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TBM choose to use the tool and maintenance management

TBM choose to use the tool and maintenance management

(Summary description)Development tool is a very broad concept , in the Stone Age people have tried to use knives , axes and service to humanity . In the modern people's daily lives , people are more widely available with a variety of tools, the machinery industry , wood industry , mining and other industries , the tool have been put to good use for the production development.

TBM choose to use the tool and maintenance management

(Summary description)Development tool is a very broad concept , in the Stone Age people have tried to use knives , axes and service to humanity . In the modern people's daily lives , people are more widely available with a variety of tools, the machinery industry , wood industry , mining and other industries , the tool have been put to good use for the production development.

Information

Development tool is a very broad concept , in the Stone Age people have tried to use knives , axes and service to humanity . In the modern people's daily lives , people are more widely available with a variety of tools, the machinery industry , wood industry , mining and other industries , the tool have been put to good use for the production development. Especially in our tunnel boring construction which , with the shield tunneling machine construction technology development , but also for the application and development tool brings a unique space for development, no matter what the ground conditions , construction, tunneling speed of , the level of construction costs are directly related to the appropriateness of the choice of the tool and its performance is good or bad has a great relationship and influence. Therefore , the world attach great importance to shield tunneling machine tool research and application , especially in the shield tunneling machine construction on a variety of rock excavation required tools , countries have done a lot of research work, the United States, Japan, Germany and some other industrial countries from the tool 's cutting mechanism , cutting theory calculations, rock breaking way , and other aspects of simulation for a long in-depth research, has achieved many achievements and experience , and constantly improve the application of and perfect for a variety of formations formed a shield tunneling machine tool series and varieties and specifications . Of shield tunneling machine tool for research and development began in the 1960s , after decades of hard work and development, but also made great progress and development , especially from the 1990s, the country 's economic development has entered a period of rapid development , the overall engineering technology has been greatly improved , the domestic underground space engineering, tunnel construction a substantial increase in domestic shield tunneling machine construction technology standards greatly improved, shield tunneling machine construction tasks a significant increase in shield tunneling machine has become the major powers on the shield tunneling machine tool increasing demand , boring machine tool research and development has made considerable progress , has developed a multi-species, multi-standard , multi- can meet the construction needs of a variety of formations shield tunneling machine tool , and some tool has reached the international advanced level of similar tools , domestic knives are gradually replace imported knives, ushered in a shield tunneling machine cutter era of great development . <2> shield tunneling machine tool working mechanism of 2,1 stratigraphic classification and characteristics we know TBM cutter ( hereinafter referred to as the tool ) is implemented TBM tunneling construction of key components , direct mining working face all ultimately have to rely on tunneling construction tool to complete, so the selection of the tool is applicable to the project and the tool itself excavation strata the quality is a key factor affecting the construction progress of the world. Construction of the project is changing ground conditions encountered , but regardless of how changes in the main geological composition is nothing more than two types of soil and rock formations or different combinations of two forms . The soil , the based on a variety sand, clay, clay , etc. or in the form presented in various combinations of them face , to their relatively low hardness , strength characteristics is weak , relatively easily broken , generally compressive strength 30MPa The following , with the scraping tool to complete the excavation construction category . The rock is concerned, is the rock strength in various solid shape, or in their different combinations presented in the face , and their high strength properties , ( often expressed uniaxial compressive strength ) Compressive strength Average in 30MPa or more, must be used with a rotary cutting tool or a combination of the hob and