Brazing apparatus

Abstract

A brazing apparatus includes a brazing chamber configured to receive the first component and the second component to be coupled, the brazing chamber including a first plate that is movable relative to a second plate and between which the first component and the second component are received, an induction spool operable to heat the first plate by induction heating, a resistance heating element operable to heat the second plate by resistance heating, and an electronic control unit configured to selectively activate and deactivate the induction spool and the resistance heating element.

Description

Attorney Docket No. 022233-0089- WO01BRAZING APPARATUSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 737,452, filed on December 20, 2024, the entire content of which is incorporated herein by reference.FIELD

[0002] The present invention relates to a brazing apparatus, and more particularly to a brazing apparatus to couple at least two components.BACKGROUND

[0003] The typical brazing apparatus and process for mass-produced brazed components often includes a vacuum brazing furnace having a large footprint.SUMMARY

[0004] The present disclosure provides, in one aspect, a brazing apparatus configured to couple a first component and a second component via a brazing process, the brazing apparatus including: a brazing chamber configured to receive the first component and the second component to be coupled, the brazing chamber including a first plate that is movable relative to a second plate and between which the first component and the second component are received; an induction spool operable to heat the first plate by induction heating; a resistance heating element operable to heat the second plate by resistance heating; an electronic control unit configured to selectively activate and deactivate the induction spool and the resistance heating element.

[0005] The present disclosure provides, in another aspect, a brazing apparatus configured to couple a first component and a second component via a brazing process, the brazing apparatus including: a brazing chamber configured to receive a first component and a second component, the brazing chamber including a first metal plate pivotably coupled to a second metal plate and between which the first component and the second component are received, the first component in contact with the first metal plate and the second component in contact with the second metalAttorney Docket No. 022233-0089- WO01 plate; an induction spool operable to inductively heat the first metal plate; a resistance heating element operable to heat the second metal plate; an electronic control unit configured to activate and deactivate the induction spool and the resistance heating element to heat the first component and the second component with the induction spool, the resistance heating element, or both the induction spool and the resistance heating element in a successive order.

[0006] The present disclosure provides, in another aspect, a method of coupling a first component and a second component by brazing including: opening a brazing chamber of a brazing apparatus, the brazing chamber including a first plate that is movable relative to a second plate; inserting the first component and the second component into the brazing chamber; closing the brazing chamber; heating the first plate by a first heating mechanism to increase a temperature of the first component and the second component to a first temperature that is less than a target temperature; heating the second plate by a second heating mechanism to increase the temperature of the components to the target temperature to join the first component and the second component into an assembly; opening the brazing chamber; removing the assembly from the brazing chamber.

[0007] Other features and aspects of the invention will become apparent by consideration of the following detailed description and accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. l is a schematic view of a brazing apparatus.

[0009] FIG. 2 is a section view of a portion of the brazing apparatus in Detail 2 of FIG. 1, including the first plate and the second plate.

[0010] FIG. 3 is a perspective view of a brazing chamber, including a lid and a base.

[0011] FIG. 4 is a cross-section of the interior of a brazing chamber.

[0012] FIG. 5 is a schematic of a plurality of brazing apparatuses in a facility.

[0013] FIG. 6 is a diagram showing a brazing assembly process.Attorney Docket No. 022233-0089- WO01

[0014] FIG. 6A is a graph illustrating a portion of the brazing assembly process of FIG.6.

[0015] FIG. 7 is a diagram showing another brazing assembly process.

[0016] FIG. 7A is a graph illustrating a portion of the brazing assembly process of FIG.7.

