FI109410B - Method and equipment in sheet metal working machine - Google Patents

Abstract

The invention relates to a method for transferring a carriage (11, 12) in a sheet metal working machine, wherein a carriage (11, 12) of a moving carriage arrangement in connection with said sheet metal working machine is transferred by means of at least two actuators (16a, 17a; 18a, 19a) parallel in the direction of movement of said carriage (11, 12) controlled by a control value (S) of the position given by a control centre (41), in order to transfer a sheet (14) to be machined and attached to the mounting means (13) of the carriage arrangement, substantially in the main plane of the sheet (14) to perform machining directed to the sheet (14). In accordance with the invention, to prevent twisting caused by asymmetric loading, individual separate measuring values (M16,M17) of the position are determined for the at least two parallel actuators (16a,17a;18a,19a) by means of separate positioning systems (16b,17b;18b,19b) attached in connection with each of said actuators, and each of said separate actuators (16a,17a;18a,19a) is controlled independently and separately by means of difference value between a control value given by the control centre (41) and the measuring value (M16,M17) of the position related to said individual actuator. The invention further relates to an apparatus implementing the method.

Description

, 109410

METHOD AND EQUIPMENT ON A PLATFORM MACHINE

The invention relates to a method for moving a workpiece moving carriage according to claim 1 in a plate working machine. The invention further relates to an apparatus according to the preamble of claim 8 for carrying out the above method.

This invention relates to sheet metal working machines which process individual sheets of sheet metal to produce them in the desired shape. As a rule, the workpieces 10 are metal sheets made of different alloys, for example 1250 x 2500 mm or 1500 x 3000 mm. Typically, the thickness of the metal plates ranges from 0.5 to 3.5 mm. sheet metal and sheet metal work machines, respectively. Typical operations performed on a sheet by a machine tool include, for example, punching, corner cutting, threading or riveting.

U.S. Patent No. 4,658,682 discloses an automatic disk machine.

Such a plate machine typically has a body, a first carriage moving relative to the body, and a second carriage attached to the first carriage and movable in a direction perpendicular to its direction of movement. Said second carriage includes fastening means for attaching the workable plate to the carriage. By means of a carriage arrangement of the first carriage and the second carriage, the workpiece can be: · 'moved substantially in the XY plane i25 parallel to the main plane of the disc relative to the working machine used, for example a piercer or: i.

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Modern plate machines are controlled by numerical computer control. A control program is stored in the memory of the control center, which is executed automatically by the disk machine 30 under the control of the control center.

The control center (or its subsystems) obtains the information needed to control various institutions and drives, such as position and position information, from various measurement systems and / or sensors connected to the disk machine. The · · · · · 35 equipment for the automatic control of plate machine tools and their functions are well known in the art and are therefore not further described herein.

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The automatic numerical control of plate machines enables the machine machines to operate at high speed and thus increase productivity. The time available per sheet to be machined can be reduced, firstly, by accelerating the movement of the sheet between and / or during the machining steps 5 and, on the other hand, by speeding up the machining steps themselves. The present invention focuses on the former possibility of improving the performance of plate machine tools.

As already mentioned above, the sheet to be machined is moved in the XY plane 10 by a slide arrangement formed by a first carriage and a second carriage connected thereto. Conventionally, both carriages of the carriage arrangement are mechanically moved by an actuator acting, for example, on a ball screw or a rack mechanism. Chain or timing belt driven movement mechanisms are also known. Em. One problem with mechanical solutions is to combine the high speed of movement required for a modern plate machine with good positioning accuracy in the same motion mechanism. By combining, for example, a ball screw propulsion mechanism with a separate, for example optical, carriage position indicating station-20 measuring system, good positioning accuracy can be achieved to achieve good machining accuracy, but at the same time one has to settle for slower movement speeds. Correspondingly, tooth-rack mechanisms provide better speeds, but; this makes it difficult to achieve good positioning accuracy.

