CNC Floor Type Boring Machine Supplier | Deep Hole Accuracy, Heavy Table Load, Large Scale Castings

CNC floor boring machine suppliers usually provide boring accuracy ≤0.01mm, spindle diameter 130–200mm, worktable load-bearing can reach 20–80 tons, suitable for large casting processing.

Need first calibrate reference plane, adopt low-speed rough boring + high-speed fine boring step-by-step complete, and real-time monitor tool wear to guarantee deep hole processing stability.

Deep Hole Accuracy

Ram Sagging Compensation

To put a heavy reaching 15 tons to 25 tons cast iron square ram, from machine column inside transversely extend out 2.5 meters, is just like in mid-air flatly lifting a huge rigid lever.

When ram extend out length reaches 2000mm, front end's natural displacement deviation usually is between 0.08mm to 0.12mm. For pursuing 0.01mm level accuracy deep hole processing tasks, this kind of naked eye hard to see bending will directly cause hole position to deviate from axis.

In order to solve this physical difficult problem, engineers at ram inside embedded made of 42CrMo alloy steel tensioning pull rods.

· Pull rod diameter usually set at 32mm to 40mm.

· Installation time's prestress torque precise to 150Nm.

· Inside configured repeated positioning accuracy at 0.002mm hydraulic fine-tuning module.

· Entire system at ram moving time, can produce a reverse upward pulling force.

Entire set mechanism's action is controlled by proportional servo valve, its frequency response speed high reaches 50Hz. Ram every outward moves 1mm, inside's pulling force all will according to preset data model conduct microsecond level adjustment, ensuring spindle front end always situates at horizontal state.

Compensation action's precision relies on extremely low pressure hydraulic station support, its pressure fluctuation is limited within 0.05MPa.

· Sensor every 50mm position grabs one time stroke coordinate.

· Compensation curve contains exceeding 60 independent data feedback points.

· Z-axis's linear scale accuracy usually maintains at plus minus 3 microns.

· Data through 16-bit high-precision conversion module directly writes into PLC.

A standard milling head weight approximately is 350kg, while heavy right-angle milling head may heavy reach 1200kg. When these giant objects hang at ram front end time, system will automatically identify and switch corresponding pressure parameters, taking whole machine vertical axis's motion deviation controlled within 0.01mm/1000mm.

In actual operation, this kind of compensation is at background silently completed, operator on CNC screen seen Y-axis coordinate may have no change. But actually, machine tool already according to ram extend out real-time data, at vertical direction superimposed a extremely small correction numerical value. This kind of software and machinery's cooperation, lets 2-meter deep boring hole can maintain extremely high straightness.

In order to verify compensation effect, before factory leaving must use Renishaw XL-80 laser interferometer conduct full stroke testing.

· Measurement environment temperature needs strict control at 20 degrees Celsius.

· Environment temperature difference every fluctuates 0.5 degrees Celsius all will be counted into correction parameters.

· Testing covers no-load, half-load and full-load three kinds of modes.

· ly formed compensation curve will be permanently locked in machine tool's memory.

Ram's guideway surface usually adopts hydrostatic oil film technology, oil film thickness stabilizes at 0.02mm to 0.04mm. This layer thin oil film not only played lubrication role, more like is a heavy damping pad. When 20000 Newtons cutting resistance acts on long reaching 2 meters tool bar time, oil film's damping characteristic can effectively absorb 70% above's vibration, preventing deep hole inside appearing naked eye visible chatter marks.

Machine tool foundation and main body's stability also is guaranteeing this kind of accuracy compensation long-term effective cornerstone.

· Select HT300 gray cast iron, carbon equivalent controlled at 3.6% to 3.9%.

· Casting undergoes 550 degrees Celsius's high temperature artificial aging treatment, time length not lower than 8 hours.

· Secondary aging can eliminate 90% above's internal stress, preventing machine tool using several years later due to casting deformation leading to compensation failure.

· This kind of treatment ensured machine tool at bearing exceeding 50 tons' heavy load worktable load time, base remains stable.

At processing large generator rotor or ship shaft system hole time, even if 0.05mm's axis deviation, all will cause subsequent bearing installation difficulty. Once forcibly assembled, bearing at every minute several hundred revolutions' high-speed running inside will generate abnormal heat, finally substantially reducing equipment's service life.

processing quality directly reflects on data, adopting this compensation technology's machine tool, at 1500mm depth inside's cylindricity deviation can be controlled within 0.012mm.

· Bored out hole surface roughness can reach Ra 1.6.

· Roundness error is compressed at 0.008mm's extremely small range inside.

· Part pairing time's contact area can reach 85% above.

· Full stroke positioning accuracy maintains at 0.015mm per meter.

