EP0084505A2 - Process for controlling a glass pane edge grinding machine, and devices for carrying out this process - Google Patents

Abstract

The invention relates to the automatic control of a machine along the edges of an object such as a glass sheet, with a view to working these edges or regions of the surface of the object which can be identified with respect to the edges. The invention provides a method for controlling such a machine in which the position of the working tool mounted on a mobile carriage in two perpendicular directions is determined by a program, this program being established using a member probing the edges of the object to be worked, articulated on the carriage which carries the working tool, mounted at the front of this carriage, and which records the coordinates of the points of the path which the working tool will have to follow. The values thus obtained are transformed into signals, stored in a shift register and then used to control the drive motors of the carriage carrying the work tool. The invention is applicable to the control of a machine for grinding the edges of glass sheets.

Description

The present invention relates to the automatic control of a machine for working around a sheet of glass, in particular an edge grinding machine, a machine whose working head carrying the working tool is mounted on a carriage which moves in two rectangular X and Y directions to follow the outline of the glass sheet immobilized on a support.

A machine of this type for grinding the edges of glass sheets is described for example in document DE-OS 2 856 519. In this known embodiment, the motors for driving the carriage in the directions X and Y are controlled by a device digital control system in which the information on the carriage path is recorded on a perforated tape. In another machine for grinding the edges of glass sheets, of the aforementioned type, described in document DE-AS 1 950 819, the carriage is guided by a feeler along a template whose shape corresponds to that of the sheet of glass to work.

In known machines intended to grind the edges of a glass sheet, the path of the grinding tool is determined by the preset program or by the rigid template. This has the consequence that these machines are designed to work glass sheets having a constant shape and size, and when you want to work with different glass sheets, you have to change the program or the template.

In addition, in both cases, the glass sheet to be worked must be positioned with respect to the machine, very precisely, which constitutes a long operation and requires sophisticated equipment.

The object of the present invention is to control a machine for working the edges of a glass sheet, in particular a machine for grinding the edges, for which no preset program is necessary. This machine is guided by the glass sheet itself, whatever its shape, without any particular intervention when glass sheets of different shapes follow one another, and without any precise positioning of the glass.

According to the invention this is achieved by the fact that the program for controlling the path is determined, for a defined distance, in front of the working tool, by means of a feeler mounted on the carriage carrying the working tool, in front of said tool, and palpating the edges of the glass sheet, the X and Y coordinates of the points of the edge identified by the probe being entered in the shift register of a memory and being used after a certain time shift to control the motors positioning the carriage in the X and Y directions.

Unlike the known devices, the device of the invention requires neither a preset program specific to each form of glazing, nor a template, the path program is determined by the tool carriage itself which explores the contour of the worksheet.

According to the invention, only a relatively short part of the path located immediately before the grinding tool is explored and the path information of the grinding tool for this part is entered into a memory from which they are extracted so continues after a lapse of tenps following their recording, which corresponds to the tenps of travel by the carriage of the distance separating the probe from the grinding tool.

Given that for the first segment of the path which corresponds to the short distance between the probe and the tool, no information is available, an external control is planned; but as soon as this short distance is crossed, the shift register, which is then filled, takes charge of the subsequent piloting.

Thanks to the invention, it becomes possible to successively grind glass sheets of any shape in any succession but also to remove references from the glass sheet. This considerably widens the field of use of the grinding machine and eliminates the downtime which had to be kept in mind in known grinding machines of this type for the passage from one program to another.

The invention is intended to control a machine for grinding the edges of a glass sheet, but it can also be used to control any machine for working the edges of a glass sheet or regions of its surface which can be identified relative to the edges. .

Thus, for example, certain glass sheets are provided on their edges or on the region of their faces near the edges, with an electrically conductive strip or a decorative strip; machines of the type of that of the invention equipped with an automatic piloting system can deposit such strips.

Furthermore, the invention can also be used to simply record the program of the path that a grinding tool should perform, in particular to control the shape of a glazing by comparing the values thus recorded with reference values stored in memory.

A first embodiment of a device used to carry out the invention by means of a tool mounted on a carriage movable in two directions XY, for example of a grinding head, is such that, for a predetermined resulting speed of the tool, i.e. for a constant sum of the carriage speeds in the X direction and in the Y direction, the speed ratio of the two drive motors along X and along Y is adjusted by means of d '' a feeler which comprises an arm which can pivot around the axis of rotation of the grinding head and a feeler roller mounted on this pivoting arm, preceding the grinding head, pressed against the edge of the glass sheet and thus following its contour, it being understood that the coordinates of the points of the path of the feeler roller are continuously noted converted into signals and that the signals thus obtained are supplied to the control circuit for the drive motors in the X and Y directions via of a m shift register emitter taking into account the distance separating the feeler roller and the grinding wheel.

For measuring the direction of movement of the roller probe, there is provided, in this case, a rotation measuring instrument coupled to the probe roller, describing the same path as the center of this probe roller, but whose angular spatial position is invariable, including the axis of rotation provided with one or more information points is fitted with a trailed roller which rolls against a flat plate and which is thus always adjusted in the direction opposite to the direction of movement. The necessary information concerning the path can, in this case, be obtained via the information ports of the rotation measuring instrument.

In another embodiment of a device according to the invention, the path program is determined by the fact that, for a predetermined resulting speed of the tool, a feeler roller rolling on the edge of the glass sheet , preceding the grinding head, is provided on the carriage on an arm which can pivot around the center of the grinding head and a second carriage movable in two perpendicular directions is coupled to this feeler roller so as to accompany it, the coordinates of the points of the path of the latter being supplied by digital signal generators mechanically connected to this second carriage, the signals supplied by the digital signal generators being transmitted to a shift register memory or to a microcomputer with register characteristic shift. Instead of using a second carriage with built-in movement to actuate the digital signal generators, it is also possible to obtain the coordinates of the points of the path of the feeler roller by electrical means from electrical voltages obtained from two path potentiometers arranged parallel to the axis X and to the axis Y and indicating the position of the carriage with ccnposed movement and of a rotation measuring instrument with sine-cosine characteristics which is coupled to the arm carrying the feeler roller.

