Used Wmw Relieving Lathe for sale (6,618)

Condition: used, Technical details: turning length: 630 mm swing diameter over slide rest: Hinterdrehschlitten: 250 mm center height over bed: 270 mm centre distance: 900 mm spindle bore: 26 mm range of revolutions per minute - continous: 1,8 - 450 U/min return movement speed: 23 / 32 / 46 / 370 / 510 / 740 U/min cross feed: 0,07 - 1,11 / 36 step mm/U longitudinal feeds:: 0,063 - 0,63 / 12 step mm/U tailstock quill taper MT: 5 quill travel: 250 mm Total power requirement: 7,0 kW machine weight approx.: 3,9 t dimension machine xH: 3,2 x 1,2 x 1,8 m Application: Mainly for relief turning and relief grinding of cutting tools (especially hobs with and without thread pitch). Back turning and relief grinding is possible from the front, the back and in the axial direction of the machine. Main drive via 8-stage manual gearbox. Feed gearbox is designed as a 12-stage manual gearbox. Swiveling range of the rear slide = 360deg. Swiveling range of the cross slide = 360degrees Kljdpfevbh N Rox Akxsr Equipment: lathe chuck driving disc Ø 210 mm with fixed tip fixed tip in tailstock with 4 pieces machine feet 3 jaw chuck Ø 250 mm i.D. *

Condition: used, Year of construction: 1979, Technical details: turning diameter over bed: 540 mm turning length: 630 mm centre distance: 900 mm center height over bed: 270 mm center height: über Hinterschlitten: 138 mm Turning diameter: über Hinterschlitten: 250 mm longitudinal feed: 700 mm facing movement : 80 / 75 mm revolution per minute: 1,8 - 450 bei 8x steples U/min clamping diameter: 26 mm range of feed in x - axis: 12 step / 0,063 - 0,63 mm/U range of feed in y - axis: 36 step / 0,070 - 1,11 mm/U tailstock quill: MK5 mm tailstock quill stroke: 250 mm Total power requirement: 7,0 kW machine weight approx.: 3,76 t dimension machine xH: 3,2 x 1,2 x 1,8 m Application: Mainly for relief turning and relief grinding of cutting tools (especially hobs with and without thread pitch). Back turning and relief grinding is possible from the front, the rear and in the axial direction of the machine. Main drive via 8-stage manual gearbox. Feed gearbox is designed as a 12-stage manual gearbox. Swivel range of the rear slide = 360deg. Swivel range of cross slide = 360deg. Lathe chuck is cone disc Ø 200mm with MK5 Equipment: turning mandrel Ø 49,5 x 400mm Kljdevbhv Ropfx Akxsr Measuring system ARBAH-L 3+1 Inverter FRENIC 5000G11 i.D. *

Condition: used, Year of construction: 1968, Technical details: bore capacity in St 60 - full boring: 40 mm drill capacity in cast iron: 55 mm turning diameter over bed: Ø 22 - 2200 mm clamping diameter: ca.: Ø 100 innen / Ø 200 außen mm Total power requirement: 5,0 kW machine weight approx.: 1,2 t dimension machine xH: 1,70 x 0,80 x 1,40 m Relieving lathe This machine can also be used as a milling head (as a side support). Designation: horizontal unit drilling machine with EB 40 Design: drilling other technical features: Headstock: - Speed 22 - 2000 rpm - feed rate range 0,025 - 0,5 U/mm - three-jaw chuck Ø 190mm with bore Ø 54mm, equipped with internal jaws - headstock bore 45mm - drilling spindle taper MK 5 Kedpou Iwwzofx Akxslr Operation via control panel on the side of the machine. By removing the lathe chuck, the spindle can be used as a drilling unit. max. slide adjustment 300 mm accessories: -div. outer jaws for lathe chuck i.D. *

Condition: like new (used), DN Solutions PUMA DNT2600L 2024 Model – Only 32 Cutting Hours (Like New Condition) Chuck: 12 inch Max Turning Diameter: 460 mm Max Turning Length: 1078 mm Spindle Bore: 81 mm Spindle Speed: 3,500 rpm Main Motor Power: 26 kW Max Torque: 735 Nm X-Axis Travel: 260 mm Z-Axis Travel: 1100 mm Kledpfx Ajy D E Riskxjr Rapid Traverse: X 24 m/min – Z 30 m/min Turret: 12 Stations Guideway System: Box Guideway Machine Weight: 4,900 kg Condition: 2024 model, only 32 cutting hours, almost in brand-new condition.

