JP6556490B2 - Method for manufacturing torcia stud bolt - Google Patents

Description

  The present invention relates to a torcia stud bolt and a method for manufacturing the same.

As a bolt used for reinforcing steel structures such as a steel slab of an expressway, a so-called Torcia bolt such as Patent Document 1 is known.
The torcia-type bolt has a head connected to one end of a bolt body having a thread formed on the outer periphery and a pin tail connected to the other end via a small diameter portion.

In use, the bolt body is passed through a pre-formed through-hole in an existing steel structure such as a steel plate deck plate and a steel reinforcing plate in contact with the steel plate. The nuts are screwed together from the side to fasten the existing structure and the reinforcing plate.
For such a fastening operation, a double-cylinder fastening machine that includes an outer sleeve and an inner sleeve and that can be driven to rotate is used.

When the outer sleeve is rotated with the outer sleeve of the tightening machine fitted to the nut and the inner sleeve fitted to the pintail of the Torcia type high-strength bolt, tightening torque is applied to the pintail fitted to the inner sleeve. The reaction force of is loaded. When the reaction force reaches a predetermined magnitude, the pin tail is separated from the bolt body by breaking the small diameter portion.
Thus, torque management is easily performed by confirming the presence or absence of the fracture of a pin tail.

Japanese Patent No. 3930799

However, in the conventional method of reinforcing a steel structure using a torcia-type bolt, as described above, it is necessary to perform a work for forming a through-hole through which the bolt passes through the existing steel structure. Take it.
Moreover, with the formation of the through hole, the strength of the existing steel structure may be reduced.

  Therefore, the problem to be solved by the present invention is to provide a torcia-type bolt that can be reinforced without forming a through-hole through which the bolt passes through the steel structure.

  In order to solve the above-described problems, the torcia bolt according to the present invention is a stud bolt that can be welded to a steel structure.

  That is, the Torcia-type stud bolt of the present invention is connected to one end of the bolt body via a bolt body having a thread formed on the outer periphery and a small diameter portion that can be broken when a predetermined amount of torque is applied. The pin tail is connected to the other end of the bolt body, and includes a discharge portion in the center and a welded portion that has a chamfered portion on the outer periphery and can be welded to a steel structure.

In this way, if the Torcia bolt is a so-called stud bolt type, it can be fixed directly by welding to the steel structure, so there is no need for a through hole for fastening, and the work of drilling the hole can be omitted. it can.
Moreover, since a through-hole is not formed in a steel structure, there is no possibility that the intensity | strength falls.

  In the torcia stud bolt of the present invention, when the bolt body has a relatively large diameter of 18 to 22 mm, the chamfered portion has a chamfer angle of 30 to 60 degrees with respect to the axial direction of the bolt body. The chamfer length of the bolt body in the axial direction is preferably 2 to 5 mm.

If the outer circumference of the welded part is not chamfered or the chamfered size is insufficient, when the entire Torcia stud bolt is tilted when the welded part is brought into contact with the steel structure to be welded, There is a possibility that the outer periphery of the part and the steel structure physically interfere with each other, or the outer periphery of the welded part and the steel structure are excessively close to each other.
If the outer circumference of the welded part interferes with the steel structure with the entire bolt tilted, the discharge protrusion at the center of the welded part cannot be sufficiently close to the steel structure, and the arc from the discharge protrusion Will interfere with the occurrence. Moreover, if the outer periphery of the welded part and the steel structure are excessively close to each other, useless arcs may be generated from the outer periphery of the welded part.
By making the chamfering of the outer periphery of the welded portion sufficiently large as described above, interference between the outer periphery of the welded portion and the steel structure and excessive approach are prevented, and as a result, the arc is concentrated on the discharge protrusion. Therefore, poor welding is less likely to occur.

  Moreover, in the manufacturing method of the Torcia type stud bolt concerning this invention, it decided to manufacture by modifying the existing Torcia type bolt by cutting a head.

That is, the method of manufacturing the Torcia stud bolt according to the present invention includes a bolt main body having a thread formed on the outer periphery and a small diameter portion that can be broken when a predetermined amount of torque is applied to one end of the bolt main body. The method includes a step of preparing a torcia-type bolt including a connected pin tail and a head connected to the other end of the bolt body.
Further, it includes a step of cutting the head portion of the torcia-shaped bolt to form a cut surface at the other end of the bolt body.
Furthermore, it includes a step of chamfering the outer periphery of the cut surface to form a chamfered portion.
Then, the method includes a step of forming a discharge projection by making a hole in the center of the cut surface and press-fitting a sphere.

