Micro O-ring assembly apparatus

Abstract

The utility model relates to automatic assembly equipment technical field especially is a kind of micro O type ring assembly equipment, including machine body, protective cover, material spare feeding device, O type ring feeding device, O type ring sorting device and the assembly mechanism for being used to assemble O type ring to material spare on, the O type ring sorting device includes parallel robot being arranged in machine body and setting material taking manipulator of parallel robot, this material taking manipulator includes the mounting seat of being installed in parallel robot, hollow negative pressure rod of being installed in mounting seat and the material taking head of being installed in the lower end of hollow negative pressure rod, the lower end surface of material taking head is opened to have multiple annularly arranged suction holes, the annular of the multiple suction holes arrangement corresponds with the size of O type ring, suction hole is communicated with negative pressure gas source equipment by the hollow pipe of hollow negative pressure rod and air duct.The stable, accurate, lossless and efficient transfer and positioning from feeding system to assembly station can be realized without damaging the sealing ring.

Description

Technical Field

[0001] This utility model relates to the field of automated assembly equipment technology, and in particular to a micro O-ring assembly equipment. Background Technology

[0002] In modern manufacturing industries such as precision instruments, microfluidic control systems, consumer electronics, medical devices, and high-end aerospace equipment, miniature O-rings are increasingly widely used as a key dynamic or static sealing element. These O-rings are typically made of highly elastic polymer materials such as silicone rubber and fluororubber, with an outer diameter often less than 5 millimeters, or even reaching the sub-millimeter level. Their tiny cross-sectional diameter gives them excellent flexibility and deformability.

[0003] The very miniaturization and flexibility described above present significant technical challenges for their automated assembly. In mass production, achieving efficient, reliable, and precise automated material handling, transfer, and assembly of tiny O-rings is crucial for improving product consistency, ensuring sealing performance, and reducing labor costs. However, current industry-standard automation solutions exhibit significant limitations and shortcomings when dealing with tiny O-rings: 1. Failure of Traditional Mechanical Grippers: Commonly available rigid mechanical grippers (such as two- or three-finger pneumatic / electric grippers) are unable to reliably grip tiny O-rings. Due to their extremely soft material, rigid grippers are prone to excessive deformation, crushing, or adhesion of the O-ring when applying sufficient gripping force. If the gripping force is reduced, insufficient friction cannot overcome the O-ring's gravity or inertia, leading to gripping failure or premature detachment. Furthermore, the positioning accuracy of the grippers is extremely mismatched with the size of the miniature O-ring, making stable alignment difficult to achieve.

[0004] 2. Unstable Vacuum Adsorption: Using a vacuum nozzle for suction is another common solution. However, for tiny O-rings, whose surfaces are curved, soft, and extremely lightweight, it is difficult for a vacuum suction cup to create a stable and uniform negative pressure seal. During suction, the O-ring is prone to leakage due to slight deformation, resulting in weak adhesion, or it may flip or drift due to airflow disturbances during movement, making it impossible to guarantee positioning accuracy. For O-rings with extremely small inner diameters, vacuum adsorption may even completely block their inner holes or even suck them into the pipeline, making stable feeding impossible.

[0005] 3. Difficulty in coordinating vision and feeding systems: Tiny O-rings in vibrating feed trays or troughs are prone to entanglement, accumulation, and misalignment due to static electricity, oil contamination, or mutual contact, leading to unstable feeding. Even if the vision system can identify their position, the actuator (gripper or nozzle) often fails to reliably grasp them in the intended posture due to the aforementioned gripping difficulties, significantly reducing the success rate and cycle time of the entire pick-and-place system.

[0006] 4. Inefficient and inconsistent quality of manual assembly: Due to the unreliability of automated equipment, many production processes still heavily rely on skilled workers performing manual assembly under microscopes. This method is not only extremely inefficient and costly in terms of labor, but also highly dependent on individual skills and condition, easily introducing contamination, damaging seals, or causing improper installation. Product consistency and reliability are difficult to guarantee, becoming a bottleneck restricting capacity and yield improvement.

