KR20240041525A - Method for determining optimal tightening torque - Google Patents

Abstract

The present invention includes a head portion, a shoulder portion extending downward from the head portion and having a smaller diameter than the head portion, and a shoulder portion extending downward from the shoulder portion and having a smaller diameter than the shoulder portion, along the outer peripheral surface. In the fastening torque measuring device used to determine the appropriate fastening torque of a shoulder bolt including a threaded portion provided with one thread, compared to the shoulder bolt, it is located between the shoulder portion and the threaded portion and has a diameter of the threaded portion. A machined shoulder bolt further including the same machined part, a washer penetrating the machined part, a load cell penetrating the machined part, and a first thread corresponding to the first thread of the threaded part of the machined shoulder bolt on the inner peripheral surface. Provided is a structure of a fastening torque measuring device including a nut provided with two threads and fastened to the threaded portion of the machined shoulder bolt, and a method for determining an appropriate fastening torque using the same.

Description

Method for determining appropriate tightening torque {METHOD FOR DETERMINING OPTIMAL TIGHTENING TORQUE}

The present invention relates to a device capable of inspecting the yield fastening torque of a shoulder bolt and a method of determining the appropriate fastening torque of the shoulder bolt using the same.

Bolts are one of the most widely used fastening means in assembling mechanical devices. A bolt provided with a male thread penetrates one or more members and can couple two or more members by being fastened to a nut or a fastening site provided with a female thread.

Figures 1 and 2 are a perspective view and a longitudinal cross-sectional view, respectively, showing a general shoulder bolt. Referring to these drawings, a general bolt is provided with a head portion 11 that has a larger diameter than the hole through which the body part penetrates, which limits insertion beyond a certain depth, and a male thread 131 that engages and engages the female thread at the fastening portion. Includes a threaded portion (13). When the thickness of the member through which the bolt penetrates is thick, a shank without threads may be provided between the head portion 11 and the thread portion 13. If the diameter of the shank part is larger than the thread part, it is called a shoulder bolt, and the shank part of the shoulder bolt is called the shoulder part (12).

On the other hand, if the degree of tightening of the bolt is excessive, yielding or breakage of the bolt may occur. In particular, automated manufacturing equipment needs to be set so that no torque exceeding a predetermined appropriate fastening torque is applied to the bolt when fastening it to the fastening site. For this purpose, a device and method for inspecting the yield fastening torque of the bolt are used as follows.

Figures 3 and 4 are a perspective view and a longitudinal cross-sectional view, respectively, showing a general fastening torque measuring device. Referring to these drawings, a general fastening torque measuring device includes a bolt (1), a washer (3), a load cell (4), and a jig (6) sequentially mounted below the head portion (11) of the bolt, and the It may include a nut (5) fastened to the threaded portion (13) of the bolt. In this case, the bottom of the head part 11 becomes a bearing surface 111, and the load cell 4 is connected to the head part 11 and the nut 5. The tensile strength between the head portion 11 and the screw portion 13 can be measured by measuring the compressive force applied to the head portion 11 and the screw portion 13. The washer 3 serves to protect the load cell 4 from the bearing surface 111.

The compressive force when the compressive force measured by applying a gradually increasing torque to the bolt 1 no longer increases can be referred to as the yield strength of the bolt 1, and the tightening torque at this time can be referred to as the yield tightening torque. there is.

Meanwhile, in determining the fastening torque of the shoulder bolt 1 as shown in FIGS. 1 and 2, it is inappropriate to use the fastening torque measuring device of FIGS. 3 and 4 as is. This is because, when actually applying the shoulder bolt 1 to a product, the bottom of the shoulder portion 12, not the bottom of the head portion 11, becomes the bearing surface. There is a risk that the yield strength of the shoulder bolt 1 may be overestimated in the above manner in which the head portion 11 becomes a bearing surface.

In addition, in the manner shown in FIGS. 3 and 4, the fastening torque of the shoulder bolt 1 is applied in a state in which the thread 131 provided on the thread portion 13 is not fully engaged with the nut 5. Since the measurement is performed with only a portion of the threads 131 fastened, there is a risk that the yield strength of the shoulder bolt 1 may be underestimated.

