EP3876669B1 - Method for manufacturing an electric heating device and electric heating device - Google Patents

Description

Electric tubular heaters are a variant of electric heating devices that has been known for many years. They are characterized by the fact that the electric heating element is arranged within a tubular metal casing, whereby it is electrically insulated in the radial direction to the tubular metal casing by embedding it in an electrically insulating but highly heat-conducting material, in many cases e.g. magnesium oxide, boron nitride or Al2O3, each in the form of a powder or granulate or also a porous molded body, in particular made of one of these materials, in order to avoid an undesirable short circuit. Furthermore, the electric heating device is compressed in many cases.

In many applications of electric tubular heaters, it is desirable for the electric tubular heater to have an unheated area on at least one of its ends. In order to provide this, it is known to establish the connection to the electric heating element by means of a connecting wire and/or connecting bolt, which has a larger cross-section than the electric heating element and, for example, in the case of a connecting wire, can be introduced into the coil interior of the electric heating element or, in the case of a connecting bolt, can accommodate an end section of the electric heating element.

In addition to the larger cross-section of the connecting bolt, in many cases the heat generated in the area of the connecting bolt is reduced by choosing a material with a lower specific resistance than that of the material from which the heating element is made; for example, by using of copper or nickel as material for the connecting bolt.

However, this known procedure causes a number of problems, particularly in applications where the available installation space is limited. Firstly, the connecting wire and/or connecting bolt hinders the filling of the electrically insulating material. Secondly, the unheated area of the electrical heating device constructed in this way is much more difficult to compact because only a small proportion of the electrically insulating material is present in this section in the cross-section, so that a largely solid structure made up of the connecting wire and/or connecting bolt and a section of the electrical heating element must be compacted. This leads to enormous loads on the compaction machines and a short service life of the compaction systems and their tools.

From the US$5,864,991 a method for producing an electric heating device with the features of the preamble of claim 1 and the preamble of claim X is known. The US 5 034 595 A , the EN 20 2017 100 786 U1 , the US 2 491 688 A , the EP 3 361 573 A1 , the EN 20 2017 100 531 U1 and the DE 17 65 324 A1 disclose further electrical heating guides or electrical feedthroughs as well as methods for their production.

• die Möglichkeit zur Unterbringung eines möglichst großen Leiterquerschnitts im unbeheizten Bereich;
• eine optimale Verdichtung in allen Bereichen, die insbesondere eine unterschiedliche Querschnittsreduktion wegen unterschiedlicher poröser Anteile unterschiedlicher Bereich berücksichtigt;
• die Lösung von Füllproblemen;
• eine Kostenoptimierung durch rationelle, sehr hochgradig automatisierbare Fertigung des beheizten Bereichs;
• eine Kostenoptimierung durch automatisierbare oder weitgehend automatisierbare Fertigung unbeheizter Bereiche einer gewünschten bzw. benötigten Länge,
• die Möglichkeit, trotz für die Herstellung des beheizten Bereichs notwendigen Glühprozessen -beispielsweise wenn die elektrische Heizvorrichtung biegefähig weichgeglüht wird- Materialien für Anschlussdrähte, Anschlusshülsen oder Anschlussbolzen zu verwenden, welche Schmelzpunkte unterhalb der Glühtemperatur haben
• eine hohe Prozesssicherheit
• und/oder die Belastung von Verdichtmaschinen und ihren Werkzeugen zu reduzieren

erzielt werden. Diese Aufgabe wird gelöst durch ein Verfahren mit den Merkmalen des Patentanspruchs 1 und eine elektrische Heizvorrichtung mit den Merkmalen des Patentanspruchs 8. Vorteilhafte Weiterbildungen der Erfindung sind Gegenstand der jeweiligen abhängigen Patentansprüche.The object of the invention is therefore to provide an improved method for producing an electric heating device and an electric heating device that can be produced using such a method. Depending on the design, the invention can, in particular, individually or in (sub)combination, provide improvements with regard to

• the possibility of accommodating the largest possible conductor cross-section in the unheated area;
• optimal compaction in all areas, which in particular takes into account different cross-sectional reductions due to different porous components in different areas;
• solving filling problems;
• cost optimization through efficient, highly automated production of the heated area;
• cost optimization through automated or largely automated production of unheated areas of a desired or required length,
• the possibility of using materials for connecting wires, connecting sleeves or connecting bolts which have melting points below the annealing temperature, despite the annealing processes required to produce the heated area - for example when the electrical heating device is annealed to make it flexible
• high process reliability
• and/or reduce the load on compaction machines and their tools

This object is achieved by a method having the features of patent claim 1 and an electric heating device having the features of patent claim 8. Advantageous developments of the invention are the subject of the respective dependent patent claims.

The method according to the invention serves to produce an electrical heating device with an electrical heating element which is embedded in an electrically insulating material inside a multi-part tubular metal casing, ie is arranged in an electrically insulated manner (eg by embedding in an electrically insulating powder or granulate or by electrically insulating molded parts), wherein the electrical heating device has an unheated area within the multi-part tubular metal casing at at least one end in which, during operation of the electrical heating device, the electrical current flows at least through at least one connecting wire and/or at least one connecting sleeve and/or at least one connecting bolt which is in electrical contact with the electrical heating element.

In this case, the unheated region can preferably have an unheated transition region in which, when the electric heating device is in operation, the electric current flows simultaneously through the at least one connecting wire and/or the at least one connecting sleeve and/or the at least one connecting bolt and through a section of the electric heating element running in the unheated transition region, which section of the electric heating element is in electrical contact with the connecting wire or connecting bolt. In other words, a section of the electric heating element and at least one section of a connecting wire or a connecting sleeve or a connecting bolt are present in the unheated transition region, whereby technically speaking, these sections are not connected in series but in parallel.

Furthermore, the electric heating device to be produced by the method has a heated region within the multi-part tubular metal casing, in which, during operation of the electric heating device, the electric current flows only through a section of the electric heating element running in the heated region.

It should be noted at this point that this does not exclude the use of the multi-part tubular metal sheath as a return conductor (because according to the above-mentioned condition for the heated area of this must be located within the multi-part tubular metal casing) nor is it excluded that in the case of the electric heating device both connections are on the same side.

The fact that the tubular metal casing is made up of several parts means in particular that it is composed of several parts - preferably several pipe sections - which can, however, be firmly connected to one another, for example pressed or welded.

Furthermore, the term "unheated area" is to be interpreted in such a way that heat can nevertheless be generated in this area - which is unavoidable and therefore necessarily the case in most real embodiments - but to a significantly lesser extent than in the heated area in which the electrical heating device is intended to generate heat in order to fulfil its intended function.

According to the method according to the invention, in a first method step the heated region is produced and compacted in a first part of the multi-part tubular metal casing, in a second method step which is carried out independently of the first method step and is generally completed after this step, at least one section of the unheated region is produced in a second part of the multi-part tubular metal casing and the first part and the second part of the multi-part tubular metal casing are connected to one another. The fact that the second method step is generally carried out at least partially after the first method step is due in particular to the fact that in order to connect the first part and the second part, the first part naturally already has to be present.

The latter step may also be carried out before, during or at the same time as the compaction of the second part of the tubular metal casing, if such compaction is provided for. It does not therefore necessarily take place at the very end of the second process step or after the second process step.

By dividing the production into two process stages, whereby the first process stage delivers at least the "finished" heated area and possibly part of the unheated area as an intermediate product and the second process stage then produces the still missing unheated area with an initially separate part of the tubular metal casing and then pieces it together, the compaction processes for the individual parts of the electric heating device can be carried out in an optimized manner. In particular, the compaction of the heated area can be carried out using a piercing process.

At the same time, this measure makes it much easier to fill the electrically insulating material because there is no longer any hindrance caused by the unheated area.

The finished heated region present after the first process step can in particular correspond to an electric heating device with a tubular metal casing, in which connections of the electric heating device protruding from the front side of the tubular metal casing are formed by a section of the electric heating element, preferably with a connecting wire and/or a connecting sleeve arranged thereon, and thus form the unheated transition section in the completely finished electric heating device according to the invention.

