Method for manufacturing an electric heating device

Abstract

Method for manufacturing an electric heating device (100, 200, 300, 400, 500, 600, 700) comprising the steps - Providing a sleeve (130, 230, 330, 430, 530, 630, 730) made of a first material having a first strength, - Arranging an electric heating element (110, 210, 310, 410, 510, 610, 710) in the sleeve (130, 230, 330, 430, 530, 630, 730) - Arranging a filling material (120, 220, 320, 420, 520, 620, 720) in the sleeve (130, 230, 330, 430, 530, 630, 730) such that current-carrying parts of the electric heating element (110, 210, 310, 410, 510, 610, 710) are electrically insulated from the sleeve (130, 230, 330, 430, 530, 630, 730) and the position of the electric heating element (110, 210, 310, 410, 510, 610, 710) in the sleeve (130, 230, 330, 430, 530, 630, 730) is fixed, and - at least partial compression of the sleeve (130, 230, 330, 430, 530, 630, 730), of the electrical heating element (110, 210, 310, 410, 510, 610, 710) arranged in sections of the sleeve (130, 230, 330, 430, 530, 630, 730) to be compressed, and of the filling material (110, 210, 310, 410, 510, 610, 710) arranged in sections of the sleeve (130, 230, 330, 430, 530, 630, 730) to be compressed, characterized in that, prior to the completion of the at least partial compression of the sleeve (130, 230, 330, 430, 530, 630, 730) at the point to be compressed Sections a pipe section (140,240,340,440,540,640,740) is arranged which consists of a second material which has a second strength which is higher than the first strength.

Description

[0001] Electric heating devices comprising a sleeve with an electric heating element arranged therein, the current-carrying parts of which are electrically insulated from the sleeve, are a standard means for the electrical heating of objects and / or media.

[0002] For many specific embodiments of such electric heating devices, there is a desire, on the one hand, for the highest possible compression to ensure optimal heat conduction from the electric heating element to the sleeve that comes into contact with the object or medium, while at the same time the applicable compression must be limited, at least locally. This is necessary, for example, because other pressure-sensitive elements, such as electronic components, are located in the sleeve at certain points, or because deformation caused by excessive compression is undesirable in these areas. This is addressed by compressing the sleeve to varying degrees in different sections. Examples of such applications include DE 10 2014 108 919 A1 and DE 20 2017 100 531 U1.

[0003] However, implementing this approach in the manufacturing process has so far proven to be unreliable. With other electric heating cartridges, manufacturing problems arise from insufficient strength of the casing material, for example, when a sleeve made of ultra-pure titanium is required for medical applications.

[0004] The object of the invention is therefore to provide a method for manufacturing an electric heating device, in particular a heating cartridge or a tubular heating element, which is improved in particular with regard to its process reliability.

[0005] This problem is solved by a method having the features of claim 1. Advantageous further developments of the method are the subject of the dependent claims.

[0006] The inventive method for manufacturing an electric heating device comprises the steps - Providing a sleeve made of a first material that has a first strength, - Arranging an electric heating element in the sleeve, - Arranging a filling material in the sleeve so that current-carrying parts of the electric heating element are electrically insulated from the sleeve and the position of the electric heating element in the sleeve is fixed, and - at least partial compression of the sleeve, the electrical heating element arranged in sections of the sleeve to be compressed, and the filling material arranged in sections of the sleeve to be compressed The essential aspect of the invention is that, prior to the completion of the at least partial compression of the sleeve, a pipe section is arranged in the sections to be compressed, which consists of a second material that has a second strength that is higher than the first strength.

[0007] In this way, the compaction of the electric heating device can be achieved very precisely and with process-reliable, highly reproducible results.

[0008] This is particularly relevant for electric heating devices with areas of varying compression, because the area in which a given compression is achieved can be locally defined in this way, allowing for a controlled gradation of different compression levels. Furthermore, the additional pipe section made of a higher-strength material ensures the ring clamping force during compression.

[0009] It should be explicitly pointed out here that the step of at least partial compression is naturally also realized when the entire electric heating device is compressed simultaneously.

[0010] The electrical heating element can be, for example, a resistance wire wound onto a winding body, in particular a ceramic winding body, a self-supporting resistance wire, or an embedded and positioned heating wire coil.

[0011] The filling material is typically an electrically insulating material with the highest possible thermal conductivity. In particular, it can be magnesium oxide granules.

