A heating unit, heating component, multi-zone heating device and sintering furnace

Abstract

This invention discloses a heating unit, a heating assembly, a multi-zone heating device, and a sintering furnace, belonging to the field of vacuum sintering furnace technology. The heating unit includes a first electrode, a second electrode, and an arc-shaped heating element. The arc-shaped heating element includes multiple arc-shaped heating plates arranged side by side. One end of each arc-shaped heating plate is connected in parallel to the first electrode, and the other end is connected in parallel to the second electrode. The heating assembly includes two heating units symmetrically arranged along a preset installation axis. The multi-zone heating device includes a heating system, which includes multiple heating assemblies spaced apart. The sintering furnace includes a furnace body and the multi-zone heating device. The arc-shaped heating plates have a sheet-like structure. A single arc-shaped heating plate has a larger heating area than a thin strip-shaped heating element. When multiple arc-shaped heating plates are arranged side by side, they can cover more space inside the furnace. The circuit structure is simple, and the design and calculation of the resistance and power of the heating unit are more convenient.

Description

Technical Field

[0001] This invention relates to the field of vacuum sintering furnace technology, and in particular to a heating unit, heating component, multi-zone heating device, and sintering furnace. Background Technology

[0002] Vacuum sintering furnaces are key equipment in the preparation processes of powder metallurgy, cemented carbide, ceramic materials, and refractory metals, and are widely used in high-temperature processing. Currently, this type of equipment generally adopts resistance heating, and the heating element material is mostly graphite, which has good electrical conductivity, high temperature resistance, and a certain mechanical strength to ensure the stability and uniformity of the heating process. However, the heating element of existing resistance heating structures is usually designed as a thin strip structure (refer to patents CN208079429U, CN223610600U, and CN211147277U), resulting in a small proportion of the heating area in the furnace chamber and insufficient heating coverage. This affects the uniformity of the temperature field during sintering, and restricts further improvement in heating efficiency and product quality. Summary of the Invention

[0003] The purpose of this invention is to solve the above-mentioned technical problems and provide a heating unit, heating component, multi-zone heating device and sintering furnace. The arc-shaped heating element has a sheet-like structure. A single arc-shaped heating element has a larger heating area than a thin strip heating element. When multiple arc-shaped heating elements are arranged side by side, they can cover more furnace space, reduce surface power, improve oxidation resistance, have milder thermal inertia of the heating element, reduce temperature fluctuation, and have a simple circuit structure. The resistance and power design and calculation of the heating unit are more convenient.

[0004] To achieve the above objectives, the present invention provides the following solution: The present invention discloses a heating unit, including a first electrode, a second electrode, and an arc-shaped heating element. The arc-shaped heating element includes a plurality of arc-shaped heating elements arranged side by side. One end of the plurality of arc-shaped heating elements is connected in parallel to the first electrode, and the other end of the plurality of arc-shaped heating elements is connected in parallel to the second electrode.

[0005] In one embodiment, a gap is reserved between any two adjacent arc-shaped heating elements.

[0006] In one embodiment, the arc-shaped heating element is a CC heating element.

[0007] In one embodiment, the arc-shaped heating element is provided with an adjustment hole for adjusting the local resistance.

[0008] In one embodiment, the adjustment hole includes a preset hole and / or a post-set hole; the preset holes are arranged in multiple rows along the width direction of the arc-shaped heating element, and a single row of preset holes extends along the arc length direction of the arc-shaped heating element; the post-set hole is used to be set on the arc-shaped heating element at the location where the resistance needs to be adjusted.

[0009] In one embodiment, the surface of the arc-shaped heating element is provided with a heat-resistant coating.

[0010] In one embodiment, both the first electrode and the second electrode include a conductive connector and an electrode rod. The conductive connector is used to connect the ends of the arc-shaped heating element in parallel, and the electrode rod is electrically connected to the conductive connector.

[0011] In one embodiment, the conductive connector includes an outer conductive connecting piece, the inner side of which is in contact with the outer arc surface of the arc-shaped heating element, and the outer side of which is connected to the electrode rod.

[0012] In one embodiment, the conductive connector includes an outer conductive connector and an inner conductive connector, which are detachably connected by a connecting assembly. The inner side of the inner conductive connector is in contact with the inner arc surface of the arc-shaped heating element, and the inner side of the outer conductive connector is in contact with the outer arc surface of the arc-shaped heating element. The outer side of the outer conductive connector is connected to the electrode rod.

[0013] In one embodiment, the connecting assembly includes a connecting screw and a connecting nut. The connecting screw passes through the outer conductive connecting piece, the inner conductive connecting piece, and the arc-shaped heating element. Both ends of the connecting screw are threaded with the connecting nut to press the outer conductive connecting piece, the inner conductive connecting piece, and the arc-shaped heating element together.

[0014] In one embodiment, the connecting screw is a CC screw, and the connecting nut is a graphite nut.

[0015] In one embodiment, the connection assembly further includes a pre-tightening member; The pre-tightening component includes an elastic sheet and a spacer sleeve. The spacer sleeve includes an open end and a closed end. The closed end of the spacer sleeve has a fitting hole for coaxially fitting onto the connecting screw. The closed end of the spacer sleeve is in contact with the inner side surface of the inner conductive connecting piece. The elastic sheet has a through hole for coaxially fitting onto the connecting screw. The elastic sheet is pressed against the open end of the spacer sleeve by a connecting nut near the inner conductive connecting piece. Alternatively, the pre-tightening component may include an elastic sheet and a spacer ring. The spacer ring includes an open end and a closed end. The closed end of the spacer ring is provided with a plurality of sleeve holes, which correspond one-to-one with the connecting screws on the inner conductive connecting piece. The sleeve holes are used for coaxially sleeved on the corresponding connecting screws. The closed end of the spacer ring is in contact with the inner surface of the inner conductive connecting piece. The elastic sheet is provided with a through hole for coaxially sleeved on the connecting screw. The elastic sheet is pressed against the open end of the spacer ring by a connecting nut close to the inner conductive connecting piece. Alternatively, the pre-tightening component may include an arc-shaped spring, which includes an arc-shaped section in the middle and connecting sections at both ends. The connecting sections are provided with connecting holes for coaxially sleeved on the connecting screws. The connecting sections at both ends are sleeved on two adjacent connecting screws through their respective connecting holes. The outer arc surface of the arc-shaped spring is in contact with the inner surface of the inner conductive connecting piece, so that the connecting section is pressed against the connecting nut near the inner conductive connecting piece.

