Verification tooling and verification methods

Abstract

The present invention belongs to the technical field of optical lenses, and discloses a verification tool and a verification method. The verification tool is used to load plastic lenses. The verification tool comprises a metal main barrel, a base and a pressure cover. A plurality of plastic lenses are sequentially arranged in the inner cavity of the metal main barrel along the axial direction; the base is arranged at one end of the metal main barrel, and the pressure cover is arranged at the other end of the metal main barrel. The base and the pressure cover are used to restrict the plastic lenses to the inner cavity. The present invention uses the verification tool to load plastic lenses, reduce interference, and improve verification accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of optical lenses, and in particular to a verification tool and a verification method. Background Art

[0002] Temperature performance is an important indicator in the reliability evaluation of optical lenses. It reflects whether the optical lens can maintain normal image resolution in a harsh temperature environment. For optical lenses using plastic lenses and plastic lens barrels, it is difficult to judge the degree of degradation of image resolution in a harsh temperature environment. The black matter produced by the plastic lens barrel in a harsh temperature environment interferes with the image resolution process. The black matter is very troublesome for image resolution, resulting in the inability to determine the extent of the impact of the plastic lens and plastic lens barrel on the defocus of the optical lens.

[0003] Currently, there is a lack of testing methods for plastic lenses in harsh temperature environments, and the defocus value caused by plastic lenses to optical lenses cannot be determined.

[0004] Therefore, a verification tool and a verification method are urgently needed to solve the above problems. Summary of the invention

[0005] One object of the present invention is to provide a verification tool for loading plastic lenses, reduce interference, and improve verification accuracy.

[0006] Another object of the present invention is to provide a verification method, using the above verification tooling to load a plastic lens, thereby reducing interference and improving verification accuracy.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, a verification tool is provided for loading a plastic lens, the verification tool comprising:

[0009] A metal main cylinder, wherein a plurality of plastic lenses are sequentially arranged in the inner cavity of the metal main cylinder along the axial direction;

[0010] The base and the pressure cover are arranged at one end of the metal main tube, and the pressure cover is arranged at the other end of the metal main tube. The base and the pressure cover are used to limit the plastic lens in the inner cavity.

[0011] As an optional technical solution, the verification tool further includes a spacer ring, which is arranged in the inner cavity and is used to adjust the installation position of the plastic lens in the inner cavity.

[0012] As an optional technical solution, the inner cavity is provided with four plastic lenses, which are respectively a first lens, a second lens, a third lens and a fourth lens, and the first lens, the second lens, the third lens and the fourth lens are arranged in sequence along the direction from the pressure cover to the base;

[0013] When verification is required in a short-focus state, the spacer ring is provided between the second lens and the third lens and between the third lens and the fourth lens;

[0014] When verification is required in a telephoto state, the spacer ring is provided between the first lens and the second lens, between the second lens and the third lens, and between the third lens and the fourth lens.

[0015] As an optional technical solution, the spacer ring is made of metal material.

[0016] As an optional technical solution, the verification tool further includes a plurality of metal mounting frames, a plurality of the plastic lenses are embedded in the plurality of metal mounting frames in a one-to-one correspondence, and the plurality of the metal mounting frames are sequentially installed in the inner cavity along the axial direction.

[0017] As an optional technical solution, central axes of all the metal installation frames are arranged to coincide with each other.

[0018] As an optional technical solution, the spacer ring and the plastic lens do not contact each other.

[0019] As an optional technical solution, the base includes a first connecting portion and a first limiting portion, the inner wall of the first connecting portion is provided with an internal thread, the outer wall of one end of the metal main tube is provided with an external thread, the first connecting portion is threadedly connected to the metal main tube, the first limiting portion extends radially to one side of the inner cavity port, and the first limiting portion is used to limit the plastic lens to the inner cavity; and / or

[0020] The pressure cover includes a second connecting portion and a second limiting portion, the inner wall of the second connecting portion is provided with an internal thread, the outer wall of the other end of the metal main tube is provided with an external thread, the second connecting portion is threadedly connected to the metal main tube, the second limiting portion extends radially to one side of the inner cavity port, and the second limiting portion is used to limit the plastic lens to the inner cavity.

