FR2713114A1 - Heat exchanger mfr. process for vheicle radiator - Google Patents

Abstract

The heat exchanger for use in cooling an engine includes two sets of fluid collecting tubes (TC). These have transverse slots formed in them in order to receive the ends of further flat tubes carrying the heat transfer fluid. A pre-cut slot is formed in the collecting tube by insertion of a cutting tool (OC) slicing over the surface of the collecting tube. A further shaping tool (OF) is then inserted at right angles in order to mould the shape of the slot. This slot is subsequently used for attachment of the perpendicular liquid carrying tubes forming a radiator.

Description

Improvements to the manufacture of a heat exchanger. especially for vehicles
The invention relates to heat exchangers, in particular for vehicles.

One type of exchanger comprises two fluid collecting tubes, or two segments of the same collecting tube, between which communication is established by means of transfer tubes, themselves in contact with heat exchange interleaves with Ambiant air.

 It is interesting that the transfer tubes are flat.

In this case, the assembly of the heat exchanger comprises the following operations (a) machining transverse slots in at least one fluid collecting tube, by sawing or punching, (b) inserting the ends of the tubes into these slots transfer dishes, coated in principle with a brazing composition, and (c) the assembly is heated to brazing temperature, to fix the transfer tubes in leaktight manner on the collecting tube.

The machining techniques known for step a) pose a problem: some, such as sawing, produce mobile residues inside the collecting tube, hence the need for a cleaning operation.

The present invention improves the situation.

According to a first characteristic of the invention, the aforementioned step (a) comprises
al) the joining of a collecting tube with respect to a support,
a2) cutting slots by passing a plurality of shearing tools, and
a3) the insertion into the slots of a plurality of forming tools capable of producing non-detachable internal burrs and shaped by the forming tools, while in step c) fixing the transfer tubes on the collecting tube is carried out at least in part on said shaped burrs.

Preferably, these steps are carried out consecutively or simultaneously for two collecting tubes having homologous transverse slots. In this case, the ends of the flat transfer tubes are inserted, one into one of the collecting tubes and the other into the other, while in step (c) the fixing of the transfer tubes takes place. performs simultaneously on the two collecting tubes.

According to a particularly advantageous characteristic of the invention, step (a2) comprises cutting pre-slits located in the positions of the slits, using a plurality of shearing tools, driven in translation so that their cutting points attack the tube to the right of the recesses of the mandrel, these pre-slots each having a width substantially equal to the desired width for the slots, and lengths slightly less than those of the final slots. In step a3), the forming tools have a thickness substantially equal to that of the shearing tools, and a width substantially equal to that desired for the slit, which gives the slits their final shape, while producing burrs.

In an advantageous embodiment, the leading edge of the forming tools is followed by a peripheral shoulder allowing the production of a chamfer facilitating the introduction of the end of a transfer tube into a slot.

Other characteristics and advantages of the invention will appear on examining the detailed description below, as well as the appended drawings, in which - FIG. 1 is a simplified diagram of a heat exchanger for vehicles; - Figures 2A and 2B are respectively a top view with partial cutaway and a longitudinal sectional view of a collecting tube for heat exchanger; - Figures 3A and 3B are two schematic sectional views of a tool for implementing the invention; - Figures 4A to 4C illustrate four successive states in the implementation of the shearing step according to the present invention; - Figures 5A and 5B are respectively a front view and a side view of a shearing tool; - Figures 6A and 6B, as well as 7A and 7B are respectively a front view and a side view of a punching tool, respectively in the preferred embodiment and in a possible variant; - Figures 8A to 8F illustrate the forming step according to the invention; and - Figures 9A to 9D illustrate in more detail the tube at one of the slots made according to the present invention.

The attached drawings are, for the most part, certain. Consequently, they are to be considered as an integral part of the present description, and may not only serve to make it better understood, but also contribute to the definition of the invention, if necessary.

In FIG. 1, the exchanger consists of two collecting tubes TC1 and TC2, having respectively an inlet pipe TA and an outlet pipe TS. The tube TC1 is provided with extreme partitions CL10 and CL19 as well as an intermediate partition CL15. Likewise, the tube TC2 is provided with partitions CL20 and CL29 at its ends CL25 in the intermediate part.

Between the two collecting tubes TC1 and TC2, and in communication by their ends with these, are mounted transfer tubes TT1 to TT8. Between them, and taking into account an upper wall PS0 and a lower wall PI9, are mounted for example nine heat exchange spacers IE1 to IE9. The fluid circuit obtained is illustrated in FIG. 1.

