Abstract: A machining apparatus has a frame having an upright front wall and two vertical guides on the front wall carrying respective spindle units displaceable on the guides and each having a workpiece holder rotatable about a respective vertical axis and vertically shiftable between a respective upper machining station and a respective lower pick-up/drop-off station. A horizontal guide on the front wall carries a tool turret carrying a tool and shiftable along the horizontal guide between one position aligned with the axis of one of the spindles and another position aligned with the axis of the other of the spindles. A conveyor transports unmachined workpieces into the lower stations and machined workpieces out of the lower stations. Respective actuators shift the spindle units vertically along the respective axis between the lower stations and the upper stations.

Abstract: A machining apparatus has a frame defining a transfer station and a machining station thereabove, a spindle having a workpiece grab and vertically displaceable on the frame between an upper position with the grab in the machining station and a lower position with the grab in the transfer station, a tool holder horizontally displaceable on the frame toward and away from the machining station, and a workpiece conveyor extending through the transfer station. After shifting a deflector underneath the machining station into a side position out from underneath the grab, the grab is lowered to pick an at least partially unmachined workpiece in the transfer station off the conveyor and then raised with the workpiece into the machining station. The deflector is then shifted between a use position over the transfer station and under the machining station and a side position allowing the spindle to pass.

Abstract: To provide a machine tool capable of preventing even chips in a powder form and coolant from leaking to a feed mechanism side. A slide plate 12 is provided to cover a feed mechanism 16. The slide plate 12 is fixed to a second headstock 6 to move in an axial direction together with the second headstock 6. Between the slide plate 12 and a bed side member, a seal portion 31 is provided. The seal portion 31 has a first slide contact member 20 provided on the slide plate 12 and a second slide contact member 18b which is provided on the bed side member and in slide contact with the first slide contact member 20, and the first and second slide contact members 20 and 18b relatively slide while being in contact with each other.

Abstract: A basic body for tools for chip removing machining, including an internal duct, and an inlet including a female thread for the supply of liquid to the duct. The female thread of the inlet is formed in a cage, which is inserted in a seating delimited by an endless inner wall as well as a bottom, the duct mouthing in the seating.

Abstract: Milling cutter (1), which can rotate about a cutter longitudinal axis (A), comprises a sleeve-shaped shaft (2) provided with an inner lying chip evacuation channel (11), which is arranged, in essence, symmetric to the cutter longitudinal axis (A), and with a suction opening (12). The milling cutter also comprises a milling head (3, 3a, 3b, 3c), which is held coaxial to the cutter longitudinal axis (A) and to the shaft (2) while being held on said shaft and which comprises, as cutting edges (7, 9), a face cutting edge (7) and a peripheral cutting edge (9). At least one cutting edge (7, 9) forms a positive rake angle (?Ya,?Yr) on the periphery of the milling head (3, 3a, 3b, 3c). The milling cutter (1) is particularly suited for machining light metals, especially for circular milling.

Abstract: This invention is a method and apparatus for cutting a workpiece which may have interruptions, with a cutting insert having a cutting edge, where the cutting insert is held in a tool holder and is optionally supported by a shim. Coolant, which may contain liquid nitrogen, is introduced through a passageway to a cooling passage located near the cutting edge. The cooling passage may be located either under, behind, or under and behind the cutting edge. Coolant impacts the wall surfaces of the cooling passage near the cutting edge where it is partly evaporated thereby cooling the cutting insert.

Abstract: Milling cutter (1), which can rotate about a cutter longitudinal axis (A), comprises a sleeve-shaped shaft (2) provided with an inner lying chip evacuation channel (11), which is arranged, in essence, symmetric to the cutter longitudinal axis (A), and with a suction opening (12). The milling cutter also comprises a milling head (3, 3a, 3b, 3c), which is held coaxial to the cutter longitudinal axis (A) and to the shaft (2) while being held on said shaft and which comprises, as cutting edges (7, 9), a face cutting edge (7) and a peripheral cutting edge (9). At least one cutting edge (7, 9) forms a positive rake angle (?a, ?r) on the periphery of the milling head (3, 3a, 3b, 3c). The milling cutter (1) is particularly suited for machining light metals, especially for circular milling.

