A bolt axial force test tool

Abstract

The utility model discloses a bolt axial force test frock belongs to axial force measuring device technical field, and it aims at solving the problem of high cost, precision is influenced or weakens bolt strength of existing outside pasting formula, internal inlay formula axial force bolt. It includes bolt mounting assembly and test mechanism: bolt mounting assembly contains truncated cone, bolt fixer and bolt lock, and the truncated cone sets up test bolt big head end, and the three cooperation clamps fastens test bolt, and test mechanism contains bottom plate, triangular support, mounting plate, bolt support and dynamometer, and the triangular support and bolt support are fixedly connected on the bottom plate, and the mounting plate is used for placing test wheel, and one end of bolt support is connected with dynamometer, and the other end is detachably connected with bolt mounting assembly, and test bolt passes through mounting plate corresponding wheel bolt mounting position. When testing, the dynamometer directly displays the axial force, and the torque and the angle can also be recorded. The frock does not need to transform the bolt, and the test is accurate and convenient, reduces the cost and improves the efficiency.

Description

Technical Field

[0001] This utility model belongs to the technical field of axial force measuring devices, and in particular relates to a bolt axial force testing fixture. Background Technology

[0002] Repeated tightening axial force testing of automotive wheel hub bolts is a crucial experiment for evaluating the bolts' ability to maintain preload (axial force) after multiple installations and removals. This test effectively prevents the risk of loosening or breakage of wheel hub bolts due to preload decay, directly impacting vehicle safety and playing a vital role in ensuring vehicle safety and reliability. As the automotive industry continues to raise its performance requirements for components, more and more OEMs and component suppliers are incorporating repeated tightening axial force testing of wheel hub bolts into their mandatory quality inspection processes, placing higher demands on the efficiency, cost, and accuracy of testing solutions.

[0003] Currently, the industry mostly relies on axial force bolts for repeated tightening axial force testing, and their manufacturing mainly uses two technical solutions: external adhesive type and internal embedded type.

[0004] External bonding method: The technical principle is to directly attach the strain gauge to the outer surface of the bolt, and indirectly obtain the axial force through strain measurement. Although this method has the advantages of relatively simple operation and low cost, it has obvious limitations: First, for bolts with limited space, such as wheel fasteners, there is a problem of insufficient bonding area for the strain gauge; second, the wiring connection is difficult, and when the bolt is a rotating part, the wires are prone to tangling or damage; third, the measurement accuracy is significantly affected by the surface treatment quality of the bolt, and it is difficult to guarantee data stability; fourth, it is not suitable for long-term monitoring or testing under harsh conditions such as vibration and dust, and its applicable scenarios are limited.

[0005] The internal embedded solution: Its technical principle is to machine a precision channel along the bolt's axis and embed a miniature force sensor to directly measure the axial force. Although this solution can achieve high measurement accuracy and is unaffected by external environmental interference, it also has unavoidable drawbacks: First, the processing technology is complex and requires specialized equipment and precision machining technology; second, the modification cost of a single bolt can be as high as thousands of yuan, resulting in high testing costs; third, the production cycle is long and cannot meet the needs of rapid batch testing; fourth, the machining of the axial channel will weaken the bolt body strength to a certain extent, which may affect the bolt's stress state during testing and thus interfere with the authenticity of the test results.

[0006] In summary, existing axial force bolt testing solutions either suffer from high costs, long cycles, and damaged bolt strength due to structural modifications, or have unstable accuracy and narrow applicability due to limitations in measurement methods. None of these solutions can simultaneously meet the automotive industry's requirements for "high efficiency, low cost, high precision, and strong adaptability" in wheel hub bolt axial force testing. There is an urgent need for a new type of testing fixture to solve the above-mentioned technical pain points. Utility Model Content

[0007] To solve the above-mentioned technical problems, this utility model proposes a bolt axial force testing fixture.

[0008] To achieve the above objectives, this utility model provides a bolt axial force testing fixture, comprising:

[0009] A bolt mounting assembly includes a truncated cone, a bolt retainer, and a bolt locking device. The truncated cone is used to fit around the outside of the large end of a test bolt. The bolt retainer and the bolt locking device are threaded together. One end of the test bolt fitted with the truncated cone is located between the bolt retainer and the bolt locking device and is clamped and fastened. The other end extends out of the end face of the bolt retainer.

[0010] The testing mechanism includes a base plate on which a mounting plate is fixedly connected via a triangular bracket. The mounting plate is used to place a test wheel. The testing mechanism also includes a bolt bracket, one end of which passes through the base plate and is connected to a force gauge, and the other end is detachably connected to the bolt mounting assembly. The test bolt passes through the mounting plate and is positioned at the bolt mounting location of the test wheel.

