EP0453986B1 - Method for controlling the parallelism of two beams of a press - Google Patents

Abstract

The invention concerns a process for regulating the parallelism of two beams of a cutting press designed for converting sheet or weblike matter into a package. The press comprises a frame made of a lower crossbar and an upper crossbar, connected to one another by means of lateral posts. An upper beam is fitted on the upper crossbar. A lower movable beam is raised and lowered with each operating cycle by means of a drive system supported by the lower crossbar by means of bearings. The bearings can be shifted vertically when the drive system is situated in a lower dead center position in such a way as to regulate the parallelism of the lower beam with regard to the upper beam. When the press accomplishes its operating cycle, a deviation e from parallelism is measured when the drive system is situated in an upper dead center position. When the lower dead center is reached, the bearings are shifted vertically so as to have the lower beam tilt in a direction contrary to the tilt resulting from the deviation of parallelism measured in the upper dead center position.

Description

The present invention relates to a cutting press, in particular that used for cutting sheet or strip material for the production of packaging, and as defined in the preamble of claim 1.

For the cutting operation, the movement, from bottom to top and from top to bottom, of the lower bed of such a press can be carried out using a system with four connecting rods - cranks, or with four knee pads - cams. The top dead center of the drive system corresponds to the working position, for example of cutting, of the press, position in which the counter-tool fixed on the lower movable bed base is pressed against the tool carried by the upper bed base.

To increase production, such presses are so designed that, during the same working operation, several cuts or blanks of the same shape and dimensions can be obtained simultaneously from a single sheet whose total area is at least equal to that of the addition of all the cuts. It follows that the tool and the counter-tool are each in the form of a plate, in principle rectangular, of large dimension, carrying on one side the working members, the other side coming to be pressed against one side. of the corresponding box spring, face whose surface will be at least equal to, if not greater than, that of the tool or counter-tool.

However, since the condition necessary for obtaining perfect cutting over the entire surface of the cardboard sheet to be cut lies in perfect parallelism between tool and counter-tool, this condition can only be fulfilled if the two surfaces of the bed bases, carrying the tool and the counter-tool, that is to say the active surfaces, are also perfectly parallel to one another, this at least at the precise instant of cutting, that is to say at the top dead center of the drive system.

A method of adjusting the parallelism of two bed bases of a cutting press in which, for each work cycle, at least one bed base is movable relative to the other between a first position where they are spaced apart and a second the position in which they are in pressure contact is known from the publication 215 VDI-Zeitschrift 128 (1986) Apr., No. 7, Düsseldorf, Deutschland. This document also shows that it is planned to use means for adjusting the parallelism of the bed bases with one another following a measurement of a parallelism error carried out when the bed bases are in the pressure position and the adjustment parallelism takes place in a direction which corrects said measured error.

Still with a view to obtaining the parallelism of the two bed bases of a press, it was proposed in patent CH-A-575814 to act at the level of the four bearings which fix the rod-crank system on the lower cross member of the frame of the press. The bearings are mounted vertically movable using a set of trapezoidal keys placed in pairs between each bearing and the bottom of a slide provided in the lower crossmember. By moving the keys, it is possible to vary the height position of the bearings and thus of the lower movable base. By a judicious choice of the height adjustment of the four bearings, one thus obtains a first parallelism, which must then be completed by the so-called "placing" operation which consists in placing short pieces of a narrow strip of adhesive paper on the rear face of the tool, facing the cutting threads or other working members, so as to compensate for the residual lack of parallelism and also the error caused by the cutting threads themselves. However, the "setting" has the disadvantage of requiring a lot of time and qualified personnel.

The patent CH-A-652967 describes a cutting press in which the drive system of the lower movable bed base is produced using a system with four cam-type knee switches. The parallelism between the two bed bases is obtained using a single key slid between the bearing of each toggle joint and the bottom crossmember of the frame. In this case, the "bet" operation is also necessary.

In addition, since a cutting press is also designed so that the same tool can be used for sheets of various sizes, the sheet generally only occupies part of the total area of the tool . However, because the sheet is generally placed, during its cutting, on the side of the downstream edge (with reference to the direction of travel of the sheet) of the tool, this only partial occupation of the active surface of the tool causes an imbalance in the distribution of the cutting pressure, imbalance which will propagate on the lateral uprights of the frame, causing different elongations there for each of them, and thereby a lack of parallelism between the two box springs.

