Unit and Method for Feeding Blanks

The present invention concerns a unit and a method for feeding blanks, intended to form boxes enclosing one or more articles.

The invention finds preferred but not exclusive use in an apparatus for packaging boxed articles, particularly suitable for packaging articles in accordance with a process in which it is provided for forming the box by folding a preformed blank.

The invention is applied in the apparatuses provided with a loading hopper intended to contain a plurality of blanks and subsequently feed them to a handling unit. Therefore, reference will be made below to this sector without thereby losing in generality.

In this description as well as in the claims appended thereto, certain terms and expressions are deemed to have, unless otherwise expressly indicated, the meaning expressed in the following definitions.

“Blank” means a shaped sheet of suitable material and thickness adapted to be folded to form a box. Preferably, the blank is made of cardstock. Preferably, the blank has two opposed substantially planar faces having dimensions substantially greater than the dimensions of the thickness of the blank itself. Preferably, the blank has a thickness of at least 0.2 mm, more preferably less than 4 mm. In a most preferred manner, the blank has a thickness comprised between 0.25 mm and 1.6 mm, more preferably between 0.3 mm and 1 mm, even more preferably between 0.4 and 0.8 mm.

A “folding line” of a blank is a predefined line made on the blank and intended to divide two panels of the blank and around which two panels of the blank are envisaged to rotate one relatively to the other so as to fold the blank, preferably to form a box. The folding line can be a virtual, albeit predefined, line. The folding line is preferably defined by a line of weakness obtained on the blank, such as for example a crease, or a scoring or a plurality of aligned holes.

By the term “stack” is intended to mean a plurality of substantially planar objects, in particular blanks positioned one above the other, or flanked one another. In particular, a stack of blanks is a set of blanks one placed in an adjacent manner to the other so that the faces of two adjacent blanks face each other. In the stack of blanks the faces of two adjacent blanks can be in contact with one another, or spaced apart from each other.

By the term “article” is intended to mean any product that is susceptible of being packaged into boxes. The articles can have a predefined geometric shape or they can have a variable geometry.

By “packaging” of one or more articles in a box is meant obtaining a box containing said one or more articles. Such packaging can be obtained by inserting one or more articles into an already formed box or, preferably, it can be obtained by forming a box around the one or more articles to be contained.

In general terms, a first element “abuts” a second element when the first element touches the second element and is able to at least partially oppose to a relative displacement of the first element against the second element.

In particular, the blank is “abutted” by a component of the feeding unit, such as for example a retaining element, when the component is in contact with the blank. It should be specified that the abutment of the blank does not in itself imply that the blank is abutted over its entire surface by a component of the feeding unit, but it is sufficient that there is a contact between the component and the blank on a portion of the blank.

“Box” means any container adapted to contain a plurality of articles for the purpose of packaging them, and which is susceptible of being made starting from a blank. The box can be obtained by folding a blank around a mandrel and then fixing the blank at its edges or panels. Preferably, the box has at least one closed contour section, more preferably it is closed laterally around the mandrel while the longitudinal ends are kept open.

By the term “movement direction” is intended to mean the direction along which an object, for example a blank, is displaced. The movement direction is represented by an oriented line.

With reference to a particular movement direction, a first element has an “advanced position”, or is defined as “advanced”, or is positioned “downstream” with respect to a second element when along the oriented line identified by said movement direction, the first element is in a position that is subsequent to the position of the second clement. In a completely similar way, a “backward position” or a position “upstream” of a first element with respect to a second element is also defined when along the oriented line identified by the direction, the first element is in a preceding position with respect to the position of the second element.

In the present description, by the definition “advanced blank” is intended to mean in particular the blank of the stack closest to an outlet section of the storage device.

The Applicant has preliminarily observed that the provision of a blanks feeding unit provided with a storage device, such as for example a loading hopper, intended to contain a stack of blanks and configured to feed in succession the blanks of the stack of blanks towards a handling unit allows to obtain significant advantages in terms of efficiency and feeding speed of the blanks. In fact, the subsequent blanks are moved in rapid succession one after the other towards the handling unit.

However, the Applicant has observed that the blanks may be torn, or ripped, in the transfer from the feeding unit to the handling unit. The Applicant has verified that the damages to the blanks are particularly evident and/or frequent when the blanks have limited thickness and strength and when the dimensions and/or the number of the blanks themselves increase.

In particular, the Applicant has observed that one of the critical steps in feeding the blanks, during which the blanks may be more subject to tears, is constituted by the picking of the blanks from the feeding unit by means of the handling unit.

To this end, the Applicant has found that a stack of blanks is loaded into a loading hopper provided with a movement mechanism for moving the blanks towards an outlet section of the hopper. At the outlet section of the hopper there are provided retaining elements intended to abut the advanced blank of the stack of blanks so as to prevent the unwanted escape of the same from the hopper. For picking the advanced blank from the loading hopper, there is usually provided a handling unit provided with gripping elements intended to engage the advanced blank. The handling unit is moved towards the loading hopper so as to engage the advanced blank with the gripping elements and subsequently moved to pick up the advanced blank from the loading hopper by disengaging it from the retaining elements.

The Applicant has observed that the retaining elements must be positioned in the loading hopper so as to avoid accidental escapes of the blanks, but at the same time allow the picking of the blanks from the hopper by the handling unit.