Condition: used, Technical details: pressure: 25 t distance between columns: 360 mm stroke: 500 mm daylight dimension : table/slide up: 800 mm throat: 360 mm Kjdsu U D I Repfx Akxslr ram stroke: 500 mm ram speed - forward: 0,200 m/s ram speed - reverse: 0,45 m/s Table dimensions: 630 x 500 x 71 mm passage inside table: Ø 182 mm surface area of ram: 450 x 360 mm mortise hole in ram: Ø 32 x 72 mm ram diameter: Ø 125 mm height over floor: 710 mm total power requirement: 12,5 kW weight of the machine ca.: 2,4 t dimension machine xH: 1,7 x 1,1 x 2,95 m Operation via two-hand control panel (and one-hand operation in set-up mode) Continuous and single stroke TÜV until *

Condition: excellent (used), Year of construction: 2008, Control system: Siemens 840-D Travel X: 1450 mm (longitudinal) Travel Y: 1100 mm (vertical) Z travel: 1300 mm Pallet size: 800 x 1000 mm Table load: 2000 kg NC rotary table with direct drive Positioning: 0.001° Max. Max. speed of the rotary indexing table: 60 rpm Rapid traverse: 60 m/min Spindle motor: 50 KW (25%) / 28 KW (100%) Spindle torque: 1210 NM / 680 NM Klodpfxjvgxfyo Akxor Spindle speed: 6000 rpm Spindle taper: HSK 100 Tool changer: 80 places Max. Tool diameter: 325 mm Max. Tool length: 800 mm Max. Tool weight: 35 kg Workpiece diameter: 1600 mm Workpiece height: 1400 mm Workpiece weight: 2000 kg Coolant through spindle Coolant shower Tool breakage detection in the tool changer Spindle motor load monitoring Spindle extension by 100 mm Electronic handwheel Machine is supplied with many tools

Condition: used, Guideway and surface grinding machine WMW FRITZ HECKERT Aschersleben type SZ 1000 x 1250 x 3000 / 344 make no. 13.2236.2 year of construction 1989 nominal grinding area 3000 x 1250 mm table clamping area 3240 x 1000 mm grinding length max. 3300 mm Machining width 1250 mm Machining height 1250 mm grinding wheel diameter (surface grinding support) max. 600 mm grinding wheel width (flat grinding support) max. 100 mm grinding wheel diameter (swivel support) max. 450 mm Ksdpfx Akjhv A A Dexjlr Mains connection 400 Volt, 50 Hz - grinding support swiveling, drive power 16,5 kW, infinitely variable speed - grinding support for surface grinding, drive power 15 kW, infinitely variable speed - new electrical control, based on SIEMENS S7 from year 2001 - new electric control cabinet beside, year of construction 2001 - infinitely variable grinding wheel speed at both grinding supports - swiveling wheelhead for guideway and profile grinding - swivel-mounted and height-adjustable control panel - coolant system adjacent - Hydraulic system adjacent - oil circulation lubrication adjacent - Various grinding wheels and holders space requirement complete L x W x H 11900 x 7700 x 4600 mm weight 45 ton. very good condition

Condition: good (used), Year of construction: 1963, 3 different eccentric presses, manuf. WMW Klsdsmi Rpiepfx Akxjr 1 x crank press with one ram 16 t 1 x crank press with one ram 25 t