[0012] The arrangement of this filling material in the sleeve can therefore particularly mean the filling of an insulating powder, insulating granules or other insulating parts.

[0013] According to a particularly preferred embodiment of the method, the material from which the sleeve is made is copper, aluminum, titanium, or brass, so that a sleeve made of copper, aluminum, titanium, or brass is provided. All these materials have in common that they exhibit relatively good thermal conductivity but not very high strength.

[0014] The sleeve, which is preferably designed as a tube closed at one end, is preferably provided by machining it from a solid block, deep drawing it from a sheet or by step pressing it.

[0015] The preferred material for the pipe sections to be arranged in sections to be compacted is a steel, in particular a stainless steel, i.e. a high-strength material.

[0016] In a preferred embodiment of the invention, the arrangement of the pipe sections for at least one pipe section is achieved by sliding it onto the sleeve in such a way that it surrounds the section to be compressed in a radial direction. This not only allows for particularly simple and precise positioning, but also enables highly precise local force application during compaction, in particular by using a compaction tool that, at least at the beginning of the compaction process, applies force primarily to the pipe section being pushed onto the sleeve.

[0017] According to a preferred further development of this embodiment of the method, the compaction is carried out in such a way that, after compaction, the pushed-on pipe section is aligned with sections of the sleeve onto which no pipe section is pushed.

[0018] However, it is also possible to insert the pipe section into the sleeve. This is particularly suitable if the sleeve's strength is insufficient to achieve the necessary ring clamping force or if a homogeneous surface is required for the electric heating device.

[0019] It is particularly preferred if the possibility of creating precisely defined uncompacted or weakly compacted areas is used to arrange at least one electronic component, in particular a sensor, a fuse and / or a switch, in the sleeve. Preferably, this is done by arranging the electronic component together with the electrical heating element in the sleeve, i.e., in particular as a pre-configured assembly.

[0020] By positioning a pipe section on the sleeve in such a way that it extends beyond the sleeve, particularly beyond an end face of the sleeve, it is possible to create an electric heating device with a connection area possessing defined properties. For example, this largely prevents unwanted heat flow towards the connections of the electric heating device. In particular, it is possible to arrange another pipe within the section of the pipe extending beyond the sleeve, thus concentrically extending the sleeve.

[0021] It can be advantageous to rework the base of the sleeve after compaction, in particular to create a flat end face, which can be achieved, for example, by machining the base. However, it should also be noted that, with an appropriate selection of the compaction levels in the respective areas, the inventive method can, in many cases, prevent deformation of the end face during compaction, thus rendering such a rework step unnecessary.

[0022] The invention is explained in more detail below with reference to figures illustrating exemplary embodiments. These show: Fig. 1a: the provided components of a first variant of an electric heating device, Fig. 1b: a sectional view of the composite components made of Fig. 1a before compaction, Fig. 1c: a cross-sectional view of the components from Fig. 1a manufactured electric heating device after compression, Fig. 2: a second variant of an electric heating device that can be produced using the method after compression, Fig. 3: a third variant of an electric heating device that can be produced using the method after compression, Fig. 4a: a fifth variant of an electric heating device producible by the method prior to compression, Fig. 4b: the heating device from Fig. 4a after compaction, Fig. 5a: a fifth variant of an electric heating device producible by the method prior to compression, Fig. 5b: the heating device from Fig. 5a after compaction, Fig. 6: a sixth variant of an electric heating device that can be produced using the method after compression, Fig. 7a: a seventh variant of an electric heating device producible by the method prior to compression, and Fig. 7b: the heating device from Fig. 8a after compaction.

[0023] Insofar as arrows are shown in some figures depicting uncompressed electric heating devices, these indicate the direction in which the system is compressed.

[0024] Fig. Figure 1a shows the partially pre-configured components of an electric heating device 100, provided for the execution of the subsequent process steps. In particular, the electric heating element 110, designed here as a winding body 112 wound with a resistance wire 111, as well as the copper sleeve 130 and the stainless steel tube section 140, are visible. Naturally, both copper and stainless steel have a strength, and the strength of stainless steel is higher than that of copper.

[0025] The electric heating element 110 is also pre-configured insofar as an electronic component 150, namely a temperature sensor, is arranged at the end of the winding body and a connection to connecting wires 160 has already been established.

