JPS62142998A - Method of permanently fixing at least each one penetrating void partially consisting of at least thermoplastic plastic into at least one opening of support plate including at least one rod and heat exchanger - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial field of application: The invention relates to the use of at least one rod at least partially made of thermoplastic, each having at least one through cavity at its ends. , in at least one opening of the support plate, in particular for the manufacture of a heat exchanger, with all the rods being provided for the purpose of the fixation relative to the rods of the support plate. in which the cavities of all rods have a hydraulic diameter corresponding to at least 10 times the thinnest wall thickness of the rod, and the walls of the rods have voids filling up to 20% of the wall volume. and the support plate is made of thermoplastic at least in the opening. The invention also relates to a heat exchanger that can be manufactured by this method.

BACKGROUND OF THE INVENTION A method and a heat exchanger according to the above concept are known from DE 33 38 157 A1. In this known method, the tube is introduced into a tubular base configured as a perforated base. This tube end is then
Welded together with the tubular bottom by an ultrasonic head. A sonotrode (5onotrode) suitable as an ultrasonic head
ode) is extremely expensive to produce. In the case of the known method, all the tube ends have to be individually welded together with the tube bottom, which is extremely expensive and requires a large number of tubes for all desired tube arrangements and/or tube numbers. requires a sonotrode originally manufactured for that purpose. When welding the tube ends individually together with the tubular bottom, in addition the individual already welded tube ends are partially melted again when welding the adjacent tube ends due to the action of heat. I can do it. The outer contour of the nnotrode can be chosen to be conical. If a sonotrode of this type is used for welding tube ends and tubular bottoms, all tube ends have a conical widening towards the end at the tubular bottom of the finished heat exchanger. This widening makes the supply and removal of the medium flowing in the heat exchanger advantageous. This widening provides a slight pressure reduction when the fluidizing medium enters the tube, which is not necessarily desirable, for example, if a heat exchanger manufactured by this method has to be used as an evaporator. That's not the point. The heat exchanger manufactured by the known method has an annular bulge on the front face of the tubular bottom which is bulging at all tubular outlet ends. Furthermore, a clear demarcation line between the tubing material and the tubular bottom material is visible when looking at the front surface of the tubular bottom material.

Problem to be solved by the invention: The object of the invention is, in particular, to produce a heat exchanger that does not require more expensive tools and that can be carried out independently of the desired arrangement of the rods. The object of the present invention is to provide a particularly simple method of the type described above, which is possible. Furthermore, it is an object of the invention to provide a particularly inexpensive heat exchanger. Preferably, the support plate material and the rod material should seamlessly transition into each other. That is, the visible boundary between the support plate material and the bar material is no longer visible at all.

Also provided is a heat exchanger suitable for use as an evaporator.

Means for solving the problem: According to the invention, the problem posed is that, in the method of the above concept, the rod, together with the support plate, is arranged such that the ends of the rod are directed upwards in an essentially vertical direction. and applying heat to the rod end from above to such an extent that the rod end is at least partially softened; The problem is solved by enlarging the outer wall of the rod end in such a way that it contacts and adheres to the wall of the support plate opening. In this case, this support plate is
At least in the opening, the rod used must be made of a material to which it can be glued when using the method of the invention.

That is, if the rods are arranged mostly vertically,
It has been found that when the thermoplastic rod material reaches a slurry state, the upper end of the rod expands upward. This condition is fully exploited in the case of the method according to the invention. The rod end expands due to heat radiation and then contacts the inside of the opening in the support plate and is bonded thereto upon further application of heat. The heat can be supplied, as already mentioned, by thermal radiation, for example by means of a heating plate. However, the C1 heat can also be supplied by ultrasound, light, electromagnetic waves, hot gas, etc. In special cases, the heat treatment can be carried out under vacuum or under a protective gas atmosphere.

