EP2311763A1

EP2311763A1 - Machine for forming packs of folded napkins, provided with means for synchronizing the speed of advancing movement of the pack separating element

Info

Publication number: EP2311763A1
Application number: EP10187093A
Authority: EP
Inventors: Marcello Tommasi
Original assignee: Omt Srl
Current assignee: Omt Srl
Priority date: 2009-10-15
Filing date: 2010-10-11
Publication date: 2011-04-20
Anticipated expiration: 2030-10-11
Also published as: IT1395942B1; ITMI20091778A1; EP2311763B1

Abstract

Machine for forming packs (P) of napkins (1c) folded into four, comprising a pair of cylinders (10) for picking up a sheet of paper (1) suitably pre-folded and feeding said sheet (1) folded along vertical folding lines (1b), said folding means (1a) also performing counting of the napkins which must form each pack; a conveying surface (20) with vertical shoulders (21) for supporting and retaining the napkins (1c); means (30) for unloading each pack (P) formed by a given number of napkins and extracted from the machine, said means being associated with at least one sensor (40) able to detect a pressure corresponding to the presence of a complete pack and emit corresponding consent signals to programming and control means (1000); an apparatus (100) for separating the packs (P₁..P_n) formed in succession, which comprises a feeler arm (110) movable rotationally about an axis parallel to the transverse direction (Y-Y), from a lowered position, where it engages with the first napkin in a pack, into a raised position where it does not interfere with the advancing packs (P) and vice versa; said feeler arms being mounted on a transverse shaft (112) operated displaceably by associated pneumatic cylinders (114) designed to move the feeler arms from a position advanced in the longitudinal direction (X-X) into a position (M2) retracted in the same longitudinal direction; means (200) for retaining the advancing packs (P) in the longitudinal direction (X-X), substantially comprising a pair of flanges (210) movable rotationally about an axis parallel to the longitudinal direction (X-X) from a raised, non-interfering position into a lowered position where they interfere with the first pack (P_n) which is advancing towards the unloading means (30); the flanges (210) being displaceable in the longitudinal direction (X-X) from an advanced position (F1) close to the unloading means (30) where the upwards rotation for disengagement from the pack (P) occurs into a retracted position (F2) where they rotate downwards so as to interfere with the advancing pack (P), the means for performing displacement of the flanges (210) comprising an electric motor (300) controlled by the programming and control means (1000) able to determine a corresponding speed of forwards displacement of the flanges (210).

