Method for measuring torsion-tension relation and friction coefficient of single-sided installation fastener

Abstract

The invention discloses a method for measuring a torsion-tension relation and a friction coefficient of a single-side-mounted fastener, which can accurately measure data such as tightening torque T, pre-tightening force F, thread friction torque Tt, torsion angle and rotating speed of a single-side-mounted threaded fastener in the whole mounting process. Parameters such as a torque coefficient K, a thread friction coefficient [mu] t, a friction torque Tb (Tb = T-Tt) of a rotary supporting surface, a friction coefficient [mu] b of the supporting surface and the like can be calculated according to a related formula of a torsion-tension relation of thread fastening, and meanwhile, the problem of disassembly after installation is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of measurement of threaded fastener connections, and particularly relates to a method for measuring the torsional-tensile relationship and friction coefficient of single-sided installation fasteners. Background Art

[0002] A typical threaded fastener fastening connection refers to a connection structure composed of a bolt, a nut and a clamped part, as shown in Figure 1 . In engineering, the installation of threaded fasteners is usually achieved by applying a certain tightening torque, torsional angle or pre-tightening force to the bolt or nut. During the installation or disassembly process, the driving side rotates, and the other side generally needs to be stopped from rotating. The characteristic is that it is generally completed on both sides of the clamped part, and the torsional-tensile relationship of the fastener can be obtained on a common torsional tensile testing machine.

[0003] In some specific occasions in engineering, the fastener can only be inserted into the mounting hole from one side of the clamped part and fixed. At this time, a single-sided installation fastener is required. Commonly used single-sided installation fasteners are shown in Figure 2 . It includes a nail body B1, a core rod bolt B2, a nail sleeve B3, and a nut B4. The inside of the nail body B1 and the nail sleeve B3 is a through hole for passing the core rod bolt B2. The bearing end of the nail body B1 is a cone, and the other end of the cone slope is in mating connection with the inner cone of the nail sleeve B3. The other end of the nail sleeve B3 is connected to the nut B4, and the mating surface is provided with teeth. When the core rod bolt B2 is tightened, the nut B4 is stopped from rotating; the core rod bolt B2 passes through the nail body B1 and the nail sleeve B3 and meshes with the nut B4. Rotating the core rod bolt B2 causes the nut B4 to move axially, pushing the nail sleeve B3 towards the nail body B1 and gradually expanding the outer circle of the inner cone of the nail sleeve B3. When the expanded end face of the nail sleeve B3 contacts the clamped part, end face bending deformation occurs. When the tightening torque reaches a predetermined value, the deformation of the nail sleeve B3 reaches the best state, and at the same time, the loading head of the core rod bolt B2 is broken off (as shown in Figure 3 ) to achieve the purpose of single-sided installation and clamping of the clamped parts (B5, B6).

[0004] The measurement of the torsional-tensile relationship and friction coefficient of single-sided installation fasteners is the basis for guiding their design and use in installation. The tightening torque of a single-sided installation fastener is converted into a clamping force, and this clamping force is usually referred to as a pre-tightening force. The conversion relationship between the tightening torque and the pre-tightening force is called the torque coefficient, which can be expressed by the following formula:

[0005] T = kdF

[0006] k is called the torque coefficient, d is the nominal diameter of the bolt or nut, T is the tightening torque, and F is the pre-tightening force. In engineering for threaded fastening connections at specific positions, designers need to determine the required pre-tightening force during installation based on conditions such as loads, and then calculate the required tightening torque or torsional angle through formulas, and use the obtained tightening torque or torsional angle to guide the installation operation.

[0007] The torsional-tensile relationship of threaded fastening can also be expressed by the following formula:

[0008]

[0009] where, T is the tightening torque, μ b is the friction coefficient of the support surface, r b is the effective radius of the support surface, p is the thread pitch, μ t is the thread friction coefficient, r t is the effective radius of the thread, and α is the thread profile angle. The first term on the right side of the above equation is the frictional torque of the support surface, which can be represented by the symbol T b ; the second term is the equivalent thread frictional torque, which can be represented by the symbol T t , that is:

[0010] Tb = Fμb rb

[0011]

[0012] In the prior art, the detection feature of the mechanical properties of single-sided installed fasteners is single-sided installation and loading test. However, due to the asymmetric force generated by single-sided contact, it is extremely easy to cause bending moment errors; at the same time, most devices only support static / quasi-static loading, and the dynamic load simulation is insufficient, which easily leads to an increase in the deviation of fatigue life prediction; in addition, the prior art also has the defect that it is not easy to disassemble the specimen after single-sided installation and loading.

