Method and device for feeding reels to a machine

A device (2) for feeding reels (3) has a manipulator (14) having a gripping member (19) for picking up one reel (3) at a time off a pallet (16) and transferring the reel (3) to an unwinding pin (4a; 4b) on a machine (1); the gripping member (19) is enabled to pick up a reel (3) off the pallet (16) when at least one reference point (k1) of the gripping member (19) lies inside a central hole (7) of the reel (3).

This application is the national phase under 35 U.S.C. § 371 of PCT International Application No. PCT/IT02/00313 which has an International filing date of May 13, 2002, which designated the United States of America.

TECHNICAL FIELD

The present invention relates to a method of feeding reels to a machine.

More specifically, the present invention relates to a method of feeding reels to a machine defined by a cigarette packaging machine, to which the following description refers purely by way of example.

BACKGROUND ART

Cigarette packaging machines now operate at such high output rates as to require large amounts of packaging material, which is partly supplied in the form of strips wound into reels. Each reel comprises a strip of packaging material wound about a spool having a central hole, and is fitted onto an unwinding pin on the packaging machine. The strip of packaging material is unwound off the reel, and sheets of packaging material are cut off the strip and folded about groups of cigarettes.

The increase in the amount of packaging material required calls for automatic reel handling to speed up reel feed to the machine, which in turn calls for determining the position of the reel to enable a reel manipulator to grip the reel by means of a gripping member and align the reel with an unwinding pin on the packaging machine.

Patent EP-A-551,854 relates to a manipulator featuring a reel gripping member and for picking reels off a pallet on which the reels are arranged with their respective axes positioned vertically. The gripping member has a TV camera for picking up an image of a reel; and an arithmetic unit for processing the image data by means of an algorithm based on translation and inversion of the image to determine the coordinates of a characteristic point on the reel. Once the coordinates of the characteristic point on the reel are determined, the manipulator sets the gripping member to a given position to grip the reel correctly.

Though reliable and capable of transferring a large number of reels per unit of time, the arithmetic unit of the above manipulator for processing the points in the image is relatively expensive.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a straightforward, low-cost method of feeding reels to a machine.

According to the present invention, there is provided a method of feeding reels to a machine from a store of reels close to said machine; each reel having an axis, a central hole which is engaged by an unwinding pin on said machine, and two flat faces perpendicular to said axis; and the method being characterized by determining whether at least one reference point of a gripping member of a manipulator lies inside the hole of a reel in the store; picking up said reel by means of the gripping member when the reference point lies inside the hole of said reel; and transferring said reel from said gripping member to said unwinding pin.

The present invention also relates to a device for feeding reels to a machine.

According to the present invention, there is provided a device for feeding reels to a machine from a store of reels close to said machine; each reel having an axis, a central hole which is engaged by an unwinding pin on said machine, and two flat faces perpendicular to the axis; and the device being characterized by comprising a manipulator having a gripping member for picking up a reel from said store when at least one reference point of the gripping member lies inside the hole of said reel.

BEST MODE FOR CARRYING OUT THE INVENTION

Number1inFIG. 1indicates as a whole a cigarette packaging machine for producing packets of cigarettes not shown.

Machine1comprises a feed device2for supplying reels3; and two unwinding pins4aand4bfor unwinding reels3. Pin4ais shown in a position supporting a reel3being unwound; and pin4bin a position to receive a reel3from feed device2.

Each reel3has an axis5, and comprises a spool6having a hole7; and a strip8of packaging material wound about spool6to form two parallel, substantially flat lateral faces9perpendicular to axis5, and a substantially cylindrical face10parallel to axis5.

Machine1comprises a frame11supporting unwinding pins4aand4b, each of which has an axis12and a drive member13for switching pin4a,4bbetween the unwinding position in which axis12is horizontal, and the receiving position in which axis12is vertical.

Device2for feeding reels3comprises a manipulator14for manipulating reels3, and a platform15for supporting a pallet16on which reels3are arranged in orderly manner with respective axes5positioned vertically. Manipulator14comprises an articulated arm17fixed at one end to frame11to rotate about a vertical axis18, and supporting at the opposite end a gripping member19for gripping one reel3at a time. Platform15is set to a given position with respect to machine1, and comprises a lifting device20, and locating elements21for locating pallet16with respect to platform15.

Gripping member19is bell-shaped with an axis A, and, as shown more clearly inFIG. 2, comprises an annular plate22in which are formed suction holes23selectively connectable to a vacuum source not shown, and a cavity24housing three distance sensors25. Gripping member19has a contact sensor26located along annular plate22and for arresting manipulator14when gripping member19contacts a reel3.

With reference toFIG. 3, each sensor25comprises an emitter27for emitting a beam of electromagnetic waves; and a receiver28for receiving a beam of electromagnetic waves. Emitter27is located at a distance D1from receiver28and emits a beam so oriented that a surface (face9of reel3) facing, parallel to and located a given distance D2from annular plate22reflects the beam in a position in which receiver28is able to pick up the reflected beam. Distance D2is measured parallel to axis A and axis5, and distance D1is measured perpendicular to axis A. Receiver28is defined by a number of adjacent cells29sensitive to electromagnetic waves, so that receiver28is able to receive the reflected beam when the reflecting surface lies within a given range I (parallel to axes5and A) about distance D2. With reference toFIG. 2, gripping member19is equipped with three sensors25, the emitters27and receivers28of which are equally spaced about axis A of cavity24of gripping member19.

