A manufacturing process for capacitor film core

Abstract

The present invention discloses a manufacturing process for a capacitor film core, comprising a first single-layer film roll and a second single-layer film roll unrolled by at least two unwinding mechanisms, wherein the first single-layer film roll and the second single-layer film roll are wound into a roll by a winder after being unrolled, and further comprising the following steps: (1) setting up a winder and film rolls; (2) winding into a roll with a large inner diameter: stacking the first single-layer film roll and the second single-layer film roll up and down, wherein the left blank area of ​​the upper and lower adjacent single-layer film rolls corresponds to the left metal coating up and down, and the right metal coating corresponds to the right blank area up and down; then, according to the requirement of the number of capacitor film layers, the core drum is driven to rotate by the winder so that the films unrolled from each single-layer film roll are wound into a roll with a large inner diameter; (3) pre-cold pressing; (4) film cutting and unfolding; (5) hot pressing and compacting; (6) cutting and stripping: according to the specifications of the capacitor product, the dense long strip capacitor core blank is cut into a plurality of capacitor core semi-finished products of the same size.

Description

Technical Field

[0001] The present invention relates to the technical field of film capacitors, and in particular to a manufacturing process of a capacitor film core. Background Art

[0002] The capacitor film core (also known as the capacitor core) is the core component of the capacitor. Its manufacturing process directly affects the performance and production efficiency of the capacitor. The traditional capacitor film core is usually made using a single-layer film winding process: according to the size of the capacitor film core, a long strip of metalized film (such as Figure 4-5 ), then place the metallized film (or a combination of metal foil and plastic film) on the unwinding device. A tension control device maintains constant tension, and the winding device (winding needle) winds the film material into a cylindrical core. After winding to the required length, the cutting device cuts the film into individual film cores.

[0003] However, the winding process of the existing capacitor film core is to increase the number of turns of the film core by continuous winding, and to increase the plate area by continuous odd layers to increase the capacitance of the capacitor. This can be understood as increasing the plate area by series connection. However, the film capacitor formed by continuous winding is prone to breakage during hot pressing or use, which will cause the metal coating part that was originally connected in series to be disconnected, resulting in a change in the effective plate area of ​​the capacitor. After the film breaks, the effective area of ​​the metal coating in series decreases, which is equivalent to a decrease in the plate area of ​​the capacitor, resulting in a decrease in the capacitance value, making it impossible for the capacitor to meet the circuit's requirements for capacitance value, and reducing the performance of the capacitor. The film in different positions may break differently during hot pressing, resulting in large differences in the capacitance values ​​of film capacitors in the same batch, and the consistency of capacitance cannot be guaranteed.

[0004] Furthermore, the winding needles used in conventional winding machines are typically very small (e.g., only about 3mm in diameter). This small diameter limits the line speed during the winding process, as well as the size of the film core. Excessive line speeds can cause excessive tension or vibration in the film material, impacting winding quality. Summary of the Invention

[0005] The problem to be solved by the present invention is to provide a manufacturing process for a capacitor film core, which can equivalently increase the effective area of ​​the plate, avoid the problem of large-area failure caused by single-layer fracture, and improve the service life and production efficiency of the entire capacitor.

[0006] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0007] A process for manufacturing a capacitor film core includes: a first single-layer film roll and a second single-layer film roll being unwound by at least two unwinding mechanisms; the first single-layer film roll and the second single-layer film roll being unwound and then wound into a roll by a winder; and the process further includes the following steps:

[0008] (1) Winding machine and film roll arrangement: the core drum of the winding machine is capable of winding a roll with a large inner diameter; the first single-layer film roll is provided with a left blank area and a right metal coating along its length, and the second single-layer film roll is provided with a left metal coating and a right blank area along its length;

[0009] (2) Winding into a coil with a large inner diameter: The first single-layer film roll and the second single-layer film roll are stacked up and down, and the left blank area of ​​the adjacent first single-layer film roll and the second single-layer film roll correspond to the left metal coating, and the right metal coating corresponds to the right blank area. The first single-layer film roll and the second single-layer film roll are wound onto the core drum of the winding machine; then, according to the requirements of the number of capacitor film layers, the core drum is driven to rotate by the winding machine so that the films released from each first single-layer film roll and each second single-layer film roll are wound into a coil with a large inner diameter and removed;

[0010] (3) Pre-cold pressing: Place the disassembled large inner diameter coil into a cold isostatic press. Under the conditions of a pressure range of 20MPa-80MPa and a temperature of 22℃-27℃, use a cold isostatic press to pre-cold press the large inner diameter coil for 60 seconds to 120 seconds with a 360° all-round uniform pressure to make the large inner diameter coil thicker.

