SMT chip mounter suction nozzle anti-blocking device

Abstract

The utility model provides an SMT chip mounter suction nozzle anti-blocking device which comprises a suction nozzle body and a suction nozzle cover, the upper end of the interior of the suction nozzle body is provided with an internal thread, the bottom of the suction nozzle cover is fixedly connected with a threaded connector, the suction nozzle cover is installed at the top of the suction nozzle body through the internal thread in a threaded mode, and the suction nozzle body is provided with a suction nozzle. A scraping mechanism is fixedly installed in the middle of the suction nozzle cover, a cleaning mechanism is fixedly connected to the portion, located on the outer side of the scraping cover, in the suction nozzle cover, an efficient cleaning system integrating scraping, washing and filtering is constructed, a driving motor drives a cleaning scraper to rotate and peel off solid pollutants, and an inclined scraper penetrates into a conical gap in the lower end of the suction nozzle to clean dead corners; an external water pump sprays high-pressure water flow through an annular pipe and an inclined cleaning rack pipe, the high-pressure water flow washes the inner wall by 360 degrees and carries impurities to the bottom, the impurities are intercepted by a magnetic adsorption filter screen, a suction nozzle cover is in threaded connection with a body, a sealing gasket is used for preventing leakage, parts can be replaced by unscrewing during maintenance, and disassembly abrasion is reduced.

Description

Technical Field

[0001] This utility model relates to the field of pick-and-place machine nozzle technology, and in particular to an anti-clogging device for SMT pick-and-place machine nozzles. Background Technology

[0002] In the SMT field of electronic manufacturing, the cleanliness of the pick-and-place machine nozzle directly affects the placement accuracy and quality. Traditional nozzles rely on manual disassembly and cleaning, which can easily cause interface wear and shorten the nozzle's lifespan. Furthermore, manual cleaning makes it difficult to reach the internal fine structure. Residual solder paste, metal debris, and other contaminants can easily cause component adsorption misalignment or block the negative pressure hole, weakening the adsorption force and causing defects such as placement misalignment and tombstoning, affecting soldering reliability and making it difficult to meet the high-precision placement requirements.

[0003] While the patent with announcement number "CN218499515U" removes impurities by rotating a scraper, avoiding the problem of frequent disassembly and wear, the cleaning method has obvious limitations. Simple scraping can only peel off impurities, but cannot remove them from inside the nozzle. Sticky or liquid contaminants are even more difficult to remove, and residual impurities still pose a risk of clogging. At the same time, the structure does not integrate a rinsing function, making it difficult to deal with complex contamination scenarios. When the cleaning components age and are damaged, the entire device needs to be disassembled and repaired, which is cumbersome and may damage the equipment seal, affecting stability. As electronic components develop towards miniaturization and high-density mounting, the shortcomings of existing nozzle cleaning technologies become increasingly apparent. Frequent downtime for cleaning reduces production efficiency, nozzle wear and consumable consumption increase maintenance costs, and incomplete cleaning may also cause batch quality defects. It is clear that the existing technology has certain defects and shortcomings, and therefore, it needs to be improved and redesigned. Utility Model Content

[0004] To address the aforementioned problems, this invention proposes an anti-clogging device for the nozzles of an SMT pick-and-place machine, which more accurately solves the problems described above.

[0005] This utility model is achieved through the following technical solution:

[0006] This utility model proposes an anti-clogging device for the nozzle of an SMT pick-and-place machine, including a nozzle body and a nozzle cover. The upper part of the nozzle body is provided with an internal thread, and the bottom of the nozzle cover is fixedly connected with a threaded interface. The nozzle cover is installed on the top of the nozzle body through the internal thread. A scraping mechanism is fixedly installed in the middle of the nozzle cover. A cleaning mechanism is fixedly connected inside the nozzle cover to the outside of the scraping cover. The scraping and cleaning end of the scraping mechanism is located inside the nozzle body and is in close contact with the inner wall of the nozzle body. A suction head is fixedly connected to the bottom of the nozzle body, and an air pump threaded connector is fixedly connected to the upper side of the nozzle cover.

