Nut structure
By designing a protrusion on the nut body and combining it with controller detection, the problem of accidental tightening of double-ended bolts of the same length is solved, achieving efficient and precise tightening operations.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2025-07-22
- Publication Date
- 2026-07-14
AI Technical Summary
When using double-ended bolts of the same length for fastening connections, it is difficult to avoid the problem of accidentally tightening a new nut on a bolt that already has a nut installed, resulting in inaccurate and inefficient fastening operations.
A nut structure was designed in which the nut body has a protruding part when screwed with a bolt. The protrusion height of the protrusion is greater than the bolt pitch. The rotational torque and angle of the nut are detected by a controller to ensure that the nut is tightened only under a predetermined torque, preventing the installation of an extra nut.
This effectively prevents new nuts from being mistakenly tightened on bolts that already have nuts installed, improving the accuracy and efficiency of tightening operations and reducing operating time and workload.
Smart Images
Figure CN224497056U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to nut structure. Background Technology
[0002] Patent Document 1 discloses a locking nut. The locking nut consists of two nuts of the same shape, each nut having a protrusion and a recess on one axial face. The two nuts with the protrusion and recess facing each other, the protrusion of one nut engaging with the recess of the other nut and being screwed into a bolt, thereby using the two nuts as locking nuts.
[0003] [Existing Technical Documents]
[0004] [Patent Literature]
[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-015392 Utility Model Content
[0006] The problem to be solved by the utility model
[0007] However, in the fastening process of manually screwing nuts and bolts together to secure two components, nut wrenches (automatic nut tightening machines), such as electric torque wrenches, are mostly used. Nut wrenches screw the nuts and bolts together to achieve a preset tightening torque.
[0008] Therefore, in the fastening process, the use of a nut wrench allows for smooth fastening operations regardless of individual differences in operator skill level (proficiency). Compared to manual fastening (manual operation), it results in less deviation in tightening force, achieving high-precision and efficient fastening. Furthermore, the use of a nut wrench in the fastening process improves workability by reducing operation time and workload in fastening connections using multiple nuts.
[0009] In the fastening and connection process, when one or more mounting components are fastened and fixed to the base by using one of the two fastened structural components as the base and the other as the mounting component, a double-ended bolt is installed on the base so that the double-ended bolt is inserted into the bolt hole formed on the mounting component, and a nut is screwed onto the double-ended bolt protruding from the bolt hole.
[0010] Previously, double-ended studs of varying lengths were typically configured based on their position on the mounting component and the substrate on which it was mounted. The protrusion height (length) of the stud from the mounting component was set to the length required to engage a single nut (the length needed for a tight connection). This prevented the accidental tightening of a connection (double nut) by installing two nuts on a single stud.
[0011] In recent years, from a cost-cutting perspective, most components have been standardized, and sometimes even the base material uses studded bolts of the same length. By configuring multiple studded bolts of the same length on the base material, it can be difficult to determine whether a studded bolt for the target object has been installed during tightening operations using a nut wrench. Therefore, if the length of the studded bolt is sufficient to install multiple nuts, it can easily lead to problems such as accidentally tightening two nuts onto a single studded bolt during tightening operations.
[0012] This utility model was made in view of the above facts, and its purpose is to provide a nut structure that can prevent the installation of a new nut on a bolt when the nut has already been installed on the bolt and the fastened connecting parts are fastened together.
[0013] Methods for solving problems
[0014] The first embodiment of the present invention for achieving the above-mentioned objective includes a nut structure comprising: a nut body having one axial side designated as a seating surface, which is screwed onto a bolt by rotating relative to the fastened structural member; and a protrusion protruding from the nut body on the side opposite to the seating surface in a direction opposite to the seating surface, wherein the protrusion maintains a protrusion height greater than the bolt pitch even under pressure corresponding to a torque exceeding the target torque.
[0015] Utility Model Effect
[0016] In the nut structure of the first embodiment of this utility model, the nut body, which is the seat surface opposite to the fastened connecting component, is screwed into the bolt by rotation. The torque of the seat surface after it is seated on the fastened connecting component reaches the preset target torque, thereby fastening the fastened connecting component and the bolt.
[0017] Furthermore, a protrusion is formed on the nut body, protruding in the opposite direction to the seat surface on the side of the nut body. This protrusion is configured to maintain a protrusion height greater than the bolt pitch, even under pressure corresponding to a torque exceeding the maximum value of the target torque. Moreover, the maximum target torque is set for each nut body, and the target torque is set within a range not exceeding this maximum value.
