FR2860447A1 - METHOD OF CUTTING A LINE TUBE AND CUTTING DEVICE USING SAID METHOD - Google Patents

Abstract

The present invention relates to a flexible cutting method and device for use with all tubes, including paperboard tubes, wherein a tube is simultaneously rotated and axially translated forwards to achieve, regardless of the tube thickness, a clean high-quality cut with no warping or burrs, without affecting production costs. Said cutting device (1) comprises two opposed rotary cutters (3) each mounted on a carriage (34) that is radially translatably movable in a direction perpendicular to the forward direction of the tube (2), and said carriages (34) are supported on an axially translatably movable holder (50) synchronised with the forward movement of the tube. The drive means (4) for driving the carriages (34) are arranged to move the cutters (3) intermittently towards the tube in cutting increments up to at least the entire thickness of the tube. Each cutting increment corresponds to a predetermined cutting depth so that the tube is cut in a series of steps. The cutting process may be followed by grooving or partial cutting steps performed using the same cutters (3) at a cutting depth smaller than the thickness of said tube (2). The present invention is useful for making tubes, particularly paperboard tubes, using a spiral winder or widening means.

Description

METHOD OF CUTTING A LINE TUBE AND CUTTING DEVICE USING

 UVRE LEDIT PROCESS

  The present invention relates to a method of cutting a tube in line, this tube being driven by a rotational movement on itself and a forward movement by axial translation, this method using at least one knife disposed in a predetermined cutting plane, this knife being simultaneously driven by a translation perpendicular to the advance of said tube in said cutting plane and an axial translation synchronized to the advance of said tube to cut at least one tube section.

  The present invention also relates to a cutting device implementing this method and comprising at least one knife disposed in a predetermined cutting plane, first knife driving means in radial translation perpendicular to the advance of said tube and second means for driving the knife in axial translation synchronized with the feed of said tube for cutting at least one tube section.

  The tubes concerned by this invention are mainly cardboard tubes, of all sizes, used as a winding support, for example in the fields of stationery, textiles, metallurgy, etc. These tubes are generally manufactured continuously on a machine for winding paper strips commonly called a spiral or chuck. At the output of this machine is placed a cutting device for cutting the tube obtained in sections of predefined length. This cutting device usually comprises two knives arranged on either side of the tube simultaneously animated with a forward movement in axial translation and a rotational movement on itself, these knives comprising a rotary cutting blade. They are mounted on carriages animated with a radial translation in advance and backward, the assembly being mounted on a movable support axially synchronized with the advance of the tube. Until now and regardless of the thickness and hardness of the cutting tube, the cut was made in a single pass. That is to say that the knives were moved in one stroke on a stroke equal to the thickness of the tube to cut it in less than a turn of the tube, about half a turn. This process is ideal for thin tubes and provides a clean cut, clean, without burrs and in a plane well perpendicular to the axis of the tube. For tubes having a thickness for example of 20 mm or more, this method does not achieve the same performance. Indeed, when the knives dive into the thickness of the tube at one time, the forces generated by the resistance of the tube tend to deform their cutting blade and to deflect their stroke generating a false cut of the tube. The cut is not clear, has burrs and is deviated from the plane perpendicular to the axis of the tube. This false cut can also locally generate deformations and / or crashes at the end of the tube that may penalize its future use. In addition, the forces collected by the knives are transmitted to the carriages, the movable support and the entire cutting device causing premature fatigue of its organs. This cutting process is therefore not satisfactory for thick or very hard tubes.

  The present invention aims to overcome these drawbacks by proposing a cutting process which takes into account the thickness and hardness of the tube and which allows a quality free cut, without impact on the cost of production, as well as a corresponding cutting device, reliable and can be suitable for any type of tubes.

  For this purpose, the invention relates to a cutting method of the kind indicated in the preamble, characterized in that the tube is cut in several successive stages by moving the knife towards the tube, in a discontinuous manner, in stages. cutting, until at least reaching the total thickness of the tube, each cutting bearing corresponding to a predetermined cutting depth.

  Advantageously, the number of cutting steps is determined as a function of at least one parameter characterizing the cutting tube chosen from the group comprising at least its thickness, hardness, density and diameter, and the enslavement is controlled. cutting knife advance control according to this parameter.

