KR101901381B1 - Reamer of pneumatic multiple hammer type for drilling horizontally having screw whose diameter decreases toward the rear and, methods for calculating the diameter - Google Patents

Abstract

A reamer according to the present invention has a screw blade with a diameter decreasing to the rear due to sagging of a rear rod such that rocks can be efficiently discharged while reducing the weight and frictional force of the screw blade and production costs.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a pneumatic multi-hammer reamer for horizontal excavation and a method for obtaining a diameter of a screw blade, calculating the diameter}

The present invention relates to a pneumatic multi-hammer reamer for horizontal excavation, and more specifically, because the diameter of a screw blade connected to the rear end of the reamer is reduced toward the rear, the weight of the screw blade and the frictional force And to reduce the manufacturing cost.

In addition, the present invention also relates to a method for obtaining the diameter of such a screw blade.

The multi-hammer type perforator excavates the front rock mass while reciprocating a plurality of hammer mounted on the body, and is classified into hydraulic type and pneumatic type according to the operation mode of the hammer.

Pneumatic multi-hammer type drilling machines are mainly used for vertical drilling such as groundwater development and geothermal development. When piercing the rock using a pneumatic hammer, the rock particles produced by crushing the rock or the ground are automatically discharged to the surface by the compressed air used for the operation of the hammer. The velocity vector is uniformly formed in a relatively uniform manner except for the partial velocity reduction due to the friction with the perforated wall when the rock is discharged to the upper portion together with the compressed air so that the cancer can be smoothly discharged to the outside have.

However, in the case of punching in the horizontal direction using a pneumatic multi-hammer type perforator, as the excavation length becomes longer, the ash discharge is not good. This will be described by taking the multi-hammer type reamer as an example.

As is known, the pneumatic multi-hammer ream expands the tunnel by hitting the rock on the front side while the hammer reciprocates by the compressed air, and the ash produced by the hitting causes the compressed air used to operate the hammer As shown in Fig.

As shown in Fig. 1 (a), at the beginning of the excavation, the female part 3 is hardly behind the reamer 1, .

However, as shown in Fig. 1 (b), when the excavation length is about 10 m to 30 m, since the rock mass 3 is accumulated behind the reamer 1, the release of the rock mass starts to be disturbed, Likewise, when the excavation field exceeds 30m to 50m, the ash (3) accumulates behind the reamer (1), so the discharge of the ash decreases and jamming occurs.

As described above, in the case of punching in the horizontal direction using a pneumatic multiple hammer drill (including reamer), the problem is that as the excavation length becomes longer, the ash 3 is not smoothly discharged to the outside, have.

In order to solve the above problems, the present applicant has installed a screw blade on the rear rod 7 of the reamer. The diameter of the screw blade is smaller than the diameter of the tunnel. The diameters of the screw blades are the same from the reamer to the ground. The screw blade is rotated together with the rear rod (7) to move the female part backward and then to the ground.

However, when the screw wing is provided on the rear rod 7, the weight of the rear rod 7 is increased accordingly, and the rotational force is lost due to the frictional force between the screw wing and the arm portion, There is a problem that it must be provided.

As a result of repeated researches to solve such a problem, Applicant has found that the rear rod 7 is lowered and the amount of deflection becomes larger as the entire length of the rear rod 7 becomes longer during horizontal excavation, It is possible to reduce the weight increase due to the screw blades and to reduce the frictional force between the screw blades and the ash blade, and to lower the manufacturing cost by reducing the diameter of the screw blades.

Thus, it is an object of the present invention to provide a reamer capable of reducing the weight and frictional force of screw wings while lowering the manufacturing cost while efficiently discharging the ash.

It is a further object of the present invention to provide a method of determining the diameter of such a screw blade.

