JP5089740B2 - Screw member - Google Patents

Description

  The present invention is, for example, a sheet pile bracket used to hold a wall body and a mold frame at a predetermined interval when a mold frame is installed facing a wall surface such as a retaining wall or a continuous underground wall. It is related with the screw member suitable for fixing the connection metal fitting.

  In order to provide a waterproof wall in a tunnel or underpass, a concrete wall is formed along a soil pile wall made of sheet pile or H steel. When forming a concrete wall, the formwork into which concrete is poured is fixed to H steel. A screw member having a predetermined structure has been developed in order to firmly and stably fix the formwork to the H steel and perform the fixing work efficiently (Patent Document 1). This screw member has a tapping screw portion that is inserted so that a pilot hole is formed in an iron wall surface and a tap is formed in the pilot hole, and supports a concrete mold (see Patent Document 1).

Japanese Patent No. 2782179

[Means described in claims]
A lower hole 16 is formed in an iron wall surface, and a tool hook portion 19 for mounting an electric tool to be used supported by an operator is provided, and the lower hole 16 is inserted so as to be tapped. ,
A tapping screw portion 14 that is inserted into the lower hole 16 and that tightly integrates the screw groove 17 and the screw thread 17 cut by the screw thread 17 into the lower hole 16;
The tapping screw portion 14 is a carbon steel containing 0.20% or more and 0.24% or less carbon in iron,
The total length L of the portion of the tapping screw portion 14 in close contact with the screw groove is 5 mm or more and 10 mm or less,
The outer diameter D of the tapping screw portion 14 not including the thread 17 exceeds 11 mm and is 15 mm or less.
The height H of the thread 17 is 1.0 mm or less,
The maximum width W of the thread 17 is 0.2 mm or more and 0.4 mm or less,
The thread 17 has an isosceles triangle cross section,
An interval P (pitch) between the adjacent screw threads 17 is 1 mm or more and 2 mm or less,
The surface is quenched, and the Picker hardness in the range of 0.4 mm from the surface of the tapping screw portion 14 is 500 HV or more, and the Picker hardness in the range of 1.00 mm to the center portion from the surface of the tapping screw portion 14 Is less than 300HV,
The outer diameter D of the portion provided with the thread 17, not including the thread 17, the height H of the thread 17, the cross section of the thread 17, and the interval P between the adjacent threads 17 are as follows. Both are constant,
The screw member, wherein the tapping screw portion 14 has a circular cross section.
[Configuration of Example]
<Configuration 1>
A tapped screw portion is formed so that a pilot hole is formed in a wall surface made of iron and the lower hole is tapped. The tapped screw portion includes carbon containing 0.18% to 0.26% carbon in iron. Steel with a total length of 5 mm or more and 15 mm or less, an outer diameter not including a screw thread of 5 mm or more and 15 mm or less, a thread height of 0.6 mm or more and 1.0 mm or less, and a maximum thread width of 0.2 mm or more 0.4mm or less, the thread has a substantially triangular cross section, the apex angle is 20 degrees or more and 45 degrees or less, and the interval (pitch) between adjacent threads is 1 mm or more and 2 mm or less, and the surface is quenched and includes the thread. A screw member, wherein a hardened layer having a hardness of at least twice the hardness of the central portion is provided in a range of 0.4 mm from the surface of the non-tapping screw portion.

The following configurations are means for solving the above-described problems.
<Configuration 1>
A lower hole is formed in an iron wall surface, and the lower hole is inserted so as to be tapped with an electric tool, and has a tapping screw portion to be inserted into the lower hole, and this tapping screw portion Is a carbon steel containing 0.20% to 0.26% of carbon in iron, the total length exceeds 10 mm and is 15 mm or less, and the outer diameter not including the thread is more than 11 mm and 15 mm or less. height 0.6mm or 1.0mm or less, the maximum width of the thread is 0.2mm or 0.4mm or less, spacing (pitch between adjacent threads is at 1mm or 2mm or less, quenched the front surface, The picker hardness is 500 HV or more in the range from the surface of the tapping screw part to 0.4 mm and the picker hardness in the range from the surface of the tapping screw part to 1.00 mm to the center is 300 HV or less. The outer diameter of the portion not including the thread, the height of the thread, the cross section of the thread, and the interval between the adjacent threads are constant, and the cross section of the tapping screw portion is circular. A screw member characterized by the above.

<Effect of Configuration 1>
When a pilot hole is formed in the iron wall surface and the tap hole is inserted into the pilot hole so that the tap hole is raised, the iron screw member can be screwed and fixed at once with an electric tool. Since the dimensions and materials of each part are optimized, it can sufficiently withstand a pulling force of about 4 t.

