EP0739711B1 - Smooth press for a machine for producing cardboard - Google Patents

Description

The present invention relates to a baler in a so-called single-sided corrugated cardboard manufacturing machine sheet of fluting paper whose crests are glued on a first cover sheet. This intermediate box is also called single-sided. In a later double-sided machine, this first carton is either directly assembled to a second sheet of cover paper outside to give a cardboard called double-sided, either before assembled with a second single-sided carton to obtain a final carton called double-double.

In the single-sided machine, the groove paper is preheated and humidified before passing between two fluted cylinders which are heated with steam. The groove thus formed is maintained against the lower grooved cylinder by means of combs, or a system of the external environment, or a vacuum system of the interior of the lower grooved cylinder, the surface of which has slots of communication. A glue roller bathed in a glue tank deposits a predetermined amount of glue on the ridges of the grooves. The paper also preheated cover and the groove paper are finally pressure assembled between the lower grooved cylinder and a device support called a smoothing press.

The most commonly used baler consists of a smooth cylinder parallel to the lower grooved cylinder against which it is support. These two cylinders rotate at the same peripheral speed of such so that the cover and groove papers are fed so identical when assembled. The smooth cylinder is also supported against the grooved cylinder with a very large force so that the pressure at the contact thread is sufficient to burst the glue cells and to simultaneously firmly apply the paper cover against groove paper. Finally, this smooth cylinder is heated to further accelerate the setting of the glue. However, the major drawback of this smooth cylinder are the brutal and repetitive jolts produced at each passage of a groove in the lower cylinder, in particular due to the force necessarily important support. Not only these jolts damage the paper at the crest of the cardboard grooves, but they generate a loud surrounding noise. In addition, at certain speeds, it may produce resonance phenomena during which the cylinders can oscillate on their axis of rotation, making the sheets of paper are more correctly applied and glued. These jolts cause also premature wear of the grooves in the lower cylinder.

To overcome these problems, we proposed heald presses whose contact surface is greater than that between two grooves. According to a first solution mentioned in document US 4 481,066 and described in more detail in document FR 2 142 591, the baler consists of a cross member held at its ends by lower branches of levers, and the active face of which faces the cylinder lower grooved is arched in portion of cylinder of equal radius, even slightly higher than that of the grooved cylinder. By acting on upper branches of the end levers by means of a pair of cylinders, we can bring this arched face into contact with the grooved cylinder with a predetermined pressure. The edges of the active face can be folded outwards or be completed with deflection rollers for better drive the cover sheet. This cross member can also be hollow for the passage of heating steam. However, less balanced and less rigid than a cylinder, such a cross member can twist and / or warp making that the application pressure is no longer uniform over the entire length of the grooved cylinder. The quality of the gluing is then greatly altered.

In document US 4,481,066, it is further mentioned that the support of the arched cross member induces significant friction forces in the cover paper. The scrolling of this cover paper is then slowed down compared to that of the fluting paper to the point of having to install, leaving the machine, a cardboard tractor device essentially acting on this cover paper to compensate for its delay. However, this device is only intended for speed compensation. In addition, this device is heavy and complex because it is formed of a plurality of endless bands side by side passing over a depressurized box, each strip having suction ports.

According to a second solution mentioned in the document FR 2 142 591 and better described in the document DE 25 27 819, the baler consists of an endless band passing between upper rollers and lower located parallel and close to the lower grooved cylinder, respectively at mid-height and below. This strip is thus in contact with the grooved cylinder on a quarter of the lower periphery. This band endless can be a thin strip of steel or a carpet of copper wires, cotton or synthetic fibers.

However, the pressure applied to the sheets by this baler depends on the tension applied to the endless belt. It is therefore advisable to provide a complex mechanical spacing device for one of the rollers of the endless belt compared to the other, and this with the possibility of adjustment of this large voltage to a specific value. Again, it's impossible to maintain a constant tension throughout the width of the endless strip, therefore a uniform application pressure of the sheet of cover against the flute sheet.