[0021] In a second aspect, a verification method is provided, wherein the plastic lens is loaded with the verification tool as described above, and the verification method comprises the following steps:

[0022] S100, embedding the plastic lens in a metal mounting frame;

[0023] S200, installing the spacer ring and the metal installation frame into the inner cavity of the metal main cylinder, and adjusting the installation position of the metal installation frame in the inner cavity by using the spacer ring;

[0024] S300, using the base and / or the gland to restrict the spacer ring and the metal mounting frame to the inner cavity;

[0025] S400. Use a camera and the verification tooling to perform a temperature test.

[0026] As an optional technical solution, step S200 includes:

[0027] Obtain two of the spacer rings and four of the metal mounting frames, and sequentially install the first metal mounting frame, the first spacer ring, the second metal mounting frame, the second spacer ring, the third metal mounting frame and the fourth metal mounting frame into the inner cavity along the axial direction;

[0028] Obtain three spacer rings and four metal mounting frames, and sequentially install the first metal mounting frame, the first spacer ring, the second metal mounting frame, the second spacer ring, the third metal mounting frame, the third spacer ring and the fourth metal mounting frame into the inner cavity along the axial direction.

[0029] The beneficial effects of the present invention are:

[0030] The verification tool provided by the present invention includes a metal main cylinder, a base and a pressure cover. A plurality of plastic lenses are sequentially loaded into the inner cavity of the metal main cylinder along the axial direction, and the base and the pressure cover are used to confine the plastic lenses in the inner cavity. When verifying the virtual focus value generated by the plastic lenses at a preset temperature, the metal main cylinder will not produce black matter, thereby avoiding interference and improving the verification accuracy of the virtual focus value generated by the plastic lenses at the preset temperature.

[0031] The verification method provided by the present invention adopts the above verification tooling to load the plastic lens, thereby improving the verification accuracy of the virtual focus value generated by the plastic lens at a preset temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention is further described in detail below based on the accompanying drawings and embodiments;

[0033] Figure 1 An exploded view of the verification tool (with two spacer rings) described in the embodiment;

[0034] Figure 2 It is a cross-sectional view of the verification tool (provided with two spacer rings) described in the embodiment;

[0035] Figure 3An exploded view of the verification tool (with three spacer rings) described in the embodiment;

[0036] Figure 4 It is a cross-sectional view of the verification tool (provided with three spacer rings) described in the embodiment;

[0037] Figure 5 The present invention is a flow chart of the verification method described in the embodiment.

[0038] In the figure:

[0039] 100. Plastic lenses;

[0040] 1. Metal main cylinder; 11. Inner cavity; 12. Exhaust hole;

[0041] 2. Base; 21. First connecting portion; 22. First limiting portion; 23. Connecting hole;

[0042] 3. gland; 31. second connection portion; 32. second limit portion;

[0043] 4. Spacer ring;

[0044] 5. Metal installation frame. DETAILED DESCRIPTION

[0045] In order to make the technical problems solved by the present invention, the technical solutions adopted and the technical effects achieved clearer, the technical solutions of the embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0046] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0047] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0048] In the description herein, it should be understood that the terms "upper", "lower", "left", "right", etc., and the like, are based on the directions or positions shown in the drawings, and are only for the convenience of description and simplified operation, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0049] In the description of this specification, the description with reference to the terms "an embodiment", "example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example.

[0050] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0051] like Figures 1 to 4 As shown, this embodiment provides a verification tool, which is used to load plastic lenses 100. The verification tool includes a metal main cylinder 1, a base 2 and a pressure cover 3. Several plastic lenses 100 are arranged in sequence in the inner cavity 11 of the metal main cylinder 1 along the axial direction; the base 2 is arranged at one end of the metal main cylinder 1, and the pressure cover 3 is arranged at the other end of the metal main cylinder 1. The base 2 and / or the pressure cover 3 are used to confine the plastic lenses 100 to the inner cavity 11.

