FR2810268A1 - SHEET TO SHEET CUTTING INSTALLATION WITH LAUNCHING DEVICE PROVIDING THE SETTING FUNCTION IN POSITION OF SHEETS - Google Patents

Abstract

The machine has a cutting cylinder (1) with a reciprocating cutter holding plate (2) and a feed (3) to project the sheets between the cylinder and the plate. A feed belt (9) is motor driven (M3) actuated by an electronic control circuit. The belt accelerates each sheet from a conveying speed to a speed matching that of the reciprocating plate. An adjusting circuit determines the cutting position for each sheet with respect to its leading edge.

Description

SHEET TO SHEET CUTTING INSTALLATION WITH DEVICE

  OF LAUNCHING PROVIDING THE SETTING FUNCTION IN

SHEET POSITION

  The present invention relates to the technical field of cutting one by one semi-rigid sheets, in particular of cardboard, and more particularly, but not exclusively of corrugated cardboard. Its main purpose is a cutting installation equipped at the input with a sheet launching device which has been perfected so as to ensure a new function of wedging in position of the

  sheets relative to the cutting tool.

  A cutting installation is in practice always integrated into a sheet processing line which comprises at least as a first upstream machine a device for introducing the sheets, commonly called a feeder, and generally having the function of automatically introducing the sheets one after the other at the entry of the line at a given rate (time interval between two successive sheets) and giving them a given linear speed. In a simplified version, when the processing line has only a sheet cutting functionality, the machine downstream of the feeder is the cutting installation. In a more complete version, when the processing line also has the function of producing a print on the sheets, it comprises between the feeder and the cutting installation a

  or several successive printing groups.

  The cutting of a semi-rigid sheet, in particular of corrugated cardboard, is carried out on conventional cutting installations using a cutting tool and a support surface. The cutting tool comprises blades or support threads substantially perpendicular to the support surface when the sheet is pressed between this support surface and the cutting tool, so that the threads pass through the

  sheets and make the corresponding cut.

  More particularly, according to a type of cutting installation known and described for example in US-A-3,765,286 or also in European patent EP-BO 625 411, the cutting tool is mounted on a tool-holder plate, also commonly called marble, while the bearing surface is formed by the surface of a cylinder, called a cutting cylinder. The tool tray is designed to be in reciprocating operation back and forth, which allows each sheet to be moved one after the other under the cutting cylinder from a sheet feeding position

  to be cut to a position for discharging the cut sheet.

  Such a cutting installation is also equipped upstream of the tool holder plate and of the bearing surface, with feeding means making it possible to introduce each sheet on the tool holder plate during the

  displacement thereof relative to the cutting cylinder.

  In European patent EP-B-O 625 411, these supply means comprise two successive systems for transporting the sheets. The first, called transfer case, receives the sheet from an upstream machine (feeder or printing unit), and transfers it at a substantially constant speed, equal to the speed of exit of the sheet from the upstream machine. The second, known as the launching device, implements a launching belt which receives the sheet from the transfer case and introduces it between the tool-holding plate and the

cutting cylinder.

  In the aforementioned cutting installations, the kinematics of the belt of the launching device is usually controlled so as to have a speed profile which is as follows. In a first phase corresponding to the waiting phase for reception of a new sheet, the linear speed of the launching belt is constant and equal to the speed of the upstream transfer system. In a second phase, of predetermined constant duration, the launching belt accelerates in a substantially linear manner until reaching the desired launching speed for the sheet (linear speed of the marble in the cutting phase). In a third phase, the speed of the launching belt is kept constant (phase during which the sheet is introduced between the cutting cylinder and the tool tray). In a fourth phase, the launching belt decelerates in a substantially linear manner until it again reaches the speed of the upstream transfer system. In a fifth phase, the speed of the launching belt is kept constant until the next operating cycle. It is important to emphasize that this speed profile, for a given cutting installation is always the same, regardless of the setting in position of the cutting relative to the sheet that

we want to get.