By remodeling the existing Torcia-type bolt in this way, it is not necessary to make the Torcia-type stud bolt of the present invention from the beginning, for example, by cold forging from a material such as a steel wire.
Therefore, it is not necessary to prepare a dedicated manufacturing facility, and it is possible to deal with small-scale production.

The manufacturing method of the torcia stud bolt according to the present invention may further include a step of cutting the small diameter portion and adjusting its breaking torque.
If it does in this way, according to the intensity | strength and the state of wear which are required for the steel structure used as welding object, it can adjust suitably so that a small diameter part may fracture | rupture with a desired torque.

The manufacturing method of the torcia stud bolt according to the present invention may further include a step of adjusting the strength by heat treatment.
If it does in this way, according to the intensity | strength requested | required of the steel structure used as welding object, or the state of wear, the whole intensity | strength of a volt | bolt can be adjusted suitably.

  Since the torcia-type stud bolt of the present invention is configured as described above, it is possible to reinforce the steel structure without forming a through hole through which the bolt passes.

The perspective view of the torcia type stud bolt of an embodiment (A) is a side view, (b) is a front view, and (c) is a rear view of a torcia stud bolt of an embodiment. Sectional view of a steel deck reinforced with a torcia stud bolt of an embodiment Manufacturing process diagram of torcia stud bolt of embodiment

  Hereinafter, a torcia stud bolt according to an embodiment of the present invention and a manufacturing method thereof will be described with reference to the drawings.

  As shown in FIG. 1 and FIG. 2, the torcia stud bolt 10 according to the embodiment includes a bolt body 11, a pin tail 12, and a welded portion 13, and a deck plate 2 of a steel deck 1 used for a highway, etc. Used when reinforcing existing steel structures.

For example, as shown in FIG. 3, the welded portion 13 of the torcia-type stud bolt 10 of the plurality of embodiments is connected to the lower surface of the deck plate 2 and the U-rib 2 b as a vertical rib arranged for reinforcement below the deck plate 2. Are welded to the side surfaces of each of them, and arc welding is performed using a known welding gun.
Then, each stud bolt 10 is passed through the through hole 3a of the steel reinforcing plate 3 applied from the lower surface of the deck plate 2 to the side surface of the U rib 2b, and a washer is used for the bolt main body 11 using a tightening machine. Screw the nut 20 to which 21 is attached.
In this way, the deck plate 2 or U rib 2b and the reinforcing plate 3 are fastened by the torcia-type stud bolt 10 of the embodiment.

For example, damage such as a crack running on the weld bead forming the welded portion of the deck plate 2 of the steel deck 1 and the U rib 2b due to the weight load of the vehicle passing on the pavement 2a applied to the upper surface of the deck plate 2 When this occurs, such a reinforcement method is implemented.
Since it is not necessary to form a through hole in the deck plate 2 or the like that is an object to be reinforced, labor for forming the hole can be saved. In particular, when a through hole is formed in the deck plate 2 of the steel slab 1, it is necessary to stop the vehicle and peel off the pavement 2 a on the upper surface, and then drill the hole. By changing, a great deal of labor can be reduced.
Moreover, the strength reduction of the deck plate 2 etc. accompanying formation of a through-hole can be prevented, and the steel deck 1 is of course a great merit for a steel structure that generally avoids the strength reduction.

Here, when the deck plate 2 and the reinforcing plate 3 are fastened, when a predetermined torque (reaction force) is applied, the pin tail 12 held by the inner sleeve of a known fastening machine breaks the small diameter portion 12a. And is separated from the bolt body 11.
Torque management is performed by visually confirming whether the pin tail 12 is broken or not.
In FIG. 3, for convenience of explanation, the pin tails 12 of some of the Torcia stud bolts 10 are depicted as remaining, but in reality, all the pin tails 12 are bolt bodies when the construction is finished. 11 is disconnected.

Next, with reference to FIG. 1 and FIG. 2, the detailed structure of the torcia stud bolt 10 of embodiment is demonstrated like FIG. 1 and FIG.
The bolt body 11 of the torcia stud bolt 10 of the embodiment has a cylindrical shape, and a thread 11a is formed on the outer periphery thereof.
Although the diameter of this bolt main body 11 is not specifically limited, The thing of a large diameter is preferable from a relationship with tensile strength etc., and 18-22 mm can be illustrated.
About the structure of such a bolt main body 11, it is the same as that of the conventional torcia-type bolt.

