WO2020203259A1 - Tapping screw and fastening structure thereof - Google Patents

Abstract

Provided are a tapping screw that can be screwed with a low screwing torque, can be fastened with a high breaking torque, and can be easily manufactured, and a fastening structure thereof. In a tapping screw 10, the screw thread height of a first screw thread part 21 is a uniform screw thread height from an intermediate part 31 to a lower neck part 30, and the screw thread height of second and third screw thread parts 22 23 is a uniform screw thread height lower than that of the first screw thread part 21 in the intermediate part 31 and is the same screw thread height as the first screw thread part 21 in the lower neck part 30.

Description

Tappin screw and its fastening structure

The present invention relates to a tapping screw, in particular, a tapping screw that can screw a member to be fastened, which is another component, into a thin plate-shaped fastening material with a low screwing torque and fasten with a high breaking torque, and a fastening structure thereof.

Conventionally, as a tapping screw capable of fastening a member to be fastened to a thin plate-shaped fastening material, for example,
"A tapping screw having a head provided with an engaging portion of a rotary tool at one end of a main body screw portion to be fastened, and a tapered approach end screw portion for forming a female screw at the other end. A multi-row tapping screw characterized in that a portion is formed in a non-circular multi-thread thread and the main body thread portion is formed in a circular parallel multi-thread thread continuous with the non-circular multi-thread thread. " Is disclosed (Patent Document 1). According to this multi-row tapping screw, it is said that the contact area between the molded female screw and the main body screw portion used for fastening is large, and a large tightening breaking torque can be obtained.

Japanese Unexamined Patent Publication No. 2001-124039

However, in the multi-thread tapping screw according to Patent Document 1, in order to reduce the screwing torque at the initial stage of screwing, the approach end screw portion is formed into a non-circular multi-thread thread, and the main body screw portion is formed into the non-circular multi-thread thread. It is formed in a continuous circular parallel multi-thread thread. For this reason, the conventional tapping screw needs to be manufactured in two stages of manufacturing steps, which is troublesome to manufacture.
In particular, when an attempt is made to manufacture a tapping screw for fastening to a thin plate-shaped fastening material, the shaft portion itself becomes short, and it becomes more difficult to form a non-circular multi-thread thread. For this reason, it is difficult to form with high dimensional accuracy, and the screwing torque and the breaking torque are liable to vary, which causes a problem that stable fastening work becomes difficult.
In view of the above-mentioned problems, it is an object of the present invention to provide a tapping screw that can be screwed in with a low screwing torque, can be fastened with a high breaking torque, and is easy to manufacture, and a fastening structure thereof.

The tapping screw according to the present invention is designed to solve the above problems.
With the head
A lower part of the neck protruding from the seating surface of the head, an intermediate part continuous with the lower part of the neck and having the same diameter, a continuous part with the middle part, and more than the middle part toward the free end. It consists of a shaft part with a thin tip part,
A tapping screw having a plurality of threaded threads continuous from the tip to the lower part of the neck.
While the thread height of the first thread portion has a uniform thread height from the middle portion to the lower part of the neck,
The thread height of the thread portion other than the first thread portion has a uniform thread height lower than that of the first thread portion in the middle portion, and the same thread height as the first thread portion in the lower part of the neck. It is a configuration having a screw.

According to the present invention, a plurality of threaded threads are formed from the tip of the shaft. For this reason, even when the tip of the tappin screw is inserted into the prepared hole of the thin plate-shaped fastening material for screwing work, the multiple threaded threads bite into the opening edge of the prepared hole at the same time, and the tapping screw wobbles. Is unlikely to occur. As a result, the operator can perform a stable screwing operation, and the workability is high.
Further, in the intermediate portion of the shaft portion, the thread height of the thread portion other than the first thread portion is lower than the height of the first thread portion. Therefore, in the intermediate portion of the shaft portion, the screwing work can be performed with a low screwing torque, and the workability is further improved.
Then, at the lower part of the neck of the shaft portion, the thread heights of all the thread portions have the same height dimension, so that a high breaking torque can be obtained.
Further, since the difference between the screwing torque and the breaking torque at the initial stage of fastening is large, when the screwing work is performed by the electric screwdriver, the adjustment range of the set torque value of the electric screwdriver is wide, and a convenient tapping screw can be obtained.
In particular, there is a large difference between the screwing torque generated by the screwing work in the intermediate portion and the breaking torque generated by the screwing work in the lower part of the neck. For this reason, the operator can easily feel the response that the screwing work by the electric screwdriver has been completed. As a result, over-rotation of the electric screwdriver by the operator can be prevented, and idling of the tapping screw can be prevented, so that the assembly workability is further improved.
Further, it is not necessary to form a non-circular multi-thread thread having a complicated shape as in the conventional example. Therefore, a tapping screw that is easy to manufacture, has high productivity, and has high dimensional accuracy can be manufactured, and a tapping screw having a small variation in screwing torque and breaking torque can be obtained.

In the embodiment of the present invention, the thread height of the thread portion other than the first thread portion in the intermediate portion may be 25% to 75% of the thread height of the first thread portion in the intermediate portion. ..
According to this embodiment, the screwing torque at the time of screwing work in the intermediate portion can be reduced.

In another embodiment of the present invention, an inclined portion which is a region from the thread height of the thread portion other than the first thread portion in the intermediate portion to the thread height of the first thread portion in the lower part of the neck. The length dimension in the axial direction of the shaft portion may be a distance traveled by rotating the shaft portion by 45 degrees to 315 degrees.
According to this embodiment, it is possible to secure a desired high breaking torque while ensuring a desired low screwing torque.

In another embodiment of the present invention, the length dimension of the inclined portion in the axial direction may be the distance traveled when the shaft portion is rotated by 90 degrees to 180 degrees.
According to this embodiment, it is possible to secure a desired high breaking torque while ensuring a desired low screwing torque.

In a different embodiment of the present invention, the thread heights of the thread portions other than the first thread portion may have the same thread height in the intermediate portion.
According to the present embodiment, since the threaded portion other than the first threaded portion has the same thread height in the intermediate portion, manufacturing becomes easy.

