A vacuum heat setting process and device for capacitor elements

Abstract

The present invention provides a capacitor element vacuum heat setting process and device, which relates to the field of capacitor processing technology. The vacuum heat setting process includes: placing the capacitor element in a closed space and performing a vacuuming operation; filling the closed space after the vacuuming operation with an inert gas; heating the closed space with heating oil, and controlling the temperature in the closed space to rise stepwise between the initial heating temperature point and the final heating temperature point; performing a second vacuuming operation in the closed space; filling the closed space after the second vacuuming with an inert gas; and controlling the temperature in the closed space to drop stepwise between the initial cooling temperature point and the final cooling temperature point. The present invention can solve the problem of uneven heating of capacitor elements and poor thermal polymerization effect of the film layer during the heat setting process.

Description

Technical Field

[0001] The present invention relates to the technical field of capacitors, and in particular to a vacuum heat setting process and device for capacitor elements. Background Art

[0002] At present, the heat setting process of metallized film capacitors generally adopts a single high temperature (95~110℃) and a long time (4~15h) to heat set the capacitor elements, and mainly uses electric heating wire as the heat source and air as the heat transfer medium to achieve the setting effect. However, after a period of use, the finished metallized film capacitors are prone to capacitor explosion, melting, fire, or capacity decay beyond the established range. After disassembling and inspecting the failed capacitors, the internal metallized film is generally corroded by electricity or the metal coating is missing, resulting in a reduction in effective area and a decrease in capacity. In severe cases, it affects the normal operation of the circuit, causing abnormal increase in voltage and current and other safety accidents.

[0003] By disassembling and confirming the defective products, it was found that compared with qualified products, the disassembly and peeling process of the inner film layer of the defective products was easier, without adhesion or pulling. After arranging temperature sensors at multiple temperature points inside the electrothermal shaping equipment and monitoring the actual temperature, it was found that when the set maximum temperature was reached and the temperature was kept constant, the maximum temperature difference at different points reached more than 15°C, which shows that the temperature uniformity in the electrothermal shaping equipment is poor, which affects the thermal shaping effect of the capacitor, and then causes poor thermal polymerization effect and poor consistency of the inner film layer of the capacitor element. Summary of the invention

[0004] The invention aims to solve the problem that capacitor elements are heated unevenly and the thermal polymerization effect of the film layer is poor during the thermal setting process.

[0005] In order to solve the above problems, the present invention provides a capacitor element vacuum heat setting process and device. And adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a vacuum heat setting process for a capacitor element, the vacuum heat setting process comprising the following steps:

[0007] Place the capacitor element in a confined space and evacuate it once;

[0008] Filling the enclosed space after the vacuum pumping with inert gas;

[0009] The enclosed space is heated by heating oil, and the temperature in the enclosed space is controlled to rise stepwise between an initial heating temperature point and a final heating temperature point, wherein the initial heating temperature point is 60° C. to 65° C., and the final heating temperature point is 100° C. to 115° C.;

[0010] Performing secondary vacuuming in the confined space;

[0011] Filling the enclosed space after the second vacuuming with inert gas;

[0012] The temperature in the enclosed space is controlled to decrease stepwise between an initial cooling temperature point and a final cooling temperature point, wherein the initial cooling temperature point is 85°C to 90°C, and the final cooling temperature point is 45°C to 50°C.

[0013] Optionally, the time for the vacuum pumping is 90 min to 100 min, and the vacuum degree after the vacuum pumping is 55 Pa to 65 Pa.

[0014] Optionally, the time for the second vacuum pumping is 90 min to 100 min, and the vacuum degree after the second vacuum pumping is 5 Pa to 10 Pa.

[0015] Optionally, after the enclosed space is filled with inert gas after the first vacuumization and the second vacuumization, the vacuum degree of the enclosed space is 9000Pa to 10000Pa.

[0016] Optionally, the step of introducing heating oil into the first heating oil pipe to control the temperature in the enclosed space to rise stepwise between an initial heating temperature point and a final heating temperature point comprises:

[0017] First, the temperature in the enclosed space is controlled to be maintained at the initial heating temperature point, the first heating temperature point, the second heating temperature point and the third heating temperature point for 90 minutes to 100 minutes respectively, and then the temperature in the enclosed space is controlled to be maintained at the final heating temperature point for 320 minutes to 340 minutes;

[0018] Wherein, the first heating temperature point is 70°C to 75°C, the second heating temperature point is 80°C to 85°C, and the third heating temperature point is 90°C to 95°C.

[0019] Optionally, the heating time of the initial heating temperature point, the first heating temperature point, the second heating temperature point, the third heating temperature point and the final heating temperature point are all 30 minutes to 35 minutes.