In a preferred development of the method, in the first process step, the section of the electric heating element running in the heated region, i.e. the section that later forms the heated region, is positioned in a first part of the multi-part tubular metal casing; the electrically insulating material, e.g. as a powder or granulate or as a molded part, is introduced into this region of the first part of the multi-part tubular metal casing, so that the section of the electric heating element arranged in the first part of the multi-part tubular metal casing is insulated, i.e. embedded, by the electrically insulating material and the first part of the multi-part tubular metal casing, in particular the heated region, is compacted.

It should be noted at this point, on the one hand, that the above-mentioned process steps are advantageously carried out in this order and, on the other hand, that further process steps can be carried out before, after or between them within the framework of the first process stage.

In an advantageous development of the invention, in the second process step carried out after the first process step, at least a section of the unheated region, including at least a part of the unheated transition region, is created by introducing a part of the electrical heating element with a connecting wire arranged thereon and/or a connecting sleeve arranged thereon and/or a connecting bolt arranged thereon into a second part of the multi-part tubular metal casing, wherein further electrically insulating material is introduced into the second part of the tubular metal casing, so that the heating element formed in the second The section of the electrical heating element arranged in the tubular metal casing is electrically insulated, in particular embedded, by the electrically insulating material. Preferably, the second part of the multi-part tubular metal casing is then also compacted.

In this second process phase, too, the above-mentioned process steps can advantageously be carried out in this order and further process steps can be carried out before, after or between them within the framework of the second process phase.

According to an advantageous development of the method, in the first method step, a connecting wire is brought into an electrically conductive connection with an end section of the electrical heating element, in particular by inserting it into a coiled end section of the electrical heating element and/or a connecting sleeve is brought into an electrically conductive connection with an end section of the electrical heating element, in particular by pushing it onto a coiled end section of the electrical heating element.

In both cases described, a (typically small) part of the transition region is also present within the first part of the multi-part tubular metal jacket, which has proven to be advantageous for process reliability, especially with regard to the electrical contacting of the electrical heating element.

In an advantageous development of the method, the electric heating element is coiled in such a way that an end section of the electric heating element has a smaller coil diameter than a section of the electric Heating element which, in the finished electrical heating device, is located in the heated area and, in particular, is preferably not an end section. This measure can, in particular, help to facilitate the filling of the first part of the multi-part tubular metal casing with the electrically insulating material.

This winding of the electric heating element is preferably carried out before it is inserted into the first part of the multi-part tubular metal casing.

The filling of the first part of the multi-part tubular metal jacket with the electrically insulating material can be facilitated particularly effectively if the electrical heating element is coiled in such a way that the end section of the electrical heating element has a smaller coil diameter than the section of the electrical heating element which lies in the heated area in the finished electrical heating device, has a coil axis which is offset relative to the coil axis of the section of the electrical heating element which lies in the heated area in the finished electrical heating device.

In some cases it can also be advantageous if, in the first process step after compaction, a connection-side section of the first part of the multi-part tubular metal casing and the layer of electrically insulating material adjoining this radially inward are cut off. As already mentioned, as a consequence of the method of production according to the invention, the first part of the multi-part tubular metal casing and the second part of the multi-part tubular metal casing are subjected to different compaction processes.

By subsequently cutting off a connection-side section of the first part of the multi-part tubular metal jacket and the layer of electrically insulating material adjoining it radially inwards, a section of the transition region that is ultimately arranged in the second part of the multi-part tubular metal jacket can be pre-compacted with the compaction parameters that are applied to the first part of the multi-part tubular metal jacket and then post-compacted with the compaction parameters that are applied to the second part of the multi-part tubular metal jacket, which can have positive effects in particular on the quality of the electrical contact between the connecting wire, connecting sleeve, connecting bolt and end section of the electrical heating element. In addition, the cutting off can also help to create a more homogeneous interface or a more homogeneous transition between the electrically insulating material in the first part of the multi-part tubular metal jacket and the electrically insulating material in the second part of the multi-part tubular metal jacket.

Advantageously, in particular after a section of the electrical heating element or a connecting wire or connecting bolt has been exposed by such a cutting off, a cleaning step is carried out in which insulating material residues are removed, for example by brushing, polishing and/or ultrasonic treatment, in order to improve the quality of the electrical contact.

A further development of the method provides that the second part of the multi-part tubular metal casing with a clear cross-section that corresponds to the outer contour of the end section of the first part of the multi-part metal casing, at least after compaction in the first process step, is pushed onto this end section of the first part of the multi-part tubular metal casing and is secured there. In this way, any gap between the first and second parts of the multi-part tubular metal casing is particularly effectively avoided. In addition, a larger clear cross-section makes it easier to fill with electrically insulating material, particularly in the area with this cross-section.

In the last-described further development, it is particularly expedient if the second part of the multi-part tubular metal casing is connected to the first part of the multi-part tubular metal casing by pressing during compaction in the second process step.

According to the invention, a second compaction is provided which is carried out in such a way that the resulting axial pressing pressure creates an almost homogeneous transition region between the electrically insulating material in regions that were subjected to the first compaction and in regions that were subjected to the second compaction.

For applications where it is important that the electric heating device has a constant outer contour over its entire length, the cross-section of the second part of the multi-part tubular metal shell can be adapted to the cross-section of the first part of the multi-part tubular metal shell during compaction in the second process step.

An unheated connection area can be designed particularly effectively if, in the second process step, before the introduction of the electrically insulating material, a part of the electrical heating element with the connecting wire and/or the connecting sleeve arranged thereon is inserted from one side into the second part of the multi-part tubular metal casing and a connecting bolt with an opening for receiving this part of the electrical heating element with the connecting wire arranged thereon is inserted from the opposite side into the second part of the multi-part tubular metal casing and is pushed with the opening onto this part of the electrical heating element.

Furthermore, in many cases where high-temperature treatment was previously necessary, which in particular prevented the use of connecting wires and/or connecting bolts made of copper, the process can now be used if at least one process step is carried out in which the intermediate product on which this process step is carried out is subjected to thermal stress and if at least the process step in which the highest thermal stress occurs is carried out before the start of the second process step.

The electrically insulating material that is introduced into the second part of the multi-part tubular metal casing can also be introduced as a molded part. It can also be useful to impregnate the electrically insulating material there in particular.

However, it is also possible to obtain the second part of the multi-part tubular metal casing by using rod material from a bushing that has an electrically connected Outer tube made of metal with an insulated inner conductor, is provided in a desired length. This makes it possible to freely adapt the length of the unheated sections required to the respective application in a simple and cost-effective manner and can contribute to a particularly cost-effective, fully automated production of these unheated sections.

In particular, an inner conductor of this feedthrough, but also another inner conductor of a differently designed second part can be machined on the side facing the first part of the tubular metal casing, provided with an annular groove or drilled in order to provide the electrical contact to the inner conductor of the first part of the tubular metal casing, i.e. the electrical heating element, directly or via its connecting wires, which can then be inserted into the hole and press-contacted - for example by means of a hexagonal press. However, threads can also be introduced into such a hole and a connecting wire or connecting bolt of the first part of the tubular metal casing.

In order to establish contact with an electrical supply line, a section facing this connection can be cut off on the side of the second part of the tubular metal jacket facing away from the first part of the tubular metal jacket, together with the layer of electrically insulating material adjoining this section of the second part of the tubular metal jacket radially inwardly.

Advantageously, a cleaning step is also carried out here afterwards, in which insulating material residues, for example, by brushing, polishing and/or ultrasonic treatment to improve the quality of the electrical contact.

Alternatively, an inner conductor of the second part of the tubular metal sheath, which is surrounded by the tubular metal sheath, can be drilled on the side facing the first part of the tubular metal sheath in order to insert an electrical contact for connecting the supply line into the hole and to be press-contacted - for example by means of a hexagonal press.

The connection between the first part of the tubular metal sheath and the second part of the tubular metal sheath can be made by welding or soldering.

However, it is more advantageous, on the one hand because this avoids any influence on the welding or soldering process by insulating material, in particular MgO, and on the other hand if the penetration of moisture is to be prevented as effectively as possible, if a ring is pushed onto the transition area between the first part and the second part of the tubular metal jacket when making this connection and this is then welded or soldered on both sides.