  In the operation of a sheet processing line comprising a cutting installation, it is important that the sheet is positioned very precisely relative to the cutting tool. In addition, this positioning may be different from an application. It is therefore necessary for an operator to be able to easily adjust this positioning, during a so-called setting operation of the sheet with respect to the cutting cylinder and to the cutting tools carried by the tool holder plate. To date, this setting in position has been adjusted at the feeder. To this end, all the feeders known to date are equipped with a sheet synchronization device, which allows the position of each sheet to be wedged during its introduction relative to the cutting cylinder and the cutting tool. As an indication, usually, in the area of cutting cardboard blanks, the adjustment latitude is +/- 100mm. In the case of mechanical feeders, this synchronism device requires the implementation of complex mechanics and a high cost price, based on differential elements. In the case of electronic feeders, it is possible to eliminate this complex mechanism, however this type of feeder due to its high cost price, is reserved for lines

high range treatment.

  The present invention provides a new solution to the problem of wedging the position of the sheets relative to the cutting tool, which is simple to implement and less expensive than the solutions currently known, and which makes it possible to simplify the

feeder design.

  The invention is based essentially on a modification made to the device for launching the sheets at the entrance to a cutting installation, making it possible to give this launching device a new functionality for wedging in the position of

  sheets in relation to the cutting cylinder and the tool tray.

  The main object of the invention is therefore a sheet-by-sheet cutting installation which is known in that it comprises a cutting cylinder, a tool-holder plate with reciprocating movement, and a device for launching the sheets between the cylinder d 'support and the tool holder plate, and comprising a launching belt which is driven by a motor (M3) controlled by electronic control means, and which allows, in synchronism with the movement of the tool holder plate and the rotation of the cutting cylinder, to accelerate each sheet from a first linear speed (Vl) to a

  second linear speed (V2) equal to the linear speed of the carrier plate

  tool (2) during the cutting operation.

  Typically according to the invention, the cutting installation comprises means allowing the entry by an operator of a setting parameter (S) characterizing the position of the cutting in each sheet relative to the front or rear edge of the sheet. , and the electronic motor control means (M3) are designed to control the motor (M3) over time, in position and speed.

  function of this setting parameter (S).

  It is another object of the invention to propose a sheet-by-sheet cutting line comprising a sheet-by-sheet cutting installation according to the invention and a mechanical feeder which is mechanically coupled for its operation to the motor shaft driving in rotation of the cutting cylinder, without means for adjusting the position of the movable elements of the mechanical feeder relative to the position

angle of the shaft of this motor.

  Other characteristics and advantages of the invention will appear

  more clearly on reading the following description of an example

  preferred to achieve a sheet-by-sheet processing line with

  cutting installation according to the invention, which description is given

  by way of nonlimiting example and with reference to the appended drawings in which: FIG. 1 is a schematic representation, side view, of a line for processing cardboard blanks, with feeder, flexography printing unit, transfer device and sheet-by-sheet cutting installation; - Figure 2 is an enlarged and more precise representation of the cutting installation of Figure 1; FIG. 3 is a simplified representation of the cutting installation, schematically showing the motors (M1), (M2) and (M3) used for driving the cutting cylinder, the tool plate (marble) respectively and the launching device belt; - Figure 4 schematically illustrates the different positions of the tool holder plate of the cutting installation during its forward movement; - Figure 5 is a block diagram of the electronic engine control means (M1), (M2), (M3); - Figure 6 shows over time, and for an operating cycle (cutting a sheet): curve (I): the speed of rotation of the motor (M1) / cutting cylinder, curve (II): the speed of rotation of the motor (M3) / launching belt, curve (111): the speed of rotation of the motor (M2) I tool holder plate, - and Figure 7 represents a cut made in a sheet according to

several calibration values.