[0017] Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.DETAILED DESCRIPTION

[0018] FIGS. 1-4 illustrates a brazing apparatus 10 configured to couple two or more components (e.g., a first component 14 and a second componentl 8) into a brazed assembly via a brazing process. The following description will describe the brazing apparatus as coupling a first component 14 and a second component 18, however, it should be understood that the brazing apparatus may be configured to combine more than two components, for instance, three components, four components, or five components. The first and second components 14, 18 are composed of a base metal that is joined by a filler metal 22 disposed on (e.g., as a cladding) the first and / or second components 14, 18, between the first and second components 14, 18. The filler metal 22 melts at a lower melting temperature than the base metals of the first and second components 14, 18 being joined. The brazing apparatus 10 includes a brazing chamber 26 that is heated by one or more heating mechanisms (e.g., a first heating mechanism and a second heating mechanism). The first heating mechanism is an induction heating mechanism. In the induction heating mechanism, one or more induction spools (e.g., a first induction spool 30 and a second induction spool 34) heat the first and second components 14, 18 to join the first and second components 14, 18. The first and second induction spools should be understood as an example of a first heating element. A second heating mechanism is a resistance heating mechanism thatAttorney Docket No. 022233-0089- WO01 will be described in greater detail below. The brazing apparatus 10 is configured to heat the one or more components 14, 18 by the first heating mechanism, the second heating mechanism, or a combination of the first and second heating mechanisms, either concurrently or in successive order (e.g., first heating mechanism, i.e., induction heating, and then the second heating mechanism, i.e., resistance heating). The first and second heating mechanisms are each advantageous in their own right, and when, combined, provide additional benefits. For instance, the induction heating mechanism may be more cost-effective (e.g., may heat the first and second components more quickly) whereas the resistance heating mechanism may be more controllable. That is, resistance heating, while more gradual, may be more accurately controlled to reach a target temperature without overshooting the target temperature.

[0019] While the disclosure provides that the first heating mechanism is an induction heating mechanism and the second heating mechanism is a resistance heating mechanism, it should be understood that the first heating mechanism may instead be a resistance heating mechanism (e.g., heating with a resistance heating element) and the second heating mechanism may be an inductive heating mechanism (e.g., heating with an induction spool). The brazing apparatus 10 may also include other heating mechanisms in addition to inductive and resistance heating.

[0020] The brazing apparatus 10 of the present embodiment is generally configured to join components such as small, flat or formed, plate components into a brazed assembly having about two to five layers of components. The components to be joined may be aluminum or other metallic material. The present embodiment (shown in FIG. 4) illustrates a heat exchanger including a first component 14 (e.g., a first cooling plate 14) to be coupled to a second component 18 (e.g., a second cooling plate 18) and may include a fin, turbulence inlay or turbulator, or other devices to increase heat transfer.

[0021] With continued reference to FIGS. 1 and 2, the brazing chamber 26 includes a first plate 38 coupled to a lid 42 and a second plate 46 coupled to a base 50, which is stationary. The first plate 38, lid 42, second plate 46, and base 50 together define an interior of the brazing chamber 26. As illustrated in FIG. 2, the lid 42, and first plate 38 with it, are movable (e.g., pivotally coupled) to the base 50 and the second plate 46 so that the first plate 38 is pivotally coupled to the second plate 46 to allow a user to insert into the brazing chamber 26 the first andAttorney Docket No. 022233-0089- WO01 second components 14, 18 to be brazed and remove the brazed assembly upon completion of the brazing process. The lid 42 and the base 50 are coupled at a pivot axis 52 about which the lid 42 pivots. The lid 42 may be pivotable by a hydraulic system, a pneumatic system, an electromechanical system (e.g., a motor or linear actuator), or another suitable system. In another embodiment, the lid 42 and first plate 38 may be translatable (e.g., vertically) relative to the second plate 46 and base 50 to open the brazing chamber 26. The first induction spool 30 may be coupled to the first plate 38 or may be supported in the brazing apparatus 10 adjacent the first plate 38. The second induction spool 34 may be coupled to the second plate 46 or may be supported in the brazing apparatus 10 adjacent the second plate 46. The first plate 38 is heated by the first induction spool 30 and the second plate 46 is heated by the second induction spool 34. The first and second plates 38, 46 comprise a metallic material, such as steel. In other embodiments, the first and second plates may be another metal that has good thermal conductivity and a sufficiently high melting point to resist melting when the plates are heated to a sufficient temperature to melt the filler metal. In another embodiment, a single spool (e.g., the first spool) may heat both the first plate 38 and the second plate 46, for instance, by heating the first plate 38, which in turn, conducts heat to the second plate 46, or vice versa. In other embodiments, the first and second plates may be heated by a single spool. As shown in FIG. 1 and 3, the first plate 38 contacts the first component 14 and the second plate 46 contacts the second component 18. The induction spools 30, 34 heat the first and second plates 38, 46 which in turn conduct heat to the first and second components 14, 18, any additional components to be included in the brazed assembly and to the filler metal 22 to melt the filler metal 22.