[0052] Specifically, the present embodiment uses the metal main barrel 1 to load the plastic lens 100, which can eliminate the interference caused by the plastic black object of the plastic lens barrel. A plurality of plastic lenses 100 are sequentially loaded into the inner cavity 11 of the metal main barrel 1 along the axial direction, and the plastic lenses 100 are confined to the inner cavity 11 by the base 2 and / or the pressure cover 3. When verifying the virtual focus value generated by the plastic lens 100 at a preset temperature, the metal main barrel 1 will not generate black objects, thereby avoiding interference and improving the verification accuracy of the virtual focus value generated by the plastic lens 100 at a preset temperature.

[0053] In this embodiment, the metal main tube 1 has a simple structure and few components are installed in the inner cavity 11. The components installed in the inner cavity 11 are only the plastic lens 100, the spacer ring 4 and the metal mounting frame 5, which can reduce the interference caused by the complex structure.

[0054] A base 2 and a pressure cover 3 are respectively provided at both ends of the metal main tube 1, so that the verification tooling can be used for projection and MTF analysis (Modulation Transfer Function, a method for analyzing and evaluating lenses); in this embodiment, the base 2 is provided with a connecting hole 23, and a threaded fastener is passed through the connecting hole 23 and threadedly connected to the camera, so that the base 2 is fixed to the camera, and the verification tooling is combined with the camera to perform a temperature test.

[0055] Optionally, the metal main cylinder 1 is made of stainless steel or aluminum alloy.

[0056] Optionally, the verification tool further includes a spacer ring 4 , which is disposed in the inner cavity 11 , and is used to adjust the installation position of the plastic lens 100 in the inner cavity 11 .

[0057] The spacer ring 4 is used to adjust the installation position of the plastic lens 100 in the inner cavity 11, so as to verify the virtual focus values ​​of the plastic lens 100 at different focal lengths. The spacer ring 4 is easy to disassemble and assemble, and can be quickly replaced, and only a small number of spacer rings 4 are needed to verify the virtual focus values ​​at multiple focal lengths.

[0058] In this embodiment, the inner cavity 11 is provided with four plastic lenses 100 , which are respectively a first lens, a second lens, a third lens and a fourth lens. The first lens, the second lens, the third lens and the fourth lens are arranged in sequence along the direction from the pressure cover 3 to the base 2 .

[0059] When verification is required in the short-focus state, a spacer ring 4 is provided between the second lens and the third lens, and between the third lens and the fourth lens. Spacer rings 4 are provided between the second lens and the third lens, and between the third lens and the fourth lens, respectively. The spacer ring 4 between the second lens and the third lens is a first short-focus spacer ring, and the spacer ring 4 between the third lens and the fourth lens is a second short-focus spacer ring, to verify the virtual focus values ​​generated by the four plastic lenses 100 under a preset temperature environment in the short-focus state.

[0060] When verification is required in the telephoto state, a spacer ring 4 is provided between the first lens and the second lens, between the second lens and the third lens, and between the third lens and the fourth lens. Spacer rings 4 are provided between the first lens and the second lens, between the second lens and the third lens, and between the third lens and the fourth lens, respectively. The spacer ring 4 between the first lens and the second lens is a first short-focus spacer ring, the spacer ring 4 between the second lens and the third lens is a second short-focus spacer ring, and the spacer ring 4 between the third lens and the fourth lens is a third short-focus spacer ring, to verify the virtual focus values ​​generated by the four plastic lenses 100 in the preset temperature environment in the telephoto state.

[0061] Optionally, the spacer ring 4 is made of metal material to avoid the spacer ring 4 from producing black matter and reduce interference.

