Used Colgar Ram-Type Floor Boring And Milling M/C for sale (1,10,424)

Condition: excellent (used), functionality: fully functional, BFT 90/5-2 CNC SINUMERIK 840D/840DE Technical Specifications Drilling Spindle Diameter: 102 mm Tool Holder: ISO 50 Operating Manual (see photo) Machine Type: Floor Type Boring Mill Manufacturer: UNION KARL MARX STADT Model: BFT 90/5-2 Year of Manufacture: 1989 Control System: CNC Country of Origin: Germany Freight Terms: Ex-works Rostock, loaded free of charge, unpacked Location: Rostock Availability: Immediately Price: On request Technical Details Spindle Diameter: 102 mm X-axis Travel: 1600 mm Y-axis Travel: 1210 mm Z-axis Travel: 980 mm B-axis (Table): 360° Drilling Depth: 710 mm (W-axis) Redpfx Adey Aiarjgsu W-axis (Longitudinal Spindle Travel): 710 mm Table Load Capacity: 2.5 / 3.0 t CNC Program Control: Numerik CNC Table Size: 1000 x 1120 mm Feed Rate (x/y/z/w): 1 - 3180 mm/min Tool Clamping: ISO 50 Rapid Traverse (x/y/z): 4000 mm/min Rapid Traverse (w): 3150 mm/min Maximum Spindle Speed: 4–1600 rpm Total Connected Load: 27 kW Machine Weight approx.: 9700 kg Electrical Cabinet Dimensions: L: 2500 x W: 650 x H: 2200 mm Machine Dimensions (LxWxH): 5.2 x 3.3 x 2.8 m Additional Information Further Features: - Thread tapping via Z-axis possible - Coolant system with pump - Hydraulic unit

Condition: used, Year of construction: 1983, spindle diameter 120 mm x-travel 1250 mm y-travel 1250 mm z-travel 800 mm spindle taper ISO SK50 number of spindle speeds Max. 2000 min-1 bore spindle stroke . mm main drive motor . kW turning speeds . U/min Feed . mm/min Control Heidenhain type iTNC 430 T-slot - width . mm T-slot - distance . mm table surface area 1000x1000 mm Table load 4000 kg total power requirement . kW weight of the machine ca. . t dimensions of the machine ca. . m Machine number: 62099 The machine table can be rotated continuously via fixed control. Tool magazine has 40 positions. Conversion from Bosch NC System 5 to Heidenhain iTNC 430 approx. 2000 The tech. Data are manufacturer or operator information and therefore non- binding. We reserve the right to prior sale; Our terms and conditions of sale apply exclusively. About us More than 400 of our own machines in stock Over 15,000 m² of storage space, 70 t crane capacity More than 10,000 items and accessories for your workshop Rodpjyqv T Tjfx Adgou If you are interested in selling machines, production lines, or your business, please contact us. You can find further offers on our website. Tours are possible by appointment. We look forward to your visit. Your Markus Hirsch Team

Condition: used, Type BF 63 Spindle mount: 4MT Spindle diameter: 63 mm Spindle speed: 8–1400 rpm Table size: 900 x 710 mm Drilling travel: 560 mm Rodpfx Adewrpy Rogju Table load capacity: 2000 kg Rotary table: 360 degrees

Condition: used, Year of construction: 1987, spindle diameter 130 mm x-travel 3000 mm y-travel 1600 mm z-travel 1250 mm Control Heidenhain type TNC 426 table surface area 2000x1600 mm Table load 12500 kg Rotary table 360 ° spindle turning speed range 12-3000 U/min Feed 1-9999 mm/min Rapid movement 10000 mm/min total power requirement 80 KVA The tech. Data are manufacturer or operator information and therefore non- binding. We reserve the right to prior sale; Our terms and conditions of sale apply exclusively. About us More than 400 of our own machines in stock Over 15,000 m² of storage space, 70 t crane capacity More than 10,000 items and accessories for your workshop If you are interested in selling machines, production lines, or your business, please contact us. You can find further offers on our website. Tours are possible by appointment. Rjdpjyutq Defx Adgsu We look forward to your visit. Your Markus Hirsch Team

