JP7607282B2 - Stud cutting device and deck replacement method - Google Patents

Description

The present invention relates to a stud cutting device that cuts off a stud protruding from a surface of a steel section.
The present invention also relates to a method for replacing a deck on a steel girder (shaped steel) in an existing bridge or the like (removal of the existing deck and installation of a new deck in its place), which includes cutting off studs left on the steel girder after removal of the existing deck.

The bridge is composed of, for example, multiple piers, multiple steel girders (e.g., H-shaped steel or I-shaped steel) each extending in parallel in the bridge axis direction across the multiple piers, and a precast concrete deck that is long in the direction perpendicular to the bridge axis, spanning across the multiple steel girders and aligned in the bridge axis direction.

Here, multiple studs (stud dowels) (for example, four studs) are planted on the top surface of the steel girder at regular intervals in the direction in which the steel girder extends, and are lined up at each position perpendicular to the direction in which the steel girder extends. Meanwhile, long holes (vertical through holes) are formed in the deck at positions corresponding to the multiple studs. This is so that the steel girder and deck can be integrated by placing the deck on the steel girder and positioning the multiple studs in the long holes, and then filling the holes with mortar.

Such decks may need to be replaced (removal of the existing deck and installation of a new one) due to reasons such as deterioration of the concrete after many years of use or corrosion of the internal rebar.

Patent Document 1 describes a method for replacing decks, in particular, a method for removing the existing deck from above the steel girders and scraping the top surface of the steel girders using a scraping device before installing a new deck, because removing the existing deck leaves concrete fragments and other adhering material on the top surface of the steel girders.
A handheld grinder or sander is used as the scraping device, and is incorporated into a self-propelled device.

In addition, studs are left behind on the steel girders after the existing deck has been removed.
The remaining studs are fatigued, so it is preferable to cut them off and install new studs. If there is enough space, new studs may be installed in a different location from the remaining studs, but the remaining studs must be cut off at the base so that they do not interfere with the new deck.

For this reason, workers would remove any remaining studs by cutting them off at their base using a handheld cutter (a cutting tool with a circular rotating blade).

JP 2020-176420 A

However, even with the use of cutting tools, manually removing studs takes time, and because it must be done by one person, when there are many studs, it takes a significant amount of time, leading to delays in the deck replacement work.

In view of the above circumstances, the present invention aims to provide a stud cutting device that can effectively cut off studs protruding from the surface of structural steel.

The stud cutting device of the present invention is a device for cutting studs protruding from the upper surface of the upper flange of a steel girder made of H-shaped steel and extending in the bridge axis direction, and when the bridge axis direction is the front-rear direction and the direction perpendicular to the bridge axis is the left-right direction,
a stand that is movable in a front-rear direction on the upper flange and that can be fixed to the upper flange at any position in the front-rear direction of the upper flange;
a rail supported by the base on an upper side of the base and extending in a left-right direction;
A pair of left and right moving devices that are movable in the left and right directions along the rail;
a cutting device attached to the underside of each of the pair of left and right moving devices;
Including,
The frame is
A main body is formed in a U-shape with an open lower side when viewed in the front-rear direction, the main body being composed of a top plate and a pair of left and right side plates;
a running roller rotatably attached to each of the pair of left and right side plates;
a toggle clamp attached to a lower end of each of the pair of left and right side plates;
Equipped with
The top plate is located above the upper flange,
Each of the pair of left and right side plates has an opening through which the cutting device passes,
The running rollers are capable of running on the left and right edges of the upper surface of the upper flange,
the toggle clamp includes a lever portion and a clamp portion, and the toggle clamp is configured such that the upper flange is clamped between the running roller and the clamp portion by moving the clamp portion through a rotational operation of the lever portion, thereby allowing the platform to be fixed at any position in the front-rear direction of the upper flange,
The cutting device has a circular rotary blade that rotates in a horizontal plane, and the circular rotary blade is rotated with the lower surface of the circular rotary blade positioned parallel to and close to the upper surface of the upper flange, and is fed along the rail to cut the base portion of the stud.

The present invention also provides a method for replacing a deck installed on the steel girder.
This method includes the steps of removing the existing deck from above the steel girder, and then using the aforementioned stud cutting device to cut out the studs that remain on and protrude from the upper surface of the upper flange , and after cutting out the studs, and before installing a new deck on the steel girder, welding new studs onto the upper surface of the upper flange .

According to the present invention, studs protruding from the surface of structural steel that constitutes a steel girder or the like can be suitably cut off.
This allows stud cutting work during deck replacement work to be carried out efficiently, enabling the work to progress quickly.

