Folding station with adjustable folding strap

A folding station of a folding box gluing machine for processing a blank having a middle piece and side pieces which are attached to sides of the middle piece and which are deflected upward and inward along folding grooves between the middle piece and the side piece across a folding line toward the lengthwise middle of the blank and then folded up in order to produce a folding boxes, includes a folding strap that deflects the side pieces and folds them upward. The folding strap is guided by a folding shunt, a positioning roller, and one or more deflection and pressure rollers. A distance between the folding strap from the folding line of the blank is adjustable, such that the folding strap acts on an outer region of the side piece.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention concerns a folding station of a folding box gluing machine for processing a blank delivered along a conveying section with a controllable delivery speed, wherein the blank has a middle piece on which side pieces are attached at the sides of the middle piece, which are folded inward along folding grooves between the middle piece and the side pieces, across a folding line toward the lengthwise middle of the blank and then folded up in order to produce the folded boxes, with a folding strap that folds the side pieces upward, being guided by a folding shunt, a positioning roller, and one or more deflection and pressure rollers.

2. Description of the Related Art

A known folding box machine used to transform blanks into folded box tubes is disclosed in DE 102 41 448. The blanks correspond to a view of a ready-to-produce folding box. The folding must be performed with precision, since the folding will determine the angle trueness of the finished folded box.

In order to produce the folded box tube, folding straps or folding bands are used and arranged to lie against portions of the blank being folded up, or the side pieces of the folding box blank, and maintain the folding along the folding line. The folding straps are arranged so as to have a helical shape and are arranged to operate on the portions being folded. To effectively perform the folding operation, the folding straps travel at a speed corresponding to the speed of the blank. In order to ensure the angle trueness of the finished folded box, a plurality of loosely turning disks are arranged in the folding line, and make contact with the folding box blank in the vicinity of the folding lines.

Another known folding station for folding blanks is disclosed in DE 44 39 198 A1. Folding is performed using folding straps, which engage the side flaps of a blank from underneath. The folding straps thus travel from a plane underneath the blank to a plane above the middle piece of the blank. The axes of the folding straps are twisted relative to each other so that the surface of the folding strap facing the blank rotates by a total of about 180 degrees along the delivery path of the blank. In order to maintain close tolerances during the folding of the blanks, an edging device is arranged in the region of the folding lines of the blanks in the forward region of the delivery path.

It is evident from the described state of the art that exact folding along the folding lines and maintaining angle trueness of the blanks after folding present problems with the conventional folding process.

SUMMARY OF THE INVENTION

To overcome the problems described above, preferred embodiments of the invention provide a folding box gluing machine which provides precise folding with minimal additional parts, and which enables adjustment of the folding station to accommodate diverse blanks in a flexible manner and with minimal expense.

A preferred embodiment of the present invention provides a folding box gluing machine in which the distance from the folding strap to the folding line of the blank is adjustable, such that the folding strap constantly works on an outer region of the side piece. Preferred embodiments of the present invention make it possible to grasp even the most diverse blanks in the region of the side pieces that is most favorable for folding to thereby assure precise folding. The adjustability of the folding strap relative to the folding line and thus to the particular length of the side piece of the blank, enables the optimal folding moment to be exerted on the blanks. The use of an adjustable modular suspension facilitates horizontal and vertical adjustment of the folding strap with respect to the direction of transport of the blanks.

Other features, elements, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments with reference to the attached drawings.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the delivery direction, which runs from right to left inFIG. 1, the folding box gluing machine preferably includes an inserter1which pulls the blanks being processed one after the other from a stack at high speed and introduces them individually to the following processing stations. After the inserter1, a primary breaker2is provided, which has two stages in the present preferred embodiment. The breaker2includes folding elements for folding side pieces or folding flaps forward and backward, so as to produce corresponding folding lines or lengthwise grooves which are soft and flexible by bending them through about 180 degrees. The two-stage configuration shown inFIG. 1makes it possible to break several lengthwise and transverse grooves and produce additional folds. A folding station3is provided after the breaker2, the folding station3includes an applicator4for applying adhesive, such as glue, arranged at the beginning of the folding station3. The adhesive applicator4includes glue nozzles or glue disks, from which the glue is applied in a strip on the blanks. At the end of the folding station3, the folded boxes are checked for folding mistakes. For this, photocells are arranged in this region, with which the length of the folded box is probed. If the length of the folding box does not correspond to a predetermined length, e.g., because a flap was not properly folded, this box is reported as defective to the central control unit of the folding box gluing machine.