[0062] Optionally, the verification tool further includes a plurality of metal mounting frames 5, a plurality of plastic lenses 100 are embedded in the plurality of metal mounting frames 5 in a one-to-one correspondence, and the plurality of metal mounting frames 5 are sequentially installed in the inner cavity 11 along the axial direction.

[0063] In a harsh temperature environment, such as a high temperature environment, there may be adhesion between the plastic material and the metal material. If the plastic lens 100 is bonded to the inner wall of the metal main tube 1, plastic material may be left on the inner wall of the metal main tube 1. If the metal main tube 1 is used again, the plastic material remaining on the inner wall of the metal main tube 1 will turn into black matter, interfering with the verification accuracy, resulting in the metal main tube 1 with the plastic material adhering to it having to be scrapped and cannot be reused, which is costly.

[0064] In order to make the plastic lens 100 reusable, in this embodiment, the plastic lens 100 is installed in the metal mounting frame 5, and then the metal mounting frame 5 is installed in the inner cavity 11 of the metal main tube 1. After the verification is completed, the metal mounting frame 5 and the plastic lens 100 are taken out together to prevent the plastic lens 100 from leaving plastic material on the inner wall of the metal main tube 1 due to adhesion.

[0065] Optionally, central axes of all metal installation frames 5 are arranged to coincide with each other.

[0066] The outer wall of the metal mounting frame 5 is tightly abutted against the inner wall of the metal main tube 1, and is positioned by an axial hole matching method to improve coaxiality, improve image resolution quality, facilitate judgment, and facilitate disassembly and assembly, which can prevent the metal mounting frame 5 from radially offset in the inner cavity 11. In this embodiment, the central axes of the four metal mounting frames 5 are arranged to coincide with each other to ensure that the central axes of the four plastic lenses 100 coincide with each other.

[0067] Optionally, the spacer ring 4 and the plastic lens 100 are not in contact with each other.

[0068] When verification is required in the short-focus state, the metal mounting frame 5 with the first lens installed is abutted against the metal mounting frame 5 with the second lens installed, the metal mounting frame 5 with the second lens installed and the metal mounting frame 5 with the third lens installed are respectively abutted against the two ends of the first short-focus spacer ring, and the metal mounting frame 5 with the third lens installed and the metal mounting frame 5 with the fourth lens are respectively abutted against the two ends of the second short-focus spacer ring, so as to avoid the plastic lens 100 leaving plastic material on the surface of the spacer ring 4 due to adhesion. The spacer ring 4 of this embodiment can be reused to reduce costs.

[0069] When verification is required in the telephoto state, the metal mounting frame 5 with the first lens installed and the metal mounting frame 5 with the second lens installed are respectively abutted against the two ends of the first short-focus spacer ring, the metal mounting frame 5 with the second lens installed and the metal mounting frame 5 with the third lens installed are respectively abutted against the two ends of the second short-focus spacer ring, and the metal mounting frame 5 with the third lens installed and the metal mounting frame 5 with the fourth lens installed are respectively abutted against the two ends of the third short-focus spacer ring, so as to avoid the plastic lens 100 leaving plastic material on the surface of the spacer ring 4 due to adhesion. The spacer ring 4 of this embodiment can be reused to reduce costs.

[0070] Optionally, the base 2 includes a first connection portion 21 and a first limiting portion 22, the inner wall of the first connection portion 21 is provided with an internal thread, the outer wall of one end of the metal main tube 1 is provided with an external thread, the first connection portion 21 is threadedly connected to the metal main tube 1, the first limiting portion 22 extends radially to one side of the end of the inner cavity 11, and the first limiting portion 22 is used to limit the plastic lens 100 to the inner cavity 11. The first limiting portion 22 is provided with a first light-transmitting portion, and light can pass through the first light-transmitting portion.

