EP3882394A1

EP3882394A1 - Cutting machine for cutting sheets of resilient material

Info

Publication number: EP3882394A1
Application number: EP21162689.0A
Authority: EP
Inventors: Roberto TROVI
Original assignee: Quarrata Forniture Srl
Current assignee: Quarrata Forniture Srl
Priority date: 2020-03-18
Filing date: 2021-03-15
Publication date: 2021-09-22
Also published as: IT202000005734A1

Abstract

Described is a machine (1) for cutting sheets of resilient material, comprising a feeding line (L) for feeding sheets of resilient material to be cut along a predetermined longitudinal direction (D1), two cutting units (8, 9) designed to cut lateral portions of the sheets in the predetermined longitudinal direction (D1), an upper bridge structure (6) and a lower connecting structure (7) configured to support slidably the two cutting units (8, 9) in their movements along a transversal direction (D2).

Description

The present invention relates to a machine for cutting sheets of resilient material.
More specifically, the invention relates to a machine for cutting sheets of resilient material designed for assembling mattresses.
The assembly of mattresses is known using sheets of resilient material, such as polyurethane, natural or synthetic latex and foam materials, currently also universally known as "memory foam".
Starting from the raw sheets supplied by the producer, the manufacturer of mattresses must perform a cutting of the sheets, so as to adapt them to the specific size of the mattress to be produced.
For example, if a manufacturer offers a mattress with a length of 190 cm, the respective width may normally comprise single mattresses with widths of 80 cm and 90 cm, double mattresses with widths of 140 cm and 160 cm and king size mattresses with a width of 180 cm.
Obviously, the machines used for longitudinal cutting of the sheets must be able to guarantee the possibility of adapting to the cutting of different widths of the sheet.
Moreover, since the sheet which forms the mattress often derives from the superposing of many sheets of different materials or shapes, it is necessary to trim them to eliminate the inevitable errors in superposing the individual sheets.
In fact, the circumstances relating to the cutting of the sheets are different: a first occurs with the cutting of the expanded polyurethane sheets, with regard to the dimensions required, for making mattresses. The machines which cut polyurethane into the three dimensions and into the various types which will contribute to making a specific model are in practice positioned outside the mattress production line and feed the sheets which have already been finished.
There are also machines which are inside the mattress production line, specifically in the line for gluing and superposing the sheets which will constitute the "core" of the mattress.
The difference is considerable and significant.
The first are the so-called cutting machines, which prepare the material to be used in the production cycle.
The second machines, on the other hand, are machines which substantially have the purpose, as mentioned, of laterally trimming the mattress with the aim of not so much adjusting the dimensions but, above all, trimming the edges to make them straight and clean.
The superposing of the sheets inevitably causes imprecise alignments also because the various materials to be superposed have different consistencies, with the original cuts which may be relatively imprecise and the sheets themselves which, during the positioning, can extend (because they are elastic), thus modifying their original size.
The prior art longitudinal cutting machines without doubt adapt to the different widths required by means of mobile cutting units but are not, however, free from drawbacks.
The main drawback is the overall longitudinal size of the movable cutting units, which consequently requires a transversal corridor to be created which is very large between the successive conveyor belts which feed the sheets.
The width of the corridor may cause a lowering of the sheet (which bends downwards inside the corridor) precisely during the cutting step, thus compromising the precision of the cut.
A further drawback of the prior art machines is due to their structural complexity, which also results in high production costs and the fact that they are not easy to use.
The aim of the invention is to provide a machine for cutting sheets of resilient material which is able to overcome the drawbacks of the prior art and which is at the same time simple and inexpensive to make.
A further aim of the invention is to provide a machine for cutting sheets of resilient material which is compact and practical to use.
According to the invention, these aims and others are achieved by a machine for cutting sheets of resilient material comprising the technical features described in the appended claims.
The technical features of the invention, according to the above-mentioned aims, are clearly described in the appended claims and its advantages are apparent from the detailed description which follows, with reference to the accompanying drawings which illustrate a nonlimiting example embodiment of it, and in which:

Figure 1 is a schematic perspective view from above of a preferred embodiment of the cutting machine according to the invention;
Figure 2 is a schematic perspective view from above, with some parts cut away to better illustrate others, of the machine of Figure 1;
Figure 3 is an enlarged view of the detail of the box III of Figure 2;
Figures 4 and 5 are respective schematic perspective views from different angles of a detail of the machine of the preceding drawings;
Figure 6 is a schematic front elevation view of the detail of Figures 4 and 5;
Figure 7 is a schematic side elevation view of the detail of Figures 4 and 5.

