WO2023158325A2

WO2023158325A2 - Nozzle changer for laser processing machine

Info

Publication number: WO2023158325A2
Application number: PCT/PL2022/050067
Authority: WO
Inventors: Janusz Marcin Ejma EAGLE POWER; Jakub JACUNIAK
Original assignee: Eagle Power Janusz Marcin Ejma
Priority date: 2022-02-17
Filing date: 2022-10-18
Publication date: 2023-08-24
Also published as: PL440404A1

Description

Nozzle changer for laser processing machine

The invention is an automatic nozzle changer for a laser processing machine. This kind of device is involved in installing and/or removing nozzles on a processing head of a laser processing machine with a centring system, where the nozzle changer is equipped with several nozzle holders. The invention can be used as a component of a new processing machine and as an adapter for the existing cutting machines in operation.

When the material from the cutting head is exposed to the laser beam with high coherence and energy density, the resulting vaporisation of the material is accompanied by the emission of vapours, dust, splinters and slag accumulates on the nozzle. Contamination of the nozzle decreases the quality and efficiency of the processing, in which case it is necessary to replace and clean the nozzle before reusing it in the cutting process. For this purpose, automatic nozzle replacement and cleaning units are used on modem cutting machines, restoring the nominal calibration. The units are equipped with magazines for removing and storing contaminated nozzles and for subsequent cleaning before use, as well as for changing the type of nozzle when changing materials, as different nozzles are used for different thicknesses and types of materials. Automating changeover operations increases productivity, improves the quality of the cutting process and enables the cutter to work without having to replace elements manually, even at night and at weekends. The device interfaces with the machine control systems and allows maintenance-free operation of the machine according to the set production plan. Patent description EP3112074B1 provides information on a nozzle changer for mounting nozzles and/or for removing nozzles from a nozzle holding device which is formed, in particular, on the processing head of a laser processing machine. The changer includes a nozzle magazine with a closed path for storing several nozzle retaining units, where the unconnected nozzle retaining units forming a push chain along the closed path, and a positioning drive for moving the nozzle retaining units along the closed path to move one of the nozzle retaining units into a transfer position along the path and/or to remove a nozzle from the nozzle retaining unit.

Based on the EP2078585B1 patent description, there is a known mechanical device for mounting and/or dismounting a laser nozzle on a nozzle receiving element of a laser machine, equipped with a nozzle magazine which has at least one nozzle holding element on the nozzle holding element bracket, and has a positioning drive by which the nozzle holding element bracket can be moved together with the nozzle holding element, thus performing a positioning movement, and the nozzle holding element can thus be moved into a mounting/dismounting position. The positioning drive shares a common drive motor with the assembly/disassembly drive. A clutch Is provided between the drive motor on one side and the nozzle retaining element carrier on the other side, which can be switched with a switching device.

On the other hand, as for the CN210633134 U utility model description, there is a known automatic nozzle changing device for a laser cutting machine. The servomotor and bottom plate are attached to the support frame, the cover plate is placed on the vertical housing plate, and the rotating shaft is driven by the servomotor to achieve synchronous rotation and is placed rotatably on the bottom plate and cover plate through bearings. A groove is formed in the rotating shaft and the rotating central shaft, it can be lifted up and down relative to the rotating shaft and rotates synchronously with the rotating shaft. The rotating central shaft passes through the cover and is fited with an adapted nozzle bowl which rotates synchronously, whereas the nozzle is placed in the nozzle bowl and rotates synchronously with the nozzle bowl. Based on the EP1602439B1 patent description, there is a known laser machine equipped with a magazine for automatic nozzle changing, set in the automatic tool changing position, including a dustproof cover which covers the upper part of the nozzle changing magazine for laser processing tools and opens up only when the nozzle of the laser processing tool is changed.