Thermal Stability Control

Spindle at every minute 3000 revolutions to 6000 revolutions high-speed running under, bearing friction generated heat will at two hours inside let spindle box temperature rise 15 degrees Celsius above. For length being 500mm spindle, every raise 1 degree Celsius, metal expansion will cause axial elongation approximately 6 microns. If at continuous 8 hours deep hole boring inside temperature difference reaches 5 degrees Celsius, tool tip position will produce 0.03mm's displacement, this will cause high-precision aero engine casing part size out of tolerance.

This kind of due to temperature fluctuation caused geometric deformation, usually relies on spindle box inside's constant temperature oil circulation system to conduct suppression. Cooling unit's cooling power usually configured at 5000W to 8000W between, circulation oil flow rate maintains at every minute 20 liters to 35 liters. Oil liquid's temperature fluctuation deviation is locked at plus minus 0.1 degrees Celsius range inside.

Cooling system not only acts on spindle, also will through circulation pump take temperature control oil liquid injected into column and bed body's rib plate cavity. HT300 cast iron's linear expansion coefficient approximately is 0.000011 per degree Celsius. For height being 6 meters' column, every raise 1 degree just will elongate 0.066mm. Large capacity cooling unit takes machine tool main body structure and environment temperature's temperature difference limited within 2 degrees Celsius, taking whole machine's thermal deformation controlled at 0.01mm magnitude.

Drive motor installed at column central axis line on, not adopt single side hanging. Double lead screw symmetrical drive method balanced thermal stress, preventing column toward heated side tilting. Spindle box adopts center symmetrical layout, letting heat toward surroundings evenly diffuse. This kind of design takes heat-induced tilt error from traditional 0.04mm reduced to 0.005mm below.

Physical cooling unable to solve all instantaneous temperature rises, at this time needs to rely on deployed at machine tool everywhere PT100 high-precision thermistor sensors.

When spindle front end sensor detects temperature rise exceeds threshold time, control system will automatically at Z-axis coordinate command inside superimpose a reverse micron-level correction amount. This kind of compensation by every 10 milliseconds one time frequency conducts smooth patching, operator observes not to coordinate jumping, but processing trajectory already completed thermal elongation offset.

· Sensor buried at distance bearing outer ring 3mm position.

· Every one second acquires 10 times temperature signals.

· Data through isolated shielded cable transmits to control module.

· Temperature difference exceeds 0.1 degrees Celsius time, cooling unit's frequency converter will raise pump speed.

· Compensation algorithm covered spindle from stationary to highest rotation speed's all temperature rise curves.

Lead screw inside adopts center hole through oil cooling technology, oil liquid pressure maintains at 0.3MPa. Lead screw two ends adopt pre-stretching installation process, pre-stretching force usually is at 3000N to 5000N between. Pre-stretching amount according to material at 3 degrees Celsius temperature rise under's expansion amount conducts calculation, usually set as 0.02mm to 0.03mm.

Due to heavy machine tool's casting volume large, thermal inertia extremely strong, this kind of based on relative temperature difference algorithm can prevent due to season alternation or day-night temperature difference caused size drift. Spindle box outside wrapped with a layer high-performance thermal insulation composite material, thickness at 10mm to 20mm between, blocking external airflow to key components' local interference.

24 hours continuous processing process inside, temperature rise caused center height change smaller than 0.01mm. Spindle rotation axis line's spatial position variation amount controlled within 0.008mm. This kind of stability allows machine tool at cold machine start after's 30 minutes inside reach processing state. Compared to no temperature control equipment, it shortened approximately 2 hours preheating wait time, lifted machine tool's effective cutting time length.

· 200L to 400L large capacity cooling oil tank.

· R410A environmental protection refrigerant's constant temperature unit.

· Spindle bearing running temperature highest point not higher than 45 degrees Celsius.

· Heat exchanger adopts high efficiency plate type structure.

· Cooling circuit equipped with 0.005mm accuracy precision filter.

data feedback shows, undergone deep thermal stability control equipment, its processing repeated positioning accuracy stabilizes at 0.003mm. Diameter 500mm deep hole at different time periods processed size deviation smaller than 0.005mm. Bearing housing hole's coaxiality at full length range inside lifted 40%. Tool durability due to reduced thermal vibration interference and lifted 15% above. Machine tool at continuous running 1000 hours after, geometric tolerance's maintainability still situates at factory leaving state.

Structural Rigidity

When a diameter 160 millimeters, long reaching 2 meters boring bar extends into metal cylinder inside cutting, tool tip every minute cuts down 300 cubic centimeters steel chips. Long overhang state lets tool bar like a plucked piano string, producing 50 Hertz to 200 Hertz violent vibration. Ordinary bed body cannot bear shaking will produce resonance, letting tool tip on deep hole wall leave deep reaching 0.05 millimeters wave shape chatter marks.

A stroke being 10 meters floor type milling and boring machine, base and column's casting total weight exceeds 80 tons. Huge mass acts as natural energy absorber, when 20000 Newtons cutting force along ram transmits to column time, chassis steadily presses down ground completely still.

