A snap assembly method and a snap

Abstract

This invention discloses a snap-fit ​​assembly method and a snap-fit ​​itself. The snap-fit ​​includes an upper universal joint, a vertical connecting post, a lower mounting body, and left and right opposing rollers disposed on both sides of the lower mounting body. During assembly, the left and right opposing rollers and the vertical connecting post are first assembled onto the lower mounting body. Then, the upper universal joint is assembled onto the vertical connecting post and pre-tightened, allowing the lower mounting body to rotate circumferentially relative to the upper universal joint. Subsequently, the lower mounting body is driven to rotate one revolution around the vertical connecting post, and the rotation path is divided into multiple circumferential detection intervals. The rotational resistance value of each interval is obtained, and the presence of local jamming points is determined based on a preset upper resistance limit and the resistance difference between adjacent intervals. When local jamming points exist, the upper universal joint is adjusted until continuous rotation is achieved. Simultaneously, axial movement detection and roller idle rotation detection are combined to determine the assembly state, reducing problems such as local tightness, looseness, and inconsistent roller guidance during snap-fit ​​rotation.

Description

Technical Field

[0001] This invention relates to the field of seat belt connectors and buckle assembly technology, and in particular to a buckle assembly method and buckle for seat belt traction scenarios. Background Technology

[0002] In scenarios involving children's outdoor training, climbing training, play training, or similar activities requiring seat belt traction, the child's seat belt is typically connected to an overhead support frame, guide frame, or sliding frame. This allows the seat belt to move synchronously with the child as they walk, turn, move laterally, or traverse bending areas. To reduce friction between the connector and the support frame, existing technologies often incorporate rollers, bearings, eyelets, or rotatable connectors on the buckle, allowing it to slide along the support frame and adapt to traction in different directions to some extent.

[0003] Existing buckles with universal joints typically include an upper adapter structure for engaging with a support frame, a vertical connector for load-bearing connection, a lower attachment structure for attaching the seat belt, and a roller structure for rolling guidance. While these buckles meet basic usage requirements for straight-line traction or low-frequency steering, they still have shortcomings in actual assembly and use.

[0004] Specifically, existing buckles typically focus on ensuring the secure connection of each component during assembly, such as whether the rollers are properly installed, the connecting posts are fixed, and the hanging body can bear the load. However, they rarely pay detailed control over the pre-tightening state of the upper universal joint. If the upper universal joint is assembled too tightly, although the buckle is securely connected, the lower hanging body will experience greater resistance when rotating around the vertical connecting post. This can lead to difficulty in timely directional alignment when the support frame turns or when the child is pulled at an angle, resulting in brief pauses. If the upper universal joint is assembled too loosely, although the buckle can rotate, it is prone to looseness, abnormal noise, and eccentric wobbling when the child runs, swings, or suddenly stops.

[0005] Furthermore, even if the upper universal joint can rotate as a whole, uneven pressing, inconsistent pressure on the gaskets, misalignment of the vertical connecting column, burrs on the mating surfaces, or uneven local stress on the clamping parts may cause the lower hanging body to not rotate continuously and smoothly around the vertical connecting column. Instead, local resistance peaks may appear at a certain angle or within a certain angle range. These local resistance peaks are not easily detected during normal no-load inspections, but when children actually use the device, they will manifest as the buckles suddenly tightening when passing through frame corners, horizontal and vertical transition positions, or oblique stress positions, causing discontinuous roller guidance.

[0006] Therefore, the existing snap-fit ​​assembly method has at least the following shortcomings: First, it lacks the detection and adjustment of the pre-tightening degree of the upper universal joint, which can easily lead to differences in snap-fits within the same batch being too tight or too loose; Second, it lacks the inspection of local jamming points during one rotation of the snap-fit, making it impossible to effectively identify the problem of sudden increase in rotational resistance at a certain angle; Third, it lacks an assembly control method that combines the judgment of rotational resistance, axial movement, and roller idling, which may cause the snap-fit ​​to still experience jamming, shaking, or untimely alignment in actual turning and oblique traction scenarios.

[0007] Therefore, it is necessary to provide a buckle assembly method and buckle. Without significantly changing the overall structure of the buckle, by limiting the assembly sequence, pre-tightening adjustment and detection method between the upper universal adapter, the vertical connecting column, the lower hanging body and the left and right opposing rollers, the buckle can maintain connection stability after assembly and reduce local jamming points during one rotation. Summary of the Invention

[0008] The purpose of this invention is to provide a buckle assembly method and buckle to solve the problem that existing buckles with universal adapter structures lack detection of pre-tightening state and local rotation jamming points during assembly, which leads to problems such as local tightness, shaking and inconsistent smoothness of the buckle during actual traction and steering.