cutter complete excavation construction . Uniaxial compressive strength of common reference values are as follows: rock types compressive strength (MPa) compressive strength of rock types (MPa) dolerite quartz schist 69 196 ~ 343 ~ 178 177 ~ 294 gabbro mica schist from 59 to 127 diorite 177 ~ 294 ~ 167 basalt tuff 59 phyllite 147 ~ 294 49 ~ 196 147 ~ 294 quartzite gneiss granite 49 to 196 98 to 245 29 to 245 limestone rhyolite porphyry 98 ~ 245 ~ 196 sandstone 19.6 marble, marl, 98 ~ 245 12 ~ 98 98 ~ 196 slate shale, dolomite 9.8 ~ 98 4.9 ~ 78 ~ 245 49 thus coal in different formations of the tool applies tunneling construction is different, but all of the tools also revolves around how to cut all kinds of rock and soil for construction . Development tool , too, after years of research around the world and construction practice, the current TBM scraping tool is divided into classes and class Hobbing two classes: Class 2.2 scraping knives and cutting mechanism ( 1 ) Class scraping scraping tool features class relative sliding tool is generally used to cut through soft rock and soil , which consists of two blade cutter body and parts, generally used for soft soil and soft rock strata excavation , sometimes as an auxiliary tool mounted on the hob for later use. Blade cutter body for a supporting role , and the cutter body also play a role in connecting the cutter installed on the role , requires a certain degree of strength and stiffness. Blade part is usually in contact directly with the face cut from rock layer. As the saying goes good knife blade to see , in order to extend tool life , the blade part is usually taken to special treatment , often surfacing or spray tungsten carbide and other hard materials wear or mosaic ( by brazing or thermal loading ) carbide blade . To ensure that the blade of the knife sharp and wear resistance, cutting to meet the needs of soft rock and soil . Alloy blade shape and size more , depending on the installation requirements and stratigraphic cutter case may be , required to have a certain degree of wear resistance, impact resistance and toughness and weldability cutter body ( welding combined ) , the tool body need also be made in accordance with a variety of shapes and sizes , so a wide variety of scraping tool , currently used on the shield tunneling machine tool main categories scraper edge scraper, baker knife, cutter, cutter, knife first ( as shown shown ) , the cutting means and the cutting mechanism is the same , in order to facilitate the description , this known type scraping tool . ( 2 ) scraping mechanism like the cutting tool is a scraping tool is usually bolted or welded on the blade disc , the continuous rotation of the cutter and the cutter drive thrust cylinder , the scraping edge of the blade portion of the constant embedding ( cutting) tunnel face , and the soft soil layer tunnel face ( or hob broken muck ) through the front scraper blade facing up and to the sides continuously squeezed out of the tunnel face peeling cutting grooves , flaking of the muck rake face along both sides of the blade slipped into the slag bath , so that the cutting blade has both the function also has the function of loading . So scraping tool is a kind of cutting force and the extrusion pressure to crush the soft rock layer tool , suitable for surface soil and soft rock ( generally less than 40MPa) tunneling construction . Also often used in hard rock scraper the time, but this time the installation is lower than the disc cutter certain height, is mainly used to cut down the rock hob scraper slag, the protective effect against cutter on rock crushing mainly rely on the hob to complete, but in order to be hob crushed rock slag into the slag bath scrape promptly to prevent sediment build-up worn cutter , if only with a scraper blade will wear quickly . 2.3 slitting knives and cutting mechanism category ( a ) the characteristics of rotary cutting tools like slitting class rolling tool is the tool to cut through the rock , so people also often used to call hob . It is generally through the knife frame holder and bolted to the cutterhead , in the work process , it is not only driven by the cutter with the cutter revolves , but also rotates around its own axis knife through continuous continuous be cut on the rock rolling , extrusion and friction, so that the working face on the rock gradually falling off , the completion of rock cutting broken. It is composed of multiple components assembled after processing , not only requires high hardness, good wear resistance, but also requires good sealing performance, load capacity, mainly for rock crushing . According to the cutter body and the shape of the blade , hob can be divided into : Taper Hob ( divided wedge hob and ball hob ) , disc cutter ( divided steel ring hob cutter ring and ball hob ) . TBM cutterhead is now generally only install disc cutter , cutter on the basis of their different installation location , hob is divided into : Positive hob , central hob, hob other side . All types of hobs illustrated below . ( 2 ) rotary cutting tool cutting mechanism a ) tapered wedge hob cutting mechanism tapered wedge hob mainly broken rock crushing and shearing . In the tunneling process, with the cutter body is rotated , the teeth have been acting on the rock in the formation of alternating adjacent teeth and contacts, hob distance from center of gravity of the rock face change periodically , the hob to the potential energy of the rock surface , the periodical variation occurs , the impact on the rock to a shock and vibration effects , helps to speed up the rock broken. Cone wedge hob with a plurality of outer cone teeth , teeth generally integrally formed with the cutter body (cast gear teeth or welding ), according to different conditions tunneling , sharp teeth and the tooth height of the teeth should be accordingly. The softer formations tunneling principle , be more pointed teeth longer ; otherwise , should be used stubby tooth structure . Tool Body Material foreign multi- carbon steel, carburized purposes . Multi domestic carbon steel, quenching and tempering treatment , in order to improve the wear resistance of the teeth , the teeth of the wedge-shaped knife with tungsten carbide and other hard surfacing wear-resistant materials or direct welding on steel bonded carbide cutter . The use of wedge hob range generally used for excavation in soft rock to hard rock ( rock compressive strength less than 80MPa). Mostly in the knife disk layout uses . 2 ) conical ball gear hob cutting mechanism conical ball gear hob cutter is mounted on the surface of the conical cutter body carbide ball column ( shanks ) , this shank made by powder metallurgy , two main materials are tungsten carbide and cobalt , cobalt is a binder from the role of the control pressure into the shank and the physical properties ( wear and bending ) . Also added some other trace metals . The compressive strength of push shanks different formations according to the conditions of use about 2600-3100MPa, hardness is generally HRA80-90, one end tooth hemisphere majority, so often called ball gear , there are also other conical shape ( see Figure 2.2 ) . Because of these characteristics , the ball hob for drilling hard rock formations require drilling pressure value is much greater than the wedge hob . Ball hob is by crushing and grinding action of crushing rocks . Its basic structure and principles of cloth gear , hob body material were similar with wedge hob , different tooth and its main point is that the different materials . Shank pressed into the shape and the height of the projecting blade formation conditions can vary . 3 ) disc cutter cutting mechanism itself as the rolling disc cutter , the wear rate much slower than the blade . Combined with a narrow blade , in the same cutter thrust acting on the rock pressure is much larger , which can crush rocks much harder than the scraper , the majority of sedimentary rocks with only disc cutter can fully broken. Stage disc cutter is mainly used in shield tunneling machine cutter head on , so long , disc cutter and a shield tunneling machine tool almost become synonymous . Compact disc cutter (≤ 12 ") is usually the blade and the blade body made of one , usually multi-blade , and some blade inlaid carbide ; large size of the disc cutter ( usually 14 " -19 " ) blade and the blade is usually separate, removable so that the blade can be replaced after wear . it is customary also often referred to as the knife blade ring, ring replaceable knife blades can be circle, it can be in steel ring inlaid carbide which to choose based on stratigraphy , inlaid carbide knife ring ( also often referred to as the ball cutter ring ) is more suitable for special hard rock excavation construction . disc cutter cutting principle is that when cutter tremendous thrust in the longitudinal cylinder under the action of the cutter mounted on a disc cutter pressed into the rock ; while the cutter is driven in rotation means rolling torque applied to the driven hob hob cutter around the central axis of revolution in hob revolution same time, because the working face on the hob Mocha force , so that the hob is also about respective spindle rotation , so that makes the surface of the hob in a continuous rolling rock . applied to the cutter knife thrust ring and rolling moment results are: thrust pushed the knife ring hob rock , roll torque to the hob cutter ring rolling ( cut ) rock through the rock knife ring hob continuous extrusion and cut, making installation in different pockets of the rolling surface of the hob in the rock cut out a series of concentric circular grooves . ( see figure below ) hob rolling rock crushing effect varies with the thrust of rock crushing generally divided into three stages: grinding, crushing and effective volume of the crushing fatigue . grind: when the hob being thrust is very small, the rock knife ring extrusion pressure is far less than the ultimate strength of rock , rock crusher is the friction force of the