Condition: used, Year of construction: 1988, spindle diameter 90 mm x-travel 2000 mm Rsdpfxsyutqks Adgeu y-travel 1250 mm z-travel 1250 mm spindle turning speed range 8-1600 U/min spindle stroke 720 mm Feed 1-2500 mm/U weight of the machine ca. 9,1 t 31881-07/9 The tech. Data are manufacturer or operator information and therefore non- binding. We reserve the right to prior sale; Our terms and conditions of sale apply exclusively. About us More than 400 of our own machines in stock Over 15,000 m² of storage space, 70 t crane capacity More than 10,000 items and accessories for your workshop If you are interested in selling machines, production lines, or your business, please contact us. You can find further offers on our website. Tours are possible by appointment. We look forward to your visit. Your Markus Hirsch Team

Condition: used, Year of construction: 1993, spindle diameter 100 mm x-travel 1250 mm y-travel 1100 mm z-travel 950 mm Table load 3000 kg table surface area 1000x1120 mm turning speeds 16-1250 U/min spindle taper ISO 50 Control Heidenhain weight of the machine ca. 13,4 t No. 2022 The tech. Data are manufacturer or operator information and therefore non- binding. We reserve the right to prior sale; Our terms and conditions of sale apply exclusively. About us More than 400 of our own machines in stock Over 15,000 m² of storage space, 70 t crane capacity More than 10,000 items and accessories for your workshop If you are interested in selling machines, production lines, or your business, please contact us. You can find further offers on our website. Tours are possible by appointment. We look forward to your visit. Your Markus Hirsch Team Rsdpfx Ajyuttfedgeu

Condition: used, Year of construction: 1982, spindle diameter 130 mm x-travel 2750 mm y-travel 2000 mm z-travel 2330 mm spindle taper ISO 50 turning speeds 900 U/min table surface area 1600x1900 mm Radial face slide 600 mm Control Heidenhain TNC 131 bore spindle stroke 1000 mm feed 2500 m/min Table load 8000 kg weight of the machine ca. 37,8 t Rotating table 360° The tech. Data are manufacturer or operator information and therefore non- binding. We reserve the right to prior sale; Our terms and conditions of sale apply exclusively. About us More than 400 of our own machines in stock Over 15,000 m² of storage space, 70 t crane capacity More than 10,000 items and accessories for your workshop If you are interested in selling machines, production lines, or your business, please contact us. You can find further offers on our website. Tours are Rodpeyt R Htsfx Adgou possible by appointment. We look forward to your visit. Your Markus Hirsch Team

Condition: used, Year of construction: 1993, spindle diameter 102 mm x-travel 1600 mm y-travel 1000 mm Redpfxjyt R Ece Adgju z-travel 1600 mm Control Heidenhain type TNC 410 table surface area 1000x1120 mm Table load 3000 kg spindle stroke 710 mm spindle turning speed range 4-1600 U/min main drive motor 13 kW weight of the machine ca. 12 t The tech. Data are manufacturer or operator information and therefore non- binding. We reserve the right to prior sale; Our terms and conditions of sale apply exclusively. About us More than 400 of our own machines in stock Over 15,000 m² of storage space, 70 t crane capacity More than 10,000 items and accessories for your workshop If you are interested in selling machines, production lines, or your business, please contact us. You can find further offers on our website. Tours are possible by appointment. We look forward to your visit. Your Markus Hirsch Team

Condition: used, spindle diameter 125 mm x-travel 2000 mm y-travel 1100 mm z-travel SK 50 mm spindle taper Philips 2500 digital readout Pfillips turning speeds 925 U/min spindle stroke 800 mm Table 1000x1400 mm The tech. Data are manufacturer or operator information and therefore non- binding. We reserve the right to prior sale; Our terms and conditions of sale apply exclusively. About us More than 400 of our own machines in stock Over 15,000 m² of storage space, 70 t crane capacity More than 10,000 items and accessories for your workshop If you are interested in selling machines, production lines, or your business, please contact us. You can find further offers on our website. Tours are Redpfx Adeyt R Anjgeu possible by appointment. We look forward to your visit. Your Markus Hirsch Team