Big factories universally adopt HT300 high-strength gray cast iron, or Meehanite inoculated cast iron. Metal liquid at smelting furnace inside adds silicon, manganese, chromium alloy elements, carbon equivalent strictly controlled at 3.6% to 3.9% interval.

Flake graphite structure's cast iron possesses far exceeding steel material 10 times damping attenuation coefficient. Metal receives mechanical shock wave impact time, internal microscopic graphite layers between occurs tiny dislocation friction, taking vibration transformed into heat energy dissipate, taking destroying accuracy's chatter marks strangled at sprout stage.

Just out of furnace giant casting like tightly stretched spring, inside remains 150 MPa's casting stress. Unprocessed sent onto machine tool processing, parked half a year later bed body also will self bend deform exceeding 2 millimeters. All large pieces demolding after will be immediately sent into heavy annealing furnace.

· Furnace temperature at every hour 50 degrees Celsius speed slowly rises to 550 degrees Celsius.

· At highest temperature state under continuous heat preservation 10 to 12 hours.

· Cooling process controlled at every hour 20 degrees Celsius, until lower than 150 degrees Celsius out of furnace.

· Two times artificial aging treatment takes internal residual stress eliminated 90% above.

Cut open machine tool column's cross section, inside densely distributed thickness at 30 millimeters to 50 millimeters between's reinforcing ribs. Common internal layout is honeycomb shape or W-type diagonal cross rib plates, lifted structure's 40% anti-bending rigidity.

Facing height reaching 6 meters giant column, two Z-axis guideways' center distance designed at 1200 millimeters to 1500 millimeters between. Ultra-wide span chassis gave column installed wide soles, bearing 15 tons ram extending out produced huge overturning moment.

Guideway slider and bed body between equipped closed hydrostatic guideway system, oil pump continuously presses into high-pressure anti-wear hydraulic oil. Oil liquid pressure maintains at 2.5 MPa to 3.0 MPa, taking heavy reaching dozens of tons metal structure forcefully held up.

· Guideway surface on forms thickness uniform 0.02 millimeters to 0.04 millimeters oil film.

· Metal components between completely detach contact, friction coefficient reduces to 0.005 below.

· Extremely low friction resistance lets heavy slide table's moving like on ice surface sliding same smooth.

· Feed system's minimum setting unit accurately responds to 0.001 millimeters displacement command.

Liquid unable to be compressed, oil film receives cutting impact time produces tiny squeezing flow. High-frequency vibration wave penetrates this layer merely 0.03 millimeters thick oil liquid layer time, amplitude will be reduced 75% around.

A 10-meter long bed body two sides, densely distributed at least 40 M36 level high-strength adjusting wedge irons. Each wedge iron's load capacity reaches 10 tons above, installation personnel uses electronic level taking support point's height error leveled to per meter 0.01 millimeters inside.

Heavy reaching hundred tons equipment base and below deep reaching 3 meters reinforced concrete independent foundation thoroughly merged into one body. Foundation inside poured label being C40 concrete, isolated workshop inside crane lifting or punch press work transmitted external surface vibration waves.

Drill bit deeply enters steel part inside 1500 millimeters time, spindle motor power output meter shows load reaches 80%, machine outer shell on almost touch not vibration feeling. Processed out hole wall surface like mirror surface, roughness value stays at Ra 0.8 microns.

Heavy Table Load

Material & Structure

Floor type milling and boring machine's load-bearing foundation starts at high-strength HT300 gray cast iron material. This kind of material's carbon content stabilizes at 2.9% to 3.2%, silicon content controlled at 1.5% to 1.8% between. Through adding 0.8% manganese element, casting inside's pearlite content can exceed 90%, forming extremely dense organizational structure.

In order to guarantee material not brittle crack, sulfur and phosphorus content must be compressed to 0.1% below. Laboratory data shows its tensile strength exceeds 300MPa, Brinell hardness at 190HBW to 230HBW fluctuates. This kind of hardness level lets worktable at facing 50 tons above's heavy pressure time, surface will not easily produce indentation or deformation.

Blank casting at cleaning after directly enters heat treatment furnace, raise temperature to 550 degrees Celsius conduct stress relief annealing. Cooling process very slow, every hour drop amplitude must not exceed 20 degrees Celsius, to prevent due to uneven cooling produced secondary internal stress.

Worktable inside is not solid, but designed thickness reaching 50mm to 70mm longitudinal and transverse crossing rib plates. These rib plates present "井" shape or rhombus layout, spacing maintains at 300mm to 450mm between. This kind of resembling honeycomb cavity structure at reducing self-weight's same time, takes per square meter load capacity lifted to 12 tons around.

· Worktable wall thickness usually at 80mm to 120mm, resisting local cutting force impact.

· Table surface processed has 28H8 specification T-shaped slots, each slot spacing is 160mm.

