KR102266504B1 - Methods for continuous abrasion test of rock cutting tool and, computer-readable media for recording computer programs for realizing the same - Google Patents

Abstract

The present invention relates to a continuous wear test method of a rock cutting tool, wherein a rock specimen is cut while the cutting tool is moved along an Archimedean spiral, (i) in an inward and outward movement, the cutting tool moves along the same spiral while cutting a rock specimen A test method in which the end point of the inward movement becomes the starting point of the outward movement, the end point of the outward movement becomes the starting point of the inward movement, and the direction of rotation of the rock specimen is reversed at the start point of the outward movement and the start point of the inward movement; (ii) repeat inward and outward movements alternately, cutting the rock specimen while the cutting tool moves along different spirals during inward and outward movements, and the end point of the inward movement becomes the starting point of the outward movement, and the end point of the inward movement becomes the starting point of the outward movement. The end point becomes the starting point of the inward movement, and the test method in which the direction of rotation of the rock specimen is the same during outward and inward movement, and (iii) the cutting tool cuts the hollow rock specimen while alternately repeating inward and outward movements. _{After the cutting tool goes out a predetermined distance (R offset} ) to the outside of the rock specimen and the indentation depth is adjusted, the inward movement starts, and when the cutting tool moves inwardly, the cutting tool moves into the hollow by a predetermined distance (R _offset ), and then the indentation depth is adjusted We provide a test method for cutting rock specimens under the condition that an outward movement begins and the indentation depth is fixed when moving along a spiral.

Description

Methods for continuous abrasion test of rock cutting tool and, computer-readable media for recording computer programs for realizing the same

The present invention relates to a continuous wear test method for a rock cutting tool. Specifically, in the present invention, a cutting tool moves at a constant speed along an Archimedean spiral in order to perform a pin-on-disk test specified in ASTM, (i) the test method according to the first embodiment is an inward movement and an outward movement During movement, the cutting tool cuts the rock specimen while moving along the same helix. The end point of inward movement becomes the starting point of outward movement, the end point of outward movement becomes the starting point of inward movement, and the starting point of outward movement and the start point of inward movement. The rotation direction of the specimen is reversed, (ii) the test method according to the second embodiment repeats inward movement and outward movement alternately, and the cutting tool cuts the rock specimen while moving along different spirals during inward movement and outward movement and the end point of the inward movement becomes the start point of the outward movement, the end point of the outward movement becomes the start point of the inward movement, and the rotation direction of the rock specimen is the same during outward movement and inward movement, (iii) test according to the third embodiment In this method, the cutting tool cuts the hollow rock specimen while repeating inward and outward movements alternately, but when moving outward, the cutting tool goes _{out a predetermined distance (R offset} ) to the outside of the rock specimen, the indentation depth is adjusted, and then the inward movement starts. When moving inward, the cutting tool moves hollow toward the center by a predetermined distance (R _offset ), then the indentation depth is adjusted and then outward movement starts. When moving along the spiral, the rock specimen is cut under the condition that the indentation depth is fixed. .

In addition, the present invention also includes a computer-readable recording medium for recording a computer program for implementing the continuous wear test method.

In general, for rock/resource excavation tools such as rod headers, continuous miners, and TBM disc cutters, durability performance is directly related to work efficiency.

1 shows an example of a uniformly worn cutting tool. If there is no problem with the build quality of the pick cutter and the design of the arrangement of the cutting head is appropriate, the pick will rotate continuously inside the holder, and the tip of the pick and the front part of the head will be worn evenly.

However, no standard test method or an official test method capable of quantitatively evaluating the durability performance of a rock cutting tool has been proposed so far. On the other hand, ASTM (American Society for Testing and Materials) discloses a pin-on-disk test, which tests metal-to-metal wear.

As shown in FIG. 2, in the pin-on-disk test, the pin moves linearly in the radial direction in a state in which the disk-shaped specimen is rotating about the vertical axis, and wear occurs. At this time, the pin is the rotating specimen. It should form an Archimedean spiral trajectory.

The pin-on-disk test has the advantage of being able to continuously test for more than 1 hour and quantitatively measuring the amount of wear of the pin when testing a metal specimen with a metal pin.

However, ASTM does not specifically describe the motion equations and control methods of pins and specimens, only the basic principles and drawings for the wear test method of metal specimens. There is a problem in that the control method, the equation of motion, and the data extraction method are not specifically described.

As described above, for the pin-on-disk test, the linear movement speed of the cutting tool and the rotation speed of the specimen must be controlled so that the cutting tool forms an Archimedes spiral trajectory on the specimen. ASTM does not describe such a control method. not.

In order to apply the pin-on-disk test to a rock specimen and a rock cutting tool, the present applicant submitted an equation for the radial movement speed of the cutting tool and the rotational speed of the rock specimen for the cutting tool to form an Archimedes spiral trajectory on the rock specimen. Newly proposed, a continuous wear test method, apparatus, and a storage medium recording the computer program of a rock cutting tool using this equation, and this has been filed as Korean Patent Application No. 10-2018-0106405.

The present invention is an improvement of the invention described in the above application, and is proposed in the process of specifying the continuous wear test.

Specifically, for the continuous wear test, the cutting tool alternately repeats inward and outward movements, but moves along the same Archimedean spiral, and the end point of the inward movement becomes the starting point of the outward movement, and the end point of the outward movement is the starting point of the inward movement. The purpose of this study is to provide a test method in which the direction of rotation of the rock specimen is reversed at the starting point of outward movement and inward movement.

