provided in the marking frame 30. The suction pipes 36 of the suckers 32b of the second group are in turn in communication with a second common collector pipe 40b which is also provided in the marking frame 30. The two collector pipes 40a, 40b communicate with a vacuum pump 42, which is illustrated in Figure 4, with, for example, a selector 44 with manual or automatic actuation being interposed and providing for selectively carrying out a pressure reduction in the single first common collector pipe 40a or in both the common collector pipes 40a, 40b. In the first case, only the suckers of the first group 32a are placed under reduced pressure, in the case in which the surface to be marked is small and has a curvature which is particularly accentuated, as in the case of the headlight groups of the vehicles, while, in the second case, all the suckers 32 are placed under reduced pressure, both those of the first group 32a and those of the second group 32b. When all the suckers 32 are placed under reduced pressure, the suction effect is sufficient to maintain the marking head 8 fixed to the surface to be marked without the operator having to keep it gripped. This makes the marking process much less hard than the conventional system. If, however, only the first group of suckers 32a is actuated, the reduced number of suckers 32 placed under reduced pressure might not be sufficient to support the marking head 8 in the vertical position, and in this case it may be convenient to mount the support bar 18 on the marking head 8, as described above.

As can be seen in Figure 4, a marking group 52 is movably mounted on the marking frame 30. In the example illustrated, the marking group 52 is mounted on a carriage 54 which is movable with respect to the marking frame 30 in two mutually orthogonal directions X and Y, which are horizontal and vertical in Figure 4, respectively.

The carriage 54 is mounted so as to be able to slide in the vertical direction Y on a guide bar 56, which slides inside a hole at one side of the carriage 54, which is preferably provided with a bush for reducing friction. At the opposite side to the guide bar 56, the carriage 54 is connected with a threaded connection to a manoeuvring screw 58 which extends vertically and which is parallel with the guide bar 56. The manoeuvring screw 58 is controlled by a motor 60, for example, a stepping motor. The motor 60 has a drive shaft 62, on which there is keyed a drive pulley 64 which extends through a belt 66 which controls in terms of rotation a driven pulley (not visible in the Figures) which is fixed to the upper end of the manoeuvring screw 58. The motor 60 is mounted on a bracket 68 which projects from an upper support 70, to which there is fixed the upper end of the guide bar 56. The lower end of the guide bar 56 is in turn fixed to a lower support 72. There is also received in the lower support 72 a bush 74 which supports the lower end of the manoeuvring screw 58 in terms of rotation.

The carriage 54 is mounted so as to be movable on a transverse carriage 76. In particular, there are fixed to the transverse carriage 76 the upper support 70 and the lower support 72 which support the carriage 54 via the guide bar 56 and the manoeuvring screw 58. The transverse carriage 76 also transports the motor 60 which actuates the marking group 52 in the vertical direction Y. Via the transverse carriage 76, the marking group 52 can also be controlled in the horizontal direction X.

The transverse carriage 76 is mounted for sliding on two horizontal guide bars 78, 79 which are fixed at the ends to supports 80, 81, 82 which project from the marking frame 30. A manoeuvring screw 84 is connected to the transverse carriage 76 by means of a threaded connection and is supported at the sides by two bushes which are mounted on the supports 80, 82. The manoeuvring screw 84 is controlled by a motor 86, for example, a stepping motor, which is similar to the motor 60. The motor 86 has a drive shaft 88, on which there is keyed a drive pulley 90 which extends through a belt 92 which controls in terms of rotation a driven pulley 94 which is fixed to an end of the manoeuvring screw 84 which projects from the support 80. The motor 86 is fixed to the marking frame 30, for example, by means of a rod 87. The motors 60 and 86 are connected to the on-board electronic unit in known manner by means of electrical conductors (not illustrated) .

Figures 5 to 7 illustrate the dispensing tank 13 for the abrasive material which is preferably corundum and which is used to mark the surfaces by means of the apparatus 1. The dispensing tank 13 has a generally cylindrical form and comprises a cylindrical member 95 with such dimensions as to be able to be gripped conveniently by an operator. There is mounted at the lower end of the cylindrical member 95 a lower support block 96 which is fixed to the marking head 8 by means of screws 97. There is mounted at the upper end of the cylindrical member 95 an upper support block 98 which is fixed to the marking head 8 by means of screws 99. The cylindrical member 95 defines therein a cylindrical chamber 100. An upper cylindrical member 101 is fixed to the upper support block 98 for receiving a recharging cartridge for an abrasive product (not illustrated). The upper cylindrical member 101 is closed by a cap 102. At the bottom of the upper cylindrical member 101, a perforation tip 103 for the recharging cartridge projects centrally. There are formed around the tip 103 openings 104, through which the abrasive product which is contained in the recharging cartridge received in the upper cylindrical member 101 can descend into a collection chamber 105 which is formed in the upper support block 98 and from there into the cylindrical chamber 100.