[0007] Currently, although there are automated solutions for small standard parts in the industry, when directly applied to tiny O-rings, they are not very effective because they fail to overcome the comprehensive gripping challenges brought about by their "small size, softness, variability, and light weight".

[0008] There is an urgent market need for an innovative, automated material handling and assembly device specifically designed for the physical characteristics of tiny O-rings. This device must be able to achieve stable, precise, non-destructive, and efficient transfer and placement of the O-ring from the feeding system to the assembly station without damaging it. This would liberate the precision manufacturing industry from the challenges of this micro-assembly process and meet the pressing demands of modern intelligent manufacturing for high precision, high reliability, and high efficiency. Utility Model Content

[0009] The technical problem to be solved by this utility model is to provide an automated material handling and assembly equipment for micro O-rings that is specifically designed for the physical characteristics of micro O-rings. It can achieve stable, accurate, non-destructive and efficient transfer and positioning of the O-rings from the material supply system to the assembly station without damaging the O-rings, thus filling a market gap.

[0010] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a micro O-ring assembly device, comprising a body, a protective cover fixedly installed on the body, a material feeding device installed inside the protective cover, an O-ring feeding device, an O-ring sorting device, and an assembly mechanism for assembling O-rings onto the material. The O-ring sorting device includes a parallel robot installed on the body and a picking manipulator installed on the parallel robot. The picking manipulator includes a mounting base installed on the parallel robot, a hollow negative pressure rod installed on the mounting base, and a picking head installed at the lower end of the hollow negative pressure rod. The lower end face of the picking head has multiple annularly arranged suction holes. The annular arrangement of the multiple suction holes corresponds to the size of the O-rings. The suction holes are connected to a negative pressure air source device through the hollow tube and air guide tube of the hollow negative pressure rod.

[0011] Preferably, a top plate is fixed above the machine body, the parallel robot is installed at the front of the top plate, a detection camera is installed at the rear of the top plate, a material tray is installed directly below the detection camera, and an O-ring feeding device disperses O-rings into the material tray.

[0012] Preferably, the hollow negative pressure rod is movably mounted on the mounting base, and the hollow negative pressure rod is fitted with a buffer spring, the two ends of which abut against the mounting base and the material taking head, respectively.

[0013] Preferably, the O-ring feeding device further includes an intermittently rotating positioning turntable and at least three positioning clamps evenly distributed in a ring on the positioning turntable. The positioning clamps are provided with positioning conical grooves corresponding to the shape and size of the O-rings. A positioning through hole is provided in the middle of the positioning conical groove. A positioning conical rod and a lifting drive mechanism for driving the positioning conical rod to move up and down are installed below the positioning turntable. When the positioning conical rod rises to the top, the top end of the positioning conical rod is embedded in the positioning conical groove.

[0014] Preferably, each of the positioning fixtures has two positioning conical grooves. The assembly mechanism includes a dual-head assembly robot and a two-axis moving mechanism for driving the dual-head assembly robot to move in the X and Z directions. The dual-head assembly robot includes two three-jaw robots arranged side by side. The inner wall of the positioning conical groove is provided with a radial groove for accommodating the three-jaw robots. When the three-jaw robots open and close, the three grippers of the three-jaw robots move radially back and forth in the radial groove.

[0015] Preferably, the assembly mechanism includes an intermittently rotating assembly turntable and at least three assembly fixtures evenly distributed in a ring on the assembly turntable, wherein one assembly fixture is positioned at the rightmost position, and when the dual-head assembly robot moves to the leftmost position along the X direction, the three-jaw robot is positioned directly above the assembly fixture.

[0016] Preferably, the two-axis moving mechanism includes a vertical plate erected on the machine body, a drive motor fixed to the back of the vertical plate, a slide plate fixed to the front of the vertical plate, and a transverse slide rail. The front of the slide plate has a U-shaped slide groove. The transverse slide rail is equipped with a slider that can move laterally. The slider is equipped with a lifting slide rail that can be raised and lowered. The dual-head assembly robot is fixedly installed at the lower end of the lifting slide rail. The main shaft of the drive motor passes through the vertical plate and is equipped with a swing arm. The outer end of the swing arm has an elongated hole. The upper end of the lifting slide rail is fixed with a linkage pin. The linkage pin passes through the elongated hole and then is movably embedded in the U-shaped slide groove.