A reamer (100) according to the present invention comprises a body (10); A rear rod 50 connected to a rear end of the body 10 and rotated together with the body 10; And a screw blade (60) formed in a spiral shape on the outer peripheral surface of the rear rod (50). When the ground excavation is performed in the horizontal direction, the rear rod 50 is struck downward. The diameter (D _sc) has a diameter capable of discharging the rock flour jidoe smaller toward the rear, considering the sagging of the back rod 50 has built-up on the tunnel floor or tunnel lower rearward (D _sc) of the screw blade (60) .

The plurality of hammers 20 installed on the body 10 are reciprocated by the compressed air to strike the front rocks. The compressed air is discharged to the rear after driving the hammers 20, And the ash discharged to the rear is discharged to the ground by the screw vanes 60. [

In order to perform curved track excavation, a part of the hammer bit of the hammer 20 may be provided to protrude laterally from the body 10, or the body 10 may be formed to have a smaller diameter as it goes backward.

The screw blades 60 are arranged at a distance of 1 m to 2 m from the rear end of the body 10 to the rear side of the rear side of the body 10, (Not shown).

The diameter D _sc of the screw vane 60 may gradually decrease or decrease stepwise toward the rear. The diameter D _sc of the screw blade 60 can be calculated by the following equation (1).

[Formula 1]

D _sc = D _t - 隆_max 2 - C _curve

D _t : Diameter of the tunnel excavated by reamer

? _max : maximum deflection amount of the rear rod 50

C _curve : Correction value for clearance with tunnel wall during curve excavation

On the other hand, the diameter D _sc of the screw vane 60 decreases toward the rear and converges to a constant value. The convergence value, which is the minimum diameter of the screw blade 60, can be calculated by the following equation (2).

[Formula 2]

D _{sc_min} = D _r + W

D _{sc_min} : the minimum diameter of the screw blade 60

D _r : diameter of rear rod 50

W : The width of the screw blade itself (70mm ~ 130mm)

(A) the maximum deflection amount? _Max of the rear rod 50 in accordance with the number of the rear rods 50 or the total length L of the rear rods 50 is determined according to the present invention, Respectively; And (b) calculating the diameter (D _sc ) of the screw blade (60) coupled to the rear rod (50) using the maximum deflection amount (? _Max ) and Equation (1).

In the step (a), the maximum deflection amount? _Max of the rear rod 50 is determined in a state where the screw blade 60 is not provided. The diameter D _sc of the screw vane 60 coupled to the rear rod 50 which is further connected to the reamer 100 as the excavation length of the reamer 100 increases, 50 and the maximum deflection amount? _Max in accordance with the length L of the entire rear rods 50 and Equation (1).

The present invention has the following effects.

First, in horizontal excavation using reamer, it is possible to reduce the weight and frictional force of the screw blade and to reduce the manufacturing cost while discharging ash efficiently.

Second, a method for obtaining the diameter of a screw blade is provided.

FIGS. 1 (a) to 1 (c) are cross-sectional views illustrating horizontal rock excavation using pneumatic multiple hammer ream, and resulting debris discharge.
2 is a front view showing a pneumatic multi-hammer reamer according to a preferred embodiment of the present invention;
Figure 3a is a cross sectional view showing the compressed air flow inside the re-air.
FIG. 3B is a cross-sectional view showing that the rock is discharged to the rear during rock excavation by reamer. FIG.
4 is a front view showing the rear rods and screw wings connected to the reamer.
5 is a front view showing a modification of the screw blade.
6 is a cross-sectional view showing a fastening structure of a drilling rod which is a numerical analysis target;
Fig. 7 is a view showing a load, a restraint condition, and a structure of a rod joint for numerically analyzing deflection of a drilling rod; Fig.
8 is a graph showing the maximum deflection amount along the length of the rod.
Fig. 9 is a view showing the amount of deflection according to the number of rods (length) when the diameter of the rod is 73 mm; Fig.
Fig. 10 is a view showing deflection amounts depending on the number (length) of rods when the diameter of the rods is 114 mm; Fig.
11 is a graph showing the diameter of a screw blade according to the length of the rod;

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately It should be interpreted in accordance with the meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined. Therefore, the embodiments described in the present specification and the configurations shown in the drawings are merely examples of the present invention and are not intended to represent all of the technical ideas of the present invention, so that various equivalents And variations are possible.