The collection chamber 105 has a funnel-shaped form in order to convey the abrasive in a supply tube 106 which is arranged downstream of a detection device 107 which detects the presence or absence of a sufficient quantity of abrasive in the dispensing tank 13 and contributes to indicating the need for the recharging cartridge to be replaced in the upper cylindrical member 101, as will be better described below. The supply tube 106 extends vertically from the upper support block 98 as far as a given distance from the base of the cylindrical chamber 100. For example, as can be seen in the section of Figure 6, the supply tube 106 extends downwards over a length which is approximately equal to two-thirds of the length of the cylindrical chamber 100. The detection device 107 is integrated in the upper support block 98 so as to be located between the collection chamber 105 and the supply tube 106. As can also be seen in the section of Figure

8, the detection device 107 comprises a tube 108, through which the abrasive passes. The tube 108 is made of a transparent or semi-transparent material. Beside the tube 108, in diametrically opposite positions, there are arranged a light source 109, for example, an LED, and a photo sensitive element 110.

Two ventilation and pressurization nozzles 112 project from the bottom of the main chamber 100 of the tank 13. A supply pipe 113 for compressed air is formed in the lower support block 96, with an opening 114 for compressed air which projects from the lower support block 96. At the opposite side, the supply pipe 113 branches in order to connect in a parallel manner the two nozzles 112, as can be seen in Figure 7.

Inside the main chamber 100, there is mounted a system for dispensing abrasive which comprises a dispensing tube 115 which extends axially over the entire length of the main chamber 100. The dispensing tube 115 communicates in the lower portion with a dispensing pipe 116 which is formed in the lower support member 96 and which opens in a dispensing opening 117 which is arranged beside the opening 114 for the compressed air. As can also be seen in the section of Figure

9, the upper end 115a of the dispensing tube 115 is inserted in a slot 118 which is formed in the upper support block 98. The upper end 115a of the dispensing tube 115 is spaced apart from the bottom of the slot 118 which communicates with the main chamber 100 of the tank 13 through a series of peripheral channels 118a which are distributed radially around the dispensing tube 115. Near the bottom of the main chamber 100, on the wall of the dispensing tube 115, there is formed a small hole 119, through which the abrasive can be introduced inside the dispensing tube 115 in order to be transported into the dispensing tube 116 by the flow of compressed air which is introduced from the main chamber 100 into the dispensing tube 115 through the upper end 115a thereof. It is possible to provide a regulator for the pressure at the outlet in order to ensure the uniformity of dispensing of the air/abrasive admixture.

With reference now to Figures 10 and 11, the marking group 52 is configured to be supported, in an operating condition, on a surface R to be marked (see Figure 11). The marking group 52 comprises a generally tubular member 120 which is fixedly joined to or integral with the carriage 54. The tubular member 120 has a rear opening 122 which is connected to the suction group 3 of the apparatus 1 through the suction pipe 10 which is fixed to the marking head 8. In an axially centred position in the tubular member 120, there is constructed an axial pipe 124 for the supply of the abrasive material which is mixed with air and dispensed from the dispensing tank 13. As can better be seen in the section of Figure 13, the axial pipe 124 communicates with a tube 128 which opens in an opening 126. The opening 126 is connected with a tubing (not illustrated) to the dispensing opening 117 of the dispensing tank 13. There are constructed around the axial pipe 124 longitudinal channels 130 which place the rear opening 122 in communication with a head 132 of the marking group 52 which, during the marking, is supported on the surface R to be marked. In the head 132, the axial pipe 124 extends into a marking nozzle 134 which is mounted to be removable so as to be readily able to be replaced after a given number of activations of the apparatus 1 in order to ensure continuity in the precision of the marking. The marking nozzle 134 is in fact one of the components most subjected to wear in respect of the entire apparatus 1 and one of the most important components for producing a marking of quality, with clean contours without any burrs or halos. In order to control the state of wear of the marking nozzle 134, it is possible to use a dedicated sensor which verifies, for example, the working pressure.

The marking nozzle 134 projects from a front opening 136 of the tubular member 120 in which there is mounted a support member 138 which is urged forwards by a spring 140. In this manner, the support member 138 can resiliently return into the front opening 136 by a given amount so as also to adapt to the formation of the surface R in the case of marked curvature thereof, such as, for example, in the case of the headlights of the vehicles. As can also be seen in the exploded depiction of Figure 12, there are mounted on the support member 138 at the front a number of bearings 142, preferably three of them, which are arranged radially around the nozzle 134. The bearings are supported by a support disc 144 which is fixed to the end of the support member 138. The bearings 142 are made from relatively soft material, for example, a silicone rubber, in order to be supported gently on the surface R by adapting to the formation thereof which often has a given curvature. The bearings 142 are mounted to be slightly self-aligning on the support disc 144 in order to better adapt to the surface of the surface R to be marked. The support disc 144 has openings 146 which communicate with the longitudinal suction channels 130 between two adjacent bearings 142. In this manner, the abrasive material which is discharged from the marking nozzle 134 and which strikes the surface R in order to produce at that location the marking is immediately drawn in together with the surface powder which is removed and conveyed into the suction group 3 of the apparatus 1 for subsequent disposal thereof. In this manner, the dispersion into the surrounding environment of the abrasive material and the surface particles removed by the marking is prevented to a maximum extent.

