The invention relates to a device for locking in position a roll of paper during the cutting operation, i.e. of reducing a roll of tissue paper of greater length, called log, into rolls of shorter length.
For the same purpose, devices for cutting machines have been known for some time which block the log while an orbital blade cuts roll sections intended to form rolls of the desired length.
These devices are provided with two locking members, called clamping devices, which tighten the two parts of the log at the sides of a cutting area where the blade of the cutting machine passes, which carries out the cut by advancing through the layers of the wound paper that forms the roll.
Some known devices only have a blocking and unlocking movement of the roll and are controlled in such a way as to keep the roll sections still during cutting and release them after completion to allow the roll to advance along the feed channel of the saw blade and to start the subsequent cutting cycles.
From EP1970175 a locking device is known in which, instead of locking the sections of the roll being formed, during the advancement phase of the blade through the log, the two clamping devices are moved away from each other, drawing the respective log portion, in such a way the blade forms a cut that progressively opens as it proceeds, to the purpose of causing the minimum friction of the paper with the blade.
However, the already known devices have some drawbacks in relation to the accuracy of the cut obtained, which can get worse due to the movement of the two sections of the log and to the high heat that is generated during the cut and absorbed by the blade, which can be estimated at approximately 50% absorbed during cutting and 50% due to the contact of the paper with the blade after the cut, before the removal of the log portion cut to size.
The mere contact of the blade with the paper immediately after the end of the cut determines in fact an overheating of the blade with deformations and other negative effects, which are felt in particular for intensive use of the saw blade with high frequency of the cutting cycles.
With the present invention it is intended to overcome the drawbacks of the already known solutions and to propose an improved clamping device with respect to devices of the known type, which is capable of contributing to a precise cutting of the log, minimizing the negative effects of the transmission to the blade of the heat generated during the cut.
A further aim is to propose a clamping device of simple and reliable construction, usable with new or pre-existing cutting machines.
These aims have been achieved by realizing a clamping device for cutting machines according to the attached claims, in which the clamping devices are locked during their cutting and they are opened, and therefore the two sections of the log, once the cut has just taken place so as to timely interrupt the heat exchange between paper and blade.
A first advantage of the invention consists in the high cutting precision which is achieved by the reduction of heat transmitted towards the blade.
A second advantage consists in the high reliability of the device.
A further advantage is the reduction of energy consumption.
An even further advantage consists in the lower contamination of the paper log on the cut section thanks to the use of a lower quantity of lubricant.
A still further advantage consists in the reduced need for blade cooling and in the lengthening of the useful life of the blade, estimated at an increase of 10-15%.
These and further advantages will be better understood by a person skilled in the art from the following description and the attached drawings, given as a non-limiting example, in which:
With reference to the drawings, a device for locking the adjacent sections 1, 2 of a roll of paper 3 cut off by the cutting blade 5 of a cutting machine M is described, schematically represented in
The cutting machine M is of the conventional type and comprises a frame 50 in which a motor (not shown) is housed for driving, for example by means of a belt transmission 53, an arm 51 carrying the rotating cutting blade 5, and provided preferably of a sharpening unit 52 and counterweights 56, also of a conventional type.
In operation, the blade 5 follows an orbital cutting path during which the cutting edge of the blade advances inside the roll 3 along a cutting section plane 4, with the adjacent sections 1, 2 of the roll 3 arranged in a feed channel 55 and each held in position by gripping members, called clamping devices, 6, 7 which are positioned along the channel 55 slightly spaced upstream and downstream of the cutting plane defined by the movement of the blade 5 so as to be able to let pass the blade during the operations.
With particular reference to the embodiment illustrated in
In the example described, both clamping devices 6, 7 comprise an open cylindrical sleeve 41 formed by two cylindrical portions 42, 43 reciprocally movable in a movement of contraction or expansion with respect to the roll 3 controlled by a respective hydraulic actuator 8 fixed at one end 57 to the frame 40 and at the other end 59 to an oscillating pedal 62 connected to a portion 43 of the cylindrical sleeve 41 movable by deformation by means of a tie rod 60 and a lever 61 fixed, for example by welding, to the deformable portion 43 and guided by a pin 63 sliding in a guide 64 which emerges and is integral with the frame 40.