[0009] To achieve the above objectives, the present invention provides a buckle assembly method for assembling a buckle used for seat belt traction. The buckle includes an upper universal joint, a ball bearing disposed below the upper universal joint, a vertical connecting post, a lower hook-up body, and a left opposing roller and a right opposing roller disposed on both sides of the lower hook-up body. The lower hook-up body has hook-up holes located below the left opposing roller and the right opposing roller. The buckle assembly method includes: The left opposing roller and the right opposing roller are assembled on both sides of the lower hanging body 30, and the vertical connecting column is assembled on the lower hanging body; The upper universal joint is assembled onto the vertical connecting column, and the upper universal joint is pre-tightened so that the lower hanging body can rotate circumferentially relative to the upper universal joint through the vertical connecting column. Drive the lower hanging body to rotate around the vertical connecting column for one revolution, obtain the resistance change state during the rotation process, and determine whether there is a local jamming point in the upper universal joint based on the resistance change state; When there are local jams in the resistance change state, adjust the pre-tightness of the upper universal joint relative to the vertical connecting column, and drive the lower hanging body to rotate one revolution again for re-inspection until the resistance change state meets the preset continuous rotation condition.

[0010] In the above-described buckle assembly method, the basic assembly of the left opposing roller, the right opposing roller, the lower hook-on body, and the vertical connecting column is completed first. Then, the upper universal joint is assembled to the vertical connecting column and pre-tightened. Compared with relying solely on manual feel to determine whether the rotation is smooth, this invention further drives the lower hook-on body to rotate one revolution around the vertical connecting column. By observing the change in resistance during the rotation, it determines whether there are local jamming points, thereby identifying the problem of the buckle suddenly tightening at a certain circumferential angle.

[0011] In one embodiment, after the left and right opposing rollers are assembled to both sides of the lower mounting body, the central region between the left and right opposing rollers is used as the assembly reference for the vertical connecting column, ensuring that the centerline of the vertical connecting column passes through the central region between the left and right opposing rollers. This reduces eccentric swaying caused by the vertical connecting column deviating from the center position of the two rollers.

[0012] In one embodiment, the upper universal joint includes an adapter seat and a clamping member. When the upper universal joint is assembled to the vertical connecting column, the vertical connecting column passes through the adapter seat, and the clamping member pre-tightens the rotational fit between the adapter seat and the vertical connecting column.

[0013] In one embodiment, when pre-tightening the upper universal joint, the clamping member is first placed in the initial locked position, and then the lower hook-on body is driven to rotate for detection. When the resistance change does not meet the preset continuous rotation condition, the position of the clamping member is incrementally adjusted. The incremental adjustment can be a small-angle loosening, a small-angle locking, increasing the shim thickness, decreasing the shim thickness, adjusting the pressure cap insertion depth, or re-cleaning the rotational mating position.

[0014] In one embodiment, obtaining the resistance change state during rotation includes: dividing the path of the lower hanging body rotating one revolution into multiple circumferential detection intervals, obtaining the rotational resistance value in each of the circumferential detection intervals, and determining whether the local jamming point exists based on the difference in rotational resistance between adjacent circumferential detection intervals.

[0015] In one embodiment, when the rotational resistance value within any circumferential detection interval is greater than a preset resistance upper limit, or the difference in rotational resistance between adjacent circumferential detection intervals is greater than a preset fluctuation threshold, it is determined that the resistance change state contains a local jamming point. Thus, the determination of local jamming points can be transformed from purely subjective feeling into a recordable and re-verifiable judgment condition.

[0016] In one embodiment, the preset upper limit of resistance is determined by the reference value of rotational resistance and the allowable deviation of qualified samples of the same specification; the preset fluctuation threshold is determined by the resistance difference between adjacent circumferential detection intervals of qualified samples of the same specification and the allowable fluctuation ratio; the preset sway range is determined by the size of the buckle, the load-bearing level, and the allowable swing requirements of the seat belt connector.

[0017] In one embodiment, after determining whether there is a local jamming point in the upper universal joint, the axial movement state of the vertical connecting column relative to the upper universal joint is also checked; when the axial movement state does not meet the preset movement conditions, the pre-tightening degree of the upper universal joint relative to the vertical connecting column is adjusted.

[0018] In one embodiment, the preset continuous rotation condition includes that no local jamming point occurs during one rotation of the lower hanging body, and the preset axial movement condition includes that the axial movement of the vertical connecting column relative to the upper universal joint is within a preset axial movement range.

[0019] In one embodiment, after the resistance change state meets the preset continuous rotation condition, the left opposing roller and the right opposing roller are driven to rotate idling relative to the lower attachment body, and the preset idling condition is determined based on the idling state of the left opposing roller and the right opposing roller; when either opposing roller does not meet the preset idling condition, the axial limit state of the opposing roller is adjusted and the idling check is performed again.

[0020] The present invention also provides a buckle, comprising: an upper universal joint, a vertical connecting post, a lower hook-up body, and left and right opposing rollers. The vertical connecting post is rotatably connected to the upper universal joint; the lower hook-up body is connected to the vertical connecting post and is capable of circumferentially rotating relative to the upper universal joint via the vertical connecting post; the left and right opposing rollers are respectively disposed on both sides of the lower hook-up body; wherein, the pre-tightening degree of the upper universal joint relative to the vertical connecting post is determined by the buckle assembly method described in any of the above embodiments.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects: This invention drives the lower mounting body to rotate around the vertical connecting column once, and judges whether there are local jamming points in the upper universal joint based on the resistance change during the rotation process. It can identify the problem of the buckle suddenly tightening at a certain angle, and avoid missing local jamming points due to simple rotation inspection.