[0007] The cleaning mechanism includes an annular tube, which is fixedly installed at the top inside the nozzle cover and located outside the scraping mechanism. The bottom of the annular tube is fixedly connected with a cleaning drain pipe arranged in a ring at equal intervals. The output end of the cleaning drain pipe is inclined towards the inner wall of the nozzle body. A connecting water pipe is fixedly connected to the outside of the annular tube, and a water pump threaded connector is fixedly connected to the outer end of the connecting water pipe.

[0008] Furthermore, the suction head is generally cone-shaped, narrower at the top and wider at the bottom, and an adsorption sealing ring is fixedly connected to the bottom of the suction head.

[0009] Furthermore, a sealing gasket is fixedly connected to the bottom of the nozzle cover, and the sealing gasket seals the gap between the nozzle body and the nozzle cover.

[0010] Furthermore, the scraping mechanism includes a drive motor, which is fixedly installed in the middle of the top of the nozzle cover. The output end of the drive motor passes through the nozzle cover and is fixedly connected to a turntable. The turntable is rotatably connected to the middle of the top inside the nozzle cover. Cleaning scrapers are fixedly installed in a ring at equal intervals on the outer side of the turntable. The cleaning scrapers are inserted into the nozzle body and their outer side is in close contact with the inner wall of the nozzle body.

[0011] Furthermore, an inclined scraper is fixedly installed at the lower end of the cleaning scraper, and the lower end of the suction nozzle body is conical. The outer side of the inclined scraper and the inner conical surface of the suction nozzle body are fitted together.

[0012] Furthermore, the top of the suction nozzle cover is fixedly connected with a mounting bracket arranged in a ring at equal intervals, and the upper end of the mounting bracket is provided with a mounting hole, which is a countersunk hole.

[0013] Furthermore, an upper magnetic ring is fixedly installed at the bottom of the suction head, and a lower magnetic ring is magnetically attracted to the suction head through the upper magnetic ring. A filter screen is fixedly connected to the bottom of the lower magnetic ring.

[0014] The beneficial effects of this utility model are:

[0015] 1. This technical solution constructs a highly efficient cleaning system integrating scraping, rinsing and filtration. The drive motor drives the cleaning scraper to rotate, removing solid contaminants. The inclined scraper penetrates deep into the conical gap at the bottom of the suction nozzle to clean dead corners. An external water pump sprays high-pressure water through a ring pipe and an inclined cleaning drain pipe, rinsing the inner wall 360° and carrying impurities to the bottom, where they are intercepted by a magnetic adsorption filter. The suction nozzle cover is threaded to the body, and a sealing gasket prevents leakage. During maintenance, parts can be replaced by unscrewing, reducing disassembly and wear.

[0016] 2. The solution achieves breakthroughs in cleaning efficiency, ease of maintenance, and structural reliability. The combined mechanism of mechanical scraping and high-pressure rinsing thoroughly removes solid and viscous liquid contaminants; the magnetic filter can be easily removed by hand, effectively shortening cleaning and maintenance time; the sealed structure ensures continuous and stable cleaning; the conical suction head with a sealing ring enhances the airtightness of the adsorption, and the magnetic filter blocks large particles of impurities, reducing the risk of clogging.

[0017] 3. This device can significantly improve the quality and efficiency of SMT placement during application. Its composite cleaning reduces the defect rate and is suitable for ultra-miniature components and high-density packaging. The modular nozzle cover is compatible with multiple nozzle specifications, improving the flexibility of the production line. The circulating cleaning fluid and reusable filter reduce consumables and comply with green manufacturing. The magnetic adsorption filtration and sealing design extend the nozzle life, reduce maintenance costs, and provide reliable placement guarantee for high-cleanliness fields. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0019] Figure 2 This is a schematic diagram of the structure of this utility model from below;

[0020] Figure 3 This is a top-view structural diagram of the entire disassembled state of this utility model;

[0021] Figure 4 This is a top view of the overall disassembled structure of this utility model;

[0022] Figure 5 This is a schematic diagram of the cleaning mechanism and the scraping mechanism of this utility model.