From the description of the EP2589458B1 European patent, there is a known nozzle changer for mounting and/or removing nozzles on the machining head of a laser processing machine, including a multi-cavity magazine with an externally mounted nozzle holder. The nozzle holder extends in the nozzle removal direction to the nozzle removal opening, wherein the nozzle holder includes at least two, shifted from each other incrementally, nozzle storage locations to store a respective nozzle, whereas the nozzle storage locations have a circumferential contour to receive the nozzle in a rotationally secured manner. The incremental shifting of nozzle storage locations enables the use of nozzles of different sizes and shapes, with the effect of making process automation more flexible.

All known designs of changers show problematic solutions for the replacement of nozzle holders from the sockets, which is particularly important with high frequency of wear among these elements. The current solutions also do not solve the problem of complex calibration and centring of the laser beam system with respect to the centre of the replaced nozzle in the cutting machine head.

The essence of the invention is a nozzle changer for installing and/or removing nozzles from a nozzle fixing device which is formed in particular on a machining head of a laser processing machine, equipped with a multi-cavity magazine with a nozzle holder embedded in the cavity extending in the direction of nozzle removal to a nozzle removal opening, wherein the nozzle holder comprises a storage space for storing the nozzle in a rotationally secured manner, and the nozzle sockets are rotated with a belt driven by a servomotor and the changer housing comprises an opening cover, characterised in that the nozzle holder is seated inside the shaft rotating the nozzle socket, supported by a spring. Through the internal thread on the lower part of the nozzle holder sleeve, it Is connected to a central fitted screw which is inserted into the rotating shaft from below. The internal seating of the nozzle holder in the rotating shaft makes the replacement of the holder quicker and easier, it can be done simply by unscrewing the fitted screw from below. As the nozzle holder is a consumable part, replacing them is important in the life cycle of the machine. The nozzle holder is interlocked with the pulley through a prismatic keyway. In order to reduce the wear of the double-toothed belt, by preventing the pulley Z-axis throw, a pulley with another prismatic keyway is interlocked with the rotating shaft, which is press-fitted in the main plate through the use of socket bearings of different diameters, the upper socket bearing being of greater diameter than the lower socket bearing. With different diameters of the socket bearings, it is possible to achieve a more rigid connection by tightening the upper bearing resting on the edge of the flange. The motherboard is mounted on feet, The nozzle changer incorporates a centring system equipped with three centring rollers evenly spaced around the circumference of the wheel and mounted in bearings on pins with a horizontal axis of rotation, tangential to the wheel. One of the centring rollers is an adjusting roller, and the position of its pin relative to the wheel centre is adjusted on the intermediate plate. An additional measuring element in the centring system is a vision sensor, suspended below the intermediate plate on a levelling system, which the task of determining the centre of the beam in the nozzle. The entire system is placed in a changer housing with a housing flap raised on the cylinders, which works with an opening sensor and a closing sensor.

The most suitable type of drive belt is the double-toothed belt.

Ideally, the ends of the pins are also fastened to an intermediate plate mounted on at least three intermediate blocks.

The best option for the vision sensor is a camera.

Also, the most suitable choice for the levelling arrangement of the vision sensor is also based on three sets of levelling screws.

It is also advantageous if the levelling system of the changer includes foot taper screws connecting the main plate to the paw and locking bolts. it is also advantageous to have cleaning brushes and a calibration point on the main board, on an arm that extends beyond the changer housing. to addition, it is advantageous if the calibration point is groove milled in the main plate of the nozzle changer.

The automatic nozzle changer according to the invention enables the automatic nozzle changes without having to do it manually. The device interfaces with the machine control systems and allows maintenance-free operation of the machine according to the set production plan. Installed in the laser cutting machine on the front connector, at the front of the machine, it makes it easier for the operator to replenish the nozzle magazine. The laser head has a distance sensor where the nozzle is mounted, with different nozzles being used for different thicknesses and types of material.

