EP0467741B1 - Continuous stapling device with a fixed stapling bed and a machine provided with such a device - Google Patents

Abstract

Device for stapling plane elements, comprising at least one oscillating or rotary stapling head, and a stapling bed (4) defined by a principal longitudinal axis (X) essentially perpendicular to the axis of pivoting of the stapling head, the active free end of which is moreover held in position facing an impression of a stapling counterpart (18) formed on the stapling bed. According to the invention, the stapling bed (4) is mounted in a fixed manner on the frame and the stapling counterpart is constituted by an anvil (18), the trajectory of the impression (25, 26) of which coincides essentially at least in part with that of the active free end of the stapling head, the mobile anvil preferably consisting of a turning disc provided with a continuous circular impression centred on its axis of rotation. Application in particular to the stapling of cardboard blanks for the manufacture of packing boxes in folded form. <IMAGE>

Description

The present invention relates to a device for stapling flat elements, such as for example cardboard blanks, of the type comprising, on a frame, at least one oscillating or rotary stapling head, as well as a defined riveting pallet by a main longitudinal axis substantially perpendicular to the pivoting axis of the stapling head, the active free end of which is also held in front of an imprint of a stapling counterpart formed on the riveting pallet .

Stapling devices of this type are fitted in particular to stapling machines which, at the outlet of the production lines for packaging cases, carry out the mutual assembly of the two free sides of the folded cardboard blanks. These pass in succession under the oscillating or rotary stapling head while being guided and positioned by the riveting pallet, which, in order to maintain the imprint of the stapling counterpart permanently in the path of the staple posed by the head must oscillate in perfect synchronism with the movement of the latter.

However, this riveting pallet must be long enough to avoid too great a deformation of the cardboard sections to be stapled and massive enough not to bend when driving in and riveting the staple. This results, for the riveting pallet, a significant inertia, source of effort and vibration during its oscillating movement at high speed, and this can result in an imperfection of the stapling performed.

The present invention seeks to remedy this drawback by proposing a device for stapling flat elements, such as for example cardboard blanks, of the type specified in the introduction, which is characterized in that its riveting pallet is fixedly mounted on the frame, and the stapling counterpart is constituted by a movable anvil whose trajectory of the imprint is at least partly substantially coincident with that of the active free end of the stapling head.

This anvil, which can have dimensions and a weight minimum, will have negligible inertia during its movement and, the riveting pallet being fixed, the problems of vibration and mechanical stress encountered hitherto disappear. In addition, no control mechanism is required to ensure its movement in synchronism with the pivoting of the stapling head, since the latter by pressing the cardboard against the anvil, automatically drives it by adhesion in its movement , when installing the clip.

In a first embodiment of the invention, the movable anvil has the shape of a plate mounted to slide on the surface of the riveting pallet, in the direction of the main longitudinal axis of the latter and against by the force of a return spring, in which case, if the stapling head is double, the two corresponding indentations can be made in the same sliding plate, one behind the other in the direction of the main axis longitudinal of the riveting pallet.

This embodiment, of simple design, gives the best results in the case of a low or medium stapling rate. However, for rates higher than 1000 strokes per minute, the necessary recall of the anvil plate at each stapling cycle, would cause its movement to be out of synchronization with that of the stapling head.

For an adaptation to such high stapling rates, it is provided, according to a second preferred embodiment of the invention, that the movable riveting anvil is constituted by a circular disc mounted in rotation on the surface of the pallet riveting around an axis substantially orthogonal to the main longitudinal axis thereof. This disc being driven always in the same direction of rotation, on an angular sector given to each stapling cycle, is in fact the subject of no return movement "empty" source of desynchronization.

If, moreover, this disc is endowed with a continuous circular imprint centered on its axis of rotation, and preferably constituted by two concentric and adjacent grooves in the shape of a circle, this eliminates the problem of the precision of the positioning of the imprint at the start of each stapling cycle.

In addition, to make the slight arrow introduced into the stapling head negligible during its short movement in an arc imposed by the shape of the imprint, it will advantageously be provided at the periphery of the disc.

According to another embodiment of the invention, the stapling head is positioned on one side of the axis of rotation of the disc and the latter inclines downward in a direction opposite to the stapling head , to avoid any friction between the element to be stapled and the part of the disc located outside the field of action of the stapling head.

Finally, in one or other of the two above-mentioned embodiments of the invention, the anvil or at least its part facing the active free end of the stapling head, is slightly protruding with respect to the surface of the riveting pallet, to be guaranteed in all circumstances to be suitably driven by the cardboard pressed in contact with it by the stapling head.

The present invention also relates to a machine for stapling flat elements, in particular cardboard blanks, comprising a stapling device, as defined above, associated with means for continuously driving the elements to be stapled, capable of scroll them successively on and along the riveting pallet, in the direction of the main longitudinal axis of the latter.