This imbalance in the distribution of forces has the serious drawback of causing premature wear of the cutting threads.

To compensate for this imbalance, recourse is generally had to the "setting" described above, and also to at least one form of compensation provided with a few cutting nets or other working members, and mounted on the side of the upstream edge of the tool, so as to obtain the parallelism of the tools. However, even in this case, the "placing" operation is too important.

So, as it is common for a cutting press to work on sheets of reduced size, it is obvious that if the "stake" could be eliminated, or at least reduced as much as possible, a very appreciable time would be saved in the preparation of the tool.

Consequently, the present invention essentially aims to achieve an adjustment of the parallelism of the two bed bases of a cutting press which makes it possible to obtain perfect parallelism between the two bed bases under pressure and thus shorten the preparation time of the tool by almost completely eliminating the "putting" and the use of forms of compensation.

This object is achieved by a method according to claim 1 and a cutting press according to claim 2.

• la figure 1 représente une vue de côté, en coupe partielle, d'une presse à découper;
• la figure 2 représente, schématiquement, le déplacement relatif entre les deux sommiers d'une presse à découper lors d'essais sous pression;
• la figure 3 représente une vue de dessus, en coupe selon III - III de la figure 1;
• la figure 4 représente une vue de côté, en coupe partielle selon IV - IV de la figure 1; et
• la figure 5 représente un schéma fonctionnel de commande de deux moteurs destinés au réglage du parallélisme des sommiers.

An embodiment of the invention is now described with reference to the accompanying drawing in which:

• Figure 1 shows a side view, in partial section, of a cutting press;
• FIG. 2 schematically represents the relative displacement between the two bed bases of a cutting press during pressure tests;
• Figure 3 shows a top view, in section on III - III of Figure 1;
• 4 shows a side view, in partial section along IV - IV of Figure 1; and
• FIG. 5 represents a functional diagram of the control of two motors intended for adjusting the parallelism of the bed bases.

Figure 1 shows a cutting press comprising a frame consisting of an upper crosspiece 3, a lower cross member 1 and lateral uprights 2 connected to the cross members 1, 3, using screws 26 and rails 25 engaged with corresponding grooves made in the cross members 1, 3. An upper bed 5 is fixed on the upper cross member 3. On the lower surface of the bed base 5 is mounted a tool 4. A lower movable bed base 6, displaceable by means of a drive system with four toggles 20a, 20b, and cams 24. The knee pads 20a, 20b are supported, using bearings 33a, 33b, on the lower cross member 1. The four knee pads are distributed in two pairs, one of which 20a is located on the side of introduction of the sheet 7 into the machine , that is to say on the upstream side, and the other pair 20b on the outlet side, ie downstream.

In the following, it will be added, when necessary for the understanding of the invention, the index a to the reference signs which relate to the elements located upstream, and the index b to the elements located at the downstream. In addition, the upstream-downstream direction will be called the longitudinal direction of the machine, and the one perpendicular to it transverse direction.

At the instant of the top dead center of the drive system, corresponding point, as already mentioned above, at the time of cutting proper, the sheet 7, brought previously by means of a clamp bar 8 moved to the using a side chain train 10, on a counter-tool 9 located on the lower movable base 6, is pressed against the tool 4. In such a press, the sheet 7 is necessarily placed on the side of the downstream edge of the tool 4 so that the gripper bar 8 is located, at the time of cutting, outside the space between the two bed bases 5, 6.

The bearing 33a, 33b of each toggle joint 20a, 20b is mounted vertically movable in a groove or groove 35a, 35b forming a slide and provided in the lower cross member 1. Between each bearing 33a, 33b and the bottom of the slide 35a, 35b is interposed a key 18a, 18b of trapezoidal shape and arranged so that its transverse movement allows an adjustment in height of the corresponding bearing 33a, 33b, and thus an adjustment of the working pressure, as well as an adjustment of the parallelism of the two bed bases 5 , 6 between them, as already described above.

It is here useful to recall that, until now, the parallelism adjustment consisted in adjusting, at the top dead center of the toggle joint system 20a, 20b, the height position of the bearings 33a, 33b using the keys 18a , 18b moved individually or in pairs upstream and downstream. In other words, at bottom dead center, the lower movable base 6 was positioned exactly parallel to the upper base 5. Then, by displacement of the four keys 18a, 18b in the same direction and according to the same amplitude, the desired pressure setting was obtained for work.

