Photovoltaic power cable quick waterproof sealing connection structure

Abstract

The application provides a photovoltaic power cable rapid waterproof sealing connection structure and relates to the field of cable connection. The photovoltaic power cable rapid waterproof sealing connection structure comprises a supporting cylinder, two telescopic cylinders are slidably arranged in the supporting cylinder, a cutting assembly is arranged on the side wall of the telescopic cylinder, and a stretching assembly is arranged between the supporting cylinder and the two telescopic cylinders. Cable bodies are arranged in the telescopic cylinder and the cutting assembly on the same side. The cutting assembly comprises a disc one, a disc two, a straight sliding groove, an arc-shaped guide groove, a cutting knife and a guide rod, the end, away from the supporting cylinder, of the telescopic cylinder is fixedly connected with the disc one, the insulating layer is removed through the cutting assembly, the conductor is precisely butt-jointed through the stretching assembly, the sealing sleeve and the conical block are used for compressing the insulating layer, and the external adhesive tape is used for reinforcing sealing, so that the problems of conductor damage, complicated steps and poor sealing in traditional butt-joint stripping are solved, and efficient, precise and waterproof butt-joint of the cable is realized.

Description

Technical Field

[0001] This invention relates to the field of cable connection technology, specifically to a rapid waterproof and sealing connection structure for photovoltaic power cables. Background Technology

[0002] With social development, the photovoltaic industry has become an important part of the clean energy sector. Photovoltaic power cables, as the key carriers for transmitting electrical energy in photovoltaic systems, are responsible for delivering the electrical energy generated by photovoltaic modules to equipment such as inverters and combiner boxes. Cable connections are used for various purposes, including cable extension during photovoltaic module array expansion, joint connection after replacing old cables, and cable reconnection after system maintenance. Cable connections not only ensure smooth current transmission and reduce line losses, but also withstand the effects of harsh outdoor environments such as rain, wind, sand, and high and low temperatures. They also prevent safety accidents such as short circuits and leakage caused by loose joints, water ingress, or insulation failure, thus ensuring the long-term reliable operation of photovoltaic systems.

[0003] However, existing photovoltaic power cable splicing methods have significant drawbacks. Traditional splicing processes first require operators to manually strip the insulation layer from the cable ends using wire strippers. This stripping process relies heavily on manual experience, and improper force control can easily damage the internal conductors. After stripping, the conductors of the two cables must be wrapped or crimped together for fixation, followed by manually wrapping multiple layers of insulating tape for insulation sealing. Finally, waterproof tape may be needed to enhance waterproofing. The entire process is cumbersome and time-consuming. Especially in large-scale photovoltaic power plant construction, splicing numerous cables consumes substantial manpower and time costs. Traditional splicing methods lack standardized structures, and the splicing quality is greatly affected by the operator's skill level, making it difficult to guarantee the consistency and reliability of batch splicing. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a rapid waterproof and sealing connection structure for photovoltaic power cables, which solves the problems of existing cable splicing requiring manual stripping that easily damages the conductor, cumbersome steps with low efficiency, poor insulation, waterproofing and sealing, and unstable quality.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a rapid waterproof sealing connection structure for photovoltaic power cables, comprising a support cylinder, two telescopic cylinders slidably installed inside the support cylinder, a cutting component installed on the side wall of the telescopic cylinder, and a tensioning component installed between the support cylinder and the two telescopic cylinders.

[0006] The cable body is installed inside the telescopic cylinder and the cutting assembly on the same side.

[0007] The cutting assembly includes a first disc, a second disc, a straight groove, an arc-shaped guide groove, a cutting blade, and a guide rod. The first disc is fixedly connected to the end of the telescopic cylinder away from the support cylinder. The second disc is movably installed at the end of the first disc away from the telescopic cylinder. Multiple straight grooves are formed on the side of the first disc near the second disc. Multiple arc-shaped guide grooves are formed on the side of the straight grooves near the first disc. The cutting blade is slidably installed inside the straight groove. A guide rod is fixedly connected to the outer wall of the cutting blade. The guide rod is slidably installed inside the arc-shaped guide groove at the corresponding position.