[0020] Optionally, controlling the temperature in the enclosed space to decrease stepwise between an initial cooling temperature point and a final cooling temperature point comprises: controlling the temperature in the enclosed space to be maintained at the initial cooling temperature point, the first cooling temperature point, the second cooling temperature point, the third cooling temperature point and the final cooling temperature point for 30 minutes to 40 minutes respectively;

[0021] Wherein, the first cooling temperature point is 75°C to 80°C, the second cooling temperature point is 65°C to 70°C, and the third cooling temperature point is 55°C to 60°C.

[0022] Optionally, the cooling time of the initial cooling temperature point, the first cooling temperature point, the second cooling temperature point, the third cooling temperature point and the final cooling temperature point are all 60 minutes to 65 minutes.

[0023] In a second aspect, the present invention provides a vacuum heat setting device, which is used to implement the above-mentioned capacitor element vacuum heat setting process, and the vacuum heat setting device includes an oven and a first heating oil pipe arranged in the oven, the first heating oil pipe is reciprocated along the width direction of the oven and extends toward the height direction of the oven, the number of the first heating oil pipes is multiple groups, and the multiple groups of the first heating oil pipes are parallel and spaced apart along the length direction of the oven;

[0024] The vacuum heat setting device further comprises a vacuum pumping component and an inert gas replenishing mechanism, and the vacuum pumping component and the inert gas replenishing mechanism are respectively communicated with the interior of the oven.

[0025] Optionally, it further includes a second heating oil pipe arranged on the inner side of the oven, wherein the second heating oil pipe is reciprocated and coiled along the length direction of the oven and extends toward the height direction of the oven.

[0026] The beneficial effects of the present invention compared to the prior art are:

[0027] Compared with conventional heat setting equipment using electric heating wires and air heat transfer, the present invention places the metallized film capacitor element in a confined space and further forms a vacuum environment, and uses heating oil as a heat transfer medium to transfer heat to the capacitor element by heat diffusion. At the same time, compared with conventional heat setting processes with high temperatures (95~110°C) and long times (4~15h), the present invention uses step-by-step heating and step-by-step cooling to achieve heat setting of capacitor elements, which is conducive to uniform heating of capacitor elements and avoids the quality of capacitor elements being affected by extremely rapid heating or extremely rapid cooling. Before step-by-step heating and step-by-step cooling, vacuuming and inert gas filling are performed, which is conducive to ensuring the vacuum degree of the entire heat setting process stage in the oven and avoiding oxidation of the end face of the element at high temperatures. According to the temperature result data of each temperature monitoring point, the use of the first heating oil pipe of the present invention to heat set the metallized film capacitor element can quickly and evenly transfer heat to various parts of the capacitor, thereby improving the efficiency and quality of heat setting. The temperature difference of each temperature monitoring point on the tooling where the capacitor element is located is small, meeting the requirement of being within 2°C, which is conducive to uniform heating of the capacitor element and consistent thermal polymerization effect, so that the shaping effect is good and the shaping is complete. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic structural diagram of a vacuum heat setting device in Example 1 of the present invention;

[0029] Figure 2 The temperature of each point of the tooling in Example 1 of the present invention changes with time;

[0030] Figure 3 It is a graph showing the temperature variation over time at each point on the tooling of the comparative example of the present invention;

[0031] Figure 4 This is a side view of the oven in Example 2 of the present invention;

[0032] Figure 5 A schematic diagram of the internal plating layer of a capacitor prepared by the hot forming process of Example 1 of the present invention after a charge and discharge test;

[0033] Figure 6 A schematic diagram of the internal plating of a capacitor prepared by a comparative example hot forming process after a charge and discharge test;

[0034] Figure 7 A schematic diagram of the internal plating layer of a capacitor prepared by the thermoforming process of Example 1 of the present invention after life testing;

[0035] Figure 8 A schematic diagram of the internal plating of a capacitor prepared by a comparative thermoforming process after a life test;

[0036] Description of reference numerals:

[0037] 1. Oven; 11. Box body; 12. Movable door; 2. First heating oil pipe; 21. Winding unit; 3. Second heating oil pipe; 4. First mounting frame; 41. Positioning hole; 5. Second mounting frame; 6. Storage cavity; 7. Storage channel; 8. Storage rack; 81. Storage layer. DETAILED DESCRIPTION

[0038] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. Although certain embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be interpreted as being limited to the embodiments described herein. On the contrary, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the drawings and embodiments of the present invention are only for exemplary purposes and are not intended to limit the scope of protection of the present invention.

[0039] The Z axis in the drawings represents the vertical direction, that is, the up and down position, and the positive direction of the Z axis represents the top, and the reverse direction of the Z axis represents the bottom; the X axis in the drawings represents the horizontal direction, and is designated as the front and back position, and the positive direction of the X axis represents the front side, and the reverse direction of the X axis represents the back side; the Y axis in the drawings represents the left and right position, and the positive direction of the Y axis represents the left side, and the reverse direction of the Y axis represents the right side. It should also be noted that the aforementioned Z axis, Y axis, and X axis are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0040] The term "including" and its variations used in this document are open inclusions, that is, "including but not limited to"; the term "based on" means "based at least in part on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one other embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiments". The relevant definitions of other terms will be given in the following description. It should be noted that the concepts of "first", "second", etc. mentioned in the present invention are only used to distinguish different devices, modules or units, and are not used to limit the order or interdependence of the functions performed by these devices, modules or units.