[0022] With continued reference to FIG. 2, the second heating mechanism is a resistance heating mechanism (e.g., an indirect resistance heating mechanism) in which one more resistance heating elements (e.g., wires 54) are positioned in channels 56 that extend through the first plate 38 and the second plate 46 to indirectly heat the first and second components 14, 18. The wires 54 are arranged such that there is one wire 54 per channel 56. The wires 54 configured as resistance heating elements should be understood as a second heating element. In the illustrated embodiment, both the first and second plates 38, 46 include channels 56, with a wire 54 extending through at least one channel 56 of the first plate 38 and at least one channel of the second plate 46. In other embodiments, a wire 54 (or wires) may extend through all of theAttorney Docket No. 022233-0089- WO01 channels 56 of either the first plate 38 or the second plate 46. In other embodiments, only the first plate 38 or the second plate 46 may include one or more wires 54 positioned in one or more of the channels 56. It should be understood that the arrangement of wires 54 in the channels 56 of either or both of the first and second plates 38, 46 may be arranged depending on the geometry of the first and second components 14, 18, the individual heating needs (e.g. the amount of heat needed to couple the first and second components 14, 18), and other factors.

[0023] Returning to FIG. 1, the brazing apparatus 10 includes a vacuum source 58 and a gas source 60. The vacuum source 58 generates a vacuum within the brazing chamber 26 by removing air, nitrogen, or other gas contained within the interior of the brazing chamber 26. The gas source 60 introduces a gas (e g., nitrogen or other non-flammable gas such as argon) into the interior of the brazing chamber 26 in order to control the quality of the brazed joint between components 14, 18. The brazing apparatus 10 also includes a cooling source 64 (e.g., a heat exchanger assembly) that generates a flow of a coolant to the first and / or second plates 38, 46 and through the channels 56. As the coolant flows through the channels 56, heat from the first and second plates 38, 46, and the first and second components 14, 18 is transferred to the coolant, thereby cooling the first and second plates 38, 46 and the first and second components 14, 18. The heat exchanger assembly may include a heat exchanger and a pump to cool and transfer the coolant, respectively.

[0024] An electronic control unit, or controller 66, coupled to the brazing chamber 26 receives signals from one or more sensors (e.g., a first temperature sensor 68a coupled to the first plate 38, a second temperature sensor 68b coupled to the second plate 46, an ambient air temperature sensor configured to monitor the temperature within the brazing chamber, an air pressure sensor configured to measure the pressure within the brazing chamber, position sensors configured to measure position of the first and second plates relative to one another, etc.). The controller 66 also generates / sends control signals to control operation of the brazing apparatus 10 (e.g., to open / close the brazing chamber 26 by pivoting the lid 42 relative to the base 50, to selectively activate / deliver power to the induction spools 30, 34 and / or wires 54 to heat the first and second plates 38, 46, to deactivate the induction spools 30, 34 and / or wires 54 to cease heating, to activate / deactivate the vacuum and gas sources 58, 60 and the cooling source 64, etc.). With reference to FIG. 5, the brazing apparatus 10 has a substantially compact footprintAttorney Docket No. 022233-0089- WO01 and one or more brazing apparatuses 10 may be installed in a manufacturing facility to independently assemble a plurality of brazed assemblies. The facility may include, for instance, ten brazing apparatuses 10 positioned adjacent one another. Components may be placed into the brazing chambers and brazing assemblies removed therefrom by an automated process (e.g., using one or more robots 70).

[0025] FIG. 6 illustrates an exemplary method 100 of coupling at least two components into a brazed assembly by brazing. In a first step 110, the brazing chamber 26 of the brazing apparatus 10 is opened by moving (e.g., pivoting) the lid 42 and first plate 38 relative to the second plate 46 and base 50. In the following step 120, the first and second components 14, 18 are inserted into the brazing chamber 26 (e g., by hand, by activation of a robot, etc ). The brazing chamber 26 is closed in the following step 130 by moving the first plate 38 and lid 42 relative to the second plate 46 and base 50. The first and second components 14, 18 may be clamped by the first and second plates 38, 46 or may be clamped by separate clamping assemblies within the brazing chamber 26. In the next step 140, the first and / or second plates 38, 46 are heated by a first heating mechanism. In the illustrated method, the first plate 38is heated by the first inductive spool 30, which conducts heat to the two or more components 14, 18 to be joined into a brazed assembly. In other embodiments of the method, the first plate 38 may be heated by the first induction spool 30 and the second plate 46 may be heated by the second induction spool 34. In other embodiments of the method, the first plate 38 may be heated by one or more wires 54 to heat the first plate 38 by the resistance heating mechanism. In still other embodiments of the method, the second plate 46 may be heated by the resistance heating mechanism. At step 150, beginning concurrently with step 140, or alternatively, with step 110, the controller 66 receives a signal from the first sensor 68a that indicates a condition of the brazing apparatus 26 (e.g., the temperature of the first plate 38) and monitors the condition.