If, to date, the pressure adjustment using the keys 18a, 18b has been obtained satisfactorily, this has not always been the case with regard to the adjustment of the parallelism between the two bed bases 5, 6. Indeed, even after adjusting the parallelism as precise as possible, it turned out that the thickness of "setting" in certain places of the tool 4 was still too large. This therefore meant that, even if the two bed bases 5, 6 were perfectly parallel at the time of the start of the stroke of the lower bed base 6 upwards, this parallelism disappeared at the instant of top dead center of the drive system 20a, 20b, that is to say at the precise instant when the cutting pressure acted on all of the elements of the press frame.

It is by researching the causes of this modification of the parallelism between bed bases 5, 6 that it has become apparent that the dimension or the format of the sheet to be worked plays a much more important role than had hitherto been imagined. Indeed, as already mentioned above, the sheet 7, of dimension smaller than that of the tool 4, is placed near the downstream edge of the tool 4 and centered transversely relative to the latter.

Tests have been carried out to study the variations in the parallelism of the two bed bases 5, 6 of a cutting press as a function of the format of a sheet to be cut. In Figure 2, the results of one of these tests are shown. In the horizontal plane, the tool 4 of length AB (or A'B ') is shown schematically in the longitudinal direction and of width AA' (or BB '), as is the sheet of length AC (or A'C ') and of width AA' (or BB '). The length of the tool 4 is 100 cm, that of the sheet 50 cm, while their width is identical and equal to 140 cm. The sheet 7 is therefore half-size relative to the tool 4.

The test consisted first of all in establishing, using jacks arranged between the two bed bases 5, 6, a pressure of 3 Mn uniformly distributed over the entire area of the two working surfaces of the two bed bases 5, 6, the sheet 7, of half format, being arranged in the downstream part of the tool, and then measuring, at different points of the working surfaces, the relative displacement of a bed base with respect to the other. In Figure 2, this relative movement is shown vertically. The test was of course carried out at the time of top dead center of the knee pads 20a, 20b, so as to best simulate the real working conditions of the press. From Figure 2, it is clear that there is a very strong tilting of the lower face of the upper base 5 relative to the upper face of the lower base 6, this tilting taking place almost only in the longitudinal direction, and not transverse. The measurements revealed that the difference Δ1 between the value of the displacement at the level of the downstream edge AA 'of the sheet 7 and that of the upstream edge CC' was of the order of 360 μ. However, this value is precisely that which gives an order of magnitude of the "stake" to be made to compensate for the lack of parallelism. For the specialist, it is obvious that "betting" such a large difference in height and over a large part of the surface area of the format is a delicate operation which requires a lot of time.

Tests have also been carried out with transversely reduced sheet sizes. However, it has been found that, in this case, the transverse tilting of a bed base with respect to the other is so minimal, in comparison with the longitudinal tilting that it can generally be neglected. In other words, it is essentially the fact of working with cardboards in a reduced format that causes the need to have recourse to a significant "bet" to compensate for the lack of parallelism of the two box springs of a cutting press.

Consequently, the tests described above have also shown that the adjustment process, in progress to date, which consisted in acting on the position in height of the bearings 33a, 33b of the drive system 20a, 20b, so that the lower movable base 6 is perfectly parallel to the upper base 5 at the instant of bottom dead center, was not suitable for work at reduced format, since, in any case, this same reduced format almost entirely destroyed this parallelism at the time of top dead center.

The basic idea of the invention which has led to the solution of the problem posed above, consists in causing the lower movable bed base 6, during its upward movement, to tilt in a manner opposite to that which so far, that is to say, placing the lower base 6, when it is at bottom dead center, inclined relative to the upper base 5 so that when it reaches top dead center, under the effect of the working pressure forces at play, these same beds 5, 6 become parallel to each other.

However, it remained to be determined according to what criteria and with what amplitude the lower bed base 6, at bottom dead center, had to be tilted relative to the upper bed base 5. To stay as close as possible to the actual working conditions of the press, it was decided to measure directly, at different points, the distance between the two working surfaces of the box springs 5, 6 at the precise instant when the cutting force is maximum, that is to say at top dead center, to then compare these measurements between them to determine the direction and the amplitude of the tilting, and to finally place, that is to say before the actual cutting operation, the lower base 6 according to an exactly opposite tilting and of identical amplitude or, in any case, proportional to that measured.

