WO2013068492A1

WO2013068492A1 - Method and device for cutting a tube and method for producing a heat exchanger using such a tube

Info

Publication number: WO2013068492A1
Application number: PCT/EP2012/072181
Authority: WO
Inventors: Michel BAZIN
Original assignee: Valeo Systemes Thermiques
Priority date: 2011-11-10
Filing date: 2012-11-08
Publication date: 2013-05-16
Also published as: FR2982514A1; FR2982514B1

Abstract

The invention relates to a method for cutting a tube (2), in particular for a heat exchanger, said tube (2) comprising two opposing and substantially planar longitudinal walls (22, 23). According to the invention, at least one blade, called the first blade (61'), is moved towards another blade, called the second blade (61''), the two blades being located to either side of the longitudinal walls (22, 23) of the tube (2) and in a single plane, called the cutting plane, in such a way as to cut the tube (2). The invention also relates to a device for implementing such a method.

Description

Process and device for cutting a tube and method of manufacturing a heat exchanger using such a tube

The invention relates to a method of cutting a tube, in particular for a heat exchanger, and a device for implementing this method.

It also relates to a method of manufacturing a heat exchanger using such a tube. This will particularly heat exchangers for a motor vehicle, such as condensers.

In this field, it is known tubes formed from a metal strip folded on itself so as to define an internal volume of the tube. The tube comprises two longitudinal walls substantially flat and opposite to the internal volume of the tube and two side walls connecting between them the longitudinal walls. In order to improve the thermal efficiency of the tube and the mechanical strength, that is to say its resistance to pressure, it is possible to provide a corrugated disturber inside the internal volume.

The strip and the interferer are shaped by profiling, the disrupter can be inserted continuously while the strip is still partially open. The tubes are formed continuously. When the tube is formed, it should be cut to a desired length. A first difficulty comes from the need to do the cutting operation without stopping the product. A second difficulty comes from the rigidity of the product to be cut.

There exists for the cutting of tubes a so-called "flying cut" system, consisting of an assembly comprising a blade mounted on a follower carriage. The follower carriage is driven in a rectilinear motion in the same direction as the advance of the tube being manufactured. The speed of this truck must be equal to the speed of the product during the effective working time of the blade. The blade is animated by a movement, said cross-section, performed in a plane perpendicular to the direction of the tube and in a direction parallel to the width. In the case of a folded tube comprising a disrupter, the cross section generates excessive deformation of the disrupter. This cross section also generates a material chip of the tube equivalent to the thickness of the blade. This chip can be completely torn off or remain partially on the tube which will cause a quality defect of the tube.

In order to maintain the tube during the cutting operation, it is furthermore necessary to clamp it into a die mounted on the follower carriage. The die then holds the tube during the cutting operation and includes a slot which must be adjusted perfectly to allow the passage of the blade to cut the tube. The follower carriage must thus have exactly the same speed as that of the tube. This causes a complexity of the drive mechanism of the blade, the follower carriage and the matrix and a decrease in rates due to the time required for the matrix to clamp and release the tube.

It is also known from JP20021514009 a tube cutting method in which a rotary knife performs a circular motion to cut the tubes according to their height. The invention aims to improve the situation.

The invention thus proposes a method of cutting a tube, in particular for a heat exchanger, said tube comprising two opposed and substantially planar longitudinal walls, in which method at least one blade, said first blade, is moved to another blade, said second blade, the two blades being located on either side of the longitudinal walls of the tube and in the same plane, said cutting plane, so that the tube is cut.

Due to the positioning of the blades and the use of a second blade in place of the state of the art holding matrix, the invention makes it possible to cut the tube by reducing the stroke that the blades must travel to cut the tube which increases the speed of cutting and therefore its quality. The process according to the invention also makes it possible to avoid crushing the disrupter and to create a material chip.

According to one aspect of the invention, at least the first blade is moved towards the second blade in a so-called inclination direction at an inclination angle, relative to the longitudinal walls strictly greater than 0 ° and strictly less than 90 °.

The angle of inclination with which the blade (s) penetrate into the tube thus makes it possible to cut the tube while minimizing the deformations that the tube undergoes during its cutting. In other words, the first blade moves to the second blade in a substantially rectilinear motion in the inclination direction. According to an exemplary embodiment of the invention:

the tube is scrolled in a direction of movement,

the two blades are moved parallel to the direction of movement of the tube.

The tube cutting process can thus be performed for continuous tube production, that is to say for so-called "on the fly" cuts.

Advantageously, the tube has degrees of freedom of movement in the cutting plane so that one of the blades automatically plays a role of reaction to the forces generated by the other of the blades on the tube. For example, there is a symmetrical distribution of the forces on either side of the tube.