The grinding head carrying the rotating wheel can in principle be fixedly mounted on the double movement carriage. However, it is advantageous if the grinding head is mounted on the double-movement carriage so that it can rotate around the axis of rotation of the grinding wheel so that, during movement around the glass sheet, it rotates 360 °. In this way it is possible to mount the grinding tool inside the grinding head on another carriage which can be moved perpendicularly to the edge of the glass sheet and this carriage can be pressed with an adjustable force against the edge of the sheet of glass. The control signals obtained during piloting in accordance with the invention can, for such a rotary grinding head and in another embodiment of the invention, also be used for controlling the rotational movement of the grinding head.

In an advantageous embodiment of the invention, the diameter of the feeler roller corresponds to the diameter of the grinding wheel. This simplifies the control circuit for the drive motors.

To produce the pressure with which the feeler roller is pressed against the edge of the glass sheet, a constant torque electric motor is preferably fitted on the pivot axis of the pivoting arm carrying the feeler roller.

• - la figure 1 illustre la structure mécanique d'une première forme d'exécution de la machine à meuler conforme à l'invention dont les éléments principaux sont représentés schématiquement ;
• - la figure 2 est une vue en élévation de côté du dispositif de palpage utilisé dans le dispositif représenté sur la figure 1 ;
• - la figure 3 est un diagramme destiné à expliquer les relations mathématiques entre la position du galet palpeur et celle de la meule ;
• - la figure 4 est le schéma de commtation pour le pilotage de trajet électronique de la tête de meulage .
• - la figure 5 est une vue schématique de la structure d'un micro-ordinateur pour le pilotage de trajet électronique, y inclus les composants périphériques ;
• - la figure 6 est une vue schématique de la construction et du circuit de commande pour la régulation de la pression de meulage ;
• - la figure 7 est un tableau schématique illustrant le déroulement des fonctions d'un mécanisme de commutation de programme pour la commande par courant fort de la machine ;
• - la figure 8 illustre le schéma de câblage pour la commande par courant fort de la machine à meuler ;
• - la figure 9 est une vue d'une deuxième forme d'exécution d'une machine à meuler conforme à l'invention comportant un deuxième chariot à double mouvement couplé au galet palpeur en vue de l'accompagner et dont la position est indiquée par des générateurs de signaux numériques;
• - la figure 10 illustre le système électronique d'exploitation et de commande pour les moteurs de positionnement de la tête de meulage dans la forme d'exécution représentée sur la figure 9 ;
• - la figure 11 est une vue d'une autre forme d'exécution d'une machine à meuler conforme à l'invention, dans laquelle la position du galet palpeur est déterminée à l'aide de composants électriques ;
• - la figure 12 illustre le système électronique de commande pour la détermination de la positon du galet palpeur dans la forme d'exécution représentée à la figure 11 et le système électronique de commande pour les moteurs de positionnement de la tête de meulage
• - la figure 13 est le schéma de commutation d'une régulation préprogrammable de la pression de meulage lors du passage autour des coins de la feuille de verre, cette régulation pouvant être utilisée pour les deux formes d'exécution du dispositif représenté aux dessins.

Other particularities and other advantageous embodiments of the invention will emerge clearly from the following claims and description in which two preferred embodiments of the invention are described in more detail with reference to the appended drawings in which:

• - Figure 1 illustrates the mechanical structure of a first embodiment of the grinding machine according to the invention whose main elements are shown schematically;
• - Figure 2 is a side elevational view of the feeler used in the device shown in Figure 1;
• - Figure 3 is a diagram for explaining the mathematical relationships between the position of the feeler roller and that of the grinding wheel;
• - Figure 4 is the switching diagram for controlling the electronic path of the grinding head.
• - Figure 5 is a schematic view of the structure of a microcomputer for electronic path control, including peripheral components;
• - Figure 6 is a schematic view of the construction and the control circuit for regulating the grinding pressure;
• - Figure 7 is a schematic table illustrating the sequence of functions of a program switching mechanism for the control by strong current of the machine;
• - Figure 8 illustrates the wiring diagram for the high current control of the grinding machine;
• FIG. 9 is a view of a second embodiment of a grinding machine according to the invention comprising a second double-movement carriage coupled to the feeler roller in order to accompany it and whose position is indicated by digital signal generators;
• - Figure 10 illustrates the electronic operating and control system for the positioning motors of the grinding head in the embodiment shown in Figure 9;
• - Figure 11 is a view of another embodiment of a grinding machine according to the invention, in which the position of the feeler roller is determined using electrical components;
• - Figure 12 illustrates the electronic control system for determining the position of the feeler roller in the embodiment shown in Figure 11 and the electronic control system for the grinding head positioning motors
• - Figure 13 is the switching diagram of a preprogrammable regulation of the grinding pressure when passing around the corners of the glass sheet, this regulation can be used for the two embodiments of the device shown in the drawings.

The mechanical structure of the grinding machine according to the invention is illustrated in its essential parts in Figure 1. The machine comprises a bridge 1 movable in the direction X on rails 2. The drive of the bridge 1 is carried out by through a drive motor 3. A carriage 4 is mounted movable in the Y direction along the deck 1 under the action of a drive motor 5. The drive motor 3 can be mounted on the bridge 1 and the displacement can be transmitted to the bridge by means of a rack disposed along one of the rails 2. As a variant, the drive motor 3 can also be mounted on the frame of the machine and the displacement can be transmitted to deck 1 by means of shafts or toothed belts or other transmission means of the same type. The drive motor 5 can be mounted in a similar manner on the deck 1 or on the carriage 4 and the transmission of the movement can also be ensured by a drive pinion and a rack or by a shaft or even by a belt. toothed.

It is also possible to mount the drive motor 5 on the frame of the machine and to transmit the driving force to the carriage 4 by a second bridge which extends above the machine in the direction X, as in the case of the device described in document DE-PS 26 46 062 (or its French correspondent FR 2 367 710).

With regard to drive motors 3 and 5, there these are direct current motors driven by pulses, with incorporated tachometer generator, of a current execution in the trade for example of motors of type M 19 P and F 12 T from the company BBC.