Another object of the present invention is that the cutting tool alternately repeats inward and outward movements, and the cutting tool cuts a rock specimen while moving along different spirals during inward and outward movements, and the end point of the inward movement is the starting point of the outward movement This is to provide a test method in which the end point of the outward movement becomes the starting point of the inward movement, and the direction of rotation of the rock specimen during the outward movement and inward movement is the same.

Another object of the present invention is to cut a hollow rock specimen while alternating inward and outward movements, but when moving outward, the cutting tool goes _{out a predetermined distance (R offset} ) to the outside of the rock specimen to adjust the indentation depth and then move inward When this starts and moves inward, the cutting tool moves in the hollow toward the center of the rock specimen by a predetermined distance (R _offset ), then the indentation depth is adjusted and then outward movement starts, and the indentation depth is fixed while moving along the spiral To provide a test method for cutting in

Another object of the present invention is to provide a computer-readable recording medium in which a computer program for implementing the continuous wear test method is recorded.

As described above, the present invention is an improvement of the invention of Korean Patent Application No. 10-2018-0106405, and all contents described in the above patent application are included in this specification and constitute a part of the present invention. And, the content of the invention described in the patent application is summarized as follows.

(1) Outline of pin-on-disk test method

3 is a perspective view showing a main configuration for a pin-on-disk test.

As shown in the figure, in the pin-on-disk test, the rotational force of the driving motor 110 is transmitted to the specimen fixing unit 130 through the rotating shaft 112, and accordingly, the rock specimen 1 is rotated. The cutting tool 10 moves linearly (straight line) from the center of the rock specimen 1 to the outside in a state of being pressed by a load unit (not shown in the drawing) (arrow direction). Meanwhile, although not shown in the drawings, the cutting tool 10 may move linearly (linearly) from the outer to the center of the rock specimen 1, or may repeatedly reciprocate from the center to the outer.

The linear movement of the cutting tool 10 may be performed by a linear movement unit (not shown in the drawing).

As described above, for the pin-on-disk test, the cutting tool 10 must move at a constant speed (constant speed) along the Archimedean spiral from the upper surface 3 of the rock specimen 1 . And, in the Archimedean spiral, the spacing between the spirals must be constant.

(2) the control equation for the cutting tool to move at a constant velocity along the Archimedean spiral

The coordinates of any point on the Archimedean spiral in the xy coordinate system can be expressed as (r(t)·cos(θ(t)), r(t)·sin(θ(t))) . As shown in Fig. 4, r(t) and θ(t) express the spiral radius and the rotation angle (the angle measured in the counterclockwise direction with respect to the +x axis) as arbitrary functions with respect to time (t), respectively. .

When the length (L) of the curve (spiral) is expressed with respect to the time (t) during which the spiral path travels, the following Equation 1 is obtained.

[Equation 1]

In the above formula,

L: Distance traveled by the cutting tool along the Archimedean spiral.

If Equation 1 is differentiated with respect to time t, it becomes a velocity expression of a point moving on the Archimedean spiral, and the equation is the same as Equation 2 below.

[Equation 2]

In the above formula,

V _L : The speed at which the cutting tool moves along the Archimedean spiral.

If the spiral radius (r) and the rotation angle (θ), which make Equation 2 have constant values, can be obtained by inverse calculation, the radial speed (radial speed of the cutting tool) and the rotation speed to move the Archimedean spiral at a constant speed (Rotational speed of the rock specimen) can be expressed as a formula.

However, since a lot of trigonometric functions for time (t) are included in Equations 1 and 2, it is impossible to calculate the radial and rotational speeds satisfying the constant velocity through simple inverse calculation (equation solving) (i.e., , it is impossible to calculate an exact solution of a differential equation).

On the other hand, in the field of Atomic Force Microscopy (AFM) and Scanning Transmission Electron Microscopy (STEM), a method for moving the Archimedean spiral at a constant speed (Constant Linear Velocity, CLV) has been developed to increase the scanning quality. has been studied. Examples and specific contents of this study are as follows.

According to the research results, in the path moving from the inside to the outside of the circle (outward path), the spiral radius (r) and the rotation angle (θ) can be expressed as Equations 3 and 4 (the spiral radius and the rotation angle) 4 for definitions).

[Equation 3]

[Equation 4]

In the above formula,

t _* =t/T (a dimensionless number)

T: the time it takes for the cutting tool 10 to move from the center to the outer edge along the helical trajectory or from the outer to the center

N: number of helices (eg, N=5 in FIG. 4 )

R: radius of the outermost part of the helix

f(t _* ) : In the case of an outward spiral, any function (any form is possible) satisfying f(0)=0, f(1)=1, in the case of an inward spiral , any function that satisfies f(0)=1 and f(1)=0 (any form is possible).

After substituting Equations 3 and 4 into Equation 1 _{, and differentiating it with respect to t *} , Equation 5 below can be obtained.

[Equation 5]

In the above formula,

V _L : The speed at which the cutting tool moves along the Archimedean spiral.

_{Since it is impossible to calculate f(t *} ), which makes Equation 5 a constant, as a differential equation, an approximate solution must be found.

를 제시하고 있는데, 이를 수학식 5에 적용하면 'V_L = 상수'로 근사하여 표현할 수 있다(수학식 6 참조). The above existing research results (research results in the field of atomic force microscopy and scanning transmission electron microscopy) are outward spiral

, which can be approximated and expressed as _{'V L} = constant' when applied to Equation 5 (see Equation 6).

[Equation 6]

The derivation process of Equation 6 is as follows.