  With reference to FIG. 1, in a particular variant embodiment of the invention, an installation for cutting one by one of semi-rigid sheets, and in particular of blanks of corrugated cardboard, is formed successively, from the entry to at the exit of the installation, a mechanical feeder A, a flexographic printing unit B, a transfer device C and a cutting unit D. Cutting unit (D) The unit cutting machine D essentially comprises a cutting cylinder 1, a tool-holder plate 2 commonly known as marble, and a launching device 3. The marble 2 is usually designed to be driven in an alternating back and forth movement under the cylinder cutting machine 1, and carries metal nets for cutting a sheet with a cookie cutter, by pinching the sheet between the cutting cylinder 1

and marble 2.

  With reference to FIG. 1, for the rotary drive of the cutting cylinder 1, the cutting unit D is equipped with a first motor M1 coupled to a reduction gear R1, by a transmission belt C1. The reducer R1 has two outputs: the main output of the reducer R1 directly drives the shaft l a of the cutting cylinder 1; the secondary output of the reducer R1 is used for driving the feeder A, the printing unit B and the transfer device C. In FIG. 3, for the sake of simplification, the transmission belt Cl between the motor M1 and the reducer R1 has been intentionally omitted. In operation, the motor M1 is controlled so as to drive this cutting cylinder 1 at a known predetermined constant speed, fixing the operating cycle of the installation (after an initial phase of linear acceleration when starting the installation ). In the embodiment below, the motor M1 is a brushless motor. However, it should be emphasized that the use of this motor M1 does not require stepping control, we can use more generally any motor delivering sufficient torque and allowing to rotate the cutting cylinder 1 at a substantially constant angular speed. We could thus use for example a motor

vector asynchronous.

  Referring to Figure 3, the marble 2 for its reciprocating movement relative to the cutting cylinder 1 is mounted in the usual way on two parallel racks 4 and 5, which mesh -7 respectively with two identical pinions 6 (only one of the two pinions 6 being visible in FIG. 3), the two pinions being driven by a brushless motor M2, by means of a set of transmission pinions 7,8. The kinematics of the return movement of the marble relative to the cutting cylinder 1, as well as the means for controlling the brushless motor M2 to obtain this kinematics will be detailed later. It should be noted that the invention is not limited to the implementation of a brushless motor for the motor (M2), but that one can more generally use any motor which can be controlled with sufficient precision in speed and position. Also in another less perfected embodiment, the plate 2 could be driven by the same motor as

  that (M1l) used to drive the cutting cylinder in rotation.

  The launching device 3 is positioned immediately in

  upstream of the cutting cylinder 1, above the rear path of the plate 2.

  This launching device 3, the structure of which is known per se, essentially comprises a belt 9 permeable to air (for example perforated belt), mounted tensioned on two rollers 10, 11, one of which 10 is mounted free to rotate and the other 11 is motor. The upper strand 9a of the belt 9 which successively receives the sheets coming from the transfer device C, is inclined slightly downwards in the direction of the marble 2. Furthermore, the launching device comprises aeraulic means making it possible, in the usual way, to create an air flow through the upper strand 9a of the belt 9 so as to press and maintain a sheet on the surface of the belt without risk of slipping of the sheet. These ventilation means being already known, they are not shown in their entirety in the appended figures, only the suction box 15 disposed under the upper strand 9a of the belt 3 being

shown in figure 2.

  For the drive of the belt 9, the shaft 11la of the drive roller 11 is mechanically coupled for its rotational drive to a brushless motor M3, via two pinions 12 and 13 connected by a transmission belt 14, the pinion 13 being mounted directly on the output shaft of the motor M3. The function of the launching belt 9 is to take up a sheet brought to an initial linear speed (Vl) by the transfer device C, and to bring this sheet between the plate 2 and the cutting cylinder 1 of the cutting, in synchronism with these two elements, and making it undergo an acceleration until reaching a determined linear speed (V2) equal to the linear speed of advancement of the marble 2 under the cutting cylinder 1 during cutting. The kinematics of this belt 9 and the means for controlling the brushless motor M3 to obtain this kinematics will be detailed later. It should be noted that the invention is not limited to the use of a brushless motor for the motor (M3), but that one can more generally use any motor which can be controlled with sufficient precision in speed and position; it could be a vertical asynchronous motor with low inertia and offering characteristics comparable to

a brushless motor.