[0016] In one embodiment, when the pretensioning member includes an elastic sheet and a spacer sleeve, the elastic sheet is a CC spring sheet and the spacer sleeve is a graphite sleeve; when the pretensioning member includes an elastic sheet and a spacer ring, the elastic sheet is a CC spring sheet and the spacer ring is a graphite sleeve; when the pretensioning member includes an arc-shaped spring sheet, the arc-shaped spring sheet is a CC arc-shaped sheet.

[0017] The present invention also discloses a heating component, comprising two heating units symmetrically arranged along a preset installation axis, wherein the arc-shaped heating elements of the two heating units face each other and are spaced apart.

[0018] In one embodiment, the conductive connectors of the two heating units are separated by an insulating pad.

[0019] In one embodiment, the electrode rod of the heating unit is fitted with an insulating sleeve to separate it from the heat insulation material on the furnace cavity wall.

[0020] The present invention also discloses a multi-zone heating device, including a heating system, wherein the heating system includes the aforementioned heating components arranged coaxially and at intervals along the preset mounting axis.

[0021] In one embodiment, a control system is also included, comprising a temperature monitoring module and an output power control module. The temperature monitoring module is used to monitor the heating temperature of the heating unit of each of the heating components, and the output power control module is used to control the heating power of the heating unit of each of the heating components. The temperature monitoring module and the output power control module are communicatively connected.

[0022] In one embodiment, the temperature monitoring module includes thermocouples corresponding to the heating units of each of the heating components.

[0023] In one embodiment, the output power control module includes a controller and a transformer. Each heating element of the heating component corresponds to a transformer. The first electrode and the second electrode of the heating element are electrically connected to their corresponding transformers. Each transformer is electrically connected to the controller.

[0024] In one embodiment, the control system further includes an alarm module, and the controller is electrically connected to the alarm module; the output power control module further includes a current transformer, and the transformer is electrically connected to the furnace wall through the current transformer, and the transformer is electrically connected to the alarm module.

[0025] The present invention also discloses a sintering furnace, including a furnace body and the aforementioned multi-zone heating device. The furnace body is provided with a cylindrical furnace cavity, and the preset installation axis of the multi-zone heating device is coaxially arranged with the central axis of the cylindrical furnace cavity.

[0026] The present invention achieves the following technical effects compared to the prior art: In this invention, the arc-shaped heating element has a sheet-like structure. Compared with the thin strip structure, a single arc-shaped heating element has a larger heating area. When multiple arc-shaped heating elements are arranged side by side, they can cover more furnace space. Moreover, the surface power is reduced, which improves the oxidation resistance and makes it more suitable for sintering AlN / SiN / SiC in an N2 environment. With the power density reduced, the thermal inertia of the heating element is milder and the temperature fluctuation is reduced. In addition, since the arc-shaped heating element has a sheet-like structure, its cross-sectional area is small, and the resistance is concentrated on the arc-shaped heating element. Multiple arc-shaped heating elements with the same resistance value are connected in parallel, which simplifies the circuit structure and makes the design and calculation of the resistance and power of the heating unit more convenient. For example, if the resistance of a heating element is R, then the overall resistance of the heating unit is (1 / n)R, and the resistance and power are easy to design and calculate.

[0027] Other technical solutions of the present invention have achieved the following technical effects compared with the prior art: Traditional heating elements are usually made of graphite, which has poor flexibility and is prone to breakage during installation, transportation and use. In contrast, the arc-shaped heating element in this invention uses CC material, which is a flexible material with advantages such as low density, low coefficient of thermal expansion, good high-temperature mechanical properties and high specific strength. It is not easy to break, easy to install, has a long service life, maintains stable roundness, heats up rapidly after being powered on, has a uniform and stable thermal field, has no aging problems, and can also reduce energy consumption. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained by analyzing these drawings without creative effort.

[0029] Figure 1 This is a three-dimensional structural diagram of the heating unit in an embodiment of the present invention; Figure 2 This is a three-dimensional structural diagram of the heating component in an embodiment of the present invention; Figure 3 This is a three-dimensional structural diagram of the multi-zone heating device in an embodiment of the present invention; Figure 4 This is a three-dimensional structural diagram of the heating unit (including preset holes) in an embodiment of the present invention; Figure 5 This is a three-dimensional structural diagram of the heating unit (including the preset hole and the post-set hole) in an embodiment of the present invention; Figure 6 This is a three-dimensional structural diagram of the heating unit (including the outer conductive connecting piece and the inner conductive connecting piece) in an embodiment of the present invention; Figure 7 This is a front view schematic diagram of the heating unit (including connecting screw and connecting nut) in an embodiment of the present invention; Figure 8 for Figure 7 A cross-sectional view of the MM section (including the connecting screw and connecting nut) of the heating unit; Figure 9 for Figure 8 A partially enlarged structural diagram of section I of the cross-sectional view of the heating unit; Figure 10 This is a three-dimensional structural diagram of the heating unit (including the elastic sheet and the spacer sleeve) in an embodiment of the present invention; Figure 11 This is a cross-sectional view of the outer conductive connecting piece and the inner conductive connecting piece (including the elastic piece and the spacer sleeve) in an embodiment of the present invention. Figure 12 This is a schematic diagram of the structure of the heating unit (including the elastic sheet and the spacer ring) in an embodiment of the present invention; Figure 13 This is a cross-sectional view of the outer conductive connecting piece and the inner conductive connecting piece (including the bow-shaped spring piece) in an embodiment of the present invention. Figure 14 This is a three-dimensional structural diagram of the heating component (including insulating pad and insulating sleeve) in an embodiment of the present invention; Figure 15This is a three-dimensional structural diagram of the multi-zone heating device (including insulating pads and insulating sleeves) in an embodiment of the present invention; Figure 16 This is a schematic diagram illustrating the temperature control principle of the multi-zone (eight-zone) heating device in an embodiment of the present invention; Figure 17 This is a schematic diagram illustrating the automatic ignition detection principle in an embodiment of the present invention; Figure 18 This is a circuit diagram of the heating unit in an embodiment of the present invention.