[0022] After identifying local jamming points, this invention adjusts the pre-tightening degree of the upper universal joint relative to the vertical connecting column and performs a re-inspection to ensure that the upper universal joint maintains connection stability and meets the requirements for continuous rotation.

[0023] The present invention further combines the axial movement state of the vertical connecting column and the idling state of the left and right opposing rollers to make judgments, which can reduce assembly differences caused by the upper universal joint being too loose or too tight and abnormal axial positioning of the rollers.

[0024] This invention can select the corresponding pre-tightening adjustment, mating surface trimming, or roller limit adjustment action based on the test results, so that the test results and adjustment actions form a corresponding relationship, reducing the problem of assembly personnel repeatedly trying to assemble based solely on experience. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of the buckle according to an embodiment of the present invention.

[0026] Figure 2 This is an exploded structural diagram of the buckle according to an embodiment of the present invention.

[0027] Figure 3 This is a schematic flowchart of a snap-fit ​​assembly method according to an embodiment of the present invention.

[0028] Figure 4 This is a schematic diagram of the assembly structure of the upper universal joint and the vertical connecting column according to an embodiment of the present invention.

[0029] Figure 5 This is a schematic diagram of the resistance detection process for one revolution as described in an embodiment of the present invention.

[0030] Figure 6 This is a schematic diagram of axial movement detection according to an embodiment of the present invention.

[0031] Figure 7 This is a schematic diagram of the left and right opposing rollers idling detection according to an embodiment of the present invention.

[0032] Figure 8 This is a schematic diagram showing the state in which the buckle and the seat belt connector are used in conjunction in one embodiment of the present invention.

[0033] Figure 9 This is a schematic diagram illustrating the division of the circumferential detection interval according to an embodiment of the present invention.

[0034] Figure 10 This is a schematic diagram of the structure of a common manual inspection fixture according to an embodiment of the present invention.

[0035] Explanation of reference numerals in the attached figures: 100. Buckle; 10. Upper universal adapter; 11. Adapter seat; 12. Clamping component; 13. Rotational mating position; 14. Ball bearing; 20. Vertical connecting column; 21. Column; 22. Axial limiting component; 30. Lower hanging body; 31. Hanging hole; 32. Roller mounting position; 33. Main body connecting hole; 40. Left opposing roller; 41. Right opposing roller; 42. Roller shaft; 43. Axial limiting component; 50. Safety belt connector; 60. Rotation detection fixture; 61. Resistance detection unit; 62. Circumferential detection range; 63. Axial movement detection component; 64. Roller idling detection component; 65. Positioning seat; 66. Rotating handle; 67. Elastic force measuring component; 68. Angle marking part; 70. Support frame. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the present invention clearer, specific embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the present invention. Where there is no conflict, the technical features in the following embodiments can be combined with each other.

[0037] like Figure 1 and Figure 2 As shown, this embodiment provides a buckle 100, which includes an upper universal joint 10, a vertical connecting post 20, a lower hook-on body 30, a left opposing roller 40, and a right opposing roller 41. The upper universal joint 10 is used to cooperate with a support frame 70 or other guide structures. The vertical connecting post 20 is disposed between the upper universal joint 10 and the lower hook-on body 30. The lower hook-on body 30 is used to cooperate with a seat belt connector 50. The left opposing roller 40 and the right opposing roller 41 are respectively disposed on both sides of the lower hook-on body 30 and are used to roll along the support frame 70 or guide structures.

[0038] Specifically, the upper universal joint 10 includes a joint seat 11, a clamping member 12, and a ball bearing 14 disposed below the upper universal joint 10. The joint seat 11 forms an assembly area for the vertical connecting post 20 to pass through. The ball bearing 14 is disposed between the joint seat 11 and the upper mating area of ​​the vertical connecting post 20 or the lower mounting body 30, and is used to form a rolling support when the lower mounting body 30 rotates circumferentially relative to the upper universal joint 10. The clamping member 12 is used to pre-tighten the rotational mating position 13 between the joint seat 11, the ball bearing 14, and the vertical connecting post 20. The clamping member 12 can be a lock nut, a pressure cap, a riveting part, an elastic washer, a limiting ring, or other components capable of forming an axial pre-tightening effect.

[0039] The vertical connecting column 20 includes a column body 21 and an axial limiting part 22. The column body 21 passes through the adapter seat 11 and is connected to the lower hanging body 30. The axial limiting part 22 is used to restrict the axial disengagement of the column body 21 relative to the upper universal adapter part 10. The axial limiting part 22 can be a limiting step, a limiting ring, a riveting end, a nut, or a retaining spring.

[0040] The lower mounting body 30 includes a mounting hole 31, a roller mounting position 32, and a main body connecting hole 33. The mounting hole 31 is used for the seat belt connector 50 to pass through or be mounted. The roller mounting positions 32 are respectively located on both sides of the lower mounting body 30 and are used to install the left opposing roller 40 and the right opposing roller 41. The main body connecting hole 33 is used to connect with the vertical connecting post 20.