이라는 해를 계산할 수 있다. '+1'항 앞에는 2π, N, f(t_*)가 곱해진 후 제곱된 항이 존재하는데, f(t_*)가 0에서 조금만 멀어지면 숫자가 금방 커지므로 '+1"을 없애도 전체적으로 보면 충분히 실질적으로 동일한 함수를 얻을 수 있다. The reason that the exact solution of the differential equation cannot be obtained in Equation 5 is because of the '+1' term in the root on the left.

can be calculated. In front of the '+1' term, there is a term that is squared after being multiplied by _{2π, N, f(t * ). If f(t *} ) is slightly farther from 0, the number quickly increases, so even removing '+1' is sufficient. You can get practically the same function.

The present applicant implemented CLV by applying the above research results to the pin-on-disk test. Although the existing research results are used, the present invention has a significantly different technical field, and the difficulty of construction is required in the process of applying the existing research results to the present invention, and the originality of the inventor is added. Progressivity alone should not be denied.

를 수학식 3, 4에 대입하고 t에 대해 미분하면 아래 수학식 7, 8을 얻을 수 있다. Meanwhile,

By substituting in Equations 3 and 4 and differentiating with respect to t, Equations 7 and 8 below can be obtained.

[Equation 7]

[Equation 8]

Equation 7 represents the linear movement speed of the cutting tool in the case of an outward spiral. However, when t=0, for example, when 0≤t≤1, the linear movement speed becomes excessively large, so a constant linear movement speed may be input to the test apparatus during an actual test.

And, Equation 8 represents the rotational speed of the rock specimen in the case of an outward spiral. However, at the start stage of the test near t=0 (for example, when 0≤t≤0.1 seconds), the rotational speed temporarily increases excessively and converges to a constant speed, so after the actual test, this should be considered when processing the result data. . This part is an error of the approximation solution, but it occurs locally within 0.1 second, so it is a negligible error.

를 적용하여 계산할 수 있는데, 이를 수학식 3, 4에 대입하고 t에 대해 미분하면 아래 수학식 9, 10을 얻을 수 있다. On the other hand, in the case of an inward spiral (where the cutting tool moves from the outside to the center of the rock specimen),

It can be calculated by applying Equations 3 and 4, and by differentiating it with respect to t, Equations 9 and 10 below can be obtained.

[Equation 9]

[Equation 10]

Equation 9 represents the linear movement speed of the cutting tool in the case of an inward spiral. However, when t = T, for example, when T = 100 sec, when 99.9 seconds ≤ t ≤ 100 seconds, the linear movement speed becomes excessively large and converges at a constant speed, so the user must consider this when processing data. However, this is also an error that occurs for a very short time and is negligible by the user.

In the test method according to the first embodiment of the present invention, in a state in which the rock specimen is rotated with respect to the center of the rock specimen, the cutting tool cuts the rock specimen while linearly moving from the outer to the center of the upper surface 3 of the rock specimen. It is a test method that alternately repeats inward movement and outward movement of cutting a rock specimen while moving linearly from the center to the outside, and the cutting tool cuts the rock specimen while moving along the same spiral during inward movement and outward movement, The moving speed of the moving cutting tool is constant, and the spacing between the helixes is the same. Then, the end point of the inward movement becomes the start point of the outward movement, the end point of the outward movement becomes the start point of the inward movement, and the rotation direction of the rock specimen is reversed at the start point of the outward movement and the start point of the inward movement.

The spiral trajectory of the inward movement is the same as Equation 1 below, and the spiral trajectory of the outward movement is the same as Equation 2 below.

In Equations 1 and 2 above,

t: time

r _inw (t) : Radial distance between the origin and the cutting tool at a specific time t when moving inward

f _inw (t) : _{any function that satisfies f inw} (0)=1, f _inw (1)=0

R: outer diameter of the rock specimen

θ _inw (t): the angle of rotation of the rock specimen at a specific time t during inward movement

N: number of spirals

θ _f : phase angle at which the cutting tool is located when t=0

P _xinw (t): the x-axis coordinate of the cutting tool at a specific time t when moving inward

P _yinw (t): y-axis coordinate of the cutting tool at a specific time t when moving inward

r _outw (t) : Radial distance between the origin and the cutting tool at a specific time t during outward movement

f _outw (t) : _{any function satisfying f outw} (0)=0, f _outw (1)=1

θ _outw (t): the rotation angle of the rock specimen at a specific time t during outward movement

P _xoutw (t) : the x-axis coordinate of the cutting tool at a specific time t during outward movement

P _youtw (t): the y-axis coordinate of the cutting tool at a specific time t during outward movement

The rock specimen is preferably a hollow specimen in which a hollow is vertically formed in the center. In the test method, the cutting tool alternately repeats inward movement and outward movement, but starts from inward movement, and inward movement starts at (R, 0), and satisfies the following equation. And, the inwardly moving 0≤t≤Tt _0, t ₀ is the outward movement ≤t≤T. Tt ₀ is the time for the cutting tool to make a helical movement.

[expression]

In the above formula,

R _o : diameter of the hollow

s: spacing between spirals

v : The speed at which the cutting tool moves along the helical trajectory (constant)

T: The time it takes for the cutting tool to move from the center of the rock specimen to the outer edge or from the outer edge to the center along the helical trajectory.

_Inw the f (t) and f _outw (t) is preferably satisfies the following equation.