[0030] Explanation of reference numerals in the attached drawings: 1. Arc-shaped heating element; 2. Electrode rod; 3. Outer conductive connecting piece; 4. Inner conductive connecting piece; 5. Pre-set hole; 6. Rear-set hole; 7. Connecting screw; 8. Connecting nut; 9. Elastic sheet; 10. Spacer sleeve; 11. Spacer ring; 12. Bow-shaped spring; 13. Insulating pad; 14. Insulating sleeve; 15. Thermocouple; 16. Transformer; 17. Current transformer. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments analyzed and obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] The purpose of this invention is to provide a heating unit, heating component, multi-zone heating device, and sintering furnace to solve the problems existing in the prior art. The arc-shaped heating element has a sheet-like structure, and the heating area of ​​a single arc-shaped heating element is relatively larger. After multiple arc-shaped heating elements are arranged side by side, they can cover more furnace space, reduce surface power, improve oxidation resistance, have milder thermal inertia, reduce temperature fluctuation, and have a simple circuit structure. The resistance and power design and calculation of the heating unit are more convenient.

[0033] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] Example 1 like Figures 1 to 18As shown, this embodiment provides a heating unit, including a first electrode, a second electrode, and an arc-shaped heating element. The arc-shaped heating element includes multiple arc-shaped heating plates 1 arranged side by side. One end of each arc-shaped heating plate 1 is connected in parallel to the first electrode, and the other end is connected in parallel to the second electrode. The arc-shaped heating plate 1 has a sheet-like structure. Compared with a thin strip structure, a single arc-shaped heating plate 1 has a larger heating area, and multiple arc-shaped heating plates 1 arranged side by side can cover more furnace space. Moreover, the surface power is reduced, improving the oxidation resistance and making it more suitable for sintering AlN / SiN / SiC in an N2 environment. With the power density reduced, the thermal inertia of the heating element is milder, and the temperature fluctuation is reduced. In addition, since the arc-shaped heating plate 1 has a sheet-like structure, its cross-sectional area is small, and the resistance is concentrated on the arc-shaped heating plate 1. Multiple arc-shaped heating plates 1 with the same resistance value are connected in parallel, simplifying the circuit structure and making the design and calculation of the resistance and power of the heating unit more convenient. For example, if the resistance of one heating plate is R, then the overall resistance of the heating unit is (1 / n)R, making the resistance and power easier to design and calculate. For details, please refer to Figure 1 and Figure 18 As shown, a heating unit has four arc-shaped heating elements 1, so the overall resistance of the heating unit is (1 / 4)R.

[0035] In one embodiment of this invention, multiple arc-shaped heating elements 1 are arranged side-by-side with spacing between them. That is, a gap is reserved between any two adjacent arc-shaped heating elements 1. Normally, the spacing between multiple arc-shaped heating elements 1 is the same, meaning they are evenly distributed, resulting in a more uniform heat field distribution. However, the spacing between multiple arc-shaped heating elements 1 can also be different as needed. For example, the spacing can vary regularly, gradually increasing or decreasing in a gradient, or it can vary irregularly. For instance, if heat needs to be concentrated in a certain area, the spacing between two adjacent arc-shaped heating elements 1 in that area can be smaller, while the spacing in other areas can be larger. The specific spacing between the arc-shaped heating elements 1 can be designed according to the actual situation, and will not be elaborated further here. The reason for leaving a gap is that when the arc-shaped heating element composed of multiple arc-shaped heating elements 1 covers a sufficiently large area, further reducing the spacing has very limited effect on improving the uniformity of heating (marginal effect). Leaving a certain gap, rather than tightly fitting them together, is mainly to allow for the thermal expansion of the multiple heating elements. Otherwise, after high-temperature expansion, the heating elements will interfere with each other, leading to collisions and compression.

[0036] The following is a specific experimental example: Based on the heating power and surface power requirements, the thickness of the arc-shaped heating element 1 is controlled to be ≤3mm, the width to be ≤300mm, and the length to be ≤3000mm. Considering the uniformity of heating, the spacing between two adjacent arc-shaped heating elements 1 is controlled to be 2mm~300mm.

[0037] In one embodiment of this invention, the arc-shaped heating element 1 is formed by bending a rectangular sheet.