The Applicant has verified that the most critical step for the integrity of the blank is the transfer of the blank from the loading hopper to the handling unit. In this step, in fact, distinct portions of the blank are retained by the gripping elements of the handling unit and respectively by the retaining elements of the loading hopper, which tend to keep the advanced blank integral respectively with the handling unit and the loading hopper.

The Applicant therefore imagined to modify the retaining elements by reducing the interference with the advanced blank. However, the Applicant has found that this would have entailed the need to provide for further measures in order to avoid the accidental disengagement of the advanced blank from the retaining elements. The Applicant has therefore verified that some of these measures would not have been sufficient to obviate this inconvenience.

The Applicant has found that sometimes the blanks may not be abutted correctly by the retaining elements at the outlet section of the loading hopper.

The Applicant has verified that this negatively affects the correct picking of the blanks by the handling unit, favouring tears of the blanks during the picking step, or an incorrect positioning of the blanks on the handling unit. The Applicant has further verified that when the blanks are not correctly positioned on the handling unit, an incorrect folding of the blank to form the box can be generated and, therefore, a decrease in the quality of the boxes produced.

The Applicant has noted that frequent maintenance interventions by operators are necessary to modify the relative position between advanced blank and retaining elements, for example by adjusting the position of the retaining elements in the loading hopper.

However, the Applicant has verified that these interventions considerably slow down the productivity of the packaging apparatus since it is necessary to interrupt the operation of the feeding unit during the maintenance interventions.

Furthermore, the Applicant has verified that this approach does not prevent some blanks from being damaged, or compromised, during the picking by the handling unit. In fact, the maintenance interventions are usually planned after a plurality of blanks have been damaged or torn, in order to avoid interrupting the operation of the feeding unit unnecessarily, or due to an isolated malfunction.

The Applicant has also found that as the movement speed of the blanks in the loading hopper increases, for example to increase the production capacity of the packaging apparatus, the tears or rips in the blanks occur more frequently.

The Applicant, in order to reduce the occurrence of possible tears of the blanks, has therefore imagined to act on the movement mechanism of the blanks, for example by reducing the movement speed of the blanks in the loading hopper, or also on the handling unit, for example by reducing the speed of picking of blanks from the loading hopper.

However, the Applicant has found that these solutions would have strongly limited the production capacity of a packaging plant. The Applicant therefore verified that the possibility of using such blanks movement and handling systems was limited by the productivity required of the packaging apparatuses.

The Applicant has therefore understood that in order to limit the possibility of damaging the blanks during the picking by the handling unit, it was necessary to redesign blanks feeding unit.

The Applicant has therefore understood that in order to achieve the aforementioned purpose while maintaining high production capacities, it was necessary to identify an operating mode that would allow the position of the retaining elements to be adjusted as a function of objectively detectable process parameters.

The Applicant, in particular, has intuited that the possibility of generating damages to the blanks was correlated to the pressure exerted by the blanks on the retaining elements and, therefore, that an optimal position of the retaining elements that would allow to avoid tears or damages to the advanced blank without thereby limiting the feeding speed of the blanks, had to be correlated to the pressure exerted on them by the blanks.

Finally, the Applicant has found that a method and a unit for feeding blanks that provide for retaining a stack of blanks by means of at least one retaining element intended to abut a portion of the advanced blank, to detect the thrust pressure exerted on the retaining element and to adjust the position of said retaining element, or of another retaining element if provided, based on the pressure detected in said detection step, surprisingly allow to effectively retain the blanks avoiding unwanted tears thereof and at the same time maintaining high production speeds without the need to continuously recur to the action of an operator.

In other words, the Applicant has found that adjusting the position of a retaining element based on the pressure exerted by the advanced blank allows to effectively retain the blanks while avoiding the defects complained about above.

In a first aspect thereof, therefore, the present invention is directed to a blanks feeding unit.

Preferably, said unit comprises a blanks storage device for containing a stack of blanks and moving said stack along a movement direction towards an outlet section of said storage device.

Preferably, said unit comprises at least one retaining element provided at said outlet section and intended to abut an advanced blank of said stack at least at a portion of said advanced blank.

Preferably, said unit comprises a pressure sensor operatively connected to said at least one retaining element and intended to detect the pressure exerted on said at least one retaining element by said advanced blank.

Preferably, said unit comprises at least one further retaining element provided at said outlet section and intended to abut an advanced blank of said stack at least at a further portion of said advanced blank distinct from said portion.

Preferably, said unit comprises an adjusting device operatively connected to said pressure sensor and intended to adjust the position of said at least one retaining element based on the pressure detected by said pressure sensor.

Preferably, said unit comprises an adjusting device operatively connected to said pressure sensor and intended to adjust the position of said at least one further retaining element based on the pressure detected by said pressure sensor.

In a second aspect thereof, the present invention is directed to a method for feeding blanks.

Preferably said method comprises storing a stack of blanks in a storage device having an outlet section.

Preferably said method comprises moving said stack along a movement direction towards said outlet section, said stack comprising an advanced blank placed at the outlet section.

Preferably said method comprises retaining said stack of blanks at said outlet section by means of at least one retaining element intended to abut a portion of said advanced blank.

Preferably said method comprises detecting the pressure exerted on said at least one retaining element.

Preferably said method further comprises retaining said advanced blank by means of at least one further retaining element intended to abut a further portion of said advanced blank distinct from said portion.

Preferably said method comprises adjusting the position of said at least one retaining element based on the pressure detected in said detection step.

Preferably said method comprises adjusting the position of said at least one further retaining element based on the pressure detected in said detection step.