[0011] (4) Film cutting and unfolding: Use a cutter to cut the pre-cold pressed large inner diameter coil along the axial direction. After cutting, the large inner diameter coil becomes a long capacitor core blank with multiple layers of film overlapping. The two sides of the long capacitor core blank are unfolded and flattened to the two sides of the core tube respectively;

[0012] (5) Hot pressing and densification: Place the flattened long capacitor core blank into a hot press. Under the conditions of a pressure range of 5MPa-10MPa and a temperature of 100℃-110℃, use a hot press to hot press the long capacitor core blank for 120 seconds-240 seconds to make the long capacitor core blank dense.

[0013] (6) Cutting and stripping: According to the specifications of the capacitor products, the dense long strip capacitor core blank is cut into multiple capacitor core semi-finished products of the same size.

[0014] The preferred embodiment further includes step (7), wherein the left end face and the right end face of the capacitor core semi-finished product are respectively used to connect to the pins of the capacitor, the left pins are connected in parallel with the alternating metal coating layers on the left end face of the capacitor core semi-finished product by welding, and the right pins are connected in parallel with the alternating metal coating layers on the right end face of the capacitor core semi-finished product by welding.

[0015] In the above step (1), the inner diameter of the large inner diameter coil is not strictly limited. Generally, after cutting, multiple capacitor core semi-finished products can be cut out. Generally speaking, the larger the inner diameter, the longer the long strip of capacitor core blank will be after cutting, and the more capacitor core semi-finished products can be cut out at one time, and the efficiency is relatively higher.

[0016] In the above step (2), the metal coatings of the first and second single-layer film rolls adjacent to each other are staggered in a left-right manner. The left blank area of ​​the first single-layer film roll corresponds to the left metal coating of the second single-layer film roll, and the right metal coating of the first single-layer film roll corresponds to the right blank area of ​​the second single-layer film roll. The metal coatings on the same side are spaced apart from each other, forming a staggered parallel structure of interlayer metal coatings, rather than a traditional head-to-tail series connection. This staggered parallel structure of interlayer metal coatings has the following advantages: (a) local damage isolation: damage to a single layer of film only reduces the metal coating area of ​​that layer, thus fundamentally avoiding the problem of "single layer fracture leading to large-area failure" and laying the foundation for the stability of subsequent steps; (b) improved capacitance uniformity: avoids concentrated stress and thermal stress concentration; (c) enhanced reliability: can equivalently increase the effective area of ​​the plate (multiple metal coatings participate in charging and discharging in parallel), while ensuring the capacitance value, improving redundancy and reducing the risk of single point failure; improving the service life of the overall capacitor; and improving the stability of electrical performance.

[0017] In the above step (3), cold isostatic pressing (CIP) is a process that applies isotropic high pressure to materials at room temperature. It has been widely used in the fields of ceramics, powder metallurgy, etc., but its use in pre-pressing capacitor coils is an innovative application that can effectively solve the problem of looseness inside large inner diameter coils. Under the action of high pressure, the layers of film inside the coil are evenly compressed, and the air between the layers is squeezed out, making the originally loose large coil thicker and denser. This pre-cold pressing step has multiple functions: first, it improves the overall density and tightness of the coil, providing a solid matrix for subsequent slicing; second, through isotropic pressure, the radial and circumferential forces on the coil are uniform, avoiding local deformation or interlayer sliding that may be caused by direct hot pressing; third, cold isostatic pressing is carried out at room temperature and will not cause thermal effects on the properties of the film material.

[0018] In the above step (4), the large inner diameter coil material that has been pre-cold pressed has a high degree of compactness, which is convenient for cutting. The large inner diameter coil material is cut axially using a cutter. The cutting position can be selected on the upper surface of the large inner diameter coil material, and the cutting is carried out from the outer to the inner surface of the upper surface of the large inner diameter coil material to the upper surface of the core tube. This cutting method can cut the flat cylindrical large inner diameter coil material into a flat long strip capacitor core blank, which creates conditions for subsequent hot pressing and slicing. Since the pre-cold pressing makes the layers of film tightly bonded, the multi-layer film will not loosen and fall off during the unfolding process, but will maintain a multi-layered structure, and the final result is a large-format long strip capacitor core blank with multiple layers of film overlapping.