Abstract: A one-piece lathe tool for boring with a cross-section of less than 10 mm, includes an essentially-cylindrical tool body intended to be inserted and held in a tool support which is traversed by at least one lubricant supply channel. One end of the tool body extends into a neck which terminates in a head that forms the active part of the tool. In order to ensure good lubrication, the neck is offset in relation to the axis of the tool body, while, at the end of the neck, the head is offset in relation to the axis. The head, together with the cutting edge thereof, falls within and is essentially tangent to the periphery of a cylindrical space corresponding to the extension of the tool body. A machining assembly including such a one-piece lathe tool and a tool support are also disclosed.

Abstract: Milling cutter (1), which can rotate about a cutter longitudinal axis (A), comprises a sleeve-shaped shaft (2) provided with an inner lying chip evacuation channel (11), which is arranged, in essence, symmetric to the cutter longitudinal axis (A), and with a suction opening (12). The milling cutter also comprises a milling head (3, 3a, 3b, 3c), which is held coaxial to the cutter longitudinal axis (A) and to the shaft (2) while being held on said shaft and which comprises, as cutting edges (7, 9), a face cutting edge (7) and a peripheral cutting edge (9). At least one cutting edge (7, 9) forms a positive rake angle (?a, ?r) on the periphery of the milling head (3, 3a, 3b, 3c). The milling cutter (1) is particularly suited for machining light metals, especially for circular milling.

Abstract: An assembly suited to the lathing of cylindrical workpieces, such as photoreceptor blanks, includes a first drive system which rotates an associated workpiece about an axis of rotation. A machining tool machines a circumference of the workpiece to generate a strip of material. A cutting apparatus cuts the strip of material into sections. The cutting apparatus includes first and second rotatably mounted members which define a nip therebetween. A first of the rotatable members carries a cutting member on a peripheral surface thereof. A second drive system rotates the first and second rotatable members. The second drive system may be adjustable whereby a circumferential speed of the rotatable members can be matched to a circumferential speed of the workpiece. A transverse speed of the cutting apparatus may be matched to that of the machining tool.

Abstract: A method and an apparatus or machining a workpiece include the use of a cryogenically cooled oxide containing ceramic cutting tool. The method involves cryogenic cooling of the cutting tool during a cutting operation, which cooling results in enhanced wear resistance and fracture resistance of the cutting tool. A preferred embodiment involves jetting a cryogenic fluid directly at the cutting tool.

Abstract: A wheel chuck assembly includes a support plate having at least one aperture formed therethrough. The support plate is adapted to be mounted upon a lathe spindle. An air conveying device is mounted adjacent to the support plate and is operable to induce an air flow through the support plate aperture such that metal chips are drawn through the support plate aperture.

Abstract: In a machine tool (10) with a machine base (11), a working area (14), in which workpieces (13) are machined, and a device (25), which receives chips (24) formed during machining of the workpieces (13) from the working area (14) and conveys them onward, at least one tunnel (31, 33) provided for receiving one end (39) of a chip conveyor (38) is provided in the machine base (11), which tunnel extends at least to below the device (25) and is there of upwardly open (28) design.

Abstract: A machine tool that comprises a fixed bed, a pair of tool posts mounted on the fixed bed on a side closer to an operator and a carriage mounted on each of the tool posts is disclosed. A headstock is provided on a side of the fixed bed farther from the operator so that a workpiece disposed in the headstock is subjected to a cutting process by moving the carriages and the tool posts relative to the workpiece. The machine tool also includes a headstock base having the headstock disposed thereon. The headstock base is structured and arranged so as to be movable between a workpiece machining position where the workpiece can be machined at a position farther from the operator and a workpiece loading and unloading position where the workpiece can be loaded and unloaded at a position closer to the operator.

Abstract: There is provided a product recovery apparatus in which mixture of cut wastes or a coolant into a receiver box is reduced and which can be disposed in the vicinity of a portion to be processed or in a processing chamber and which saves space and has high recovery rate of products. The product recovery apparatus for recovering the product from a machine tool for processing a material held by material hold means to produce the product, comprises: a product recovery tube for receiving the product; suction air generation means for bringing the product into the product recovery tube by suction of air; and a recovery container of the product disposed between the suction air generation means and product recovery tube. The recovery container may include a coolant reservoir portion for pooling a coolant in the recovery container, and the product recovered by the product recovery tube may be allowed to drop into the coolant in the coolant reservoir portion.