[0013] Therefore, for single-sided installed fasteners, a method that can accurately measure the torsional-tensile relationship and friction coefficient is needed, and at the same time, it is easy to disassemble the specimen. Summary of the Invention

[0014] The purpose of the present invention is to provide a method for measuring the torsional-tensile relationship and friction coefficient of single-sided installed fasteners to solve the problems of the prior art.

[0015] To achieve the above purpose, the present invention specifically adopts the following technical solutions:

[0016] The present invention provides a method for measuring the torsional-tensile relationship and friction coefficient of single-sided installed fasteners, using a measuring device composed of a fixed carrier, a tensile-torsion composite sensor, an adjusting wedge, an adjusting lead screw, a stop clamp, a movable carrier, a bearing plate, a stop pressure plate, a clamp, and a rotational torque and torsional angle sensor, and the following steps:

[0017] S1. Fix the fixed carrier in place. The fixed carrier, adjusting wedge block, adjusting lead screw, and movable carrier form a loading frame.

[0018] S2. Rigidly mount the tension-torsion composite sensor on the end face of the fixed carrier, with axial and circumferential constraints.

[0019] S3. Install the stop clamp on the inner end face of the tension-torsion composite sensor, with axial and circumferential constraints.

[0020] S4. The movable carrier displaces axially along the test piece and is rigidly positioned with the fixed carrier, and its position can be controlled through the adjusting wedge block and adjusting lead screw.

[0021] S5. Rigidly mount the bearing plate on the end face of the movable carrier, with axial and circumferential constraints.

[0022] S6. Insert the single-sided mounting fastener into the hole of the bearing plate, then install the stop pressure plate, and compress the end face of the single-sided mounting fastener through the screw to achieve axial positioning and circumferential rotation stop of the test piece.

[0023] S7. Connect the rotational torque and rotation angle sensor to the loading head of the single-sided mounting fastener through a clamp.

[0024] S8. Drive the horizontal movement of the movable carrier by rotating the adjusting lead screw. After adjusting to the required distance from the fixed carrier, load the test piece.

[0025] S9. Obtain the tightening torque T and torsional angle through the rotational torque and torsional angle sensor, and obtain the pre-tightening force F and thread friction torque T of the test piece through the tension-torsion composite sensor t ; Through the pre-tightening force F, tightening torque T, and thread torque T t , calculate the torque coefficient K, or calculate the thread friction coefficient μ t , or calculate the support surface friction coefficient μ b ;

[0026] S10. When the experiment ends and the loading head of the single-sided mounting fastener breaks, rotate the adjusting lead screw down to the lowest position. At this time, the distance between the movable carrier and the fixed carrier is the smallest, and the pre-tightening force of the single-sided mounting fastener is removed accordingly. Separate the nut of the single-sided mounting fastener from the core rod bolt.

[0027] Furthermore, the fixed carrier is of a bent plate structure. The lower end face of the fixed carrier can be connected to the application bench. The vertical face of the fixed carrier is perpendicular to the lower end face. The center of the fixed carrier is a stepped hole, which cooperates with the tension-torsion composite sensor and is rigidly constrained with the tension-torsion composite sensor through circumferentially evenly distributed fastening screws.

[0028] Furthermore, the tension-torsion composite sensor has a cage-shaped structure. The right end face of the tension-torsion composite sensor is a stepped shaft structure, and the outer step is rigidly connected to the fixed carrier. The left end face of the tension-torsion composite sensor is an inner stepped through-hole structure, and the inner stepped through-hole is used to install the stop fixture.

[0029] Furthermore, the inner stepped through-hole of the tension-torsion composite sensor installs the stop fixture through a pin, so that the stop fixture is axially and circumferentially constrained with the tension-torsion composite sensor. The end face of the inner stepped hole of the tension-torsion composite sensor is perpendicular to the center, and two cylindrical pin holes are evenly distributed, which are used to install two cylindrical pin shafts, thereby restricting the circumferential rotation of the stop fixture, enabling the tension-torsion composite sensor to measure the pre-tightening force F and the thread torque T of the single-sided installed fastener. t 。

[0030] Furthermore, the stop fixture has a stepped bowl-shaped structure. Two symmetrically and evenly distributed grooves are arranged on the outer end face of the stop fixture, which are stuck on the two cylindrical pin shafts of the tension-torsion composite sensor and are used to transmit the thread torque T of the single-sided installed fastener t to the tension-torsion composite sensor; the inner end face of the stop fixture is perpendicular to the center, and the central through-hole has a clearance fit with the outer cylinder of the single-sided installed fastener. The pre-tightening force F and the thread torque T of the single-sided installed fastener t are transmitted to the tension-torsion composite sensor through the stop fixture, and the pre-tightening force F and the thread torque T of the single-sided installed fastener are measured through the tension-torsion composite sensor. t 。

[0031] Furthermore, the center of the movable carrier is a stepped through-hole. The stepped end face of the movable carrier is perpendicular to the stepped through-hole and is used to install the bearing disc, which is rigidly connected by screws. The stepped hole is coaxial with the tension-torsion composite sensor.