[0071] Optionally, the gland 3 includes a second connection portion 31 and a second limiting portion 32, the inner wall of the second connection portion 31 is provided with an internal thread, the outer wall of the other end of the metal main tube 1 is provided with an external thread, the second connection portion 31 is threadedly connected to the metal main tube 1, and the second limiting portion 32 extends radially to one side of the port of the inner cavity 11, and the second limiting portion 32 is used to limit the plastic lens 100 to the inner cavity 11. The second limiting portion 32 is provided with a second light-transmitting portion, and light can pass through the second light-transmitting portion.

[0072] Optionally, a side wall of the inner cavity 11 is provided with an exhaust hole 12, and the exhaust hole 12 is used to discharge the gas in the inner cavity 11 to the outside.

[0073] like Figure 5 As shown, this embodiment also provides a verification method, using the above verification tool to load the plastic lens 100, the verification method includes the following steps:

[0074] S100 , embedding the plastic lens 100 in the metal mounting frame 5 .

[0075] S200 , installing the spacer ring 4 and the metal installation frame 5 into the inner cavity 11 of the metal main tube 1 , and adjusting the installation position of the metal installation frame 5 in the inner cavity 11 by using the spacer ring 4 .

[0076] S300 , the base 2 and the pressure cover 3 are used to confine the spacer ring 4 and the metal mounting frame 5 to the inner cavity 11 .

[0077] S400, use camera with verification tooling to conduct temperature test.

[0078] In step S100, the metal mounting frame 5 is used to isolate and protect the plastic lens 100 to prevent the plastic lens 100 from leaving plastic materials on other components such as the metal main tube 1. In step S200, the spacer ring 4 is used to adjust the installation position of the metal mounting frame 5 in the inner cavity 11, which is convenient for disassembly and assembly and can be quickly replaced. Only a small number of spacer rings 4 are needed to verify the virtual focus values ​​generated under multiple focal lengths. In step S300, the base 2 and / or the pressure cover 3 are used to restrict the spacer ring 4 and the metal mounting frame 5 to the inner cavity 11 to prevent the spacer ring 4 and the metal mounting frame 5 from axially separating from the inner cavity 11 during the verification process. In this embodiment, the second limiting portion 32 of the pressure cover 3 abuts against the metal mounting frame 5 on which the first lens is installed, and a third limiting portion is provided on the inner wall of one end of the metal main tube 1 connected to the base 2, and the third limiting portion is used to abut against the metal mounting frame 5 on which the fourth lens is installed, thereby fixing the metal mounting frame 5 and the spacer ring 4. In some other embodiments, the first limiting portion 22 of the base 2 abuts against the metal mounting frame 5 on which the fourth lens is installed, and a fourth limiting portion is provided on the inner wall of one end of the metal main tube 1 connected to the pressure cover 3, and the fourth limiting portion is used to abut against the metal mounting frame 5 on which the first lens is installed.

[0079] Optionally, the base 2 and / or the pressure cover 3 are made of metal material.

[0080] Optionally, step S200 includes:

[0081] Obtain two spacer rings 4 and four metal mounting frames 5, and sequentially install the first metal mounting frame 5, the first spacer ring 4, the second metal mounting frame 5, the second spacer ring 4, the third metal mounting frame 5 and the fourth metal mounting frame 5 into the inner cavity 11 along the axial direction. This step is used when verification is required in the short-focus state.

[0082] Obtain three spacer rings 4 and four metal mounting frames 5, and sequentially install the first metal mounting frame 5, the first spacer ring 4, the second metal mounting frame 5, the second spacer ring 4, the third metal mounting frame 5, the third spacer ring 4 and the fourth metal mounting frame 5 into the inner cavity 11 along the axial direction. This step is used when verification is required in the telephoto state.