· Bottom bearing surface undergone high-frequency quenching, hardened layer depth exceeds 3mm.

· Quenching after surface hardness can reach HRC 50, preventing guideway scoring.

· Supporting base equipped with M48 level anchor bolts, single bolt preload reaches 1000 Newton meters.

Hydrostatic oil cavity evenly distributed at guideway surface under, each oil cavity area approximately 200 square centimeters. High-pressure pump station takes lubricating oil pressed into it, forming thickness approximately being 0.035mm stable oil film, taking huge metal piece entirely "held up".

System working pressure usually set at 3.5MPa to 6.0MPa. Through flow distributor, even if workpiece center of gravity biased to one side, each oil cavity's pressure also will automatically compensate. This kind of design makes friction coefficient reduced to 0.0005 around, driving heavy worktable moving only needs extremely small torque.

Targeting 100 tons load, worktable's guideway oil film static rigidity greater than 1000 Newtons per micron. At receiving 10 tons lateral cutting force time, worktable's offset amount will not exceed 10 microns.

· Hydrostatic system oil tank capacity reaches 200 liters, and equipped with oil cooler.

· Oil temperature fluctuation controlled at plus minus 0.5 degrees Celsius range inside.

· B-axis rotation indexing error smaller than 0.005 millimeters.

· Circular grating scale per circle generates 360 thousand pulse signals to conduct real-time position monitoring.

· Transmission mechanism selects module being 12 heavy helical gear.

· Dual motor backlash elimination system eliminated reverse backlash generated 0.01mm error.

Stainless steel telescopic cover thickness fixed at 3mm, capable of bearing adult trampling and maintaining flat. Scraper board uses 90 Shore hardness polyurethane material, can block diameter 0.05mm fine debris. Bed body foundation pit depth often needs to dig to 2 meters below, cooperating with high-density steel rebar mesh frame, absorbing equipment running time's all vibrations.

Through laser interferometer measurement, at 6 meters long stroke inside, positioning accuracy is locked at 0.02mm range inside. This kind of accuracy level at machine tool delivery 15 years after still able to maintain, mainly attributed to static oil film to metal surface's zero wear protection.

Worktable at bearing irregular workpiece time, anti-overturning moment by large diameter thrust bearing jointly bears. Main bearing diameter often reaches 1.5 meters above, roller accuracy level is P4. This kind of large span support point effectively dispersed lateral pressure, ensuring at conducting 3000mm/min high-speed milling time, workpiece will not produce tiny swinging.

· Bearing roller adopts GCr15 high-carbon chromium bearing steel, tempering hardness reaches HRC 62.

· Automatic lubrication system every interval 15 minutes to key points sprays 2 milliliters lubricating oil.

· Worktable side's grating scale feedback accuracy is 0.1 microns.

· Base casting's natural aging cycle must satisfy 180 days complete span.

Coolant circulation flow rate is set at every minute 60 liters, rapidly taking away large depth cutting generated heat. All hydraulic pipelines uniformly undergone 10MPa pressure test, eliminated heavy load situation under's oil leakage hidden danger. Electrical control cabinet installed has independent air conditioning, ensuring electronic components at 40 degrees Celsius workshop environment under still maintain logic operation's stability.

Constant Temperature Hydrostatic Technology

Motor at 1450 revolutions/minute speed runs, taking label being ISO VG 68 anti-wear hydraulic oil pumped out. Pump station outlet pressure stabilizes at 8.5 MPa around. Hydraulic oil subsequently enters 22 millimeters outer diameter, wall thickness 3 millimeters seamless steel pipe inside.

Oil liquid at steel pipe inside at per second 2.5 meters speed flows, reaching multi-point flow distributor. Distributor inside contains 24 independent capillary restrictors. Capillary inner diameter is precisely processed to 0.8 millimeters, length fixed at 50 millimeters. Oil liquid passes through fine tube time produces pressure drop, reaching guideway oil cavity time pressure becomes 4.5 MPa.

Each rectangular oil cavity's size usually is 400 millimeters long, 150 millimeters wide. High-pressure oil liquid at this place gathers, upward pushing up weight reaching 80 tons worktable. Metal surfaces between formed a layer thickness strictly maintained at 0.04 millimeters oil film.

Metal contact is by this layer thin oil film completely isolated, friction coefficient subsequently cliff-style drops to 0.0003. Thrust test shows, even if table surface on placed 60 tons diesel engine cylinder block, only needs 150 Newtons horizontal thrust just can let worktable produce sliding.

· Oil supply tank total volume reaches 800 liters, inside set three layers magnetic partition boards.

· Double barrel return oil filter interception pore size low to 5 microns, dirt holding capacity reaches 400 grams.

· System circulation flow rate maintains at every minute 65 liters up and down.

· Return oil pipeline slope is 1.5 degrees, relying on gravity naturally returning flow.