The amount of heat required to carry out the method of the invention can be determined by a simple test. Generally, the heat treatment is carried out maintaining the following conditions: where Q is the amount of heat supplied per unit surface M (front surface') per hour in t/m2s, and e is the amount of heat supplied per unit surface M (front surface') in t/m2s. is the linear expansion coefficient of the rod material at K, and t is sec
where ζ is the density of the rod material in kFl/m', cp is the specific heat of the rod material in J/kgK, λ is J/msK
is the thermal conductivity of the rod material at .

The degree of enlargement of the rod end is most advantageously between 100.10 and 400.0 in the range between room temperature and melting temperature.
It is regulated by using a rod made of thermoplastic with an average coefficient of linear expansion of 10 l/K.

Particularly advantageously, if the support plate is made of thermoplastic at least in the opening, the rod end is supplied with such heat as to melt the rod end together with the support plate. Introducing the rod into an opening provided in the support plate ensures that the opening is larger in cross-sectional dimension than the corresponding outer cross-sectional dimension of the rod by at least a factor of 20 of the wall thickness of the rod. Simplified by using plates. It has also been found that in this way the strength of the connection between the rod and the support plate can be adjusted particularly advantageously.

The method according to the invention is characterized in that the hydraulic diameter of all cavities is between 0.3 and 15, which can have a porosity of up to 10% of the wall volume.
between 0.5 and 75 mm, and the wall thickness at the thinnest point is between 5 and 25% of the hydraulic diameter, especially between 7.5 and 17.5 mm of the hydraulic diameter. It can be advantageous if bars between % are used. As is well known, the hydraulic diameter (dh) is defined as the quotient of the area of the inner cross-section of four times the passage of the rod divided by the moist inner circumference (for this, Dubbe I ,
“Tatsusienpoofufufyourdenmachinenhow(
Taschenbuch fjjr denfVIas
13th edition, 1970
．． (See page 314, paragraph 4) Advantageously, a support plate is used whose opening cross-section area is increased at least towards the front side compared to the outer cross-section of the rod or rods used. .

In this case, the rod is positioned such that the rod end reaches at least into the widening of the support plate opening. The manner in which the cross section is widened or widened towards the front side of the support plate influences the inner profile of the bar obtained by heat treatment.

If the cross-section of the opening in the support plate is constantly enlarged towards the front, the inner cross-section of the bar will be approximately 10 to 60 inches in area of the inner cross-section in the direction of the interior of the bar and further inward. It has a narrow portion that transitions to the inner cross section of the rod. If the cross-section of the support plate opening widens dramatically towards the front, the inner surface of the rod end has no narrowing of the inner cross-section at all or almost no narrowing of the inner cross-section. It has a narrow area where it cannot be used.

Before heat treating the rod, the end of the rod should be 1 to 2 mm from the front of the support plate.
A protruding position in the opening of the support plate has proven to be particularly advantageous.

The possibility of retaining the joint position between the rod and the support plate is such that after the positioning of the rod but before the heat treatment of the rod, at least the intermediate space that may exist between the jacket of the rod and the opening of the support plate is reduced. Partial filling with polymer powder can have an advantageous effect. Preferably, a polymer powder is used which has a melting temperature that is also about 5-50°C lower than that of the rod material, especially 20-50°C lower.

Polymer powders with an average particle size of 20 to 100μ, in particular 40 to 100μ, are advantageously used.

Particle sizes larger than l○0μ often result in undesirable non-uniform surfaces.

The process according to the invention provides that the support plate, the rod and optionally the polymer powder consist of a thermoplastic polymer, which thermoplastic polymers belong to the same polymer species and/or are identical or almost identical in their basic structure. They almost always have the same melting point or melting range.