  It is preferable to use two knives arranged in the same plane of section, in opposition on either side of said tube, and the movement of the knives in said cutting plane is controlled in a synchronous and opposite manner. In this case, each cutting stage is performed on at least half a turn of the tube.

  At least two knives arranged in different cutting planes can be used to cut at least two tube sections. In this case, it controls the movement of each knife in its cutting plane independently, synchronized or offset, or in a dependent manner.

  It is also possible to use at least two pairs of knives, the knives of each pair being arranged in the same plane of section, in opposition on both sides of the tube. In this case, it controls the movement of the knives of each pair in their cutting plane in a synchronous and opposite manner.

  For this purpose, the invention relates to a cutting device of the kind indicated in the preamble, characterized in that the first drive means are arranged to move said knife towards said tube discontinuously, by cutting stages until reaching at least the total thickness of the tube, each cutting bearing corresponding to a predetermined depth of cut so as to cut the tube in several successive steps.

  In a preferential manner, this device comprises servo-control means arranged to control the first drive means as a function of at least one parameter characterizing said cutting tube chosen from the group comprising at least its thickness, its hardness, its density, its diameter, and for controlling the second driving means according to at least the speed of advance of the tube.

  These servo-control means may comprise at least one programmable control unit and the drive means may be chosen from the group comprising at least the motors, the stepper motors, the servomotors, the cylinders, the cam systems.

  In a preferred embodiment, this device comprises two knives arranged in the same plane of section, in opposition on both sides of the tube, and the first and second drive means are common to both knives.

  It may comprise at least two knives arranged in different cutting planes for cutting at least two pipe sections or at least two pairs of knives, the knives of each pair being arranged in the same section plane, in opposition to each other and to other of the tube.

  In the preferred embodiment, each knife is mounted on a carriage coupled to the first drive means, all mounted on a movable support coupled to the second drive means.

  The first drive means can be coupled to the carriages of the same pair of knives by a double worm nut connection, the winding of the endless screws being opposite.

  According to the embodiments, the knife or knives are coupled to rotating drive means.

  The present invention and its advantages will appear better in the following description of an embodiment, given by way of non-limiting example, with reference to the accompanying drawings, in which: FIG. 1 is a side view of a device for FIG. 2 is an end view of the cutting device of FIG. 1, and FIGS. 3A-D are detailed views of the tube and cutters illustrating cutting progress.

  With reference to FIGS. 1 and 2, the cutting device 1 according to the invention is generally positioned at the outlet of an in-line tube-making machine by winding paper strips, commonly called a spiral or mandrel, and allows cutting of the tube 2 obtained in sections of predetermined length.

  This cutting device 1 is fed by the tube 2 simultaneously driven by a rotational movement on itself and a forward movement by axial translation, these movements being generated by the tube manufacturing machine. The tube 2 is guided in translation in the cutting device 1 to the cutting zone. After the cutting zone, the pipe sections 2 are discharged from the cutting device 1 by any known discharge means (not shown), such as a conveyor belt, a chute, etc. to a storage area (not shown) or palletizing. The guide tube 2 in translation is provided by external guides: top 20, bottom 21 and side 22, adjustable in position depending on the diameter of the tube 2 by any known means. This guidance can be completed further by an inner mandrel (not shown). In FIG. 2, the tube 2 is represented by the smallest diameter and the largest diameter allowed on this cutting device 1. The advance movement of the tube 2 follows an axis coinciding with the median plane A of the cutting device 1 .

  On either side of this median plane are arranged two knives 3 aligned in the same sectional plane B and defining the cutting zone. Each knife 3 consists of a circular cutting blade 30 driven in rotation by a motor 31 and a gear transmission 32 and chain 33. Other drive means are also possible and can be coupled directly to the circular blade 30 or by other means of transmission. In other embodiments not shown, the cutting blades are not motorized and are rotated by the single rotation of the tube 2. The two knives 3 are diametrically opposed, one serving as a support against the other in order to avoid misaligning the tube 2. If only one knife 3 is provided, it is then necessary to provide a counter-support on the opposite, for example by means of a rotating roller. This cutting device 1 may also comprise several knives 3 or pairs of knives 3 arranged in separate cutting planes to cut simultaneously or not several tube sections 2.

