KR20200078890A - Soil reamer having three or four bit parts and three or four spiral screws, reaming methods using the same and, manufacturing methods for the same - Google Patents

Abstract

According to present invention, a reamer and a reaming method can reduce propulsion resistance and rotation resistance provided to the reamer when the soil ground is reamed and can also reduce downward deflection. Also, according to the present invention, provided is a manufacturing method of the reamer.

Description

Soil reamer having three or four bit parts and three or four spiral screws, reaming methods using the same and manufacturing methods for the same}

The present invention relates to a soil spreader and a method for expanding the soil, and more specifically, to reduce the propulsion resistance and rotational resistance received by the expander when expanding the soil, it is possible to reduce the downward deflection and also reduce the downward deflection. And its construction method. In addition, the present invention also provides a method for manufacturing such a reamer.

Sediment expansion is for excavating small-diameter tunnels on the soil and is used to bury underground pipes underground.

After the earth drilling operation, called the shooting process, the soil excavation machine is mounted on the peak of the extension rod, and after excavating the tunnel several times while towing in the opposite direction, the underground pipe is buried. In general, a conical-shaped expander is used in the earthwork expansion process, and the earthwork expansion operation is performed while pressing and rotating it.

1 is a cross-sectional view showing a conical expander for expanding the soil foundation 1, and FIG. 2 is a perspective view showing a conical expander 4.

The conical expander 4 is pulled forward while rotating by the rotational force (torque) and the traction force transmitted through the action tension rod 3. The conical shape is for minimizing the rotational force and traction required for excavation and enabling curved orbital excavation when the expander 4 is pressed along the shooting hole 2.

However, since the conical expander 4 has its head portion blocked (that is, because it is closed), the excavated soil is pushed laterally on the slope of the cone and then moves rearward, thus requiring large traction and rolling resistance. Big.

In general, the expansion process is performed while gradually increasing the diameter of the expansion through 6-8 steps. For example, when constructing a soil tunnel of 800 mm in diameter, a total of 8 processes of 200, 300, 400, 500, 600, 700, and 800 mm in diameter are required, starting with an initial 150 mm shooting process. That is, it is common to increase the diameter by about 15% to complete the tunnel diameter of 100%.

However, to shorten the air, the construction can be performed by skipping the construction step by step, but in this case, the construction area increases by 4 times, so the traction force (thrust) and torque (rotating power) also increase by 4 times. Therefore, the hydraulic performance of the press-fitting equipment must be improved four times, which leads to an increase in equipment cost. If the construction is performed with a press-fit device that does not have hydraulic performance, the construction speed of the corresponding step is slowed, which may cause air delay.

In addition, the existing air expander including the air expander 4 has a large self-weight, and thus, when excavating the soil, there is a tendency to sag downward and deflect downwardly when tunneling. Due to this lower deflection, there is a problem that a vertically elongated elliptical tunnel is formed when the construction process is repeated several times. This elliptical cross-section excavation not only extends the air, but also causes undesired ground subsidence since unnecessary over-excavation is formed on the upper side of the buried pipe even after the construction is completed. Therefore, it is advantageous to eliminate the lower deflection in terms of construction economics and safety.

The present invention has been proposed to solve the above problems, and the excavated soil can be moved rearwardly through the expander head portion, and accordingly, it is intended to provide an air expander having a small traction force and a small rotational resistance required for expansion. It has a purpose.

Another object of the present invention is to provide an air expander capable of reducing downward deflection during construction.

Another object of the present invention is to provide an expansion method using such an expansion machine.

Another object of the present invention is to provide a method for manufacturing such a reamer.

Figure 3a is a perspective view showing a reamer with a double helix screw, Figure 3b is a front view of Figure 3a.

The expander 10 includes a central shaft 11, two spiral screws 13 welded to the outer circumferential surface of the central shaft 11, and a bit 15 installed at the tip of the spiral screw 13. The two spiral screws 13 have a 180° phase difference. And, the diameter of the spiral screw 13 decreases toward the rear for excavation of a curved track.