[0032] Furthermore, the bearing disc has a disc structure, and the center is a conical through-hole. The conical surface is matched with the conical surface at the end of the specimen to restrict the axial movement of the specimen. Four light holes are symmetrically arranged on the end face for installing fastening screws; the inner hole of the bearing disc is slightly larger than the outer diameter of the specimen for passing the specimen; two threaded holes are arranged on the end face of the bearing disc for fastening the stop pressing plate.

[0033] Furthermore, two through-holes are symmetrically distributed at both ends of the stop pressing plate, and the center distance is the same as the threaded hole on the end face of the bearing disc. It is connected to the bearing disc through screws. By controlling the pressing force of the screws, the pressure of the convex step on the end face of the stop pressing plate pressing the single-sided installed fastener can be controlled, thereby restricting the rotation of the nail body of the single-sided installed fastener.

[0034] Furthermore, the fixed carrier, the adjusting wedge, the adjusting lead screw and the movable carrier form a load-bearing frame. The movable carrier moves left and right along the guide post group and the guide rail group through the cooperation of the adjusting lead screw and the adjusting wedge. The guide rods of the guide post group are rigidly installed on the end face of the movable carrier, symmetrically distributed at the four corners of the movable loading body, and perpendicular to the movable carrier. The linear bearings of the four sets of guide post groups are rigidly installed on the end face of the fixed carrier and perpendicular to the fixed carrier, realizing the parallel displacement of the movable carrier relative to the fixed carrier.

[0035] The guide rail group is installed on two inclined surfaces of the adjusting wedge. The sliders on both sides are respectively installed on the end faces of the fixed carrier and the movable carrier. The vertical movement of the adjusting wedge drives the horizontal movement of the movable carrier. By adjusting the vertical position of the adjusting wedge, the relative position between the movable carrier and the fixed carrier can be controlled.

[0036] The end of the adjusting lead screw is connected to the upper end face of the adjusting wedge and is constrained by a pin. The adjusting lead screw can rotate freely. The up and down movement of the adjusting lead screw drives the adjusting wedge to move up and down accordingly. The upper end of the adjusting lead screw meshes with the nut fixed to the fixed carrier. By rotating the adjusting lead screw, the adjusting wedge moves up and down, and then the horizontal position of the movable carrier is moved.

[0037] Furthermore, in step S9, the torque coefficient K is calculated through the pre-tightening force F, the tightening torque T and the following formula:

[0038] K = T / (D·F)

[0039] where D is the diameter of the nut of the single-sided installed fastener.

[0040] Through the thread torque T t and the following formula, the thread friction coefficient μ is calculated t :

[0041]

[0042] where p is the thread pitch of the single-sided installed fastener, r t is the effective radius of the thread surface, and α is the thread profile angle;

[0043] Subtract the thread torque T from the tightening torque T t to obtain the support surface friction torque T b , and then calculate the support surface friction coefficient μ based on the following formula b :

[0044] μ b＝ T b / (F·r b )

[0045] where rb is the effective friction radius of the support surface.

[0046] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0047] The method for measuring the torque-tension relationship and friction coefficient of a single-sided mounted fastener provided by the present invention can not only accurately measure the tightening torque T, pre-tightening force F, thread friction torque T t , torsional angle and rotational speed and other data during the entire installation process of the single-sided mounted threaded fastener, and can calculate the torque coefficient K, thread friction coefficient μ t , friction torque T of the rotating support surface b (T b = T - T t ) and support surface friction coefficient μ b and other parameters, and at the same time solves the disassembly problem after installation. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 is a schematic structural diagram of the connection of a typical threaded fastener; Figure 1 In, A1 is a bolt, A2 is a nut, A3 is a clamped part 1, and A4 is a clamped part 2.

[0049] Figure 2 is a schematic structural diagram of a currently commonly used single-sided mounted fastener (specimen); Figure 2 In, B1 is a nail body, B2 is a core rod bolt, B3 is a nail sleeve, and B4 is a nut.