The automatic nozzle changer is a device which can only perform its function when working together with a machine such as a laser cutting machine. It is, therefore, clear that in order to explain the structural connections and the principle of operation, it is necessary to use the components that are part of this machine, such as the head, the electro-valves, parts of the supporting structure, as well as the software and the necessary components for its application, such as the controller, the PLC card and others. With the current state of the art, it will be obvious to an expert that most of these elements, and the elements described as the ones creating the object of the invention, can be used interchangeably with others performing similar functions. Therefore, those enumerated as examples do not limit the scope of protection of the invention.

The more detailed description of the invention is included in the execution example and illustrated in the figure, where fig. 1 presents the changer in the mode adapted for operation with the flap open, fig. 2 presents the changer as in fig. 1 , in an exploded view with visible elements of the magazine, drive system and centring system, fig. 3 presents the changer in a front view, in longitudinal section. There is detail A as shown in fig. 2 with the two rollers of the centring system and the adjusting roller attachment visible, fig. 4 presents a fragment of the automatic changer in the part covering the centring system in axonometrlc view, fig. 5 shows a fragment of the automatic changer in the part covering the centring system in top view with the B-B section marked, while fig. 6 is the centring system as per fig. 5 in section B-B, fig. 7 presents the magazine socket of the nozzle changer, while fig. 8 presents the magazine socket of the nozzle changer in an exploded view; fig. 9 presents the magazine socket of the nozzle changer in section A-A, white fig. 10 presents the magazine socket of the nozzle changer with marked cross-section A-A, fig. 11 presents a cutting head, which is not an object of the invention, topped with a distance sensor with visible inductive centring sensors, and fig.12 is a block diagram of the implementation of a nozzle change with centring, during the laser cutting process.

List of markings used in the figures and text: 100 - nozzle changer, 101 - magazine, 102 - nozzle socket, 103 - nozzle holder, 104 - rotating shaft, 105 - seat bearing, 106 - spring, 107 - pressure ring, 108 - fitted screw, 109 - pressure flange, 110 - prismatic keyway, 111 - washer, 112 - selfdocking nut, 113 - pulley, 114 - servomotor, 115 - double-toothed belt, 116 - belt tensioner, 117 » main plate, 118 - mounting foot, 119 - foot taper screw, 120 - locking screw, 121 - nozzle, 122 - spacer, 200 - centring system, 201 - centring roller, 202 - roller pin, 203 - intermediate plate, 204 - intermediate block, 205 - vision sensor, 300 - changer housing, 301 - housing flap, 302 - pneumatic solenoid valve, 303 - flap actuator, 304 - closing sensor, 305 - opening sensor, 307 - cleaning brush, 308 - calibration point, 400 - laser cutting machine head, 401 - distance sensor, 402 - inductive centring sensor.

Example: The automatic nozzle changer is built on the main board 117, where the individual parts of the device are distributed. The main plate 117, which is the load- bearing base, is supported by three feet 118, acting as fasteners to the load- bearing element of the machine, which is the front connector. The three mounting feet 118, nozzle changer 100 are fixed to the connector with 6 screws. The main plate 117 itself is attached to the mounting feet 118 with 6 foot taper screws 119. The main plate 117 has a levelling function for mounting feet 118, thanks to additional arrangement built upon locking screws 120, two locking screws 121 for each foot 118. The bolt arrangement is designed to enable levelling of the changer on the connector during installation. By releasing the foot taper screws 119 with which the main plate 117 is bolted to the mounting feet 118 and tightening the locking screws 120, and then tightening the foot taper screws 119 between the mounting feet 118 and the main plate 117, with the additional screw counter, the nozzle changer 100 is levelled to the required level.

