Joining methods and devices for carrying them out

Abstract

Joining method for connecting an inner joining partner with an outer joining partner geometrically matched to it, in which the outer joining partner is heated to a joining temperature, then the outer joining partner is placed onto the inner joining partner, and the outer joining partner is cooled, wherein the outer joining partner is first heated to a preheating temperature in a furnace in a first heating step and then brought to the joining temperature in a second heating step by means of inductive heating, characterized in that the furnace is operated at least predominantly by means of waste heat generated by a waste heat-producing production component, which is a power plant, and in which the heat input into the outer joining partner in the furnace is determined and the heat input still required to reach the joining temperature by means of inductive heating is calculated from this.

Description

[0001] The present invention relates to a joining method with two-stage heating of components and devices for carrying it out.

[0002] In joining processes involving an outer and an inner component, it is often necessary to first heat the outer component so that it expands, then place it onto the inner component and shrink it in place by cooling. An example of this is the motor housing and stator of an electric motor. Here, it is crucial that the housing presses very tightly against the stator to prevent it from rotating within the housing. A common and relatively fast method is the inductive heating of the outer component. For this, the outer component is placed on an inductor, which is then switched on. Heat is generated in the outer component via induction, causing it to expand. However, this inductor method is very energy-intensive.

[0003] DE 10 2019 129 271 B3 relates to a device for mounting a spherical plain bearing comprising an inner ring and a split outer ring. The device includes a clamping ring designed to receive the outer ring, the inner diameter of which corresponds at most to the outer diameter of the outer ring in its maximally compressed state. A temperature control device in the form of an induction heater is provided for shrinking the clamping ring onto the outer ring and for releasing the clamping ring from the outer ring.

[0004] EP 1 962 410 B1 discloses a heating and temperature monitoring system for shrinking a rotor cap onto a rotor. The heating and temperature monitoring system has a control unit designed to measure temperatures detected by means of temperature sensors and output a signal to a heating element, thereby heating the rotor cap and enabling it to be shrunk onto the rotor.

[0005] DE 909 405 B relates to a heat-shrinkable hub for rotors of large electrical machines, designed for shrinking onto or removing from a shaft. At least the inner annular space between suitably short hub seating surfaces is filled with a heat-insulating lining, thereby achieving intensive heat transfer to the hub and largely preventing such transfer to the hub support, such as a shaft. In addition to the heat-insulating inner lining, the outer surfaces of the hub can also be covered with a heat-insulating lining, which can be sealed off by a sheet metal jacket bolted to the hub. To further improve the thermal conditions during the shrinking process, the end faces of the hub support not covered by the hub seating surface can also be provided with heat insulation.

[0006] German patent DE 10 2008 025 692 A1 proposes using the waste heat from electrical converters and electric machines for heating in a subsequent process step within an industrial process. This involves using liquid cooling for the heat-generating elements. This saves electrical or fossil-based energy, which in turn leads to a direct or indirect reduction of greenhouse gas emissions.

[0007] DE 10 2005 061 920 B4 relates to a method for producing a shrink fit for an annular drive component on a shaft, in which the drive component has an opening corresponding to the outer diameter of the shaft, the drive component is heated until a joining temperature profile is reached and thereby expanded, the drive component is pushed over the shaft upon reaching the joining temperature profile and subsequently cools in a predefined position, thereby shrinking firmly onto the shaft. Before being pushed onto the shaft, the drive component is heated simultaneously and exclusively from the radial inside and radial outside, respectively with respect to the opening.

[0008] Against this background, the invention aims to provide a method and a device with which a joining process can be optimized in terms of energy and time.

[0009] The problem is solved according to the invention by a method with the features of claim 1 and devices with the features of claims 3 and 5. Embodiments and further developments of the invention are set out in the dependent claims and the description.

[0010] The invention relates to a joining method for connecting an inner joining partner with an outer joining partner geometrically matched to it, in which the outer joining partner is heated to a joining temperature, then the outer joining partner is placed onto the inner joining partner, and the outer joining partner is cooled. In the method according to the invention, the outer joining partner is first heated to a preheating temperature in an oven in a first heating step and then brought to the joining temperature in a second heating step by means of inductive heating. According to the invention, the oven is operated at least predominantly by means of waste heat generated by a production component, for example, a power plant, and the heat input into the outer joining partner in the oven is determined, and from this the additional heat input required to reach the joining temperature by means of inductive heating is calculated.