[0041] The left opposing roller 40 and the right opposing roller 41 can be mounted on their respective roller mounting positions 32 via roller shafts 42. An axial limiting member 43 can be provided at the end of the roller shaft 42 to restrict the axial movement of the corresponding roller along the roller shaft 42. The axial limiting member 43 can be a washer, nut, retaining ring, rivet end, or pressure cap.

[0042] like Figure 3 As shown, this embodiment also provides a snap-fit ​​assembly method for assembling the snap-fit ​​100 described above. The snap-fit ​​assembly method includes a roller assembly step, a vertical connecting column assembly step, an upper universal joint pre-tightening step, a rotational resistance detection step, a local jamming point judgment step, a pre-tightening adjustment and re-inspection step, an axial movement detection step, and a roller idle rotation detection step.

[0043] In the roller assembly step, the left opposing roller 40 and the right opposing roller 41 are respectively assembled into the roller mounting positions 32 on both sides of the lower mounting body 30. Specifically, the roller shaft 42 can first pass through the left opposing roller 40 and the corresponding roller mounting position 32, and then the left opposing roller 40 can be axially limited by the axial limiting member 43; similarly, the right opposing roller 41 is installed into the roller mounting position 32 on the other side. After assembly, both the left opposing roller 40 and the right opposing roller 41 can rotate relative to the lower mounting body 30.

[0044] In the vertical connecting column assembly step, the vertical connecting column 20 is assembled to the lower hanging body 30. Specifically, the column 21 can be inserted through the main body connecting hole 33, and the vertical connecting column 20 and the lower hanging body 30 can be fixedly or rotatably connected. When assembling the vertical connecting column 20, the middle area between the left opposing roller 40 and the right opposing roller 41 is used as the assembly reference, so that the center line of the vertical connecting column 20 passes through the middle area between the left opposing roller 40 and the right opposing roller 41.

[0045] In this embodiment, the central region can be understood as the area between the inner sides of the left opposing roller 40 and the right opposing roller 41, or as the middle region between the roller axes of the left opposing roller 40 and the right opposing roller 41. By making the center line of the vertical connecting post 20 pass through this central region, the probability of the buckle 100 swaying eccentrically when rotating around the vertical connecting post 20 can be reduced.

[0046] like Figure 4 As shown, in the pre-tightening step of the upper universal joint, the upper universal joint 10 is assembled to the vertical connecting post 20. Specifically, the ball bearing 14 is first arranged in the rolling support position below the upper universal joint 10, and then the post 21 of the vertical connecting post 20 is inserted into the adapter seat 11. The rotational engagement position 13 between the adapter seat 11, the ball bearing 14, and the vertical connecting post 20 is pre-tightened by the clamping member 12. After pre-tightening, the ball bearing 14 can reduce rotational friction when the lower mounting body 30 rotates circumferentially relative to the upper universal joint 10. After pre-tightening, the lower mounting body 30 can rotate circumferentially relative to the upper universal joint 10 via the vertical connecting post 20.

[0047] In one embodiment, when pre-tightening the upper universal joint 10, the clamping member 12 is first placed in the initial locking position. The initial locking position can be a position where the clamping member 12 continues to rotate by a preset angle after contacting the adapter seat 11, or a position where the clamping member 12 reaches a preset assembly height, or a position where the clamping member 12 prevents significant loosening between the vertical connecting column 20 and the adapter seat 11 but still allows rotation.

[0048] like Figure 5As shown, in the rotational resistance detection step, the lower mounting body 30 is driven to rotate one revolution around the vertical connecting column 20, and the resistance change state during the rotation is acquired. This rotation can be completed manually or using a rotational detection fixture 60. The rotational detection fixture 60 may include a resistance detection unit 61, which is used to acquire the rotational resistance value of the lower mounting body 30 during the rotation process. The resistance detection unit 61 may be a torque sensor, an elastic force measuring structure, or other detection structure capable of reflecting changes in rotational resistance.

[0049] like Figure 9 As shown, in one embodiment, the path of the lower attachment body 30 rotating one revolution is divided into multiple circumferential detection intervals 62. For example, the one-revolution path can be divided into four, six, eight, or more circumferential detection intervals 62, and the rotational resistance value within each circumferential detection interval 62 can be obtained. The rotational resistance value can be the maximum resistance value, average resistance value, or peak resistance value within the corresponding circumferential detection interval 62.

[0050] In the local jamming point judgment step, the presence of a local jamming point in the upper universal joint 10 is determined based on the resistance change state. Specifically, when the rotational resistance value within any circumferential detection interval 62 is greater than a preset resistance upper limit, or the difference in rotational resistance between adjacent circumferential detection intervals 62 is greater than a preset fluctuation threshold, it is determined that a local jamming point exists in the resistance change state.

[0051] In one embodiment, the local jamming point may also be caused by uneven pressure on the ball bearing 14, foreign objects at the rolling support location of the ball bearing 14, excessive axial preload on the ball bearing 14 caused by the clamping member 12, or misalignment of the contact position between the ball bearing 14 and the adapter seat 11. When a local jamming point is detected, the smoothness of the ball bearing 14 rotation, whether there are missing balls, foreign objects stuck in it, or local indentations can be checked, and the preload and re-inspection can be performed after cleaning or adjustment.