Condition: used, Year of construction: 1992, spindle diameter 100 mm x-travel 1500 mm y-travel 1250 mm z-travel 1800 mm turning speeds 7,1-1120 U/min table surface area 1200x1200 mm w-axis 800 mm Radial face slide 600 mm radial face slide travel 200 mm digital readout Heidenhain The tech. Data are manufacturer or operator information and therefore non- binding. We reserve the right to prior sale; Our terms and conditions of sale apply exclusively. About us More than 400 of our own machines in stock Over 15,000 m² of storage space, 70 t crane capacity More than 10,000 items and accessories for your workshop Rsdpfx Asyqwazedgou If you are interested in selling machines, production lines, or your business, please contact us. You can find further offers on our website. Tours are possible by appointment. We look forward to your visit. Your Markus Hirsch Team

Condition: used, Year of construction: 1985, spindle diameter 130 mm x-travel 3500 mm y-travel 2000 mm z-travel 1250 mm w-axis 800 mm b-axis 360 ° spindle turning speed range 12,5-900 U/min Control Heidenhain type 155 table surface area 1800x1600 mm Table load 12000 kg spindle taper ISO 50 width of T-slots 22 mm T-slot - distance 160 mm Feed 1-6000 mm/min table rotating 360 ° total power requirement 80 KVA weight of the machine ca. 36 t dimensions of the machine ca. 7,7x7,2x4,9 m Refurbished 2005 Head extension Tool kit can be purchased optionally The tech. Data are manufacturer or operator information and therefore non- Rsdpsyqvx Njfx Adgju binding. We reserve the right to prior sale; Our terms and conditions of sale apply exclusively. About us More than 400 of our own machines in stock Over 15,000 m² of storage space, 70 t crane capacity More than 10,000 items and accessories for your workshop If you are interested in selling machines, production lines, or your business, please contact us. You can find further offers on our website. Tours are possible by appointment. We look forward to your visit. Your Markus Hirsch Team

Condition: used, Year of construction: 1992, spindle diameter 100 mm x-travel 1500 mm y-travel 1250 mm Rjdpfx Asyqvmyjdgju z-travel 1800 mm turning speeds 7,1-1120 U/min table surface area 1200x1200 mm w-axis 800 mm Radial face slide 600 mm radial face slide travel 200 mm digital readout Heidenhain The tech. Data are manufacturer or operator information and therefore non- binding. We reserve the right to prior sale; Our terms and conditions of sale apply exclusively. About us More than 400 of our own machines in stock Over 15,000 m² of storage space, 70 t crane capacity More than 10,000 items and accessories for your workshop If you are interested in selling machines, production lines, or your business, please contact us. You can find further offers on our website. Tours are possible by appointment. We look forward to your visit. Your Markus Hirsch Team

Condition: used, spindle diameter 150 mm x-travel 2500 mm y-travel 1600 mm z-travel 1000 mm spindle taper ISO 50 turning speeds 4-1120 U/min Feed 5-2000 mm/min bore spindle stroke 580 mm main drive motor 45 kW table surface area 1600x2000 mm Rsdpfeyquh Aex Adgju table load 12,5 t Control Heidenhain type TNC 410 workpiece weight 15000 kg total power requirement 80 kW dimensions of the machine ca. 6,5x5x5x4 m Machine overhauled 2004 The tech. Data are manufacturer or operator information and therefore non- binding. We reserve the right to prior sale; Our terms and conditions of sale apply exclusively. About us More than 400 of our own machines in stock Over 15,000 m² of storage space, 70 t crane capacity More than 10,000 items and accessories for your workshop If you are interested in selling machines, production lines, or your business, please contact us. You can find further offers on our website. Tours are possible by appointment. We look forward to your visit. Your Markus Hirsch Team

Condition: used, Year of construction: 1980, spindle diameter 100 mm travel -x axis 2000 mm travel -y axis 1200 mm travel -z axis 1000 mm spindle stroke - max. 500 mm table surface area 1250 x 1250 mm table rotating 360 ° max. table load 8000 kg spindle taper ISO 50 spindle turning speed range 30 - 1300 U/min feeds 2 - 1000 mm/min rapid traverse 6 m/min drive capacity - spindle motor 14 kW voltage 380 V control Bosch1-OSA total power requirement 15,0 kW dimensions of the machine ca. 4,20 x 3,00 x 3,00 m - Factory No.: 0149 Refurbished 2000 Machine can be used conventionally The tech. Data are manufacturer or operator information and therefore non- binding. We reserve the right to prior sale; Our terms and conditions of sale apply exclusively. About us More than 400 of our own machines in stock Over 15,000 m² of storage space, 70 t crane capacity More than 10,000 items and accessories for your workshop If you are interested in selling machines, production lines, or your business, please contact us. You can find further offers on our website. Tours are possible by appointment. Rodpfoyqt Hqjx Adgeu We look forward to your visit. Your Markus Hirsch Team