[0050] Figure 3 is a schematic structural diagram of the head being broken after loading during the installation of a currently commonly used single-sided mounted fastener. Figure 3 In, B2 is a core rod bolt, B5 is a clamped part 3, and B6 is a clamped part 4.

[0051] Figure 4 is an installation schematic diagram of the tension-torsion composite sensor and the fixed loading body provided by the embodiment of the present invention.

[0052] Figure 5 is an installation schematic diagram of the tension-torsion composite sensor and the stop fixture provided by the embodiment of the present invention.

[0053] Figure 6 is an installation schematic diagram of the movable loading body and the bearing plate provided by the embodiment of the present invention. Figure 6 In, (a) is a side cross-sectional view, and (b) is a three-dimensional structural diagram.

[0054] Figure 7 is an installation schematic diagram of the bearing plate and the stop pressure plate provided by the embodiment of the present invention. Figure 7In the figure, (a) is a side cross-sectional view, and (b) is a front view.

[0055] Figure 8 This is a schematic structural diagram of the loading frame provided by an embodiment of the present invention. Figure 8 In the figure, (a) is a left view, (b) is a front view, and (c) is a right cross-sectional view.

[0056] Figure 9 This is a schematic structural diagram of the measuring device for the torsional tension relationship and friction coefficient of single-sided mounting fasteners provided by an embodiment of the present invention. Figure 1 。

[0057] Figure 10 This is a schematic structural diagram of the measuring device for the torsional tension relationship and friction coefficient of single-sided mounting fasteners provided by an embodiment of the present invention. Figure 2 。 Detailed implementation manners

[0058] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0059] Currently commonly used single-sided mounting fasteners, such as Figure 2 shown, include a nail body B1, a core rod bolt B2, a nail sleeve B3, and a nut B4. The nail body B1 and the nail sleeve B3 are through holes inside for passing the core rod bolt B2. The bearing end of the nail body B1 is a cone, and the other end of the cone slope is in mating connection with the inner cone of the nail sleeve B3. The other end of the nail sleeve B3 is connected to the nut B4, and the mating surface is provided with teeth. When the core rod bolt B2 is tightened, the nut B4 is prevented from rotating; the core rod bolt B2 passes through the nail body B1, the nail sleeve B3 and meshes with the nut B4. Rotating the core rod bolt B2 causes the nut B4 to move axially, pushing the nail sleeve B3 towards the nail body B1, and gradually expanding the outer circle of the inner cone of the nail sleeve B3. When the expanded end face of the nail sleeve B3 contacts the clamped part, end face bending deformation occurs. When the tightening torque reaches a predetermined value, the deformation of the nail sleeve B3 reaches the best state, and at the same time, the loading head of the core rod bolt B2 is broken off (as Figure 3 shown), achieving the purpose of clamping the clamped parts (B5, B6) by single-sided mounting.

[0060] The measuring method for the torsional tension relationship and friction coefficient of the single-sided mounting fasteners provided by the present invention, aiming at the currently commonly used single-sided mounting fasteners, adopts a measuring device composed of a fixed carrier 1, a tensile-torsional composite sensor 2, an adjusting wedge 3, an adjusting lead screw 4, a stop fixture 5, a movable carrier 6, a bearing plate 7, a stop pressure plate 8, a fixture 9, and a rotational torque and torsional angle sensor 10 (as Figure 9 and10 as shown in the figure, and the following steps:

[0061] S1. Fix the fixed carrier 1 in place. The fixed carrier 1, the adjusting wedge block 3, the adjusting lead screw 4, and the movable carrier 6 form a loading frame.

[0062] Specifically, as Figure 4 shown, the fixed carrier 1 is of a bent plate structure. The lower end face of the fixed carrier 1 can be connected to the application bench. The vertical face of the fixed carrier 1 is perpendicular to the lower end face. The center of the fixed carrier 1 is a stepped hole, which cooperates with the tensile-torsional composite sensor 2 and is rigidly constrained with the tensile-torsional composite sensor 2 through circumferentially evenly distributed fastening screws.

[0063] S2. Rigidly install the tensile-torsional composite sensor 2 on the end face of the fixed carrier 1 through screws, so that the fixed end of the tensile-torsional composite sensor 2 is axially and circumferentially constrained by the fixed carrier 1, enabling the tensile-torsional composite sensor to measure the pre-tightening force and torque at the loading end.