[0041] It should be noted that the modifications of "one" and "plurality" mentioned in the present invention are illustrative rather than restrictive, and those skilled in the art should understand that, unless otherwise clearly indicated in the context, it should be understood as "one or more".

[0042] Metallized film capacitors are electronic components that are made of metallized film that is rolled into a certain shape through a winding device and then coated on the outer layer or loaded into a shell. The preparation process of metallized film capacitors specifically includes the steps of material preparation, winding, loading into tooling, heat setting, gold spraying, energization, welding, packaging, epoxy pouring, curing and finished product testing. Among them, the heat setting process has a particularly significant impact on the quality of the finished product. The heat setting process is specifically a special processing process that fixes the shape of the core or component of the metallized film capacitor and heat-polymerizes the internal film material in a closed device with temperature and time control to fix its shape.

[0043] In order to solve the problem that capacitor elements are heated unevenly and the thermal polymerization effect of the film layer is poor during the heat setting process, an embodiment of the present invention provides a vacuum heat setting process and device for capacitor elements.

[0044] As a first aspect, the present invention provides a capacitor element vacuum heat setting process, which is based on a vacuum heat setting device. The vacuum heat setting device includes an oven and a first heating oil pipe, the first heating oil pipe includes a first heating oil pipe arranged in the oven, the first heating oil pipe is reciprocated along the width direction of the oven and extends toward the height direction of the oven. The vacuum heat setting process includes the following steps:

[0045] S1: Place the capacitor element in a confined space and perform vacuuming;

[0046] S2: Filling the enclosed space after the vacuum pumping with inert gas;

[0047] S3: heating the enclosed space by heating oil, and controlling the temperature in the enclosed space to rise stepwise between the initial heating temperature point and the final heating temperature point, wherein the initial heating temperature point is 60°C to 65°C, and the final heating temperature point is 100°C to 115°C;

[0048] S4: Perform secondary vacuuming in the confined space;

[0049] S5: Filling the enclosed space after secondary vacuuming with inert gas;

[0050] S6: Control the temperature in the enclosed space to drop step by step between the initial cooling temperature point and the final cooling temperature point, the initial cooling temperature point is 85°C to 90°C, and the final cooling temperature point is 45°C to 50°C.

[0051] Compared with conventional heat setting equipment using electric heating wire and air heat transfer, the present invention places the metallized film capacitor element in a confined space and further forms a vacuum environment. By using heating oil as a heat transfer medium, heat is transferred to the capacitor element by heat diffusion. Compared with the electric heating wire, the heat diffusion effect of the heating oil pipe is better, which can improve the problem of uneven temperature inside the oven. At the same time, compared with the conventional heat setting process of high temperature (95~110℃) and long time (4~15h), the present invention adopts step-by-step heating and step-by-step cooling to achieve heat setting of the capacitor element, which is conducive to uniform heating of the capacitor element, avoiding the quality of the capacitor element affected by extremely rapid heating or extremely rapid cooling, and can improve the problem of uneven temperature inside the oven during heating and cooling, avoiding large temperature differences in different areas. Before step-by-step heating and step-by-step cooling, vacuuming and inert gas filling are performed, which is conducive to ensuring the vacuum degree of the entire heat setting process stage in the oven and avoiding oxidation of the component end face at high temperature. According to the temperature result data of each temperature monitoring point, it can be known that the use of the vacuum heat setting device of the present invention to heat set the metallized film capacitor element can quickly and evenly transfer heat to each part of the capacitor, thereby improving the efficiency and quality of heat setting. The temperature difference of each temperature monitoring point on the tooling where the capacitor element is located is small, satisfying the requirement of being within 2°C, which is conducive to uniform heating of the capacitor element and consistent thermal polymerization effect, so that the setting effect is good and the setting is complete.

[0052] Optionally, in the above step S1, the time of one vacuuming is 90 min to 100 min, and the vacuum degree after one vacuuming is 55 Pa to 65 Pa. Specifically, after the capacitor element is sprayed with gold, it is placed in a closed space to ensure that the spacing between the capacitor elements is consistent, and then vacuuming is performed once. One vacuuming is conducive to removing water vapor in the closed space and bubbles in the internal gaps of the capacitor elements.

[0053] Optionally, in the above step S2, the enclosed space after the first vacuuming is continuously filled with an inert gas, and the inert gas may be nitrogen, neon, argon, helium, krypton or xenon. After the enclosed space after the first vacuuming is filled with an inert gas, the vacuum degree of the enclosed space is 9000Pa to 10000Pa. Continuing to fill the inert gas after the first vacuuming is beneficial to ensure the heating efficiency of the capacitor element and reduce the entry of water vapor into the enclosed space, thereby avoiding oxidation of the element in a subsequent high temperature environment.

