EP0764501A1 - Quick clamping frame for a punching tool - Google Patents

Abstract

The frame has an upper cross-member (10), two side bars and a stop, and incorporates a quick-lock for the cutting tool (3) comprising a thrust bar (50) close to one of the bars or cross-pieces parallel to it, and able to push the tool against the bar or cross-piece. It incorporates springs (80) between the inner face of a bar or cross-piece and the outer surface of the thrust bar to exert a pressure against it, and a retractor. The springs are situated symmetrically on either side of the retractor located in the middle of the bar, and each is fitted into a blind hole (77) in the bar or cross-piece and exerts a pressure against a recess in the rear surface of the thrust bar (50). The retraction mechanism comprises a lug (55) which is fixed to the outer face of the thrust bar (50) and able to slide in a corresponding slot in the crosspiece.

Description

The present invention relates to a quick-tightening frame for a cutting tool used in a machine for cutting plate elements, such as sheets of paper or cardboard. The invention relates more particularly to a frame holding a tool in the form of a board, in which knives are installed, the whole being arranged in a platen cutting press.

For example, these machines are used to cut from each sheet of paper or cardboard one or more formats which, after folding and gluing, can be transformed into boxes. Each format generally includes the six sides of a box, some edges being supplemented with gluing or closing tabs. Usefully, the waste, that is to say the unused areas of the sheet between the tabs or between the formats, are immediately ejected after cutting so as to accumulate in the output stack only finished formats linked together by a few breaking points. Such a machine usually comprises first of all an introduction station, in which the sheets are apprehended one by one from the top of a stack to be sent to a margin table where they are placed in position against front and side tabs. The sheet can then be gripped at its front edge by a series of pliers mounted along a transverse bar, each end of which is attached to a train of lateral chains taking the bar, therefore the sheet, to the following processing stations. The sheet is thus transported to a cutting station comprising a platen press fitted with knives, then to an ejection station where the waste is pinched by needles to be drawn down into a tray. If desired, the cutting station can be preceded by a printing station also with platinum. These processing stations are followed by a receiving station, in which each cut sheet is released by the clamps to fall, square, on top of an output stack.

In the rest of the presentation, the terms upstream and downstream will be used with reference to the direction of movement of the leaves, that is to say that a room on the upstream side is close to the entrance to the station. , while a part on the downstream side is close to its outlet. Similarly, the expressions left and right are to be considered with respect to the direction of travel of the strip, the left side being usually the driver side and the right side the side opposite to the machine driver. Finally, by tool is meant the cutting tool located in the platen press of a cutting station, at the lower face of the stationary upper platen.

The commonly used tool includes a rectangular wooden base plate, into which a series of knives are inserted. This tool is previously positioned and fixed in an intermediate metal frame, itself mounted by sliding, from the left side of the machine, by engaging its bars, or gibs, upstream and downstream in slides corresponding to the plate.

With each new series, this tool must be changed in order to be adapted to the new format. It is therefore necessary to remove the metal chassis from the plate, to separate the tool from the chassis, to reinstall a new tool, and, finally, to reassemble this chassis in the plate.

The positioning and fixing of the tool in the chassis must be easy in order not to make the assembly and disassembly operations too long and tedious, as well as reliable in order to ensure a precise positioning of the tool throughout the entire operation. 'execution of a series, even after a large number of series changes.

As such, the document CH 652 059 describes a device for centering and fixing a tool in a chassis, a device in which these two operations are carried out by means of two pressers, one longitudinal, one lateral, located in the plane of the frame, and respectively close to the upstream cross member and the right bar of the frame, pushing the tool respectively against a downstream transverse and left lateral stopper. vis-a-vis. Each of these pressers consists of a deformable blade whose bearing faces, that is to say the faces opposite with the buffers, are machined according to a profile corresponding to the deformation curve of a beam loaded uniformly on two supports. The first centering operation consists in advancing a first adjusting screw, which acts simultaneously by means of a ramp on the two close ends of each of the pressers, which pushes the tool against the two opposite buffers. The second tightening operation consists in advancing two screws, which are placed respectively on the other two ends of the pressers, and which cause their deformation. To obtain effective centering and fixing, each of the three aforementioned screws is supposed to be blocked at the bottom of a counterbore made in correspondence.

One of the drawbacks of this device comes from the fact that the centering and tightening operations must be carried out in a well-defined order, at the risk of obtaining a positioning error, and then improper fixing of the tool in its chassis. We cannot already exclude an operator error at this level.

In addition, the quality of the centering and tightening depends on the torque applied to each of these screws. Too low a clamping force inevitably leads to a random and imprecise holding of the tool in its chassis. Too much clamping force induces tensions in the wooden plate, which then warps due to variations in temperature and / or humidity. In addition, the travel of each screw is predetermined by the depth of the countersinks, which limits, despite the presence of spring washers, the catching up of the structural changes of this wooden plate.