From the considerations above on the subject of the tilting in question, it immediately appears that, in the case which concerns us essentially, namely that of cutting a sheet of reduced format and transversely centered on the tool, it suffices, in done, to measure the distance in question in two places, one of which is located between the upstream edges, and the other between the downstream edges of the other two bed bases 5, 6. For this purpose, the upper bed base 5 is equipped with two proximity sensors P₁, P₂, fixed by means of brackets 17a, 17b at the bottom of the vertical transverse faces upstream and respectively downstream of this same base 5, this opposite a location of the lower base 6 which is not covered neither by the gripper bar 8, nor by the sheet 7 and neither by the counter-tool 9. When therefore the lower movable bed base 6 will be pressurized against the upper bed base 5, the two sensors P₁, P₂ will indicate exactly the distance between the upstream edges, respectively t downstream, of the two bed bases 5, 6. A comparison of the two values provided by the two sensors P₁, P₂ will make it possible to define the tilting in question.

It is interesting here to recall that the parallelism measurements are carried out at the very place of production and at the moment when the first sheets of a new series to be cut are introduced by the clamp bars 8 between the two box springs 5, 6 of the press. Those skilled in the art will already appreciate the simplicity of implementing the measurement here. Of course, given the infinitesimal values at play, of the order of a few hundred microns, the measured values will in principle be displayed on a screen (not shown).

It now remains to modify the height of the four bearings 33a, 33b of the knee pads 20a, 20b so as to obtain a tilting of the lower base 6 - in principle from a position parallel to the upper base 5 - which is opposite and proportional to that measured. by sensors P₁, P₂. Several possibilities are offered here.

It should first be noted that one of the first solutions which could come to mind would consist in introducing into a comparator the two values emitted by the sensors P₁, P₂, to display their difference and to vertically move the bearings 33a, 33b until the displayed difference becomes zero. This solution is however impracticable; in fact, since such an adjustment must be made at top dead center, that is to say under full working pressure, it is impossible to act at this instant with sufficient force at the bearings 33a, 33b, using keys or other means, to cause an ascent or descent of each of the knee pads 20a, 20b. The adjustment can therefore only be made around the bottom dead center, as has always been the case up to now.

Furthermore, from the above considerations according to which the longitudinal tilting, that is to say from upstream to downstream, must be taken essentially into consideration, it is possible to deduce that the two bearings of each upstream pair 33a and downstream 33b each located under the two upstream knee protectors 20a, respectively downstream 20b, must in principle be adjusted in height simultaneously and identically. To obtain the simultaneous displacement either of the pair of upstream keys 18a, or of the pair downstream 18b, an advantageous solution consists in mounting each pair 18a, 18b on a square bar 34a, respectively 34b, movable along the slide 35a, respectively 35b, as described in patent CH-A-575814. By a displacement of each of the bars 34a, 34b is also obtained a simultaneous displacement of the two upstream keys 18a, respectively downstream 18b.

To make and measure the displacement of the bar 34a, there is provided a motor M₁ and a linear position sensor C₁, as shown in FIGS. 3 and 4 in which the two upstream keys are also shown schematically (in dashed lines) 18a fixed in a known manner to the bar 34a, as well as the two bearings 33a. In FIG. 1, the motor M₂ and the linear position sensor C₂, relating to the bar 34b, are not shown, but replaced by a section along L - L in FIG. 4. The bar 34a is provided at its end ( in principle located on the operator's side) of a threaded part 50 engaged with a corresponding internal thread of a hollow axis 51 rotatably mounted, using a plain bearing 52, inside a bearing 53 fixed, by means of screws 54, to the lower cross member 1 of the frame. The hollow axis 51 is provided with a flange 51c. A first toothed wheel 55, provided with a hub 56, is locked in rotation with the hollow axis 51 by means of screws 70 which pass through the hub 56 and the flange 51c. The hydraulic motor M₁ is fixed on a main support 58 using screws 69, the support 58 itself being fixed to the lower cross member 1 by means of screws 59. On the output shaft 57 of the motor M₁ is mounted keyed a second toothed wheel 60 engaged with a gear located inside a free hollow sleeve 61. An auxiliary shaft 63 is rotatably mounted in a corresponding bore of the support 58 and in the extension of the output shaft 57 of the motor M₁. On a first end of the auxiliary shaft 63 is keyed a toothed wheel 62 engaged with the internal gear of the hollow sleeve 61, while on the other end is keyed a first toothed pinion 64 engaged with the first wheel toothed 55. From FIG. 3 it is possible to see that, by rotation of the pinion 64 by means of the motor M₁, in one direction or the other, there is caused a corresponding displacement of the bar 34a and therefore of the upstream keys 18a .