In another embodiment of the present invention, the thread heights of the thread portions other than the first thread portion may have different thread heights in the intermediate portion.
According to this embodiment, the screwing torque in the intermediate portion can be adjusted to a desired value.

As another embodiment of the present invention, it may have three threads.
According to this embodiment, three threaded threads are formed from the tip of the shaft. For this reason, even when the tip of the tapping screw is inserted into the prepared hole of the thin plate-shaped fastening material for screwing work, the three threaded threads bite into the opening edge of the prepared hole at the same time, and the tapping screw wobbles. Is unlikely to occur. As a result, the operator can perform a stable screwing operation, and the workability is high.
Further, in the intermediate portion of the shaft portion, the thread heights of the second thread portion and the third thread portion are lower than the height of the first thread portion. Therefore, in the intermediate portion of the shaft portion, the screwing work can be performed with a low screwing torque, and the workability is further improved.
Then, at the lower part of the neck of the shaft portion, the thread heights of all the thread portions have the same height dimension, so that a high breaking torque can be obtained.
Further, since the difference between the screwing torque and the breaking torque at the initial stage of fastening becomes large, when the screwing work is performed by the electric screwdriver, the adjustment range of the set torque value of the electric screwdriver is wide, and a convenient tapping screw can be obtained.
In particular, there is a large difference between the screwing torque generated by the screwing work in the intermediate portion and the breaking torque generated by the screwing work in the lower part of the neck. For this reason, the operator can easily feel the response that the screwing work by the electric screwdriver has been completed. As a result, it is possible to prevent the electric screwdriver from over-rotating by the operator and prevent the tapping screw from idling, which has the effect of further improving the assembly workability.
Further, it is not necessary to form a non-circular multi-thread thread having a complicated shape as in the conventional example. Therefore, a tapping screw that is easy to manufacture, has high productivity, and has high dimensional accuracy can be manufactured, and a tapping screw having a small variation in screwing torque and breaking torque can be obtained.

In a different embodiment of the present invention, the thread heights of the second thread portion and the third thread portion other than the first thread portion may have the same thread height in the intermediate portion.
According to the present embodiment, since the third thread portion has the same thread height in the second thread portion in the intermediate portion, manufacturing becomes easy.

In another embodiment of the present invention, the thread heights of the second thread portion and the third thread portion other than the first thread portion may have different thread heights in the intermediate portion.
According to this embodiment, the screwing torque in the intermediate portion can be adjusted to a desired value.

In a different embodiment of the present invention, the screw tip portion of the shaft portion may have a conical trapezoidal shape, a conical shape, or a dome shape.
According to the present embodiment, the shape of the tip portion of the tapping screw can be selected as needed, and the assembly workability of the screwing work is further improved.

The fastening structure of the tapping screw according to the present invention has a configuration in which the member to be fastened is fastened to the thin plate-shaped fastening material with the tapping screw described above.

According to the present invention, a plurality of threaded threads are formed from the tip of the shaft. Therefore, even when the tip of the tappin screw is inserted into the pilot hole of the substrate and the screwing operation is performed, the plurality of thread portions bite into the opening edge of the pilot hole at the same time, and the tappin screw is less likely to wobble. As a result, stable screwing work can be performed, and a fastening structure with high workability can be obtained.
Further, in the middle portion of the shaft portion, the height of the screw thread portion other than the first thread portion is lower than the height of the first thread portion, so that the screwing work can be performed with a low screwing torque. A tapping screw fastening structure with even higher performance can be obtained.
Then, at the lower part of the neck of the shaft portion, the height dimensions of all the thread portions are the same as the height of the complete thread, so that a fastening structure having a high breaking torque can be obtained.
Furthermore, since the difference between the screwing torque and the breaking torque at the initial stage of fastening is large, when the screwing work is performed with an electric screwdriver, the adjustment range of the set torque value of the electric screwdriver is wide, and a convenient tapping screw can be used. The structure is obtained.
In particular, there is a large difference between the screwing torque generated by the screwing work in the intermediate portion and the breaking torque generated by the screwing work in the lower part of the neck. For this reason, the operator can easily feel the response that the screwing work by the electric screwdriver has been completed. As a result, it is possible to prevent the electric screwdriver from over-rotating by the operator and prevent the tapping screw from idling, so that a fastening structure of the tapping screw having excellent assembly workability can be obtained.
Further, it is not necessary to form a non-circular multi-thread thread having a complicated shape as in the conventional example. Therefore, there is an effect that the manufacturing is easy, the productivity is high, the tapping screw with high dimensional accuracy can be manufactured, and the fastening structure of the tapping screw having a small variation in screwing torque and breaking torque can be obtained.