The soil excavated by the bit 15 passes through the air expander head portion (H, the front part of the air expander), and then is transferred backward by a spiral screw 13. Therefore, the expander 10 has an advantage that the traction force required for excavation is small and the rotational resistance is small as compared to the conical expander 4. However, the air expander 10 still has a problem of downward deflection, which will be described in detail below.

Since the expander 10 has two spiral screws 13, the diameter of the spiral screw 13 gradually decreases toward the rear, as shown in FIG. 3B, the diameter D1 of the bit installation direction is in the orthogonal direction. It is larger than the diameter (D2). For example, for a 1 m diameter air expander, the diameter D1 is 1000 mm and the diameter D2 is 950 mm.

Due to the difference in diameter, deflection excavation in the downward direction proceeds more rapidly when excavating soil. 4(a) to (c), when the bit line (the line formed by arranging the bits) faces in the vertical direction, load concentration is more generated on the bottom surface of the tunnel and the outermost bit located on the bottom surface ( The gauge bit) digs the lower surface more deeply, because the diameter D2 in the left-right direction of the expander is small, so it does not prevent the expander from being deflected downward. Therefore, as over-drilling of the lower surface proceeds, the construction work is performed, and accordingly, a tunnel having an elliptical cross section elongated downward is excavated.

On the other hand, it is most advantageous to apply a constant traction force and rotational force when the air expander rotates. When a constant load is generated, excavation of the soil is most stable and rapid. However, when the two spiral screws are installed to have a phase difference of 180°, when the bit line (the line formed by arranging the bits) is leveled, only the front film is excavated, but when the bit line is vertical, the film surface and the bottom surface are excavated. Since this occurs simultaneously, the maximum rotational load occurs.

When the bit line is perpendicular to 0° as the starting point and the lowest rotation load is expressed as 1 kN·m, a pulsation phenomenon as shown in the graph of FIG. 5 occurs. In FIG. 5, the x-axis (horizontal axis) represents the rotation angle (°), and the y-axis (vertical axis) represents the rotational load (torque, kN·m) applied to the expander.

Two pulsations occur during one revolution of the air expander. The graph of FIG. 5 assumes that the load required for the lower excavation is 40% of the basic excavation load, but as the amount of deflection increases, the rotational load increases, and the pulsation phenomenon increases significantly, making operation of the equipment difficult. Therefore, as the expansion process progresses, the upper and lower widths of the pulsation phenomenon are gradually increased, making it difficult for the equipment to exhibit a certain excavation performance. The expected result of this phenomenon is expressed in FIG. 6. In FIG. 6, the x-axis (horizontal axis) represents the rotation angle (°), and the y-axis (vertical axis) represents the rotational load (torque, kN·m) of the expander. R1 (black line) represents the rotational load when the shooting hole is expanded (1st expansion), R2 (red line) represents the rotational load during the 2nd expansion, and R3 (blue line) indicates the 3rd expansion. Represents a rotating load.

As shown in Fig. 6, if the rotation load according to the expansion process increases by about 10-15% in proportion to the increase in the diameter of the excavation, the maximum value according to the pulsation phenomenon rises by 20-30% or more to put a burden on the load of the indentation equipment. do.

As described above, since the expander 10 has two spiral screws 13 and the head portion H is open, the soil excavated by the bit 15 penetrates the head portion H and then spirals. It is conveyed rearward by the screw 13 and accordingly the traction force required for excavation is small and the rotational load is small. However, the air expander 10 still has a problem of being downwardly deflected upon expansion. Therefore, it is necessary to solve these problems.

Expander according to the present invention (100) (200), the central shaft 110 is rotated while being pulled by the drive rod; Three or more spiral screws 120 installed on the outer circumferential surface of the central shaft 110; And, a bit portion 130 installed at the tip of each spiral screw 120.

Each spiral screw 120 has a constant phase angle difference from the neighboring spiral screw 120, and the bit unit 130 includes a bit 132 for excavating soil.