surface caused by wear and tear. crushed particles is small, knife ring wear serious, slow rock crushing . fatigue broken : When the hob been thrust increases, but the knife ring extrusion pressure is still on the rock less than the ultimate strength of rock , the rock through multiple knife ring rolling , the rock will be distributed along the rolling direction of a certain stress , rock experience fatigue cracks along the line of pressure , and thus were fractured . effective volume broken: when the hob being thrust large enough for rock cutter ring squeeze pressure is greater than the ultimate strength of rock , the blade penetrating the rock formations to produce stress , forcing the rock cracks generated by leaps and direct crushing , crushing blocks increases, crushing speed , and with the cutter axis pressure increased linearly ( but subject to other conditions, axial compression can not grow indefinitely ) . rock surface is extruded disc cutter to form a multi-channel concentric rupture circular grooves. with groove depth increases, the rock surface cracks deepen expanding concentric grooves between adjacent rock caving into pieces . complete disc cutter rock breaking process of the rock breaking speed Kuaidao conditions ring wear, rock crushing process can also consume smaller than the actual excavation process, the cutter rock breaking effects and thrust , pitch circle cutter knife , knife blade ring shape , rock properties and other relevant, difficult to fully achieve optimum crushing volume , often various stages of addition , the tunneling process, the disc cutter movement of the cutter disc cutter around the center of the disc in addition to the tangential peripheral revolution , rotation and along the direction of tunneling hob cut deep squeezing motion , there is along the radial sliding movement of the cutter , and at the same speed the greater the smaller the radius of the slip , under normal circumstances, so hob most worn close to the site of the hob cutter center inside knife ring hob by rock sliding direction of the force along the axial direction of the cutter radius deviation Second, the shield tunneling machine tool used for different strata excavation construction , different types of tools should be used in determining the tunneling tool forms must be preceded by the formation of the construction and survey sampling and testing, to develop a detailed geological report , generally are based on combinations of strata formation conditions occur , Herrenknecht commonly used tool installation diagram is also the case with a single layer , and then the distribution characteristics of strata select the tool and rock compressive strength . < 1> select the tool should follow the general principles of sexual selection 1,1 based on economic tool ( 1 ) driving speed , high efficiency ; ( 2 ) Unit footage tool consumption costs less ; ( 3 ) do may be required to adapt to a variety of stratigraphic excavation ; few species , low-cost spare parts : ( 4 ) excavation Unit footage power consumption, integrated low cost ; 1,2 according to the formation select tool for soft soil conditions are better in terms of choice , as long as good wear resistance, good slag scraper tool will be able to meet the general needs ; for rock formations , rock mainly consider the following characteristics ( 1 ) rock uniaxial compressive strength of the rock is a key factor affecting the efficiency of tunneling general tunneling shield machine best suited for the 40-150MPa compressive strength of rock . cutter depends in part on the cost of rock strength . now calculate the tool most commonly used standard cost of the compressive strength of the rock in the soft rock , the compressive strength is a more reliable measure , but in the hard rock , the rock compressive strength and the actual resistance can be broken is often not proportional strength is due to some moderate elastic or ductile rock . in the excavation process, the resistance is greater than its compressive strength of rock excavation indicated resistance. elastic performance of the rock toughness, when the tool is pressed in , the rock crumbled rock deformation without residue in such rock excavation , the difficulty Although large extent greater than the compressive strength but brittle and fragile rock. around the world are studying , looking for ways to represent the rock can be broken a reliable indicator of sex , but the strata are often complex , tool selection must consider its complexity. ( 2 ) the rock abrasion tool selection must also consider the second factor is the rock abrasion resistance of rock hardness and wear resistance is higher, tool consumption and higher construction costs , increase the number of tool changes cause downtime affect the driving speed , the relative does not wear high compressive strength even in rocks , using the disc cutter or wedge hob often with good results , whereas large in wear resistance , compressive strength of the rock is often small use hard alloy