It is a perspective view which shows the 1st Embodiment of the tapping screw which concerns on this invention. It is a front view of the tapping screw shown in FIG. It is a rear view of the tapping screw shown in FIG. It is a top view of the tapping screw shown in FIG. It is a bottom view of the tapping screw shown in FIG. It is a left side view of the tapping screw shown in FIG. It is a right side view of the tapping screw shown in FIG. It is a vertical sectional view of line VIII-VIII shown in FIG. It is a vertical sectional view of IX-IX line shown in FIG. It is a cross-sectional view of X-ray shown in FIG. FIG. 2 is a cross-sectional view taken along the line XI-XI shown in FIG. FIG. 2 is a cross-sectional view taken along the line XII-XII shown in FIG. It is a graph which shows the change of the thread height of the tapping screw shown in FIG. It is a partial fracture view which shows the position of the change of the thread height shown in FIG. It is a partial fracture view which shows the change of the thread height shown in FIG. It is an upper perspective view which shows the 2nd Embodiment of the tapping screw which concerns on this invention. It is a lower perspective view which shows the 2nd Embodiment of the tapping screw which concerns on this invention. It is a front view of the tapping screw shown in FIG. It is a rear view of the tapping screw shown in FIG. It is a top view of the tapping screw shown in FIG. It is a bottom view of the tapping screw shown in FIG. It is a left side view of the tapping screw shown in FIG. It is a right side view of the tapping screw shown in FIG. FIG. 8 is a cross-sectional view taken along the line XXIV-XXIV shown in FIG. FIG. 8 is a cross-sectional view taken along the line XXV-XXV shown in FIG. FIG. 8 is a cross-sectional view taken along the line XXVI-XXVI shown in FIG. It is a vertical sectional view of line XXVII-XXVII shown in FIG. It is a vertical sectional view of line XXVIII-XXVIII shown in FIG. It is a graph which shows the change of the thread height of the tapping screw shown in FIG. It is a perspective view which shows the 3rd Embodiment of the tapping screw which concerns on this invention. It is a front view of the tapping screw shown in FIG. It is a vertical sectional view of the tapping screw shown in FIG. It is a chart which shows the measurement result of Example 1 which concerns on a tapping screw shown in FIG. 16 and Comparative Example 1. FIG. 3 is a graph of Example 1 shown in FIG. 33. It is a graph of the comparative example 1 shown in FIG. 33. It is a figure which shows the measurement result of Examples 2, 3 and 4 which concerns on the tapping screw shown in FIG. It is a chart which shows the measurement result of the comparative example 2, 3 and 4. It is a graph of Example 2 shown in FIG. It is a graph of the comparative example 2 shown in FIG. 37. It is a graph of Example 3 shown in FIG. It is a graph of the comparative example 3 shown in FIG. 37. It is a graph of Example 4 shown in FIG. It is a graph of the comparative example 4 shown in FIG. 37. It is a figure which shows the measurement result of Examples 5, 6 and 7 which concerns on the tapping screw shown in FIG. It is a chart which shows the measurement result of the comparative examples 5, 6 and 7. It is a graph which shows Example 5 shown in FIG. 44. It is a graph which shows the comparative example 5 shown in FIG. 45. It is a graph which shows the Example 6 shown in FIG. 44. It is a graph which shows the comparative example 6 shown in FIG. 45. It is a graph which shows the Example 7 shown in FIG. 44. It is a graph which shows the comparative example 7 shown in FIG. 45. It is a chart which shows the measurement result of Example 8, 9, 10, 11, 12 which concerns on a tapping screw shown in FIG. It is a chart which shows the measurement result of the comparative example 8, 9, 10, 11, 12. It is a graph of Example 8 shown in FIG. 52. It is a graph of the comparative example 8 shown in FIG. 53. FIG. 5 is a graph of Example 9 shown in FIG. 52. It is a graph of the comparative example 9 shown in FIG. 53. FIG. 5 is a graph of Example 10 shown in FIG. 52. FIG. 5 is a graph of Comparative Example 10 shown in FIG. 53. FIG. 5 is a graph of Example 11 shown in FIG. 52. It is a graph of the comparative example 11 shown in FIG. 53. FIG. 5 is a graph of Example 12 shown in FIG. 52. It is a graph of the comparative example 12 shown in FIG. 53.

An embodiment of the tapping screw according to the present invention will be described with reference to the accompanying drawings of FIGS. 1 to 32.
As shown in FIGS. 1 to 15, the tapping screw according to the first embodiment is applied to the three tapping screws 10, and has a head portion 11 of a truss head with a cross-shaped hole and a shaft portion 20. are doing.

As shown in FIG. 2, the head portion 11 has a cross-shaped screw hole 12 on its upper surface that can be tightened with a cross-shaped screwdriver, and a shaft portion 20 projects from the center of the seating surface 13.
The shape of the head 11 may be, for example, a countersunk head, a round countersunk head, a truss head, a pan head, a hexagonal head, or a washer head.
Further, the head portion 11 may be provided with, for example, a sliding hole, a plus / minus hole, a square hole, a hexagonal hole, or a star-shaped hole.

As shown in FIGS. 2 to 9, the shaft portion 20 extends from the center of the seat surface 13 of the head portion 11, and has three first, first, second, and third thread portions 21 on the surface thereof. 22 and 23 are formed. Then, as shown in FIGS. 13 to 15, the shaft portion 20 is divided into a lower neck portion 30, an intermediate portion 31, and a tip portion 32. The lower part of the neck 30 is a region where the thread heights of the first, second, and third thread portions 21, 22, and 23 are aligned at the same height. The intermediate portion 31 is a region in which the thread heights of the second and third thread portions 22 and 23 are lower than the thread heights of the first thread portion 21. The tip portion 32 is a region where the first, second, and third thread portions 21, 22, and 23 begin to be formed.
The screw tip portion 24 located at the free end of the shaft portion 20 has a conical trapezoidal shape. However, the screw tip portion 24 is not limited to the conical trapezoidal shape, and may be, for example, a conical shape or a dome shape, and can be appropriately selected as needed.

As shown in FIG. 13, the first thread portion 21 starts to be formed from the tip portion 32, forms a complete thread at the intermediate portion 31 of the shaft portion 20, and has the same thread height up to the vicinity of the bearing surface 13. There is.

Like the first thread portion 21, the second thread portion 22 and the third thread portion 23 start to be formed from the tip portion 32, and the intermediate portion is 25% to 75% of the thread height of the first thread portion. It is formed at the thread height of. This is because if it is less than 25%, the guide effect cannot be obtained, and if it exceeds 75%, the mechanical resistance at the time of screwing becomes large and the desired low screwing torque cannot be obtained. The second thread portion 22 and the third thread portion 23 are formed at the lower part of the neck 30 at the same thread height as the first thread portion 21. This is to secure a desired breaking torque.

The length dimension of the lower neck portion 30 can be appropriately determined by the thickness dimension of the thin plate-shaped fastening material to be fastened and the member to be fastened.

More specifically, for example, in the case of a three-threaded tapping screw having an outer diameter of 4 mm and a shaft length of 8 mm, the position where the first thread portion 21 forms a complete thread is the seat surface of the head 11. It is set to 13 to 5.94 mm. Further, the second thread portion 22 and the third thread portion 23 are between the intermediate portion 31, that is, the position separated from the seat surface 13 by 5.94 mm and the position separated from the seat surface by 2.14 mm. It has a thread height lower than that of the first thread portion 21. Further, the second thread portion 22 and the third thread portion 23 have the same thread height as the first thread portion 21 at the lower neck portion 30 starting from a position 2.14 mm from the seat surface.