Another variant for producing this connection provides that the end sections of the first part of the tubular metal casing and the second part of the tubular metal casing are each machined so that they overlap each other with a precise fit and are then welded or soldered together. If the end section of the first or second part of the tubular metal casing, which is weakened from the outside, is longer than the end section of the second or first part of the tubular metal jacket which overlaps it, it can also be achieved that a weld or solder seam which projects beyond the outer diameter of the tubular metal jacket is avoided.

The electric heating device according to the invention can be produced in particular by a method according to one of claims 1 to 8, but does not necessarily have to be produced by such a method.

• an mindestens einem Ende einen unbeheizten Bereich auf, in dem bei Betrieb der elektrischen Heizvorrichtung der elektrische Strom zumindest auch durch mindestens einen Anschlussdraht und/oder mindestens eine Anschlusshülse und/oder mindestens einen Anschlussbolzen fließt, wobei der mindestens eine Anschlussdraht und/oder die mindestens eine Anschlusshülse und/oder der mindestens eine Anschlussbolzen in elektrischem Kontakt mit dem elektrischen Heizelement steht, und
• einen beheizten Bereich auf, in dem bei Betrieb der elektrischen Heizvorrichtung der elektrische Strom lediglich durch einen in dem beheizten Bereich verlaufenden Abschnitt des elektrischen Heizelements fließt, wobei der beheizte Bereich im ersten Teil des mehrteiligen rohrförmigen Metallmantels angeordnet ist und der unbeheizte Bereich im zweiten Teil des mehrteiligen rohrförmigen Metallmantels angeordnet ist.

It comprises in particular an electrical heating element which is arranged in an electrically insulated, in particular embedded, manner inside a multi-part tubular metal casing which has a first part and a second part in an electrically insulating material. The electrical heating device has within the multi-part tubular metal casing

• at least one end has an unheated area in which, when the electric heating device is in operation, the electric current flows at least through at least one connecting wire and/or at least one connecting sleeve and/or at least one connecting bolt, wherein the at least one connecting wire and/or the at least one connecting sleeve and/or the at least one connecting bolt is in electrical contact with the electric heating element, and
• a heated region in which, when the electric heating device is in operation, the electric current flows only through a section of the electric heating element running in the heated region, wherein the heated region is arranged in the first part of the multi-part tubular metal casing and the unheated area is arranged in the second part of the multi-part tubular metal casing.

By dividing the tubular metal casing into several parts, the compaction processes for the individual parts of the electric heating device can be carried out in an optimized manner. At the same time, this measure makes filling each part with the electrically insulating material much easier.

Preferably, a part of the unheated region is formed by an unheated transition region in which, during operation of the electrical heating device, the electrical current flows simultaneously both through the at least one connecting wire and/or connecting bolt and through a section of the electrical heating element running in the unheated transition region, which section is in electrical contact with the connecting wire and/or connecting bolt.

According to a preferred development, a connecting wire is in an electrically conductive connection with an end section of the electrical heating element, which can in particular be introduced into a coiled end section of the electrical heating element.

Alternatively or additionally, a metal sleeve can serve as a connection sleeve in an electrically conductive connection with an end section of the electrical heating element and can be applied to a coiled end section of the electrical heating element (12, 12', 12") in particular by pushing, soldering or welding the connection sleeve.

In both cases described, a (typically small) part of the transition area may also be present within the first part of the multi-part tubular metal jacket, which has proven to be advantageous for process reliability, particularly with regard to the electrical contacting of the electrical heating element. However, the transition area must necessarily extend into the second part of the multi-part tubular metal jacket.

Filling with the electrically insulating material can be simplified by coiling the electrical heating element in such a way that an end section of the electrical heating element has a smaller coil diameter than a section of the electrical heating element which lies in the heated area in the finished electrical heating device.

This effect is particularly strong if the electric heating element is coiled in such a way that the end section of the electric heating element, which has a smaller coil diameter than the section of the electric heating element which lies in the heated area in the finished electric heating device, has a coil axis which is offset relative to the coil axis of the section of the electric heating element which lies in the heated area in the finished electric heating device.

The tightness of the multi-part tubular metal casing is enhanced if the second part of the multi-part tubular metal casing with a clear cross-section which can accommodate the outer contour of the end section of the first part of the multi-part metal casing facing it, at least after compaction in the first process step, is placed on this end section of the first part of the multi-part tubular metal casing and is fixed there.

The cross-section of the second part of the multi-part tubular metal casing can be adapted to the cross-section of the first part of the multi-part tubular metal casing by compaction in the second process step.

A particularly effective design of the unheated area provides that a part of the electric heating element with the connecting wire and/or the connecting sleeve arranged thereon is inserted from one side into the second part of the multi-part tubular metal casing and a connecting bolt with an opening for receiving this part of the electric heating element with the connecting wire and/or the connecting sleeve arranged thereon on the part of the electric heating element is inserted from the opposite side into the second part of the multi-part tubular metal casing and is pushed with the opening onto this part of the electric heating element.

It is particularly preferred if the second part of the multi-part tubular metal casing is formed from rod material of a feedthrough which has an inner conductor that is electrically insulated from an outer metal tube. This makes it possible to freely adapt the length of the unheated sections that are required in each case to the respective application in a simple and cost-effective manner and can contribute to a particularly cost-effective, fully automated production of these unheated sections.

In particular, an inner conductor of this bushing, but also another inner conductor of a second part can be on the The side facing the first part of the tubular metal casing can be machined, provided with an annular groove or drilled in order to provide electrical contact to the inner conductor of the first part of the tubular metal casing, i.e. the electrical heating element, directly or via its connecting wires, which are then inserted into the hole and press-contacted, for example by means of a hexagonal press. However, threads can also be introduced into such a hole and a connecting wire or connecting bolt of the first part of the tubular metal casing.

In order to establish contact with an electrical supply line, a section facing this connection can be cut out on the side of the second part of the tubular metal jacket facing away from the first part of the tubular metal jacket, together with the layer of electrically insulating material adjoining this section of the second part of the tubular metal jacket radially inwardly.

Alternatively, an inner conductor of the second part of the tubular metal sheath, which is surrounded by the tubular metal sheath, can be drilled on the side facing the first part of the tubular metal sheath and provided with an electrical contact inserted into the hole and pressed in for connecting the supply line.

The connection between the first part of the tubular metal sheath and the second part of the tubular metal sheath can be made by welding or soldering.

However, it is more advantageous, on the one hand because this avoids any influence on the welding or soldering process by insulating material, in particular MgO, and on the other hand also if the penetration of moisture is to be prevented as effectively as possible, if a ring is pushed onto the transition area between the first part and the second part of the tubular metal jacket and is welded or soldered on both sides.

Another variant for producing this connection provides that the end sections of the first part of the tubular metal casing and the second part of the tubular metal casing are each machined so that they overlap each other with a precise fit and are then welded or soldered together. If the end section of the first or second part of the tubular metal casing that is weakened from the outside is longer than the end section of the second or first part of the tubular metal casing that overlaps it, it is also possible to avoid a weld or solder seam that protrudes beyond the outer diameter of the tubular metal casing.

Fig. 1a:

eine Ansicht einer Hälfte eines Ausführungsbeispiels einer elektrischen Heizvorrichtung,

Fig. 1b:

einen Längsschnitt durch die Darstellung der Figur 1a,

Fig. 1c:

eine erste Detailvergrößerung aus Figur 1b,

Fig. 1d:

eine zweite Detailvergrößerung aus Figur 1b,

Fig. 2:

einen Abschnitt eines ersten Zwischenstadiums bei der Durchführung eines ersten Verfahrens zur Herstellung einer elektrischen Heizvorrichtung,

Fig. 3:

einen Abschnitt eines zweiten Zwischenstadiums bei der Durchführung des ersten Verfahrens zur Herstellung einer elektrischen Heizvorrichtung,

Fig. 4:

einen Abschnitt eines dritten Zwischenstadiums bei der Durchführung des ersten Verfahrens zur Herstellung einer elektrischen Heizvorrichtung,

Fig. 5:

einen Abschnitt eines vierten Zwischenstadiums bei der Durchführung des ersten Verfahrens zur Herstellung einer elektrischen Heizvorrichtung, das das nach dem ersten Verfahrensabschnitt erhaltene Zwischenprodukt zeigt,

Fig. 6:

einen Abschnitt eines fünften Zwischenstadiums bei der Durchführung des ersten Verfahrens zur Herstellung einer elektrischen Heizvorrichtung,

Fig. 7a:

eine erste Gestaltung eines Endabschnitts des elektrischen Heizelements,

Fig. 7b:

eine zweite Gestaltung eines Endabschnitts des elektrischen Heizelements,

Fig. 7c:

eine dritte Gestaltung eines Endabschnitts des elektrischen Heizelements,

Fig. 8a:

eine erste Gestaltung eines unbeheizten Übergangsbereichs,

Fig. 8b:

eine zweite Gestaltung eines unbeheizten Übergangsbereichs,

Fig. 8c:

eine dritte Gestaltung eines unbeheizten Übergangsbereichs.