Long time flow friction will let oil temperature every hour rise approximately 2.5 degrees Celsius. Worktable side equipped cooling capacity being 15 kilowatts variable frequency oil cooler. Compressor uses R410a environmental protection refrigerant, taking flowing back to oil tank's hydraulic oil cooled, sent out temperature constant at 22 degrees Celsius.

Temperature difference's tiny change will cause cast iron bed body's physical expansion. At 6 meters long guideway on, 1 degree Celsius temperature difference will cause 0.06 millimeters linear elongation. Constant temperature control takes up and down fluctuation locked dead at plus minus 0.1 degrees Celsius interval, prevented micron-level accuracy's loss.

Encountering workshop sudden power outage, oil supply pump will instantly lose power. Pipeline inside parallelly installed capacity being 10 liters bladder type accumulator. Inside pre-charged 3.0 MPa high-purity nitrogen gas.

Accumulator released flow rate able to maintain 0.04 millimeters oil film long reaching 15 seconds. Operator has sufficient time letting 100 tons heavy rotary table safely stop steady.

Grating scale at 2 milliseconds inside captures worktable's tiny tilting trend. PLC controller to PM proportional valve sends out analog signal. 0 to 10 volts voltage signal controls valve core opening degree.

Bearing heavy pressure one side's oil cavity, oil inlet amount instantly increased, pressure is pulled up to 7.6 MPa. Receiving force lighter one side, pressure falls back to 1.5 MPa. Two ends produced pressure difference forms a reverse moment, at 15 milliseconds inside taking 120 tons worktable re-leveled.

Table surface surroundings processed has a circle wide 30 millimeters, deep 20 millimeters oil drain slot. Oil film edge overflowed hydraulic oil along channel flows. Every minute has 45 liters return oil passes through workshop underground polyurethane hose, returns to main pump station filter layer.

Guideway two ends installed Shore hardness being 85 A fluorine rubber scraper boards. Board surface closely sticks to metal surface, bearing per square centimeter 2 kilograms pressing force. Cutting processing generated 0.05 millimeters fine iron chips are blocked at dust cover outside.

· Proportional valve's control dead zone set at 0.5% inside.

· Pressure relay alarm stop threshold locked at 2.0 MPa.

· Filter screen pressure difference transmitter at reaching 0.35 MPa time lights up red lamp.

· New oil first time filling needs to undergo 24 hours precipitation exhaust.

Daily machine start undergoes 120 seconds preheating cycle. Pump station idles, hydraulic oil at pipeline inside completes three times complete closed-loop flow. Temperature sensors distributed at base's 6 temperature measurement points, collected back data comparison error smaller than 0.05 degrees Celsius time, spindle unlocks starts.

Oil tank bottom's water content rate detector stares at five ten-thousandths warning line. Anti-wear additive at extremely high pressure under works 3000 hours after starts degrading. Maintenance regulation requires at this time drain empty 800 liters old oil, to 24 restrictors conduct ultrasonic wave cleaning.

Guideway static oil film rigidity at highest pressure under reaches 1200 Newtons per micron. Spindle at side surface at 1500 revolutions/minute speed conducts 8 millimeters depth heavy cutting. Cutting force to worktable transmitted 8000 Newtons impact. Oil film thickness's compression amount stays at 6 microns.

Oil circuit joint adopts 24 degrees cone surface cooperating O-ring seal. Pipeline at 10 MPa pressure resistance test under maintains 60 minutes no leakage. Torque wrench takes joint nut tightened to 85 Newton meters. System pipeline undergone pickling and phosphating, inner wall roughness reaches Ra 1.6 level.

Load Bearing Range & Anti-Overturning

Bearing dozens up to hundred tons steel giant beast, base size from 2500 by 2500 millimeters starts, maximum splicing size reaches 8000 by 10000 millimeters. A 50-ton class rotary worktable, only itself cast iron weight just high reaches 22 tons. Table surface below evenly distributed 16 to 32 auxiliary support points, taking huge vertical gravity downward transmitted to 1.5 meters deep cement anti-vibration foundation inside.

Milling cutter at table surface edge conducts 12 millimeters depth strong rough cutting time, will to workpiece apply 45000 Newtons horizontal thrust. Table surface bottom's 8 groups hydraulic clamping mechanisms at millisecond level time inside start. Piston rod at 15 MPa high pressure pushes out, deadly bites base on's high-strength dovetail groove.

Single clamping oil cylinder's locking force reaches 120 kilonewtons. Extremely biased load state under's worktable is firmly locked solid at cast iron bed body on, physical displacement amount is forcibly limited at 0.008 millimeters inside. Cutting generated violent vibration along tightly stretched clamping mechanism guided into underground, placed on table surface on's mine crusher thick heavy machine shell completely still.

Heavy load cutting extremely tests downward bearing limit, lateral thrust and workpiece center of gravity's offset to worktable's mechanical structure caused severe pulling.