[0019] In step (5) above, heat pressure is used to slightly soften the film material, thereby eliminating the tiny gaps between the layers under pressure, achieving close bonding between the layers and uniform overall thickness. After heat pressing, the multi-layer long strip capacitor core blank becomes more dense and flat, and its thickness and density meet the process requirements. Compared with the traditional hot pressing of only a single small core, this process heat presses the entire large-scale long strip capacitor core blank as a whole, which is more efficient and the force is evenly distributed across all parts.

[0020] After the cutting is completed in the above step (6), the multiple semi-finished capacitor cores obtained can enter the next process of capacitor assembly, such as gold spraying, lead welding, packaging, etc. In the gold spraying process, the end faces of multiple side-by-side semi-finished capacitor cores can be metallized at one time, thereby improving equipment utilization. This simplifies the subsequent process flow and is conducive to the continuous and automated manufacturing of capacitors. Since this process has already combined the processing of multiple layers of thin films in the early stage, each semi-finished capacitor core does not need to be wound again, and can be directly stacked to form a capacitor core, thereby shortening the entire process flow.

[0021] In a preferred embodiment, the core barrel is composed of at least two winding rods that deviate from the rotation center of the winder. Of course, the core barrel can also be composed of a winding rod with a large diameter.

[0022] In a further preferred embodiment, at least two of the winding rods are in a straight line with the rotation center. More preferably, the two winding rods are symmetrically arranged with respect to the rotation center.

[0023] In a further preferred embodiment, the distance between the two winding rods is greater than 200 mm. Setting the distance between the two winding rods to greater than 200 mm allows for winding of longer and wider strips of capacitor core blanks, with a length of at least 400 mm. If the size of the capacitor core semi-finished product is 10 mm, approximately 40 capacitor core semi-finished products can be cut out. Furthermore, the longer distance between the two winding rods provides more stable support for the film, resulting in a more even distribution of axial tension during winding, reducing edge wrinkles caused by a too-short distance between the two winding rods and ensuring interlayer alignment accuracy.

[0024] In a further preferred embodiment, the distance between the two winding rods is 400 mm to 800 mm.

[0025] In a further preferred embodiment, the distance between the two winding rods is 600 mm.

[0026] In another preferred embodiment, the core drum is a cylinder that rotates around the rotation center of the winder.

[0027] In a further preferred embodiment, the outer diameter of the cylinder is greater than 200 mm.

[0028] In a further preferred embodiment, the outer diameter of the cylinder is 400 mm-800 mm.

[0029] In a preferred embodiment, the winding machine is equipped with a tension sensor, a servo motor, and a controller. The core drum is mounted on the winding machine's rotating shaft, and the servo motor's power output shaft is in driving connection with the winding machine's rotating shaft. The tension sensor's signal output terminal is electrically connected to the controller's corresponding signal input terminal, and the servo motor is electrically connected to the controller's corresponding signal output terminal. The controller first presets a target tension value, and then uses the tension sensor to monitor the tension data of the large inner diameter web in real time. The controller compares the real-time tension data with the preset target tension value, calculates the tension deviation, and sends the tension deviation to the controller. The controller processes the tension deviation and sends a signal to adjust the speed of the servo motor's power output shaft. If the real-time tension data is too high or too low, the controller sends a command to the servo motor to adjust the speed of the servo motor's power output shaft. This automatic tension control can adjust the tension of each layer of film by controlling the winding machine's rotational speed, avoiding film stretching deformation or interlayer slippage caused by tension fluctuations, thereby ensuring winding quality and consistency.

[0030] In a preferred embodiment, the cold isostatic press utilizes a staged pressurization process during pre-cold pressing: the total pre-cold pressing pressure is divided into a lower pressure and a target pressure. The large inner diameter coil is initially held at a lower pressure of 5MPa-15MPa for 20-30 seconds, then gradually increased to the target pressure of 20MPa-80MPa and maintained at the final pressure for 40-90 seconds. This staged pressurization allows sufficient time for air inside the large inner diameter coil to escape, preventing air from being trapped under high pressure and forming bubbles. Furthermore, staged pressurization reduces the impact of instantaneous high pressure on the edges of the large inner diameter coil, preventing edge film extrusion or damage.