As illustrated in Figure 1, the reference numeral 1 denotes in its entirety a machine for cutting sheets, not illustrated, of resilient material, made according to the invention.
The cutting machine 1 comprises a first conveyor belt 2 to which are fed, along a predetermined longitudinal direction D1, in the direction indicated by the arrow F1, sheets - not illustrated - made of material which is resilient to cutting.
The concept of the sheet made of resilient material means, for the purposes of this description, a sheet made of natural or synthetic material, more or less porous, designed to be used in the construction of mattresses and the like.
The above-mentioned sheet, if necessary, consists of several superposed layers, also made of different materials but always compatible with the use in a mattress.
The first conveyor belt 2 feeds, in a know manner, the above-mentioned sheet, not illustrated, to be cut in the direction indicated by the arrow F1.
The cutting machine 1 comprises a second conveyor belt 3 positioned adjacent to the first conveyor belt 2 and designed to receive from it the above-mentioned sheet of resilient material for feeding it in turn in the direction indicated by the arrow F1.
The first and second conveyor belts 2, 3 define, for the cutting machine 1, a feeding line L for feeding the above-mentioned and not illustrated sheets of resilient material along the predetermined longitudinal direction D1.
The two belts 2, 3 have a width at least equal to the maximum cutting width which the user wants to obtain in the machine according to the invention.
In fact, in order to perform a precise cut the entire surface of the sheets must be supported by the belts 2, 3.
Otherwise there would be bending, due to the resilience of the material, which would cause imprecisions in the cutting operations.
As illustrated in Figure 2, in which the two first and second conveyor belts 2, 3 have been removed, the cutting machine 1 comprises a frame 4 and a plurality of containment walls 5.
The containment walls 5 are positioned in such a way as to form, basically, two opposite lateral portions PL, PR of the machine 1: one, PL, on the left and the other, PR, on the right of an observer looking at the cutting machine 1 in the direction of the arrow F1 of Figure 1.
Again with reference to Figure 2, the cutting machine 1 comprises an upper bridge structure 6 extending in a direction D2 transversal to the above-mentioned predetermined feed direction D1 of the sheets of resilient material.
Again considering Figure 2, the cutting machine 1 comprises a lower structure 7 for connecting between its two above-mentioned portions PL, PR on the left and right.
The upper bridge structure 6 also connects the two left and right portions PL, PR of the cutting machine 1.
The two upper bridge 6 and lower connecting 7 structures are parallel to each other, one substantially superposed on the other, with the two first and second conveyor belts 2, 3 defining a sliding plane P interposed between them.
As illustrated in Figure 1, the sliding plane P is defined by the upper, substantially coplanar, surface of the two first and second conveyor belts 2, 3.
With reference to Figure 1, between the first and second conveyor belts 2, 3 there is a space defining a transversal gap G in the feeding line L, the gap G extending parallel to the above-mentioned transversal direction D2.
Advantageously, the above-mentioned transversal gap G extends, along the predetermined longitudinal direction D1, for a distance of less than 60 millimetres.
The cutting machine 1 comprises two cutting units 8, 9, positioned on both sides of the above-mentioned and not illustrated sheet of resilient material which feeds along the direction D1, as indicated by the arrow F1.
The two cutting units are substantially the same, that is to say, mirrored relative to a vertical plane of symmetry, parallel to the predetermined direction D1 and passing through a central zone of the two structures 6, 7.
The two cutting units 8, 9 are free to move independently of each other.
For this reason, only one, the left-hand one, 8, of the two cutting units 8, 9, is described below in more detail, and moreover more clearly shown in Figures 1 and 2.
With reference to Figures 2 and 3, the cutting unit 9 comprises a C-shaped frame 10 having an upright 11 and two arms 12, 13 respectively lower and upper.
The two lower and upper arms 12, 13 are parallel to each other and project in cantilever fashion from respective longitudinal ends of the upright 11.
The lower and upper arms 12, 13 rotatably support two pulleys 14, 15, respectively lower and upper, around which pulleys 14, 15 are looped a bandsaw blade 16 designed to cut the resilient material of the above-mentioned and not illustrated sheets.
The bandsaw blade 16 looped around the pulleys 14, 15 has a cutting side 14a, distal from the upright 11, and a return side 14b, proximal to the upright 11.
Pairs of guide wheels 17 are positioned close to the bandsaw blade 16 inlet and outlet towards and from each pulley 14, 15.
A control wheel 18 is coaxially fixed to the lower pulley 15 and engaged by a belt 19 for transmitting the rotational motion.
The transmission belt 19 is moved by a respective pinion, not visible in the drawing, keyed on the shaft of an electric motor 20.
The electric motor 20 is stably fixed at the above-mentioned lower end of the upright 11.
According to alternative embodiments, not illustrated, of the cutting machine 1, the drive is operated on the upper pulley 15, thereby placing the electric motor 20, the belt 19 and the control wheel 18 above it.
A belt tightening device 21 is located between the control wheel 18 and the above-mentioned and not illustrated pinion, for keeping the transmission belt 19 in the optimum tension state.
The two cutting units 8, 9 slidably engage with the two upper bridge 6 and lower connecting 7 structures to move along the transversal direction D2 in order to vary the width of the sheet of resilient material.
The two cutting units 8, 9 move independently of each other.