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In recent plate working machines, linear servomotors are used to move the carriages, which can provide high speed of movement and, at the same time, good positioning accuracy when combined with a separate accurate, e.g., optical position measurement system 30. The maximum movement speeds that can be achieved with linear servos are: ···. 3-5 m / s and maximum accelerations 20-40 m / s2.

In practice, however, it has been found that while linear servomotors per se provide the ability to move the carriage assembly carriages and 35 workable discs rapidly, especially between machining steps, there is high acceleration and deceleration of the movable masses! ··! cause the life of the structures of the mobile toboggan arrangement, which limits the speeds used in the movement. For example, in a situation where the second carriage of the carriage assembly, and a plate substantially secured to the side of the carriage, is fastened by moving the first carriage from one position to another, such unbalanced loading results in significant structural stressing and bending forces on the carriage assembly. When the movement of the tray arrangement is stopped rapidly, vibration of the structures is caused, which diminishes the accuracy of the plate machining that requires good positioning accuracy.

Em. undesired bending / twisting of the carriage arrangement structures 10 due to eccentric load also occurs in non-linear sero-drive solutions when a significant increase in the carriage arrangement speeds and trails is sought.

Em. in order to reduce the problems of rotation / deflection of structures 15, a technique is known in which one carriage of a carriage arrangement is moved instead of one drive by two parallel drives in the movement direction of said carriage, for example two parallel ball screw drives. Thus, for example, the second carriage of the carriage arrangement is arranged to be movable relative to the first carriage 20 by two parallel drives, which are controlled by the position information provided by one position sensor. By doubling the drives needed to move the carriage in the aforementioned manner, the said drives are applied in the carriage acceleration or braking situation: forces are applied to the carriage at two points, thereby reducing the i.i i 25 torque forces exerted on the carriage. This solution somewhat reduces the tendency for structures to rotate. In such a known solution, both drives are controlled in the same way by a common position sensor! : ***: information provided, i.e. both drives are controlled by a single control unit which supplies the same 30 controls to both drives. For ball screw drives, for example, the power of a single drive motor is mechanically transmitted to two parallel ball screws which rotate with each other at the same speed.

The problem of living in structures can also be thought of as: · · ·: 35 also eliminated by sufficiently reinforcing and stiffening the sled. juggling structures, but, for example, if the structures of the second carriage moving with the first carriage are reinforced * while significantly increasing their mass, this, on the other hand, aggravates the situation as the moving masses increase. In addition, the cost of manufacturing sheet metal working tools is increased, since more raw materials are needed to produce stronger structures and, consequently, moving a heavier carriage assembly requires higher power drive motors, thicker linear guides, etc.

The main object of the present invention is to provide a novel method for moving a sled in a plate moving carriage arrangement in a plate machine so that the above-described problems caused by the fast, high acceleration and deceleration of said 10 sled can be significantly reduced. To accomplish this purpose, the method according to the invention is essentially characterized in what is set forth in the characterizing part of independent claim 1.

15

It is a further object of the invention to provide an apparatus implementing the above method. Correspondingly, the apparatus according to the invention is essentially characterized by what is set forth in the characterizing part of independent claim 8.

20

The invention is fundamentally based on the idea that the sledge arrangement of a plate machine is moved by two or more parallel and controlled independent drives, each drive being controlled by its own separate position measuring system; ; ; 25 man based on drive measurements. This allows the position error of said carriage position, i.e., substantially the movement direction of the carriage

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rotation detection and active compensation. Rotation compensation is achieved so that the individual drives connected to the carriage respond individually to a position error 30 provided by the positioning system of the individual drive. the actual drive dimension value and the disk machine control center. ·· '·. The difference between the control value of the given position.

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An important advantage of the invention over the prior art is that it enables the plate machine and its tray arrangement to be realized; lighter than before, but at the same time allow for very high positioning accuracy for high quality machining results »» ·. 109410

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To achieve. Lighter structures achieve significant cost savings in sheet metalworking.