1. Configuration of reamer

2 is a front view showing a pneumatic multi-hammer reamer according to a preferred embodiment of the present invention.

As shown in the drawing, the reamer 100 includes a body 10, a hammer 20 provided on the body 10, a driving rod 5 connected to the front end of the body 10, A rear rod 50 connected to the rear end, and a screw blade 60 coupled to the outer circumferential surface of the rear rod 50. [

As described above, the reamer 100 is used in the horizontal excavation of a ground (including a rock), in which 'horizontal excavation' refers not only to horizontal excavation in a mathematical sense, This means excavation in the direction in which the rearward rod is struck down when used.

The body 10 is connected to the driving rod 5 and rotated at a predetermined rotation speed R.P.M. The driving rod 5 pulls the body 10 forward and rotates.

A rear rod 50 is connected to the rear end of the body 10 and the rear rod 50 supplies compressed air for operation of the hammer 20 to the body 10. [ A screw blade (60) is coupled to the outer circumferential surface of the rear rod (50).

The compressed air supplied through the rear rod (50) allows the hammer (20) to reciprocate forward and backward to excavate the rock mass. The red dotted lines and the arrows in FIG. 3A indicate the flow of compressed air inside the reamer.

The compressed air used for the operation of the hammer 20 is discharged to the cover through the discharge hole 21 formed in the hammer bit, and then discharged backward through the flushing channel 30 as shown in FIG. 3B. The flushing channel 30 is formed along the longitudinal direction of the body 10 so as to penetrate through the body 10.

The rotation of the body 10 by the drive rod 5, the supply of the compressed air through the rear rod 50, the operation of the hammer 20 by the compressed air, and the discharge of the ash back through the flushing channel 30 And the like are well known to those skilled in the art, so a detailed description thereof will be omitted here.

The rear rod 50 is coupled to the rear end of the body 10 and is thus rotated together with the body 10. The coupling of the body 10 and the rear rod 50 is performed by a known coupler (not shown). The coupler not only connects the body 10 and the rear rod 50 but also transmits the rotational force of the body 10 to the rear rod 50.

The rear rod 50 is a hollow tube whose inside is hollow, and both ends thereof can be engaged with the neighboring rear rod 50. Accordingly, when the excavation distance of the reamer 100 becomes long, the rear rods 50 can be coupled to each other and extend to the ground. When the rear rod 50 is connected to the body 10, the rear rod 50 is sagged downward at the time of horizontal excavation. The amount of deflection becomes larger as the entire length of the rear rod 50 becomes longer, The smaller the diameter, the larger the diameter.

On the outer circumferential surface of the rear rod (50), a screw blade (60) is continuously engaged along the longitudinal direction of the rear rod (50) in a spiral shape. The screw blade (60) is rotated together with the rear rod (50). Therefore, when the body 10 is rotated by the rotational force of the driving rod 5, the rear rod 50 and the screw blade 60 are rotated together to discharge the female parts backward.

Since the ash discharged from the rear side of the body 10 starts to accumulate at a distance of 1 to 2 m from the rear of the body 10 and more precisely from 1.5 m to the rear of the body 10, May be installed. 2, g represents the distance between the rear end of the body 10 and the starting point of the screw blade 60. This configuration has the advantage that the weight of the screw vane 60 can be reduced, the torque reduction can be reduced, and the manufacturing cost can be reduced.