[expression]

In the test method according to the second embodiment of the present invention, in a state in which the rock specimen is rotated with respect to the center of the rock specimen, the cutting tool cuts the rock specimen while linearly moving from the outer to the center of the upper surface 3 of the rock specimen. It is a test method that alternately repeats an inward movement and an outward movement of cutting a rock specimen while moving linearly from the center to the outside, and the cutting tool cuts the rock specimen while moving along different spirals during inward and outward movement, The moving speed of the cutting tool moving along is constant, and the spacing between the helixes is the same. And, the end point of the inward movement becomes the starting point of the outward movement, the end point of the outward movement becomes the starting point of the inward movement, and the rotation direction of the rock specimen is the same during the outward movement and inward movement.

The cutting tool starts with inward movement, but alternately repeats inward movement and outward movement, and the phase angle of the cutting tool during inward movement and outward movement is as follows.

In the above formula,

t: time

N: number of spirals

f _inw (t) : _{any function that satisfies f inw} (0)=1, f _inw (1)=0

f _outw (t) : _{any function satisfying f outw} (0)=0, f _outw (1)=1

T: The time it takes for the cutting tool to move from the center of the rock specimen to the outer edge or from the outer edge to the center along the helical trajectory.

Tt ₀ : The time the cutting tool travels along the helical trajectory when moving inward and outward, respectively.

θ ₀ : A constant used to match the radius and angle at the end point of the inward movement (R ₀ ) and the starting radius and angle of the outward movement.

_Inw the f (t) and f _outw (t) is preferably satisfies the following equation.

[expression]

Preferably, the difference between the inclination of the end point of the inward movement and the inclination of the start point of the outward movement and the difference between the inclination of the inclination of the end point of the outward movement and the start point of the inward movement are 0.5° to 5°.

In the test method according to the third embodiment of the present invention, in a state in which the rock specimen is rotated with respect to the center of the rock specimen, the cutting tool cuts the rock specimen while linearly moving from the outer to the center of the upper surface 3 of the rock specimen. The rock specimen is cut by inward movement or outward movement, which cuts the rock specimen while linearly moving from the center to the outside. Accordingly, a spiral-shaped cut is made on the upper surface 3, and the rock specimen has a hollow in the center part vertically. Formed specimen, the cutting tool moves inwardly by at least a predetermined distance (R _offset ) into the hollow, then the indentation depth is adjusted, and then starts to move outward, and when moving outward, goes out to the outside of the rock specimen by a predetermined distance (R _offset ) is adjusted and then inward movement begins. In addition, the moving speed of the cutting tool moving along the spiral is constant, and the interval between the spirals is the same.

Preferably, the cutting tool cuts the rock specimen while alternating inward and outward movements, but when moving inward, the cutting tool moves _{spirally from a place spaced apart by a predetermined distance (R offset} ) to the outside of the rock specimen while spirally moving the rock specimen When moving outward, the cutting tool enters the rock specimen while moving spirally from a location spaced apart from the center of the rock specimen by R _o -R _offset. On the other hand, the R _o is the radius of the hollow.

It is preferable to cut while maintaining a constant indentation depth while the cutting tool moves along the helix.

The linear movement speed of the cutting tool and the rotational speed of the rock specimen may be calculated by the following equation.

[expression]

In the above formula,

Vr _outw : Radial linear movement speed of the cutting tool when moving outward

R: radius of the specimen

R _offset : The distance that the cutting tool leaves the rock specimen when moving outward, or the distance it moves toward the center of the rock specimen when moving inward.

t: time

T : Time taken to move from the center of the rock specimen to 'R+R _{offset' when the cutting tool moves inward or outward}

RPM _outw : Rotational speed of rock specimen when moving outward

N: Number of spirals formed from the center of the rock specimen to 'R+R _offset'

Vr _inw : Radial linear movement speed of the cutting tool when moving inward

RPM _inw : Rotational speed of the rock specimen when moving inward

The recording medium, which is another aspect of the present invention, records a computer program capable of automatically calculating the radial movement speed of the cutting tool and the rotational speed of the rock specimen in order to implement the continuous wear test method.

The present invention is a further improvement of the continuous wear test described in Korean Patent Application No. 10-2018-0106405 previously filed by the present applicant, and has the following effects.

First, for the continuous wear test, the cutting tool alternately repeats inward and outward movements, but moves along the same Archimedean spiral, and the end point of the inward movement becomes the starting point of the outward movement, and the end point of the outward movement becomes the starting point of the inward movement, A test method in which the direction of rotation of a rock specimen is reversed at the starting point of outward movement and inward movement is provided.

Second, the cutting tool alternately repeats inward and outward movements, and the cutting tool cuts the rock specimen while moving along different Archimedean spirals during inward and outward movements, and the end point of the inward movement becomes the starting point of the outward movement, The end point of the movement becomes the starting point of the inward movement, and the direction of rotation of the rock specimen during outward and inward movement is the same, providing a test method.

Third, the hollow rock specimen is cut while alternately repeating inward and outward movements along the Archimedean spiral, but when moving outward, the cutting tool goes _{out a predetermined distance (R offset} ) to the outside of the rock specimen, and after the indentation depth is adjusted, inward movement is not possible. After starting and moving inward, the cutting tool moves into the hollow by a predetermined distance (R _offset ), then the indentation depth is adjusted and then outward movement starts. Provides a test method in which the indentation depth is fixed while moving along the spiral. do.

Fourth, in order to implement the continuous wear test method, there is provided a recording medium recording a computer program capable of automatically calculating the radial movement speed of the cutting tool and the rotational speed of the rock specimen.