• la figure 1 est une vue de côté schématique, partiellement en coupe longitudinale d'un dispositif d'agrafage conforme à cette invention ;
• la figure 2 est une vue de face de sa palette de rivetage à l'intérieur d'un flan en carton plié ;
• la figure 3 est une vue en perspective, à plus grande échelle, d'un premier mode de réalisation de cette palette de rivetage ;
• les figures 4 et 5 sont des vues en coupe longitudinale et transversale de son enclume de rivetage mobile ;
• la figure 6 illustre en coupe les deux pans agrafés d'un flan en carton ;
• la figure 7 est une vue en perspective d'un second mode de réalisation de la palette de rivetage ; et
• la figure 8 est une vue en coupe agrandie selon la ligne VIII-VIII de la figure 7.

The present invention will now be described in more detail, but only without limitation, with reference to the accompanying drawings, in which:

• Figure 1 is a schematic side view, partially in longitudinal section of a stapling device according to this invention;
• Figure 2 is a front view of its riveting pallet inside a folded cardboard blank;
• Figure 3 is a perspective view, on a larger scale, of a first embodiment of this riveting pallet;
• Figures 4 and 5 are views in longitudinal and cross section of its movable riveting anvil;
• Figure 6 illustrates in section the two stapled sides of a cardboard blank;
• Figure 7 is a perspective view of a second embodiment of the riveting pallet; and
• FIG. 8 is an enlarged sectional view along line VIII-VIII of FIG. 7.

In a manner known per se, the stapling device shown in FIG. 1 comprises a stapling head 1, here a double head, which is suspended from a frame 2 by a deformable parallelogram pivoting around two axes A, of so as to be able to be animated with an oscillating movement in the direction of travel D of the folded cardboard blanks F, the two free sides P₁ and P₂ of which are to be stapled together.

The mechanism generating the oscillating movement of the stapling head 1, which does not appear in the figures, can be of the type described in document FR-A-2 624 431 in the name of the present Applicant.

To achieve the insertion of the staples into the carton, the stapling head 1 cooperates, at its free end 1a, with a stapling counterpart 3, visible in FIG. 3, located at the front of a riveting pallet 4. This pallet 4 has the shape of a long rectangular plate whose median longitudinal axis X extends in the direction of travel D of the blanks F, that is to say substantially perpendicular to the axes of pivoting A of the stapling head 1.

According to the invention, this riveting pallet 4 is fixed, being secured to the frame 2 by a solid vertical arm 5 which is slightly offset towards the rear of the pallet 4, in order to leave any freedom of movement to the stapling head oscillating 1 located at the front. By its lower end, the arm 5 is connected to the outer longitudinal edge 6 of the pallet 4 by a curved lateral veil 7, tilting backwards.

The folded blanks F, which arrive in succession on cleat chains, not shown, engage, by their double central pan P₃, under the pallet 4 and advance along it with their flaps free sides P₁ and P₂ sliding respectively on the veil 7 and on the upper surface 4a of the pallet 4, as can be seen in FIG. 2. Beyond the veil 7, the lips superimposed to staple the two sides P₁, P₂ s '' introduce under the active free end 1a of the double stapling head 1, which is then pressed against them to simultaneously install two joining staples, while pivoting a short angular distance forward in order to follow the continuous movement of the blank F. During this movement, the stapling counterpart 3 must of course be permanently under the active free end 1a of the oscillating head 1 and, to this end, it is formed, according to the invention, by a movable riveting anvil.

According to a first embodiment, represented in FIGS. 3 to 5, this movable anvil is constituted by a rectangular plate 8, of minimum dimensions, mounted to slide, in the direction of travel D of the blanks F, inside of a light 9, of complementary shape, formed in the riveting pallet 4. To this end, the plate 8 has, in each of its lateral edges, a groove 10 or 11 in which engages a respective tongue 12 or 13 formed in protrusion on a corresponding edge of the lumen 9. It will be observed that the two tongues 12, 13 are flush with the upper surface 4a of the riveting pallet 4, so that the plate 8 protrudes slightly above the latter. Its upper surface 8a is furthermore provided with two indentations, each of which, formed of two cells 14, 15 and 14a, 15a, is associated with a respective staple driving part of the double head 1. Finally, a spring 16, working in elongation, is interposed between the front edge of the light 9 and the front part of the plate 8, which is also, for its assembly, formed of two symmetrical parts 8b, 8c assembled by a screw 17.

FIG. 4 represents the plate 8 in the remote position which it occupies at the starting point of each stapling cycle, just before the head 1 intervenes on the two superimposed cardboard sections P₁, P₂ advancing on its upper surface 8a. During the stapling operation proper which follows, the head pressing the two sides of cardboard, while pivoting forward, will cause in its movement of the sliding plate 8 by compressing the spring 16. In this way, the pairs of cells 14, 15 and 14a, 15a will be permanently in alignment with the two staples placed B to ensure perfect riveting of the branches of the latter after pushing in, as shown in FIG. 6. Once this operation has been carried out, the head releases its pressure on the staples P₁, P₂, so that the plate 8 is automatically pushed back by the spring 16 into its starting position in view of the cycle next stapling.