The head portion H of the expander 100 and 200 has an open structure in which the rest of the portion except the bit portion 130 is empty, and accordingly, the soil excavated by the bit 132 is the head portion H After passing through, it is moved to the spiral screw 120 and is moved backward by the spiral screw 120.

It is desirable for a curved tunnel excavation that the diameter of the spiral screw 120 decreases toward the rear. In addition, three of the spiral screws may be installed with a 120° phase difference or four with a 90° phase difference.

The bit unit 130 may include a base 131 and a bit 132. Base 131 is welded to the tip of the spiral screw 120 is installed in the radial direction, has a narrow width and a long length. The bit 132 may be installed at a predetermined interval on the base 131.

Among the bits 132, the outermost gauge bit is installed at the outermost portion of the base 131, and it is preferable that the gauge bits installed in each bit portion 130 have the same radius.

The bit may be arranged to satisfy the following equation in consideration of the rotation trajectory of another bit. The second bit 132b is installed in the bit portion 130 adjacent to the bit portion 130 in which the first bit 132a is installed based on the direction of rotation of the air expander, and has a radius r _i+1 and No other bits are installed between the radii (r _i ).

[expression]

r _i+1 = r _i + s

In the above equation, r _i+1 : turning radius of the first bit 132a

r _i : Turning radius of the second bit 132b.

s: 1.0w to 1.1w is preferred. (w is the width of the bit, which means the width of the trajectory that occurs when the bit is rotated in a circular trajectory)

In addition, the spiral screw 120 is preferably coupled to the outer circumferential surface of the central shaft 110 in a length of 1 to 1.5 revolutions. If the length of the spiral screw 120 is less than one revolution, the rear discharge of the soil is not smooth and the direction control of the expansion machine becomes unstable. If it is longer than 1.5 revolutions, the expansion machine becomes heavier than necessary and the production cost is high. There is a problem that it takes.

In addition, the difference (pulsation) between the maximum value and the minimum value of the rotational load for rotating the reamer 100, 200 is preferably 0.4 kN·m or less.

The expansion method according to the present invention repeats the expansion step to become a tunnel having a target diameter using the above-described expansion machine. At this time, the diameter of the expander may be increased by 150 to 250 mm for each expansion step. If the diameter increase is less than 150 mm, the expansion step is too large, which is uneconomical and prolongs the construction period. When the diameter increase exceeds 250 mm, the torque required for drilling increases, making rotation of the press-fitting equipment difficult. In order to increase the diameter to 250 mm or more, it is necessary to use a presser with a larger output, which increases the construction cost.

Another aspect of the present invention, a method for manufacturing an air inflator includes: (a) removing a central portion 310 of a circular metal plate 300 to become a donut shape; (B) cutting in the radial direction from the center of the donut-shaped circular metal plate 300 to form a cutting line 316; (C) after the step (B), torsionally forming the circular metal plate 300 at a constant angle so as to be a screw 120 of a spiral shape; And, (D) welding the torsionally shaped screw 120 to the outer circumferential surface of the central axis 110.

Prior to the step (c), the outer rim of the circular metal plate 300 is cut into a spiral 312 to form a stepped jaw 314, but the stepped jaw 314 extends along the extension line of the cutting line 316. To be located in This is to ensure that the diameter of the expander decreases toward the rear.

In order to allow the torsionally shaped screw 120 to be welded to the outer circumferential surface of the central shaft 110, the diameter of the central portion 310 removed in step (a) is greater than the outer diameter of the central shaft 110. desirable.

The present invention has the following effects.

First, the excavated soil can be moved through the screw head straight through the expander head, and accordingly, the traction force required for the expansion is small, the rotational load is small, and the discharge of the soil can be smoothly performed.

Second, it is possible to reduce downward bias that occurs during construction.

Third, the manufacturing process of the spiral screw can be simplified.