[0018] Here, when using a nut wrench to screw the nut body onto the bolt, the torque required to rotate the nut body is relatively low until the nut body's seat surface settles on the fastened connecting component, etc., but increases as the seat surface settles. After the nut body is seated, the nut wrench stops rotating to achieve the target torque required to rotate the nut body. At this time, the protruding part of the nut body is not under pressure.
[0019] In contrast, when a new nut body is screwed onto a bolt that already has a nut body installed, the seat surface of the new nut body abuts against the protrusion of the existing nut body. At this time, by making the protrusion height of the protrusion greater than the bolt pitch, even if the new nut body is to be rotated further, the protrusion of the already installed nut body will impede the rotation.
[0020] Therefore, when a nut body is already installed on the bolt, the new nut body will not rotate even if the torque used for rotation increases. The nut wrench can detect the rotation of the nut body and stop operating, thus preventing the nut body from being mistakenly tightened. Attached Figure Description
[0021] Figure 1 This is a schematic side view of the nut and double-ended bolt of this embodiment.
[0022] Figure 2 (A) is a schematic structural diagram showing the side view of the nut body, (B) is a schematic structural diagram showing the side view of the main part of the double-ended bolt, and (C) is a schematic structural diagram showing the state of installing a new nut body overlapping with the already installed nut body.
[0023] Figure 3 It is a line graph that roughly represents the change of torque relative to the nut body over time. Detailed Implementation
[0024] The embodiments of this utility model will now be described in detail with reference to the accompanying drawings.
[0025] In this embodiment, the nut 10 is mounted on a stud bolt 12, which serves as a bolt. The nut 10 includes a nut body 14, which is mounted on the stud bolt 12.
[0026] exist Figure 1 In the diagram, a side view is used to show a schematic representation of the nut 10 and the stud bolt 12 of this embodiment. Additionally, in... Figure 2 In (A), the nut body is represented by a side view schematic structural diagram. Figure 2 In (B), the main parts of the double-ended bolt are shown in a side view schematic structural diagram. Figure 2In (C), a schematic side view shows an example of a state where two nut bodies are mounted on a stud bolt. Furthermore, in the drawing, the axial direction of the stud bolt 12 is indicated by arrow S. Additionally, in the following description, the direction intersecting the axial direction of the stud bolt 12 is defined as lateral.
[0027] like Figure 1 and Figure 2 As shown in (A), the nut body 14 of the nut 10 has a generally hexagonal prism shape, and the nut body 14 is a hexagonal nut. An inner hole 16 with a predetermined inner diameter (nominal diameter) is formed in the axial part of the nut body 14 (nut 10), and an internal thread is engraved on the inner circumferential surface of the inner hole 16.
[0028] The nut body 14 can be of two types (two types of nuts), but preferably one type (one type of nut) is defined by chamfering one side in the axial direction to form the seat surface. Furthermore, a disc-shaped flange 18 is integrally formed on one side (seat surface side) of the nut body 14 in the axial direction, making the nut body 14 a flanged nut. The surface of the nut body 14 with the flange 18 side in the axial direction is designated as the seat surface 20, and the surface opposite to the seat surface 20 is designated as the top surface 22.
[0029] like Figure 1 As shown, the double-ended stud 12 has a generally cylindrical shaft portion 24 with a predetermined outer diameter, and the shaft portion 24 has a general structure with external threads engraved on its outer periphery. In the double-ended stud 12, a nut body 14 with an inner hole 16 having an inner diameter corresponding to the outer diameter of the shaft portion 24 (the same nominal diameter) is used to screw the nut body 14 onto the shaft portion 24.
[0030] In this embodiment, the nut 10 and the stud bolt 12 are used for fastening and connecting two fastened structural members, namely the base 26 and the mounting component 28 mounted on the base 26. The stud bolt 12 is installed at a predetermined position in the base 26. Furthermore, the base 26 is configured with a known structure, such as the shaft portion 24 protruding from the base 26 by embedding the head of the stud bolt 12 into the base 26.
[0031] The base 26 can accommodate structures capable of mounting one or more mounting components 28, and the shapes, functions (types), etc., of the mounting components 28 can vary. When multiple mounting components 28 are mounted on the base 26, double-ended bolts 12 are inserted at positions corresponding to the respective mounting positions of the mounting components 28. Furthermore, bolt holes 30 are formed through the mounting components 28 for the shaft portions 24 of the double-ended bolts 12 to be inserted. By inserting the shaft portions 24 of the double-ended bolts 12 into the bolt holes 30, the mounting components 28 are positioned relative to the base 26.