Immediately next to the folding station3is the transfer station5. The transfer station5feeds the folded boxes having not-yet-hardened glue seams to a collecting and pressing station6. A stream of folded boxes is produced as they pass from the transfer station5to the collecting and pressing station6. Therefore, the collecting and pressing station6includes pressing bands, by which the glue seams are maintained under pressure until the adhesive is securely set.

FIG. 2shows a three dimensional view of a folding station3, which includes a guide7for a folding strap8designed in accordance with a preferred embodiment of the present invention.FIG. 2shows the arrangement of the guide7in the folding station3, as well as the direction of travel L of the blanks through the folding box gluing machine.

FIG. 3shows a magnified isometric view of the guide7shown inFIG. 2, which folds the side pieces. The guide7includes a folding strap8, which is deflected by 90 degrees by a deflection roller9and guided across a positioning roller10. From the positioning roller10, the folding strap8travels across another deflection roller11and then across a first region of the folding station12to a deflection roller region located in a second region13, where the folding strap8is guided around three deflection rollers (seeFIG. 5). From the second region13, the folding strap8is guided to a third region15around individually adjustable pressure rollers14such that, beginning with the deflection roller11, the folding strap8is rotated by about 180 degrees along the entire path of the folding strap8. After moving through the system of several deflection rollers14arranged in the third region15, the folding strap8returns to the deflection roller9in the first region12of the folding station3.

In the first region12, the side piece of the blank, lying flat on the folding strap8at the beginning of the folding station, is rotated through about 90 degrees to a perpendicular position. The perpendicular position, also designated below as the vertical direction, is relative to the transport direction of the blanks, from the start of the folding station at the deflection roller11to the end of the third region15.

In the first region12, the folding strap8is deflected through about 90 degrees by a folding shunt16. The deflection of the folding strap8pushes up the side piece of the blank by about 90 degrees. Thus, the side piece is situated at a right angle to the plane of the transport direction and is perpendicular to the middle piece of the blank. The middle region13follows the first region12, and includes three deflection rollers defined by triple roller13′ (seeFIG. 5). These deflection rollers stabilize the guidance of the folding strap8. In the third and last region15of the folding station3, the folding strap8is guided across a number of pressure rollers14through about another 90 degrees in the direction of the plane of the flat lying region of the blanks.

According to the preferred embodiment of the present invention, the folding strap8is configured to be adjustable with respect to the folding line. For this, folding shunt16, triple roller13′ and the pressure rollers14are mounted on a linear guide17by adjustment devices18. The adjustment devices18enables horizontal and vertical adjustment of the folding shunt16, the triple roller13′ and the pressure rollers14. The adjustment devices18are freely adjustable in the preferred embodiment, and include screws20arranged in slots19, seeFIGS. 4 and 5. However, any suitable adjustment device could be used. For clarity, only one adjustment device18is designated by the reference numbers19,20. The other adjustment devices18may also include slots19and screws20. The folding shunt16is likewise provided with longitudinal holes19. By placing the pressure rollers14on a separate carriage21, as shown inFIG. 5, it is very easy to adjust the pressure rollers14. The triple roller13′ and the folding shunt16are also mounted in a similar manner and are easily adjustable. As shown inFIGS. 4 and 5, adjustment is clearly obtained using the slots19.

To ensure that the folding strap8optimally engages with the side pieces of the blanks in the entry zone of the blanks, the location of the positioning roller10is also adjustable. The folding strap8is fed over the deflection roller9to the positioning roller10. The location of the positioning roller10can be changed by a spindle drive with a set screw22, which turns in the direction of the arrow P. The adjustment will be explained usingFIG. 6as an example. If the position of the positioning roller10is changed by the set screw22, as indicated by the arrow M, the folding strap8will migrate across the deflection roller11in the direction of the arrow B. This enables adjustment of the folding strap8to the proper location on the side pieces to be folded via a very simple device when the blanks are fed in.

Adjustment of the folding strap8provides the advantage of optimal folding of the boxes in the region of the finished folding station3. It is always preferable to apply the folding strap8as far away from the folding line or groove line as possible, in order to minimize deviations from the angle-true folding, also known as fish-tailing, and to provide an optimal operating location. In all known folding box gluing machines, the operating location of the folding strap always lies in the immediate vicinity of and directly on the groove line of the bend. The present invention provides for adjustment of the folding strap8sideways in the forward starting region12. In the following folding shunt16, where the folding strap8is twisted from about 0 degrees to about 90 degrees, the folding shunt16is secured to the side in the forward region and adjustable in height in the rear region.