1 is a cross-sectional view showing a conical expander according to the prior art to expand the soil.
Figure 2 is a perspective view showing the conical expander of Figure 1;
Figure 3a is a perspective view showing an expander with two helix screws (double helix screws) and a bit.
Figure 3b is a front view showing the air expander of Figure 3a.
Figure 4 (a) ~ 4 (c) is a cross-sectional view showing that the deflator of Figure 3a is deflected downward when digging.
FIG. 5 is a graph showing a rotational load (torque) generated when the reamer of FIG. 3A is reamed with respect to a rotation angle.
Figure 6 is a graph showing the rotational load (torque) that occurs when the reamer of FIG.
7A is a perspective view showing a three-screw screw (triple screw) and an expander with a bit.
Figure 7b is a front view showing the air expander of Figure 7a.
Figure 7c is a side view showing the air expander of Figure 7a.
8(a) to 8(c) are graphs showing the bit arrangement method of the reamer in FIG. 7A.
9(a) to 9(b) are cross-sectional views showing that the air in FIG. 7A is deflected downward when the air is excavated.
10 is a cross-sectional view showing a tunnel in which the expander of FIG. 7A is expanded.
Figure 11a is a perspective view showing an expander with four helix screws (quad screw) and bits.
Figure 11b is a front view showing the air expander of Figure 11a.
12 is a graph showing the rotational load (torque) generated when the expansion machine is expanding and drilling, with respect to the rotation angle and the number of spiral screws.
13 is a view sequentially showing a method of manufacturing a reamer with a triple helix screw.
14 is a cross-sectional view showing that the air in FIG. 7A constructs a curved tunnel.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. Prior to this, the terms or words used in the present specification and claims should not be construed as being limited to ordinary or dictionary meanings, and the inventor appropriately explains the concept of terms in order to explain his or her invention in the best way. Based on the principle that it can be defined, it should be interpreted as meanings and concepts consistent with the technical spirit of the present invention. Therefore, the configuration shown in the embodiments and drawings described in this specification are only examples of the present invention and do not represent all of the technical spirit of the present invention, and various equivalents that can replace them at the time of this application It should be understood that there may be variations.

Hereinafter, the description will be given by taking as an example an expander having three spiral screws (triple screw) and an expander having four spiral screws (quad screw). However, this is only for convenience of description, and the present invention makes the air expander having three or more spiral screws as its right scope. The expander having five or more spiral screws will be omitted here, as those skilled in the art with reference to the present specification will be able to easily or clearly know the structure.

1.Expansion machine with triple helix screw and bit

7A is a perspective view showing a reamer according to a first embodiment of the present invention, FIG. 7B is a front view showing the reamer, and FIG. 7C is a side view showing the reamer.

As shown in the drawing, the expander 100 includes a central shaft 110, three spiral screws 120 installed on the outer circumferential surface of the central shaft 110, and a bit unit 130 installed at the tip of the spiral screw 120 ).

The central shaft 110 is an axis having a predetermined diameter, and is connected to a driving rod (extension rod, 3 in FIG. 1 ). The central shaft 110 is pulled forward while being rotated by the rotational force and the traction force transmitted from the driving rod 3.

The spiral screw 120 is a spiral-shaped screw, and is coupled to the outer circumferential surface of the central shaft 110 by welding or the like. Three spiral screws 120 are installed on the outer circumferential surface of the central shaft 110 at 120° intervals. That is, the three spiral screws 120 have a phase difference of 120°.

The spiral screw 120 preferably has a length of 1 pitch to 1.5 pitch. That is, the spiral screw 120 is welded to a length of 1 rotation or 1.5 rotations around the central axis 110 (the length of the spiral screw is 1 pitch in FIGS. 7A to 7C).

If the length of the spiral screw 120 is less than one revolution, the rear discharge of the soil is not smooth and the direction control of the expander becomes unstable. If it is longer than 1.5 revolutions, the expander becomes heavier than necessary and the production cost is high. There is a problem.

The spiral screw 120 serves to transfer the soil excavated by the bit 132 to the rear. And, for the excavation of the curved tunnel, the spiral screw 120 is preferably reduced in diameter as it goes to the rear, which will be further described below.

The bit portion 130 is installed in the radial direction at the tip of each spiral screw 120. The bit unit 130 may include a base 131 and a bit 132.