[0017] Preferably, a T-shaped connector is fixedly installed at the upper end of the lifting slide rail, the front end of the linkage pin is fixed to the T-shaped connector, and a roller is installed at the rear end of the linkage pin, which is movably embedded in the U-shaped slide groove.

[0018] The beneficial effects of this utility model are as follows: This utility model provides a micro O-ring assembly device. In practical applications, the O-rings are first transported to the material tray by a vibrating feeder, and then the picking robot picks up the O-rings one by one and places them into the assembly mechanism. The assembly mechanism then assembles the O-rings with the material (in this embodiment, a silencer nozzle) and collects them, thus completing the automated assembly process of the micro O-rings. This utility model adopts a special picking head structure, utilizing multiple suction holes arranged in a ring corresponding to the size of the O-rings, combined with negative pressure to achieve precise picking of the O-rings. It is an automated picking and assembly device specifically designed for the physical characteristics of micro O-ring seals. This device must be able to achieve stable, accurate, non-destructive, and efficient transfer and placement of the seals from the feeding system to the assembly station without damaging them, thereby liberating the precision manufacturing industry from this micro-assembly dilemma, filling a market gap, and meeting the urgent needs of modern intelligent manufacturing for high precision, high reliability, and high efficiency. It is highly practical. Attached Figure Description

[0019] Figure 1 This is a three-dimensional structural diagram of the micro O-ring assembly equipment of this utility model.

[0020] Figure 2 This is a three-dimensional structural diagram of the assembly equipment of this utility model with the protective cover hidden.

[0021] Figure 3 This is a three-dimensional structural diagram of the assembly equipment of this utility model when the protective cover is hidden.

[0022] Figure 4 This is a top view of the assembly equipment of this utility model with the protective cover hidden.

[0023] Figure 5 This is a three-dimensional structural diagram of the O-ring sorting device in the assembly equipment of this utility model.

[0024] Figure 6 This is a three-dimensional structural diagram of the parallel robot in the assembly equipment of this utility model.

[0025] Figure 7 This is a three-dimensional structural diagram of the two-axis moving mechanism in the assembly equipment of this utility model.

[0026] Figure 8 This is an exploded three-dimensional structural diagram of the two-axis moving mechanism in the assembly equipment of this utility model.

[0027] Figure 9 for Figure 5 A magnified schematic diagram of part A in the middle.

[0028] Figure 10This is a three-dimensional structural diagram of the positioning turntable and positioning clamp in the assembly equipment of this utility model. Detailed Implementation

[0029] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments. The content mentioned in the embodiments is not intended to limit the present invention.

[0030] like Figures 1 to 10 As shown, a micro O-ring assembly device includes a body, a protective cover 4 fixedly installed on the body, a material feeding device 1 installed inside the protective cover 4, an O-ring feeding device 2, an O-ring sorting device 3, and an assembly mechanism 5 for assembling O-rings onto the materials. The O-ring sorting device 3 includes a parallel robot 31 installed on the body and a picking manipulator 32 installed on the parallel robot 31. The picking manipulator 32 includes a mounting base 33 installed on the parallel robot 31, a hollow negative pressure rod 34 installed on the mounting base 33, and a picking head 35 installed at the lower end of the hollow negative pressure rod 34. The lower end face of the picking head 35 has a plurality of annularly arranged suction holes 36. The annular arrangement of the plurality of suction holes 36 corresponds to the size of the O-rings. The suction holes 36 are connected to a negative pressure air source device through the hollow tube and air guide tube of the hollow negative pressure rod 34.