[0038] In one embodiment of this invention, the arc-shaped heating element 1 is a CC heating element. Traditional heating elements are usually made of graphite material, which has poor flexibility and is prone to breakage during installation, transportation, and use. CC heating elements, on the other hand, use CC material, also known as C / C composite material, which refers to a pure carbon multiphase structure composed of carbon fiber or its fabric as the reinforcing phase and chemically vapor-permeated pyrolytic carbon or liquid-phase impregnated-carbonized resin carbon or pitch carbon as the matrix. CC material has good flexibility, superior high-temperature mechanical properties compared to graphite, and is not sensitive to thermal stress; its coefficient of thermal expansion is only 1 / 5 to 1 / 10 that of metals, far lower than graphite, and shows almost no change at high temperatures; it has low density and can be designed as a thin sheet, making it lighter, while graphite is brittle and requires a certain thickness. Installation is easier, and it has stronger adaptability. CC material is highly flexible, with low stress at the joints, good contact surface, and adjustable distance between the electrode rods 2, allowing for the adaptation of heating elements of different lengths. Moreover, CC material can be molded in one piece, eliminating the need for multi-segment splicing structures like graphite to prevent cracking due to thermal expansion. Graphite heating elements require precise alignment and splicing during installation, and thermal expansion gaps must be allowed, making the process cumbersome and prone to affecting the thermal field due to seams. CC material, on the other hand, can be directly fixed, significantly simplifying the installation process and avoiding uneven localized temperatures caused by gaps. Transportation and maintenance are also more convenient; CC material is highly resilient and will not be damaged even by minor impacts during transport and installation, while graphite is brittle and can easily break with slight force during installation, requiring careful handling by specialized personnel and increasing installation costs and risks. Furthermore, CC material heating elements have a long lifespan, reducing the frequency of disassembly and replacement, further minimizing downtime costs during assembly and disassembly. The roundness of the heating element (the arc of the arc-shaped heating element 1) directly affects the uniformity of the thermal field inside the furnace. CC material has a significant advantage in terms of process and performance compared to graphite in this respect. Moreover, CC material can be prefabricated into a high-precision cylindrical preform through a three-dimensional weaving process, so that the preform is subjected to uniform stress in all directions. In contrast, graphite heating elements are mostly molded, and after high-temperature sintering, they are prone to slight elliptical deformation due to the release of internal stress, which is difficult to correct in subsequent processing. Under repeated high-temperature thermal shocks inside the furnace, the layered structure of graphite is prone to local protrusions due to thermal stress, which destroys the roundness. In CC material, thermal stress is buffered and dispersed by the fiber structure. Even after long-term use, the error can be controlled within a very small range. For example, the roundness deviation of existing graphite heating elements may expand to more than ±1mm after a period of use, while CC material heating elements can maintain a roundness tolerance within ±0.2mm for a long time.

[0039] In one embodiment of this invention, the arc-shaped heating element 1 is provided with adjustment holes. These holes are used to adjust the local resistance of the arc-shaped heating element 1, ensuring uniform resistance at all locations and preventing excessively high or low local resistance, thus resulting in more even heating. The adjustment principle is that drilling holes in the arc-shaped heating element 1 increases local resistance at the drilled areas. Therefore, by controlling the position, number, and diameter of the adjustment holes, the local resistance of the arc-shaped heating element 1 can be adjusted.

[0040] In one embodiment of this invention, the adjustment hole includes a preset hole 5 and / or a subsequent hole 6. That is, the arc-shaped heating element 1 may only have a preset hole 5 (see reference). Figure 4 As shown), preset holes 5 are used to arrange multiple rows along the width direction of the arc-shaped heating element 1. A single row of preset holes 5 extends along the arc length direction of the arc-shaped heating element 1, with adjacent rows of arc-shaped heating elements 1 arranged alternately. By drilling holes (preset holes 5) on the arc-shaped heating element 1, the weight of the arc-shaped heating element 1 is further reduced, and the resistance of the arc-shaped heating element 1 can be locally adjusted, resulting in more uniform heating. The staggered arrangement ensures structural strength. The arc-shaped heating element 1 can also have only post-set holes 6. Post-set holes 6 are only locally set, meaning that the arc-shaped heating element 1 only sets them at the location where the local resistance needs adjustment. This location is usually where the resistance is lower, to ensure consistent resistance throughout the arc-shaped heating element 1. Of course, preset holes 5 and post-set holes 6 can also be set simultaneously on the arc-shaped heating element 1 (see reference). Figure 5 As shown in the diagram, first, preset holes 5 are set on the arc-shaped heating element 1. After setting the preset holes 5, if there are still local areas with low resistance on the arc-shaped heating element 1, then subsequent holes 6 can be set. If there are no local areas with low resistance, then subsequent holes 6 are not needed. The purpose of first regularly drilling holes to form the preset holes 5, besides adjusting the resistance, is mainly to reduce weight. The subsequent holes 6 are used to increase the number of drilling positions as needed to further adjust the local resistance. The diameter and number of preset holes 5 and subsequent holes 6 are set according to the local resistance of the arc-shaped heating element 1. The optimal diameter can be selected by computer software simulation or experimental testing.

[0041] In one embodiment of this invention, a heat-resistant coating is provided on the surface of the arc-shaped heating element 1 to form a protective film on the surface of the arc-shaped heating element 1, preventing the arc-shaped heating element 1 from peeling off in sheets and increasing the lifespan of the heating element. Specifically, the heat-resistant coating can be a SiC coating or a TaC coating (tantalum carbide coating).

[0042] In one embodiment of this invention, both the first electrode and the second electrode include a conductive connector and an electrode rod 2. The conductive connector is used to connect the ends of the arc-shaped heating elements 1 in parallel, and the electrode rod 2 is electrically connected to the conductive connector. This achieves the following: one end of multiple arc-shaped heating elements 1 is connected in parallel to the first electrode, and the other end of multiple arc-shaped heating elements 1 is connected in parallel to the second electrode.

[0043] In one embodiment of this invention, the conductive connector has the following two specific structures.

[0044] Type 1: The conductive connector only includes the outer conductive connector piece 3 (reference) Figure 1 , Figure 2 , Figure 3 , Figure 4 as well as Figure 5 The outer surface of the outer conductive connecting piece 3 is connected to the electrode rod 2, and the inner surface of the outer conductive connecting piece 3 is connected to the outer arc surface of the arc-shaped heating element 1. The outer conductive connecting piece 3 and the arc-shaped heating element 1 can be stably connected by conductive adhesive.