Schematic diagram showing an example of a bridge that will be subject to deck replacement FIG. 1 is a front view of a stud cutting device according to an embodiment of the present invention; FIG. 2 is a plan view of the stud cutting device of the same FIG. 2 is a right side view of the stud cutting device. Plan view showing stud removal FIG. 13 is a front view of a stud cutting device according to another embodiment of the present invention; FIG. 11 is a right side view of the stud cutting device according to another embodiment of the present invention;

Hereinafter, an embodiment of the present invention will be described in detail.
FIG. 1 is a schematic diagram showing an example of a bridge to be subjected to deck replacement, in which (A) is a front longitudinal cross-sectional view and (B) is a plan view.

The steel girder 1 is made of H-shaped steel (or I-shaped steel), is supported on piers (not shown), and extends in parallel in the bridge axis direction.

The deck 2 is made of precast concrete, is long in the direction perpendicular to the bridge axis, and is placed across multiple steel girders 1 (on the upper flanges of H-shaped steel). The length of each deck 2 in the bridge axis direction is about 2 m, and they are lined up in the bridge axis direction to form the roadbed.

A large number of studs (stud dowels) 3 are welded (melted) onto the steel girder 1 to integrate it with the deck 2. The studs 3 are arranged in a row of, for example, four studs per row, perpendicular to the bridge axis, and are spaced at a specified interval in the bridge axis direction.

On the other hand, the deck slab 2 has long holes 4 formed at positions corresponding to each of the four studs 3, penetrating the deck slab in the vertical direction.
Therefore, the deck 2 is placed on the steel girder 1, four studs 3 are positioned in each of the long holes 4, and then the long holes 4 are filled with mortar, thereby making it possible to integrate the steel girder 1 and the deck 2.

In a bridge that is to have its deck replaced as described above, when the existing deck 2 is removed from the steel girders 1, the studs 3 are left behind on the steel girders 1.
Since such studs 3 are fatigued, it is desirable to cut them off and melt-plant new studs before installing the new deck. If there is enough space, new studs may be melt-planted in a location separate from the remaining studs 3, but it is necessary to cut them off at the base so that the protruding length is about 2 cm or less so that the remaining studs 3 do not interfere with the new deck.

The present invention provides a stud cutting device that can be suitably used for the above-mentioned stud cutting work.

Figure 2 is a front view of a stud cutting device shown as one embodiment of the present invention, viewed in the direction of steel girder extension, Figure 3 is a plan view of the stud cutting device, and Figure 4 is a right side view of the stud cutting device. Figure 5 is a plan view showing the stud cutting process, and corresponds to the V-V arrow view of Figure 2.

The stud cutting device 5 is set on the steel girder 1 after the existing deck has been removed and the studs 3 remain on the upper surface.

In this embodiment, the steel girder 1 is an H-shaped steel beam measuring 250 mm x 250 mm. The studs 3 are arranged in a row of four on the steel girder 1 (on the upper flange of the H-shaped steel beam) perpendicular to the bridge axis, and are spaced 200 mm apart in the bridge axis direction. These dimensions are for ease of understanding, and needless to say, they are not limited to these.

The stud cutting device 5 includes a stand 10 for setting it on the steel girder 1 .
As shown in FIG. 2, the main body of the stand 10 is formed from a top plate 11 and left and right side plates 12, 12 into a U-shaped cross section that is open downward when viewed from the front (in the extending direction of the steel girder 1).

The top plate 11 is positioned above the steel girder 1.
4, the left and right side plates 12, 12 have an opening 13 in the center when viewed from the side. This is a passage for a cutting device 40, which will be described later.

Bolt shafts 14, 14 are attached to the left and right side plates 12, 12, penetrating each of them so that their axial position can be adjusted with a lock nut. Traveling rollers 15 are rotatably attached to the inner end of each bolt shaft 14. These traveling rollers 15 are wheels with outer flanges that engage with the left and right edges of the upper surface of the steel girder 1. This allows the frame 10 to move in the extension direction of the steel girder 1.

Toggle clamps 16, 16 are attached to the lower end of each of the left and right side panels 12, 12. When the lever of each toggle clamp 16 is rotated inward, the clamp portion 16a moves upward as shown in the figure, and the upper flange of the steel girder 1 is clamped between the running roller 15 and the clamp portion 16a, thereby fixing the position of the frame 10. On the other hand, when the lever is rotated outward, the clamp portion 16a moves away from the steel girder 1, and the fixed position can be released.