FIG. 7 illustrates a second embodiment of the invention, in which the movable anvil has the shape of a circular disc or pellet 18, mounted in rotation about an axis Y substantially perpendicular to the axis main longitudinal X of the riveting pallet 4, inside a housing 19 of complementary shape, machined in the front part 20 of the latter, enlarged for this purpose.

Figure 8 shows that the disc 18 is rotatably mounted, by means of a ball bearing 21, around a hub 22 fixed to the center of the bottom of the circular housing 19 by screws 23. In addition, to be perfectly stable during its rotation, the disc 18 rests, near its peripheral edge 18b, on needle stops, such as 24, positioned radially on the bottom of the housing 19.

In FIGS. 7 and 8, it can also be seen that two circular grooves 25, 26, concentric and adjacent, with a rounded bottom, are engraved in the upper surface 18a of the disc 18, very close to the peripheral edge 18b of the latter. These two grooves 25, 26, which are centered on the axis of rotation Y of the disc 18, constitute a continuous riveting imprint intended to cooperate with the stapling head 1 (symbolized by an arrow in FIG. 8), which is here positioned so that at the start of a stapling cycle, it is plumb with a point in the circular imprint 25, 26 very close to a tangent to the disc 18, parallel to the longitudinal axis X of the riveting pallet 4.

Consequently, once the two sides P₁, P₂ of the blank F have, in this starting position, been pressed against the surface of the disc 18 by the stapling head 1, the active free end thereof, in its forward movement, will drive the disc in rotation about the Y axis and will describe, following the circular imprint, a trajectory in an arc, over 4 to 5 mm, along which the staples will be driven into the cardboard and riveted in the two grooves 25, 26 of the imprint, as described previously with reference to FIG. 6. After this operation, the stapling head will be raised and returned to its starting position, above another point of the continuous circular imprint 25, 26 for the next stapling cycle, without any problem being posed positioning vis-à-vis the latter.

In FIG. 8, it can be observed that, in its housing 19, the disc tilts down, gradually sinking under the surface 4a of the riveting pallet 4, from its part 18c subjected to the action of the stapling head 1, which on the contrary is slightly protruding above this same surface. Thus, on the one hand, the disc 18 will not be braked by the cardboard, in its part where it rotates in the opposite direction to the advance movement of the latter, and, on the other hand, it will be perfectly well driven under the stapling head.

It should also be added that the deflection introduced into the stapling head 1, during its movement in an arc, can be neglected, taking into account the mechanical tolerances.

Claims (10)

1. A device for stapling flat elements, such as for example cardboard blanks, of the type comprising, on a frame (2), at least one swinging or rotating stapling head (1), as well as a stapling bed (4) defined by a major longitudinal axis (X) substantially perpendicular to the pivot axis (A) of the stapling head, said stapling head further having its active free end (1a) held opposite an indentation of a stapling counterpart (8; 18) formed on the stapling bed, characterized in that the stapling bed (4) is fixedly mounted on the frame (2) and the stapling counterpart is formed by a mobile anvil (8; 18) with the path of the indentation (14, 15; 25, 26) thereof being at least in part substantially merged into that of the active free end (1a) of the stapling head (1).
2. The device according to claim 1, characterized in that the mobile anvil is in the form of a small plate (8), which is slidably mounted on the surface (4a) of the stapling bed (4), in the direction of the major longitudinal axis (X) of the latter and against the force of a return spring (16).
3. The device according to claim 2, provided with a double stapling head, characterized in that the two respective indentations (14, 15; 14a, 15a) are formed in one same slidable small plate (8), one behind the other in the direction of the major longitudinal axis (X) of the stapling bed (4).
4. The device according to claim 1, characterized in that the mobile anvil is in the form of a circular disk (18), which is rotatably mounted on the surface (4a) of the stapling bed (4), about an axis (Y) substantially orthogonal to its major longitudinal axis (X).
5. The device according to claim 4, characterized in that the disk (18) comprises a continuous circular indentation (25, 26) centered on the axis of rotation (Y) thereof.
6. The device according to claim 5, characterized in that the indentation is formed by two concentric and adjacent circular grooves (25, 26).
7. The device according to claim 5 or 6, characterized in that the indentation is formed at the periphery of the disk (18).
8. The device according to any of claims 4 to 7, characterized in that the stapling head (1) is positioned on one side of the axis of rotation (Y) of the disk (18) and in that the disk is slanting downwards from the stapling head.
9. The device according to any of claims 1 to 8, characterized in that the anvil (8, 18) or at least the part thereof which is opposite the active free end of the stapling head, is slightly projecting from the surface (4a) of the stapling bed (4).
10. A machine for stapling flat elements, in particular cardboard blanks, comprising a stapling device, such as defined in any of claims 1 to 9, associated with means for continuously driving elements (F) to be stapled which are operable to make them run successively on and along the stapling bed (4) in the direction of the major longitudinal axis (X) of the latter.

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