[0083] In addition, the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A verification tool for loading a plastic lens (100), characterized in that: The verification tooling comprises: A metal main cylinder (1), wherein a plurality of plastic lenses (100) are sequentially arranged in the inner cavity (11) of the metal main cylinder (1) along the axial direction; A base (2) and a pressure cover (3), wherein the base (2) is arranged at one end of the metal main tube (1), and the pressure cover (3) is arranged at the other end of the metal main tube (1), and the base (2) and / or the pressure cover (3) are used to confine the plastic lens (100) in the inner cavity (11); The verification tool further comprises a spacer ring (4), wherein the spacer ring (4) is arranged in the inner cavity (11), and the spacer ring (4) is used to adjust the installation position of the plastic lens (100) in the inner cavity (11); The inner cavity (11) is provided with four plastic lenses (100), the four plastic lenses (100) are respectively a first lens, a second lens, a third lens and a fourth lens, the first lens, the second lens, the third lens and the fourth lens are arranged in sequence along the direction from the pressure cover (3) to the base (2); When verification is required in a short-focus state, the spacer ring (4) is provided between the second lens and the third lens, and between the third lens and the fourth lens; When verification is required in a telephoto state, the spacer ring (4) is provided between the first lens and the second lens, between the second lens and the third lens, and between the third lens and the fourth lens.

2. The verification tool according to claim 1, characterized in that: The material of the spacer ring (4) is metal material.

3. The verification tool according to claim 1, characterized in that: The verification tool also includes a plurality of metal installation frames (5), a plurality of the plastic lenses (100) are embedded in the plurality of metal installation frames (5) in a one-to-one correspondence, and the plurality of the metal installation frames (5) are sequentially installed in the inner cavity (11) along the axial direction.

4. The verification tool according to claim 3, characterized in that: The central axes of all the metal installation frames (5) are arranged to coincide with each other.

5. The verification tool according to claim 3, characterized in that: The spacer ring (4) and the plastic lens (100) do not contact each other.

6. The verification tool according to claim 1, characterized in that: The base (2) comprises a first connecting portion (21) and a first limiting portion (22); the inner wall of the first connecting portion (21) is provided with an internal thread; the outer wall of one end of the metal main tube (1) is provided with an external thread; the first connecting portion (21) is threadedly connected to the metal main tube (1); the first limiting portion (22) extends radially to one side of the port of the inner cavity (11); the first limiting portion (22) is used to limit the plastic lens (100) to the inner cavity (11); and / or The pressure cover (3) comprises a second connecting portion (31) and a second limiting portion (32); the inner wall of the second connecting portion (31) is provided with an internal thread; the outer wall of the other end of the metal main tube (1) is provided with an external thread; the second connecting portion (31) is threadedly connected to the metal main tube (1); the second limiting portion (32) extends radially to one side of the port of the inner cavity (11); the second limiting portion (32) is used to limit the plastic lens (100) to the inner cavity (11).

7. A verification method, characterized in that The plastic lens (100) is loaded with the verification tool as claimed in any one of claims 1 to 6, and the verification method comprises the following steps: S100, embedding the plastic lens (100) in a metal mounting frame (5); S200, installing the spacer ring (4) and the metal installation frame (5) into the inner cavity (11) of the metal main cylinder (1), and using the spacer ring (4) to adjust the installation position of the metal installation frame (5) in the inner cavity (11); S300, using the base (2) and / or the gland (3) to restrict the spacer ring (4) and the metal mounting frame (5) to the inner cavity (11); S400. Use a camera in combination with the verification tooling to perform a temperature test.

8. The verification method according to claim 7, characterized in that: The step S200 includes: Obtain two of the spacer rings (4) and four of the metal mounting frames (5), and sequentially install the first metal mounting frame (5), the first spacer ring (4), the second metal mounting frame (5), the second spacer ring (4), the third metal mounting frame (5), and the fourth metal mounting frame (5) into the inner cavity (11) along the axial direction; Obtain three of the spacer rings (4) and four of the metal mounting frames (5), and sequentially install the first metal mounting frame (5), the first spacer ring (4), the second metal mounting frame (5), the second spacer ring (4), the third metal mounting frame (5), the third spacer ring (4), and the fourth metal mounting frame (5) into the inner cavity (11) along the axial direction.

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