Machine for packaging mattresses in a sheet unwound continuously from a roll

Abstract: A machine for packaging a mattress in a sheet, comprising horizontal supporting and receiving mattress surfaces, guides (3,18,19) for guiding the sheet (4) on a vertical plane, so that by moving the mattress in the advancement direction (7) from the supporting surface (1) toward the receiving surface (5) the sheet is arranged over and under the mattress, a device for joining and cutting the sheet upstream of the mattress and for forming a bag which wraps around the mattress, sheet unwinding assemblies (27,28) comprising two rollers (42,42a) movable along the receiving surface with a return stroke, the rollers (42,42a) being articulated to rotate between alignment and parallel positions in which they are perpendicular or parallel to the advancement direction (F) and to the sides of the mattress, and actuators (45,45a) for actuating the rollers (42,42a).

Description: The present invention relates to a machine for packaging mattresses in a sheet unwound continuously from a roll. Mattress packaging machines are already known. A first type of these machines, shown in Figures 1, 2 and 3, comprises a frame provided with a horizontal surface 1 for supporting the mattress 2, at the end of which there is a tensioning roller 3 for guiding, at right angles to the surface 1, a packaging sheet 4 (usually made of plastics) unwound from a roll 4a. As the mattress 2 advances in the direction F, from the supporting surface 1 onto the package receiving surface 5, the sheet 4 (as shown in Figure 2) is folded and stretched over and under the mattress 2, so as to form a bag which is then closed at the rear (see Figure 3) and on both sides by heat-sealing. Packaging defects often occur in these conventional packaging machines being due to the fact that the sheet unwound from the roll slides on the front edge of the mattress and therefore tends to form unsightly longitudinal creases and wrinkles owing to the unevenness and flexible consistency of the front edge. In order to avoid these drawbacks, it has been proposed (Figures 4, 5 and 6) to push the mattress 2 against the sheet 4 by using a pusher 6 having an arm 7 which lies above the mattress, reaches beyond the front edge of said mattress and supports a roller 8 being parallel to the front edge of the mattress. The roller 8 acts as a redirection element for the packaging sheet 4, preventing its contact with the front edge of the mattress and thus preventing the formation of creases. The refinement of the roller supporting arm 7 in these packaging machines, however, entails a longer production cycle, since the arm 7 has to be fully returned above the supporting surface in order to clear the receiving surface for the descent of the heat-sealing bars that have to provide the heat-seal that closes the bag perimetrically. A packaging machine with the features of the preamble of claim 1 is known from the document DE 44 16 540 C. The aim of the present invention is to provide a packaging machine which allows to avoid the formation of creases of the package without compromising the operating times. This aim is achieved with a packaging machine whose characteristics are defined in the appended claims. Further characteristics and advantages of the present invention will become better apparent from the following detailed description of a preferred embodiment thereof illustrated only by way of non-limitative example in the accompanying drawings, wherein: Figures 1-6 show known type of mattress packaging machines; Figure 7 is a perspective view of the apparatus; Figure 8 is a sectional elevation view, taken along a longitudinal central plane; Figures 9 and 10 are views of two details enclosed in the circles A and B of Figure 7; Figure 11 is a view of the detail Figure 9, taken from another viewpoint; Figure 12 is a perspective view of an element of the machine; Figures 13, 14 and 15 are views of three successive operating conditions of the machine; and finally Figure 16 is a view of the machine, taken in the direction XVI-XVI of Figure 8. With reference to Figures 7 and 8, the mattress packaging machine is generally designated by the reference numeral 9 and comprises a frame composed of vertical posts 10 which are mutually connected by longitudinal members and cross-members. In particular, the posts 10 are connected at the top by longitudinal members 11 which support two rails 12 for the sliding of a carriage 13 which is motorized so that it can move in both directions X and Y and on which the roll 4a that supplies the packaging sheet 4 is supported. The frame comprises a supporting surface 1 with shoulders 14 for containing and guiding a mattress 2 and a receiving surface 5 being constituted by a plurality of belts 15. An opening 16 (Figure 8) remains between the exit portion of the supporting surface 1 and the receiving surface 5, and the packaging sheet 4 is guided downward from above, through said opening, in the direction Z at right angles to the surfaces 1 and 5. The mattress 2 to be packaged, by means of a pusher 6 (see Figure 13) or the like, is pushed in the direction F against the sheet 4, which is stretched over and under the mattress 2 (see Figure 14) by means of a pair of guiding rollers 18 and 19 and of a device 20 described hereinafter. When the mattress 2, after moving beyond the opening 