The heat exchanger produced by the method of the invention exhibits a series of characteristics on the basis of which it is distinguished from heat exchangers produced hitherto. For example, a heat exchanger is disclosed in West German Patent Application Publication No. 333.
8157, the front side of the support plate or the front side of the tubular bottom remains smooth, and the support plate material and the rod material do not swell on the front side of the support plate. They are not clearly visible and distinguishable from each other only because of the ovoid ridge, and the inner surface of the rod end shows the footprint of the contact sonotrode used. The front surface of the heat exchanger produced by the method of the invention exhibits the typical appearance of a thermoplastic material solidified from the melt, which appearance is compared with the surface of a crepe rubber sole (sole). Can: This front surface gives the impression of being slightly honeycombed.

Furthermore, in the cross-sectional view of the plates and tubes in the case of a heat exchanger obtained by the method according to the invention, no transition between the support plate material and the bar material can any longer be discerned. The surface of the support plate material also exhibits the gloss typical of thermoplastic resins solidified from a melt known to manufacturers.

According to the invention, the task therefore consists of a plurality of thermoplastic rods each having at least one through cavity, the ends of which are permanently connected to at least one support plate. , in which case this cavity widens towards the end of the thermoplastic rod and is also solved by the heat exchanger obtainable by the method of the invention.

In general, the heat exchanger according to the invention also exhibits that all rod ends are fused together with the support plate, viewed from the front of the support plate, to a depth at least corresponding to the thinnest wall thickness of the rod.

As already mentioned above, the heat exchanger according to the invention generally exhibits that the rod material is fused together with the support plate material in such a way that there is always a transition between these two materials.

The rods of the heat exchanger may be constructed as tubes with one or more through cavities, the hydraulic diameter of which (individual cavities) ranges from 0.5 to 15 mm. Between the reeds and the wall thickness of this tube is between 5 and 25% of the hydraulic diameter at its thinnest point. The heat exchanger according to the invention can also include a rod consisting of tubes arranged in groups.

Although this tube group outwardly exhibits the shape of a plate, i.e. when the tubes are parallel to each other parallel to the axis and the axis is arranged in a straight line, this tube group may be a profiled plate or a spiral. It can also take the form of a shaped board. In the case of a spiral plate,
A group of tubes exists in parallel, in which case this axis is (
(above) are arranged on a spiral line. Such a tube bank can consist of 2 to 100000 tubes, in particular 2 to 20,000 tubes.

When the heat exchanger according to the invention is used as an evaporator, the heat exchanger according to the invention has a narrowing section in the direction of the interior of the rod when all the internal cross sections of the rod ends widen. The area of this cross section is about 10 of the area of the inner cross section.
~60%, in which case this narrowing transitions further inwardly onto the rod inner cross-section. Such a heat exchanger is
Any widening of the inner cross section of the rod end narrows in the direction of the rod interior before it transitions to the rod inner cross section to a cross section that is approximately 10-60% of the area of the inner cross section. Indicates that the The area of the narrowed cross section preferably has an area of about 20 to 5% of the area of the inner cross section.

The heat exchanger according to the invention can consist at least partially of a thermoplastic polymer belonging to the fluoropolymers group. However, this heat exchanger may also consist at least partially of polyethylene or of polypropylene.

An advantage of the method according to the invention is that the joining position, in particular between the rod and the support plate, is obtained without the application of mechanical forces, so that at the end of the rod there are no traces of the rams used for example to apply the forces. The reason is that it does not have any. This is because tools of this type are not necessary for carrying out the method according to the invention. The pressing force of the rod against the support plate opening wall, which is necessary for carrying out the method of the invention, is produced only by the enlargement of the rod end obtained by the heat treatment.

Furthermore, the cross-section of the heat source depends exclusively on the outer diameter of the support plate and is therefore independent of what kind, arrangement and number of rods are used, as long as the cross-section of the heat source is sufficiently dimensioned. The same heat source can be used for The method of the invention is carried out without contact, so there is no need to glue the heat exchanger to the heat source. The front side of the support plate, when using the method according to the invention, does not have the hair-like surface typical when using contact bodies.