A grinding head 10 is mounted for rotation on the carriage 4. The grinding head 10 can, for example, be constructed in a manner as described in document DE-AS 19 66 260 (or its French correspondent FR 1 588 348 ). This means that in the rotating grinding head 10 is mounted a carriage movable in one direction and connected to an adjustable pressure device, which carries the grinding tool itself with the grinding motor. An adjustable pressure of the grinding tool perpendicular to the edge of the glass is thus possible. The rotation of the grinding head 10 is ensured by a motor 11 which is also mounted on the carriage 4. This motor 11 and its control device will be described later.

At the front of the carriage 4, the front being determined relative to its direction of movement (arrow F), a feeler roller 15 is mounted on an arm 14 and rolls on the outer contour of the glass sheet 16 to be ground. The arm 14 is pivotally mounted, author of the axis of rotation 18 of the grinding head 10. The feeler roller 15 is kept in uninterrupted contact with the edge of the glass sheet 16 by the effect of the rotor 20 of a motor. constant torque mounted on a shaft 19 rigidly connected to the arm 14 and exerting on the arm 14 a constant torque in the direction of the glass sheet (Figure 2).

The shaft 19 is extended upwards beyond the arm 14 and its end is connected to an arm 21 parallel to the arm 14 and of the same length. This arm 21 carries at its other end a toothed wheel 22 which can rotate about a vertical axis 25. Above the shaft 19, a toothed wheel 23 is fixedly mounted on the carriage 4 and is connected to the toothed wheel 22 by through a chain 24. This arrangement has the consequence that the axis of the toothed wheel 22 describes the same path as that of the feeler roller 15, the angular position of the toothed wheel 22 when moving around the sheet of glass remaining unchanged, however.

A rotation measuring instrument 29 constituted by a sine-cosine potentiometer is mounted on the toothed wheel 22 centered on the axis 25. An extension of the axis 25 is provided with an arm 26 at the end of which is mounted a so-called drag wheel 27.

This drag wheel 27 rolls on a horizontal upper plate 30. When the feeler roller 15 rolls on the edge of the glass sheet 16, the arm 26 always pivots thanks to the roller 27, in the opposite direction to that in which the feeler roller moves, so that the direction of movement of the touch roller is established at all times. The sine-cosine potentiometer 29 converts the angular position of the arm 26 into electrical quantities which are used for the control of the drive motors 3 and 5 and of the motor 11.

FIG. 3 illustrates the mathematical relationships which exist between the location of the feeler roller 15 and that of the grinding head 10, and which are at the basis of the construction of the machine. The fi ^g ure 3, denotes the angle which the arm 14 forms with the axis X and which also corresponds to the angle which the arm 26 carrying the trailing wheel 27 forms with the axis X. X _T and Y _T are the coordinates of the location of the feeler roller 15, X _K and Y _K are the coordinates of the location of the grinding head 10. A _T designates the length of the arm 14, that is to say the distance separating the feeler roller 15 from the grinding head 10. Between the location of the grinding head and the location of the feeler roller, the following relationship can be established:

If we calculate the differentials of the values X and Y, we get:

Since the angle α is measured continuously by the feeler roller system described above and the sine and cosine values of the angle 0 (are available directly as electrical voltages thanks to the sine-cosine potentiometer 29, these electrical voltages can be used directly to control the path of the grinding head.

The sine-cosine potentiometer 29 is, for example, a rotary potentiometer with four quadrants of the SCB 50 type from the company MEGA-TRON from Munich, Germany. Alternatively, one can also use, for example, the rotating generator of sine-cosine functions Art. n ° V 23 401 E 0012-B 001 from the company SIEMENS. The potentiometer 29 has, as clearly shown in Figure 4, via the two sliding contacts 38, 39, a double voltage tap, both sliding contacts 38, 39 forming an angle of 90 ° with each other and being rigidly connected to each other, so that the first tap directly gives the value of the sine of the angle α and the another take gives directly the value of the cosine of the angle α. The double socket 38, 39 rotates by virtue of the drag wheel 27, the movement of which is transmitted via the axis 25.

A tachometer generator 32 is mounted on the shaft 19 (Figure 2) in addition to the constant torque motor 20. The tachometer generator 32 provides an electrical voltage which is proportional to the angular speed of the shaft 19. Instead of a tachometer generator, it is also possible to use a digital signal generator which supplies a voltage of a frequency dependent on the angular speed of the shaft 19. The signals of the tachometer generator or of the digital signal generator are used to compensate for the errors which occur when the feeler roller passes, for example around a 90 ° corner. This compensation is effected by the expansion of the shift register 42 by means of the tachometric generator 32. If the peripheral speed of the feeler roller corresponds, for example, to the resulting grinding speed, that is to say to the sum geometrical speeds on X and Y axes, the number of storage locations in the shift register of the memory 42 on the X axis or the Y axis corresponds precisely to the length A _T arm of the feeler roller. When, on the other hand, the speed of the feeler roller, as a result of the pivoting of the arm 14, for example when passing around a corner at 90 °, becomes greater than the resulting grinding speed, thanks to the voltage supplied by the generator tachometer 32, the number of storage locations in the shift register of memory 42 is increased correspondingly. The signals corresponding to the sine and cosine values of the potentiometer 29 then leave phase shifted from the shift register and are transmitted with this phase shift as set values via the conductors 44 and 46 to the control devices 45 and 47 for the drive motors 3 and 5.

For regulating apparatuses 45 and 47, it is possible, for example, to use regime regulating apparatuses with transistor with four quadrants rhythmic by clock pulses of the model SMC, type 280 a, of the company HAUSER-ELEKTPONIK.

The drive motors 3 and 5 are each coupled, as mentioned above, to a tachometer generator 48 or 49. These gener tachometric indicators 48 and 49 supply a voltage corresponding to the actual speed of the motors 3, 5 and these voltages are brought via the conductors 50, 51 to the regulating devices 45, 47 where they are compared with the reference control voltages coming from conductors 44, 46 and are used for the control of motors 3 and 5.

The signals from the tachogenerators 48, 49 are also used to control the motor 11 which rotates the grinding head to rotate the carriage mounted in the grinding head and carrying the grinding motor with the grinding wheel. in such a way that the pressure of the grinding wheel is always exerted perpendicular to the edge of the glass sheet. For this purpose, the two sine-cosine potentiometers 54 and 55 are activated by means of the conductors 52 and 53 and these potentiometers are mechanically coupled to one another, by the connections 56, or are mounted in a single housing. and have a single common axis of rotation. This double sine-cosine potentiometer is connected directly by the link 57 to the drive motor 11 of the head, so that the shaft of the double potentiometer rotates in synchronism with the grinding head. The drive motor 11 is coupled to a tachometer generator 59 which, via the conductor 60, introduces the actual value of the speed of rotation of the grinding head into the regulating device 61.