16, reaches the receiving surface 5, the upper and lower flaps of the sheet 4, which lie upstream of the mattress, are joined by a heat-sealing assembly 21 composed of two heat-sealing bars 22 and 23 which provide two parallel heat-seals being spaced enough to allow a blade 24 which is intermediate thereto to cut and separate the sheet 4. In this manner, the heat-sealing line downstream of the cut closes the sheet 4, forming a loop which wraps around the mattress 2, while the heat-sealing line upstream of the cut allows the sheet 4 to remain attached to the takeup roller 3 located below the surface 1, in order to allow to take up a portion which is long enough to prevent the heat-sealing line from remaining in the portion of sheet used to package the next mattress. Once the mattress 2, with the sheet 4 wrapped in a loop around it, has advanced onto the conveyor 15, two lateral heat-sealing units 25 (Figures 13-15), actuated in the direction D, close it laterally so as to form a hermetic bag. The machine shown in Figures 1 and 2 is equipped with an apparatus for automatically changing the roll 4a from which the sheet is taken either because it is about to end or because it is necessary to change the type of sheet used to package the mattresses. Said apparatus (generally designated by the reference numeral 17) is not described hereinafter for the sake of brevity in description and because it is beyond the scope of the present invention. However, it is disclosed in EP 1 094 007 A of October 4, 2000 by the same Applicant and reference is made thereto as an integral part of the present description. The device 20 that completes the arrangement of the sheet 4 over and under the mattress 2 is composed of two unwinding assemblies 27 and 28 which are adapted to engage the sheet 4 and gradually pull it in the direction F in front of the mattress, as said mattress is moved forward, by means of the pusher 6, from the surface 1 onto the surface 5. The assembly 27 (visible as a whole in Figure 12) is composed (see particularly Figures 9-11) of a pair of pulleys 29 and 30 which cantilever out above the surface 5 from respective flanges 31, 32 on which they are rotatably supported. A belt 33 is closed in a loop on the pulleys 29, 30 and its upper and lower portions are horizontal. The flanges 31, 32 are rigidly coupled to a side wall 34 which lies to one side of the conveyor 15 and is supported so as to be rigidly coupled to the posts 10, so that it can be moved parallel to itself, as will become better apparent from the description of Figure 16 that follows. A guide 35 is fixed to the inner face of the side wall 34 and is parallel to the upper portion of the belt 33. A slider 37 is coupled to the upper portion of the belt 33 by means of a clamp 36 (see Figure 9), and a bracket 38 protrudes from said slider toward the surface 1 and is flat and parallel with respect to the side wall 34. Two mutually superimposed lugs 39 (see Figure 11) are fixed to the end of the bracket 38, and a stem 40 is supported in said lugs so that it can rotate about a vertical axis; a bar 41 protrudes at right angles from said stem 40. A roller 42 can rotate on the bar 41 and protrudes toward the centerline of the pivot 5. The roller 42 lies at a level, with respect to the surface 5, such that its rotation plane about the vertical axis is higher than the height of the mattress to be packaged, so that it cannot interfere with said mattress by rotating. A tab 43 is rigidly coupled to the bar 41, proximate to the stem 40, and the stem 44 of a fluid-actuated jack 45 is articulately coupled in said tab 43; the cylinder 45a of said jack is articulated to an L-shaped element 46 being fixed to the bracket 38. The actuation of the jack 45 actuates the oscillation, on a horizontal plane, of the roller 42 between a position which is perpendicular to the bracket 38 and a position in which the roller 42 is arranged itself as an extension of the bracket 38. Of the two pulleys 29 and 30, the pulley 29 is the driven one and the pulley 30 is the driving one. In order to actuate the pulley 30 there is a motor 47 which is mounted outside the flange 32. The motor 47 is of the reversible type, so that the slider 37, and therefore the roller 42, is given a back-and-forth movement along the guide 35. This movement of the roller 42 in the mattress advancement direction F is synchronized with the movement of the pusher 6. The other sheet transport assembly 28 is mirror-symmetrically similar to the above-described assembly 27 and is shown in perspective in Figure 12, where its parts are designated by the same reference numerals with the addition of the letter "a". The operation of the described machine is as follows. Assume an initial condition of Figure 13, in which the sliders 37 and 37a of the two unwinding assemblies 27 and 28 are arranged proximate to the heat-sealing assembly 21 with the rollers 42, 42a mutually aligned, i.e., at right angles to the direction F in which the mattress 2 advances and upstream of the sheet 4, which is stretched at right angles downstream of them between the roll 4a and the tensioning roller 3. In this situation, when the front end of the mattress 2 is about to strike the sheet 4, the sliders 37, 37a are actuated in the direction F, so that the rollers 42, 42a stretch the sheet 4 in front of the mattress. As the rollers 42, 42a advance, the