In order to be able to carry out a manual drive of the output pinion 64, an auxiliary pinion 65 is also provided, in engagement with the output pinion 64 and mounted keyed on an axis 66 rotatably mounted inside a corresponding bore of the support 58. The axis 66 emerges by a hexagonal part 67 from the support 58 to allow manual rotation drive using a key.

In order to measure the displacement and the position of the bar 34a, it is extended (in principle also on the side of the operator, that is to say on the side of its threaded part 50) by a rod 80 passing freely through a corresponding bore executed in the hub 56 of the toothed wheel 55. At the free end of the rod 80 is fixed a plate 81. The end of the output rod 82 of the linear position sensor C₁ is fixed in an adjustable manner to the plate 81. The linear sensor C1 is mounted in an adjustable position on an auxiliary support 85 fixed to the main support 58. On the support auxiliary 85 are also mounted in an adjustable manner two end-of-travel stops 83, 84 which have the function of causing the power supply to the system to be cut in the event that the bar 34a has to move outside the travel defined by these two stops 83, 84. A graduated ruler 87, fixed on the auxiliary support 85 near the plate 81, gives the operator a first visual approximation of the displacement and of the position of the bar 34a.

To make and measure the displacement of the downstream bar 34b, a construction identical to that described above for the upstream bar 34a is used, with this difference however, that the hydraulic motor is indicated by the reference M₂, and the position sensor linear C₂.

• le moteur M₁ déplace les clavettes amont 18a, c'est-à-dire la barre amont 34a;
• le moteur M₂ déplace les clavettes aval 18b, c'est-à-dire la barre aval 34b;
• le réglage de la pression de travail, effectué au point mort bas, est initialisé par l'introduction d'une consigne de position x correspondant à la pression de travail désirée, consigne identique pour les deux capteurs de position linéaire C₁, C₂, cette valeur ayant été déterminée à priori par l'opérateur, en fonction essentiellement du travail à effectuer, de la dureté, de l'épaisseur et de la matière de la feuille à travailler et également de l'expérience antérieure de l'opérateur; et
• le réglage du parallélisme des sommiers 5, 6 est obtenu en agissant uniquement sur les deux clavettes amont 18a, de manière à obtenir un basculement du sommier inférieur 6 dans le sens amont-aval (ou longitudinal).

FIG. 5 represents the functional diagram of the control of the two hydraulic motors M₁, M₂ according to an embodiment in which it is therefore provided that:

• the motor M₁ moves the upstream keys 18a, that is to say the upstream bar 34a;
• the motor M₂ moves the downstream keys 18b, that is to say the downstream bar 34b;
• the working pressure adjustment, carried out at bottom dead center, is initialized by the introduction of a position setpoint x corresponding to the desired working pressure, identical setpoint for the two linear position sensors C₁, C₂, this value having been determined a priori by the operator, essentially depending on the work to be performed, the hardness, the thickness and the material of the sheet to be worked and also on the operator's previous experience; and
• the adjustment of the parallelism of the bed bases 5, 6 is obtained by acting only on the two upstream keys 18a, so as to obtain a tilting of the lower bed base 6 in the upstream-downstream (or longitudinal) direction.

est nulle, le réglage du positionnement de la barre aval 34b pour obtenir la pression de travail souhaitée est en principe achevé.To adjust the positioning of the downstream bar 34b, the setpoint x first passes through a value limiter V working in saturation, then a digital-analog converter D₂, a comparator E₂ in which the setpoint x is compared at the actual position c₂ given by the linear position sensor C₂. Their difference c₂ is introduced successively into an analog regulator G₂ and a control system S₂ of the hydraulic motor M₂. When the motor M₂ is started, it acts on the reducer R₂ constituted in this case by the pinion 64 and the toothed wheel 55. When the toothed wheel 55 is rotated, the bar 34b is moved by a distance x₂ , as well as the output rod 82a of the linear sensor C₂ which, at this instant, will emit a new value c₂ of its position, value which will be introduced into the comparator E₂ to obtain a closed loop control of the positioning adjustment of the bar 34b. In the diagram, the influence of the output x₂ of the reducer R₂ is represented by the element T₂ symbolizing the dynamics of the mechanical system with delay occurring between the output of the reducer R₂ and the proximity sensor P₂. When the difference $\text{e₂ = x - c₂}$

is zero, the adjustment of the positioning of the downstream bar 34b to obtain the desired working pressure is in principle completed.