[0064] Specifically, as Figure 4 shown, the tensile-torsional composite sensor 2 is of a cage-shaped structure. The right end face of the tensile-torsional composite sensor 2 is of a stepped shaft structure, and the outer step is rigidly connected to the fixed carrier 1; the left end face of the tensile-torsional composite sensor 2 is of an inner stepped through-hole structure, and the inner stepped through-hole is used to install the stop fixture 5.

[0065] S3. Install the stop fixture 5 on the inner end face of the tensile-torsional composite sensor 2 through a pin, and the stop fixture 5 is axially and circumferentially constrained with the tensile-torsional composite sensor 2; enabling the tensile-torsional composite sensor to measure the pre-tightening force (F) and thread torque (T t ) of the single-sided mounted fastener (specimen).

[0066] Specifically, as Figure 5 shown, the inner stepped through-hole of the tensile-torsional composite sensor 2 installs the stop fixture 5 through a pin, so that the stop fixture 5 is axially and circumferentially constrained with the tensile-torsional composite sensor 2. The end face of the inner stepped hole of the tensile-torsional composite sensor 2 is perpendicular to the center and is evenly distributed with two cylindrical pin holes for installing two cylindrical pin shafts, thereby restricting the circumferential rotation of the stop fixture 5, enabling the tensile-torsional composite sensor 2 to measure the pre-tightening force F and thread torque T of the single-sided mounted fastener t .

[0067] The stop fixture 5 is of a stepped bowl-shaped structure. The outer end face of the stop fixture 5 is provided with two symmetrically and evenly distributed grooves, which are stuck on the two cylindrical pin shafts of the tensile-torsional composite sensor 2 for transmitting the thread torque T t of the single-sided mounted fastener to the tensile-torsional composite sensor 2; the inner end face of the stop fixture 5 is perpendicular to the center, and the central through-hole has a clearance fit with the outer cylinder of the single-sided mounted fastener. The pre-tightening force F and thread torque T of the single-sided mounted fastenert It is transmitted to the tension-torsion composite sensor 2 through the stop fixture 5, and the pre-tightening force F and the thread torque T of the single-sided mounted fastener are measured by the tension-torsion composite sensor 2 t .

[0068] S4. The movable carrier 6 axially displaces along the test piece, and is rigidly positioned with the fixed carrier 1 through screws, and the position can be controlled by adjusting the wedge block 3 and the adjusting lead screw 4

[0069] Specifically, as Figure 6 shown, the center of the movable carrier 6 is a stepped through-hole. The stepped end face of the movable carrier 6 is perpendicular to the stepped through-hole, which is used to install the bearing disc 7 and is rigidly connected by screws. The stepped hole is coaxial with the tension-torsion composite sensor 2

[0070] S5. Rigidly install the bearing disc 7 on the end face of the movable carrier 6 through screws, with axial and circumferential constraints

[0071] Specifically, as Figure 7 shown, the bearing disc 7 is of a disc structure, and the center is a conical through-hole. The conical surface cooperates with the conical surface at the end of the test piece to restrict the axial movement of the test piece. Four light holes are symmetrically arranged on the end face for installing fastening screws to restrict the circumferential movement of the test piece; the inner hole of the bearing disc 7 is slightly larger than the outer diameter of the test piece for passing the test piece; two threaded holes are arranged on the end face of the bearing disc for fastening the stop pressing plate 8

[0072] S6. Install the single-sided mounted fastener into the hole of the bearing disc 7, then install the stop pressing plate 8, and press the end face of the single-sided mounted fastener through screws to achieve axial positioning and circumferential rotation stop of the test piece

[0073] Specifically, as Figure 7 shown, two through-holes are symmetrically distributed at both ends of the stop pressing plate 8, and the center distance is the same as the threaded hole on the end face of the bearing disc. It is connected to the bearing disc through screws. By controlling the pressing force of the screws, the pressure of the convex step on the end face of the stop pressing plate 8 pressing the single-sided mounted fastener can be controlled, thereby restricting the rotation of the nail body of the single-sided mounted fastener

[0074] S7. Connect the rotational torque and rotation angle sensor 10 to the loading head of the single-sided mounted fastener through the fixture 9

[0075] It is transmitted to the loading head of the single-sided mounted fastener (test piece) through the rotational torque and torsion angle sensor 10 and the fixture 9. The rotational torque and torsion angle sensor 10 is used to measure the tightening torque (T) and the torsion angle of the single-sided mounted fastener (test piece)

[0076] S8. Drive the horizontal movement of the movable carrier 6 by rotating the adjusting lead screw 4. After adjusting to the required distance from the fixed carrier 1, load the test piece

[0077] Specifically, as Figure 8 shown, the fixed carrier 1, the adjusting wedge 3, the adjusting lead screw 4 and the movable carrier 6 form a load-bearing frame. The movable carrier 6 moves left and right along the guide post group 11 and the guide rail group 12 through the cooperation of the adjusting lead screw 4 and the adjusting wedge 3.