Description

The present invention relates to a machine for forming packs of napkins folded into four, provided with means for synchronizing the speed of advancing movement of the pack separating means.
In the paper processing industry it is known that there are machines for the production of paper napkins formed from a continuous strip which is folded in the longitudinal direction (parallel to the direction of advancing movement) and fed to a pair of counter-rotating cylinders provided with means for producing a fold in the same strip in the transverse direction so as to form a continuous pleat which is moved forwards, in a guided manner, towards a fixed blade which cuts the pleat into two in the longitudinal direction, producing two rows of napkins which are folded and separate from each other and which are moved forwards in a parallel manner along the machine.
It is also known that the two rows of napkins must be divided into separate packs which are each formed by a precise and specific number of napkins and which must be removed from the forming machine and supplied to the packaging machine for packaging thereof.
Although performing their function, the operating devices of the known machines have, however, a structural limitation in that it is not possible to ensure correct and continuous operation of the machine in all those cases where variations in the thickness of the paper strip occur or where there is a variation in the working speed due to the different characteristics of the paper strip and machine stoppages in order to change the reel; this reduces significantly the efficiency of the machine owing to the repeated stoppages, large number of finished product rejects and incorrect transfer of the packs of napkins from the forming machine to the packaging machine.
The technical problem which is posed, therefore, is to provide a machine for producing napkins and for dividing them into packs formed by a specific and constant number of napkins, said machine being equipped with apparatus which provide a solution to the abovementioned problems of known machines.
In connection with this problem a further requirement is that the apparatus should be able to reduce the damage to the sheets at the moment of separation and/or movement away from each other of the two sheets in adjacent packs and that said apparatus should also be suitable for application to ready-existing machines with a limited need for special adaptation.
These results are achieved according to the present invention by a machine for forming packs (P) of napkins folded into four, comprising a pair of cylinders for picking up a sheet of paper suitably pre-folded along a longitudinal folding line and feeding said sheet folded along vertical fold lines; said folding means also performing counting of the napkins which must form each pack; a conveying surface with vertical shoulders for supporting and retaining the napkins; means for unloading each pack (P) formed by a given number of napkins and extracted from the machine, said means being associated with at least one sensor able to detect a pressure corresponding to the presence of a complete pack and emit corresponding consent signals to programming and control means; an apparatus for separating the packs formed in succession, which comprises a feeler arm movable rotationally from a lowered position, where it engages with the first napkin in a pack, into a raised position where it does not interfere with the advancing packs (P) and vice versa; said feeler arms being mounted on a transverse shaft operated rotationally by associated pneumatic means and displaceably by associated pneumatic cylinders (114) designed to move the feeler arms from a position (M1) advanced in the longitudinal direction (X-X), where the downwards rotation occurs, into a position (M2) retracted in the same longitudinal direction, where the feeler arms are raised; means for retaining the advancing packs (P) in the longitudinal direction (X-X), substantially comprising a pair of flanges movable rotationally about an axis parallel to the longitudinal direction (X-X) from a raised non-interfering position into a lowered position where they interfere with the first pack (P_n) which is advancing towards the unloading means; said retaining means being mounted on a respective longitudinal pin rotationally operated by associated pneumatic actuating means where the flanges are displaceable in the longitudinal direction (X-X) from an advanced position close to the unloading means where the upwards rotation for disengagement from the pack (P) occurs into a retracted position (F2) where they rotate downwards so as to interfere with the advancing pack (P), the means for performing displacement of the flanges comprising an electric motor controlled by the programming and control means which determine the sequences of movements of the various parts of the machine and said programming and control means being able to detect the speed of rotation of the cylinders and therefore advancing movement of the sheet and determine a corresponding speed of forwards displacement of the flanges.
Further details may be obtained from the following description of a non-limiting example of embodiment of the subject of the present invention provided with reference to the accompanying drawings in which:

Figure 1:: shows a schematic top plan view of the machine according to the present invention;
Figure 2:: shows a side view of the machine according to Fig. 1;
Figure 3:: shows a side view of the machine according to Fig. 1 during completion of a pack of napkins;
Figure 3a:: shows a front view of the machine according to Fig. 3;
Figure 4:: shows a side view of the machine according to Fig. 1 during unloading of the completed pack; and
Figure 4a:: shows a front view of the machine according to Fig. 4.

As shown in Figs. 1 and 2 and assuming solely for the sake of convenience of description and without any limitation in meaning a set of three reference axes in a longitudinal direction X-X, transverse direction Y-Y and vertical direction Z-Z, respectively, as well as a front part corresponding to the part where the packs of napkins exit and a rear part opposite to the front part, the machine according to the present invention comprises essentially:

a pair of cylinders 10 which are fed with a sheet of paper 1 suitably pre-folded along a longitudinal folding line by means 1a; upon leaving the cylinders 10 said sheet 1 is already folded along vertical fold lines 1b so as to form a continuous strip 2 which is folded into four and which, pushed by the rotation of the cylinders 10 towards the front part of the machine, is intercepted by a cutting blade 2a which, acting in the longitudinal direction, cuts the strip, forming two lines of napkins 1c folded into four and individually separated from each other;
a surface 20 with vertical shoulders 21 for supporting and retaining the napkins 1c;
means 30 for retaining and unloading each pack P which is formed by a given number of napkins and is extracted from the machine and conveyed to the packaging machine (not shown);
sensor means 40 associated with the retaining and unloading means 30 and designed to detect the presence of a complete pack P by means of the pressure exerted longitudinally by the same and emit the start-of-cycle signals of the separation apparatus;
an apparatus 100 for separating packs P₁..P_n formed in succession, said apparatus comprising:
- a pair of feeler arms 110, one for each line of napkins 1c, which are movable rotationally about an axis parallel to the transverse direction Y-Y, from a lowered position into a raised position and vice versa so as to interfere with / free the advancing packs P and retain / allow movement thereof in the longitudinal direction X-X; said feeler arms being mounted on a transverse shaft 112 operated by associated pneumatic means 111;
means 200 for retaining the advancing packs P in the longitudinal direction X-X, substantially comprising a pair of flanges 210 movable rotationally about an axis parallel to the longitudinal direction X-X from a raised non-interfering position into a lowered position where they interfere with the first pack P which is advancing towards the unloading means 30; said retaining means being mounted on a respective longitudinal pin 211 rotationally operated by associated pneumatic operating means 213.