sheet 4, unwound from the roll 4a and guided by the roller 18, is stretched under the mattress. Once the rear end of the mattress 2 has passed beyond the heat-sealing assembly 21 and therefore the mattress 2 is resting fully on the receiving surface 5, the jacks 45, 45a are activated and, by turning the rollers 42, 42a from the mutual alignment position to the parallel position, determine their disengagement from the sheet 4. Once the rollers 42, 42a are arranged parallel to the direction F at the sides of the mattress, the pusher 6 is retracted and the flaps of the sheet 4 that lie to the rear of the mattress are heat-sealed by means of the heat-sealing bars 22 and 23 and the lateral flaps are heat-sealed by means of the heat-sealing bars 25, so as to provide perimetric closure of the package. After removing the mattress 2 from the surface 5, the sliders 37, 37a are returned to the initial position proximate to the heat-sealing assembly 21; once said assembly has been reached, the jacks 45, 45a are activated so as to turn the rollers 42, 42a into the alignment position behind the sheet 4. The cycle can thus be repeated in the above-described manner. The fundamental feature of the present invention is that the rollers 42, 42a are made to advance in front of the front end of the mattress, so as to prevent the onset of undue traction stresses on the sheet 4, which in conventional machines are caused by the friction with which the sheet adheres to the mattress. The coaxial arrangement of the rollers 42, 42a in the alignment position further defines a cylindrical surface which keeps the sheet 4 perfectly stretched transversely and prevents creasing. It is evident that the device 20 fully achieves the intended aim and objects. In particular, it should be noted that the heat-sealing and cutting of the sheet 4 to the rear of the mattress 2 can occur directly after the rollers 42, 42a have been turned on a horizontal plane to the side of the mattress, i.e., as soon as they are in a position in which they are disengaged from the sheet. After the disengagement of the rollers 42, 42a, the mattress 2 can advance in order to allow the lateral heat-sealing units 25, 25a to provide the lateral heat-seals which, by intersecting the rear heat-seal, allow to close the package hermetically. It should be noted that the execution of the lateral heat-seals does not hinder the return of the rollers 42, 42a into the engagement position upstream of the sheet 4. Another particularity of the described machine is that the unwinding assemblies 27, 28 and the lateral heat-sealing units 25, 25a can be moved at right angles to the direction F in order to be adapted to the lateral dimensions of the mattress. For this purpose (see Figures 7, 16), on one side of the receiving surface 5 there is a pair of C-shaped shoulders 48, 49. Likewise, on the other side of the mattress there is a second pair of shoulders 48a, 49a being mirror-symmetrical with respect to the shoulders 48 and 49 in terms of shape and arrangement. The lower arms 50, 50a of the shoulders 48, 48a and 49, 49a have rollers 51, 51a which slide on two rails 52, 53 which lie transversely to the direction F and are rigidly coupled to respective longitudinal beams 54, 55 being fixed on cross-members 56, 57 which connect the posts 10 one another. Accordingly, the shoulders 48, 49 and 48a, 49a constitute two carriages which can slide on the rails 52, 53. Two female threads 58, 58a are fixed under the lower arms 50, 50a of the two mutually opposite shoulders 49, 49a, and two rods 59, 60 with mutually opposite threads are engaged in said female threads by screw coupling and are actuated by a gearmotor 61 which is mounted under the rail 53. The gearmotor 61 also actuates, by means of an appropriate transmission which is not shown but entirely conventional, the two shoulders 48, 48a, so that the shoulders 48, 49 move in opposition to the shoulders 48a, 49a. The side walls 34, 34a of the two unwinding assemblies 27 and 28 are rigidly coupled to the shoulders 48, 49 and 48a, 49a and accordingly follow the transverse mutual approach and spacing movements of the shoulders actuated by the gearmotor 61. The shoulders 48, 49, 48a, 49a have, at their top, two upper arms 62, 62a which support respective vertical jacks 63, 63a, to the stems of which the heat-sealing bars 25, 25a are fixed. The heat-sealing bars 25, 25a cooperate with abutment bars 64, 64a which are mounted on the lower arms 50, 50a at the level of the receiving surface 5. From the above description it is evident that by actuating the gearmotor 61 it is possible to arrange the heat-sealing bars 25, 25a and the corresponding abutment bars 64, 64a at the distance that allows heat-sealing of the lateral flaps of the sheet 4, after the rollers 42, 42a have been turned into the position in which they are parallel to the sides of the mattress. In this position, the rollers 42, 42a are in any case outside the descent planes of the heat-sealing bars, so that they can perform their return stroke toward the sheet during the provision of the lateral heat-seals. The disclosures in Italian Patent Application No. BO2000A000134 from which this application claims priority are incorporated herein by reference. Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the scope of each element identified by way of example by such reference signs.

