Title: Unit for feeding a sheet of material into a machine for the manufacture of packaging

Technical Field

The invention relates to a unit (feeder) for feeding a sheet of material into a machine for the manufacture of packagings, said unit comprising a frame with a height adjustable support for the sheets of material, said sheets preferably being present in the form of a stack.

Background Art

An apparatus for feeding and aligning a sheet is known, said machine having a double drive. Two "catch" wheels are provided, each being driven by its own motor and each optionally rotating with its own speed, said wheels being able to "catch" the top sheet of a stack of sheets in a tray. Simultaneous with advancing the sheets the catch wheels "align" them, i.e. turn the sheets a little with respect to their main advance direction. However, the apparatus does not operate reliably with respect to its aligning ability, especially when large sheets are being advanced.

The object of the invention is to provide a unit of the type disclosed in the preamble and being more reliable compared to the prior art.

Disclosure of Invention

The unit according to the invention is characterized in that it consists of two separate sets of continuous conveyors, the conveyors of each conveyor set being interconnected, and at least one of the conveyor sets being laterally adjustable in order to align each sheet of material with a main line operative for the remaining part of the machine for the manufacture of packaging. In this way, greater reliability and operation speed are obtained.

According to the invention, at least one set of interconnected conveyors may increase their sheet advancing velocity with respect to the sheet advancing velocity of the second set of interconnected conveyors. This provides better adjustment possibilities.

Moreover, according to the invention, at least one set of interconnected conveyors may laterally move a packaging sheet aligned at its front edge. This ensures that the advanced sheets can be centred with respect to the subsequent machine for the manufacture of packaging in a very reliable manner.

Furthermore, according to the invention, the front conveyor, seen in advance direction, of each conveyor set may consist of at least two rollers and a continuous belt led around them. This ensures an especially "good grip" of each conveyor set on the top sheet of material on said stack at any time.

According to the invention, the continuous belt for the front conveyor of each conveyor set may consist of a comparatively thick belt portion, the end of which being connected to a comparatively thin belt portion, the end of said latter belt portion being connected to the beginning of the comparatively thick belt portion. In this way, when the top sheet of the stack of sheets has been advanced so far into the unit that "the thick belt portion" lies opposite the sheet, said sheet may be easily moved sideways by means of said thick belt portion, since the thick belt portion exerts pressure on the sheet, in order to centre the sheet with respect to the subsequent machine for the manufacture of packagings.

Moreover, according to the invention, the front conveyor of each conveyor set may be provided with three rollers, around which the corresponding continuous belt is led. In practice, this has also proved to be particularly practical.

Further, according to the invention, the two sets of conveyors may each be driven by its own servo motor operational at different angular velocities, thus permitting the two conveyor sets to be brought to run with exactly the same advancing velocity.

Furthermore, according to the invention, each of the two conveyor sets may be driven by its own variable frequency motor thus achieving a very reliable operation of the unit

Finally and according to the invention, the packaging sheets may be of corrugated cardboard, solid (thick) cardboard or plastics. In practice, it has been found that the unit can advance this type of packaging sheet in a particularly reliable way.

Brief Description of the Drawing

The invention is explained in detail below with reference to the drawing, in which

Fig. 1 shows a perspective view of an embodiment of a unit according to the invention,

Fig. 2 shows a schematic lateral view of another embodiment of the unit, where said embodiment is now positioned on top of a stack of paper,

Fig. 3 shows a schematic top view of the same embodiment, and

Fig. 4 shows a lateral view of an embodiment of the conveyor belt, said belt consisting of a comparatively thick belt portion and a comparatively thin belt portion which are connected.

Best Modes for Carrying out the Invention

The embodiment shown in Fig. 2 of a unit for feeding a sheet of material into a machine for the manufacture of packaging 1 comprises a frame with height adjustable support 2 for sheets of material 3, as shown in Fig. 3. The latter is usually present in the form of a stack, as shown in Fig. 2. As shown in Fig. 1, the unit may possess two separate sets 4 and 5 of continuous conveyors. The conveyors 4a and 4b of conveyor set 4 are interconnected. Similarly, the conveyors 5 a and 5b of conveyor set 5 are interconnected. One conveyor set 4 of conveyor sets 4, 5 is laterally adjustable - this means first and foremost a lateral translational movement, cf. the double arrow A in Fig. 2 - in order to align the sheets of material advanced by means of this unit with a main line H operative for the remaining part of the machine for the manufacture of packaging 1. Usually, the second conveyor set 5 is not laterally adjustable.

The two separate sets of continuous conveyors 4 and 5 are usually mounted parallel to each other and on top of said stack. At least one of the conveyor sets, e.g. conveyor set 4, may increase its sheet advancing velocity compared to the sheet advancing velocity deliverable by the second set 5 of the interconnected conveyors.

Thus, it is possible to align (i.e. turn) the sheet of material (on top) which is being advanced. Turning takes place such that it results in the front edge of the sheet being exactly perpendicular to the advance direction of Hie sheet.

The front conveyor 4a, 5 a, seen in advance direction, of the conveyor set 4 and 5 may e.g. consist of two, three or more rollers 12a, 12b and 13a, 13b, 13c, and a continuous belt 12', 13' is led around each of these roller sets.

With respect to the continuous belt 12' or 13' for the front conveyor of each conveyor set 4 5, it may consist of a comparatively thick belt portion 12'a, the end 12'a _o of which being connected to the beginning of a comparatively thin belt portion 12'b, the end 12'b ₀ of said latter belt portion being connected to the beginning of the comparatively thick belt portion 12'a, as shown in Fig. 4. This ensures that pressure exerted by the unit on the top sheet of the stack can increase a

little, when said comparatively thick belt portion 12'a is positioned above the top sheet of the stack,, which is advantageous, if the conveyor is to be moved laterally for a moment and is to pull the top sheet of the stack for a short distance.

Instead, the front conveyor 4a, 5 a of each conveyor set 4, 5 may be provided with three rollers (cf. Fig. 1), around which the corresponding continuous belt 12', 13' is led, as shown in Fig. 2. Normally,, the conveyor 4b, 5b, the "next in line" in each conveyor set 4 or 5, is only provided with two rollers, around which a continuous belt runs.

The two sets of conveyors 4, 5 may be driven by their own servomotors (not shown), and each servomotor may operate at different angular velocities.

Optionally, each servomotor may be a variable frequency motor (not shown).

The invention may be modified in many ways without thereby deviating from its scope. Thus, each conveyor may consist of more than three rollers and a continuous belt led around them.