1 is a photograph showing an example of a uniformly worn cutting tool.
Figure 2 is a perspective view showing a pin-on-disk test specified in ASTM.
3 is a perspective view showing a main configuration for a pin-on-disk test.
4 is a view showing the definition of a helix radius (r) and a rotation angle (θ) in an Archimedean spiral.
5 is a view showing the helical trajectory when the cutting tool moves inward while the rock specimen is rotating in the test method according to the first embodiment of the present invention.
6 is a view showing the helical trajectory when the cutting tool moves outward in a state in which the rock specimen is rotating in the test method according to the first embodiment of the present invention.
7 is a helical trajectory (left) when the cutting tool moves inwardly while the rock specimen is rotating in the test method according to the second embodiment of the present invention, and the helical trajectory when moving outward (middle) and a diagram showing an overlapping of the inward spiral trajectory and the outward spiral trajectory (right).
8 is a view showing a section (left) in which a cutting tool cuts a rock specimen under a condition of a constant indentation depth (left) and a section (right) in which a cutting tool cuts a rock specimen under a condition of a constant load (right);
9 is a perspective view showing a rock specimen used in the third embodiment of the present invention and definitions of each symbol;
10 is a helical trajectory (left) when the cutting tool moves inwardly in a state in which the rock specimen is rotating in the test method according to the third embodiment of the present invention, and the helical trajectory when moving outward (right) drawings showing each.

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 conventional or dictionary meanings, and the inventor should properly understand the concept of the term in order to best describe his invention. Based on the principle that it can be defined, it should be interpreted as meaning and concept consistent with the technical idea of the present invention. Accordingly, since the embodiments described in the present specification and the configurations shown in the drawings are merely embodiments of the present invention and do not represent all the technical spirit of the present invention, various equivalents that can be substituted for them at the time of the present application It should be understood that there may be variations and variations.

[First embodiment]

As described above, in the test method according to the first embodiment of the present invention, the cutting tool alternately repeats inward movement and outward movement, but moves along the same Archimedean spiral, and the end point of the inward movement becomes the starting point of the outward movement, and the outward movement The end point of is the starting point of the inward movement, and the direction of rotation of the rock specimen is reversed at the start point of the outward movement and the inward movement.

5 is a view showing a spiral trajectory formed when the cutting tool moves inward while the rock specimen is rotating, and FIG. 6 is a spiral formed when the cutting tool moves outward while the rock specimen is rotating A drawing showing the trajectory.

The input variables are R (outer diameter of the hollow specimen), R ₀ (diameter of the hollow), S (space between the helixes, S in Fig. 4), and v (the movement speed of the cutting tool moving along the helix). Then, from this, Tt ₀ (the time the cutting tool moves along the helix), N (the number of helixes) and θ (the rotation angle) can be calculated.

As described above, the spiral path for moving the Archimedean spiral with Constant Linear Velocity (CLV) can be calculated as follows. However, the spiral path starts at (R,0) on the x-axis and starts from an inward spiral, moving inward (inward spiral) → moving outward (outward spiral) → moving inward (inward spiral) → outward Cut while repeating movement (outward spiral) ...... alternately.

The trajectory (path) of the inward spiral is shown in Equations (1) to (5) below. (t=0~(Tt ₀ ))

The trajectory (path) of the outward spiral is shown in Equations (6) to (10) below. (t=t ₀ ~T)

Calculation of parameters used in both inward and outward helix is as Equation (11). Here, θ _f is the value applied to make the inward spiral start at (R,0) on the x-axis (the phase angle at the end of the previous helix).

When the calculation is performed by setting the variables for calculating the Archimedes spiral as shown in Table 1 below, it is shown in FIGS. 5 (inward spiral) and 6 (outward spiral). 5 to 6 , it can be seen that the inward spiral and the outward spiral move in opposite directions along the same spiral path.

[Second embodiment]

In the test method according to the second embodiment of the present invention, the cutting tool alternately repeats inward and outward movements, and the cutting tool cuts a rock specimen while moving along different Archimedean spirals when moving inward and outward. It is a test method in which the end point becomes the starting point of outward movement, the end point of outward movement becomes the starting point of inward movement, and the direction of rotation of the rock specimen during outward and inward movement is the same.

In this test method, as the rock specimen continues to rotate in the same direction, there is no strain on the motor for rotating the specimen. In contrast, the test method of the first embodiment may be burdensome in the case of a device with a large rotational inertia because the rotational direction of the rock specimen must be instantaneously reversed at the end point of the inward spiral and the end of the outward spiral.

On the other hand, FIG. 7 shows a spiral trajectory when the cutting tool moves inwardly (left diagram), a spiral trajectory when the cutting tool moves outward (middle diagram), and an inward spiral in the test method according to the second embodiment of the present invention. The superimposition of the trajectory and the outward spiral trajectory (right drawing) is shown, respectively.

The inward spiral starts at (R,0) on the x-axis and alternates inward movement (inward spiral) → outward movement (outward spiral) → inward movement (inward spiral) → outward movement (outward spiral) ...... Repeatedly cutting, but moving along different trajectories (paths), and the direction of rotation of the rock specimen is the same.

The trajectory (path) of the inward spiral is the following equations (12) to (16) (t = 0 to (Tt ₀ )), which is the same as the Archimedean spiral of the first embodiment (that is, the path of the initial inward spiral is both cases are the same).

The trajectory (path) of the outward spiral is as follows (17) to (21) (t=t ₀ to T).