As illustrated by way of example in Figures 3 and 4, the cutting units 8, 9 comprise guide elements 22 designed to slidably engage on respective linear cylindrical rails 23.
As clearly illustrated in Figure 4, in order to achieve a correct translation of the cutting unit 8, 9, they comprises two guide elements 22 positioned on the upper arm 13 and suitably spaced from each other and two guide elements 22 positioned on the lower arm 12 and also suitably spaced from each other.
The accompanying drawings show the linear cylindrical rails 23 supported by the lower connecting structure 7, whilst the cylindrical rails housed in and supported by the upper bridge structure 6 are not visible.
With reference to Figure 2, the cylindrical rails 23 extend from the frame 4 of the cutting machine 1 and reach a central zone of the lower connecting structure 7, fixed to a trestle 24 integral with it.
As illustrated in Figure 2 and in detail in Figure 3 with reference to the cutting unit 8, the cutting machine 1 comprises, for each cutting unit 8, 9, a respective lead nut and screw coupling 25.
More in detail, with reference to the cutting unit 8 shown in Figure 3, the lead nut and screw coupling 25 comprises a threaded bar 26 supported rotatably at the relative longitudinal ends 26a, 26b respectively by the frame 4 and by the trestle 24, and a lead nut 27 integral with the cutting unit 8.
Advantageously, the lead nut 27 is connected to the cutting unit 8 at its upright 11 by interposing an L-shaped bracket 28.
The above-mentioned guide elements 22, linear cylindrical rails 23, lead nut and screw couplings 25 define in their entirety, for the cutting machine 1, respective means 29 for moving the cutting units 8, 9.
In use, as mentioned, sheets of resilient material are fed along the feeding line L, on the first and second conveyor belts 2, 3.
When a sheet, not illustrated, arrives at the transversal gap G existing between the first and the second conveyor belts 2, 3, the sheet engages, with relative opposite lateral zones, with the respective bandsaw blades 16 of the two cutting units 8, 9.
More specifically, the cutting sides 16a of each bandsaw blade 16 engage with the sheet.
A central portion of sheet with the desired width (measured along the transversal direction D2) will then be fed on the second conveyor belt 3 and two lateral strips constituting the waste material generated by the cutting operation.
The measurement of the actual width of the sheet made of cut resilient material is adjusted by the relative positioning of the two cutting units 8, 9 in the transversal direction D2.
In other words, the final width, in the transversal direction D2, of the sheet passing through the cutting machine 1, is determined by the actual distance between the cutting sides 16a of the bandsaw blades 16 of the two cutting units 8, 9.
I order to modify the distance from each other and, therefore, the final width of the sheet, the movement means 19 are used, by which the two cutting units 8, 9 can be moved along the transversal direction D2.
In the preferred embodiment illustrated, the right-hand cutting unit 8 is advantageously movable along the transversal direction D2 manually, that is to say, manually rotating the respective threaded bar 26.
This manual actuation is advantageously used for adjustment movements, in such a way that the cutting unit 8 substantially maintains its position even with variations in the width of the sheets to be cut.
In fact, again in the preferred embodiment illustrated, the left-hand cutting unit 9 is, on the other hand, advantageously movable along the transversal direction D2 automatically, that is to say, by rotating the respective threaded bar 26 using a suitable electric gear motor 30.
This automatic actuation is advantageously used for movements adapting to the different widths required for the sheets to be cut.
Advantageously, a computerised command and control unit, not illustrated, controls the movement of the left-hand unit 9.
Advantageously, the transversal gap G extends, as mentioned, for a distance of less than 60 millimetres along the longitudinal direction D1.
Still more advantageously, the gap G extends for a distance of less than 50 millimetres along the longitudinal direction D1.
The two cutting units 8, 9 are configured to move inside the space defined by the transversal gap G between the two first and second conveyor belts 2, 3.
For this purpose, that is to say, for passing inside the transversal gap G, the cutting units 8, 9 are suitably configured.
As clearly shown in Figure 6, the overall dimensions of the cutting unit 8 (and also of the unit 9 equivalent to it) in its central zone is particularly limited, providing a thickness of the upright 11 which is well less than 50 mm.
Even more reduced is the width of the bandsaw blade 16 which does not protrude relative to the dimensions of the upright.
In the preferred embodiment illustrated in the accompanying drawings, the thickness of the upright 11, that is to say, its dimensions along the longitudinal direction D1, is approximately 20 mm.
The machine 1 for cutting sheets of resilient material according to the invention overcomes the above-mentioned drawbacks and brings important advantages.
A first advantage linked to the invention is due to the fact that it allows the production of very small transversal gaps G, that is to say, in the order of a few centimetres, thereby limiting and in fact eliminating the depression of the sheet of resilient material at the cutting zone, which is a decisive aspect for obtaining a straight and uniform cut.
Another advantage linked to the cutting machine according to the invention is due to the reduced and compact dimensions of the cutting units which can therefore be moved easily to adapt the machine to the cutting of sheets of different sizes.
Yet another advantage of the cutting machine according to the invention is due to the extreme compactness and stability of the system for moving the cutting units which is substantially integrated with the frame of the machine and therefore extremely rigid so as to guarantee precise movements and predetermined and stable positions.