Encountering wind power hub extremely irregular part, 60 tons weight often deviates from worktable center axis line 1.5 meters above. Gravity multiplied by eccentric distance, produced a near 900 kilonewton meters huge overturning moment. Table surface one side edge bears extremely high downward pressure, another side produces upward turning up furious warping force.

Resisting overturning force originates from bottom's ultra-large thrust roller bearing. Bearing outer ring diameter reaches 2800 millimeters, inside closely arranged 180 pieces diameter being 65 millimeters cylindrical rollers. Roller material selects high-carbon GCr15 bearing steel, surface undergone high-frequency induction quenching, hardness test value reaches HRC 60.

· Dynamic load rated physical value high reaches 8500 kilonewtons, static load destruction limit exceeds 22000 kilonewtons.

· Bearing raceway undergone multiple passes precision grinding, circular runout error is controlled at 0.005 millimeters extremely narrow interval.

· Cage adopts high-strength brass integral turning molding, anti-pulling physical tensile force exceeds 500 MPa.

· Lubricating grease pump station every 200 hours automatically to inside pumps in 150 grams special grease, taking away high-speed friction dissipated heat.

Facing 100 tons above level's ultra-large load task, bottom changes installation to hydrostatic bearing cooperating YRT crossed roller bearing's composite support structure. Outer ring uses 48 pieces M30 specification high-strength bolts with base deadly locked tight. Assembly technician uses hydraulic torque wrench, dividing three times taking nut preload accurately hit to 1800 Newton meters.

Assembly bolt level entirely adopts highest 10.9 level. Preloaded after's bearing inner ring and rotary table surface merged into one body, formed a rigidity extremely strong metal circular disk. At 150 tons biased load working condition under conducting laser interferometer dialing test, table surface outermost edge's physical sinking amount only has 0.012 millimeters.

Physical anti-overturning structure outside covered a layer electronic monitoring protection net. Table surface bottom four quadrants installed micron-level high-precision displacement sensors. Detection probe at per second 500 times high frequency scans table surface and base's gap change. Certain corner's metal gap shrinks exceeding 0.005 millimeters, servo alarm system immediately cuts off feed.

Even if is 0.01 millimeters tiny base tilting, undergone 3 meters high column geometric amplification after, all will at part top cause naked eye visible processing misalignment.

Rotary table carrying 80 tons marine diesel engine giant cylinder block, at every minute 3 revolutions speed conducts indexing alignment. Centrifugal force lets originally static overturning moment produce periodic dynamic change. Servo motor erupts out 45 kilonewton meters peak torque, cooperating double pinion backlash elimination reducer, forcefully pulls holding wanting to follow inertia thrown out heavy table surface.

Transmission gear ring's outer diameter compared to main bearing larger by one circle, reaches 3200 millimeters. Module being 16 heavy gear engaging surface undergone deep layer carburizing quenching, hardness layer deep reaches 4 millimeters. Coping with 200-ton class heavy load emergency stop impact time, gear tooth root can bear 600 MPa instantaneous shear stress and not break.

Table surface processed 28H8 standard T-shaped slot depth reaches 55 millimeters. Clamping uses M24 high-strength pressing plate stud, single stud provides 8 tons vertical downward pressing force. 12 groups heavy pressing plates taking 6 meters wide large flange plate firmly pressed dead at cast iron table surface on.

120 tons worktable at full speed rotating time is heavily pressed down emergency stop button. Huge inertia at 0.5 seconds inside is by hydraulic brake caliper entirely absorbed. Brake disk surface temperature instantly soars to 180 degrees Celsius, table surface sliding distance stays at 15 millimeters inside.

Facing exceeding 300 tons nuclear reactor thick wall outer shell, pure mechanical bearing's load capacity touched physical material's limit. Worktable center area added a group diameter 800 millimeters hydraulic unloading oil cylinder. Pump station outputs 20 MPa high-pressure hydraulic oil, taking bottom oil cylinder upward strongly pushed up, shared away nearly 150 tons vertical gravity.

· Unloading oil cylinder's physical lifting stroke only has 2 millimeters, hydraulic valve response delay shorter than 50 milliseconds.

· Top adopts carrying curvature spherical support block, self-adapting workpiece bottom's tiny uneven state.

· Shared half gravity after, outer ring main bearing borne physical load sharply drops 40%.

· Table surface rotating time's motor friction torque from 8000 Newton meters suddenly drops to 3500 Newton meters inside.

5 years full load uninterrupted service after, table surface center area will measure out 0.02 millimeters slight depression. Maintenance technician uses high-precision laser tracker re-calibrates three-dimensional space coordinate system, taking numerical control system's backlash compensation parameter modified 3 to 5 microns.

Large Scale Castings

Material & Chemical Composition

10-ton medium frequency induction electric furnace produced HT300 high-strength gray cast iron needs to satisfy 3.0% to 3.3% carbon content. Silicon content maintains at 1.4% to 1.8% interval, manganese element content at 0.8% to 1.1% range inside fluctuates. Phosphorus content strictly controlled at 0.12% below, sulfur element locked dead at 0.10% below level.