According to one aspect of the invention, the cutting plane is perpendicular to the longitudinal walls. According to an exemplary embodiment, the second blade is moved towards the first blade in a direction opposite to the direction of inclination simultaneously with the displacement of the first blade in said direction of inclination. Advantageously, the first blade and the second blade are moved at the same distance.

According to one aspect of the invention, the blades comprise a cutting edge penetrating into the tube, said cutting edge being substantially parallel to the longitudinal walls. The cutting edge is substantially parallel to the longitudinal walls, for example, at the time of penetrating the tube and / or at the end of the stroke, in particular during the entire cutting operation of the tube. According to an exemplary embodiment, at the end of travel along said inclination direction, the cutting edges are substantially parallel to each other and situated at a distance from one another, in particular less than or equal to 0.05 mm, so that the tube is cut in half. According to another exemplary embodiment, at the end of travel along said inclination direction, the cutting edges are substantially parallel to one another and situated at a distance from one another, in particular greater than or equal to 0.2 mm, so that the tube includes a partial cut. Advantageously, the tube is then broken in two at the partial cutoff.

According to one aspect of the invention, the angle of inclination is less than or equal to 45 °. Advantageously, the angle of inclination is between 2 ° and 7 °. It is interesting to increase the angle of inclination to reduce the stroke of the blades. It is advantageous to reduce this angle to minimize the deformations of the tube.

The invention also relates to a device for cutting a tube, in particular for a heat exchanger, said tube comprising two opposite and substantially planar longitudinal walls, said device comprising:

two blades arranged to be situated on either side of the tube and movable in the same plane, called the cutting plane, and

- Means for moving at least one of the blades, said first blade, to another blade, said second blade, in the cutting plane. According to one aspect of the invention, the means for moving at least the first blade towards the second blade in the cutting plane are arranged to move or move in a direction, called inclination, intended to make an angle, said d inclination, with respect to the longitudinal walls strictly greater than 0 ° and strictly less than 90 °.

Advantageously, the device comprises:

means for scrolling the tube in a direction of displacement,

means for moving the first and second blades of said device parallel to the direction of movement of the tube.

According to an exemplary embodiment the blades comprise a cutting edge, said cutting edge being flared at an angle less than or equal to 35 °. Said cutting edge is flared at an angle, for example, substantially equal to 30 ° so that the burrs are reduced during cutting. The profile of the blades thus makes it possible to avoid creating material chips from the tube.

The invention also relates to a method of manufacturing an exchanger using tubes obtained according to the cutting method described above.

The appended figures will make it clear how the invention can be realized. In these figures, identical references designate similar elements.

Figure 1 is a schematic plan view of an embodiment of a heat exchanger comprising cut tubes by the method of the invention.

Figure 2 is a schematic view of a cutting device of a tube according to the invention. Figure 3a is a cross-sectional view of blades of the tube cutter. Figure 3b is a view similar to Figure 3a showing the blades in contact with each other.

Figure 4 is a longitudinal sectional view of the tube shown in Figure 3a.

The tubes obtained by the cutting method of the invention may be used for the manufacture of a heat exchanger 1 as shown in FIG. This exchanger is, for example, a condenser of an air conditioning loop of the passenger compartment of a vehicle.

The exchanger 1 here comprises a bundle of parallel tubes 2 whose ends 2A are connected in a fixed and sealed manner to manifolds 3, 4. In particular, the tubes 2 in which the coolant circulates extend longitudinally along an axis L, said longitudinal extension axis L of the tube 2. Between the tubes 2 are arranged interleaves 7 increasing the heat exchange surface between the coolant circulating in the tubes 2 and a second fluid, including air crossing the exchanger 1.

The various components of the heat exchanger 1 are, in particular, aluminum. They are assembled, for example, by brazing.

FIG. 2 schematically represents a device 50 for cutting the tube 2. The device 50 is supplied with the tube 2 by means of a forming unit of the tube 52 situated upstream of the device 50 with respect to the direction of displacement and forming the tube 2 so that it is ready to be cut. The tube 2 leaves the forming unit 52 and is driven outside thereof by drive rollers 51. The device 50 performs the cutting at a distance of between about 500 mm and 1000 mm from the forming unit 52, in particular between 500 mm and 1000 mm from the last drive rollers 51. The tube 2 is then cantilevered with respect to the forming unit 52, which gives it freedom of movement in a plane perpendicular to the direction of movement of the tube 2. It may be possible to provide holding rollers or sliders accompanying the tube 2 between the forming unit 52 and the cutting device 50.

