The present invention relates to equipment for cutting

sheet material, for example paper or plastics material,

comprising a plurality of pairs of blade units and

counter-blade units slidable and fixable on respective

elongate support members.

Cutting equipment of the type indicated above is used,

for example, in winding-cutting machines, that is machines which can unwind a roll of the sheet material,

for example paper or plastics film, cut it into several

sections perpendicular to its axis and rewind the cut

sections to form rolls of shorter axial extent than that

of the starting roll.

The object of the present invention is to provide

automatic cutting equipment in which it is possible to

adjust the axial extent of the various sections cut from

the starting sheet material rapidly and in a desired

manner.

This object is achieved by equipment of the type

indicated above characterised in that it includes:

a first positioning carriage which can move

parallel to the elongate supporting member of the

counter-blade units and which has means for selectively

engaging the counter-blade units and means for locking

the units selectively relative to the elongate support

member, a second positioning carriage which can move

parallel to the elongate support member of the blade

units and which has means for selectively engaging the

blade units and means for locking the units selectively

relative to the elongate support member,

- drive means which can drive the first and second

carriages to move uniformly and in synchronism with each

other,

- means for detecting the axial position of at least

one of the carriages, and

- a control unit for controlling the drive means,

the selective engagement means and the selective locking

means .

In the equipment of the invention, the positioning of the

various blade and counter-blade units is achieved by the

two carriages which, at any particular time, locate them

at the desired positions along the respective elongate

support members by means of a series of operations of

unlocking, longitudinal movement and locking. These

operations are controlled by the control unit which has

previously been programmed appropriately and which

continuously receives signals output by the detector

means in order to effect any adjustments necessary to

ensure that the actual positions of the blade and counter-blade units conform with the desired positioning.

Thus, once the various blade and counter-blade units have

been positioned and the cutting operation is started, it

is possible for the starting sheet material to be cut

into strips of the desired widths.

The equipment of the invention also has the advantage

that it does not require the removal of the roll of sheet

material, which must subsequently be cut, from the

associated winding-cutting machine during the period in

which the positions of the blades and counter-blades are

adjusted.

Further advantages and characteristics of the present

invention will become apparent from the detailed

description which follows, given with reference to the

appended drawings, provided purely by way of non-

limitative example, in which:

Figure 1 is a schematic view of cutting equipment

according to the invention,

Figure 2 is a front elevational view illustrating

the first carriage and a counter-blade unit of the

equipment of Figure 1, and

Figure 3 is a front elevational view illustrating

the second carriage and a blade unit of the equipment of

Figure 1.

Equipment for cutting sheet material, for example of

paper or plastics material, comprises (Figure 1) a

plurality of pairs comprising a blade unit 10 and a

counter-blade unit 12 slidable and fixable on respective

elongate support members 14 and a first positioning

carriage 16 and a second positioning carriage 18 for

positioning the counter-blade units 12 and the blade

units 10 respectively. For reasons of clarity, in Figure

1, the units 10 and 12 are illustrated spaced from their

respective elongate support members 14.

Each counter-blade unit 12 includes (Figure 2) a support

frame 20 and a counter-blade proper 22. Each frame has

splined shoes 24 for facilitating its sliding along

raised ribs 26 fixed to the respective elongate support

member 14. Each frame 20 also carries a respective lever

30 pivoted at one end 28 thereon and from which projects

transversely a brake element 32 which can bear against

the elongate support member 14.

The brake element 32 comprises a shaft 34 fixed at one

end to the lever 30 and having a head 36 at its opposite

end which has a surface 38 which can come into frictional

contact with the elongate support member 14.

The lever 30 also has a threaded through-hole 40 which

can receive a screw 42, the distal end 44 whereof,

opposite the actuating head 46, can bear against the

frame 20.

The first positioning carriage 16 includes a support

structure 48 which has splined shoes 50 which enable it

to slide along raised ribs 52 fixed to the respective

elongate support member 14, a first actuator 54 and a

second actuator 56, preferably of pneumatic type, being

mounted on the first carriage.

The first actuator 54 includes a piston, the distal end

58 vhensof nas a 3 ^~ ιεp - for exaiple sσrlcircuiar ≤rd ccrcave in Dian view - such

as to enable it, in its extended position, to engage a

pin 60 projecting from the frame 20 of a counter-blade

unit 12. As will become clear from the description of

operation below, it is thus possible to engage the

carriage 16 selectively with the counter-blade unit 12.

The second actuator 56 includes a piston, the distal end

62 whereof, in its extended position, is arranged to

contact the end 64 of the lever 30 opposite the pivoted

end 28 so as to cause the unit 12 to be unlocked from the

elongate support member 14, as will be described fully

below.

The first carriage 16 also carries (Figure 1) a position

detector sensor 66 adapted to cooperate with a magnetic

ruler 68 parallel to the elongate support members 14.

The structure of the second carriage 18 and of the blade

units 10, illustrated in Figure 3, is substantially the

same as that of the first carriage 16 and of the counter-

blade units 12. The same reference numbers have

therefore been assigned to parts equivalent to or the

same as those described previously.