In particular, the inclined portion 33 shown in FIGS. 13 and 14 shows a region from the thread height in the intermediate portion 31 to the thread height in the lower neck 30. The length dimension of the inclined portion 33 in the axial direction is the distance traveled when the shaft portion 20 is rotated by 45 degrees to 315 degrees, preferably 90 degrees to 180 degrees. This is because if it is less than 45 degrees, the desired low screwing torque cannot be obtained, and if it exceeds 315 degrees, the desired high breaking torque cannot be obtained.
Then, as shown in FIG. 13, the inclination angle of the inclined portion 33 is the intermediate portion between the second and third threaded portions 22 and 23 according to the thickness of the thin plate-shaped fastening material based on predetermined conditions. Even if the length dimension changes, it is preferable that it is constant.
Further, as shown in FIG. 13, the inclination angle of the inclined portion 33 changes based on predetermined conditions so that the thread heights of the second and third thread portions 22 and 23 are shown by thick dotted lines. Is also preferable to be constant.
Needless to say, the inclination angle of the inclined portion 33 may be changed based on the plate thickness of the thin plate-shaped fastening member, the diameter of the prepared hole, the desired screwing torque, the breaking torque, and the like.

The shaft portion 20 may have an outer diameter of 2 mm to 10 mm. If it is less than 2 mm, it is not practical, and if it exceeds 10 mm, a desired torque can be obtained without intentionally adjusting the shape of the three threaded threads, so that there is little need for it.

Further, the thread portion of the shaft portion 20 is not limited to the case of having three threads, and may have, for example, a case of having two threads or a case of having four threads. However, of the plurality of threaded threads, one first threaded portion 21 is a completely threaded portion having the same thread height in the intermediate portion 31 and the lower neck portion 30. The threaded portion other than the first threaded portion 21 is formed lower than the thread height of the first threaded portion 21 in the intermediate portion 31, and is the same as the first threaded portion 21 in the lower neck portion 30. It is formed at the thread height of. This is to reduce the screwing torque and secure a high breaking torque.

The lead angle of the tapping screw 10 is preferably 5 degrees to 25 degrees. This is because if the lead angle is less than 5 degrees, the valley portion of the screw cannot be sufficiently secured and the tightening strength is lowered. Further, when the lead angle exceeds 25 degrees, the load that the thread portion can withstand in the screwing direction becomes small, and the return rotation becomes easy, so that it becomes difficult to obtain the original function of the screw.

The material of the thin plate-shaped fastening material to be applied is not particularly limited, and examples thereof include cold rolled steel material (SPCC), stainless steel material (SUS), tin-plated steel material (SPTE), and light alloys such as duralumin. It is not limited to the metal material, and may be a resin reinforced plate made of glass fiber. The plate thickness of the thin plate-shaped fastening material may be, for example, 0.05 d to 0.25 d of the nominal diameter d of the tapping screw. This is because if it is less than 0.05d, the strength of the thin plate-shaped fastening material itself becomes too small, and if it exceeds 0.25d, the specificity of the present invention becomes small. For example, a tapping screw having a nominal diameter d of 4 mm can be fastened to a thin plate-shaped fastening material having a plate thickness of 1.0 mm or less.

The diameter of the pilot hole is preferably 60% to 90% of the nominal diameter d of the tapping screw. This is because if it is less than 60%, the screwing operation becomes difficult and it is not practical, and if it exceeds 90%, the desired breaking torque cannot be obtained. For example, in the case of a tapping screw having a nominal diameter d of 4 mm, a diameter of 2.4 mm to 3.6 mm is preferable.

As shown in FIGS. 16 to 29, the tapping screw 10 according to the second embodiment is applied to a three-row tapping screw 10 having an outer diameter of 4 mm, a shaft length of 6 mm, and a truss head having a cross-shaped head. is there.
Since this embodiment is almost the same as the above-described first embodiment except for the length of the shaft portion 20, the same number is added to the same portion and the description thereof will be omitted.

As shown in FIGS. 30 to 32, the tappin screw 10 according to the third embodiment is applied to the three tappin screws 10 having an outer diameter of 4 mm, a shaft length of 6 mm, and a pan head with a cross-shaped hole. is there.
This embodiment is almost the same as the above-described second embodiment except that the head portion 11 has a pan head shape. Therefore, the same parts are designated by the same numbers and the description thereof will be omitted.

(Example 1)
The fastening test of Example 1 was performed using a 3-row tapping screw (5 samples) made of SUS410 with an outer diameter of 4 mm and a shaft length of 6 mm according to the second embodiment.
The fastening conditions of Example 1 are a thin plate-shaped fastening material of cold rolled steel (SPCC) having a thickness of 0.2 mm and having a pilot hole with a diameter of 2.7 mm, and a thickness of 0. The members to be fastened of 2 mm cold rolled steel (SPCC) were overlapped. Then, a tapping screw was screwed into the pilot hole of the thin plate-shaped fastening material located below, and the screwing torque (hereinafter referred to as "DT") and the breaking torque (hereinafter referred to as "ST") were measured. The measurement result is shown in FIG. 33, and the change in torque during the fastening test is shown in the graph of FIG. 34.

(Comparative Example 1)
As Comparative Example 1, an outer diameter of 4 mm, a shaft length of 8 mm, a JIS tapping screw type 1 (single thread screw) (5 samples) was used, and a fastening test was performed under the same fastening conditions as in Example 1. The screwing torque (DT) and breaking torque (ST) were measured. The measurement result is shown in FIG. 33, and the change in torque during the fastening test is shown in the graph of FIG. 35.

