METHOD AND APPARATUS FOR COVERING BOXES

Covering of raw boxes with a sheet blank in a box laminating machine with a rubbing-down device that sweeps or rolls over the surface to be covered and a counter-holder that interacts with said rubbing-down device, wherein the rubbing-down operation takes place during a transport movement of the box and the counter-holder plunges into the box in order to support the wall to be covered against the rubbing-down device.

BACKGROUND

The present invention pertains to a method for covering boxes according to the preamble of claim1and to an apparatus for carrying out the method according to the preamble of claim6.

A system for producing boxes with an apparatus for covering the raw boxes is disclosed in publication US2009/0156380A1. In this system, the raw boxes and the cover material provided with glue, i.e., the sheet blanks, are fed from respective upstream apparatuses to a joining device by means of transport devices. This joining device places the bottom of the raw box on the glued side of the sheet blank. The sheet blank is rolled down on all four box walls in a downstream apparatus. Any protrusion of the sheet blank is turned inward. A covering device is assigned to each wall for this purpose.

The four covering devices are arranged opposite of one another in pairs. They respectively have a rubbing-down roller and a turn-in slide. Joining of the sheet on the outer walls takes place by rolling the rubbing-down rollers on the outer sides of the box. For this purpose, the box is vertically transported through between the stationary first pair of covering devices in a first step. The box subsequently remains in a resting position and the turn-in slides of the first pair turn the protrusions of the sheet blank inward. Subsequently, the second pair of covering devices rolls the sheet on the remaining walls in a vertical movement of their rubbing-down rollers before their turn-in slides turn in the remaining protrusions. A form punch is subsequently lowered into the covered box in order to rub down the turned-in cover on the inner sides of the box.

Such a covering device allows a compact construction. However, one disadvantage can be seen in the resulting poor accessibility of the components. Cleaning of the elements that come in contact with the cover sheet particularly is impeded. Only one pair can process the box at all times due to the arrangement of the covering devices relative to one another. The other pair has to wait until this processing is completed or the box is transported out of the apparatus. The capacity of the system therefore remains limited. The form punch has to be manufactured extremely true to size in order to reliably glue the turn-ins of the sheet to the inner surfaces of the raw box on the one hand and to prevent damages to the box on the other hand. This requires a separate form punch for each inside dimension of a box to be produced. Format deviations of the raw boxes, e.g., due to manufacturing tolerances or climatic influences, also lead to corresponding quality losses of the finished boxes or even rejects.

SUMMARY

An objective of the present invention therefore can be seen in developing an apparatus that is improved in comparison with the prior art, eliminates at least one of the aforementioned disadvantages of the prior art and meets the increased requirements regarding the product quality to be achieved.

The box laminating machine comprises different processing devices and transport devices. These processing devices are arranged on the transport paths of the transport devices. A transport system successively transports the respective blank box to be covered into different processing stations of the box laminating machine for processing. In this case, the transport of the blank box to be covered takes place in a plane extending parallel to the bottom of the blank box. However, the laminating machine at least comprises a transport device and a side rolling-down device.

This side rolling-down device is arranged on the transport path of the transport device. It has at least one rubbing-down element and one counter-holder assigned to this rubbing-down element. The counter-holder plunges into the raw box. The rubbing-down element subsequently rubs down the corresponding wall region of the sheet blank on the associated wall of the raw box against the counter-holder. For this purpose, the rubbing-down element sweeps over the wall of the box in a rubbing-down movement. The rubbing-down operation takes place during the continuing transport movement of the raw box. In this context, it is irrelevant whether the rubbing-down element is formed by a rail, a brush or an optionally driven roller.

The apparatus has a first guidance system of the rubbing-down element, which defines the movement path of the rubbing-down element. A second guidance system of the counter-holder defines the movement path of the counter-holder. This movement path of the counter-holder comprises at least one segment that is oriented parallel to the transport path of the raw box. The rubbing-down operation during the continuing transport of the box allows a temporal overlap of movements such that an increased throughput can be achieved.

The movement of the counter-holder is advantageously composed of multiple linear partial movements. The movement of the counter-holder particularly is formed by two partial movements that run orthogonal to one another. These partial movements do not necessarily take place successively. In fact, they may overlap in time such that a curved overall movement of the counter-holder takes place.

In this context, a first linear partial movement preferably runs parallel to a surface normal of the bottom of the blank box. The first partial movement then is directed toward or away from the bottom surface. A second linear partial movement runs orthogonal to this first partial movement and therefore parallel to the bottom of the blank box and parallel to the transport direction of the blank box.