[0031] In the preferred embodiment, in the step (5), the long strip capacitor core blank needs to be slowly cooled after hot pressing, so that the long strip capacitor core blank is allowed to drop to room temperature while maintaining the pressure, so as to fix its size and flatness.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] (1) The present invention adopts a staggered parallel structure of metal coatings. Even if a single layer of film is damaged, it only affects the local capacitance and does not cause overall failure. The stability of the capacitance value is improved, overcoming the problem of "easy breakage during continuous winding".

[0034] (2) The present invention adopts the core barrel of the winding machine to replace the traditional small diameter winding needle (such as 3mm), which can wind large inner diameter coils, breaking through the size limit of the film core. Combined with centralized cutting and slitting, it improves production efficiency and can adapt to larger specifications of capacitor cores; at the same time, it reduces the tension impact of the winding line speed on the film (large size winding can be achieved without high-speed winding), reduces film vibration and damage, and improves winding quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram of the structure of winding, pre-cooling and film cutting in Example 1 of the present invention;

[0036] Figure 2 This is a schematic diagram of the structure of unfolding, hot pressing and strip cutting in Example 1 of the present invention;

[0037] Figure 3 This is a schematic diagram of the structure of winding, pre-cooling and film cutting in Example 2 of the present invention;

[0038] Figure 4 It is a front view of the long strip metallized film in the background technology of the present invention;

[0039] Figure 5 It is a top view of the long strip metallized film in the background technology of the present invention. DETAILED DESCRIPTION

[0040] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] Example 1, as Figure 1-2 As shown, the manufacturing process of the capacitor film core in this embodiment includes at least two unwinding mechanisms 1 unwinding a first single-layer film roll 2 and a second single-layer film roll 3, which are then unwound by a winder 4 into a roll, and further includes the following steps:

[0042] (1) Winding machine 4 and film roll arrangement: The core drum 41 of the winding machine 4 is capable of winding a roll with a large inner diameter; the first single-layer film roll 2 is provided with a left blank area 21 and a right metal coating 22 along its length, and the second single-layer film roll 3 is provided with a left metal coating 31 and a right blank area 32 along its length;

[0043] (2) Winding into a large inner diameter coil 5: The first single-layer film roll 2 and the second single-layer film roll 3 are stacked up and down, and the left blank area 21 of the adjacent first single-layer film roll 2 and the second single-layer film roll 3 corresponds to the left metal coating 31, and the right metal coating 22 corresponds to the right blank area 32. The first single-layer film roll 2 and the second single-layer film roll 3 are wound onto the core drum 41 of the winder 4; then, according to the number of layers of capacitor film required, the core drum 41 is driven to rotate by the winder 4, so that the films released from each first single-layer film roll 2 and each second single-layer film roll 3 are wound into a large inner diameter coil 5, and then disassembled;

[0044] (3) Pre-cold pressing: Place the disassembled large inner diameter coil 5 in a cold isostatic press. Under the conditions of a pressure range of 20MPa-80MPa and a temperature of 22℃-27℃, use the cold isostatic press to pre-cold press the large inner diameter coil 360° uniformly for 60 seconds to 120 seconds to make the large inner diameter coil 5 thicker.

[0045] (4) Film cutting and unfolding: The pre-cold-pressed large inner diameter coil 5 is cut axially by a cutter 6. After cutting, the large inner diameter coil 5 is transformed into a long capacitor core blank 7 with multiple layers of film overlapping. The two sides of the long capacitor core blank 7 are unfolded and flattened to the two sides of the core tube 41;

[0046] (5) Hot pressing and densification: Place the flattened long capacitor core blank 7 into a hot press. Under the conditions of a pressure range of 5MPa-10MPa and a temperature of 100℃-110℃, use a hot press to hot press the long capacitor core blank 7 for 120 seconds-240 seconds to make the long capacitor core blank 7 dense.

[0047] (6) Cutting and stripping: According to the specifications of the capacitor products, the dense long strip capacitor core blank 7 is cut into multiple capacitor core semi-finished products 8 of the same size;

[0048] (7) The left end face and the right end face of the capacitor core semi-finished product 8 are respectively used to connect to the pins 9 of the capacitor. The left pin 9 is connected in parallel with the alternate metal coating layers on the left end face of the capacitor core semi-finished product 8 by welding, and the right pin 9 is connected in parallel with the alternate metal coating layers on the right end face of the capacitor core semi-finished product 8 by welding.