Condition: good (used), Reamer, twist drill, drill -Twist drills: different sizes on request -different manufacturers Klsdpfx Aksv H D N Rexjr -Price: Ø 10 - 30 mm 0.50 EUR/mm (drill Ø 20 mm = 10 EUR net) -Price: Ø 31 - 45 mm 1 EUR/mm (drill Ø 35 mm = 35 EUR net) -Price: Ø 46 - 80 mm 1.60 EUR/mm (drill Ø 50 mm = 80 EUR net) -Two-cutter -Diameter: 10-80mm -different lengths -Recordings: MK1 - MK6 -Type: HSS

Condition: good (used), functionality: fully functional, Honing machine SZS 200X500D Ksdpfx Aey D A Niskxolr

Condition: excellent (used), workpiece diameter 60 mm grinding depth 30 mm clamping length 1000 mm weight of the machine ca. 0,6 t dimensions of the machine ca. 0,5 x 0,5 x 2,1 m Ksdpjunt Egsfx Akxolr

Condition: new, Year of construction: 2025, operating hours: 60 h, functionality: fully functional, workpiece weight (max.): 40,000 kg, wheel width: 3,700 mm, feed length X-axis: 2,000 mm, feed length Y-axis: 1,300 mm, feed length Z-axis: 500 mm, rotary table diameter: 3,700 mm, position of the milling head: 0,025, table diameter: 2,000 mm, feed rate X-axis: 10 m/min, feed rate Y-axis: 10 m/min, feed rate Z-axis: 6 m/min, total length: 12,000 mm, gear diameter: 400 mm, total height: 5,000 mm, total width: 4,000 mm, Equipment: CE marking, documentation/manual, rotational speed infinitely variable, TECHNICAL REQUIREMENTS GERARING HOBBING MACHINE GHM 2500 CNC Description of the main components of the GHM 2500 machine The GHM 2500 CNC gearing milling machine is a machine tool intended for processing by milling toothed wheels and toothed crowns. The machine is equipped with an external teeth milling head - which can process the teeth with an inclination angle from 0 to +/- 45 degrees - and an internal teeth milling head. The machine is composed of a milling unit, a unit for clamping and rotating the workpiece and the pinion axis centering tip. The milling/gearing unit is provided with three translation axes and two rotation axes, as follows: -X axis: longitudinal/radial movement towards the workpiece axis -Y axis: vertical movement of the gearing head -Aza Z: tangential movement of the gearing head -Axis: inclination +/-45 degrees of the gearing head -Axis C: rotation of the main axis of the gearing head The part fixing unit (the machine plate) has a rotation axis, axis B, for rotating the part. Kledpfx Asy A Nglskxsr 1. External Gearing head – the housing of the tooth milling head is a GG300 gray cast iron cast piece. On the front side there are the counter guides of the Y axis (vertical movement of the head). Inside are the main tool actuation mechanisms, the mechanism for the horizontal movement of the gearing head axis and the mechanism for tilting the gearing head. The main actuation mechanism of the gearing shaft is composed of a 55 kW – S1 motor, a ZF angular reducer and a gearing shaft, mounted in the housing of the toothing horse. 2. Internal Gearing head – the housing of the tooth milling head is a GG300 gray cast iron cast piece. On the front side there are the counter guides of the Y axis (vertical movement of the head). Inside are the main tool actuation mechanisms, the mechanism for the horizontal movement of the gearing head axis and the mechanism for tilting the gearing head. The main actuation mechanism of the gearing shaft is composed of a 55 kW – S1 motor, a ZF angular reducer and a gearing shaft, mounted in the housing of the toothing horse. 3. The Quill - has the role of fixing the high parts, having a vertical displacement stroke. 4. The longitudinal advance mechanism of the upright, X axis – is made by a servo motor 30 Nm_ 3000 rpm, a Gressner worm reducer and a ball screw diam. 80 x 10, accuracy class IT 3. 5. The vertical advance mechanism of the toothing head, Y axis – consisting of a 30 Nm_ 3000 rpm servo motor, a Gressner worm reducer and a ball screw diam 80 x 10, precision class IT3. 6. Plate advance mechanism / plate rotation, C axis – is made with two 50 Nm_ 2000 rpm servo motor, a Gressner worm reducer and a duplex worm that meshes with the worm crown located on the plate. 7. The gearing head tilting mechanism, axis B – is made by a / 20 Nm_3000 rpm servo motor, a Gressner worm reducer and a worm gear-segment worm gear transmission. 8. The axial displacement mechanism of the gear head, Z axis – is made by a 20 Nm_3000 rpm servomotor, an Alpha Getriebe planetary reducer and a ball screw diam. 63 x 10, accuracy class IT3. 9. Top horizontal positioning mechanism, auxiliary axis X1 – a 20 Nm_ 2000 rpm servo motor, an Alpha Getriebe planetary reducer and a ball screw diam 63 x 10, precision class IT5 are used.