[0031] In practical applications, O-rings are first transported to the material tray 38 by a vibrating feeder 38, and then the picking robot 32 picks up the O-rings one by one and places them into the assembly mechanism 5. The assembly mechanism 5 then assembles the O-rings with the material (in this embodiment, a silencer nozzle) and collects them, thus completing the automated assembly and processing of the micro O-rings. This utility model adopts a special material picking head 35 structure, utilizing multiple suction holes 36 arranged in a ring corresponding to the size of the O-rings, combined with negative pressure to achieve precise picking of the O-rings. It is an automated material picking and assembly device specifically designed for the physical characteristics of micro O-ring seals. This device must be able to achieve stable, accurate, non-destructive, and efficient transfer and placement of the seals from the feeding system to the assembly station without damaging them, thereby liberating the precision manufacturing industry from this micro-assembly dilemma, filling a market gap, and meeting the urgent needs of modern intelligent manufacturing for high precision, high reliability, and high efficiency. It is highly practical.

[0032] In this embodiment, a top plate 37 is fixed above the machine body, and the parallel robot 31 is mounted on the front of the top plate 37. A detection camera is mounted on the rear of the top plate 37, and a material tray 38 is mounted directly below the detection camera. The O-ring feeding device 2 disperses the O-rings into the material tray 38. The detection camera can accurately locate the specific position of the O-rings, facilitating precise gripping by the material-picking robot 32. This method has the advantages of fast positioning speed, high positioning accuracy, and high reliability.

[0033] In this embodiment, the hollow negative pressure rod 34 is movably mounted on the mounting base 33. A buffer spring 39 is fitted onto the hollow negative pressure rod 34, with both ends of the buffer spring 39 abutting against the mounting base 33 and the material handling head 35, respectively. When the hollow negative pressure rod 34 moves downward under the drive and control of the material handling robot 32, the buffer spring 39 is designed to reduce the impact force of the material handling head 35 on the O-ring workpiece, preventing damage to the O-ring and ensuring a high safety factor.

[0034] In this embodiment, the O-ring feeding device 2 further includes an intermittently rotating positioning turntable 21 and at least three positioning clamps 22 evenly distributed in a ring on the positioning turntable 21. The positioning clamps 22 have positioning conical grooves 23 corresponding to the shape and size of the O-rings. The positioning conical grooves 23 have positioning through holes 25 in the middle. A positioning conical rod 24 and a lifting drive mechanism 26 for driving the positioning conical rod 24 to move up and down are installed below the positioning turntable 21. When the positioning conical rod 24 rises to the top, the top end of the positioning conical rod 24 is embedded in the positioning conical groove 23. The top of the positioning cone 24 and the positioning cone groove 23 form an annular groove. When the picking robot 32 moves the O-ring into the positioning cone groove 23, the annular groove structure effectively prevents the O-ring from twisting or shifting when it is dropped from the picking robot 32, resulting in high positioning accuracy. After the O-ring is put down, the top of the positioning cone 24 retracts under the action of the lifting drive mechanism 26, which facilitates the rotation of the positioning turntable 21 to drive the positioning fixture 22 to move to the next station for feeding or inspection, resulting in high reliability.

[0035] See Figure 5 and Figure 10 In this embodiment, each positioning fixture 22 has two positioning conical grooves 23. The assembly mechanism 5 includes a dual-head assembly robot 30 and a two-axis moving mechanism 6 for driving the dual-head assembly robot 30 to move in the X and Z directions. The dual-head assembly robot 30 includes two three-jaw robots 27 arranged side by side. The inner wall of the positioning conical groove 23 has a radial groove 28 for accommodating the three-jaw robots 27. When the three-jaw robots 27 open and close, the three jaws of the three-jaw robots 27 move radially back and forth within the radial groove 28. The dual-groove structure and dual-robot structure design double the assembly efficiency of O-rings, significantly improving production efficiency. When not picking up material, the three grippers of the three-jaw robot 27 are in a closed state. When picking up material, the three grippers of the three-jaw robot 27 move to the middle position of the positioning cone groove 23, and then the three grippers open outwards simultaneously to push the O-ring from the inner ring outwards. This not only achieves the picking and fixing of the O-ring, but also allows the O-ring to be easily fitted onto the workpiece (in this embodiment, a silencer nozzle) in the opened state. The assembly and processing are stable and reliable, and the operability is strong. The design of the radial groove 28 solves the problem that the three-jaw robot 27 cannot hold the O-ring within the positioning cone groove 23. The structural design is ingenious and practical.