Calculation of parameters used in both the inward spiral and the outward spiral is the same as in Equation (11) above. Here, θ _{0 is a value used to match the radius (R 0} ) and angle at the end point of the inward spiral with the starting radius and angle of the outward spiral. When the calculation is performed by setting the constants as shown in Table 1 above, it is as shown in FIG. 7 (the trajectories (paths) of the two spirals are different, but the constants of the functions are the same). Since the outward helix begins where the inward helix ends, it can be seen that the different helix paths move in the same direction of rotation.

As shown in the graph on the right of Fig. 7, the instantaneous slope (dy/dx) of the spiral path is different when switching from an inward spiral to an outward spiral (about -1.71 for an inward spiral, about -1.12 for an outward spiral), so the connection between the spirals is not smooth. Can not do it. (Refer to the discontinuous point indicated in green in FIG. 7 ) In particular, the difference in inclination increases as the helix interval (s) increases, because the inclinations are different when different helices have the same radius.

The slope difference may be calculated by the following equation.

By adjusting the four constant values in Table 1, the difference between the slope of the end point of the inward movement and the start point of the outward movement, and the slope of the end point of the outward movement and the inclination difference of the start point of the inward movement are 0.5° to 5° it is preferable If the slope difference is greater than 5°, the connection between the spirals is not smooth, which may cause problems in continuous data acquisition. If the slope difference is less than 0.5°, the interval between the spirals is too tight, which may cause problems in the test. Not desirable.

As such, in the case of different paths and spiral paths having the same rotational direction, it is relatively difficult to calculate the helix because the paths of the inward spiral and outward spiral are different from each other. In particular, as the inward spiral/outward spiral is switched, the end point and the start point of the spiral path coincide when the end position and angle are input as the initial start position and angle to implement the path. For this, the angle (Equation 14, Equation 19) must be calculated as follows.

In the above formula,

t: time

N: number of spirals

f _inw (t) : _{Any function that satisfies f inw} (0)=1, f _inw (1)=0. For example

f _outw (t) : _{Any function satisfying f outw} (0)=0, f _outw (1)=1. For example

T: The time it takes for the cutting tool to move from the center of the rock specimen to the outer edge or from the outer edge to the center along the helical trajectory.

Tt ₀ : The time the cutting tool travels along the helical trajectory.

θ ₀ : A constant used to match the radius and angle at the end point of the inward movement (R ₀ ) and the starting radius and angle of the outward movement

According to the above angle calculation method, inward movement (inward spiral) → outward movement (outward spiral) → inward movement (inward spiral) → outward movement (outward spiral) ...... is repeated in the formula for calculating the angle The regularity is seen, that is, the angle is calculated by reflecting the ending angle of the previous helix, and the method of calculating the angle of the inward helix and the angle of the outward helix is different. Based on the above formula and regularity, a continuous spiral path in the same rotational direction can be created.

[Third embodiment]

FIG. 8 shows a cross section in which a cutting tool cuts a rock specimen under a condition of a constant indentation depth (left drawing) and a cross section in which a cutting tool cuts a rock specimen under a condition of a constant load (right drawing), respectively.

During the pin-on-disk test, if a vertical load is applied as much as the indentation depth directly from the top of the specimen without setting the _{distance (separation distance, R offset ) to the outside of the specimen, several problems occur.} To explain this in detail, since the vertical pressure of the motor driver is excessively required, the capacity of the vertical electric motor should be increased from the original design value. In this case, since a hydraulic motor is generally not used, an additional cost is incurred in purchasing a high-capacity electric motor.

And, in order to reach a specific indentation depth, a specific vertical load must be applied, and in the end, the test must be conducted under a constant load condition. However, when the surface properties of the specimen are non-uniform, the cutting test may proceed while the cutting tool rides over the high hardness part. Therefore, as shown in the right drawing of FIG. 9 , there is a risk that an uneven surface is generated and continuously accumulated after the wear test depending on the surface hardness.

(1) A method for stably implementing the indentation depth

In order to solve this problem, in this embodiment, a cutting tool (pick cutter, etc.) goes out of the specimen to adjust the vertical indentation depth. And, the outgoing separation distance is defined _{as R offset.} At this time, the actual distance (the distance the cutting tool actually moved, L _total ), the wear distance (the distance the cutting tool moved while cutting the rock specimen, L _test ), the total travel time (T _total ), and the actual wear time (T _test) ) must be calculated to enable test setting.

(2) Definition of variables and constants

As shown in FIG. 9, it is assumed that inward spiral movement and outward spiral movement are alternately repeated along the Archimedean spiral for a hollow specimen in which a hollow is formed perpendicularly to the central portion of the specimen. Constants and time variables can be defined. Each constant and time variable can be defined as follows.

R: outer diameter of the hollow specimen [mm]

R ₀ : inner diameter of hollow specimen [mm]

R _offset : Length of cutting tool (pick cutter, etc.) out of the hollow specimen [mm]

t ₀ : time taken to move from the center of rotation of the hollow specimen to (R ₀ -R _{offset ) [s]}

t ₁ : Time taken to move from the center of rotation of the hollow specimen to R _{0 [s]}

t ₂ : Time taken to move from the center of rotation of the hollow specimen to R [s]

T=T _total : Time taken to move from the center of rotation of the hollow specimen to (R+R _{offset) [s]}

T _move : Actual movement time of the cutting tool. That is, the time it takes for the cutting tool to move from (R ₀ -R _offset ) to (R+R _{offset ) [s]}

T _test : The time at which the actual rock specimen was worn (contact time with the specimen). That is, T _test =t ₂ -t ₁ [s]

(3) Spiral function calculation and setting

The total number of helixes (N=N _total ), the number of helixes that the cutting tool actually moves (N _move ), and the number of helixes actually worn on a rock specimen (N _test ) can be calculated as follows.