[0026] At step 160, at a first predetermined temperature that is less than a target temperature (e.g., a 400° C temperature of the first and / or second plate), the controller 66 activates the vacuum source 60 to remove the gas (e.g., air or nitrogen) within the brazing chamber 26 while the inductive spool 30 continues heating the first plate 38. In a following step 170, when the first and / or second plates 38, 46 reach a second predetermined temperature (e.g., 500°C) that is higher than the first predetermined temperature, but less than the target temperature, as measured by theAttorney Docket No. 022233-0089- WO01 first and / or second sensors 68a, 68b, the controller 66, in response to the temperature signals, activates the gas source 60 to introduce a gas (e.g., nitrogen) into the brazing chamber 26. It will be appreciated that by introducing a gas into the brazing chamber 26, the quality of the brazed joint may be better controlled by limiting undesired inclusions in the brazed joint. In a following step 180, when the temperature of the first plate 38 reaches a temperature below the target temperature, the controller 66 sends a control signal to control operation of the induction spool 30 to deactivate the induction spool 30 and activates the second heating mechanism (e.g., wires 54) to heat the second plate 46 by the second heating mechanism (e.g., the wires 54 comprising the resistance heating mechanism) until the target temperature is reached. In some embodiments, the first and second predetermined temperatures of steps 160 and 170 may be higher than the temperature at which the controller 66 switches between the first and second heating mechanisms. The temperature at which the controller 66 switches between the first and second heating mechanisms may be represented by a percentage of the target temperature. The percentage of the target temperature may be, for instance, 90% of the target temperature. In other embodiments, the percentage of the target temperature may be 95% or another percentage.

[0027] Following heating of the first and second plates 38, 46 and joining of the first and second components 14, 18, to the target temperature, at step 180, the controller 66 receives a second signal from the second sensor 68b and sends a control signal to control operation of the resistance heating element to deactivate the second heating mechanism and activate the cooling source 64 to cool the brazing chamber 26. Once cooled, in the following step 200, the brazing chamber 26 is opened. Once opened, in step 210, the brazed assembly of the first and second components 14, 18 is removed from the brazing chamber 26.

[0028] FIG. 6A graphically illustrates the heating and cooling process, showing a complete heating and cooling cycle of the brazing apparatus 10. At step 140, the first plate is heated by the first heating mechanism. As the temperature increases toward the target temperature, at step 160, at a first predetermined temperature, a vacuum source is activated. At step 170, the gas source is activated. At step 180, at a temperature below the target temperature, heating of the first plate 38 is stopped and heating of the second plate begins. The first and second components s are heated by the second heating mechanism. At step 190, the cooling source is activated, theAttorney Docket No. 022233-0089- WO01 second heating mechanism is deactivated, and the brazing apparatus along with the first and second components are cooled.

[0029] FIG. 7 illustrates another exemplary method 300 of coupling at least two components into a brazed assembly by brazing. In a first step 310, the brazing chamber 26 of the brazing apparatus 10 is opened by moving (e.g., pivoting) the lid 42 and first plate 38 relative to the second plate 46 and base 50. In the following step 320, the first and second components 14, 18 are inserted into the brazing chamber 26 (e.g., by hand, by activation of a robot, etc.). The brazing chamber 26 is closed in the following step 330 by moving the first plate 38 and lid 42 relative to the second plate 46 and base 50. The first and second components 14, 18 may be clamped by the first and second plates 38, 46 or may be clamped by separated clamping assemblies within the brazing chamber 26. In the next step 340, the first plate 38 is heated by a first heating mechanism. In the exemplary method 300, the first heating mechanism is a resistance heating process in which the wires 54 heat the first plate 38. In another embodiment of the method 300, the first heating mechanism may be an inductive heating mechanism in which the first inductive spools 30 heats the first plate 38, which in turn conducts heat to the two or more components 14, 18 to be joined into a brazed assembly. In another embodiments, the first induction spool 30 heats the first plate 38 and the second induction spool heats the second plate 46. At step 350, beginning concurrently with step 340, or alternatively, with step 310 or at another step, the controller 66 receives signals from the first sensor 68a that indicates the temperature of the first plate 38 and monitors the temperature.