[0026] In the illustration of the electric heating device 100 before the process step of at least partial compression in Fig. 1b the electric heating element 110 has been arranged in the sleeve 130 and the filling material 120 in the form of magnesium oxide powder has also been arranged in the sleeve 130, so that current-carrying parts, namely the resistance wire 111, of the electric heating element 110 are electrically insulated from the sleeve 130 and the position of the electric heating element 110 in the sleeve 130 is fixed.

[0027] By the process step of at least partially compressing the electric heating device 100, this arrangement is then placed in the Fig. The form shown in Figure 1c was converted. In particular, only the stainless steel pipe section 140 was compacted, resulting in a compacted section 101 and an uncompacted section 102, in which the electronic component 150 is located. The compaction was carried out such that the pipe section 140 now runs in alignment with the sleeve 130 in the uncompacted section 102 of the electric heating device 100.

[0028] Fig. Figure 2 shows a second variant of an electric heating device 200 that can be produced by the method, comprising a compacted section 201, uncompacted sections 202, 203, an electric heating element 210 with resistance wire 211 and wound coil body 212, filler material 220, sleeve 230, pipe section 240, electronic component 250 and connecting wires 260 after compaction, at least in sections.

[0029] The difference to the electric heating device 100 is that the pipe section 240 does not include the connection-side end region of the electric heating device 200 and the sleeve 230, thus creating a second unsealed area 203. This can be useful, for example, for some types of electrical connections between connecting wires 260 and the electric heating element 210 and / or electronic component 250.

[0030] Fig. Figure 3 shows a third variant of an electric heating device 300 that can be produced by the method, comprising a compacted section 301, uncompacted sections 302, 303, an electric heating element 310 with resistance wire 311 and wound coil body 312, filler material 320, sleeve 330, tube section 340, electronic component 350 and connecting wires 360 after compaction, at least in sections.

[0031] Unlike the electric heating device 200, in the electric heating device 300 the pipe section 340 projects beyond the connection-side end region of the sleeve 330, wherein an additional pipe 370, in this embodiment again a stainless steel pipe, is arranged in the area of ​​the pipe section 340 that projects beyond the sleeve 330, which concentrically extends the sleeve 330. In this way, the heat transfer to the connection side can be reduced.

[0032] Fig. 4a and Fig. Figure 4b shows a fourth variant of an electric heating device 400 that can be produced by the method, comprising a compacted section 401, an uncompacted section 402, an electric heating element 410 with resistance wire 411 and wound coil body 412, filler material 420, sleeve 430, pipe section 440, electronic component 450 and connecting wires 460 before and after compaction, at least in sections.

[0033] The difference to the electric heating device 100 is that the pipe section 440 is part of a further sleeve 441 surrounding the sleeve 430, with both sleeves 430,441 having a larger cross-section in the area to be compressed before compression than in the area not to be compressed.

[0034] Fig. 5a and Fig. Figure 5b shows a fifth variant of an electric heating device 500 that can be produced by the method, comprising a compacted section 501, an uncompacted section 502, an electric heating element 510 with resistance wire 511 and wound coil body 512, filler material 520, sleeve 530, pipe section 540 and connecting wires 560 before and after compaction, at least in sections.

[0035] The electric heating device 500 is similar to the electric heating device 300 in that, as with the latter, the pipe section 540 projects beyond the sleeve 530 in the connection-side direction. However, unlike the electric heating device 300, in the embodiment according to the Fig. 5a and Fig. 5b, however, no further pipe is arranged in this area. Another difference from the electric heating device 300 is that the sleeve 530 has a reinforced base 531 with a significantly increased wall thickness. This is particularly advantageous if any deformation of this base during compaction is to be compensated for, in particular, by machining, e.g., by turning. Furthermore, no electronic component is present.

[0036] Fig. Figure 6 shows a sixth variant of an electric heating device 600 that can be produced by the method, with compacted section 601, electric heating element 610 with resistance wire 611 and wound coil body 612, filler material 620, sleeve 630, pipe section 640 and connecting wires 660 after compaction.

[0037] The electric heating device 600 is structurally similar to the electric heating device 500, but unlike the latter, it has a thermocouple 650 on the bottom side and the pipe section 640 completely accommodates the sleeve 630.