[0052] In one embodiment, the preset upper limit of resistance can be determined by the rotational resistance benchmark value and allowable deviation of qualified samples of the same specification. Specifically, for buckles 100 of the same specification, multiple qualified samples that have been manually inspected and confirmed to have no obvious looseness, no obvious jamming, and normal roller rotation are selected. The lower hanging body 30 of each qualified sample is driven to rotate around the corresponding vertical connecting post 20 for one revolution to obtain the rotational resistance value of each qualified sample, and the rotational resistance benchmark value is calculated. The rotational resistance benchmark value can be the average value of the rotational resistance of multiple qualified samples, or it can be the median value of the rotational resistance of multiple qualified samples.

[0053] The preset upper limit of resistance can be set as the sum of the rotational resistance reference value and the allowable deviation. The allowable deviation can be a fixed resistance value or a certain percentage of the rotational resistance reference value. For example, in a certain specification of buckle 100, if the average resistance of multiple qualified samples in one revolution is 15 N·mm and the allowable deviation is 5 N·mm, then 20 N·mm can be used as the preset upper limit of resistance; if a proportional method is used, 30% of the average resistance can also be used as the allowable deviation, thus obtaining the corresponding preset upper limit of resistance.

[0054] In one embodiment, the preset fluctuation threshold can be determined by the resistance difference between adjacent circumferential detection intervals 62 of qualified samples of the same specification and the allowable fluctuation ratio. Specifically, the qualified sample is rotated one revolution and divided into multiple circumferential detection intervals 62, the resistance difference between adjacent circumferential detection intervals 62 is calculated, and the average value or the maximum allowable value of the resistance difference between adjacent intervals in the qualified sample is used as the fluctuation reference value. The preset fluctuation threshold can be the sum of the fluctuation reference value and the allowable fluctuation deviation, or it can be a certain proportion of the rotational resistance reference value.

[0055] In one embodiment, the preset axial movement range can be determined based on the size of the buckle 100, its load-bearing capacity, and the allowable swing requirements of the seatbelt connector 50. For buckles 100 that are smaller in size, have a lower load-bearing capacity, and have a smaller swing amplitude of the seatbelt connector 50, a smaller axial movement range can be set; for buckles 100 that are larger in size, have a higher load-bearing capacity, or require the seatbelt connector 50 to swing within a certain range, a larger axial movement range can be set. The preset movement range is used to simultaneously prevent the upper universal joint 10 from being too loose or too tight.

[0056] The following description uses a specific type of buckle 100 as an example to illustrate the process of resistance detection during one rotation, local jamming point judgment, pre-tightening adjustment, and re-inspection. This buckle 100 includes an upper universal joint 10, a vertical connecting post 20, a lower hook-on body 30, a left opposing roller 40, and a right opposing roller 41. During testing, the lower hook-on body 30 is rotated one revolution around the vertical connecting post 20, and the rotation path is divided into eight circumferential detection intervals 62, sequentially labeled as the first interval to the eighth interval.

[0057] In this embodiment, the preset upper limit of resistance is set to 20 N·mm, and the preset fluctuation threshold is set to 6 N·mm. During the initial assembly inspection, the rotational resistance values ​​measured in each circumferential detection interval 62 are as follows: the first interval is 14 N·mm, the second interval is 15 N·mm, the third interval is 16 N·mm, the fourth interval is 27 N·mm, the fifth interval is 17 N·mm, the sixth interval is 16 N·mm, the seventh interval is 15 N·mm, and the eighth interval is 14 N·mm.

[0058] Based on the above test results, the rotational resistance differences between adjacent circumferential test intervals 62 are as follows: the difference between the first interval and the second interval is 1 N·mm, the difference between the second interval and the third interval is 1 N·mm, the difference between the third interval and the fourth interval is 11 N·mm, the difference between the fourth interval and the fifth interval is 10 N·mm, the difference between the fifth interval and the sixth interval is 1 N·mm, the difference between the sixth interval and the seventh interval is 1 N·mm, the difference between the seventh interval and the eighth interval is 1 N·mm, and the difference between the eighth interval and the first interval is 0 N·mm.

[0059] Since the rotational resistance value of 27 N·mm in the fourth interval is greater than the preset resistance upper limit of 20 N·mm, and the difference between the third and fourth intervals of 11 N·mm and the difference between the fourth and fifth intervals of 10 N·mm are both greater than the preset fluctuation threshold of 6 N·mm, it is determined that there is a local jamming point in the circumferential position corresponding to the fourth interval of the upper universal adapter 10.

[0060] For this local jamming point, the assembly personnel loosened the clamping member 12 at a small angle and checked whether there were burrs, local indentations, or foreign objects at the rotational engagement position 13 between the adapter 11 and the vertical connecting column 20. If a slight burr was found at the rotational engagement position 13, the burr was cleaned and the clamping member 12 was readjusted to a new pre-tightened state.

[0061] After adjustment, the lower mounting body 30 is driven to rotate around the vertical connecting column 20 for a re-inspection. During the re-inspection, the rotational resistance values ​​measured in each circumferential detection interval 62 are as follows: the first interval is 14 N·mm, the second interval is 15 N·mm, the third interval is 16 N·mm, the fourth interval is 17 N·mm, the fifth interval is 16 N·mm, the sixth interval is 16 N·mm, the seventh interval is 15 N·mm, and the eighth interval is 14 N·mm.