[0036] In this embodiment, the assembly mechanism 5 includes an intermittently rotating assembly turntable 51 and at least three assembly fixtures 52 evenly distributed in a ring on the assembly turntable 51. One of the assembly fixtures 52 is positioned at the rightmost end, and when the dual-head assembly robot 30 moves along the X-axis to the leftmost end, the three-jaw robot 27 is positioned directly above the assembly fixture 52. This facilitates material handling and assembly by the three-jaw robot 27, greatly simplifies the displacement control structure of the dual-head assembly robot 30, makes displacement drive more precise and reliable, reduces operating and maintenance costs and manufacturing difficulty, and offers high cost-effectiveness.

[0037] See Figure 7 and Figure 8 In this embodiment, the two-axis moving mechanism 6 includes a vertical plate 61 erected on the machine body, a drive motor 62 fixed to the back of the vertical plate 61, a slide plate 63 fixed to the front of the vertical plate 61, and a transverse slide rail 64. The front of the slide plate 63 is provided with a U-shaped slide groove 65. The transverse slide rail 64 is equipped with a slider 66 that can move laterally. The slider 66 is equipped with a lifting slide rail 67 that can be raised and lowered. The dual-head assembly robot 30 is fixedly installed at the lower end of the lifting slide rail 67. The main shaft of the drive motor 62 passes through the vertical plate 61 and is equipped with a swing arm 69. The outer end of the swing arm 69 is provided with an elongated hole 6A. The upper end of the lifting slide rail 67 is fixed with a linkage pin 68. The linkage pin 68 passes through the elongated hole 6A and is then movably embedded in the U-shaped slide groove 65. The swing arm 69 reciprocates under the action of the drive motor 62, and drives the linkage pin 68 to move back and forth along the trajectory of the U-shaped slide 65. At this time, the slider 66 moves back and forth along the transverse slide rail 64, and the lifting slide rail 67 moves up and down synchronously, so that the double-head assembly robot 30 moves in the X and Z directions according to the U-shaped slide 65. This realizes the driving effect of the double-head assembly robot 30 picking up materials from the positioning fixture 22 and placing materials on the assembly fixture 52 for assembly. The structure is simple, stable and reliable, with high control precision and strong durability.

[0038] In this embodiment, a T-shaped connector 6B is fixedly installed at the upper end of the lifting slide rail 67. The front end of the linkage pin 68 is fixed to the T-shaped connector 6B, and a roller is installed at the rear end of the linkage pin 68. The roller is movably embedded in the U-shaped slide groove 65. The design of the T-shaped connector 6B greatly reduces the assembly difficulty of the linkage pin 68 and the U-shaped slide groove 65, facilitating inspection and maintenance. The roller design reduces wear and significantly extends the service life of the two-axis moving mechanism 6, making it more practical.

[0039] In the description of this utility model, it should be noted that the directional terms such as "center", "horizontal (X)", "longitudinal (Y)", "vertical (Z)", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", and "counterclockwise" indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. They should not be construed as limiting the specific protection scope of this utility model.

[0040] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features. Thus, the use of "first" and "second" to define a feature may explicitly or implicitly include one or more of that feature. In this description of the utility model, "a number" means two or more, unless otherwise explicitly specified.

[0041] In this utility model, unless otherwise explicitly specified and limited, the terms "assembly," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can also refer to a mechanical connection; they can refer to a direct connection or a connection through an intermediate medium; or they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0042] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A micro O-ring assembly device, comprising a body, a protective cover (4) fixedly disposed on the body, a material feeding device (1) installed inside the protective cover (4), an O-ring feeding device (2), an O-ring sorting device (3), and an assembly mechanism (5) for assembling O-rings onto the material, characterized in that: The O-ring sorting device (3) includes a parallel robot (31) installed on the machine body and a picking manipulator (32) installed on the parallel robot (31). The picking manipulator (32) includes a mounting base (33) installed on the parallel robot (31), a hollow negative pressure rod (34) installed on the mounting base (33), and a picking head (35) installed at the lower end of the hollow negative pressure rod (34). The lower end face of the picking head (35) is provided with a plurality of annularly arranged suction holes (36). The annular arrangement of the plurality of suction holes (36) corresponds to the size of the O-ring. The suction holes (36) are connected to the negative pressure air source equipment through the hollow tube and air guide tube of the hollow negative pressure rod (34).

