Background
Generalized rock breaking cutters including hobs, cutters, drills, pickaxes, etc. are widely used in mechanical engineering, geotechnical engineering and tunnel engineering, where: disc cutter (hereinafter referred to as cutter) is used for cutting and breaking hard rock, and is a main rock breaking cutter of a full-face hard rock tunnel boring machine (Tunneling boring machine, hereinafter referred to as TBM) and a shield; the cutter is used for cutting soft rock and soil, and is a main rock (soil) breaking cutter of the shield. The rock breaking mechanism of the rock breaking tool is very complex due to severe and changeable stratum geological conditions, but extrusion rock breaking is one of the most common and wide rock breaking mechanisms of the rock breaking tool.
Taking a TBM hob as an example, specifically, the hob directly contacts and rolls and cuts rock by means of a cutter ring, and applies huge extrusion stress to enable the rock to be highly powdered and densified, so that a compact core similar to the processes of drilling, impact rock drilling, cutting pick cutting and the like is formed at the blade bottom; in the process of rock breaking by continuously revolving, rolling and pressing of the hob, the dense nuclear material at the blade bottom is periodically derived, developed and collapsed.
As is common in the aforementioned extrusion rock breaking mechanisms, the phenomenon of dense nuclei is widely present in the rock breaking process of the above-mentioned rock breaking tools, and the dynamic derivatization mechanism thereof definitely directly influences the rock breaking mechanism of the rock breaking tools and changes the boundary conditions of the tool-rock interaction, i.e. in the initial state, the hob comes into contact with the complete fresh rock mass, but in the relatively stable continuous rotary rolling rock breaking process, the contact with the blade bottom is not the complete fresh rock mass but dense nuclear material. In addition, according to the conclusion of a dense core theory proposed by soviet union expert A.H. Bilong in coal mining engineering, the dense core phenomenon at least has a great influence on the friction and wear performance of a hob ring, so that extremely adverse contact force characteristics are generated on a hob contact interface, and the hob wear service life is seriously shortened.
However, due to the lack of a feasible physical test device for simulating and reproducing the continuous grinding and sliding action of the compact nuclear substance on the edge bottom of the rock breaking cutter in the compact nuclear region, and the lack of a reasonable cutter opposite grinding test method for quantitatively and intensively researching the continuous grinding and sliding action process of the compact nuclear substance on the edge bottom of the rock breaking cutter, the compact nuclear phenomenon is not considered in the research of the friction and abrasion mechanism of the conventional hob ring material.
Therefore, the rock breaking cutter material-compact core material counter-grinding test method which is economical, convenient and meets engineering requirements is provided, and particularly relates to the rock breaking cutter material-compact core material counter-grinding test method which considers the effect of the compact core material on grinding and sliding the blade bottom, which is an urgent problem to be solved in the industry.
Disclosure of Invention
Aiming at the defects in the prior art, the application provides a rock breaking cutter material-compact core substance counter grinding test method, which comprises the following steps:
s1: basic information related to friction and wear performance of a hob ring (hereinafter referred to as a hob ring) under study is obtained, including but not limited to a cutterhead hob mounting dimension parameter (hob mounting radius R) i Hob spacing S c ) Cutter ring profile dimension parameter (cutter ring outer diameter R) c Equal cutter ring outline dimension parameter, cutter ring cutting edge width B c Angle of blade theta c Radius r of arc transition c Parameters of the equal cutter ring blade shape section size), cutting parameters (cutter disc rotating speed n and cutting depth H), material components of the cutter ring and physical and mechanical property parameters (density, poisson ratio, elastic modulus, impact toughness, yield strength, hardness H and the like), and physical and mechanical property parameters of rock (density, poisson ratio, elastic modulus and tensile strength sigma) t Compressive Strength sigma c Shear strength);
s2: collecting rock powder samples in a compact nuclear area of an actual construction site or a cutting test site of a researched hob, and obtaining composition components and physical mechanical parameters (including particle size, water content, density and the like) of the rock powder samples;