[0011] Optionally, the top of the bolt locking device abuts against the large end of the test bolt, the large end of the test bolt abuts against the truncated cone, and the truncated cone abuts against the inner bottom surface of the bolt retainer, so that the test bolt and the truncated cone are engaged between the bolt retainer and the bolt locking device.

[0012] Optionally, the bolt retainer is provided with a square platform at one end near the bolt locking device.

[0013] Optionally, it also includes a bolt fastening base, the bolt fastening base having a central hole at the top, and a recessed platform corresponding to the square platform at the top of the central hole; the bolt fastener is inverted and placed in the central hole, and the square platform is aligned with the recessed platform, and the bolt tightener can be rotated to lock the internal test bolt.

[0014] Optionally, the top of the triangular bracket is fixed with several positioning pins, and the mounting plate is provided with positioning holes corresponding to the positioning pins.

[0015] Optionally, a positioning block is fixedly attached to the mounting plate, the positioning block being used to limit the movement of the test wheel.

[0016] Optionally, the bolt bracket has a mounting groove on its side, and the top of the mounting groove has an embedding groove corresponding to the bolt fastener. The bolt fastener is embedded in the embedding groove through the top of the mounting groove. The outer side of the square platform has four threaded holes. A first bolt is provided on the outer side of the bolt bracket at the position corresponding to the threaded holes, passing through the bolt bracket and threadedly connected to the threaded holes, thereby connecting the bolt bracket and the bolt fastener.

[0017] Optionally, a second bolt is provided at the bottom of the mounting groove, penetrating the bottom surface of the bolt bracket and the base plate to connect with the force measuring instrument.

[0018] Compared with the prior art, the present invention has the following advantages and technical effects:

[0019] The design of the bolt mounting assembly, which uses a truncated cone to hold the large end of the test bolt and a threaded engagement between the bolt retainer and bolt locking device to clamp and secure the test bolt, eliminates the need to modify the test bolt by embedding internal sensors or attaching external strain gauges. This avoids weakening the bolt's strength and completely solves the problems of complex and costly manufacturing processes for traditional internally embedded axial force bolts and the issues of easily tangled and damaged wiring and surface treatment quality affecting measurement accuracy for externally attached axial force bolts. Simultaneously, the base plate of the testing mechanism is fixed to the mounting plate via a triangular bracket to stably support the test wheel. One end of the bolt bracket is detachably connected to the bolt mounting assembly, and the other end passes through the base plate to connect to the force gauge. The structure of the test bolt passing through the mounting plate corresponds to the bolt mounting position on the test wheel, accurately simulating the actual bolt installation conditions and ensuring the authenticity of the test data. The bolt axial force can also be directly read from the force gauge without strain value conversion, significantly improving testing convenience and data accuracy. Furthermore, the detachable connection design between the bolt bracket and the bolt mounting assembly facilitates the assembly, disassembly, and maintenance of the tooling, further improving testing efficiency. Attached Figure Description

[0020] The accompanying drawings, which form part of this utility model, are used to provide a further understanding of the utility model. The embodiments of the utility model and their descriptions are used to explain the utility model and do not constitute an undue limitation of the utility model. In the drawings:

[0021] Figure 1 This is a schematic diagram of the bolt axial force testing fixture of this utility model;

[0022] Figure 2 This is a schematic diagram of the bolt mounting assembly structure in this utility model;

[0023] Figure 3 This is an exploded view of the bolt mounting assembly in this utility model;

[0024] Figure 4This is a schematic diagram of the installation of the test bolt and the truncated cone in this utility model;

[0025] Figure 5 This is a schematic diagram of the bolt fastening base and bolt fixing device structure in this utility model;

[0026] Figure 6 This is a schematic diagram of the bolt axial force testing fixture structure of this utility model, which is equipped with a test wheel.

[0027] In the diagram: 1. Frustum cone; 2. Test bolt; 3. Bolt retainer; 4. Bolt locking device; 5. Bolt fastening base; 6. Positioning block; 7. Positioning pin; 8. Mounting plate; 9. Bolt bracket; 10. Triangular bracket; 11. Base plate; 12. Force gauge; 13. Test wheel. Detailed Implementation

[0028] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0029] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] Reference Figures 1 to 6 As shown, this embodiment provides a bolt axial force testing fixture, including:

[0031] The bolt mounting assembly includes a truncated cone 1, a bolt retainer 3, and a bolt locking device 4. The truncated cone 1 is used to fit around the outside of the large end of the test bolt 2. The bolt retainer 3 and the bolt locking device 4 are threaded together. One end of the test bolt 2, which is fitted with the truncated cone 1, is located between the bolt retainer 3 and the bolt locking device 4 and is clamped and fastened. The other end extends out of the end face of the bolt retainer 3.