As shown in FIGS. 1 and 2, the pin tail 12 is a polygonal column shape that can be fitted to the inner sleeve of the tightening machine, and is usually a twenty-four square column shape in which peaks and valleys are alternately repeated. I am doing.
The pin tail 12 is coupled to one end of the bolt main body 11 so that the axis of the pin main body 11 coincides with the axis.
A boundary portion between the pin tail 12 and the bolt body 11 is a small-diameter portion 12 a having a smaller diameter than other portions of the pin tail 12. That is, the pin tail 12 is connected to the bolt body 11 via the small diameter portion 12a.
The structure of such a pin tail 12 is the same as that of a conventional Torcia bolt.

On the other hand, as shown in FIG. 1 and FIG.
The welded portion 13 is connected to the other end of the bolt body 11, that is, the end opposite to the end to which the pin tail 12 is connected, so that the axis of the bolt body 11 coincides with the axis.
The welded portion 13 has a chamfered portion 13a at the outer peripheral portion and a discharge projection 13b at the central portion.

More specifically, as shown in FIGS. 1 and 2, the entire outer periphery of the end face of the welded portion 13 is chamfered to form a chamfered portion 13a.
The size of the chamfered portion 13a is not particularly limited. However, when the bolt body 11 has a relatively large diameter of 18 to 22 mm, the chamfered portion 13a is preferably relatively large.
Specifically, the chamfer angle of the bolt body 11 with respect to the axial direction is preferably 30 to 60 degrees, and the chamfer length of the bolt body 11 with respect to the axial direction is preferably 2 to 5 mm. In particular, the chamfer angle is about 45 degrees. More preferably, the chamfer length is about 3 mm.
When the bolt body 11 has a large diameter, if the welded portion 13 is tilted even a little when contacting the steel structure such as the deck plate 2 to be reinforced, the outer periphery of the welded portion 13 interferes with the steel structure. There is a risk that it may become easy or excessively close to the steel structure.
As a result, it becomes difficult to generate a sufficient arc between the discharge projection 13b and the steel structure during arc welding, or a useless arc is easily generated between the outer periphery of the welded portion and the steel structure. There is a risk of failure.
For this reason, it is because it is necessary to chamfer the outer periphery of the welding part 13 largely, and to prevent the interference with the steel structure of an outer periphery, and the excessive approach with respect to a steel structure.
On the other hand, if the chamfer is excessively large, the contact area between the welded portion 13 and the steel structure is reduced, and the welding strength cannot be ensured.

Further, as shown in FIGS. 1 and 2, a discharge projection 13 b projecting in a hemispherical shape is formed at the center of the end face of the welded portion 13.
When performing arc welding, the discharge protrusion 13b functions as a location where an arc is intensively generated between the torcia stud bolt 10 of the embodiment and the steel structure such as the deck plate 2.
A method for forming the discharge protrusion 13b is not particularly limited, and it can be exemplified that a hole is formed in the center of the end face of the welded portion 13 and a metal sphere such as an aluminum sphere is press-fitted.
In the drawing, the discharge protrusion 13b is formed by such press-fitting, and the portion that does not fit in the hole of the metal sphere is softened by the heat during the press-fitting operation, and the portion overflowing from the hole is flattened. It has spread.
The shape of the discharge protrusion 13b is not particularly limited as long as it does not hinder arc generation, and may be a conical shape.

Here, the strength of the torcia-type stud bolt 10 according to the embodiment is not particularly limited, but the tensile strength is 600 to 600, which is suitable for connecting the steel structure such as the deck plate 2 and the reinforcing plate 3 by a friction bonding method. 1000 N / mm ² is preferred.
If the tensile strength is less than 600 N / mm ² , the strength may be insufficient. If the tensile strength exceeds 1000 N / mm ² , the welded portion between the stud bolt 10 and the steel structure breaks first. This is because the performance cannot be fully exhibited.
In the torcia-type stud bolt 10 used for applications that require particularly high strength such as reinforcement of the steel slab 1, it is more preferable that the tensile strength is generally as high as 800 to 1000 N / mm ² , which is generally referred to as a high strength bolt. .

In addition, the Vickers hardness of the torcia stud bolt 10 of the embodiment is not particularly limited, but it is 250 to 350 Hv because the strength and toughness are affected if it is too hard or too soft due to the relationship with the tensile strength. Can be exemplified.
Such Vickers hardness and the like can be appropriately adjusted by heat treatment (QT treatment: quenching and tempering treatment).
The composition of the torcia-type stud bolt 10 of the embodiment is not particularly limited, but can be exemplified as a carbon steel having a carbon equivalent of 0.35 to 0.45% by weight from the relationship with tensile strength, Vickers hardness, and the like. . Moreover, it is preferable that 0.0005 to 0.0020 weight% of boron is contained.