4, the diameter D _sc of the screw blade 60 is the sum of the diameter of the rear rod 50 and the width W of the screw blade itself. Even though the diameter of the rear rod 50 is constant, Since the width W of the wing itself becomes smaller toward the rear, the diameter D _sc becomes smaller toward the rear as well. This is because the diameter D _sc of the screw blade 60 and the width W of the screw blade itself are set to be large in consideration of the fact that the amount of deflection of the rear rod 50 increases toward the rear side and the arm portion is accumulated in the lower portion of the tunnel. The female part can be efficiently discharged even if the distance is reduced toward the rear. If the diameter D _sc is made smaller toward the rear side, the load of the screw vane 60 becomes smaller, thereby reducing the torque loss.

As shown in Fig. 4, the diameter D _sc of the screw vane 60 is reduced stepwise. That is, of the screw blade (60) coupled to one of the rear rod 50 diameter (D _sc) is the diameter (D _sc) of the screw blade (60) coupled to the rear rod 50 which, but the same, neighbor There is a difference. Accordingly, a stepped step 62 is formed at a portion where the rear rod 50 is connected to the neighboring rear rod 50 (FIG. 4 is an enlarged view of the connecting portion of the rear rod).

In contrast, FIG. 5 shows a structure in which the diameter D _sc of the screw vanes 60 gradually changes. That is, in the same rear rod 50, the diameter of the screw blade 60 gradually decreases from the left end to the right end. Therefore, the stepped jaws 62 are not provided at the both side ends of the rear rod 50. The diameter D _sc of the screw blade 60 calculated by the following equations (1) and (2) corresponds to the diameter of the central portion of the rear rod 50.

The present invention can also be applied to excavating tunnels of curved trajectories. The present applicant has researched and developed a reamer which can be effectively used for excavating a curved orbit tunnel, and has been registered as a Korean Patent Registration No. 1677278 entitled " Reamer capable of excavating in a curved orbit, and a reaming method using the reamer " . The contents disclosed in the above-mentioned Patent Registration No. 1677278 are included in this specification.

The registered patent invention has a structure in which some of the hammer bits are protruded laterally from the reamer body, or the diameter of the reamer body decreases as the reamer body is moved backward. This structure is effective in expanding the curved track to be.

It is desirable that the diameter D _sc of the screw blade 60 be smaller than that of the linear orbit when the curved orbit is excavated because the larger diameter D _sc may touch the tunnel sidewall or the ceiling at the time of excavation of the curve orbit to be.

Specifically, in the case of a curved track, the diameter D _sc is smaller by about 50 mm to 250 mm, preferably about 100 mm to 200 mm, and more preferably about 130 mm to 170 mm, as compared with the case of a straight track. This will be discussed in more detail below.

2. Calculation of diameter of screw blade

As described above, the rear rod 50 is a hollow tube and has a constant length. When the excavation length of the reamer 100 becomes long, the rear rods 50 are sequentially connected one by one to correspond to the excavation length, and the screw wings 60 of the rear rods 50, which are sequentially connected, It is necessary to be able to efficiently discharge the ash backward. The method of determining the diameter D _sc of the screw blade 60 under these conditions is different from the method of calculating the deflection of a beam having a predetermined length, for example, a beam having a predetermined length, and calculating the amount of rebar or the like.

In order to obtain the diameter D _sc of the screw blade 60 according to the present invention, the screw blade 60 of the rear rod 50, which is further connected to the reamer 100 as the length of the reamer 100 is increased, The diameter D _sc was obtained by using the maximum deflection amount? _Max according to the number (length) of all the rear rods 50 connected to the reamer and the following equations (1) and (2).

The calculation method will be described below.

(1) Analysis condition

In the present invention, the deflection of the rear rod 50 is numerically calculated (of course, deflection of the rear rod 50 can also be obtained through a reduced model experiment or an actual scale experiment).

Specifically, numerical analysis was carried out for four drilling rods (without screw blades) as shown in Table 1 below. The rod 50 is a load that is being applied or is to be applied to a real spot among the loads manufactured in various sizes. As shown in FIG. 6, the rod 50 is a hollow tube, and threaded portions 52 are formed at both ends of the hollow tube 50 to be screwed to the adjacent rod 50.