s3: the dynamic characteristic parameters related to the friction and wear performance of the cutter ring during the rolling and breaking of the rock under the cutting depth h of the hob are obtained based on the basic information obtained in the step S1 by at least one of theoretical, simulation and test means, including but not limited to the stress level P of the dense core region of the edge bottom of the cutter ring field KnifeA circle peripheral line speed v;
s4: preparing a probe with the same material composition and physical and mechanical performance parameters as those of the cutter ring obtained in the step S1;
s5: filling the rock powder sample acquired in the step S2 into a containing cavity between a loading head and a cavity, and applying extrusion load to the rock powder sample by using the loading head to ensure that the stress level of the rock powder sample reaches the stress level P of a dense nuclear area at the edge bottom of the cutter ring field ;
S6: the probe vertically penetrates into the rock powder sample at a given positive pressure N, wherein N meets the following formula (3), so that the contact stress between the probe and the rock powder sample reaches the stress level P of the dense nuclear region at the bottom of the cutter ring blade field ;
N=A·P field (3)
Wherein A is the contact area between the probe and the rock powder sample;
preferably, the pattern of probes prepared in S4 includes, but is not limited to, one of the following patterns: the cylinder, the cylinder with the tip at the tail end, the cylinder with the frustum at the tail end and the cylinder with the transition ball head at the tail end;
s7: the probe is driven to horizontally and periodically slide and wipe the rock powder sample to a certain distance (marked as sliding distance L) at a sliding speed v 1 And the peripheral linear velocity v of the cutter ring is the same as that v, and L and v satisfy the following formula (3):
wherein t is the sliding time;
preferably, in S4, the probe is only required to have the same element composition as the cutter ring, and the average mass fraction of each constituent element composition of the probe is within the statistical range of the mass fraction of the corresponding element of the cutter ring; the average hardness of the probe is required to be within the statistical range of the hardness of the knife ring edge part;
preferably, a rock sample is collected from a cutter ring cutting site, and is ground into an approximate rock powder sample with the same physical and mechanical parameters as the rock powder sample collected in the step S2 by using a ball mill;
preferably, only the approximate rock dust sample is required to have the same average particle size as the rock dust sample collected in S2;
s8: recording and analyzing test phenomena and results;
preferably, S8 includes, but is not limited to, recording and analyzing the following:
1) The probe friction force f in S7 is measured, and the friction coefficient μ is calculated from the following formula:
f=μN (5)
2) Measurement of the Mass loss Δm of the Probe before and after S7 0 And calculating the mass loss rate v of the probe under the unit sliding distance according to the following formula m :
3) Measuring the microcosmic appearance of the tail end of the probe before and after the step S7, and analyzing the abrasion failure mechanism of the rock breaking cutter material-compact nuclear material;
4) Obtaining the sliding speed v by the following fitting 1 Law of influence on coefficient of friction μ:
wherein a, b, c and d are constants determined by the material composition of the probe and the contact load of the probe-rock powder sample;
preferably, S8 further includes analyzing the following items:
research on composition components of rock powder sample, physical and mechanical parameters of rock powder sample and stress level P of dense nuclear region of knife ring edge bottom field The circumferential line speed v of the cutter ring and the mass loss rate v of the positive pressure N to the probe m And the law of influence of the coefficient of friction mu;
more preferably, S8 further comprises analyzing the following items:
based on an Archard theoretical model, the abrasion coefficient K can be obtained by deduction from the following formula (8);
wherein H is the probe hardness.
Compared with the prior art, the application has the following advantages:
1) The method for testing the tool rock counter grinding can accurately measure the quality change of the probe and the compact core powder after counter grinding.
2) The method for testing the tool rock opposite grinding has higher similarity with the actual working condition of the hob under study.