  The configuration of the torcia stud bolt 10 according to the embodiment is as described above. As an example of the manufacturing method, a method for manufacturing the torcia stud bolt according to the embodiment will be described below with reference to FIG.

  First, as shown in FIG. 4A, an existing Torcia bolt 10 ′ is prepared in which a pin tail 12 is connected to one end of a bolt body 11 via a small diameter portion 12 a and a head 14 is connected to the other end. Such an existing Torcia bolt 10 'is produced by, for example, cold forging a boron steel wire and is commercially available.

If necessary, the strength such as tensile strength and Vickers hardness is adjusted by heat-treating such an existing Torcia bolt 10 '.
Such as those tensile strength before treatment was 500 N / mm ^2, quenching of the known, to high strength can be exemplified in accordance with the tempering 800 N / mm ² and intended use by the process. Such a process can be omitted.
Further, if necessary, a known surface treatment may be applied to the existing Torcia bolt 10 'to improve the lubricity and thereby stabilize the torque coefficient, or to suppress the occurrence of rust.

Next, as shown in FIG. 4B, the head portion 14 of the existing Torcia bolt 10 ′ is cut and separated from the bolt body 11 by using a known bite.
At this time, when it is desired to adjust the length of the bolt main body 11 together, a part of the bolt main body 11 continuous to the head 14 is cut together with the head 14.
In the center portion of the cut surface thus formed, a press-fitting hole 14a is formed by drilling using a known drill or the like.

Here, if necessary, before and after the cutting process of the head 14, the small diameter part 12 a of the pin tail 12 is cut and the breaking strength of the small diameter part 12 a is adjusted according to the purpose of use.
For example, when the overall strength is excessively improved by the heat treatment described above, the breaking strength can be lowered according to the purpose of use by reducing the cross-sectional area by further reducing the diameter of the small-diameter portion 12a by cutting. Can be illustrated. Such a process can be omitted.

  Further, as shown in FIG. 4C, the outer periphery of the cut surface formed by cutting the head portion 14 of the existing Torcia bolt 10 'is chamfered by using a known tool. Thereby, the chamfered portion 13a is formed.

At the same time, a separately prepared metal sphere such as an aluminum sphere is press-fitted into the press-fitting hole 14a using a known press machine. The half of the press-fitted metal sphere protrudes from the hole to form a discharge protrusion 13b.
Prior to this press-fitting operation, operations such as bolt oil washing and degreasing may be performed as appropriate.
In this way, by modifying the existing Torcia bolt 10 ', the Torcia stud bolt 10 of the embodiment is completed.

  It is necessary to provide a dedicated facility for manufacturing the torcia stud bolt 10 of the embodiment by remodeling the existing torcia bolt 10 'which is widely used and easily available, and producing the torcia stud bolt 10 of the embodiment. In addition, it can be suitably applied to the production of small lots.

  It should be considered that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications and variations within the scope and meaning equivalent to the terms of the claims.

For example, the method for manufacturing the torcia stud bolt 10 of the embodiment is not limited to the manufacturing method of the embodiment.
Without using the existing Torcia-type bolt 10 ', a dedicated facility is prepared, and by this, cold-forging a boron steel wire or the like, a bolt without the head 14 can be directly produced from the beginning. Is possible.
Further, the order of performing each step of the manufacturing method of the embodiment is not limited to the above-described one, and for example, chamfering may be performed prior to drilling of the press-fitting hole 14a.

DESCRIPTION OF SYMBOLS 1 Steel floor slab 2 Deck plate 2a Pavement 2b U rib 3 Reinforcement plate 3a Through hole 10 Torcia type stud bolt 10 'of the embodiment Existing Torcia type bolt 11 Bolt body 11a Thread 12 Pin tail 12a Small diameter part 13 Welded part 13a Chamfer 13b Discharge projection 14 Head 14a Press-fit hole 20 Nut 21 Washer

Claims (3)

A bolt body with a thread formed on the outer periphery, a pin tail connected to one end of the bolt body via a small diameter portion that can be broken when a torque of a predetermined magnitude is applied, and connected to the other end of the bolt body Preparing a torcia-type bolt comprising:
Cutting the head of the torcia-shaped bolt to form a cut surface at the other end of the bolt body;
Chamfering the outer periphery of the cut surface to form a chamfered portion;
Forming a discharge projection by making a hole in the center of the cut surface and press-fitting a sphere. The manufacturing method of the torcia type stud bolt of Claim 1 which further includes the process of performing a cutting process to the said small diameter part, and adjusting the breaking torque. The method of manufacturing a torcia stud bolt according to claim 1 or 2 , further comprising a step of adjusting strength by heat treatment.

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