As is clear from FIGS. 33 to 35, the average value of the torque difference between the screwing torque (DT) and the breaking torque (ST) according to the first embodiment is 1.44, whereas the screwing according to the comparative example 1 The average value of the torque difference between the torque (DT) and the breaking torque (ST) is 0.62. Therefore, it was found that the average value of the torque difference in Example 1 was 2.32 times the average value of the torque difference in Comparative Example. Therefore, when the tappin screw is fastened to the thin plate-shaped fastening material having a thickness of 0.2 mm with an electric screwdriver, the range of the set torque value that can be set in the electric screwdriver is wide, and it has been found that a convenient tapping screw can be obtained. ..
Further, it was found that even a short tapping screw can obtain a larger breaking torque (ST) than a long tapping screw for a thin plate-shaped fastening material, and the material can be saved.
Then, as shown in FIG. 35, it was found that in Comparative Example 1, the waveform around the breaking torque varied widely and was unstable. It is considered that this is due to the fastening at the incomplete threaded portion under the neck.

(Example 2 to Example 4)
As Example 2, a fastening test was conducted using a 3-row tapping screw (5 samples) made of SUS410, having an outer diameter of 4 mm and a shaft length of 6 mm according to the second embodiment. The fastening conditions of Example 2 are a thin plate-shaped fastening material of cold rolled steel (SPCC) having a thickness of 0.4 mm and having a pilot hole with a diameter of 2.6 mm, and a thickness of 0. The members to be fastened of 4 mm cold rolled steel (SPCC) are overlapped. Then, the tapping screw was screwed into the prepared hole of the thin plate-shaped fastening material located below, and the screwing torque (DT) and the breaking torque (ST) were measured. The measurement result is shown in FIG. 36, and the change in torque during the fastening test is shown in the graph of FIG. 38.
As Example 3, a thin plate-shaped fastening material having a prepared hole having a diameter of 2.7 mm was used, and the others were processed under the same fastening conditions as in Example 2, and the screwing torque (DT) and breaking torque (ST) were measured. .. The measurement result is shown in FIG. 36, and the change in torque during the fastening test is shown in the graph of FIG. 40.
As Example 4, a thin plate-shaped fastening material having a prepared hole having a diameter of 2.8 mm was used, and the others were processed under the same fastening conditions as in Example 2, and the screwing torque (DT) and breaking torque (ST) were measured. .. The measurement result is shown in FIG. 36, and the change in torque during the fastening test is shown in the graph of FIG. 42.

(Comparative Example 2 to Comparative Example 4)
As Comparative Example 2, an outer diameter of 4 mm, a shaft length of 8 mm, a JIS tapping screw type 1 (single thread screw) (5 samples) was used, and the other fastening tests were performed under the same conditions as in Example 2, and the screwing torque was applied. (DT) and breaking torque (ST) were measured. The measurement result is shown in FIG. 37, and the change in torque during the fastening test is shown in the graph of FIG. 39.
As Comparative Example 3, a thin plate-shaped fastening material having a prepared hole having a diameter of 2.7 mm was used, and the others were processed under the same fastening conditions as in Comparative Example 2, and the screwing torque (DT) and breaking torque (ST) were measured. .. The measurement result is shown in FIG. 37, and the change in torque during the fastening test is shown in the graph of FIG. 41.
As Comparative Example 4, a thin plate-shaped fastening material having a prepared hole having a diameter of 2.8 mm was used, and the others were processed under the same fastening conditions as in Comparative Example 2, and the screwing torque (DT) and breaking torque (ST) were measured. .. The measurement result is shown in FIG. 37, and the change in torque during the fastening test is shown in the graph of FIG. 43.

As is clear from FIGS. 36 and 37, the torque difference between the screwing torque and the fastening torque according to the second embodiment is 1.78 times as large as the torque difference between the screwing torque and the fastening torque according to the comparative example 2. understood. Similarly, it was found that the ratio was 2.00 times in Example 3 and Comparative Example 3, and 1.87 times in Example 4 and Comparative Example 4. Therefore, even when a pilot hole having a different diameter is provided in a thin plate-shaped fastening material having a thickness of 0.4 mm and the tappin screw is fastened with an electric screwdriver, the second to fourth embodiments are set as the electric screwdriver. It was found that the range of set torque values that can be set is wide, and a convenient tapping screw can be obtained. From this result, it was clarified that the machining accuracy of the pilot hole is low in the field, and even if the diameter of the pilot hole varies, a highly reliable tapping screw without fastening failure can be obtained.
Further, it was found that even a short tapping screw can obtain a larger breaking torque (ST) than a long tapping screw for a thin plate-shaped fastening material, and the material can be saved.

(Examples 5 to 7)
As Example 5, a fastening test was performed using a 3-row tapping screw (5 samples) made of SUS410, having an outer diameter of 4 mm and a shaft length of 6 mm according to the second embodiment. The fastening condition of Example 5 is that a thin plate-shaped fastening material of cold rolled steel (SPCC) having a thickness of 0.6 mm and having a prepared hole with a diameter of 3.0 mm has a prepared hole with a diameter of 4.5 mm and a thickness of 0. The members to be fastened of 4 mm cold rolled steel (SPCC) are overlapped. Then, the tapping screw was screwed into the prepared hole of the thin plate-shaped fastening material located below, and the screwing torque (DT) and the breaking torque (ST) were measured. The measurement result is shown in FIG. 44, and the change in torque during the fastening test is shown in the graph of FIG.
As Example 6, a thin plate-shaped fastening material of cold rolled steel (SPCC) having a thickness of 0.8 mm and having a pilot hole with a diameter of 3.0 mm was used. Other than that, the screwing torque (DT) and the breaking torque (ST) were measured under the same fastening conditions as in Example 5 described above. The measurement result is shown in FIG. 44, and the change in torque during the fastening test is shown in the graph of FIG. 48.
As Example 7, a thin plate-shaped fastening material of a cold-rolled steel material (SPCC) having a thickness of 1.0 mm and having a pilot hole with a diameter of 3.0 mm was used. Other than that, the screwing torque (DT) and the breaking torque (ST) were measured under the same fastening conditions as in Example 5 described above. The measurement result is shown in FIG. 44, and the change in torque during the fastening test is shown in the graph of FIG.