[0045] The second type: The conductive connector includes both an outer conductive connecting piece 3 and an inner conductive connecting piece 4. The outer conductive connecting piece 3 and the inner conductive connecting piece 4 are interconnected, and can be detachably connected via a connecting assembly. All the arc-shaped heating elements 1 of the arc-shaped heating element are sandwiched between the outer conductive connecting piece 3 and the inner conductive connecting piece 4. The outer surface of the inner conductive connecting piece 4 is fitted with the inner arc surface of the arc-shaped heating element 1, and the inner surface of the outer conductive connecting piece 3 is fitted with the outer arc surface of the arc-shaped heating element 1. The outer surface of the outer conductive connecting piece 3 is connected to the electrode rod 2. The addition of the inner conductive connecting piece 4, in conjunction with the outer conductive connecting piece 3, forms a double-sided connection, making the connection more reliable.

[0046] The conductive connectors utilize sheet-like connecting pieces (outer conductive connecting piece 3 and inner conductive connecting piece 4), creating a larger contact area between the pieces. This results in a larger connection area between the conductive connectors and the arc-shaped heating element 1, ensuring reliable connection and effectively reducing arcing. The larger connection area also means more connection points (positions of the connecting screw 7 and connecting nut 8). Even if one or two of these connection points (connecting screw 7 and connecting nut 8) become loose, gaps will not form, preventing arcing. It is recommended that the width of the outer conductive connecting piece 3 and the inner conductive connecting piece 4 be approximately 80mm, but this can be adjusted according to actual needs and is not limited to this value.

[0047] In one embodiment of this invention, the electrode rod 2 is located at the center of the conductive connector, i.e., at the center of the outer conductive connector 3. Preferably, both the outer conductive connector 3 and the inner conductive connector 4 are rectangular sheets.

[0048] In one embodiment of this example, when the conductive connector adopts the second configuration, that is, when it includes both an outer conductive connector 3 and an inner conductive connector 4, the outer conductive connector 3 and the inner conductive connector 4 are detachably connected by a connecting assembly.

[0049] In one embodiment of this invention, the connecting assembly mainly includes a connecting screw 7 and connecting nuts 8. The connecting screw 7 passes through the outer conductive connecting piece 3, the inner conductive connecting piece 4, and the arc-shaped heating element 1. Through holes can be correspondingly provided on the outer conductive connecting piece 3, the inner conductive connecting piece 4, and the arc-shaped heating element 1 for the connecting screw 7 to pass through. Connecting nuts 8 are threaded onto both ends of the connecting screw 7 to press the outer conductive connecting piece 3, the inner conductive connecting piece 4, and the arc-shaped heating element 1 together. That is, tightening the connecting nuts 8 at both ends of the connecting screw 7 can press the outer conductive connecting piece 3 and the inner conductive connecting piece 4 together, clamping each arc-shaped heating element 1. When the connecting nuts 8 at both ends of the connecting screw 7 are unscrewed, the outer conductive connecting piece 3 and the inner conductive connecting piece 4 can be disassembled.

[0050] In one embodiment of this invention, the connecting screw 7 is a CC screw, and the connecting nut 8 is a graphite nut. The reason why the connecting nut 8 is made of graphite and the connecting screw 7 is made of CC material is that the structural strength of graphite is lower than that of CC material. Under the same stress conditions, graphite will fracture preferentially over CC material. After the outer conductive connecting piece 3, the inner conductive connecting piece 4, and the arc-shaped heating element 1 are connected by the connecting screw 7 and the connecting nut 8, stress concentration is unavoidable. Therefore, by actively using connecting screw 7 and connecting nut 8 made of different materials, the stress can be consciously (actively) guided to the connecting nut 8, causing the connecting nut 8 to fail before the connecting screw 7. The connecting nut 8 is also easier to detect and replace in a timely manner compared to the connecting screw 7.

[0051] In one embodiment of this example, the connecting assembly further includes a pre-tightening member, which can prevent the connecting nut 8 from loosening, making the connection more secure and adaptable to the furnace environment with frequent heating and cooling.

[0052] The pre-tightening components are configured in three ways: The first type: The pre-tightening component includes an elastic plate 9 and a spacer sleeve 10. The spacer sleeve 10 has an open end and a closed end. The closed end of the spacer sleeve 10 has a fitting hole for coaxially fitting onto the connecting screw 7. The closed end of the spacer sleeve 10 is in contact with the inner surface of the inner conductive connecting piece 4. The elastic plate 9 has a through hole for coaxially fitting onto the connecting screw 7. The elastic plate 9 is pressed against the open end of the spacer sleeve 10 by the connecting nut 8 near the inner conductive connecting piece 4. The diameter of the open end of the spacer sleeve 10 is larger than the outer diameter of the connecting nut 8. Because the elastic plate 9 deforms when pressed by the connecting nut 8, it provides pre-tightening force, making the connection more reliable.

[0053] The second type: The pre-tightening component includes an elastic plate 9 and a spacer ring 11. The spacer ring 11 has an open end and a closed end. The closed end of the spacer ring 11 has multiple sleeve holes, which correspond one-to-one with the connecting screws 7 on the inner conductive connecting piece 4. The sleeve holes are used for coaxially sleeved on the corresponding connecting screws 7. The closed end of the spacer ring 11 is in contact with the inner surface of the inner conductive connecting piece 4. The elastic plate 9 has through holes for coaxially sleeved on the connecting screws 7. The elastic plate 9 is pressed against the open end of the spacer ring 11 by the connecting nut 8 near the inner conductive connecting piece 4. Because the elastic plate 9 deforms when pressed by the connecting nut 8, it provides pre-tightening force, making the connection more reliable. Compared with the first type, where each connecting screw 7 needs to be fitted with a spacer sleeve 10, the second type uses a spacer ring 11 instead of multiple spacer sleeves 10, which reduces the number of parts while still providing a fastening function.