Detailed Description
The application provides a rock breaking cutter material-compact core material counter grinding test method, which comprises the following steps as shown in figure 5:
s1: basic information related to friction and wear performance of a hob ring (hereinafter referred to as a hob ring) under study is obtained, including but not limited to a cutterhead hob mounting dimension parameter (hob mounting radius R) i Hob spacing S c ) Cutter ring profile dimension parameter (cutter ring outer diameter R) c Equal cutter ring outline dimension parameter, cutter ring cutting edge width B c Angle of blade theta c Radius r of arc transition c Parameters of the equal cutter ring blade shape section size), cutting parameters (cutter disc rotating speed n and cutting depth h), material components of the cutter ring and physical and mechanical property parameters (density, poisson ratio, elastic modulus, impact toughness, yield strength, hardness and the like), and physical and mechanical property parameters of rock (density, poisson ratio, elastic modulus and tensile strength sigma) t Compressive Strength sigma c Shear strength);
s2: collecting rock powder samples in a compact nuclear area of an actual construction site or a cutting test site of a researched hob, and obtaining composition components and physical mechanical parameters (including particle size, water content, density and the like) of the rock powder samples; for example, observing the particle size distribution of rock powder samples in a compact nuclear area by adopting a microscope, and calculating the average particle size;
s3: the dynamic characteristic parameters related to the friction and wear performance of the cutter ring during the rolling and breaking of the rock under the cutting depth h of the hob are obtained based on the basic information obtained in the step S1 by at least one of theoretical, simulation and test means, including but not limited to the stress level P of the dense core region of the edge bottom of the cutter ring field The circumferential linear velocity v of the cutter ring; more specifically, in this example, the bottom contact stress level P of the cutter ring edge during rock breaking by rolling and pressing of the hob can be obtained by adopting a simulation analysis means, such as transient nonlinear dynamics software simulation of ANSYS/LS-DYNA, abaqus and the like field Vertical cutting force F of knife ring v The peripheral line velocity v of the cutter ring can also be obtained by theoretical analysis means, for example, by calculating and obtaining P by referring to the pressure of the dense nuclear region after rock invasion of the blunt cutter shown in the following formula (1) field The method comprises the steps of carrying out a first treatment on the surface of the In the model, the compact nuclear area is assumed to be in a hydrostatic pressure state, namely the pressures in the compact nuclear area are equal;
s4: preparing a probe with the same material composition and physical and mechanical performance parameters as those of the cutter ring obtained in the step S1; in the example, a probe is prepared by adopting a cutter ring common material H13 steel;
s5: filling the rock powder sample acquired in the step S2 into a containing cavity between a loading head and a cavity, and applying extrusion load to the rock powder sample by using the loading head to ensure that the stress level of the rock powder sample reaches the stress level P of a dense nuclear area at the edge bottom of the cutter ring field For simulating the confining pressure of rock powder in the compacted core area, i.e. for simulating the compacted core material (i.e. the stress level P of the compacted core area with the knife ring edge bottom field Rock dust of (a); in this example, P field Applied according to the following formula (2):
wherein F is t Is the pretightening tension of a single bolt, A 1 Is the area of the loading head;
s6: the probe vertically penetrates into the rock powder sample at a given positive pressure N, wherein N meets the following formula (3), so that the contact stress between the probe and the rock powder sample reaches the stress level P of the dense nuclear region at the bottom of the cutter ring blade field The method comprises the steps of carrying out a first treatment on the surface of the In this way, the probe may remain stationary in a vertical direction relative to the surface of the rock dust sample;
N=A·P field (3)
in this example, n= (m+m) 0 ) g; a is the contact area between the probe and the rock powder sample; m and m 0 Respectively the weight mass and the probe mass;
more specifically, in this example, the step S6 is specifically performed using a rock breaking tool material-dense core material counter-grinding test apparatus. As shown in fig. 1 to 4, the rock breaking cutter material-compact nuclear material counter grinding test device comprises a base 1, an upper pressing die 2, a probe mounting sliding table 3, a probe 32 and a power transmission system, wherein:
a loading head 11 is vertically arranged at the upper center of the base 1;
the upper pressing die 2 is positioned right above the base 1; a cavity 21 is formed inwards at the center of the lower part of the upper pressing die 2; as shown in fig. 5, a slit 22 communicating with the cavity 21 is formed at the upper center position of the upper die 2; under the action of a given tensile force, the upper pressing die 2 vertically presses the base 1 downwards along the length direction of the loading head 11, and the probe mounting sliding table 3 moves freely in a reciprocating manner right above the upper pressing die 2 along the length direction of the slit 22; a probe through hole is formed in the top of the probe mounting sliding table 3; the lower end of the probe 32 sequentially and movably passes through the probe through hole and the slit 22, then contacts the rock powder, and applies a given positive pressure N to the rock powder below the probe;
the power transmission system drives the probe installation sliding table 3 to reciprocate relative to the upper pressing die 2, so that rock powder in a given confining pressure stress state is simulated to repeatedly grind and slide the hob edge base material according to a given positive pressure N;