Condition: used, Year of construction: 1992, spindle diameter 130 mm x-travel 3500 mm y-travel 2500 mm z-travel 1250 mm w-axis 800 mm b-axis 360 ° spindle turning speed range 1000 U/min transmission ratio 4 Control Heidenhain type 355 table surface area 1800x2200 mm Table load 12000 kg spindle taper ISO 50 Rsdpfx Adoyqti Esgsu width of T-slots 22 mm T-slot - distance 160 mm Feed 1-6000 mm/min total power requirement 80 KVA weight of the machine ca. 36 t dimensions of the machine ca. 7,7x7,2x4,9 m The tech. Data are manufacturer or operator information and therefore non- binding. We reserve the right to prior sale; Our terms and conditions of sale apply exclusively. About us More than 400 of our own machines in stock Over 15,000 m² of storage space, 70 t crane capacity More than 10,000 items and accessories for your workshop If you are interested in selling machines, production lines, or your business, please contact us. You can find further offers on our website. Tours are possible by appointment. We look forward to your visit. Your Markus Hirsch Team

Condition: used, spindle diameter 130 mm x-travel 2000 mm y-travel 1600 mm z-travel 1000 mm spindle taper ISO 50 turning speeds 4-1120 U/min Feed 5-2000 mm/min bore spindle stroke 850 mm main drive motor 45 kW table surface area 1250x1600 mm Control Heidenhain type TNC 426 Redpfx Aoyqr U Tsdgsu workpiece weight 12500 kg 720 radial face slide travel 240 mm total power requirement 90 kW weight of the machine ca. 26,3 t dimensions of the machine ca. 6,5x5x5x4 m The tech. Data are manufacturer or operator information and therefore non- binding. We reserve the right to prior sale; Our terms and conditions of sale apply exclusively. About us More than 400 of our own machines in stock Over 15,000 m² of storage space, 70 t crane capacity More than 10,000 items and accessories for your workshop If you are interested in selling machines, production lines, or your business, please contact us. You can find further offers on our website. Tours are possible by appointment. We look forward to your visit. Your Markus Hirsch Team

Condition: used, spindle diameter 130 mm x-travel 3500 mm y-travel 2050 mm z-travel 1050 mm spindle taper ISO 50 turning speeds 4-1120 U/min Feed 5-2000 mm/min bore spindle stroke 850 mm main drive motor 45 kW table surface area 1600x2000 mm Control Heidenhain type TNC 426 workpiece weight 12500 kg 720 mm radial face slide travel 240 mm total power requirement 90 kW weight of the machine ca. 31,1 t dimensions of the machine ca. 6,5x5x5x4 m Turntable with digital display The tech. Data are manufacturer or operator information and therefore non- binding. We reserve the right to prior sale; Our terms and conditions of sale apply exclusively. About us More Rodpfx Aoyqr U Hodgou than 400 of our own machines in stock Over 15,000 m² of storage space, 70 t crane capacity More than 10,000 items and accessories for your workshop If you are interested in selling machines, production lines, or your business, please contact us. You can find further offers on our website. Tours are possible by appointment. We look forward to your visit. Your Markus Hirsch Team