[0008] The tensioning assembly includes a protective cylinder, a lifting block, a lead screw, a connecting rod, and a cross groove. The protective cylinder is fixedly connected to the top of the support cylinder. The lifting block is slidably installed inside the protective cylinder. The lead screw is rotatably installed inside the protective cylinder. The lead screw is threaded through the lifting block. Both ends of the lifting block pass through the protective cylinder and are movably installed with connecting rods. The end of the connecting rod away from the lifting block is movably installed on the side wall of the disc.

[0009] Preferably, the cable body includes an insulation layer and a conductor, the conductor being located inside the insulation layer, and two opposite faces of the conductors being bonded together.

[0010] Preferably, a protective sleeve is fixedly connected to one end of the second disc, and a conical block is fixedly connected to the end of the protective sleeve away from the second disc. A sealing sleeve is threaded onto the outer wall of the protective sleeve.

[0011] Preferably, the conical block has multiple slots inside, and the inner wall of the sealing sleeve has an inner conical groove that fits into the conical block.

[0012] Preferably, the outer wall of the first disc is provided with an annular movable groove, the outer wall of the second disc is fixedly connected with a toggle ring, the inner wall of the toggle ring is fixedly connected with an annular movable block, and the annular movable block is movably installed inside the annular movable groove.

[0013] Preferably, the outer wall of the telescopic cylinder is provided with multiple sliding grooves, and multiple sliders are fixedly connected to both ends of the inner wall of the support cylinder, with the sliders slidably installed inside the sliding grooves.

[0014] Preferably, the top of the lead screw extends through the top of the protective cylinder, and a cross groove is formed on the top of the lead screw.

[0015] Preferably, both the sealing sleeve and the actuating ring have anti-slip textures on their outer walls.

[0016] This invention provides a rapid waterproof sealing connection structure for photovoltaic power cables. It offers the following advantages:

[0017] 1. By setting up the cutting component, during use, rotating the second disc causes the annular movable block to rotate along the annular movable groove of the first disc, driving the guide rod to slide along the arc-shaped guide groove, which in turn pushes the cutting blade to move radially along the straight slide groove, so that the cutting blade accurately inserts into the cable insulation layer until it contacts the conductor. Continuing to rotate the second disc allows the cutting blade to cut the insulation layer through its circumferential motion, achieving the function of quickly cutting the insulation layer. This solves the problems of easy damage to the conductor and low stripping efficiency in existing technologies when manually stripping wires. It does not rely on manual experience, and the cutting depth and range are precisely controllable. It can avoid damaging the conductor and quickly complete the stripping operation, improving the efficiency of cable splicing preparation.

[0018] 2. By setting up a tensioning component, a Phillips screwdriver is inserted into the Phillips groove to rotate the lead screw. The lead screw engages with the threaded engagement of the lifting block, causing the lifting block to slide along the protective cylinder. The lifting block, through the connecting rod, pulls the two discs on both sides to move in opposite directions. With the guidance of the sliding groove on the outer wall of the telescopic cylinder and the slider on the inner wall of the support cylinder, the two telescopic cylinders move smoothly closer along the support cylinder, ultimately driving the conductors of the two cables to accurately connect and fit together. This achieves the function of bringing the two cables closer together and completing the conductor connection, solving the problems of easy misalignment and uneven connection force in manual conductor connection in the existing technology. The conductor connection position is accurate and the fit is tight, reducing contact resistance. At the same time, there is no need to manually support the cables, reducing the difficulty of operation and improving the connection efficiency and quality stability.

[0019] 3. By setting up a sealing sleeve, a protective sleeve, a conical block, a slot, and an inner conical groove, when the sealing sleeve is rotated, the inner conical groove on its inner wall squeezes the conical block. Because the conical block has a slot and a contraction space, the conical block will contract inward and press the cable insulation layer, thus achieving a tight fixation and initial sealing effect on the cable insulation layer. Combined with the subsequent wrapping of external insulating tape, it solves the problem of easy water ingress and aging in the existing technology. The mechanical pressing structure of the conical block and the sealing sleeve can maintain pressure on the insulation layer for a long time, improve the waterproof sealing and structural stability of the joint, and extend the service life of the joint. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the photovoltaic power cable rapid waterproof sealing connection structure proposed in this invention;

[0021] Figure 2 This is a cross-sectional schematic diagram of the rapid waterproof sealing connection structure for photovoltaic power cables proposed in this invention.