preferably, the pattern of probes prepared in S4 includes, but is not limited to, one of the following patterns: as shown in fig. 7, the device is a cylinder, a cylinder with a tip at the tail end, a cylinder with a frustum at the tail end and a cylinder with a transition ball head at the tail end in sequence;
s7: the probe is driven to horizontally and periodically slide and wipe the rock powder sample to a certain distance (marked as sliding distance L) at a sliding speed v 1 And the peripheral linear velocity v of the cutter ring is the same as that v, and L and v satisfy the following formula (4):
wherein t is the sliding time;
preferably, in order to simplify the preparation flow and test calibration time of the probe, in S4, the probe is only required to have the same element components as the cutter ring, and the average mass fraction of each component element component of the probe is within the statistical range of the mass fraction of the corresponding element of the cutter ring, in consideration of the fluctuation of the material components and the physical mechanical properties of the cutter ring and the difference of the prepared probe; the average hardness of the probe is required to be within the statistical range of the hardness of the knife ring edge part; in this way, the rock powder sample adopted in the rock breaking cutter material-dense core material pair grinding test has the same composition and physical and mechanical properties as rock powder in the blade bottom dense core area when the hob rolls to break rock in the actual working condition;
preferably, considering that the amount of the rock powder sample collected in the step S2 is small and insufficient to meet the requirement of a large-batch test, collecting the rock sample from a cutter ring cutting site, and grinding the rock sample into an approximate rock powder sample with the same physical and mechanical parameters as the rock powder sample collected in the step S2 by using a ball mill;
preferably, in order to further simplify the preparation process flow of the approximate rock powder sample, and reduce the preparation cost, it is only required that the approximate rock powder sample has the same average particle size as the rock powder sample collected in S2;
s8: recording and analyzing test phenomena and results;
preferably, S8 includes, but is not limited to, recording and analyzing the following:
1) The probe friction force f in S7 is measured, and the friction coefficient μ is calculated from the following formula:
f=μN (5)
2) Measurement of the Mass loss Δm of the Probe before and after S7 0 And calculating the mass loss rate v of the probe under the unit sliding distance according to the following formula m :
3) And (7) measuring the microcosmic appearance of the tail end of the probe before and after the step S7, and analyzing the abrasion failure mechanism of the rock breaking cutter material-compact nuclear substance.
4) Obtaining the sliding speed v by the following fitting 1 Law of influence on coefficient of friction μ:
wherein a, b, c and d are constants determined by the material composition of the probe and the contact load of the probe-rock powder sample;
preferably, S8 further includes analyzing the following items:
research on composition components of rock powder sample, physical and mechanical parameters of rock powder sample and stress level P of dense nuclear region of knife ring edge bottom field The circumferential line speed v of the cutter ring and the mass loss rate v of the positive pressure N to the probe m And the law of influence of the coefficient of friction mu;
more preferably, S8 further comprises analyzing the following items:
based on an Archard theoretical model, the abrasion coefficient K can be obtained by deduction from the following formula (7) and is used for researching the influence rule between different sliding materials and different friction conditions in actual working conditions;
wherein H is the hardness of the probe, namely the cutter ring, and particularly the Brinell hardness value; the others are the same as above.
Compared with the prior art, the application has the following advantages:
1) The method for testing the tool rock counter grinding ensures that the change condition of the quality loss after the counter grinding of the probe and the compact nuclear powder can be accurately measured.
2) The method for testing the tool rock opposite grinding has higher similarity with the actual working condition of the hob to be researched; the concrete steps are as follows: the cutter ring material is similar to the physical and mechanical properties, and the physical and mechanical properties of the rock are similar to those of the rock.
In order that the above-recited objects, features and advantages of the present application will be more clearly understood, a more particular description of the application will be rendered by reference to the appended drawings and appended detailed description. The embodiments of the present application and the features in the embodiments may be combined with each other without collision. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application, and the described embodiments are merely some, rather than all, embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present application without making any inventive effort, are intended to fall within the scope of the present application.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
In the working principles provided by the present application, it should be understood that the disclosed components and structures may be implemented in other ways. It will be evident to those skilled in the art that the application is not limited to the details of the foregoing illustrative embodiments, and that the present application may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the application being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned. Furthermore, it is evident that the word "comprising" does not exclude other elements or steps, and that the singular does not exclude a plurality. The terms first, second, etc. are used to denote a name, but not any particular order.
The above embodiments are only for illustrating the technical solution of the present application and not for limiting the same, and although the present application has been described in detail with reference to the above preferred embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the technical solution of the present application.