ball hob to avoid downtime caused by frequent tool . ( 3 ) the degree of development of rock structural plane of rock structural plane ie the degree of development and degree of rock fracture tunneling efficiency have a great relationship . compressive strength, hardness, wear the same or similar rock , if the degree of development of different structural surface , TBM tunneling speed differences are significant due to a variety of tools , the structure, mechanism and breaking rock breaking rock geology different parts , each one kind of tool can only adapt to a certain stratigraphic excavation table 3.1 is recommended by the United States Reid use of several tools . ( 4 ) composite stratigraphic tool selection for complex formation conditions inconsistent formations such as sand gravel strata, soil layers , clay layers and layers of rock formations such as layered distribution , construction and selection tool is a certain difficulty , then we must consider various geological characteristics , it is necessary to be able to use some suitable soil , clay layer tunneling scraper, also used part of the rock layers can deal with hob and staggered tool can compensate for each other , give full play to its rightful potential in tool manufacturing , they should also take appropriate measures , such as the manufacture of the blade fully consider its resistance grindability , the tool should be beneficial to both the structural form scraping , but also could help clean up rock hob scraper slag and clay groups ; manufacture of hobs , they need to consider the needs of broken rock , with enough strength and hardness, but also consider the sand gravel wear and tear on the hob , in the outer surface of knives and knife seat surfacing wear- resistant material , or other measures to prevent premature wear failure , but also do not control hob starting torque too large to avoid hob sandy gravel layer and through the soil can not spin , producing grinding chord failure of <2> tool design and manufacture of the structural characteristics and scraping tools and rotary cutting tool is a shield tunneling machine of the two most commonly used class cutter , respectively, are briefly its structural features and design manufacturing processes. 2,1 scraper structural characteristics and performance of the main properties of the design and manufacture scraper is scraping the softer layer of sand and rock soil residue, its structure and shape can be designed according to ground conditions a wide range , but they are the knife , knife body and the edge of three parts , the knife block is part of the connection with the cutter , the cutter is connected with the welding tool such as first , as there are bolted edge scraper and articulated as positive cutter, replacement parts hob cutter or cutter is installed in the same way with the hob . knife block some system into one with the knife , some with the cutter body welded with the welding tool body knife materials are generally low carbon steel . blade body from cemented carbide blade support and protection , to have sufficient strength and wear resistance , is usually used carbon steel, alloy steel or air quenching , the hardness of HRC40 or more , often using surface hardening technology or partial surfacing wear layer ; scraping blade is a blade scraping soil and protect the cutter body is not being worn, key parts , usually made of cemented carbide , and its hardness is generally HRA83-88 between the cemented carbide grades and sizes and shapes depending on the installation position , expected, and formation of the design. blade and the cutter body is a critical connection , the specific processes are brazing, welding set and set the connection strength requirements greater than 250MPa2, 2 hob structural characteristics and performance of design and manufacturing ( 1 ) disc cutter performance structural characteristics we know the main properties of disc cutter is used for breaking rocks , must have good rolling rock breaking and shear cut features, and rock formations to adapt to a variety of conditions . disc cutter knife rings are wearing parts , because of its large consumption , the price is more expensive, should be able to be replaced at the job site to improve its value in use , the knife cross-sectional geometry of the circle under the rock conditions change can have a variety of options . hob internal parts of the cutter ring is equally important to its excellent performance bearings and shaft seal parts and reliable performance , lubrication, can increase the carrying capacity of the hob and prolong life. knife block structure to facilitate better hob cutter on the installation and removal , safety and reliability , all of which are designed should be taken into account . disc cutter has a size variety series, now commonly used in general 17 "series hobs, now with 17" disc cutter for example the performance characteristics of its structure and design of the manufacturing process are described below: 1 ) 17 " disc