Fig. 9a:

eine Ansicht eines Abschnitts eines zweiten Ausführungsbeispiels einer elektrischen Heizvorrichtung vor dem Zusammenfügen des ersten und des zweiten Teils des rohrförmigen Metallmantels,

Fig. 9b:

einen Längsschnitt durch die Darstellung der Figur 9a,

Fig. 9c:

eine Ansicht des Längsschnitts aus Figur 9b nach dem Zusammenfügen des ersten und des zweiten Teils des rohrförmigen Metallmantels,

Fig. 9d:

eine Ansicht des Längsschnitts aus Figur 9c nach einem lokalen Verpressen,

Fig. 9e:

eine Ausschnittsvergrößerung aus Figur 9c,

Fig. 9f:

eine Ausschnittsvergrößerung aus Figur 9d,

Fig. 10a:

eine erste Variante des Ausführungsbeispiels aus Figur 9a-f vor dem Zusammenfügen des ersten und des zweiten Teils des rohrförmigen Metallmantels,

Fig. 10b:

die erste Variante des Ausführungsbeispiels gemäß Figur 10a nach dem Zusammenfügen des ersten und des zweiten Teils des rohrförmigen Metallmantels,

Fig. 11:

eine zweite Variante des Ausführungsbeispiels aus Figur 9a-f nach dem Zusammenfügen des ersten und des zweiten Teils des rohrförmigen Metallmantels,

Fig. 12:

eine dritte Variante des Ausführungsbeispiels aus Figur 9a-f nach dem Zusammenfügen des ersten und des zweiten Teils des rohrförmigen Metallmantels,

Fig. 13a:

einen Längsschnitt durch einen Abschnitt eines dritten Ausführungsbeispiels einer elektrischen Heizvorrichtung vor dem Zusammenfügen des ersten und des zweiten Teils des rohrförmigen Metallmantels,

Fig.13b:

eine Ansicht des Längsschnitts aus Figur 13a nach dem Zusammenfügen des ersten und des zweiten Teils des rohrförmigen Metallmantels,

Fig.13c:

eine Ansicht des Längsschnitts aus Figur 13b nach einem lokalen Verpressen,

Fig. 14:

einen Abschnitt eines ersten Zwischenstadiums bei der Durchführung eines zweiten Verfahrens zur Herstellung einer elektrischen Heizvorrichtung,

Fig. 15a:

einen Abschnitt eines zweiten Zwischenstadiums bei der Durchführung des zweiten Verfahrens zur Herstellung einer elektrischen Heizvorrichtung in einer ersten Variante,

Fig. 15b:

den Abschnitt aus Fig. 15a in einer zweiten Variante,

Fig. 16:

einen Abschnitt eines dritten Zwischenstadiums bei der Durchführung des zweiten Verfahrens zur Herstellung einer elektrischen Heizvorrichtung in der ersten Variante,

Fig. 17a:

einen Abschnitt eines vierten Zwischenstadiums bei der Durchführung des zweiten Verfahrens zur Herstellung einer elektrischen Heizvorrichtung in der ersten Variante,

Fig. 17b:

den Abschnitt aus Fig. 17a in der zweiten Variante,

Fig. 18:

einen Abschnitt eines ersten Zwischenstadiums bei der Durchführung eines dritten Verfahrens zur Herstellung einer elektrischen Heizvorrichtung,

Fig. 19:

einen Abschnitt eines zweiten Zwischenstadiums bei der Durchführung des dritten Verfahrens zur Herstellung einer elektrischen Heizvorrichtung,

Fig. 20:

einen Abschnitt eines dritten Zwischenstadiums bei der Durchführung des dritten Verfahrens zur Herstellung einer elektrischen Heizvorrichtung, und

Fig. 21:

einen Abschnitt eines vierten Zwischenstadiums bei der Durchführung des dritten Verfahrens zur Herstellung einer elektrischen Heizvorrichtung.

The invention is explained in more detail below with reference to figures which show exemplary embodiments. It shows:

Fig. 1a:

a view of one half of an embodiment of an electric heating device,

Fig. 1b:

a longitudinal section through the representation of the Figure 1a ,

Fig. 1c:

a first detailed enlargement from Figure 1b ,

Fig. 1d:

a second detail enlargement from Figure 1b ,

Fig. 2:

a section of a first intermediate stage in carrying out a first method for producing an electric heating device,

Fig. 3:

a section of a second intermediate stage in carrying out the first method for producing an electric heating device,

Fig.4:

a section of a third intermediate stage in carrying out the first method for producing an electric heating device,

Fig.5:

a section of a fourth intermediate stage in carrying out the first process for producing an electric heating device, showing the intermediate product obtained after the first process stage,

Fig.6:

a section of a fifth intermediate stage in carrying out the first method for producing an electric heating device,

Fig. 7a:

a first configuration of an end portion of the electric heating element,

Fig. 7b:

a second configuration of an end portion of the electric heating element,

Fig. 7c:

a third design of an end portion of the electric heating element,

Fig. 8a:

a first design of an unheated transition area,

Fig. 8b:

a second design of an unheated transition area,

Fig. 8c:

a third design of an unheated transition area.

Fig. 9a:

a view of a portion of a second embodiment of an electric heating device before joining the first and second parts of the tubular metal casing,

Fig. 9b:

a longitudinal section through the representation of the Figure 9a ,

Fig. 9c:

a view of the longitudinal section Figure 9b after joining the first and second parts of the tubular metal casing,

Fig. 9d:

a view of the longitudinal section Figure 9c after local grouting,

Fig. 9e:

a detail enlargement from Figure 9c ,

Fig. 9f:

a detail enlargement from Figure 9d ,

Fig. 10a:

a first variant of the embodiment from Figure 9a-f before joining the first and second parts of the tubular metal casing,

Fig. 10b:

the first variant of the embodiment according to Figure 10a after joining the first and second parts of the tubular metal casing,

Fig. 11:

a second variant of the embodiment from Figure 9a-f after joining the first and second parts of the tubular metal casing,

Fig. 12:

a third variant of the embodiment from Figure 9a-f after joining the first and second parts of the tubular metal casing,

Fig. 13a:

a longitudinal section through a portion of a third embodiment of an electric heating device before joining the first and second parts of the tubular metal casing,

Fig.13b:

a view of the longitudinal section Figure 13a after joining the first and second parts of the tubular metal casing,

Fig.13c:

a view of the longitudinal section Figure 13b after local grouting,

Fig. 14:

a section of a first intermediate stage in carrying out a second method for producing an electric heating device,

Fig. 15a:

a section of a second intermediate stage in carrying out the second method for producing an electric heating device in a first variant,

Fig. 15b:

the section from Fig. 15a in a second variant,

Fig. 16:

a section of a third intermediate stage in carrying out the second method for producing an electric heating device in the first variant,

Fig. 17a:

a section of a fourth intermediate stage in carrying out the second method for producing an electric heating device in the first variant,

Fig. 17b:

the section from Fig. 17a in the second variant,

Fig. 18:

a section of a first intermediate stage in carrying out a third method for producing an electric heating device,

Fig. 19:

a section of a second intermediate stage in carrying out the third method for producing an electric heating device,

Fig. 20:

a portion of a third intermediate stage in carrying out the third method for producing an electric heating device, and

Fig. 21:

a portion of a fourth intermediate stage in carrying out the third method for producing an electric heating device.