The second partial movement advantageously is at least temporarily identical to the continuing transport movement of the box with respect to its direction and amount. A relative movement between the counter-holder and the raw box is precluded as long as the rubbing-down element exerts a force upon the wall and the counter-holder in that the counter-holder plunged into the box is moved in the same way as the raw box during the rolling-down operation. The counter-holder can be designed true to format and support the wall over its entire surface.

A closed, revolving movement of at least the counter-holder is advantageously realized. In this way, the sequences of movement of the individual elements can overlap in a particularly time-saving manner.

In a particularly advantageous embodiment, the second guidance system assigned to the counter-holder has at least one first linear guide. This first linear guide is aligned parallel to the transport direction. This makes it possible to reliably prevent undesirable movements of the counter-holder transverse to the transport direction, which affect the quality of the box.

The second guidance system assigned to the counter-holder preferably comprises a second linear guide that defines a movement plane together with the first linear guide. The first partial movement and the second partial movement run parallel to this plane defined by the linear guides. In this way, any two-dimensional movement patterns, particularly curved movement patterns, can be imparted on the counter-holder. The second linear guide preferably is arranged orthogonal to the first linear guide.

As an alternative to multiple linear guides, the second guidance system assigned to the counter-holder may also have a curved guide. In this case, this curved guide defines the first linear movement segment and the second linear movement segment.

According to a special embodiment, the width of the counter-holder corresponds to the inside length of the raw box. The associated wall therefore is supported over its entire surface and undesirable damages are prevented. In this case, one of its partial movements follows the transport movement of the blank box with respect to its direction and speed. This synchronous movement of the box and the counter-holder prevents relative movements between the box and the counter-holder as long as the rubbing-down element exerts a force upon the wall. This makes it possible to prevent quality losses.

The counter-holder preferably is formed by two interconnected rails. At least a section of the respective rails is with respect to time and space at least sectionally arranged opposite of the rubbing-down element. These rails preferably are spaced apart from one another in such a way that the jointly formed contour is narrower than the inner side of the associated wall of the raw box. In this way, the counter-holder can be easily introduced into the raw box and inadvertent displacements of or damages to the raw box are prevented. In this context, the greatest possible spacing between the rails is advantageous for reliably preventing the undesirable tendency of the box to rotate about the rails during the rolling-down operation.

The extent of the individual rails forming the counter-holder in the transport direction of the blank boxes preferably is small in relation to the length of the blank box in the same direction. A supporting plate is arranged between the rails in order to bridge the thusly formed gap. The supporting plate forms the counter-holder together with the rails. In this way, the counter-holder can be adjusted to different lengths by simply exchanging the supporting plate.

The bottom of the box is aligned horizontally during the entire rubbing-down operation in order to allow a simple construction and easy accessibility.

The box laminating machine preferably comprises multiple side rolling-down devices of this type along the transport path such that all walls of the blank can be covered in one pass of the box.

DETAILED DESCRIPTION

FIG.1schematically shows the product flow during a box covering operation. The raw boxes2are respectively made available in a standby position by an infeed7. For this purpose, the box infeed7has a transport device with a first conveyor belt31. The raw boxes2are moved into the standby position such that their bottom21points downward and is aligned horizontally. The end walls22of the raw box2are oriented parallel to the feed direction whereas the sidewalls23are oriented transverse to the feed direction. The feed direction extends transverse to the transport path1000, on which the processing devices100,200are arranged. The standby position of the raw boxes is arranged adjacent to a band conveyor30of the sheet infeed8supplying the sheet blanks1.

The sheet blanks1are glued individually, transferred to the band conveyor30and moved along a linear transport path1000. Suitable apparatuses for applying glue on the sheet1are sufficiently known and therefore not illustrated in the figures or described in greater detail. A not-shown robot picks up the supplied raw box2and places it on the bottom region11of the cover sheet1in an accurately positioned manner in a curved downward movement1010. The now connected unit3consisting of the raw box2and the sheet blank1glued to its bottom21is transferred to a conveyor device9that follows the band conveyor30and has the same transport direction1000.

The conveyor belts32of this conveyor device9transport the box units3through the processing devices100,200arranged along the transport path1000in order to completely cover the box units3.FIG.2shows the elements101,105,106of a side rolling-down device100that interact with the box unit3. A second, identical side rolling-down device arranged on the opposite side is not illustrated in order to provide a better overview.

A rubbing-down roller105is illustrated in its starting position underneath the movement path of the box units3. The rubbing-down roller105is essentially cylindrical. Its rotational axis extends parallel to the transport direction1000of the box units3. The rubbing-down roller105rolls on the sidewall23in a vertical partial movement1004from its starting position and in the process rolls down the associated outer region13of the sheet blank1on the sidewall23.