The term "heat exchanger" includes within the scope of the invention mass exchangers for gases and mufflers for gas or liquid jets.

Example: Next, the present invention will be explained in detail with reference to examples.

The properties of the plastics used in the following examples are listed in the table.

Example 1 PVDF whose outer dimensions are 101 x 5 C, 1 l x 15 x
The plate from type I (see table) is provided with 28 penetrating slits arranged perpendicular to the surface (10111 x 50'), each of length 10 mm and width 2 ffl B. There is. The slits are arranged parallel to each other and have a dimension of 5°? It runs parallel to the width side with IIB. The slit widens over the entire surface from the lower l sn of the rear front surface to the front surface, the contour opposite this widening encompassing an angle of 60°. Thereby approximately 41,211+1X on the front face of every slit 3. ) IIB is found to have an aperture.

Into all the slits rods from PVDF type I, each 1 m long, 40 mm wide and 2 mm thick, are introduced. All rods are provided with 20 through cavities with a hydraulic diameter of 1.6111 m, in this case the center distance between two adjacent through cavities &Z 2 Im. The thinnest wall thickness between the cavity and the outer surface of the rod is 0.21111. The rod is positioned 5 such that the end of the rod protrudes 1.5 ++n from the front surface of the plate, the rod itself is arranged vertically, and the enlargement of the slit and thus the front surface is directed upwards.

Furthermore, a flat heating plate with a surface area of 50 cm x 50 cm, with an emission rate of 0.9 and a temperature of 4300 C,
It is directed at the PVDF board for 2 minutes at a distance of 1 mm from the front surface and then removed again.

Considering the front side, it can be seen that all the rods are now curved outwards and are touching the enlarged part of the slit. If the end of such a rod is cut parallel to the axis, it can be seen that in the enlarged part of the rod this rod is partially melted together with the walls of the slit in the plate over a length of 1.5 strands. It can be confirmed.

Example 2 The same plate and the same rod as in Example 1 are used, but in this case the rod is 39. '5 rnaO width. Once again in the slit of the board, this rod is introduced and positioned so that it protrudes about 1.5 blades from the front side of the board. Furthermore, the draft gap formed by the outer wall of the rod and the wall of the enlarged part of the slit partially has an average grain size of 0.0
Filled with 6 wings of PVDF-powder, type I. Example 1
After the heat treatment described in , the powder melts. In a section parallel to the longitudinal axis of the rod, it can be seen that the rod was uniformly fused to a depth of 1.5 mm together with the surface of the slit.

Example 3 A cylindrical plate with a diameter of 150 am and a thickness 7 of 3Q11 m is made of PVDF type ■. This plate has 1440 through holes 7 with a diameter of 2 mm. Plate diameter 150
On one surface with an audience, on the front, all the holes have been enlarged dramatically. This dramatic expansion has a diameter of 3 and a depth of 0.8. 2 in all holes
A tube with an outer diameter of 0.15 mm and a wall thickness of 0.15 mm is introduced and positioned such that the end of the tube protrudes 1.5 wings from the front surface. Pipe materials (・Engineering P V 1.)
It is F type I.

This tube is oriented vertically, so the front side of the plate is
An upward direction 7 is shown. On the plate and on the slits formed by the tubes and enlargements, a polymer powder of type I with an average particle size of 0.06 mm is sprinkled, after which the heating plate described in Example 1 is heated over a distance of 1 wet. with the front facing upward. The temperature of this heating plate is 430°C. After 2 minutes, the hot plate is removed again. Thereafter, the plate, together with the tubes fixedly connected thereto, is cooled to room temperature.

Example Cow Repeat Example 3. However, in this case a plate is used whose widening is conically configured.

The larger diameter of the conical enlargement touching the front surface of the plate is 3
1ri11, and the apex angle of the conical expansion part is 85
°. After heat treatment, all tubes are provided with an annular narrowing in the plate at the location where there is a transition between cylindrical hole and conical widening.