Due to the lighter structure of the slide arrangement, the movement of the machining plate can be further accelerated between the machining steps and / or during which the capacity and productivity of the plate working machine in production use can be increased.

The solution according to the invention also allows effective compensation of the position and / or position error of the carriage 10 caused by one movement axis of the carriage arrangement due to movement of the carriage arrangement according to another movement axis. For example, the fast movement of the first carriage may cause an error in the position of the second carriage attached thereto due to the rotation of the second carriage (and a workable plate attached thereto), although during this movement the second carriage position control value is maintained constant, i.e. However, according to the invention, rotation in the position of the second carriage can be actively compensated for during the movement of the first carriage.

Preferably, in the solution of the invention, parallel and controlled independent drive of the carriage is effected by linear servomotors Linear servomotors have the advantage of their speed, which allows for rapid response when incoming carriage rotation is detected, whereby: V rotation can be effectively compensated

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The following is an exemplary embodiment of the invention, * ·· '. further explanation will further illustrate to the skilled person, ···. advantageous embodiments of the invention as well as advantages over the prior art.

The invention will now be described in more detail with reference to the accompanying drawings, in which:

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Fig. 1 illustrates, in a simplified side view, essential elements of a linear servomotor, Fig. 4 illustrates a plan view of the forces acting on the carriage, Fig. 3 illustrates, in simplified side view, essential components of a linear servomotor. a control system implementing the method according to the invention, and FIG. 5 illustrates, in principle, a top plan view of another embodiment of the invention.

It will be understood, of course, that the various embodiments of the invention are not limited to the following examples, but may freely vary within the scope of the inventive features set forth in the claims below.

Figure 1 illustrates in principle a plan view of a preferred embodiment of the invention. Figure 1 is a simplified representation of the essential parts of the tray machine 20 assembly which allow the workpiece to be moved relative to the machine tool machine.

«* 4 ·; In the plate working machine of Fig. 1, a first carriage 11 is connected to the body 10, typically below the body} 25, which is arranged to move along guides 10 within the body 10 in a direction Y. The second carriage 12 is arranged. to move along guides in the first carriage 11 in the direction X which is perpendicular to the direction of motion of the first carriage 11. The other * * · 30 carriage 12 is fitted with fastening members 13 on the work plate 14. for attaching the peripheral portion to said carriage 12. By means of the carriage arrangement of the first # · carriage 11 and the second carriage 12, the workable plate 14 can be moved in a substantially V * indicated in the figure relative to the working device 15. The working device 15 may be e.g. , angle cutter, •: Threading or riveting device. Typically, the machining plate 14 is a systematic, '···! (not shown in Fig. 1), 7 109410, the plate 14 of which moves along the surface of the desk as moved by the above-described slide arrangement.

In Figure 1, the first carriage 11 according to the invention is arranged to be moved by two parallel and guided independent drives 16a, 17a, each of which is controlled by the position information provided by the drive's own separate position measuring system 16b, 17b. Ts. drive 16a is controlled by the position information provided by the position measuring system 16b, and drive 17a is controlled by the position information provided by the position measuring system 10b 17b, respectively. For the sake of clarity, Figure 1 does not show the separate guides, etc., which may be used to support the carriage 11.

In Figure 1, the second carriage 12 is arranged to be moved along guides or the like in the first carriage 15 (not shown in Figure 1) in a suitable manner according to the prior art. Ts. for example, by a single drive 18a, which drive is controlled by the position measurement system 18b. Of course, one of ordinary skill in the art will appreciate that the method of the invention may also be applied to moving the second carriage 12, but since said second carriage 12 is subjected to relatively slight rotational forces of carriage 12 in the carriage arrangement of Figure 1.