The travel time can be calculated as:

That is, T=T _total , T _move =Tt ₀ , T _real =t ₂ -t ₁ .

And, in equation (27),

v : speed at which the cutting tool moves along the helix (constant)

The travel distance can be calculated as follows.

Here, L _inwtotal , L _inwtest , L _outwtotal , and L _outwtest are the total travel distance of inward movement, wear test distance of inward movement, total movement distance in outward direction, and wear test distance of outward direction, respectively.

In addition, the calculation formulas of the trajectory of the inward spiral (P _xinw , P _yinw ) and the trajectory of the outward spiral (P _xoutw , P _youtw ) are as follows.

In _{the test in which R offset} is considered, five inherent constants can be defined as shown in Table 2 below. Input variable values for calculation are arbitrarily designated as shown in Table 2, and the output table can be organized into thirteen as shown in Table 3.

On the other hand, when the trajectory (path) of the inward spiral is expressed as a graph, it is the same as the left graph of FIG. 10 , and when the trajectory (path) of the outward spiral is expressed as a graph, it is the same as the right graph of FIG. 10 . In FIG. 10 , the gray path represents the entire path, and the red and blue paths represent the wear test path, respectively.

(4) Radial displacement and rotational displacement are expressed in linear speed and RPM, respectively.

The rotary motor that rotates the rock specimen and the linear motor drive that moves the cutting tool in a straight line are both controlled by speed. Therefore, since the path calculation formulas (Equations 35-38) express the local point of the cutting tool, it is necessary to convert it into linear speed and RPM by differentiating it.

When applying the _offset R, the radial velocity (vr _outw, vr _inw) and RPM (RPM _{outw, inw} RPM) is equal to the expression below.

In the above formula,

Vr _outw : Radial linear movement speed of the cutting tool when moving outward

R: outer diameter of the specimen

R _offset : The distance that the cutting tool leaves the rock specimen when moving outward, or the distance it moves toward the center of the rock specimen when moving inward.

t: time

T : Time taken to move from the center of the rock specimen to 'R+R _{offset' when the cutting tool moves inward or outward}

RPM _outw : Rotational speed of rock specimen when moving outward

N: Number of spirals formed from the center of the rock specimen to 'R+R _offset'

Vr _inw : Radial linear movement speed of the cutting tool when moving inward

RPM _inw : Rotational speed of the rock specimen when moving inward

On the other hand, above Equations 39 to 42 can also be applied when moving the cutting tool and the rock specimen as in the first and second embodiments.

_{That is, when cutting a hollow rock specimen in consideration of R offset} in the first embodiment, the cutting tool cuts the rock specimen while moving along the same spiral during inward and outward movement, and the end point of the inward movement is the starting point of the outward movement. and the end point of the outward movement becomes the starting point of the inward movement, and the rotational direction of the rock specimen may be reversed at the start point of the outward movement and the start point of the inward movement. And, in the second embodiment, _{when cutting a hollow rock specimen in consideration of R offset} , inward movement and outward movement are alternately repeated, and the cutting tool cuts the rock specimen while moving along different spirals during inward movement and outward movement. The end point of the inward movement becomes the starting point of the outward movement, and the end point of the outward movement becomes the starting point of the inward movement, and the direction of rotation of the rock specimen may be the same during outward movement and inward movement. Since a person skilled in the art with reference to the present specification can easily or clearly understand the configuration of this point, a detailed description thereof will be omitted herein.

1: rock specimen 3: upper surface of rock specimen (1)
10: cutting tool 110: drive motor
112: rotation shaft of the drive motor 130: specimen fixing part

Claims (13)

In a state in which the rock specimen is rotated with respect to the center of the rock specimen, the cutting tool linearly moves from the outer to the center of the upper surface 3 of the rock specimen to cut the rock specimen in inward movement and linearly moves from the center to the outer side to cut the rock specimen. It is a test method that alternately repeats the outward movement of cutting,
The cutting tool cuts the rock specimen while moving along the same spiral during inward and outward movement, the cutting tool moving along the spiral has a constant moving speed, and the spacing between the spirals is the same,
A rock cutting tool, characterized in that the end point of the inward movement becomes the starting point of the outward movement, the end point of the outward movement becomes the starting point of the inward movement, and the direction of rotation of the rock specimen is reversed at the starting point of the outward movement and the starting point of the inward movement of continuous wear test method. According to claim 1,
A continuous wear test method for rock cutting tools, characterized in that the spiral trajectory of inward movement is the same as Equation 1 below, and the spiral trajectory of outward movement is the same as Equation 2 below.
[Equation 1]

[Equation 2]

In Equations 1 and 2 above,
t: time
r _inw (t) : Distance between the origin and the cutting tool at a specific time t when moving inward
f _inw (t) : _{any function that satisfies f inw} (0)=1, f _inw (1)=0
R: outer diameter of the rock specimen
θ _inw (t): the angle of rotation of the rock specimen at a specific time t during inward movement
N: number of spirals
θ _f : phase angle at which the cutting tool is located when t=0
P _xinw (t): the x-axis coordinate of the cutting tool at a specific time t when moving inward
P _yinw (t): y-axis coordinate of the cutting tool at a specific time t when moving inward
r _outw (t) : The distance between the origin and the cutting tool at a specific time t during outward movement
f _outw (t) : _{any function satisfying f outw} (0)=0, f _outw (1)=1
θ _outw (t): the rotation angle of the rock specimen at a specific time t during outward movement
P _xoutw (t) : the x-axis coordinate of the cutting tool at a specific time t during outward movement
P _youtw (t): the y-axis coordinate of the cutting tool at a specific time t during outward movement 3. The method of claim 2,
The rock specimen is a specimen with a hollow inside,
The cutting tool alternately repeats inward movement and outward movement, but starts from inward movement, and inward movement starts at (R, 0), and the continuous wear test method of a rock cutting tool, characterized in that it satisfies the following equation.
[expression]