[0049] In the above step (1), the inner diameter of the large inner diameter coil is not strictly limited. Generally, after cutting, multiple capacitor core semi-finished products 8 can be cut out. Generally speaking, the larger the inner diameter, the longer the long strip capacitor core blank 7 after cutting, and the more capacitor core semi-finished products 8 can be cut out at one time, and the efficiency is relatively higher.

[0050] In the above step (2), the metal coatings of the first single-layer film roll 2 and the second single-layer film roll 3 adjacent to each other are staggered in the left and right directions. The left blank area 21 of the first single-layer film roll 2 corresponds to the left metal coating 31 of the second single-layer film roll, and the right metal coating 22 of the first single-layer film roll 2 corresponds to the right blank area 32 of the second single-layer film roll. The metal coatings on the same side are spaced apart from each other, forming a staggered parallel structure of interlayer metal coatings, rather than the traditional head-to-tail series connection. This staggered parallel structure of interlayer metal coatings has the following advantages: (a) local damage isolation: damage to a single layer of film only reduces the metal coating area of ​​that layer, thus avoiding the problem of "single layer fracture leading to large-area failure" from the root, laying the foundation for the stability of subsequent steps; (b) improved capacitance uniformity: avoids concentrated stress and thermal stress concentration; (c) enhanced reliability: can equivalently increase the effective area of ​​the plate (multiple metal coatings participate in charging and discharging in parallel), while ensuring the capacitance value, improving redundancy and reducing the risk of single point failure; improving the service life of the overall capacitor; and improving the stability of electrical performance.

[0051] In the above step (3), cold isostatic pressing (CIP) is a process that applies isotropic high pressure to materials at room temperature. It has been widely used in the fields of ceramics, powder metallurgy, etc., but its use in pre-pressing capacitor coils is an innovative application that can effectively solve the problem of looseness inside the large inner diameter coil 5. Under the action of high pressure, the layers of film inside the coil are evenly compressed, and the air between the layers is squeezed out, making the originally loose large coil thicker and denser. This pre-cold pressing step has multiple functions: first, it improves the overall density and tightness of the coil, providing a solid matrix for subsequent slicing; second, through isotropic pressure, the radial and circumferential forces on the coil are uniform, avoiding local deformation or interlayer sliding that may be caused by direct hot pressing; third, cold isostatic pressing is carried out at room temperature and will not cause thermal effects on the properties of the film material.

[0052] In the above step (4), the large inner diameter coil 5 that has been pre-cold pressed has a high degree of compactness, which is convenient for cutting. The large inner diameter coil 5 is cut axially using a cutter 6. The cutting position can be selected on the upper surface of the large inner diameter coil 5, and the cutting is carried out from the outer to the inner surface of the upper surface of the large inner diameter coil 5 to the upper surface of the core tube 41. This cutting method can cut the flat cylindrical large inner diameter coil 5 into a flat long strip capacitor core blank 7, which creates conditions for subsequent hot pressing and slicing. Since the pre-cold pressing makes the layers of film tightly bonded, the multi-layer film will not loosen and fall off during the unfolding process, but will maintain a multi-layered structure, and the final result is a large-format long strip capacitor core blank 7 with multiple layers of film overlapping.

[0053] In step (5) above, heat pressure is used to slightly soften the film material, thereby eliminating the tiny gaps between the layers under pressure, achieving close bonding between the layers and uniform overall thickness. After hot pressing, the multi-layer long strip capacitor core blank 7 becomes more dense and flat, and its thickness and density meet the process requirements. Compared with the traditional hot pressing of only a single small core, this process hot presses the entire long strip capacitor core blank 7, which is more efficient and the force is evenly distributed across all parts.

[0054] After the cutting is completed in the above step (6), the multiple semi-finished capacitor cores 8 obtained can enter the next process of capacitor assembly, such as gold spraying, lead welding, packaging, etc. In the gold spraying process, the end faces of multiple side-by-side semi-finished capacitor cores 8 can be metallized at one time, thereby improving equipment utilization. This simplifies the subsequent process flow and is conducive to the continuous and automated manufacturing of capacitors. Since this process has already combined the processing of multiple layers of thin films in the early stage, each semi-finished capacitor core 8 does not need to be wound again in the future, and can be directly laminated to form a capacitor core, thereby shortening the entire process flow.