[0078] The guide rods of the guide post group 11 are rigidly installed on the end face of the movable carrier 6, symmetrically distributed at the four corners of the movable carrier 6, and perpendicular to the movable carrier 6. The linear bearings of the four sets of guide post groups 11 are rigidly installed on the end face of the fixed carrier 1 and perpendicular to the fixed carrier 1, realizing the parallel displacement of the movable carrier 6 relative to the fixed carrier 1.

[0079] The guide rail group 12 is installed on two inclined surfaces of the adjusting wedge 3. The sliders on both sides are respectively installed on the end faces of the fixed carrier 1 and the movable carrier 6. The vertical movement of the adjusting wedge 3 drives the horizontal movement of the movable carrier 6. By adjusting the vertical position of the adjusting wedge 3, the relative position between the movable carrier 6 and the fixed carrier 1 can be controlled.

[0080] The end of the adjusting lead screw 4 is connected to the upper end face of the adjusting wedge 3 and is constrained by a pin. The adjusting lead screw 4 can rotate freely. The up and down movement of the adjusting lead screw 4 drives the adjusting wedge 3 to move up and down accordingly. The upper end of the adjusting lead screw 4 meshes with the nut fixed to the fixed carrier 1. By rotating the adjusting lead screw 4, the adjusting wedge 3 moves up and down, and further moves the horizontal position of the movable carrier 6.

[0081] S9. Obtain the tightening torque T and the torsional angle through the rotational torque and torsional angle sensor 10, and obtain the pre-tightening force F and the thread friction torque T of the test piece through the tension-torsion composite sensor t ; Through the pre-tightening force F, the tightening torque T, and the thread torque T t , calculate the torque coefficient K, or calculate the thread friction coefficient μ t , or calculate the support surface friction coefficient μ b .

[0082] Specifically, the torque coefficient K is calculated through the pre-tightening force F, the tightening torque T, and the following formula:

[0083] K = T / (D·F)

[0084] where D is the diameter of the nut of the single-sided installed fastener.

[0085] The thread friction coefficient μ is calculated through the thread torque T t and the following formula t :

[0086]

[0087] where p is the thread pitch of the single-sided mounting fastener, r t is the effective radius of the thread surface, and α is the thread profile angle;

[0088] Subtract the thread torque T t from the tightening torque T to obtain the frictional torque T b of the support surface, and then calculate the coefficient of friction μ of the support surface based on the following formula b :

[0089] μ b＝ T b / (F·r b )

[0090] where r b is the effective friction radius of the support surface.

[0091] S10. When the experiment ends and the loading head of the single-sided mounting fastener is broken off, lower the adjusting screw 4 to the lowest position. At this time, the distance between the movable loading body 6 and the fixed loading body 1 is the smallest, and the pre-tightening force of the single-sided mounting fastener is removed, and the nut and the core rod bolt of the single-sided mounting fastener can be separated conveniently.

[0092] Control the position of the adjusting wedge 3 by rotating the adjusting screw 4, that is, control the distance between the movable bearing body 6 and the fixed bearing body 1; for models with small loads, the torque for driving the adjusting screw 4 is not large and can be easily turned by hand, so a manual driving method is adopted; for models with large loads, the torque for driving the adjusting screw 4 is relatively large, and it is relatively laborious to turn by hand at this time, so an electric driving method is adopted.

[0093] In summary, the test method provided by the present invention can not only accurately measure data such as the tightening torque T, pre-tightening force F, thread frictional torque Tt, torsional angle and rotational speed during the entire installation process of the single-sided mounted threaded fastener, but also calculate the torque coefficient K and the thread friction coefficient μ according to the relevant formulas of the torque-tension relationship of the thread fastening t , the frictional torque T b (T b =T - T t ) of the rotating support surface, the coefficient of friction μ b of the support surface and other parameters, and at the same time solve the problem of disassembly after installation.

[0094] The above is only a preferred embodiment of the present invention and is not intended to limit the present invention. The scope of patent protection of the present invention shall be subject to the claims. Any equivalent structural changes made by using the content of the specification and drawings of the present invention shall similarly be included in the scope of protection of the present invention.

