An optical fiber automatic rotating clamp

Abstract

This utility model relates to a clamp, specifically an automatic optical fiber rotating clamp, aiming to solve the problem that existing optical fiber rotating clamps cannot simultaneously meet the requirements of automated production lines and free rotation from 0 to 360°. This utility model includes a base plate, a photoelectric sensor mounted on the base plate, a motor, a gear set, a gear mounting base, a clamp mounting shaft, and an optical fiber holder. The optical fiber holder is used to clamp the optical fiber. The gear mounting base has a first U-shaped notch with an upward opening. The gear set includes a fourth gear coaxially connected to the second output shaft of the motor, a second gear and a third gear meshing with the fourth gear, and a first gear meshing with the second gear and / or the third gear. This utility model allows the first gear to rotate freely at any angle between 0 and 360° without power interruption. This design allows the optical fiber to be normally placed and fixed in the optical fiber placement slot from top to bottom, while also eliminating requirements on the initial placement posture of the optical fiber.

Description

Technical Field

[0001] This utility model relates to a clamp, specifically an automatic optical fiber rotating clamp. Background Technology

[0002] Optical fiber is a type of fiber made of glass or plastic, typically cylindrical, used as a means of light transmission. Some optical fibers have a beveled end with an angle of 42° or 45° between the bevel and the fiber's cross-section. During processing, these fibers usually need to be clamped and rotated to a suitable angle, for example, so that the beveled end faces upwards, to meet subsequent processing requirements.

[0003] To address the aforementioned needs, some manual fiber optic rotation clamps have emerged on the market, but they cannot meet the requirements of automated production lines. To solve the problem of adapting to automated production lines, Shenyang Donglai Optoelectronic Technology Co., Ltd. developed an automatic rotating fiber optic clamp (model: FS266N). However, its maximum fiber rotation angle is only 260°, meaning that some fibers cannot ultimately rotate to the appropriate angle during use, limiting its applicability.

[0004] Furthermore, Chinese invention patent CN115327694A discloses a clamping device for laser direct writing of multi-core fiber Bragg gratings. This device includes a fixed frame, a rotating mechanism, and a placement stage. The fixed frame includes a fixed plate, two end plates, and two support platforms. An end plate is disposed at each end of the fixed plate, and the surface of the end plate is perpendicular to the surface of the fixed plate. The two support platforms are located within the placement space, with one end fixed to the fixed plate. The side of the fixed plate facing away from the placement space is mounted on a three-dimensional motion mechanism. The two ends of the placement stage are respectively disposed on the two support platforms. The multi-core fiber is placed at the slit position of the placement stage, and its extension direction is parallel to the length direction of the placement stage. A rotating mechanism is disposed on the side of each end plate near the placement space. The rotating mechanism clamps both ends of the multi-core fiber and can drive the multi-core fiber to rotate along its own axis. However, this clamping device also cannot meet the needs of automated production lines.

[0005] In summary, existing fiber optic rotary fixtures cannot simultaneously meet the requirements of automated production lines and 0–360° free rotation. Utility Model Content

[0006] The purpose of this invention is to solve the problem that existing fiber optic rotary clamps cannot simultaneously meet the needs of automated production lines and 0-360° free rotation, and to provide an automatic fiber optic rotary clamp.

[0007] To achieve the above objectives, the technical solution provided by this utility model is as follows:

[0008] An automatic optical fiber rotation clamp is used to clamp and rotate an optical fiber, wherein the output end of the optical fiber is provided with an inclined surface. Its special feature is that:

[0009] The device includes a base plate, a photoelectric sensor mounted on the base plate, a motor, a gear mounting base, a gear set, a clamp mounting shaft, and an optical fiber holder, wherein the optical fiber holder is used to clamp optical fibers; the gear mounting base has a first U-shaped notch with the opening facing upward.

[0010] The motor is provided with a first output shaft and a second output shaft at its two ends respectively;

[0011] The gear set includes a fourth gear coaxially connected to the second output shaft of the motor, a second gear and a third gear meshing with the fourth gear, and a first gear meshing with the second gear and / or the third gear; the fourth gear, the third gear, and the second gear are respectively mounted on one side of the gear mounting base; the clamp mounting shaft is rotatably inserted into the first U-shaped notch, with one end located on one side of the gear mounting base and coaxially connected to the first gear, and the other end located on the other side of the gear mounting base and connected to the optical fiber clamp; the first gear has a second U-shaped notch for the optical fiber to pass through;

[0012] The end of the first output shaft of the motor is provided with a photoelectric sensing plate that cooperates with the photoelectric sensor to determine the initial position of the first gear. The initial position is defined as the position when the second U-shaped notch opening faces upward and the photoelectric sensor detects the photoelectric sensing plate.