Preferably, each clamping device is controlled by an actuator 8 connected to the clamping device by two levers 61 spaced along the length of the clamping device and operating as described above.
In operation, in order to pass from an open expanded unlocking configuration to a closed contracted locking configuration of the respective section 1, 2, the actuator 8, for example an hydraulic actuator, is commanded to push the pedal 62 which by means of the tie rod 60 causes the lowering of the lever 61 guided by the pin 63 and therefore the deformation of the cylindrical portion which surrounds and stably tightens the roll 3 arranged inside the clamping device.
According to the invention, the device is also provided with at least one second actuator 10 connected to the clamping devices 6, 7 to perform a reciprocal movement of the clamping devices in a locking configuration with respect to said cutting section plane 4, which are active immediately after the end of the cutting cycle of the roll 3, and of means 11 for inhibiting the moving away movement of the clamping devices which are instead active during the cutting advancement of the blade 5 through the roll 3.
Preferably, the inhibition means 11 comprise an actuator 11 which during the cutting advancement of the blade 5 maintains a locking pin 66 in an interfering position with the removal movement of the clamping devices 6, 7.
In the example described, the activation and control of the actuators 10 and 11 are carried out by means of a control and activation unit 12, schematized in
In the functioning of the device, during the cutting phase the unit 12 keeps the clamping devices in the locking position of the sections 1, 2 and the locking pin 66 of the actuator 11 in an advanced interference position so as to inhibit any lateral movement of the clamping devices.
At the end of the cut, the unit 12 keeps the clamping devices locked on the sections, releases the pin 66 which returns from the interference position, and activates the actuators 10 to perform the lateral removal of the sections 1, 2 from the blade 5.
Subsequently, the sections can be freed by expanding the clamping devices, the roll 3 is made to advance along the channel 55 for the execution of a further cutting cycle.
Alternatively, it is possible to provide that the means for inhibiting the lateral movement of the clamping devices during cutting are constituted by the same actuators 10, if sized sufficiently to be able to oppose the lateral thrust exerted by the blade 5 on the sections 1, 2 during cutting and controlled by the unit 12 so as to remain stationary during the cutting phase.
Advantageously, with this solution the precision of the cut is guaranteed by preventing the movement of the sections during the advancement of the blade 5 through the roll and at the same time excessive overheating of the blade is avoided by detaching the sections 1, 2 from the blade as soon as the cut is concluded.
In the example illustrated in
Alternatively, it will be possible to provide actuators 10 connected to both clamping devices and controlled by the unit 12 so as to carry out the movement away at the end of the cut.
In greater detail, the symmetrical constraint kinematics may comprises a rocker mechanism 13a provided with a lever 14 with a fixed central fulcrum 15 and two opposite ends 16 fixed to first ends 18 of respective first and second rods 20, 21 in turn each fixed with second ends 22, 23 to a respective clamping device 6, 7. With this solution, when at the end of the cut the actuators 10 impose the moving away of the first clamping device 6, this movement causes a rotation of the lever 14 and a symmetrical removal of the second clamping device 7 connected to the second rod 21.
With reference to the exemplary embodiment schematized in
Similarly, with reference this time to the embodiment schematized in
With this solution, when the actuator 10 commands the first clamping device 6 to move away from the cutting area and the displacement of the respective rack 33 due to the rotation of the intermediate toothed wheel 35, the opposite rack 34 connected to the second clamping device 7 determines its symmetrical displacement.
The present invention has been described according to preferred embodiments but equivalent variants can be conceived without departing from the scope of the invention.
Number | Date | Country | Kind |
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102021000011042 | Apr 2021 | IT | national |
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Number | Date | Country |
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1970175 | Sep 2008 | EP |
Number | Date | Country | |
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20220347880 A1 | Nov 2022 | US |