(Comparative Example 5 to Comparative Example 7)
As Comparative Example 5, a fastening test was conducted using an outer diameter of 4 mm, a shaft length of 8 mm, and a JIS tapping screw type 1 (single thread screw) (5 samples). The screwing torque (DT) and breaking torque (ST) were measured under the same fastening conditions as in Example 5. The measurement result is shown in FIG. 45, and the change in torque during the fastening test is shown in the graph of FIG. 47.
As Comparative Example 6, an outer diameter of 4 mm, a shaft length of 8 mm, and a JIS tapping screw type 1 (single thread screw) (5 samples) are used, and the screwing torque (DT) is the same as in Example 6 under the same fastening conditions. And the breaking torque (ST) was measured. The measurement result is shown in FIG. 45, and the change in torque during the fastening test is shown in the graph of FIG. 49.
As Comparative Example 7, an outer diameter of 4 mm, a shaft length of 8 mm, a JIS tapping screw type 1 (single thread screw) (5 samples) is used, and the screwing torque (DT) is the same as in Example 7 under the same fastening conditions. And the breaking torque (ST) was measured. The measurement result is shown in FIG. 45, and the change in torque during the fastening test is shown in the graph of FIG. 51.

As is clear from FIGS. 44 and 45, it was found that the torque difference between the screwing torque and the fastening torque of Example 5 is 1.93 times as large as the torque difference between the screwing torque and the fastening torque of Comparative Example 5. .. Similarly, it was found that Example 6 and Comparative Example 6 were 1.87 times, and Example 7 and Comparative Example 7 were 1.34 times. Therefore, even when the pilot holes having the same diameter are provided in the thin plate-shaped fastening materials having different thicknesses and the tapping screw is fastened with the electric screwdriver, the fifth to seventh embodiments are set as the electric screwdriver. It was found that the range of set torque values that can be set is wide, and a convenient tapping screw can be obtained.
Further, it was found that even a short tapping screw can obtain a larger breaking torque (ST) than a long tapping screw for a thin plate-shaped fastening material, and the material can be saved.

Next, the usefulness of the tapping screw according to the present invention will be described.
Normally, when the tapping screw according to the fifth to seventh embodiments is fastened with an electric screwdriver, the set torque value of the electric screwdriver is a numerical value obtained by the following formula at the work site.

Set torque value = average value of screwing torque + average value of torque difference x 0.5

For example, when calculated with reference to the thin plate-shaped fastening material having a plate thickness of 0.8 mm according to Example 6,
Set torque value = 1.84 + 4.12 x 0.5 = 3.90 Nm
Will be.
Similarly, when calculated based on the thin plate-shaped fastening material having a plate thickness of 0.8 mm according to Comparative Example 6,
Set torque value = 1.32 + 2.20 x 0.5 = 2.42 N ・ m
Will be.
Then, considering ± 10% of the tightening accuracy of the electric screwdriver, the set torque value of the sixth embodiment is 3.51 N ・ m to 4.29 N ・ m.
On the other hand, the set torque value of Comparative Example 6 is 2.18 N · m to 2.66 N · m.

At the work site, the maximum value is selected as the screwing torque (DT) and the minimum value is selected as the breaking torque (ST) (the values in FIGS. 44 and 45 are hatched and shown).
As a result, if the set torque value of the electric screwdriver is set to the minimum of 3.51 Nm among the set torque values set based on the sixth embodiment, the seventh embodiment relating to the thin plate-shaped fastening material having a plate thickness of 1.0 mm. Since the screwing torque exceeds 3.22 Nm, it can be screwed in without any problem.
Further, if the maximum set torque value of the electric screwdriver is 4.29 Nm among the set torque values set based on the sixth embodiment, the fifth embodiment relating to the thin plate-shaped fastening material having a plate thickness of 0.6 mm. Since the breaking torque is smaller than 4.38 Nm, the thin plate-shaped fastening material is not damaged.

On the other hand, in Comparative Examples 5 to 7, if the minimum set torque value of the electric screwdriver is 2.18 Nm among the set torque values set with reference to Comparative Example 6, a thin plate having a plate thickness of 1.0 mm is used. Since the screwing torque of Comparative Example 7 relating to the shape fastening material is smaller than 2.46 Nm, the screwing operation cannot be performed.
Further, in Comparative Examples 5 to 7, if the maximum set torque value of the electric screwdriver is 2.66 Nm among the set torque values set based on Comparative Example 6, a thin plate having a plate thickness of 0.6 mm is used. Since the breaking torque of Comparative Example 5 relating to the shape fastening material exceeds 2.30 Nm, the thin plate shape fastening material is damaged.

In short, in the tapping screw according to Comparative Example 5 to Comparative Example 7, the difference between the screwing torque generated in the intermediate portion and the breaking torque generated in the lower part of the neck is small. Therefore, if the set torque value of the electric screwdriver is set based on the plate thickness of 0.8 mm, the electric screwdriver cannot be used for fastening the thin plate-shaped fastening material having the plate thickness of 0.6 mm and 1.0 mm. Therefore, in Comparative Examples 5 to 7, it is necessary to reset the set torque value of the electric screwdriver for each thickness of the thin plate-shaped fastening material, which is troublesome and does not provide a convenient tapping screw.
On the other hand, in the case of the tapping screw according to the fifth to seventh embodiments, the difference between the screwing torque generated in the intermediate portion and the breaking torque generated in the lower part of the neck is large. Therefore, since all the thin plate-shaped fastening members having a plate thickness of 0.6 mm to 1.0 mm can be fastened with one set torque value, it is not troublesome and a convenient tapping screw can be obtained.

From the above results, according to Examples 5 to 7, a tapping screw capable of fastening with the same set torque value even for thin plate-shaped fastening materials having a constant pilot hole diameter and different plate thicknesses. It turned out that I could get it.