The object of the present invention is a heald press in a more efficient single-sided corrugated machine in particular by constantly applying uniform pressure to full width of a cover sheet joined to a sheet of groove passing around the lower grooved cylinder. The document DE 43 05 158 describes a device for regulating the bearing force of a cylinder upper arm against a lower grooved cylinder. In this device, the smooth cylinder is mounted on both sides on a pair of levers, both upstream ends of the levers being rotatably mounted on an axis integral with the frame, while the two downstream ends each rest on a stop vertically movable under the control of a corresponding motorized cam. On each side, a constant pressure hydraulic actuator exerts a vertical force pointing down also on the downstream end corresponding lever. On both sides, a force detector inserted between the stop and the downstream end of lifting measures the resulting force towards the lower cylinder weight and actuator support more or less compensated upwards by the feedback of the grooved cylinder. If the force result differs from a set value, the position of the cam is modified, which raises or lowers the stop and end of the lift, so changes the smooth cylinder feedback. However, this device is essentially designed to regulate a support load from a single global measurement very important capable, at the level of a single contact net, of bursting glue cells and assemble the papers. The force detectors are so chosen so that you can read important values with their precision given. In a low load regulation application, the force sensor would read the maximum force almost permanently resulting from the weight of the cylinder and the support of the actuators, and would absolutely insensitive to any variation in low load. In addition, variations in the apparent weight of the cylinder due to changes in tension cover paper, or a drift in actuator pressure may completely deceive the feedback. In addition, the baler must allow the adjustment of the application pressure to a fair value necessary and sufficient to obtain the effective setting of the adhesive without damaging the leaves. Finally, the design of this smooth press must be relatively simple to ensure operational reliability in the time and ease of implementation and maintenance at cost reasonable.

These goals are achieved with a heddle press comprising a smooth cylinder acting in conjunction with a lower grooved cylinder to apply a cover paper against a passing groove paper around this grooved cylinder, this press further comprising a device tractor downstream of the lower grooved cylinder, located in relation to the cylinder smooth so that there is a tying angle for the paper cover against the grooved cylinder, this tractor device applying to the cardboard a tension of tension repercussions in the form of a pressure of cover paper against groove paper at surface level lashing, characterized in that the linear bearing load of the cylinder smooth against the lower grooved cylinder is regulated to a low value between 0 to 7 N / mm and in that the smooth cylinder is mounted between a pair of levers underlying the grooved cylinder, pair of levers whose two ends on the same side are rotatably mounted on an axis secured to the smooth press frame, while the other two ends opposite levers are each carried by a pressure actuator constant through a first force detector, the upper edge of each lever abutting against a motorized cam through a second force detector.

By lashing angle is meant the angle at the top of the arc of circle defining, in a vertical plane transverse to the grooved cylinder, the contact surface, in a cylinder portion, between the cover paper and the grooved cylinder, surface also called tying surface. Voltage tensile force is defined as the tensile force per unit width of papers. Similarly, the linear bearing load is defined as the bearing force per unit of width exerted by the smooth cylinder on its thread contact with the grooved cylinder.

According to a preferred embodiment, the tractor device is supplemented by a parallel flexible roller with additional support acting on the fluting paper.

Advantageously, the contact between each lever and its stop is located at the contact thread between the smooth cylinder and the grooved cylinder.

According to another embodiment, the axis of rotation of the levers is located at the same height as the axis of the smooth cylinder, and in that the paper cover is guided by an upstream roller so as to enter contact with the smooth cylinder at its lower generator for the leave at the level of its upper generator. The tractor cylinder is supplemented by a parallel flexible roller with additional support acting on the fluting paper, and this to limit the sliding of the cardboard to the strict necessary.