Figure 1a shows one half of an embodiment of an electric heating device 10, the second half of which is symmetrical to the first half and Figure 1b a longitudinal section of this half, which is however slightly offset from the central plane. The electric heating device 10 has a multi-part tubular metal casing 11 with a first part 11.1 of the multi-part tubular metal casing 11 and a second part 11.2 of the multi-part tubular metal casing 11, which has a larger clear cross-section than the first part 11.1 of the multi-part tubular metal casing, overlaps it in sections and is connected to it, as can be seen in particular from the detailed representation of the Figure 1d clarified.

Inside the first part 11.1 of the multi-part tubular metal casing 11 there is the heated area B, which is formed by the section of an electrical heating element 12, in which only this is traversed by the electrical current during operation. An electrically insulating material 16, shown here as transparent, ensures the electrical insulation from the multi-part tubular metal casing 11.

Inside the second part 11.2 of the multi-part tubular metal casing 11, an unheated area U is present at the end, which includes an unheated transition area Ü1. The unheated transition area Ü1 is formed by a section 12.1 of the electric heating element 12, which is coiled more tightly than the electric heating element 12 in the heated area, into which a connecting wire 13 is inserted and onto which a connecting sleeve 14 is pushed, which in turn is received in an opening 15.1 of a connecting bolt 15, the solid end section of which is in the unheated area U. This structure is, for example, the synopsis of the Figures 1a and 1c easy to remove. How to remove the Figures 8a to 8c However, not only the configuration described above with connecting wire and connecting sleeve shown in Figure 8c can be used, but also optionally the connecting wire 13 can be used, as shown in Figure 8b shown, or the connection sleeve 14, as in Figure 8a shown, can be omitted. Accordingly, in the unheated region U, when the electrical heating device 10 is operating, the electrical current flows at least through at least one connecting wire 13, a connecting sleeve 14 and/or a connecting bolt 15, which is in electrical contact with the electrical heating element 12, and the unheated region U also has an unheated transition region Ü1, in which, when the electrical heating device 10 is operating, the electrical current simultaneously flows both through the at least one connecting wire 13, the at least one connecting sleeve 14 and/or the at least one connecting bolt 15 and through a section 12.1 of the electrical heating element 12 running in the unheated transition region Ü1, which section is in electrical contact with the connecting wire 13 and/or connecting bolt and has a smaller coil diameter. The unheated transition region extends into the first part 11.1 of the multi-part tubular metal casing 11.

Also inside the second part 11.2 of the multi-part tubular metal casing 11, a transparent electrically insulating material 17 is arranged, which ensures the insulation of the multi-part tubular metal casing 11. A plug 18 closes the front of the second part 11.2 of the multi-part tubular metal casing 11. The first part 11.1 of the multi-part tubular metal casing 11 with the components of the electric heating device 10 arranged therein and the second part 11.2 of the multi-part tubular In this example, the metal casing 11 with the components of the electric heating device 11 arranged therein are each compacted, but in different ways, in particular to different degrees, preferably with a weaker compaction of the second part 11.2 of the multi-part tubular metal casing 11. However, the invention also covers embodiments in which the second part 11.2 of the multi-part tubular metal casing 11 with the components arranged therein is no longer compacted.

A method for producing such an electric heating device is now described, with individual intermediate stages in the Figures 2 to 6 are shown.

First, as in Figure 2 shown, a coiled electrical heating element 12 is provided, which in this embodiment has a coiled end section 12.1 with a smaller coil diameter, into which a connecting wire 13, e.g. made of Cu or Ni, is inserted and which in the Figure 7a is shown again in cross section.

Other variants of electric heating elements 12' or 12" can be found in the Figures 7b and 7c which illustrate in particular that the electric heating element 12' does not necessarily have to taper at the end or that the electric heating element 12" has an end section 12.1" which has a smaller spiral diameter and is wound around a different spiral axis W2 than the spiral axis W1 around which the spirals with a larger spiral diameter are wound, which in the finished electric heating device are located in the heated region b; more precisely around a spiral axis W2 offset parallel to the spiral axis W1.

Based on the Figure 2 In the intermediate stage shown, a thin-walled, electrically conductive connection sleeve 14 is pushed onto the end section 12.1 of the electrical heating element 12, which leads to the Figure 3 shown intermediate stage.

The electrical heating element 12 prepared in this way with connecting wire 13 and connecting sleeve 14 is now inserted into the first part 11.1 of the multi-part tubular metal casing 11. Electrically insulating material 16 is sprinkled in the form of a powder or granulate and the arrangement is compacted, which leads to the intermediate stage according to Figure 4 which already represents a "finished" electric tubular heater of conventional design, in which - unlike in known tubular heaters - the connections of the electric heating device protruding from the front side of the tubular metal casing are formed by a section of the electric heating element with a connecting wire and/or a connecting sleeve arranged thereon, and thus form the unheated transition section in the completely finished electric heating device according to the invention.

Next, an end part of the first part 11.1 of the multi-part tubular metal casing 11 is cut off together with the electrically insulating material 16. The reason for this is in particular that during the compression process of the first part 11.1 of the multi-part tubular metal casing 11, higher pressures can be used, which leads to a desirable intimate press contact of the pressed section 12.1 of the electrical heating element 12 with the connecting wire 13 and the connecting sleeve 14. Accordingly, it may be useful to initially carry out this pressing in a longer section, provided that a sufficiently good fillability with the electrically insulating material 16 is provided. This is also the reason why the entire section 12.1 of the electrical heating element 12 is not initially simply embedded and pressed; in this case, the improvement in the fillability with the electrically insulating material 16 would be largely negated.

To move from the intermediate stage of Figure 5 to the intermediate stage of Figure 6 To access the heating element 12, the connecting bolt 15 with its opening 15.1 is pushed onto the arrangement from section 12.1 of the electrical heating element 12 with inserted connecting wire 13 and pushed-on connecting sleeve 14.

In the Figures 1a to 1d The finished electric heating device 1 shown is obtained from the intermediate stage according to Figure 6 in that the second part 11.2 of the multi-part tubular metal jacket 11 is pushed on until it overlaps with and is fastened to the first part 11.1 of the multi-part metal jacket 11 and this part is then filled with electrically insulating material 17, closed with the plug 18 and preferably suitably compacted.

The Figures 9a to 9f show different views of a section of a second embodiment of an electric heating device 100 with a multi-part tubular metal casing 101. The section not shown is constructed essentially identically.

The Figures 9a and 9b the electric heating device 100 in a first intermediate stage of its manufacture before assembling the first part 111 of the tubular metal jacket 101 and the second part 121 of the tubular metal jacket 101.

The first part 111 of the tubular metal casing 101 is here part of an electrical heating device 110 produced in a known manner, in the interior of which an electrical heating element 112 in the form of a coiled resistance wire is arranged, which is insulated from the first part 111 of the tubular metal casing 101 by electrically insulating material 116. To connect the electrical heating element 112, a connecting wire 113, which protrudes from the front of the electrical heating element 112, is inserted into the end coils of the electrical heating element 112 and, in this example, is connected to it at the welding point 114. The inserted section of the connecting wire 113 thus defines an unheated transition region Ü1, and the section of the connecting wire 113 that runs within the first part 111 of the tubular metal casing 101 forms a first part U1 of the unheated region U of the electrical heating device 100.

The second part 121 of the tubular metal casing 101 is part of the second part U2 of the unheated area U of the electrical heating device 100. The second part U2 of the unheated area U is made in this example from a section of a feedthrough 120, the outer metal casing of which serves as the second part 121 of the tubular metal casing 101 of the electrical heating device 100, wherein an inner conductor 122 is arranged in the interior of which is electrically insulated from the outer metal casing of the feedthrough 120 by an electrically insulating material 125. The inner conductor can preferably be made of nickel or copper. Note It should be noted that such a feedthrough can also include mineral-insulated cables.