[0022] Figure 3 This is a schematic diagram of the structure of the photovoltaic power cable quick waterproof sealing connection structure proposed in this invention during cable connection;

[0023] Figure 4 for Figure 3 Enlarged structural diagram at point A in the middle;

[0024] Figure 5 for Figure 3 Enlarged structural diagram at point B;

[0025] Figure 6 This is an exploded structural diagram of the photovoltaic power cable rapid waterproof sealing connection structure proposed in this invention;

[0026] Figure 7 This is a cross-sectional structural diagram of the cutting component in the rapid waterproof sealing connection structure for photovoltaic power cables proposed in this invention;

[0027] Figure 8 for Figure 7 Enlarged structural diagram at point C;

[0028] Figure 9 This is an enlarged structural diagram of the cutting component in the rapid waterproof sealing connection structure for photovoltaic power cables proposed in this invention;

[0029] Figure 10 This is an enlarged structural schematic diagram of the disk one in the rapid waterproof sealing connection structure for photovoltaic power cables proposed in this invention;

[0030] Figure 11 This is an enlarged structural schematic diagram of the second disk in the rapid waterproof sealing connection structure for photovoltaic power cables proposed in this invention;

[0031] Figure 12 This is an enlarged structural diagram of the support cylinder in the rapid waterproof sealing connection structure for photovoltaic power cables proposed in this invention.

[0032] Among them, 1. Support cylinder; 101. Slider; 2. Telescopic cylinder; 201. Slide groove; 3. Cutting assembly; 301. Disc one; 302. Disc two; 303. Straight slide groove; 304. Arc guide groove; 305. Cutting blade; 306. Guide rod; 307. Annular movable groove; 308. Annular movable block; 4. Sealing sleeve; 5. Tensioning assembly; 501. Protective cylinder; 502. Lifting block; 503. Lead screw; 504. Connecting rod; 505. Cross groove; 6. Insulation layer; 7. Conductor; 8. Protective sleeve; 9. Conical block; 10. Slot; 11. Inner conical groove. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Example 1:

[0035] like Figure 1-12 As shown, this embodiment of the invention provides a rapid waterproof sealing connection structure for photovoltaic power cables, including a support cylinder 1. The support cylinder 1 provides the core support frame for the entire connection structure. Its hollow internal structure provides space for the sliding of telescopic cylinders 2. Two telescopic cylinders 2 are slidably installed inside the support cylinder 1. The telescopic cylinders 2 are used to accommodate and fix the cables and can slide along the axial direction of the support cylinder 1 to move the cables closer and further away. A cutting component 3 is installed on the side wall of the telescopic cylinder 2. The cutting component 3 is used to automatically cut the insulation layer 6 of the cable, replacing manual stripping. A tensioning component 5 is installed between the support cylinder 1 and the two telescopic cylinders 2. The tensioning component 5 provides power for the opposite movement of the two telescopic cylinders 2 to achieve precise docking of the conductors 7 of the two cables. The tensioning component 5 is installed between the support cylinder 1 and the two telescopic cylinders 2.

[0036] The cable body is installed inside the telescopic cylinder 2 and the cutting component 3 on the same side. The telescopic cylinder 2 and the cutting component 3 work together to position, strip and fix the cable, ensuring that the cable is stable during the docking process. The cable body is installed inside the telescopic cylinder 2 and the cutting component 3 on the same side.