  Marker (A) With reference to FIG. 1, the mechanical feeder (A) essentially comprises two superposed rollers A1 and A2, associated with an upstream device A3, with reciprocating movement, and usually having the function of pushing the sheets one at a time. one between the two rollers

  A1 and A2. This pushing device A3 being known, it will not be detailed.

  For their rotational drive, the two rollers A1 and A2 of the feeder A are mechanically coupled to the secondary output of the reducer R1 by a mechanical transmission chain essentially comprising from the output of the secondary reducer R1, a cardan transmission CA, a second reducer R2 with angle gear, and an A4 belt driving the two rollers A1 and A2 at the same speed and in opposite directions. For its reciprocating movement, the leaf pushing device A3 is coupled to the axis of rotation of the lower roller A2, by a pinion A5 driving a known mechanism A6 of the connecting rod type, making it possible to transform the rotational movement

  continuous of pinion A5 in an alternating movement of given amplitude.

  We understand in light of the above description of the chain

  mechanical transmission between the motor M1 and the moving parts of feeder A, that this transmission chain does not allow any adjustment of the position of the mobile elements (A1, A2, A3) of the mechanical feeder relative to the angular position of the shaft of this engine (M1). Thus, unlike the usual implementation of a mechanical feeder in a cutting installation, there is no system between the feeder and the mechanical control shaft of this feeder (in this case secondary output of the reducer R1) synchronism based on differentials allowing a user to program a delay or an advance of the feeder operation with respect to the operating cycle of the cutting unit E. In other words, the feeder A under the control of the rotation of the motor M1 is designed to deliver at the output of the sheets one after the other, by communicating to each sheet a given speed fixed by the speed of rotation of the rollers A1 and A2, and above all with a positioning of each sheet at the output of the feeder relative to the angular position of the cutting cylinder which is set once and for all during the design of the cutting installation, and which cannot be modified by an i user installation. This relative positioning corresponds to an initial setting of a sheet relative to the cylinder of

  cutting, and determines an initial position of the cutting in the sheet.

  Printing unit (B) The different cylinders of group B flexographic printing (plate cylinder B1, backpressure cylinder B2, screen cylinder B3) are also mechanically coupled for their drive, to the universal joint CA by a third reducer R3 with return angle and by a transmission belt B4. In the variant illustrated in FIG. 1, each sheet output from the feeder A is taken up directly by pinching between the plate cylinder B1 and the backpressure cylinder B2 of the printing unit. B. Transfer device (C) The transfer device C is known per se and will therefore not be detailed. It essentially implements a box containing a plurality of conveyor belts CT, of small width, parallel and spaced, and mounted tensioned, above a perforated curved plate P, on two rollers, one of which 17a is motor and the other 17b is mounted free to rotate. The drive roller 17a, for its rotational drive, is coupled to the secondary output of the reducer R1, by a synchronous transmission belt C2 and a reducer R4. This transmission chain is calculated so that the linear speed (Vl) of the belts CT is constant (the motor M1 being driven at constant speed) and substantially equal to the linear speed of the sheets leaving the printing unit (circumferential speed backpressure cylinders B2 and plate holder B1). Thus the CT conveyor belts make it possible to receive the sheets one after the other after printing and to convey them at a constant speed (Vl) to the launching device 3 of the cutting unit. Also, similar to the launching device 3, in order to prevent the sheets from sliding during transport, the transfer device (C) is equipped with suction means (not shown) enabling the sheets to be pressed

  transported against the upper face of the CT belts.

  Means for controlling brushless motors M1 to M3 (FIG. 5) Usually in the field of controlling a brushless motor, each brushless motor M1 to M3 is equipped with a sensor (not shown), commonly known as a "resolver" delivering information on the instantaneous angular position of the motor rotor (FIG. 5, signal 18), and is controlled in torque mode by a variator 19 delivering for the motor three control signals (R, S, T), depending on a setpoint signal 20, and position feedback information

(signal 18).