Therefore, the frame 10 can be moved in the extension direction of the steel girder 1 made of H-shaped steel, and can be fixed at any position with a single touch.
As the toggle clamp 16, a "Toggle Clamp TDE41F" manufactured by Misumi Group Headquarters Co., Ltd. was used.

The stud cutting device 5 also includes rails 20 with a square cross section that are supported by the frame 10 and extend to both sides of the frame 10 in a direction perpendicular to the extension direction of the steel girder 1 and parallel to the upper surface of the steel girder 1.
In order to support the rail 20, a support plate 17 is erected and supported in the center of the top plate 11 of the stand 10, and the rail 20 is supported by the support plate 17 at its longitudinal center and extends to the left and right of the support plate 17.

Rack gears 22, 22 are attached to the left and right undersides of the rail 20 along the longitudinal direction of the rail 20.

The stud cutting device 5 also includes moving devices 30, 30 that can move along the rail 20 on the left and right sides of the rail 20, and cutting devices 40, 40 that are supported by these moving devices 30, 30 and can move together with them.

Each moving device 30 includes a carriage 31 and an automatic feed device 32 .
The carriage 31 has a square hole in the center of its cross section, and is slidably attached to the rail 20 .
The automatic feed device 32 is attached to the side of the carriage 31 via an appropriate mounting member.

The automatic feed device 32 has a built-in feed motor (not shown), a pinion shaft 33 that is driven by the motor via a worm gear, a worm wheel, a reduction gear mechanism, and a clutch mechanism, and a pinion gear 34 (see Figure 3) that is attached to the pinion shaft 33 and meshes with the rack gear 22 of the rail 20.

Therefore, when the built-in feed motor is activated, the pinion gear 34 of the automatic feed device 32 meshes with the rack gear 22 of the rail 20, and the automatic feed device 32 can move along the rail 20 together with the carriage 31. It is preferable to detect the load current of the feed motor and control the feed amount based on this.

The automatic feeder 32 used was a commercially available "automatic feeder EHAC-80A" manufactured by Consec Corporation. This is an automatic feeder for core drills (see JP-A-10-296574), but can be repurposed.

Each cutting device 40 is attached below the carriage 31 of the moving device 30 via an appropriate mounting member.
Therefore, the cutting device 40 can be fed in accordance with the movement of the carriage 31 along the rail 20 by the automatic feed device 32.

Each cutting device 40 has a circular rotary blade (tip saw) 42 at the tip of a main body 41 attached to the carriage 31, which is driven by a motor not shown and rotates in a horizontal plane, and the upper surface side of the circular rotary blade 42 is covered by a cover 43 (see Figure 5) except for the tip.
As the cutting device 40, a commercially available handheld "Flush Cutter DEC-51" manufactured by IKK Corporation was used.

Next, the process of removing the stud 3 using the stud removal device 5 will be described with reference mainly to Figure 5.

In FIG. 5(A), the stud cutting device 5 (its base 10) is fixed using toggle clamps 16 in a position where a pair of cutting devices 40, 40 (particularly their circular rotary blades 42, 42) on the left and right sides clamp both ends of a row of four studs 3 arranged on a steel girder 1 in a direction perpendicular to its extension direction.

From this state, the moving devices 30, 30 (automatic feed devices 32, 32) are operated to move the cutting devices 40, 40 (circular rotary blades 42, 42) onto the upper surface of the steel girder 1.
As a result, as shown in FIG. 5B, first, the outer two of the four studs 3 are cut off at their bases almost simultaneously and removed.

Then, by further moving the cutting devices 40, 40 (circular rotary blades 42, 42) inward by the automatic feed devices 32, 32, the two inner strands are cut at their roots and removed almost simultaneously, following the two outer strands, as shown in Figure 5 (C).
By cutting two studs at a time from the left and right in this way, the cutting work can be completed efficiently and in a short time. Note that in rare cases where there is an odd number of studs 3 (for example, three), cutting two studs and one stud from each side can still be completed in a short time, rather than cutting three studs from one side.

After this, the operation of the cutting devices 40, 40 (rotation of the circular rotary blades 42, 42) is stopped, the automatic feed devices 32, 32 are reversed, and the cutting devices 40, 40 (circular rotary blades 42, 42) are moved away from above the steel girder 1 as shown in Figure 5 (D).

Then, the position fixed by the toggle clamp 16 is released, and the stud cutting device 5 (its base 10) is moved in the extension direction of the steel girder 1 (i.e., in the direction in which the stud cutting work proceeds in Figures 3 and 4) by the pitch of four studs 3, and the position is again fixed using the toggle clamp 16.
This allows the next four studs 3 to be cut off.