[0037] The cutting assembly 3 includes a first disc 301, a second disc 302, a straight groove 303, an arc-shaped guide groove 304, a cutting blade 305, and a guide rod 306. The first disc 301 is fixedly connected to the end of the telescopic cylinder 2 furthest from the support cylinder 1. The first disc 301 provides a fixed mounting base for the cutting assembly 3, and its fixed connection with the telescopic cylinder 2 ensures structural stability during cutting. The second disc 302 is movably mounted to the end of the first disc 301 furthest from the telescopic cylinder 2. The second disc 302 can rotate relative to the first disc 301, driving the cutting blade 305 through rotation. Multiple straight grooves 303 are provided on the side of the first disc 301 closest to the second disc 302. These straight grooves 303 provide radial sliding guidance for the cutting blade 305, restricting its movement to the radius of the first disc 301, ensuring controllable cutting depth. Multiple arc-shaped guides are provided on the side of the straight grooves 303 closest to the first disc 301. The arc-shaped guide groove 304 converts the rotational motion of the second disk 302 into the radial movement of the cutting blade 305 through the guide rod 306. Its arc-shaped trajectory design determines the moving speed and range of the cutting blade 305. The cutting blade 305 is slidably installed inside the straight slide groove 303. The cutting blade 305 is the execution component for cutting the insulation layer 6. Its blade sharpness and length are adapted to the thickness of the photovoltaic cable insulation layer 6, which can accurately cut the insulation layer 6 without damaging the conductor 7. The guide rod 306 is fixedly connected to the outer wall of the cutting blade 305. The guide rod 306 is embedded in both the arc-shaped guide groove 304 and the cutting blade 305, which plays the role of transmitting the rotational power of the second disk 302 to the cutting blade 305. The guide rod 306 is slidably installed inside the arc-shaped guide groove 304 at the corresponding position. When the guide rod 306 slides along the arc-shaped guide groove 304, it pushes the cutting blade 305 to move along the straight slide groove 303 to realize the cutting action.

[0038] The tensioning assembly 5 includes a protective cylinder 501, a lifting block 502, a lead screw 503, a connecting rod 504, and a cross groove 505. The protective cylinder 501 is fixedly connected to the top of the support cylinder 1. The protective cylinder 501 provides protection and installation space for the internal components of the tensioning assembly 5, preventing external impurities from affecting the movement of the components. The lifting block 502 is slidably installed inside the protective cylinder 501. The lifting block 502 drives the connecting rod 504 to move by sliding, thereby pulling the disc 301 to move. The lead screw 503 is rotatably installed inside the protective cylinder 501. The lead screw 503 is threadedly engaged with the lifting block 502, converting the rotational motion into rotational motion. The linear motion of the lifting block 502 is ensured by the precision of its thread, which guarantees smooth movement and controllable position. The screw 503 is threaded through the lifting block 502. Both ends of the lifting block 502 pass through the protective cylinder 501 and are movably mounted with connecting rods 504. The connecting rods 504 are the power transmission components between the lifting block 502 and the disc 301. Their movable connection design can adapt to the angle changes when the disc 301 moves, avoiding motion interference. The end of the connecting rod 504 away from the lifting block 502 is movably mounted on the side wall of the disc 301, ensuring that the sliding of the lifting block 502 can effectively drive the disc 301 to move.

[0039] The cable body includes an insulation layer 6 and a conductor 7. The conductor 7 is located inside the insulation layer 6. The insulation layer 6 provides insulation protection to prevent leakage of the conductor 7. The conductor 7 is the core component for power transmission. Its material and cross-sectional area are adapted to the current requirements of the photovoltaic system. The two conductors 7 are connected face to face to ensure smooth current transmission and reduce contact resistance.

[0040] A protective sleeve 8 is fixedly connected to one end of the disc 2 302. The protective sleeve 8 is used to guide the cable insertion and also plays a preliminary positioning role for the cable to prevent the cable from shifting during the cutting process. A conical block 9 is fixedly connected to the end of the protective sleeve 8 away from the disc 2 302. The conical block 9 has elastic contraction capability and can compress the cable insulation layer 6 under the pressure of the sealing sleeve 4 to achieve fixation and sealing. The sealing sleeve 4 is installed on the outer wall of the protective sleeve 8. The sealing sleeve 4 achieves axial movement through the rotation of the thread, thereby compressing the conical block 9.

[0041] The conical block 9 has multiple slots 10 inside, which provide space for the conical block 9 to contract, allowing it to deform inward when squeezed by the inner conical groove 11, thus tightly fitting the cable insulation layer 6. The inner wall of the sealing sleeve 4 has an inner conical groove 11, the conical angle of which is adapted to the conical block 9. The conical block 9 contracts evenly through the inclined surface compression, and the inner conical groove 11 fits into the conical block 9. This ensures that the squeezing force of the sealing sleeve 4 can be evenly transmitted to the conical block 9, improving the sealing effect.