0.2% to 0.4% chromium element added to molten pool can suppress ferrite growth. 0.3% to 0.6% copper can play refine graphite flake effect. Molybdenum addition amount set as 0.15% to 0.25%, used for improving machine tool large piece's thermal strength. This kind of ratio makes component at 20 degrees Celsius to 100 degrees Celsius environment under's thermal expansion coefficient stabilizes at 12 times 10 to the negative 6th power /K.

· 45% ratio high-quality A3 scrap steel

· 35% ratio low-phosphorus low-sulfur Z14 foundry pig iron

· 20% ratio machine tool factory self-produced high-quality return material

· Per ton molten iron fixed amount adding 5.5kg high-purity graphite recarburizer

· 0.3% to 0.5% ratio 75 ferrosilicon inoculant

Molten iron out of furnace temperature set at 1450 degrees Celsius to 1500 degrees Celsius. Poured into pouring ladle after, 75 ferrosilicon inoculant throwing needs at 3 minutes inside completed. Graphite morphology needs to conform to GB/T 7216 standard inside's A type requirement. Microscope under observed graphite length needs calibrated at level 4 to level 6 range inside.

Pearlite content needs to reach 90% above ratio. Matrix structure inside eradicates appearing free cementite. This kind of structure state lets casting's Brinell hardness at 190HBW to 230HBW between jumps. Machine tool column wall thickness from 40mm transitions to 80mm time, different parts' hardness difference value not exceeds 15 units.

Tensile strength at 300MPa to 350MPa. Using 30mm standard test bar measured bending strength should be at 550MPa above. 12 tons heavy crossbeam casting at bearing 20 tons load time, static deformation amount suppressed at 0.008mm range inside. This kind of density hindered 0.05mm above micro-cracks at inside expanding.

· 20mm wall thickness corresponding hardness standard is 220HBW

· 50mm wall thickness corresponding hardness standard is 205HBW

· 100mm wall thickness corresponding hardness standard not lower than 190HBW

· Guideway surface overall hardness tolerance fluctuation needs controlled at 10 points inside

· Metallographic analysis sampling inspection frequency set as per furnace batch 100% full inspection

Ultrasonic flaw detection depth covers 500mm. Bed body single side guideway surface's non-metallic inclusion area smaller than 0.5 square millimeters. Microstructure inside's phosphorus eutectic interception standard set as smaller than 1.0%. Due to strictly limited impurities, fine grinding after's guideway surface roughness Ra value lower than 0.8 microns.

Pouring completed after's cooling time maintains at 72 hours to 120 hours. Too early shakeout will cause residual stress increase 15% to 25%. Casting at sand box inside naturally cools to 200 degrees Celsius below then allowed opening box operation. Subsequently enters temperature control accuracy being plus minus 5 degrees Celsius annealing furnace to conduct thermal aging.

Tempering temperature set at 550 degrees Celsius to 580 degrees Celsius. Heating speed every hour not exceeds 50 degrees Celsius. Heat preservation 6 hours after, follow furnace cooling speed needs drops to every hour 20 degrees Celsius. This process eliminates 85% above's casting internal stress. Undergone treated casting, at long reaching 10 meters machine tool bed body on, 10 years inside's deformation amount controlled at 0.02mm inside.

· Casting tolerance level needs to conform to GB/T 6414 inside's CT10 level

· Non-processed surface roughness Ra value controlled at 12.5 microns to 25 microns

· Every furnace molten iron needs to retain 3 groups standard tensile test blocks

· Use carbon sulfur analyzer conduct real-time composition monitoring, error smaller than 0.001%

· Guideway quenching depth ensures at 3mm to 5mm between

Floor boring machine's column height reaches 6 meters above, its bottom flange plate thickness designed as 150mm to 200mm. To guarantee pouring mold filling complete, molten iron fluidity through spiral flow experiment measured, length not lower than 800mm. 1.6% around silicon element ratio provides support.

15-ton class above base casting at molding stage adds special chill iron material. Chill iron thickness according to formula Tc = 0.8 multiplied by Tw set. Tc represents chill iron thickness, Tw represents wall thickness. Local chilling means can make guideway part's structure density lift 10%.

Machine tool at 50 tons maximum table surface load under, bed body guideway's unit pressure controlled at 0.2kg/cm2 below. HT300 material's compressive strength high reaches 900MPa, provided sufficient bearing redundancy. At heavy cutting generated 2000Hz high-frequency vibration under, high-damping material can at 0.5 seconds inside attenuate away 80% amplitude.

Spectrometer recorded 12 kinds elements content must true traceability. From ore sand entering site to white blank leaving factory, whole process data recording amount exceeds 150 items. This kind of data transparency provided 15 years accuracy maintainability foundation.