It is a side view which shows the screw member of Example 1. FIG. It is a side view of screw member 10 which changed a part design. It is a side view which shows the state which screwed and fixed the screw member 10 to the H steel 13. FIG. 4 is a side view showing a state in which the direction of the connecting screw portion 18 is corrected by hitting the connecting screw portion 18 of the screw member 10. FIG. FIG. 4 is an enlarged longitudinal sectional view of a thread 17 portion. It is a partial expanded longitudinal cross-sectional view which shows the relationship between the screw thread 17 and the pilot hole 16 of H steel 13. FIG. (A) is a fragmentary longitudinal cross-sectional view which shows the cross-section of the screw member 10 of a comparative example, (b) is a GG cross-sectional view. It is explanatory drawing when extraction force is added to the screw member. It is a thread part longitudinal cross-sectional view of the screw member of an Example. It is intensity | strength explanatory drawing of a hardened layer part. It is the table | surface which put together the conditions of the screw member of this invention.

  Hereinafter, embodiments of the present invention will be described in detail for each example.

1 is a side view showing a screw member of Example 1. FIG.
The screw member 10 in FIG. 1A has the structure introduced in Patent Document 1. A tapping screw portion 14 is provided on the right side, a connecting screw portion 18 is provided on the left side, and a tool hook portion 19 is provided on the center. A thread 17 is provided on the outer periphery of the tapping screw portion 14. As shown in FIG. 1 (b), the screw member 10 is screwed and fixed to an H steel 13 erected along the earth retaining member 12.

  As shown in FIG.1 (c), the pilot hole 16 is previously formed in the H steel 13 with the drill which is not shown in figure. Then, an electric tool (not shown) is attached to the tool hook portion 19 and the tapping screw portion 14 is screwed into the lower hole 16 so as to be tapped. The connecting screw portion 18 penetrates the waterproof sheet 21 and the packing 20 and supports the waterproof sheet 21. Further, a connecting metal fitting 15 is attached to support a concrete mold (not shown). The waterproof pressure is applied to the waterproof sheet 21 by groundwater leaking from the earth retaining member 12 in the direction indicated by the arrow A in the figure. In addition, a load due to unillustrated formwork or concrete poured into the formwork is applied to the connection fitting 15 in the direction indicated by the arrow B.

  These forces are applied in the direction of pulling the screw member 10 out of the H steel 13. Conventionally, it has been sufficient to design the screw member 10 assuming that the pulling force is about 3 t. However, in the construction of deep underground facilities, it is desirable to withstand a higher pulling force of about 4 t. In this embodiment, in order to satisfy the requirement, the material of the screw member 10 and the dimensions of each part were optimized. If a screw member that can withstand a pulling force of about 4 t is obtained, it can be used for, for example, a waterproof sheet having a thickness of about 10 mm, a thick heat insulating material, an interior material, and the like. For this reason, the length of the connecting screw portion 18 can be set to 20 mm to 100 mm. Since the strength is improved, such a large screw member is realized.

  As described above, when a pilot hole is formed in an iron wall surface and a tap is inserted into the pilot hole, the iron screw member can be screwed and fixed at once with an electric tool. This structure is suitable for the operation of attaching a large number of screw members to the wall surface in a short time. In this embodiment, the iron wall includes a sheet pile, H steel, an iron plate, and other surfaces such as iron and iron alloy walls and columns. Since the screw member is mainly composed of the same kind of iron, it is well-fitted and can be integrated by screwing to obtain high strength. Therefore, it does not include completely foreign aluminum or wood columns or walls.

  First, the material of the screw member 10 is carbon steel. That is, iron contains 0.18% or more and 0.26% or less, preferably 0.20% or more and 0.24% or less of carbon by weight. If the carbon content is less than 0.18%, the strength is insufficient. If the carbon content exceeds 0.26%, the workability is remarkably deteriorated. This ensures the strength that can be inserted so that the tap is raised in the pilot hole of the iron material.

  Further, when considering the variation of the steel material such as H steel, the total length L shown in FIG. 1A is 15 mm or less, the dimension is preferably set to 10 mm or less and 5 mm or more. When the total length exceeds 15 mm, the heat generation amount exceeds the limit when screwed at once with the electric tool, and the tapping screw portion 14 is annealed by the heat, and the strength is lowered. To limit the generation of frictional heat to an acceptable value, the length must be limited. If the total length is less than 5 mm, the absolute strength is insufficient, so that the required strength against the pulling force of about 4 t cannot be obtained.