[0042] The outer wall of disc 301 is provided with an annular movable groove 307. The annular movable groove 307 provides rotation guidance and limit for the annular movable block 308, ensuring that disc 302 can rotate smoothly relative to disc 301 and avoid deviation. A toggle ring is fixedly connected to the outer wall of disc 302. The toggle ring facilitates the operator to rotate disc 302. The anti-slip texture on its outer wall increases the friction of the hand and prevents slippage during rotation. An annular movable block 308 is fixedly connected to the inner wall of the toggle ring. The annular movable block 308 is embedded in the annular movable groove 307 to realize the movable connection between disc 301 and disc 302, and at the same time transmit rotational power. The annular movable block 308 is movably installed inside the annular movable groove 307.

[0043] Multiple sliding grooves 201 are provided on the outer wall of the telescopic cylinder 2. The sliding grooves 201 cooperate with the sliders 101 to restrict the telescopic cylinder 2 to slide only along the axial direction of the support cylinder 1, ensuring that the telescopic cylinder 2 does not rotate circumferentially when it moves. Multiple sliders 101 are fixedly connected to both ends of the inner wall of the support cylinder 1. The sliders 101 provide guidance for the sliding of the telescopic cylinder 2. The clearance fit between the sliders 101 and the sliding grooves 201 ensures smooth sliding. The sliders 101 are slidably installed inside the sliding grooves 201.

[0044] The top of the lead screw 503 passes through the top of the protective cylinder 501, making it easy for operators to rotate the lead screw 503 with tools. The top of the lead screw 503 has a cross groove 505, which is compatible with a standard Phillips screwdriver, making it easy for operators to rotate the lead screw 503 with tools and reducing the difficulty of operation.

[0045] Both the sealing sleeve 4 and the actuating ring have anti-slip textures on their outer walls. These textures increase the friction between the operator's hand and the parts, preventing the hand from slipping when rotating the sealing sleeve 4 or the actuating ring, thus improving ease of operation.

[0046] Working principle: First, insert the two photovoltaic cables to be connected into the protective sleeves 8 on both sides, pass through the second disc 302 and the first disc 301 in sequence, and finally insert them into the telescopic cylinder 2 until the end conductor 7 of the cable approaches the end of the telescopic cylinder 2 near the support cylinder 1, thus completing the cable positioning.

[0047] Then, hold the actuating ring on the outer wall of the second disc 302 and rotate it clockwise. The annular movable block 308 rotates along the annular movable groove 307 of the first disc 301, driving the guide rod 306 to slide along the arc-shaped guide groove 304, pushing the cutting blade 305 to move along the straight slide groove 303 towards the center of the cable, and the blade inserts into the insulation layer 6. Continue rotating until the cutting blade 305 contacts the conductor 7. Determine whether it has contacted the conductor 7 by the change in resistance. Rotate a few more times to cut the circumference of the insulation layer 6. Then rotate the second disc 302 counterclockwise, retract the cutting blade 305, pull out the cable and remove the cut insulation layer 6.

[0048] Next, reinsert the stripped cable, exposing conductor 7 to the appropriate length. Hold the anti-slip groove of the sealing sleeve 4 and rotate it clockwise. The sealing sleeve 4 moves along the protective sleeve 8 towards the conical block 9. The inner conical groove 11 squeezes the conical block 9. Because the slot 10 provides space for contraction, the conical block 9 contracts inward and fits tightly against the insulation layer 6, thus fixing the cable and providing initial waterproofing.

[0049] Then, insert a Phillips screwdriver into the Phillips groove 505 of the lead screw 503 and rotate it clockwise. The lead screw 503 drives the lifting block 502 to slide upward along the protective cylinder 501. The lifting block 502 pulls the two discs 301 to move towards each other through the connecting rod 504. The telescopic cylinder 2 slides along the support cylinder 1 with the disc 301 until the conductors 7 of the two cables are tightly attached, completing the docking.