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Mi 25 Preferably, drive 16a and drive 17a are each implemented in Figure 1

Mv with a separate linear servomotor, the operation of which is described in more detail below in the -V-j. It will, of course, be understood that the invention is not limited to the use of linear servomotors, but that the drive 16a and the drive 17a may be implemented in any other manner obvious to one skilled in the art.

. ···, Such as ball screw, toothed rack, chain or <«,! ', Toothed belt drive mechanisms.

Preferably, the position measuring system 16b and the position measuring system: M 35 17b are implemented by means of a sensor operating on an optical principle, so-called. Optical M-bar. Such an optical gauge bar, which is a technique well known in the art, provides very good measurement and positioning accuracy. However, the invention is not limited here to the use of position measuring systems / sensors operating on an optical basis, but any other solution apparent to one skilled in the art can be applied for this purpose.

5

The invention will now be explained in more detail with reference to Figures 1 and 2.

In Fig. 1, the workable plate 14 may move within a rectangular motion range moved by the carriage arrangement of the first carriage 11 and 10, the extreme positions of the disc 14 at the transverse angles of motion being indicated by reference letters A and B. and the second carriage 12 is shown in Figure 1 with dashed lines. Fig. 1 further shows positions C and D corresponding to the other two angles of the aforementioned range of motion. For clarity, the plate 14 or the tray arrangement in position C or D is not shown separately in Figure 1.

As the second carriage 12 moves from position A in Fig. 1 along the first carriage 11 towards station C, a torsional force is applied to the support between the first carriage 11 and the body 10 of said second carriage 12 and the plate 14 attached thereto. These torques tend to rotate the first carriage 11 relative to the body 10.

I I 25 1 · · · I Figure 2 illustrates in more detail the effect of the above torque forces; - the drives 16a and 17a of the first carriage 11.

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In Figure 2, the first carriage 11 relative to the frame and drives 30 16a, 17a in the XY plane rotates 21.22 in magnitude and direction depending on e.g. - the distance of the second carriage 12 from the support between the first carriage 11 and the body 10, i.e. the length of the so-called "torsion arm" • ** ·: - the movement space of the second carriage 12, i.e. is the movement i of the second carriage 12 flat 10 · 109410 - of the common mass of the second carriage 12 and the plate 14 attached thereto and the location of this center of mass relative to the longitudinal axis 5 of the carriage 11 According to the invention, the torque 21,22 rotating the carriage 11 can now be compensated as follows.

Having first considered the situation in which the position control value provided by the disk machine numerical control center for drives 16a and 17a is constant, i.e., the position of the first carriage 11 in the Y direction is tended to be kept constant / stationary. However, when the torque forces 21,22 resulting from the movement of the second carriage 12 tend to rotate the first carriage 11 relative to the body 10, the position measuring system 16b of the drive 16a detects the difference of the actual position control values measured at the measuring point 17c.

As a result, the separate and independent control units of the drives 16a and 17a each tend to eliminate the difference between the measured actual position values and the aforementioned position control value. This 20 causes the actuators 16a and 17a to be controlled such that the actuators apply counter-forces 23,24 to the body 10 to compensate for the effect of the torque 21,22.

In the situation where the first carriage 11 is displaced in the Y direction • ·: 25, the numerical control center of the disk machine supplies the drives 16a and 17a with a continuously variable drive control value. In this case, the drives 16a and 17a: the independent control units tend to eliminate the position value measured by the said control value and the position measurement systems 16b and 17b. the first slide 11 moves in the drive. 30a, 17a respectively. Similarly to the above, in this situation also the control units of the drives 16a and 17a may react to the rotation of the first carriage 11 caused, for example, by the movement of the second carriage 12 relative to the first carriage 11. Em. the situation is created, for example, by moving obliquely from position A to position B in Fig. 1, whereby both carriages of the carriage arrangement • »move simultaneously.