The base 131 is welded to the tip of each spiral screw 120 and is installed in a radial direction, and may have a narrow width and a long length (relatively long in the radial direction compared to the width). The bit 132 is installed on the base 131, and in the present specification, the bit 132 is used in a sense including all conventional drilling means, such as a cutter, a bit, and the like, capable of excavating the soil.

Since the head portion (H) of the expansion machine is an open structure except for the portion where the base 131 is installed, the soil excavated by the bit 132 moves through the head portion (H) and moves toward the spiral screw (120). Is done. As described above, since the head portion H has an open type, the expansion machine 100 has a small rotational resistance and traction resistance during expansion, thereby reducing the construction stage while leaving the capacity of the press-in equipment (not shown in the drawing) intact. Can.

That is, compared with the conical bulge 4, the bulge 100 according to the present invention maintains a similar number of bits, but can reduce the rolling resistance (required torque) by reducing the contact area with the soil. When a constant thrust (traction force) and rotational force (torque) from the press-in equipment (not shown in the drawings) are applied to the air expander, the rotational resistance increases in proportion to the frictional area between the soil and the head. Since the head portion H of the expander 100 is open, it is possible to significantly reduce the rotational resistance, and accordingly, the expansion stage may be skipped by one or two stages to construct.

For example, when constructing a soil tunnel of 800 mm in diameter, a total of 8 processes of 200, 300, 400, 500, 600, 700, and 800 mm in diameter are required, starting with the initial 150 mm shooting process. That is, it is common to increase the diameter by about 15% to complete the tunnel diameter of 100%.

In contrast, the expander 100 may increase the diameter by 150 to 250 mm for each expansion step, so that the general expansion step may be skipped. On the other hand, if the diameter increase is less than 150 mm, the expansion step is too large, so it is uneconomical and the construction period is long, and when the diameter increase exceeds 250 mm, the torque required for excavation increases, making rotation of the press-fitting equipment difficult. In order to increase the diameter to 250 mm or more, it is necessary to use a presser with a larger output, which increases the construction cost.

For reference, Table 1 below is an example in which the contact area of the conical reamer 4 and the reamer 100 is compared with each reinforcing step. It can be seen that in the reamer 100, since the head portion H is all open except the base 131, the contact area is greatly reduced, and accordingly, the rotational resistance is also reduced.

[Table 1]

The bit 132 may be installed at a predetermined interval on the base 131. 8(a) to 8(c) show an example in which bits are installed. Reference numerals 132, 132a, and 132b denote bits, and are separated for convenience of description. Reference numeral 132a denotes a first bit, 132b denotes a second bit, and 132 denotes all bits (including the first and second bits).

The first bit 132a is installed outside the second bit 132b installed in the neighboring base 131 by s in the radial direction. The bit arrangement method includes single spiral and double spiral methods, which will be arranged as a single spiral.

The radius of the first bit (132a), (r _{i + 1,} a turning radius) to the radius of the second bit (132b) (r _i, the turning radius) should satisfy the formula (1) below. And, another bit is not installed between the radius r _i+1 and the radius r _i . The bit part 130 in which the first bit 132a is installed based on the direction of rotation of the reamer is located 120° ahead of the bit part 130 in which the second bit 132b is installed.

This arrangement of bits considers the trajectory of the bit so that there is no unearthed sediment and overlapping trajectories.

r _i+1 = r _i + s......... (1)

In the above equation, r _i+1 : radius of rotation of the first bit 132a.

r _i : Turning radius of the second bit 132b.

s: 1.0w~1.1w is desirable (w is the width of the bit, which means the width of the trajectory that occurs when the bit is rotated in a circular trajectory)

And, the outermost bit (gauge bit) is installed on the outermost side of the base 131 so as to have the largest radius, but three gauge bits have the same radius. This is because the three outermost gauge bits smoothly form the tunnel lining and reduce wear on the outside of the expander.