Once cut, the tube 2 falls on a drive belt 59, located downstream of the cutting device 50 relative to the direction of travel of the tube 2 and below the cutting device 50. The belt 59 has a speed slightly greater than the scroll speed of the tube 2 so that two tubes 2 cut in sequence do not overlap. The carpet 59 thus allows to evacuate the tubes 2 once cut. The tube 2 here comprises two longitudinal walls 22, 23, opposite, substantially parallel to each other and for example flat. It is by one of the two longitudinal walls 22, 23 that the tube 2 is in contact with the rollers at the outlet of the forming unit 52. The device 50 also comprises means 55 for moving two blades 61 ', 61 "( better visible in the following figures) of cutting the tube 2 in a direction represented by the arrow referenced 56 in Figure 2, direction parallel to the direction of movement 57 of the tube 2. The two blades 61 ', 61 "are here from and other longitudinal walls 22, 23 of the tube 2 and in a same plane, said cutting plane. The means 55 for moving the two blades 61 ', 61 "parallel to the direction of displacement 57 of the tube 2 have a speed equal to the speed of the tube 2 during the cutting work of the tube by the blades 61', 61" so that the cutting can be done precisely and continuously, that is to say without stopping the forming unit 52 and thus without stopping the movement of the tube 2.

The device 50 further comprises means 58 for moving at least one of the blades 61 ', said first blade, to the other of the blades 61 ", said second blade, in the cutting plane so as to cut the tube 2. Otherwise according to the cutting method of the tube 2 of the invention, at least the first blade 61 'is moved towards the second blade 61 "in the cutting plane so that the tube 2 is cut. FIG. 3a illustrates the first and second blades 61 'and 61 "as well as one of the tubes 2 of the exchanger according to section III-III of FIG. 2, that is to say in a cross section. parallel to the cutting plane Such a tube 2 comprises a metal strip 20, folded on itself so as to define an internal volume 21 of the tube 2. The strip 20 has the two longitudinal walls 22, 23, respectively called lower wall 22 and top wall 23. The tube 2 also comprises two side walls, said left wall 24 to the left in Figure 3a and right wall 25 to the right in Figure 3a, connecting the two longitudinal walls 22, 23 between them. 24, 25 are, in particular, semi-circular shape so that the tube 2 has a substantially oblong cross section.

The strip 20 also comprises a first edge portion 41 and a second edge portion 42 joining so as to divide the internal volume 21 into at least two channels over all or part of the length of the tube 2. The tube 2 then presents a B-shaped profile

The tube 2 has a disrupter 30, for example, corrugated and inserted into said internal volume 21. Said disrupter 30 defines a plurality of channels 31, in which the fluid circulates so that it increases the heat exchange surface and the mechanical strength of the tubes 2.

The first blade 61 'of the device is here disposed above the tube 2 while the second blade 61 "of the device is disposed below the tube 2. The blades are thus located on either side of the tube 2, and are, for example, symmetrical with each other, they extend substantially in the plane of section, The blades 61 ', 61 "comprise a cutting edge 65, beveled and allowing the blades to penetrate the tube 2 in order to cut it. Here, the first blade 61 'is moved towards the second blade 61 "in the cutting plane in a direction of inclination represented by the arrow referenced 62 in order to cut the tube 2. The inclination direction 62 is in the plane of inclination. cut and makes an angle with respect to the longitudinal walls 22, 23 strictly greater than 0 ° and strictly less than 90 °. This angle a is advantageously less than 45 °. It is for example between 2 ° and 7 ° to limit the deformation of the tube 2. The cutting edge may be substantially parallel to the longitudinal walls 22,

23, for example, at the moment when it enters the tube 2 and in particular at the end of stroke blades 61 ', 61 ". Advantageously, the cutting edge is substantially parallel to the longitudinal walls 22, 23 during all the cutting work of the tube 2 by the blades 61 ', 61 ".

The cutting of the tube 2 can be effected by the displacement of one of the two blades, for example, the first blade 61 'towards the other of the two blades, in particular the second blade 61 ". by moving the two blades towards each other, the second blade 61 "moving in a direction represented by the arrow referenced 63, direction opposite to the inclination direction 62. In this last variant, the two blades 61 ', 61 "move, for example, simultaneously, the movement of the blades 61', 61" is, in particular, substantially rectilinear manner.

Since the tube 2 has degrees of freedom of movement in the plane of section, it will be able to self-adjust between the blades 61 ', 61 "so that the cutting forces will be distributed on each side of the tube 2. Thus, in the case where only the first blade 61 'moves, it penetrates inside the tube 2 a distance equivalent to that traveled inside the tube 2 by the second blade 61 ". Indeed, the second blade 61 "does not move, it is the tube 2 which moves to the second blade 61" thanks to its degrees of freedom of movement in the cutting plane. FIG. 3b illustrates an exemplary embodiment according to which the two blades 61 ', 61 "move towards one another at the same distance. At the end of the stroke, the cutting edges 65 are, for example, substantially parallel between them and located here at a distance from each other less than 0.05 mm so that the tube 2 is cut in half.