  For its control each brushless motor M2 to M3 is equipped with an incremental encoder 21 mounted directly on the motor rotor and coding in pulse form the angular position of the rotor (signal 22), the number of pulses per revolution of the rotor being fixed and defined by the resolution of the encoder. For controlling the motor M1, the cutting unit D also includes a third incremental encoder 21 ', which is mounted directly on the shaft 1a of the cutting cylinder 1. This encoder 21' delivers a first signal 22 'encoding in the form of pulses the angular position of the cutting cylinder 1, as well as a second signal 23 'which is synchronous with the first signal 21', and which results in a pulse every (n) pulses of the first signal 21 ', the counting factor (n) being configurable. The counting factor (n) of this signal is adjusted so that the encoder 21 'associated with the motor M1 delivers a pulse (synchronization signal 23') at each revolution of the cutting cylinder 1, each pulse (top synchronization) being used for the

  synchronization of other M2 and M3 motors.

  For controlling the variators 19, the cutting unit comprises an axis card 24 which makes it possible to drive at least three separate axes in parallel (one axis corresponding to a brushless motor M1, M2

or M3).

  For each axis, the card 24 usually comprises a trajectory generator 25 which is controlled by a movement program 26 stored in random access memory. This movement program 26 successively communicates over time to the associated trajectory generator 25 the information on the next axis trajectory point (next position of the axis, speed of the axis at this position, and duration of movement of the axis to reach this position), the trajectory generator automatically calculating point by point the kinematics of the axis between two successive points provided by the movement program 26. At output, the trajectory generator 25 delivers a position setpoint 27 which is compared to the position feedback signal 22 or 22 '. The setpoint signal 20 for controlling each variator 19 is generated by a regulator R, for example of the PID type, from the difference between the setpoint 27 delivered by the trajectory generator 25 and the signal

position feedback 22 or 22 '.

  The movement program 26 for controlling each brushless motor M1, M2, and M3 is specific to the kinematics of the cutting cylinder 1, the plate 2 and the belt 9 respectively of the

launch 3.

  The kinematics of the cutting cylinder 1 is extremely simple, since the latter is driven at constant angular speed (Qo) by the motor M1, with the exception of the initial start-up phase, during which movement program 26 provides the trajectory generator 25 1 5 driving the motor M1, trajectory points allowing a constant acceleration of the cutting cylinder, until reaching the

  predefined speed of rotation (l0).

  The kinematics of the marble 2 and the belt 9 of the device

  launch 3 are more complex and will now be explained.

  Kinematics of the cutting unit marble (D) Referring to Figure 6 (curve Ill), each operating cycle of the marble 2 is broken down into three main phases, the start of a cycle being synchronized by the synchronization signal 23 '(top synchronization) delivered by the incremental encoder 21' of the motor M1. The first phase (phase I / FIG. 5) is a waiting phase of fixed and known duration (toffset), during which the plate 2 is stationary in a known position, called neutral. This is the position (a) of the marble 2 in Figure 4. In this neutral position, the first marble cutting net is located at a known distance d from the axis of rotation of the

cutting cylinder 1.

  The second phase (phase II / Figure 5) corresponds to the forward movement of the marble. This phase breaks down as follows. At first, the marble accelerates (Figure 5 / point P0 to P2) to the position referenced (b) in Figure 4. This position corresponds to a positioning of the front edge of the marble 2 upstream of the cutting cylinder and at a short distance from the axis of this cylinder. In a second step, the marble 2 is driven at the constant speed V2 (figure 5 / points P2 to P3) to the position referenced (c) in figure 4. Finally, in the third step, the marble 2 undergoes a deceleration ( Figure 5 / points P3 to P5) until reaching with zero speed the position referenced (d) in Figure 4. The cutting sheet and the cutting trimmings are in a known manner removed from the marble 2 from the moment when the marble arrives in position (c) and before

marble return movement 2.