FIGS. 2A and 2B show a more detailed example of a collecting tube, which in this case comprises several intermediate partitions. FIG. 2B shows that the slits are made with a pitch P, and with the number of N, which implies that the distance between two extreme slits is (n-l) .P.

In a variant, instead of two collecting tubes, transfer tubes of different shapes are provided, which can then return to the same collecting tube.

With reference to FIGS. 3A and 3B, the collecting tube TC is mounted on a support S, defined by a frame S1, the lower part of which exactly houses the tube, and removably receives a cover S2, shaped to adapt to the bottom of the tube
TC.

In the frame S1, horizontal through passages, such as S10 allow the passage of shearing tools, such as OC, here with an upper guide in Sll. Each shearing tool is capable of alternating translations from left to right and vice versa. The shape of a shearing tool is illustrated in FIGS. SA and 5B, with an angle a less than 45.

From the top of the frame S1 to the passage S10, other vertical non-crossing passages, such as S15, allow the passage of forming tools, such as OF, with bilateral guidance.

OF forming tools can be translated alternately from bottom to top and vice versa. The shape of a forming tool is illustrated in Figures 6A and 6B, or alternatively 7A and 7B.

Shear tools such as forming tools can be articulated on pusher carts, themselves fixed on a mobile assembly, either horizontal in the case of shearing tools, or vertical in the case of forming tools (the assembly not shown). Each mobile unit thus carries N tools, either shearing or forming, in principle equidistant.

Reference is now made to FIGS. 4A to 4C.

OC shear tools are positioned so that their cutting points are at the desired distance I from the horizontal plane passing through the axis of the tube TC.

The attack of the shearing tool OC produces the beginning of chips CC (FIG. 4B), which detach towards the outside after removal of the tool, insofar as the cutting angle of the latter is suitably selected.

The result of this first operation is visible in FIG. 4C. A pre-slit is obtained, the width dl of which is substantially equal to that of the final slit intended to accommodate the flat tube (by lower values).

The second operation is carried out with a forming tool, which preferably has the form illustrated in FIGS. 6A and 6B (although a tool of the form illustrated in FIGS. 7A and 7B can also be envisaged).

The forming tool OF of FIGS. 6 comprises a leading edge provided with two bevelled faces OF11 and OF12. In front view, this leading edge consists of two segments OF21 and OF22 forming between them an acute angle. These segments are connected to an intermediate portion OF30 of substantially rectangular cross section. An OF40 shoulder is provided, the shape of which is chosen to establish a chamfer of the tube, as will be seen below, after which the OF50 tool body is found.

Reference is now made to FIGS. 8A to 8F. The forming tool enters each pre-slot, in a direction substantially perpendicular to that which was used for the action of the shearing tool.

FIG. 8A illustrates the forming tool before it enters the slot. In the position of Figure 8B, the forming tool has advanced.

As the terminal end of the OF21 and OF22 segments enters the tube, the slot is brought to its final size and end shape. After that, the OF40 shoulder (Figure 8C) will slightly flare the ends of the slots, and if desired, slightly round the upper edge of the slot.

In its movement to go inside this slot, the forming tool OF splits the material from the end or edge of the pre-slot, to the size of the desired slot. This material is pushed back and laminated by the tool towards the inside of the tube so that it is perpendicular to the walls of the final slot, creating burrs.
B10 and B11 on one side of the slot, as well as B12 and B13 on the other side.

This can be obtained by providing that the forming tools have a thickness substantially equal (by greater values) to that of the shearing tools, and a width substantially equal to that desired for the slot, therefore substantially equal (by greater values) to that shear tools.

The Applicant has observed that these internal burrs are not detachable, that they individually have a substantially continuous profile, and that they extend, by their short sides, over approximately 1 mm. In some cases, it is even possible to obtain a single continuous burr, instead of the two burrs B10 and B11.

The comparison of FIGS. 8D and 8E shows the passage from the pre-slit to the final slit, and in particular the passage from the slit length from dl to d2.

FIGS. 9A to 9D show the final shape of a slit, the cutting planes being taken with reference to FIGS. 2A and 2B.

FIG. 9A shows that the length D2 of the slot is broken down into two equal parts D20 and D21 relative to the axis of symmetry of the tube.