(Examples 8 to 12)
As Example 8, a fastening test was conducted using a 3-row tapping screw (5 samples) made of SUS410 with an outer diameter of 4 mm and a shaft length of 6 mm according to the second embodiment. The fastening condition of Example 8 is that a thin plate-shaped fastening material of cold rolled steel (SPCC) having a diameter of 2.7 mm and a plate thickness of 0.2 mm has a prepared hole with a diameter of 4.5 mm and a thickness of 0. Overlay members to be fastened with 2 mm cold rolled steel (SPCC). Then, the tapping screw was screwed into the prepared hole of the fastening material located below, and the screwing torque (DT) and the breaking torque (ST) were measured. The measurement result is shown in FIG. 52, and the change in torque during the fastening test is shown in the graph of FIG. 54.
As Example 9, a thin plate-shaped fastening material of cold-rolled steel (SPCC) having a diameter of 2.7 mm and a plate thickness of 0.4 mm was used. Further, a cold rolled steel material (SPCC) having a plate thickness of 0.4 mm was used as the member to be fastened. Then, the other tapping screws were screwed under the same fastening conditions as in Example 8, and the screwing torque (DT) and the breaking torque (ST) were measured. The measurement result is shown in FIG. 52, and the change in torque during the fastening test is shown in the graph of FIG. 56.
As Example 10, a thin plate-shaped fastening material of a cold-rolled steel material (SPCC) having a plate thickness of 0.5 mm and having a pilot hole with a diameter of 2.7 mm was used. Then, the other tapping screws were screwed under the same fastening conditions as in Example 9, and the screwing torque (DT) and the breaking torque (ST) were measured. The measurement result is shown in FIG. 52, and the change in torque during the fastening test is shown in the graph of FIG. 58.
As Example 11, a thin plate-shaped fastening material of a cold-rolled steel material (SPCC) having a plate thickness of 0.6 mm and having a pilot hole with a diameter of 2.7 mm was used for the member to be fastened. Then, the other tapping screws were screwed under the same fastening conditions as in Example 9, and the screwing torque (DT) and the breaking torque (ST) were measured. The measurement result is shown in FIG. 52, and the change in torque during the fastening test is shown in the graph of FIG. 60.
As Example 12, a thin plate-shaped fastening material of a cold-rolled steel material (SPCC) having a plate thickness of 0.8 mm and having a pilot hole with a diameter of 2.7 mm was used. Then, the other tapping screws were screwed under the same fastening conditions as in Example 9, and the screwing torque (DT) and the breaking torque (ST) were measured. The measurement result is shown in FIG. 52, and the change in torque during the fastening test is shown in the graph of FIG. 62.

(Comparative Example 8 to Comparative Example 12)
As Comparative Example 8, an outer diameter of 4 mm, a shaft length of 8 mm, and a JIS tapping screw type 1 (single thread screw) (5 samples) were used. Then, the screwing torque (DT) and the breaking torque (ST) were measured under the same fastening conditions as in Example 8. The measurement result is shown in FIG. 53, and the change in torque during the fastening test is shown in the graph of FIG. 55.
As Comparative Example 9, an outer diameter of 4 mm, a shaft length of 8 mm, and a JIS tapping screw type 1 (single thread screw) (5 samples) were used. Then, the screwing torque (DT) and the breaking torque (ST) were measured under the same fastening conditions as in Example 9. The measurement result is shown in FIG. 53, and the change in torque during the fastening test is shown in the graph of FIG. 57.
As Comparative Example 10, an outer diameter of 4 mm, a shaft length of 8 mm, and a JIS tapping screw type 1 (single thread screw) (5 samples) were used. Then, the screwing torque (DT) and the breaking torque (ST) were measured under the same fastening conditions as in Example 10. The measurement result is shown in FIG. 53, and the change in torque during the fastening test is shown in the graph of FIG. 59.
As Comparative Example 11, an outer diameter of 4 mm, a shaft length of 8 mm, and a JIS tapping screw type 1 (single thread screw) (5 samples) were used. Then, the screwing torque (DT) and the breaking torque (ST) were measured under the same fastening conditions as in Example 11. The measurement result is shown in FIG. 53, and the change in torque during the fastening test is shown in the graph of FIG.
As Comparative Example 12, an outer diameter of 4 mm, a shaft length of 8 mm, and a JIS tapping screw type 1 (single thread screw) (5 samples) were used. Then, the screwing torque (DT) and the breaking torque (ST) were measured under the same fastening conditions as in Example 12. The measurement result is shown in FIG. 53, and the change in torque during the fastening test is shown in the graph of FIG. 63.

As is clear from FIGS. 52 and 53, it is found that the torque difference between the screwing torque and the fastening torque of Example 8 is 2.32 times larger than the torque difference between the screwing torque and the fastening torque of Comparative Example 8. It was. Similarly, Example 9 and Comparative Example 9 were 2.01 times, Example 10 and Comparative Example 10 were 1.83 times, Example 11 and Comparative Example 11 were 1.74 times, and Example 12 was compared. It was found that it was 1.61 times that of Example 12. For this reason, even when pilot holes of the same diameter are provided in thin plate-shaped fastening materials having different thicknesses and the tapping screw is fastened with an electric screwdriver, the range of set torque values that can be set in the electric screwdriver is wide and it is easy to use. It turns out that a good tapping screw is obtained.
Further, it was found that even a short tapping screw can obtain a larger breaking torque (ST) than a long tapping screw for a thin plate-shaped fastening material, and the material can be saved.

Next, as in Examples 5 to 7, the usefulness of the tapping screw according to the present invention will be described.
At the work site, when fastening the tapping screws according to the eighth to twelfth embodiments with an electric screwdriver, the set torque value of the electric screwdriver is calculated by the following formula.

Set torque value = average value of screwing torque + average value of torque difference x 0.5

For example, when calculated with reference to the thin plate-shaped fastening material having a plate thickness of 0.5 mm according to Example 10,
Set torque value = 0.66 + 2.75 x 0.5 = 2.035 N ・ m
Will be.
Similarly, when calculated based on the thin plate-shaped fastening material having a plate thickness of 0.5 mm according to Comparative Example 10,
Set torque value = 0.75 + 1.83 x 0.5 = 1.665 N ・ m
Will be.
Then, considering ± 10% of the tightening accuracy of the electric screwdriver, the range of the set torque value is 1.83 N ・ m to 2.24 N ・ m based on the tenth embodiment.
On the other hand, based on Comparative Example 10, the range of the set torque value is 1.50 N ・ m to 1.83 N ・ m.