There is a magazine 101 with thirty-six nozzle sockets 102, which are secured to the main plate 117 with clamping flanges 109, bolted to the main platel 17 by four screws, in addition, each nozzle socket 102 is press-fitted to the main plate 117with two socket bail bearings 105 of different diameters, which are, in turn, fitted relative to the main plate 117. The seat bearings 105 are separated from each other with a spacer 122. The upper seat bearing 105 is placed on a larger diameter than the lower seat bearing 105. In the event of wear or deterioration of the components, the different diameters of the seat bearings 105 facilitate the assembly and disassembly of the nozzle socket 102 and since they are seated on the shelves and not press-fitted on the sidewall, hence basing on a single plane only. Furthermore, such a solution does not require special equipment to remove the press-fitted nozzle socket 102. Furthermore, the use of two seat bearings 105 makes the structure more stiff, and protects the nozzle seat 102 from bending, caused by the tensions generated by the double-toothed belt 115.

From above, the nozzle socket 102 provides a nozzle holder 103 widening in the direction of nozzle removal 121. The internal shape of the nozzle holder 103 is adapted to the nozzle 121 and enables easy and hassle-free replacement The point of adding chamfers is to lock the nozzle in position and prevent rotation in the socket. The technical apertures are used to purge the nozzle holder 103 of fine dirt and swarf using technical gases from the laser cutting machine head 400.

The nozzle holder 103 is fixed inside the rotating shaft 104 and rests against the spring 106. By means of an internal thread in the lower part of the sleeve of the nozzle holder 103, it is connected to the fitted screw 108 which is centrally seated from below in the rotating shaft 104. The nozzle socket 102 moves along the Z- axis, and rotates around its own axis. The downward movement along the Z-axis occurs during the replacement process of the nozzle 121. The laser cutting machine head 400 moves to the position of the respective nozzle socket 102 and, when the nozzle 121 is screwed in, it lowers together with the nozzle socket 102, It is returned to its position by the expansion of the tensioned spring 106 until the initial position is reached. In the nozzle holder 103, as in the case of the pulley 113, there is an opening for the parallel key 110, and this prismatic keyway 110 is intended to prevent rotation of the nozzle holder 103 and to position it relative to the rotating shaft 104. Movement in the Z-axis of the nozzle holder 103 is blocked by a fitted screw 108, which at the same time acts as a locking element for Z-axis movement of the entire nozzle socket 102, It allows the nozzle socket 102 to remain aligned with the beam axis.

Each of the thirty-six sockets of the nozzle 102, is installed on the main plate 117, is driven by one double toothed belt 115, The drive is transmitted from a double toothed belt 115 to the nozzle socket 102 and further, to further pulleys 113 of the other nozzle sockets 102, via the pulley 113 on the nozzle socket 102. Servomotor

114, which is fixed to the main plate 117 from below by means of four screws, transmits the drive through a diverted pulley and is the driving element of pulleys 113. The pulley 113, on its inner circumference, has a groove for a prismatic keyway 110 to prevent the pulley 113 from rotating on the rotating shaft 104, as well as to hold the pulley 113 in a predetermined position, compensating for manufacturing inaccuracies, thereby extending the life of the double toothed belt

115. A pressure ring 107 was used for locking the pulley in Z-axis movement. In order for the double toothed belt 115 to function properly, its proper tension is required, therefore the drive system of the magazine 101 is equipped with a belt tensioner 116, mounted on the drive assembly in an elongated socket and tensioned with a screw.

The nozzle socket 102 has been secured from falling out of socket bearings 105, from below, with a washer 111 and a self-locking nut 112.

The nozzle changer 100, according to the invention, comprises a centring system 200 with three centring rollers 201 , arranged at 120° intervals, which act as a guide for the centring module on the laser cutting machine head 400. The centring module on the laser cutter head 400, when it rests against centring rollers 201 , can be positioned due to the rigid holding of the centring rollers 201 and the adequate control enabled by laser cutter software. Centring rollers 201 are pressed onto the bearings which are mounted on pins 202. The pins 202, in turn, are seated on an intermediate plate 203 which is fixed on intermediate blocks 204 to the main plate 117. An additional measurement element in the centring system is a vision sensor 205, which is designed to determine the centre of the beam in the nozzle 121. The vision sensor 205 is suspended below the intermediate plate 203, on a levelling arrangement supported on three sets of levelling screws 206. With the use of three levelling screws 206, the vision sensor 205 can be levelled to the appropriate calibration value, which is reached before the cutting process begins. Centring of the head by means of the vision sensor 205 consists in sending an output signal from the laser beam, which is transmitted to the vision sensor 205, from which, via the PLC card, it is processed into a signal fed to the X,Y axis motors.