As shown in the above, the expander 100 having three spiral screws 120 reduces downward deflection during excavation excavation. As shown in FIG. 9(a), when the two bit parts 130 are at the bottom of the tunnel Since two bit portions (and/or two spiral screws) support the left and right wall surfaces, the lower flat digging is partially reduced, and as shown in FIG. 9(b), one bit portion 130 is located at the bottom of the tunnel. If present, the lower deflection excavation is partially reduced by the frictional force between the two bit portions (and/or two spiral screws) and the left and right wall surfaces. In addition, although the diameter of the expander head portion H differs depending on the measurement direction, it is smaller than the diameter difference D1-D2 of the expander 10, and this configuration also helps to reduce the roughness.

FIG. 10 shows the air expander 100, the actual tunnel excavated by the air expander 100, and the target tunnel (the tunnel to be constructed), which can be seen as compared to FIG. 4(c). have.

On the other hand, since the digging machine 100 is excavated by three spiral screws 120, the maximum size of the pulsation is reduced compared to the case of the expanding machine 10. This point is explained below.

2. Expeller with quadruple screw and bit

Figure 11a is a perspective view showing the air expander according to the second embodiment of the present invention, Figure 11b is a front view showing the air expander.

As shown in the drawing, the expander 200 includes a central shaft 110, four spiral screws 120 installed on the outer circumferential surface of the central shaft 110, and a bit portion installed at the tip of each spiral screw 120 ( 130).

Among the above components, the central axis 110 is the same as the central axis 110 of the expander 100.

In addition, the bit unit 130 is the same as the bit unit 130 of the reamer 100, and the arrangement method of the bit 132 is also the same.

The spiral screw 120 is a spiral-shaped screw, and is coupled to the outer circumferential surface of the central shaft 110 by welding or the like. Four spiral screws 120 are installed on the outer circumferential surface of the central shaft 110 at 90° intervals. That is, the four spiral screws 120 have a phase difference of 90°.

Like the spiral screw 120 of the expander 100, the spiral screw 120 is preferably having a length of 1 to 1.5 pitch. That is, the spiral screw 120 is welded to the length of one revolution or 1.5 revolutions around the center shaft 110 (the spiral screw length is 1 pitch in FIG. 11A ).

The spiral screw 120 serves to transfer the soil excavated by the bit 132 to the rear. In addition, for excavating a curved tunnel, it is preferable that the diameter of the spiral screw 120 decreases toward the rear.

Since the head portion H of the expander 200 is an empty space except for the bit portion 130, the expander 200 has an open head structure, and the contact area with the soil is much smaller than that of the conical expander 4 . Thus, the soil excavated by the bit 132 passes through the head portion H and is directly moved toward the spiral screw 120. And, when the traction force and the rotational force of the press-fitting equipment are the same, it is possible to excavate with a larger diameter than the conical expansion machine 4, so the expansion stage may be omitted in steps 1 to 2.

In general, the expander has the largest vertical load when a certain bit portion passes the lowest point, and at this time, the possibility of downward deflection drilling is greatest. Since the expander 200 has four spiral screws 120, when a specific bit portion 130 is at its lowest point, the bit portions on both sides (or spiral screws on both sides) support the tunnel wall surface, thus reducing downward deflection. Can be reduced. That is, when the downward deflection occurs, the gauge bit (the outermost bit) is fixed (or supported) at the maximum radius point of the tunnel wall, so that downward drilling can be prevented or reduced, and the tunnel cross section can be as close as possible to the circle.

3. Pulsation phenomenon

FIG. 12 is a graph showing the rotational load (torque) generated when the reamer 10, 100, 200 is excavated, with respect to the rotation angle and the number of spiral screws, for a specific soil (eg, sandy soil) It shows the pulsation when the minimum rotational load (torque load) required to dig a tunnel with a diameter of 1 m is assumed to be 1.0 kN·m. In FIG. 12, the x-axis represents the rotation angle (°) of the reamer and the y-axis represents the rotational load (torque load, kN·m).

In the drawing, the black line represents the rotational load of the expander (having 10, two helix screws and two bit parts). The pulsation is 1 to 1.5 kN·m, and the red line is the expander (100, three helix screws. And three bit parts). The pulsation occurs from 1.1 to 1.4 kN·m, and the blue line represents the rotational load of the expander (200, with four helix screws and four bit parts). It occurs at 1.125 to 1.375 kN·m.