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109410 10

In Figure 1, rotation of the first carriage 11 with respect to the body 10 may also be caused by the fact that only the first carriage 11 is moved relative to the body 10 without the second carriage 12 moving relative to the first carriage. Such a situation occurs, for example, when moving from position A to position D in Figure 1, the second carriage 12 and the plate 14 attached thereto are eccentrically relative to the body 10.

In Figure 2, the actuators 16a and 17a are shown to be implemented by linear servo-10 motors. Figure 3 is a simplified and principled illustration of the parts essential to the operation of a linear servomotor. The linear servomotor is a brushless electric motor in which the rotor 31 is arranged to move by a magnetic field generated by an electric current applied to the windings contained in the rotor 31 along a path formed by the permanent magnets 32 (not shown in Figure 3). There is a small air gap, typically of the order of 1 mm, between the rotor 31 and the permanent magnets 32, which remains constant as the abovementioned guides support the rotor 31 at a certain distance from the path formed by the permanent magnets 32.

20

The advantage of linear servomotors in the use according to the invention is their speed, which allows for a rapid reaction upon detection of incoming rotation of the carriage, whereby the rotation can be effectively compensated in its initial stage before it becomes significant.

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Figure 4 illustrates in principle one control system: ·; The control system consists of a disk machine control center 41 and the separate control units 16 and 17 of the drives 16a, 17a, while the control center 41 provides control units 16,17 for the station control value S. ··. supplying to drives 16a, 17a, preferably linear servomotors, separate controls D16, D17, which drive actuators 16a, 17a '· Ί 35 so that the difference between the station dimension values M16, M17 and the station control value S is S-M16 = Δ16 and S-M17 = Δ17 are minimized.

; : ·; When the carriage 11 reaches the desired position S, the difference values Δ-Ι6 and Δι7 are obtained. both have a value of zero. As a result, the controls D16, D17 also receive a value of "109410". When the values of Δ16 and Δ17 are zero, the control center 41 knows that the carriage 11 is in the desired position.

In a situation where the control value S is constant, i.e. the position of the carriage 11 is held constant but the carriage 11 is subjected to forces rotating in the plane of the carriage 11 movement, this difference is observed as Δ16 or Δ17, or both. Thus, to compensate for the rotation of the carriage 11, the control units 16 or 17, or both, independently seek to reset the difference values to zero by appropriate control D16, D17.

When moving the carriage from one station to another, the control center 41 supplies the control units 16,17 with a continuously variable station control value S.

Here, with the differential values Δ16 and Δ17 constantly being non-zero, the drives D, 6, Di7 of the drives 16a, 17a also receive a non-zero value for moving the carriage 11 in the desired direction. In this situation, the rotation of the carriage 11 is detected by the difference values Δ16 and Δ17 being different from each other, i.e. Δ = Δ16 - Δ17 ^ 0. As a result, the drives 16a and 17a receive different large controls D16 and D17.

By controlling the difference difference Δ = Δ16 - Δ17, the control center 41 can determine the amount of rotation of the carriage 11. Also, a maximum value can be set for the difference difference Δ, above which the control center: V 25 41 can reduce the rate of change of the station control value S, i.e. the acceleration or deceleration of the carriage 11, thereby correspondingly reducing the strain on the carriage arrangements. This allows, for example, that the amount or location of the mass attached to the carriage 11 (the position of the second carriage 12 and the mass / size of the plate 14 attached thereto) is such that ···. 30 having a low tendency for the carriage 11 to rotate, the carriage 11 may be moved at higher accelerations and decelerations than in a condition where the carriage 11 is subject to high rotational forces due to the amount and location of the mass to be moved.

Figure 5 further illustrates, in principle, a top plan view of the application of the invention ·: ·: to a disc machine of another type with a tray arrangement.

. In a plate working machine according to Fig. 5, a first carriage 11 is arranged above the body and is arranged to move 1 to 12 109410 along the guides 10 in the body 10 in the direction X. The second carriage 12 is arranged to move the guides 11 in the first carriage 11 or the like. along a Y direction. The second carriage 12 is provided with fastening means 13 for securing a workable plate 14 to said carriage 12.