[0050] Finally, insulating tape is wrapped around the outside of the entire connection structure, covering the support cylinder 1, the sealing sleeve 4, and the transition area at the cable end, to further improve insulation and waterproofing, and ensure long-term stable operation of the joint.

[0051] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. Photovoltaic power cable quick waterproof sealing connection structure, comprising a support cylinder (1), characterized in that: The inside of the support cylinder (1) is slidably installed with two telescopic cylinders (2), the side wall of the telescopic cylinder (2) is installed with a cutting assembly (3), and the support cylinder (1) and the two telescopic cylinders (2) are installed with a stretching assembly (5); The telescopic cylinder (2) and the cutting assembly (3) are installed with a cable body inside the same side; The cutting assembly (3) comprises a disc one (301), a disc two (302), a straight chute (303), an arc-shaped guide groove (304), a cutting knife (305) and a guide rod (306), one end of the telescopic cylinder (2) away from the support cylinder (1) is fixedly connected with the disc one (301), one end of the disc one (301) away from the telescopic cylinder (2) is movably installed with the disc two (302), a plurality of straight chutes (303) are formed in the side of the disc one (301) close to the disc two (302), a plurality of arc-shaped guide grooves (304) are formed in the side of the straight chute (303) close to the disc one (301), the cutting knife (305) is slidably installed in the inside of the straight chute (303), the guide rod (306) is fixedly connected to the outer wall of the cutting knife (305), and the guide rod (306) is slidably installed in the inside of the arc-shaped guide groove (304) at the corresponding position. The stretching assembly (5) comprises a protection cylinder (501), a lifting block (502), a lead screw (503), a connecting rod (504) and a cross groove (505), the protection cylinder (501) is fixedly connected to the top of the support cylinder (1), the lifting block (502) is slidably installed in the inside of the protection cylinder (501), the lead screw (503) is rotatably installed in the inside of the protection cylinder (501), the lead screw (503) is threaded through the lifting block (502), the connecting rod (504) is movably installed at one end of the lifting block (502) away from the protection cylinder (501), and the other end of the connecting rod (504) is movably installed in the side wall of the disc one (301).

2. The photovoltaic power cable quick waterproof sealing connection structure according to claim 1, characterized in that: The cable body comprises an insulating layer (6) and a conductor (7), the conductor (7) is located in the inside of the insulating layer (6), and the opposite surfaces of the two conductors (7) are abutted together.

3. The photovoltaic power cable quick waterproof sealing connection structure according to claim 1, characterized in that: One end of the disc two (302) is fixedly connected with a protection sleeve (8), one end of the protection sleeve (8) away from the disc two (302) is fixedly connected with a tapered block (9), and the outer wall of the protection sleeve (8) is threadedly installed with a sealing sleeve (4).

4. The photovoltaic power cable quick waterproof sealing connection structure according to claim 3, characterized in that: A plurality of grooves (10) are formed in the inside of the tapered block (9), an inner tapered groove (11) is formed in the inner wall of the sealing sleeve (4), and the inner tapered groove (11) is abutted with the tapered block (9).

5. The photovoltaic power cable quick waterproof sealing connection structure according to claim 4, characterized in that: An annular movable groove (307) is formed in the outer wall of the disc one (301), a knob ring is fixedly connected to the outer wall of the disc two (302), an annular movable block (308) is fixedly connected to the inner wall of the knob ring, and the annular movable block (308) is movably installed in the inside of the annular movable groove (307).

6. The photovoltaic power cable quick waterproof sealing connection structure according to claim 1, characterized in that: The outer wall of the telescopic cylinder (2) is provided with a plurality of sliding grooves (201), the inner wall of the supporting cylinder (1) is fixedly connected with a plurality of sliding blocks (101) at both ends, and the sliding blocks (101) are slidingly installed in the sliding grooves (201).

7. The photovoltaic power cable quick waterproof sealing connection structure according to claim 1, characterized in that: The top of the lead screw (503) penetrates the top of the protection cylinder (501), and the top of the lead screw (503) is provided with a cross groove (505).

8. The photovoltaic power cable quick waterproof sealing connection structure according to claim 5, characterized in that: The sealing sleeve (4) and the outer wall of the rotating ring are both provided with anti-skid lines.

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