Condition: used, x-axis / mm y-axis / mm z-axis / mm The boring mill is sold without clamping plates – the price refers exclusively to the boring mill. Technical data Horizontal milling and drilling machine with support sleeve Working range Vertical adjustment of the headstock from the clamping surface: 0 - 3000 mm Horizontal adjustment of the column: 7000 mm Maximum drilling depth with drill spindle alone: 1200 mm Maximum drilling depth with drill spindle and support sleeve together: 1300 mm Drill spindle diameter: 150 mm Milling spindle diameter: 240 mm Support sleeve diameter: 390 mm Support sleeve extension: 700 mm Drill spindle tool holder: ISO 50 Maximum workpiece weight: 70,000 kg When placed in 4 prisms: 95,000 kg Main drive Total speed range, adjustable from 2 - 795 rpm Series 1 2 - 50.4 rpm Series 2 50.4 - 126 rpm Series 3 126 - 314 rpm Series 4 314 - 795 rpm Maximum drive power at rated speed 17.5 80 kW Quick adjustment speed of spindle box and column 1800 mm/min Rapid adjustment speed of drill spindle and support sleeve 1400 mm/min Fine adjustment speed of spindle box and column medium 75 mm/min Fine 3 mm/min Fine adjustment speed of drill spindle and support sleeve Medium 57.7 mm/min Fine 2.5 mm/min Feed of headstock and column for milling Row 1 3 - 75 mm/min Row 2 72 - 1800 mm/min Feed of drill spindle for drilling Row 1 0.19 - 4.7 mm/min Row 2 2.2 - 56 mm/min Row 3 56 - 1400 mm/min Special equipment Numerical length measuring device in horizontal and vertical directions Accuracy 0.01 mm Rotatable and movable clamping table, Collet & Engelhard, Offenbach Model Tdvmf 1.6 (for technical data, see ‘Clamping table’) Rotatable and movable clamping table from Scharmann, Rheydt Model DAV 1600 Rotatable and movable clamping table from Froriep, Rheydt Swivel crane for tool change, maximum load capacity 500 kg Special tools Carbide core drill bits for extracting core samples Universal facing and boring head from Wohlhaupter, Frickenhausen Model UPA7, with the following specifications: 1 division of the fine adjustment 0.01 mm in diameter 1 revolution of the fine adjustment 0.5 mm in diameter Facing and boring range 0 - 1250 mm Maximum slide adjustment 210 mm Automatic slide feed in mm/rev during facing 0.05 - 0.10 - 0.15 - 0.20 - 0.25 - 0.30 - 0.35 - 0.40 - 0.45 - 0.50 - 0.55 - Rjdpfx Adoxdnrasgsu Quick adjustment per revolution of the quick adjustment spindle 6 mm in diameter Largest diameter of the slide at zero position corresponds to the smallest drilling diameter of 323 mm Head height without shaft 260 mm

Condition: used, travel distance X-axis: 6,000 mm, travel distance Y-axis: 1,800 mm, travel distance Z-axis: 1,000 mm, spindle speed (max.): 4,500 rpm, Equipment: rotational speed infinitely variable, X-AXIS STROKE 6000 MM Redpfjv H D Exsx Adgou Y-AXIS STROKE 1800 MM AXIS STROKE 1000 MM 7300 X 1090 X H 900 MM BENCH ISO 50 SPINDLE NOSE CONNECTION SPINDLE SPEED 0 - 4500 RPM 2.5 ° X 2.5 ° AUTOMATIC INDEX HEAD CNC SELCA 3045 PD EXTERNAL AND INTERNAL HIGH PRESSURE COOLING TOOL CHANGE 60 PLACES NR 01 CNC-MANAGED DIVIDING DEVICE

Condition: used, travel distance X-axis: 16,000 mm, travel distance Y-axis: 3,500 mm, travel distance Z-axis: 1,500 mm, spindle speed (max.): 4,000 rpm, spindle motor power: 37 W, X-AXIS TRAVEL: 16,000 MM Z-AXIS TRAVEL: 1,500 MM Y-AXIS TRAVEL: 3,500 MM SPINDLE MOTOR POWER: 37 KG SPINDLE NOSE CONNECTION: ISO 50 SPINDLE SPEED: 4,000 RPM HEIDENHAIN iTNC 430 CNC 80-POT TOOL CHANGER 2.5° X 2.5° AUTOMATIC HEAD INTERNAL AND EXTERNAL COOLANT HEXAGON WORKPIECE PROBE 2000 X 2000 MM ROTARY-TRANSLATING TABLE, 15 TON LOAD CAPACITY, 1500 MM V-AXIS STROKE OPERATOR CABIN WITH OPERATOR Redpfjx A Ulwox Adgou FIXED PLATES CHIP CONVEYOR