  The third phase (phase III / Figure 5) corresponds to the return movement of the plate from position (d) to the neutral position (a). This third phase is also broken down into an acceleration step (Figure 5 / points P5 to P6), a step of moving the marble at constant speed (point P7 to P8) and a deceleration step until reaching the position point (a) with zero speed (Figure 5 / points P8 to Po10). During the return movement, the intermediate positions of the plate 2 at the end of the acceleration and displacement stages at constant speed do not correspond

  necessarily at positions (b) and (c) of the forward movement.

  The movement program 26 for controlling the motor M2 is parameterized by the designer of the cutting unit, at least with the points P0 to P10 (FIG. 5), which correspond to changes in the speed profile of the plate. In practice, other intermediate programming points are also inserted by the designer of the cutting unit D. Each point Pi corresponds to three pieces of information provided by the movement program 26 for the trajectory generator 25: position information ( Xi) characterizing the distance (for example in mm) of movement of the plate 2 from the previous position Pi.,; speed information (Qi) giving the speed of the rotor of the motor M2 (in rev / s) to obtain the required instantaneous linear speed of the marble at the position Pi; temporal information (Ti) characterizing the duration of movement of the plate 2 between the positions Pi-1 and Pi. It is up to the person skilled in the art, for a given installation, to judiciously program the points Pi of the path of the plate 2 for obtain the required reciprocation. It will simply be recalled that in the programming of these points Pi, three essential constraints must be respected: 1st constraint: the constant speed of movement of the marble in the cutting phase must be equal to the linear speed of the cutting cylinder 1., ie: for point P2 of the marble trajectory: Q2 (turn / s) = Qo.D1. N7 / D6.N8 with Q0 (speed of rotation in rev / s of the cutting cylinder 1), D, (diameter in mm of the cutting cylinder 1), D6 (diameter in mm of the pinion 6), N7. (Number of sprocket teeth 7), and N8 (number of teeth of

pinion 8).

  2nd constraint: the distance of movement of the marble during the cutting phase (parameter X3 of point P3 of the trajectory of the marble) must be greater than or equal to the dimension of the sheet in the machine direction. 3rd constraint: the distance from the plate must be equal to the distance

  return (X1 + X2 + X3 + X4 + X5 = X6 + X7 + X8 + X9 + Xo10).

  Kinematics of the launching device belt With reference to FIG. 6 (curve 11), each operating cycle of the launching device 3 is broken down into five phases, and is, in the same way as for the plate 2, synchronized by the 23 'synchronization signal (top synchronization) delivered by the encoder

incremental 21 'of the motor M1.

  Phase (1): the motor M3 drives the belt 9 at a first constant linear speed (point P'0 of the trajectory) which is equal to the speed

  linear V1 of the belts CT of the transfer device.

  Phase (2) [points P'1 to P'4]: acceleration of the belt 9 of the launching device until reaching a second constant linear speed which is equal to the limit speed V2 of the plate 2 in the cutting phase. Phase (3) [points P'4 to P'5]: drive of the belt 9 of the

launch at this second speed.

  Phase (4) [points P'5 to P'8]: deceleration of the belt 9 of the launching device until again reaching the first aforementioned first linear speed equal to the linear speed of the belts CT of the transfer device. Phase (5) [points P'8 to P'g]: drive of the belt 9 of the launching device at this first speed In a manner comparable to what was previously explained for the plate 2, the axis card 24 has been programmed by the designer of the cutting installation with at least the points (P'o to P'9) of the trajectory which is shown in solid lines in FIG. 6, and which is designated below as reference trajectory, each point P'1 being characterized by position information (X '), defining the distance (for example in mm) of movement of the belt 9 from the previous position Pi- ,, speed information (Q',) giving the motor rotor speed M3 (in revolution /: s) to obtain the required instantaneous linear speed of the belt 9 at position P ',, and time information (T') characterizing the duration of movement of the belt 9 between the positions P'Y-1 and P'i The reference trajectory (trajectory in tr has full in FIG. 6) which is initially programmed in the axis card 24 corresponds to an initial setting in position of each sheet relative to the cutting cylinder 1, which translates in practice by a determined initial position of the cutting in each sheet, relative to the front edge

(or back) of the sheet.