[0054] Optionally, the above step S3 specifically includes: first, controlling the temperature in the enclosed space to maintain at the initial heating temperature point, the first heating temperature point, the second heating temperature point and the third heating temperature point for 90 minutes to 100 minutes respectively, and then controlling the temperature in the enclosed space to maintain at the final heating temperature point for 320 minutes to 340 minutes. Among them, the first heating temperature point is 70°C to 75°C, the second heating temperature point is 80°C to 85°C, and the third heating temperature point is 90°C to 95°C. Further, the heating time of the initial heating temperature point, the first heating temperature point, the second heating temperature point, the third heating temperature point and the final heating temperature point is 30 minutes to 35 minutes.

[0055] In the above step S3, the temperature in the enclosed space is first raised to the initial heating temperature point (60°C-65°C) within 30 to 35 minutes, then raised to the first heating temperature point (70°C-75°C) within 30 to 35 minutes, further raised to the second heating temperature point (80°C-85°C) within 30 to 35 minutes, and then raised to the third heating temperature point (90°C-95°C) within 30 to 35 minutes, and maintained at the above temperature points for 90 to 100 minutes respectively. Finally, the temperature is raised to the final heating temperature point (100°C-115°C) within 30 to 35 minutes, and maintained at the final heating temperature point for 320 to 340 minutes.

[0056] The above-mentioned step-by-step heating process is conducive to uniform heating and shaping of the capacitor element, avoiding uneven thermal expansion inside the capacitor due to extremely rapid heating, thereby generating internal stress and structural deformation.

[0057] Optionally, in the above step S4, the time of the second vacuuming is 90 min to 100 min, and the vacuum degree after the second vacuuming is 5 Pa to 10 Pa. The second vacuuming is helpful to remove bubbles inside the capacitor element, so that the element is completely finalized.

[0058] Optionally, in the above step S5, after the inert gas is filled into the enclosed space of the second vacuum pumping, the vacuum degree of the enclosed space is 9000 Pa to 10000 Pa. Continuing to fill the inert gas after the second vacuum pumping is conducive to ensuring the cooling efficiency and reducing the entry of water vapor into the enclosed space, thereby preventing the end surface of the component from being oxidized at high temperature.

[0059] Optionally, the above step S6 specifically includes: controlling the temperature in the enclosed space to maintain at the initial cooling temperature point, the first cooling temperature point, the second cooling temperature point, the third cooling temperature point and the final cooling temperature point for 30 minutes to 40 minutes respectively. Among them, the first cooling temperature point is 75°C to 80°C, the second cooling temperature point is 65°C to 70°C, and the third cooling temperature point is 55°C to 60°C. Further, the cooling time of the initial cooling temperature point, the first cooling temperature point, the second cooling temperature point, the third cooling temperature point and the final cooling temperature point is 60 minutes to 65 minutes.

[0060] In the above step S6, the temperature in the enclosed space is first cooled to the initial cooling temperature point (85°C-90°C) within 60min to 65min, then cooled to the first cooling temperature point (75°C-80°C) within 60min to 65min, further cooled to the second cooling temperature point (65°C-75°C) within 60min to 65min, then cooled to the third cooling temperature point (55°C-60°C) within 60min to 65min, and finally cooled to the final cooling temperature point (45°C-50°C) within 60min to 65min, and maintained at the above temperature points for 30min to 40min respectively.

[0061] The above-mentioned step-type cooling process allows the component to cool down slowly, thus avoiding the situation where the component film collapses due to extreme sudden cooling.

[0062] It should be understood that since the present invention achieves the change of temperature in the enclosed space by adjusting the temperature of the heating oil, and considering the temperature loss of the heating oil during transportation and heat transfer, the actual temperature in the enclosed space will be lower than the temperature of the heating oil. Therefore, when actually adjusting the temperature of the heating oil, the temperature of the heating oil can be adjusted to be 5°C to 8°C higher than the set enclosed space temperature to ensure that the temperature in the enclosed space meets the requirements of the heat setting process parameters.

[0063] As a second aspect, an embodiment of the present invention further provides a vacuum heat setting device, which is used to implement the above vacuum heat setting process. Figure 1 As shown, the vacuum heat setting device includes an oven 1 and a first heating oil pipe 2 arranged in the oven 1. The first heating oil pipe 2 is reciprocatingly coiled along the width direction of the oven 1 and extends toward the height direction of the oven 1. There are multiple first heating oil pipes 2, and the multiple first heating oil pipes 2 are distributed at intervals along the length direction of the oven 1.

[0064] Specifically, taking the X-axis as the width direction of the oven 1, the Y-axis as the length direction of the oven 1, and the Z-axis as the height direction of the oven 1 as an example, the first heating oil pipe 2 is reciprocated and coiled along the width direction of the oven 1 and extends toward the height direction of the oven 1, that is, the first heating oil pipe 2 extends in an S-shape or a wavy shape in the XZ plane.