Abstract: A portion (14a, 14b) of a chip remover (14) is defined to be vibratory to give an NC machine tool (MT 1) a vibration transferable onto a surface (FS) of a work (13) under a finishing by the NC machine tool (MT1), a decision is made whether the NC machine tool (MT1) enters the finishing, and vibration of the vibratory portion (14a, 14b) is controlled, as the decision is true. A chip removal method and an NC machine tool equipped with a spiral chip remover (113) as a chip remover have various chip removal rules for determining permission/prohibition of the operation of the spiral chip remover (113). This spiral chip remover (113) operates based on commands described in a machining program. When a command in the machining program is executed, the permission/prohibition of the operation of the spiral chip remover (113) is controlled according to the chip removal rules.

Abstract: A chip conveyer including an endless conveying member (18) that circulates in a predetermined direction for receiving chips discharged from a machine tool in a receiving zone, conveying the chips to a discharge position (E2) spaced from the receiving zone at a predetermined interval, and discharging the chips at the discharge position. A conveying member (18) travels along a forward route (R2) from an end (E1) of the receiving zone to a turning point (E2) of the conveying member (18), discharges the chips at the turning point (E2), and travels along a return route (R3) from the turning point (E2) to a return point (E3) where the conveying member (18) is returned to the receiving zone. The conveying member (18) enters the liquid reservoir (31) while moving along the return route (R3) such that the chips adhered to the conveying member due to an oil component are separated in liquid in the liquid reservoir (31). A liquid supply device supplies the liquid to the liquid reservoir (31).

Abstract: A method of optimizing the functioning of a machining center for machining, at least one piece, by removal of material by means of at least one cutting tool. The machining center includes a certain number of different components including at least a structure, such as a frame, and at least one motor elements for producing actions of driving and displacement of at least the cutting tool and the piece. Further, the method includes an installation for lubricating and cooling the tool and the piece by means of a fluid, (i.e., lubricant) by determining at least one temperature value for the lubricant, at least empirically, referred to as the reference value, at which the machining center functions in a stable way, (e.g.

Abstract: A machining system having a first machine tool assembly with a first workpiece holder and a first machining unit for performing a processing operation on a workpiece held by the first workpiece holder, and a second machine tool assembly having a second workpiece holder and a second machining unit for performing a processing operation on a workpiece held by the second workpiece holder. The machining system further includes a base assembly on which the first and second machine tool assemblies are supported in an operative position. At least a part of the first machine tool assembly is repositionable by movement along a first line. At least a part of the second machine tool assembly is repositionable by movement along a second line that is non-parallel to the first line. The parts of the first and second machine tool assemblies are relatively repositionable along the first and second lines to facilitate transfer of a workpiece between the first and second machine tool assemblies.

Abstract: A chip conveyor includes an endless carrier that circulates in a predetermined direction such that chips discharged by machine tools are collected at a collecting position, are carried to a discharging position, which is spaced from the collecting position by a predetermined distance, and are discharged at the discharging position. The carrier follows an upper path from the collecting position to the discharging position and returns through a lower path from the discharging position to the collecting position. A reservoir tank is provided to correspond to the lower path of the carrier. The carrier passes through the reservoir tank, and chips attached to the carrier are separated from the carrier in a liquid in the reservoir tank.

Abstract: A cutting method in which a solution is sprayed or jetted to a machining portion when machining by use of a water-insoluble cutting oil, wherein recovered liquid is collected and stored in one recovery tank, and separated into the water-insoluble cutting oil and another solution on the basis of the specific gravity difference, and are re-used. Stable machining is enabled by using the water-insoluble cutting oil, and measures against disaster are fully taken.

Abstract: Universal tool holder coolant delivery adapters have adapter bodies which are removably attachable to a tool holder by at least one fastening device, the adapter located between an attachment end of the tool holder and a distal end of the tool holder, the distal end of the tool holder having a cutting tool attached thereto, the adapter bodies having an internal coolant passageway including an intake port and an exit port, the intake port adapted for attachment to a pressurized coolant supply line and the outlet port adapted for attachment to or configured in the form of a coolant spray nozzle, the coolant spray nozzle being closely positioned and substantially aligned with the cutting interface of the cutting tool and a workpiece.

Abstract: A process including providing a hollow cvlindrical substrate, the substrate having a dry outer surface describing a curvilinear plane, a dry inner surface describing a curvilinear plane, a first end opposite a second end, and an imaginary axis extending from the first end to the second end, supporting the substrate, machining at least a portion of at least one end of the substrate with at least one dry polycrystalline diamond cutting tool in the absence of liquids to remove material from the substrate, and simultaneously maintaining, during machining, the dry inner surface of the cylindrical substrate free of the material machined from the at least one end of the substrate by the at least one dry polycrystalline diamond cutting tool.