Although the average value of the rotating load is similar, the pulsation phenomenon decreases as the number of spiral screws increases, so stable operation of the air expander is possible. Table 2 shows the calculation. As shown in Table 2, the case of having a triple helix screw can reduce the pulsation phenomenon by 40%, and the case of having a triple helix screw can reduce the pulsation phenomenon by 50%. According to the applicant's study, it was analyzed that the pulsation difference decreases to less than 0.4 kN·m when a triple or quadruple screw is used.

[Table 2]

4. Manufacturing method of expanding air

13 is a view sequentially showing a method of manufacturing an expander having a triple helix screw.

As shown in the figure, the manufacturing method of the air expander is cut into a donut shape by cutting the central portion 310 of the circular metal plate 300 and cutting the outer border of the circular metal plate 300 into a spiral 312 shape to form a stepped jaw 314 Step (S10) (S20) to be formed, cutting in the radial direction from the center of the cut circular metal plate 300 to form a cutting line 316, but the cutting line 316 is on the extension line of the stepped jaw 314 Step (S30) to be positioned on the torsional molding of the circular metal plate 300 at a constant angle so as to be a screw 120 of a spiral shape (S40), the central axis of the torsional circular metal plate 300 (ie, spiral screw) (S50) of welding to the outer circumferential surface of 110 and welding the bit portion 130 to the front end of the circular metal plate 300 (S50) and the two spiral screws 120 made through the steps of S10 to S50 as the central axis (110) ) May further include welding (S60 ).

Each of the above steps will be described below.

First, the central portion 310 of the circular metal plate 300 is removed to make a donut shape (S20). The central portion 310 can be removed by punching a circular metal plate 300 with a press mold. It is preferable that the diameter of the central portion 310 to be removed is slightly larger than the outer diameter of the central shaft 110, which is to be coupled (welded) at an angle to the outer peripheral surface of the central shaft 110 according to the pitch angle. Because.

Subsequently, the outer rim of the circular metal plate 300 is cut into a spiral 312 shape so that the stepped jaw 314 is formed. The spiral is to reduce the diameter of the spiral screw 120, that is, to realize that the diameter of the spiral screw 120 gradually decreases toward the rear of the expander.

Next, by cutting in the radial direction from the center of the cut circular metal plate 300 to form a cutting line 316, so that the stepped jaw 314 and the cutting line 316 are located on the same line (S30).

Subsequently, the spiral screw 120 is made by twisting the circular metal plate 300 at a constant angle so as to be a spiral screw (S40). At this time, it is preferable that the circular metal plate 300 is torsionally formed to form a 1 or 1.5 pitch spiral screw.

After the torsion molding, a circular metal plate 300 (that is, a spiral screw) is welded to the outer circumferential surface of the central shaft 110 and a bit portion 130 is welded to the tip of the circular metal plate 300 (S50). Welding the bit portion 130 to the tip of the circular metal plate (the tip of the spiral screw) may be made before or after welding the circular metal plate 300 and the central shaft 110. Meanwhile, the bit portion 130 may be welded to both the front end and the central shaft 110 of the circular metal plate 300. Further, after the bit portion 130 is first welded to the central shaft 110, the spiral screw 120 may be welded to the bit portion 130 and the central shaft 110.

Finally, in addition to the welded circular metal plate (spiral screw), two circular metal plates (spiral screw) are additionally welded to the central shaft 110 (S60). The three spiral screws 120 are installed to have a phase difference of 120° from the neighboring spiral screws 120.

5. How to set screw length and draft angle according to tunnel curvature

14 shows that the expander 100 expands (digs) a curved tunnel. When excavating a curved tunnel, the head portion of the expander 100 (H, the tip of the expander) remains in close contact with the side walls of both sides of the tunnel, and the rear end of the expander (the rear end of the spiral screw) is one side wall of the tunnel (drawings) Excavation while maintaining a close contact with the outer side wall).