Example 5 The production described in Example 1 of the heat exchanger can be carried out under the same processing conditions when using polypropylene (PP) according to the above table as material for the plates and rods.

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows that in a tubular bottom (support plate) 2, a tube is formed on the top surface by the method of the invention so that the tube end actually protrudes about 1.5 mm above the front surface (top surface) with a conical enlargement. 1 is a schematic diagram showing a cross section of a heat exchanger in which a (rod) 1 is introduced; FIG. The end of the tube 1 and the cavity formed by the conical enlargement are already filled with polymer powder 5.

The heat exchanger thus prepared is already suitable for carrying out the method according to the invention with the casing 3 in such a way that the ends of the tubes are arranged vertically upwards and the support plates are arranged essentially horizontally. It is provided below the heating plate 6 which provides heat release. After a sufficiently long action time of heat release, the tube end was fixedly connected to the tubular bottom. The location of the connection between the tube and the tubular bottom is shown in FIG. The end of the tube 1 (
The tube end in this tubular bottom has a conical widening 7 towards the end and this conical widening 7
It has a narrow part 8 which is annularly swollen toward the smallest cross section.

The end of the tube 1 is firmly glued to the tubular base 2 in the area of a conical widening 7 and an annularly concave narrowing 8 .

The conical enlargement of the front surface can be simply obtained by recessing the hole in the tubular bottom. The connection between the tube and the tubular bottom is particularly strong if the tubular bottom also consists of a thermoplastic material, in particular of the same thermoplastic material as the tube. The separation shown in FIG. 2 between the tube end and the tubular bottom is such that the opening of the tubular bottom 2 is made of thermoplastic material and that the tube end 7 is
If such heat is supplied that the and tubular bottom 2 are melted, the melting process can no longer be seen with the naked eye.

FIG. 3 is a perspective view showing that the flat rod end 9 is arranged in the support plate 10. In this case, all the rods 9 are machined and have six openings 11 passing through them. The rod end 9 is positioned in the support plate 10 in such a way that it projects from the support plate 10 at the front. The opening (not visible) in the support plate 10 has an enlargement 12 towards the front, which is configured in such a way that it is elongated and has the shape of a truncated cone. There is.

FIG. 4 shows a flat rod 13 having an arcuate profile with a circular end.
FIG. 4 is a further perspective view showing that it is expected to be arranged in a correspondingly formed support plate 14; The rod 13 also has a number of openings 15 passing through it. For the heat treatment apparatus shown in FIG. 4, a heating rod 16 is particularly suitable, which is brought into the position shown in the country of birth for the heat treatment.

As shown in FIG.
It can also be configured so that it is extended by This kind of support board? In use, a particularly rigid connection is obtained between the rod end and the support plate. This also applies to the embodiment shown in FIG. 6 of the openings in the support plate 19. In this case, the support plate 19 has an enlargement 20 towards the front, which may exhibit a circular shape in the case of a round rod or a truncated cone shape in the case of a flat rod. . Additionally, a web 21 is arranged on the enlarged part 20, which ensures a particularly tight and firm fusion with the rod end.

The web 21 expands together with the tube end during the heat treatment, so that the web 21 abuts the expansion 20. After the heat treatment, the web 21 is melted together with the support plate 19 and the tube end is bath-fused together with the web 21.

FIGS. 7 to 13 exemplarily show embodiments in which the opening of the support plate is expected to expand toward the front.

In the case of FIG. 7, the rod end 24 is inserted into the support plate 23.
4 is introduced so as to protrude from the front surface of the support plate 23. The opening in the support plate (not shown) has a continuous enlargement 22 . In the case of a round rod 24, the arrangement of FIG. 2 is obtained after heat treatment.