  The outer diameter D not including the screw thread 17 is set to 5 mm or more and 15 mm or less. When considering the variation of steel materials such as H steel, the safety zone is preferably 7 mm or more and 11 mm or less. When the outer diameter is small, the tapping screw portion itself cannot obtain a strength against a pulling force of about 4 t. If the outer diameter is too large, the reaction force when screwed with the electric tool will be significantly increased. Even if the orientation is adjusted after screwing and fixing, it is too hard to bend.

  The height H of the thread 17 is 0.6 mm or more and 1.0 mm or less, the maximum width W of the thread 17 is 0.2 mm or more and 0.4 mm or less, the thread 17 has a substantially triangular cross section, and the apex angle α is 20 The interval (pitch P) between the adjacent threads 17 is preferably in the range of 1 mm to 2 mm. When the dimension of the screw thread 17 exceeds these ranges or the pitch becomes denser, a large screwing force is required, and a burden is imposed on an operator who supports the power tool. On the other hand, when the dimension of the thread 17 is less than these, or the pitch becomes coarser than this, the strength against the sufficient pulling force cannot be obtained. The thread is generally trapezoidal, but it is desirable for the thread 17 to be sharp for tapping. However, it is assumed that a slightly rounded or chamfered top corresponds to a triangle. Moreover, it is preferable that the cross section is substantially an isosceles triangle so that it can withstand the pressure from either the left or right direction.

FIG. 2 is a side view of the screw member 10 whose design is partially changed. FIG. 3 is a side view showing a state in which the screw member 10 is screwed and fixed to the H steel 13. FIG. 4 is a side view showing a state in which the direction of the connecting screw portion 18 is corrected by hitting the connecting screw portion 18 of the screw member 10.
The screw member 10 is provided with a taper joint portion 24 between the tool hook portion 19 and the tapping screw portion 14. When the screw member 10 is screwed into the H steel 13, a slight gap is generated between the tool hook 19 and the H steel 13 by the taper joint 24. Here, it is assumed that the direction of the H steel 13 does not face a concrete mold (not shown) and is slightly inclined. At this time, the connecting screw portion 18 is hit to turn the connecting screw portion 18 in the correct direction. At this time, if there is a gap between the tool-hanging portion 19 and the H steel 13, it becomes easy to bend as shown in FIG.

  As described above, the screw member 10 is required to be made of a material that is easy to bend and does not bend to some extent when the direction is corrected after being bent to the H steel 13. The portion of the thread 17 (FIG. 1) is preferably as hard as possible, but the entire screw member is too hard to meet the requirement to bend. Therefore, the surface of the screw member 10 is quenched and a hardened layer is formed only near the surface of the screw member 10.

FIG. 5 is an enlarged longitudinal sectional view of the thread 17 portion. FIG. 6 is a partially enlarged vertical sectional view showing the relationship between the screw thread 17 and the prepared hole 16 of the H steel 13.
As already described, the height H, the maximum width W, and the interval (pitch P) of the screw thread 17 are set to the predetermined dimension range. This thread 17 threads the inner wall of the pilot hole 16 (FIG. 2) of the H steel 13. A thread groove corresponding to the thread 17 is cut in the prepared hole 16 of the H steel 13. When the thread 17 and the thread groove of the lower hole 16 are in close contact with each other, if a pulling force in the direction of arrow F is applied to the tapping screw portion 14, the thread 17 and the thread groove of the H steel 13 are respectively shown in FIG. The reaction force shown by the short arrow is added.

  The H steel into which the tapping screw portion 14 is screwed varies in strength. That is, there are sufficiently hard H steel, soft H steel, and medium hardness H steel. In the case of hard H-steel, the tapping screw portion 14 and the H-steel pilot hole 16 are in close contact with each other, and a performance capable of withstanding a pulling force of 4 t is obtained. That is, as shown in FIG. 6, a substantially uniform force is applied to the entire surface, and the lower hole 16 and the entire thread 17 can be supported by receiving the pulling force integrally.

  On the other hand, in the case of H steel softer than the standard, the portion sandwiched between the screw threads 17 in the lower hole 16 of the H steel breaks, the screw groove of the lower hole collapses, and the tapping screw portion 14 comes off at once. End up. Such H steel as a whole is insufficient in strength and unsuitable for retaining walls and is rarely used. However, moderately hard steel with a certain degree of strength is low in cost and is likely to be used. In this case, there is a problem that the strength against the pulling force of the conventional tapping screw portion is insufficient as follows.