  With reference to FIG. 5, in order to allow an operator to modify the setting of a sheet relative to the cutting cylinder 1, by entering a new setting parameter (S), one of the input / output ports 28 of the card with axis 24 is connected, for example by a serial link of RS232 type, to input / output means 29 (operator interface), comprising input means such as a keyboard and display means (screen). The axis card 24 is also programmed to execute in the background a program 30, which permanently performs a scanning loop of the input / output port 28, and which upon detection 110 of the sending by the means of input / output 29 of a new timing parameter (S), interrupts its scanning loop, performs the calculation of a new value (T'1) for point P'1 of the path of the belt 9 of the device of launching, and of a new value (T'5) for the point P'5 of the trajectory of the belt 9 of the launching device, sends these new values of the parameters T'1 and T's to the movement program 26 driving the generator 25 associated with the motor M3, then resumes its scan loop of the input / output port 28, pending

  a new value for the setting parameter (S).

  FIG. 7 shows a sheet (F) having a cutout 31, which has been produced at an initial distance e given from the front edge 32 of the sheet F. This initial distance e corresponds to an initial setting of the sheet relative to to the support cylinder 1 (reference trajectory in solid line in FIG. 6). The setting parameter (S) is a distance of advance (negative value) or delay (positive value) compared to the initial distance (e) which is entered by the operator. In FIG. 7, reference has been made by the distance Sa, an example of distance in advance,

  and by the difference Sr an example of delay distance.

  The aforementioned program 30 of the axis card 24 is designed to calculate the new value of T ', by adding to the current value of T', a variation of time At calculated according to the following formula: At = S / (V2 - V1) with S having a negative or positive value (by 1? Example in mm) according to whether the stalling distance which has been entered is respectively a distance of advance or delay, V2 being the linear speed of advance (for example in mm / s) during the cutting phase, and V1 corresponds to the linear drive speed (for example in mm / s) of the belts CT of the transfer device. Conversely, the aforementioned program 30 of the axis card 24 is designed to calculate the new value of T'5 by subtracting from the current value of

  T's the variation of time At above.

  There are shown in dotted lines in FIG. 6, two examples of modification of the trajectory of the belt 9 of the launching device 3, consecutive respectively to the input of a feed distance Sa and

  a delay distance Sr with respect to the initial setting distance (e).

  In FIG. 6, the time values corresponding to the time variation At calculated automatically each time by the program 30 of the axis card 24 are indicated respectively Ta and Tr. It is understood in the light of these modified trajectories, that taking into account a new setting in position (parameter S) is carried out by automatically modifying in the operating cycle of the belt 9 of the launching device 3, the instant (point P'1) relative to the start of a cycle from which the belt 9 enters its acceleration phase (2), and correspondingly by modifying the duration of the phase (3) at constant speed, by decreasing or increasing the duration of this phase (3) as the entry point (P'1) was respectively delayed or advanced in the acceleration phase (2). These modifications allow automatic adjustment of the position of the cutout 31 in the sheet F.

Claims (8)

