A box-closing apparatus has a hanger link having one end pivoted about a fixed link axis on a stationary housing adjacent a station holding a box blank and another end defining a movable link axis. A two-arm main lever pivoted generally centrally at the movable link axis on the link has a pusher arm extending from the movable link axis and carrying a pusher block engageable with the flap of the box blank in the station and an actuating arm extending from the movable link axis and having an outer end. A drive lever pivoted at a fixed drive axis on the housing has an outer end pivoted at an outer drive axis on the outer end of the actuating arm of the main lever. The pusher block moves generally through a 0°–90° sinusoidal trajectory to press an outer flap against a glue flap of the blank in the station.

FIELD OF THE INVENTION

The present invention relates to a box-closing apparatus. More particularly this invention concerns an apparatus that presses a flap at a side of a box against a strip at the same side to adhere the flap to the strip and close this side of the box.

BACKGROUND OF THE INVENTION

In a box-erecting or packaging operation as described in German patent publication 100 65 310 of R. Stahn a flattened box blank is typically pushed into a tubular three-dimensional having two oppositely open sides from each of which several flaps extend. Then two flaps at one of the open sides are folded in and pressed together, normally after applying a contact adhesive to that face of one of the flaps that bears against the other flap, typically the outer face of the inner flap. This creates a stable three-dimensional box that can be tipped up on the now closed side formed by the glued-together flaps, and then filled through the other side that is upwardly open.

Other apparatuses for folding in and gluing flaps are described in German patent publication 1j99 18 940 of R. Ruf and U.S. Pat. No. 5,369,933 of M. Waldstädt. These devices are all fairly complex. None of them allows a flap to be pivoted gently from a position projecting outward through a box through 90° to a position bearing against the glue strip of the box by a relatively simple mechanism. Furthermore changing the operation of the box-closing apparatus to accommodate a box of different size is very difficult with the prior-art machines.

OBJECTS OF THE INVENTION

It is therefore an object of the present invention to provide an improved box-closing apparatus.

Another object is the provision of such an improved box-closing apparatus that overcomes the above-given disadvantages, in particular that can swing in and press down a box flap using a relatively simple apparatus that can be easily reset for boxes of different sizes.

SUMMARY OF THE INVENTION

An apparatus for pressing an outer flap of a box blank against a glue flap of the blank has according to the invention a housing adapted to support the box blank in a closing station and a hanger link having one end pivoted about a fixed link axis on the housing adjacent the station and another end defining a movable link axis. A two-arm main lever pivoted generally centrally at the movable link axis on the link has a pusher arm extending from the movable link axis and carrying a pusher block engageable with the flap of the box blank in the station and an actuating arm extending from the movable link axis and having an outer end. A drive lever pivoted at a fixed drive axis on the housing has an outer end pivoted at an outer drive axis on the outer end of the actuating arm of the main lever. The axes all is generally parallel, and a drive oscillates the drive lever about the fixed drive axis and thereby moves the pusher block generally through a 0°–90° sinusoidal trajectory between an upper point above and spaced horizontally from the blank in the station and a lower point pressing the outer flap against the glue flap of the blank in the station.

The main lever carrying the pusher block is able to describe the sinusoidal movement because it is carried on two axes that each oscillate about a respective fixed axis. This makes it possible to convert a simple oscillation of the drive lever about the fixed drive axis into a downward and inward movement of the pusher block, so that the projecting box flap is first pivoted down and then pressed horizontally against the glue flap.

The pusher block according to the invention has a rounded edge engageable with the outer flap of the box in the station. In addition it has a width generally equal to a width of the outer flap. Thus it will not damage the flap and will press it against the box's glue strip along its full length.

The fixed link axis is above the movable link axis and the fixed drive axis is below the outer drive axis. Thus the weight of the main lever in part is responsible for its sinusoidal downward movement on pivoting of the hanger link towrd the box blank.

In accordance with the invention an applicator lever pivoted about an applicator-lever axis on the housing serves for applying glue to the glue flap. The drive is coupled to the applicator lever to pivot it about the applicator-lever axis synchronously with pivoting of the drive lever about the fixed drive axis. Thus the applicator lever swings up and simultaneously pushes in the glue flap and applies a line of adhesive to it, then drops back out of the way as the pusher block presses the outer flap against the glue flap.

The drive has a cam with a pair of cam formations respectively connected to the drive lever and applicator lever. The cam is pivotal about a cam axis and one of the cam formations is a radially open annular groove coupled to the drive lever. The drive lever has an arm projecting from the fixed drive axis and the drive includes a cam follower riding in the respective cam formation and fixable at any of a plurality of locations along the drive-lever arm. Simply relocating the attachment location of this cam follower along this arm changes the lever arm through which the cam is effective on the drive lever and thus changes the vertical stroke of the pusher block, mainly by raising or lowering its uppermost point.

Another of the cam formations is an axially open groove coupled to the applicator lever, typically via a pivotal link lever. The drive can also include a variable-stroke linear servomotor connected to the drive lever and/or to the applicator lever.

SPECIFIC DESCRIPTION

As seen inFIGS. 1,2,3, and4, an apparatus1for folding a flap4of a box blank2against a glue-covered flap3of the blank2has a stationary housing10past which the boxes2are moved in a horizontal transport direction D (FIG. 2), stopping in a treatment station on the housing10. The apparatus1has a main two-arm lever5pivoted centrally at26at a lower end of a swing link11pivoted at an upper axis15fixed on a post of the housing10. An outer end of this lever5carries a flap-pushing block6which has a width in the direction D generally equal to that of the flap4. An inner end of the lever is pivoted at16at the upper end of another lever12whose lower end is pivoted at14in the housing10. The axes of the pivots14,15,16, and26are all parallel to each other and to the direction D. In addition a two-arm glue-applying lever17is pivoted on the housing10at27directly below the pivot15and has an outer arm engageable with the flap3to apply glue to it.

A common drive18oscillates the lever12about its axis14and the lever17about its axis27. This drive18has a continuously rotating cam wheel19centered on a vertical axis and formed with a horizontally and radially open cam groove20and with an axially upwardly open cam groove21. A cam follower23engaged in the cam groove20is shiftable along an arm22of the lever22and lockable at any position therealong by an adjustment rod24. The further from the axis14the cam follower23is fixed to the arm22, the shorter the vertical movement of the pusher block6. A cam-follower link13connects the cam21with the glue-applicator lever17so that same rises up to apply glue to the flap3and fold it in, then drop back down out of the way before the pusher block6pivots down the outer flap4and presses it against the flap3.

The kinematics are such that the pusher block6describes a 0°–90° sinusoidal trajectory9between an upper point7and a lower point8as it pushes the flap4down and then in. This movement is created by arcuate orbiting of the central pivot26of the lever4about the pivot axis15and synchronous arcuate orbiting of its rear-end pivot16about the axis14. It is shown in dashed lines inFIG. 10.

Alternately as shown inFIG. 9, a variable-stroke linear servomotor or drive25can be connected to the levers12and17to operate them.