Claims

A cutting machine for cutting sheets of resilient material, comprising:
- a feeding line (L) to feed said sheets of resilient material to be cut along a predetermined longitudinal direction (D1); said line (L) comprising a first (2) and a second (3) conveyor belt positioned adjacent to and configured for feeding said sheets along said longitudinal direction (D1), said line (L) also comprising a transversal gap (G) extending parallel to a transversal direction (D2), said gap (G) being interposed between said first (2) and said second (3) belt;

- two cutting units (8, 9) designed to cut lateral portions of said sheets along said predetermined longitudinal direction (D1) whilst said sheets feed from said first (2) to said second (3) belt along said longitudinal direction (D1),

- an upper bridge structure (6) and a lower connecting structure (7) configured to support slidably said two cutting units (8, 9) in their movements along said direction (D2) transversal with respect to said predetermined longitudinal direction (D1); during their said movements along said transversal direction (D2) the cutting units (8, 9) moving through said transversal gap (G).
The machine according to claim 1, characterised in that it comprises means (29) for moving said cutting units (8, 9), said movement means (29) being supported by said upper bridge structure (6) and by said lower connecting structure (7).
The machine according to claim 2, characterised in that said movement means (29) comprise linear cylindrical rails (23) supported by said upper connecting bridge structure (6) and lower connecting structure (7), and guide elements (22) positioned on said cutting units (8, 9), with guide elements (22) configured to slidably engage on said linear cylindrical rails (23).
The machine according to claim 2 or 3, characterised in that said movement means (29) comprise for each cutting unit (8, 9) a threaded bar (26) rotatably supported at its longitudinal ends (26a, 26b) and a lead nut (27) integral with the cutting unit (8, 9), said threaded and female bar (26) and lead nut (27) defining a screw-nut coupling (25).
The machine according to claim 1, characterised in that said transversal gap (G) extends, along said predetermined longitudinal direction (D1), for a distance of less than 60 millimetres.
The machine according to claim 1, wherein each of said cutting units (8, 9) comprises a bandsaw blade (16) wound in a ring around respective pulleys (14, 15), characterised in that each of said cutting units (8, 9) comprises an upright (11), and two lower and upper arms (12, 13) supporting said pulleys (14, 15), said upright (11) being configured to at pass at least partly through said transversal gap (G).
The machine according to claim 6, characterised in that said upright (11) has an overall dimension along said predetermined longitudinal direction (D1), at said transversal gap (G), of less than 50 millimetres.
The machine according to claim 6 or 7, wherein each cutting unit (8, 9) comprises a respective electric motor (20) to drive said bandsaw blade (16), characterised in that said electric motor (20) is supported by one of said lower and upper arms (12, 13) .
The machine according to claim 8, wherein said electric motor (20) is positioned spaced above or below said first (2) and second (3) conveyor belt in such a way as not to interfere with said conveyor belts (2, 3) during the movement of said cutting units (8, 9) through said transversal gap (G).
The machine according to claim 1, wherein said two cutting units (8, 9) are movable independently of each other.