Therefore, there is a need for a structure for a fastening torque measuring device that can more accurately reproduce the bearing surface and fastening part of the shoulder bolt to measure and determine an accurate fastening torque, and a method for determining an appropriate fastening torque using the same.

The present invention was created against the background of the above-described prior art, and its purpose is to provide a structure of a fastening torque measuring device that can accurately implement the bearing surface and fastening portion of the shoulder bolt.

Another technical problem of the present invention is to provide a method for determining appropriate fastening torque using the fastening torque measuring device described above.

The technical problems of the present invention are not limited to the purposes mentioned above, and other purposes and advantages of the present invention that are not mentioned can be understood through the following description and will be more clearly understood by the examples of the present invention. . Additionally, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof indicated in the patent claims.

In order to solve the above problem, the present invention includes a head portion, a shoulder portion extending downward from the head portion and having a smaller diameter than the head portion, and a shoulder portion extending downward from the shoulder portion and having a diameter compared to the shoulder portion. In the fastening torque measuring device used to determine the appropriate fastening torque of a shoulder bolt including a small, threaded portion with a first thread along the outer peripheral surface, the device is located between the shoulder portion and the threaded portion, compared to the shoulder bolt, and , a machined shoulder bolt further comprising a machined portion having the same diameter as the threaded portion, a washer penetrating the machined portion, a load cell penetrating the machined portion, and a threaded portion of the machined shoulder bolt on the inner peripheral surface. A structure of a fastening torque measuring device is provided, including a second thread corresponding to the first thread and a nut fastened to the threaded portion of the machined shoulder bolt.

The load cell may be mounted lower than the washer. As a result, the load cell can be protected from being directly subjected to the bearing force applied by the machined shoulder bolt.

In order to implement a realistic bearing surface, it is desirable that the bottom surface of the washer and the shoulder portion contact each other in as much area as possible. Accordingly, the inner diameter of the washer may be equal to or larger than the diameter of the machined part, and may be smaller than the outer diameter of the shoulder part and the load cell. Preferably, the inner diameter of the washer may be the same as the diameter of the machined part. Additionally, the outer diameter of the washer may be equal to or larger than the outer diameter of the shoulder portion. Preferably, the outer diameter of the washer may be larger than the outer diameter of the shoulder portion.

The washer must be able to directly transmit the compressive force applied by the processed shoulder bolt to the load cell. Accordingly, the inner diameter of the load cell may be equal to or larger than the diameter of the machined part, and may be smaller than the outer diameter of the washer and the nut.

It is preferable that the fastening torque is measured while all sections of the first screw thread are fastened to the second screw thread. Accordingly, the length of the machined portion may be equal to or greater than the sum of the thicknesses of the washer and the load cell. Preferably, the length of the machined portion may be greater than the sum of the thicknesses of the washer and the load cell. Additionally, the thickness of the portion of the nut where the second thread is provided may be equal to or greater than the length of the thread portion of the machined shoulder bolt. Preferably, the thickness of the portion of the nut where the second thread is provided may be greater than the length of the thread portion of the machined shoulder bolt.

The machined portion may be formed by machining a portion of a lower section of the shoulder portion so that its diameter is equal to the diameter of the screw portion. However, despite the names of the machined shoulder bolt and the machined portion, the shoulder bolt may be manufactured from scratch with the machined portion, and may have a shape suitable for achieving the purpose of the present invention. If it is available, it can be manufactured in any way.

The present invention also provides a method for determining appropriate fastening torque using the fastening torque measuring device.

The method for determining an appropriate fastening torque according to the present invention may include measuring the yield fastening torque of a machined shoulder bolt and determining the appropriate fastening torque based on the yield fastening torque.

The step of measuring the yield fastening torque may be performed by measuring the torque at which yield occurs by applying gradually increasing torque to the shoulder bolt and the nut. That is, a gradually increasing torque is applied to the shoulder bolt and the nut to measure the compressive force applied to the load cell, and the time when the compressive force no longer begins to increase can be viewed as the time when the shoulder bolt yields. The torque at this time can be called the yield tightening torque.