[0062] In the re-inspection results, the rotational resistance value within any circumferential detection interval 62 did not exceed the preset resistance upper limit of 20 N·mm, and the maximum rotational resistance difference between adjacent circumferential detection intervals 62 was 2 N·mm, which did not exceed the preset fluctuation threshold of 6 N·mm. Therefore, it was determined that the resistance change state met the preset continuous rotation condition. At this point, axial movement detection and roller idle rotation detection can continue.

[0063] In this embodiment, the preset axial movement range is set to 0.1mm to 0.5mm. The axial movement of the vertical connecting column 20 relative to the upper universal joint 10 is detected by the axial movement detection component 63. The measured axial movement is 0.3mm, which is within the preset axial movement range. Therefore, it is determined that the axial movement state meets the preset axial movement condition.

[0064] Furthermore, the left opposing roller 40 and the right opposing roller 41 were driven to idle. The test results showed that the left opposing roller 40 could rotate continuously without obvious scraping noise, and the right opposing roller 41 could rotate continuously without obvious wobble. The difference in their idle states did not exceed the preset difference range. Therefore, it was determined that both the left opposing roller 40 and the right opposing roller 41 met the preset idle conditions. At this point, the buckle 100 of this specification was successfully assembled.

[0065] To facilitate assembly personnel in determining adjustment actions based on inspection results, this embodiment also provides a correspondence between inspection results and adjustment actions. This correspondence can be part of the assembly process document or incorporated into the operating procedures of the inspection tooling.

[0066] When the rotational resistance values ​​of multiple circumferential detection intervals 62 are all too high during one rotation, and the axial movement of the vertical connecting column 20 relative to the upper universal joint 10 is less than the lower limit of the preset movement range, it is determined that the upper universal joint 10 may have excessive overall pre-tightening. In this case, the pre-tightening degree can be reduced, for example, by loosening the clamping member 12 at a small angle, reducing the pressing depth of the pressure cap, or reducing the clamping amount of the gasket.

[0067] When the rotational resistance during one revolution is generally low, but the axial movement of the vertical connecting column 20 relative to the upper universal joint 10 exceeds the upper limit of the preset movement range, it is determined that the upper universal joint 10 may have insufficient pre-tightening. In this case, the pre-tightening degree can be increased, for example, by locking the clamping member 12 at a small angle, increasing the pressure of the gasket, or increasing the pressing depth of the pressure cap.

[0068] When the rotational resistance value of only one circumferential detection interval 62 or a few adjacent circumferential detection intervals 62 increases significantly, while the rotational resistance values ​​of other circumferential detection intervals 62 are within the normal range, it is determined that the upper universal joint 10 may have a local jamming point. At this time, it is possible to check whether there are burrs, local indentations, eccentric assembly, or foreign objects at the rotational fit position 13 between the adapter 11 and the vertical connecting column 20, and re-tighten and re-inspect after cleaning or repair.

[0069] If no local jamming occurs during one rotation and the axial movement meets the preset movement conditions, but the left opposing roller 40 or the right opposing roller 41 fails to rotate properly without load, it is determined that the corresponding roller may have an axial limiting abnormality. In this case, the axial limiting component 43 at the end of the corresponding roller shaft 42 can be adjusted, for example, by adjusting the position of the shim, nut, retaining ring, pressure cap, or riveted end, so that the corresponding roller is neither axially loose nor stiff due to excessive axial compression.

[0070] When no local jamming occurs during one rotation, the axial movement is within the preset range, and both the left opposing roller 40 and the right opposing roller 41 meet the preset idling conditions, the buckle 100 is deemed to be assembled successfully. This judgment method establishes a combined judgment relationship between rotational resistance, axial movement, and roller idling, avoiding the need to judge whether the buckle 100 is qualified based on a single indicator.

[0071] like Figure 10 As shown, in another embodiment, the rotary detection fixture 60 can be a common manual detection fixture, without relying on complex automated detection equipment. The rotary detection fixture 60 includes a positioning base 65, a rotary handle 66, an elastic force measuring element 67, and an angle marking part 68. The positioning base 65 is used to fix the upper universal joint 10 or support the joint 11. The rotary handle 66 is used to drive the lower hanging body 30 to rotate around the vertical connecting column 20. The elastic force measuring element 67 is used to display or reflect the force applied to the rotary handle 66. The angle marking part 68 is used to mark different circumferential detection intervals 62 during one rotation of the lower hanging body 30.

[0072] When using the rotary detection fixture 60, first install the buckle 100 on the positioning seat 65 to keep the upper universal joint 10 relatively fixed, and then connect the rotary handle 66 to the lower hanging body 30. The operator applies force with a constant handle length to drive the lower hanging body 30 to rotate one revolution around the vertical connecting column 20, and reads the force readings in different circumferential detection intervals 62 through the elastic force measuring element 67. Since the length of the rotary handle 66 remains constant, the readings of the elastic force measuring element 67 can reflect the changes in rotational resistance.