[0023] In the diagram: 1. Nozzle body; 2. Nozzle cover; 3. Scraping mechanism; 31. Drive motor; 32. Turntable; 33. Cleaning scraper; 34. Angled scraper; 4. Threaded interface; 5. Internal thread; 6. Cleaning mechanism; 61. Ring tube; 62. Cleaning drain pipe; 63. Connecting water pipe; 64. Water pump threaded connector; 7. Nozzle head; 8. Air pump threaded connector; 9. Adsorption sealing ring; 10. Sealing gasket; 11. Mounting bracket; 12. Mounting hole; 13. Upper magnetic ring; 14. Lower magnetic ring; 15. Filter screen. Detailed Implementation

[0024] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0025] Example 1

[0026] An anti-clogging device for a pick-and-place machine nozzle includes a nozzle body 1 and a nozzle cover 2. The upper part of the nozzle body 1 is provided with an internal thread 5. The bottom of the nozzle cover 2 is fixedly connected with a threaded interface 4. The nozzle cover 2 is threadedly installed on the top of the nozzle body 1 through the internal thread 5. A scraping mechanism 3 is fixedly installed in the middle of the nozzle cover 2. A cleaning mechanism 6 is fixedly connected inside the nozzle cover 2 on the outside of the scraping cover. The scraping and cleaning end of the scraping mechanism 3 is located inside the nozzle body 1 and is in close contact with the inner wall of the nozzle body 1. A suction head 7 is fixedly connected to the bottom of the nozzle body 1. An air pump threaded connector 8 is fixedly connected to the upper side of the nozzle cover 2.

[0027] The cleaning mechanism 6 includes an annular tube 61, which is fixedly installed at the top inside the nozzle cover 2 and located outside the scraping mechanism 3. Cleaning pipes 62 are fixedly connected to the bottom of the annular tube 61 in a ring-shaped arrangement at equal intervals. The output end of the cleaning pipes 62 is inclined towards the inner wall of the nozzle body 1. A connecting water pipe 63 is fixedly connected to the outer side of the annular tube 61, and a water pump threaded connector 64 is fixedly connected to the outer end of the connecting water pipe 63. During the application of this device, when cleaning of the nozzle is required, the air pump provides negative pressure to the inside of the nozzle through the air pump threaded connector 8, keeping the nozzle in an adsorption state; simultaneously, the water pump is connected to the connecting water pipe 63 through the water pump threaded connector 64. The cleaning solution is delivered to the annular tube 61 and then sprayed onto the inner wall of the nozzle body 1 through the cleaning drain pipe 62 at the bottom of the annular tube 61, forming a 360° rinsing effect. At this time, the drive motor 31 drives the turntable 32 of the scraping mechanism 3 to rotate, so that the cleaning scraper 33 rotates in close contact with the inner wall of the nozzle body 1, mechanically peeling off stubborn pollutants. The peeled impurities flow downward with the water flow and are intercepted by the magnetic filter screen 15 when passing through the suction head 7, preventing them from entering the negative pressure channel and causing blockage. Throughout the cleaning process, the nozzle cover 2 and the nozzle body 1 are tightly connected through the threaded interface 4, and the sealing gasket 10 ensures no liquid leakage, achieving efficient and comprehensive anti-clogging cleaning.

[0028] Combination Figures 1-3 As shown, the suction head 7 is generally conical in shape, narrow at the top and wide at the bottom. An adsorption sealing ring 9 is fixedly connected to the bottom of the suction head 7, and a sealing gasket 10 is fixedly connected to the bottom of the nozzle cover 2. The sealing gasket 10 seals the gap between the nozzle body 1 and the nozzle cover 2.

[0029] In the above-described embodiments of this application, the suction head 7 is designed as a cone shape that is narrow at the top and wide at the bottom. This can form a concentrated negative pressure area when adsorbing components, enhancing adsorption stability. At the same time, the cone-shaped structure reduces airflow dead angles, making it easier for impurities to collect at the bottom with the water flow. The bottom adsorption sealing ring 9 is made of elastic material, which fits tightly against the surface of the component when the suction head 7 contacts it, further improving airtightness and preventing adsorption failure or displacement due to air leakage. The sealing gasket 10 at the bottom of the nozzle cover 2 is made of flexible materials such as rubber. When the nozzle cover 2 is installed on the top of the nozzle body 1 through the threaded interface 4, the sealing gasket 10 is squeezed and filled in the gap between the two, forming a physical sealing barrier to prevent water or suction air from leaking from the connection during the cleaning process. This ensures the normal operation of the high-pressure rinsing and negative pressure adsorption functions, while preventing external dust from entering the nozzle and maintaining the reliability of the cleaning environment.