The feedthrough 120, which in this example is made from a rod or continuous material, was cut off from this rod or continuous material to a length that corresponds to the sum of the desired length of the second part U2 of the unheated area and the desired length A of a connection of the electrical heating device 100. Furthermore, a bore 123 was made in the end face of the inner conductor 122 facing the first part 111 of the tubular metal jacket 101 to accommodate the section of the connecting wire 113 that projects beyond the end face of the first part 111 of the tubular metal jacket, and on the opposite side, to form the connection of length A, the outer metal jacket of the feedthrough 120 and the electrically insulating material 125 were cut off over this length and the surface of the inner conductor 122 was preferably cleaned, e.g. by brushing, polishing or ultrasound. The order in which these steps are carried out is not important.

Figure 9c shows a view of the longitudinal section Figure 9b after joining the first part 111 and the second part 121 of the tubular metal casing 101. The first part 111 and the second part 121 of the tubular metal casing 101 were positioned against each other at the end and welded or soldered at the connection point 131.

Preferably, the electric heating device 100 as shown in Figure 9c shown, a further processing step is carried out, the result of which is Figure 9d and Figure 9f becomes clear: further compaction, which is also known as local grouting or re-compaction, in the region of the second part 121 of the tubular metal casing, preferably in the region in which the bore 123 with the section of the connecting wire 113 arranged therein is located, but at a distance from the connection point 131. This processing step can be carried out in concrete terms, for example, as a hexagonal compaction, in particular by hammering, and has two advantages:
The first advantage is that the electrical contact between the connecting wire 113 and the inner conductor 122 is improved by a press contact.

The second advantage, which is particularly noticeable when comparing the detail enlargements of the Figures 9e and 9f with each other is that the resulting axial pressing pressure creates an almost homogeneous transition region between the electrically insulating material 115 and the electrically insulating material 125 and in particular fills cavities 132 and breakouts on the joined end faces.

In a first variant of the electric heating device 100, which is shown in the Figures 10a and 10b As shown, the only difference is that the connecting wire 113 has a thread 113a and the bore 123 has a counter thread 123a cut into it. Accordingly, a connection is made by screwing in before the first part 111 of the tubular metal jacket 101 and the second part 121 of the tubular metal jacket 101 are welded or soldered together. The entire other structure is identical, which is why identical reference numerals are used.

In a second variant of the electric heating device 100, which is shown in the Figure 11 is the only difference to the one shown in Figure 9c shown representation that the end region 111a of the first part 111 of the tubular metal jacket 101 is weakened on its side facing the second part 121 of the tubular metal jacket 101 by material-removing machining on its outside, while the end region 121a of the second part 121 of the tubular metal jacket 101 is weakened on its side facing the first part 111 of the tubular metal jacket 101 by material-removing machining on its inside, so that a section of the end regions 111a and 121a overlap each other. This leads to improved protection against the penetration of moisture.

Furthermore, the end region 111a is longer than the end region 121a, which means that the weld or solder seam that fixes the connection is arranged in a recess and does not increase the diameter of the electric heating device. The entire other structure is identical, which is why identical reference numerals are used.

In a third variant of the electric heating device 100, which is shown in the Figure 12 is the only difference to the one shown in Figure 9d shown representation that the connection between the first part 111 of the tubular metal jacket 101 and the second part 121 of the tubular metal jacket 101 by sliding on a ring 133 and welding or soldering the ring 133 at its one edge to the second part 121 of the tubular metal jacket 101 and at its other edge to the first part 121 of the tubular metal jacket 101. This also leads to improved protection against the penetration of moisture.

The Figures 13a to 13c each show a longitudinal section through a portion of a third embodiment of an electric heating device 200, wherein the Figure 13 a shows the state before joining the first and second parts of the tubular metal casing, the Figure 13b shows the state after joining the first and second parts of the tubular metal casing and Fig.13c after a further local compaction step, e.g. hammering into a hexagon shape.

As with the electric heating device 100, the first part 211 of the tubular metal casing 201 is part of an electric heating device 210 produced in a known manner, with an electric heating element 212 arranged in the interior in the form of a coiled resistance wire, which is insulated from the first part 211 of the tubular metal casing 201 by electrically insulating material 216. To connect the electric heating element 212, a connecting wire 213, which protrudes from the front of the electric heating element 212, is inserted into the end coils of the electric heating element 212 and, in this example, is connected to it at the welding point 214. The inserted section of the connecting wire 213 thus defines an unheated transition region Ü1, and the section of the connecting wire 213 which runs within the first part 211 of the tubular metal jacket 201 forms a first part U1 of the unheated region U of the electrical heating device 200.

The second part 221 of the tubular metal casing 201 is part of the second part U2 of the unheated area U of the electric heating device 200. The second part U2 of the unheated area U is also in this example made of a section a feedthrough 220, the outer metal casing of which serves as the second part 221 of the tubular metal casing 201 of the electric heating device 200, wherein an inner conductor 222 is arranged in the interior of which is electrically insulated from the outer metal casing of the feedthrough by an electrically insulating material 225. The inner conductor can preferably be made of nickel or copper.

The feedthrough 220, which in this example is also made of a rod or continuous material, was here, however, unlike the electric heating device 100, cut off from this rod or continuous material over a length that corresponds to the desired length of the second part U2 of the unheated area. Furthermore, in the electric heating device 200, holes 223, 224 were made in both end faces of the inner conductor 222, into which on one end face the section of the connecting wire 213 projecting beyond the end face of the first part 211 of the tubular metal jacket 201 is made and on the opposite side serves to form the connection 226, which is simply inserted into the hole and, as in Figure 13c shown, is press-contacted and fixed by a pressing or compaction step. The order in which these steps are carried out is not important.

Figure 13b shows a view of the longitudinal section Figure 13a after joining the first part 211 and the second part 221 of the tubular metal casing 201. The first part 211 and the second part 221 of the tubular metal casing 201 were positioned against each other at the end and welded or soldered at the connection point 231.

Preferably, the electric heating device 200 as shown in Figure 13b shown, a further processing step is carried out, the result of which is Figure 13c becomes clear: a further compaction, which can also be referred to as local pressing or re-compaction, in the region of the second part 221 of the tubular metal casing, preferably in the region in which the bore 223 with the section of the connecting wire 213 arranged therein is located, but at a distance from the connection point 231. This processing step can be carried out specifically, for example, as a hexagonal compaction, in particular by hammering, and brings with it the advantages already discussed above.

The Figures 14 to 17 show different intermediate stages in carrying out another method for producing an electric heating device 300.

The electric heating device 300 differs fundamentally from the previously discussed electric heating devices 10, 100 and 200 in that here the first part 311 of the tubular metal casing 301 has no first unheated section U1 and in particular no unheated transition section Ü1. In its interior, it therefore only forms the heated area over its entire length with an electric heating element 312 formed here by a coiled resistance wire and electrically insulating material 315.

With this design, it is possible to freely choose the length of the heated area by providing the coiled heating element with electrically insulating material and tubular metal casing as a rod material and cutting a piece of it with a length that corresponds to the length of the desired heated area. plus the length of the unheated transition sections and then the tubular metal casing and the surrounding electrically insulating material are cut off at the end on the length corresponding to the respective unheated transition sections with a tool 350, so that a part of the coiled electrical heating element used to form the unheated transition area Ü1 protrudes at the front, as shown in Figure 14 is shown.

As in Figure 15a As can be seen, a connecting wire 313 and a feedthrough 320, the metal sheath of which forms the second part of the tubular metal sheath of the electric heating device 300, with inner conductor 322, bore 323 and electrically insulating material 325 are then provided, which can be manufactured as explained above in connection with the electric heating devices 100 and 200, respectively.

Thereafter, the connecting wire 313 is inserted into the end section of the electric heating element 312; this section of the electric heating element 312 with the inserted connecting wire is inserted into the hole 323 of the inner conductor 322 and the first part 311 of the tubular metal jacket 301 is butt welded or soldered to the second part 321 of the tubular metal jacket 301, which leads to the Figure 16 shown intermediate stage.

A further local compaction process, e.g. by hammering in a hexagonal shape, is then carried out in the unheated transition area Ü1, whereby on the one hand the homogenization of the electrically insulating material in the transition area between the first part 311 of the tubular metal jacket 301 and the second part 321 of the tubular metal jacket 301 and on the other hand an intimate press contact between electrical Heating element 312, connecting bolt 313 and inner conductor 322, as can be seen in the Figure 17a can recognize.