FIG. 7A is a partial longitudinal sectional view showing a sectional structure of the screw member 10 of the comparative example, and FIG. 7B is a GG transverse sectional view.
In order to maintain the strength of the screw member 10, as shown in FIG. 7A, surface hardening is performed to form a hardened layer 28 having an outer diameter of 10 mm and a depth of about 0.1 mm. Quench to the minimum necessary depth so that it can be bent sufficiently easily. Thus, the strength required for the screw portion to cut the screw when screwed into the prepared hole can be sufficiently maintained. As a result, as shown in (b) of the figure, the surface of the screw member 10 including the screw thread 17 is strengthened, and the core portion 30 retains flexibility. For example, the cured layer 28 portion of the skin has a Picker hardness of 650 HV, and the core portion 30 portion has about 250 HV.

FIG. 8 is an explanatory diagram when a pulling force is applied to the above structure.
As shown in the figure, in the case of medium hardness H steel, when a pulling force is applied, the portion sandwiched between the threads in the H steel pilot hole is plastically deformed. Stress is applied. Since the hardened layer by quenching is brittle, fracture occurs at the root of the thread as shown in the figure. If the entire screw member is hardened and strengthened, this problem is solved, but then the above-mentioned bending adjustment cannot be performed. In addition, cracking occurs when it is forced to bend. Therefore, the thickness of the hardened layer strengthened by quenching was optimized. That is, a hardened layer having twice or more the hardness of the central portion was provided in the range from the surface of the tapping screw portion not including the screw thread to 0.4 mm.

FIG. 9 is a vertical cross-sectional view of the thread portion of the screw member of the embodiment, and FIG.
In this example, the outer diameter of the screw member was 10 mm. Bending characteristics by adjusting the strength of the portion of 80 to 90% as seen from the cross section, with the picker hardness in the range of 1.00 mm or more, preferably 0.6 mm or more from the surface of the tapping screw section to 300 HV or less. Is held. On the other hand, surface quenching was performed so that the Picker hardness in the range from the surface of the tapping screw portion to 0.4 mm was 500 HV or more. As a result, it was found that even when used for medium-hardness H-steel and a pulling force of about 4 t was applied, the screw thread was not deformed or damaged and could withstand. The vertical axis of the graph in the figure is Picker's hardness (HV), and the horizontal axis is the distance (mm) in the center direction from the surface of the screw member. A solid line is an example and a broken line is a comparative example. In the comparative example, the screw thread broke off and the screw member fell off at 3.5 t.

FIG. 11 is a table summarizing the conditions of the screw member of the present invention.
In each case, the constraints such as dimensions are indicated by solid lines. The thick line part is the range of the safety zone when considering the variation of the steel material. Within this range, a pulling-out force that can withstand 4 t could be realized. As described above, a screw member having a tapping screw portion that is inserted so as to form a pilot hole in an iron wall surface and be tapped in the pilot hole is designed to have a predetermined size range, so that screwing with an electric tool can be performed. We were able to obtain something that was not affected by frictional heat. In addition, by adjusting the thickness of the hardened layer by surface quenching, a screw member that can withstand a high pulling force of 4 t while allowing bending after attachment was realized.

12 Earth retaining 13 H steel 14 Tapping screw portion 15 Connecting metal fitting 16 Pilot hole 17 Screw thread 18 Connecting screw portion 19 Tool hook portion 20 Packing 21 Waterproof sheet 24 Tapered joint portion 28 Hardened layer 30 Core portion

Claims (1)

A lower hole 16 is formed in an iron wall surface, and a tool hook portion 19 for mounting an electric tool to be used supported by an operator is provided, and the lower hole 16 is inserted so as to be tapped. ,
A tapping screw portion 14 that is inserted into the lower hole 16 and that tightly integrates the screw groove 17 and the screw thread 17 cut by the screw thread 17 into the lower hole 16;
The tapping screw portion 14 is a carbon steel containing 0.20% or more and 0.24% or less carbon in iron,
The total length L of the portion of the tapping screw portion 14 in close contact with the screw groove is 5 mm or more and 10 mm or less,
The outer diameter D of the tapping screw portion 14 not including the thread 17 exceeds 11 mm and is 15 mm or less.
The height H of the thread 17 is 1.0 mm or less,
The maximum width W of the thread 17 is 0.2 mm or more and 0.4 mm or less,
The thread 17 has an isosceles triangle cross section,
An interval P (pitch) between the adjacent screw threads 17 is 1 mm or more and 2 mm or less,
The surface is quenched, and the Picker hardness in the range of 0.4 mm from the surface of the tapping screw portion 14 is 500 HV or more, and the Picker hardness in the range of 1.00 mm to the center portion from the surface of the tapping screw portion 14 Is less than 300HV,
The outer diameter D of the portion provided with the thread 17, not including the thread 17, the height H of the thread 17, the cross section of the thread 17, and the interval P between the adjacent threads 17 are as follows. Both are constant,
The screw member, wherein the tapping screw portion 14 has a circular cross section.

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