With reference toFIG. 1, each pin4a,4bcomprises an expansion spindle30having a tapered free end31, and three sectors32movable between a closed position contacting one another, and an open position in which they are forced against spool6of a reel3to hold reel3in a given position about axis12. As sectors32are opened, axis5of reel3is positioned to coincide with axis12of the unwinding pin. In other words, spindle30is self-centering.

Feed device2is controlled by a control unit33, which processes the signals from sensors25and26and controls the movements of manipulator14, lifting device20and pins4aand4b.

In actual use, and with reference toFIG. 1, a pallet16of reels3is placed on platform15. Pallets16and reels3are of standard size, so that the arrangement of reels3on pallet16varies within relatively small limits. Consequently, reels3on pallet16on platform15are arranged with a certain tolerance about respective given positions memorized in control unit33; and, to pick up a reel3for supply to machine1, manipulator14positions gripping member19over one of reels3whose position and height in a vertical direction D are roughly known. Manipulator14positions gripping member19at or roughly at distance D2from the top lateral face9of reel3, as shown inFIGS. 3 and 4.

Given the approximate positions of reels3, gripping member19can be set to theFIG. 3or4position, i.e. with axis A of gripping member19close to or at hole7in reel3. For the sake of simplicity and to generalize the concept underlying the present invention, gripping member19inFIGS. 3 and 4is equipped with one distance sensor25. When gripping member19is positioned over reel3, annular plate22is maintained horizontal so as to be parallel to lateral face9of reel3. With reference to theFIG. 3case, emitter27emits a beam of electromagnetic waves, which is reflected by lateral face9at a given point K1. Face9lying within range I of distance D2enabling receiver28to receive the reflected beam, the reflected beam strikes one of cells29of receiver28, which transmits a signal to control unit33, which in turn determines the location of reflection point K1on lateral face9of reel3. When reflection point K1is located on face9, gripping member19and reel3are not sufficiently aligned to ensure reel3is positioned correctly on unwinding in4a,4b, so gripping member19is moved about its initial position in directions perpendicular to direction D. At each movement, sensor25determines whether reflection point K1lies on lateral face9or in hole7. When the beam enters hole7, reflection point K1may be located on a support underneath reel3or along an inner face of spool6. Whichever the case, when the beam enters hole7, the reflected beam does not strike receiver28, on account of the reflecting surface not being within range I of distance D2, so that the absence of a receiving signal by receiver28combined with an emission signal by emitter27indicates gripping member19is correctly aligned with reel3, or at least is aligned sufficiently to ensure correct transfer of reel3from gripping member19to unwinding pin4a,4b.

Manipulator14lowers gripping member19towards reel3in direction D until sensor26detects plate22contacting lateral face9; suction holes23are then connected to the vacuum source, and reel3is raised for transfer to pin4b; gripping member19and reel3are positioned over pin4bso that axis A of member19is aligned with axis12of pin4b; gripping member19is lowered onto pin4bin direction D so that pin4bengages hole7, even if axis5of reel3is not perfectly aligned with pin4b, by virtue of the tapered free end31of spindle30; reel3is released by gripping member19; and spindle30is expanded so that axis5of reel3coincides with axis12of unwinding pin4b.

In other words, before a reel3is picked up, a check is made to determine whether reference point K1of gripping member19lies inside hole7of reel3. Obviously, the more reference points there are, the more accurately and faster hole7of reel3is determined.

FIGS. 5,6and7show, schematically, the case in which gripping member19comprises three distance sensors25, as inFIG. 2. InFIG. 5, three separate reflection points K1, K2, K3are located on lateral face9of reel3, which is tantamount to theFIG. 3situation, so that a number of movements about the initial position are required to determine the location of hole7. This may result in the situation shown inFIG. 6, in which two points K1and K2are located on lateral face9, and point K3lies in hole7and is therefore not picked up by receiver28. Control unit33, however, knows the hypothetical position of point K3and commands a movement in the direction of arrow F1, i.e. towards point K3, to also bring points K1and K2inside hole7.

Alternatively, as shown inFIG. 7, one point K1may be located on lateral face9of reel3, and points K2and K3inside hole7. In which case, manipulator14moves gripping member19in a direction perpendicular to the line joining hypothetical points K2and K3and in the direction of arrow F2until point K1also lies inside hole7.

In one variation, control unit33does not know the height of reels3in direction D, but only the approximate arrangement of reels3in the plane perpendicular to direction D, so that, when positioned over a reel3, gripping member19is lowered into contact with reel3; and, upon sensor26indicating contact between gripping member19and reel3, gripping member19is set to or within the range about distance D2so as to effectively determine the position of gripping member19with respect to reel3, as in the previous case.

The method and device according to the present invention are particularly advantageous by only requiring the processing of a relatively small number of data items.

When the position of gripping member19with respect to reel3is determined using only one reference point K1, reel3is centered on unwinding pin4aor4bby expansion spindle30. When the position of gripping member19with respect to reel3is determined using three reference points K1, K2, K3, axis A of gripping member19can be aligned with axis5of reel3by simply selecting three reference points K1, K2, K3located, at distance D2from a reflecting surface, along a hypothetical circumference slightly smaller in diameter than hole7, so that reel3is transferred to pin4aor4bwith no need for centering by a self-centering spindle30. In a further variation not shown, the same result as with three reference points can also be achieved with only two separated, at distance D2from a reflecting surface, by a distance slightly less than the diameter of the reel hole.