[0054] The third type: The pre-tightening component includes an arc-shaped spring 12, which comprises an arc-shaped section in the middle and connecting sections at both ends. The connecting sections are provided with connecting holes for coaxially fitting onto the connecting screws 7. The connecting sections at both ends are fitted onto the two adjacent connecting screws 7 through their respective connecting holes. The outer arc surface of the arc-shaped spring 12 fits against the inner surface of the inner conductive connecting piece 4, so that the connecting section is pressed against the connecting nut 8 near the inner conductive connecting piece 4. The elastic pre-tightening force of the arc-shaped spring 12 can play a role in preventing loosening, making the connection more secure and adaptable to the furnace environment of frequent heating and cooling.

[0055] In one embodiment of this invention, when the pretensioning component includes an elastic sheet 9 and a spacer sleeve 10, the elastic sheet 9 can be a CC spring sheet, and the spacer sleeve 10 can be a graphite sleeve. When the pretensioning component includes an elastic sheet 9 and a spacer ring 11, the elastic sheet 9 can be a CC spring sheet, and the spacer ring 11 can be a graphite sleeve. When the pretensioning component includes an arc-shaped spring sheet 12, the arc-shaped spring sheet 12 is a CC arc-shaped sheet. The spacer sleeve 10 and the spacer ring 11 are made of graphite instead of CC material mainly for cost considerations. Although CC material has better strength, it is more expensive, while using graphite material for the spacer sleeve 10 and the spacer ring 11 can meet the strength requirements and reduce costs; of course, any material with the required strength can be used in this structure.

[0056] Example 2 like Figures 1 to 18As shown, this embodiment provides a heating component, including two heating units as described in Embodiment 1. The two heating units are symmetrically arranged along a preset installation axis. The arc-shaped heating elements of the two heating units face each other and are spaced apart, forming a cylindrical structure. The two heating units can be independently controlled through their respective first and second electrodes, thus forming a basic two-zone heating element. After the heating component is installed in the furnace cavity, if the two heating units are arranged vertically (with the preset installation axis set horizontally), two heating zones are formed, one above the other. If the two heating units are arranged horizontally (with the preset installation axis set vertically), two heating zones are formed, one to the left and one to the right. The spacing between the arc-shaped heating elements of the two heating units can prevent accidental contact and sparking. The recommended spacing is 2mm to 300mm, but it can be adjusted according to actual needs and is not limited to this range.

[0057] In one embodiment of this invention, the conductive connectors (mainly the outer conductive connectors 3) of the two heating units are separated by an insulating pad 13, which can effectively prevent arcing caused by accidental contact between the arc-shaped heating elements of the two heating units.

[0058] In one embodiment of this example, an insulating sleeve 14 is provided on the electrode rod 2 of the heating unit. The insulating sleeve 14 is used to separate the electrode rod 2 from the heat insulation material (not shown) on the furnace cavity wall to prevent the electrode rod 2 from contacting the heat insulation material and causing sparking.

[0059] In one embodiment of this example, both the insulating pad 13 and the insulating sleeve 14 can be made of BN ceramic material, where BN is the abbreviation for boron nitride, and BN ceramic is also known as "white graphite".

[0060] Example 3 like Figures 1 to 18 As shown, this embodiment provides a multi-zone heating device, including a heating system comprising multiple heating components as described in Embodiment 2. The multiple heating components are coaxial along a preset mounting axis and spaced apart. The recommended spacing is 2mm to 300mm, but can be adjusted according to actual needs and is not limited to this range. One heating component is a basic two-zone heating device. When this heating component is expanded (to multiple heating components), it can be designed as a four-zone (two heating components), six-zone (three heating components), eight-zone (four heating components), or higher heating device to adapt to different furnace types. The spacing setting prevents accidental ignition between adjacent heating components.

[0061] In one embodiment of this invention, taking the furnace cavity as a reference, the two heating units of each heating component can be arranged in the same orientation (e.g., both heating units of each heating component are arranged vertically, or both are arranged horizontally), or they can be arranged in different orientations (e.g., both heating units of the first heating component are arranged vertically, and the two heating units of the remaining heating components are arranged horizontally). The specific arrangement can be determined according to actual needs. (Refer to...) Figure 3 and Figure 16 As shown, this is an eight-zone heating device with a total of four heating components. The two heating units of each heating component are arranged vertically to form upper heating zone ①, upper heating zone ②, upper heating zone ③, upper heating zone ④, lower heating zone ①, lower heating zone ②, lower heating zone ③, and lower heating zone ④. Each heating zone (eight zones) can be controlled independently.

[0062] In one embodiment of this invention, a control system is further included. The control system includes a temperature monitoring module and an output power control module. The temperature monitoring module is used to monitor the heating temperature of the heating unit of each heating component. The output power control module is used to control the heating power of the heating unit of each heating component. The temperature monitoring module and the output power control module are communicatively connected.

[0063] In one embodiment of this invention, the temperature monitoring module includes thermocouples 15 corresponding to heating units of each heating component. Taking an eight-zone heating device as an example, refer to... Figure 3 , Figure 16 as well as Figure 17 As shown, each of the eight heating units (upper heating field ①, upper heating field ②, upper heating field ③, lower heating field ④, lower heating field ①, lower heating field ②, lower heating field ③, and lower heating field ④) corresponds to a thermocouple 15 (Thc①, Thc③, Thc⑤, Thc⑦, Thc②, Thc④, Thc⑥, and Thc⑧, respectively). Thc① monitors the real-time temperature PV① of upper heating field ①, Thc② monitors the real-time temperature PV② of lower heating field ①, and so on. Note: PV represents the process variable.

[0064] In one embodiment of this invention, the output power control module includes a controller and a transformer 16. Each heating element of the heating component corresponds to a transformer 16. The first and second electrodes of the heating element are electrically connected to their corresponding transformers 16, and each transformer 16 is electrically connected to the controller. Specifically, by controlling the transformers 16 through the controller, the heating power of each heating element can be controlled.