Similarly to the plate machine shown in Fig. 1, the plate 14 to be machined in Fig. 5 may be moved by a carriage arrangement of the first carriage 11 and the second carriage 12 in a straight-railed movement area 14 for machining the plate 14 with peripheral positions of the plate 14 with reference letters AD.

In a plate working machine of the type shown in Figure 5, the method 15 of the invention can be applied to the movement of both the first carriage 11 and the second carriage 12. In Figure 5, two controllably independent actuators 16a and 17a are used for moving the first carriage, which are controlled by the measurement data provided by the position measuring systems 16b and 17b. Similarly, two self-actuating controls 18a and 19a are used for moving the second carriage, which are controlled by the measurement data provided by the position measuring systems 18b and 19b.

Preferably, in the case of Fig. 5, the method according to the invention is particularly suited for moving the second carriage 12 (drives 18a and 19a), since the structure of the second carriage 12 and the guide rails supporting the carriage should preferably be as light as possible. To support the first carriage 11 '·' ·, the body 10 and carriage support guides or the like attached thereto.

...: can be built to be very rigid (and thus heavier) if necessary, Y .: 30 because they are not moving parts of the plate machine and thus their weight does not directly affect the movement of the carriage arrangement.

Of course, it is clear that there may be more than two parallel drives in one carriage. In this case, to prevent / compensate for carriage rotation, at least two of these drives must be controlled according to the invention, but preferably all drive uses: controlled independently and separately by their own control units according to the invention.

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It will, of course, be apparent to one skilled in the art that the present invention is not limited to the machining of the aforementioned metal sheets, but can also be applied to the machining of sheets of other materials, for example plastic or bakelite sheets.

5

Of course, one of ordinary skill in the art will also appreciate that various combinations of the methods, methods, and apparatus structures described above in connection with the various embodiments of the invention may provide various embodiments of the invention that are within the scope of the invention. Therefore, the foregoing examples are not to be construed as limiting the invention, but embodiments of the invention may freely vary within the scope of the inventive features set forth in the claims below.

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Claims (16)