  1. Installation (D) for cutting sheet by sheet comprising a cutting cylinder (1), a tool-carrying plate (2) with reciprocating motion, and a device (3) for launching the sheets between the support cylinder ( 1) and the tool holder plate (2), and comprising a launching belt (9) which is driven by a motor (M3) controlled by electronic control means, and which allows, in synchronism with the movement of the carrier plate -tools and the rotation of the cutting cylinder (1), to accelerate each sheet from a first linear speed (Vl) to a second linear speed (V2) equal to the linear speed of the tool tray (2) during of the cutting operation, characterized in that it comprises means (28, 29, 30) allowing the entry by an operator of a setting parameter (S) characterizing the position of the cutting (31) in each sheet (F) relative to the front or rear edge (32) of the sheet (F), and in that the means engine control electronics (M3) are designed to control the motor (M3) over time, in position and speed   function of this setting parameter (S).   2. Installation according to claim 1 characterized in that the electronic motor control means (M3) control the motor (M3) according to a programmed path of points (P'1), each point P ', being characterized by position information (X '), defining the distance of movement of the launching belt (9) from the previous position Pi-.1, speed information (Q') defining the speed of the motor rotor (M3) for obtain the required instantaneous linear speed of the belt 9 at position P ',, and a time information (T'i) characterizing the duration of movement of the launching belt (9) between positions P' *. 1 and P ' i, and in that the electronic engine control means (M3) comprise a program (30) making it possible, with each modification of the setting parameter (S), to automatically calculate a new trajectory of points (P'i).   3. Installation according to claims 2 characterized in that the   trajectory calculation program (30) is designed to calculate a time variation (At) depending on the value of the setting parameter (S) which has been entered and the difference between the first (Vl) and second (V2) linear velocities, to calculate, by adding the calculated time variation (At), a new value for the time information (T ',) of the point (P'1) of the trajectory corresponding to the point of entry into the phase of acceleration of the launching belt (9), and to calculate by subtracting the calculated time variation (At), a new value for the time information (T'5) of the point (P'5) of the trajectory corresponding to the exit point of the training phase of the   launching belt (9) at constant speed (V2).   4. Installation according to one of claims 1 to 3 characterized in that   the motor (M3) is a brushless motor.   5. Sheet-by-sheet cutting line comprising a sheet-by-sheet cutting installation and a mechanical feeder for the introduction, one by one, of the sheets in synchronism with the rotation of the cutting cylinder (1) of the cutting installation, characterized in that installation   cutting (D) conforms to that referred to in one of claims 1   to 5 and in that the mechanical feeder (A) is mechanically coupled for its operation to the motor shaft (M1) driving the cutting cylinder (1) in rotation, without means for adjusting the position of the mobile elements (A1 , A2, A3) of the mechanical feeder by   relative to the angular position of the shaft of this motor (M1).   6. Device for launching a sheet at the entrance to a cutting unit and comprising a launching belt (9) which is driven by a motor (M3) controlled by electronic control means, and which allows, in synchronism with a synchronization signal (23 ') to accelerate each sheet from a first linear speed (Vl) to a second linear speed (V2), characterized in that it comprises means (28, 29,30 ) allowing the entry by an operator of a setting parameter (S) characterizing the position of the cutout (31) in each sheet (F) relative to the front or rear edge (32) of the sheet (F), and that the electronic engine control means (M3) are designed to control the motor (M3) over time, in position and in speed as a function of this parameter setting (S).   7. Device according to claim 6 characterized in that the electronic motor control means (M3) control the motor (M3) according to a programmed trajectory of points (P ',), each point P'i being characterized by position information (X '), defining the distance of movement of the launching belt (9) from the previous position Pi- ,, speed information (Q'1) defining the speed of the motor rotor (M3) for obtain the required instantaneous linear speed of the belt 9 at position P'i, and time information (T'1) characterizing the duration of movement of the launching belt (9) between positions P'i.1 and P ' 1, and in that the electronic engine control means (M3) comprise a program (30) allowing, with each modification of the setting parameter (S) to automatically calculate a new trajectory of points (P ',).   8. Device according to claims 7 characterized in that the program   (30) trajectory calculation is designed to calculate a variation of time (At) depending on the value of the setting parameter (S) that has been entered and the difference between the first (Vl) and second (V2) speeds linear, and to calculate, by adding the calculated time variation (At), a new value for the time information (T'1) of the point (P'1) of the trajectory corresponding to the point of entry into the phase of acceleration of the launching belt (9), and to calculate by subtracting the calculated time variation (At), a new   value for the time information (T'5) of the point (P'5) of the trajectory corresponding to the exit point of the drive phase of the launching belt (9) at constant speed (V2) .9. Device according to one of Claims 6 to 8, characterized in that the   motor (M3) is a brushless motor.