[0065] In one embodiment of this invention, there is only one controller. Each heating unit can be controlled separately by a single controller.

[0066] In one embodiment of this invention, the controller may be a PID controller, which can control each heating unit individually. The transformer 16 may be an SCR transformer (SCR is an abbreviation for Silicon Controlled Rectifier).

[0067] Taking an eight-zone heating device as an example, refer to Figure 3 , Figure 16 as well as Figure 17 As shown, each of the eight heating units (upper heating field ①, upper heating field ②, upper heating field ③, lower heating field ④, lower heating field ①, lower heating field ②, lower heating field ③ and lower heating field ④) corresponds to a thermocouple 15 (Thc①, Thc③, Thc⑤, Thc⑦, Thc②, Thc④, Thc⑥ and Thc⑧, respectively).

[0068] The user sets the target temperature SV and sends it to the PID controller. The thermocouple 15 (Thc) of each heat field (heating unit) monitors the real-time temperature PV of that area and sends it to the PID controller. The PID controller automatically calculates the heating power required by the arc-shaped heating element 1 of each heat field (heating unit) based on the target temperature SV and the real-time temperature PV of the eight heat fields (heating units). Then, it sends the heating power to the corresponding transformer 16. The transformer 16 controls the heating power of the arc-shaped heating element 1 through power percentage output, so that the real-time temperature PV of the eight heat fields (heating units) simultaneously approaches the target temperature SV.

[0069] Unified PID temperature control is suitable for large furnaces with more zones, and the control is more stable due to the comprehensive temperature changes between different zones.

[0070] In one embodiment of this invention, the control system further includes an alarm module, and the controller (PID controller) is electrically connected to the alarm module. The PID controller monitors the voltage and current in real time and can automatically determine leakage, arcing, and heating element wear based on current changes. If the current exceeds the normal range, it indicates leakage; if the current suddenly increases to a peak value, it indicates arcing; if the current is below the normal range, it indicates excessive wear of the heating element. The alarm module includes, but is not limited to, audible and visual alarms, APP message push alarms, and central control console push alarms.

[0071] In one embodiment of this invention, the output power control module further includes a current transformer 17. The transformer 16 is electrically connected to the furnace wall via the current transformer 17, and the transformer 16 is also electrically connected to the alarm module. Specifically, both ends of the transformer 16 are connected to the electrode rods 2 of the first electrode and the second electrode, respectively, to provide heating power to the heating element. A middle tap is led out from the middle of the transformer 16 and connected to the furnace wall, and a current transformer 17 is installed on the wire at this location.

[0072] When each arc-shaped heating element 1 is working normally, the furnace wall is not energized, and the current transformer 17 will not detect current. When the electrode rod 2 of the first electrode or the electrode rod 2 of the second electrode accidentally touches the furnace wall and causes sparking, the furnace wall and the transformer 16 form a circuit, the current transformer 17 detects current, the controller (PID controller) recognizes the sparking of the equipment, and the alarm module issues an alarm.

[0073] Example 4 This embodiment provides a sintering furnace, including a furnace body and the multi-zone heating device in Embodiment 3. The furnace body is provided with a cylindrical furnace cavity, and the preset installation axis of the multi-zone heating device is coaxial with the central axis of the cylindrical furnace cavity.

[0074] In one embodiment of this invention, the two heating units of each heating component are arranged vertically, forming multiple upper thermal fields and multiple lower thermal fields.

[0075] In one embodiment of this example, the sintering furnace is a vacuum sintering furnace.

[0076] This invention has the following advantages: (1) The heating element is a thin sheet type and is evenly and densely arranged, with a larger heating area, covering more furnace space and a more uniform heat field distribution; the surface power is reduced, which improves the oxidation resistance and makes it more suitable for sintering AlN / SiN / SiC in N2 (nitrogen) environment; after the power density is reduced, the thermal inertia of the heating element is milder and the temperature fluctuation is reduced. (2) Using new flexible materials such as CC, it is not easy to break, easy to install, has a long service life, and the roundness (arc of the arc heating element 1) remains stable. After being powered on, it heats up quickly, the heat field is uniform and stable, there is no aging problem, and energy consumption can also be reduced. (3) The structure is simple and clear, with fewer types of components, making processing and installation more convenient; (4) The circuit structure is simple and the design and calculation of the resistance and power of the heating element are convenient; (5) Unified PID temperature control is applicable to large furnaces with more zones, and the temperature changes between different zones are more stable.

[0077] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A heating unit, characterized in that, It includes a first electrode, a second electrode, and an arc-shaped heating element. The arc-shaped heating element includes multiple arc-shaped heating elements (1) arranged side by side. One end of the multiple arc-shaped heating elements (1) is connected in parallel to the first electrode, and the other end of the multiple arc-shaped heating elements (1) is connected in parallel to the second electrode.

2. The heating unit according to claim 1, characterized in that, A gap is reserved between any two adjacent arc-shaped heating elements (1).

3. The heating unit according to claim 1 or 2, characterized in that, The arc-shaped heating element (1) is a CC heating element.

4. The heating unit according to claim 1 or 2, characterized in that, The arc-shaped heating element (1) is provided with an adjustment hole for adjusting the local resistance.

5. The heating unit according to claim 4, characterized in that, The adjustment hole includes a preset hole (5) and / or a rear-mounted hole (6); the preset holes (5) are arranged in multiple rows along the width direction of the arc-shaped heating element (1), and a single row of preset holes (5) extends along the arc length direction of the arc-shaped heating element (1); the rear-mounted hole (6) is used to be set on the arc-shaped heating element (1) where the resistance needs to be adjusted.

6. The heating unit according to claim 1, characterized in that, The surface of the arc-shaped heating element (1) is provided with a heat-resistant coating.