[0013] The output power of the motor is transmitted to the first gear in sequence through the fourth gear, the second gear and / or the third gear, which drives the fixture mounting shaft and the fiber optic clamp to rotate, thereby driving the fiber optic to rotate.

[0014] The fixture mounting shaft and the fiber optic clamping seat are respectively provided with fiber optic placement slots for placing fiber optics along the axial direction. M sets of fiber optic clamping components are sequentially arranged along the axial direction on the fiber optic placement slots of the fiber optic clamping seat, where M is an integer greater than or equal to 1.

[0015] Both the photoelectric sensor and the motor are electrically connected to an external control module.

[0016] Furthermore, the motor is mounted on the base plate via a motor mounting plate, which is arranged parallel to the gear mounting base plate;

[0017] The input end of the fourth gear is provided with a transition shaft, and the transition shaft is connected to the second output shaft of the motor.

[0018] The fourth gear is fixedly connected to the inner ring of the fourth bearing via the fourth shaft, the third gear is fixedly connected to the inner ring of the third bearing via the third shaft, and the second gear is fixedly connected to the inner ring of the second bearing via the second shaft; the outer rings of the second bearing, the third bearing, and the fourth bearing are all fixedly connected to the gear mounting base plate.

[0019] The fixture mounting shaft is in rolling connection with the outer rings of four first bearings mounted on the gear mounting base plate on its outer periphery; the inner rings of the four first bearings are fixedly connected to the gear mounting base plate.

[0020] Furthermore, the fiber clamping assembly includes a fiber clamping strip disposed above the fiber placement groove of the fiber clamping seat and extending perpendicular to the fiber placement groove, a pull screw disposed on the upper surface of one end of the fiber clamping strip, a fiber clamping strip mounting ear disposed on the fiber clamping seat and connected to the other end of the fiber clamping strip via a rotating shaft, and a magnet embedded in the fiber clamping seat for adsorbing the fiber clamping strip.

[0021] Furthermore, it also includes a protective shield;

[0022] The protective cover is connected to the base plate and is located on the side of the gear mounting substrate away from the fiber optic clamp. The first gear, the second gear, the third gear, the fourth gear, the second shaft, the third shaft, the fourth shaft, and the transition shaft are all located within the space enclosed by the protective cover, the base plate, and the gear mounting substrate. The protective cover has a third U-shaped notch for the fiber optic cable to pass through.

[0023] Furthermore, the first gear and the fourth gear have the same number of teeth; the second gear and the third gear have the same number of teeth.

[0024] Furthermore, the first gear and the fourth gear each have 32 teeth; the second gear and the third gear each have 16 teeth.

[0025] Furthermore, a reinforcing plate is provided on the side wall of the gear mounting base near the optical fiber holder, and a bearing cover plate is provided on the side wall away from the optical fiber holder.

[0026] Furthermore, M = 2;

[0027] The second output shaft and the transition shaft of the motor are connected by a coupling.

[0028] Furthermore, both the second and third shafts have shaft end caps at the ends furthest from the gear mounting base.

[0029] Furthermore, it also includes a first limiting plate and a second limiting plate;

[0030] A cylinder is provided on the side of the first gear near the gear mounting base plate;

[0031] One end of the fixture mounting shaft passes through the cylinder and the first gear in sequence and is connected to the second limiting plate, and is fixedly connected to the cylinder and the first gear;

[0032] The other end of the fixture mounting shaft is connected to the fiber optic clamping seat via a first limiting plate.

[0033] Four spring plungers are provided on the side of the gear mounting base near the first gear, which abut against the end face of the cylinder near the gear mounting base.

[0034] The first limiting plate, the second limiting plate, and the cylinder are all provided with U-shaped limiting notches corresponding to the first U-shaped notch and the second U-shaped notch.