There are two blocks mounted on the main plate 117 to secure the changer housing 300. Bolted to these blocks are the wails holding the opening mechanism of the housing flap 301. The housing flap 301 opens by means of three pneumatic flap actuators 303 fixed to it. The housing flap 301 is suspended on pins which maintain the axis of rotation of the housing flap 301 during opening. The housing flap 301 is also equipped with hydraulic buffers which damp vibrations when the nozzle changer 100 opens and closes. Information on the closing and opening of the housing flap 301 is provided by inductive sensors: the opening sensor 305 and the closing sensor 304.

A component that is also located on the main plate 117, on an arm extending beyond the changer housing 300, is the cleaning brushes 307. The cleaning brushes 307 ensure that nozzle 121 is properly cleaned during the cutting process. The calibration point 308, which is a designated location on the main board 117, in the part that is the cleaning brush 307 attachment arm, is responsible for properly calibrating the distance sensor 401 on the head, which is not the subject matter of the invention. The calibration point 308 is a several millimetre deep groove milled from the bottom into the main plate 117 of the nozzle changer 100. The laser cutter head 400 approaches the calibration point 308, where data is checked for inductive centring sensors 402 of the distance sensor 401, with which the laser cutting machine head 400 is equipped.

How to change nozzles:

During the cutting process, the machine registers one of the signals: -system for counting holes pierced in the material -number of nozzle changes -change of the material being cut.

When it is necessary to change the nozzle 121 , the machine interrupts the current cutting programme, The control computer, by a signal via the PLC card, opens the opening solenoid valve 302 of the changer housing 300 of the automatic nozzle changer (100), exposing the changer magazine 101 and the centring system (200). The flap opening sensor 305 confirms that the housing flap 301 has been opened. Subsequently, motors of the X, Y axes of the laser cutting machine head 400, which are part of the laser processing machine and are not the subject matter of the invention, move the laser cutting machine head 400 to a position above the changer magazine 101 that corresponds to the position of the respective nozzle 121 to be changed. The Z-axis motor moves the laser cutting machine head 400 to the nozzle removing position 119, while the servomotor 114, by a signal from the PLC card, the sensor system not being the subject mater of the invention, verifies the position of the head along the X,Y, Z axes, confirms the approach to the preset nozzle replacement position, receives information that the Z-axis is in the correct position and is actuated to unscrew the nozzle 121 .

After the unscrew cycle, the laser cuting machine head 400 is moved to the closing sensor 304, which at this point is also the calibration point of the capacitive distance sensor 401, thus to the position of the nozzle 121 in the Z axis. On this sensor, it verifies that the nozzle 121 is in the distance sensor 401 . If it is confirmed that it is not present, the laser cutting machine head 400 drives to the predefined nozzle socket 102 with a new nozzle 121 to be picked up, the axis slides to the picking position, the Z-axis encoder confirms that the Z-axis is in the correct position, the servomotor 114 gets the starting signal, tightens the nozzle 121 in the distance sensor 401, measuring the tightening torque, If the torque is reached, the servomotor 114 stops, the laser cutting machine head 400 is again moved to the flap closing sensor 304 which again acts as a nozzle position sensor 121 to verify that the nozzle 121 has been properly picked up. If the nozzle position sensor sends the signal with a confirmation, the laser cutting machine head 400 moves to the last preset position in the processing area, then the signal that the position has been reached goes to the control computer, which sends a signal to the pneumatic solenoid valve 302 that the housing flap 301 is closed.