It is also envisaged that:

the feeler arms 110 are displaceable from a start-of-cycle position M1 advanced in the longitudinal direction X-X, where the downwards rotation and engagement with the first napkin in the advancing pack occur, into a position M2 retracted in the same longitudinal direction X-X, where the feeler arms are raised; said displacement is produced by means of pneumatic cylinders 114, the rod of which acts on a cross-piece 114a supporting the shaft 112 of the feeler arms.
the flanges 210 are in turn displaceable in the longitudinal direction X-X independently of the displacement of the feeler arms 110 from a start-of-cycle position F1 close to the retaining and unloading means 30 where the upwards rotation for disengagement from the pack P occurs into a retracted position where the flanges rotation downwards so as to interfere with the advancing pack P.

The operating device which produces the displacement of the flanges 210 is formed by an electric motor 300, which is preferably of the brushless or stepper type, controlled by the programming means 1000 which also control the sequences of movements of the various parts of the machine, which programming means are also able to control the speed of rotation of the cylinders 10 and therefore the speed of advancing movement of the sheet 2; this means that the advancing movement of the packs P and extraction thereof is always linked to the actual speed of movement of the sheet 2 which forms the napkins, this being a factor which, as will emerge more clearly below, is decisive for correct operation of the machine when there is variation in the characteristics of the paper. The constructional details of the mechanical supporting and transmission parts are not described here, since they are conventional per se and lie within the competence of the person skilled in the art.
With the machine structure described above, the general embodiments of which are already known in the art, the operating principle of the machine in accordance with sequences programmed and controlled by the unit 100 is as follows:

at the start of the cycle the feeler arms 110 and the flanges 210 are located in their initial positions, M1 and F1, respectively engaged with and disengaged from the advancing packs P_n-1 and P;
the longitudinally folded sheet 1 is pulled by the cylinders 10 and expelled by them in the longitudinal direction further folded along vertical folding lines so as to supply a continuous sheet which is already folded into four and which, cut by the blade 2a, gives rise to the formation of rows of correctly folded napkins;
the longitudinal folding device 1a arranged at the entry point of the two cylinders performs simultaneously a synchronized movement from the top downwards so that the succession of a predetermined number of napkins arranges the same with their upper edge at different heights so that the last napkin in the front pack P_n is lower than the first napkin in the immediately adjacent rear pack P_n-1; the same synchronized movement produces the correct number of napkins which form each pack;
rotation of the two cylinders with feeding of the sheet 2 folded into four also produces the advancing movement in the longitudinal direction X-Y of the two parallel rows of napkins 1c;
when the pack P_n-1 of each row reaches a predetermined position M1, the corresponding feeler arm 110, which is rotated downwards, intercepts the first napkin in the pack P_n-1 (Fig.3) and retains the whole row until the means 30 for unloading the front pack P_n start to rotate downwards, separating the two packs and allowing entry of the flanges 210 which are present in the position F2 and, rotating downwards, are arranged in front of the first napkin of the preceding pack P_n-1 (Fig. 4);
at this point the feeler arm 110 rotates upwards, freeing the row of napkins, which is able to advance towards the unloading means 30, retained by the flange 210 which moves forwards together with the napkins upon operation of the drive motor 300;
when the longitudinal position F1 close to the unloading means 30 is reached, the flange 210 receives the consent signal from the sensors 40 and rotates upwards, disengaging the pack P_n and allowing the further accumulation of napkins against the unloading means 30 so that, when the pressure exerted on the sensor 40 corresponds to that produced by the exact number of napkins in the pack, the sensor sends a corresponding signal so that the means 30 rotate again downwards in order to unload the formed pack; at the same time the feeler arm 110 has lowered again and the flange 210 has been recalled into the initial position ready to be lowered when the means 30 rotate so as to pick up the new pack P_n-1 being formed.