The motor control circuit M₁ is identical and parallel (see diagram in which the elements relating to the upstream side have the index 1), with the difference however that the position reference value x, before passing through the digital converter- analog D₁, is introduced into an intermediate comparator E coming into play when adjusting the parallelism of the two bed bases 5, 6.

As regards the pressure adjustment, it is still possible to specify that, when the position setpoint value x has been entered and that the adjustment of the positioning of the keys 18, 18b is finished, the operator can carry out a first cycle test of cutting a sheet of the new series in order to check whether, at the top dead center, the desired working pressure is actually obtained. The cutting force (in MN) is measured using, for example, at least one inductive displacement sensor 12 measuring the relative displacement between a high point H and a low point B of the frame. The sensor 12 is located at the point of the high point H, a rod 13, interposed between the two points H, B being fixed only by one end at the low point B, the other end, free, acting on the sensor 12. Such a measuring device is sufficiently known not to need to be described here in more detail. If the pressure measured at top dead center is not that desired, the operator enters a new position reference x. This test can be repeated several times until the desired pressure is obtained. It is interesting here to note how quickly and easily the pressure adjustment is carried out since everything is automated and that in principle no manual intervention is necessary.

Simultaneously with the adjustment of the working pressure, the adjustment of the parallelism of the bed bases 5, 6 is carried out. For this, at the instant of the neutral point of the drive system 20a, 20b, the proximity detectors P₁, P₂ indicate the distances e₁ and e₂ separating the two bed bases 5, 6 on the upstream side, respectively downstream. These distances e₁ _, e₂, after passing through an analog-digital converter A₁, respectively A₂, are introduced into a distance comparator E _p . The difference of the two distances e₁ and e₂ gives the value and the direction of the parallelism error e which will be introduced, after passing through a correction filter F produced digitally on a microcontroller and intended to eliminate random errors, in the parallelism comparator E. A parallelism setpoint value x _p is introduced, after passing through a value limiter V₁, into the parallelism comparator E. Thus, the parallelism error e is compared with the parallelism setpoint value x _p and their difference e _p is introduced into the digital-analog converter D₁, then into the closed-loop control circuit of the motor M₁ regulating the positioning of the upstream bar 34a and therefore of the upstream keys 18a.

The parallelism setpoint x _p is an infinitesimal value, sensitive to the slightest variations in the operating conditions of the press, the type of work to be carried out and other factors such as those already mentioned above with regard to the pressure adjustment. of work. It suffices here, however, to recall the basic principle already mentioned above, namely that the parallelism x _p is chosen so as to cause, at bottom dead center, a relative tilting between the bed bases 5, 6 which is opposite to that measured using proximity detectors P₁, P₂, at top dead center.

In addition, the operator can vary the setpoint of parallelism x _p taking into account the examination of the cut sheet and previous experience.

As we saw above, since the "setting" is almost canceled, the press preparation time for a new series of cutting sheets is much reduced compared to that used to date. This preparation time is further reduced considerably in the case where it is a series of sheets already worked previously, in which case, the position x and parallelism x _p setpoint values already known because they have been determined and stored previously, just have to be introduced into the adjustment system.

Many modifications can be made to the process described above without departing from the scope of the invention. Thus, for example, the successive sheets can be further connected to each other by attachment points, so as to form a strip which passes through the cutting press. Likewise, the press can have a movable upper bed and a fixed lower bed, as described in patent CH-A-363666. In this case, the parallelism errors come from the elongation of the pulls which connect the movable upper bed base to the drive system mounted on a lower cross member of the machine frame.