[0035] Compared with the prior art, the beneficial effects of this utility model are:

[0036] 1. The automatic optical fiber rotating fixture provided by this utility model, by setting a second gear and a third gear, allows the first gear with a second U-shaped notch to rotate freely at any angle between 0 and 360° without power interruption. This setting allows the optical fiber to be normally placed into the optical fiber placement slot from top to bottom and fixed (without damaging the inclined surface of the optical fiber output end), and there are no requirements for the initial placement posture of the optical fiber. Regardless of the initial placement posture of the optical fiber, it can be rotated to a suitable angle by the gear set driven by the motor to meet the subsequent processing requirements, making the operation simple.

[0037] 2. The fiber optic automatic rotating fixture provided by this utility model has its motor and photoelectric sensor electrically connected to a common external control module, which makes the rotation of the fiber optic cable and the reset (i.e., restoration to the initial state) of the gear set driven by the motor fully automated, without the need for manual monitoring or intervention.

[0038] 3. The fiber optic automatic rotating clamp provided by this utility model is equipped with a protective cover, which can maximize the protection of components such as gears from the influence of dust in the air and improve the working stability of the clamp.

[0039] 4. The automatic optical fiber rotating clamp provided by this utility model, with its photoelectric sensor and photoelectric sensor plate, can ensure that the automatic optical fiber rotating clamp is in its initial state before each optical fiber is inserted, without the need for manual adjustment of the gears to return to their original positions. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the structure of an embodiment of the fiber optic automatic rotating clamp of this utility model. Figure 1 ;

[0041] Figure 2 This is a schematic diagram of the structure of an embodiment of the fiber optic automatic rotating clamp of this utility model. Figure 2 ;

[0042] Figure 3 This is a schematic diagram of the structure of an embodiment of the fiber optic automatic rotating clamp of this utility model. Figure 3 ;

[0043] Figure 4 This is a schematic diagram of the structure of an embodiment of the fiber optic automatic rotating clamp of this utility model. Figure 4 ;

[0044] Figure 5 This is a schematic diagram of the structure of an embodiment of the fiber optic automatic rotating clamp of this utility model. Figure 5 (Protective cover not shown);

[0045] Figure 6 This is a schematic diagram of the structure of an embodiment of the fiber optic automatic rotating clamp of this utility model. Figure 6 (Protective cover not shown);

[0046] Figure 7 for Figure 5 X-direction view;

[0047] Figure 8 for Figure 5 Y-direction view;

[0048] Explanation of reference numerals in the attached figures:

[0049] 01-Fiber optic cable; 1-Base plate; 2-Protective cover; 3-Gear mounting base plate; 4-Motor mounting plate; 51-Photoelectric sensor; 52-Photoelectric sensor sheet; 6-Motor; 7-Coupling; 8-Clamp mounting shaft; 9-Fiber optic clamp holder; 901-Fiber optic strip mounting ear; 902-Fiber optic strip; 903-Hand screw; 101-Bearing cover plate; 102-Reinforcing plate; 11-Shaft end cover; G1-First gear; G2-Second gear; G3-Third gear; G4-Fourth gear; B1-First bearing; B2-Second bearing; B3-Third bearing; B4-Fourth bearing; 601-First output shaft of motor; 602-Second output shaft of motor; S2-Second shaft; S3-Third shaft; S4-Fourth shaft; S7-Transition shaft. Detailed Implementation

[0050] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0051] An automatic optical fiber rotating clamp, see Figures 1 to 8 It is used to clamp and rotate optical fiber 01. The output end of optical fiber 01 is provided with an inclined surface.

[0052] The device includes a base plate 1, a photoelectric sensor 51 mounted on the base plate 1, a gear mounting base 3 and a motor mounting plate 4 mounted parallel to the base plate 1, a motor 6 mounted on the motor mounting plate 4, a gear set connected to the gear mounting base 3, a clamping mounting shaft 8 connected to the gear set, an optical fiber clamping seat 9 mounted on the clamping mounting shaft 8, a protective cover 2, a first limiting plate and a second limiting plate. The optical fiber clamping seat 9 is used to clamp the optical fiber 01. The gear mounting base 3 has a first U-shaped notch with an upward opening.