Note that at the end of the stroke, the cutting edges 65 could be, for example, at a distance from each other greater than 0.2 mm so that the tube 2 comprises a partial cut. In this embodiment, the method according to the invention provides for breaking the tube 2 in two at the partial cut.

FIG. 4 illustrates the fact that the cutting plane here is perpendicular to the longitudinal walls 22, 23 of the tube 2. Thus, the cutting of the tube 2 by the blades 61 ', 61 "takes place in a plane perpendicular to the longitudinal walls 22, 23. In other words, according to the example shown in Figure 4, the blades extend in the plane of section in addition to moving according to the latter.Of course, the blades 61 ', 61 "could s extend in planes close to the plane of section, that is to say inclined less than 10 °, especially 5 ° with respect to the latter without departing from the scope of the invention.

In order to facilitate the cutting of the tube 2 by the blades 61 ', 61 ", the cutting edges may be of beveled shape so that it forms a cutting tip, that is to say that the cutting edges are sharpened. The cutting edges 65 are here doubly bevelled so that they are symmetrical with respect to the sectional plane, the cutting edges 65 thus forming an angle β, for example less than or equal to 35 °, in particular substantially equal to 30 °. thickness I of the blades 61 ', 61 "in the longitudinal direction L is preferably substantially equal to 0.4 mm.

According to an advantageous embodiment, the sharpening of the blades 61 ', 61 "and their thickness are configured to allow the blades 61', 61", during cutting, to be in contact with the tube 2, for example, only at their cutting edge, that is to say the beveled edge.

Claims

1. A method of cutting a tube (2), in particular for a heat exchanger (1), said tube (2) comprising two longitudinal walls (22, 23) opposite and substantially planar, in which method moves at least one blade, said first blade (61 '), towards another blade, said second blade (61 "), the two blades being located on either side of the longitudinal walls (22, 23) of the tube (2) and in the same plane, said cutting plane, so that the tube (2) is cut.

2. Method according to claim 1, wherein at least the first blade (61 ') is moved towards the second blade (61 ") in a direction (62), said inclination angle (a), said inclination, with respect to the longitudinal walls (22, 23) strictly greater than 0 ° and strictly less than 90 °.

The method of claim 1 or 2, wherein:

the tube (2) is scrolled in a direction of displacement (57),

the two blades (61 ', 61 ") are moved parallel to the direction of movement of the tube (57).

4. Method according to any one of the preceding claims, wherein the tube (2) has degrees of freedom of movement in the cutting plane so that one of the blades automatically plays a role of reaction to the forces generated by the other blades on the tube (2).

5. Method according to any one of the preceding claims, wherein the cutting plane is perpendicular to the longitudinal walls (22, 23).

The method of any of the preceding claims, wherein the second blade (61 ") is moved toward the first blade (61") in a direction (63) opposite the tilting direction (62) simultaneously. moving the first blade (61 ') in said tilting direction (62).

7. The method of claim 6, wherein moving the first blade (61 ') and the second blade (61 ") by the same distance.

The method of any one of the preceding claims, wherein the blades (61 ', 61 ") comprise a cutting edge (65) penetrating into the tube

(2), said cutting edge (65) being substantially parallel to the longitudinal walls (22, 23).

9. Method according to any one of the preceding claims, wherein at the end of stroke in said direction of inclination (62) the cutting edges (65) are substantially parallel to each other and located at a distance from one another so that the tube (2) comprises a partial cut.

10. The method of claim 9, which breaks the tube (2) in two at the partial cut.

1 1. A method as claimed in any one of the preceding claims, wherein the angle of inclination (a) is less than or equal to 45 °.

12. A method according to any one of the preceding claims, wherein the angle of inclination (a) is between 2 ° and 7 °.

13. Device (50) for cutting a tube (2), in particular for heat exchanger, said tube (2) comprising two longitudinal walls (22, 23) opposite and substantially flat, device (50) comprising:

- two blades (61 ', 61 ") arranged to be located on either side of the tube (2) and movable in the same plane, said cutting plane and

- Means (58) for moving at least one of the blades, said first blade (61 '), to another blade, said second blade (61 ") in the cutting plane.

14. Device (50) according to claim 13, wherein the means (58) for moving at least the first blade (61 ') to the second blade (61 ") in the cutting plane are arranged to move them or according to a direction (62), called inclination, intended to make an angle (a), said inclination, with respect to the longitudinal walls (22, 23) strictly greater than 0 ° and strictly less than 90 °.

15. A method of manufacturing an exchanger using tubes obtained according to the cutting method of any one of claims 1 to 12.