[0030] At step 360, at a first predetermined temperature that is less than a target temperature (e.g., a 400° C temperature of the first and / or second plate), the controller 66 activates the vacuum source 60 to remove the gas (e.g., air or nitrogen) within the brazing chamber 26 while the inductive spool 30 continues heating the first and second plate 38. In a following step 370, when the first plates 38 reaches a second predetermined temperature (e.g., 500°C) that is higher than the first predetermined temperature, but less than the target temperature, as measured by the first sensor 68a, the controller 66, in response to the temperature signals, activates the gas source 60 to introduce a gas (e.g., nitrogen) into the brazing chamber 26. It will be appreciated that by introducing a gas into the brazing chamber 26, the quality of the brazed joint may be better controlled by limiting undesired inclusions in the brazed joint. In a following step 380, theAttorney Docket No. 022233-0089- WO01 controller 66 continues heating the first plate 38 by the first heating mechanism until the target temperature is reached. At the following step 390, the controller 66 receives the signal from the temperature sensor 68a and sends a control signal to deactivate the first heating mechanism and activates the cooling source 64 to cool the brazing chamber 26. Once cooled, in the following step 400, the brazing chamber 26 is opened. Once opened, in step 410, the brazed assembly of the first and second components 14, 18 is removed from the brazing chamber 26.

[0031] FIG. 7A graphically illustrates the heating and cooling process, showing a complete heating and cooling cycle of the brazing apparatus 10. At steps 340 and 380, the first plate is heated by the first heating mechanism. As the temperature increases toward the target temperature, at step 360, at a first predetermined temperature, a vacuum source is activated. At step 370, the gas source is activated. At step 390, the cooling source is activated, the first heating mechanism is deactivated, and the brazing apparatus, and the first and second components are cooled.

[0032] The methods described above refer to heating either a first plate or a second plate of the brazing apparatus. It should be understood that the description is not limited to heating only the first plate or the second plate by the first heating mechanism or the second heating mechanism, but also contemplates heating the first and second plates by either the first heating mechanism or the second heating mechanism.

[0033] Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of one or more independent aspects of the invention as described. Various features of the invention are set forth in the following claims.

Claims

Attorney Docket No. 022233-0089- WOOlCLAIMSWhat is claimed is:

1. A brazing apparatus configured to couple a first component and a second component via a brazing process, the brazing apparatus comprising: a brazing chamber configured to receive the first component and the second component to be coupled, the brazing chamber including a first plate that is movable relative to a second plate and between which the first component and the second component are received; an induction spool operable to heat the first plate by induction heating; a resistance heating element operable to heat the second plate by resistance heating; an electronic control unit configured to selectively activate and deactivate the induction spool and the resistance heating element.

2. The brazing apparatus of claim 1, wherein the resistance heating element includes a plurality of wires disposed in channels in the first plate and the second plate.

3. The brazing apparatus of claim 2, wherein the induction spool is a first induction spool operable to inductively heat the first plate, the brazing apparatus further comprising a second induction spool configured to inductively heat the second plate.

4. The brazing apparatus of claim 1, wherein the first plate is pivotably coupled to the second plate.

5. The brazing apparatus of claim 1, wherein the first plate contacts the first component and the second plate contacts the second component.

6. The brazing apparatus of claim 1, wherein the first plate and the second plate are metal plates.

7. The brazing apparatus of claim 1, further comprising a vacuum source configured to generate a vacuum within the brazing chamber.

8. The brazing apparatus of claim 1, further comprising a gas source configured to introduce a gas into the brazing chamber.Attorney Docket No. 022233-0089- WOOl9. The brazing apparatus of claim 8, wherein the gas source is a nitrogen gas source.

10. The brazing apparatus of claim 1, wherein the electronic control unit receives a signal indicative of a temperature of the first plate, and controls operation of the induction spool and the resistance heating element based on the temperature of the first plate.