Furnace charge inside's titanium element content needs pressed down to 0.05% below, preventing producing too many hard spots increasing processing difficulty. Antimony element's trace adding (approximately 0.005% to 0.01%) can strengthen pearlite, but exceeding 0.02% will cause brittleness. Technician at pouring before needs to conduct triangular test block test, observing chill depth, range controlled at 3mm to 5mm.

Bed body casting every interval 1.5 meters sets a pass transverse reinforcing rib plate, rib plate thickness is 45mm. Column inside adopts honeycomb shape rib arrangement, rib plate intersection points opened have diameter 50mm process vent holes. This kind of structure at guaranteeing exhaust sand clean's same time, taking whole machine static rigidity lifted to per micron 500 Newtons above.

Stress Elimination

15-ton class floor boring machine bed body from 1450 degrees Celsius molten iron solidifying into solid after, internal residual stress high reaches 80MPa to 120MPa. Not undergo treatment, 10 meters long machine tool at factory leaving half year after, guideway surface's straightness will spontaneously release producing 0.5mm above twisting deformation. Thick large column and base at cooling time inside outside temperature difference uneven, metal lattice inside situates at extremely tightly stretched state.

Heat treatment parameters' setting controls metal inside atoms rearranging process.

Heating up stage strictly controlled at every hour 60 degrees Celsius limit speed inside. Casting thin wall place 40mm and thickened flange place 180mm's expansion difference will tear grain boundary producing tiny cracks. Electric furnace inside's temperature control system every interval 10 minutes acquires one time data, taking bed body front rear ends' temperature difference fluctuation suppressed at 15 degrees Celsius inside. Temperature reaches 580 degrees Celsius's plastic deformation critical point time, metal lattice dislocation gets repaired. Worktable load bearing exceeding 50 tons large base, heat preservation time extends to 8 hours above, heat thoroughly penetrates into thick reaching 200mm reinforcing rib inside.

Cooling stage every hour 20 degrees Celsius descending speed simulated extremely slow physical environment cooling. Furnace door at 300 degrees Celsius above ahead of time opened, cold air rushing in instantly produced thermal shock will make guideway hardness appear 3 to 5 HBW's deviation.

· Thermal aging after's residual stress elimination rate needs to reach 85% above standard

· Furnace bottom support point every interval 1.2 meters sets one place, preventing self weight causing thermal state deformation

· Adopting nitrogen gas protection atmosphere preventing casting surface producing 0.1mm above oxide scale

· Cooling to 150 degrees Celsius below then allowed to conduct lifting transfer operation

Heat treatment finished's white blank piece is moved to open-air stockyard to conduct period being 12 months to 18 months natural standing still. Casting at minus 20 degrees Celsius to above zero 40 degrees Celsius four seasons temperature difference alternation inside, experiences countless times tiny expansion and contraction, removing residual 5% to 10% unstable lattice internal force. Technician at bed body side sets 6 reference measuring points, every interval 90 days uses laser interferometer measures records one time size change. Data deviation from initial period's 0.08mm converges to 0.01mm inside, surveying mapping curve tending flat casting is approved sent into rough processing workshop.

Rough processing cutting off surface 5mm to 8mm hard skin layer broke casting originally had internal external force balance. Workshop introduces vibration aging process, taking large power vibration exciter clamped tight at column rigidity strongest part, seeking machine tool component's inherent resonance frequency point.

Acceleration sensor transmitted back signal if shows main vibration frequency drops and amplitude rises, internal metal lattice dislocation is occurring slipping, force state gets homogenized. 6 meters above long bed body segmented implements excitation, oscillation energy penetrates to every honeycomb shape reinforcing rib node. Semi-finish processing after, metal large piece experiences one time low temperature tempering treatment, temperature set at 350 degrees Celsius. Removing mechanical processing brought cutting force, floor boring machine spindle box's mating surface's flatness maintains at 0.005mm level. Extremely tiny force release all will cause bearing housing hole out of round.

· Rough processing allowance reserved 3mm to 5mm used for force release compensation

· Two times vibration operations between standing still time must not lower than 48 hours

· Contact positioning surface smeared red lead oil to conduct grinding contact rate test

· fine processing before internal force level needs drops to 15MPa below

Assembling horizontal bed body time, anchor bolt's preload uses torque wrench accurately controlled at 400 Newton meters. Casting material's high damping characteristic cooperates thorough treatment procedure, machine tool at conducting 20mm depth large cutting time, bed body guideway's dynamic drift amount controlled at 0.01mm inside.

Manufacturing link issues exclusive verification report, carrying heat treatment temperature curve chart and vibration spectrum chart. Penetrating production beginning to end calculation record escorts floor boring machine continuous serving 15 years after, ram downward bending compensation accuracy maintains at initial factory standard 90% above. High label HT300 cast iron crystal structure extremely dense, chromium, molybdenum etc elements stabilized metal grain boundary.