[0032] The testing mechanism includes a base plate 11, on which a mounting plate 8 is fixedly connected via a triangular bracket 10. The mounting plate 8 is used to place the test wheel 13. The testing mechanism also includes a bolt bracket 9, one end of which passes through the base plate 11 and is connected to a force gauge 12, and the other end is detachably connected to a bolt mounting assembly. The test bolt 2 passes through the mounting plate 8 and is set at the bolt mounting position of the test wheel 13.

[0033] By using the design of the bolt mounting assembly, where the truncated cone 1 houses the large end of the test bolt 2, and the bolt retainer 3 and bolt locking device 4 are threadedly engaged to clamp and secure the test bolt 2, there is no need to modify the test bolt 2 by embedding sensors internally or attaching strain gauges externally. This avoids weakening the bolt body strength due to modifications and completely solves the problems of complex and costly processing of traditional internally embedded axial force bolts and the easy entanglement and damage of wiring and the influence of surface treatment quality on measurement accuracy of externally attached axial force bolts. At the same time, the base plate 11 in the testing mechanism is fixed to the mounting plate 8 by the triangular bracket 10 for stability. The test wheel 13 is supported by a bolt bracket 9, one end of which is detachably connected to the bolt mounting assembly, and the other end passes through the base plate 11 and connects to the force gauge 12. The test bolt 2 passes through the mounting plate 8 corresponding to the bolt mounting position of the test wheel 13. This structure can accurately simulate the actual installation conditions of the bolt, ensuring the authenticity of the test data. The bolt axial force can also be read directly through the force gauge 12 without the need for strain value conversion, which greatly improves the convenience of testing and the accuracy of data. In addition, the detachable connection design between the bolt bracket 9 and the bolt mounting assembly also facilitates the assembly, disassembly and maintenance of the tooling and components, further improving the testing efficiency.

[0034] In some alternative implementations, the top of the bolt locking device 4 abuts against the large end of the test bolt 2, the large end of the test bolt 2 abuts against the truncated cone 1, and the truncated cone 1 abuts against the inner bottom surface of the bolt retainer 3, so that the test bolt 2 and the truncated cone 1 are engaged between the bolt retainer 3 and the bolt locking device 4.

[0035] The interlocking structure provides precise axial positioning and secure clamping for the test bolt 2, effectively preventing radial displacement or loosening during testing. This ensures that the bolt force is always transmitted axially, guaranteeing the accuracy of axial force test data from a structural perspective. It solves the measurement deviation problem that may occur due to unstable bolt positioning in traditional external adhesive methods. At the same time, this structure eliminates the need to modify the test bolt 2 by drilling holes to embed sensors or attaching strain gauges externally. It fully preserves the strength of the test bolt 2, avoids the drawback of weakening bolt strength in internal embedding methods, and saves modification procedures and costs. Furthermore, assembly can be completed simply by interlocking, making it convenient to operate and further improving the practicality and testing efficiency of the testing fixture.

[0036] In some alternative implementations, the bolt retainer 3 is provided with a square platform at one end near the bolt locking device 4.

[0037] From a structural fit perspective, the square platform can be precisely matched with the corresponding recessed platform opened in the center hole at the top of the bolt fastening base 5 (described later), and can also be stably engaged with the embedded groove at the top of the mounting groove of the bolt bracket 9 (described later). This provides a clear positioning benchmark for the assembly of the bolt fastener 3 with the bolt fastening base 5 and the bolt bracket 9, avoiding offset or misalignment during assembly, and greatly improving the docking efficiency and assembly accuracy of the tooling components.

[0038] In some alternative implementations, a bolt fastening base 5 is also included, with a central hole at the top of the bolt fastening base 5 and a recess at the top of the central hole corresponding to the square platform; the bolt retainer 3 is inverted and placed in the central hole, with the square platform corresponding to the recess, and the bolt locking device 4 can be rotated to lock the internal test bolt 2.