Condition: new, Year of construction: 2026, functionality: fully functional, workpiece weight (max.): 60,000 kg, wheel width: 4,300 mm, feed length X-axis: 2,200 mm, feed length Y-axis: 2,500 mm, feed length Z-axis: 1,500 mm, position of the milling head: 0,02, table diameter: 3,500 mm, feed rate X-axis: 10 m/min, feed rate Z-axis: 6 m/min, total length: 6,000 mm, wheel diameter: 4,300 mm, total height: 7,000 mm, total width: 5,000 mm, workpiece diameter (max.): 4,300 mm, milling spindle length: 2,500 mm, type of input current: three-phase, milling length: 2,500 mm, spindle speed (max.): 2,500 rpm, spindle speed (min.): 1 rpm, Vertical Turning and Milling Lathe VL 40 CNC Turning Center’s Specifications Nominal Turning Envelope Faceplate Diameter 3.500 mm Machining Diameter: -maximum -minimum 4.000 mm 0 mm Swing diameter 4.000 mm Machining Heights 2.000 mm Work Piece Weight 60,000 kg Nominal Turning Travels X - Axis Ram Carriage From -100 mm To 2.250 mm + ATC travel Z - Axis Ram 1.500 mm Work Table WorkTable Diameter 3.500 mm Normal face plate with T-slots Work Table Speed: -for machining 1 - 110 rpm Power Continuous S1/ S6 57/75 kW Torque Continuous S1 / S6 70,000 / 90.000 Nm Turning main drive mechanism Gear box reducer and belt transmission, C axis drive Work Table Milling Speed 0.02 to 2 rpm Milling Torque Continuous S1 43,000 Nm Locking Table Torque (hydraulic double side devices) 60,000 Nm Z - Axis Ram Turning & Milling Ram Ram Size 300 x 300 mm Tool shank size: Shank 32*32 / 40*40 mm automated tool clamping Ram Speed 0 to 2.500 rpm Power Continuous S1 22 kW Torque Continuous S1 1.400 Nm Driving mechanism ZF gearbox, two stages, belt transmission ZF gearbox and main spindle bearing sets are supplied with coolant systems, individually for each. Tool taper BT 50 DIN 69871 / automated tool clamping Tool Storage Number Of Tool Magazines two ATC -one for left side, 20 turning/milling/drilling stations -one for right side 20 milling/drilling and part probe Tool Storage 20 + 20 ATC turning capabilities: Maximum Singular Tool Weight – turning toolholder Maximum Singular Tool Weight – milling/drilling toolholder Total Tool Weight Maximum tool size – turning Maximum tool size – milling Maximum tool size - drilling Maximum length 50 kg 25 kg 600 kg 250 x 150 mm Dia. 300 mm Dia. 120 mm 600 mm Axes Drives X and U - Axes Ram Carriage Power Continuous S1 5.5 kW Thrust Continuous S1 40,000 N Z-Axis Ram Power Continuous S1 5.5 kW Thrust Continuous S1 40,000 N Power Continuous S1 11 kW Axes Rates X And Z - Axes Feed Rates 0.02 to 6,000 mm/min X And Z -Axes Rapid Rates 10,000 mm/min Coolant System Klodjy Dfraspfx Akxsr Coolant Tank Capacity 2.000 L Coolant Pressure / Flow Rate: -internal coolant (turning) -internal coolant (milling) / pressure adjustments steps Filtration unit: -type 6 bar at 100 LPM 30 bar at 60 LPM Cartridge type Chips conveyor Conveyor type Hinged , frontal placed