Since the aim of the present invention is to reduce the weight of the screw blade 60, when the overloaded rod 50 and the screw blade 60 are subjected to deflection analysis, the diameter of the screw blade 60 is underestimated. Failure to do so can lead to errors. Therefore, a conservative design method is applied so that the screw vane 60 can be surely contacted with the bottom of the tunnel.

[Table 1] Specification of drilling rod to be analyzed

The rod 50 is a G105 Grade drilling pipe, and is made of steel such as 27MrCo, 37CrMnMo, and 42CrMo. In other words, the Young's modulus (E) is 210 GPa and Poisson's ratio (ν) is 0.3 in numerical analysis because of similar mechanical properties.

In the finite element analysis, only the weight due to gravity acts on the rod 50, and the gravity acceleration (g) is set to 9810 mm / s ² . The direction of action of the gravitational acceleration is -y direction in Fig.

7, one end of the rod 50 connected to the reamer restrains 3 degrees of freedom (x, y, z axis translational motion), and the other end Constrained the two degrees of freedom (y, z translation).

The portions where the rods 50 are fastened to each other by the threads join the nodes on the facing surfaces with the 1D rigid to restrain the translations in the x, y and z directions, Friction coefficient = 0.05).

(2) Analysis result

The finite element analysis was performed while increasing the load length (number of loads) until the rod 50 hit the bottom of the tunnel due to deflection.

8 shows the maximum deflection amount according to the connection length of the rod 50 for each rod type. As shown in FIG. 8, the maximum deflection increased sharply as the length of the rod 50 (the number of the rods) was increased, and as the rod diameter was smaller, more deflection occurred at the same length.

Since the size of the reamer is 650 mm in diameter and 900 mm in diameter (total of 2 types), 73 (2-7 / 8 "), 89 (3-1 / 2"), 114 (4-1 / 2 " (5-1 / 2 ") is connected to the bottom of the tunnel due to sagging when the number of connected rods is 8, 6, 5, 4 or more, respectively.

Table 2 below shows the graph of FIG. 8 in a table.

[Table 2] Maximum deflection for the total length of the rod for each load type

9 is a view showing the amount of deflection when one to eight rods 50 are connected when the diameter of the rod 50 is 73 mm. 10 is a view showing the amount of deflection when 1 to 5 rods are connected when the diameter of the rod 50 is 114 mm.

(3) Calculation of diameter of screw blade

In order to propose the proper diameter D _sc of the screw blade 60, it is assumed that the diameter of the tunnel to be excavated is equal to the diameter of the reamer. For example, when excavating with a 650 mm diameter reamer, the tunnel diameter is assumed to be 650 mm.

The diameter D _sc of the screw vane 60 was further subtracted from the screw correction value (clearance with the tunnel surface) for curved excavation after subtracting twice the maximum deflection amount in the tunnel diameter (see Equation 1 below) ). The screw correction value (C _curve ) is determined according to the curvature of the curved track, the tunnel diameter, etc., and is approximately 50 mm to 250 mm, preferably 100 mm to 200 mm, and more preferably 130 mm to 170 mm. And, if the excavation trajectory is a straight line, the screw correction value (C _curve ) is zero. However, most small utility tunnel works have a curvature, so in most cases it is desirable to enter a screw correction value (C _curve ).

Diameter (D _sc) the minimum value that is, the minimum diameter (D _{sc_min)} of the order of rock flour discharge of the minimum required screw blade itself width - was applied to the sum of the (W = screw wings diameter rod diameter) of the rod diameter (below (2) "

[Equation 1]

D _sc = D _t - 隆_max 2 - C _curve

D _sc : Diameter of the screw blade 60

D _t : Diameter of the tunnel excavated by reamer

隆_max : maximum deflection amount of the rod (50)

C _curve : Correction value for clearance with tunnel wall during curve excavation

&Quot; (2) "

D _{sc_min} = D _r + W

D _{sc_min} : the minimum diameter of the screw blade 60

D _r : diameter of the rod 50

W : The width of the screw blade itself. About 70 mm to about 130 mm, and preferably about 100 mm.