In the Figures 15b and 17b will be the Figures 15a or 17a, respectively, in a second variant, which differs from the variant of the Figures 15a and 17a only differs in that a stepped connecting bolt 313' is used instead of the connecting bolt 313 and accordingly the bore 323 is replaced by a stepped bore 323'. The thinner section 313a' of the stepped connecting bolt 313' is also subjected to a local compaction process after it has been introduced into the section 323a' of the stepped bore 323' and is thereby directly press-contacted, while in the other section of the stepped connecting bolt 313' a press contact to the bore 323' only takes place indirectly via the electrical heating element 312.

Since there are no other differences, the reference symbols from the Figures 15a and 17a used, and for the description of the other from the Figures 15b and 17b For the aspects contained in this document, please refer to the corresponding description of the Figures 15a and 17a referred to.

The Figures 18 to 21 show different intermediate stages in carrying out another method for producing an electric heating device 400.

Just as in the case of the electric heating device 300, in the case of the electric heating device 400 the first part 411 of the tubular metal casing 401 has no first unheated section U1 and in particular no unheated transition section Ü1. It therefore only forms over its entire length the heated area with electrical heating element 412 formed here by a coiled resistance wire and electrically insulating material 415.

As with the electrical heating device 300 or its manufacture, the coiled heating element with electrically insulating material and tubular metal jacket is provided as a bar material and then the tubular metal jacket and the surrounding electrically insulating material are cut off at the end with a tool 450 to the length corresponding to the respective unheated transition sections, so that a part of the coiled electrical heating element, which is used to form the unheated transition region Ü1, protrudes at the end, as shown in Figure 18 is shown.

As in Figure 19 As can be seen, a feedthrough 420 is then provided, the metal casing of which forms the second part 421 of the tubular metal casing 401 of the electric heating device 400, with an inner conductor 422, an annular groove 423 introduced into the front side of the inner conductor 422 and electrically insulating material 425. Unlike in the corresponding step, which is shown in Figure 15 As shown, no separate connecting wire is required.

Thereafter, the end portion of the electric heating element 412 is inserted into the bore 423 of the inner conductor 422 and the first part 411 of the tubular metal jacket 401 is butt welded or soldered to the second part 421 of the tubular metal jacket 401, resulting in the Figure 20 shown intermediate stage.

A further local compaction process, e.g. by hammering in a hexagonal shape, is then carried out in the unheated transition area Ü1, which on the one hand causes the homogenization of the electrically insulating material in the transition area between the first part 411 and the second part 421 of the tubular metal jacket and on the other hand an intimate press contact between the electrical heating element 412 and the inner conductor 422, as can also be seen in the Figure 21 can recognize.

List of reference symbols

10,100,110,200,210, 300,400

electric heater

11,101,201,301,401

multi-part tubular metal casing

11.1,111,211,311,411

first part (of the metal shell)

11.2,121,221,321,421

second part (of the metal shell)

12,12',12",112,212, 312,412

electric heating element

12.1,12.1"

Section

13,113,213,313

Connecting wire

313'

stepped connecting wire

313a'

Section

14

Connection sleeve

15

Connecting bolt

15.1

opening

16,115,215,315,415

electrically insulating material

17,125,225,325,425

electrically insulating material

18

Plug

111a

End area

113a

thread

121a

End area

123a

Counter thread

114,214

Weld point

120,220,320,420

execution

122,222,322,422

Inner conductor

123,223,224,323

drilling

323'

stepped bore

323a'

Section

131,231,331,431

Connection point

132

cavity

133

ring

226

Connection

350,450

Tool

423

Ring groove

A

Length (of a connection)

B

heated area

U

unheated area

U1

first part (of the unheated area)

U2

second part (of the unheated area)

Ü1

unheated transition area

W1,W2

Spiral axle

Claims (14)

1. Method for manufacturing an electric heating apparatus (10, 100, 200, 300, 400) having an electric heating element (12, 12', 12", 112, 212, 312, 412) which is arranged, embedded in an electrically insulating material (16, 17, 115, 125, 215, 225, 315, 325, 415, 425), on the inside of a multi-piece tubular metal casing (11, 101, 201, 301, 401), wherein the electric heating apparatus (10, 100, 200, 300, 400) comprises, on the inside of the multi-piece tubular metal casing (11, 101, 201, 301, 401),

   - on at least one end, an unheated region (U) in which, when the electric heating apparatus (10, 100, 200, 300, 400) is in operation, the current at least also flows through at least one connection wire (13, 113, 213, 313) and/or at least one connection sleeve (14) and/or at least one connection bolt (15) which is in electrical contact with the electric heating element (12, 12', 12", 112, 212, 312, 412), and further

   - a heated region (B) in which, when the electric heating apparatus (10, 100, 200, 300, 400) is in operation, the current only flows through a section extending through the heated region (B) of the electric heating element (12, 112, 212, 312, 412),
   wherein, in accordance with the method,

   - in a first method step, the heated region (B) is produced in a first part (11.1, 111, 211, 311, 411) of the multi-piece tubular metal casing (11, 101, 201, 301, 401) and is compressed,

   - in a second method step, carried out independently of the first method step, at least one section of the unheated region (U) is produced in a second part (11.2, 121, 221, 321, 421) of the multi-piece tubular metal casing (11, 101, 201, 301, 401), and the first part (11.1, 111, 211, 311, 411) and the second part (11.2, 121, 221, 321, 421) of the multi-piece tubular metal casing (11, 101, 201, 301, 401) are connected to each other,

   characterized in that, in the second method step, the second part (11.2, 121, 221, 321, 421) of the multi-piece tubular metal casing (11, 101, 201, 301, 401) is compressed, together with the components arranged therein, wherein the second compression is carried out such that, due to the resulting axial pressing force, an almost homogenous transition region is formed between the electrically insulating material (16, 115, 215, 315, 415) in the regions which were subject to the compression in the first method step and the electrically insulating material (17, 125, 225, 325, 425) in the regions which were subject to the compression in the second method step.
2. Method for manufacturing an electric heating apparatus (10, 100, 200, 300, 400) in accordance with claim 1,
   characterized in that

   - the section of the electric heating element (12, 12', 12", 112, 212, 312, 412) that extends through the heated region (B) is positioned in a first part (11.1, 111, 211, 311, 411) of the multi-piece tubular metal casing (11, 101, 201, 301, 401),

   - the electrically insulating material (16, 115, 215, 315, 415) is introduced into in this region of the first part (11.1, 111, 211, 311, 411) of the multi-piece tubular metal casing (11, 101, 201, 301, 401) such that the section of the electric heating element (12, 12', 12", 122, 222, 322, 422) arranged in the first part (11.1, 111, 211, 311, 411) of the multi-piece tubular metal casing (11, 101, 201, 301, 401) is insulated by the electrically insulating material (16, 115, 215, 315, 415), and