Next, another embodiment of the present invention will be described with reference to FIGS.
FIG. 6 is a front view of a stud cutting device according to another embodiment of the present invention, and FIG. 7 is a right side view of the stud cutting device according to the same embodiment.
1 to 3 are given the same reference numerals and their explanations are omitted, and only different elements are explained.

In this embodiment, a position adjustment device (lab jack) 50 is interposed between the carriage 31 of the moving device 30 and the cutting device 40 .
Therefore, the cutting device 40 is attached below the carriage 31 of the moving device 30 via a position adjustment device 50 .

The position adjustment device 50 has an extension mechanism between the upper and lower mounting plates and can be extended and retracted in the vertical direction (height direction), thereby allowing the proximity position of the cutting device 40 (circular rotary blade 42) to the surface of the steel girder 1 to be adjusted.

The position adjustment device 50 used here is called a "precision lab jack" and is a commercially available tool used to adjust the height of equipment and supplies during research and experiments. There are various height adjustment methods, such as ratchet handle type, knob type, and jack-up type, and models equipped with a remote switch can also be operated remotely.

In this way, by using a position adjustment device 50 that is extendable and retractable between the moving device 30 (carriage 31) and the cutting device 40 (circular rotary blade 42) and adjusts the position (proximity position) of the cutting device 40 (circular rotary blade 42) relative to the surface of the steel girder 1, a pressing force is generated to prevent the cutting edge from floating when cutting the stud 3, and the stud 3 can be cut closer to the base, resulting in a cleaner cut.

Next, we will explain the method of replacing deck slabs on steel girders (shaped steel) in an existing bridge (removing the existing deck slab and installing a new one in its place), including the cutting of studs left on the steel girders after removing the existing deck slab, in the order of steps.

(1) Existing deck removal process When replacing a deck on a steel girder on an existing bridge, the existing deck is first cut off from the steel girders and then removed.

(2) Stud Removal Process After the edges of the existing deck have been cut and removed, the studs (existing studs) remaining on the steel girders and protruding from the surface are removed using the stud removing device of the present invention.

(3) New stud welding process After removing the existing stud, a new stud (new stud) is welded (welded) onto the steel girder.

(4) Rust inhibitor application process: Before or after the new stud welding process, the top surface of the steel girder is cleaned and the corners are chamfered. After that, a rust inhibitor is applied to the top surface of the steel girder.

(5) Height Adjustment Process After the rust inhibitor has dried, hard rubber is installed to adjust the height of the deck slab, and sole sponge is installed to stop leakage of non-shrink mortar from under the deck slab.

(6) New Deck Installation Process The new deck is brought in and erected. The new deck has long holes that penetrate vertically at positions corresponding to the rows of new studs. After the new studs are positioned in the long holes, the long holes are filled with mortar to integrate the steel girders and the new deck.

The above mainly describes the cutting of studs from steel girders (H-beams or I-beams) during deck replacement work, but the present invention is not limited to deck replacement work, and is not limited to H-beams or I-beams, but can be applied to the cutting of studs from various types of steel beams.

Furthermore, it goes without saying that the illustrated embodiments are merely schematic illustrations of the present invention, and that the present invention encompasses various improvements and modifications made by those skilled in the art within the scope of the claims, in addition to those directly shown in the described embodiments.
The claims as originally filed were as follows:
[Claim 1]
A device for cutting off studs protruding from a surface of a steel section, comprising:
A stand that can be moved in the extension direction of the shaped steel and can be fixed at any position;
A rail supported by the frame and extending parallel to the surface in a direction perpendicular to the extension direction of the steel section;
A moving device movable along the rail;
a cutting device supported by the moving device;
Including,
The cutting device has a circular rotary blade that is arranged parallel to and close to the surface of the steel section from which the stud protrudes and is driven to rotate, and is fed along the rail to cut off the root portion of the stud.
[Claim 2]
The studs are provided in a plurality of positions in the extension direction of the shaped steel, aligned in a direction perpendicular to the extension direction of the shaped steel,
2. The stud cutting device according to claim 1, wherein the moving device and the cutting device are provided in pairs and move inwardly from both ends of the rail.
[Claim 3]
3. The stud cutting device according to claim 1, wherein the base has a running roller that can move in the extending direction of the structural steel, and a toggle clamp that can clamp and release the structural steel with a single touch.
[Claim 4]
The stud cutting device described in any one of claims 1 to 3, characterized in that the moving device has a feed motor and a pinion gear driven by the feed motor, and moves along the rail by meshing with the pinion gear with a rack gear attached to the rail.
[Claim 5]
A stud cutting device as described in any one of claims 1 to 4, further comprising a position adjustment device located between the moving device and the cutting device, which is extendable and contractible and adjusts the position of the cutting device relative to the surface of the steel section.
[Claim 6]
A method for replacing a deck installed on a steel girder, comprising:
After removing the existing deck from above the steel girder, a step of cutting off the studs remaining on the steel girder and protruding from the surface using the stud cutting device according to any one of claims 1 to 5;
After removing the stud, before installing a new deck on the steel girder, a step of newly installing a stud on the steel girder by welding;
A method for replacing a deck slab, comprising:

1. Steel girder (H-shaped steel)
2 Deck 3 Stud 4 Slot 5 Stud cutting device 10 Stand 11 Top plate 12 Side plate 13 Opening 14 Bolt shaft 15 Travel roller 16 Toggle clamp 16a Clamp unit 17 Support plate 20 Rail 22 Rack gear 30 Movement device 31 Carriage 32 Automatic feed device 33 Pinion shaft 34 Pinion gear 40 Cutting device 41 Main body 42 Circular rotary blade 43 Cover 50 Position adjustment device (lab jack)

Claims (7)

A device for removing studs protruding from the upper surface of the upper flange of a steel girder made of H-shaped steel and extending in the bridge axis direction , in which the bridge axis direction is the front-to-back direction and the direction perpendicular to the bridge axis is the left-to-right direction,
a stand that is movable in a front-rear direction on the upper flange and that can be fixed to the upper flange at any position in the front-rear direction of the upper flange;
a rail supported by the base on an upper side of the base and extending in a left-right direction ;
A pair of left and right moving devices that are movable in the left and right directions along the rail;
a cutting device attached to the underside of each of the pair of left and right moving devices ;
Including ,
The frame is
A main body formed in a U-shape with an open lower side when viewed in the front-rear direction, the main body being composed of a top plate and a pair of left and right side plates;
a running roller rotatably attached to each of the pair of left and right side plates;
a toggle clamp attached to a lower end of each of the pair of left and right side plates;
Equipped with
The top plate is located above the upper flange,
Each of the pair of left and right side plates has an opening through which the cutting device passes,
The running rollers are capable of running on the left and right edges of the upper surface of the upper flange,
the toggle clamp includes a lever portion and a clamp portion, and the toggle clamp is configured such that the upper flange is clamped between the running roller and the clamp portion by moving the clamp portion through a rotational operation of the lever portion, thereby allowing the platform to be fixed at any position in the front-rear direction of the upper flange,
the cutting device has a circular rotary blade that rotates within a horizontal plane, and the circular rotary blade is rotated while a lower surface of the circular rotary blade is disposed parallel to and close to an upper surface of the upper flange , and is fed along the rail to cut the base portion of the stud .
Stud cutting device. The cutting device further includes a cover that covers an upper surface side of the circular rotary blade,
the left-side moving device and the cutting device attached to the underside of the left-side moving device move from the left end of the rail toward the right side when cutting off the stud;
the right-side moving device and the cutting device attached to the underside of the right-side moving device move from the right end of the rail toward the left side when cutting off the stud;
A cutout portion is formed at a right end of the cover of the cutting device attached to the lower side of the left moving device to expose the circular rotary blade,
A cutout portion for exposing the circular rotary blade is formed at the left end of the cover of the cutting device attached to the lower side of the right-side moving device.
The stud cutting device of claim 1 . When viewed from above, the diameter of the cover is larger than the diameter of the circular rotary blade;
The cutout portion has a rectangular shape extending in the left-right direction when viewed from above.
The stud cutting device of claim 2. The stud cutting device according to any one of claims 1 to 3, wherein the studs are arranged in a plurality of rows in the left-right direction at a single position in the front-to-rear direction on the upper surface of the upper flange . The stud cutting device according to any one of claims 1 to 4, wherein the moving device has a feed motor and a pinion gear driven by the feed motor, and moves along the rail by meshing with the pinion gear with a rack gear attached to the rail. A stud cutting device as described in any one of claims 1 to 5 , further comprising a position adjustment device located between the moving device and the cutting device, which is extendable and contractible in the vertical direction and adjusts the position of the circular rotary blade relative to the upper surface of the upper flange. A method for replacing a deck installed on the steel girder ,
After removing the existing deck from above the steel girder, a step of cutting off the studs remaining on the upper surface of the upper flange and protruding from the upper surface of the upper flange using a stud cutting device according to any one of claims 1 to 6;
After removing the studs and before installing a new deck on the steel girder, a step of newly installing studs on the upper surface of the upper flange by welding ;
A method for replacing a deck slab, comprising :