The potentiometer 54 is connected via the control conductor 52 to the tachometer generator 48 of the X axis and the potentiometer 55 is connected via the control conductor 53 to the tachometer generator 49 of the Y axis. Both potentiometers are electrically connected to each other in a difference circuit and the setpoint voltage is obtained on the socket 63 of the potentiometer 54 and is brought via the conductor 62 to the regulating device 61. Thanks to this assembly, the motor 11 which directs the head 10 rotates in a manner corresponding to the preset preset voltage by means of the double sine-cosine potentiometer in connection with the tachynetric generator 59 forming the real value. When adjusting the head orientation, the setpoint voltage from the double sine-cosine potentiometer is then zero.

The double sine-cosine potentiometer 54, 55 also has the task of ensuring the correction of the effective grinding speed and this, by influencing the clock frequency of the shift register 42 by through the conductor 68. This correction is carried out as follows: from the voltage supplied by the tachometer generator 48 and by the potentiometer 54 associated with this tachometer generator 48, for setting the taps 63, 73 caused by the head orienting motor 11, an electric voltage is produced in the switching element 70 and corresponds to the value cos ² U _X. Furthermore, the voltage in the switching element 72 corresponds to the value sin ² _U y because the voltage coming from the tachometer generator 49 associated with the potentiometer 55 is multiplied by the voltage coming from the tap 74 in the potentiometer 55. The elements of switching 70, 72 are galvanic separation elements, that is to say direct current transformers, intended to avoid reactions due to the interconnection. The outputs of the two switching elements 70, 72 are connected in series. The sum of the resulting voltages corresponds to the cos ² U _X + sin ² Uy function, which, from the result point of view, is nothing other than the resulting voltage U _R corresponding to the resulting grinding speed. The resulting voltage U _R is present at the output of the switching element 75. It is applied to the clock signal generator 76, the output voltage of which is brought via the conductor 68 to the shift register 42 and serves setpoint value for the clock frequency by which the shift register 42 is paced or clocked.

When the resulting grinding speed changes, for example by adjusting the setpoint data at potentiometers 34, 35 whose sliding contacts are connected to terminals 38, 37 of sine-cosine potentiometer 29, the clock frequency of the register with offset 42 increases or decreases as a result of the switching described so that at the end of the account, the product of time and speed remains constant. The shift register 42 shown in FIG. 4 can advantageously be part of a microcomputer.

Figure 5 is a block diagram of the basic structure of such a microprocessor-controlled device, including the peripheral components necessary for this purpose. The device comprises the proprenent central unit called 80 of the microcomputer, for example a microprocessor of the type 8085 from the company INTEL, the input and output unit 81 with the connection line E leading to the control device. and the connection line A leading to the display unit, the RAM memory 82 and the EPROM memory 83. To the bus system are connected the memory expansion unit 84, which is also a memory RAM, and the interrupt processing unit 85. Unlike the _R AM memories which lose the values stored when the supply voltage is interrupted, the EPROM memory 83 retains its data even in the event of an interruption of the supply voltage. food. This memory 83 can be erased, for example by UV radiation.

The various interface blocks 86 to 93 are also connected to the bus system. The interface block 86 adapts the sine voltage value X which is brought to the interface block 86 from the potentiometer. sine-cosine 29 via the line 40 (FIG. 4) and via the analog-digital converter 94. The interface block 87 serves, in an analogous manner, for the adaptation of the value of cosine voltage Y which also comes from the sine-cosine potentiometer 29 and is brought to the interface block 87 via the line 41 and the analog-digital converter 95.

The microcomputer is programmed in such a way that it exhibits the properties of an expandable shift register. The clock frequency which is produced by the clock signal generator 76 (FIG. 4), is brought via the line 68 to the analog to digital converter 96 and is adapted to the microcomputer using the block. interface 88. This clock frequency is identical to the input or output clock frequency of the microcomputer. The expansion of the shift register is ensured by the electrical voltage which is supplied by the tachometer generator 32 mounted on the shaft 19 (Figure 2). This voltage is also digitized by an analog-digital converter 97 and is connected via the interface block 97 to the bus system of the microcomputer.

Depending on the sequence of the shift register which corresponds to the clock frequency, a voltage value introduced at input X via line 40 appears with the delay corresponding to output X (line 44) of the microcomputer, after the corresponding digital value has first been converted into an analog value in the digital-analog converter 98, since the following command already described requires analog values. The same goes for the voltage value brought to input Y via line 41, which appears after time delay in the form of an analog value in command line 46 after the digital value has all first been converted to an analog value in the digital-to-analog converter 99.

The signal intended for erasing the shift register is introduced into the microcomputer via the following command input of the interface block 92. This erasure signal is triggered by a potential-free contact 100 which belongs to the relay d8 in the wiring diagram of figure 8. The interface block 93 provides a control signal which switches relay d2. This relay d2 is also represented in the diagram in FIG. 8 and its mission is to signal the re-filling of the axes of the shift register, that is to say the fact that the shift register is ready.

As already explained, the grinding motor proper with the grinding wheel located inside the grinding head 10 is slidably mounted on a carriage which, by rotation of the grinding head 10 by means of the head turning motor 11 ( Figure 4) is oriented perpendicular to the edge of the glass sheet and is stressed under an adjustable pressure. This assembly is illustrated diagrammatically in FIG. 6. FIG. 6 shows the motor 106 of the grinding wheel on the carriage 107 which can be moved on rails 109 by means of bushings with ball bearings 108. The desired pressure of the grinding wheel on the edge of the glass sheet is produced by a constant torque motor 110 which acts on the carriage 107 by means of a shaft 112. To regulate the pressure force, regulator 114 is used in which the value of setpoint is introduced by means of potentiometer 115. For the rest, a dynamonetric capsule 117 is inserted in the transmission system for the pressure force in order to supply the regulator 114, via line 119, with an electrical voltage which corresponds to the actual value of the mechanical pressure.