[0030] Example 2

[0031] Combination Figures 3-5 As shown, the scraping mechanism 3 includes a drive motor 31, which is fixedly installed in the middle of the top of the nozzle cover 2. The output end of the drive motor 31 passes through the nozzle cover 2 and is fixedly connected to a turntable 32. The turntable 32 is rotatably connected to the middle of the top of the nozzle cover 2. Cleaning scrapers 33 are fixedly installed in a ring at equal intervals on the outer side of the turntable 32. The cleaning scrapers 33 are inserted into the nozzle body 1 and their outer side is in close contact with the inner wall of the nozzle body 1. The lower end of the cleaning scraper 33 is fixedly installed... The nozzle body 1 is equipped with a slanted scraper 34. The lower end of the nozzle body 1 is conical. The outer side of the slanted scraper 34 is fitted and connected to the inner conical surface of the nozzle body 1. The top of the nozzle cover 2 is fixedly connected with a mounting bracket 11 arranged in a ring at equal intervals. The upper end of the mounting bracket 11 is provided with a mounting hole 12, which is a countersunk hole. An upper magnetic ring 13 is fixedly installed at the bottom of the nozzle 7. A lower magnetic ring 14 is magnetically attracted to the nozzle 7 through the upper magnetic ring 13. A filter screen 15 is fixedly connected to the bottom of the lower magnetic ring 14.

[0032] The technical solution described in the above-described embodiments of this application enables the drive motor 31 to start and rotate the turntable 32 when the SMT pick-and-place machine nozzle needs cleaning during application. This causes the cleaning scraper 33, fixed to the outside of the turntable 32, to rotate synchronously. The outer side of the cleaning scraper 33 is in close contact with the inner wall of the nozzle body 1, and the contaminants attached to the inner wall are peeled off through mechanical friction. Since the lower end of the nozzle body 1 is conical, the inclined scraper 34 at the lower end of the cleaning scraper 33 can be in contact with the inner conical surface, effectively removing stubborn impurities in this area. At the same time, the water pump delivers the cleaning fluid to the annular pipe 61 through the connecting water pipe 63, and then through the inclined setting The cleaning pipe 62 sprays water at high speed onto the inner wall of the nozzle body 1, creating a 360° rinsing effect. The detached contaminants flow downwards with the water flow. When the water flows through the suction head 7, the upper magnetic ring 13 at the bottom of the suction head 7 magnetically attracts the lower magnetic ring 14, causing the filter screen 15 fixed at the bottom of the lower magnetic ring 14 to be stably positioned inside the suction head 7. This intercepts and filters impurities in the water, preventing them from entering the negative pressure channel and causing blockage. Throughout the cleaning process, the nozzle cover 2 is mounted on the pick-and-place machine through the top mounting bracket 11 and countersunk hole, ensuring stable operation of the device. The sealing gasket 10 ensures the sealing of the connection between the nozzle cover 2 and the nozzle body 1, preventing leakage of cleaning fluid.

[0033] The working principle and advantages of this utility model are as follows: This technical solution integrates scraping, rinsing and filtering functions to build a highly efficient cleaning system. The specific working process is as follows: After the drive motor 31 starts, it drives the turntable 32 and the cleaning scraper 33 to rotate synchronously, so that the outer side of the scraper closely fits the inner wall of the nozzle body 1 to perform mechanical movement, thereby removing solid contaminants such as solder paste and metal shavings. For the conical structure at the lower end of the nozzle body 1, the inclined scraper 34 at the lower end of the cleaning scraper 33 can penetrate into the conical surface gaps, effectively removing dead corners that are difficult to reach by traditional cleaning methods. At the same time, the water pump is connected to the annular pipe 61 through the connecting water pipe 63. During cleaning, water is delivered into the annular pipe 61. The water flows through the evenly spaced sections at the bottom of the annular pipe 61. The inclined cleaning pipe 62 sprays water, forming a 360° flushing path covering the inner wall of the nozzle body 1. The water flow and the scraper scrape work together to carry the detached impurities to the bottom of the nozzle, where they are intercepted and collected by the lower magnetic ring 14 and the filter screen 15 inside the suction head 7, which are magnetically fixed by the upper magnetic ring 13. This prevents impurities from entering the negative pressure hole and causing blockage. The nozzle cover 2 and the nozzle body 1 are detachably connected through the internal thread 5 and the threaded interface 4. When connected, the sealing gasket 10 at the bottom of the nozzle cover 2 fills the gap between the two to ensure that there is no liquid or gas leakage during the cleaning process. During maintenance, there is no need to disassemble the entire nozzle. You only need to unscrew the nozzle cover 2 to easily replace the scraper or take out the filter screen 15 for cleaning, which greatly reduces the wear of the nozzle caused by frequent disassembly.