Then, for example, the screwing torque (DT) is selected from the maximum value of Examples 9 to 11, and the breaking torque (ST) is selected from the minimum value of Examples 9 to 11 (FIG. 52). , The numerical values in Fig. 3 are shown by hatching).
As a result, among the set torque values set with reference to the tenth embodiment, even if the set torque value of the electric screwdriver is set to the minimum 1.83 Nm, the maximum screwing torque 1.41 Nm according to the eleventh embodiment is obtained. Since it exceeds, it can be screwed in.
Further, among the set torque values set with reference to the tenth embodiment, even if the set torque value of the electric screwdriver is the maximum set torque value of 2.24 Nm, the minimum breaking torque of the ninth embodiment is 2.93 Nm. Since it does not exceed the above, the thin plate-shaped fastening material is not damaged.

On the other hand, for example, in Comparative Example 9 to Comparative Example 11, among the set torque values of the electric screwdriver set based on the plate thickness of 0.5 mm, the set torque value of the electric screwdriver is set to 1.83 Nm, which is the maximum. Then, the minimum breaking torque of 1.70 Nm according to Comparative Example 9 is exceeded, and the thin plate-shaped fastening material is damaged, so that it cannot be used.

In short, in the case of the tapping screw according to Comparative Examples 9 to 10, the difference between the screwing torque generated in the intermediate portion and the breaking torque generated in the lower part of the neck is small. Therefore, if the set torque value of the electric screwdriver is set with reference to Comparative Example 10 having a plate thickness of 0.5 mm, the set torque value as it is cannot be used for the thin plate-shaped fastening material having a plate thickness of 0.4 mm according to Comparative Example 9. .. Therefore, when the tapping screw according to Comparative Example 9 is fastened to the thin plate-shaped fastening material, it is necessary to reset the set torque value of the electric screwdriver, which is troublesome and inconvenient.
On the other hand, in the case of the tapping screw according to the ninth to eleventh embodiments, the difference between the screwing torque generated in the intermediate portion and the breaking torque generated in the lower part of the neck is large. Therefore, it can be used for a thin plate-shaped fastening material having a plate thickness of 0.4 mm to 0.6 mm with one set torque value set with reference to Example 10. As a result, it was found that since it is not necessary to reset the set torque value of the electric screwdriver, it is not troublesome and a convenient tapping screw can be obtained.

From the above results, according to Examples 9 to 11, a tapping screw capable of fastening with the same set torque value even for thin plate-shaped fastening materials having a constant pilot hole diameter and different plate thicknesses. It turned out that I could get it.

The tapping screw according to the present invention is not limited to the above-mentioned 3-row tapping screw, and may be applied to, for example, a 2-row or 4-row tapping screw. Further, it is needless to say that it may be applied not only to the cross-shaped tapping screw but also to, for example, a sliding tapping screw and a hexagonal tapping screw.

10 Tappin screw 11 Head 12 Thread hole 13 Seat surface 20 Shaft part 21 1st thread part 22 2nd thread part 23 3rd thread part 24 Thread tip part 30 Lower neck 31 Intermediate part 32 Tip part 33 Inclined part

Claims (13)

1. With the head
   A lower part of the neck protruding from the seating surface of the head, an intermediate part continuous with the lower part of the neck and having the same diameter, a continuous part with the middle part, and more than the middle part toward the free end. It consists of a shaft part with a thin tip part,
   A tapping screw having a plurality of threaded threads continuous from the tip to the lower part of the neck.
   While the thread height of the first thread portion has a uniform thread height from the middle portion to the lower part of the neck,
   The thread height of the thread portion other than the first thread portion has a uniform thread height lower than that of the first thread portion in the middle portion, and the same thread height as the first thread portion in the lower part of the neck. A tapping screw characterized by having a thread.
2. The first aspect of claim 1, wherein the thread height of the thread portion other than the first thread portion in the intermediate portion is 25% to 75% of the thread height of the first thread portion in the intermediate portion. Tappin screw.
3. The axial length dimension of the inclined portion, which is the region from the thread height of the thread portion other than the first thread portion in the middle portion to the thread height of the first thread portion in the lower part of the neck, is The tapping screw according to any one of claims 1 or 2, wherein the shaft portion is rotated by 45 degrees to 315 degrees to travel a distance.
4. The tapping screw according to claim 3, wherein the length dimension of the inclined portion in the axial direction is the distance traveled when the shaft portion is rotated by 90 degrees to 180 degrees.
5. The tapping screw according to any one of claims 1 to 4, wherein the thread heights of the thread portions other than the first thread portion have the same thread height in the intermediate portion.
6. The tapping screw according to any one of claims 1 to 4, wherein the thread heights of the thread portions other than the first thread portion have different thread heights in the intermediate portion.
7. The tapping screw according to any one of claims 1 to 6, which is characterized by having a thread portion of 3 articles.
8. The tapping screw according to claim 7, wherein the thread heights of the second thread portion and the third thread portion other than the first thread portion have the same thread height in the intermediate portion.
9. The tapping screw according to claim 7, wherein the thread heights of the second thread portion and the third thread portion other than the first thread portion have different thread heights in the intermediate portion.
10. The tapping screw according to any one of claims 1 to 9, wherein the screw tip portion of the shaft portion has a conical trapezoidal shape.
11. The tapping screw according to any one of claims 1 to 9, wherein the screw tip portion of the shaft portion has a conical shape.
12. The tapping screw according to any one of claims 1 to 9, wherein the screw tip portion of the shaft portion has a dome shape.
13. The fastening structure of the tapping screw according to any one of claims 1 to 12, wherein the member to be fastened is fastened to the thin plate-shaped fastening material.

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