Another known device intended to ensure the attachment of a tool in its chassis comprises a rack included in the upstream cross member having in its internal side one or more planes inclined opposite identical plans belonging to the rear of a support bar. By acting on this rack by rotating a toothed wheel in the correct direction, the lateral displacement results in an advance in orthogonal translation towards the inside of the bar to push the tool. A plurality of racks are arranged along the periphery of the chassis in order to ensure effective clamping of the tool.

A first drawback results from the fact that these racks must be operated individually in a predetermined order with a non-standard key, which is long and tedious. Another drawback comes from the fact that the control of each rack is indexed by notches, acting as pawls. However, as in the first embodiment described, this tightening is then carried out by a positive action of the operator, who can actuate his key with too great or too weak a force, and moreover irregular. This then results, depending on the case, insufficient tightening and / or local deformation of the base plate.

The object of the present invention is a chassis comprising a quick clamping and centering device for a cutting tool in the form of a wooden base plate furnished with knives, chassis whose device is either simple in design or easy to apply, and apply an optimized constant pressing force. This device must, moreover, be able to make up for changes in the dimensions of this plate over time while retaining the positioning accuracy and the holding force in its chassis.

These goals are achieved thanks to a chassis composed of an upstream crossmember, two side bars and a downstream bumper crossmember, and comprising a quick tool clamping device including a support bar close to one bars, or crosspieces, parallel to the latter and movable in perpendicular translation to push the tool against the bar, or crosspiece, facing one another, because this clamping device comprises elastic means acting between the face internal of the bar, or cross member, and the external face of the bar for pushing it, and a withdrawal mechanism allowing the bar to be brought back towards the bar, or cross member, against the elastic means.

Thanks to this arrangement, the clamping force of the tool against the frame essentially depends on the sum of the pre-established forces of a plurality of elastic means, such as springs, which can evolve in compression or in relaxation to follow the dimensional changes of this tool as a function of variations in temperature and hydrometry.

Preferably, the elastic means are arranged symmetrically on each side of the withdrawal mechanism located in the middle of the bar so as to balance the support forces along the bar, and thus avoid any crossing.

Preferably, each elastic means is a spring housed in a blind hole in the bar or cross member and exerting its thrust at the bottom of a counterbore made in the rear face of the bar. The springs are thus correctly guided in their evolution. In addition, this arrangement is reliable because it is simple to make and robust.

According to a preferred embodiment, the withdrawal mechanism comprises a tab integral with the external face of the bar, movable in sliding in a housing formed in correspondence in the bar, or crosspiece, this tab having a substantially rectangular light oriented in the direction of the bar, this mechanism further comprising a control cam having an upper head housed in a bore in the bar, or cross member, and movable in rotation about an axis perpendicular to the tab, as well as a lower cylindrical tenon eccentric relative to to the head and engaged in the light of the paw.

In other words, this withdrawal mechanism, based on the rotation of an adequately dimensioned cam, makes it possible to easily counter very large spring forces necessary for good tightening. The force of action being reasonable, one can use only a traditional hexagon wrench. Usefully, the cylindrical post acts in the light through a free shoe in translation, and made of a material with a low coefficient of friction, which optimizes the torque to be applied with the key.

According to an advantageous embodiment, the quick clamping device is arranged only in the upstream crosspiece to push the tool against the downstream stopper crosspiece, the latter comprising a lateral centering stud penetrating into a centering notch in correspondence with the 'tool. The tightening in the direction of movement of the sheets being powerful, we can then be satisfied with a simple lateral wedging by means of a stud penetrating into a notch, which greatly facilitates and accelerates the positioning of the tool in its frame.

Advantageously, the frame comprises a cross-stopper made in one piece, and having along the length of the internal face one or more recesses intended to receive the sheet. This precisely machined one-piece stopper crossbar constitutes, in this chassis, a particularly reliable positioning reference.

• la figure 1 est une vue de dessus du châssis selon l'invention,
• les figures 2a, 2b, 2c sont des vues en coupe dans le plan du châssis du dispositif de serrage, respectivement en position retirée, en position intermédiaire, et en position de serrage,
• la figure 3 est une vue d'un détail de la traverse-butoir longitudinale du châssis de la figure 1,
• la figure 4 est une vue en coupe selon le plan IV-IV des figures 2 à 3,
• la figure 5 est une vue en coupe selon le plan V-V des figures 2 à 3,
• la figure 6 illustre en perspective une came appartenant aux moyens de commande du serrage.