  Each knife 3 is mounted on a carriage 34 movable in translation in said cutting plane B by first drive means 4. In the example shown, these first drive means 4 comprise a motor 40 coupled to a worm 41, for example ball, by means of a pulley transmission 42 and belt 43, the worm 41 meshing with a nut 44 integral with the carriage 34. These first drive means 4 are common to the two knives 3 since they drive a double worm 41 inverted winding. Each carriage 34 is guided in translation by a raceway 35 provided on either side of the worm 41, between the carriage 34 and a support 50. Of course, other drive, transmission and guidance may be appropriate. In Figure 2, the knife 3 of the left is shown in two positions respectively corresponding to the two extreme sizes of the tube 2. The right knife 3 is only partially represented.

  The carriages 34 are mounted on a support 50 movable in axial translation by second drive means 5 synchronized to the advance of the tube 2. These second drive means 5 comprise a motor 51 provided with a motor pinion 52 meshing with a notched belt 53 secured to said support 50. This toothed belt 53 extends parallel to the median plane A and forms a closed loop which circulates between a pinion receiver 54 and the drive pinion 52. The support 50 is guided in translation by two rails 55 parallel secured to a frame 6 and stopped in translation by two flexible stops 56 provided on this frame. Of course, other drive, transmission and guide means may be suitable. In FIG. 1, the extreme positions of the support 50 are shown on the left as a strong line and on the right as a thin line and partially.

  The frame 6 is for example made of an assembly of welded steel profiles and sheets and houses in particular the motors 40 and 51 of the first and second drive means 4, 5. This frame 6 is covered with a cover 7, made by example in an assembly of plates and translucent plates, and houses in particular the tube 2, the knives 3, the carriages 34 and the support 50.

  This cutting device 1 also comprises a control unit (not shown) programmable to control the various motors 31, 40 and 51 according to parameters such as the diameter, the thickness and the speed of travel of the tube 2, these motors being for example servomotors.

  This cutting device 1 allows great flexibility and flexibility of use. It can thus be suitable for different tube sizes 2 and can make quality cuts regardless of the thickness of the tube 2. For the tubes 2 of small thickness, for example less than 20 mm, the cutting is carried out in a manner known in one step. The knives 3 are moved in radial translation in their cutting plane towards the tube 2 on a cutting stroke equal to at least the thickness of the tube 2 to be cut. Thus, the section is cut into one less than one turn of tube 2, about half a turn.

  For tubes 2 of greater thickness E, for example greater than or equal to 20 mm and / or having high hardnesses or densities, the section is made in several successive steps as illustrated by FIGS. 3A to 3D. In FIG. 3A, the knives 3 are approached from the tube 2. In FIG. 3B, the knives 3 are displaced by a first cutting stroke C1 less than the thickness E of the tube 2, so that after a first half turn, the tube 2 is partially cut to a depth P1. In FIG. 3C, the knives 3 are displaced by a second cutting stroke C2, the sum of the races C1 and C2 being even smaller than the thickness E of the tube 2, so that after a second half turn, a complete turn, the tube 2 is partially cut to a depth P2. In FIG. 3D, the knives 3 are moved by a third cutting stroke C3, the sum of the strokes C1 to C3 being now equal to the thickness of the tube 2, so that after a third half turn, ie one turn and half, the tube 2 is cut completely over its entire thickness E. The next step is the movement of the knives 3 in the opposite direction and in a single step to be able to restart a cutting cycle. These different cutting steps are of course carried out simultaneously with the axial advance of the tube 2 by means of the second drive means 5 which move the support 50 carrying said knives 3. Thus, a section of the tube 2 is obtained step by step, each step corresponding to a half turn of the tube 2. The number of cutting steps may vary depending on the parameters of the tube 2 which determines its ability to be cut, such as its thickness, density, hardness, material, etc. This stepwise cutting process has the advantage of making a quality cut, without crushing or deforming the tube 2, without burring, or false cutting and without deformation or deflection of the cutting blades 30. Of course, if the device of cut 1 comprises only a knife 3, each cutting bearing will be performed on at least one complete revolution of the tube 2.