The operating mode of the grinding machine and its control will now be described in more detail with reference to Figure 7 and the wiring diagram of Figure 8 in conjunction with the other figures. An essential element of the control device is a programming device, for example a programmable drum which is driven by a drive motor P _m . Discs forming cams are mounted on the periphery of the drum in order to actuate the limit switches P _o to P ₆ . The time course of the actuation of the individual limit switches is illustrated in the diagram in FIG. 7 as a function of the angle of rotation of the programming drum.

In its rest position, the carriage 4 of the furniture machine ler occupies a position in which the limit switch b ₁ actuated by the bridge 1 and the limit switch b ₃ mounted on the bridge 1 and actuated by the carriage 4 are closed. In addition, in the machine rest position, the arm 14 carrying the feeler roller 15 is oriented in the X direction. The drive motor P _m of the programming device is set in motion by actuation of the start key lbl, after which the programmer drum starts to rotate. When the programming drum turns, the switch Pl is first closed. This has the effect of actuating the relay dl which starts the drive motor 3 for moving the carriage 4 in the X direction. The speed of movement in the X direction is determined by a preset voltage preset by the microphone -computer which is brought to regulator 45 via line 44 and contacts dl and d6 (Figure 4). The carriage 4 thus travels a distance in the direction X which corresponds at least to the length A _T of the arm 14 carrying the feeler roller.

During the movement of the carriage 4 and of the feeler roller 15 as well as of the auxiliary feeler roller system 22 to 30 which is coupled thereto, the voltage signals supplied by the sine-cosine potentiometer 29 are introduced via the lines 40, 41 in the shift register 42 and the shift register is filled with this information. As soon as the X axis or Y axis of the shift register is filled in, the activation of relay d2 is triggered via the interface block 93, which has the effect of releasing the signal output from the register with offset 42. During this tenps, the bridge 1 which moves in the direction X actuated the limit switch b2, whereby the contacts of the relay dl are open and the relay d3 is activated. The regulating devices 45 and 47 are therefore separated from the preset set voltages and are switched to the outputs of the shift register 42 which now takes over the subsequent control of the drive motors 3 and 5. In addition, the constant torque motor 20 (Figure 2) is activated to rotate the arm 14 carrying the feeler roller 15 towards the edge of the glass sheet 16 and keep this feeler roller 15 continuously in contact with the sheet of glass.

During the rotation of the programmer drum, approximately when the command is taken over by the shift register, the contact P2 is closed by the drum and the constant torque motor 110 which produces the grinding pressure is, therefore , powered up (figure 6).

Contact P3 is then closed by the rotating programming drum. An opening of P3 also causes the programmer motor Pm to immobilize initially, until the limit switch b2 is again actuated by bridge 1, it being understood that the actuation of the limit switch b2 can only occur when the bridge 1 moves in the starting direction. The new actuation of this limit switch b2 therefore means that the carriage 2 has traversed the entire periphery of the glass sheet 16. The limit switch b2 actuates the contact d4, which has the effect of restoring the programmer motor Pm.

The contact P4 which is actuated during the continuation of the rotation of the programming drum actuates the relay d5, whereby the direction of rotation of the constant torque motor 110 regulating the grinding pressure (figure 11) is reversed and the grinding head is returned to its starting position. In addition, the constant torque motor 20 of the feeler roller is switched off by the contact P4 and the relay d3 is tripped, which separates the regulating devices 45, 47 from the shift register. Subsequently, the P5 contact closes, which again immobilizes the Pm motor of the programmer and energizes the relay d6. The relay d6 connects the regulating device 45 via the relay d3 to a pre-established negative reference voltage which ensures that the bridge 1 returns in the direction X to its rest position. As soon as the limit switch bl is actuated by the bridge 1 in its rest position, the relay d6 opens again. Simultaneously, the relay d7 is activated by bl, whereby the regulating device 47 is connected to a pre-established negative reference voltage which causes the carriage 4 to return in the Y direction until the relay d7 is triggered by actuation. of the limit switch b3 by the carriage 4.

The programmer motor Pm is then restarted by the limit switch b3. Closing the contact P6 has the effect of exciting the relay d8, whereby, on the one hand, by the action of the constant torque motor 20 and an electromagnet not shown, the arm 14 and thus the roller probe 15 are brought into their rest position and, on the other hand, by another contact of relay d8, the shift register 42 is erased. The programmer cycle continues until the Po contact is actuated, which ends the grinding cycle and disables the programmer motor. The machine is thus ready for a new grinding cycle.

In the device described so far, the sine-cosine potentiometer 29 serves as a measuring instrument for determining the path of the feeler roller 15 and intervenes to establish the speed ratio in the X direction and in the Y direction, it being understood that the analog values supplied by the sine-cosine potentiometer are stored after digitalization in the shift register. However, it is also possible to detect the coordinates of the track roller path in another way. Thus, the position of the feeler roller can, for example, be determined by means of an auxiliary coordinate system immediately by a digital signal generator. A device operating according to this principle is described with reference to FIGS. 9 and 10. It is also possible to determine the path coordinates of the feeler roller by using electronic components. Such an embodiment operating by means of electronic components is described in detail with reference to FIGS. 11 and 12.

The device operating by means of an auxiliary coordinate system and shown in Figures 9 and 10 will be described first. The lower part of Figure 9 is a plan view of the main parts of the grinding machine of the type shown in Figure 1, bearing the bridge 1 which can move on the rails 2, the carriage 4 which can move along of the bridge 1 and the probing system formed by the arm 14 and the feeler roller 15. The movement of the bridge 1 in the direction X is controlled by the drive motor 3 and the movement of the carriage 4 in the direction Y is controlled by the drive motor 5 mounted on the carriage 4. The motor 11 which is also mounted on the carriage 4 serves to rotate the grinding head 10 so that the pressure is always exerted perpendicular to the edge of the glass sheet.

In a plane situated above this grinding machine with a carriage movable in two perpendicular directions and parallel to this is disposed a second carriage device also movable in two perpendicular directions in which the carriage 124 is mounted movable along the rail 125 in the direction X and of the rail 126 in the direction Y. The rail 125 along X is guided on the pair of rails 128, 128 ′ so that it can move parallel to it, while the rail 126 along Y can move on the Pai re rails 129, 129 'parallel to it. The carriage 124 is coupled, by means of the coupling rod 132 shown diagrammatically, to the center of the feeler roller 15 with a view to accompanying it so that the carriage 124 describes a path which corresponds to the path of the feeler roller 15.