[0032] The double-ended bolt 12 is inserted into the bolt hole 30 of the mounting component 28, and the nut body 14 is screwed onto the shaft portion 24 protruding on the opposite side of the base 26. Thus, the mounting component 28 is securely connected and fixed to the base 26 by the axial force generated by the shaft portion 24 of the double-ended bolt 12.
[0033] On the other hand, the engagement (tightening connection operation) of the nut body 14 with the double-ended bolt 12 (shaft 24) can be performed using a nut wrench (automatic nut tightening connection machine) 40, which functions as an electric torque wrench. A controller 42 is connected to the nut wrench 40, and the nut wrench 40 controls the operation of a motor (not shown) via the controller 42, thereby rotating the nut body 14 mounted on the socket using the rotational force of the motor.
[0034] The controller 42 is a microcomputer (not shown) that connects the CPU, ROM, RAM and non-volatile memory via a bus to exchange data. The controller 42 reads the torque control program stored in the ROM and RAM through the CPU and executes it using the RAM as working memory, thereby realizing the torque control function for the nut wrench 40.
[0035] A sensor (not shown) is provided on the nut wrench 40. This sensor detects the rotation angle (rotation angle), rotation time (working time) of the nut body 14, and the torque (rotation torque, i.e. tightening torque) that causes the nut body 14 to rotate.
[0036] The controller 42 controls the motor's operation while acquiring the rotation angle, rotation time (action time), and torque that rotates the nut body 14, as detected by various sensors in the nut wrench 40. Alternatively, the nut wrench 40 can detect the rotation angle of a rotating shaft or similar component rotated by the motor, instead of the rotation angle of the nut body 14. This basic structure of the nut wrench 40 and controller 42 allows for the application of known structures.
[0037] However, a protrusion 50 is formed in the nut body 14 of the nut 10. The protrusion 50 protrudes at a predetermined height from the periphery of the inner hole 16 in the top surface 22 of the nut body 14 toward the side opposite to the seat surface 20. When the protrusion 50 is subjected to pressure toward the seat surface 20 in the nut body 14, even if the pressure exceeds a predetermined set pressure, it can suppress plastic deformation and elastic deformation and maintain the predetermined height.
[0038] Next, the fastening connection between the base 26, which uses nut 10 and double-ended bolt 12, and the mounting component 28 will be described.
[0039] In the nut 10, a target torque Tt [N·m] is set relative to the tightening torque of the nut body 14. In the nut body 14, if the lower limit of the target torque Tt is set to a [N·m] and the upper limit of the target torque Pt is set to b [N·m], then the lower limit a and the upper limit b are determined by the structure (structural dimensions), material, etc. of the nominal diameter (inner diameter of the inner hole 16) of the nut body 14.
[0040] Furthermore, the nut body 14 rotates with a target torque Tt while seated on the mounting component 28, thereby generating an axial force [N] corresponding to the target torque Tt. The mounting component 28, etc., bears a target pressure Pt [N / m], which is a pressure corresponding to the target torque Tt. 2 Therefore, the target torque Tt of the nut body 14 used for fastening the base 26 and the mounting component 28 is set within the range of lower limit a to upper limit b (a≤Tt≤b) based on the base 26, the mounting component 28 and their strength, etc.
[0041] In the nut body 14, the torque (rotational torque) T [N·m] required for rotation to engage with the stud bolt 12 is a low value during the period until the nut body 14's seat surface 20 is seated on the mounting component 28, etc. Furthermore, as the nut body 14 is seated on the mounting component 28, etc., the torque T required for rotation increases, functioning as the tightening torque at the start of formal tightening. Between the nut body 14 and the stud bolt 12, an axial force [N] corresponding to the tightening torque (torque T) is generated when formal tightening begins.
[0042] In the nut body 14, when the new nut body 14 is screwed into the double-ended bolt 12, the seat surface 20 of the new nut body 14 abuts against the protrusion 50, thereby the protrusion 50 receives a pressure corresponding to the torque T from the new nut body 14.
