EP0681892B1 - Platen press for a cutting station in a machine for treating plates - Google Patents

Abstract

A plate press is claimed for the cutting station of a machine for treating plate elements, comprising an upper bolster (4) embedded on each side in the framework of the cutting station and a lower moving bolster (8) displaced vertically by some toggle joints of which the pivoting axes are oriented in the span of the lower moving bolster (8). Each toggle joint (16,18) is activated by at least one rod (20,24) connected to a brace (14). The lower moving bolster (8) is activated by only two identical toggle joints (16,18), each being symmetrical w.r.t. a median vertical plane passing through the middle of the span of the lower moving bolster. The width of each toggle joint is between one third and two thirds the width of the lower moving bolster. The brace (14) is driven by a screw and an endless screw track arranged outside the operating zone of the toggle joints (16,18). <IMAGE>

Description

The present invention relates to a platen press for the cutting station of a machine for treating plate elements, such as sheets of paper or cardboard, and more particularly to a press comprising a lower bed base which can be moved vertically during of each machine cycle until its substantially planar upper surface comes to apply pressure on a flat marble secured to a fixed upper bed base.

Such a plate element processing machine usually comprises first of all an insertion station in which a stack of sheets is installed, each sheet being successively removed from the top of the stack to be sent to a margin table. On this table, each sheet is placed in position against front and side cleats before being gripped at its front edge by a series of clamps mounted along a transverse bar, each end of which is attached to a train of side chains taking the bar, and therefore the sheet, to the following treatment stations. The treatment stations can be a cutting station, the latter being followed by a waste ejection station. These processing stations are followed by a receiving station in which each sheet released by the clamps is squared by falling on top of a pile accumulating on an output pallet.

In known machines, the upper box spring is embedded on each side in the station frame cutting. The movable bed base is usually moved at four points, on each of which acts a toggle driven by a connecting rod connected to a crankshaft. These points are generally distributed in pairs, one pair, upstream, being placed in the vicinity of the upstream edge of the bed base, that is to say near the introduction station, and the other pair, downstream, being disposed in the vicinity from the downstream edge of the bed base, that is to say near the ejection station. Each pair of points, taken across the width of the base, is normally arranged symmetrically with respect to the median vertical plane of the base, the points being located near the lateral edges of the base. It should be noted that the pairs of upstream and downstream points are often located at a spacing of different width to take account of the geometry and the position of the drive members, in particular the crankshaft, connecting rods, the worm and of the worm wheel.

When pressure is applied, the bed bases deform according to the position of the lifting points of the lower bed base. It is difficult to envisage obtaining, during the pressurization, a deformation curve which is absolutely the same for the two bed bases. It is however essential, for a good quality of the treatment of the elements in plate and in particular of their cutting, that the curves of deformation of the upper and lower bed bases match as best as possible.

However, it turns out that the use of four independent knee pads, or even only three, requires adaptations of the geometry of the bed bases, which are particularly difficult to determine and carry out, in order to modify the characteristics of resistance of the box springs so that the upper and lower deformities are combined. Indeed, it is difficult to produce variations in section and thickness in large box springs, made of cast iron, when some of these sections are necessarily determined by the arrangement of the drive members of the lower bed base. The current technique therefore consists in compensating for the deformations of the bed bases by manual setting of the cutting tools, which is also tedious.

In addition, the actuation of four knee pads by four independent connecting rods requires a crankshaft connected to a central worm wheel installed under the lower bed base in its median vertical plane. The underside of this bed base must then have, in its central part, a clearance zone for the passage of the worm wheel when the bottom bed base passes through its bottom dead center. This clearance zone is in fact a weakening zone of the bed base which obviously and inevitably modifies its stiffness characteristics.

The object of the present invention is a platen press arranged so that the combination of the deformation curves of two bed bases is more easily achievable, and, if possible, at lower cost by a simplified structure of the bed bases.

These goals are achieved by a platen press for the cutting station of a plate processing machine, this press comprising an upper base embedded on each side in the frames of the cutting station and a movable lower base moved vertically by knee pads whose pivot axes are oriented in the width of the movable lower base, each knee switch being driven by at least one connecting rod connected to a crankshaft, characterized in that the movable lower bed base is actuated by only two identical knee switches, an upstream knee switch and a downstream knee switch, each being symmetrical with respect to a median vertical plane passing through the middle of the width of the movable lower bed base, the width of each of these toggles being between one third and two thirds of the width of this movable lower bed base and in that the crankshaft is driven by a screw and a screw wheel without end arranged outside the operating area of the knee pads.

Thus, by reducing to the use of two knee pads, these being nevertheless wide enough to effectively support the lower movable base, and to a drive of the knee pads disposed outside their zone of action, the curve of deformation of the bed bases can be determined precisely and can be used to calculate exactly the geometry of each of the upper and lower bed bases.

By compensating the rigidity of the lower bed base in a uniform shape in length and progressive in width, it is easy to obtain a perfect combination of the contact surfaces under pressure. This compensation of the lower bed base is all the easier since it is rigorously symmetrical with respect to the median longitudinal axis.

In a preferred embodiment, one of the knuckles is driven by a first major central link, while the other knuckle is driven by a pair of minor links respectively located on either side of the first on the same crankshaft . The dimensions of the pair of minor connecting rods are such that the sum of their tensile and compressive strength is equivalent to that of the major connecting rod. Unlike two identical connecting rods side by side conceivable, this configuration ensures a homogeneity of the lifting action with respect to the median vertical plane of the bed bases.