[0039] The above structure has significant advantages and technical effects in terms of precise positioning, stable locking, and simplified operation: Firstly, the central hole provides an axial installation reference for the bolt retainer 3, while the concave platform precisely matches the square platform of the bolt retainer 3, effectively limiting the circumferential rotation of the bolt retainer 3 during the locking process. This avoids tightening failure caused by the bolt retainer 3 rotating synchronously with the bolt locking device 4, ensuring that when torque is applied to the bolt locking device 4, the torque can be completely converted into axial clamping force on the test bolt 2, ensuring that the test bolt 2 is stably clamped. Secondly, this structure does not require additional tools to fix the bolt retainer 3; positioning can be achieved simply by the cooperation of the concave and convex platforms. The locking operation can be completed by rotating the bolt locking device 4, simplifying the tightening steps in the tooling assembly and shortening the test preparation time. At the same time, the bolt fastening base 5 has a simple structure that does not require complex processes and does not increase additional costs, which is highly consistent with the core objective of this tooling: "reducing the manufacturing process and cost of axial force bolts and improving test efficiency."

[0040] In some alternative implementations, the top of the tripod bracket 10 is fixed with several positioning pins 7, and the mounting plate 8 has positioning holes corresponding to the positioning pins 7.

[0041] From an assembly and positioning perspective, the corresponding fit between the positioning pin 7 and the positioning hole provides a clear and unique benchmark for the installation of the mounting plate 8 on the triangular bracket 10. This eliminates the need for repeated adjustments to the mounting plate 8, enabling rapid and accurate alignment and significantly shortening the docking time between the mounting plate 8 and the triangular bracket 10 during tooling assembly. From a testing stability perspective, this structure effectively limits lateral shift or wobbling of the mounting plate 8 during testing, ensuring that the test wheel 13 placed on the mounting plate 8 remains in the preset test position. This allows for precise alignment of the bolt mounting position of the test wheel 13 with the test bolt 2 penetrating the mounting plate 8, simulating the actual alignment conditions of the bolt during vehicle installation. This prevents the test bolt 2 from deviating from its axial direction due to mounting plate 8 offset, solving the problem of inaccurate component alignment affecting axial force measurement accuracy in traditional testing. Furthermore, this positioning structure is simple in design, requiring only the plug-in fit between the positioning pin 7 and the positioning hole for installation and disassembly, eliminating the need for complex connection procedures. This reduces tooling processing difficulty and cost while further enhancing the overall ease of operation of the tooling.

[0042] In some alternative implementations, a positioning block 6 is fixed to the mounting plate 8, which is used to limit the test wheel 13.

[0043] The positioning block 6 can directly provide physical restraint for the test wheel 13, preventing lateral displacement or rotation of the test wheel 13 during bolt tightening or force measurement. This ensures that the bolt mounting position of the test wheel 13 is always precisely aligned with the test bolt 2 penetrating the mounting plate 8, perfectly simulating the alignment condition of the bolt during actual vehicle installation. This fundamentally solves the problem of the test bolt 2's force direction deviating from the axial direction due to wheel offset, thus causing deviation in axial force measurement and ensuring the accuracy of the force gauge 12 readings. At the same time, the positioning block 6 eliminates the need for repeated adjustments to the position of the test wheel 13 before testing. Precise positioning can be achieved simply by placing the test wheel 13 against the positioning block 6, significantly shortening the test preparation time and improving test efficiency. Furthermore, this structure only requires the positioning block 6 to be fixed on the mounting plate 8 to achieve its function. The manufacturing process is simple, requiring no additional complex parts and not increasing the overall cost of the tooling, further enhancing the practicality and economy of the tooling.

[0044] In some alternative implementations, the bolt bracket 9 has a mounting groove on its side, and the top of the mounting groove has an embedding groove corresponding to the bolt fastener 3. The bolt fastener 3 is embedded into the embedding groove through the top of the mounting groove. The outer side of the square platform has four threaded holes. The outer side of the bolt bracket 9 has a first bolt that passes through the bolt bracket 9 and is threadedly connected to the threaded holes, thereby connecting the bolt bracket 9 and the bolt fastener 3.

[0045] The design of the mounting slot and the embedding slot provides a clear installation path and precise positioning reference for the bolt fastener 3. The bolt fastener 3 can be directly embedded into the embedding slot along the mounting slot without repeated alignment adjustments, greatly simplifying the assembly process of the bolt fastener 3 and the bolt bracket 9 and improving test efficiency. In addition, the four threaded holes of the square platform and the cooperation with the first bolt enable a rigid connection between the bolt fastener 3 and the bolt bracket 9, ensuring that the axial force of the test bolt 2 can be stably transmitted to the force gauge 12 below. This solves the problem of axial force measurement deviation that may be caused by unstable component connections in traditional tests, ensuring the accuracy of the force gauge 12 readings. Furthermore, this detachable bolt connection method facilitates subsequent individual maintenance and replacement of the bolt fastener 3 or the bolt bracket 9 without disassembling the entire tooling, reducing maintenance costs and time, and without increasing the processing complexity of the tooling, thus avoiding additional cost investment.