[0065] Furthermore, the vacuum heat setting device may further include a vacuum pumping component, which is connected to the oven 1. The vacuum pumping component may be a vacuum pump (not shown in the figure), which is arranged outside the oven 1. Before the capacitor element is heated and set, the oven 1 may be vacuumed by the vacuum pump, thereby reducing the influence of air on the heat setting effect of the capacitor.

[0066] Furthermore, the vacuum heat setting device also includes an inert gas replenishing mechanism (not shown in the figure), which is connected to the inside of the oven 1 and is used to fill the oven 1 with inert gas. Specifically, the inert gas replenishing mechanism may include a gas nozzle, a control valve and an air pump, wherein a gas nozzle may be arranged at each of the four corners of the oven 1, and the gas nozzles are connected to the air pump through a vent pipe, and the control valve is arranged on the vent pipe. The inert gas may be nitrogen, neon, argon, helium, krypton, xenon, etc.

[0067] In the embodiment of the present invention, the vacuum degree in the oven 1 is increased by a vacuum pumping assembly, and the oven 1 is filled with inert gas by an inert gas replenishing mechanism, thereby jointly improving the vacuum heat setting effect, reducing the oxidation phenomenon of the capacitor film at high temperature, and allowing the capacitor element to be evenly heated in a vacuum state.

[0068] In some optional embodiments, the vacuum heat setting device further includes a temperature monitoring mechanism (not shown in the figure), which is connected to the inside of the oven 1 and is used to detect the temperature inside the oven 1 in real time. Specifically, the temperature monitoring mechanism may include a temperature sensor, wherein a temperature sensor may be arranged at each of the four corners of the oven 1, and the temperature sensor is further externally connected to a controller and a display to reflect the real-time temperature inside the oven 1.

[0069] In some optional embodiments, the oven 1 includes a box body 11 and at least one movable door 12. Figure 4 As shown, the movable door 12 is movably connected to the box body 11. Specifically, the movable door 12 can be rotatably connected to the box body 11, or slidably connected, so as to realize the opening and closing of the oven 1. The number of movable doors 12 can be one or two. For example, in a specific embodiment, the oven 1 can include two movable doors 12 arranged opposite to each other along the width direction of the box body 11.

[0070] In some optional embodiments, referring to Figure 1 As shown, the vacuum heat setting device further includes a second heating oil pipe 3 disposed in the oven 1, the second heating oil pipe 3 is reciprocated along the length direction of the oven 1 and extends toward the height direction of the oven 1. The second heating oil pipe 3 can further increase the heating area, so that the capacitor element in the storage cavity 6 is fully heated and set.

[0071] Specifically, taking the X-axis as the width direction of the oven 1, the Y-axis as the length direction of the oven 1, and the Z-axis as the height direction of the oven 1 as an example, the second heating oil pipe 3 is reciprocated along the length direction of the oven 1 and extends toward the height direction of the oven 1, that is, the second heating oil pipe 3 extends in an S-shape or a wavy shape in the YZ plane.

[0072] In some optional embodiments, referring to Figure 1 As shown, the vacuum heat setting device also includes a first mounting frame 4 for mounting the first heating oil pipe 2 and a second mounting frame 5 for mounting the second heating oil pipe 3. The number of the first mounting frame 4 can be one, that is, one first mounting frame 4 can simultaneously mount multiple first high-temperature oil pipes; the number of the first mounting frames 4 can also be adapted to the number of the first high-temperature oil pipes, and each first mounting frame 4 can mount one first high-temperature oil pipe.

[0073] In some optional embodiments, the first heating oil pipe 2 and the second heating oil pipe 3 are interconnected. Specifically, when the number of the first heating oil pipes 2 is multiple groups, each of the first heating oil pipes 2 is interconnected, and the first heating oil pipes 2 and the second heating oil pipes 3 are also interconnected. It should be understood that, although not fully shown in the figure, the first heating oil pipe 2 and the second heating oil pipe 3 can extend to the top wall and the bottom wall of the box body 11, and each of the first heating oil pipes 2 and the second heating oil pipe 3 can be interconnected in the top wall and the bottom wall, thereby forming a complete oil circuit. In one embodiment, the oil inlet of the oil circuit can be opened at the lower end of the second heating oil pipe 3, and the oil outlet can be opened at the lower end of one of the first heating oil pipes 2, and the heating oil enters the oven 1 from the oil inlet, passes through the second heating oil pipe 3 and the first heating oil pipe 2 in sequence, and finally leaves the oven 1 from the oil outlet. It should be noted that a matching heater and a power pump should be further provided outside the oven 1. The heater is used to heat the heating oil to keep the heating oil at a set temperature, and the power pump is used to provide power for the heating oil to circulate in the first heating oil pipe 2 and the second heating oil pipe 3.