cutter performance indicators: hob diameter 17" (432mm) roll knife carrying capacity of 30 tons / adapt the hob hob formation conditions 30-200MPa starting torque 30-70N.m2) 17 " disc cutter Features: hob divided into positive hob , side hob, central hob and so on. According to the geological conditions are different, there are single-pole and multi- ring hob cutter ring hob . Its internal structure as shown above. They are mainly from the knife ring , blade , knife shaft , tapered roller bearings , metal floating seal ring , knife cover ( seat ) and coupling bolts and other pieces of composition . Regardless of their size and specifications currently installed different parts , the internal structure of disc cutter are used back to back installation of tapered roller bearing assembly , oil bath lubrication, metal floating seal ring seal forms . Different ways depending on the installation , hob cutter spindle shaft cover and different forms . According to the different types of formations and knives , knife ring thickness ranging from 57.2mm-80mm , knife ring bore size of the companies there are differences, there are also different knife blade circle shape . ( 2 ) disc cutter design and manufacture of major components to meet the hob installed properly, choose a suitable ground conditions, affect the service life of the four key hob cutter ring , blade , bearings and seals manufacturing quality and assembly quality . Now these types of parts manufacturing and assembly processes are described below: a ) the manufacture knife ring hob hob cutter ring is affecting the life of the key , because of the poor quality of its manufacturing premature wear , fracture and reduce entire blade life . Cutter diameter circle at home and abroad using the popular 17-inch (432mm) size. The cross-sectional shape of the knife ring rock breaking a greater impact on the current ring knife blade contour line has become streamlined , usually ring knife edge radius R = 3-4mm. Hob knife ring material has two categories: the overall alloy rims and carbide teeth knife ring . ( See figure below ) overall steel knife ring material is mainly dominated by hot die steel , hardness is generally between HRC54-58 , which can be characterized withstand greater impact loads , and has good wear resistance, tool manufacturing costs are relatively low, the conditions applicable to hard rock rock breaking to do business . Alloy ball cutter knife ring alloy ring is mounted on the substrate column tooth carbide , carbide stelidium spherical head , carbide hardness HRA85-88. Under normal circumstances, the hard rock compressive strength over 150Mpa ball cutter ring used for construction , can solve knife ring hardness ( mainly alloy ball tooth hardness ) and toughness ( knife ring matrix toughness ) of contradiction because alloy steel rings to improve wear resistance , while increasing its hardness increases brittleness, lower toughness and reduce its strength , easy to make knife ring crack, ball cutter ring can solve this problem , its life is steel ring 2-5 times , more suitable for mounting on the side hob and overbreak knife cutter location requiring high wear resistance , but higher manufacturing costs. According to the working conditions of knife ring , knife ring material shall meet the following properties : a) high yield strength , reducing the blade end crushed under high stress deformation ; b) a good impact toughness , crack propagation energy to improve the material , to prevent the knife ring fracture ; c) a sufficiently high hardness , wear resistance increases , reducing knife ring wear ; d) good resistance to tempering performance, improved thermal stability, ensure the knife ring and rolling in the thermal loading process does not reduce the hardness of the rock . e) good thermal processing and cold process performance, low material cost , ease of manufacture , improve product yield. 2 ) hob sealing characteristics and manufacturing : Sealed bearing lubricant can be saved and to prevent foreign objects entering , to ensure normal operation and long bearing service life is very important . Metal floating seal ring belonging to a mechanical seal is ideal for complex formation hob job working conditions ( poor environment , and there is some external media pressure , which has a low speed and heavy load and shock resistance characteristics) have some bearing capacity and good sealing performance and longer life. This sealing engagement by two hardened alloy steel or high chromium cast iron sealing ring and two flexible rubber ring composed of toric . Toric ring with rubber seal ring to adjust the position , because it has the ability to float , can compensate for assembling face clearance or prevent deflection . Toric seals the metal seal ring face constant pressure. When space is limited and the use of short- hob , can be improved floating seal . ( This time with a toric rubber ring , a metal seal ring , a hob parts finishing off face ) . Metal seal rings are main parts of the