In the case of FIGS. 8, 10, 11 and 12, the openings 27 in the support plates 26, 32, 35 and 38,
33. Dramatic expansion of 36 or 39 25, 31.
34 to 37 are shown, and FIGS. 9 and 13
In the case shown, 1'lX, opening 3 in support plate 29 or 42
0 to 44 continuous enlargements 28 to 41 are shown. In the case of FIG. 13, the female end 43 is connected to the support plate 42.
, but does not protrude from the front surface of the support plate 42 .

[Brief explanation of drawings]

FIG. 1 is a schematic representation of a heat exchanger prepared for heat treatment, with the heating plates already positioned; FIG. 2 is a sectional view showing the connection position between the tube and the tubular bottom; FIG. 3 is a perspective view showing a flat bar end with a number of through openings placed in the support plate before heat treatment; FIG. FIG. 5 is a perspective view further illustrating the anticipated arrangement of the bars; FIG. 5 is a perspective view illustrating the anticipated configuration 7 of the support plate; FIG. 6 is a schematic diagram illustrating one embodiment of the openings in the support plate;
and FIGS. 7, 8, 9, 10, 11, 12 and 13 are schematic drawings showing the outline of various possible enlargements of the opening in the support plate, respectively. . 1... Pipe, 2... Tubular bottom, 3... Casing,
5... Polymer powder, 6... Heating plate, 7... Conical enlarged part, 8... Annularly swollen narrow part, 9,43
...rod end, 10.14-. 17, 19, 23, 26
゜29.32, 35, 38.40.4-2... Support plate, 11.15, 27.30, 3.3.36, 39゜ + Cow... Penetrating opening, 12.20, 22 .25°28.
31.34, 37.41... Enlarged part, 13... Bar,
16...Heating rod, 18.21...Web, 24...
・Round stick.

Claims (1)