Condition: used, Year of construction: 2004, travel distance X-axis: 6,000 mm, travel distance Y-axis: 2,500 mm, travel distance Z-axis: 1,400 mm, CNC HEIDENHAIN iTNC 530 X-AXIS STROKE 6000 MM Y-AXIS STROKE 1400 MM Z-AXIS STROKE (VERTICAL) 2500 MM Rjdpfoxhqivjx Adgeu SPINDLE CONNECTION ISO 50 DIN 69871-B50 SPINDLE SPEED 5000 RPM MOTOR POWER S1 37 KW - S6 56 KW AUTOMATIC INDEX HEAD 1 ° X 2.5 ° TOOL CHANGER 40 PLACES COOLANT TROUGH THE SPINDLE AND EXTERNAL CHIP CONVEYOR ANCHORING PLATE 8000 X 2000 MM PERIMETER PROTECTIONS

Condition: used, Year of construction: 2007, travel distance X-axis: 6,000 mm, travel distance Y-axis: 2,000 mm, travel distance Z-axis: 1,250 mm, rotational speed (max.): 5,000 rpm, SPINDLE TAPER ISO 50 X LONG. TRAVEL MM.6000 Z SADDLE TRAVEL MM.1250 Y VERTICAL TRAVEL MM.2000 SPINDLE SPEED RPM.5000 FEEDS MM/MIN.8000 SPINDLE MOTOR POWER KW. 37 CNC HEIDENHAIN iTNC 530 REMOTE HAND WEEL FLOOR PLATES 7000x2000- 15 TON/MQ. Rsdjwz H Rfepfx Adgju TABLE 1080 X 7220 X H 820 MM ATC.40 CHIP CONVEYOR ROTATING HEAD IN CONTINUOUS TUPC 0,001°x0,001° COOLANT THROUGH THE SPINDLE 20bar FUNCTION RTCP FPT AUTOCAL EXTERNAL COOLANT TANK HEIGH & LOW PRESSURE WITH PAPER FILTER N.2 AUTOMATIC HORIZONTAL DIVIDERS WITH 2 SUPPORT TABLES N.1 PIECE PROBE

Condition: used, Year of construction: 2005, X AXIS TRAVEL: 10000 MM Y AXIS TRAVEL: 4000 MM Z AXIS TRAVEL (RAM): 1000 MM W AXIS TRAVEL (SPINDLE): 800 MM TOTAL Z + W AXIS TRAVEL: 1800 MM SPINDLE DIAMETER 160 MM SPINDLE MOTOR POWER 40 KW SPINDLE RPM: 3000 RPM SPINDLE TAPER ISO 50 DIN 69871/1A NR 02 SPEED RANGE RAM DIMENSIONS: 460 X 520 MM Rodsup Dclopfx Adgeu RAPID FEEDING 20000 MM/MIN ROTARY TRANSLATION TABLE MODEL MG 50 OF 2500 x 3500 mm , load 50 ton , 360000 position 0,001° stroke 2000 mm HEIDENHAIN iTNC 530 CNC TOOL CHANGER 40 PLACES MANUAL UNIVERSAL HEAD ANCHOR PLATE 6000 X 2000 X 300 MM EXTERNAL REFRIGERATION TOTAL INSTALLED POWER 110 KVA YEAR : 2005

Condition: used, travel distance X-axis: 6,000 mm, travel distance Y-axis: 3,000 mm, travel distance Z-axis: 1,000 mm, spindle diameter: 150 mm, spindle speed (max.): 2,800 rpm, travel distance W-axis: 700 mm, X-AXIS TRAVEL: 6000 MM Y-AXIS TRAVEL: 3000 MM Z-AXIS TRAVEL: 1000 MM Rsdpfxeyb Rzte Adgsu W-AXIS TRAVEL: 700 MM ISO 50 SPINDLE MOTOR POWER: 51 KW SPINDLE ROTATIONAL SPEED: 2800 RPM SPINDLE QUILL DIAMETER: 150 MM SIEMENS 840 D CNC 2000 x 2500 mm rotary table, 1500 mm V-travel, 25 ton load capacity 80-station tool changer AUTOMATIC HEAD 1 AXIS MODEL KF-D4 2.5 ° Through-spindle coolant 2 x 2000 x 5000 mm clamping plates Chip conveyor

Condition: used, Year of construction: 1988, control Heidenhain 355 tool adaptor SK50 weight of the machine ca. 8 t +++++ Please note: The machine is dismantled and ready for loading. It is not possible to show it under power or make a video. Our offer includes already the best pictures. So we don’t have and won’t send additional pictures. +++++ Rsdpfx Ajf Tdvbsdgeu