Method for producing a plate heat exchanger using two welds, and a corresponding plate heat exchanger

Abstract

A method for producing a plate heat exchanger and the plate heat exchanger, particularly a soldered aluminium plate heat exchanger. In the method, a heat exchanger block is provided having a plurality of partition plates and edge strips arranged between the partition plates. A connection device is provided to be mounted on the heat exchanger block. A planar region for securing the connection device to the heat exchanger block is provided with at least one welded weld bead by means of a first weld. The connection device is welded onto the weld bead by means of a second weld. The welding method used for the first weld is a friction stir welding method.

Claims

1. A method for producing a plate heat exchanger, said method comprising in which: providing a heat exchanger block comprising a number of parting sheets and edge bars arranged in between, providing a connection device to be attached to the heat exchanger block, providing at least one welding bead by means of a first welding on a planar region intended for fixing the connection device to the heat exchanger block, and welding the connection device onto the welding bead by means of a second welding, wherein the first welding is formed by friction stir welding and said first welding is performed only to the extent sufficient to remove brazing inhomogeneities down to a depth of 5 mm.

2. The method for producing a plate heat exchanger as claimed in claim 1, wherein unevennesses of the planar region intended for fixing the connection device to the heat exchanger block are at least partially evened out by the first welding.

3. The method for producing a plate heat exchanger as claimed in claim 1, wherein the plate heat exchanger is an aluminum plate heat exchanger.

4. The method for producing a plate heat exchanger as claimed in claim 1, wherein the welding bead produced by the first welding has a silicon content and/or magnesium content of greater than 1.5% or less than 0.5%.

5. The method for producing a plate heat exchanger as claimed in claim 1, wherein the welding bead produced by the first welding has a silicon content of greater than 1.5% or less than 0.5%.

6. The method for producing a plate heat exchanger as claimed in claim 1, wherein the welding bead produced by the first welding has a magnesium content of greater than 1.5% or less than 0.5%.

7. The method for producing a plate heat exchanger as claimed in claim 1, wherein the welding bead has a welding filler.

8. The method for producing a plate heat exchanger as claimed in claim 1, wherein the plate heat exchanger is a brazed plate heat exchanger.

9. The method for producing a plate heat exchanger as claimed in claim 1, wherein the second welding is a fillet weld.

10. The method for producing a plate heat exchanger as claimed in claim 1, wherein the width of the welding bead is 2 to 3 times the wall thickness of the connection device in the region to be welded on.

Description

(1) The invention is explained below on the basis of the exemplary embodiments represented in the accompanying drawings, in which

(2) FIG. 1 shows a conventional plate heat exchanger,

(3) FIG. 2 shows an enlarged, perspective view of an upper region of a heat exchanger block.

(4) The structural design of a conventional plate heat exchanger has already been discussed when presenting the prior art with reference to FIG. 1.

(5) The distributor fins 2, the passages 3 for conducting the process streams A, B, C, D, E, the parting sheets 4 and an outer sheet 5 can also be seen in the heat exchanger block 1 that is represented in FIG. 2. Arranged on the connection devices 7, which are also referred to as headers, are means for supplying and discharging 6 the process streams A, B, C, D, E as nozzles 6. The edge bars 8 that are arranged between individual parting sheets 4 and are also referred to as side bars can also be seen.

(6) In particular because of unavoidable production tolerances and/or brazing-induced heat distortion, gaps 9 may occur between parting sheets 4 and edge bars 8. Moreover, brazing solder that is present between the edge bars 8 and the parting sheets 4 may have certain inhomogeneities. It also cannot be ruled out that the outer surfaces of the parting sheets 4 and of the edge bars 8 have unevennesses. These gaps, inhomogeneities and unevennesses may lead to leaks, in particular in the case of automated welding on of the connection devices 7 onto the heat exchanger block 1.

(7) It is therefore provided according to the invention that the surface of the heat exchanger block 1 in a planar region 10 that is intended for fixing the connection device 7 to the heat exchanger block 1 is provided by means of a welding bead 12 produced in a first welding 11. With this welding bead 12, the planar region 10 is made more uniform and brazing inhomogeneities that may be present there are eliminated. This first welding 11 is carried out by means of friction stir welding, the pin-shaped welding tool 20 that is represented, while undergoing constant rotation about its longitudinal axis, being moved on the translational path 21 indicated by the arrows through the heat exchanger block 1, and consequently through the parting sheets 4 arranged parallel to one another and edge bars 8. The frictional heat thereby generated has the effect that the material of the parting sheets 4 and of the edge bars 8 becomes doughy, and a welded connection is produced between these heat exchanger elements. However, in this case the welded materials are preferably not heated in such a way that a possibly existing critical silicon or magnesium concentration of 0.5% to 1.5% in the welding seam region could lead to the risk of crack formation.

(8) Once the welding bead has been applied, a second welding 13 is used to produce a welding seam 14, with which the connection device 7 is welded onto the welding bead 12, and consequently onto the heat exchanger block 1, as indicated in FIG. 2 at the edge of the connection device 7 already arranged on the heat exchanger block 1.

LIST OF REFERENCE NUMERALS

(9) TABLE-US-00001 1 Heat exchanger block 2 Distributor fin 3 Passage 4 Parting sheet 5 Outer sheet 6 Means for supplying and discharging 7 Connection device 8 Edge bar A, B, C, D, E Process stream 9 Gap 10 Planar region 11 First welding 12 Welding bead 13 Second welding 14 Welding seam 20 Welding tool 21 Translational path