A digital signal generator 134 for the X direction is provided on the rail 126 and a digital signal generator 135 for the Y direction is provided on the rail 125. The gear wheels for driving the rotors of the digital signal generators 134, 135 each mesh with racks, not shown, which are arranged along the rails 128 ′, 129. Of course, other assemblies of the digital signal generators are also possible, provided that they are mechanically connected to the carriage 124.

As for the digital signal generators 134, 135, they provide two-sign rotational pulses, i.e. when the digital signal generators move in the first direction, positive voltage pulses are produced and when they move in the opposite direction, the voltage pulses produced are negative. The pulses from the digital signal generators 134 and 135 are supplied to a microcomputer 137 with a shift register characteristic. The microcomputer supplies, with the corresponding delay, positive or negative control pulses, via the forward-reverse difference sensor 138, to the digital-analog converter 139, from which the corresponding analog value arrives. to the amplifier 140 which, for its part, controls the drive motor 3 intended to move the grinding head in the X direction. The tachometer generator 141 coupled to the drive motor 3 serves to compare the set value and the actual value. The pulse generator 142 also coupled to the axis of the drive motor 3 has the task, at the end of the path of the grinding head, of bringing the forward / reverse difference counter 138 to zero , that is to say that the drive motor 3 rotates until the actual starting position, in which the counter 138 is at zero, is again reached.

Similarly, the control for the drive motor 5 is designed to move the grinding head in the Y direction. The control signals from the microcomputer 137 are supplied via the counter. forward - reverse 148 and digital-analog converter 149, to the amplifier 150 which, for its part, governs the speed of rotation and the direction of rotation of the drive motor 5. The tachometer generator 151 which is coupled to the axis of the drive motor 5 supplies the actual speed value and the generator 152 supplies, at the end of the journey, if at this time the counter 148 has not returned to zero, as many control pulses preceded by the necessary sign as it is necessary for the sensor 148 to return to zero, so that the exact starting position is reached.

For the rest, the control of the machine corresponds to the control of the embodiment described above in relation to FIGS. 4 to 8. In particular, the voltages supplied by the tachometric generators 141 and 151 are used to control the head turning motor 11 by activating, via lines 52, 53, the double sine-cosine potentiometer 54, 55 shown in FIG. 4. The voltages on this double sine-cosine potentiometer 54, 55 can again be used to control the frequency generator clock 76 which determines the rhythm or the cadence of the microcomputer.

In this embodiment of the invention described with reference to FIG. 9, it is necessary to ensure that the microcomputer 137 with shift register characteristic includes a deletion of the empty storage locations simultaneously on the two axes. If this is not so, oscillations could appear in the forward speed when empty locations appear simultaneously on the two axes.

While in the embodiment described with reference to Figures 9 and 10, an auxiliary mechanical device in the form of an additional X, Y compound carriage is necessary, it is possible to achieve the same goal also by the arrangement shown in Figures 11 and 12, in which such additional mechanical devices are not necessary, but where the position of the feeler roller is obtained electrically.

The grinding machine, including the feeler system, is basically constructed in the same way as that described in front of Figure 9. As shown in Figure 11, the bridge 1 can be moved along the rail 2 in the X direction by means of the drive motor 3 and the carriage 4 is moved along the bridge 1 in the direction Y by means of the drive motor 5. The feeler system mounted on the carriage 4 is again fortified with the arm 14 and the roller 15. The rotor 20 of an engine at constant torque acting on the arm 14 ensures that the roller 15 remains in contact with the edge of the glass sheet 16. The motor 11, which is also mounted on the carriage 4, is designed to rotate the grinding head 10 each time so that the wheel is always pressed perpendicularly to the edge of the glass. A sine-cosine rotation potentiometer 155 is also coupled to the axis of rotation of the arm 14 carrying the feeler roller 15. A potentiometer 156 is mounted parallel to a rail 2 for the X direction and a potentiometer 158 is provided in parallel at bridge 1 for direction Y. A sliding contact 159 is provided on bridge 1; the electric voltage obtained from the potentiometer 156 constitutes a measurement of the position of the center of the grinding head 10 on the axis of the coordinates X. The sliding contact 160 which is mounted on the carriage 4 takes, for its part, from the potentiometer 158, an electric voltage which constitutes a measure of the position of the center of the grinding head 10 on the axis of coordinates Y. The path coordinates of the center of the grinding head can thus be determined simply. The electronic circuit now has the function of determining from these data the path coordinates of the center of the feeler roller preceding the grinding head. This goal is obtained by the means cited on the basis of the mathematical relationship below.

et

When the length of the arm 14 is expressed from its pivot point to the center of the feeler roller by AL, the path coordinates of the grinding head by X _s , Y _s and the path coordinates of the feeler roller by X _T , Y _T and that the angle of rotation of the arm 14 is expressed by α, we can, as shown in Figure 11 in detail, express the coordinates X _T , Y _T of the instantaneous location of the feeler roller as follows:

and

The values corresponding to the sine and the cosine of the angle α are obtained from the sine-cosine potentiometer 155. These values allow the path coordinates of the feeler roller to be calculated immediately as indicated by means of voltages corresponding to the coordinates path X _s and Y _s obtained via path potentiometers 156 and 158.

The analog system described here and formed of potentiometers 156 and 158 and of the sine-cosine potentiometer 155 can obviously also be replaced by a corresponding digital system, in which case we use instead of the potentiometers 156, 158, elements called "digital gauges" and instead of the sine-cosine potentiometer 155, a digital angular function generator.

The electronic processing of the signals coming from the potentiometers 155, 156 and 158 comes from the assembly shown in FIG. 12. For the X axis, the voltage obtained at the sinus tap 162 is combined via the galvanic separating element 163 with the voltage present at the sliding contact 159. The voltage resulting from these two voltages is brought via the line 164 to the servo-amplifier 165 as the reference voltage. The servo-amplifier 165 drives a combined measurement system formed by a motor 166, a tachymeter generator 167, a pulse generator 168 and a rotational patentiometer 169. The tachometer generator 167 supplies the actual voltage which is brought to the amplifier-servicer 165 by the line 161. The rotary potentiometer 169 supplies by the line 170 the signal qualified as feedback signal so that it is formed with the voltage value introduced by the line 164 a difference of voltage which, as such, controls the motor 166. In this case, therefore, it is an inertia control; for an exact inertia the difference in tension is equal to zero. The digital signal generator which is also coupled to the motor 166 corresponds to the digital signal generator 134 of Figure 10 and provides the path signals which are then used later as described in connection with Figure 10, to which reference should be made for this peculiarity.