Abstract: A cutting tool for cutting a work piece and catching debris during turning operations is described herein. The cutting tool comprises a tubular cutting member having first and second ends, the first end having a sharpened edge, and a debris receiving means connected to the second end. The tubular cutting member may have a number of different cross-sections providing a number of different cutting tool configurations for use in turning operations. The debris receiving means may further include a flexible hose having a first hose end and a second hose end, wherein the first hose end is connected to the second end of said tubular cutting member. The hose may be connected to a vacuum source to more effectively collect debris generated during turning operations. The tubular cutting member could be made in a range of sizes from one quarter inch to two inches in diameter, with a nominal tube length of from three inches to twenty inches, or even larger where needed.

Abstract: A tool block and holder for metal working lathes, comprising, a tool block having a tool channel extending therethrough sized to receive snugly a collet holder with a collar at its proximate end serving as a stop against the tool block, and first coolant channel that communicates a fluid coolant from a source external to the tool block to the tool channel at a point beyond the distal end of the collet holder; a collet sized to be received snugly within the collet holder and having a hollow interior and a nose at its proximate end with an opening sized to receive the shank of a metal working tool and having male threads at its distal end; and a draw nut having a proximate end sized to be received snugly within the tool channel, female threads at its proximate end sized to receive the male threads at the distal end of the collet, a flange at the distal end of the draw nut serving as a stop against the tool block, and second coolant channel in fluid communication with the first coolant channel and the hollow int

Abstract: A coolant liquid feeding method comprises feeding a coolant liquid, with air bubbles caused to form continuously therein, for cutting or grinding operation to a region under machining, expediting the splashing of air bubbles in all directions when the air bubbles impinge on the region under machining and burst, and also expediting the entry of accelerated splashed liquid particles into a cutter/workpiece pressure contact plane, thereby improving the cooling and lubrication of the region under machining, whereby the air bubbles in the coolant liquid which has failed to reach the region under machining or which, though reaching there, has left there for the recovery channel are allowed to adhere to suspended foreign matters in the liquid, thereby expediting the surfacing of the foreign matters.

Abstract: A tool holder for holding cutting inserts for machine tool work includes an integral cooling passage therethrough. Various coolant nozzles are interchangeably installable in the holder, to provide different amounts of coolant fluid flow depending upon the specific work being accomplished. The portion of the cooling passage in the tool holder adjacent to the installed nozzle, as well as the nozzles, are devoid of bends or changes in direction of the coolant flow path for greater efficiency and to ensure that the coolant flow is directed precisely at the cutting tip of the insert regardless of the radial orientation of the nozzle. The nozzles each incorporate a non-circular, preferably triangular, coolant outlet tip, which cross sectional shape blends smoothly with the circular cross sectional shape of the nozzle inlet and passage through the tool holder.

Abstract: There are disclosed a cylindrical member, constituting the main body of an electrophotographic photosensitive drum or a developing sleeve adapted for use in an image forming apparatus such as electrophotographic copying machine, laser beam printer, facsimile or printer, and a producing method therefor. A work obtained by cutting a tube, is worked to a predetermined internal diameter at the left-hand end, and is supported by an opening collet of the left arbor, while the other end is supported by a closing collet of the right arbor. A cutting tool holder, supporting a rough cutting tool and a finish cutting tool, rotates around the work at a high speed, and the work is moved axially by the table. Thus, the rough cutting tool and the finish cutting tool move in the axial direction of the work while rotating along the external curved surface thereof, thus cutting the surface.

Abstract: A structural frame is provided for a machine tool including a tool holder and a workpiece holder for holding the workpiece as the workpiece is machined by a cutting tool held in the tool holder.

Abstract: The hobbing machine has a tool assembly with a tool spindle and a workpiece holding assembly with a workpiece spindle. A first drive unit for driving the tool spindle is provided. A second drive unit for driving the workpiece spindle is provided. The tool spindle and/or the workpiece spindle is a rotor of the first and second drive unit so that the tool spindle and/or workpiece spindle can be directly driven by the drive unit.