7. The heating unit according to claim 1, characterized in that, Both the first electrode and the second electrode include a conductive connector and an electrode rod (2). The conductive connector is used to connect the ends of the arc-shaped heating element (1) in parallel, and the electrode rod (2) is electrically connected to the conductive connector.

8. The heating unit according to claim 7, characterized in that, The conductive connector includes an outer conductive connector (3), the inner side of which is in contact with the outer arc surface of the arc-shaped heating element (1), and the outer side of which is connected to the electrode rod (2).

9. The heating unit according to claim 7, characterized in that, The conductive connector includes an outer conductive connector (3) and an inner conductive connector (4). The outer conductive connector (3) and the inner conductive connector (4) are detachably connected by a connecting assembly. The outer side of the inner conductive connector (4) is in contact with the inner arc surface of the arc-shaped heating element (1). The inner side of the outer conductive connector (3) is in contact with the outer arc surface of the arc-shaped heating element (1). The outer side of the outer conductive connector (3) is connected to the electrode rod (2).

10. The heating unit according to claim 9, characterized in that, The connecting assembly includes a connecting screw (7) and a connecting nut (8). The connecting screw (7) is used to pass through the outer conductive connecting piece (3), the inner conductive connecting piece (4), and the arc-shaped heating element (1). Both ends of the connecting screw (7) are threaded with the connecting nut (8) to press the outer conductive connecting piece (3), the inner conductive connecting piece (4), and the arc-shaped heating element (1) together.

11. The heating unit according to claim 10, characterized in that, The connecting screw (7) is a CC screw, and the connecting nut (8) is a graphite nut.

12. The heating unit according to claim 10 or 11, characterized in that, The connection assembly also includes a pre-tightening member; The pre-tightening component includes an elastic sheet (9) and a spacer sleeve (10). The spacer sleeve (10) includes an open end and a closed end. The closed end of the spacer sleeve (10) is provided with a fitting hole for coaxially fitting onto the connecting screw (7). The closed end of the spacer sleeve (10) is in contact with the inner side of the inner conductive connecting piece (4). The elastic sheet (9) is provided with a through hole for coaxially fitting onto the connecting screw (7). The elastic sheet (9) is pressed against the open end of the spacer sleeve (10) by a connecting nut (8) near the inner conductive connecting piece (4). Alternatively, the pre-tightening component may include an elastic sheet (9) and a spacer ring (11). The spacer ring (11) includes an open end and a closed end. The closed end of the spacer ring (11) is provided with a plurality of sleeve holes, which correspond one-to-one with the connecting screws (7) on the inner conductive connecting piece (4). The sleeve holes are used to be coaxially sleeved on the corresponding connecting screws (7). The closed end of the spacer ring (11) is in contact with the inner side surface of the inner conductive connecting piece (4). The elastic sheet (9) is provided with a through hole for coaxially sleeved on the connecting screws (7). The elastic sheet (9) is pressed against the open end of the spacer ring (11) by a connecting nut (8) close to the inner conductive connecting piece (4). Alternatively, the pre-tightening component may include an arc-shaped spring (12), which includes an arc-shaped section in the middle and connecting sections at both ends. The connecting sections are provided with connecting holes for coaxially sleeved on the connecting screws (7). The connecting sections at both ends are sleeved on the two adjacent connecting screws (7) through their respective connecting holes. The outer arc surface of the arc-shaped spring (12) is in contact with the inner side surface of the inner conductive connecting piece (4) so ​​that the connecting section is pressed against the connecting nut (8) near the inner conductive connecting piece (4).

13. The heating unit according to claim 12, characterized in that, When the pre-tightening component includes an elastic sheet (9) and a spacer sleeve (10), the elastic sheet (9) is a CC spring sheet and the spacer sleeve (10) is a graphite sleeve; when the pre-tightening component includes an elastic sheet (9) and a spacer ring (11), the elastic sheet (9) is a CC spring sheet and the spacer ring (11) is a graphite sleeve; when the pre-tightening component includes an arc-shaped spring sheet (12), the arc-shaped spring sheet (12) is a CC arc-shaped sheet.

14. A heating element, characterized in that, It includes two heating units as described in any one of claims 1-13, which are symmetrically arranged along a preset installation axis, wherein the arc-shaped heating elements of the two heating units face each other and are spaced apart.

15. The heating component according to claim 14, characterized in that, The conductive connectors of the two heating units are separated by an insulating pad (13).

16. The heating component according to claim 15, characterized in that, The electrode rod (2) of the heating unit is fitted with an insulating sleeve (14) to separate it from the heat insulation material on the furnace wall.

17. A multi-zone heating device, characterized in that, The system includes a heating system comprising heating components as described in any one of claims 14-16, which are coaxially arranged and spaced apart along the preset mounting axis.

18. The multi-zone heating device according to claim 17, characterized in that, It also includes a control system, which includes a temperature monitoring module and an output power control module. The temperature monitoring module is used to monitor the heating temperature of the heating unit of each of the heating components, and the output power control module is used to control the heating power of the heating unit of each of the heating components. The temperature monitoring module and the output power control module are communicatively connected.

19. The multi-zone heating device according to claim 18, characterized in that, The output power control module includes a controller and a transformer (16). Each heating unit of the heating component corresponds to a transformer (16). The first electrode and the second electrode of the heating unit are electrically connected to their corresponding transformers (16). Each transformer (16) is electrically connected to the controller.

20. The multi-zone heating device according to claim 19, characterized in that, The control system also includes an alarm module, and the controller is electrically connected to the alarm module; the output power control module also includes a current transformer (17), and the transformer (16) is electrically connected to the furnace wall through the current transformer (17), and the transformer (16) is electrically connected to the alarm module.

21. A sintering furnace, characterized in that, The device includes a furnace body and a multi-zone heating device as described in any one of claims 17-20, wherein the furnace body is provided with a cylindrical furnace cavity, and the preset installation axis of the multi-zone heating device is coaxially arranged with the central axis of the cylindrical furnace cavity.

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