As described above, the expander 100 may decrease the diameter of the spiral screw 120 toward the rear to excavate the curved tunnel. The reduction ratio, that is, the gradient ratio is obtained by the following equation (2).

.............. (2)

.............. (2)

Further, the gradient ratio is preferably 1/15 to 1/10. The gradient ratio has the same meaning as the gradient angle (θ _g ).

A suitable draft angle (θ _g , gradient ratio) depends on the radius of curvature of the tunnel. The appropriate draft angle according to the radius of curvature of the tunnel is shown in Table 3 below. The draft angle in Table 3 comes from the applicant's long field experience.

[Table 3]

1: Tosa ground 2: Shooting hole
3: Action tension rod 4: Conical expansion machine
10, 100, 200: air expander 11, 110: central axis
13, 120: screw 15, 132: bit
130: bit part 131: base
132a: first bit 132b: second bit
D1, D2: diameter of the expander 10 H: head portion of the expander
s: Radius difference between the first bit and the second bit
R _t : radius of curvature of the tunnel θ _g : draft angle

Claims (10)

A central axis that is rotated while being pulled by the driving rod;
Three or more spiral screws installed on the outer circumferential surface of the central axis; And,
Includes; a bit portion installed on the tip of each spiral screw,
Each spiral screw has a constant phase angle difference from a neighboring spiral screw, and the bit portion includes a bit for excavating soil,
The head portion of the expander has an open structure in which the rest of the portion except for the bit portion is empty, and accordingly, the soil excavated by the bit passes through the head portion and then moves backward by a spiral screw. According to claim 1,
The diameter of the spiral screw decreases toward the rear, and the spiral screw is characterized in that three or four are installed. According to claim 2,
Bit part,
It is welded to the tip of the spiral screw is installed in the radial direction, the base having a narrow width and long length; And,
The base is installed at a predetermined interval; includes;
The outermost gauge bit of the bit is installed on the outermost portion of the base, but the air blower characterized in that the gauge bit installed in each bit portion has the same radius. According to claim 3,
The bit is arranged to satisfy the following equation in consideration of the rotation trajectory of another bit.
[expression]
r _i+1 = r _i + s
In the above equation, r _i+1 : turning radius of bit 132a
r _i : The radius of rotation of the bit 132b. The bit 132b is a bit installed in the bit portion where the bit 132a is installed and a neighboring rear bit portion based on the rotation direction of the air expander.
s: 1.0w to 1.1w. (w is the width of the trajectory that occurs when the bit is rotated in a circular trajectory) According to claim 3,
The spiral screw is a reamer, characterized in that it is coupled to the outer circumferential surface of the central shaft with a length of 1 to 1.5 revolutions. According to claim 3,
The difference between the maximum and minimum values of the rotating load for rotating the expansion air is 0.4 kN·m or less. A method for constructing a tunnel using the air expander according to any one of claims 1 to 6,
(a) constructing a tunnel; And,
(b) re-expanding the expanded tunnel using a reamer having a diameter larger than that of the step (a);
The repeating step is repeated so as to be a tunnel having a desired diameter, and the expanding method is characterized in that the diameter of the expander is increased by 150 mm to 250 mm for each expansion step. (A) removing the central portion of the circular metal plate to be a donut shape;
(B) forming a cutting line 316 by cutting in a radial direction from the center of the donut-shaped circular metal plate;
(C) after the step (B), torsionally forming a circular metal plate at a constant angle to become a spiral screw; And,
(D) welding the torsion-molded circular metal plate to the outer circumferential surface of the central axis. The method of claim 8,
Before the step (c), the outer edge of the circular metal plate is cut into a spiral shape so that the stepped jaw 314 is formed, but the stepped jaw 314 is positioned on the extension line of the cutting line 316. The manufacturing method of the air expanding machine. The method of claim 8 or 9,
In order to weld the torsion-molded circular metal plate to the outer circumferential surface of the central axis, the diameter of the central portion removed in step (A) is greater than the diameter of the central axis.

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