The step of determining the appropriate fastening torque may be performed by calculating the appropriate fastening torque by multiplying the yield fastening torque by a predetermined safety factor.

The present invention uses the bottom of the shoulder portion as a bearing surface and measures the fastening torque with the screw portion fully fastened, thereby providing a structure for a fastening torque measuring device that can measure the fastening torque more accurately in a realistic environment. there is.

The present invention can also provide a method for determining appropriate fastening torque using the fastening torque measuring device described above.

In addition, the present invention may have various other effects, and these will be described in each embodiment, or the description of effects that can be easily inferred by a person skilled in the art will be omitted.

Figures 1 and 2 are a perspective view and a longitudinal cross-sectional view, respectively, showing a general shoulder bolt.
Figures 3 and 4 are a perspective view and a longitudinal cross-sectional view, respectively, showing a general fastening torque measuring device.
Figures 5 and 6 are a perspective view and a longitudinal cross-sectional view, respectively, showing a processed shoulder bolt according to an embodiment of the present invention.
Figures 7 and 8 are a perspective view and a longitudinal cross-sectional view, respectively, showing a fastening torque measuring device according to an embodiment of the present invention.
Figure 9 is a flowchart showing a method for determining appropriate fastening torque according to an embodiment of the present invention.

The above-mentioned objects, features, and advantages will be described in detail later with reference to the attached drawings, so that those skilled in the art will be able to easily implement the technical idea of the present invention. In describing the present invention, if it is determined that a detailed description of known technologies related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings. In the drawings, identical reference numerals are used to indicate identical or similar components.

Although first, second, etc. are used to describe various components, these components are of course not limited by these terms. These terms are only used to distinguish one component from another component, and unless specifically stated to the contrary, the first component may also be the second component.

Throughout the specification, unless otherwise stated, each element may be singular or plural.

Hereinafter, the “top (or bottom)” of a component or the arrangement of any component on the “top (or bottom)” of a component means that any component is placed in contact with the top (or bottom) of the component. Additionally, it may mean that other components may be interposed between the component and any component disposed on (or under) the component.

Additionally, when a component is described as being “connected,” “coupled,” or “connected” to another component, the components may be directly connected or connected to each other, but the other component is “interposed” between each component. It should be understood that “or, each component may be “connected,” “combined,” or “connected” through other components.

As used herein, singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, terms such as “consists of” or “comprises” should not be construed as necessarily including all of the various components or steps described in the specification, and some of the components or steps may include It may not be included, or it should be interpreted as including additional components or steps.

Additionally, as used herein, singular expressions include plural expressions, unless the context clearly dictates otherwise. In the present application, terms such as “consists of” or “comprises” should not be construed as necessarily including all of the various components or steps described in the specification, and some of the components or steps may include It may not be included, or it should be interpreted as including additional components or steps.

Throughout the specification, when referred to as “A and/or B”, this means A, B or A and B, unless specifically stated to the contrary, and when referred to as “C to D”, this means unless specifically stated to the contrary. Unless there is one, it means that it is C or higher and D or lower.

Throughout the specification, for convenience, the diameter of the threaded portion may mean any of the inner diameter, outer diameter, effective diameter, and valley diameter of the threaded portion.

Hereinafter, the structure of the shoulder bolt, which is the measurement object of the fastening torque measuring device according to the present invention, will be described with reference to the drawings.

Figures 1 and 2 are a perspective view and a longitudinal cross-sectional view, respectively, showing a general shoulder bolt. Referring to these drawings, the shoulder bolt 1, which is the object of measurement by the fastening torque measuring device according to the present invention, may include a head portion 11, a shoulder portion 12, and a thread portion 13.

The shoulder bolt 1 may be made of metal. In particular, the shoulder bolt 1 may be metal injection molded. However, the shoulder bolt 1 may be made of any material as long as it is made of a material that can have a certain yield or fracture strength.

The head portion 11 may have the largest diameter of the shoulder bolt 1. The head portion 11 may have a larger diameter than the inner diameter of the hole into which the shoulder bolt 1 is inserted, which may limit insertion of the shoulder bolt 1 beyond a certain depth.