Claims (6)

1. Method for controlling the parallelism of the two beams (5, 6) of a cutting press designed for converting sheetlike or weblike matter into package and in which, with each operating cycle, at least one beam (6) is movable with regard to the other (5), under the effect of a drive system (20a, 20b) supported by means of bearings (33a, 33b) by the lower crossbar (1), between a first position in which the two beams (5, 6) are separated from one another, and a second position in which they are in pressure contact, means such as wedges (18a, 18b) are foreseen for controlling the reciprocal parallelism of the two beams (5, 6), in the course of an operating cycle of the press, deviation of parallelism (e) of the beams (5, 6) is measured when they are in the so-called second pressure position and that, in the so-called first position with the beams separated, the parallelism of the beams is controlled in a manner enabling the correction of the deviation (e) of parallelism measured, characterized by the fact that the deviation of parallelism (e) is measured by means of proximity sensors (P₁, P₂) fitted on at least one beam (5), and that the vertical position of the bearings (33a, 33b) is determined by at least one position sensor (C₁, C₂), by the fact that the proximity sensors (P₁, P₂) are fitted on the beam (5) in such a way as to allow the measuring of the deviation (e) of parallelism causing a downstream to upstream tilting or inversely of one of the beams with regard to the other, by the fact that only one pair of wedges (18a) likely to cause the tilting of the lower beam (6) contrary to the one measured is shifted by means of a corresponding bar (34a), ba the fact that the position of each of the bars (34a, 34b) is determined by the position sensors (C₁, C₂), the bars (34a, 34b) being shifted by means of an electric pneumatic or hydraulic motor (M₁, M₂), and by the fact that, the wedges (18a, 18b) being also used for controlling the operating pressure of the press, this operating pressure is controlled principally by means of the command rate (x) identical to the one of the two linear position sensors (C₁, C₂), and that the control circuit of every motor (M₁, M₂) operates with a closed loop so as to enable each of them to automatically cause respective shifts (x₁, x₂) of the bars (34a, 34b) until a position rate (e₁, e₂) given by each of the linear sensors (C₁, C₂) will be identical to the one of the command (x) and than this same closed loop control circuit of one of the motors (M₁) is used for controlling the parallelism of the two beams (5, 6) by feeding in a parallelism command rate (x_p) into the control circuit.
2. Cutting press designed for converting sheetlike or weblike matter into package for applying the method according to claim 1, comprising a frame made of a lower crossbar (1) and an upper crossbar (3) connected to one another by means of lateral posts (2), an upper fixed beam (5) being fitted on the upper crossbar (3), a lower movable beam (6) being raised and lowered with each operating cycle by means of a drive system (20a, 20b) supported by means of bearings (33a, 33b) by the lower crossbar (1), the said bearings being movable vertically when the drive system is situated in lower dead center position in such a way as to control the parallelism of the lower beam (6) with regard to the upper beam (5), characterized by the fact that it comprises proximity sensors (P₁, P₂) for measuring the parallelism of the two beams (5, 6), sensors (C₁, C₂) for determining the position of the wedges (18a, 18b), at least one motor (M₁, M₂) for shifting the wedges (18a, 18b), a control system with closed loop for each motor (M¹, M₂) with which it is possible to feed in a position command rate (x) common to all linear position sensors (C₁, C₂) in order to control the operating pressure of the press, and a parallelism command rate (x_p) for at least one position sensor (C₁) in order to control the parallelism of the two beams (5, 6) with regard to one another.
3. Cutting press according to claim 2, with which the drive system (20a, 20b) is supported by the lower crossbar (1) by means of two bearings (33a) upstream and two bearings (33b) downstream fitted respectively on crosswise bars (34a) upstream and crosswise bars (34b) downstream shiftable independently from one another and of which one end has a threaded extension (50) engaged in a corresponding threading of a toothed wheel (55) whose revolution causes the shifting of the bar (34a, 34b), characterized by the fact that the toothed wheel (55) is rotarily driven by a hydraulic motor (M₁, M₂).
4. Cutting press according to claim 3, characterized by the fact that a pinion (64) is cottered on the first end of a shaft (63) able to rotate on a support (58) itself fitted on the lower crossbar (1) whereas a second pinion (62) is cottered on the other end and engaged in an inner gear of a hollow sleeve (61), the inner gear being moreover engaged in a third pinion (60) cottered on the output shaft (57) of the hydraulic motor (M₁, M₂).
5. Cutting press according to claim 4, characterized by the fact that the threaded extension (50) has a rod (80) whose free end is provided with a device (81) arranged so as to be able to act on the linear position sensor (C₁, C₂).
6. Cutting press according to claim 5, characterized by the fact that the device (81) on the end of the rod (80) acts on two stroke end stops (83, 84).

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