The positioning of the two inductive centring sensors 402 on the laser cutting head 400 makes it possible to measure the position and distance (shifting relative to the X, Y axis). The closing sensor 304, on the other hand, is a binary device and is designed to detect and communicate whether a metal object is nearby.

The position of the head centring system (not an object of the invention) is set using the centring system 200 included in the nozzle changer 100, according to the invention, and the position corrections are determined based on the image from the vision sensor 205. The position of the centring module and thus the distance sensor 401 is set based on the reading of the inductive centring sensors 402, The point with respect to which the position of the inductive centring sensors 402 is analysed is determined by the "centre in the centre" test - tape shot, the fired beam has to be in the very centre of the nozzle. This is the reference point for the centring system 200.

Alternatively, the centring process can be implemented without the vision sensor 205, in which case the position of the inductive centring sensors 402 is taken into account by the machine software and the position of the laser beam is determined.

Claims

Patent claim 1. A nozzle changer for installing and/or removing nozzles from a nozzle fixing device which is formed in particular on the machining head of a laser processing machine, comprising a multi-cavity magazine with a nozzle holder embedded in the cavity extending in the nozzle removal direction to a nozzle removal opening, wherein the nozzle holder has a storage space for storing the nozzle in a manner that prevents rotation, the nozzle sockets are rotated with a belt driven by a servomotor and the changer housing has an opening cover, characterised in that the nozzle holder (103) is placed inside the rotating shaft (104) of the nozzle socket (102), supported by a spring (106), and connected via an internal thread, located in the tower part of the sleeve of the nozzle holder (103), is connected to a fitted screw (108) centrally located in the rotating shaft (104) at the bottom, and is connected to a pulley (113) with a prismatic keyway (110), while the pulley (113) is connected via another prismatic keyway (110) to the rotating shaft (104), is interlocked with the rotating shaft (104), which is interference fit in the main plate (117) by means of socket bearings (105) of different diameters, the upper socket bearing (105) being of larger diameter than the lower socket bearing (105), the socket bearings (105) being interference fit relative to the main plate (117) and secured by means of pressure flanges (109) screwed to the main plate (117), which is mounted on feet (118), where the nozzle changer (100) includes a centring system (200) provided with three centring rollers (201) equally distributed around the circumference of the wheel and bearing on pins (202), with a horizontal axis of rotation tangential to this wheel, whereby one of the centring rollers (201) is an adjusting roller and the position of Its pin (202) relative to the centre of the wheel is adjusted on an intermediate plate (203), while below the intermediate plate (203) a levelling system below the intermediate plate (203), on a levelling system, a vision sensor (205) is suspended, while the whole is contained in a changer housing (300) with a housing flap (301) raised on cylinders (303), cooperating with an opening sensor (305) and a closing sensor (304).

2. The nozzle changer according to claim no. 1 , characterised in that the transmission belt is a double-toothed belt (115).

3. The nozzle changer according to claim no. 1,characterised in that the ends of the pins (202) are fixed to an intermediate plate (203), seated on at least three intermediate blocks (204).

4. The nozzle changer according to claim no. 1, characterised in that when the video sensor (205) is a camera.

5. The nozzle changer according to claim no. 1, characterised in that the levelling arrangement of the vision sensor (205) is based on three sets of levelling screws (206).

6. The nozzle changer according to claim no. 1, characterised in that the changer levelling arrangement provides foot taper screws (119) connecting the main plate (117) to the foot (118) and locking bolts (120).

7. The nozzle changer according to claim no. 1 , characterised in that on the main board (117), on an arm extending beyond the changer housing (300), there are cleaning brushes (307) and a calibration point (308),

8. The nozzle changer according to claim no. 7, characterised in that the calibration point (308) is groove milled in the main plate (117) of the nozzle changer (100).