[0055] The core drum 41 is composed of at least two winding rods 411 deviating from the rotation center of the winder 4. Of course, the core drum 41 can also be composed of winding rods 411 with a large diameter.

[0056] At least two of the winding rods 411 are on the same straight line with the rotation center. More preferably, the two winding rods 411 are symmetrically arranged with respect to the rotation center.

[0057] The distance between the two winding rods 411 is greater than 200mm. Setting the distance between the two winding rods 411 to greater than 200mm allows for winding of longer, wider strips of capacitor core blanks 7, at least 400mm in length. Therefore, if the size of the capacitor core semi-finished product 8 is 10mm, approximately 40 capacitor core semi-finished products 8 can be cut out. Furthermore, the longer distance between the two winding rods 411 provides more stable support for the film, resulting in a more even distribution of axial tension during winding, reducing edge wrinkles caused by a too-short distance between the two winding rods 411 and ensuring interlayer alignment accuracy.

[0058] The winding machine 4 is equipped with a tension sensor, a servo motor, and a controller. The core drum 41 is mounted on the winding machine 4's rotating shaft, and the servo motor's power output shaft is in driving connection with the winding machine 4's rotating shaft. The tension sensor's signal output terminal is electrically connected to the controller's corresponding signal input terminal, and the servo motor is electrically connected to the controller's corresponding signal output terminal. The controller first sets a target tension value. The tension sensor then monitors the tension data of the large inner diameter web 5 in real time. The controller compares the real-time tension data with the preset target tension value, calculates the tension deviation, and sends the tension deviation to the controller. The controller processes the tension deviation and sends a signal to adjust the speed of the servo motor's power output shaft. If the real-time tension data is too high or too low, the controller sends a command to the servo motor to adjust the speed of the servo motor's power output shaft. This automatic tension control adjusts the tension of each film layer by controlling the rotation speed of the winding machine 4, preventing film deformation or interlayer slippage caused by tension fluctuations, thereby ensuring winding quality and consistency.

[0059] The cold isostatic press utilizes a staged pressurization process during pre-cold pressing: the total pre-cold pressure is divided into a lower pressure and a target pressure. The large inner diameter coil 5 is initially held at a lower pressure of 5MPa-15MPa for 20-30 seconds, then gradually increased to the target pressure of 20MPa-80MPa and maintained at the final pressure for 40-90 seconds. This staged pressurization allows sufficient time for air inside the large inner diameter coil 5 to escape, preventing air from being trapped under high pressure and forming bubbles. Furthermore, staged pressurization reduces the impact of sudden high pressure on the edges of the large inner diameter coil 5, preventing film extrusion or damage at the edges.

[0060] In step (5), the long strip capacitor core blank 7 needs to be slowly cooled after hot pressing, so that the long strip capacitor core blank 7 can be reduced to room temperature while maintaining the pressure to fix its size and flatness.

[0061] Example 2, as Figure 3 As shown, the manufacturing process of the capacitor film core in this embodiment is different from that in embodiment 1 in that:

[0062] The core drum 41 is a cylinder 42 that rotates around the rotation center of the winding machine. The outer diameter of the cylinder 42 is 600 mm.

[0063] In addition, it should be noted that the names of the various parts of the specific embodiments described in this specification may be different. Any equivalent or simple changes made based on the structure, features, and principles described in the patent concept of the present invention are included in the scope of protection of the patent of this invention. Those skilled in the art of the technical field to which the present invention relates may make various modifications, supplements, or replace the specific embodiments described in the description with similar methods. As long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, they shall fall within the scope of protection of the present invention.