The head portion 11 may be provided with a wrench hole that is recessed downward at its upper end. The wrench hole may be provided so that a general hexagon wrench can be inserted, or, despite the name, it may be provided so that a cross or flat head screwdriver or other various fastening torque providing means can be inserted.

The bottom of the head portion 11 may be formed to be flat.

The shoulder portion 12 may extend downward from the head portion 11.

The diameter of the shoulder portion 12 may be smaller than the diameter of the head portion 11.

The bottom of the shoulder portion 12 may be formed to be flat. Since the bottom surface of the shoulder portion 12 serves as a bearing surface when fastening the shoulder bolt 1, it is preferably formed flat.

The threaded portion 13 may extend downward from the shoulder portion 12.

The diameter of the threaded portion 13 may be smaller than the diameter of the shoulder portion 12. In order for the shoulder portion 12 to become a bearing surface when the shoulder bolt 1 is fastened, the diameter of the threaded portion 13 is preferably smaller than the diameter of the shoulder portion 12.

A first screw thread 131 may be provided along the outer peripheral surface of the screw portion 13.

The first thread 131 may be a male thread.

The shoulder bolt 1 may be fastened to the fastening portion having a female thread corresponding to the first thread 131 by applying a fastening torque to the head portion 11. At this time, if the fastening torque is excessive, the shoulder bolt 1 may yield or break. Yield or fracture of the shoulder bolt (1) deforms or destroys the shoulder bolt (1), preventing it from performing as designed. Therefore, it is necessary to determine the appropriate fastening torque that allows the shoulder bolt (1) to exhibit appropriate performance, and for this purpose, the structure of a fastening torque measuring device that can measure the yield fastening torque of the shoulder bolt (1) is required. do.

The present invention relates to a fastening torque measuring device used to determine the appropriate fastening torque of the shoulder bolt, and, compared to the shoulder bolt, a machined part located between the shoulder part and the screw part and having the same diameter as the screw part. A machined shoulder bolt further comprising a washer penetrating the machined portion, a load cell penetrating the machined portion, and a second thread corresponding to the first thread of the threaded portion of the machined shoulder bolt is provided on the inner peripheral surface. and provides a structure of a fastening torque measuring device including a nut fastened to the threaded portion of the processed shoulder bolt.

Hereinafter, the structure of the processed shoulder bolt will be described with reference to the drawings.

Figures 5 and 6 are a perspective view and a longitudinal cross-sectional view, respectively, showing a processed shoulder bolt according to an embodiment of the present invention. Referring to these drawings, the machined shoulder bolt 2 according to an embodiment of the present invention may additionally include a machined portion 24 compared to the shoulder bolt 1. That is, the machined shoulder bolt 2 includes a head portion 21, a shoulder portion 22, a machined portion 24, and a threaded portion 23, and the threaded portion 23 has a first thread 231. ) may include.

The machining part 24 may extend downward of the shoulder part 22.

The diameter of the machined part 24 may be the same as the diameter of the threaded part 23. When the diameter of the machined part 24 is different from the diameter of the threaded part 23, the area of the bottom surface of the shoulder part 22 is different from that of the unmachined shoulder bolt 1, so the bearing surface is also different. Measuring accurate fastening torque may become difficult.

The machined portion 24 may be formed by machining a portion of the lower end of the shoulder portion 22 so that its diameter is the same as the diameter of the threaded portion 23. However, despite the names of the machined shoulder bolt 2 and the machined portion 24, the shoulder bolt 2 may be manufactured with the machined portion 24 from the beginning, It may be manufactured in any way as long as it has a shape suitable for achieving the purpose of the present invention.

Hereinafter, the structure of the fastening torque measuring device according to an embodiment of the present invention including the processed shoulder bolt 2 will be described with reference to the drawings.

Figures 7 and 8 are a perspective view and a longitudinal cross-sectional view, respectively, showing a fastening torque measuring device according to an embodiment of the present invention. Referring to these drawings, the fastening torque measuring device according to an embodiment of the present invention may include the processed shoulder bolt (2), washer (3), load cell (4), and nut (5).