The processing of the voltages obtained from the potentiometer 156 at the sliding contact 160 and from the sinus-cosine rotation potentiometer 155 at the cosine socket 172 is carried out in an analogous manner by means of the galvanic separating element 173, of the servo amplifier 175 and the combined measurement system formed by the motor 176, the tachometric generator 167, the digital signal generator 178 and the rotary potentiometer 179. The digital signal generator 178 corresponds to the digital signal generator 135 of FIG. 10 and provides the path signals for the Y axis which are processed as described with reference to Figure 10.

In all embodiments of a grinding machine according to the invention, it is possible to provide for a higher development. additional, which resides in the fact that the grinding pressure is not adjusted, count described with reference to FIG. 6, only on a determined value, but that the grinding pressure is increased or decreased during moving around the glass sheet in critical places, for example at the acute corners, to produce in these places, in a desired manner, rounding of desired radii. For the regulation of the constant torque motor 110 determining the grinding pressure, according to this embodiment, use is made of the signals which are supplied by the tachometer generator 32 and which represent a measure of the angular modification of the grinding direction.

A control circuit for regulating the grinding pressure when moving around a sheet of glass in particular for changing the pressure when passing around the corners is illustrated in Figure 11. In this case, the mounting of the movable carriage 107 with the grinding head 106, the constant torque motor 110, the dynamotnetric capsule 117 and the regulator 114 corresponds to that shown in FIG. 6.

The programming around the illustrated periphery is intended for a sheet of glass with several corners and it essentially comprises a current digital preselection counter 180 having ten preselection possibilities by which the grinding pressure can be increased or decreased in a maximum of five corners and, when the corners have been crossed, this pressure can each time be reduced to its normal value. For the adjustment of the normal pressure, the potentiometer R1 is used, while the level of the grinding pressure on the individual corners of the glass sheet of the series is adjusted by means of the potentiometers R2 to R6. The control voltage for the regulator 114 which advantageously has the form of a four-quadrant servo-amplifier, is supplied to the regulator 114 via the line 182 and the contact P2. The patent sensor R7 is used to adjust the value of the withdrawal force of the constant torque motor 10 and the control voltage thus adjusted is supplied to the amplifier 114 via the contact d5.

The control signals for the modification of the grinding pressure at the corners are supplied by the tachometer machine 32 which also ensures the expansion of the shift register which is controlled by the line 183. The signals supplied by the tachometer machine 32 correspond to the angular speed of the arm 14 on which the feeler roller 15 is mounted. Since the grinding pressure should only be changed for relatively sharp angles, since only angles smaller or equal to 90 ° are critical for the grinding pressure, the tension of the tachometer machine 32 is applied to a device measurement trigger 184. The desired switching point is set in this measurement trigger device using potentiometer 185, that is to say it is thus established from which corner angle a modification of grinding pressure must be performed. If when the sensor roller 15 reaches a corner, the tachometer machine 32 produces a ten _- sion that operates the trigger device 184, the dl3 relay is actuated for a short period of time.

In the zone of the preselection counter 180, the relay dl4 is energized by the relay dl3 and is then maintained spontaneously. The relay dl4 simultaneously supplies the digital preset counter 180 which, at this time, is still at zero, by means of the counting clock pulses taken from the clock signal generator 76 which controls the shift register. The preselection counter 180 is programmed so that after a constant path distance, which corresponds to the length A _T of the arm of the feeler roller 14, the relay Zl of the counter operates. The relay Zl ensures that the potentiometer R2 has the set value, whereas before that, it was the potentiometer Rl which was responsible for it. During the following preselection, it is determined for which travel distance the potentiometer R2 remains switched on. This means that, when the sensor relay Z2 operates, the control voltage is brought back to the potentiometer Rl, which simultaneously interrupts the chain towards the trigger element or trigger dl5. Relay dl4 is therefore triggered, after which the counting rhythm is interrupted and the preset counter is stopped.

If the feeler roller 15 then detects the second critical corner, the relay d14 is again closed and the operation which has just been described is repeated, this time via the preselection relays Z3 and Z4. For the third corner, the described operation is repeated again, through the preselection relays Z5 and Z6. The grinding pressure can, in this way, and with the help of this system, be adjusted to a desired value for a number of wedges of up to five, independently for each of them, i.e. say that each corner can be treated with another piece of furniture pressure age. At the end of the molding operation, the digital preset counter 160 is reset to zero by the control device of the grinding machine via the erasing input 186.

Claims (25)