Preferably, the crankshaft actuating the connecting rods is driven at its end by a vertical worm wheel installed on the side of the knee pads. This configuration made possible by the small number of connecting rods involved first avoids having to unnecessarily cut the bottom base and then allows to accommodate on the side the worm wheel drive and its automatic release device in case overpressure.

• la figure 1 est une vue du côté "conducteur" de la presse à platine, c'est-à-dire du côté gauche tel que considéré par rapport au sens de déplacement des feuilles,
• la figure 2 est une vue amont, c'est-à-dire de l'entrée de la presse à platine, et
• la figure 3 est une vue aval de la presse a platine.

The invention will be better understood from the study of an embodiment taken without any limitation being implied and illustrated by the appended figures, in which:

• FIG. 1 is a view of the "driver" side of the platen press, that is to say of the left side as considered with respect to the direction of movement of the sheets,
• FIG. 2 is an upstream view, that is to say of the entrance to the platen press, and
• Figure 3 is a downstream view of the platen press.

As illustrated in FIG. 1, a sheet of paper or cardboard 2 is brought by a gripper bar 3 between the fixed upper bed base 4 and the vertically movable lower bed base 8 of a platen press. Once the sheet in place, the upward movement of the box spring 8 presses the sheet 2 into the knives 5 of the upper box spring 4, this sheet then being cut into the format defined by the arrangement of its knives.

More particularly according to the invention, and as can be seen from the simultaneous examination of the three figures, the base 8 rests on the lower frame 7 of the machine by only two identical knee pads: an upstream 16 and a downstream 18. Each of these kneepads comprises an upper half-toggle 36 and a lower half-toggle 32 substantially symmetrical with respect to a horizontal plane. The lower half-toggle joint 32 is articulated in rotation about an axis Y3 on a lower roller 34 resting in a pad 35 housed in the lower frame 7, and at its upper end it is articulated in rotation around an axis Y2 against a middle roller 22 (26). Similarly, the upper half-toggle 36 is articulated at its lower end in rotation about the axis Y2 against the median roller 22 (26), and at its upper end in rotation around an axis Y1 against a half roller 38 housed in feet 39 of the lower base 8.

As can best be seen in FIGS. 2 and 3, each half-toggle joint has a central recess 30 from the edge in contact with the median roller 22, and the resulting general shape has symmetry with respect to their median vertical plane which, according to the invention, coincides with the median vertical plane of the lower base 8. In each of the lateral edges of the lower half-knee pads 32 and of the upper half-knee pads 36 are housings for bolts for fixing the knee pad to the 'one of the rotation rollers. The rotation rollers are also required transversely in these toggles by flanges 28 receiving a positioning axis located at the ends of the rollers, these flanges being bolted in the lower pad or half-toggle.

More particularly according to the invention, the middle roller 22 of the upstream toggle joint 16 is held in its middle by a major connecting rod 20 connected to the crankshaft 14. On the downstream side, the middle roller 26 of the toggle joint 18 is held by a pair of connecting rods minor 24 arranged, in the recess 30, against the internal face of each of the lower and upper parts of the half-toggles in contact with this median roller 26. In other words, each minor connecting rod of the pair 24 is symmetrically arranged on either side of the major connecting rod 20 on the crankshaft 14. The dimensions of the two minor connecting rods 24 are such that together they are equivalent to the major connecting rod 20.

As best seen in Figures 2 and 3, the end of the crankshaft 14 leaves the area of action of the knee pads 16, 18 on the side opposite the conductor, to be connected to a vertical worm wheel 12 driven by a screw endless lower 10.

As can be seen from the simultaneous examination of the three figures, the knee pads 16 and 18 are symmetrical with respect to the vertical longitudinal XX and transverse YY planes. The thrust force applied by these toggles on the base 8 is therefore balanced with respect to these two planes. On the other hand and more particularly according to the invention, the width of the knee pads 16 and 18 is only between one third and two thirds of the width of the bed base so that the intensity of the thrust is maximum in the vertical median plane XX which allows , in combination with installation according to two lateral edges of the fixed upper bed base 4, to combine the deformation of these two bed bases when pressurized. The adaptation of the lower base 8 to the fixed upper base 4 is therefore particularly easy since it is symmetrical in the width direction and substantially constant in the length direction.

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

Claims (3)

1. Platen press for the die-cutting station of a machine for processing plate-like workpieces, this press comprising an upper beam (4) secured at each end in the frames of the die-cutting station, and a movable lower beam (8) vertically moved by knuckles whose pivoting axles are orientated in the width of the movable lower beam (8), each knuckle (16, 18) being actuated by at least one connecting rod (20, 24) connected to a crankshaft (14), characterized by the fact that the movable lower beam (8) is actuated by only two identical knuckles, i.e. an upstream knuckle (16) and a downstream knuckle (18), the two being symmetrical with respect to a central vertical plane (X-X) extending through the middle of the width of the movable lower beam (8), the width of each knuckle (16, 18) being between one third and two thirds the width of this movable lower beam (8), and by the fact that the crankshaft (14) is driven by a worm (10) and a worm wheel (12) arranged outside the area of operation of the knuckles (16, 18).
2. Platen press according to claim 1, characterized by the fact that the knuckles (16, 18) are symmetrically arranged with respect to the central vertical plane (Y-Y) through the middle of the length of the movable lower beam (8).
3. Platten press according to claim 1, characterized by the fact that one knuckle (16) is actuated by a first main central connecting rod (20), whereas the other knuckle (18) is actuated by a pair of smaller connecting rods (24) arranged respectively on each side of the first connecting rod (20) on the same crankshaft (14).

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