[0053] The motor 6 has a first output shaft 601 and a second output shaft 602 at its two ends. The end of the first output shaft 601 is provided with a photoelectric sensor 52 that cooperates with the photoelectric sensor 51. The photoelectric sensor 51 and the photoelectric sensor 52 are used together to determine the initial position of the first gear G1. The initial position is defined as the position when the second U-shaped notch of the first gear G1 is vertically upward, the second U-shaped notch is aligned with the first U-shaped notch, and the photoelectric sensor 51 detects the photoelectric sensor 52. The input end of the fourth gear G4 is provided with a transition shaft S7, and the transition shaft S7 is connected to the second output shaft 602 through a coupling 7.

[0054] The gear set includes a fourth gear G4 coaxially connected to the second output shaft 602 of the motor, a second gear G2 and a third gear G3 meshing with the fourth gear G4, and a first gear G1 meshing with the second gear G2 and / or the third gear G3; wherein the fourth gear G4 is fixedly connected to the inner ring of the fourth bearing B4 via the fourth shaft S4, the third gear G3 is fixedly connected to the inner ring of the third bearing B3 via the third shaft S3, and the second gear G2 is fixedly connected to the inner ring of the second bearing B2 via the second shaft S2; the first gear G1 has a second U-shaped notch for inserting the optical fiber 01, and the first gear G1 is always meshed with at least one of the second gear G2 or the third gear G3; the outer rings of the second bearing B2, the third bearing B3 and the fourth bearing B4 are all fixedly connected to the gear mounting base plate 3; the ends of the second shaft S2 and the third shaft S3 away from the gear mounting base plate 3 are each provided with a shaft end cap 11.

[0055] The output end of the first gear G1 is connected to one end of the clamp mounting shaft 8 that passes through the first U-shaped notch. The clamp mounting shaft 8 is in rolling connection with the outer rings of the four first bearings B1 that are mounted on the gear mounting base plate 3. The inner rings of the four first bearings B1 are fixedly connected to the gear mounting base plate 3.

[0056] The fiber optic clamp 9 is located at the other end of the clamp mounting shaft 8. Both the clamp mounting shaft 8 and the fiber optic clamp 9 have axially arranged fiber placement slots for placing fiber optic 01. Two sets of fiber clamping assemblies are axially arranged on the fiber placement slots of the fiber optic clamp 9. Each fiber clamping assembly includes a fiber clamping strip 902 vertically positioned above the fiber placement slots of the fiber optic clamp 9, a pull screw 903 on the upper surface of one end of the fiber clamping strip 902, a fiber clamping strip mounting ear 901 connected to the other end of the fiber clamping strip 902 via a shaft on the fiber optic clamp 9, and a magnet embedded in the fiber optic clamp 9 for attracting the fiber clamping strip 902. The cooperation of the fiber clamping strip 902 and the magnet prevents the fiber optic 01 from slipping out during rotation.

[0057] The first gear G1 is used to receive the power transmitted from the second output shaft 602 of the motor 6 through the fourth gear G4, the second gear G2 or the third gear G3 in sequence, so as to drive the fixture mounting shaft 8, the fiber optic clamp 9 and the fiber optic cable 01 to rotate together in sequence.

[0058] The protective cover 2 is connected to the base plate and is located on the side of the gear mounting base 3 away from the optical fiber holder 9. The first gear G1, the second gear G2, the third gear G3, the fourth gear G4, the second output shaft 602 of the motor, the second shaft S2, the third shaft S3, the fourth shaft S4 and the transition shaft S7 are all located in the space enclosed by the protective cover 2, the base plate 1 and the gear mounting base 3. The protective cover 2 has a third U-shaped notch for the optical fiber 01 to pass through.

[0059] The first gear G1 and the fourth gear G4 have the same number of teeth, both being 32; the second gear G2 and the third gear G3 have the same number of teeth, both being 16.

[0060] A reinforcing plate 102 is provided on the side wall of the gear mounting base 3 near the optical fiber holder 9, and a bearing cover plate 101 is provided on the side wall away from the optical fiber holder 9.