Virtually immediately upstream of the nozzle 134, there is mounted on the axial pipe 124 a shut-off valve 148 which upon command provides for the axial pipe 124 to be closed, preventing the supply of abrasive material to the nozzle 134. The shut-off valve 148 is of the type with a resilient sleeve and particularly comprises a compressible sleeve 150. The external surface of the sleeve 150 defines a wall of a control chamber 152, in which a pipe 154 which is connected to a pneumatic control circuit by means of an opening 156 opens. When the control chamber 152 is pressurized by supplying compressed air in the pipe 154, the sleeve becomes compressed, closing the axial passage thereof and therefore interrupting the continuity of the axial pipe 124. Conversely, by removing the pressure from the control chamber 152, the resilience of the sleeve 150 extends it radially, opening the axial passage thereof and restoring the continuity of the axial pipe 124.

As can be seen in Figure 14, in the region of the rear opening 122 of the marking group 52, there is constructed a small U-shaped pipe 158 with an external opening 160, through which it is possible to detect, via a sensor of known type, the presence or absence of the reduced pressure which is generated when the suction group 3 is active and the head 132 is supported with good sealing against the surface R to be marked.

The marking process comprises three main steps: a preliminary authorization step, an actual marking step which is carried out by the apparatus 1 and a data recovery step.

In the authorization step, there is submitted to an authorizing person a request to carry out the marking of one or more surfaces, for example, the plate glass panes of a motor vehicle. The authorization request for the marking is advantageously submitted via a computer or a smart phone which are connected to the internet. In this step, the registration of the identification data of the vehicle to be marked may be carried out, for example, the data item of the frame number and/or the number plate which can also comprise a facilitated input by means of optical recognition methods which automate the data input operations. Following the positive result of the verifications regarding the data input by the applicant, the authorizing person may grant authorization for the marking by sending the marking data to the apparatus 1. To this end, the apparatus 1 may include, for example, a wireless connection module (WiFi, GSM,

Bluetooth, etc.) to the internet. The data can also be input by means of USB and, in that case, the data which are managed during the transfer are preferably encrypted with a dedicated algorithm in order to then be decrypted by the firmware of the apparatus 1. With the transmission of the marking data, for example, the frame number, number plate number or a unique code which is generated by the authorizing person, the apparatus 1 is also enabled to be activated by an operator.

When the apparatus 1 has received the marking data and is enabled, it can indicate the activation standby state thereof by an operator with a signal or an indication on a monitor or control panel, for example, the touch-screen 12. The apparatus 1 can further show by video, for example, on the touch-screen 12, the list of the marking authorizations recovered from the source which may also be more than one, indicating for each, for example, the number plate, frame, mark and model of the vehicle. The operator can select, for example, via the touch-screen 12 itself or via a dedicated application on a smart phone, the vehicle which is desired or the specific code to be marked among the ones available and authorized.

When the operator has carried out the selections, there can be shown on video a stylized shape of the car, on which it is indicated where to position the marking head 8 in order to be able to carry out the first marking. Therefore, the operator holds the marking head 8, supports it in the position indicated on the surface R to be marked, for example, the plate glass of a vehicle, and activates the push-button 15 for activating the marking.

The activation of the push-button 15 activates the suction group 3. If the marking head 8 is correctly supported on the surface R to be marked, the sensor associated with the U- shaped pipe 158 in the marking group provides a first permission signal. The activation of the push-button 15 further activates the vacuum pump 42 for the adhesion of the suckers 32 to the surface R to be marked. In accordance with the type of surface to be marked, there are activated all the suckers 32 or, if the surface to be marked is small, as in the case of headlights or optical groups of a vehicle, only the suckers of the first group 32a are activated. As indicated above, the selection of the suckers to be activated can be carried out manually by the operator or automatically by the equipment 1. When all the suckers 32 have been activated, the suction applied to the surface R to be marked is sufficient to retain in position the marking head 8 without the operator having to support it. In any case, the operator can make use of the support bar 18 as an auxiliary member to support the marking head 8, especially in the case in which only the suckers of the first group 32a are activated. The correct adhesion of the marking head 8 can be detected by sensors which are associated with the suckers 32 and/or the circuit of the vacuum pump 42, which provide another permission signal for the marking.