[0011] Since heating the outer joining partner with the induction unit is very energy-intensive, the outer joining partner is preheated to a preheating temperature via an oven process, so that only a small amount of heat input is required from the induction unit. The preheating temperature is lower than the joining temperature. Vehicle plants typically have their own power plants that generate waste heat. This waste heat can be used to operate the oven, thus generating the initial and larger heat input into the outer joining partner in a virtually energy-neutral manner. The final heating to the ultimately required joining temperature is then carried out by the induction unit.

[0012] According to the invention, the heat input into the outer joining partner in the oven is determined, and the additional heat input required by inductive heating to reach the joining temperature is calculated from this. In a further embodiment, the calculated required heat input by inductive heating is used to control the power and / or the cycle time of an induction unit for carrying out the second heating step. Communication is provided between the oven and the induction unit, so that the induction unit receives information about the initial heat input received by the outer joining partner at any given time and the amount of heat that the induction unit still needs to supply to the outer joining partner.

[0013] The invention also relates to a device for carrying out the joining process according to the invention. The device comprises an oven for carrying out the first heating step and an induction unit for carrying out the second heating step, and a unit configured to detect the heat input into the outer joining partner in the oven at a given time and to determine from this the amount of heat that the induction unit still needs to supply to the outer joining partner, wherein communication is provided between the oven and the induction unit so that the induction unit receives information about the initial heat input received by the outer joining partner at any given time and the amount of heat that the induction unit still needs to supply to the outer joining partner.

[0014] In another embodiment, the device comprises a unit that is configured to regulate the power and / or cycle time of the induction unit according to the amount of heat that the induction unit still needs to supply to the external joining partner.

[0015] The invention also relates to a production plant comprising a device for carrying out the joining process according to the invention and at least one production component that produces waste heat, wherein means are provided for supplying the waste heat generated to the furnace of the device for carrying out the joining process according to the invention. According to the invention, the at least one production component that produces waste heat comprises at least one power plant.

[0016] The advantages of the solution according to the invention include the sustainable use of the power plant's waste heat and energy savings in the joining process. Furthermore, the process step using the inductor can be significantly shortened. While the furnace process is carried out offline in batches, possibly outside the main line, the inline process can be shortened, resulting in a reduction of the cycle time. Further advantages and embodiments of the invention will become apparent from the description.

Claims

[1] Joining method for connecting an inner joining partner with an outer joining partner geometrically matched to it, wherein the outer joining partner is heated to a joining temperature, then the outer joining partner is placed on the inner joining partner, and the outer joining partner is cooled, wherein the outer joining partner is first heated to a preheating temperature in an oven in a first heating step and then brought to the joining temperature in a second heating step by means of inductive heating, characterized by , that the furnace is operated at least predominantly by means of waste heat generated by a waste heat-producing production component, which is a power plant, and in which the heat input into the external joining partner in the furnace is determined and the heat input still required to reach the joining temperature by inductive heating is calculated from this. [2] Joining method according to claim 1, wherein the calculated required heat input by inductive heating is used to control the power and / or the cycle time of an induction device for carrying out the second heating step. [3] Apparatus for carrying out the method according to one of the preceding claims, comprising an oven for carrying out the first heating step and an induction unit for carrying out the second heating step, characterized bythat the device comprises a unit which is designed to detect the heat input into the external joining partner in the oven at a given time and to determine from this the amount of heat that the induction unit still needs to supply to the external joining partner, and that communication is provided between the oven and the induction device so that the induction device receives information about the initial heat input that the external joining partner received at what time and the amount of heat that the induction unit still needs to supply to the external joining partner. [4] Device according to claim 3, comprising a unit configured to control the power and / or cycle time of the induction unit according to the amount of heat that the induction unit still needs to supply to the external joining partner. [5] Production plant comprising a device according to claim 3 or 4 and at least one waste heat producing production component, which includes at least one power plant, and means for supplying the waste heat generated to the furnace of the device according to claim 3 or 4.