At its ends, the slot is flared, as indicated by the angles b of FIG. 9A.

The detail D illustrated in FIG. 9B shows the relationship between the slot height h and the length 1 of the aforementioned flared area, as well as the connection radius R1 between them.

FIGS. 9C and 9D respectively show the slot obtained in a part of the collecting tube, as well as the shape of the burrs B10 and B11.

Widening the ends of the slots by the forming tool also produces material repulsion, which results in an extension of the internal burrs, as well as the appearance of a slight bead at the ends of the slot. This double action is particularly suitable for fixing flat ends of straight cut tubes, insofar as they partially compensate for the roundness of the collecting tube.

Of course, the present invention is not limited to the embodiment described.

For example, instead of the slots being of orientation strictly perpendicular to the axis of the tube, they can easily be made with a slight obliquity with respect to the latter.

Although in many heat exchangers for vehicles, the fluid used is water, it is possible to use the exchanger according to the present invention with various other advantageous fluids, liquid and / or gaseous.

Furthermore, although the invention is particularly advantageous with flat tubes coated in advance with a brazing composition, it is conceivable to fix these flat tubes on the collecting tube by equivalent means.

Finally, the present invention is not limited to the subject of the description, with regard to the general shape of the tubes, in particular of the collecting tube, which is not necessarily round, nor as to the shape of the flat tubes. , which can be flat only at their ends, or even the particular shape given to shearing and forming tools, which can be replaced by equivalent tools, insofar as they provide non-detachable oblique internal burrs having sufficient continuity.

Claims (10)

 a3) the insertion into the slots (FA) of a plurality of forming tools capable of producing non-detachable internal burrs (B10-B13), and in that in step c) the fixing of the tubes transfer (TT) to the collecting tube (TC) takes place at least in part on said shaped burrs.  a2) cutting slots (FA) by passing a plurality of shearing tools (OC), and  al) the joining of a collecting tube (TC) on a support,  CLAIMS 1. Method for manufacturing a heat exchanger for a vehicle, in which: a) transverse slots (F1-FN) are machined in at least one fluid collecting tube (TC), b) the slots are inserted ends of flat transfer tubes (TT1-TT8), and c) the assembly is heated, to fix the transfer tubes in a sealed manner on the collecting tube, characterized in that step a) comprises: 2. Method according to claim 1, characterized in that step a) further comprises:  a4) repeating steps a1 to a3) for a second collecting tube (TC2), in that step b) is carried out by inserting the opposite ends of the transfer tubes into the slots of the two collecting tubes (TC1, TC2 ), respectively, and and in that in step c) the transfer tubes (TT) are fixed simultaneously on the two collecting tubes (TC1, TC2). 3. Method according to one of claims 1 and 2, characterized in that step a2) comprises cutting pre-slots (FA) located in the positions of the slots, using a plurality of tools shear, driven in translation, these pre-slits having substantially the desired width for the slits, but lengths slightly less than that of the final slits, and in that in step a3), the forming tools have a thickness substantially equal to those of the shearing tools, and a length substantially equal to that desired for the slot, which gives the slots (FB) their final shape, while producing burrs. 4. Method according to one of claims 1 to 3, characterized in that the cutting angle of the shearing tools (OC) is less than about 45, so that the sheared chips (CC) are pushed back to the outside of the tube. 5. Method according to one of claims 1 to 4, characterized in that the forming tools (OF) have a leading edge with double bevel. 6. Method according to claim 5, characterized in that the forming tools (OF) have a leading edge in two symmetrical segments forming an acute angle. 7. Method according to one of claims 5 and 6, characterized in that the leading edge of the forming tools (OF) is followed by a peripheral shoulder allowing the production of a chamfer facilitating the introduction of the end of a transfer tube in a slot. 8. Method according to one of the preceding claims, characterized in that the forming tools (OF) produce at the end of the slots a bead outward. 9. Method according to one of the preceding claims, characterized in that step b) also comprises the insertion of heat exchange inserts (IE) between the flat transfer tubes, while fixing the step c) at the same time connects the heat exchange spacers (IE) to the transfer tubes. 10. Vehicle heat exchanger, of the type comprising at least one fluid collecting tube (TC1), fitted with transverse slots F1..FN), in which the ends of flat transfer tubes are fixed (in particular by brazing) TT), characterized in that these ends of flat tubes (TT) are at least partly fixed on internal burrs formed from said slots.