[0043] Here, as Figure 2 As shown in (B), the external thread of the double-ended bolt 12 is formed with a predetermined pitch p [mm]. Additionally, as... Figure 2 As shown in (A), the protrusion height of the protrusion 50 from the top surface 22 is d [mm]. Furthermore, in the nut body 14, the protrusion height d of the protrusion 50 is greater than the pitch p of the stud bolt 12 (d > p).
[0044] Furthermore, in the nut body 14, even when the protrusion 50 is subjected to a pressure Pb [N / m] corresponding to a torque Tb exceeding the upper limit value b of the target torque Tt, 2Even under conditions where the protrusion 50 is subjected to pressure exceeding the upper limit of the target pressure Pt (pressure Pb), the protrusion height d remains greater than the pitch p. That is, even when subjected to pressure exceeding the upper limit of the target pressure Pt (pressure Pb), the protrusion 50 can suppress plastic deformation. Furthermore, the protrusion 50 can also elastically deform; in this case, even when subjected to pressure exceeding Pb, the protrusion height (protrusion height after elastic deformation) d remains greater than the pitch p (d > p), and the material (Young's modulus) is also present.
[0045] In the controller 42, a target torque Tt and a settling torque Tc are set for the nut body 14 of the nut 10. In the controller 42, when the settling torque Tc is detected, the nut wrench 40 is controlled (formally tightened) in such a way that the detected torque T reaches the target torque Tt.
[0046] Furthermore, a delay sometimes occurs between the nut wrench 40 and the controller 42, affecting the control of the controller 42 based on the torque (measured value) detected in the nut wrench 40. Therefore, when the nut body 14 rotates, the actual torque sometimes exceeds the detected torque T (overshoot). The controller 42 preferably performs torque control that takes this overshoot into account.
[0047] exist Figure 2 In (C), a side view is used to show a schematic of a case where two nut bodies 14 are mounted on a single stud bolt 12. Additionally, in Figure 3 In the diagram, a line graph is used to represent the approximate change of the torque (fastening torque) T detected in the controller 42 with respect to time when the nut body 14 is screwed into the double-ended bolt 12.
[0048] It should be noted that, in Figure 2 In (C), a schematic diagram of the installation of one of the two nut bodies 14 (hereinafter referred to as nut body 14A) with the double-ended bolt 12 already installed is shown.
[0049] In addition, the controller 42 stops the rotation of the nut body 14 (14A, 14B) by determining that the torque T detected in the nut wrench 40 reaches the target torque Tt, or that the change in torque T or the rotation of the nut body 14 is abnormal.
[0050] Here, with the mounting component 28 fastened to the base 26 using the nut body 14A and the double-ended bolt 12, the nut body 14A is rotated using the nut wrench 40. As a result, the seat surface 20 of the nut body 14A sits on the mounting component 28, and the torque T increases, reaching the target torque Tt. The controller 42 detects the nut body 14A sitting on the mounting component 28 (seat under the required pressure) and stops the rotation of the nut body 14A. Thus, the base 26 and the mounting component 28 are fastened together with an axial force corresponding to the target torque Tt (see reference). Figure 1 and Figure 3 (solid line).
[0051] At this time, as Figure 3 As shown by the solid line, the change in torque T is gradual until the target torque Tt is reached (no abnormal torque T change was detected). Therefore, the controller 42 determines that the connection is properly tightened by the nut bodies 14, 14A. That is, if the controller 42 detects that the slope (rate of change of torque) of the change in torque T after the nut body 14 is seated is lower than a preset slope (threshold), it determines that the base 26 and the mounting component 28 are securely connected and fixed by the nut body 14 with an appropriate tightening torque.
[0052] Conversely, when the nut body 14B is installed with the nut body 14A mounted on the stud bolt 12, the support surface 20 of the nut body 14B, rotated by the nut wrench 40, abuts against the protrusion 50 of the nut body 14A. The controller 42 then detects the settling of the nut body 14B. Afterwards, the controller 42 causes the nut body 14B to continue rotating until the torque T reaches the target torque Tt.
[0053] Here, in the nut body 14 (14A, 14B), the protrusion height d of the protrusion 50 is greater than the pitch p of the stud bolt 12 (d > p). In addition, even when the protrusion 50 is subjected to pressure exceeding the pressure corresponding to the target torque Tt (target pressure Pt), it can suppress plastic deformation and elastic deformation and maintain the protrusion height d.