Tables 3 to 6 below illustrate the case where the load is 140 (5-1 / 2) when the load is 73 (2-7 / 8 "), 89 (3-1 / 2""), It indicates the maximum deflection amount and the diameter of the screw blade according to the number of rods (total length of the rod). The screw diameter considering only the maximum deflection amount is calculated by subtracting twice the maximum deflection amount in the tunnel diameter. The screw correction value (C _curve ) and the minimum diameter (D _{sc_min} ) are not considered.

[Table 3] Screw diameter of 73 (2-7 / 8 ") rod

[Table 4] Screw diameter of 89 (3-1 / 2 ") rod

[Table 5] Screw diameter of 114 (4-1 / 2 ") rod

[Table 6] Screw diameter of 140 (5-1 / 2 ") rod

By referring to the above calculation results, it is possible to reduce the weight of the screw blades. For example, the diameter of the screw blade of the first to third rear rods of the 89 (3-1 / 2 ") rod (Table 4) is designed to be about 450 mm, the diameter of the screw blade of the fourth rear rod is Φ300, Screw blades can be designed to have a diameter of Φ189 mm or more to lighten the screw blades.

The results of the above calculations are shown in FIG. 11 as a graph. 11, the diameter D _sc of the screw blade 60 decreases as the length of the rear rod 50 becomes longer, and converges to a constant value. The decrease interval is calculated by Equation (1), and the convergence interval is calculated by Equation (2).

(4) Proposal of calculation formula

The calculation of the maximum deflection (? _Max ) according to the total length (L) of the rear rod (50) can be made as follows by analyzing the results of (2) and (3) In the following equation (3), the coefficient A has a different value for each rear load.

&Quot; (3) "

隆_max = A x L ⁴

L: length of the rod 50

Equation (3) is based on a formula for calculating the maximum deflection (occurring at the center) when a beam having a constant sectional shape receives a uniform distribution load p in the direction perpendicular to the longitudinal direction. Although the cross-sectional shape of the drilling rod is not constant due to the joint, the joint length is very short compared to the total length of the rod and the load is almost constant in the direction of gravity due to its own weight. It is considered applicable.

The coefficient value (A) for each load is calculated using Equation (3).

[Table 7] Coefficient (A) value of Equation 3 according to the rod length

The maximum deflection amount according to the total length L of the rod is calculated by substituting the value of the above A into the equation (3), and the diameter (D _sc ) of the screw blade 60 can be obtained by substituting this maximum deflection amount into the equation The diameter D _sc thus obtained is shown by a dotted line graph (a dotted line graph for each color) in FIG. Referring to FIG. 11, it can be seen that the dotted line graph and the solid line graph are almost the same.

As described above, when the deflection analysis is performed for each load specification (model) to determine the coefficient A, the maximum deflection amount according to the load length L can be calculated. Applying this to Equations 1 and 2, The diameter of the screw blade can be calculated.

3: female part 5: drive rod
7, 50: rear rod 1, 10: body
20: Hammer 21: Exhaust hole
30: Flushing channel 60: Screw wing
52: thread 62: step jaw
100: Pneumatic multi-hammer reamer for horizontal excavation
g: distance between the rear end of the body 10 and the point where the screw blade 60 starts
D _sc : diameter of the screw blade 60
D _t is the diameter of the tunnel excavated by the reamer 100
? _max : maximum deflection amount of the rear rod 50
C _curve : Correction value for clearance with tunnel wall during curve excavation
D _{sc_min} : the minimum diameter of the screw blade 60
D _r : diameter of rear rod 50
W : Width of the screw blade itself

Claims (9)