A method in a plating work machine, wherein a sled (11, 12) of a movable sliding arrangement 5 in connection with the plating machine is transmitted with at least two relative directions of movement (16a, 17a; 18a, 19a) controlled by the sled (11, 12). a control value (S) given by a control center (41) of the position, to transmit a plate (14) fixed to the fastener (13) of the carriage arrangement which is to be processed substantially in the main plane by the plate (14) to carry out processing to be directed to the plates (14), characterized in that - for the at least two parallel drives (16a, 17a; 18a, 19a) of the sled (11, 12), their own separate measurement values (M16, M17) are determined by the position by means of a with each said operation separately connected the position measuring system (16b, 17b; 18b; 19b), and - each said separate operation (16a, 17a; 18a, 19a) is controlled independently and separately by a difference value obtained as the difference between e a control value (S) provided by the control center (41), and a measured value (M16, M17) of a station belonging to said single operation. Method according to claim 1, characterized in that each of said at least two single drives (16a, 17a; 18a, 19a) of the sled (11, 12):. 25 is independently controlled to minimize the current operation associated with the "X difference value. · · · · · · Method according to claim 1 or 2, characterized in that each of said at least two single drives (16a, 17a; 18a, 19a) of the sled; 30 is independently controlled to maintain the difference value associated with the present operation with respect to the difference values of the other drives (16a, 17a; 19a, 19a) of the sled (11,12). A method according to any preceding claim, characterized in that, for the difference values of said drives (16a, 17a; 18a, 19a), the maximum permissible value for single difference values, i.e. the first limit value. is 109410 Method according to claim 4, characterized in that when the differential value of any single operation (16a, 17a; 18a, 19a) of the carriage (11, 12) exceeds said predetermined first limit value, the rate of change is reduced by the position control value (S), i.e. The acceleration or deceleration of the sled (11,12) is reduced. Method according to any of the preceding claims, characterized in that the maximum permissible value, i. the second limit value, is determined for the difference between the difference values of said drives (16a, 17a; 18a, 19a). Process according to claim 6, characterized in that when the difference between the difference values between some two of the individual drives (16a, 17a; 18a, 19a) of the sled (11, 12) exceeds said predetermined second limit value, the rate of change is reduced by position control value (S), ie. the acceleration or deceleration of the sled (11, 12) is reduced. An operating apparatus for transmitting a carriage (11, 12) in a plating machine, wherein the carriage (11, 12) of a carriage arrangement of said plating machine is arranged to be transmitted by means of at least two parallel drives (16a) in the direction of movement of the carriage (11, 12). , 17a; 18a, 19a), controlled by a control value (S) of a position given by a control center (41), to transmit a plate (14) to be processed and:. 25, which is fixed to the fastening means (13) of the carriage arrangement, substantially parallel to the main plane of the plate (14) for carrying out operations which are directed to the plates (14), characterized in that the operating apparatus of the carriage (11, 12) comprises at least: ···: 30 - separate position measuring systems (16b, 17b; 18b, 18b) connected in connection with each of at least two: · · parallel operations (16a, 17a; 18a, 19a) of the carriage (11, 12) to determine the position measurement values (M16, M17) separately for /; each said operation (16a, 17a; 18a, 19a), and 35. own separate controllers (16, 17) for said least two parallel drives (16a, 17a; 18a, 19a) of the carriage (11, 12) for: "to control each said operation (16a, 17a; 18a, 19a) independently and separately by means of a differential value obtained 20 1 0 9 4 1 0 as the difference between a control value (S) given by the control center (41) and a measured value (M16, M17) of a current operation (16a, 17a; 18a, 19a) associated position. 9. An operating device according to claim 8, characterized in that the control units (16, 17) are arranged to independently control each of said at least two single drives (16a, 17a; 18a, 19a) of the carriage (11, 12.). the present value of the difference. 10. Apparatus according to claim 8 or 9, characterized in that the control units (16, 17) are arranged to independently control each of said at least two single drives (16a, 17a; 18a, 19a) of the carriage (11, 12.). holding the differential value associated with the present operation equal to the corresponding difference values of the other drives 15 (16a, 17a; 18a, 19a) of the sled (11, 12). 11. An operating apparatus according to any of the preceding claims 8-10, characterized in that the operating apparatus comprises means (41) for determining the maximum permissible value, ie. the first limit value, for the 20 individual difference values that belong to said operations (16a, 17a; 18a, 19a). 12. Apparatus according to claim 11, characterized in that when the differential value of any single operation (16a, 17a; 18a, 19a) of the sled:. (11, 12) exceeds said predetermined first limit value, the control unit (41) is arranged to reduce the rate of change of the position control value (S), i.e. to reduce the acceleration or deceleration of the sled. '··· * 30 Operating apparatus according to any of the preceding claims 8-12, characterized in that the operating apparatus comprises means (41) for determining the maximum permissible value, i.e. the second limit value for the difference between the difference values of said operations (16a, 17a; 18a, / Γ: 19a). 35 14. Apparatus according to claim 13, characterized in that when the difference values of the difference between some two of the individual drives (16a, 17a; 18a, 19a) of the carriage (11, 12) exceed said predetermined other limit value, the control unit (41) is arranged to reduce the rate of change of the position control value (S), i.e. to reduce the acceleration or deceleration of the sled. Operating apparatus according to any of the preceding claims 8-14, characterized in that the position measuring systems (16b, 17b; 18b, 19b) are measuring rod or the like which function with an optical principle. The operating apparatus according to any of the preceding claims 8-15, 10, characterized in that the drives (16a, 17a; 18a, 19a) are linear servomotors / drives (31, 32). »·