1. Method for the automatic control of a machine along a path, in particular of a machine for grinding the edges of glass sheets comprising a grinding head mounted on a carriage with double movement in two directions X, Y, characterized in that a feeler member mounted on the carriage carrying the grinding head, preceding this head and palpating the edge of the glass sheet, determines the path control program for a defined distance in front of the grinding head, the coordinates X and Y of the path points being stored in a biaxial shift register and, after crossing the shift register, being used to control the drive motors of the carriage carrying the grinding head. 2. Device for carrying out the method according to claim 1, comprising a working tool, for example a grinding head (10), mounted on a double-movement carriage in two directions X, Y, characterized in that for a resulting preset speed of the tool, that is to say for a constant sum of the speeds of the double-movement carriage (4) in the directions X and Y, the ratio of the speeds of the drive motors along X and Y ( 3, 5) is adjusted using a feeler member which has an arm (14) which can pivot around the axis of rotation (18) of the grinding head (10) and a feeler roller mounted on this arm (14), preceding the grinding head (10) pressed against the edge of the glass sheet (16) and thus following its contour, the direction of movement of the feeler roller (15) being continuously taken into account and the signals thus obtained being brought in via a shift register corresponding to the distance (AT) between the feeler roller (1 5) and the grinding head, to the control circuit of the drive motors along X and Y. 3. Device according to claim 2, characterized in that the feeler roller (15) mounted on the arm (14) which can pivot has a diameter corresponding approximately to the diameter of the grinding wheel belonging to the grinding head. 4. Device according to claims 2 and 3, characterized in that to produce the pressure of the feeler roller (15) on the glass sheet (16), an electric motor with constant torque (20) is provided, motor which transmits a torque to the shaft (19) to which the arm (14) which carries the feeler roller is connected. 5. Device according to claims 2 to 4, characterized in that to determine the direction of rotation of the feeler roller (15) a rotation measuring instrument (29) coupled to the feeler roller and performing the same movement as the center of the feeler roller is provided, the axis of rotation (25) of this instrument being provided with a dragging wheel (27) arranged at a distance of the axis (25) and rolling on a flat plate (30). 6. Device according to claim 5, characterized in that the rotation measuring instrument (29) is mounted on a support (22) whose spatial angular position remains constant. 7. Device according to claims 5 and 6, characterized in that the support (22) of the rotation measuring instrument (29) is a toothed wheel (22) mounted to rotate whose angular position is determined by another toothed wheel (23) with fixed angular position and a chain (24) which couples the wheel (23) to the toothed wheel (22). 8. Device according to any one of claims 5 to 7, characterized in that the support (22) of the measuring instrument (29) coupled to the feeler roller (15) so as to accompany it is mounted on an arm (21) disposed above the grinding plane and kinematically connected to the arm (14). 9. Device according to any one of claims 5 to 8, characterized in that the rotation measuring instrument (29) is a generator of rotation signals by induction. 10. Device according to any one of claims 5 to 8, characterized in that the rotation measuring instrument (29) is a sine-cosine potentiometer. 11. Device according to any one of claims 5 to 10, characterized in that an expandable shift register comprising a variable number of storage locations is used as the shift register (42), the number of storage locations each occupied time can be adjusted according to the angular speed of the arm (14) carrying the feeler roller (15). 12. Device according to claim 11, characterized in that a tachometric machine (32) or a generator of digital signals whose output voltage or frequency influences the number of locations of the shift register is coupled to the arm (14) carrying the touch roller and turns with it. 13. Device according to claim 12, characterized in that the tachometer machine (32) or the digital signal generator is mounted on the shaft (19) carrying the arm (14) or is coupled to this shaft. 14. Device according to any one of claims 2 to 13, characterized in that the shift register (42) is part of a microcomputer. 15. Device according to any one of claims 2 to 14, characterized in that two potentiometers (34, 35) precede the rotation measuring instrument (29) to preset the resulting grinding speed and determine the maximum voltages supplied to the drive motor along X and drive motor along Y (3, 5). 16. Device for carrying out the method according to claim 1, co-carrying a working tool, for example a grinding head, mounted on a double-movement carriage composed according to X and Y, characterized in that for a predetermined speed resulting from the tool on the carriage (4), a feeler roller (15) rolling on the edge of the glass sheet and preceding the grinding head (10) is provided on an arm (14) which can pivot around the center of the head grinding (10), and a second double movement carriage (124) is coupled to this feeler roller (15) so as to accompany it, the coordinates of the points of the path of the latter being provided by digital signal generators ( 134, 135) mechanically connected to the second carriage (124), it being understood that the signals supplied by the digital signal generators (134, 135) are brought to a shift register or to a microcomputer (13) with register characteristic shifted. 17. Device for carrying out the method according to claim 1, comprising a tool, for example a grinding head, mounted on a double-movement carriage composed according to X and Y (4), characterized in that for a resulting preset speed of the tool on the carriage (4) a feeler roller rolling on the edge of the glass sheet (16) and pre-delivering the grinding head (10) is provided on an arm (14) which can pivot around the point of rotation of the grinding head and for determining the coordinates of the points of the path of this feeler roller (15), is mounted, on the one hand, parallel to the X axis and to the Y axis, respectively a potentiometer (156, 158 ) from which sliding contacts (159, 160) connected to the carriage (4) take electrical voltages which correspond to the position of the grinding head (10) and, on the other hand, a rotation measuring instrument (155 ) with sine-cosine characteristic coupled to the pivotable arm, it being understood that the information d The path for the position of the feeler roller (15) is obtained from the tensions resulting from the combination of the voltages taken from patentiaretres (156, 158, 155). 18. Device according to any one of claims 2 to 17, characterized in that the grinding head (10) is rotatably mounted on the compound double carriage (4) and the spatial angular position of the grinding head (10 ) is determined by a drive motor which is controlled by the electrical signals for adjusting the drive speed of the motors along X and Y. 19. Device according to claim 18, characterized in that the signals used to camander the drive motor (11) of the grinding head, taken from the shift register (42) or from the tachometric machines (48, 49, 141, 151) reproducing the actual position of the drive motors along X and Y (3, 5) are supplied to a double sine-cosine potentiometer (54, 55) whose axis of rotation is mechanically coupled to the axis of rotation of the drive motor (11) and which supplies the control voltage for the regulator (61) of the motor (11). 20. Device according to claim 19, characterized in that the voltages taken from the double sine-cosine potentiometer (54, 55) are used for the control of the clock signal generator (76) which determines the clock frequency of the register offset (42). 21. Device according to any one of claims 2 to 20, characterized in that inside the rotating grinding head (10), the grinding tool (106) is slidably mounted on a carriage (107) and a constant torque motor (110) acting on the carriage (107) is provided for adjusting the grinding pressure. 22. Device according to claim 21, characterized in that the pressure produced by the constant torque motor (110) is transmitted via a manometric capsule (117) to the carriage (107) whose electrical output signal is supplied to the regulator (114) acting on the motor (110) to regulate the preset pressure. 23. Device according to claims 21 and 22, characterized in that to modify the grinding pressure when passing around a corner, the regulator (114) is activated by the signals produced by the tachometer machine (32) indicating the speed angle of the feeler arm (14). 24. Device according to claim 23, characterized in that a preselection counter (180) comprising adjustment potentiometers (Rl to R6) associated with its contacts, precedes the regulator (114), for the preselection of the desired pressure at level of each corner of the glass sheet. 25. Device according to any one of claims 2 to 24, characterized in that a progression circuit is provided for controlling the progress over time of the individual functions.

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