seal , their structure and their quality play a decisive role . Metal seal ring with high hardness wear-resistant , high chromium molybdenum cast iron , hardness HRC60-65, work surface roughness Ra ≤ 0.1um, surface flatness ≤ 0.0015mm. This metal seal ring features the following : a) oil derivative with 3.5 degree incline and a small radius of curvature of the spherical ring and flat ring structure is conducive to the formation of oil film bearing oil to ensure no leakage and prevent dirt from entering the bearing cavity ; b) using high-quality finish and high hardness face , making a good fit , reduce friction and improve sealing performance ; c) thickening of the sealing ring size and improved structural strength ; d) floating seal ring with the 0 -rings , are the conditions required by the tool , the development of special rubber parts (P118 and P229 rubber ) , with favorable results ; with ordinary rubber , compared with a large compressibility and elasticity is good. Even if the impact of the outside rock , to metal seal ring has always put pressure on the metal ring face is always in contact , to ensure the bearing lubricating oil does not leak and prevent dirt from entering the bearing cavity , play a sealing effect. 3 ) bearing structural properties hob hob bearing most of the United States Timken tapered roller bearings produced as a hob bearings, these bearings use carburizing steel , the surface with high hardness , the core has a very high strength and toughness, these bearings are required to have the following advantages : a) be able to support radial load and axial thrust ; b) on the same bearing size , the relatively longer life ; c) for the same carrying capacity , the smaller size . d) adjusting performance: either axial clearance or preload , can be transferred according to the design requirements for optimal performance ; e) its conical structure inherent characteristics of the automatic shift oil , from the raceway contact area to exclude any particulate contaminants , greatly reducing the impact of environmental pollutants by work ; f) and other types of roller bearings , because of its relatively pure rolling effect , reducing the coefficient of friction , wear, slow, long life ; g) due to its internal and external raceway separable, installation and removal is very simple ; another bearing load changes on bearing life is very much affected , for example, a bearing 18,144 kg of pressure, speed of 120 rev / min , according to theoretical calculations bearing design life is 564 hours, and when the load is decreased by 50 %, the bearing life may be extended to 5684 hours , up to ten times or more. 4 ) blade , knife blade cover is manufactured mainly by the capacity hob parts , which supports cutting knife ring for rock breaking , while protecting the hob internal bearings and seals for normal operation , it is necessary to has sufficient strength to withstand the working face from the cutter and the pressing force , but also to deal with a higher wear resistance of the rock cutter ring broken down slag wear ; blade protection cap is floating seal support member , while pressed bearing play the role of regulator hob starting torque , the two materials generally used material 42CrMo forging and heat treatment after two to make hardness HRC40-45, for some sand pebbles complex formation , in order to improve the resistance of the cutter body grindability , still in the cutter body surfacing wear-resistant materials such as tungsten carbide , to ensure that it meets specific strata wear needs. 5 ) the assembly of hob hob hob assembly part is to ensure that the overall performance of one of the key processes , to ensure that all the amount of interference with the size of the design requirements , ensure that the bearing preload adjustment , and carefully examine the existence of the seal scratches and other defects , sealed pressure test inspection , add a little oil , and adjust according to ground conditions hob starting torque . Hard rock to be larger when the starting torque , soft rock when starting torque to be smaller, in order to prevent the hob does not appear chord instead grinding , resulting in premature failure of the hob . Hob torque between general 30N.m --- 70N.m . 6 ) lubrication requirements because the metal floating seal ring need to meet in order to oil bath lubrication, so the use of tapered roller bearing manufacturer recommended vehicle gear oil (GL-5), it has the following characteristics: a) good abrasion resistance . In the solid film formed on the surface to be lubricated to prevent the bearing and floating seal ring of high pressure area surface scratches and gluing . b) good oxidation stability, in order to adapt to long-term use in harsh conditions , but easily oxidized decay . c) Good anti-foam , the operating conditions to ensure vigorous stirring less foam generated in the process , and easy to destroy . d) good rust resistance, to ensure that the surface to be lubricated no corrosion and rust . In