[0074] As an optional embodiment, for the arrangement of capacitor elements, refer to Figure 1 As shown, a placement cavity 6 can be formed between each two adjacent groups of first heating oil pipes 2. When actually performing the heat setting work, the capacitor element can be placed in the placement cavity 6 between the two adjacent groups of first heating oil pipes 2 for heating.

[0075] Of course, in some other optional embodiments, since the first heating oil pipe 2 can be specifically coiled in a wave shape or an "S" shape, each first heating oil pipe 2 includes a plurality of winding units 21 extending along the width direction of the oven 1, and each adjacent two winding units 21 are connected end to end, and a storage channel 7 is formed between each adjacent two winding units 21, and the storage channels 7 of the plurality of first heating oil pipes 2 are arranged in a horizontally aligned manner. It should be noted that when the first heating oil pipe 2 is reciprocally coiled along the width direction of the oven 1 and extends toward the height direction of the oven 1, it specifically includes a plurality of sections of pipe bodies extending along the width direction and connected end to end, and the winding unit 21 refers to each section of the pipe body extending along the width direction in the first heating oil pipe 2.

[0076] Therefore, refer to Figure 1 and Figure 4 As shown, when the first heating oil pipe 2 is coiled in a set direction and path, a plurality of storage channels 7 with staggered opening directions can be formed, and some capacitor elements can be placed in the storage channels 7 for heating, which can further increase the space utilization rate in the oven 1.

[0077] Several different arrangements of capacitor elements in the oven 1 are described below through specific embodiments:

[0078] Example 1

[0079] Based on the above vacuum heat setting device, in this embodiment, the number of the first heating oil pipes 2 is three groups. Figure 1 As shown, three groups of first heating oil pipes 2 are respectively located near the two side walls of the oven 1 and the middle of the oven 1, and a storage cavity 6 is formed between each two adjacent groups of first heating oil pipes 2. This embodiment also includes a second heating oil pipe 3 arranged adjacent to the inner side wall of the oven 1, that is, the side wall opposite to the movable door 12. The second heating oil pipe 3 is reciprocated along the length direction of the oven 1 and extends toward the height direction of the oven 1. The extension direction of the second heating oil pipe 3 is parallel to the inner side wall of the oven 1.

[0080] During the actual heating and shaping process, the tooling or mounting rack equipped with capacitor elements can be placed in the storage cavity 6, and the capacitor elements on the tooling or mounting rack can be fully heated and shaped using the first heating oil pipes 2 on both sides of each storage cavity 6 and the second heating oil pipes 3 inside the oven 1.

[0081] Based on the above vacuum heat setting device, the vacuum heat setting process of this embodiment specifically includes the following steps:

[0082] S1: stack the capacitor elements in sequence on the tooling, then put the tooling into the storage chamber 6 in the oven 1, and perform a vacuum pumping, wherein the vacuum pumping time is 90 minutes, and the vacuum degree after the vacuum pumping is 60Pa.

[0083] S2: nitrogen is filled into the oven 1 after the vacuum is evacuated once, and the vacuum degree in the oven 1 after the nitrogen is filled is controlled to be 95000Pa.

[0084] S3: heating the heating oil to control the temperature in the oven 1 to rise stepwise between the initial heating temperature point and the final heating temperature point, wherein the initial heating temperature point is 60°C and the final heating temperature point is 100°C.

[0085] Specifically, the temperature in the oven 1 was first raised to 60°C within 30 minutes, then to 70°C within 30 minutes, further to 80°C within 30 minutes, and then to 90°C within 30 minutes, and maintained at the above temperature points for 90 minutes respectively. Finally, the temperature was raised to the final heating temperature point of 100°C within 30 minutes, and maintained at the final heating temperature point for 330 minutes.

[0086] S4: performing secondary vacuuming in the oven 1, wherein the secondary vacuuming time is 90 minutes, and the vacuum degree after the secondary vacuuming is 10 Pa.

[0087] S5: nitrogen is filled into the oven 1 after the second vacuuming, and the vacuum degree in the oven 1 after the nitrogen is filled is controlled to be 95000Pa.

[0088] S6: Cooling the heating oil, controlling the temperature in the oven 1 to decrease stepwise between the initial cooling temperature point and the final cooling temperature point, wherein the initial cooling temperature point is 90°C and the final cooling temperature point is 50°C.

[0089] Specifically, the temperature in oven 1 was first cooled to 90°C within 60 min, then cooled to 80°C within 60 min, further cooled to 70°C within 60 min, then cooled to 60°C within 60 min, and finally cooled to 50°C within 60 min, and maintained at the above temperature points for 30 min respectively.

[0090] In this embodiment, temperature sensors can be arranged at multiple points on the tooling where the capacitor elements are placed, and the temperature data obtained by the temperature sensors arranged at various points on the tooling are analyzed. Figure 2 The different curves in the figure represent the changes in temperature at different points as the heat setting time increases. Figure 2 It can be seen that the temperature difference of different curves at the same heat setting time is less than 2° C., and the curves almost overlap. This shows that the vacuum heat setting device and process in this embodiment can effectively improve the uniformity of heating of the capacitor element.