Claims

1. A method for measuring the torsional tension relationship and friction coefficient of a single-sided mounting fastener, characterized in that Adopt a measuring device composed of a fixed carrier (1), a tension-torsion composite sensor (2), an adjusting wedge block (3), an adjusting lead screw (4), a stop fixture (5), a movable carrier (6), a bearing plate (7), a stop pressure plate (8), a fixture (9) and a rotational torque and torsion angle sensor (10), and the following steps: S1. Fix the fixed carrier (1) in place. The fixed carrier (1), the adjusting wedge block (3), the adjusting lead screw (4) and the movable carrier (6) form a loading frame. S2. Rigidly mount the tension-torsion composite sensor (2) on the end face of the fixed carrier (1), with axial and circumferential constraints. S3. Install the stop fixture (5) on the inner end face of the tension-torsion composite sensor (2), with axial and circumferential constraints. S4. The movable carrier (6) displaces axially along the test piece and is rigidly positioned with the fixed carrier (1), and its position can be controlled by the adjusting wedge block (3) and the adjusting lead screw (4). S5. Rigidly mount the bearing plate (7) on the end face of the movable carrier (6), with axial and circumferential constraints. S6. Insert the single-sided mounting fastener into the hole of the bearing plate (7), then install the stop pressure plate (8), and compress the end face of the single-sided mounting fastener with screws to achieve axial positioning and circumferential anti-rotation of the test piece. S7. Connect the rotational torque and rotation angle sensor (10) to the loading head of the single-sided mounting fastener through the fixture (9). S8. Drive the movable carrier (6) to move horizontally by rotating the adjusting lead screw (4). After adjusting to the required distance between the fixed carrier (1), load the test piece. S9. Obtain the tightening torque T and the torsional angle through the rotational torque and torsional angle sensors, and obtain the pre-tightening force F and the thread friction torque T of the test piece through the combined tension-torsion sensor t ; Through the pre-tightening force F, the tightening torque T, and the thread torque T t , calculate the torque coefficient K, or calculate the thread friction coefficient μ t , or calculate the support surface friction coefficient μ b ; S10. When the experiment ends and the loading head of the single-sided mounting fastener is broken, rotate the adjusting lead screw (4) down to the lowest position. At this time, the distance between the movable carrier (6) and the fixed carrier (1) is the smallest, and the pre-tightening force of the single-sided mounting fastener is removed accordingly. Separate the nut of the single-sided mounting fastener from the core rod bolt.

2. The measuring method for the torsional tension relationship and friction coefficient of a single-sided mounting fastener according to claim 1, wherein The fixed carrier (1) is of a bent plate structure. The lower end face of the fixed carrier (1) can be connected to the application bench. The vertical face of the fixed carrier (1) is perpendicular to the lower end face. The center of the fixed carrier (1) is a stepped hole, which cooperates with the tension-torsion composite sensor (2) and is rigidly constrained with the tension-torsion composite sensor (2) through circumferentially evenly distributed fastening screws.

3. The measuring method for the torsional tension relationship and friction coefficient of a single-sided mounting fastener according to claim 1, characterized in that The tension-torsion composite sensor (2) is of a cage structure. The right end face of the tension-torsion composite sensor (2) is of a stepped shaft structure, and the outer step is rigidly connected to the fixed carrier (1). The left end face of the tension-torsion composite sensor (2) is of an inner stepped through-hole structure, and the inner stepped through-hole is used to install the stop fixture (5).

4. The measuring method for the torsional tension relationship and friction coefficient of a single-sided mounting fastener according to claim 3, characterized in that, The inner stepped through hole of the combined tension and torsion sensor (2) is installed with a stop fixture (5) through a pin, so that the stop fixture (5) is axially and circumferentially constrained with the combined tension and torsion sensor (2). The end face of the inner stepped hole of the combined tension and torsion sensor (2) is perpendicular to the center, and two cylindrical pin holes are evenly distributed for installing two cylindrical pin shafts, thereby restricting the circumferential rotation of the stop fixture (5), enabling the combined tension and torsion sensor (2) to measure the pre-tightening force F and the thread torque T received by the single-sided installed fastener t .