The washer 3 and the load cell 4 may have a through hole in their center. Hereinafter, the diameter of the through hole of the washer 3 and the load cell 4 is referred to as the inner diameter of the washer 3 and the load cell 4.

The washer 3 and the load cell 4 can be mounted on the machined part 24 by penetrating the machined part 24 through the through hole.

The washer 3 may be mounted so that its upper surface is in contact with the bearing surface 221 provided on the bottom of the shoulder portion 22, and the load cell 4 is mounted lower than the washer 3. It can be. This is to protect the load cell 4 from receiving bearing force directly from the bearing surface 221.

The nut 5 may be provided below the load cell 4 and fastened to the threaded portion 23.

The nut 5 may include a second thread 51 corresponding to the first thread 231, and the second thread 51 may be a female thread. The nut 5 can be fastened to the screw portion 23 by engaging the second screw thread 51 with the first screw thread.

The more the nut 5 is fastened with the threaded portion 23, the closer the distance between the nut 5 and the shoulder portion 22 becomes, so that the compressive force is applied to the washer 3 and the load cell 4. It can be inflicted.

The load cell 4 may be capable of measuring the magnitude of compressive force applied through the washer 3 and the nut 5. In particular, the load cell 4 may be capable of measuring the amount of compressive force applied by the washer 3 and the nut 5 in real time, and transmit the measured value through an electrical signal or other information transmission means. It may be capable of being transmitted to an external processing device or display device.

It is desirable that the bottom surface of the washer 3 and the shoulder portion 22 contact each other in as much area as possible so that the bearing surface 221 can have the same area as in the case of actual shoulder bolt fastening. Accordingly, the inner diameter of the washer 3 may be equal to or larger than the diameter of the machined part 24, and may be smaller than the outer diameter of the shoulder part 22 and the load cell 4. Preferably, the inner diameter of the washer 3 may be the same as the diameter of the machined part 24. Additionally, the outer diameter of the washer 3 may be equal to or larger than the outer diameter of the shoulder portion 22. Preferably, the outer diameter of the washer 3 may be larger than the outer diameter of the shoulder portion 22. As a result, the entire bottom of the shoulder portion 22 can serve as the bearing surface 221.

It is preferable that the washer (3) can directly transmit the compressive force applied by the processed shoulder bolt (2) to the load cell (4). Accordingly, the inner diameter of the load cell 4 may be equal to or larger than the diameter of the machined part 24, and may be smaller than the outer diameter of the washer 3 and the nut 5.

It is preferable that the fastening torque is measured while all sections of the first screw thread 231 are fastened to the second screw thread 51. Accordingly, the length of the machined portion 24 may be equal to or greater than the sum of the thicknesses of the washer 3 and the load cell 4. Preferably, the length of the machined portion 24 may be greater than the sum of the thicknesses of the washer 3 and the load cell 4. Additionally, the thickness of the portion of the nut 5 where the second screw thread 51 is provided may be equal to or greater than the length of the screw portion 23. Preferably, the thickness of the portion of the nut 5 where the second screw thread 51 is provided may be greater than the length of the screw portion 23. Accordingly, the entire thread portion 23 can protrude downward from the load cell 4, and the entire first thread 231 can be fastened to the second thread 51.

The present invention also provides a method for determining appropriate fastening torque using the fastening torque measuring device described above.

Figure 9 is a flowchart showing a method for determining appropriate tightening torque according to an embodiment of the present invention. Hereinafter, a method for determining appropriate fastening torque according to a preferred embodiment of the present invention will be described with reference to this.

Measure the yield tightening torque of the machined shoulder bolt (S1).

The yield fastening torque refers to the reaction force provided by the machined shoulder bolt (2) to the nut (5) and the washer (3) against tension when the machined shoulder bolt (2) yields. This may mean the size of the fastening torque applied to the processed shoulder bolt (2) when the size no longer increases.

In order to measure the yield fastening torque, gradually increasing torque is applied to the machined shoulder bolt 2 and the nut 5 and the compressive force applied to the load cell 4 is measured, but the compressive force no longer increases. A method of viewing the torque value at the point in time as the yield fastening torque may be used. The yield fastening torque of the processed shoulder bolt 2 measured in this way can be considered to be the same as the yield fastening torque of the shoulder bolt 1.