[0061] A cylinder is provided on the side of the first gear G1 near the gear mounting base 3; one end of the clamp mounting shaft 8 passes through the cylinder and the first gear G1 in sequence and is connected to the second limiting plate, and is fixedly connected to the cylinder and the first gear G1; the other end of the clamp mounting shaft 8 is connected to the fiber optic clamp 9 through the first limiting plate; four spring plungers are provided on the side of the gear mounting base 3 near the first gear G1, which abut against the end face of the cylinder near the gear mounting base 3; the first limiting plate, the second limiting plate, and the cylinder are all provided with U-shaped limiting notches corresponding to the first U-shaped notch and the second U-shaped notch. Specifically, the end ball of each spring plunger abuts against the cylinder to provide axial force.

[0062] In this embodiment, both the photoelectric sensor 51 and the motor 6 are electrically connected to an external control module.

[0063] In practical applications, this embodiment can be mounted on a slide table. The method for holding and adjusting the optical fiber using the above-described automatic optical fiber rotation fixture includes the following steps:

[0064] Step 1: Assemble the automatic optical fiber rotating fixture and position it in its initial state; prepare optical fiber 01.

[0065] Step 2: Open the two fiber optic clamps 902 by pulling the screw 903, then insert the fiber optic cable 01, put the two fiber optic clamps 902 down and tighten them with the magnet;

[0066] Step 3: Pass an optical signal into optical fiber 01 and start motor 6. This causes the first gear G1 to receive power transmitted from the second output shaft 602 of motor 6 through the fourth gear G4, the second gear G2, or the third gear G3 in sequence. This power drives the fixture mounting shaft 8, the optical fiber holder 9, and optical fiber 01 to rotate together. At the same time, the external optical receiver, which is electrically connected to the external control module, detects the optical power P at the output end of optical fiber 01 in real time.

[0067] Step 4: During the rotation of optical fiber 01, when the optical power P is exactly at its maximum value, the external optical receiver sends signal SS1 to the external control module. After receiving signal SS1, the external control module sends stop signal SS2 to motor 6, causing motor 6 to stop running.

[0068] Step 5: Perform subsequent processing operations on fiber optic 01. After processing, if fiber optic 01 is already fixed to the product, the automatic rotating fixture for the fiber optic cable can be moved out along the axial direction of fiber optic 01 via the slide table. Then, the automatic rotating fixture for the fiber optic cable can be returned to its initial state for future use.

Claims

1. An automatic optical fiber rotation clamp for clamping and rotating an optical fiber (01), wherein the output end of the optical fiber (01) is provided with an inclined surface, characterized in that: It includes a base plate (1), a photoelectric sensor (51) mounted on the base plate (1), a motor (6), a gear mounting base (3), a gear set, a clamp mounting shaft (8), and an optical fiber holder (9), wherein the optical fiber holder (9) is used to hold an optical fiber (01); the gear mounting base (3) is provided with a first U-shaped notch with the opening facing upward. The motor (6) is provided with a first output shaft (601) and a second output shaft (602) at its two ends respectively; The gear set includes a fourth gear (G4) coaxially connected to the second output shaft (602) of the motor, a second gear (G2) and a third gear (G3) meshing with the fourth gear (G4), and a first gear (G1) meshing with the second gear (G2) and / or the third gear (G3); the fourth gear (G4), the third gear (G3), and the second gear (G2) are respectively mounted on one side of the gear mounting base (3); the clamp mounting shaft (8) is rotatably inserted into the first U-shaped notch, and one end of it is located on one side of the gear mounting base (3) and coaxially connected to the first gear (G1), and the other end is located on the other side of the gear mounting base (3) and connected to the optical fiber clamp (9); the first gear (G1) has a second U-shaped notch for the optical fiber (01) to pass through; The end of the first output shaft (601) of the motor is provided with a photoelectric sensor (52) that cooperates with the photoelectric sensor (51) to determine the initial position of the first gear (G1). The initial position is defined as the position when the second U-shaped notch opening faces upward and the photoelectric sensor (51) detects the photoelectric sensor (52). The output power of the motor (6) is transmitted to the first gear (G1) in sequence through the fourth gear (G4), the second gear (G2) and / or the third gear (G3), which drives the fixture mounting shaft (8) and the fiber optic clamp (9) to rotate, thereby driving the fiber optic (01) to rotate. The fixture mounting shaft (8) and the fiber clamping seat (9) are respectively provided with fiber placement slots for placing fiber (01) along the axial direction. M sets of fiber clamping components are arranged sequentially along the axial direction on the fiber placement slot of the fiber clamping seat (9), where M is an integer greater than or equal to 1. Both the photoelectric sensor (51) and the motor (6) are electrically connected to the external control module.