The quick-release chassis according to the invention will be better understood from the study of a non-limiting embodiment and illustrated in the following figures:

• FIG. 1 is a top view of the chassis according to the invention,
• FIGS. 2a, 2b, 2c are sectional views in the plane of the chassis of the clamping device, respectively in the withdrawn position, in the intermediate position, and in the clamping position,
• FIG. 3 is a view of a detail of the longitudinal cross-member of the chassis of FIG. 1,
• FIG. 4 is a sectional view along the plane IV-IV of FIGS. 2 to 3,
• FIG. 5 is a sectional view along the plane VV of FIGS. 2 to 3,
• Figure 6 illustrates in perspective a cam belonging to the clamping control means.

As illustrated in FIG. 1, the quick-tightening chassis according to the invention comprises an upstream cross member 10, two side bars: one on the right 20 and one on the left 21, and a downstream stopper cross member 12, arranged so as to form a rectangle. This chassis has over the entire length of each of the lower edges of the outer faces of the upstream and downstream crosspieces a machining forming a lardon, respectively 15 and 16, also visible in FIGS. 4 and 5. These lardons of constant section are intended for engage in a slide corresponding to the upper plate of the press. The left sidebar 21 has on its outer face two handles 25 making it possible to easily enter and exit this chassis in its slides. The right side bar 20 has on its outer face a centering tongue 18 intended to cooperate with a corresponding machining carried out in the right side of the plate.

A sheet 1 is installed halfway up the chassis. More specifically, this sheet is screwed into the lower face of the right side bar, is sandwiched between a lower part 14 and an upper part 10 of upstream cross member, as illustrated in FIGS. 4 and 5, and is also taken sandwiched between a lower and upper part of the left sidebar, where it is held by means of pins and fixing means. The downstream stopper crosspiece 12, for its part, is made in one piece, and has over its entire length a series of recesses 49 with rounded ends intended to receive the corrugated downstream edge of the sheet 1, as clearly visible on the Figures 3, 4 and 5. Each recess 49 is separated by a bridge of reinforcing material. Within this downstream bumper cross member 12, the sheet 1 is positioned by means of pins 46 and fixed by screws 42 and spacers 44 illustrated in FIGS. 4 and 5.

The underside of a wooden board 3, forming the base of a cutting tool, rests on this sheet 1, the surface of which is treated by dipping to form an effective support base for knives installed in the thickness from this board 3.

The vertical holding of this board is achieved by means of downstream tabs 32 and movable upstream pins 38 hooking the upper surface of the tool, and distributed respectively over the length of downstream cross 12 and upstream 10. Each cleat 32 is positioned at a material bridge. Each tenon 38 is removable, that is to say that it can be rotated about 90 degrees along its axis of attachment. For this purpose, a machining 40 is carried out on the upper surface of the upstream cross member 10 in order to provide a space necessary for the housing of the stud 38. These studs are oriented in the longitudinal axis of the upstream cross member 10 during installation. of the tool, and perpendicular to it when the tool is installed in its chassis.

Furthermore, the downstream stopper crosspiece 12 has substantially in its middle and on its inner side a centering stud 34 intended to interact with a notch in correspondence with the board 3. This stud 34 ensures the lateral positioning of the tool in its frame. In addition, each of the two side bars 20, 21 has at its inner edge an adjustment wheel 30 disposed opposite the other, and intended to confirm the maintenance in lateral position of the tool.

Two devices 90 for rapid clamping of the tool in the direction of travel of the sheets are included in the upstream crosspiece as clearly visible in FIGS. 1, 2, 4 and 5.

As best seen in Figures 2 and 4, each clamping device comprises a support bar 50 connected to a rear tab 55. This tab 55 slides within a housing provided for this purpose in the underside of the upstream crossmember upper 10, and closed by the lower upstream cross-member 14. In the upper face of this tab 55, a shallow cylindrical bore 56 is produced. In the thickness of this tab is also produced a rectangular light 60 with rounded angles, and oriented parallel to the support bar, this light opening into the bore.

Within this light is installed, free in translation, a shoe 58 of octagonal shape made of a metal having a low coefficient of friction, for example brass. This shoe has in its center a circular opening opening 59. A control cam 65, illustrated in perspective in FIG. 6, comprises a lower cylindrical tenon 69 and an upper cylindrical head 67 connected by a central flange 72, the axis of the tenon being substantially offset from that of the head. The cylindrical post 69 comes to take place in the circular orifice 59 of the shoe, the diameter of this post being substantially equal to that of this orifice. The collar 72 evolves in the cylindrical bore 56 whose diameter is greater than that of this collar. The upper head 67 takes place in a vertical hole made in the upper upstream crosspiece 10. This cylindrical head 67 has a hexagonal orifice to receive a conventional hexagon wrench 70.

Furthermore, three blind holes 77 are produced on either side of the tab 55, perpendicularly in the upper upstream crosspiece 10. Countersinks 74 are formed in the rear face of the support bar 50, opposite these holes. 77. A spring 80 is installed in each of the holes and presses into the corresponding counterbore.