  The present invention is not limited to the embodiment described but extends to any modification and variation obvious to a person skilled in the art while remaining within the scope of protection defined in the appended claims.

Claims (14)

claims   1. A method of cutting a tube (2) in line, this tube being simultaneously driven by a rotational movement on itself and an advance movement by axial translation, this method using at least one knife ( 3) disposed in a predetermined cutting plane (B), this knife (3) being simultaneously driven by a translation perpendicular to the advance of said tube (2) in said cutting plane (B) and a synchronized axial translation on the advance of said tube (2) for cutting at least one tube section, characterized in that the tube (2) is cut in several successive stages by moving the knife (3) towards the tube, discontinuously, in steps of cutting, until at least the total thickness (E) of the tube (2), each cutting bearing corresponding to a predetermined cutting depth (P1, P2, P3).   2. Method according to claim 1, characterized in that one determines the number of cutting steps according to at least one parameter characterizing the tube (2) to be cut selected from the group comprising at least its thickness, its hardness , its density, its diameter, and in that one slaves the cutting advance control of the knife (3) according to this parameter.   3. Method according to claim 1, characterized in that two knives (3) are used arranged in the same plane of section (B), in opposition on both sides of said tube (2), in that controlling the movement of the knives (3) in said cutting plane in a synchronous and opposite manner and in that each bearing; cutting is performed on at least a half turn of the tube (2).   4. Method according to claim 1, characterized in that at least two knives (3) are used in different cutting planes (B) to cut at least two tube sections.   5. Method according to claim 4, characterized in that at least two pairs of knives (3) are used, the knives (3) of each pair being arranged in the same plane of section (B), in opposition from and other of said tube (2), and in that it controls the movement of the knives (3) of each pair in said cutting plane (B) synchronously and opposite.   6. Cutting device (1) of a tube (2) in line, this tube (2) being simultaneously driven in a rotational movement on itself and a forward movement by axial translation, this device comprising at least one knife (3) arranged in a predetermined cutting plane (B), first drive means (4) of the knife (3) in radial translation perpendicular to the advance of said tube (2) and second means drive (5) of the knife (3) in axial translation synchronized on the advance of said tube (2) for cutting at least one tube section, characterized in that the first drive means (4) are arranged to move said knife (3) in the direction of said tube (2) discontinuously in cutting steps until at least the total thickness (E) of the tube (2) is reached, each cutting bearing corresponding to a depth of cut ( P1, P2, P3) so as to cut the tube (2) in several successive steps.   7. Device according to claim 6, characterized in that it comprises servo-control means arranged to control said first drive means (4) as a function of at least one parameter characterizing said tube (2) to be cut selected in the group comprising at least its thickness, its hardness, its density, its diameter, and for controlling said second drive means (5) as a function of at least the speed of advance of said tube (2).   8. Device according to claim 7, characterized in that the servo means comprise at least one programmable control unit and the drive means (4, 5) are selected from the group comprising at least the motors, the motors not stepping motors (40, 51), cylinders, cam systems.   9. Device according to claim 6, characterized in that it comprises two knives (3) arranged in the same plane of section (B), in opposition on both sides of said tube (2), and in that the first and second drive means (4, 5) are common to both knives (3).   10. Device according to claim 6, characterized in that it comprises at least two knives (3) arranged in different cutting planes (B) for cutting at least two pipe sections (2).   11. Device according to claim 10, characterized in that it comprises at least two pairs of knives (3), the knives (3) of each pair being arranged in the same section plane (B), in opposition of part and another of said tube (2).   12. Device according to one of claims 9 to 11, characterized in that each knife (3) is mounted on a carriage (34) coupled to said first drive means (4), all mounted on a support (50). ) movable coupled to said second drive means (5).   13. Device according to claim 12, characterized in that the first drive means (4) are coupled to the carriages (34) of the same pair of knives (3) by a double connection nut (44) worm ( 41), the winding of the worm (41) being opposite.   14. Device according to claim 6, characterized in that said knife (3) is coupled to drive means (31) in rotation.