Claims: 1. At least one of the supporting plates, comprising at least one rod, the ends of which are at least partially made of thermoplastic, each having at least one through cavity; permanent fixing in one opening, in particular for the production of heat exchangers, in which case all the rods are located in openings provided for the rods of the support plate for their fixing, in this case All bar cavities have a hydraulic diameter corresponding to at least 10% of the smallest external cross-sectional dimension of the bar, and the walls of the bar may have voids filling up to 20% of the wall volume. , the rod is positioned with the support plate such that the ends of the rod are oriented essentially vertically upwardly and the support plate is oriented essentially horizontally, and then Heat is applied to the rod end to such an extent that the rod end is at least partially softened and the outer wall of the rod end is brought into contact with and adheres to the wall of the support plate opening. at least one at least one through-hole, each consisting of at least one thermoplastic, characterized in that it is enlarged to
A method for permanently securing the ends of two rods into at least one opening in a support plate containing at least one rod. 2. 100 x 10^- within the range between room temperature and melting temperature
2. The method according to claim 1, wherein a rod made of a thermoplastic having an average linear expansion coefficient of ^6 to 400 x 10^-^6 l/k is used. 3. The support plate is made of thermoplastic at least at the opening, and the rod end is supplied with heat to such an extent that the rod end melts together with the support plate. The method described in Section 2. 4. Heat treatment under the following conditions: 0.0175<Qe(t/(ζc_pλ))^1^/^
2<0.5 [where, Q is the amount of heat supplied per unit area (front surface) per hour in J/m^2s, e is the linear expansion coefficient of the rod material in l/K, and t is sec. is the time of thermal action at , ζ is the density of the bar material in kg/m^3, and c_p is J
/kgK is the specific heat of the rod material, and λ is the thermal conductivity of the rod material in J/msK. The method described in section. 5. The hydraulic diameter of all cavities is between 0.3 and 15 mm, and the wall thickness at the thinnest point is the hydraulic diameter, which can have a porosity of up to 10% of the wall volume. 5~
Claim 1, in which a bar between 25% and 25% is used.
The method described in any one of paragraphs to paragraphs 4 to 4. 6. The method according to claim 5, wherein the hydraulic diameter of the cavity is between 0.5 and 7.5 mm. 7. The wall thickness at the thinnest point is 7.5 to 1 of the hydraulic diameter.
Claims 5 or 6 between 7.5%
The method described in section. 8. Using a support plate whose opening cross-sectional area is enlarged at least towards the front compared to the outer cross-section of the rod or group of rods used, the rod end being at least in the enlarged area of the support plate opening. 8. A method according to any one of claims 1 to 7, wherein the method is positioned so as to reach inside. 9. Before heat treating the rod, the end of the rod should be 1 to 2 m from the front of the support plate.
9. The method according to claim 1, wherein the support plate is protruded into the opening of the support plate. 10. After positioning of the rod but before heat treatment of the rod, any intermediate space that may exist between the jacket of the rod and the opening of the support plate is at least partially filled with polymer powder. The method according to item 8 or 9. 11. Any one of claims 1 to 10, wherein the support plate, the rod, and optionally the polymer powder are made of polymers having the same or almost the same melting point or melting range. The method described in Section 1. 12. Using a polymer powder having a melting temperature about 5 to 50°C lower than the melting temperature of the rod material, claim 1
The method according to item 0 or item 11. 13. The method of claim 12, wherein a polymer powder having a melting temperature of about 20-50°C lower than the melting temperature of the rod material is used. 14. Process according to any one of claims 10 to 13, using a polymer powder having an average particle size of 20 to 100 μ. 15. The method of claim 14, wherein a polymer powder having an average particle size of 15,40 to 100 microns is used. 16. Any one of claims 1 to 15, wherein the support plate, the rod, and in some cases the polymer powder are composed of thermoplastic polymers whose basic structure belongs to the same polymer species. The method described in section. 17. permanently inserting the ends of at least one rod, each having at least one through-hole, at least partially of thermoplastic, into at least one opening of the support plate containing the at least one rod; , in which case all the rods are located in openings provided for the rods of the support plate for their fixation, in which case the spaces in all the rods are at least as large as the smallest external cross-sectional dimension of the rods. 10%, and the walls of the rods can have voids filling up to 20% of the wall volume, in each case at least one through hole. consisting of a plurality of thermoplastic rods having cavities, the ends of which are permanently connected to at least one support plate, the cavities widening towards the ends of the thermoplastic rods; A heat exchanger characterized by: 18. The heat exchanger according to claim 17, wherein all rod ends together with the support plate are melted from the front side of the support plate to a depth at least corresponding to the thinnest wall thickness of the rod. 19. Heat exchanger according to claim 17 or 18, in which the bar material is fused together with the support plate material in such a way that there is always a transition between these two materials. 20. Heat exchanger according to any one of claims 17 to 19, wherein the rods are constructed as tubes. 21. Heat exchanger according to any one of claims 17 to 19, characterized in that the tubes arranged in groups are included as rods. 22. Heat exchanger according to claim 21, wherein the tube group is formed from tubes located in parallel, the axes of which are arranged on the line of the helix (as mentioned above). 23. All tube groups consist of 2 to 100,000 tubes,
A heat exchanger according to claim 21 or 22. 24. The heat exchanger according to claim 23, wherein each tube group consists of 2 to 20,000 tubes. 25. All enlargements of the inner cross-section of the rod end have a cross-section in the direction of the interior of the rod that is about 10-60% of the area of the inner cross-section before it transitions to the inner cross-section of the rod. A heat exchanger according to any one of claims 17 to 24, which is reduced. 26. The heat exchanger of claim 25, wherein the area of the reduced cross-section is about 20-50% of the area of the inner cross-section. 27. Heat exchanger according to any one of claims 17 to 26, consisting of a thermoplastic polymer at least partially belonging to the fluoropolymers group. 28. A heat exchanger according to any one of claims 17 to 26, consisting at least partially of polyethylene. 29. A heat exchanger according to any one of claims 17 to 26, consisting at least partially of polypropylene.