Condition: good (used), Year of construction: 1982, number of straightening rollers: 13, sheet thickness (max.): 10 mm, Year of construction / YOM: 1982/2024 Sheet width: 2000 mm Sheet thickness - max.: 10 mm Sheet thickness - min.: 3 mm Number of straightening rollers: 13 rollers Straightening roller diameter: 145 mm Straightening speed: 16 m/min Bundle length: 2330 mm Center distance between straightening rollers: 150 mm Support roller diameter: 290 mm Main drive motor: 30 kW Weight: 32 t Klodpfx Aey Ddh Tekxer Additional information: - Number of support rollers: 21/24 - Number of supports (top/bottom): 3 /3 - Traverse lift speed: 0.71 mm/sec - Traverse lift stroke: -18 mm to +42 mm - Max. tilting of lower traverse: 8 mm

Condition: good (used), Year of construction: 1969, number of straightening rollers: 7, working width: 2,500 mm, sheet thickness (max.): 39 mm, max. sheet width: 2500 mm Convexity length of rollers: 2700 mm max. sheet thickness (St 50): 32 mm max. sheet thickness (St 34): 39 mm min. sheet thickness (St 50): 8 mm number of straightening rollers: 7 rollers number of driven straightening rollers: 5 rollers Klodoy Ddf Espfx Akxer diameter of straightening rollers: 290 mm diameter of input/output straightening rollers: 345 mm number of support rollers: 13 diameter of support rollers: 288 mm stroke of upper beam: 120 mm Straightening speed: 16 m / min Rated power of main drive: 90 kW Total load: 138 kW

Condition: good (used), WMW BR 40/2 x 1250 radial drilling machine Drilling capacity in steel (diameter): 60 mm Kledox U Ectepfx Akxjr Arm reach: 1250 mm Max. workpiece height: 820 mm Spindle speed: 20-1200 rpm Spindle taper: MK 5 Spindle stroke: 400 mm Feed rate: 0.063-0.63 m/min Vertical arm adjustment: 950 mm Electrical connection: 380 / 50 V / Hz Clamping surface of base plate: 1400x800 mm Total power requirement: 5 kW Machine weight approx.: 3 t Floor space required approx.: 2.2 x 1.0 x 2.8 m

Condition: used, functionality: fully functional, Column drilling machine Tool holder MK 4 With gear transmission, quill feed. Kljdoy A Sz Sspfx Akxsr

Condition: good (used), Year of construction: 1972, Slideway grinding machine WMW SFBZ 2200/6000 Kedsw U A Rmjpfx Akxjlr Manufactured by WMW Germany in 1972 Main technical data: Table size: 2240x6000 mm Max. grinding width: 2200 mm Max. grinding length: 6000 mm Max. grinding height: 2000 mm Max. workpiece weight: 15000 kg Machine weight: 130 tons The machine underwent a general overhaul in 2022. The feed boxes with electromagnetic couplings were replaced with motors and gearboxes for both heads. The bearings for the universal grinding head were also replaced. For more information, please contact us.

Condition: ready for operation (used), functionality: fully functional, turning diameter over cross slide: 530 mm, spindle bore: 90 mm, turning diameter: 920 mm, Lathe type WMW DLZ 800 III for sale. Equipped with Heidenhain digital readout. The machine functions flawlessly and has seen very little use (mainly for maintenance). Includes faceplate, 2x steady rests, several tool holders, and operating manual. - Heidenhain digital readout Kljdpfx Aksy Ar Nisxsr - Turning length: 3150 mm - Weight: approx. 7300 kg - Power: 13/20 kW - 380 V - Swing over bed: 800 mm - Swing over gap: 920 mm - Swing over cross slide: 530 mm - Spindle bore: 90 mm - Tailstock MK-6 Loading by forklift. Shipping possible by arrangement. Please feel free to contact me with any questions.