[0054] Therefore, the nut body 14B is tilted (see reference). Figure 2 C) The engagement between the internal thread in the inner hole 16 of the nut body 14B and the external thread in the shaft portion 24 of the stud bolt 12 is hindered by the protrusion 50 of the nut body 14A. The rotation of the nut body 14B is hindered by the protrusion 50 of the nut body 14A, thereby increasing the torque T required for the rotation of the nut body 14B.
[0055] Therefore, as Figure 3As shown by the dashed line, the torque T detected by the controller 42 increases sharply (the rate of change of torque T increases). The controller 42 stops the rotation of the nut body 14B by detecting the sharp increase in torque T (exceeding the preset rate of change), for example, by determining that a mis-tightening connection has occurred in the nut body 14B (mis-tightening connection detected).
[0056] Therefore, by forming a protrusion 50 in the nut body 14 with a protrusion height d greater than the pitch p of the double-ended bolt 12, the nut 10 can be detected by the controller 42 for accidental tightening, and accidental tightening of the nut 10 can be suppressed.
[0057] Furthermore, in the embodiment described above, it was explained that mis-tightening connections are detected based on the change (rate of change) of the torque T (tightening torque) of the nut body 14 with the protrusion 50. However, mis-tightening connections are not limited to changes in torque; changes in the rotation angle of the nut body (smaller changes in rotation angle), the time from torque settling to reaching the target torque, etc., can also be used.
[0058] For example, the controller controls the nut wrench to rotate the nut 10 (nut body 14) at the moment when the torque T reaches a predetermined torque (e.g., the lower limit a of the target torque Tt). At this time, in the controller 42, the nut body 14 is rotated at a preset rotational speed by the nut wrench 40, resulting in a high rotational speed and thus overshoot during torque changes (see reference). Figure 3 (The solid line). At this time, the controller 42 causes the nut body 14 to rotate at a constant rotational speed set so that the torque T does not exceed a predetermined torque c (a < c < b) (refer to the solid line). Figure 3 (solid line).
[0059] Here, when the nut body 14B is screwed onto the stud bolt 12 with the nut body 14A installed, the torque T changes drastically. Even if the rotation of the nut body 14B is stopped at the lower limit value c, a large overshoot will occur, causing the detected torque T to significantly exceed the predetermined torque c. Therefore, for the nut body 14B overlapping with the nut body 14A, the torque c detected due to the overshoot is set as a threshold relative to the target torque (e.g., the lower limit value a). Thus, in the controller 42, when torque c is detected, it can be determined that an incorrect tightening connection has occurred, where the nut body 14B and the nut body 14A are tightly connected by overlapping.
[0060] Furthermore, torque detection time anomalies can also be applied in the detection of incorrectly tightened connections. For example, the time from torque rise to reaching the target torque (e.g., lower limit a) differs between the initially installed nut body 14A and the nut body 14B installed with nut body 14A. For example, for nut body 14A, the time to detect seat engagement is set as t1, and the time to reach the lower limit a is set as t2; for nut body 14B overlapping with nut body 14A, the time to detect seat engagement is set as t3, and the time to reach the lower limit a is set as t4.
[0061] In this case, the time difference (t4-t3) is shorter than the time difference (t2-t1) ((t2-t1) > (t4-t3)). Therefore, in the nut body 14, by setting a threshold for the time from the detection of seat engagement (from the detection of torque rise) to the attainment of the predetermined torque, it is possible to determine whether a erroneous tightening connection has occurred and to suppress the occurrence of erroneous tightening connections.
[0062] Explanation of reference numerals in the attached figures
[0063] 10 nuts
[0064] 12 double-ended bolts
[0065] 14 (14A, 14B) Nut Body
[0066] 20 seating surfaces
[0067] 22. Top surface (the surface opposite to the sitting surface)
[0068] 24 shafts
[0069] 26. Base (the fastened structural component)
[0070] 28. Mounting components (fastened connecting parts)
[0071] 40 nut wrench
[0072] 42 controllers
[0073] 50. Protrusions (protrusions)
Claims
1. A nut structure comprising: The nut body has one axial side as a seat surface. The seat surface is rotated relative to the fastened structural member to engage with the bolt. The torque of the seat surface after it sits on the fastened structural member reaches a preset target torque, thereby fastening the fastened structural member to the bolt. and A protrusion is formed on the side of the nut body opposite to the seat surface, protruding in a direction opposite to the seat surface. Even when subjected to pressure corresponding to a torque exceeding the target torque, the protrusion maintains a protrusion height greater than the bolt pitch.