A counter-holder101is provided in order to support the sidewall23against the rubbing-down roller105during the rolling-down operation. This counter-holder101is formed by a pair of rails102,103. A supporting plate104is arranged between the rails102,103in order to realize a full-surface support. These elements jointly form a supporting surface115that extends parallel to the associated box wall23. Linear guidance systems are provided in order to allow a revolving movement1005of the counter-holder101. A horizontally oriented linear guide111is arranged parallel to the transport path1000of the box units3. It accommodates a vertically aligned linear guide109in the manner of a coordinated table. The rails102,103of the counter-holder101are accommodated in the vertical linear guide109. The vertical guide109is connected to a drive112in such a way that it can be moved along the horizontal guide111. The vertical partial movement1002of the counter-holder101is generated by another drive110that acts upon the rails102,103. This drive110for the vertical partial movement1002of the counter-holder101comprises a guide track114that can be vertically moved in a motor-driven manner. This guide track extends parallel to the transport direction1000of the box units3. A roller113arranged on a rail103of the counter-holder runs in the guide track114in order to transmit its vertical movement1002to the counter-holder101.

The counter-holder101plunges into the raw box1from its starting position1100above the box unit3during a closed, revolving movement1005on the sidewall23while the box3is continuously transported in the predefined direction1000by the belts32. The revolving movement1005of the counter-holder101essentially takes place in a plane extending parallel to its supporting surface115. InFIG.2, this plane is defined by the transport path1000of the box units3, which extends in a horizontal x-direction, and a vertical y-direction. The revolving movement1005is composed of multiple segments. The lowering segment1006into the box3begins in the starting position1100above the box unit3and ends within the box unit3at or slightly above its bottom21. It can be dissected into a vertical portion1002and a simultaneous horizontal portion1001. The lowering segment1006essentially is characterized by a vertical downward movement relative to the box. The lowering segment1006is followed by a holding segment1007, during which the counter-holder101maintains a fixed position relative to the box unit3. The counter-holder101moves synchronous with the box unit3in its transport direction1000. The actual rubbing-down operation of an outer region13of the sheet blank1on the outer surface of the associated box wall23by means of the rubbing-down roller105takes place during this holding segment1007. The subsequent lifting segment1007corresponds to the lowering segment1006with a reversed vertical partial movement1002. The counter-holder101subsequently returns into its starting position1100in a horizontal return movement1009.

FIG.4shows the temporal correlations between the partial spatial movements1000,1001,1002,1004in accordance with the coordinate systems in the illustrations inFIGS.1to3in the form of a movement diagram. In this case, all movements1000,1001,1002,1004are illustrated in a simplified manner and composed of linear portions with different gradients. The transport movement1000of the box unit3is illustrated in the form of a dotted line. It extends in the form of an ascending straight line in the x-direction as a function of the time t.

The horizontal movement1001of the counter-holder101is illustrated with a broken line and divided into the holding segment1007and the return movement1009. The progression of the horizontal movement1001is identical to the transport movement1000of the box units3during the holding segment1007. The vertical partial movement1002of the counter-holder101is illustrated with a continuous line. The coinciding gradient jumps of the vertical partial movement1002and the horizontal partial movement1001of the counter-holder101characterize its starting position1100. The holding segment1007is defined by the lower end position of the vertical movement1002.FIG.4clearly shows that the segment of the horizontal movement1001, which takes place synchronous with the transport movement1000, comprises in terms of time the movement segments lowering1006, holding1007and lifting1008.

The vertical partial movement1004of the rubbing-down roller105is likewise illustrated with a continuous line. The rubbing-down operation takes place during the upward movement. This upward movement coincides with the holding segment1007of the counter-holder101. The horizontal partial movement of the rubbing-down roller105ensures that a rolling movement on the box unit3only runs perpendicular to the bottom21. A relative movement of the rubbing-down roller105transverse to the box3is prevented. The horizontal partial movement of the rubbing-down roller105is not illustrated, but simply identical to the horizontal partial movement1001of the counter-holder.

The movement diagram inFIG.4shows the sequences of movement in a schematically simplified manner. Curved transitions may be chosen instead of the gradient jumps. This particularly makes it possible to advantageously influence the machine dynamics. In addition, the movement segments and partial movements shown may shift relative to one another or overlap. In this way, the loads occurring due to the machine dynamics can be additionally reduced and the processing times can be improved. These adaptations can be optimized in dependence on the dimensions of the boxes2or the sheet blanks1.

REFERENCE SYMBOLS