[0073] In one embodiment, the effective length of the rotary handle 66 is fixed, and the operator slowly pushes the rotary handle 66 in the same manner within each circumferential detection interval 62. If the reading of the elastic force measuring element 67 in a certain circumferential detection interval 62 is significantly higher than in other intervals, or if a significantly greater pushing force is required to pass through that interval, it is determined that there may be a local jamming point in that interval. Using this manual inspection fixture, even if a torque sensor is not installed on the production site, a semi-quantitative judgment of the change in rotational resistance can be made.

[0074] In another embodiment, the angle marking unit 68 can divide the circumferential rotation path into eight circumferential detection intervals 62. The operator sequentially records the readings of the elastic force measuring element 67 corresponding to each circumferential detection interval 62, and then determines whether there are local jamming points based on the preset resistance upper limit and preset fluctuation threshold. This method can reduce the difference in detection results caused by relying solely on tactile judgment and improve the assembly consistency of the same batch of buckles 100.

[0075] like Figure 6 As shown, in the axial movement detection step, after determining whether there are any local jamming points in the upper universal joint 10, the axial movement state of the vertical connecting column 20 relative to the upper universal joint 10 is also checked. Specifically, the axial movement of the vertical connecting column 20 relative to the upper universal joint 10 can be detected by pulling or pushing the lower hanging body 30 along the axial direction of the vertical connecting column 20 using the axial movement detection component 63.

[0076] When the axial movement is too large, it indicates that the preload of the upper universal joint 10 relative to the vertical connecting post 20 may be insufficient; when the axial movement is too small and the rotational resistance is too large, it indicates that the preload of the upper universal joint 10 relative to the vertical connecting post 20 may be too large. Therefore, when the axial movement does not meet the preset movement conditions, the preload of the upper universal joint 10 relative to the vertical connecting post 20 should be adjusted.

[0077] The preset movement condition may include the axial movement of the vertical connecting column 20 relative to the upper universal joint 10 being within a preset movement range. The preset movement range can be set according to the size, material, load-bearing requirements, and safety requirements of the buckle 100. This inspection can prevent the upper universal joint 10 from becoming too loose by using only smooth rotation as a passing standard.

[0078] like Figure 7 As shown, in the roller idle detection step, after the resistance change state meets the preset continuous rotation condition, the left opposing roller 40 and the right opposing roller 41 are driven to idle relative to the lower hanging body 30, and the preset idle condition is determined based on the idle state of the left opposing roller 40 and the right opposing roller 41. Specifically, the left opposing roller 40 and the right opposing roller 41 can be rotated by moving or driving the roller idle detection component 64.

[0079] The preset idling conditions may include: the rollers can rotate continuously, there is no obvious scraping sound, there is no obvious wobble, the rotational resistance does not exceed a preset range, or the difference in idling state between the left opposing roller 40 and the right opposing roller 41 does not exceed a preset difference range. When either opposing roller does not meet the preset idling conditions, the axial limit state of the opposing rollers is adjusted and the idling check is performed again.

[0080] Specifically, when the left opposing roller 40 becomes stiff during rotation, the axial limiting member 43 at the end of the corresponding roller shaft 42 can be adjusted to prevent the left opposing roller 40 from becoming axially loose or stiff due to excessive axial compression. When the right opposing roller 41 has a similar problem, the corresponding axial limiting member 43 can be adjusted in the same way. This ensures that the left opposing roller 40 and the right opposing roller 41 roll stably during seatbelt traction.

[0081] like Figure 8 As shown, in actual use, the seat belt connector 50 is connected to the hook-up hole 31 of the lower hook-up body 30, and the buckle 100 cooperates with the support frame 70 or other guide structure through the upper universal joint 10. When the child walks, moves sideways, turns around, or suddenly stops, the seat belt connector 50 applies traction force in different directions to the lower hook-up body 30. Since the upper universal joint 10 has been adjusted to meet the preset continuous rotation conditions through the above assembly method, the lower hook-up body 30 can smoothly rotate circumferentially relative to the upper universal joint 10 through the vertical connecting post 20, thereby timely aligning when the traction direction changes.

[0082] Meanwhile, the left opposing roller 40 and the right opposing roller 41 can roll along the support frame 70 or the guide structure. Since the idling state of the left opposing roller 40 and the right opposing roller 41 has been checked during the assembly process, and the rollers that do not meet the preset idling conditions have been axially limited, the probability of the rollers being assembled too tightly, too loosely, or with excessive resistance on one side can be reduced.

[0083] In this embodiment, the pre-tightening state of the upper universal joint 10 is not determined by a single locking action, but rather by the combined effects of the resistance change during one rotation, the axial movement, and the free-spinning state of the left and right opposing rollers. This avoids problems such as the upper universal joint 10 being too tight leading to localized jamming, the upper universal joint 10 being too loose leading to wobbling, and abnormal axial positioning of the rollers leading to increased sliding resistance.

[0084] In another embodiment, the clamping member 12 can be an adjustable structure or a structure that can be adjusted after a single press-fit. When there are local jamming points in the resistance change state, the preload can be changed by adjusting the clamping member 12, replacing the shims, adjusting the rotational fit position 13, or re-press-fitting.