Abstract: A method of for performing a machining operation and recovering a liquid used in the machining operation. The method includes the steps of providing a machine tool to perform a machining operation, directing a liquid against at least one of a) a part of the machine tool and b) a workpiece on which the machining operation is being performed by the machine tool in such a manner that discrete particles become entrained in the liquid, directing at least a part of the liquid with the discrete particles entrained therein to a first location, and at the first location separating the liquid from the discrete particles.

Abstract: A controlled atmosphere machining process which involves a work station for machining a workpiece with an inert gas in an enclosed environment which will not support combustion. The process further includes a vacuum system which removes particulate matter occurring during the machining process and transports the matter to a collecting tank. The inert fluid is recycled through a filter and cooling system and continues to be drawn by the vacuum system into the enclosed machining area of each work station.

Abstract: A numerically controlled lathe includes a spindle, a hydraulic rotary cylinder driven by a pressurized working fluid for causing the spindle to rotate, a fluid pump for discharging the working fluid to be delivered to the hydraulic rotary cylinder, a reservoir for storage of the working fluid, first and second delivery conduits each having first and second ends, the first ends of the delivery conduits selectively connected to the fluid pump and the reservoir, and a fluid coupler for coupling the second ends of the delivery conduits with the hydraulic rotary cylinder.

Abstract: A method for producing discontinuous chips during the machining of a work piece by a cutting tool is provided. The method includes the steps of engaging the cutting tool into the workpiece to produce a continuous chip and directing a stream of cryogen toward the continuous chip, so as to rapidly cool the continuous chip and fracture the continuous chip into the discontinuous chips.

Abstract: Apparatus capable of performing wet and dry machining processes such as a hobbing machine for producing spur and helical gears, shafts, splines, and the like, by wet and dry hobbing methods. The apparatus comprises means to remove metal chips resulting from the wet and dry machining processes from the apparatus via respective independent wet and dry chip outlets. The chip removal means comprises a transfer means located in the machine base with the transfer means being reversible in direction in order to convey metal chips, emanating from the machining process, to the respective wet or dry chip outlet. The chip removal means enables metal chips from wet machining processes to be conveyed to and discharged from an outlet in one side surface and metal chips from dry machining processes to be conveyed to and discharged from an outlet in another side surface.

Abstract: The chuck, the bar which operates it, and the cylinder and piston assembly which moves the bar are axially hollow and form a vertical duct which is open at the top next to the workpiece and which is open at the bottom over a conveyor with a filter and a unit for collecting and pumping the cutting fluid. The chips from the piece are channelled and removed downwards through the said duct by at least one jet of fluid at high pressure, which has a location and direction such that it strikes the chip after its formation without interfering with the normal jet of fluid at low pressure which is applied to the tool. The said jet or jets of fluid at high pressure consist of the same cutting fluid as that which is directed against the tool at low pressure. The chips leaving the lower end of the said duct fall on to the conveyor which removes them and separates them from the cutting fluid which, when suitably filtered, is returned to circulation by low-pressure and high-pressure pumps.

Abstract: A metal turning chip breaking apparatus includes an impulse actuator in the form of a piezoelectric element that rapidly expands and contracts in response to a rapidly applied and removed voltage. This, in turn, is used to impulsively move a cutter support in a matching fashion, causing a cutter to rapidly withdraw from and return to the cut in a chopping action. This breaks up the chip, which would otherwise form continuously. There is no need to synchronize the incremental motion of the cutter with the rotation of the workpiece.

Abstract: An improved toolholder assembly and method is provided that comprises an adjustable nozzle for redirecting a liquid coolant stream from a direction generally parallel or slightly oblique with respect to the axis of rotation of a workpiece to a direction that is substantially orthogonal with respect to this axis. The nozzle assembly includes a threaded base on one end and a nozzle head on the other, and the threaded base may be screwed into or out of a threaded opening in the toolholder body which communicates with the original coolant stream opening in order to adjust the nozzle head at both a desired angle in a plane orthogonal with respect to the axis of rotation of the workpiece, as well as at a desired point along this axis.

Abstract: A CNC (computer numerical control) lathe includes a tailstock feed mechanism consisting of a feed hopper and an air cylinder for feeding a short workpiece, and a secondary tool turret having a feed chuck and a set of rear end cutting tools for processing the end of a bar stock material which has been processed by a main tool turret and a radial processing mechanism for processing a short workpiece delivered through the tailstock feed mechanism.