addition, lubrication and exhaust full of good , but also conducive hob use . Three , tool use, maintenance and management of < 1> reasonable cloth cutter different engineering geological conditions should be different structural forms and fabric cutter knife method and tool combination type. Cloth cutter is reasonable will directly affect the construction effect , driving speed , and project benefits. In the design of the tool cutter layout should consider the following aspects: ( 1 ) technical characteristics of cloth cutter according to the construction in order to ensure safe and reliable operation of construction , we should first consider the following a ) the cutter force balance , small vibration , smooth operation ; 2 ) tool covering the entire section 3 ) shall not cause roadway deflection ; 4 ) easy to exclude muck ; 5 ) ease of assembly and disassembly and inspection repairs. ( 2 ) work is characterized by the district cloth cutter knife : According to the nature of the cutter on three different regions ( center , front areas and marginal zone ) of the operating characteristics , cloth knife must fully consider the distribution characteristics. 1 ) the central area of the district is characterized cutter center position is characterized by small , hob small turning radius curvature , so the hob to reverse swipe -based, hob radial forces and axial forces are relatively large, often mounted on a single disc knife center pivot center of the knife blade to reduce sliding wear . The center of the cutterhead knife cutterhead thrust bear larger , commonly with the specifications of double-edged disc cutter , internally mounted four bearings to meet the needs of its force . Center hob hob with being the main difference is : Installation in different ways : a single disk-shaped cutter is mounted on the cutterhead , the knife is fixed at cutterhead ; disc is generally installed in the center of the hob cutter rack installed in groups , relying on both ends of the axial compression and wedge bolt connection, the assembly dimensional accuracy requirements are higher . Structure in different forms : disc central hob by space constraints in the design ( hard rock is not too wide blade pitch ) , but also to withstand greater pressure , often made of double-edged general hob, fitted four bearings to meet by force requirements. Some seals different forms : some centers hob cutter body to stay in place no separate floating seal ring position , then both ends of the cutter body must be directly made in the sealing tape , and placed at both ends of the metal blade cover floating seal ring pair to achieve seal. For example, the distribution of the center knife TBM880E is this structure. 2 ) characteristics of the area in the front area and the edge of the area between the central area , facing the tunnel face when working tool , there are certain turning radius , most of the hob is pure rolling work -based, there is sufficient space layout , so the district cloth cutter easy, general often furnished with hob and scraper , tool life and long. In hard rock tunneling , the front area should try to make the cloth cutter tool wear evenly as possible, hob pure rolling , then either knife ring bearing life or life will be very high. 3 ) characteristics of the area is located in the edge region of the edge of the cutter , the tool will not only undertake large rock breaking , and the tool force complex , the rotation speed is higher, but also to ensure excavation diameter , so the knife is a knife edge zone cloth dish cloth cutter key , more often than cloth cutter , some companies also on the knife blade circle shape and special design and made into special edge cutter or edge scraper to meet the construction needs. ( 3 ) cloth cutter spacing and number 1 ) cloth cutter spacing in a given geological conditions , knife and tool spacing on the working face of the thrust -related , knives thrust greater depth of cut of the tool relative to the greater , the hard rock case, knife cutter spacing is about 10-20 times the depth of cut , generally knife pitch 60-100mm, close to the cutter center spacing greater, in close proximity to the edge cutter knife spacing smaller. Tests showed that when reducing knife spacing to obtain a certain desired tool thrust driving speed will drop . This means that in the case of very hard rock , every knife thrust to maintain constant spacing by reducing the knife , driving speed can be increased , but the corresponding requirements increase overall thrust boring machines , and produce smaller gravel residue. The smaller the slag gravel , rock cutting energy consumption greater than required , the more economical excavation process is poor. Therefore, in cloth cutter knife spacing design , think the relationship between geological characteristics and efficiency . Thank you !

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Key words: hield tool  Engineering tool  Wear-resistant heart

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