• faire lever par les actuateurs les leviers et le cylindre lisse pour lire la valeur des premiers détecteurs influencés que par le poids de ses organes, puis recalibrer ces lectures à une valeur nulle,
• faire buter chaque levier par son actuateur contre sa came avec une force Fh lue sur le premier détecteur associé, relever la force de contre-réaction Fb de la butée correspondante telle que lue par le second détecteur, et établir, au niveau de l'axe de rotation des leviers, l'égalité des couples Fh x Lh = Fb1 x Lb, dans laquelle Lh et Lb sont les entre-axes respectivement de l'actuateur et de la came,
• modifier la position de chaque came pour appuyer le cylindre lisse contre le cylindre cannelé créant de part et d'autre une force de contre-réaction Fp du cylindre cannelé diminuant celle de la came en obtenant la nouvelle égalité des couples Fh x Lh = (Fb2 x Lb) + (Fp x Lp), où Lp est l'entre-axe du filet de contact du cylindre lisse avec le cylindre cannelé et Fb2 la nouvelle lecture du second détecteur,
• asservir la position de chaque came à la lecture du second détecteur Fbi de telle sorte à maintenir de part et d'autre la force Fp à une valeur constante telle que : 2 x Fp / largeur de papier = q charge linéaire désirée.

The method of regulating the linear bearing force used in this smooth press consists in:

• have the levers and the smooth cylinder lifted by the actuators to read the value of the first detectors influenced only by the weight of its organs, then recalibrate these readings to a zero value,
• make each lever abut by its actuator against its cam with a force Fh read on the first associated detector, note the feedback force Fb from the corresponding stop as read by the second detector, and establish, at the axis lever rotation, equal torque Fh x Lh = Fb1 x Lb , in which Lh and Lb are the axes between the actuator and the cam respectively,
• modify the position of each cam to press the smooth cylinder against the splined cylinder creating on both sides a feedback force Fp of the splined cylinder decreasing that of the cam by obtaining the new equality of the torques Fh x Lh = (Fb2 x Lb) + (Fp x Lp) , where Lp is the inter-axis of the contact net of the smooth cylinder with the grooved cylinder and Fb2 the new reading of the second detector,
• slaving the position of each cam to the reading of the second detector Fbi so as to maintain the force Fp on both sides at a constant value such that: 2 x Fp / paper width = q desired linear load .

In other words, we start by squeezing each lift between a support actuator and a stop with a first holding force Fh avoiding any strong or vibration, regardless of the weight. Then we transfers part of this clamping force in a controlled manner bearing force of the smooth cylinder against the grooved cylinder. So the determination of the feedback of the grooved cylinder is carried out by a differential measurement giving excellent resolution compared to an absolute measure including values assumed, wrongly, constant. By example, the two force sensors can be strain gauges whose resistance variations are detected within a circuit electric called Wheatstone Bridge.

Usefully, the contact between each lever and its stop is located at the contact thread between the smooth cylinder and the grooved cylinder. Thus, the second detector is directly influenced by the feedback from the grooved cylinder, which avoids any random disturbance. We then obtain the equality of the inter-axes Lb = Lp .

Preferably, the axis of rotation of the levers is located at the same height as the axis of the smooth cylinder, and the cover paper is guided by a upstream roller so as to come into contact with the smooth cylinder at level of its lower generator to leave it at the level of its generator higher, i.e. the two generators belonging to the same plane vertical center of the cylinder. Thus, the harmful effects of variations in tension in the cover paper on the apparent weight of the smooth cylinder are annihilated.

The invention will be better understood when studying a mode of realization taken on a nonlimiting basis, and illustrated schematically from the side in the appended figure in which is shown a so-called single-sided manufacturing intended for the manufacture of a carton 6 also called single-sided consisting of the assembly of a fluting paper 2 and cover paper 4.

More precisely, the fluting paper 2 arrives from above and travels a first U-turn around an upper grooved cylinder 10. This paper 2 is grooved at the level of the engagement of the upper cylinder 10 with a second lower grooved cylinder 12. The groove paper 2 as well formed is held against this lower cylinder 12 during a second half-turn downwards by a device not illustrated which can be combs, a external overpressure created in a casing or a depression internal to the lower grooved cylinder with radial openings allowing the suction of the paper. During this second U-turn, a roller sizing machine 13 deposits a line of glue on each groove crest.

In addition, a cover paper 4 is guided by a roller upstream 11 to arrive horizontally towards a lower smooth cylinder 14 with which it comes into contact tangentially at its generator lower. This paper is preheated when it rotates half a turn towards the high around this smooth cylinder which it leaves at the level of its generator superior when applied well parallel to the paper flute 2 wound on the lower fluted cylinder 12.