[0038] Fig. 7a and Fig. Figure 7b shows a seventh variant of an electric heating device 700 that can be produced by the method, comprising a compacted section 701, an uncompacted section 702, an electric heating element 710 with resistance wire 711 and wound coil body 712, filler material 720, sleeve 730, pipe section 740, electronic component 750 and connecting wires 760 before and after compaction, at least in sections.

[0039] The difference to the electric heating device 100 according to Fig. 1a to 1c consists in the fact that the pipe section 740 is inserted into the sleeve 730 and not pushed onto it. Reference symbol list 100, 200, 300, 400, 500, 600, 700 Electric heating device 101, 201, 301, 401, 501, 601, 701 compacted section 102, 202, 302, 303, 402, 403, 502, 602 uncompacted section 110, 210, 310, 410, 510, 610, 710 electric heating element 111, 211, 311, 411, 511, 611, 711 Resistance wire 112, 212, 312, 412, 512, 612, 712 Wrapping body 120, 220, 320, 420, 520, 620, 720 Filling material 130, 230, 330, 430, 530, 630, 730 Sleeve 140, 240, 340, 440, 540, 640, 740 pipe section 150, 250, 350, 450, 550, 750 electronic component 370 pipe 441 Sleeve 531 Floor 650 thermocouple

Claims

[1] Method for manufacturing an electric heating device (100,200,300,400,500,600,700) comprising the steps - Providing a sleeve (130, 230, 330, 430, 530, 630, 730) made of a first material having a first strength, - Arranging an electric heating element (110, 210, 310, 410, 510, 610, 710) in the sleeve (130, 230, 330, 430, 530, 630, 730) - Arranging a filling material (120, 220, 320, 420, 520, 620, 720) in the sleeve (130, 230, 330, 430, 530, 630, 730) such that current-carrying parts of the electric heating element (110, 210, 310, 410, 510, 610, 710) are electrically insulated from the sleeve (130, 230, 330, 430, 530, 630, 730) and the position of the electric heating element (110, 210, 310, 410, 510, 610, 710) in the sleeve (130, 230, 330, 430, 530, 630, 730) is fixed, and - at least section-by-section compaction of the sleeve (130, 230, 330, 430, 530, 630, 730), of the electrical heating element (110, 210, 310, 410, 510, 610, 710) arranged in sections of the sleeve (130, 230, 330, 430, 530, 630, 730) that are compacted, and of the filling material (110, 210, 310, 410, 510, 610, 710) arranged in sections of the sleeve (130, 230, 330, 430, 530, 630, 730) that are compacted, characterized by , that before the completion of the at least partial compaction of the sleeve (130,230,330,430,530,630,730) in sections to be compacted, a pipe section (140,240,340,440,540,640,740) is arranged which consists of a second material which has a second strength which is higher than the first strength. [2] Method according to claim 1, characterized by , that a sleeve (130,230,330,430,530,630,730) made of copper, aluminium, titanium or brass is provided. [3] Method according to claim 1 or 2, characterized by, that a pipe section (140,240,340,440,540,640,740) made of steel, in particular stainless steel, is arranged in sections to be compacted. [4] Method according to any of the preceding claims, characterized by , that the pipe section (140,240,340,440,540,640,740) is pushed onto the sleeve (130,230,330,430,530,630,730). [5] Method according to claim 4, characterized by , that the compaction is carried out in such a way that after compaction the pushed-on pipe section (140,240,340,440,540,640) is aligned with sections of the sleeve (130,230,330,430,530,630) onto which no pipe section (140,240,340,440,540,640) is pushed. [6] Method according to any one of claims 1 to 3, characterized by , that the pipe section (740) is inserted into the sleeve (730). [7] Method according to any of the foregoing claims, characterized by, that at least one electronic component (150,250,350, 450,550), in particular a sensor, a fuse and / or a switch, is arranged in the sleeve (130,230,330,430,530,630,730). [8] Method according to claim 7, characterized by , that the electronic component (150,250,350,450,550) together with the electrical heating element (110,210,310,410,510,610,710) is arranged in the sleeve (130,230,330,430,530,630,730). [9] Method according to any of the foregoing claims, characterized by , that a pipe section (340,440,540) is arranged on the sleeve (330,430,530) such that it extends beyond the sleeve (330,430,530). [10] Method according to claim 9, characterized by , that in the area of ​​the pipe section (340) extending beyond the sleeve (330) an additional pipe (370) is arranged, which extends the sleeve (340) concentrically.

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