[0085] In another embodiment, the left opposing roller 40 and the right opposing roller 41 can be rollers with arc-shaped guide surfaces on their outer periphery, or they can be rollers adapted to the shape of the support frame 70. The specific shape of the rollers does not affect the core solution of the present invention to determine the pre-tightening state of the upper universal joint 10 through the assembly method.

[0086] The technical features of the embodiments described above can be combined arbitrarily. For the sake of brevity, not all possible combinations in the above embodiments have been described one by one. However, as long as the combination of these technical features does not contradict each other, it should be considered to fall within the scope of this specification.

[0087] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of protection of the present invention. For those skilled in the art, various modifications and improvements can be made without departing from the concept of the present invention, and all such modifications and improvements should fall within the scope of protection of the present invention.

Claims

1. A buckle assembly method for assembling a buckle used for seat belt traction, the buckle comprising an upper universal joint, a vertical connecting post, a lower hook-up body, and left and right opposing rollers disposed on both sides of the lower hook-up body, characterized in that, The buckle assembly method includes: The left opposing roller and the right opposing roller are assembled on both sides of the lower hanging body, and the vertical connecting column is assembled on the lower hanging body; The upper universal joint is assembled onto the vertical connecting column, and the upper universal joint is pre-tightened so that the lower hanging body can rotate circumferentially relative to the upper universal joint through the vertical connecting column. The lower hanging body is driven to rotate around the vertical connecting column for one revolution, and the path of one revolution is divided into multiple circumferential detection intervals, and the rotational resistance value in each circumferential detection interval is obtained respectively. Based on whether the rotational resistance value within any of the circumferential detection intervals is greater than a preset resistance upper limit, or whether the difference in rotational resistance between adjacent circumferential detection intervals is greater than a preset fluctuation threshold, it is determined whether there is a local jamming point in the upper universal joint. When the aforementioned local jamming point exists, adjust the pre-tightening degree of the upper universal joint relative to the vertical connecting column, and drive the lower hanging body to rotate one revolution again for re-inspection until the resistance change state during the rotation of the lower hanging body one revolution meets the preset continuous rotation condition.

2. The snap-fit ​​assembly method according to claim 1, characterized in that, After assembling the left and right opposing rollers on both sides of the lower hanging body, the middle area between the left and right opposing rollers is used as the assembly reference for the vertical connecting column, so that the center line of the vertical connecting column passes through the middle area between the left and right opposing rollers.

3. The snap-fit ​​assembly method according to claim 1, characterized in that, The upper universal adapter includes an adapter seat and a clamping member. When the upper universal adapter is assembled onto the vertical connecting column, the vertical connecting column passes through the adapter seat, and the clamping member pre-tightens the rotational fit position between the adapter seat and the vertical connecting column.

4. The snap-fit ​​assembly method according to claim 3, characterized in that, When pre-tightening the upper universal joint, first place the clamping member in the initial locking position, and then drive the lower hanging body to perform rotation detection; when the resistance change state does not meet the preset continuous rotation condition, the position of the clamping member is adjusted incrementally.

5. The snap-fit ​​assembly method according to claim 1, characterized in that, The preset upper limit of resistance is determined by the reference value of the rotational resistance of qualified samples of the same specification and the allowable deviation, and the preset fluctuation threshold is determined by the resistance difference between adjacent circumferential detection intervals of qualified samples of the same specification and the allowable fluctuation ratio.

6. The snap-fit ​​assembly method according to claim 1, characterized in that, After determining whether there are any local jamming points in the upper universal joint, the axial movement of the vertical connecting column relative to the upper universal joint is also checked; when the axial movement does not meet the preset movement conditions, the pre-tightening degree of the upper universal joint relative to the vertical connecting column is adjusted.

7. The snap-fit ​​assembly method according to claim 6, characterized in that, The preset continuous rotation condition includes that no local jamming point occurs during one rotation of the lower hanging body, and the preset axial movement condition includes that the axial movement of the vertical connecting column relative to the upper universal joint is within the preset axial movement range.

8. The snap-fit ​​assembly method according to claim 7, characterized in that, The preset range of movement is determined by the size of the buckle, the load-bearing capacity, and the allowable swing requirements of the seat belt connector.

9. The snap-fit ​​assembly method according to claim 1, characterized in that, After the resistance change state meets the preset continuous rotation condition, the left and right opposing rollers are driven to rotate relative to the lower hanging body. The rotation state of the left and right opposing rollers is used to determine whether the preset rotation condition is met. If either opposing roller does not meet the preset rotation condition, the axial limit state of the opposing rollers is adjusted and the rotation check is performed again.

10. A buckle, characterized in that, include: The upper universal joint has a ball bearing installed below it. A vertical connecting column is rotatably connected to the upper universal joint, and the ball bearing is disposed at the rotatable engagement position between the upper universal joint and the vertical connecting column. The lower mounting body is connected to the vertical connecting post and has mounting holes located below the opposing left and right rollers. The lower mounting body can rotate circumferentially relative to the upper universal joint via the vertical connecting post and the ball bearings. A left opposing roller and a right opposing roller are respectively disposed on both sides of the lower hanging body; The pre-tightening degree of the upper universal joint relative to the vertical connecting post is determined by the snap-fit ​​assembly method as described in any one of claims 1 to 9.

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