[0091] Comparative Example

[0092] The shaping device in this comparative example uses an electric heating wire as a heat source and air as a heat transfer medium. At the same time, the capacitor element is heated and shaped at 110° C. for 12 hours.

[0093] By analyzing the temperature data obtained by the temperature sensors arranged at various points on the tooling of this comparative example, Figure 3 The different curves in the figure represent the changes in temperature at different points as the heat setting time increases. Figure 3 It can be seen that the temperature difference between different curves at the same heat setting time can reach up to 15°C or more, and when the set maximum temperature is reached and the temperature is kept constant, the temperature difference is 17.8°C. This shows that the temperature uniformity of the heat setting equipment and process in this comparative example is poor, which will affect the heat setting effect of the capacitor element, the thermal polymerization effect of the film layer, and the life of the finished capacitor.

[0094] Furthermore, the capacitor products prepared by the thermoforming process in Example 1 and the comparative example were subjected to a charge and discharge comparison test. The charge and discharge comparison test data are shown in Table 1:

[0095] Table 1 Charge and discharge test data of capacitors prepared by thermoforming process in Example 1 and Comparative Example

[0096]

[0097] The capacitor was disassembled to check the internal metallized film coating, wherein the schematic diagram of the internal coating of the capacitor prepared by the thermoforming process of Example 1 is shown as follows: Figure 5 As shown, the microscopic schematic diagram of the internal coating of the capacitor prepared by the comparative thermoforming process is shown in Figure 6 shown.

[0098] As shown in Table 1, compared with Comparative Example 1, the capacity attenuation value, loss value and ESR change value of the capacitor in Example 1 are significantly reduced in the charge and discharge test, while Figure 5 , Figure 6 It can be further seen that the metallized film coating of the capacitor in the comparative example is electrified and the effective coating area is reduced. This shows that the capacitor in Example 1 has a higher capacity, a correspondingly smaller loss value, and a better performance when used.

[0099] Furthermore, when other parameters are the same, the capacitors prepared by the thermoforming process in Example 1 and the comparative example are subjected to life test, and the life comparison data are shown in Table 2:

[0100] Table 2 Life test data of capacitors prepared by thermoforming process in Example 1 and Comparative Example

[0101]

[0102] The capacitor after the life test was further disassembled to check the internal metallized film coating, wherein the schematic diagram of the internal coating of the capacitor prepared by the thermoforming process of Example 1 is shown in FIG. Figure 7 As shown, the microscopic schematic diagram of the internal coating of the capacitor prepared by the comparative thermoforming process is shown in Figure 8 shown.

[0103] As shown in Table 2, compared with Comparative Example 1, the capacitance attenuation value, loss value and ESR change value of the capacitor in Example 1 are significantly reduced in the life test. Figure 7 , Figure 8 It can be further known that the metallized film coating of the capacitor in the comparative example is electrified during the life test, and the effective area of ​​the coating is reduced. The life test test data shows that the capacitor prepared in Example 1 has a longer service life.

[0104] Example 2

[0105] In this embodiment, refer to Figure 4 As shown, the oven 1 further includes a storage rack 8, which includes a plurality of storage layers 81 that are interconnected and spaced apart in the height direction, and the plurality of storage layers 81 are arranged one-to-one correspondingly to the plurality of storage channels 7 of each first heating oil pipe 2, and each storage layer 81 is movably arranged in the corresponding storage channel 7. The storage layer 81 is used to carry capacitor elements, and the storage rack 8 treats the plurality of storage layers 81 in the storage channel 7 as a whole, thereby improving the stability of each storage layer 81.

[0106] Furthermore, each storage layer 81 is slidably connected to the oven 1 on both sides along the length direction. Specifically, as an embodiment, multiple sets of slide rails (not shown in the figure) are provided on the inner side wall of the oven 1 along the length direction, and the multiple sets of slide rails are distributed corresponding to the multiple storage layers 81, and both sides of each storage layer 81 are slidably connected to the corresponding slide rails. By providing multiple sets of slide rails on the inner side wall of the oven 1, the multiple storage layers 81 can be pushed in or pulled out in a sliding manner as a whole, thereby improving operability and structural stability of the storage layer 81.

[0107] Further, see Figure 4 As shown, in order to further improve the stability of the storage layer 81, each first mounting rack 4 is provided with a plurality of positioning holes 41 along the height direction, and the plurality of positioning holes 41 are arranged one-to-one with the plurality of storage layers 81, and each storage layer 81 is movably plugged into the corresponding positioning hole 41. Specifically, each storage layer 81 has a positioning protrusion on one side close to the first mounting rack 4, and when the storage rack 8 is pushed into the oven 1, the positioning protrusion on the storage layer 81 can be inserted into the corresponding positioning hole 41, thereby further improving the stability of the storage rack 8 in the oven 1 and preventing the capacitor from being damaged or deformed during the heating and shaping process.