2. The micro O-ring assembly equipment according to claim 1, characterized in that: A top plate (37) is fixed above the body. The parallel robot (31) is installed at the front of the top plate (37). A detection camera is installed at the rear of the top plate (37). A material tray (38) is installed directly below the detection camera. The O-ring feeding device (2) disperses the O-rings into the material tray (38).

3. The micro O-ring assembly equipment according to claim 1, characterized in that: The hollow negative pressure rod (34) is movably mounted on the mounting base (33). The hollow negative pressure rod (34) is fitted with a buffer spring (39). The two ends of the buffer spring (39) abut against the mounting base (33) and the material taking head (35) respectively.

4. The micro O-ring assembly equipment according to claim 1, characterized in that: The O-ring feeding device (2) further includes an intermittently rotating positioning turntable (21) and at least three positioning clamps (22) evenly distributed in a ring on the positioning turntable (21). The positioning clamps (22) are provided with positioning cone grooves (23) corresponding to the shape and size of the O-rings. A positioning through hole (25) is provided in the middle of the positioning cone groove (23). A positioning cone rod (24) and a lifting drive mechanism (26) for driving the positioning cone rod (24) to move up and down are installed below the positioning turntable (21). When the positioning cone rod (24) rises to the top, the top of the positioning cone rod (24) is embedded in the positioning cone groove (23).

5. The micro O-ring assembly equipment according to claim 4, characterized in that: Each of the positioning fixtures (22) has two positioning cone grooves (23). The assembly mechanism (5) includes a double-headed assembly robot (30) and a two-axis moving mechanism (6) for driving the double-headed assembly robot (30) to move in the X and Z directions. The double-headed assembly robot (30) includes two three-jaw robots (27) arranged side by side. The inner wall of the positioning cone groove (23) is provided with a radial groove (28) for accommodating the three-jaw robots (27). When the three-jaw robots (27) open and close, the three jaws of the three-jaw robots (27) move radially back and forth in the radial groove (28).

6. The micro O-ring assembly equipment according to claim 5, characterized in that: The assembly mechanism (5) includes an intermittently rotating assembly turntable (51) and at least three assembly fixtures (52) evenly distributed in a ring on the assembly turntable (51), wherein one of the assembly fixtures (52) is stopped at the rightmost position, and when the dual-head assembly robot (30) moves to the leftmost position along the X direction, the three-jaw robot (27) is located directly above the assembly fixture (52).

7. The micro O-ring assembly equipment according to claim 5, characterized in that: The two-axis moving mechanism (6) includes a vertical plate (61) erected on the machine body, a drive motor (62) fixed to the back of the vertical plate (61), a slide plate (63) fixed to the front of the vertical plate (61), and a transverse slide rail (64). The slide plate (63) has a U-shaped slide groove (65) on its front side. The transverse slide rail (64) is equipped with a slider (66) that can move laterally. The slider (66) is equipped with a lifting slide rail (67) that can be lifted up and down. The double-headed assembly robot (30) is fixedly installed at the lower end of the lifting slide rail (67). The main shaft of the drive motor (62) passes through the vertical plate (61) and is equipped with a swing arm (69). The outer end of the swing arm (69) is provided with an elongated hole (6A). The upper end of the lifting slide rail (67) is fixed with a linkage pin (68). The linkage pin (68) passes through the elongated hole (6A) and then is movably embedded in the U-shaped slide groove (65).

8. The micro O-ring assembly equipment according to claim 7, characterized in that: The upper end of the lifting slide rail (67) is fixedly equipped with a T-shaped connector (6B), the front end of the linkage pin (68) is fixed to the T-shaped connector (6B), and the rear end of the linkage pin (68) is equipped with a roller, which is movably embedded in the U-shaped groove (65).

Images