Calculate the appropriate tightening torque (S2).

The appropriate fastening torque may mean a value of fastening torque that can be expected to provide sufficient fastening strength without yielding the shoulder bolt 1 when fastening the shoulder bolt 1.

The appropriate fastening torque may be a dependent variable of a function that uses the yield fastening torque as an independent variable. For example, the appropriate fastening torque may be calculated by multiplying the yield fastening torque by a predetermined safety factor. The safety factor can be determined in various ways depending on the shape, material, and purpose of the shoulder bolt and fastening portion.

The above-described embodiments should be understood in all respects as illustrative and not restrictive, and the scope of the present invention will be indicated by the claims to be described later rather than the detailed description given above. In addition, the meaning and scope of the patent claims to be described later, as well as all changes and modifications derived from the equivalent concept, should be construed as being included in the scope of the present invention.

As described above, the present invention has been described with reference to the illustrative drawings, but the present invention is not limited to the embodiments and drawings disclosed herein, and various modifications may be made by those skilled in the art within the scope of the technical idea of the present invention. It is obvious that transformation can occur. In addition, although the operational effects according to the configuration of the present invention were not explicitly described and explained while explaining the embodiments of the present invention above, it is natural that the predictable effects due to the configuration should also be recognized.

1: Shoulder bolt
11: Head part
111: Bearing surface
12: Shoulder part
13: Threaded part
131: first thread
2: Machined shoulder bolt
21: head part
22: shoulder part
221: Bearing surface
23: Threaded portion
231: first thread
24: Mechanical Engineering Department
3: Washer
4: load cell
5: nut
51: Second thread
6: Jig

Claims (11)

head part;
a shoulder portion extending downward from the head portion and having a smaller diameter than the head portion; and
A screw portion extending downward from the shoulder portion, having a smaller diameter than the shoulder portion, and having a first screw thread along the outer peripheral surface; a fastening torque measuring device used to determine an appropriate fastening torque of a shoulder bolt including a Because,
Compared to the shoulder bolt, a processed shoulder bolt is located between the shoulder portion and the threaded portion and further includes a machined portion having the same diameter as the threaded portion;
a washer penetrating the machining part;
a load cell penetrating the machining unit; and
A fastening torque measuring device comprising: a second thread corresponding to the first thread of the threaded portion of the machined shoulder bolt, and a nut fastened to the threaded portion of the machined shoulder bolt.
In claim 1,
A fastening torque measuring device wherein the load cell is mounted lower than the washer.
In claim 2,
A fastening torque measuring device wherein the inner diameter of the washer is equal to or larger than the diameter of the machined part and is smaller than the outer diameters of the shoulder part and the load cell.
In claim 3,
A fastening torque measuring device wherein the internal diameter of the load cell is equal to or larger than the diameter of the machined part and is smaller than the external diameter of the washer and the nut.
In claim 1,
A fastening torque measuring device wherein the outer diameter of the washer is equal to or larger than the outer diameter of the shoulder portion.
In claim 1,
A fastening torque measuring device wherein the length of the machined portion is equal to or greater than the sum of the thicknesses of the washer and the load cell.
In claim 6,
A fastening torque measuring device wherein the thickness of the portion of the nut where the second thread is provided is equal to or greater than the length of the threaded portion of the machined shoulder bolt.
In claim 1,
A fastening torque measuring device wherein the machined portion is formed by machining a lower portion of the shoulder portion so that its diameter is equal to the diameter of the screw portion.
In a method for determining an appropriate tightening torque of the shoulder bolt using the tightening torque measuring device of claims 1 to 8,
Measuring the yield fastening torque of the machined shoulder bolt; and
A method for determining an appropriate fastening torque, comprising: determining an appropriate fastening torque based on the yield fastening torque.
In claim 9,
The step of measuring the yield fastening torque is performed by measuring the torque at which yield occurs by applying gradually increasing torque to the shoulder bolt and the nut.
In claim 9,
The determining step of the appropriate fastening torque is performed by calculating the appropriate fastening torque by multiplying the yield fastening torque by a predetermined safety factor.

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