[0034] From a technical performance perspective, this solution achieves breakthroughs in cleaning efficiency, ease of maintenance, and structural reliability: the combined cleaning mechanism of mechanical scraping and high-pressure rinsing can simultaneously handle the removal of solid contaminants and the flushing of liquid contaminants. Compared with the traditional single scraping method, the cleaning coverage is more comprehensive, especially effective in removing sticky substances such as cured solder paste and flux residue. The magnetic filter screen 15 design eliminates the traditional tool disassembly and assembly mode, enabling quick disassembly and installation by hand, reducing maintenance time by about 50% compared to the traditional method. The sealed structure ensures the cleaning stability during continuous operation of the production line. The conical suction head 7 at the bottom of the suction head body 1, combined with the adsorption sealing ring 9, can enhance the airtightness of the components during adsorption. With the negative pressure provided by the air pump through the threaded joint, the adsorption process is stable and reliable, effectively reducing the offset of the patch caused by poor sealing. The magnetic adsorption filter screen 15 structure inside the suction head 7 can form a physical barrier against large particles of impurities, further reducing the risk of blockage in the negative pressure channel.

[0035] In SMT production applications, this solution significantly improves placement quality and production efficiency: through a composite cleaning mechanism, the amount of contaminants remaining inside the nozzle can be controlled to an extremely low level, reducing the incidence of defects such as component misalignment and tombstoning. It is suitable for 01005 ultra-miniature components and high-density packaging scenarios. The modularly designed nozzle cover 2 can be quickly adapted to different specifications of nozzle body 1. By changing the scraper size or adjusting the angle of the cleaning tube 62, it is compatible with the cleaning needs of components with various packaging forms, improving the flexibility of the production line. The recyclable cleaning fluid and reusable filter 15 reduce the consumption of consumables such as alcohol and wiping paper, which is in line with the concept of green manufacturing. In addition, the magnetic adsorption filter structure and sealing design can effectively extend the service life of the nozzle and reduce equipment maintenance costs, providing reliable placement guarantee for fields with stringent cleanliness requirements such as semiconductor packaging and medical electronics.

[0036] The main structural components of this SMT pick-and-place machine nozzle anti-clogging device include: the nozzle body 1, made of aerospace-grade aluminum alloy (such as 6061-T6), with a hard anodized inner surface; the conical nozzle head 7, made of stainless steel (SUS316L), with an inner diameter of φ8-φ12mm and internal thread 5 specifications of M16×1.5-M20×1.5; the nozzle cover 2, made of POM engineering plastic; the bottom sealing gasket 10, made of fluororubber (FKM), with an outer diameter of φ25-φ35mm; and the mounting bracket 11, with countersunk holes of specifications M3-M4; the cleaning scraper 33, made of nylon PA66+glass fiber, with a thickness of 1.5-2mm; the angled scraper 34, with an angle of 45°±5° to the inner wall; and the drive motor 31, a DC micro stepper motor (such as TB6600, 24VDC, torque 0.5-1N・m); and the ring... The tube 61 and the cleaning drain pipe 62 are made of 304 stainless steel. The drain pipe has a diameter of φ1.5-2mm and an inclination angle of 30°-45°. The connecting water pipe 63 is a PU polyurethane flexible hose (inner diameter φ4-φ6mm). The adsorption sealing ring 9 is made of silicone (Shore hardness A50-60). The magnetic adsorption component is a neodymium iron boron permanent magnet (N35). The filter screen 15 is made of 316 stainless steel mesh (mesh size 200-300 mesh). Among the electronic components, the drive motor 31 is powered by a 24V DC power supply. The water pump (model such as the miniature magnetic drive pump MP-40R, 12VDC) is connected to an external water source through the water pump threaded connector 64. The air pump (model such as the miniature diaphragm pump VP-240, 24VDC) provides negative pressure through the air pump threaded connector 8. All components are powered and controlled by the chip mounter control system.