Condition: good (used), Year of construction: 1975, table width: 750 mm, table length: 1,000 mm, throat depth: 400 mm, ram plate width: 500 mm, ram plate length: 630 mm, Pressure: 250 t Throat: 400 mm Stroke: 30...140 mm Table size: 1000 x 750 mm Passage opening in table: 360 x 400 mm Ram area: 630 x 500 mm Ram adjustment: 110 mm Kjdpfx Aksy Amypjxslr Total power requirement: 18 kW Machine weight approx.: 16 t

Condition: good (used), Year of construction: 1994, Pressure: 250 t Throat depth: 360 mm Table size: 1250 x 630 mm Table diameter: 250 mm Ram clamping surface: 850 x 450 mm Kjdpfx Aey Amxxekxelr Installation height: 800 mm Piston stroke: up to 500 mm Piston diameter: 400/360 mm Ram speed downward: 200 mm/sec Ram speed upward: 110 mm/sec Total power requirement: 20.5 kW Machine weight approx.: 8 t

Condition: good (used), Year of construction: 1986, Inner diameter: 20…400 mm Grinding depth: 315 mm Internal grinding spindle speeds, stepless: 2,640…16,500 rpm Workpiece spindle speed: 40…400 rpm Table feed rate: 0.1…8 m/min Rapid traverse: 10 m/min Table travel: 630 mm Total power requirement: 16 kW Machine weight approx.: 5.8 t Additional information: Grindable diameter within workpiece guard: internal 20…400 mm; external 500 mm Max. workpiece diameter in workpiece guard: 500 mm Max. grinding depth: 315 mm Grindable taper angle: 60° Internal grinding spindle speeds: 2,640…16,500 rpm Drive power for face grinding attachment: 4 kW Kedpfxey Amwnj Akxelr Drive power for workpiece motor: 1.5 kW Workpiece spindle speeds: 40…400 rpm Table speed: 0.1…8 m/min Rapid traverse: 10 m/min Table travel: 630 mm Max. distance from workpiece spindle flange to grinding spindle carrier: 1,250 mm

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 Kledpfxsy Aiars Akxsr 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) 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: good (used), Year of construction: 1991, Table clamping surface: 710 x 400 mm Tool holder: ISO 40 Travel paths: X-axis: 400 mm Y-axis: 350 mm Additionally displaceable in Y-axis: 420 mm Z-axis: 380 mm Quill stroke: 80 mm Speed range: 45 – 2240 rpm Feed range, stepless: 6.3 – 1250 mm/min Kledsupiypepfx Akxjr Rapid traverse: 1250 mm/min Drive power: 2.2 / 2.8 kW Dimensions (L x W x H): 1400 x 1600 x 1850 mm Weight: 1900 kg Accessories / Special Features: • 3-axis digital readout by HEIDENHAIN • Vertical and horizontal milling spindle • Vertical milling head with quill, tiltable right and left • Stepless feed • Rapid traverse on all 3 axes • Fixed angle table • Coolant system • Chip tray • Spindle clamping by push button, e.g., for tool change • Machine feet • Central lubrication • Control panel • Emergency stop switch Siegfried Volz Machine Tools Rüschebrinkstr. 151-153 DE - 44143 Dortmund - Wambel

Condition: used, total height: 1,800 mm, total length: 3,500 mm, total width: 2,300 mm, Empty weight: 5.800 kg Price: On request Grinding diameter: 315mm Grinding depth: 500mm Swing: 500/600mm Stroke of table: 800mm - Documentation available: No - CE certificate present: No - Serial number: 31577 - Drive system: Conventional - Grinding diameter [mm]: 315 - X-axis travel [mm]: 800 - Transport dimensions: 3500mm x 2300mm x 1800mm (l x w x h) - Transport weight [kg]: 5800kg - Transport packages [pcs.]: 1 Financial information VAT: The price shown is exclusive of VAT VAT/margin: VAT deductible for entrepreneurs Delivery and trade-in always possible for everything in the industrial sectors Kljdswya A Sepfx Akxor Lukas van Rossum