Claims

1. A process for manufacturing a capacitor film core, comprising: a first single-layer film roll and a second single-layer film roll being unwound by at least two unwinding mechanisms; the first single-layer film roll and the second single-layer film roll being unwound and wound into a roll by a winder; and characterized in that: The following steps are also included: (1) Winding machine and film roll arrangement: the core drum of the winding machine is capable of winding a roll with a large inner diameter; the first single-layer film roll is provided with a left blank area and a right metal coating along its length, and the second single-layer film roll is provided with a left metal coating and a right blank area along its length; (2) Winding into a coil with a large inner diameter: The first single-layer film roll and the second single-layer film roll are stacked up and down, and the left blank area of ​​the adjacent first single-layer film roll and the second single-layer film roll correspond to the left metal coating, and the right metal coating corresponds to the right blank area. The first single-layer film roll and the second single-layer film roll are wound onto the core drum of the winding machine; then, according to the requirements of the number of capacitor film layers, the core drum is driven to rotate by the winding machine so that the films released from each first single-layer film roll and each second single-layer film roll are wound into a coil with a large inner diameter and removed; (3) Pre-cold pressing: Place the disassembled large inner diameter coil into a cold isostatic press. Under the conditions of a pressure range of 20MPa-80MPa and a temperature of 22℃-27℃, use a cold isostatic press to pre-cold press the large inner diameter coil for 60 seconds to 120 seconds with a 360° uniform pressure to make the large inner diameter coil thicker. (4) Cutting and unfolding the film: Use a cutter to cut the pre-cold-pressed large inner diameter coil along the axial direction. After cutting, the large inner diameter coil becomes a long capacitor core blank with multiple layers of film overlapping. The two sides of the long capacitor core blank are unfolded and flattened to the two sides of the core tube respectively; (5) Hot pressing and densification: Place the flattened long capacitor core blank into a hot press. Under the conditions of a pressure range of 5MPa-10MPa and a temperature of 100℃-110℃, use a hot press to flatten the long capacitor core blank for 120 seconds-240 seconds to make the long capacitor core blank dense. (6) Cutting and stripping: According to the specifications of the capacitor products, the dense long strip capacitor core blank is cut into multiple capacitor core semi-finished products of the same size.

2. The process for manufacturing a capacitor film core according to claim 1, characterized in that: The method further includes step (7), wherein the left end face and the right end face of the capacitor core semi-finished product are respectively used to connect to the pins of the capacitor, the left pins are connected in parallel with the layers of alternating metal coatings on the left end face of the capacitor core semi-finished product by welding, and the right pins are connected in parallel with the layers of alternating metal coatings on the right end face of the capacitor core semi-finished product by welding.

3. The process for manufacturing a capacitor film core according to claim 1, characterized in that: The core barrel is composed of at least two winding rods offset from the rotation center of the winder.

4. The process for manufacturing a capacitor film core according to claim 3, characterized in that: At least two of the winding rods are on the same straight line with the rotation center.

5. The process for manufacturing a capacitor film core according to claim 4, characterized in that: The two winding rods are symmetrically arranged around the rotation center.

6. The process for manufacturing a capacitor film core according to claim 3, characterized in that: The distance between the two winding rods is greater than 200 mm.

7. The process for manufacturing a capacitor film core according to claim 1, characterized in that: The core drum is a cylinder that rotates around the rotation center of the winder; The outer diameter of the cylinder is greater than 200 mm.

8. The process for manufacturing a capacitor film core according to claim 1, characterized in that: The winding machine is provided with a tension sensor, a servo motor and a controller. The core drum is installed on the rotating shaft of the winding machine, and the power output shaft of the servo motor is transmission-connected to the rotating shaft of the winding machine; the signal output end of the tension sensor is electrically connected to the corresponding signal input end of the controller, and the servo motor is electrically connected to the corresponding signal output end of the controller; the controller first presets a target tension value, and monitors the tension data of the large inner diameter coil in real time through the tension sensor. The controller compares the real-time tension data with the preset target tension value, calculates the tension deviation, and sends the tension deviation to the controller. After processing, the controller sends a signal to adjust the speed of the power output shaft of the servo motor.

9. The process for manufacturing a capacitor film core according to claim 1, characterized in that: The cold isostatic press adopts a segmented pressurization process during pre-cold pressing: the total pressure of the pre-cold pressing is divided into a lower pressure and a target pressure, and the large inner diameter coil is first maintained at a lower pressure of 5MPa-15MPa for 20 seconds to 30 seconds, and then gradually increased to a target pressure of 20MPa-80MPa and the final pressure is maintained for 40 seconds to 90 seconds.

10. The process for manufacturing a capacitor film core according to claim 1, characterized in that: In the step (5), the long strip capacitor core blank needs to be slowly cooled after hot pressing, so that the long strip capacitor core blank is cooled to room temperature while maintaining the pressure, so as to fix its size and flatness.

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