The decisive factor in the sequence of movements described above is the advancing movement of the flanges 210 from the retracted engaged position F2 into the advanced disengaged position F1 produced by the motor 300, the speed of rotation of which is controlled by the programming device 1000 linked also to the speed of rotation of the two cylinders 10 and therefore to the speed of advancing movement of the sheet 1 entering the cylinders, so that any variation in the speed of movement of the sheet 1, due to different characteristics of the paper, is compensated for by a corresponding different speed of movement of the flange 210 which thus compensates for any different speeds of movement and prevents incorrect formation of the packs present on the conveying surface along the entire exit section from the cylinders/unloading means.
Although described in connection with certain constructional forms and certain preferred examples of embodiment of the invention, it is understood that the scope of protection of the present patent is defined solely by the following claims.

Claims

Machine for forming packs (P) of napkins (1c) folded into four, comprising:
- a pair of cylinders (10) for picking up a sheet of paper (1) suitably pre-folded along a longitudinal folding line via associated means (1a) and feeding said sheet (1) folded along vertical fold lines (1b) so as to form a continuous strip (2) folded into four; said folding means (1a) also performing counting of the napkins which must form each pack;

- a conveying surface (20) with vertical shoulders (21) for supporting and retaining the napkins (1c);

- means (30) for unloading each pack (P) formed by a given number of napkins and extracted from the machine, said means being associated with at least one sensor (40) able to detect a pressure corresponding to the presence of a complete pack and emit corresponding consent signals to programming and control means (1000);

- an apparatus (100) for separating the packs (P₁..P_n) formed in succession, which comprises:
a feeler arm (110), for each line of napkins (1c), movable rotationally about an axis parallel to the transverse direction (Y-Y), from a lowered position, where it engages with the first napkin in a pack, into a raised position where it does not interfere with the advancing packs (P) and vice versa; said feeler arms being mounted on a transverse shaft (112) operated rotationally by associated pneumatic means (111) and displaceably by associated pneumatic cylinders (114) designed to move the feeler arms from a position (M1) advanced in the longitudinal direction (X-X), where the downwards rotation occurs, into a position (M2) retracted in the same longitudinal direction, where the feeler arms are raised;

means (200) for retaining the advancing packs (P) in the longitudinal direction (X-X), substantially comprising a pair of flanges (210) movable rotationally about an axis parallel to the longitudinal direction (X-X) from a raised non-interfering position into a lowered position where they interfere with the first pack (P_n) which is advancing towards the unloading means (30); said retaining means being mounted on a respective longitudinal pin (211) rotationally operated by associated pneumatic actuating means (213) where the flanges (210) are displaceable in the longitudinal direction (X-X) from an advanced position (F1) close to the unloading means (30) where the upwards rotation for disengagement from the pack (P) occurs into a retracted position (F2) where they rotate downwards so as to interfere with the advancing pack (P),
said machine being characterized in that
the means for performing displacement of the flanges (210) comprise an electric motor (300) controlled by the programming and control means (1000) which determine the sequences of movements of the various parts of the machine
and in that
said programming and control means are able to detect the speed of rotation of the cylinders (10) and therefore advancing movement of the sheet (2) and determine a corresponding speed of forwards displacement of the flanges (210).
Machine according to Claim 1, characterized in that it comprises a cutting blade (2a) which, acting in the longitudinal direction, cuts the strip forming two lines of napkins (1c) folded into four and individually separated from each other.
Machine according to Claim 1, characterized in that said electric motor is of the brushless type.
Machine according to Claim 1, characterized in that said electric motor is of the stepper type.