A body 10;
A rear rod 50 connected to a rear end of the body 10 and rotated together with the body 10; And
And a screw blade (60) formed in a spiral shape on an outer peripheral surface of the rear rod (50)
When the ground excavation is performed in the horizontal direction, the rear rod 50 is struck downward,
The diameter D _sc of the screw blade 60 gradually decreases or decreases stepwise as it goes backward, but the diameter of the screw blade 60 is set to a diameter that allows the debris accumulated at the bottom of the tunnel or at the bottom of the tunnel to be discharged backward (D _sc )
Characterized in that the diameter (D _sc ) of the screw blade (60) is calculated by the following equation (1).
[Formula 1]
D _sc = D _t - 隆_max 2 - C _curve
D _t : Diameter of the tunnel excavated by reamer
? _max : maximum deflection amount of the rear rod 50
C _curve : Correction value for clearance with tunnel wall during curve excavation The method according to claim 1,
The driving rod 5 is connected to the front end of the body 10 to rotate the body 10 while pulling the body 10 and the rear rod 50 supplies compressed air to the body 10 ,
The plurality of hammers 20 installed on the body 10 are reciprocated by the compressed air to strike the front rocks. The compressed air is discharged to the rear after driving the hammers 20, , And the ash discharged to the rear is discharged to the ground by the screw blade (60). 3. The method of claim 2,
Wherein a part of the hammer bit of the hammer is formed so as to protrude laterally from the body or the diameter of the body is smaller as the body is rearward. . 3. The method of claim 2,
The screw blades 60 are arranged at a distance of 1 m to 2 m from the rear end of the body 10 to the rear side of the rear side of the body 10, (50), the pneumatic multi-hammer reamer for horizontal excavation. delete The method according to claim 1,
The diameter D _sc of the screw blade 60 decreases toward the rear and converges to a constant value and the convergence value that is the minimum diameter of the screw blade 60 is calculated by the following equation Pneumatic multiple hammer ream for directional excavation.
[Formula 2]
D _{sc_min} = D _r + W
D _{sc_min} : the minimum diameter of the screw blade 60
D _r : diameter of rear rod 50
W : The width of the screw blade itself (70mm ~ 130mm) (a) obtaining the maximum deflection amount? _max of the rear rod 50 according to the number of the rear rods 50 or the total length L of the rear rods 50; And
(b) calculating a diameter (D _sc ) of the screw blade (60) coupled to the rear rod (50) using the maximum deflection amount (? _max )
The rear wing 50 is connected to the rear end of the reefer body 10 and is rotated together with the body 10 to have a predetermined length, A further rear rod 50 is connected to the rear end of the rear rod 50,
A screw blade 60 is formed in a spiral shape on the outer circumferential surface of the rear rod 50. The screw blade 60 moves the arm portion generated by the excavation of the reamer backward,
In the step (a), the maximum deflection amount? _Max of the rear rod 50 is obtained in a state in which the screw vane 60 is not present,
The diameter D _sc of the screw vane 60 coupled to the rear rod 50 which is further connected to the reamer 100 as the excavation length of the reamer 100 increases, (50), or the maximum deflection amount (? _Max ) according to the length (L) of the entire rear rod (50) and the following formula (1).
[Formula 1]
D _sc = D _t - 隆_max 2 - C _curve
D _t : Diameter of the tunnel excavated by reamer
? _max : maximum deflection amount of the rear rod 50
C _curve : Correction value for clearance with tunnel wall during curve excavation 8. The method of claim 7,
Wherein the diameter D _sc of the screw blade 60 decreases toward the rear and converges to a constant value and the convergence value that is the minimum diameter of the screw blade 60 is calculated by the following equation 2: How to find the diameter of a wing.
[Formula 2]
D _{sc_min} = D _r + W
D _{sc_min} : the minimum diameter of the screw blade 60
D _r : diameter of rear rod 50
W : The width of the screw blade itself (70mm ~ 130mm) 9. The method according to claim 7 or 8,
Characterized in that, when excavating a curved tunnel, the C _curve is from 100 mm to 200 mm.

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