2. The automatic optical fiber rotary clamp according to claim 1, characterized in that: The motor (6) is mounted on the base plate (1) via a motor mounting plate (4), and the motor mounting plate (4) is arranged parallel to the gear mounting base plate (3); The input end of the fourth gear (G4) is provided with a transition shaft (S7), and the transition shaft (S7) is connected to the second output shaft (602) of the motor. The fourth gear (G4) is fixedly connected to the inner ring of the fourth bearing (B4) via the fourth shaft (S4), the third gear (G3) is fixedly connected to the inner ring of the third bearing (B3) via the third shaft (S3), and the second gear (G2) is fixedly connected to the inner ring of the second bearing (B2) via the second shaft (S2); the outer rings of the second bearing (B2), the third bearing (B3), and the fourth bearing (B4) are all fixedly connected to the gear mounting base plate (3). The fixture mounting shaft (8) is in rolling connection with the outer rings of the four first bearings (B1) disposed on the gear mounting base plate (3) on its outer periphery; the inner rings of the four first bearings (B1) are fixedly connected to the gear mounting base plate (3).

3. The automatic optical fiber rotary clamp according to claim 2, characterized in that: The fiber clamping assembly includes a fiber clamping strip (902) disposed above the fiber placement slot of the fiber clamping base (9) and extending perpendicular to the fiber placement slot, a pull screw (903) disposed on the upper surface of one end of the fiber clamping strip (902), a fiber clamping strip mounting ear (901) disposed on the fiber clamping base (9) and connected to the other end of the fiber clamping strip (902) via a rotating shaft, and a magnet embedded in the fiber clamping base (9) for adsorbing the fiber clamping strip (902).

4. The automatic optical fiber rotating clamp according to any one of claims 1 to 3, characterized in that: It also includes a protective cover (2); The protective cover (2) is connected to the base plate and is located on the side of the gear mounting base (3) away from the optical fiber holder (9). The first gear (G1), the second gear (G2), the third gear (G3), the fourth gear (G4), the second shaft (S2), the third shaft (S3), the fourth shaft (S4), and the transition shaft (S7) are all located within the space enclosed by the protective cover (2), the base plate (1), and the gear mounting base (3). The protective cover (2) has a third U-shaped notch for the optical fiber (01) to pass through.

5. The automatic optical fiber rotating fixture according to claim 4, characterized in that: The first gear (G1) and the fourth gear (G4) have the same number of teeth; the second gear (G2) and the third gear (G3) have the same number of teeth.

6. The automatic optical fiber rotary fixture according to claim 5, characterized in that: The first gear (G1) and the fourth gear (G4) each have 32 teeth; the second gear (G2) and the third gear (G3) each have 16 teeth.

7. The automatic optical fiber rotary clamp according to claim 6, characterized in that: A reinforcing plate (102) is provided on the side wall of the gear mounting base (3) near the optical fiber holder (9), and a bearing cover plate (101) is provided on the side wall away from the optical fiber holder (9).

8. The automatic optical fiber rotary fixture according to claim 7, characterized in that: The M = 2; The second output shaft (602) and the transition shaft (S7) of the motor are connected by a coupling (7).

9. The automatic optical fiber rotary fixture according to claim 8, characterized in that: Both the second shaft (S2) and the third shaft (S3) have shaft end caps (11) at the ends away from the gear mounting base plate (3).

10. The automatic optical fiber rotary fixture according to claim 9, characterized in that: It also includes a first limiting plate and a second limiting plate; A cylinder is provided on the side of the first gear (G1) near the gear mounting base plate (3); One end of the fixture mounting shaft (8) passes through the cylinder and the first gear (G1) in sequence and is connected to the second limiting plate, and is fixedly connected to the cylinder and the first gear (G1); The other end of the fixture mounting shaft (8) is connected to the fiber optic clamp (9) via a first limiting plate; Four spring plungers are provided on the side of the gear mounting base plate (3) near the first gear (G1), which abut against the end face of the cylinder near the gear mounting base plate (3). The first limiting plate, the second limiting plate, and the cylinder are all provided with U-shaped limiting notches corresponding to the first U-shaped notch and the second U-shaped notch.

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