More particularly according to the invention, the cardboard 6 thus formed and leaving the grooved cylinder 12 is pulled downstream by a grille made up of a traction cylinder 16 surmounted by a flexible support roller 18. The cardboard 6 is thus wrapped by its more solid cover paper 4 around the upper half of the traction cylinder 16. The contact pressure between this carton and this traction cylinder is reinforced by the support of the roller 18 acting against the more fragile fluting paper. For this, this roller support includes an elastomer periphery connected to its central shaft by a series of longitudinal radial fins also made of elastomer, the cross section is oblique, even curved.

The traction cylinder 16 rotates at a peripheral speed 4 to 6% greater, for example 5%, than the speed of the cardboard as imposed downstream by the common peripheral speed of rotation of the smooth cylinder and grooved cylinder 12. This slight speeding implies a sliding friction of the cylinder with respect to the cardboard, which induces in the entire width of the cardboard strip a tensile tension (f).

However, as well illustrated in this figure, the tractor cylinder 16 is arranged parallel and close to the first upper grooved cylinder 10 of so as to increase the contact surface between the cardboard just formed and the lower grooved cylinder 12 at least at a lashing angle greater than 25 °, in this case practically equal to 45 °. In this surface contact in the cylinder portion, the tension of tension (f) is reflected under the form of a pressure (p) which keeps the paper cover 4 against the fluting paper 2 when setting the glue which can therefore be carried out more completely and more effectively.

Unlike the heald presses according to the state of the art, it is not then more useful that the smooth cylinder 14 is excessively pressed against the lower grooved cylinder 12 with all the drawbacks mentioned previously. According to the invention, this smooth cylinder is brought in and automatically kept close to the grooved cylinder with just clearance (h) sufficient to make the first application of the cover paper under a low load of the order of 0 to 7 N / mm, preferably between 3 and 5 N / mm. This charge is sufficient to burst and trigger the glue cells without any risk for papers and cylinders.

For this, the axis of rotation 17 of the smooth cylinder 14 is maintained from on both sides by levers 50 movable in rotation in one of their ends, preferably on the supply side of the cover paper 4, at a axis 52 secured to the frame of the machine. The other end of each lift 50 is supported by a hydraulic cylinder 60 through a first force detector 62. As illustrated, the axis of articulation of the levers 52 being at the same height as the axis of rotation 17 of the smooth cylinder 14, the action of the cylinder 60 is essentially an ascent or descent of the smooth cylinder 14 vertically, allowing this cylinder to come into contact with the lower grooved cylinder 12 according to a coinciding contact thread respectively with the upper and lower generators. In addition, this equal height of the axes of rotation means that a variation in tension at within the cover paper, resulting in a force on the cylinder also horizontal, does not create any torque at the articulation axis 52 risking inadvertently going up or down this smooth cylinder 14.

At the contact thread between the grooved cylinder 12 and the smooth cylinder 14, the upper edge of the levers 50 is in constant support on a linear cam with oblique face 70 through a second detector force 63. As illustrated, this cam 70 can be moved horizontally by a motor 72 mounted on the lever 50. The threaded outlet axis 74 of the motor 72 is engaged in a tapping of the cam 70. With this cam 70, we can impose on a very precise value the spacing (h) desired between these two cylinders.

Thanks to the presence of the two force detectors 62 and 63, the automatic gap regulation (h) can be performed on the base of a differential measurement according to the following method.

Firstly, the cylinder 60 lifts the cylinder. 14 and the levers 50 without the latter touching the linear cam 70. The first reading of the force detector 62 then corresponds to the only weight of its organs, which reading is memorized for subsequent subtraction, this which eliminates any influence of this weight in the rest of the process.

Then, the jack 60 presses the levers 50 against the linear cam 70 with an upwardly directed force Fh, the cam 70 being sufficiently advanced so that the smooth cylinder 14 is not in contact with the papers and the lower grooved cylinder 12. Then, the feedback of the cam 70, as read by the second force detector 63, implies a value Fb such that, at the level of the articulation axis 52 of the levers 50, an equality of torques is obtained. Fh x Lh = Fb x Lb . This is the tightening torque holding the levers 50 firmly in position.