In the clamping position, the bar 50 protrudes from the interior surface of the upstream cross member 10 to bear against the edge of the wooden board 3 to be clamped. In order to adapt to possibly smaller tool dimensions, a shim 52 can be attached against the external face of the support bar 50, and held thereon by means of pins taking place in vertical orifices 51 of the support bar and in holes corresponding to the wedge.

The positioning and clamping of the tool in the quick clamping frame according to the invention is carried out as follows. It is first of all necessary to ensure that the removable pins 38 are located in the extension of the longitudinal bar 10. The tool is then brought inside the chassis against the downstream stopper cross member 12, between the tabs 32 and the sheet 1. The knives arranged on the tool are then directed towards the operator. The notch made on the downstream edge of the base board 3 of the tool engages in the centering stud 34 so as to ensure the lateral positioning of this tool. The adjustment knobs 30 are then actuated so as to come into contact with the lateral edges of this board 3 and thus confirm the maintenance in the lateral position. The removable pins 38 are then oriented perpendicular to the longitudinal bar 10, so as to be located just above the upper surface of the tool.

The initial position of the clamping devices is illustrated in Figure 2a. In this position, the effect of the springs 80 on the bar 50 is transmitted both in the tab 55 is compensated by the feedback of the cross member 10 on the cam 65 because it is aligned with the direction of movement of the leaves.

After placing the tool in position, the tool is tightened by turning the control cam 65 of each of the clamping devices 90 anticlockwise by means of a wrench 70 By this action, the cylindrical post 69 drives the shoe 58 which begins to describe an arc of a circle. The springs 80, previously compressed, relax and exert a pressing force at the bottom of the countersinks 74, which has the effect of driving the support bar 50, as described in FIG. 2b. The cylindrical pin 69 and the shoe 58 no longer being in alignment with the upper head 67, the rear tab 55 of the bar is free to slide forward under the effect of the springs. The shoe 58 then describes a translational movement in the lumen 60, combined with a transverse movement.

In the final position, ie in the clamping position illustrated in FIG. 2c, the support bar is pressed directly against the corresponding edge of the tool by the forces of each of the springs distributed at substantially regular intervals.

This tool has therefore been put in place properly and immobilized firmly by the combined action on the one hand of the centering stud 34 and the knobs 30, and on the other hand by the clamping between the two support bars 50 and the cross-member downstream stopper 12. This tightening obtained by this device no longer depends on the torque imparted by the operator, but only on the predetermined compression force of the springs. The support of the bar 50 against the tool is constant whatever the operator, and adapts to variations in dimensions of the tool in contact, without however the clamping force being altered. In addition, this method of tightening is simple and quick.

Many improvements can be made to this quick-release chassis within the scope of the claims.

Claims (7)

Quick clamping frame for a cutting tool composed of an upstream crosspiece (10), two side bars (20, 21) and a downstream crossbar (12), and comprising a quick clamping device (90) the tool (3) including a support bar (50) close to one of the bars, or crosspieces, parallel thereto and movable in perpendicular translation to push the tool (3) against the bar, or cross member, opposite, characterized in that this device comprises elastic means (80) acting between the internal face of the bar, or cross member, and the external face of the bar for pushing it, and a withdrawal mechanism allowing to bring the bar (50) in the direction of the bar, or cross, against the elastic means (80). Quick-tightening frame according to claim 1, characterized in that the elastic means (80) are arranged symmetrically on each side of the withdrawal mechanism located in the middle of the bar. Quick-tightening frame according to claim 1, characterized in that each elastic means (80) is a spring housed in a blind bore (77) of the bar or cross member and exerting its thrust at the bottom of a counterbore made in the rear face of the bar (50). Quick-tightening frame according to claim 1, characterized in that the withdrawal mechanism comprises a lug (55) integral with the external face of the bar (50), movable in sliding in a housing formed in correspondence in the bar, or cross-member , this tab having a substantially rectangular lumen (60) oriented in the direction of the bar (50), this mechanism further comprising a control cam (65) having an upper head housed in a bore in the bar, or cross member, and movable in rotation about an axis perpendicular to the tab, as well as a lower cylindrical tenon (69) eccentric with respect to the head and engaged in the lumen (60) of the tab. Quick-tightening frame according to claim 4, characterized in that the cylindrical pin (69) acts in the lumen (60) through a shoe (58) free in translation, and made of a material of low coefficient of friction. Quick clamping frame according to claim 1, characterized in that the quick clamping device (90) is arranged in the upstream crossmember (10) and pushes the tool (3) against the downstream stopper crossmember (12), this- ci comprising a lateral centering stud (34) penetrating a centering notch corresponding to the tool (3). Quick-tightening frame according to claim 6, characterized in that the bumper cross-member (12) is made in one piece, and has, along the length of the internal face, one or more recesses (49) intended to receive a sheet ( 1).

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