For the activation of the marking process, it is necessary for the dispensing tank 13 to contain a sufficient quantity of abrasive. It is noted in fact that an excessively low level of abrasive in the dispensing tank 13 brings about a marking of inferior quality. For this reason, it is necessary to have an additional permission signal which depends on the detection device 107 which is mounted in the dispensing tank 13 which operates according to the following principle.

When a recharging cartridge of abrasive is inserted in the upper cylindrical member 101, a pressure downwards brings about the piercing of the base thereof by the tip 103, with a resultant outpouring of the abrasive contained in the recharging cartridge in the collection chamber 105 through the openings 104 which are provided around the tip 103. From the collection chamber 105, the abrasive is conveyed in the tube 108 of the detection device 107 and from there in the supply tube 106. The abrasive flows into the cylindrical chamber 100 until the level of the abrasive reaches the lower opening of the supply tube 106, clogging it and thereby interrupting the further supply of abrasive into the cylindrical chamber 100. If the quantity of abrasive is sufficient to occupy all the supply tube 106 and the tube 108 of the detection device 107, it is opaque to light. In this case, the photo-sensitive element 110 does not detect the light emitted by the light source 109. This condition is interpreted by the electronic circuit to which the photo sensitive element 110 is connected as an indication that the level of abrasive is regular for carrying out subsequent markings. The abrasive in the cylindrical chamber 105 which is used gradually for the markings is replaced by new abrasive which is drawn from the collection chamber 105 through the supply tube 106. When abrasive is not present in the collection chamber 105, an additional drawing of abrasive for replacing the abrasive used for the markings causes the tube 108 also to be emptied, which thereby allows the light emitted by the light source 109 to pass, no longer being obstructed by the presence of the abrasive. In this case, the photo-sensitive element 110 detects the light of the light source 109 through the tube 108 and sends a signal to the on board electronic unit, which provides for processing it in order to indicate that a minimum permitted level of reserve of the abrasive product has been reached, indicating the need to replace the recharging cartridge in the upper cylindrical member 101.

Finally, the activation of the push-button 15 also brings about the supply of compressed air to the dispensing tank 13 which is pressurized by means of compressed air which is conveyed to the nozzles 112 on the bottom of the cylindrical chamber 100. The abrasive material is placed in vortical movement, being introduced into the dispensing tube 115 via the small hole 119. The air in the dispensing tube 115 is placed under pressure because it is in communication with the cylindrical chamber 100 via the peripheral channels 118a of the slot 118. In this initial condition, the shut-off valve 148 immediately upstream of the nozzle 134 in the marking group 52 is closed by the control pressure present in the pipe 154 which compresses the sleeve 150. The motors 60, 86 are controlled in order to bring the marking group 52 which is mounted on the carriage 54 into a zero position of the movement axes X and Y.

If all the conditions are complied with, that is to say, if the on-board electronic unit of the apparatus 1 receives the various permissions described above, the actual marking operation has started. On the touch-screen 12, the information that the process is under way appears. At the start of the marking, the on-board electronic unit of the apparatus 1 provides for moving the marking group 52 along the axes X and Y by controlling the respective motors 86 and 60 and at the same time by opening and closing the sleeve type valve 148 in order to allow or prevent the jet of air and abrasive against the surface R in the position and along the path of the marking nozzle 134, respectively.

Once the marking of the surface R is ended, the apparatus 1 stops the pressurization in the dispensing tank 13 and brings the marking group 52 back into a zero position. However, the vacuum pump 42 is kept active in order to ensure that the suckers 32 remain bonded to the surface R already marked. This is because the marking can generally be carried out without the operator having to maintain the grip on the marking head 8. When the operator is ready to remove the marking head 8, the operator can press the deactivation push button 16 which stops the vacuum pump 42. With the vent push button 17, the pneumatic circuit of the suckers 32 is then discharged in order to ensure the complete discharge of the reduced pressure and therefore the detachment of the marking head 8 from the marked surface R. In order to discharge the pneumatic circuit, it is also possible to replace the vent push-button 17 with an automatic device which is activated by the deactivation push-button 16. In the case of marking a plurality of surfaces of the same vehicle, for example, of all the plate glass panes thereof, there is indicated on the touch-screen 12 the position of the subsequent plate glass pane on the vehicle. Therefore, the operator positions the marking head 8 in the desired position on the subsequent plate glass pane and again activates the marking process as indicated above by actuating the activation push-button 15. This step is repeated for all the plate glass panes and the surfaces of the vehicle which are intended to be marked, such as, for example, headlights, spoilers, roof, mirrors, etc.

Naturally, the principle of the invention remaining the same, the forms of embodiment and details of construction may be varied widely with respect to those described and illustrated, without thereby departing from the scope of the present invention.