11. The brazing apparatus of claim 10, wherein the signal is a first signal and the electronic control unit receives a second signal indicative of a temperature of the second plate, and the electronic unit controls operation of the induction spool and the resistance heating element based on the temperature of the second plate.

12. A brazing apparatus configured to couple a first component and a second component via a brazing process, the brazing apparatus comprising: a brazing chamber configured to receive a first component and a second component, the brazing chamber including a first metal plate pivotably coupled to a second metal plate and between which the first component and the second component are received, the first component in contact with the first metal plate and the second component in contact with the second metal plate; an induction spool operable to inductively heat the first metal plate; a resistance heating element operable to heat the second metal plate; an electronic control unit configured to activate and deactivate the induction spool and the resistance heating element to heat the first component and the second component with the induction spool, the resistance heating element, or both the induction spool and the resistance heating element in a successive order.

13. The brazing apparatus of claim 12, further comprising a vacuum source coupled to the brazing chamber and configured to generate a vacuum within the brazing chamber.

14. The brazing apparatus of claim 12, further comprising a gas source configured to introduce a gas into the brazing chamber.

15. The brazing apparatus of claim 14, wherein the gas source is a nitrogen gas source.Attorney Docket No. 022233-0089- WOOl16. The brazing apparatus of claim 12, wherein the resistance heating element includes a first wire that is operable to heat the first plate and a second wire that is operable to heat the second plate.

17. The brazing apparatus of claim 12, wherein the induction spool is a first induction spool, the brazing apparatus further comprising a second induction spool operable to inductively heat the second metal plate.

18. The brazing apparatus of claim 12, wherein the electronic control unit receives a signal indicative of a temperature of the first metal plate, and sends a control signal to control operation of the induction spool.

19. The brazing apparatus of claim 12, wherein the electronic control unit receives a signal indicative of a temperature of the second metal plate and sends a control signal to control operation of the resistance heating element.

20. The brazing apparatus of claim 12, wherein the electronic control unit deactivates the induction spool and activates the resistance heating element at a temperature below a target temperature.

21. A method of coupling a first component and a second component by brazing comprising: opening a brazing chamber of a brazing apparatus, the brazing chamber including a first plate that is movable relative to a second plate; inserting the first component and the second component into the brazing chamber; closing the brazing chamber; heating the first plate by a first heating mechanism to increase a temperature of the first component and the second component to a first temperature that is less than a target temperature; heating the second plate by a second heating mechanism to increase the temperature of the components to the target temperature to join the first component and the second component into an assembly; opening the brazing chamber; removing the assembly from the brazing chamber.Attorney Docket No. 022233-0089- WOOl22. The method of claim 21, wherein the first plate is pivotably coupled to the second plate and opening and closing the brazing chamber includes pivoting the first plate relative to the second plate.

23. The method of claim 22, wherein the first heating mechanism is an induction heating mechanism in which an induction spool heats the first plate.

24. The method of claim 23, wherein the induction spool is a first induction spool configured to inductively heat the first plate, the method further comprising inductively heating the second plate with a second induction spool.

25. The method of claim 21, further comprising pulling a vacuum within the brazing chamber while heating the first plate when the first plate reaches a predetermined temperature that is less than the target temperature.

26. The method of claim 21, further comprising pulling a vacuum within the brazing chamber while heating the second plate when the second plate reaches a predetermined temperature that is less than the target temperature.

27. The method of claim 25, wherein the predetermined temperature is a first predetermined temperature, the method further comprising introducing a gas into the brazing chamber from a gas source when a temperature of the first plate or the second plate reaches a second predetermined temperature that is higher than the first predetermined temperature.

28. The method of claim 25, wherein the predetermined temperature is a first predetermined temperature, the method further comprising introducing a gas into the brazing chamber from a gas source when a temperature of the second plate reaches a second predetermined temperature that is higher than the first predetermined temperature.

29. The method of claim 27, wherein the gas source is a nitrogen gas source.

30. The method of claim 28, wherein the gas source is a nitrogen gas source.Attorney Docket No. 022233-0089- WOOl31. The method of claim 21, wherein an electronic control unit receives a signal indicating a temperature of the first plate and generating a control signal to control operation of the brazing apparatus.

32. The method of claim 31, wherein the signal is a first signal and the control signal is a first control signal, the electronic control unit receiving a second signal indicating a temperature of the second plate, and generating a second control signal to control operation of the brazing apparatus.

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