As may be noted, each blade unit 10 also includes a

spacer member 70 which enables the blade 72 to project

from the frame 20.

The equipment further includes (Figure 1) a central

control unit 74 and drive means for the carriages 16, 18

comprising an electric motor 76 connected to a

transmission mechanism 78 with one input and two outputs,

from which extend two belts 80, each of which can engage

(Figures 2 and 3) an appendage 82 projecting from the

support structure 48 either of the first carriage 16 or

of the second carriage 18 respectively.

The equipment further includes (Figure 1) a radially

expansible shaft 84 which can be rotated by a respective

motor 86 and around which are mounted (Figure 2) all of

the counter-blades 22 of the various counter-blade units

12.

The control system for the equipment is finally completed

by proximity switches, means for detecting the centring

of the carriages 16, 18 and sensors for sensing the

positions of the pistons of the actuators 54, 56. These

components are in themselves known and shown

schematically at 88, 90 and 92 in Figure 1.

In use of the cutting equipment, the various pairs of

blade units 10 and counter-blade units 12 are

longitudinally spaced along their respective elongate

support members 14 so as to allow a continuous web of

sheet material to be cut into a plurality of strips each

having a width corresponding to the spacing between the

respective adjacent pairs of blade units 10 and counter-

blade units 12.

Before the cutting operation, in order to achieve the

desired positioning of the various units 10, 12, the

control unit 74 is first programmed with data relative to

this positioning.

Then the control unit 74 activates the motor 76 and,

through the transmission mechanism 78 and the belts 80,

causes the two carriages 16, 18 to move uniformly and in

synchronism into positions adjacent a blade unit 10 and

a counter-blade unit 12 respectively constituting a first

pair, which are initially in a parked position.

Once they have reached this position, the pistons of the

second actuators 56 of the two carriages 16, 18 are

extended so as to pivot the levers 30 about their pivoted

ends 28 and disengage the friction surfaces 38 of the

heads 36 of the brake elements 32 from the respective

elongate support members 14 so that the units 10, 12 are

thus ^• released from engagement therewith and are free to slide .

The pistons of the first actuators 54 are then extended

so that their distal ends 58 engage the respective pins 60 of the units 10, 12 which are thus made fast with the

respective carriages 16, 18.

The subsequent actuation of the motor 76 then causes the

translational movement of the carriages 16, 18, together

with the units 10, 12 fixed thereto, and these latter are

thus driven to their desired positions. Once these

positions have been reached, the pistons of the first

actuators 54 are retracted, releasing the units 10, 12

from the carriages 16, 18. The pistons of the second

actuators 56 are also retracted, causing the

anticlockwise pivoting of the levers 30 which are urged

in this sense by springs not illustrated in the drawings. Thus the friction surfaces 38 of the heads 36 of the

brake elements 32 are returned to the positions

illustrated in Figures 2 and 3 in which they contact

their respective elongate support members 14 and lock the

respective units 10, 12 so as to prevent further sliding.

The cycle of operations just described is then repeated

in a similar manner for all the other pairs comprising a

blade unit 10 and a counter-blade unit 12 until all of

them are located in their respective desired positions.

During each cycle, the sensor 66 continuously transmits

to the control unit 74 information relative to the

position of the first carriage 16, with which a very

precise position of the second carriage 18 is univocally

associated by virtue of the coupling determined by the

transmission mechanism 78. Hence, whenever a difference

is found between the actual positions and the desired

positions, the control unit 74 may cause suitable

adjustments to be made to cancel these differences.

Finally once all of the units 10, 12 have been moved to

their desired positions, the shaft 84 is expanded

radially so as to fix the counter-blades 22 securely to

it .

The equipment is thus ready for the cutting proper which

is carried out in a manner similar to that of

conventional equipment.

It is clear from the description above that the

positioning of the various units 10, 12 takes place very

quickly and precisely, being completely automated and

controlled continuously. The time for which the machine

must be stopped in order for the cutting equipment to be

moved from one configuration to another is thus

considerably reduced, with obvious economic benefit.

At the same time, in order to ensure that the equipment

is even more reliable, the option of manual positioning

of the various units 10, 12 is provided so as to avoid

emergencies such as a failure of the electrical power

supply and the like.

In manual positioning, the screw 42 of a given unit is

first screwed into its hole 40 so that its distal end 44

bears against the facing surface of the frame 20 and

causes the lever 30 to pivot in a manner similar to that

caused by the distal end 62 of the piston of the second

actuator 56 during automatic positioning. Thus the brake

element 32 is disengaged from the respective elongate

support member 14 and the unit 10, 12 may be slid

manually to the desired position. At this point, the

screw 42 is again unscrewed so that the lever 30 is

returned, by pivoting in the opposite sense from its

previous pivoting, to its starting position in which the

head 36 of its brake element 32 is in frictional contact

with the respective elongate support member 14, locking

the unit 10, 12 in the desired position.

Naturally, the principle of the invention remaining the

same, the constructional details and forms of embodiment

may be varied widely with respect to that described and illustrated, purely by way of example, without thereby

departing from its scope.