[0046] In some alternative implementations, a second bolt is provided at the bottom of the mounting slot, penetrating the bottom surface of the bolt bracket 9 and the base plate 11 to connect with the force gauge 12.

[0047] The second bolt achieves a rigid connection with the force measuring instrument 12 by passing through the bottom surface of the bolt bracket 9 and the base plate 11. This can establish a stable force transmission path, ensuring that the axial force on the test bolt 2 can be transmitted to the force measuring instrument 12 without loss, avoiding force attenuation caused by loose connection or gap, and thus ensuring the authenticity and accuracy of the reading of the force measuring instrument 12. This solves the error problem that may occur when traditional axial force bolts need to undergo strain calculation.

[0048] Any aspects of this utility model that are not detailed herein are conventional technical means known to those skilled in the art.

[0049] In the description of this utility model, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or 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 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. Therefore, they should not be construed as limitations on this utility model.

[0050] The embodiments described above are merely preferred embodiments of the present utility model and are not intended to limit the scope of the present utility model. Various modifications and improvements made to the technical solutions of the present utility model by those skilled in the art without departing from the spirit of the present utility model should fall within the protection scope defined by the claims of the present utility model.

Claims

1. A bolt axial force testing fixture, characterized in that, include: The bolt mounting assembly includes a truncated cone (1), a bolt retainer (3), and a bolt locking device (4). The truncated cone (1) is used to fit around the large end of the test bolt (2). The bolt retainer (3) and the bolt locking device (4) are threaded together. One end of the test bolt (2) fitted with the truncated cone (1) is located between the bolt retainer (3) and the bolt locking device (4) and is clamped and fastened. The other end extends out of the end face of the bolt retainer (3). The testing mechanism includes a base plate (11), on which a mounting plate (8) is fixedly connected by a triangular bracket (10). The mounting plate (8) is used to place a test wheel (13). The testing mechanism also includes a bolt bracket (9). One end of the bolt bracket (9) passes through the base plate (11) and is connected to a force gauge (12). The other end is detachably connected to the bolt mounting assembly. The test bolt (2) passes through the mounting plate (8) and is set at the bolt mounting position of the test wheel (13).

2. The bolt axial force testing fixture according to claim 1, characterized in that, The top of the bolt locking device (4) abuts against the large end of the test bolt (2), the large end of the test bolt (2) abuts against the truncated cone (1), and the truncated cone (1) abuts against the inner bottom surface of the bolt retainer (3), so that the test bolt (2) and the truncated cone (1) are locked between the bolt retainer (3) and the bolt locking device (4).

3. The bolt axial force testing fixture according to claim 2, characterized in that, The bolt fastener (3) has a square platform at one end near the bolt locking device (4).

4. The bolt axial force testing fixture according to claim 3, characterized in that, It also includes a bolt fastening base (5), the bolt fastening base (5) has a central hole at the top, and the central hole has a recessed platform corresponding to the square platform at the top; the bolt fastener (3) is inverted in the central hole and the square platform is aligned with the recessed platform, and the bolt locking device (4) can be rotated to lock the internal test bolt (2).

5. The bolt axial force testing fixture according to claim 1, characterized in that, The top of the triangular bracket (10) is fixed with several positioning pins (7), and the mounting plate (8) has positioning holes corresponding to the positioning pins (7).

6. The bolt axial force testing fixture according to claim 1, characterized in that, A positioning block (6) is fixedly connected to the mounting plate (8), and the positioning block (6) is used to limit the test wheel (13).

7. The bolt axial force testing fixture according to claim 3, characterized in that, The bolt bracket (9) has an installation groove on its side, and the top of the installation groove has an embedding groove corresponding to the bolt fastener (3). The bolt fastener (3) is embedded in the embedding groove through the top of the installation groove. The outer side of the square platform has four threaded holes. The outer side of the bolt bracket (9) is provided with a first bolt that passes through the bolt bracket (9) and is threadedly connected to the threaded holes, thereby connecting the bolt bracket (9) and the bolt fastener (3).

8. The bolt axial force testing fixture according to claim 7, characterized in that, The bottom of the mounting groove is provided with a second bolt that passes through the bottom surface of the bolt bracket (9) and the base plate (11) and connects to the force measuring instrument (12).

Images