METHOD FOR PRODUCING A HEAT EXCHANGER

Abstract

The invention relates to a method for producing a heat exchanger (1) having tubes (2), which are each received at the longitudinal end side in an associated header (3), wherein the tubes (2) and the headers (3) are formed out of aluminium and are soldered to one another and, in a state soldered to one another, form a coolant-conducting channel structure (4).

Here it is substantial for the invention that the heat exchanger (1), following the soldering of the tubes (2) to the headers (3), is cold-formed and the strength thereby increased.

By way of this, the weight and the costs can be reduced and the performance and the strength increased.

Claims

1. A method for producing a heat exchanger (1) having tubes (2), which are each received at the longitudinal end side in an associated header (3), wherein the tubes (2) and the headers (3) are formed out of aluminium and are soldered to one another and in a soldered-together state form a coolant-conducting channel structure (4), characterised, in that the heat exchanger (1) following the soldering of the tubes (2) to the headers (3) is cold-formed and the strength thereby increased.

2. The method according to claim 1, characterised, in that the heat exchanger (1) following the soldering of the tubes (2) to the headers (3) is stretched, i.e. elongated by approximately 0.1% to 10%.

3. The method according to any one of the preceding claims, characterised, in that the heat exchanger (1) following the soldering of the tubes (2) to the headers (3) is stretched, i.e. elongated by approximately 1% to 3%.

4. The method according to any one of the preceding claims, characterised, in that the heat exchanger (1) following the soldering of the tubes (2) to the headers (3) defines an x-y-plane and is stretched, i.e. elongated, in the x-direction and/or in the y-direction.

5. The method according to any one of the preceding claims, characterised, in that the heat exchanger (1) following the soldering of the tubes (2) to the headers (3) is hammered, rolled, stamped or pressurised.

6. The method according to any one of the preceding claims, characterised, in that the heat exchanger (1), following the soldering of the tubes (2) to the headers (3) and prior to the stretching, is cooled with a cooling rate of typically 15-100 K/min, in particular 40-100 K/min, in a temperature range 570-200° C.

7. The method according to any one of the preceding claims, characterised, in that the tubes (2) are formed as flat tubes.

8. The method according to any one of the preceding claims, characterised, in that between the individual tubes (2) heat exchanger elements (5), for example corrugated fins, are provided, which, together with the tubes (2) and the headers (3), are soldered and subsequently stretched.

9. A heat exchanger (1), produced according to the method in accordance with any one of the preceding claims.

Description

[0013] Further important features and advantages of the invention are obtained from the subclaims, from the drawings and from the associated figure description by way of the drawings.

[0014] It is to be understood that the features mentioned above and still to be explained in the following cannot only be used in the respective combination stated but also in other combinations or by themselves without leaving the scope of the present invention.

[0015] Preferred exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description, wherein same reference numbers relate to same or similar or functionally same components.

[0016] It shows, in each case schematically,

[0017] FIG. 1 a possible sequence of a method according to the invention for producing a heat exchanger,

[0018] FIG. 2 a view of a heat exchanger according to the invention produced in accordance with a method according to the invention.

[0019] According to FIG. 1, tubes 2 and two headers 3 are initially provided in a method according to the invention for producing a heat exchanger 1 (see also FIG. 2). This can take place for example in the method step A. Following this, the tubes 2 are each inserted at the longitudinal end side into openings (passages) of the headers 3, wherein both the tubes 2 and also the headers 3 are formed out of aluminium. The tubes 2 and the headers 3 are soldered to one another and, in an interconnected state, form a coolant-conducting channel structure 4. This can take place for example in the method step B. Following the establishment of the soldered connection, the heat exchanger 1 is cold-formed in the method step C, as a result of which the strength of the heat exchanger 1 is increased. Following the cold-forming, the heat exchanger 1 is completed in the method step D.

[0020] Here, the tubes 2 can be designed as flat tubes and be produced for example by the extrusion moulding method.

[0021] By the cold-forming in the method step C, the strength of the aluminium can be significantly increased as a result of which the heat exchanger 1 is sturdier and need no longer be handled so carefully in a further production or assembly step. Through the higher strength by way of the cold-forming an increased pressure stability can be additionally achieved, as a result of which the use of reduced wall thicknesses both of the tubes 2 and also of the headers 3 is possible. By way of this, resources, costs and weight can be saved.

[0022] The cold-forming can take place for example by a stretching, so that the heat exchanger 1 following the soldering of the tubes 2 to the headers 3 is stretched, i.e. elongated by approximately 0.1% to 10%. Preferentially, an elongation here amounts to approximately 1% to 3%.

[0023] According to FIG. 2 such a stretching process is shown, wherein in this case suitable forces F act on all four sides or edges of the heat exchanger 1 and bring about the stretching of the heat exchanger 1 and thus the strength increase of the same.

[0024] Viewing FIG. 2 further it is noticeable that the heat exchanger 1, after the soldering of the tubes 2 to the headers 3, defines an x-y-plane and a stretching takes place in the x-direction and/or in the y-direction. A stretching transversely to the x-y-plane, i.e. perpendicularly to the image plane, is not provided.

[0025] A cold-forming of the heat exchanger 1 after the establishment of the soldered connection between the tubes 2 and the headers 3 can additionally or alternatively to the stretching also take place by a hammering, rolling, high-pressure internal forming or stamping. Merely a transforming of the crystal structure, increasing the strength of the heat exchanger 1 is important here.

[0026] Between the individual tubes 2, heat exchanger elements 5, for example corrugated fins, can be additionally provided, which, together with the tubes 2 and the headers 3, are soldered together and subsequently stretched.

[0027] Practically, after the soldering of the tubes 2 to the headers 3 and still prior to the cold-forming, i.e. for example prior to the stretching, the heat exchanger 1 is cooled with a cooling rate of at least 15 K/min, in particular at least 40 K/min, preferentially 40 to 100 K/min in the temperature range 570-200° C. Through the subsequent cold-forming, the heat exchanger 1, after the soldered connection has been established, can be cooled more rapidly as a result of which an improved hardening and thus likewise a strength increase can be achieved. Through the increased strength, not only can the lifespan of the heat exchanger 1 be increased but, with the same required strength, a wall thickness of the tubes 2 and/or of the headers 3 can also be reduced so that compared with previous heat exchangers a reduction of the wall thickness by 20-50% is possible. During the cold-forming, for example during the stretching, a strength increase, depending on the aluminium alloy, of up to 100% can materialise, so that in this case a reduction of the wall thickness by 50% would be conceivable.

[0028] With the method according to the invention, a heat exchanger 1 according to the invention, for example for an electric vehicle, can thus be created which can be produced more rapidly, with lower weight, with same strength or higher strength with same weight.