In the above formula,
R _o : diameter of the hollow
s: spacing between spirals
v : The speed at which the cutting tool moves along a spiral trajectory.
T: The time it takes for the cutting tool to move from the center of the rock specimen to the outer edge or from the outer edge to the center along the spiral trajectory. 4. The method of claim 3,
_inw f (t) and f _outw continuous abrasion test method (t) is to satisfy the following expression, rock cutting tool.
[expression]

In a state in which the rock specimen is rotated with respect to the center of the rock specimen, the cutting tool linearly moves from the outer to the center of the upper surface 3 of the rock specimen to cut the rock specimen in inward movement and linearly moves from the center to the outer side to cut the rock specimen. It is a test method that alternately repeats the outward movement of cutting,
The cutting tool cuts the rock specimen while moving along different helixes during inward and outward movement, the moving speed of the cutting tool moving along the helix is constant, and the spacing between the helices is the same,
A continuous wear test method for rock cutting tools, characterized in that the end point of the inward movement becomes the start point of the outward movement, the end point of the outward movement becomes the start point of the inward movement, and the rotational direction of the rock specimen during outward movement and inward movement is the same. 6. The method of claim 5,
The cutting tool starts with an inward movement, alternating inward and outward movements,
A continuous wear test method for a rock cutting tool, characterized in that the phase angle of the cutting tool during inward movement and outward movement is as follows.

In the above formula,
t: time
N: number of spirals
f _inw (t) : _{any function that satisfies f inw} (0)=1, f _inw (1)=0
f _outw (t) : _{any function satisfying f outw} (0)=0, f _outw (1)=1
T: The time it takes for the cutting tool to move from the center of the rock specimen to the outer edge or from the outer edge to the center along the spiral trajectory.
Tt ₀ : The time the cutting tool travels along the helical trajectory.
θ ₀ : A constant used to match the radius and angle at the end point of the inward movement (R ₀ ) and the starting radius and angle of the outward movement. 7. The method of claim 6,
_inw f (t) and f _outw continuous abrasion test method (t) is to satisfy the following expression, rock cutting tool.
[expression]

8. The method of claim 7,
Continuous wear test method for rock cutting tools, characterized in that the difference between the inclination of the end point of the inward movement and the inclination of the start point of the outward movement and the difference between the inclination of the end point of the outward movement and the start point of the inward movement are 0.5° to 5° . In a state in which the rock specimen is rotated with respect to the center of the rock specimen, the cutting tool cuts the rock specimen while alternating inward and outward movements,
In the inward movement, the cutting tool cuts the rock specimen while moving linearly from the outer to the center of the upper surface 3 of the rock specimen, and in the outward movement, the cutting tool linearly moves from the center of the upper surface 3 of the rock specimen to the outside of the rock specimen. is cut, and accordingly, a spiral-shaped cut is made on the upper surface (3),
The rock specimen is a specimen in which a hollow is formed vertically in the central part, and the cutting tool moves to the hollow by at least a predetermined distance (R _offset ) when moving inward, the indentation depth is adjusted, then starts moving outward, and moves outward to the outside of the rock specimen After going out by a predetermined distance (R _offset ), the indentation depth is adjusted, and then inward movement is started,
A continuous wear test method for a rock cutting tool, characterized in that the moving speed of the cutting tool moving along the helix is constant and the spacing between the helixes is the same. 10. The method of claim 9,
When moving inward, the cutting tool enters the rock specimen while spirally moving from a place spaced apart by a _{predetermined distance (R offset) to the outside of the rock specimen,}
During outward movement, the cutting tool enters the rock specimen while moving spirally from a location spaced apart from the center of the rock specimen by R _o -R _offset.
R _o is a continuous wear test method of a rock cutting tool, characterized in that the radius of the hollow. 10. The method of claim 9,
A continuous wear test method for a rock cutting tool, characterized in that cutting is performed while maintaining a constant indentation depth while the cutting tool moves along the helix. 11. The method of claim 10,
A continuous wear test method for rock cutting tools, characterized in that the linear movement speed of the cutting tool and the rotational speed of the rock specimen are calculated by the following equation.
[expression]

In the above formula,
Vr _outw : Radial linear movement speed of the cutting tool when moving outward
R: radius of the specimen
R _offset : The distance that the cutting tool leaves the rock specimen when moving outward, or the distance it moves toward the center of the rock specimen when moving inward.
t: time
T : Time taken to move from the center of the rock specimen to 'R+R _{offset' when the cutting tool moves inward or outward}
RPM _outw : Rotational speed of rock specimen when moving outward
N: Number of spirals formed from the center of the rock specimen to 'R+R _offset'
Vr _inw : Radial linear movement speed of the cutting tool when moving inward
RPM _inw : Rotational speed of the rock specimen when moving inward 13. A computer program for implementing the continuous wear test method of any one of claims 1 to 12, wherein the computer program calculates the radial movement speed of the cutting tool and the rotational speed of the rock specimen. readable recording medium.

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