   - in that the first part (11.1, 111, 211, 311, 411) of the multi-piece tubular metal casing (11, 101, 201, 301, 401) is compressed.
3. Method for manufacturing an electric heating apparatus (10, 100, 200, 300, 400) in accordance with claim 1 or 2,
   characterized in that an electric heating apparatus (10, 100, 200, 300, 400) is produced in which the unheated region (U) includes a transition region (Ü1), through which, when the electric heating apparatus (10, 100, 200, 300, 400) is in operation, the electrical current flows simultaneously both through the at least one connection wire (13, 113, 213, 313) and/or the connection bolt (15), as well as through a section (12.1, 12.1") of the electric heating element (12, 12', 12") extending through the unheated transition region (Ü1) which is in electrical contact with the connection wire (13, 113, 213, 313) and/or the connection bolt (15), and in that, in accordance with the method, in the second method step, carried out independently of the first method step, at least one section of the unheated region (U) is produced by inserting, together with at least one section of the unheated transition region (Ü1), in which a section (12.1, 12.1") of the electric heating element (12, 12', 12"), together with the connection wire (13, 113, 213, 313) arranged thereupon, and/or together with the connection sleeve (14) arranged thereupon, and/or together with the connection bolt (15) arranged thereupon, into a second part (11.2, 121, 221, 321, 421) of the multi-piece tubular metal casing (11), by filling the electrical insulating material (17, 125, 225, 325, 425) into the second part (11.2, 121, 221, 321, 421) of the multi-piece tubular metal casing (11, 101, 201, 301, 401), such that the section (12.1, 12.1") of the electric heating element (12, 12', 12") which is arranged in the second part (11.2, 121, 221, 321, 421) of the multi-piece tubular metal casing (11, 101, 201, 301, 401) is embedded in the electrically insulating material (17, 125, 225, 325, 425).
4. Method for manufacturing an electric heating apparatus (10, 100, 200, 300, 400) in accordance with any of claims 1 to 3,
   characterized in that, in the first method step, a connection wire (13, 113, 213, 313) is brought into an electrically conductive connection with an end section of the electric heating element (12, 12', 12", 112, 212, 312, 412), and/or in that, in the first method step, a connection sleeve (14) made of metal is brought into an electrically conductive connection with an end section of the electric heating element (12, 12', 12", 112, 212, 312, 412).
5. Method for manufacturing an electric heating apparatus (10, 100, 200, 300, 400) in accordance with any of claims 1 to 4,
   characterized in that the electric heating element (12, 12', 12", 112, 212, 312, 412) is coiled such that an end section (12.1, 12.1', 12.1") of the electric heating element (12, 12', 12", 112, 212, 312, 412) comprises a smaller coil diameter than a section of the electric heating element (12, 12', 12", 112, 212, 312, 412) which is located in the heated region (B) of the completed electric heating apparatus (10, 100, 200, 300, 400).
6. Method for manufacturing an electric heating apparatus (10, 100, 200, 300, 400) in accordance with any of claims 1 to 5,
   characterized in that, in order to produce the second part (11.2, 121, 221, 321, 421) of the multi-piece tubular metal casing (11, 101, 201, 301, 401), a conduit (120, 220, 320, 420) which comprises an inner conductor (122, 222, 322, 422) which is electrically insulated from an outer tube made of metal.
7. Method for manufacturing an electric heating apparatus (10, 100, 200, 300, 400) in accordance with any of claims 1 to 6,
   characterized in that an inner conductor (122, 222, 322, 422) of the second part (11.2, 121, 221, 321, 421) of the multi-piece tubular metal casing (11, 101, 201, 301, 401) is formed on side facing the first part (11.1, 111, 211, 311 411) of the multi-piece tubular metal casing (11, 101, 201, 301, 401), is provided with an annular groove or is half-drilled, and in that the electrical contact to the electric heating element (12, 12', 12", 112, 212, 312, 412) is established directly or through one of its connection wires (13, 113, 213, 313) by inserting into the thereby machined section of the inner conductor (122, 222, 322, 422) of the second part (11.2, 121, 221, 321, 421), and pressure bonding, a section of the electric heating element (11, 12', 12", 112, 212, 312, 412) or of its connection wire (12, 113, 213, 313).
8. Electric heating apparatus (10, 100, 200, 300, 400), which can be manufactured in accordance with any of claims 1 to 7, having an electric heating element (12, 12', 12", 112, 212, 312, 412) which is arranged, embedded in an electrically insulating material (16, 17, 115, 125, 215, 225, 315, 325, 415, 425), on the inside of a multi-piece tubular metal casing (11, 101, 201, 301, 401) which comprises a first part (11.1, 111, 211, 311, 411) and a second part (11.2, 121, 221, 321, 421), wherein the electric heating apparatus (10, 100, 200, 300, 400) comprises, on the inside of the multi-piece tubular metal casing (11, 101, 201, 301, 401);

   - on at least one end, an unheated region (U) in which, when the electric heating apparatus (10, 100, 200, 300, 400) is in operation, the electrical current also at least flows through at least one connection wire (13, 113, 213, 313) and/or at least one connection sleeve (14) and/or at least one connection bolt (15), which is in electrical contact with the electric heating element (12, 12', 12", 112, 212, 312, 412), and further comprises

   - a heated region (B) in which, when the electric heating apparatus (10, 100, 200, 300, 400) is in operation, the electrical current only flows through a section of the electric heating element (112, 12', 12", 112, 212, 312, 412) which extends through the heated region (B), wherein the heated region (B) is arranged in the first part (11.1) of the multi-piece tubular metal casing (11, 101, 201, 301, 401) and the unheated region (U) is arranged in a second part (11.2, 121, 221, 321, 421) of the multi-piece tubular metal casing (11, 101, 201, 301, 401),

   characterized in that the second part (11.2, 121, 221, 321, 421) of the multi-piece tubular metal casing (11, 101, 201, 301, 401) is compressed, together with the components arranged therein, is compressed such that a nearly homogeneous transition region is created between the electrically insulating material (16, 115, 215, 315, 415) in the first part (11.1, 111, 211, 311, 411) of the multi-piece tubular metal casing (11, 101, 201, 301, 401) and the electrically insulating material in the second part (11.2, 121, 221, 321, 421) of the multi-piece tubular metal casing (11, 101, 201, 301, 401).
9. Electric heating apparatus (10, 100, 200, 300, 400) in accordance with claim 8, characterized in that
   the unheated region (U) comprises an unheated transition region (Ü1) in which, when the electric heating apparatus (10, 100, 200, 300, 400) is in operation, the electrical current flows simultaneously both through the at least one connection wire (13, 113, 213, 313) and/or the at least one connection sleeve (14), and/or the at least one connection bolt (15), as well as through a section (12.1) of the electric heating element (12, 12', 12", 112, 212, 312, 412) extending through the unheated transition region (Ü1) which is in electrical contact with the connection wire (13, 113, 213, 313) and/or the connection sleeve (14) and/or the connection bolt (15).
10. Electric heating apparatus (10, 100, 200, 300, 400) in accordance with either of claims 8 or 9,
    characterized in that
    a connection wire (13) is in an electrically conductive connection with an end section of the electric heating element (12, 12', 12", 112, 212, 312, 412).
11. Electric heating apparatus (10, 100, 200, 300, 400) in accordance with any of claims 8 to 10,
    characterized in that a connection sleeve (14) made of metal is in an electrically conductive connection with an end section of the electric heating element (12, 12', 12", 112, 212, 312, 412).
12. Electric heating apparatus (10, 100, 200, 300, 400) in accordance with any of claims 8 to 11,
    characterized in that the electric heating element (12, 12', 12", 112, 212, 312, 412) is coiled such that an end section (12.1, 12.1', 12.1") of the electric heating element (12, 12', 12", 112, 212, 312, 412) comprises a smaller coil diameter than a section of the electric heating element (12, 12', 12", 112, 212, 312, 412) which is located in the heated region (B) of the completed electric heating apparatus (10, 100, 200, 300, 400).
13. Electric heating apparatus (10, 100, 200, 300, 400) in accordance with any of claims 8 to 12,
    characterized in that the second part (11.2, 121, 221, 321, 421) of the multi-piece tubular metal casing (11, 101, 201, 301, 401), having free cross section which, at least following the compression, can accommodate the outer contour of the end section of the first part (11.1, 111, 211, 311, 411) of the multi-piece tubular metal casing (11, 101, 201, 301, 401) in the first method step, is slid over this end section of the first part (11.1, 111, 211, 311, 411) of the multi-piece tubular metal casing (11, 101, 201, 301, 401) and is fixed thereon.
14. Electric heating apparatus (10, 100, 200, 300, 400) in accordance with any of claims 8 to 13,
    characterized in that a part of the electric heating element (12, 12', 12", 112, 212, 312, 412), together with a thereupon arranged connection wire (13, 113, 213, 313) and/or with a thereupon arranged connection sleeve (14), is inserted from the one side into the second part (11.2, 121, 221, 321, 421) of the multi-piece tubular metal casing (11, 101, 201, 301, 401), and in that a connection bolt (15), having an opening (15.1) for receiving this part of the electric heating element (12, 12', 12", 112, 212, 312, 412), together with the thereupon arranged connection wire (13, 113, 213, 313) and/or with the thereupon arranged connection sleeve (14), is inserted from the other side into the second part (11.2, 121, 221, 321, 421) of the multi-piece tubular metal casing (11, 101, 201, 301, 401) and, through the opening (15.1) is slid over this part of the electric heating element and the thereupon arranged connection wire (13, 113, 213, 313) and/or the thereupon arranged connection sleeve (14).

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