Claims: A machine for packaging a mattress (2) in a sheet (4) which is unwound continuously from a feeder roll (4a), comprising a horizontal supporting surface (1) for said mattress and a horizontal receiving surface (5), means (3, 18, 19) for guiding said sheet in a substantially vertical direction (Z) which passes between said supporting surface (1) and said receiving surface (5), so that by moving said mattress in the advancement direction (F) from said supporting surface toward said receiving surface said sheet (4) is arranged over and under said mattress, means (21-25) for joining and cutting said sheet upstream of said mattress and for forming a bag which wraps around said mattress in a loop, characterized in that it comprises assemblies (27, 28) for unwinding said sheet from said roll (4a) which comprise two rollers (42, 42a) which can move along said receiving surface (5) and are actuated with an outgoing stroke in said advancement direction and with a return stroke, said rollers (42, 42a) being articulated about vertical axes to rotate between an alignment position which is perpendicular to the advancement direction (F) and a position in which they are parallel to said direction and to the sides of said mattress, means (45, 45a) being provided for actuating said rollers (42, 42a) so that they are arranged in said alignment position upstream of said sheet (4) when said mattress (2) is still arranged on the supporting surface (1) and so that they maintain said position during said outgoing stroke and the transfer of the mattress from the supporting surface (1) onto the receiving surface (5), in order to allow said rollers (42, 42a) to engage said sheet (4) and stretch it over and under the mattress (2), and so that they return to said parallel position after the mattress has been transferred onto said receiving surface (5) in order to allow said rollers (42, 42a) to disengage from said sheet (4) and return to said position for engaging said sheet. The machine according to claim 1, characterized in that said unwinding assemblies (27, 28) comprise two guides (35, 35a) which are arranged to the sides of said receiving surface (5) and are parallel to said advancement direction (F), a slider (37, 37a) being able to slide on each guide, a respective horizontal roller (42, 42a) being articulated on a vertical axis to said slider, a jack (45, 45a) for the actuation of said roller between said alignment and parallel positions being supported on said slider. The machine according to claim 2, characterized in that each slider (37, 37a) is fixed to a horizontal portion of a belt (33) which is closed in a loop on a driving pulley (30) and a driven pulley (29), said driving pulley (30) being actuated by a reversible motor (47) in order to make said slider perform said outgoing and return strokes. The machine according to one of claims 1 to 3, characterized in that said rollers (42, 42a) can rotate about their respective vertical axes on horizontal planes which lie above the upper face of the mattresses. The machine according to one of the preceding claims, characterized in that it is associated with a device for automatic roll changing (17). The machine according to one of the preceding claims, characterized in that it comprises elements (25) for the lateral heat-sealing of said bag, and in that said unwinding assemblies (27, 28) and said elements for the lateral heat-sealing of said bag can be adjusted transversely to the advancement direction (F) of the mattress. The machine according to claim 6, characterized in that said unwinding assemblies (27, 28) and said elements (25) for the lateral heat-sealing of said bag are mounted on carriages (48, 49 and 48a, 49a) which can slide on rails (52, 53) arranged transversely to said advancement direction (F), means (58, 61) being provided for adjusting the position of said unwinding assemblies and of said lateral heat-sealing elements on said rails.

Inventors: RESTA ROBERTO, RESTA, ROBERTO
Applicants: RESTA SRL, RESTA S.R.L.
Application year: 2001
Main classification: B65B11
IPC codes: B65B11