Subsequently, the linear cam 70 is partially withdrawn so that the smooth cylinder 14 presses the cover paper 4 against the flute paper 2 with a linear load q therefore a feedback force Fp = qx La , where La is the width of the papers. Half of this force comes from both sides to correspondingly reduce the feedback exerted by the linear cams 70, resulting in a second reading Fb2 lower than the first Fb1. In other words, in order to apply only a weak charge q, it is necessary to maintain the reading of the second force detector 63 at a set value Fbcons Fbcons = 1 / Lb [Fh x Lh - (1/2 qx La) x Lb] and this by advancing or retreating as much as necessary the linear cam 70 by means of its motor 72 and output axis 74.

Many improvements can be made to this heald press within the scope of the claims.

Claims (5)

1. Smooth press in a single-face machine for manufacturing corrugated cardboard (6), said smooth press comprising a smooth cylinder (14) acting conjointly with a lower corrugating roll (12) in order to apply a cover paper (4) against a fluted paper (2) passing around said corrugating roll (12), additionally comprising a traction device (16) downstream from the lower corrugating roll (12), situated with respect to the smooth cylinder (14) so as to present a tension angle (e) of the cover paper (4) against the corrugating roll, said traction device applying to the cardboard (6) a traction tension (f) reflected in the form of a pressure (p) of the cover paper against the fluted paper at the level of the tension surface, characterized by the fact that the linear support load (q) of the smooth cylinder (14) against the lower corrugating roll (12) is regulated at a low value, from 0 to 7 N/mm, and in that the smooth cylinder (14) is mounted between a pair of levers (50) subjacent to the corrugating roll (12), the two ends on the same side of the said pair of levers (50) being rotationally mounted on an axle (52) fixedly attached to the frame of the smooth press, while the two other, opposite ends of the levers (50) are each held by an actuator (60) at a constant pressure across a first force detector (62), the upper edge of each lever (50) coming to rest against a motorized cam (70, 72) across a second force detector (63).
2. Smooth press according claim 1, characterized by the fact that the traction device (16) is provided with a complementary parallel flexible support roller (18) acting on the fluted paper (2).
3. Smooth press according claim 1, characterized by the fact that the contact between each lever (50) and its stop (70) is situated at the level of the line of contact between the smooth cylinder (14) and the corrugating roll (12).
4. Smooth press according to claim 1, characterized by the fact that the rotational axle (52) of the levers (50) is situated at the same height as the axle (17) of the smooth cylinder (12), and in that the cover paper (4) is guided by an upstream roller (11) so as to enter into contact with the smooth cylinder (12) at the level of its lower generating line and to leave it at the level of its upper generating line.
5. Method for regulating a smooth press according to claim 1, characterized by the fact that it consists in :

   lifting, by means of actuators (60), of the levers (50) and the smooth cylinder (12) in order to read the value of the first detector (62), affected only by the weight of these organs, and then recalibration of these readings to a zero value,

   bringing each lever (50) to rest against its cam (70) by means of its actuator (60) with a force Fh, read from the first associated detector (62), relieving the force of counter-reaction Fb of the corresponding cam as read by the second detector (63), and establishing, at the level of the rotational axle (52) of the levers, the equality of the torques Fh x Lh = Fb1 x Lb, where Lh and Lb are the center axis distances respectively of the actuator and of the cam,

   modifying the position of each cam (70) so as to support the smooth cylinder (14) against the corrugating roll (12), creating on both sides a force of counter-reaction Fp of the corrugating roll, diminishing that of the cam while obtaining the new equality of the torques Fh x Lh = (Fb2 x Lb) + (Fp x Lp), where Lp is the center axis distance of the line of contact of the smooth cylinder with the corrugating roll and Fb2 is the new reading of the second detector,

   controlling the position of each cam (70) to the reading of the second detector (63) Fbi so as to maintain, on both sides, the force Fp at a constant value such that : 2 x Fp / width of the paper = q desired linear load.

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