Abstract: An apparatus and method for the hydraulic removal and collection of cuttings from machine tool systems. The present invention provides a cutting removal and collection system comprising a housing at least partially enclosing a machine tool and a plurality of trays at the bottom of the housing for collecting the cuttings as they fall from the machine tool. Jets of fluid, such as a liquid coolant, are used to direct the cuttings along the trays and into a rotating drum. The drum has a hollow annular structure with fins disposed in an axial direction along its interior. The drum also has a perforated surface for allowing drainage of the fluid off of said cuttings and back into a tank positioned below the rotating drum. As the drum rotates, the fins carry the cuttings in the circumferential direction of rotation. Once the cuttings are carried to a certain height, gravity causes the cuttings to fall onto a drop tray positioned along a horizontal chord of the rotating drum.

Abstract: A chip flushing apparatus for connection to a machine tool for flushing chips of debris from cutting operations performed by the machine tool. The flushing apparatus includes a header bar having outlet means for dispensing fluid to a chip receiving area of the machine tool for transporting the chips to a recovery box. A fluid flow deflector is positioned near the outlets of the header to deflect the fluid streams into a laminar flow across the fluid receiving area. A removable tank is mounted below the receiving area to receive the flushing fluid. The tank is wheeled for convenient transport.

Abstract: A machine tool (100) has a spindle (101) and a turret or toolholder (124) which are disposed at the front of a base (134).A workpiece (W) is rotated by the spindle (101). The turret (124) is movable toward and away from the workpiece (W) along a path which has vertical and horizontal components. A conveyor assembly (200) is operable to move workpieces between the rear of the base (134) and the spindle (101) along a path (A) which extends through a plane (E) which contains the axis (C) of rotation of the spindle. The plane (E) is parallel to vertical and horizontal components of movement of the turret (123). An alternative embodiment (100a) of the machine tool includes a pair of spindles (101a, 301) and a pair of turrets (124a, 324) disposed at the front of a base (134a, 334). Workpieces (W9, W10) are moved two at a time between the rear of the base (134a, 334 ) and the two spindles (101a, 301) along a path which extends through a plane which contains the axes (C, J) of rotation of the spindles (101a, 301).

Abstract: A machine tool comprises a work table arranged for being displaced in at least one coordinate direction relative to a spindle stock. Longitudinal drive means arranged beneath the work table are covered on both sides of the work table by means of a cover composed of telescoping elements. One of the said elements is provided in stationary arrangement adjacent one side wall of a trough enclosing the cover.In order to prevent the chips from forming into balls in front of the overlapping elements, when the extreme end position of the work table is reached, at least one opening giving access to the trough is provided on the upside of the one element, at the edge facing the side wall.

Abstract: This invention pertains to a head stock assembly for a chucker and bar machine which includes a special bearing system comprising three forward bearings and two rearward bearings for providing five point contacts to the spindle for maintaining stiffness and rigidity and improved accuracy in machining. It also includes cooling fin means for dissipating the heat about the bearings which would normally build up in a headstock after long periods of operation. The heat dissipation reduces growth of the headstock and therefore improves accuracy. In addition, the headstock assembly has mounted directly thereon a spindle encoder, a brake disc, a collet closer mechanism, a balancing disc, as well as a low pressure means for preventing cutting fluids and dust and dirt from entering into the bearing mechanism.

Abstract: Apparatus for and method of clearing scrap from the opening of a workpiece in which a jet of fluid is directed over the opening, causing the scrap to be entrained in fluid streaming out of the opening to join the fluid jet. In a preferred embodiment of the invention, the fluid jet is pulsed in order to maximize its efficiency. In an alternative embodiment, a vacuum is used to collect the entrained scrap.

Abstract: A mechanism for lifting a wheel set, such as a railroad wheel set, is constructed for cooperation especially with wheel truing machines for lifting a wheel set into a machining position or out of the machining position. In order to facilitate the chip removal, the lifting mechanism is tiltably mounted in a chip removal pit. In its uplifting working position a cover of the lifting mechanism substantially closes the chip pit except for the wheel carriers. In the recessed position of the lifting mechanism the cover tilts along with the lifting mechanism thereby guiding any chips accumulated on the cover onto a chip removing conveyor in the pit. For this purpose the lifting mechanism has a movable frame hinged to a stationary frame so that the hinging axis extends outside of a lifting plane passing through the rotational axis of the wheel set.