5. The measuring method for the torsional tension relationship and friction coefficient of a single-sided mounting fastener according to claim 1, characterized in that The stop fixture (5) is a stepped bowl-shaped structure. Two symmetrically and evenly distributed grooves are arranged on the outer end face of the stop fixture (5), which are clamped on the two cylindrical pin shafts of the pull-twist composite sensor (2) to transmit the thread torque T of the single-sided mounting fastener. t to the pull-twist composite sensor (2); the inner end face of the stop fixture (5) is perpendicular to the center, and the central through hole has a clearance fit with the outer cylinder of the single-sided mounting fastener. The pre-tightening force F and the thread torque T of the single-sided mounting fastener t are transmitted to the pull-twist composite sensor (2) through the stop fixture (5), and the pre-tightening force F and the thread torque T of the single-sided mounting fastener are measured by the pull-twist composite sensor (2). t .

6. The measurement method of the torsional tension relationship and friction coefficient of a single-sided mounting fastener according to claim 1, characterized in that The center of the movable carrier (6) is a stepped through-hole. The stepped end face of the movable carrier (6) is perpendicular to the stepped through-hole and is used to install the bearing plate (7), and is rigidly connected by screws. The stepped hole is coaxial with the tension-torsion composite sensor (2).

7. A method for measuring the torsional tension relationship and friction coefficient of a single-sided mounting fastener according to claim 1, characterized in that, The carrier plate (7) is of a disc structure, with a conical through-hole at the center. The conical surface mates with the conical surface at the end of the test piece to restrict the axial movement of the test piece. Four light holes are symmetrically arranged on the end face for installing fastening screws; the inner hole of the carrier plate (7) is slightly larger than the outer diameter of the test piece for passing the test piece; two threaded holes are arranged on the end face of the carrier plate for fastening the stop pressing plate (8).

8. The measuring method for the torsional tension relationship and friction coefficient of a single-sided mounting fastener according to claim 1, characterized in that Two through-holes are symmetrically distributed at both ends of the stop pressing plate (8), and the center distance is the same as that of the threaded holes on the end face of the bearing plate. It is connected to the carrier plate by screws. By controlling the pressing force of the screws, the pressure of the convex step on the end face of the stop pressing plate (8) pressing the single-sided mounting fastener can be controlled, thereby restricting the rotation of the nail body of the single-sided mounting fastener.

9. The measuring method for the torsional tension relationship and friction coefficient of a single-sided mounting fastener according to claim 1, characterized in that The fixed carrier (1), the adjusting wedge block (3), the adjusting lead screw (4) and the movable carrier (6) form a loading frame. The movable carrier (6) moves left and right along the guide post group (11) and the guide rail group (12) through the cooperation of the adjusting lead screw (4) and the adjusting wedge block (3); the guide rods of the guide post group (11) are rigidly installed on the end face of the movable carrier (6), and are symmetrically distributed at the four corners of the movable loading carrier (6) and perpendicular to the movable carrier (6). The linear bearings of the four sets of guide post groups (11) are rigidly installed on the end face of the fixed carrier (1) and perpendicular to the fixed carrier (1) to realize the parallel displacement of the movable carrier (6) relative to the fixed carrier (1). The guide rail group (12) is installed on the two inclined surfaces of the adjusting wedge block (3). The sliders on both sides are respectively installed on the end faces of the fixed carrier (1) and the movable carrier (6). The up and down vertical movement of the adjusting wedge block (3) drives the horizontal movement of the movable carrier (6). By adjusting the up and down vertical position of the adjusting wedge block (3), the relative position between the movable carrier (6) and the fixed carrier (1) can be controlled. The end of the adjusting lead screw (4) is connected to the upper end face of the adjusting wedge block (3) and is restricted by a pin. The adjusting lead screw (4) can rotate freely. The up and down movement of the adjusting lead screw (4) drives the adjusting wedge block (3) to move up and down accordingly. The upper end of the adjusting lead screw (4) meshes with the nut fixed to the fixed carrier (1). By rotating the adjusting lead screw (4), the adjusting wedge block (3) moves up and down accordingly, and then the horizontal position of the movable carrier (6) is moved.

10. The measuring method for the torsional tension relationship and friction coefficient of a single-sided mounting fastener according to claim 1, wherein In step S9, the torque coefficient K is calculated through the pre-tightening force F, the tightening torque T and the following formula: K = T / (D·F) Where D is the diameter of the nut of the single-sided mounting fastener. Through the thread torque T t and the thread friction coefficient μ is calculated by the following formula t : where p is the thread pitch of the single-sided mounting fastener, r t is the effective radius of the thread surface, and α is the thread profile angle; Subtract the thread torque \(T\) from the tightening torque \(T\). t Obtain the frictional torque \(T\) of the support surface b , and then calculate the coefficient of friction \(\mu\) of the support surface based on the following formula b : μ b = T b / (F·r b ) Among them, r b is the effective friction radius of the support surface.

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