[0037] Of course, there may be other implementations of this utility model. Based on this implementation, other implementations obtained by those skilled in the art without any creative effort are all within the scope of protection of this utility model.

Claims

1. A nozzle anti-clogging device for an SMT pick-and-place machine, characterized in that, The device includes a suction nozzle body (1) and a suction nozzle cover (2). The upper part of the suction nozzle body (1) is provided with an internal thread (5). The bottom of the suction nozzle cover (2) is fixedly connected with a threaded interface (4). The suction nozzle cover (2) is threadedly installed on the top of the suction nozzle body (1) through the internal thread (5). A scraping mechanism (3) is fixedly installed in the middle of the suction nozzle cover (2). A cleaning mechanism (6) is fixedly connected inside the suction nozzle cover (2) on the outside of the scraping cover. The scraping and cleaning end of the scraping mechanism (3) is located inside the suction nozzle body (1) and is in close contact with the inner wall of the suction nozzle body (1). A suction head (7) is fixedly connected to the bottom of the suction nozzle body (1). An air pump threaded connector (8) is fixedly connected to the upper side of the suction nozzle cover (2). The cleaning mechanism (6) includes an annular tube (61), which is fixedly installed at the top inside the nozzle cover (2) and located outside the scraping mechanism (3). The bottom of the annular tube (61) is fixedly connected with a cleaning drain pipe (62) arranged in a ring at equal intervals. The output end of the cleaning drain pipe (62) is inclined towards the inner wall of the nozzle body (1). A connecting water pipe (63) is fixedly connected to the outside of the annular tube (61), and a water pump threaded connector (64) is fixedly connected to the outer end of the connecting water pipe (63).

2. The SMT pick-and-place machine nozzle anti-clogging device according to claim 1, characterized in that, The suction head (7) is generally conical in shape, narrow at the top and wide at the bottom, and an adsorption sealing ring (9) is fixedly connected to the bottom of the suction head (7).

3. The SMT pick-and-place machine nozzle anti-clogging device according to claim 1, characterized in that, A sealing gasket (10) is fixedly connected to the bottom of the nozzle cover (2), and the sealing gasket (10) seals the gap between the nozzle body (1) and the nozzle cover (2).

4. The SMT pick-and-place machine nozzle anti-clogging device according to claim 1, characterized in that, The scraping mechanism (3) includes a drive motor (31), which is fixedly installed in the middle of the top of the nozzle cover (2). The output end of the drive motor (31) passes through the nozzle cover (2) and is fixedly connected to a turntable (32). The turntable (32) is rotatably connected to the middle of the top inside the nozzle cover (2). Cleaning scrapers (33) are fixedly installed in a ring at equal intervals on the outer side of the turntable (32). The cleaning scrapers (33) are inserted into the nozzle body (1) and their outer side is in close contact with the inner wall of the nozzle body (1).

5. The SMT pick-and-place machine nozzle anti-clogging device according to claim 4, characterized in that, The lower end of the cleaning scraper (33) is fixedly equipped with an inclined scraper (34), and the lower end of the suction nozzle body (1) is conical. The outer side of the inclined scraper (34) and the inner conical surface of the suction nozzle body (1) are fitted together.

6. The SMT pick-and-place machine nozzle anti-clogging device according to claim 1, characterized in that, The top of the nozzle cover (2) is fixedly connected with a mounting bracket (11) arranged in a ring at equal intervals. The upper end of the mounting bracket (11) is provided with a mounting hole (12), which is a countersunk hole.

7. The SMT pick-and-place machine nozzle anti-clogging device according to claim 1, characterized in that, An upper magnetic ring (13) is fixedly installed at the bottom of the suction head (7). A lower magnetic ring (14) is magnetically attracted to the suction head (7) through the upper magnetic ring (13). A filter screen (15) is fixedly connected to the bottom of the lower magnetic ring (14).

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