[0108] Based on the vacuum heat setting device in this embodiment, the vacuum heat setting process of this embodiment specifically includes the following steps:

[0109] S1: stack the capacitor elements in sequence on each storage layer 81 of the storage rack 8, and then push each storage layer 81 into the storage channel 7 to perform a vacuum pumping operation. The vacuum pumping operation lasts for 100 minutes, and the vacuum degree after the vacuum pumping operation is 65 Pa.

[0110] S2: nitrogen is filled into the oven 1 after the vacuum is evacuated once, and the vacuum degree in the oven 1 after the nitrogen is filled is controlled to be 90000Pa.

[0111] S3: The heating oil is heated to control the temperature in the oven 1 to rise stepwise between the initial heating temperature point and the final heating temperature point, wherein the initial heating temperature point is 65°C and the final heating temperature point is 115°C.

[0112] Specifically, the temperature in the oven 1 was first raised to 65°C within 35 minutes, then raised to 75°C within 35 minutes, further raised to 85°C within 35 minutes, and then raised to 95°C within 35 minutes, and maintained at the above temperature points for 100 minutes respectively. Finally, the temperature was raised to the final heating temperature point of 115°C within 35 minutes, and maintained at the final heating temperature point for 320 minutes.

[0113] S4: performing secondary vacuuming in the oven 1, wherein the secondary vacuuming time is 100 min, and the vacuum degree after the secondary vacuuming is 10 Pa.

[0114] S5: nitrogen is filled into the oven 1 after the second vacuuming, and the vacuum degree in the oven 1 after the nitrogen is filled is controlled to be 10000Pa.

[0115] S6: Cooling the heating oil, controlling the temperature in the oven 1 to decrease stepwise between the initial cooling temperature point and the final cooling temperature point, wherein the initial cooling temperature point is 85°C and the final cooling temperature point is 45°C.

[0116] Specifically, the temperature in oven 1 was first cooled to 85°C within 65 min, then cooled to 75°C within 65 min, further cooled to 65°C within 65 min, then cooled to 55°C within 65 min, and finally cooled to 45°C within 65 min, and maintained at the above temperature points for 40 min respectively.

[0117] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A vacuum heat setting process for capacitor elements, characterized in that: The following steps are involved: Place the capacitor element in a confined space and evacuate it once; Filling the enclosed space after the vacuum pumping with inert gas; The enclosed space is heated by heating oil, and the temperature in the enclosed space is controlled to rise stepwise between an initial heating temperature point and a final heating temperature point, wherein the initial heating temperature point is 60°C to 65°C, and the final heating temperature point is 100°C to 115°C. First, the temperature in the enclosed space is controlled to be maintained at the initial heating temperature point, the first heating temperature point, the second heating temperature point and the third heating temperature point for 90 min to 100 min respectively, and then the temperature in the enclosed space is controlled to be maintained at the final heating temperature point for 320 min to 340 min, wherein the first heating temperature point is 70°C to 75°C, the second heating temperature point is 80°C to 85°C, and the third heating temperature point is 90°C to 95°C; Performing secondary vacuuming in the confined space; Filling the enclosed space after the second vacuuming with inert gas; The temperature in the enclosed space is controlled to decrease stepwise between an initial cooling temperature point and a final cooling temperature point, wherein the initial cooling temperature point is 85°C to 90°C, and the final cooling temperature point is 45°C to 50°C. The temperature in the enclosed space is controlled to be maintained at the initial cooling temperature point, the first cooling temperature point, the second cooling temperature point, the third cooling temperature point and the final cooling temperature point for 30 min to 40 min respectively; wherein the first cooling temperature point is 75°C to 80°C, the second cooling temperature point is 65°C to 70°C, and the third cooling temperature point is 55°C to 60°C.

2. The capacitor element vacuum heat setting process according to claim 1, characterized in that: The time for the vacuum pumping is 90 minutes to 100 minutes, and the vacuum degree after the vacuum pumping is 55Pa to 65Pa.

3. The capacitor element vacuum heat setting process according to claim 1, characterized in that: The time of the secondary vacuum pumping is 90 minutes to 100 minutes, and the vacuum degree after the secondary vacuum pumping is 5Pa to 10Pa.

4. The capacitor element vacuum heat setting process according to claim 1, characterized in that: After the inert gas is respectively filled into the enclosed space after the first vacuum pumping and the second vacuum pumping, the vacuum degree of the enclosed space is 9000Pa to 10000Pa.

5. The capacitor element vacuum heat setting process according to claim 1, characterized in that: The heating time of the initial heating temperature point, the first heating temperature point, the second heating temperature point, the third heating temperature point and the final heating temperature point are all 30 minutes to 35 minutes.

6. The capacitor element vacuum heat setting process according to claim 1, characterized in that: The cooling time of the initial cooling temperature point, the first cooling temperature point, the second cooling temperature point, the third cooling temperature point and the final cooling temperature point are all 60 minutes to 65 minutes.

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